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Registros recuperados: 10
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Apports des données de la 'couleur de l'eau' à la modélisation couplée physique-biogéochimie en milieu dynamique côtier : Application au Rio de la Plata et au Golfe de Gascogne ArchiMer
Huret, Martin.
Continental margins play a crucial role in biogeochemical fluxes between the continents and the open ocean. They are also highly sensitive to human perturbations. Primary production is highly dependent on the complex dynamics of these coastal zones, and on the river supply in nutrients, as well as in Suspended Particulate Matter (SPM) which limit light availability. The quantification of the production is a prerequisite in many applications, from the understanding of the role of the coastal ocean in climate change, to eutrophication and fisheries resources issues within the frame of the integrated management of the coastal zone. Coupled physical-biogeochemical models are useful in studying and monitoring primary production. Because of the numerous complex...
Tipo: Text Palavras-chave: Parameter estimation; Data assimilation; Suspended Particulate Matter (SPM); Chlorophyll a; Phytoplankton blooms; Physical biogeochemical coupled model; Ocean color; Satellite data; Coastal area; Bay of Biscay; Rio de la Plata; Estimation de paramètres; Assimilation de données; Matières En Suspension (MES); Chlorophylle a; Blooms phytoplanctoniques; Modèle couplé physique biogéochimie; Couleur de l'eau; Donnée satellitale; Milieu côtier; Golfe de Gascogne; Rio de la Plata.
Ano: 2005 URL: http://archimer.ifremer.fr/doc/2005/these-337.pdf
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Deriving CGE Baselines from Macro-economic Projections AgEcon
Mueller, Marc; Ferrari, Emanuele.
Quantitative policy analysts are usually confronted with the problem to derive a base-line scenario that reflects the most likely state of an economy in a future year. The methods used in practice to derive such a base-line scenarios are heterogeneous and range from the usage of the last observable year to complete and consistent estimation procedures. In the case of general equilibrium (CGE) analyses, the Scenar2020 project (European Commission 2006a) is one example how projections of macro-economic indicators (exogenous drivers) are used to construct the base-line as a model scenario: Starting from a calibrated version, exogenous variables are modified until macro-economic projections are met. However, numerous projections refer to economic indicators...
Tipo: Conference Paper or Presentation Palavras-chave: General equilibrium model; Baseline construction; Parameter estimation; Macro-economic projections; Research Methods/ Statistical Methods.
Ano: 2011 URL: http://purl.umn.edu/114638
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Differences and Congruencies between PVA Packages: the Importance of Sex Ratio for Predictions of Extinction Risk Ecology and Society
Brook, Barry W; Northern Territory University; barry.brook@ntu.edu.au; Burgman, Mark A; University of Melbourne; m.burgman@botany.unimelb.edu.au; Frankham, Richard; Macquarie University; rfrankha@rna.bio.mq.edu.au.
Population viability analysis (PVA) is used in conservation biology to predict extinction probabilities for threatened species. Previous studies have revealed large differences between the predictions of PVA modeling packages, but these comparisons included a range of nonstandard factors. A standardized comparison of five PVA packages (GAPPS, INMAT, RAMAS Metapop, RAMAS Stage, and VORTEX) was conducted on six examples (two mammals, two birds, one reptile, and a hypothetical bird/mammal-like life history). The individual-based packages (GAPPS and VORTEX) predicted a consistently higher risk of extinction than their matrix-based counterparts (INMAT and the RAMAS programs). This arose as only the former considered the effect of demographic stochasticity in...
Tipo: Peer-Reviewed Reports Palavras-chave: Demographic stochasticity; Extinction risk; Individual-based models; Matrix-based models; Model comparison; Parameter estimation; Population viability analysis; Sex ratio.
Ano: 2000
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Fast and reliable calibration of solid substrate fermentation kinetic models using advanced non-linear programming techniques Electron. J. Biotechnol.
Araya,M. Macarena; Arrieta,Juan J; Pérez-Correa,J. Ricardo; Biegler,Lorenz T; Jorquera,Héctor.
Calibration of mechanistic kinetic models describing microorganism growth and secondary metabolite production on solid substrates is difficult due to model complexity given the sheer number of parameters needing to be estimated and violation of standard conditions of numerical regularity. We show how advanced non-linear programming techniques can be applied to achieve fast and reliable calibration of a complex kinetic model describing growth of Gibberella fujikuroi and production of gibberellic acid on an inert solid support in glass columns. Experimental culture data was obtained under different temperature and water activity conditions. Model differential equations were discretized using orthogonal collocations on finite elements while model calibration...
Tipo: Journal article Palavras-chave: Dynamic models; Gibberellic acid; Nonlinear models; Parameter estimation; Secondary metabolites; Solid substrate cultivation.
Ano: 2007 URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582007000100005
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Improved calibration of a solid substrate fermentation model Electron. J. Biotechnol.
Sacher,Johannes; Saa,Pedro; Cárcamo,Martín; López,Javiera; Gelmi,Claudio A; Pérez-Correa,Ricardo.
Background: Calibration of dynamic models in biotechnology is challenging. Kinetic models are usually complex and differential equations are highly coupled involving a large number of parameters. In addition, available measurements are scarce and infrequent, and some key variables are often non-measurable. Therefore, effective optimization and statistical analysis methods are crucial to achieve meaningful results. In this research, we apply a metaheuristic scatter search algorithm to calibrate a solid substrate cultivation model. Results: Even though scatter search has shown to be effective for calibrating difficult nonlinear models, we show here that a posteriori analysis can significantly improve the accuracy and reliability of the estimation....
Tipo: Journal article Palavras-chave: Gibberella fujikuroi; Gibberellic acid; Global optimization; Metaheuristics; Nonlinear dynamic models; Parameter estimation; Solid substrate cultivation.
Ano: 2011 URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582011000500007
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Logistic growth models of China pinks, cultivated on seven substrates, as a function of degree days Ciência Rural
Milani,Marília; Lopes,Sidinei José; Bellé,Rogério Antônio; Backes,Fernanda Alice Antonello Londero.
ABSTRACT: The objective of this study was to characterize the height (H) and leaf number (LN) of China pinks, grown in seven substrates, as a function of degree days, using the logistic growth model. H and LN were measured from 56 plants per substrate, for 392 plants in total. Plants that were grown on substrates formed of 50% soil with 50% rice husk ash (50% S + 50% RH) and 80% rice husk ash with 20% worm castings (80% RH + 20% W) had the longest vegetative growth period (74d), corresponding to 1317.9ºCd. The logistic growth model, adjusted for H, showed differences in the estimation of maximum expected height (α) between the substrates, with values between 10.47cm for 50% S + 50% RH and 35.75cm for Mecplant(r). When α was estimated as LN, variation was...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Dianthus chinensis L; Growth model; Protected environment; Parameter estimation.
Ano: 2016 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-84782016001101924
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MODELING OF BASIL ESSENTIAL OIL EXTRACTION WITH VARIABLE DIFFUSION COEFFICIENT REA
Silveira,Jeniffer C.; Costa,Andréa O. S. da; Costa Junior,Esly F. da.
ABSTRACT: Essential oils are complex mixtures of volatile compounds found at low levels in aromatic plant specific parts. Soluble in organic solvents, these oils are characterized by their fragrance and antimicrobial activity, being widely used in industries. The mathematical modeling of essential oil extraction is a relevant step in the project of industrial plants because it is about achieving optimized operational conditions. A model is available in the literature describing the extraction process of basil essential oil, based on diffusion within the leaf. Parametric equations were tested for the variable diffusion coefficient with the concentration, resulting in a significant improvement in the description process, when compared to papers presented in...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Concentration variable diffusion; Parameter estimation; Essential oils.
Ano: 2017 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-69162017000400717
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Modeling the Transmission of Vibrio aestuarianus in Pacific Oysters Using Experimental Infection Data ArchiMer
Lupo, Coralie; Travers, Marie-agnes; Tourbiez, Delphine; Barthélémy, Clement; Beaunée, Gaël; Ezanno, Pauline.
Vibrio aestuarianus is a bacterium related to mortality outbreaks in Pacific oysters, Crassostrea gigas, in France, Ireland, and Scotland since 2011. Knowledge about its transmission dynamics is still lacking, impairing guidance to prevent and control the related disease spread. Mathematical modeling is a relevant approach to better understand the determinants of a disease and predict its dynamics in imperfectly observed pathosystems. We developed here the first marine epidemiological model to estimate the key parameters of V. aestuarianus infection at a local scale in a small and closed oyster population under controlled laboratory conditions. Using a compartmental model accounting for free-living bacteria in seawater, we predicted the infection dynamics...
Tipo: Text Palavras-chave: Marine epidemiology; Parameter estimation; Compartmental model; ABC method; Global sensitivity analysis; Basic reproduction number R-0; Crassostrea gigas; Oyster mortality.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00495/60652/64148.pdf
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Turix, a dynamic mechanistic model for feed evaluation R. Bras. Zootec.
Vargas-Villamil,Luis Manuel; Ku-Vera,Juan Carlos; Vargas-Villamil,Felipe; Medina-Peralta,Salvador; Avila-Vales,Eric José; Aranda-Ibañez,Emilio Manuel; Avendaño-Reyes,Leonel.
The objective of this study was to use the Turix model (a new mechanistic dynamic model that can be used for feed evaluation under tropical conditions), along with in situ and in vitro sugar cane experimental data from a previous study, to evaluate sugar cane kinetics through estimation of three parameters associated with ruminal bacterial growth: kM,SmL, the substrate uptake; kLM, the bacterial growth from intermediate metabolite; and Y VFAP,FS, the products related to volatile fatty acid yield. Values of these parameters for the whole sugar cane and its neutral detergent fiber (NDF) and acid detergent fiber (ADF) fractions were: a) kM, SmL, 16.20, 50.47 and 21.97 mL h-1 (mg M)-1 ; b) kLM, 96.00, 543.00 and 1,680.00 h-1 ; and, 1.02, 0.40 and 0.23 g g-1 ,...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Model fitting; Parameter estimation; Ruminant; Simulation; Sugar cane.
Ano: 2013 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-35982013000400009
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Use of SeaWiFS data for light availability and parameter estimation of a phytoplankton production model of the Bay of Biscay ArchiMer
Huret, Martin; Gohin, Francis; Delmas, Daniel; Lunven, Michel; Garcon, Véronique.
Processing SeaWiFS (Sea-viewing Wide Field-of-view Sensor) data provides useful information for the observation and modelling of the phytoplankton production of the Bay of Biscay. Empirical algorithms allow the retrieval of chlorophyll a and non-living Suspended Particulate Matter (SPM) concentrations. These data are used to constrain a coupled 3D physical-biogeochemical model of the Bay of Biscay continental shelf Two issues are investigated, depending on the variable used, to constrain the winter to spring phytoplankton production for the year 2001. First, SPM data is used as forcing data to correct the corresponding state variable of our model. This allows the realistic simulation of the light limited bloom at the end of February 2001, as observed with...
Tipo: Text Palavras-chave: Bay of Biscay; SeaWiFS; Parameter estimation; Chlorophyll; Suspended Particulate Matter; Physical biogeochemical modelling.
Ano: 2007 URL: http://archimer.ifremer.fr/doc/2007/publication-2493.pdf
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