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Registros recuperados: 204
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A bio-economic analysis of experimental selective devices in the Norway lobster (Nephrops norvegicus) fishery in the Bay of Biscay ArchiMer
Raveau, Adriana; Macher, Claire; Mehault, Sonia; Merzereaud, Mathieu; Le Grand, Christelle; Guyader, Olivier; Bertignac, Michel; Fifas, Spyros; Guillen Garcia, Jordi.
Several fleets with various fishing strategies operate as a mixed fishery in the Bay of Biscay. Among the main fleets, bottom trawlers target Norway lobster (Nephrops norvegicus) and, together with gillnetters, they also catch hake (Merluccius merluccius). Trawling leads to average-size catches that are below the minimum landing size (MLS); such catches are discarded since they cannot be sold. These discards result in negative impacts on stock renewal, as most of them do not survive. This also results in an economic loss for both bottom trawlers and gillnetters since these discards represent a future loss of rent. This study, based on the 2009 and 2010 selectivity experiments at sea, assesses the short- and long-term bio-economic impacts of four...
Tipo: Text Palavras-chave: Demersal trawl fishery; Bio-economic analysis; Selectivity; Simulation; Selective device; Nephrops norvegicus; Merluccius merluccius; Atlantic Ocean.
Ano: 2012 URL: http://archimer.ifremer.fr/doc/00110/22135/19774.pdf
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A Fractal Landscape Realizer for Generating Synthetic Maps Ecology and Society
Hargrove, William; Oak Ridge National Laboratory; hnw@fire.esd.ornl.gov; Hoffman, Forrest M; Oak Ridge National Laboratory;; Schwartz, Paul M; ;.
A fractal landscape realizer has been developed that generates synthetic landscape maps to user specifications. The alternative landscape realizations are not identical to the actual maps after which they are patterned, but are similar statistically (i.e., the areas and fractal character of each category are replicated). A fractal or self-affine pattern generator is used to provide a spatial probability surface for each category in the synthetic map. The Fractal Realizer arbitrates contentions among categories in a way that makes it possible to preserve the fractal patterns of all the categories in the resulting synthetic landscape. Each synthetic landscape is one equally likely realization from among an infinite ensemble of possible fractal landscape...
Tipo: Peer-Reviewed Reports Palavras-chave: FRAGSTATS; Fractal Realizer; Turing Test; Categorical maps; Fractal; Landscape ecology; Neutral model; Null model; Pattern; Pseudoreplication; Realization; Simulation; Synthetic map.
Ano: 2002
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A method to assess farmers' room for maneuvering crop location at the landscape level for biodiversity conservation Inra
Joannon, A.; Baudry, J.; Boussard, H.; Castellazzi, M.S; Schermann, N.; Vasseur, C.; Joannon, A..
Tipo: Conference Paper Palavras-chave:  BIODIVERSITE Biodiversity; Agricultural landscape; Crop mozaic; Simulation; Decision making; Indicators.
Ano: 2009 URL: http://www.prodinra.inra.fr/prodinra/pinra/doc.xsp?id=PROD2009942e5c05&uri=/notices/prodinra1/2011/03/
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A Risk Analysis of Converting CRP Acres to a Wheat-Sorghum-Fallow Rotation AgEcon
Williams, Jeffery R.; Llewelyn, Richard V.; Pendell, Dustin L.; Schlegel, Alan J.; Troy, Dumler.
This study examines the economic potential of producing a wheat (Triticum aesitivum) and grain sorghum (Sorghum bicolor (L.) Moench) rotation with three different tillage strategies compared to the Conservation Reserve Program (CRP) in a semi-arid region. This research uses stochastic efficiency with respect to a function (SERF) to determine the preferred management strategies under various risk preferences and utility-weighted certainty equivalent risk premiums. Yields, input rates, and field operations from an experimental field in western Kansas are used to calculate net returns for each tillage strategy. Although current net returns to crop production using reduced tillage and no-tillage strategies are higher than CRP, risk analysis indicates CRP...
Tipo: Conference Paper or Presentation Palavras-chave: Conservation Reserve Program; Conservation tillage; Simulation; Sorghum; Wheat; Risk; Agricultural and Food Policy; Crop Production/Industries; Farm Management; Land Economics/Use; Risk and Uncertainty.
Ano: 2008 URL: http://purl.umn.edu/45985
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A UNIFIED APPROACH TO SENSITIVITY ANALYSIS IN EQUILIBRIUM DISPLACEMENT MODELS: COMMENT AgEcon
Griffiths, William E.; Zhao, Xueyan.
It is pointed out that the Chebychev confidence intervals and maximum p-values advocated by Davis and Espinoza for sensitivity analysis of equilibrium displacement models are unnecessary. Desired probability intervals and probabilities can be accurately estimated without resorting to gross approximations.
Tipo: Working or Discussion Paper Palavras-chave: Simulation; Probability distributions; Empirical quantiles; Research Methods/ Statistical Methods.
Ano: 1999 URL: http://purl.umn.edu/12950
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A Whole Farm Analysis of the Influence of Auto-Steer Navigation on Net Returns, Risk, and Production Practices AgEcon
Shockley, Jordan M.; Dillon, Carl R.; Stombaugh, Timothy S..
A whole farm economic analysis was conducted to provide a detailed assessment into the economic, risk, and production implications due to the adoption of auto-steer navigation. It was determined that auto-steer navigation was profitable for a grain farmer in Kentucky with net returns increasing up to 0.90% ($3.35/acre). Additionally, the technology could be used in reducing production risk. Adoption of the technology also alters production practices for optimal use.
Tipo: Journal Article Palavras-chave: Economics; Farm management; Mean-variance; Precision agriculture; Simulation; Farm Management; Risk and Uncertainty; C61; C63; D81; Q12; Q16.
Ano: 2011 URL: http://purl.umn.edu/100640
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ACCOUNTING FOR SPATIAL CHARACTERISTICS OF WATERSHEDS IN EVALUATING WATER POLLUTION ABATEMENT POLICIES AgEcon
Qiu, Zeyuan; Prato, Anthony A..
This study evaluates three agricultural nonpoint pollution abatement policies: regulating the spatial pattern of agricultural activities, ambient tax, and abatement tax/subsidy. All three policies incorporate spatial characteristics of agricultural emission loading and movement for an agricultural watershed in the Midwest. The effects of spatial variation in natural conditions and landscape features on agricultural emissions and crop yield are evaluated using a newly developed biophysical simulation model and experimental data. While the policies are equally cost effective in reducing agricultural nonpoint source pollution, their implementation feasibility is quite different.
Tipo: Journal Article Palavras-chave: Atrazine; Environmental policy; Nonpoint pollution; Simulation; Watershed management; Water quality; Environmental Economics and Policy.
Ano: 1999 URL: http://purl.umn.edu/15135
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Adaptação do modelo STICS ao balanço hídrico da sequência milho-milheto em sistema de plantio direto no cerrado brasileiro. Infoteca-e
SILVA, F. A. M. da; SCOPEL, E.; PINTO, H. S.; ASSAD, E. D.; CORBEELS, M..
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Tipo: Fôlder / Folheto / Cartilha (INFOTECA-E) Palavras-chave: Balanço hídrico; Milho; Zea mays; Cerrado; Simulação; Crescimento; Rendimento; Water balance; Maize; Simulation; Growth; Crop yield.
URL: http://www.infoteca.cnptia.embrapa.br/handle/doc/569497
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Adaptive Harvesting in a Multiple-Species Coral-Reef Food Web Ecology and Society
Kramer, Daniel B; Michigan State University; dbk@msu.edu.
The utility of traditional bio-economic harvest models suffers from their dependence on two commonly used approaches. First, optimization is often assumed for harvester behavior despite system complexity and the often neglected costs associated with information gathering and deliberation. Second, ecosystem interactions are infrequently modeled despite a growing awareness that these interactions are important. This paper develops a simulation model to examine the consequences of harvesting at two trophic levels in a coral-reef food web. The model assumes adaptive rather than optimizing behavior among fishermen. The consequences of changing economic, biological, and social parameters are examined using resilience as an evaluative framework. Three general...
Tipo: Peer-Reviewed Reports Palavras-chave: Fisheries; Resource economics; Coral reefs; Resilience; Adaptive behavior; Food web; Simulation.
Ano: 2008
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Advanced Biofuel Production in Louisiana Sugar Mills: an Application of Real Options Analysis AgEcon
Darby, Paul M.; Mark, Tyler B.; Detre, Joshua D.; Salassi, Michael E..
In order to more fully study the risks and uncertainty involved in cellulosic ethanol production, we examine a simulated plant in South Louisiana using Real Options Analysis
Tipo: Conference Paper or Presentation Palavras-chave: Real options; Risk; Uncertainty; Cellulosic ethanol; Energy cane; Sorghum; Bagasse; Simulation; Agribusiness; Agricultural Finance; Production Economics; Resource /Energy Economics and Policy; Risk and Uncertainty; Q42; Q14; Q16; D81; G31.
Ano: 2011 URL: http://purl.umn.edu/103747
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Aerobic rice - the China story International Rice Research Institute
Bouman, Bas.
Powerpoint presentation; 55 slides
Tipo: Presentation Palavras-chave: Aerobic rice; Water requirements; China; Simulation; Oryza 2000.
Ano: 2007 URL: http://hdl.handle.net/10269/37
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Agent-Based Modelling and Sensitivity Analysis by Experimental Design and Metamodelling: An Application to Modelling Regional Structural Change AgEcon
Happe, Kathrin.
This paper presents the application of the sensitivity analysis techniques Design of Experiments (DOE) and metamodelling to the agent-based model AgriPoliS, which is a spatial and dynamic simulation model of regional structural change. DOE and metamodelling provide a more systematic analysis of results of complex simulation models. When summarising the results, it becomes clear that interest rates, technical change and managerial ability influence average economic land rent the most.
Tipo: Conference Paper or Presentation Palavras-chave: Simulation; Design of experiments; Metamodelling; Structural change; Research and Development/Tech Change/Emerging Technologies; C9; C15.
Ano: 2005 URL: http://purl.umn.edu/24464
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Agricultural policy (AP2011) Reform and the WTO: Potential Impacts on Swiss Agriculture AgEcon
Ferjani, Ali.
This article analyses the impact of the planned Swiss package of agricultural policy measures AP2011 and the tariff reductions scheduled as part of the WTO Doha Round, with special emphasis on effects in the dairy and meat sector. The simulations are carried out using an extended partial equilibrium model. This article discusses the anticipated impact of changing structural conditions on production, processing, consumption, prices and exports in the milk market. If account is taken of the Bilateral Agreements between Switzerland and the EU providing for liberalisation of the common cheese market, raw milk production increases by 10.5 %, whereas the milk price shows a significant drop to around 60 centimes per kilogram of milk. The abolition of subsidies...
Tipo: Conference Paper or Presentation Palavras-chave: Partial equilibrium model; Simulation; AP2011; WTO; Dairy industry; Agricultural and Food Policy; International Relations/Trade; Livestock Production/Industries.
Ano: 2008 URL: http://purl.umn.edu/6638
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Agricultural Trade and Freshwater Resources AgEcon
Reimer, Jeffrey J..
Approximately 75% of all water used by humans goes towards food production, much of which is traded internationally. This study formally models how this works in the case of crop agriculture, making use of recent advances in international trade theory and new data on the productivity by which countries use water for crop agriculture. The strength of the model lies in its ability to predict, when there is a shock to the system, how trade between pairs of specific countries changes for products that use water intensively. In one application of the model, international trade in final products is shown to be a means for countries to deal with short- and long-run shocks to water resources that are too big for one country to handle by itself in isolation. In...
Tipo: Presentation Palavras-chave: Climate change; Simulation; Trade liberalization; Water; Agricultural and Food Policy; Crop Production/Industries; International Development; International Relations/Trade; Resource /Energy Economics and Policy; F11; F18; Q25; Q54.
Ano: 2012 URL: http://purl.umn.edu/123944
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An Economic Assessment of the BSE Crisis in Canada: Impact of Border Closure and BSE Recovery Programs AgEcon
Weerahewa, Jeevika; Meilke, Karl D.; Le Roy, Danny G..
This article assesses the economic consequences of three alternative government responses to the BSE crisis in Canada: 1) expansion in slaughter capacity; 2) partial destruction of the cattle herd; and 3) deficiency payments. Each of these policies is evaluated under four different border situations: 1) autarky; 2) free trade in young beef only; 3) free trade in young beef and cattle; and 4) complete free trade. The results of the policy analysis are quite sensitive to the border assumptions, making it impossible to select a “best” policy without perfect foresight with respect to the timing and the extent of the border opening.
Tipo: Journal Article Palavras-chave: BSE; Cattle and beef; Partial equilibrium model; Simulation; Trade ban; International Relations/Trade; Livestock Production/Industries.
Ano: 2008 URL: http://purl.umn.edu/6176
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An Economic Risk Analysis of No-till Management for the Rice-Soybean Rotation System used in Arkansas AgEcon
Hristovska, Tatjana; Watkins, K. Bradley; Anders, Merle M..
Arkansas is the top domestic rice producer, representing nearly half of total U.S. rice production. Sediment is one of the major pollutants in rice producing areas of Arkansas. In order to mitigate this problem no-tillage management is often recommended. No-tillage is not well understood by farmers who believe that no-till is less profitable due to lower yields offsetting cost savings. This study evaluates the profitability and variability of no-till in the typical rice-soybean rotation used in Arkansas rice production. Crop yields, prices and prices for key production inputs (fuel and fertilizer) are simulated for the rotation, and net return distributions for rice, soybean and the two-year rotation are evaluated for no-till and conventional till using...
Tipo: Presentation Palavras-chave: Simulation; Rice-soybean; No tillage-profitability; Risk analysis; Environmental Economics and Policy; Farm Management; Resource /Energy Economics and Policy.
Ano: 2012 URL: http://purl.umn.edu/119676
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An evaluation of multi-annual management strategies for ICES roundfish stocks ArchiMer
Kell, L; Pilling, G; Kirkwood, G; Pastoors, M; Mesnil, Benoit; Korsbrekke, K; Abaunza, P; Aps, R; Biseau, Alain; Kunzlik, P; Needle, C; Roel, B; Ulrich, C.
Current scientific management objectives for ICES roundfish stocks are to ensure conservation of the biological resource and do not explicitly consider economic or social objectives. For example, there are currently no objectives to maximize the sustainable yield or to reduce variability in total allowable catches (TACs). This is despite the fact that the current system can result in wide annual fluctuations in TAC, limiting the ability of the fishing industry to plan for the future. Therefore, this study evaluated management strategies that stabilized catches by setting bounds on the interannual variability in TACs. An integrated modelling framework was used, which simulated both the real and observed systems and the interactions between system...
Tipo: Text Palavras-chave: Whiting; TAC; Simulation; Saithe; Population modelling; North Sea; Management; Limiting variations; Harvest strategies; Hake; Haddock; Evaluation; Cod; Bounds.
Ano: 2006 URL: http://archimer.ifremer.fr/doc/2006/publication-3694.pdf
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AN EX ANTE ASSESSMENT OF INVESTMENTS IN TEXAS GRAPEFRUIT UNDER UNCERTAINTY AgEcon
Elmer, Nicole A.; Thurow, Amy Purvis; Johnson, Jason L.; Rosson, C. Parr, III.
The Dixit-Pindyck model was applied to examine the hypothesis that uncertainty associated with grapefruit production costs and returns is an important determinant of Texas grapefruit growers' investment behavior. Freezes, price variability, and the effects of expanded trade were analyzed as risk factors. An investment decision rule based on a net-present value calculation would approve a 25-year commitment to a 20-acre grapefruit grove, given a 6-percent discount rate. The modified hurdle rate, calculated using an ex ante version of the Dixit-Pindyck model, is 24 percent. The major source of the risk borne by Texas grapefruit investors is from freezes, rather than from expanded trade.
Tipo: Journal Article Palavras-chave: Citrus; Ex ante analysis; Dixit-Pindyck model; Freezes; Investment; Simulation; Texas; Trade; Crop Production/Industries.
Ano: 2001 URL: http://purl.umn.edu/15451
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An iterative approach for generating statistically realistic populations of households. Repositório Alice
GARGIULO, F.; TERNES, S.; HUET, S.; DEFFUANT, G..
Background. Many different simulation frameworks, in different topics, need to treat realistic datasets to initialize and calibrate the system. A precise reproduction of initial states is extremely important to obtain reliable forecast from the model. Methodology/Principal Findings. This paper proposes an algorithm to create an artificial population where individuals are described by their age, and are gathered in households respecting a variety of statistical constraints (distribution of household types, sizes, age of household head, difference of age between partners and among parents and children). Such a population is often the initial state of microsimulation or (agent) individual-based models. To get a realistic distribution of households is often...
Tipo: Artigo em periódico indexado (ALICE) Palavras-chave: Simulação; Algoritmo; População x tarefas do lar; Projeto PRIMA; Synthetic population; Algorithm; Artificial population; Population distributed in households; Simulation; Prototypical Policy Impacts on Multifunctional Activities - PRIMA.
Ano: 2010 URL: http://www.alice.cnptia.embrapa.br/handle/doc/864056
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Análise da produção de embriões na fertilização in vitro e transferência de embriões para doadoras Nelore. Repositório Alice
BELTRAME, R. T.; QUIRINO, C. R.; BARIONI, L. G.; DIAS, Â. J. B.; SOUZA, P. M. de..
Ajustou-se uma função de densidade probabilidade para o número de embriões viáveis produzidos após fertilização in vitro em doadoras da raça Nelore, a partir de dados fornecidos pela Associação Brasileira de Criadores de Zebu (ABCZ), referente à análise de 20.619 doadoras, 71.602 aspirações e um total de 509.643 embriões. Modelou-se a densidade probabilidade do número de embriões viáveis mediante a função exponencial, executando-se a determinação dos parâmetros por meio da máxima verossimilhança, em um método de gradiente não linear. O nível de precisão obtido foi de RMSE = 0,040 e R2 = 0,98, para a representação da probabilidade do número de embriões viáveis produzidos por doadoras Nelore na técnica de fertilização in vitro(FIV). Para comparar os modelos...
Tipo: Artigo em periódico indexado (ALICE) Palavras-chave: Banco de dados; Densidade probabilidade; Embriões na fertilização in vitro; Simulação; Doadoras da raça Nelore; Databases; Simulation; Statistics.
Ano: 2010 URL: http://www.alice.cnptia.embrapa.br/handle/doc/875499
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