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A Multi-Observation Least-Squares Inversion for GNSS-Acoustic Seafloor Positioning ArchiMer
Sakic, Pierre; Ballu, Valerie; Royer, Jean-yves.
Monitoring deformation on the seafloor is a major challenge for modern geodesy and a key to better understanding tectonic processes and assess related hazards. The extension of the geodetic networks offshore can be achieved by combining satellite positioning (GNSS) of a surface platform with acoustic ranging to seafloor transponders. This approach is called GNSS-Acoustic (GNSS-A). The scope of this work is to provide a tool to identify and quantify key points in the error budget of such experiment. For this purpose, we present a least-squares inversion method to determine the absolute position of a seafloor transponder array. Assuming the surface platform is accurately positioned by GNSS, the main observables are the two-way travel time in water between...
Tipo: Text Palavras-chave: Seafloor geodesy; Offshore geodesy; Absolute seafloor positioning; GNSS-Acoustic; Simulations; Least-squares inversion; Acoustic two-way-travel times; Depth differences; Baseline lengths.
Ano: 2020 URL: https://archimer.ifremer.fr/doc/00659/77080/78401.pdf
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Análise dos Resultados de Operações de Hedging com Contratos Futuros de Boi Gordo da BM&F: 2001 a 2006 AgEcon
Alves, Alexandre Florindo; Serra, Marco Henrique.
O presente estudo tem como objetivo, usando simulações, analisar as operações de hedge com contratos de boi gordo da Bolsa de Mercadorias & Futuros (BM&F). As simulações compreenderam o período de 2001 a 2006, sendo que em todos os anos os contratos simulados são do mesmo vencimento, outubro com entrada na operação no mês de março, em três estados diferentes: São Paulo, Paraná e Mato Grosso do Sul. A estratégia de utilização do mercado futuro mostrou-se viável, desde que acompanhada do conhecimento de fatores que interferem no mecanismo de comercialização: o comportamento da base e do risco de base em cada região. O conhecimento e o acompanhamento destes fatores, através dos anos, tem fundamental importância na tomada de decisão para operações no...
Tipo: Conference Paper or Presentation Palavras-chave: Boi gordo; Contratos futuros; Simulações; Hedge; Live cattle; Futures contracts; Simulations; Hedge; Livestock Production/Industries; Marketing; Risk and Uncertainty.
Ano: 2008 URL: http://purl.umn.edu/102471
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Detecting outliers in species distribution data: Some caveats and clarifications on a virtual species study ArchiMer
Meynard, Christine N.; Kaplan, David; Leroy, Boris.
Liu et al. (2018) used a virtual species approach to test the effects of outliers on species distribution models. In their simulations, they applied a threshold value over the simulated suitabilities to generate the species distributions, suggesting that using a probabilistic simulation approach would have been more complex and yield the same results. Here, we argue that using a probabilistic approach is not necessarily more complex and may significantly change results. Although the threshold approach may be justified under limited circumstances, the probabilistic approach has multiple advantages. First, it is in line with ecological theory, which largely assumes non‐threshold responses. Second, it is more general, as it includes the threshold as a...
Tipo: Text Palavras-chave: ENM; Observation errors; Outliers; Prevalence; Probabilistic approach; Sample bias; Simulations; Species distribution models; Virtual ecology; Virtual species.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00501/61309/64868.pdf
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Diagnosis and validation by computational fluid dynamics of poultry house with negative pressure ventilation AGRIAMBI
Cunha,Gisele C. de A.; Lopes Neto,José P.; Furtado,Dermeval A.; Borges,Valéria P.; Freire,Elias A.; Nascimento,José W. B. do.
ABSTRACT Negative pressure ventilation in poultry houses has been used to enable the correction of their internal microclimates, and studies point to the heterogeneous distribution of air along the aviaries and the inadequacy of the environmental variables to the recommended ranges for thermal comfort of adult birds, especially in the hottest hours of the day. This study aimed to diagnose the facilities of a poultry house in the state of Paraíba, Brazil, regarding the distribution of environmental variables and thermal comfort; develop a computational model and validate it for Computational Fluid Dynamic - CFD simulations. Air temperature (Tair), air relative humidity (RH) and air velocity (Vair) data allowed characterizing the internal environment by...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Thermal comfort; Thermal index; Simulations.
Ano: 2019 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-43662019001000761
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EXPERIMENTAL MARKETS USING THE ELECTRONIC MARKET PLACE (EMP) AgEcon
Fackler, Paul L.; McNew, Kevin.
A computer system for implementing electronic markets on networks of personal computers is described. The program allows a researcher or teacher to design market simulations to meet a variety of goals, and records a complete set of market activities for analysis. Illustrations of example markets are provided, and the classroom application of market simulations in teaching agricultural economics is discussed.
Tipo: Journal Article Palavras-chave: Computer software; Experimental economics; Simulations; Marketing.
Ano: 1998 URL: http://purl.umn.edu/15094
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Integrating research tools to support the management of social-ecological systems under climate change Ecology and Society
Miller, Brian W.; Department of the Interior North Central Climate Science Center, Natural Resource Ecology Laboratory, Colorado State University; brian.miller@colostate.edu; Morisette, Jeffrey T.; Department of the Interior North Central Climate Science Center, Natural Resource Ecology Laboratory, Colorado State University; U.S. Geological Survey; morisettej@usgs.gov.
Developing resource management strategies in the face of climate change is complicated by the considerable uncertainty associated with projections of climate and its impacts and by the complex interactions between social and ecological variables. The broad, interconnected nature of this challenge has resulted in calls for analytical frameworks that integrate research tools and can support natural resource management decision making in the face of uncertainty and complex interactions. We respond to this call by first reviewing three methods that have proven useful for climate change research, but whose application and development have been largely isolated: species distribution modeling, scenario planning, and simulation modeling. Species distribution...
Tipo: Peer-Reviewed Synthesis Palavras-chave: Agent-based modeling; Complex-adaptive systems; Natural resource management; Scenario planning; Simulations; Species distribution modeling; State-and-transition modeling.
Ano: 2014
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Modèle hydro-sédimentaire du bassin de Marennes-Oléron : présentation et principaux résultats. 1992 ArchiMer
Raillard, Olivier; Le Hir, Pierre.
Le bassin conchylicole de Marennes-Oléron fait l'objet d'une étude par modèle mathématique. L'outil est élaboré par étapes successives qui voient la mise en jeu de nouveaux processus et l'introduction de nouvelles variables (Bacher, 1989 ; Raillard, 1991). La forte variabilité spatio-temporelle des matériaux dissous et particulaire de la baie a focalisé l'attention sur les processus hydrodynamiques. Les modèle de couplage des processus physiques et biologiques développés jusqu'à présent ont privilégié la représentation des phénomènes biologiques en moyennant dans le temps et l'espace les phénomènes physiques. Un tel choix s'est avéré inadapté pour simuler la variabilité spatiale et temporelle du bassin de Marennes-Oléron (Raillard, 1991). L'objectif du...
Tipo: Text Palavras-chave: Modèle hydro-sédimentaire; ¨Production primaire; Production secondaire; Simulations; Bassin de Marennes Oléron; Charente Maritime.
Ano: 1993 URL: http://archimer.ifremer.fr/doc/00102/21302/18922.pdf
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Modelo dinámico para evaluar la trazabilidad en el mercado de carne de bovino: caso México Colegio de Postgraduados
Herrera Ayala, Lucila.
En la actualidad la trazabilidad en el mercado de carne de bovino se está tornando una herramienta trascendente, principalmente para los países que se han visto afectados por la Encefalopatía Espongiforme Bovina (EEB) u otra enfermedad zoonótica. Esta medida se está dando en respuesta a los requerimientos de los consumidores, quienes cada vez solicitan más información sobre el producto que están adquiriendo, debido a estas exigencias los principales exportadores de carne de bovino tienen que recurrir a esta nueva tendencia, de lo contrario perderían mercados y se vería gravemente afectada su economía. La presente investigación tuvo como finalidad evaluar la posible implementación de un sistema de trazabilidad en el mercado de carne de bovino en...
Tipo: Tesis Palavras-chave: Encefalopatía espongiforme bovina; Simulaciones; Valor del inventario; Maestría; Economía; Bovine spongiform encephalopathy; Simulations; Cattle value.
Ano: 2009 URL: http://hdl.handle.net/10521/1305
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Sequential process to choose efficient sampling design based on partial prior information data and simulations ArchiMer
Kermorvant, Claire; Coube, Sébastien; D’amico, Frank; Bru, Noëlle; Caill-milly, Nathalie.
Issues on sampling procedure definition led numerous study results to be biased and object of controversy. Choosing relevant sampling design and number of samples is a difficult task when wanted to set up or optimize a survey. The survey design choice is very important to avoid bias and increase the survey cost-efficiency. It can have a strong effect on the sample size needed to achieve some targeted accuracy on results. And on the final cost of the procedure. The sequential process we expose here melt design based and model based sampling theories. Its objectives is helping practitioners defining a sampling design and a number of samples for their survey when inference to the whole population is wanted. The main idea is to mathematically reconstruct the...
Tipo: Text Palavras-chave: Accuracy; Cost-effectiveness; Survey; Simulations; Survey optimization; Virtual ecology.
Ano: 2020 URL: https://archimer.ifremer.fr/doc/00619/73140/72306.pdf
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Tax Deductions, Consumption Distortions, and the Marginal Excess Burden of Taxation AgEcon
Parry, Ian W.H..
Certain types of expenditure--e.g. mortgage interest and medical insurance—- receive favorable tax treatment and are effectively subsidized relative to other (non-tax-favored) expenditures. Labor taxes (e.g. income taxes) can therefore produce efficiency losses by distorting the allocation of consumption, in addition to distorting the labor market. Using evidence on the responsiveness of taxable income to changes in tax rates, a seminal study by Feldstein (1999) estimates that the marginal excess burden of taxation (MEB) could exceed unity, when the effects of tax deductions are taken into account. This is several times larger than in previous studies of the MEB that focus exclusively on labor market effects. This paper develops a "disaggregated" approach...
Tipo: Working or Discussion Paper Palavras-chave: Welfare costs; Tax system; Tax deductions; Simulations; Political Economy; H21; H43.
Ano: 1999 URL: http://purl.umn.edu/10801
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Testing methods in species distribution modelling using virtual species: what have we learnt and what are we missing? ArchiMer
Meynard, Christine N.; Leroy, Boris; Kaplan, David.
Species distribution models (SDMs) have become one of the major predictive tools in ecology. However, multiple methodological choices are required during the modelling process, some of which may have a large impact on forecasting results. In this context, virtual species, i.e., the use of simulations involving a fictitious species for which we have perfect knowledge of its occurrence‐environment relationships and other relevant characteristics, have become increasingly popular to test SDMs. This approach provides for a simple virtual ecologist framework under which to test model properties, as well as the effects of the different methodological choices, and allows teasing out the effects of targeted factors with great certainty. This simplification is...
Tipo: Text Palavras-chave: Artificial species; Environmental niche models; Niche; Simulations; Species distribution modelling; Virtual ecologist.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00501/61308/64864.pdf
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What Drives Land-Use Change in the United States? A National Analysis of Landowner Decisions AgEcon
Lubowski, Ruben N.; Plantinga, Andrew J.; Stavins, Robert N..
Land-use changes involve important economic and environmental effects with implications for international trade, global climate change, wildlife, and other policy issues. We use an econometric model to identify factors driving land-use change in the United States between 1982 and 1997. We quantify the effects of net returns to alternative land uses on private landowners’ decisions to allocate land among six major uses, drawing on detailed micro-data on land use and land quality that are comprehensive of the contiguous U.S. This analysis provides the first evidence of the relative historical importance of markets and Federal farm policies affecting land-use changes nationally.
Tipo: Working or Discussion Paper Palavras-chave: Land Use; Land-Use Change; Econometric Analysis; Simulations; Land Economics/Use; O51; Q15.
Ano: 2008 URL: http://purl.umn.edu/44534
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