Consulta: subjectFacets:"Modelling"
Registros recuperados: 152
Data/hora: 10/06/2024 03:47:13

Multiple model approach to modelling of Escherichia coli fed-batch cultivation extracellular production of bacterial phytase
Provedor de dados: Electronic Journal of Biotechnology
Autores: Roeva,Olympia; Pencheva,Tania; Tzonkov,Stoyan; Arndt,Michael; Hitzmann,Bernd; Kleist,Sofia; Miksch,Gerchard; Friehs,Karl; Flaschel,Erwin.
The paper presents the implementation of multiple model approach to modelling of Escherichia coli BL21(DE3)pPhyt109 fed-batch cultivation processes for an extracellular production of bacterial phytase. Due to the complex metabolic pathways of microorganisms, the accurate modelling of bioprocesses is rather difficult. Multiple model approach is an alternative concept which helps in modelling and control of complex processes. The main idea is the development of a model based on simple submodels for the purposes of further high quality process control. The presented simulations of E. coli fed-batch cultivation show how the process could be divided into different functional states and how the model parameters could be obtained easily using genetic algorithms....
Tipo: Journal article
Palavras-chave: Genetic algorithms; Modelling; Multiple model approach.
Ano: 2007
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582007000400012

POSSIBILITIES FOR ECOHYDROLOGICAL MONITORING IN NATURAL AND MANAGED ECOSYSTEMS IN SOUTHERN CHILE
Provedor de dados: Gayana Botánica
Autores: Peters,Jan; Wieme,Vanessa; Boeckx,Pascal; Samson,Roeland; Godoy,Roberto; Oyarzún,Carlos; Verhoest,Niko.
Ecohydrology investigates how hydrological processes affect plant growth and vice versa. As these mutual interactions are important in many ecosystems, ecohydrology has wide applicability. An important aspect of ecohydrological research is the assessment and prediction of the occurrence of plant species or vegetation types in relation to hydrological or hydrogeochemical habitat conditions. Several models have been developed (e.g. DEMNAT, ICHORS, ITORS, ITORS-VL). All of these models are data driven. Consequently a monitoring network has to be installed, possibly in addition to existing databases. These networks are ecosystem specific but the most widely monitored variables are: water table depth, electric conductivity of groundwater, soil moisture content...
Tipo: Journal article
Palavras-chave: Ecohydrology; Modelling; Vegetation; Hydrology; Decision support systems.
Ano: 2005
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-66432005000200007

Models and indicators for assessing conservation and fisheries-related effects of marine protected areas
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Pelletier, Dominique; Claudet, Joachim; Ferraris, J; Benedetti Cecchi, L; Garcia Charton, J.
Two kinds of approaches have been used for assessing conservation and fisheries-related effects of marine protected areas (MPAs): (i) statistical modelling based on field data and (ii) mathematical modelling quantifying the consequences of MPAs on the dynamics of populations, communities, and fisheries. Statistical models provide a diagnostic on the impact of MPAs on the ecosystem and resources; they are also needed for devising and assessing sampling designs for monitoring programs. Dynamic models enable exploration of the consequences of MPA designs and other management policies. We briefly review how each of these approaches has been implemented up to now in the literature and identify potential indicators of MPA effects that can be obtained from each...
Tipo: Text
Palavras-chave: Ecosystem conservation; Fisheries management; Modelling; Indicators; Marine Protected Areas.
Ano: 2008
URL: http://archimer.ifremer.fr/doc/2008/publication-4229.pdf

A single bio-energetics growth and reproduction model for the oyster Crassostrea gigas in six Atlantic ecosystems
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Alunno-bruscia, Marianne; Bourles, Yves; Maurer, Daniele; Robert, Stephane; Mazurie, Joseph; Gangnery, Aline; Goulletquer, Philippe; Pouvreau, Stephane.
Many studies based on bioenergetics growth models have investigated the effects of environmental factors on oyster (Crassostrea gigas) growth and physiology. However, most of these models are site-specific and cannot be applied to other culture sites without the re-estimation of parameters or re-formulation of some processes. We aimed to develop a generic growth model suitable for application in contrasting environments, with a constant set of parameters. We tested the oyster-DEB model (Bourlès et al. 2009) for the stimulation of C. gigas growth in different cohorts (spats and adults) at major shellfish culture sites in France, in several years: Arcachon (1993–1994); Marennes-Oléron (2007); Quiberon (1999, 2000, 2001); Rade de Brest (2008); Baie du...
Tipo: Text
Palavras-chave: DEB theory; Modelling; Bivalves; Crassostrea gigas; Phytoplankton; Temperature effect; Coastal environment.
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00043/15403/12762.pdf

How do microalgae perceive light in a high-rate pond? Towards more realistic Lagrangian experiments
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Demory, David; Combe, Charlotte; Hartmann, Philipp; Talec, Amelle; Pruvost, Eric; Hamouda, Raouf; Souille, Fabien; Lamarea, Pierre-olivier; Bristeau, Marie-odile; Sainte-marie, Jacques; Rabouille, Sophie; Mairet, Francis; Sciandra, Antoine; Bernard, Olivier.
Hydrodynamics in a high-rate production reactor for microalgae cultivation affects the light history perceived by cells. The interplay between cell movement and medium turbidity leads to a complex light pattern, whose forcing effects on photosynthesis and photoacclimation dynamics are nontrivial. Hydrodynamics of high density algal ponds mixed by a paddle wheel has been studied recently, although the focus has never been on describing its impact on photosynthetic growth efficiency. In this multidisciplinary downscaling study, we first reconstructed single cell trajectories in an open raceway using an original hydrodynamical model offering a powerful discretization of the Navier-Stokes equations tailored to systems with free surfaces. The trajectory of a...
Tipo: Text
Palavras-chave: Photosynthesis; Hydrodynamics; Modelling; Photoacclimation; Dunaliella salina; Non-photochemical quenching.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00445/55692/57352.pdf

Modelling larval dispersal and settlement of the reef-building polychaete Sabellaria alveolata: Role of hydroclimatic processes on the sustainability of biogenic reefs
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Ayata, Sakina-dorothee; Ellien, Celine; Dumas, Franck; Dubois, Stanislas; Thiebaut, Eric.
The honeycomb worm Sabellaria alveolata forms biogenic reefs which constitute diversity hotspots on tidal flats. The largest known reefs in Europe, located in the Bay of Mont-Saint-Michel (English Channel), are suffering increasing anthropogenic disturbances which raise the question of their sustainability. As the ability to recover depends partly on the recolonization of damaged reefs by larval supply, evaluating larval dispersal and the connectivity between distant reefs is a major challenge for their conservation. In the present study, we used a 3D biophysical model to simulate larval dispersal under realistic hydroclimatic conditions and estimate larval retention and exchanges among the two reefs of different sizes within the bay. The model takes into...
Tipo: Text
Palavras-chave: Bay of Mont Saint Michel; English Channel; Modelling; Larval settlement; Larval transport; Connectivity; Biogenic reefs; Sabellaria alveolata.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/publication-6841.pdf

Projecting changes in the distribution and productivity of living marine resources: A critical review of the suite of modeling approaches used in the large European project VECTORS
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Peck, Myron A.; Arvanitidis, Christos; Butenschon, Momme; Canu, Donata Melaku; Chatzinikolaou, Eva; Cucco, Andrea; Domenici, Paolo; Fernandes, Jose A.; Gasche, Loic; Huebert, Klaus B.; Hufnagl, Marc; Jones, Miranda C.; Kempf, Alexander; Keyl, Friedemann; Maar, Marie; Mahevas, Stephanie; Marchal, Paul; Nicolas, Delphine; Pinnegar, John K.; Rivot, Etienne; Rochette, Sebastien; Sell, Anne F.; Sinerchia, Matteo; Solidoro, Cosimo; Somerfield, Paul J.; Teal, Lorna R.; Travers-trolet, Morgane; Van De Wolfshaar, Karen E.
We review and compare four broad categories of spatially-explicit modelling approaches currently used to understand and project changes in the distribution and productivity of living marine resources including: 1) statistical species distribution models, 2) physiology-based, biophysical models of single life stages or the whole life cycle of species, 3) food web models, and 4) end-to-end models. Single pressures are rare and, in the future, models must be able to examine multiple factors affecting living marine resources such as interactions between: i) climate-driven changes in temperature regimes and acidification, ii) reductions in water quality due to eutrophication, iii) the introduction of alien invasive species, and/or iv) (over-)exploitation by...
Tipo: Text
Palavras-chave: Distribution; Modelling; Habitat; Resources; Man-induced effects.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00337/44845/44436.pdf

A moderate melting model for the Voring margin (Norway) based on structural observations and a thermo-kinematical modelling: Implication for the meaning of the lower crustal bodies
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Gernigon, Laurent; Lucazeau, Francis; Brigaud, Frederic; Ringenbach, Jean-claude; Planke, Sverre; Le Gall, Bernard.
High P-wave velocities (7.1-7.8 km/s) lower crustal bodies (LCBs) imaged along volcanic margins are commonly interpreted as plume and break-up-related thick mafic underplating. This interpretation is partly challenged in this paper based on new seismic observations and modelling of the outer Voring Basin (Norway). An exceptional strong amplitude reflection, the T Reflection, is particularly well defined below the North Gjallar Ridge (NGR) between 7 and 8 s TWT. The T Reflection is located near the volcanic lava flows emplaced during the NE Atlantic breakup (similar to 55-54 Ma ago) and coincides with the top of the LCB, forming a mid-crustal dome. Based on structural and temporal relationships, we show that the dome clearly influences the structural...
Tipo: Text
Palavras-chave: Mantle plume; Norwegian margin; Underplating; Breakup; Modelling; Rifting; Volcanic margins.
Ano: 2006
URL: http://archimer.ifremer.fr/doc/2006/publication-1042.pdf

Modélisation de l'affinage de l'huître Crassostrea gigas alimentée avec la diatomée Skeletonema costatum
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Meleder, Vona; Barille-boyer, Anne-laure; Baud, Jean-pierre; Barille, Laurent; Cognie, Bruno; Rosa, Philippe.
The traditional fattening of the oyster Crassostrea gigas in oyster ponds of the French Atlantic Coast is submitted to natural environmental fluctuations. In order to reduce the growth variability of the soft parts of the bivalve, an intensive fattening process was developed, where the conditions of temperature, particulate organic and inorganic matter (POM and PIM) are controlled. This process relies on the production of the diatom Skeletonema costatum, which is then distributed to the oysters at an average concentration of 4–5 mg POM·L–1. An ecophysiological model of the oyster C. gigas, which simulates the evolution of somatic and gonad–reserve compartments, was applied to these conditions in order to analyse the bivalve responses. Experimentation was...
Tipo: Text
Palavras-chave: Modélisation; Affinage; Ecophysiologie; Crassostrea gigas; Skeletonema costatum; Modelling; Oyster fattening; Ecophysiology; Crassostrea gigas; Skeletonema costatum.
Ano: 2001
URL: http://archimer.ifremer.fr/doc/00021/13248/10285.pdf

Ecologie bacterienne dans les bacs d'elevage larvaire de coquilles Saint-Jacques (Pecten maximus )
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Jacq, E; Moal, Jeanne; Samain, Jean-francois; Corre, S; Daniel, J; Nicolas, Jean-louis; Cochard, Jean-claude; Fera, P.
Larval rearings were performed with seawater either freshly pumped or after storage in a pond. Concerning bacterial populations these waters were characterized by a high diversity, little sized bacteria whose few of them (1%) were cultivable on Zobell medium. In the tanks, the bacterial ecosystem was modified by the presence of antibiotics, larvae and algae: the diversity was lowered, the cellular volume was increased by a factor 2 to 5, 100% bacteria were cultivable and chloramphenicol resistant, and their metabolism changed. Taxonomic screening showed no differences among the two waters neither at the beginning nor at the end of the rearings. However, depending on the water (stored or not) differences were identified for bacterial physiology and...
Tipo: Text
Palavras-chave: Marine aquaculture; Pond culture; Scallop culture; Ecology; Antibiotics; Organic matter; Grazing; Carbohydrates; Mathematical models; Modelling; Growth; Bacterial diseases; Biological production; Culture tanks; Larvae; Rearing.
Ano: 1992
URL: http://archimer.ifremer.fr/doc/1992/acte-914.pdf

Modelling growth and reproduction of the Pacific oyster Crassostrea gigas: Advances in the oyster-DEB model through application to a coastal pond
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Bourles, Yves; Alunno-bruscia, Marianne; Pouvreau, Stephane; Tollu, Guillaume; Leguay, Didier; Arnaud, Christophe; Goulletquer, Philippe; Kooijman, S.
A bio-energetic model, based on the DEB theory exists for the Pacific oyster Crassostrea gigas. Pouvreau et al. [Pouvreau, S., Bourles, Y., Lefebvre, S., Gangnery, A., Alunno-Bruscia, M., 2006. Application of a dynamic energy budget model to the Pacific oyster, C. gigas, reared under various environmental conditions. J. Sea Res. 56, 156–167.] successfully applied this model to oysters reared in three environments with no tide and low turbidity, using chlorophyll a concentration as food quantifier. However, the robustness of the oyster-DEB model needs to be validated in varying environments where different food quantifiers reflect the food available for oysters, as is the case in estuaries and most coastal ecosystems. We therefore tested the oyster-DEB...
Tipo: Text
Palavras-chave: Coastal Environment; Temperature effect; Food Quantifiers; Crassostrea gigas; Bivalves; Modelling; DEB theory.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/publication-6436.pdf

In-situ database toolbox for short-term dispersion model validation in macro-tidal seas, application for 2D-model
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Bailly Du Bois, P.; Dumas, Franck; Solier, L.; Voiseux, C.
Appropriate field data are required to check the reliability of hydrodynamic models simulating the dispersion of soluble substances in the marine environment. This study deals with the collection of physical measurements and soluble tracer data intended specifically for this kind of validation. The intensity of currents as well as the complexity of topography and tides around the Cap de La Hague in the centre of the English Channel make it one of the most difficult areas to represent in terms of hydrodynamics and dispersion. Controlled releases of tritium-in the form of HTO-are carried out in this area by the AREVA-NC plant, providing an excellent soluble tracer. A total of 14,493 measurements were acquired to track dispersion in the hours and days...
Tipo: Text
Palavras-chave: Modelling; Data collection; Tritium; Dispersion; Tidal dynamics; English Channel.
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00077/18775/16484.pdf

Modelisation numerique du flambage de panneaux sandwich raidis
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Batoz, J; Quesnel, T.
This paper presents a numerical method for the buckling analysis of stiffened sandwich panels for ship building with composite materials. The formulation of a multi-layered quadrilateral finite element of a plane shell including transverse shear effects is presented. Some classical tests allow the performance of this element to be evaluated for composite plates. Then an explanation is given for a method used for analyzing the buckling of panels.
Tipo: Text
Palavras-chave: Ship technology; Composite materials; Modelling; Mathematical models; Numerical analysis; Eléments finis; Plaque coque; Flambage; Structure sandwich; Matériau composite.
Ano: 1992
URL: http://archimer.ifremer.fr/doc/1992/acte-1074.pdf

Dynamique des matières en suspensions minérales des eaux de surface de la Manche observée par satellite et modélisée numériquement.
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Rivier, Aurelie.
Study of mineral suspended particulate matter (SPM) is essential to understand ecosystem dynamics. SPM influences light penetration which is closely related to primary production and carries pollutants and nutrients within the water masses. This work aims to study near-surface mineral SPM dynamics in the English Channel using two complementary methods: remote-sensing by satellites and numerical modelling. Firstly, MODIS and MERIS satellite images processed by the IFREMER semi-analytical algorithm and describing non-algal SPM, are analysed to build three statistical models which are able to estimate near-surface SPM using simple variables, e.g., tidal coefficient, significant wave height and mean chlorophyll-a concentration. Secondly, the three-dimensional...
Tipo: Text
Palavras-chave: Matière en suspension; Télédétection; Satellite; Modélisation; Manche; Sédiments; Turbidité; Marée; Houle; Suspended particulate matter; Satellite; Remote-sensing; Modelling; English Channel; Sediments; Turbidity; Tide; Wave.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00157/26783/24884.pdf

Experimental Analysis of the Influence of Hydrostatic Stress on the Behaviour of an Adhesive Using a Pressure Vessel
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Cognard, J. Y.; Creac'Hcadec, R.; Da Silva, L. F. M.; Teixeira, F. G.; Davies, Peter; Peleau, Michel.
The modelling of the non-linear behaviour of ductile adhesives requires a large experimental database in order to represent accurately the strains which are strongly dependent on the tensile-shear loading combination. Various pressure-dependent constitutive models can be found in the literature, but only a few experimental results are available, for instance, to represent accurately the initial yield surface taking into account the two stress invariants, hydrostatic stress, and von Mises equivalent stress. This paper presents the possibility of combining the use of tests on bulk specimens and tests on bonded assemblies, which strongly limit the influence of the edge effects, with a pressure vessel especially designed to study the influence of hydrostatic...
Tipo: Text
Palavras-chave: Adhesive testing; Finite element analysis; Hydrostatic stress; Modelling; Non-linear behaviour; Yield surface.
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00048/15917/13374.pdf

A modelling study of the thermohaline circulation of the Mediterranean Sea: Water formation and dispersal
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Haines, K; Wu, Pl.
A model of the whole Mediterranean sea at 0.25 degrees x 0.25 degrees resolution has been run for ten years with a mean seasonal cycle of forcing using NMC winds and a relaxation to NODC surface temperature and salinity. The winter season water formation and dispersal in the model thermocline has been studied using isopycnal diagnostics and potential vorticity as a water mass tracer. In the eastern basin Levantine Intermediate Water (LIW) is formed in the cyclonic Rhodes gyre and moves west in a continuous mass, accumulating and mixing in the centre of the Northern Ionian. The LIW spreading path is identified both from the high salinity and low potential vorticity values on the 28.8 isopycnal surface. Some LIW then spreads west and south towards Sicily,...
Tipo: Text
Palavras-chave: PRIMO-O; Circulation thermohaline; Eau levantine intermédiaire; Formation; Modélisation; PRIMO-O; Thermohaline circulation; Levantine Intermediate Water; Water formation; Modelling.
Ano: 1995
URL: http://archimer.ifremer.fr/doc/00323/43387/43113.pdf

Processus Gravitaires et Évaluation de la Stabilité des Pentes : Approches Géologique et Géotechnique. Application à la marge algérienne et à l'effondrement de l'aéroport de Nice en 1979
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Dan, Gabriela.
The present work consists of two areas of interest: the Algerian margin and the area affected by the 1979 Nice slide.  The first scientific survey, MARADJA, took place in 2003 in order to characterize the Algerian margin from a morpho-sedimentary point of view and to map the presence of mass-wasting deposits. Based on other two scientific surveys, PRISMA and MARADJA 2, the mechanical and physical properties of the Algerian sediment were defined. The geotechnical properties were used to identify the triggering mechanisms of the observed mass-wasting deposits and to assess the present-day slope stability. The main results are:  • The sedimentary processes are clearly influenced by the morphology of the margin, which is controlled by the tectonics. The...
Tipo: Text
Palavras-chave: Liquefaction; Slope stability; Nice 1979; Algeria; Modelling; Numerical; Modélisation; Liquéfaction; Stabilité de pente; Processus gravitaires; Nice 1979; Algérie.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/these-3881.pdf

Modélisation bioénergétique de la croissance, du développement et de la reproduction d'un petit pélagique : l'anchois du golfe de Gascogne
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Pecquerie, Laure.
Understanding the recruitment variability of fish populations is a major challenge in fishery sciences. In the present work, we explore a new approach to study the potential factors that determine this recruitment in the context of biophysical modelling. The adult spawning pattern might influence the survival of the larvae as it determines the environmental conditions they experience during this critical period. We apply our study to the Bay of Biscay anchovy Engraulis encrasicolus, which is a multiple-batch spawner.  The objective of the study is to understand the effect of the environmental conditions experienced by an individual i) on the energy available for reproduction and ii) on the temporal distribution of the spawning events and its consequences...
Tipo: Text
Palavras-chave: Inter individual variability; Environmental scenarios; Link fish metabolism   otolith; Larval survival; Spawning windows; Engraulis encrasicolus; Dynamic Energy Budget theory; Life cycle; Bioenergetic; Modelling; Variabilité inter individuelle; Scénarios environnementaux; Lien métabolisme   otolithe; Survie larvaire; Fenêtres de ponte; Engraulis encrasicolus; Energy Budget; Théorie Dynamic; Cycle de vie; Bioénergétique; Modélisation.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/these-3505.pdf

Managing the Agri-Food System of Watersheds to Combat Coastal Eutrophication: A Land-to-Sea Modelling Approach to the French Coastal English Channel
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Garnier, Josette; Riou, Philippe; Le Gendre, Romain; Ramarson, Antsiva; Billen, Gilles; Cugier, Philippe; Schapira, Mathilde; Théry, Sylvain; Thieu, Vincent; Ménesguen, Alain.
The continental coastal waters of the Eastern Channel, from Normandy to Hauts-de-France, are subject to the major influence of unbalanced nutrient inputs from inflowing rivers. Several episodes of harmful algal blooms (HABs) compromising fishing and shellfish farming activities have been observed at the coast. For a better understanding of how the land-to-sea aquatic continuum functions, the GRAFS-RIVERSTRAHLER river biogeochemical model was implemented to cover the watersheds of 11 rivers flowing into this area (including the Seine) and chained with the ecological marine ECO-MARS3D model, applied to the French Northern coastal zone. Human activities strongly impact on the functioning of coastal ecosystems. Specifically, for these fertile soils of Northern...
Tipo: Text
Palavras-chave: Toxic microalgae; Pseudo-nitzschia spp.; River basins; Nutrient flows; Scenarios; Coastal zone ecosystem; Modelling.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00589/70076/68049.pdf

Modelling the non Fickian water absorption in polyamide 6
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Arhant, Mael; Le Gac, Pierre-yves; Le Gall, Maelenn; Burtin, Christian; Briancon, Christophe; Davies, Peter.
This paper investigates the water absorption of polyamide 6. The high amount of absorbed water in the polymer and the large resulting decrease in the glass transition temperature (Tg) leads to a non Fickian water diffusion when samples are immersed, which is a significant difficulty when trying to model the water profile in thick specimens. The aim of this study is to be able to model this particular behaviour based on physical considerations. First, it is shown that the non Fickian water diffusion is caused by an increase in the diffusivity during water absorption. Two cases are then identified; one below Tg where the diffusivity is described using an Arrhenius law and one above Tg based on the free volume theory. Then, these two laws are implemented in a...
Tipo: Text
Palavras-chave: Water absorption; Free volume; Polyamide 6; Sea water; Modelling.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00350/46158/45856.pdf

Hydrologie du Grand Etang de Miquelon. Estimation des flux et renouvellements
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Le Moine, Olivier; Geairon, Philippe; Robert, Stephane; Coudray, Sylvain; Fiandrino, Annie; Goraguer, Herle; Goulletquer, Philippe.
This study aims to assess the hydrological fluxes between the ‘Grand Etang’ of Miquelon and the oceanic part. Bathymetric surveys and Doppler current meter data acquisitions were carried out from August 14th, to November 5th, 2014 and from April 1st, to end of July 2015 to allow the following estimates : Total area (227 Ha) and characteristics volumes (total : 6,7 106 m3; oscillating 2,8 106 m3 (40 %); half-tide 5,2 106 m3) Velocity Index of channel to evaluate the average current speed at cross-section channel Fluxes, on flood and ebb tide respectively : Instantaneous flow: maxima at 94,2 et 65 m3/s mean 37.2 et 24.5 m3/s. in 2014 and maxima 85,03 et 73,62 m3/s mean 26,22 et 28,20 m3/s in 2015. Circulating fluxes by tide : maxima 1,06 and 1,09 106 m3,...
Tipo: Text
Palavras-chave: Flux hydrologiques; Courantométrie; Bathymétrie; Grand Etang Miquelon; Modélisation; Hydrological fluxes; Current meter data acquisition; Bathymetry; Grand Etang Miquelon; Modelling.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00332/44325/43904.pdf

Active faulting and deep crustal structure of the Eastern Sicily Margin
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Dellong, David.
In the Ionian Sea (central Mediterranean) the slow convergence between Africa and Eurasia results in the formation of a narrow subduction zone. The nature of the crust of the subducting plate remains debated and could represent the last remnants of the Neo-Tethys ocean. The origin of the Ionian basin is also under discussion, especially concerning the rifting mechanisms as the Malta Escarpment could represent a remnant of this opening. This subduction retreats toward the south-east (motion occurring since the last 35 Ma) but is confined to the narrow Ionian basin. A major lateral slab tear fault is required to accommodate the slab rollback.This fault is thought to propagate along the eastern Sicily margin but its precise location remains controversial.This...
Tipo: Text
Palavras-chave: Méditerranée; Ionien; Calabre; Géodynamique; Marge; Faille de déchirure lithosphérique; Sismicité; Sismique; Grand-angle; Bathymétrie; Gravimétrie; Modélisation; Mediterranean; Ionian; Calabria; Geodynamic; Subduction; Margin; STEP fault; Wide-angle seismic; Seismicity; Bathymetry; Gravity; Modelling.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00499/61026/64430.pdf

Etude et modélisation des mécanismes impliqués dans la croissance de l'huître perlière, Pinctada margaritifera, au sein de l'écosystème conchylicole du lagon de l'atoll de Takapoto (Polynésie Française)
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Pouvreau, Stephane.
L'huître perlière, Pinctada margaritifera (Linné, 1758) var. cumingi (Reeve), productrice de perles noires, fait l' objet d'une aquaculture florissante en Polynésie Française. Afin de pérenniser cette activité, un programme de recherche (le PGRN) a été lancé, en 1990, sur l' atoll de Takapoto. L' un des thèmes de ce programme réside dans l'étude de la capacité trophique d'un lagon soumis à une activité de perliculture. A cet égard, un modèle déterministe expliquant la croissance et la reproduction de P. margaritifera à partir des paramètres du milieu (notamment la nourriture disponible) a été mis au point. La construction de ce modèle a impliqué : ( 1) l'analyse de l'hydrobiologie du lagon; (2) l'étude de la physiologie de P. margaritifera; (3) le sui vi...
Tipo: Text
Palavras-chave: Bivalves; Huîtres perlières; Pinctada margaritifera; Physiologie; Croissance; Reproduction; Hydrobiologie; Atoll; Lagon; Écosystème; Réseau trophique; Modélisation; Capacité trophique; Polynésie française; Bivalves; Pearl oyster; Pinctada ma rgaritifera; Physiology; Growth; Reproduction; Hydrobiology; Atoll; Lagoon; Ecosystem; Trophic web; Modelling; Carrying capacity; French Polynesia.
Ano: 1999
URL: http://archimer.ifremer.fr/doc/00034/14558/11856.pdf

3D modelling of seasonal evolution of Loire and Gironde plumes on Biscay Bay continental shelf
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Lazure, Pascal; Jegou, Anne-marie.
A 3D model of the Atlantic shelf has been developed and applied to study shelf dynamics and evolution of hydrology. The model takes the combined effects of tide, wind, river discharges and surface heat flux into account. Time scales vary from 1 day to several years. Following a brief description of the model and forcing variables, the behaviour of the Loire and Gironde plumes is described, first for winter and spring, then over a period of several years, under realistic forcing. The results show that plume evolution depends on the high Variability of river runoff and winds. Model simulations performed over 7 years (1990 to 1996) have highlighted several features of these plumes: 1) In early winter and periods of high river runoff, plumes usually spread...
Tipo: Text
Palavras-chave: Panache; Modélisation; Dynamique du plateau continental; Golfe de Gascogne; River plume; Modelling; Shelf dynamics; Bay of Biscay.
Ano: 1998
URL: http://archimer.ifremer.fr/doc/1998/publication-847.pdf

Applying Dynamic Energy Budget (DEB) theory to simulate growth and bio-energetics of blue mussels under low seston conditions
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Rosland, R; Strand, O; Alunno-bruscia, Marianne; Bacher, Cedric; Strohmeier, T.
A Dynamic Energy Budget (DEB) model for simulation of growth and bioenergetics of blue mussels (Mytilus edulis) has been tested in three low seston sites in southern Norway. The observations comprise four datasets from laboratory experiments (physiological and biometrical mussel data) and three datasets from in situ growth experiments (biometrical mussel data). Additional in situ data from commercial farms in southern Norway were used for estimation of  biometricalrelationships in the mussels. Three DEB parameters (shape coefficient, half saturation coefficient, and somatic maintenance rate coefficient) were estimated from experimental data, and the estimated parameters were complemented with parameter values from literature to establish a basic parameter...
Tipo: Text
Palavras-chave: Low seston; Modelling; DEB theory; Mytilus edulis; Mussel culture.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/publication-6266.pdf

Méthodologie pour une simulation des transformations granulométriques de sables de la zone d'avant-côte
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Barusseau, Jp; Diouf, Mb; De La Bardonnie, M; El Ghandour, N.
The grain-size of mature coastal sands changes rapidly in response to the variation of the energy regime which provokes either erosion or deposition of fractions of the textural assemblage. Whatever the dynamic conditions, questions of paramount importance such as the size of grain populations transported simultaneously, the most common size of the grains in movement and the grain-size range of the sediment fraction involved ape still poorly understood. The present paper deals with an attempt to describe this fraction without any consideration of the processes responsible for the observed changes. A major problem results from the fact that the distribution of the mobilized fraction cannot be known and described by direct comparison between the initial and...
Tipo: Text
Palavras-chave: Granulométrie; Fraction mobile; Modélisation; Simulation; Grain-size; Mobile fraction; Modelling; Simulation.
Ano: 1999
URL: http://archimer.ifremer.fr/doc/00325/43619/43919.pdf

Ecosystème estuarien et système économique régional : faisabilité d’une intégration par modélisation Input-Output. Application au cas de l'habitat halieutique dans l’estuaire de la Seine
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Cordier, Mateo.
Mateo Cordier’s PhD addresses the interactions between the economic system and the ecosystem of the Seine estuary, an ecosystem deeply modified by human activities. His work aims at a holistic perspective and targets, among others, the destruction of nursery habitats and the subsequent impact on fish stocks in the Seine estuary. The hybrid input-output model developed in the PhD manuscript brings a quantitative insight on stakeholders and natural resources impacted by the modifications of ecosystem services (modifications caused by economic activities, political measures or restoration programs).
Tipo: Text
Palavras-chave: Input-output; Services écosystémiques; Processus participatifs; Gestion intégrée des zones côtières; Science Post-Normale; Aide à la décision; Économico-écologique; Modélisation; Prospective; Input-Output; Ecosystem services; Participative process; Integrated coastal zone management; Post-Normal Science; Decision-support; Ecological-economics; Modelling; Foresight.
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00048/15926/13351.pdf

Sur l'hydrodynamique de la Baie de Seine. Resultats d''observations et de modelisations
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Leprovost, C; Fornerino, M; Villaret, C.
Study of Seine bay hydrodynamics can't be separated from the Channel and continental shelf. The authors' modellings are aimed at the study of this global ladder and the insertion of coastal areas such as the Seine Bay in this context. Two 2-D models are used. One covers only the Channel, and the other from Pas-de-Calais to continental shelf limits including Celtic sea, Channel and southern North Sea. The results are comparated with long time current observations.
Tipo: Text
Palavras-chave: Current data; Mathematical models; Modelling; Tidal currents; Current prediction; Water circulation; Hydrodynamics.
Ano: 1985
URL: http://archimer.ifremer.fr/doc/1985/acte-1259.pdf

Modélisation des cycles de l'azote et du phosphore dans les sédiments d'une lagune soumise à une exploitation conchylicole
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Chapelle, Annie; Mesnage, Valérie; Mazouni, Nabila; Deslous-paoli, Jean-marc; Picot, Bernadette.
A simulation of nitrogen and phosphorus exchanges for the sediment-water interface is presented, The aim of the sttudy is to understand the dynamic behaviour of an eutrophie coastal lagoon (Thau, France), ln situ experiments were performed to estimate the different pools of nitrogen and phosphorus in the water column and in the sediment. The diffusive fluxes between them were also estimated. A numerical mode1, simulating nitrogen and phosphorus cycles, was developed and calibrated with data recorded .at two seasons (winter and summer). This study leads to the conclusion that is necessary to know the different pools of nitrogen and phosphorus in order to estimate which fraction is bioavailable and the rate of nutrient exchange between sediment and water. It...
Tipo: Text
Palavras-chave: Modèle; Phosphore; Azote; Sédiment; Ecosystème conchylicole; Modelling; Phosphorus; Nitrogen; Sediment; Shellfish ecosystem.
Ano: 1994
URL: http://archimer.ifremer.fr/doc/00039/15026/12360.pdf

Phytoplankton competition and coexistence: Intrinsic ecosystem dynamics and impact of vertical mixing
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Perruche, Coralie; Riviere, Pascal; Pondaven, Philippe; Carton, Xavier.
This paper aims at studying analytically the functioning of a very simple ecosystem model with two phytoplankton species. First, using the dynamical system theory, we determine its nonlinear equilibria, their stability and characteristic timescales with a focus on phytoplankton competition. Particular attention is paid to the model sensitivity to parameter change. Then, the influence of vertical mixing and sinking of detritus on the vertically-distributed ecosystem model is investigated. The analytical results reveal a high diversity of ecosystem structures with fixed points and limit cycles that are mainly sensitive to variations of light intensity and total amount of nitrogen matter. The sensitivity to other parameters such as remineralisation, growth...
Tipo: Text
Palavras-chave: Water mixing; Dynamical system; Phytoplankton; Competition; Ecosystem; Modelling.
Ano: 2010
URL: http://archimer.ifremer.fr/doc/2009/publication-7334.pdf

Simulation des trajectoires de matière organique dans le Pertuis Breton. Couplage de l'hydrodynamisme et d'un modèle écophysiologique de M. edulis
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Pallas Sanz, Enric.
The "Pertuis Breton" is a macrotidal estuary with an important mollusc exploitation of the inter-tidal zones. The main cultivated specie is M.edulis. In 1991, 250 long lines have been immersed in the centre of the bay. It will be able to extend the concession on the basis of the studies results about the trophy capacity of the "Pertuis Breton". Two deterministic models have been developed for to determining the geographical origin of the matter organic sources for the long line mussels culture, and the destine of this matter in the culture park: a) a model of trajectories of the organic matter particles, b) a coupled model of the hydrodynamic conditions and a ecophysiological model of the mussel growth. The result's simulations of the trajectories model...
Tipo: Text
Palavras-chave: M. edulis; Potentialité mytilicole; Déplétion; Trajectoires; Modélisation; M. edulis; Trophy capacity; Depletion; Trajectories; Modelling.
Ano: 2001
URL: http://archimer.ifremer.fr/doc/00449/56098/57634.pdf

Analysis of the Influence of Hydrostatic Stress on the Behaviour of an Adhesive in a Bonded Assembly
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Cognard, J. Y.; Creac'Hcadec, R.; Maurice, J.; Davies, Peter; Peleau, Michel; Da Silva, L. F. M.
Generally, adhesives are viscoelastic-plastic materials, for which the development of viscosity and plasticity varies depending on the type of adhesive and the stress state. Various models exist to represent the yield surface, or the so-called elastic limit, taking into account the two stress invariants, hydrostatic stress and von Mises equivalent stress. Moreover, to develop precise pressure-dependent constitutive models, it is necessary to have a large experimental database in order to accurately represent the adhesive strains which are strongly dependent on the tensile-shear loading combination. Under quasi-static loadings, for a given strain rate range viscous effects can be neglected, but only a few experimental results are available to model the...
Tipo: Text
Palavras-chave: Adhesive testing; Non-linear behaviour; Modelling; Hydrostatic stress; Finite element analysis.
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00018/12903/10396.pdf

Modélisation morphodynamique d'une embouchure tidale : Application aux Passes d'entrée du Bassin d'Arcachon
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Cayocca, Florence.
The Arcachon tidal inlet exhibits a particularly active morphology due to strong tidal currents and rough wave conditions. During the past 300 years, maximum and minimum extents of the Cap Ferret sand spit have resulted in a difference of 8 km while two channels have alternatively allowed circulation between the lagoon and the ocean.   A bidimensional horizontal morphodynarnic model was developed in order to simulate the system evolution under tidal forcing alone or under combined tide and wave action. Modelling at a scale of decades requires the definition of mean annual wave and tide conditions which are representative with respect to sediment transport. Medium term results thus give general trends of evolution. Driven by these average conditions and...
Tipo: Text
Palavras-chave: Littoral drift; Sediment transport; Tide; Waves; Arcachon lagoon; Tidal inlet; Modelling; Morphodynamic; Dérive littorale; Transport sédimentaire; Marée; Houle; Bassin d'Arcachon; Modèle; Morphodynamique.
Ano: 1996
URL: http://archimer.ifremer.fr/doc/1996/these-4520.pdf

Eutrophication modelling chain for improved management strategies to prevent algal blooms in the Bay of Seine
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Passy, Paul; Le Gendre, Romain; Garnier, Josette; Cugier, Philippe; Callens, Julie; Paris, Francois; Billen, Gilles; Riou, Philippe; Romero, Estela.
Eutrophication of the Seine estuary and the Bay of the Seine is a crucial environmental issue for the management of ecosystems and economic activities related to fisheries and tourism. A large quantity of nutrients, especially nitrogen, is brought to the coastal zone by the Seine River, the main input of that area, but also by smaller rivers along the Normandy coast. This large delivery of nitrogen leads to an imbalance between nitrogen (N), phosphorus (P) and silica (Si), which affects the growth of planktonic organisms and can exacerbate the occurrence of harmful algal blooms (HABs). These events can be damaging for shellfish fisheries, an important economic resource for the region. The study describes a new modelling chain coupling a riverine and a...
Tipo: Text
Palavras-chave: Eutrophication; Harmful algal blooms; Nutrient load; Modelling; Water quality; Seine.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00300/41103/41542.pdf

Études des interactions entre la bactérie bioprotectrice Lactococcus piscium et Brochothrix thermosphacta et Listeria monocytogenes dans la crevette tropicale
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Fall, Papa-abdoulaye.
The bioprotective potential of Lactococcus piscium CNCM I-4031 towards a specific spoilage organism, Brochothrix thermosphacta, was studied on tropical cooked peeled shrimp packed under modified atmosphere. In co-culture, the growth of this spoilage bacterium was inhibited by 4 log ufc/g by L. piscium and the sensory quality of the product was improved during 31 days. The inhibition could not be attributed to lactic acid or nutritional competition for amino acids. The growth modelling of L. piscium and B. thermosphacta was performed in different conditions of temperature, pH and NaCl concentrations. The optimal growth values of these two bacteria are quite similar, however L. piscium seemed to be more psychrotolerant than B. thermosphacta but twice less...
Tipo: Text
Palavras-chave: Biopreservation; Inhibition; Modélisation; Lactococcus piscium; Flore d’altération; Analyse sensorielle; Produits de la mer; Co-cultures; Biopreservation; Inhibition; Modelling; Lactococcus piscium; Spoilage microflora; Sensory analysis; Seafood products; Co-cultures.
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00050/16164/13649.pdf

Modélisation du transport particulaire dans le Golfe du Lion en vue d'une application au devenir des traceurs radioactifs issus du Rhône
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Dufois, Francois.
Among the contaminants introduced into the environment, the artificial radionuclides appear particularly important to take into account because of their chemical toxicity and/or of their radiotoxicity. Some radionuclides present a high affinity with particles so that the study of the sediment dynamics is a useful preliminary to the study of their dispersion on the open sea. This thesis is focused on the fate of sediments in the Gulf of Lions (NW Mediterranean) and in particular on the impact of the Rhone River, which is the main source of particulate matter in the Gulf of Lions. In order to study the sediment transport mechanisms on various space and time scales, this thesis is based on mathematical modelling. The hydro-sedimentary model set up in the Gulf...
Tipo: Text
Palavras-chave: Waves; MARS 3D; Hydrodynamic; Radionuclides; Modelling; Sediment; Rhône prodelta; Gulf of Lions; Vagues; MARS 3D; Hydrodynamique; Radioéléments; Modélisation; Sédiment; Prodelta du Rhône; Golfe du Lion.
Ano: 2008
URL: http://archimer.ifremer.fr/doc/2008/these-6308.pdf

In modelling effects of global warming, invalid assumptions lead to unrealistic projections
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Lefevre, Sjannie; Mckenzie, David J.; Nilsson, Goeran E.
Tipo: Text
Palavras-chave: Climate change; Fish; Growth; Metabolism; Modelling; Oxygen uptake; Scaling; Warming.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00426/53762/54697.pdf

Assessment of the quantities of herbicides and nutrients brought down by the river Charente to the coast and modelling of the dispersion of atrazine in the Marennes-Oleron bay
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Munaron, Dominique; Dubernet, Jf; Delmas, F; Stanisiere, Jean-yves; Scribe, P.
Our study aims at making progress the estimate of herbicide and nutrient inputs to the Marennes-Oleron bay which could influence summer oysters mortalities, and to bring, a better understanding of the impact on coastal ecosystems by modelling the dynamics of these compounds in the shellfish-farming area. The development of a strategy adapted to the river Charente and its estuary reveals that agricultural activity on the watershed area is omnipresent, as well on the level of the nitrogen as on the one of herbicides contributions. It is thus necessary to specify Charente fluxes, which is the main tributary of the Marennes-Oleron bay, in order to better characterize its impact on shell fish-farming activity. Hydrodynamic modelling will constitute an...
Tipo: Text
Palavras-chave: Marennes Oleron bay; River Charente; Modelling; Fluxes; Nutrients; Herbicides.
Ano: 2006
URL: http://archimer.ifremer.fr/doc/2006/publication-3612.pdf

Typology of individual growth in sea bass (Dicentrarchus labrax)
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Gardeur, J; Lemarie, Gilles; Coves, Denis; Boujard, Thierry.
The individual growth variability of passive integrated transponder tagged sea bass was studied using data sets from two different experiments. In experiment 1 (n = 485), fish submitted to different photoperiod regimes were held in fourteen groups of individual weight of 88 ± 13 g (mean ± SD). In experiment 2 (n = 748, initial weight 243 ± 30 g) fish were held in fifteen groups and had either free or restricted access to diets with three lipid levels. After adjustment for treatment and tank effects, individual growth curves were analysed using multivariate analysis (principal component analysis and clustering) and were modelled using the summary statistics technique. Different growth profiles where characterized. All of them appeared to be curvilinear....
Tipo: Text
Palavras-chave: Variability; Typology; Sea bass; Modelling; Growth curves; Variabilité; Typologie; Bar; Modélisation; Courbes de croissance.
Ano: 2001
URL: http://archimer.ifremer.fr/doc/2001/publication-548.pdf

Caractérisation des composantes hydrodynamiques d'une lagune mésotidale, le Bassin d'Arcachon.
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Plus, Martin; Maurer, Daniele; Stanisiere, Jean-yves; Dumas, Franck.
Introduction and objectives of the study: Understanding the operation modes of the coastline systems requires the study of the hydrodynamics responsible for transporting the whole of the chemical and biological elements of which they are composed. The idea of maintaining a close connexion between the physics, biology, geology and chemistry of the oceans is not new, and was for that matter the subject of a note in the first report of the International Council for the Study of the Oceans (ICSS) in 1902 (Sverdrup et al., 1954):  " it was seen from the beginning that the study of the physical conditions, of the chemical nature of the ocean waters, of the currents, etc., was of the greatest importance for the investigation of the problems connected with life,...
Tipo: Text
Palavras-chave: France; Atlantic north east; Arcachon basin; Modelling; Measuring; Current; Hydrodynamic.
Ano: 2006
URL: http://archimer.ifremer.fr/doc/2006/rapport-2352.pdf

The effect of catch weight on trawl behaviour
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Priour, Daniel.
Measurements at sea during fishing trials on bottom trawl, have revealed that the geometry of the trawl is affected by the catch. A series of 27 hauls of around 3h have been carried out during the EFFICHALUT project. This project aimed to find out improvements on the fishing gear in order to reduce the energy consumption. For this project numerous sensors have been used, for bridles tension, doors spread, vertical opening, doors attitude. The measurements show quite clearly that the doors spread decreases and the bridles tension increases along most of the hauls. The doors spread decreases by 1.35m per hour, with a standard deviation of 1.98m/h when the top bridle tension increases of 47kg/h, with a standard deviation of 59kg/h. The mean catch per haul is...
Tipo: Text
Palavras-chave: Trawl; Data; Modelling; Doors spread; Bridle tension; Catch weight.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00186/29761/28208.pdf

The collapse and recovery potential of carbon sequestration by baleen whales in the Southern Ocean
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Durfort, Anaelle; Mariani, Gael; Troussellier, Marc; Tulloch, Vivitskaia; Mouillot, David.
Limiting climate warming below 2°C requires both reducing anthropic greenhouse gas emissions and sequestering more atmospheric carbon. Natural Climate Solutions (NCS) rely on the ability of ecosystems to capture and store carbon. Despite the important role of marine megafauna on the ocean carbon cycle, its potential as a NCS has not yet been explored. Here, we quantify the amount of carbon potentially sequestered by five baleen whale species across the Southern Hemisphere between 1890 and 2100 through both the sinking of carcasses after natural death and the fertilisation of phytoplankton by nutrients in faeces. At their pre-exploitation abundances, the five whales could sequester 10.6 106 tonnes of carbon per year (tC.yr-1) but this natural carbon sink...
Tipo: Text
Palavras-chave: Natural Climate Solutions; Climate change; Population dynamics; Modelling; Krill.
Ano: 2021
URL: https://archimer.ifremer.fr/doc/00682/79434/82038.pdf

Adaptative responses of E-coli to marine environmental stresses. a modelling approach based on viability and dormancy concepts
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Martin, Y; Troussellier, Marc; Bonnefont, Jl.
In an attempt to synthesize conceptual and experimental information on the behaviour of enteric bacteria in seawater, a mathematical model has been developed. This model is based on changes in intracellular metabolisable components depending an physiological responses of the cell when subjected to nutrient starvation, salinity stress and solar radiation. Following a strategy which takes into account short- and mid-term physiological adaptation and reversal processes, the cells can develop in different states: culturable (B-1), viable and definitively nonculturable (B-2), and reversibly dormant (B-3) cells. Model parameters were deduced either from original microcosm experiments, from literature data or calibration procedures. Validation of the model was...
Tipo: Text
Palavras-chave: Escherichia coli; Eau de mer; Stress; États cellulaires; Modélisation; Escherichia coli; Seawater; Stress; Cellular states; Modelling.
Ano: 1998
URL: http://archimer.ifremer.fr/doc/00325/43646/43224.pdf

Environmental and behavioural factors affecting activity in the intertidal gastropod Hydrobia ulvae
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Orvain, Francis; Sauriau, Pierre-guy.
Laboratory microcosms were used to investigate the mud snail Hydrobia ulvac (Pennant) bioturbation activities and behavioural changes in response to snail density, algal food, sediment moisture content, light regime and water cover conditions. Density-dependent kinetics of bioturbated muddy areas were described by von Bertalanffy equations, which provided reliable estimates of mud surface covering rates by snail tracks (m(2) h(-1) snail(-1)), Snails need a wet habitat to be active either covered by seawater or by moving in fluid layers for low-tide conditions. Light and microphytobenthic biomass, which are less potent to affect snail activity, are positively interrelated to increase covering rates in the tested chl a concentrations within the range of 1 -...
Tipo: Text
Palavras-chave: Modelling; Intertidal mudflat; Hydrobia ulvae; Environmental factors; Bioturbation; Behaviour.
Ano: 2002
URL: http://archimer.ifremer.fr/doc/2002/publication-3775.pdf

Pattern formation in models of plankton dynamics. A synthesis
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Malchow, H; Petrovskii, S; Medvinsky, A.
The history of modelling plankton dynamics is already quite long and has been initiated by fishery science in the early 20th century. The main aim of modelling population dynamics is to improve the understanding of the functioning of food chains and webs and their dependence on internal and external conditions. Hence, mathematical models of biological population dynamics have not only to account for growth and interactions but also for spatial processes like random or directed and joint or relative motion of species as well as the variability of the environment. Early attempts began with physicochemical diffusion, exponential growth and Lotka-Volterra type interactions. These approaches have been continuously refined to more realistic descriptions of the...
Tipo: Text
Palavras-chave: Modélisation; Schémas de formation; Agrégation du plancton; Auto-organisation; Modelling; Pattern formation; Plankton patchiness; Self-organization.
Ano: 2001
URL: http://archimer.ifremer.fr/doc/00322/43344/42882.pdf

Numerical optimisation of trawls design to improve their energy efficiency
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Priour, Daniel.
Trawls energy efficiency is greatly affected by the drag, as well as by the swept area regarding pelagic trawls and by the swept width for bottom ones. The drag results in an increase of the energy consumption and the sweeping influences the catch. In order to reduce the drag per swept area (or width) a numerical tool dedicated to the automatic optimisation of the trawl design has been developed. Based on a finite element method model for flexible netting structures, the tool modifies step by step a reference design. For each step the best-modified design, in terms of drag per swept area (or width), is kept. Such a methodology was used in two cases: which show a 43% increase in energy efficiency regarding the pelagic trawl case and 27% for the bottom trawl...
Tipo: Text
Palavras-chave: Swept width; Swept area; Drag; Fuel consumption; Optimisation; Modelling; Trawl; Fishing gears.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/publication-6583.pdf

Experimental testing and modelling of an industrial insulated pipeline for deep sea application
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Bouchonneau, Nadege; Sauvant-moynot, Valerie; Choqueuse, Dominique; Grosjean, Francois; Poncet, Emmanuel; Perreux, Dominique.
Ultra-deep water (up to 3000 in) is one of the next frontiers for oil offshore exploitation. It requires the use of conduits having to resist in the long run (durability about 25 years) the mechanical and environmental requests. One of the key points is the thermal insulation of the structure to avoid the formation of hydrates and paraffin plugs inside of the steel pipe. Over the past 10 years, many studies were performed to better understand the behaviour of the syntactic foams used as thermal insulation of pipes for deepwater production, but few tests were run on industrial prototypes to reach the actual thermal properties of the systems. This paper presents the numerical and experimental characterizations of an industrial multilayered insulated pipeline...
Tipo: Text
Palavras-chave: Layered structure; Subsea; Thermal properties; Modelling; Syntactic foam.
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00011/12248/9032.pdf

Fonctionnement des marais maritimes atlantiques: échanges d'énergie et effets des flux aquacoles diffus
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Bel Hassen, Malika.
French estuaries, from the Atlantic coast to the English channel, have been characterized by a poor phytoplankton biomass. The turbidity has always been considered as the limiting factor for phytoplankton. Estuarine ecosystems are situated at the boundary between the land and the sea. Consequently, they are subject to an enrichment by nutrient loadings from upland ecosystems. Although it has been demonstrated that a part of the nutrient loadings support an important benthic production. The part, which escapes to the estuarine benthic and planktonic food web and is exported to adjacent estuarine ecosystems, still remains undetermined. Quantifying the nu trient and particulate matter exchange between a macrotidal Bay, the Fier d'Ars, and the adjacent ocean...
Tipo: Text
Palavras-chave: Aquaculture; Exportation; Matière dissoute; Fiers d'Ars; Systèmes d'Information Géographique; Importation; Usages; Lumière; Micorphytobenthos; Modélisation; Nutriments; Matière organique; Matière particulaire; Phytoplancton; Sédimentation; Aquaculture; Export; Dissolved matter; Fier d'Ars Bay; Geographic Information Systems; Import; Land use; Light; Microphytobenthos; Modelling; Nutrients; Organic matter; Particulate matter; Phytoplankton; Sedimentation.
Ano: 2000
URL: http://archimer.ifremer.fr/doc/00450/56185/57738.pdf

Theory of turbid microalgae cultures.
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Martinez, Carlos; Mairet, Francis; Bernard, Olivier.
Microalgae can be cultivated in closed or open photobioreactors (PBR). In these systems, light rapidly decreases as it passes through the culture due to the turbidity of the medium. Thus, microalgae experiment different light intensities depending on their position in the medium. In this paper, we study theoretically how the growth rate of microalgae is affected by different factors; incident light intensity, form of the PBR, microalgae population density, turbidity of non-microalgae components, and light path-length of the reactor. We show that for different types of PBR the average growth rate is completely determined by the incident light intensity and the optical depth. In the case of vertical cylindrical PBRs illuminated from above (e.g. race-way or...
Tipo: Text
Palavras-chave: Photobioreactor; Optical depth; Photoinhibition; Light limitation; Turbidity; Modelling.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00450/56133/57675.pdf

La cinématique de l'Atlantique Nord : la question de la déformation intraplaque
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Fidalgo González, Luis.
The main features of geodynamic evolution in the North Atlantic and the lithospheric plates surrounding it have been known for a quarter of a century now.  However, a number of questions raised by the first models published have still not been clearly answered in detail. Among them, the difficulty in adjusting the domain to the north and the south of the Faeroe-Iceland-Greenland ridge should be highlighted. This study addresses the issue by using fracture zones as the main data for our reconstructions. We show that they accurately bound the kinematical reconstructions. They also enable kinematical reorganisation periods to be studied on the scale of oceans, as well as their duration.  Reconstructions carried out on these bases confirm the existence of...
Tipo: Text
Palavras-chave: Europa; Africa; North Atlantic; Modelling; Fracture zone; Magnetic anomaly; Ocean crust; Deformation; Plate tectonic; Europe; Afrique; Atlantique Nord; Modélisation; Zone Fracture; Ouverture; Anomalie Magnétique; Croute Oceanique; Déformation; Tectonique Plaque.
Ano: 2001
URL: http://archimer.ifremer.fr/doc/2001/these-1205.pdf

A digital atlas to link ontogenic shifts in fish spatial distribution to the environment of the eastern English Channel. Dab, Limanda limanda as a case-study
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Martin, Corinne; Vaz, Sandrine; Koubbi, Philippe; Meaden, Geoff; Engelhard, Georg H.; Lauria, Valentina; Gardel, Laure; Coppin, Franck; Delavenne, Juliette; Dupuis, Ludovic; Ernande, Bruno; Foveau, Aurelie; Lelievre, Stephanie; Morin, Jocelyne; Warembourg, Caroline; Carpentier, Andre.
The eastern English Channel, which connects the Atlantic Ocean to the North Sea through the Dover Strait, is an area where numerous and often conflicting human activities take place. A cross-border multidisciplinary project called CHARM was initiated to provide knowledge and tools for planners and decision-makers to durably manage the shared marine living resources. One such tool was an atlas of fish spatial distributions and modelled habitats, which was used here to investigate ontogenic and seasonal shifts in fish spatial distribution and habitat through a case-study, the dab Limanda limanda. Survey data for several life-history stages (eggs, larvae, coastal nurseries, &lt; and &gt; 1 year old) and seasons were used to map spatial patterns (using...
Tipo: Text
Palavras-chave: Pleuronectidae; Limanda limanda; Eastern Channel; Spatial distribution; Modelling; Kriging; Ichthyoplankton; Trawl; CUFES.
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00008/11942/8646.pdf

Modelisation morphodynamique de l'embouchure de la seine
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Waeles, Benoit.
The mouth of the Seine has been undergoing intense morphological changes for decades, because of containment work to improve access to the ports of Rouen and Le Havre. A significant trend is the progradation of the downstream estuary. Simultaneously, the surface area of the intertidal mudflats tends to decrease. The estuary's sediments are composed of silt and fine sand (respectively transported from the river Seine and the open sea). Their distribution is linked to the hydrodynamic characteristics of the estuary and may display layered vertical structures. To understand the estuary's morphological changes, a morphodynamic ditigal model is developed from a validated (3D) model of silty sediment transport. A model of suspended fine sand transport as well as...
Tipo: Text
Palavras-chave: Seine estuary; Modelling; Sediment transport; Hydrodynamic; Morphodynamic; Seine estuaire; Modelisation; Transport sediment; Hydrodynamique; Morphodynamique.
Ano: 2005
URL: http://archimer.ifremer.fr/doc/2005/these-2195.pdf

Programme coordonné Ecotron sur le site d'Arcachon (Aquitaine, France) : contrôle de la production biologique marine dans un écosystème lagunaire aménagé (réservoirs à poissons) - Bilan, synthèse et perspectives
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Lasserre, Pierre.
Coordinated ECOTRON Program on the Arcachon Basin (Aquitaine, France) : Control of marine biological production in a man-modified lagoon ecosystem (fish ponds). Results, synthesis and prospects. The "fish reservoirs" of the Arcachon Basin consist of eutrophic lagoon ecosys­tems, empirically exploited for extensive amphihaline fish culture (grey mullets, sea bass, eels, sea breams). The 1000 hectares of exploited farms, well integrated in a traditional socio-economic context, are presently not adapted for various reasons.The coordinate researches, which have been developed at Arcachon since 1974, within the ECOTRON (CNEXO) Program, show that these highly productive man modified ecosystems are well adapted for the development of semi-intensive aqua­culture....
Tipo: Text
Palavras-chave: Lagunes côtières exploitées; Réservoirs à poissons; Bassin d'Arcachon; Fonctionnement écosystème; Contrôle productivité; Modélisation; Développement potentiel; Exploited coastal lagoons; Fish ponds; Arcachon Bay; Ecosystem functioning; Productivity control; Modelling; Potential development.
Ano: 1979
URL: http://archimer.ifremer.fr/doc/00306/41676/40885.pdf

Modélisation de la détoxication de mollusques bivalves contenant des phycotoxines paralysantes ou diarrhéiques
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Gueguen, Marielle.
The purpose of this study is to implement models to describe detoxification kinetics of Pacific oysters Crassostrea gigas and Blue mussels Mytilus edulis containing paralytic and diarrheic phycotoxins respectively. First, experimental trials made it possible to complement data from the literature regarding the understanding of processes involved in mollusc detoxification. In particular, they pointed out a difference in the mollusc capacity to degrade cellwalls of phycotoxin-producing dinoflagellates, according to their en cystement capacities. It was observed that paralytic phycotoxins reached the various oyster tissues whereas diarrheic toxins were mainly sequestred in the digestive gland of mussels. The latter seem to be retained by lysosomes localized...
Tipo: Text
Palavras-chave: Modélisation; Mytilus edulis; Crassostrea gigas; Phycotoxines; Détoxication; Acide okadaïque; Toxines paralysantes; Modelling; Mytilus edulis; Crassostrea gigas; Phycotoxins; Detoxification; Okadaix acid; Paralytic toxin.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/00003/11473/8032.pdf

Development of emergency response tools for accidental radiological contamination of French coastal areas
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Duffa, Celine; Du Bois, Pascal Bailly; Caillaud, Matthieu; Charmasson, Sabine; Couvez, Celine; Didier, Damien; Dumas, Franck; Fievet, Bruno; Morillon, Mehdi; Renaud, Philippe; Thebault, Herve.
The Fukushima nuclear accident resulted in the largest ever accidental release of artificial radionuclides in coastal waters. This accident has shown the importance of marine assessment capabilities for emergency response and the need to develop tools for adequately predicting the evolution and potential impact of radioactive releases to the marine environment.  The French Institute for Radiological Protection and Nuclear Safety (IRSN) equips its emergency response centre with operational tools to assist experts and decision makers in the event of accidental atmospheric releases and contamination of the terrestrial environment. The on-going project aims to develop tools for the management of marine contamination events in French coastal areas. This should...
Tipo: Text
Palavras-chave: Decision support; Marine; Modelling; Radioecology; Nuclear accident.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00270/38118/36480.pdf

Les besoins écophysiologiques des larves d'huitres creuse Crassostrea gigas en conditions contrôlees : effet de la température, de la nourriture et modélisation de la croissance
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Rico Villa, Benjamin.
Nowadays, spat production of Pacific oyster Crassostrea gigas relies on rearing techniques under controlled conditions in hatchery. In this context, an extensive research in aquaculture is necessary because larval development and metamorphosis are critical for hatchery management. Firstly, a diet consisted in a Haptophyceae: Isochrysis affinis galbana (clone T-ISO) and a Bacillariophyceae: Chaetoceros calcitrans forma pumilum demonstrated its efficiency to supply the nutritional needs throughout the whole larval rearing. Then, a flow-through rearing system was developed and coupled with a continuous hydrobiological data recorder to provide basic information for ecophysiology research through different trophic levels and/or temperature throughout larval...
Tipo: Text
Palavras-chave: Crassostrea gigas; Larve; Huître; Croissance; Ecophysiologie; Microalgues; Température; Système d’élevage; Modélisation; Crassostrea gigas; Larvae; Oyster; Growth; Ecophysiology; Microalgae; Temperature; Rearing System; Modelling.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/00012/12308/9102.pdf

Modélisation et analyse numérique du couplage filet-écoulement hydrodynamique dans une poche de chalut
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Pichot, Geraldine.
We are interested in the numerical simulation of the catch process at the end part of a trawl. The study of previous works emphasizes the lack of a convincing flow model. The need of a physical understanding of the flow leads us to perform experimental campaigns around a rigid cod-end net model, whose results are given in the manuscript. We propose a model based on the Navier-Stokes/Brinkman equations coupled to an equation for the turbulent kinetic energy by the means of an eddy viscosity, with appropriate boundary conditions. Existence of a weak solution to our coupled problem is proved in dimension 2. Then, we present the axisymmetric code we developed, called SeaNet. We set the parameters of the model and validate the code by comparison with the...
Tipo: Text
Palavras-chave: Finite Element Method; Numerical simulations; Variational formulations; Modelling; Fluid/structure interactions; Turbulence; Fluid mechanics; Selectivity of fishing gear; Méthode des éléments finis; Simulations numériques; Formulations variationnelles; Modélisation; Intéractions fluide/structure; Turbulence; Mécanique des fluides; Sélectivité des engins de pêche.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/these-3350.pdf

Potential role of compressional structures in generating submarine slope failures in the Niger Delta
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Sultan, Nabil; Voisset, Michel; Marsset, Bruno; Marsset, Tania; Cauquil, E; Colliat, J.
The study area, offshore Nigeria, is located in one of the compressional zones within the Niger Delta, which is characterized by imbricate thrust structures. Although the low mean slope angle (around 2°), bathymetry data from the study area have shown the existence of several submarine landslides which coincide with known subsurface faulted compressive features.  In this paper, we have focused on a submarine slide occurring in water depths ranging between 1690 and 1750 m. Headwall scars, internal architecture and associated deposits have been characterized using a combination of 3D seismic data, near-bottom echosounder seismic profiles, Kullenberg cores and in-situ geotechnical measurements. The slide shows horseshoe shaped headwall scars and depositional...
Tipo: Text
Palavras-chave: Slope stability; Piezometer; Penetrometer; Niger Delta; Modelling; Compressional structures.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/publication-2408.pdf

Endommagement mecanique de materiaux composites. Role sur les proprietes hygrothermiques
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Perreux, D; Suri, C; Varchon, D; Oytana, C.
The mechanical behaviour of polymer based glass fibre composites depends on the damage level and the amount of moisture present. Two anelastic damage models, both adapted to the mechanical properties of epoxy and polyester matrix polymers, are proposed. A coupling effect between the kinetics of damage and moisture level is shown.
Tipo: Text
Palavras-chave: Moisture; Damage; Modelling; Ship technology; Mechanical properties; Composite materials; Humidité; Endommagement; Modélisation; Comportement; Matériau composite.
Ano: 1992
URL: http://archimer.ifremer.fr/doc/1992/acte-1062.pdf

Modelling the effects of macrofauna on sediment transport and bed elevation: Application over a cross-shore mudflat profile and model validation
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Orvain, Francis; Le Hir, Pierre; Sauriau, Pierre-guy; Lefebvre, Sebastien.
Tipo: Text
Palavras-chave: Modelling; Sediment dynamics; Erodability; Bioturbation; Macrofauna; Biota; Sediment stability.
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00079/19055/18610.pdf

Influence of temperature, pH and NaCl concentration on the maximal growth rate of Brochothrix thermosphacta and a bioprotective bacteria Lactococcus piscium CNCM I-4031
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Leroi, Francoise; Fall, Papa-abdoulaye; Pilet, Marie-france; Chevalier, Frederique; Baron, Regis.
The maximum specific growth rate (μmax) of Brochothrix thermosphacta, a spoilage bacteria of cooked peeled shrimp, and Lactococcus piscium CNCM I-4031, a bioprotective strain, was investigated under different conditions of temperature, NaCl concentrations and pH. The basic modelling approach used was the Gamma concept (γ-concept) and the model developed was then adapted to shrimp. Cardinal growth parameters were quite similar for the two strains, except for NaCl. No NaCl was required for growth and the NaClmax was three-times higher for B. thermosphacta than for L. piscium (62 and 23 g l−1 respectively). However, tolerance to NaCl was higher in seafood than in liquid broth, possibly due to presence of osmoltically active molecules. L. piscium and B....
Tipo: Text
Palavras-chave: Modelling; Biopreservation; Shrimp; Lactic acid bacteria; Brochothrix thermosphacta; Spoilage bacteria; Environmental conditions.
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00083/19473/17088.pdf

The quest for seafloor macrolitter: a critical review of background knowledge, current methods and future prospects
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Canals, Miquel; Pham, Christopher K.; Bergmann, Melanie; Gutow, Lars; Hanke, Georg; Van Sebille, Erik; Angiolillo, Michela; Buhl-mortensen, Lene; Cau, Alessando; Ioakeimidis, Christos; Kammann, Ulrike; Lundsten, Lonny; Papatheodorou, George; Purser, Autun; Sanchez-vidal, Anna; Schulz, Marcus; Vinci, Matteo; Chiba, Sanae; Galgani, Francois; Langenkämper, Daniel; Möller, Tiia; Nattkemper, Tim W.; Ruiz, Marta; Suikkanen, Sanna; Woodall, Lucy; Fakiris, Elias; Molina Jack, Maria Eugenia; Giorgetti, Alessandra.
The seafloor covers some 70% of the Earth's surface and has been recognized as a major sink for marine litter. Still, litter on the seafloor is the least investigated fraction of marine litter, which is not surprising as most of it lies in the deep sea, i.e. the least explored ecosystem. Although marine litter is considered a major threat for the oceans, monitoring frameworks are still being set up. This paper reviews current knowledge and methods, identifies existing needs, and points to future developments that are required to address the estimation of seafloor macrolitter. It provides background knowledge and conveys the views and thoughts of scientific experts on seafloor marine litter offering a review of monitoring and ocean modeling techniques....
Tipo: Text
Palavras-chave: Seafloor; Marine litter; Trawl surveys; Visual surveys; Deep sea; Modelling; Data harmonisation.
Ano: 2021
URL: https://archimer.ifremer.fr/doc/00657/76947/78156.pdf

Optimisation des conditions hydrobiologiques pour la conservation de l'huître creuse Crassostrea gigas en système re-circulé
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Buzin, Florence.
The maintenance of bivalve commercialisation du ring periods when sales are prohibited represents a major economic issue for shellfish-farming. To ensure their survival and to preserve the oyster Crassostrea gigas quality, their storage in land-based systems has been studied i) out of water in a cold room at 3°C with controlled humidity, enabling the bivalve sensory quality to be retained for 15 days, and ii) in recirculating systems in immersed conditions for 30 days. For the latter, the oysters were stored at 167 kg.m3 density in a tank equipped with an air-lift system, with water treated with UV and thermoregulated. A minimum of food was supplied to avoid mass tissue loss. A temperature of 16°C was defined as optimal to limit mortality and to avoid...
Tipo: Text
Palavras-chave: Crassostrea gigas; Huître Pacifique; Système re-circulé; Ecophysiologie; Sauvegarde; Modélisation; Crassostrea gigas; Pacific oyster; Recirculating system; Ecophysiology; Safeguard; Modelling.
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00092/20350/17995.pdf

Approche de la circulation residuelle en Baie de Seine
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Lehir, P; Salomon, J; Leprovost, C; Chabertd'Hieres, G; Mauvais, J.
By taking into account salinity measurements and consequently mean residence time, current measurements, tidal computation with a 2-D model and wind induced currents provided by a 3-D model, a global diagram of residual flow in Seine Bay is given. Main patterns are exhibited: density currents in the eastern part of the bay, off the Seine Estuary, wind induced circulation, especially along the coast and over the Channels, and tidal residual patterns induced by topography.
Tipo: Text
Palavras-chave: Simulation; Modelling; Wind driven circulation; Bottom topography; Density gradients; Water masses; River discharge; Haline circulation; Salinity gradients; Tidal currents; Residual flow.
Ano: 1985
URL: http://archimer.ifremer.fr/doc/1985/acte-1263.pdf

Modelling paralytic shellfish toxins (PST) accumulation in Crassostrea gigas by using Dynamic Energy Budgets (DEB)
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Pousse, Emilien; Flye-sainte-marie, Jonathan; Alunno-bruscia, Marianne; Hegaret, Helene; Rannou, Eric; Pecquerie, Laure; Marques, Goncalo M.; Thomas, Yoann; Castrec, Justine; Fabioux, Caroline; Long, Marc; Lassudrie, Malwenn; Hermabessiere, Ludovic; Amzil, Zouher; Soudant, Philippe; Jean, Fred.
As other filter-feeders, Crassostrea gigas can concentrate paralytic shellfish toxins (PST) by consuming dinoflagellate phytoplankton species like Alexandrium minutum. Intake of PST in oyster tissues mainly results from feeding processes, i.e. clearance rate, pre-ingestive sorting and ingestion that are directly influenced by environmental conditions (trophic sources, temperature). This study aimed to develop a mechanistic model coupling the kinetics of PST accumulation and bioenergetics in C. gigas based on Dynamic Energy Budget (DEB) theory. For the first time, the Synthesizing Units (SU) concept was applied to formalize the feeding preference of oysters between non-toxic and toxic microalgae. Toxin intake and accumulation were both dependent on the...
Tipo: Text
Palavras-chave: Alexandrium minutum; Paralytic shellfish toxins (PST); Dynamic Energy Budget (DEB); Modelling; Pacific oyster.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00455/56662/58407.pdf

Predictive systems ecology
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Evans, Matthew R.; Bithell, Mike; Cornell, Stephen J.; Dall, Sasha R. X.; Diaz, Sandra; Emmott, Stephen; Ernande, Bruno; Grimm, Volker; Hodgson, David J.; Lewis, Simon L.; Mace, Georgina M.; Morecroft, Michael; Moustakas, Aristides; Murphy, Eugene; Newbold, Tim; Norris, K. J.; Petchey, Owen; Smith, Matthew; Travis, Justin M. J.; Benton, Tim G.
Human societies, and their well-being, depend to a significant extent on the state of the ecosystems that surround them. These ecosystems are changing rapidly usually in response to anthropogenic changes in the environment. To determine the likely impact of environmental change on ecosystems and the best ways to manage them, it would be desirable to be able to predict their future states. We present a proposal to develop the paradigm of predictive systems ecology, explicitly to understand and predict the properties and behaviour of ecological systems. We discuss the necessary and desirable features of predictive systems ecology models. There are places where predictive systems ecology is already being practised and we summarize a range of terrestrial and...
Tipo: Text
Palavras-chave: Modelling; Systems ecology; Climate change; Ecosystem assessment.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00177/28816/27291.pdf

Ecophysiological deterministic model for Crassostrea gigas in an estuarine environment
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Barille, Laurent; Heral, Maurice; Barilleboyer, Al.
An ecophysiological deterministic model of growth, reproduction and interactions between the bivalve and its estuarine environ ment was established for the Japanese oyster Crassostrea gigas. The environmental variables used in the model are: total particulate matter, particulate organic matter, particulate inorganic matter, chlorophyll, phaeopigments, proteins, lipids and carbohydrates. Rates of clearance, filtration, ingestion, absorption and respiration along with efficiencies of retention, selection and absorption are modelled with endogenous (dry weight of the animal, energy allocation between growth and reproduction) and exogenous variables (temperature, food quality and quantity). The model simulate the temporal evolution of two compartments: somatic...
Tipo: Text
Palavras-chave: Crassoslrea gigas; Croissance; Écophysiologie; Modélisation; Turbidité; Crassostrea gigas; Ecophysiology; Growth; Modelling; Turbidity.
Ano: 1997
URL: http://archimer.ifremer.fr/doc/00038/14892/12219.pdf

Comportement du cadmium et du mercure lors de la diagenèse précoce et flux à l'interface eau-sédiments en zone littorale
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Gonzalez, Jean-louis.
The early diagenesis of Cd and Hg has been studied in different coastal areas (vasière Ouest-Gironde, Pertuis d'Antioche, baie de Marennes-Oléron). For these two metals, the fluxes at the sediment-water interface have been calculated. Considering only molecular diffusion, the diffusionnal fluxes of Cd and Hg to the colurnn water are negligible with regard to both the particular fluxes to the sediments and the inputs of the "Gironde" and "Charente" ·,estuaries. The take into account of the different processes which affect the ex changes at the interface (erosion, bioturbation) permits more realistic an estimation of the role of sediments in the geochemical cycle of Cd and Hg. The results show that up to 50% of particular Cd and Hg which are integrated into...
Tipo: Text
Palavras-chave: Cadmium; Mercure; Eaux intrstitielles; Diagenèse précoce; Flux; Interface eaux-sédiments; Bioturbation; Modélisation; Cadmium; Mercury; Pore waters; Early diagenesis; Fluxes; Sediment-water interface; Bioturbation; Modelling.
Ano: 1992
URL: http://archimer.ifremer.fr/doc/00442/55402/56920.pdf

The influence of variability in larval dispersal on the dynamics of a marine metapopulation in the eastern Channel
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Ellien, Celine; Thiebaut, Éric; Barnay, Anne-sophie; Dauvin, Jean-claude; Gentil, Franck; Salomon, Jean-claude.
In the English Channel, the polychaete Pectinaria in koreni forms isolated populations confined in bays and estuaries. To determine the influence of larval dispersal variability on the observed stock fluctuations of the three major Pectinaria koreni populations reported along the French coasts of the eastern Channel, larval dispersal was simulated using a 2D hydrodynamical lagrangian model integrating both the tidal residual and the wind-driven circulation. Year-to-year fluctuations of adult stocks were established from benthic surveys carried out between 1973 and 1998. Larval dispersal patterns vary between populations according to the relative importance of tidal advection and eddy diffusion so that local larval retention is maximal where tidal advection...
Tipo: Text
Palavras-chave: Pectinaria koreni; Metapopulation; Modelling; Recruitment; Larval dispersal; Pectinaria koreni; Métapopulation; Modélisation; Recrutement; Dispersion larvaire.
Ano: 2000
URL: https://archimer.ifremer.fr/doc/2000/publication-535.pdf

Un modèle asymptotique de la plaque stratifiée
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Kail, R; Lene, F; De Roeck, Y.
In order to calculate the behaviour of thin structures of laminated composite materials, a bidimensional plate model is generated by an asymptotic development technique. From a structural analysis by plane finite elements at the middle surface, this model yields the equations leading to the computation, at each point of the laminated material, of the displacement and the stress tensor. After describing the theoretical model, numerical results are compared with the analytical solution of a test problem.
Tipo: Text
Palavras-chave: Ship technology; Modelling; Mathematical models; Composite materials; Eléments finis; Développement asymptotique; Composites; Plaque.
Ano: 1992
URL: http://archimer.ifremer.fr/doc/1992/acte-1081.pdf

Biological and economic factors in the selection of cultured fish species and the development of a bio-economic model
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Wu, R.
The selection of candidate species for mariculture is determined by a number of biological factors, e.g. foraging efficiency, growth efficiency, mortality, grow-out period and susceptibility to environmental fluctuations, disease and crowding, as well as economic factors e.g. the supply and price of fry, grow-out cost and price of adult. A computer model incorporating these major factors is being developed, to determine and compare the potential of different culture species.
Tipo: Text
Palavras-chave: Lates calcarifer; Epinephelus tauvina; Mylio macrocephalus; Pisces; Marine fish; Tolerance; Biology; Modelling; Economic models; Diseases; Mortality; Growth; Cultured organisms.
Ano: 1989
URL: http://archimer.ifremer.fr/doc/1989/acte-1488.pdf

Fast hydrodynamic model for medium- and long-term dispersion in seawater in the English Channel and southern North Sea, qualitative and quantitative validation by radionuclide tracers
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Bailly Du Bois, Pascal; Dumas, Franck.
The database for medium- and long-term model validation using Sb-125 released by the La Hague reprocessing plant includes 1400 measurements performed between 1987 and 1994 in the English Channel and the North Sea and data for each release since 1982. Antimony-125 has a conservative behaviour in water masses over a period of several years. These data can be used qualitatively and quantitatively to compare the measured concentrations with the calculated ones and quantities of tracers. Tritium measurements are also available for model calibration.   A two-dimensional hydrodynamic model has been developed to allow repetitive long-term simulations. This model uses a database of residual tidal currents calculated using the Lagrangian barycentric method [Salomon,...
Tipo: Text
Palavras-chave: North Sea; English Channel; European Continental Shelf; Tritium; Sb 125; Radioactive tracer; Wind stress; Calibration; Modelling.
Ano: 2005
URL: http://archimer.ifremer.fr/doc/2005/publication-731.pdf

Modélisation du transport sédimentaire et des interactions morphodynamiques par les courants de turbidité dans les canyons sous-marins. Application à la Méditerranée Occidentale
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Payo Payo, Marta.
Turbidity currents in submarine canyons are the main contribution for sediment transfer across the continental margins. Geological studies of submarine canyons and associated turbiditic systems for more than 30 years led to an extraordinary breakthrough in the understanding of how turbidite systems evolve. However, these studies remain limited to a posteriori interpretations, based on the distribution of deposits and morphological evidences. The overarching aim of this thesis is to apply a 2DH process-based model to simulate large-scale turbidity currents on two different submarine canyons in the western Mediterranean coast.The work in La Fonera canyon, in the Catalan margin, focuses on the modelling of sediment transport and accumulation resulting from...
Tipo: Text
Palavras-chave: Canyons sous-marins; Chalutage; Courants de turbidité; Forces de Coriolis; Hydrodynamique; Modélisation; Sédimentologie; Submarine canyons; Trawling; Turbidity current; Modelling; Hydrodynamics; Sedimentology; Coriolis forces.
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00498/60919/64280.pdf

Modélisation de la dynamique du microphytobenthos des vasières intertidales du bassin de Marennes-Oléron. Effets des synchroniseurs physiques sur la régulation de la production
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Guarini, Jean-marc.
The study aimed at quantifying the spatio-temporal evolution of microphytobenthic biomass in intertidal mudflats of Marennes-Oléron Bay. To reach this goal, a dynamic model has been proposed, including processes of primary production, active migration of epipelic diatoms and biomass lasses due to mortalities on one hand and resuspension in the water column during submersion on the other hand. The spatialisation is given by a hydrodynamic madel which calculates the water height everywhere. The photic environment of microphytobenthos is described in a discrete way, by means of two layers: the biofilm of epipelic algae « S »on the top of the sediment and the fust centimeter of the mud « F ». The endogenous vertical migration rhythm of epipelic algae controls...
Tipo: Text
Palavras-chave: Microphytobenthos; Vasière intetidale; Modélisation; Dynamique de la biomasse; Expérimentation; Ecophysiologie; Couplage physique/biologie; Microphytobenthos; Intertidal mudflat; Modelling; Dynamics of the biomass; Experimentation; Ecophysiology; Physics/biology coupling.
Ano: 1998
URL: http://archimer.ifremer.fr/doc/00439/55029/56462.pdf

Getting the most out of it: Optimal experiments for parameter estimation of microalgae growth models
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Munoz-tamayo, Rafael; Martinon, Pierre; Bougaran, Gael; Mairet, Francis; Bernard, Olivier.
Mathematical models are expected to play a pivotal role for driving microalgal production towards a profitable process of renewable energy generation. To render models of microalgae growth useful tools for prediction and process optimization, reliable parameters need to be provided. This reliability implies a careful design of experiments that can be exploited for parameter estimation. In this paper, we provide guidelines for the design of experiments with high informative content based on optimal experiment techniques to attain an accurate parameter estimation. We study a real experimental device devoted to evaluate the effect of temperature and light on microalgae growth. On the basis of a mathematical model of the experimental system, the optimal...
Tipo: Text
Palavras-chave: Biofuel; Biological processes; Modelling; Parameter identification; Optimal experiment design.
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00191/30252/28684.pdf

Physiologie de la maturation et de la ponte chez l'huître creuse Crassostrea gigas
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Soletchnik, Patrick; Geairon, Philippe; Razet, Daniel; Goulletquer, Philippe.
The physiological ecology of the Pacific oyster Crassostrea gigas was studied using a conditioning delayed by temperature. Experiments were carried out on five batches and 2 year-classes classified into 6 maturation stages. The scope for growth concerning the stages N*5 and 6 was nearly zero while positive for early stages as well as for the post-spawning stage. Moreover, the 1 year-old oysters showed a significant lowered scope for growth (-110 J/h) compared to adult oysters (-14 J/h), therefore demonstrating the increased sensitivity of young oysters to stressful environmental conditions. By comparing the experimental results with the current models, developed on immature oysters, facilitates the model parameters spécifications during gametogenesis. For...
Tipo: Text
Palavras-chave: Modelling; Ecophysiology; Mortality; Crassostrea gigas; Modèle; Ecophysiologie; Mortalité; Crassostrea gigas.
Ano: 1996
URL: http://archimer.ifremer.fr/doc/1996/rapport-1643.pdf

Dynamical contribution to sea surface salinity variations in the eastern Gulf of Guinea based on numerical modelling
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Berger, Henrick; Treguier, Anne-marie; Perenne, Nicolas; Talandier, Claude.
In this study, we analyse the seasonal variability of the sea surface salinity (SSS) for two coastal regions of the Gulf of Guinea from 1995 to 2006 using a high resolution model (1/12°) embedded in a Tropical Atlantic (1/4°) model. Compared with observations and climatologies, our model demonstrates a good capability to reproduce the seasonal and spatial variations of the SSS and mixed layer depth. Sensitivity experiments are carried out to assess the respective impacts of precipitations and river discharge on the spatial structure and seasonal variations of the SSS in the eastern part of the Gulf of Guinea. In the Bight of Biafra, both precipitations and river runoffs are necessary to observe permanent low SSS values but the river discharge has the...
Tipo: Text
Palavras-chave: Gulf of Guinea; Salinity; Modelling; Congo; Bight of Biafra; Mixed layer budget.
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00194/30493/29215.pdf

Modelling abrupt glacial North Atlantic freshening: Rates of change and their implications for Heinrich events
Provedor de dados: Institutional Archive of Ifreme (ArchiMer)
Autores: Bigg, Grant R.; Levine, Richard C.; Green, Clare L.
The abrupt delivery of large amounts of freshwater to the North Atlantic in the form of water or icebergs has been thought to lead to significant climate change, including abrupt slowing of the Atlantic Ocean meridional overturning circulation. In this paper we examine intermediate complexity coupled modelling evidence to estimate the rates of change, and recovery, in oceanic climate that would be expected for such events occurring during glacial times from likely sources around the North Atlantic and Arctic periphery. We show that rates of climate change are slower for events with a European or Arctic origin. Palaeoceanographic data are presented to consider, through the model results, the origin and likely strength of major ice-rafting, or Heinrich,...
Tipo: Text
Palavras-chave: Heinrich events; Modelling; Quaternary; Icebergs.
Ano: 2011
URL: https://archimer.ifremer.fr/doc/00227/33777/82665.pdf

Pêcherie démersale côtière au Sénégal. Essai de modélisation de la dynamique de l'exploitation des stocks
Provedor de dados: Ocean Docs: e-repository of  publications
Autores: Institut de Recherche pour le Développement, Paris (France); Fall, Massal.
Français - Les traits essentiels de la côte sénégalaise, repères historiques de la pêche, communautés de pêcheurs, caractéristiques des flottes et modes d’accès à la ressource et d’interaction sont analysés. Les caractéristiques, tendances décroissantes de l’abondance,niveaux d’exploitation, mesures d’aménagement, relations interspécifiques, changements potentiels et sources de variation des stocks démersaux côtiers sont précisés. Les notions de tactiques et stratégies de pêche sont passées en revue, conceptualisées puis étudiées.Le modèle «Dynamique Conjointe Exploitation Ressource» utilisé repose sur la définition de 4 typologies. L’utilisation de méthodes de classification et de connaissances d’experts conduit à considérer 32 stocks, 31 strates, 82...
Tipo: Theses and Dissertations
Palavras-chave: Fisheries; Demersal fisheries; Modelling; Stocks; Ecosystems; Community fishing; Inland waters; Marine water; Hydrologic cycle; Fishermen; Fishing fleet; Shrimp fisheries; Capture fisheries; Fisheries management; Trawling; Artisanal fishing; Fishing licenses.
Ano: 2009
URL: http://hdl.handle.net/1834/5004

The effect of the Mbita Causeway on water currents in the region of Rusinga Channel, Winam Gulf, Lake Victoria: a 3D modelling study with ELCOM
Provedor de dados: Ocean Docs: e-repository of  publications
Autores: Romero, J.R.; Khisa, P.
The Mbita Causeway in Kenya was constructed in the early 1980’s to link Rusinga Island to the mainland to facilitate the transport of people, goods, and services to the island. One of the effects of the Causeway was to permanently block a secondary connection between Rusinga Channel and the offshore waters of Lake Victoria. This secondary channel may have served as a substantial pathway of exchange between Winam Gulf and Lake Victoria prior to the Causeway. There has been considerable scientific and political debate as to whether decreased flushing within the two bays on either side of the Causeway has occurred and led to poorer lake water quality since the construction of the barrier. In Apr.-May 2005 an intensive field investigation was undertaken to...
Tipo: Proceedings Paper
Palavras-chave: Hydrodynamics; Water quality; Channel flow; Development projects; Simulation; Modelling; Flushing; Environmental effects; Water currents; Inland water environment; Hydrodynamics; Http://aims.fao.org/aos/agrovoc/c_3723.
Ano: 2006
URL: http://hdl.handle.net/1834/1473

Biophysical isopycnic-coordinate modelling of plankton dynamics in the Arabian Sea
Provedor de dados: Ocean Docs: e-repository of  publications
Autores: Idrisi, N.; Romanou, A.; Olascoaga, M.J.
A Nutrients-Phytoplankton-Zooplankton-Detritus (NPZD) ecosystem model is coupled to the Miami Isopycnic-Coordinate Ocean Model (MICOM) to study planktondynamics in the Arabian Sea. Experiments oriented to testing the NPZD-MICOM coupled model sensitivity to variations in several parameters are performed. Particular attention is paid to the rates of detritus sinking and maximum phytoplankton growth rate. The coarse features of the blooms are captured by all the experiments considered, and agree with earlier models for the biological activity of the region. Intensity, duration, and peaks of the blooms are found to be quite sensitive to the parameter choices. The existence of an offshore deep chlorophyll maximum in the model is found to be closely related to...
Tipo: Journal Contribution
Palavras-chave: Phytoplankton; Zooplankton; Detritus; Biophysics; Modelling; Arabian Sea; Http://aims.fao.org/aos/agrovoc/c_565.
Ano: 2005
URL: http://hdl.handle.net/1834/271

Assessment of an environmental barrier to transport of ichthyoplankton from the southern to
Provedor de dados: Ocean Docs: e-repository of  publications
Autores: Lett, Christophe; Veitch, Jennifer; Van der Lingen, Carl D.; Hutchings, Larry.
The Lüderitz upwelling cell and Orange River cone (LUCORC) area, a transboundary region between South Africa and Namibia, is considered to be an environmental barrier to transport of ichthyoplankton from the southern to the northern Benguela upwelling ecosystems. We use environmental data and modelling to assess the potential mechanisms responsible for this barrier: environmental data were extracted from the 1 × 1° World Ocean Atlas 2001 database and used to build maps of annual mean salinity, temperature, chlorophyll, dissolved oxygen and nutrient concentrations; outputs of a regional circulation model were used in an individual-based model to assess the transport of passive particles from the southern to the northern Benguela. The data show no clear...
Tipo: Journal Contribution
Palavras-chave: Ichthyoplankton; Upwelling; Modelling; Coastal oceanography; Trade winds; Salinity; Hydrodynamics; Cartesian coordinates; Chlorophylls.
Ano: 2007
URL: http://hdl.handle.net/1834/4667

Cross-shelf biogeochemical characteristics of sediments in the central Benguela and their relationship to overlying water column hypoxia
Provedor de dados: Ocean Docs: e-repository of  publications
Autores: Monteiro, P.M.S.; Van Der Plas, Anja; Pascall, A.
Data from two cross-shelf sediment sampling cruises were used to explain reasons for the sediment biogeochemical variability in respect of carbon, nitrogen and sulphur, and how the cycling of these elements governs the biogeochemistry of the overlying water through their control of the redox conditions. The spatial extent of this benthic–pelagic flux link is limited to the innershelf mud belt system on the Namibian shelf. The inshore mud belt is the primary deposition area of the carbon and nitrogen new production export flux. The offshore organic-rich zones are thought to be relict particulate organic matter originating from the inshore mud belt rather than from an overlying pelagic source. These data were used to set up a multi-layer sediment model that...
Tipo: Journal Contribution
Palavras-chave: Anoxia; Carbon; Hypoxia; Modelling; Sediments; Carbon; Anoxia; Hypoxia; Http://aims.fao.org/aos/agrovoc/c_1301; Http://aims.fao.org/aos/agrovoc/c_8831; Http://aims.fao.org/aos/agrovoc/c_24472.
Ano: 2007
URL: http://hdl.handle.net/1834/2129

Factores que afectan las tasas de captura de langostino amarillo (Cervimunida johni) en la zona norte de Chile
Provedor de dados: Ocean Docs: e-repository of  publications
Autores: Wiff, R.; Quiroz, J.C.; Montenegro, C.
An analysis was made of the factors affecting the catch rates of the yellow squat lobster (Cervimunida johni) in Chile’s northern region (26°03’-32°10’S) by reviewing commercial fishing logbooks from 1993 to 2003. Factors evaluated included years, months, depth stratum, fishing areas and fleet characteristics as linear predictors in a generalized linear model (GLM) in order to explain variability in the catch rate. In contrast with other fisheries, with this resource the technical characteristics of the fleet and its’ specialization poorly explain variations in catch rate; temporal factors and their interaction were, however, highly significant. The results of this study, together with the life history of the resource, allow the supposition that...
Tipo: Journal Contribution
Palavras-chave: Modelling; Catch/effort; Crustacean fisheries; Lobster fisheries.
Ano: 2005
URL: http://hdl.handle.net/1834/2070

Wave and wind conditions in the Red Sea: A numerical study using a third generation wave model
Provedor de dados: Ocean Docs: e-repository of  publications
Autores: Saad, Ahmed Mohamed Elfatih.
In order to understand how waves behave and how other parameters can interact between ocean and atmosphere we can use a numerical model. For the Red Sea basin wave measurements are absent and due to that a WAM wave model is used to study the wave climate. The aim of this thesis is to run a wave model for the Red Sea area to begin a local forecast service and then estimate climatology of wave height, needed in almost all coastal engineering studies. As well as to give engineers a description of ocean surface waves and forces, this knowledge about Red Sea wave conditions can help the local  shermen that use small vessels. The third generation wave model WAM is used to hindcast the wave condition in the Red Sea for the year 2007. The WAM model is forced using...
Tipo: Theses and Dissertations
Palavras-chave: Modelling.
Ano: 2010
URL: http://hdl.handle.net/1834/5074

Development and evaluation of neural network models to estimate daily solar radiation at Córdoba, Argentina
Provedor de dados: Pesquisa Agropecuária Brasileira
Autores: Bocco,Mónica; Ovando,Gustavo; Sayago,Silvina.
The objective of this work was to develop neural network models of backpropagation type to estimate solar radiation based on extraterrestrial radiation data, daily temperature range, precipitation, cloudiness and relative sunshine duration. Data from Córdoba, Argentina, were used for development and validation. The behaviour and adjustment between values observed and estimates obtained by neural networks for different combinations of input were assessed. These estimations showed root mean square error between 3.15 and 3.88 MJ m-2 d-1 . The latter corresponds to the model that calculates radiation using only precipitation and daily temperature range. In all models, results show good adjustment to seasonal solar radiation. These results allow inferring the...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Modelling; Prediction; Backpropagation neural networks.
Ano: 2006
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-204X2006000200001

Economic and climatic models for estimating coffee supply
Provedor de dados: Pesquisa Agropecuária Brasileira
Autores: Moraes-Oliveira,Adriana Ferreira de; Aparecido,Lucas Eduardo de Oliveira; Figueira,Sérgio Rangel Fernandes.
Abstract: The objective of this work was to estimate the coffee supply by calibrating statistical models with economic and climatic variables for the main producing regions of the state of São Paulo, Brazil. The regions were Batatais, Caconde, Cássia dos Coqueiros, Cristais Paulista, Espírito Santo do Pinhal, Marília, Mococa, and Osvaldo Cruz. Data on coffee supply, economic variables (rural credit, rural agricultural credit, and production value), and climatic variables (air temperature, rainfall, potential evapotranspiration, water deficit, and water surplus) for each region, during the period from 2000-2014, were used. The models were calibrated using multiple linear regression, and all possible combinations were tested for selecting the variables....
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Coffea arabica; Climate; Econometrics; Modelling; Rural credit.
Ano: 2017
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-204X2017001201158

Optimisation methods for assisting policy decisions on endemic diseases
Provedor de dados: Research in Agricultural & Applied Economics (AgEcon Searh)
Autores: Stott,   Alistair W.
Endemic disease of animals is an economic problem as it deprives humans of scarce resources that might otherwise satisfy human wants. Optimisation methods identify the strategies that minimise this economic problem. Given the potentially vast extent of the deprivation, not only in terms of lost wealth but also in terms of animal welfare, human health and environmental damage, this subject offers great benefits to decision-makers from the individual farm to the global level. This paper uses examples to illustrate the basic economic principles concerned. It shows how these principles may be extended to deal with current limitations in theory and practice. Lack of data is a common problem that may be dealt with by using computer simulation, theoretical...
Tipo: Working or Discussion Paper
Palavras-chave: Economics; Decision analysis; Optimisation; Modelling; Endemic disease; Knowledge transfer; Health Economics and Policy.
Ano: 2006
URL: http://purl.umn.edu/46000

Plagiarism Without Apology--Systematic Integration of Available Information in a Long Run Agricultural Outlook
Provedor de dados: Research in Agricultural & Applied Economics (AgEcon Searh)
Autores: Witzke,   Heinz Peter; Britz,   Wolfgang.
In the context of a long run agricultural outlook on behalf of the European Environmental Agency a new methodology has been developed to systematically integrate external forecasts into a quite detailed agricultural sector model. External forecasts usually provide estimates for the exogenous variables in modelling work and frequently they are also used for comparisons and potential reassessment of empirical specifications. The innovative characteristic of this study is that expert forecasts have been used to specify parameter changes expressing structural change affecting behavioural functions. The outlook was therefore set up as a simultaneous estimation and forecasting effort which permitted to integrate various, usually contradictory expert forecasts...
Tipo: Conference Paper or Presentation
Palavras-chave: Agricultural outlook; Forecasting; Modelling; Expert information; Agricultural and Food Policy; C15; C53; Q11; Q19; Q21.
Ano: 2005
URL: http://purl.umn.edu/24666

MODELLING IMPACTS OF SOME EUROPEAN BIOFUEL MEASURES
Provedor de dados: Research in Agricultural & Applied Economics (AgEcon Searh)
Autores: Ledebur,   Oliver von; Salamon,   Petra; Zimmermann,   Andrei; van Leeuwen,   Myrna; Tabeau,   Andrzej A.; Chantreuil,   Frederic.
Against the background of increasing concerns regarding the energy supply security as well as environmental concern the interest for renewable energy sources has increased in recent years. The biofuel sector, backed by public policies, experienced a strong increase in and outside Europe. A methodology that allows for the estimation of the impacts of the fulfilment of the proposed biofuel targets in the EU member states is proposed and implemented in the AGMEMOD model for France and Germany. The so called normative approach, based on the use of a logistic function as biofuel demand function allows to perform simulations to assess the impact of the biofuel demand expansion on agricultural markets. The implemented approach and the simulation results indicate...
Tipo: Conference Paper or Presentation
Palavras-chave: Biofuel targets; Biodiesel; Ethanol; Modelling; Crop Production/Industries; Public Economics; Resource /Energy Economics and Policy.
Ano: 2008
URL: http://purl.umn.edu/6649

The profitability of a lamb meat system is greatly influenced by lambing time
Provedor de dados: Research in Agricultural & Applied Economics (AgEcon Searh)
Autores: Casburn,   Geoff.
Special Edition Sheep and Cattle Production in New South Wales
Tipo: Article
Palavras-chave: Modelling; Sheep enterprise; Lamb meat; Joining; Gross margin; Farm Management.
Ano: 2011
URL: http://purl.umn.edu/121461

Modelling Policies for Multifunctional Agriculture and Rural Development in a Remote EU Region (Caithness &amp; Sutherland, Scotland, UK)
Provedor de dados: Research in Agricultural & Applied Economics (AgEcon Searh)
Autores: Bergmann,   Holger; Thomson,   Kenneth J.
A modified version of a system dynamics model constructed for an EU-wide case-study project (TOPMARD) using STELLA software was used to simulate the effects of a number of development scenarios for a remote rural area in Northern Scotland, i.e. Caithness &amp; Sutherland, which is characterised by multifunctional agriculture. In this paper, the context of the modelling work in policy and socioeconomic terms is first described. This is followed by the specification of the model and of the modelling scenarios, one of which relates to the “decommissioning” (run-down) of a major industrial site (Dounreay) within the area. The modelling results are discussed, in terms of regional population, land use, economic and other terms, from 2001 to 2015/2031. Finally,...
Tipo: Conference Paper or Presentation
Palavras-chave: Modelling; Multifunctionality; Input-output; Systems dynamics; Rural policy; Agricultural and Food Policy; Community/Rural/Urban Development; Public Economics; Research Methods/ Statistical Methods.
Ano: 2008
URL: http://purl.umn.edu/6596

REGIONAL IMPACT ANALYSIS OF EUROPEAN POLICY SPENDING IN A RURAL REMOTE AREA (CAITHNESS &amp; SUTHERLAND, SCOTLAND, UK)
Provedor de dados: Research in Agricultural & Applied Economics (AgEcon Searh)
Autores: Bergmann,   Holger; Thomson,   Kenneth J.
A modified version of a system dynamics model constructed for an EU-wide case-study project (TOP-MARD) using STELLA software was used to simulate the effects of a number of development scenarios for a remote rural area in Northern Scotland, i.e. Caithness &amp; Sutherland, which is characterised by a high regional importance of agriculture for the local economy. In this paper, the context of the modelling work in policy and socio-economic terms is first described. This is followed by the specification of the model and of the several modelling scenarios, which relate to the reconfiguration of Pillar 2 spending within the area and an reversal of recent Structural Funds spending for 2007 onwards. The modelling results are discussed, in terms of regional...
Tipo: Conference Paper or Presentation
Palavras-chave: Modelling; Input-output; Systems dynamics; Rural viability; Marketing.
Ano: 2008
URL: http://purl.umn.edu/52645

Karpography: a generic concept of quality for chain analysis and knowledge transfer in supply chains
Provedor de dados: Research in Agricultural & Applied Economics (AgEcon Searh)
Autores: McRoberts,   Neil.
As with other areas of science, supply chain analysis suffers from the fact that practitioners of its different component disciplines often find it exchange results and methods of analysis. For fresh produce supply chains a key issue is how to unite the elegant mathematical work on the physiology of quality change with the more qualitative methods of social science that are applied to the analysis supply chain management. This paper explores the possibility of utilising approaches which are widely used in demography to unify concepts of quality modelling and supply chain efficiency in the fresh produce sector. A key feature of demographic (or karpographic) models is that they use the average properties of individuals to model the behaviour of cohorts (or...
Tipo: Working or Discussion Paper
Palavras-chave: Quality; Modelling; Matrix model; Variance; Supply chain; Probability; Agribusiness.
Ano: 2006
URL: http://purl.umn.edu/45995

A fenntartható fejlődést szolgáló paradigma
Provedor de dados: Research in Agricultural & Applied Economics (AgEcon Searh)
Autores: Meszaros,   Sandor.
Az uralkodó neoklasszikus paradigma alapján a 20. század második felében a gazdasági növekedés a várható klímaváltozás, a Föld természeti erőforrásai és a társadalmi egyenlőtlenségek figyelembevétele nélkül ment végbe. Erre a helyzetre szolgált válaszul a fenntarthatóság koncepciója, amely az utóbbi két évtizedben globális mozgalommá vált, és nemzeti alkalmazkodási stratégiák kidolgozásához vezetett. A gazdaság működésére azonban igazán új paradigma mégsem született, bár a köz¬gazdaságtan a komplexitás irányába látszik fejlődni. Az új (transzdiszciplináris) paradigma eddigi hiánya ellenére a szükséges változások irányai már felismerhetők: a fosszilis energiaforrások mielőbbi helyettesítése és az erdőgazdaság kiemelt kezelése (Low Carbon Economy), valamint...
Tipo: Journal Article
Palavras-chave: Gazdasági paradigmák; Fenntarthatóság; Klímaváltozás; Globalizáció; Modellezés; Economic paradigms; Sustainability; Climate change; Globalisation; Modelling; Agricultural and Food Policy; Environmental Economics and Policy.
Ano: 2010
URL: http://purl.umn.edu/99116

CAP-reform and the provision of non-commodity outputs in Brandenburg
Provedor de dados: Research in Agricultural & Applied Economics (AgEcon Searh)
Autores: Happe,   Kathrin; Damgaard,   Martin; Osuch,   Amanda; Sattler,   Claudia; Zander,   Peter; Uthes,   Sandra; Schuler,   Johannes; Piorr,   Annette.
This paper presents an attempt to model the response of selected farms to decoupled direct payments and the associated impact on the provision of a defined set of non-commodity outputs (NCO’s) using a combined modelling approach consisting of the AgriPoliS and MODAM models. AgriPoliS focuses on the socio-economic dimension of multifunctionality at the individual farm and regional levels and explicitly models heterogeneous farms (in size, location and efficiency) within a competitive and dynamic environment. The linear-programming model MODAM allows a detailed representation of production processes and their impact on the environmental dimension of multifunctionality at the farm level. We simulate the impact of a uniform area payment and a fully decoupled...
Tipo: Journal Article
Palavras-chave: Decoupling; Multifunctionality; Non-commodity outputs; Modelling; Simulation; Policy analysis; Ecological indicators; Agricultural and Food Policy; Land Economics/Use.
Ano: 2006
URL: http://purl.umn.edu/97193

Modelling Climate Change and Agricultural Production in Sub-Saharan Africa (SSA): In Quest of Statistics
Provedor de dados: Research in Agricultural & Applied Economics (AgEcon Searh)
Autores: Koffi-Tessio,   Egnonto M.
Climate change is a natural and dynamic phenomenon resulting from complex interrelationships between physical, environmental and human factors. The sustainability of life on earth depends partly on the ability of mankind to maintain this natural and balanced flow of such gases such as carbon dioxide (CO2) and water vapor traping heat. Unfortunately, human beings contribute significantly to the presence of such gases known as Green House Gases (GHGs) through agricultural and industrial activities. The implications are the excess trap of sunlight and the blocking of outward radiation. In sub-Saharan Africa (SSA), the importance of agriculture cannot be stressed enough given that it is central to economic growth and most of economic activities in the region...
Tipo: Conference Paper or Presentation
Palavras-chave: Modelling; Agriculture; Climate change; Variability; Statistics; Policies; Environmental Economics and Policy; Farm Management.
Ano: 2009
URL: http://purl.umn.edu/50821

Land Transactions in the North of Vietnam: A Modelling Approach
Provedor de dados: Research in Agricultural & Applied Economics (AgEcon Searh)
Autores: Van Hung,   Pham; MacAulay,   T. Gordon.
The use of mathematical models to describe the interactions of variables is useful in modern management. In this paper, a 'mixed' model combining the knapsack problem, a household model and a form of spatial equilibrium model into a modelling framework is developed. The impacts of changes in off-farm wage rates, transaction costs in the rental market, the output prices of paddy crops, and land transactions were examined in the model. The simulation has led to the conclusion that the real benefits to farm households from land consolidation may not be apparent until the real opportunity cost of farm labour begins to rise. In addition, a reform policy in the administrative sector which encourages, not only the process of land accumulation and the rental...
Tipo: Conference Paper or Presentation
Palavras-chave: Land transactions; Modelling; Knapsack problem; Vietnam; Land Economics/Use; C6; Q15; Q24.
Ano: 2006
URL: http://purl.umn.edu/25601

Modelling the CAP Reform at the Regional Level with ProLand
Provedor de dados: Research in Agricultural & Applied Economics (AgEcon Searh)
Autores: Weinmann,   Bernd; Sheridan,   Patrick; Schroers,   Jan Ole; Kuhlmann,   Friedrich.
The reform of the European Common Agricultural Policy (CAP) will fundamentally affect the decision behaviour of land users. So far transfer payments were coupled to specific forms of land use. The reform encourages land users to make decisions concerning production based solely on market aspects. The effects of the CAP reform on the Lahn Dill region in Germany are simulated with the spatially explicit land use model ProLand. The results show that land use decisions will be based stronger on site specific natural conditions than was the case in the Agenda 2000 scenario. The transfer payment volume directed into the region increases considerably.
Tipo: Conference Paper or Presentation
Palavras-chave: Modelling; Decision support; Land use; Spatially explicit; Agricultural and Food Policy; Q01.
Ano: 2005
URL: http://purl.umn.edu/24508

DOING POLICY IN THE LAB! OPTIONS FOR THE FUTURE USE OF MODEL-BASED POLICY ANALYSIS FOR COMPLEX DECISION-MAKING
Provedor de dados: Research in Agricultural & Applied Economics (AgEcon Searh)
Autores: Happe,   Kathrin; Balmann,   Alfons.
For models to have an impact on policy-making, they need to be used. Exploring the relationships between policy models, model uptake and policy dynamics is the core of this article. What particular role can policy models play in the analysis and design of policies? Which factors facilitate (inhibit) the uptake of models by policy-makers? What are possible pathways to further develop modelling approaches to better meet the challenges facing agriculture today? In this paper, we address these issues from three different points of view, each of which should shed some light on the subject. The first point of view discusses models in the framework of complex adaptive systems and uncertainty. The second point of view looks at the dynamic interplay between...
Tipo: Conference Paper or Presentation
Palavras-chave: Modelling; Complexity; Participatory modelling; Policy analysis; Model use; Agricultural and Food Policy; Research Methods/ Statistical Methods.
Ano: 2008
URL: http://purl.umn.edu/6588

Improving Forecast Performance with Reduced Parameter, Large Order AR Models
Provedor de dados: Research in Agricultural & Applied Economics (AgEcon Searh)
Autores: Ramirez,   Octavio A.; Dorfman,   Jeffrey H.
Tipo: Conference Paper or Presentation
Palavras-chave: Time series; Modelling; Bayesian probability; Research Methods/ Statistical Methods.
Ano: 2010
URL: http://purl.umn.edu/60917

Derogation on the EU Nitrates Directive: does it make a difference?
Provedor de dados: Research in Agricultural & Applied Economics (AgEcon Searh)
Autores: Claeys,   Dakerlia; Lauwers,   Ludwig H.; Marchand,   Fleur L.; Van Meensel,   Jef; Buysse,   Jeroen; Van der Straeten,   Bart; Van Huylenbroeck,   Guido.
The paper discusses an ex ante evaluation of the derogation on the Nitrates Directive for Flanders, Belgium, which is a case of intensive but highly productive livestock areas. The aim is to develop an accurate simulation model to detect small differences in manure surpluses caused by changes of manure production and/or utilization. The system of models consists of various modules to fine tune the calculations of manure production, fertilizing behaviour and manure allocation and disposal on and off farm. The results show that derogation may cause the existing manure surpluses to expire, if only nitrogen limits are considered and no transactions costs are taken into account. When also phosphate fertilization limits are considered, the increase in manuring...
Tipo: Conference Paper or Presentation
Palavras-chave: Nitrates Directive; Derogation; Modelling; Environmental Economics and Policy; Livestock Production/Industries.
Ano: 2008
URL: http://purl.umn.edu/44436

Economic Evaluation of Irrigated Dairy Forage Production.
Provedor de dados: Research in Agricultural & Applied Economics (AgEcon Searh)
Autores: Gaffy,   Joe; Gyles,   Oliver.
An optimisation model was developed to compare the profitability of different forage species on irrigated dairy farms. The model is driven by the energy and protein requirements of the milking cow. The objective of the model is to maximise income, after herd and feed costs, by selecting the area of the farm sown to particular forage species. Different forage species may require different animal production systems to optimise their profitability. In order to achieve this, the model can alter the herd size and structure, level of production, concentrate feeding regime and forage conservation and feeding on a monthly basis.
Tipo: Conference Paper or Presentation
Palavras-chave: Dairy cows; Modelling; Forage.; Farm Management.
Ano: 2003
URL: http://purl.umn.edu/57869

The Nexus Land-Use Model, an Approach Articulating Biophysical Potentials and Economic Dynamics to Model
Provedor de dados: Research in Agricultural & Applied Economics (AgEcon Searh)
Autores: Souty,   Francois; Brunelle,   Thierry; Dumas,   Patrice; Dorin,   Bruno; Ciais,   Philippe; Crassous,   Renaud.
Interactions between food demand, biomass energy and forest preservation are driving both food prices and land-use changes, regionally and globally. This study presents a new model called Nexus Land-Use which describes these interactions through a generic representation of agricultural intensification mechanisms. The Nexus Land-Use model equations combine biophysics and economics into a single coherent framework to calculate crop yields, food prices, and resulting pasture and cropland areas within 12 regions inter-connected with each other by international trade. The representation of cropland and livestock production systems in each region relies on three components: (i) a biomass production function derived from the crop yield response function to inputs...
Tipo: Working Paper
Palavras-chave: Land-use Change; Modelling; Global Biomass Projections; Environmental Economics and Policy; Q11; Q15.
Ano: 2012
URL: http://purl.umn.edu/122859

Methods for the Assessment of Livestock Development Interventions in Smallholder Livestock Systems
Provedor de dados: Research in Agricultural & Applied Economics (AgEcon Searh)
Autores: Rushton,   Jonathan.
This Working Paper presents a framework for assessing the impact of livestock diseases on the household economy and at local level. The framework is designed to help decision and policy makers in their selection of pro-poor livestock interventions. It should also help to protect them from making decisions under unwanted pressure from strong, non-objective political voices.  The immediate users of the assessment methods presented in the Working Paper are expected to be consultants who have to evaluate interventions on behalf of their clients. These clients may be multi and bi lateral donors and, possibly, NGOs. Other users of the output could be governments receiving aid and communities receiving support.  The author has drawn upon past experience to...
Tipo: Working or Discussion Paper
Palavras-chave: Livestock; Animal; Production; Health; Interventions; Prioritisation; Modelling; Households; Bolivia; Kenya; India; Livestock Production/Industries.
Ano: 2003
URL: http://purl.umn.edu/23769

NASYP: Online expert tool on the control of major-accident hazards involving dangerous substances
Provedor de dados: Research in Agricultural & Applied Economics (AgEcon Searh)
Autores: Kahuda,   Daniel; Vach,   Marek; Cerba,   Otakar; Krivanek,   Zbynek; Jezek,   Jan; Charvat,   Karel; Vohnout,   Premysl; Dvorak,   V.
NASYP is an online Geoportal tool being developed in cooperation with state and regional authorities to improve insufficient practices based on implementation of Directive nr. 2003/105/ES on the control of major-accident hazards involving dangerous substances. The tool is applicable for managing the permits, reporting and regular monitoring issues. Furthermore, it’s applicable for a risk assessment and a rapid management of disasters in the initial phase. There’re simple modeling tools included to simulate early stages of the contamination caused by disasters occurred to be used for decision making and effective use of emergency services. In this manner, there’re low atmospheric and surface water pollutions taken into account. For the study area, Liberec...
Tipo: Journal Article
Palavras-chave: Spatial data; Geoportal; Risk management; Modelling; Research and Development/Tech Change/Emerging Technologies; Research Methods/ Statistical Methods; Risk and Uncertainty; GA; IN.
Ano: 2011
URL: http://purl.umn.edu/116384

Opt-in of the agricultural sector to the European trading scheme for greenhouse gas emissions – a proposal and its possible effects
Provedor de dados: Research in Agricultural & Applied Economics (AgEcon Searh)
Autores: Perez Dominguez,   Ignacio; Holm-Muller,   Karin.
In light of international discussions on a possible opt-in of the agricultural sector to the current European emission trading system for greenhouse gases, the objective of this article is to present a feasible implementation strategy for a market of emission permits in European agriculture and to simulate its economic effects within the regionalised agricultural sector model CAPRI. With this purpose, we compare the effects of a 15% reduction of greenhouse gas emissions from European agriculture with and without a trading scheme. Our findings suggest that if significant emission abatement is to be achieved in the agricultural sector, efficiency gains from expanding the current emission trading scheme to this sector can be appreciable. An additional finding...
Tipo: Journal Article
Palavras-chave: Climate gas emissions; Emission trading; Abatement costs; Agricultural policy; Modelling; Agricultural and Food Policy.
Ano: 2007
URL: http://purl.umn.edu/96766

Methodological and empirical progress and challenges in integrated assessment of agricultural systems and policies
Provedor de dados: Research in Agricultural & Applied Economics (AgEcon Searh)
Autores: van Ittersum,   Martin K.; Heckelei,   Thomas; Oude Lansink,   Alfons G.J.M.; Wolf,   Joost; Kanellopoulos,   Argyris; Britz,   Wolfgang.
In this contribution we first present a methodology for integrated assessment of agricultural systems (SEAMLESS Integrated Framework), illustrate its application in an integrated assessment of high commodity prices and then discuss its flexibility and limitations. From there we take a broader view and reflect on key scientific and empirical questions with respect to the development of research tools for the integrated assessment of agricultural systems.
Tipo: Presentation
Palavras-chave: Agricultural systems; Integrated assessment; Modelling; Agricultural and Food Policy; Farm Management.
Ano: 2011
URL: http://purl.umn.edu/119329

Comparative Performance of Selected Mathematical Programming Models
Provedor de dados: Research in Agricultural & Applied Economics (AgEcon Searh)
Autores: Arriaza Balmón,   Manuel; Gomez-Limon,   Jose Antonio.
This study compares the predictive performance of several mathematical programming models. Using the cropping patterns, yields and crop gross margins of eighteen farms over a period of five years we compare the models' optimum solutions with observed crop distributions after the Reform of the EU Common Agricultural Policy of 1992. The results show that the best prediction corresponds to a model that includes expected profit and a qualitative measure of crop riskiness. The results suggest that, in order to obtain reliable predictions, the modelling of farmers' responses to policy changes must consider the risk associated with any given cropping pattern. Finally, we test the ability of the proposed model to reproduce the farmers' observed behaviour with...
Tipo: Conference Paper or Presentation
Palavras-chave: Model performance; Mathematical programming; Modelling; Decision-making; Resource /Energy Economics and Policy.
Ano: 2002
URL: http://purl.umn.edu/24792

Whole farm analysis-Fertiliser nitrogen can reduce deep drainage and increase profitability
Provedor de dados: Research in Agricultural & Applied Economics (AgEcon Searh)
Autores: Scott,   J. Fiona.
Opportunity cropping has been shown to reduce mean annual deep drainage compared to long fallow systems. A question that remained was the effect of added fertiliser nitrogen under each of the cropping systems and whether it would make a significant difference to amounts of deep drainage and to profitability. Estimates of crop yield and deep drainage results were generated using the APSLM (Agricultural Production Systems Simulator) cropping systems model, to compare long-fallow wheat/sorghum and two opportunity-cropping scenarios on a vertosol on the Liverpool Plains using rainfall data from 1958 to 1997. The results showed that fertiliser nitrogen did have a significant effect on deep drainage and gross margin under each cropping system. However, higher...
Tipo: Conference Paper or Presentation
Palavras-chave: Cropping systems; Profitability; Modelling; Variability; Whole farm budgeting; Farm Management; Land Economics/Use.
Ano: 2004
URL: http://purl.umn.edu/59705

Analyse de la Reponse de l'offre des Pommes en Tunisie : Une Approche Econometrique
Provedor de dados: Research in Agricultural & Applied Economics (AgEcon Searh)
Autores: Laajimi,   Abderraouf; Guesmi,   Anis; Dhehibi,   Boubaker.
In Tunisia, the apples occupy a significant place on the sector of perennial crops. This crop covered expanded areas during the eighties following an extensive use of efficient water equipments. However, significant seasonal and annual variation of fruit supplies in the domestic market were frequently encountered affecting prices at both wholesale and consumption levels. To study the supply response of apples we carried out an econometric estimate of the model of supply response. Modelling was carried out in two stages: determination of the variation of the surfaces, on the basis of equation of news plantations and the equation of removals, and the variation of yields. The methodological approach that we followed takes account of the characteristics and...
Tipo: Conference Paper or Presentation
Palavras-chave: Supply response; Modelling; Expected prices; Apples; Demand and Price Analysis.
Ano: 2007
URL: http://purl.umn.edu/9392

Combining non-modelling and modelling approaches for the evaluation of RD policy: study of the impact of modulation as a policy instrument
Provedor de dados: Research in Agricultural & Applied Economics (AgEcon Searh)
Autores: Nowicki,   Peter.
Two separate, but interlinked methodological approaches – the modelling approach and non-modelling approach – have been used in a study commissioned by DG Agriculture and Rural Development to understand the impact of Modulation. In these two approaches a range of methodological and analytical tools are used, as follows:  Non-modelling Approach  • Literature Review;  • Case Studies carried out in eight Member States;  • Questionnaires carried out by telephone interviews in the 19 Member States, in which case studies were not conducted;  • CMEF Indicators – collation of information on output, result and impact indicators for the case study Member States.  Modelling Approach:  • Budget model, tailor made for the project, provides much of the financial detail...
Tipo: Conference Paper or Presentation
Palavras-chave: Rural development policy evaluation; Modelling; Non-modelling; Modulation; Community/Rural/Urban Development.
Ano: 2010
URL: http://purl.umn.edu/94893

A review of Multi-Agent Simulation Models in Agriculture
Provedor de dados: Research in Agricultural & Applied Economics (AgEcon Searh)
Autores: Kaye-Blake,   William; Li,   Frank Y.; Martin,   A. McLeish; McDermott,   Alan; Neil,   Hayley; Rains,   Scott.
Multi-Agent Simulation (MAS) models are intended to capture emergent properties of complex systems that are not amenable to equilibrium analysis. They are beginning to see some use for analysing agricultural systems. The paper reports on work in progress to create a MAS for specific sectors in New Zealand agriculture. One part of the paper focuses on options for modelling land and other resources such as water, labour and capital in this model, as well as markets for exchanging resources and commodities. A second part considers options for modelling agent heterogeneity, especially risk preferences of farmers, and the impacts on decision-making. The final section outlines the MAS that the authors will be constructing over the next few years and the types of...
Tipo: Conference Paper or Presentation
Palavras-chave: Multi-agent simulation models; Modelling; Agent-based model; Cellular automata; Decision-making; Crop Production/Industries; Environmental Economics and Policy; Farm Management; Land Economics/Use; Livestock Production/Industries.
Ano: 2009
URL: http://purl.umn.edu/97165

Participatory Modelling and Decision Support for Natural Resources Management in Climate Change Research
Provedor de dados: Research in Agricultural & Applied Economics (AgEcon Searh)
Autores: Giupponi,   Carlo; Mysiak,   Jaroslav; Sgobbi,   Alessandra.
The ever greater role given to public participation by laws and regulations, in particular in the field of environmental management calls for new operational methods and tools for managers and practitioners. This paper analyses the potentials and the critical limitations of current approaches in the fields of simulation modelling (SM), public participation (PP) and decision analysis (DA), for natural resources management within the context of climate change research. The potential synergies of combining SM, PP and DA into an integrated methodological framework are identified and a methodological proposal is presented, called NetSyMoD (Network Analysis – Creative System Modelling – Decision Support), which aims at facilitating the involvement of...
Tipo: Conference Paper or Presentation
Palavras-chave: Modelling; Public Participation; Natural Resource Management; Policy; Decision-Making; Governance; DSS; Resource /Energy Economics and Policy; Q5.
Ano: 2008
URL: http://purl.umn.edu/6375

The Estimation of Food Demand Elasticities in Canada
Provedor de dados: Research in Agricultural & Applied Economics (AgEcon Searh)
Autores: Pomboza,   Ruth; Mbaga,   Msafiri Daudi.
Changing consumer and market demands is an important driver behind the challenges and opportunities that are facing the agriculture and agri-food sector in Canada and that will influence the sector's profitability and competitiveness in the future. It is therefore important to understand developments in the consumer demand for agriculture and agri-food products. The report provides updated demand elasticities for fourteen food groups in Canada. The estimates are useful for conducting analysis of the changing structure of the agriculture and agri-food sector and can help quantify the impacts that changes in economic variables and policies that impact those economic variables might have.
Tipo: Report
Palavras-chave: Food; Demand; Demand analysis; Elasticities; Price elasticities; Cross price elasticities; Income elasticities; Price; Econometric; Modelling; Agribusiness; Agricultural and Food Policy; Consumer/Household Economics; Crop Production/Industries; Demand and Price Analysis; Financial Economics; Food Consumption/Nutrition/Food Safety; Food Security and Poverty; Health Economics and Policy; Labor and Human Capital; Land Economics/Use; Livestock Production/Industries; Marketing; Production Economics; Public Economics.
Ano: 2007
URL: http://purl.umn.edu/52705

Welfare distribution between EU Member States through different national decoupling options. Implications for Spain
Provedor de dados: Research in Agricultural & Applied Economics (AgEcon Searh)
Autores: Dominguez,   Ignacio Perez; Wieck,   Christine.
SUMMARY: This paper makes use of an agricultural sector model to analyse welfare effects derived from different national implementation options of the CAP Reform 2003. It shows that agricultural prices developed more favourable in a full premium decoupling scenario, since agricultural production declines more pronounced compared to a partial decoupling scenario. The use of the partial decoupling mechanism helps Member States to distribute income into less favoured areas but is not the optimal policy choice. However, if other Member States follow the same path of reform, a "prisoner's dilemma" will most likely be observed: partial decoupling appears as the preferred option for individual Member States, since high domestic production and high producer prices...
Tipo: Journal Article
Palavras-chave: Common Agricultural Policy; Partial equilibrium analysis; Modelling; Decoupling; Welfare analysis.; Agricultural and Food Policy; C61; D60; Q18.
Ano: 2006
URL: http://purl.umn.edu/8005

Sheep enterprises—what are the differences?
Provedor de dados: Research in Agricultural & Applied Economics (AgEcon Searh)
Autores: Graham,   Phil; White,   A.
Difficult seasonal conditions during the last six years have placed many farms under significant financial pressure. Producers have been looking for enterprise changes which will quickly improve their profits. New breeds have increased the options available, but there is rarely any local production data for them. Information in the media has done little more than create confusion about the true differences between sheep enterprises. Modelling allows this complex question to be looked at in a logical fashion and combines production and financial factors in the comparison. GrassGro® was used at two locations in southern NSW, Yass and Cowra, for the period 1960 to 2007. The results indicated that no enterprise performed consistently better based on profit per...
Tipo: Article
Palavras-chave: Sheep enterprises; Modelling; GrassGro®; Profitability; Farm Management.
Ano: 2010
URL: http://purl.umn.edu/120870

MAKING SENSE OF AGRICULTURAL TRADE POLICY REFORM
Provedor de dados: Research in Agricultural & Applied Economics (AgEcon Searh)
Autores: Vanzetti,   David; Peters,   Ralf.
Proposals for agricultural trade reform put forward by the main protagonists remain far apart, with little sign of convergence.  In an attempt to progress the negotiations towards a successful outcome, the chairman of the WTO Committee on Agriculture has proposed a compromise.  The alternative proposals by the United States, the European Union and the WTO are analysed with the Agricultural Trade Policy Simulation Model, a static, multi-commodity, multi-region, partial equilibrium trade model.  The estimated annual global welfare gains are $26 billion, $12 billion and $17 billion respectively.  Least developed countries, as a group, gain from the US proposal but are made worse off under the WTO and EU proposals.  Furthermore, in the best case many...
Tipo: Conference Paper or Presentation
Palavras-chave: Agriculture; Trade; Modelling; Negotiations; International Relations/Trade; F13; Q17.
Ano: 2003
URL: http://purl.umn.edu/25858

Modelling the Dynamics of Weed Management Technologies
Provedor de dados: Research in Agricultural & Applied Economics (AgEcon Searh)
Autores: Jones,   Randall E.; Cacho,   Oscar J.; Sinden,   Jack A.
An appropriate economic framework for valuing the benefits of weed management technologies is to treat weeds as a renewable resource stock problem. Consequently, the weed seed bank is defined as a renewable resource that changes through time due to management and seasonal conditions. The goal of decision-makers is to manage this (negative) resource so as to maximise returns over some pre-specified period of time. A modelling framework is presented for evaluating the biological and economic effects of weed management. The framework includes population dynamics, water balance, crop growth, pasture growth and crop/pasture rotation models for measuring the physical interactions between weeds and the environment. These models link in with numerical optimal...
Tipo: Conference Paper or Presentation
Palavras-chave: Weeds; Modelling; Dynamic analysis.; Land Economics/Use.
Ano: 2003
URL: http://purl.umn.edu/57902

Extraction of soil water by plants: development and validation of a model
Provedor de dados: Revista Brasileira de Ciência do Solo
Autores: de Jong van Lier,Q.; Libardi,P. L.
A quantitative model of water movement within the immediate vicinity of an individual root is developed and results of an experiment to validate the model are presented. The model is based on the assumption that the amount of water transpired by a plant in a certain period is replaced by an equal volume entering its root system during the same time. The model is based on the Darcy-Buckingham equation to calculate the soil water matric potential at any distance from a plant root as a function of parameters related to crop, soil and atmospheric conditions. The model output is compared against measurements of soil water depletion by rice roots monitored using γ-beam attenuation in a greenhouse of the Escola Superior de Agricultura "Luiz de...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Modelling; Soil water depletion; Soil water extraction.
Ano: 1997
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06831997000400002

Critical levels for soil attributes in irrigated banana plantations in semiarid region
Provedor de dados: Revista Brasileira de Engenharia Agrícola e Ambiental
Autores: Maia,Celsemy E.; Morais,Elis R. C. de.
ABSTRACTThis study aimed to estimate the critical levels for soil chemical attributes through the criterion of reduced continuous probability distribution (NCRIz) in areas under irrigated banana cultivation and evaluate soil fertility of low-yield areas in the Apodi Plateau. A dataset composed of analysis of 60 producing areas and their respective yields was used. It was concluded that the method can be used to obtain critical levels for soil chemical attributes and the critical levels obtained for the irrigated areas under banana cultivation corresponded to 7.2 for pH, 0.91 g kg-1 for N, 0.31, 6.34, 2.63, 1.42 and 25.76 mg kg-1 for Cu, Fe, Mn, Zn and P, respectively, and 6.43, 1.14, 0.24 and 0.36 cmolc kg-1 for Ca, Mg, Na and K, respectively. In the...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Soil fertility; Modelling; Musa spp.
Ano: 2015
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-43662015001000926

Hydrodynamic changes of the soil-cactus interface, effective actual evapotranspiration and its water efficiency under irrigation
Provedor de dados: Revista Brasileira de Engenharia Agrícola e Ambiental
Autores: Morais,José E. F. de; Silva,Thieres G. F. da; Queiroz,Maria G. de; Araújo,Gherman G. L. de; Moura,Magna S. B.; Araújo Júnior,George do N.
ABSTRACT The knowledge on soil water dynamics is the basis of crop water management. The soil water balance (SWB) method is used for this purpose. However, its application in cactus may lead to misinterpretation in water efficiency analysis, since it does not consider the amount of water retained in the plant (WRP). This study aimed to evaluate SWB applicability, hydrodynamic changes and water efficiency of forage cactus clones under irrigation. The clones ‘Orelha de Elefante Mexicana’ (OEM), ‘IPA Sertânia’ (IPA) and ‘Miúda’ (MIU) were submitted to irrigation depths (2.5, 5.0 and 7.5 mm) and frequencies (7, 14 and 28 days), in Serra Talhada, PE, Brazil, between March 2012 and August 2013. The SWB was applied, by adding the WRP in the estimate of the...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Water retained in the plant; Soil water balance; Cactus; Modelling.
Ano: 2017
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-43662017000400273

Evaluation of mathematical equations for estimating leaf area in rapeseed
Provedor de dados: Revista Ciência Agronômica (RCA)
Autores: Dalmago,Genei Antonio; Bianchi,Cleusa Adriane Menegassi; Kovaleski,Samuel; Fochesatto,Elizandro.
ABSTRACT The aim of this study was to evaluate estimations of leaf area in rapeseed (Brassica napus L.) and the potential for application to different genotypes, environmental conditions and types of crop management. In experiments conducted during 2013, 2014, 2016 and 2017, three genotypes of rapeseed, five doses of nitrogen and three sowing dates were used. Leaves were randomly collected from different plants and positions on the plants. The leaf area (LA), and maximum width (W) and length (L) were determined for each leaf, and the product of L and W (LxW) was calculated. Fifty-six equations for estimating LA in rapeseed, where the independent variables were W, L or LxW, were compiled from the bibliography and evaluated in this work. The evaluation was...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Brassica napus; Colza; Modelling; Leaf area index.
Ano: 2019
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1806-66902019000300420

Estimation of leaf area index in the sunflower as a function of thermal time1
Provedor de dados: Revista Ciência Agronômica (RCA)
Autores: Lucas,Dioneia Daiane Pitol; Heldwein,Arno Bernardo; Hinnah,Fernando Dill; Maldaner,Ivan Carlos; Loose,Luis Henrique.
The aim of this study was to obtain a mathematical model for estimating the leaf area index (LAI) of a sunflower crop as a function of accumulated thermal time. Generating the models and testing their coefficients was carried out using data obtained from experiments carried out for different sowing dates in the crop years of 2007/08, 2008/09, 2009/10 and 2010/11 with two sunflower hybrids, Aguará 03 and Hélio 358. Linear leaf dimensions were used for the non-destructive measurement of the leaf area, and thermal time was used to quantify the biological time. With the data for accumulated thermal time (TTa) and LAI known for any one day after emergence, mathematical models were generated for estimating the LAI. The following models were obtained, as they...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Helianthus annuus; Leaf analysis; Modelling.
Ano: 2015
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1806-66902015000200404

Empirical models to predict feed intake of growing-finishing pigs reared under high environmental temperatures
Provedor de dados: Scientia Agricola
Autores: Perondi,Dani; Kipper,Marcos; Andretta,Ines; Hauschild,Luciano; Lunedo,Raquel; Franceschina,Carolina Schell; Remus,Aline.
ABSTRACT Several empirical models were proposed to predict feed intake (FI) of growingfinishing pigs reared under high environmental temperatures. However, these models have not been evaluated under conditions different from those in which they were developed. Twelve empirical models were evaluated using a database built after systematic literature review (observed data: 28 studies in which the FI was evaluated in pigs under high environmental temperatures). Model accuracy was assessed using the mean squared of prediction error (MSPE). Analyses were performed considering two scenarios: (1) general population, where all observed data were used in the simulation; (2) reference population, where data were filtered in order to simulate only scenarios with...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Consumption; Heat stress; Modelling; Precision feeding; Swine.
Ano: 2018
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162018000400296

Meta-analysis of individual and combined effects of mycotoxins on growing pigs
Provedor de dados: Scientia Agricola
Autores: Andretta,Ines; Kipper,Marcos; Hauschild,Luciano; Lehnen,Cheila Roberta; Remus,Aline; Melchior,Raquel.
ABSTRACT Little is known about the toxicity of concomitantly occurring mycotoxins in pig diets. This study was conducted to evaluate, through meta-analysis, the individual and the combined effects of mycotoxins on pig performance. The meta-analysis followed three sequential analyses (graphical, correlation, and variance-covariance) based on a database composed of 85 published papers, 1,012 treatments and 13,196 animals. Contamination of diets with individual mycotoxins reduced (p &lt; 0.05) feed intake by 14 % and weight gain by 17 %, while combined mycotoxins reduced the same responses by 42 % and 45 %, respectively, in comparison with the non-challenged group. The correlation (p &lt; 0.05) between reduction in weight gain (ΔG) and reduction in feed...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Modelling; Sanitary challenge; Swine; Toxicology.
Ano: 2016
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162016000400328

Changes in soil organic matter under different land management in misiones province (Argentina)
Provedor de dados: Scientia Agricola
Autores: Piccolo,Gabriel Agustín; Andriulo,Adrián Enrique; Mary,Bruno.
Highly weathered tropical soils rapidly loose soil organic matter (SOM) and may be affected by water erosion and soil compaction after deforestation and intensive cultivation. With the main objective to estimate the SOM balances in a subtropical soil we determined the dynamics of SOM in a degraded yerba mate (Ilex paraguaiensis Saint Hil.) plantation introduced after deforestation and with elephant grass (Pennisetum purpureum L.) as a cover crop. The study site was in Misiones, Argentina, and we use the natural 13C abundance methodology and a descriptive model. The study was conducted on three contiguous 50 x 100 m plots of a typic Kandihumult soil with: (i) native forest, (ii) 50 years of continuous yerba mate monoculture with intensive tillage, and (iii)...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Ilex paraguaiensis; Pennisetum purpureum; Natural 13C abundance; Soil carbon; Modelling.
Ano: 2008
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162008000300009

Estimation of leaf nutrient concentration from hyperspectral reflectance in Eucalyptus using partial least squares regression
Provedor de dados: Scientia Agricola
Autores: Oliveira,Luiz Felipe Ramalho de; Santana,Reynaldo Campos.
ABSTRACT: Leaf hyperspectral reflectance has been used to estimate nutrient concentrations in plants in narrow bands of the electromagnetic spectrum. The aim of this study was to estimate leaf nutrient concentrations using leaf hyperspectral reflectance and verify the variable selection methods using the partial least squares regression (PLSR). Two studies were carried out using stands with Eucalyptus clones. Study I was established in Eucalyptus stands with three clones, classifying leaves into five colour patterns using the Munsell chart for plant tissues. Immediately after leaf collection, leaf reflectance was read and the chemical analysis was performed. Study II was carried out in commercial clonal stands of Eucalyptus performing the same leaf...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Remote sensing; Tree monitoring; Modelling; Variable selection.
Ano: 2020
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162020000601402

Allometric equations for total, above- and below-ground biomass and carbon of the Amazonian forest type known as campinarana
Provedor de dados: Acta Amazonica
Autores: WOORTMANN,Cecilia P.I.B.; HIGUCHI,Niro; SANTOS,Joaquim dos; SILVA,Roseana P. da.
ABSTRACT The Amazon forest comprises many different forest types, amongst them are campinas and campinaranas, which occur on Amazonian sandy soils, representing 2.65% of Amazonian territory. An understanding of the ecology and quantification of the environmental goods and services of campinaranas is key to their conservation. Based on a direct method to estimate biomass and carbon content of campinarana, we harvested and weighted 89 trees and other forest components in ten randomly allocated plots of 100 m2 (10 x 10 m) and 11 additional trees outside the plots. The data allowed us to describe how biomass is distributed amongst campinarana vegetation and amongst tree compartments. We developed allometric equations to estimate the total, above- and...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Modelling; Forests on sand; Climate change.
Ano: 2018
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0044-59672018000200085

Adjusting weight growth curve of male quails Coturnix japonica reared in the semi-arid region of the State of Pernambuco
Provedor de dados: Acta Scientiarum: Animal Sciences
Autores: Lucena, Leandro Ricardo Rodrigues de; Holanda, Marco Aurélio Carneiro de; Holanda, Mônica Calixto Ribeiro de; Anjos, Marcelo Lopes dos.
This study adjusted different regression models to describe the growth pattern of meat quails from birth to 42 days of age. Data of 300 male quails were used. Weight and height information of all quails were collected weekly from the 1st to the 42nd day of age. Body weight of poultry was subjected to the polynomial, logistic, Gompertz, Weibull, and log-normal regression models. The criteria used to choose the best model to explain the growth curve of quails were the coefficient of determination of the model, Akaike’s information criterion, sum of squared residuals and Willmott’s index. For all the models used, the variables age and height were significant to explain the weight of quails. The polynomial (R² = 99.99%, AIC = 24.68, SSR = 27.5, d = 0.9999) and...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Modelling; Poultry; Regression model.
Ano: 2018
URL: http://periodicos.uem.br/ojs/index.php/ActaSciAnimSci/article/view/42563

Finite modelling of growth and yield of okra using different tillage systems in Obubra, Nigeria
Provedor de dados: Agricultural Engineering International : The CIGR e-journal
Autores: Odey, Simon Ogbeche.
Abstract:  Field experiment was conducted at the teaching and research farm of Cross River University of Technology, Faculty of Agriculture and Forestry, Obubra Campus. The study was aimed at finite modelling of growth and yield of Okra (Abelmoschus esculentus L.) using different tillage systems. Randomised Complete Block Design (RCBD) was used in the field, 1,024m2 with three treatments and three replicates. These treatments were Conventional, Conservative and Zero tillage. Each treatment had three replicates of size 8m x 8m, separated from each other by 2m for manoeuvring of the tractor. Planting of okra and other cultural practices were carried out. Soil samples were collected for analysis in the laboratory. Data on growth parameters and yield of okra...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Finite; Modelling; Growth; Yield; Okra; Tillage Systems; Soil.
Ano: 2022
URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/7067

Prediction of tractive force model for disc harrowing using sensitivity analysis
Provedor de dados: Agricultural Engineering International : The CIGR e-journal
Autores: Nkakini, Silas Ovua; Douglas, I. E.
In this study, a comparative evaluation of tractive force models for disc harrowing, at different tillage speeds was carried out in order to determine optimal tillage speeds.  The predictive models were developed using dimensional analysis.  The tillage operation in a loamy sand soil, at tillage speeds of 1.94 m s-1, 2.22 m s-1 and 2.5 m s-1 respectively was conducted, using trace tractor techniques.  Parameters such as drawbar pull, rolling resistance, wheel slip, moisture content, cone index, wheel numeric, contact pressure, speed, width of harrow, depth of harrow, and tractive force were measured.  The developed mathematical models describing the tractors tyre-soil interactions parameters were evaluated using sensitivity analysis of the measured...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Predictive; Tractive force; Disc harrowing; Tillage; Loamy; Sand; Soil; Modelling; Sensitivity measurement; Soil   moisture.
Ano: 2013
URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/2374

Engineered solutions for animal heat stress abatement in livestock buildings.
Provedor de dados: Agricultural Engineering International : The CIGR e-journal
Autores: Arcidiacono, Claudia.
Heat stress in animal housing is one of the drivers affecting animal productivity and welfare in hot climates, and causing consequent reduced profits for the farmers. The main challenges that livestock breeding faces in hot climates regards how to foster, improve, and assess methods and strategies for animal heat stress abatement. Research studies in this field have generally proposed modifications in herd management and in feeding strategies, breed selection, and engineered solutions aimed at exploiting heat transmission phenomena. In this paper, the most recent engineered solutions for animal heat stress abatement in livestock buildings have been reviewed and described; they have involved new building and ventilation design and modelling, and improved...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Rural buildings livestock buildings; Design; Modelling; Ventilation; Hot climate.
Ano: 2018
URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/4705

Evaluation of Energy Consumption Pattern in Rice Processing Using Taguchi and Artificial Neural Network Approaches
Provedor de dados: Agricultural Engineering International : The CIGR e-journal
Autores: SANUSI, Mayowa Saheed; Akinoso, Rahman.
This study was designed to evaluate and model the impacts of processing parameters (steaming time, soaking time, paddy moisture content and soaking temperature) on the energy consumption of five rice varieties (NERICA 8, FARO 52, FARO 61, FARO 60 and FARO 44). Energy consumption in the cleaning, soaking, steaming, drying, dehusking, polishing and grading operations were estimated by fitting data on labour, fuel and electricity consumption, time and machine efficiency into standard equations to determine total energy consumption. The energy consumptions were separately modelled using Taguchi and Artificial Neural Network (ANN) techniques for each rice variety. The accuracy of models was determined using the coefficient of determination (R2) and Mean Square...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Artificial neural network; Energy Consumption; Modelling; Rice varieties; Taguchi.
Ano: 2022
URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/7235

Measured Energy use in a Greenhouse with Tomatoes Compared to Predicted use by a Mechanistic Model Including Transpiration
Provedor de dados: Agricultural Engineering International : The CIGR e-journal
Autores: Sven Nimmermark.
In regions with a colder climate the use of heat energy for climatization of greenhouses can be significant. Beside outdoor temperatures and climate also transpiration affects the use of heat energy since heating and ventilation or dehumidification may be required in order to keep the humidity in the greenhouse below levels which may lead to plant diseases. A reliable model is a powerful tool to predict energy use for greenhouse cultivation. Thus, a mechanistic model including transpiration and energy use for dehumidification and hourly output data was developed from an older simpler model. To be reliable, modelled data must fit with real data. The aim of the present study is to compare measured and modelled use of heat energy. Thus, energy use for a...
Palavras-chave: Greenhouses; Energy; Measurements; Modelling.
Ano: 2015
URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/3100

Modelling of the rotational - vibration generator for the flow fruit detachers
Provedor de dados: Agricultural Engineering International : The CIGR e-journal
Autores: Ishpekov, Stoyan Savov.
The investigation aims at modelling the dynamics of rotational vibration generator, which is widely used for driving flow fruit detachers at harvesting of many crops like grape, tomatoes, blueberries, raspberries, chokeberry, black currant, sesame seeds etc. The research on this model has been digitally performed by software, written in FORTRAN and by using the LabView environment as input-output interface. Identification of unknown model coefficients has been carried and their influence upon precision of the model has been determined. The effect of vibration generator parameters upon its dynamic characteristics has been defined. The synthesized model reaches a relative error for the carrier angular amplitude of 0.48 % compared to the one, determined by an...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Agricultural engineering flow fruit detacher; Rotation vibration generator; Modelling.
Ano: 2018
URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/3940

Fuel consumption models of MF285 tractor under various field conditions
Provedor de dados: Agricultural Engineering International : The CIGR e-journal
Autores: Almaliki, Salim; Alimardani, Reza; Omid, Mahmoud.
Due to the ascending importance of energy in the world, prediction and optimization of Fuel Consumption (FC) in agricultural tasks is merit to consideration. In this study a Massey Ferguson (MF285) tractor was implemented with a low cost and precise data acquisition system as a means to record and monitor the affectual parameters on FC such as forward speed and instant fuel flow rate during field operation. Field experiments were carried out in the experimental farm of Agricultural Engineering Department of Tehran University, Karaj province, Iran, which had loamy soil texture. A mouldboard plow was used as tillage toll during the experiments at various tillage depths, engine speeds, forward speeds, tire inflation pressures, moisture contents and cone...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Fuel consumption; Massey Ferguson (MF285); Modelling; Data logging system.
Ano: 2016
URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/3776

Calibrating and validating AquaCrop model for maize crop in Northern zone of Nigeria
Provedor de dados: Agricultural Engineering International : The CIGR e-journal
Autores: Ezekiel, Oiganji; Igbadun, H. E.; Mudiare, O.J.; Oyebode, M.A.
Farmers in the northern Guinea Savannah ecological zone of Nigeria have been experiencing declining crop yield due to erratic water supply. In recent times, research on better water management and interaction between effects of climate, soil and field management on crop production is fast gaining grounds with the use of models. Models can be used to predict the impact of long-term climate variability, thus providing an opportunity of better techniques compared with the traditional multi-location trials. This study presents the calibration and validation of AquaCrop model for drip irrigated maize (Zea mays). Calibration was done using data of 2013, while validation across seasons was done with data of 2014. The modelling efficiency of grain yield, biomass...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Agricultural Engineering/ soil and water conservation engineering growth stage; Deficit irrigation; Drip irrigation; Water management; Modelling.
Ano: 2016
URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/3755

Performance evaluation of hybrid thin layer solar tunnel-windmill dryer in the drying of brined and non-brined Tafi (Siganussutor) Fish
Provedor de dados: Agricultural Engineering International : The CIGR e-journal
Autores: Odote, Peter; Kituu, Gareth M.; Obiero, Maurice; Ruwa, R; Honell, N H.
Studies were carried out to evaluate the performance of hybrid solar tunnel-windmill dryer in thin layer drying of brined and non-brined Tafi (Siganus spp.) fish. The fish were, eviscerated, and split into pieces of approximately 6cm by 4cm by 5mm was soaked in brine at 0 and 5% concentrations. The samples were dried in the dryer for 44 hours. The moisture content of the drying fish was evaluated by the AOAC oven drying procedure. In addition, analysis was carried out to establish the best thin layer drying model that describes the drying of fish in the hybrid wind-solar tunnel dryer. The moisture content of the drying fish was found to reduce linearly from 4.2 and 3.9kg/kg (db), respectively for brined and non-brined fish to 0.8kg/kg (db).  A two way...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Agricultural Engineering; Food Science and Technology Fish; Hybrid wind-solar tunnel dryer; Diffusivity; Modelling; Moisture content; Drying rate constant.
Ano: 2015
URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/3093

Moisture sorption isotherms and thermodynamic properties of Asteriscus graveolens leaves
Provedor de dados: Agricultural Engineering International : The CIGR e-journal
Autores: Saad, Amel; Touati, Boumediene; Draoui, Belkacem; Tabti, Boufeldja; Abdenebi, Asma; Mir, Krima.
Asteriscus graveolens is a medicinal and aromatic plant which has been used to treat several diseases.Moisture equilibrium data of the plant leaves were determined by using the gravimetric static method at 30°C, 40°C, and 50°C for water activity (
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Moisture sorption; Isotherm; Asteriscus graveolens; Isosteric heat; Modelling.
Ano: 2016
URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/3585

Measured Energy use in a Greenhouse with Tomatoes Compared to Predicted use by a Mechanistic Model Including Transpiration
Provedor de dados: Agricultural Engineering International : The CIGR e-journal
Autores: Nimmermark, Sven.
In regions with a colder climate the use of heat energy for climatization of greenhouses can be significant. Beside outdoor temperatures and climate also transpiration affects the use of heat energy since heating and ventilation or dehumidification may be required in order to keep the humidity in the greenhouse below levels which may lead to plant diseases. A reliable model is a powerful tool to predict energy use for greenhouse cultivation. Thus, a mechanistic model including transpiration and energy use for dehumidification and hourly output data was developed from an older simpler model. To be reliable, modelled data must fit with real data. The aim of the present study is to compare measured and modelled use of heat energy. Thus, energy use for a...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Greenhouses; Energy; Measurements; Modelling.
Ano: 2015
URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/3100

Modelling mass transfer during water absorption of  closed mouth pistachios
Provedor de dados: Agricultural Engineering International : The CIGR e-journal
Autores: Kouchakzadeh, Ahmad; Tajri, Behnam.
This study was undertaken to analyze the kinetics of water absorption and to derive an equation for the rate at which water is absorbed by closed mouth pistachios.  We used Kaleh_ghoochi, the major variety of Iranian pistachios.  The water-absorption rate equation of closed mouth pistachios between 5°Cand 25°Cwas presumed based on the Peleg equation.  The Peleg coefficients k1 and k2 were negligible changed with water temperature depending on the product and can be useful in estimating approximate immersing time and temperature for splitting mouth of pistachios.
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Pistachios; Water absorption; Peleg equation; Modelling.
Ano: 2017
URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/3907

Crop yield estimation using satellite images: comparison of linear and non-linear models
Provedor de dados: Agriscientia
Autores: Sayago,S; Bocco,M.
Development of models for crop yield prediction using remote sensing allows accurate, reliable and timely estimations over large areas. Particularly, this information is necessary to ensure the adequacy of a nation's food supply as well as to aid policy makers and farmers. In Argentina, soybean (Glycine max (L.) Merr.) and corn (Zea mays L.) are the most important crops. The goal of this research was to develop and evaluate linear and non-linear models to estimate crop yield from satellite data. Particularly, we proposed and applied those models to obtain soybean and corn yield in the central region of Córdoba (Argentina) using Landsat and SPOT images. The models were designed taking into account all or some bands included in the images from one or both...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Neural networks; Multiple linear regression; Soybean; Corn; Modelling.
Ano: 2018
URL: http://www.scielo.org.ar/scielo.php?script=sci_arttext&pid=S1668-298X2018000100001

Robust volumetric models for supporting the management of secondary forest stands in the Southern Brazilian Atlantic Forest
Provedor de dados: Anais da Academia Brasileira de Ciências
Autores: OLIVEIRA,LAIO Z.; KLITZKE,ALINE R.; FANTINI,ALFREDO C.; ULLER,HEITOR F.; CORREIA,JEAN; VIBRANS,ALEXANDER C.
Abstract The majority of Atlantic Forest fragments in Southern Brazil are second-growth forests dominated by fast-growing species with considerable market-value timber. Nevertheless, volume prediction models are scarce, especially to estimate tree total volume (i.e., stem plus branches). This study approached the issue through the following aims: to fit and select stem and total volume models (generic and species-specific) using data from 288 harvested trees in a management operation, and to fit generic and species-specific bark factors. The power model embedding diameter at breast height (D) and tree stem or total height (H) presented the greatest prediction strength for both stem and total tree volume. Models including only D to predict total tree volume...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Forest inventory; Mata Atlântica; Modelling; Regression.
Ano: 2018
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652018000703729

Trophic dynamics (Dissolved Inorganic Nitrogen-DIN and Dissolved Inorganic Phosphorus-DIP) in tropical urban estuarine systems during periods of high and low river discharge rates
Provedor de dados: Anais da Academia Brasileira de Ciências
Autores: NORIEGA,CARLOS; ARAUJO,MOACYR; FLORES-MONTES,MANUEL; ARAUJO,JULIA.
Abstract: This paper focused on the use of the biogeochemical LOICZ (Land Ocean Interactions in the Coastal Zone) to investigate the dynamics of DIN and DIP nutrients among three highly urbanized tropical estuaries (Barra das Jangadas (BJ), Recife (RE) and Timbó (TB)), located in the northeastern region of Brazil. The input data were obtained through in situ measurements (2007) and governmental agency databases (2001-2007). The balances of the non-conservative elements showed that the RE and TB systems alternated between sources and sinks during the observation periods (0.2-0.8 mmoles DIP m-2 d-1 and 0.1-10 mmoles DIN m-2 d-1). The metabolism rates in the systems indicated that the BJ system was autotrophic during the two observation periods (10-26 mmoles...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Nutrients dynamics; Estuarine; Eutrophication; Modelling; Brazil.
Ano: 2019
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652019000300502

Ultrasonic pretreatment of carrot slices: Effects of sonication source on drying kinetics and product quality
Provedor de dados: Anais da Academia Brasileira de Ciências
Autores: YILMAZ,BURCIN; CAKMAK,HULYA; TAVMAN,SEBNEM.
Abstract: In this study effects of ultrasonic pretreatment with different sonication sources on drying behavior of carrot slices were evaluated. Fresh carrot slices were pretreated with ultrasonic probe at 65, 75 and 85 W or ultrasonic bath at 10, 20 and 30°C for 3, 5 and 10 min before air drying. Water gain % and solid loss % of pretreated samples were calculated and color values, β-carotene content and rehydration ratios of dried samples were determined. Drying behavior of the pretreated samples was evaluated and the drying data were fitted to thin layer drying models. Constant drying rate period was not observed for the carrot slices; however two definite falling-rate periods having different slopes were obtained. Drying time was significantly reduced...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Carrot; Ultrasound; Β-carotene; Rehydration; Modelling.
Ano: 2019
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652019000500905

Potato potential yield based on climatic elements and cultivar characteristics
Provedor de dados: Bragantia
Autores: Pereira,André Belmont; Villa Nova,Nilson Augusto; Ramos,Valdir Josué; Pereira,Antonio Roberto.
There is currently a great deal of interest in estimating crop productivity as a function of climatic elements by means of different crop weather models. An agrometeorological model is presented based on carbon dioxide assimilation maximum rates for C3 plants, fraction of photosynthetically active radiation, air temperature, photoperiod duration, and crop parameters under tropical climate conditions. Such crop parameters include leaf area and harvest indexes, dry matter content of potato tubers, and crop cycles to estimate potato potential yields. Field data from observed productivity obtained with the cultivar Itararé (IAC-5986), grown under adequate soil water supply conditions at four different regions in the State of São Paulo (Itararé, Piracicaba,...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Modelling; Solanum tuberosum L.; Climatic elements; Crop indexes; Yield.
Ano: 2008
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052008000200008

Kinetics and Thermodynamics of Thermal Inactivation of β-Galactosidase from Aspergillus oryzae
Provedor de dados: Brazilian Archives of Biology and Technology
Autores: Klein,Manuela Poletto; Sant’Ana,Voltaire; Hertz,Plinho Francisco; Rodrigues,Rafael Costa; Ninow,Jorge Luiz.
ABSTRACT For optimization of biochemical processes in food and pharmaceutical industries, the evaluation of enzyme inactivation kinetic models is necessary to allow their adequate use. Kinetic studies of thermal inactivation of β-galactosidase from Aspergillus oryzae were conducted in order to critically evaluate mathematical equations presented in the literature. Statistical analysis showed that Weibull model presented the best adequacy to residual enzymatic activity data through the processing time and its kinetic parameters as a function of the temperature, in the range of 58-66 ºC. The investigation suggests the existence of a non-sensitive heat fraction on the enzyme structure, which is relatively stable up to temperatures close to 59 ºC....
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Β-Galactosidase; Enzyme Inactivation; Modelling; Protein Denaturation; Weibull.
Ano: 2018
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132018000100409

Homology modelling and insilico analysis of neuraminidase protein in H1N1 Influenza A virus
Provedor de dados: Brazilian Archives of Biology and Technology
Autores: Manohar,Abhilash.
In this work, modelling of Neuraminidase protein of Influenza A virus (A/Himeji/1/2009(H1N1)) neuraminidase (NA) protein was done using Modeller 9V2. Modelled structure was submitted to protein model database and could be downloaded using accession number PM0075830. The modelled protein structure was subjected to In silco analysis using various bioinformatics tools. Two anti-influenza drugs currently being used to treat infected patients are oseltamivir (Tamiflu) and zanamivir (Relenza), both of which target the neuraminidase enzyme of the virus. Reports of the emergence of drug resistance make the development of new anti-influenza molecules a priority. Hence the modelled structure of H1NI Neuraminidase could be very useful for in silico analysis of...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: H1N1; Neuraminidase; Modelling; In silico analysis.
Ano: 2011
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132011000100003

A simplified model for A. Niger FS3 growth during phytase formation in solid State fermentation
Provedor de dados: Brazilian Archives of Biology and Technology
Autores: Spier,Michele Rigon; Letti,Luiz Alberto Junior; Woiciechowski,Adenise Lorenci; Soccol,Carlos Ricardo.
A simplified model to describe fungal growth during citric pulp fermentation for phytase production was described for the first time. Experimental data for biomass growth were adjusted to classical mathematical growth models (Monod and Logistic). The Monod model predictions showed good agreement with the experimental results for biomass concentration during 96 hours of fermentation. Parameters such as yield of biomass from oxygen (Y X/O), maintenance coefficient (m) and specific growth rate (µ) were compared showing a good correlation between the data and the model. An alternative method for biomass determination in this process was developed since a great correlation was found between biomass growth and enzyme formation.
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Monod Model; Logistic model; Modelling; Fungal growth; Phytase formation; Citric pulp.
Ano: 2009
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132009000700020

Effect of combined function of temperature and water activity on the growth of Vibrio harveyi
Provedor de dados: Brazilian Journal of Microbiology
Autores: Zhou,Kang; Gui,Meng; Li,Pinglan; Xing,Shaohua; Cui,Tingting; Peng,Zhaohui.
Vibrio harveyi is considered as a causative agent of the systemic disease, vibriosis, which occurs in many biological fields. The effects of temperatures (12.9-27.1 ºC) and water activity (NaCl% 0.6%-3.4%) on V. harveyi were investigated. The behavior and growth characteristics of V. harveyi was studied and modeled. Growth curves were fitted by using Gompertz and Baranyi models, and the Baranyi model showed a better fittness. Then, the maximum growth rates (µmax) and lag phase durations (LPD, λ) obtained from both Gompertz and Baranyi model were modeled as a combination function of temperature and water activity using the response surface and Arrhenius-Davey models for secondary model. The value of r², MSE, bias and accuracy factor suggest Baranyi model...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Vibrio harveyi; Modelling; Temperature; Water activity.
Ano: 2012
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1517-83822012000400018

Applying precision feeding to improve the nitrogen efficiency of swine production: a review of possible practices and obstacles
Provedor de dados: Ciência Rural
Autores: Monteiro,Alessandra Nardina Trícia Rigo; Bertol,Teresinha Marisa; Kessler,Alexandre de Mello.
ABSTRACT: Optimizing nutrient efficiency is essential in order to increase sustainability of pig production systems, especially where the growing demand for food must be met at an affordable cost, without compromising environmental resources. To make this happen, it is necessary to develop efficient methods to accurately estimate the nutritional requirements of animals, as well as develop equipment and systems that allow for applying such expertise in the production system. Estimating the nutritional requirement of pigs through mathematical models, considering several factors that can impact the requirement, is a key factor to reduce the environmental load from pig production. Likewise, feed formulation and feeding programs, can help to achieve this. In...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Diet formulation; Environmental impact; Modelling; Nutritional requirement; Pig.
Ano: 2017
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-84782017000700653