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A model for predicting the quantities of dissolved inorganic nitrogen released in effluents from a sea bass (Dicentrarchus labrax) recirculating water system ArchiMer
Pagand, Pascal; Blancheton, Jean-paul; Casellas, Claude.
Fish excretions and the transformation of nitrogen by bacteria in the nitrifying biofilter are two of the main sources of dissolved inorganic nitrogen (DIN) in fish farms that use recirculating water systems. In this study, the DIN concentration in an experimental Dicentrarchus labrax aquaculture system was calculated using empirical sub-models for fish growth, ingested food and water replacement. The specific growth rate (SGR) (% day(-1)) and the daily feeding rate (DFR) (% day(-1)) both depend on the average weight, W (g), of the fish: Y = aW(b), where Y may be SGR or DFR, and a and b are empirical constants. The DIN discharge rate, Gamma(N) (% of ingested nitrogen), in the experimental aquaculture system was expressed as a function of increasing...
Tipo: Text Palavras-chave: Recirculating water system; Nitrogen production; Model; Fish farm effluent; European sea bass; Dissolved inorganic nitrogen.
Ano: 2000 URL: http://archimer.ifremer.fr/doc/2000/publication-514.pdf
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A model of sediment transport under the influence of surface bioturbation: generalisation to the facultative suspension-feeder Scrobicularia plana ArchiMer
Orvain, Francis.
Flume experiments were designed to study how sediment erodibility was modified by the facultative suspension-feeder Scrobicularia plana living at different densities in sediment beds of various degrees of compaction. Two separate erosion phases were identified from the resuspension kinetics: (1) erosion of an unconsolidated surficial layer (i.e. fluff layer) and (2) the subsequent bed erosion. S. plana were found to influence both erosion phases: (1) erosion rates of the fluff layer were controlled by bioturbation activities, the extents of which were influenced by bivalve density and the degree of compaction of the sediments, and (2) critical thresholds of the subsequent bed erosion decreased as clam density increased, likely due to depressions in the...
Tipo: Text Palavras-chave: Resuspension; Model; Functional groups; Sediment transport; Bioturbation; Scrobicularia plana; Intertidal mudflat.
Ano: 2005 URL: http://archimer.ifremer.fr/doc/2005/publication-3776.pdf
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A model-based evaluation of Marine Protected Areas: the example of eastern Baltic cod (Gadus morhua callarias L.) ArchiMer
Kraus, Gerd; Pelletier, Dominique; Dubreuil, Julien; Moellmann, Christian; Hinrichsen, Hans-harald; Bastardie, Francois; Vermard, Youen; Mahevas, Stephanie.
The eastern Baltic cod stock collapsed as a consequence of climate-driven adverse hydrographic conditions and over fishing and has remained at historically low levels. Spatio-temporal fishing closures [Marine Protected Areas (MPAs)] have been implemented since 1995, to protect and restore the spawning stock. However, no signs of recovery have been observed yet, either suggesting that MPAs are an inappropriate management measure or pointing towards suboptimal closure design. We used the spatially explicit fishery simulation model ISIS-Fish to evaluate proposed and implemented fishery closures, combining an age-structured population module with a multifleet exploitation module and a management module in a single model environment. The model is parameterized...
Tipo: Text Palavras-chave: Stock recovery; Model; Marine Protected Areas; Fishery management; Baltic cod.
Ano: 2009 URL: http://archimer.ifremer.fr/doc/2009/publication-6094.pdf
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A new innovated and cheep model in building artificial reefs OceanDocs
Mahmoud, M.A.; Ammar, M.S.A..
A novel and cheep approach for building artificial reefs was designed in such a way that sediments in an area of high sedimentation rate will be utilized in building the artificial substrate with no further sediment accumulation afterwards. The model consists of several steel cylinders which are soldered together in such a way to form a reef flat, a gentle slope and a steep slope, with two layers of narrow opening meshes (a lower plastic and an upper metallic one). Within a short periode (3 months), a substrate layer of a total of ~ 1 cm was formed between the two meshes, this layer increased to ~2 cm after 9 months. Transplants of the three species Stylophora pistillata, Echinopora gemmacea and Montipora spongiosa grow better when the attaching surface is...
Tipo: Journal Contribution Palavras-chave: Coral reefs; Artificial coral reefs; Transplantation; Substrate; Model; Sedimentation Sediment transport Artificial reefs.
Ano: 2005 URL: http://hdl.handle.net/1834/1298
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A non-linear viscoelastic viscoplastic model for the behaviour of polyester fibres ArchiMer
Chailleux, Emmanuel; Davies, Peter.
In this study the macroscopic analysis proposed by Schapery has been applied to model the non-linear viscoelastic and viscoplastic behaviour of polyester fibres. First, a special non-contact extensometry method has been developed in order to measure the fibre response without affecting the behaviour of these extremely anisotropic fibres. An accelerated identification method has then been developed. This enables a unique and independent set of parameters to be determined, which separate the reversible and non-reversible mechanisms responsible for measured strains. The model prediction for an arbitrary loading sequence corresponds closely to the measured strains. The model has been applied here at the yarn level but can equally well be used to predict rope...
Tipo: Text Palavras-chave: Viscoplastic; Viscoelastic; Polyester; Non linear; Model; Fibre.
Ano: 2005 URL: http://archimer.ifremer.fr/doc/2005/publication-794.pdf
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A SYSTEM DYNAMICS MODEL OF AGRICULTURE AND RURAL DEVELOPMENT: THE TOPMARD CORE MODEL AgEcon
Johnson, Thomas G.; Bryden, John Marshall; Refsgaard, Karen; Alva Lizarraga, Sara.
The goal of the TOPMARD project is to develop a model of agriculture and rural development to better understand the agronomic, ecological, economic and social dimensions of rural regions. The resulting model, (Policy Model of Multifunctional Agriculture and Rural Development) was built collaboratively and hierarchically by the research teams from the 11 countries. The model features eight subsectors (Land, Agriculture, Tourism, Region, Human Resources, Non-commodities, Capital, and Quality of Life). Imbedded in the model are a complete dynamic input-output model, and an agecohort education demographic model. The model has both supply-side and demand-side drivers. Land use is the key supply-side driver. Land use, coupled with production system choices,...
Tipo: Conference Paper or Presentation Palavras-chave: Multifunctionality; System dynamics; Policy; Model; Rural development; Community/Rural/Urban Development; Research Methods/ Statistical Methods; Research and Development/Tech Change/Emerging Technologies.
Ano: 2008 URL: http://purl.umn.edu/6497
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A Theoretical Approach to Tourism Sustainability Ecology and Society
Casagrandi, Renato; Dipartimento di Elettronica e Informazione, Politecnico di Milano; casagran@elet.polimi.it; Rinaldi, Sergio; CIRITA, Politecnico di Milano; rinaldi@elet.polimi.it.
This paper shows that it is difficult, if not impossible, to formulate policies that guarantee that tourism can be maintained for a long time without severely impacting on the environment. The analysis is purely theoretical and is based on very simple and general assumptions about the interactions between the three main components of the system: the tourists, the environment, and the capital. These assumptions are encapsulated in a so-called minimal model, used to predict the economic and environmental impact of any given policy. This paper is of value for three reasons. First, it introduces the approach of minimal descriptive models in the context of tourism, which has traditionally been dominated by the use of black-box econometric models. Second, the...
Tipo: Peer-Reviewed Reports Palavras-chave: Bifurcation analysis; Environment; Model; Nonlinear dynamics; Sustainability; Tourism.
Ano: 2002
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A TRADE LIBERALIZATION IN INTERNATIONAL DAIRY MARKETS AgEcon
Langley, Suchada V.; Blayney, Donald P.; Stout, Jim; Somwaru, Agapi; Normile, Mary Anne; Miller, James J.; Stillman, Richard.
International dairy industries remain among the most distorted agricultural sectors. Dairy average bound tariffs remain among the highest of all agricultural commodities, and dairy trade is characterized by a large number of megatariffs and tariff-rate quotas (TRQs). The objective of our study is to examine how the international dairy markets might respond to policy changes under various assumptions, using a partial equilibrium, multiple-commodity, multiple-region model of agricultural policy and trade. Our results indicate that liberalization will reduce supplies, increase dairy trade, and raise world prices.
Tipo: Conference Paper or Presentation Palavras-chave: Dairy Markets; Trade Liberalization; Model; Policy; International Relations/Trade.
Ano: 2003 URL: http://purl.umn.edu/21997
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Adaptive Capacity and Traps Ecology and Society
Carpenter, Stephen R; University of Wisconsin-Madison; srcarpen@wisc.edu; Brock, William A.; University of Wisconsin-Madison; WBrock@ssc.wisc.edu.
Adaptive capacity is the ability of a living system, such as a social–ecological system, to adjust responses to changing internal demands and external drivers. Although adaptive capacity is a frequent topic of study in the resilience literature, there are few formal models. This paper introduces such a model and uses it to explore adaptive capacity by contrast with the opposite condition, or traps. In a social–ecological rigidity trap, strong self-reinforcing controls prevent the flexibility needed for adaptation. In the model, too much control erodes adaptive capacity and thereby increases the risk of catastrophic breakdown. In a social–ecological poverty trap, loose connections prevent the mobilization of ideas and resources...
Tipo: Peer-Reviewed Insight Palavras-chave: Adaptation; Allostasis; Model; Poverty trap; Resilience; Rigidity trap; Transformation.
Ano: 2008
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Alocação de biomassa e ajuste de equações para estimativa de biomassa em compartimentos aéreos de Eucalyptus benthamii. Repositório Alice
SILVA, H. D. da.; FERREIRA, C. A.; CORRÊA, R. S.; BELLOTE, A. F. J.; TUSSOLINI, E. L..
Este trabalho tem por objetivo apresentar os resultados do ajuste de modelos para determinação da biomassa seca de compartimentos aéreos e a alocação percentual de biomassa nos compartimentos madeira, casca, folhas e galhos em árvores de Eucalyptus benthamii de 12, 24, 36 e 48 meses de idade e plantios com espaçamento 3 m x 2 m, no município de Guarapuava-PR. Para os compartimentos considerados, o modelo logarítmico generalizado foi de melhor índice de ajuste para a variável galho e, juntamente com o modelo variável, combinada logarítmica, o de menor erro para casca. Com relação aos compartimentos folha e madeira, foi mais adequado o uso do modelo lnY=b 0 +b 1 *lnDAP e variável combinada logarítmica, respectivamente. A alocação de biomassa foi diferenciada...
Tipo: Artigo em periódico indexado (ALICE) Palavras-chave: Eucalyptus benthami; Idade; Modelo; Variável; Age; Model; Variable.
Ano: 2004 URL: http://www.alice.cnptia.embrapa.br/handle/doc/311927
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An Analysis of Global Timber Markets AgEcon
Sohngen, Brent; Mendelsohn, Robert; Sedjo, Roger A.; Lyon, Kenneth S..
This paper presents a model of global timber markets that captures the evolution of a broad array of forest resources and timber market margins over time. These margins include the inaccessible northern and tropical margins, plantation establishment, and timberland management. A baseline case is presented and discussed. Five alternative scenarios are then presented. These scenarios allow us to consider several important questions about timber market behavior and the future supply of industrial fiber: (1) What happens along the northern and the tropical inaccessible margins? (2) What role do timber plantations play? and (3) How do shifts in management intensity interact with market forces? The baseline case suggests that both prices and harvests rise over...
Tipo: Working or Discussion Paper Palavras-chave: Global timber markets; Forest plantations; Model; Forecast; Resource /Energy Economics and Policy; Q10; Q21; Q23; Q24.
Ano: 1997 URL: http://purl.umn.edu/10449
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Análise de investimento de programas de melhoramento de pastagem para a produção de gado de corte no Cerrado. Infoteca-e
MONTEIRO, L. A.; CHUDLEIGH, P. D.; GARDNER, A. L..
Descrição do modelo. Suposições referentes ao sistema tradicional. Estrutura do modelo. Dados. Validação. Programa de computador. Experimentação. Resultados e discussão. Proporção de pastagem melhorada na fazenda e idade de venda de macho. Taxa de estabelecimento da pastagem cultivada. Método para aumentar o numero de vacas de cria. Método para aumentar o tamanho do rebanho. Compra de vacas velhas para engordar durante a estação chuvosa. Prioridade para o uso da pastagem melhorada.
Tipo: Documentos (INFOTECA-E) Palavras-chave: Pastagem cultivada; Cerrado; Bovino de corte; Produção; Modelo; Simulação; Aspecto econômico; Brasil; Sown pasture; Brazilian savannas; Beef cattle; Production; Model; Simulation; Economic situation; Brazil.
Ano: 1981 URL: http://www.infoteca.cnptia.embrapa.br/handle/doc/319643
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Análise econômica de lâminas de água e doses de nitrogênio, para cultura de milho, utilizando o modelo ceres-maize. Repositório Alice
FREITAS, P.S.L.de; LEITE, C.A.M.; MANTOVANI, E. C.; MANTOVANI, B.H.M..
Para a simulacao dos dados necessarios nas analises do presente trabalho, utilizou-se o modelo CERES-MAIZE, que esta inserido no pacote DSSAT 3.0. Nas simulacoes, realizadas para o municipio de Janauba - MG, utilizou-se o cultivar de milho BR-201, desenvolvido na EMBRAPA Milho e Sorgo, que ocupa entre 5 a 7% da area de plantio da cultura no Brasil. Foram simulados os dados de produtividade do cultivar BR-201, em tres epocas de plantio (15.05, 15.10 e 15.11), com ou sem irrigacao, com as seguintes laminas d'agua 4,8,12,16,20,24,30 e 36mm, aplicadas em um turno de rega de 7 dias. As laminas de agua foram combinadas com as seguintes doses de nitrogenio 0, 30, 60, 90, 120, 150, 180 e 210 kg/ha 4. Os dados foram simulados utilizando-se dados climaticos de 18...
Tipo: Artigo em anais de congresso (ALICE) Palavras-chave: Milho; Irrigacao; Simulacao; Modelo; Zea mays; Maize; Irrigation; Simulation; Model.
Ano: 1998 URL: http://www.alice.cnptia.embrapa.br/handle/doc/480272
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Analysis of Effects of Different Operation Patterns of Returning Farmland to Forest(grass) on Rural Economy-A Case of Wuqi County, China AgEcon
Meng, Luo; Gui-xian, Li.
Taking Wuqi country, shanxi Province as an example, this paper is based on the introductions of the researched regions and according to the planting model and some factors influencing economy. After systematic analysis and selection, it selects ecological forestry, wood-grass-husbandry, wood-grass-husbandry, wood-medicine, economic forestry and greenhouse vegetable these five models of returning farming to grass, with Wuqi town, Baibaotown, Wu Cangbao county, Xinzhai county, Xuecha county and Wugu town these five sites as examples. This paper has carried out a research on these 5 models at country, town and household levels through Participatory Rural Appraisal and Document Search to gain the related data. And making a comparison on the contribute of the 5...
Tipo: Journal Article Palavras-chave: Agribusiness; Model; Wuqi county; Returning farmland to forest and grassland; Economic; Efficiency; China.
Ano: 2010 URL: http://purl.umn.edu/93231
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Analysis of soil organic matter in tropical soils with near-infrared spectroscopy (NIRS) and chemometrics Ciencia e Investigación Agraria
Jarquín-Sánchez,Aarón; Salgado-García,Sergio; Palma-López,David J; Camacho-Chiu,Wilder.
The objective of this study was to predict the concentration of soil organic matter (SOM) in tropical soils using near-infrared spectroscopy (NIRS) for samples measured within a polyethylene bag and without a bag. One hundred and fifty six soil samples from the humid tropics of Tabasco, Mexico with contrasting chemical characteristics were selected. The samples were dried, ground, and sieved through 2 mm and 5 mm screens, and their SOM contents were determined using the Walkley-Black method. The soil samples were packed in polyethylene bags, and SOM was measured directly with and without a bag using a quartz probe (FOSS 5000 model of NIRsystems, DK-3400 Hillerod,Denmark) for a range from 1100 to 2000 nm to obtain a prediction model of SOM. The model for...
Tipo: Journal article Palavras-chave: Chemical analysis; Tropical soil; Optical fiber; Model; Organic matter prediction.
Ano: 2012 URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-16202012000200015
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Analysis of tagging data from North Atlantic Albacore (Thunnus Alalunga): Attrition Rate Estimates ArchiMer
Ortiz De Zarate, Victoria; Bertignac, Michel.
In this study, an attempt is made to estimate natural mortality rate for North Atlantic albacore. We implement a spatially aggregated tag-attrition model to analyse the results of an albacore tagging experiment conducted in the Bay of Biscay from 1988 to 1991. The model predicts probabilities of the possible fates of tagged fish and the tags that they carry. The model includes several parameters consisting of catchabilities by fleets involved in recaptures and a combination of natural mortality plus emigration from the study area. Model fitting is carried out by finding the maximum of a multinomial likelihood function. Effect of reporting rate values on the estimations are evaluated and several hypothesis on the pre-mixing period of the tagged fish...
Tipo: Text Palavras-chave: Bay of Biscay; Attrition rate; Model; Natural mortality estimation; Albacore.
Ano: 2001 URL: http://archimer.ifremer.fr/doc/2001/publication-977.pdf
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Assessment of the CERES-Rice model for rice production in Ibadan, Nigeria CIGR Journal
Christopher Oluwakunmi Akinbile; FUTA.
CERES-Rice model was used to simulate growth and yield of a new rice variety in Nigeria with the attention on rates of water application, one major factor that retards crop’s grain yield. The rates were full irrigation (100%ET), medium (75% ET), average (50% ET) and low (25% ET) irrigation intervals. The NEw RIce for AfriCA (acronym for NERICA) 2 variety was grown at the International Institute for Tropical Agriculture (IITA), Ibadan, Nigeria. Experimental agronomic values of parameters such as plant height, root depth, canopy shading, Leaf area index (LAI), biomass and grain yield in relation to water use were obtained and compared with simulated modelled values from CERES and the results were subjected to statistical analysis. The model predicted...
Palavras-chave: Agricultural Engineering; Soil and Water Conservation Engineering Rice; Model; Water; Simulation; Production; Food security..
Ano: 2013 URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/2405
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AZ ÖKOLÓGIAI MÓDON MŰVELT TERMŐTERÜLETEK NAGYSÁGÁT BEFOLYÁSOLÓ TÉNYEZŐK ÉS AZ ÁRUTERMELŐ NÖVÉNYEK PIACI POZICIÓI MAGYARORSZÁGON AgEcon
Jarasi, Eva Zsuzsanna.
The significance of organic farmlands can be evaluated in two ways: based on their ecological and their economic implications. Regarding the former, it does not make a crucial difference how the land is utilised specifically: pasture and meadow; arable land or plantation or certified organic farmland, use not known. For an illustration, let us consider that in 2005, almost half of organic farmlands in the world were located in Australia, amounting to over 31 million hectares. Most of this area is pastoral land for low intensity grazing in Australia. Therefore, one organic hectare in Australia is not directly equivalent to one organic hectare in Denmark, for example, due to its level of productivity. As a result, it is worthwhile to survey the exact extent...
Tipo: Book Palavras-chave: Ökológiai növénytermesztés; Fejlődési lehetőség; Modellezés; Pareto-elv; Organic crop production; Possibility for development; Model; Pareto principle; Agribusiness; Crop Production/Industries; Farm Management.
Ano: 2008 URL: http://purl.umn.edu/43327
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Batch anaerobic digestion of banana waste - energy potential and modelling of methane production kinetics CIGR Journal
Khan, Muhammad Tahir; Brulé, Mathieu; Maurer, Claudia; Argyropoulos, Dimitrios; Müller, Joachim; Oechsner, Hans.
Different fractions of banana (stalk, peel, and flesh) as well as the whole unpeeled banana were studied in a laboratory Biochemical Methane Potential (BMP) assay. After completion of 35-day digestion at 37°C in 2L-reactors, specific methane yields reached 0.256, 0.322, 0.367 and 0.349 m³/kg VS (volatile solids) for stalk, peel, flesh, and unpeeled banana respectively. Considering the country of Uganda, East Africa, the collection of peels and stalks from banana production would yield a theoretical potential of about 60 GWh of electrical energy per year in biogas plants. In order to verify the suitability of banana fractions to the biogas process, their chemical composition was analyzed, and their methane production kinetics was estimated with exponential...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Energy biogas; Anaerobic digestion; BMP assay; Model; Energy; Methane; Waste.
Ano: 2016 URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/3244
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Challenges and Prospects in Ocean Circulation Models ArchiMer
Fox-kemper, Baylor; Adcroft, Alistair; Boening, Claus W.; Chassignet, Eric P.; Curchitser, Enrique; Danabasoglu, Gokhan; Eden, Carsten; England, Matthew H.; Gerdes, Ruediger; Greatbatch, Richard J.; Griffies, Stephen M.; Hallberg, Robert W.; Hanert, Emmanuel; Heimbach, Patrick; Hewitt, Helene T.; Hill, Christopher N.; Komuro, Yoshiki; Legg, Sonya; Le Sommer, Julien; Masina, Simona; Marsland, Simon J.; Penny, Stephen G.; Qiao, Fangli; Ringler, Todd D.; Treguier, Anne-marie; Tsujino, Hiroyuki; Uotila, Petteri; Yeager, Stephen G..
We revisit the challenges and prospects for ocean circulation models following Griffies et al. (2010). Over the past decade, ocean circulation models evolved through improved understanding, numerics, spatial discretization, grid configurations, parameterizations, data assimilation, environmental monitoring, and process-level observations and modeling. Important large scale applications over the last decade are simulations of the Southern Ocean, the Meridional Overturning Circulation and its variability, and regional sea level change. Submesoscale variability is now routinely resolved in process models and permitted in a few global models, and submesoscale effects are parameterized in most global models. The scales where nonhydrostatic effects become...
Tipo: Text Palavras-chave: Ocean circulation; Model; Parameterization; Climate; Ocean processes.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00488/59989/63213.pdf
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