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Registros recuperados: 12
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A dynamic dual model under state-contingent production uncertainty AgEcon
Serra, Teresa; Stefanou, Spiro E.; Oude Lansink, Alfons G.J.M..
In this paper we assess how production costs and capital accumulation patterns in agriculture have evolved over time, by paying special attention to the influence of risk. A dynamic state-contingent cost minimization approach is applied to assess production decisions in US agriculture over the last century. Results suggest the relevance of allowing for the stochastic nature of the production function which permits to capture both the differences in the costs of producing under different states of nature, the differences in the evolution of these costs over time, as well as the differential impacts of different states of nature on investment decisions.
Tipo: Conference Paper or Presentation Palavras-chave: Risk; State-contingent; Dynamic model; Investment decisions; Agricultural and Food Policy; Farm Management; Land Economics/Use; D21.
Ano: 2010 URL: http://purl.umn.edu/61353
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A Dynamic Model of Mesh Size Regulatory Compliance AgEcon
Akpalu, Wisdom.
This paper employs a dynamic model for crimes that involve time and punishment to analyze the use of a net with illegal mesh size in a management regime where each community claims territorial use right over a fishery but has a discount rate that may differ from the social discount rate. The equilibrium stock and harvest levels are found to be much lower if the regulation is violated. Moreover, the optimal penalty for violation must be decreasing in the shadow cost of taking the risk to fish illegally, and increasing the risk of punishment increases the equilibrium stock level.
Tipo: Journal Article Palavras-chave: Crime; Dynamic model; Fishery; Regulation; Resource /Energy Economics and Policy.
Ano: 2010 URL: http://purl.umn.edu/61059
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BIOMECHANICAL PROPERTIES OF WOLFBERRY PLANT ORGANS REA
Ma,Fulong; Li,Lekai; Wang,Yutan; Li,Ping; Zhu,Chaowei.
ABSTRACT To improve the picking rate and reduce the wrong picking rate of the existing wolfberry harvesting machinery, in this study, the binding force and physical appearance of the immature fruit stalk, mature fruit stalk, flower, and leaf were studied to guide the designing of new-generation wolfberry harvesting machinery and lay theoretical foundation for further studies on biomechanical properties of wolfberry. By preprocessing the experimental data with the Pauta criterion, the distribution range of the binding force and physical appearance of stalk were obtained; the binding force was not influenced by the picking temperature, mass of the fruit, and location of the branch of the fruit. The length-diameter ratio of mature fruit was confirmed by image...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Binding force; Biomechanical characteristics; Constitutive equation; Dynamic model; Vibrating wolfberry harvesting machinery.
Ano: 2020 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-69162020000200162
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Des modèles et des indicateurs pour évaluer la performance des Aires Marines Protégées pour la gestion des zones côtières. Application à la Réserve Naturelle des Bouches de Bonifacio ArchiMer
Rocklin, Delphine.
These last decades have been characterized by a great development of fishing techniques, contributing to the overexploitation of numerous marine fish stocks. In order to limit this collapse and to restore impacted communities, the implementation of management measures was necessary. Marine Protected Areas (MPAs), initially developed to protect remarkable habitats and associated biodiversity, are more and more used as a tool for spatial management of fishing activities, by adult export and/or larvae migrations from protected zones to surrounding fisheries. The aim of this PhD was to use indicators and predictive models for evaluating the impact of the Bonifacio Strait Natural Reserve (Corsica) implementation on fish communities and the benefits of such...
Tipo: Text Palavras-chave: Aires marines protégées; Pêche artisanale; Gestion des pêcheries; Ressource; Modélisation dynamique; Indicateurs; Gestion des zones côtières; Évaluation de scénarios; Conservation des écosystèmes; Marine protected areas; Artisanal fisheries; Fishing management; Resource; Dynamic model; Indicators; Coastal areas management; Scenarios evaluation; Ecosystems conservation.
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00285/39593/38085.pdf
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Dynamic model of the short-term variability of microphytobenthic biomass on temperate intertidal mudflats ArchiMer
Guarini, Jean-marc; Blanchard, Gf; Gros, Philippe; Gouleau, Dominique; Bacher, Cedric.
In the present paper, we list and document the relevant behavioral and physiological processes controlling primary productivity of epipelic microalgae on intertidal mudflats in order to develop a simplified model. We first propose, in an attempt to characterize the 'photosynthetically active biomass' of the epipelic community, a new approach to describe the photic environment at the sediment surface, by substituting a discrete a-layer model in place of continuous vertical light distribution. This concept thus allows us to build a functional representation of the distribution of the photosynthetically active biomass in the sediment and, by then integrating the light and temperature forcing of the latter biomass, to predict the dynamics of the whole epipelic...
Tipo: Text Palavras-chave: Microphytobenthos; Intertidal mudflat; Primary production; Dynamic model; Migratory rhythm; Ecophysiological response.
Ano: 2000 URL: http://archimer.ifremer.fr/doc/00000/10540/7601.pdf
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Impacts of Land Rental Markets on Rural Poverty in Kenya AgEcon
Jin, Songqing; Jayne, Thomas S..
This study uses panel data from 1,142 Kenya smallholder households over four survey periods to examine the determinants of participation in land rental markets and to quantify the impact of renting land on households’ crop income and total income. We find that land rental markets in Kenya enhance productivity and are equitable. The results are consistent across different estimation methods and model specifications. Dynamic panel models were used to assess the impact of rental participation on households’ crop income and total income. After controlling for the endogeneity of rental market participation and the persistent effects of lagged income, we find that the decision to rent land increased tenant households’ net crop (net total) income by 25.1 (6.6)...
Tipo: Conference Paper or Presentation Palavras-chave: Land rental market; Kenya; Income; Poverty; Dynamic model; Agricultural and Food Policy; International Development; Land Economics/Use; O12; Q13; Q12; Q15.
Ano: 2011 URL: http://purl.umn.edu/103907
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Studies on the dynamic model of plant adaptation of quantitative characters. I. Estimation of space-time parameters Taiwan Agricultural Research Institute
Lu, H. Y.; Wu, H. P..
Palavras-chave: Dynamic model; Genotype-time-environment interaction; Linear regression; [[classification]]6.
Ano: 1987
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Studies on the dynamic model of plant adaptation of quantitative characters. III. Diallel analysis Taiwan Agricultural Research Institute
Lu, H. Y.; Wu, H. P..
Palavras-chave: Arabidopsis thaliana; Diallel analysis; Dynamic model; [[classification]]6.
Ano: 1991
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The adoption of innovative cropping systems under price and production risks: a dynamic model of crop rotation choice AgEcon
Ridier, Aude; Chaib, Karim; Roussy, Caroline.
In the paper we investigate the role played by both production and market risks on farmer’s decision to adopt long rotations (over 2 years), considered as innovative cropping systems. We build a multiperiod dynamic farm model (run under GAMS) that arbitrates each year between traditional and innovative rotations. With discrete stochastic programming, the production risk is accounted as an intra-year risk; yearly farming operations are declined according to a decision tree where probabilities are assigned. Subjective yield and cost distributions linked to this decision tree are elicited among a sample of 13 farmers that are experiencing this innovation in South-western France. The price risk is randomly distributed with a given market trend. The crop...
Tipo: Presentation Palavras-chave: Innovative cropping systems; Dynamic model; Crop rotation decision; Risk; Subjective probabilities; Risk and Uncertainty; C61; D0; Q12; Q55.
Ano: 2012 URL: http://purl.umn.edu/122440
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Towards a Theory of Policy Making AgEcon
Mittenzwei, Klaus; Bullock, David S.; Salhofer, Klaus; Kola, Jukka.
The paper presents a theory of policy timing that relies on uncertainty and transaction costs to explain the optimal timing and length of policy reforms. Delaying reforms resolves some uncertainty by gaining valuable information and saves transaction costs. Implementing reforms without waiting increases welfare by adjusting domestic policies to changed market parameters. Optimal policy timing is found by balancing the trade-off between delaying reforms and implementing reforms without waiting. Our theory offers an explanation of why countries differ with respect to the length of their policy reforms, and why applied studies often judge agricultural policies to be inefficient.
Tipo: Conference Paper or Presentation Palavras-chave: Policy analysis; Uncertainty; Dynamic model; Transaction costs; Agricultural and Food Policy.
Ano: 2011 URL: http://purl.umn.edu/114639
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Use of the Dynamic Model for the Assessment of Winter Chilling in a Temperate and a Subtropical Climatic Zone of Chile Chilean J. Agric. Res.
Pérez,Francisco J; Ormeño N,Juan; Reynaert,Bryan; Rubio,Sebastián.
Accumulated chilling was estimated by applying three different models to the hourly autumn-winter temperature records from Santiago (33°34 S lat; 625 m.a.s.l.) and Vicuña (30°02´ S lat; 643 m.a.s.l.) for the years 2005 and 2006. The model of chilling hours, currently used in Chile as an agroclimatic indicator, was of limited use for effectively contrasting a subtropical condition (Vicuña) with a temperate area such as Santiago. The application of the Utah model gave negative values from March to May, and even up to June in Vicuña, since in this model the chilling effect is “negated” by warmer temperatures. However, a modified version of the Utah model named Positive Chilling Units (PCU), in which negative values are omitted, showed differences in the...
Tipo: Journal article Palavras-chave: Accumulated winter-chill; Bud dormancy; Dynamic model.
Ano: 2008 URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-58392008000200010
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水芋收穫指數的動態模式 Taiwan Agricultural Research Institute
呂秀英; 呂椿棠; 陳烈夫; Hsiu-Ying Lu;Chun-Tang Lu;Lit-Fu Chan.
[[abstract]]本研究之目的在建立水芋收穫指數之動態模式,並進而探討模式之生長參數估計值在不同種植期下的季節變異性,以解析其對最終收穫指數的影響。模式呈一種連續的三相分段線性函數,不但所有種植期下的水芋收穫指數都能配合模式良好,同時該模式能解釋收穫指數總變異的能力高達95%以上。從模式中可推測出收穫指數在遲滯期、線性增加期及成熟期之三個直線階段的速率及持續時間。根據動態模式之解析,可知收穫指數線性增加期的開始及結束受到栽培季節之氣象變化影響甚鉅,故造成最終收穫指數在不同種植期之間的季節性差異。水芋最終收穫指數之表現主要決定於線性增加期收穫指數的增加速率及持續時間,而以時間長短最為重要。至於遲滯期及成熟期的影響則不大。
Palavras-chave: 水芋 收穫指數 動態模式 三相分段線性函數 季節性變異 Wetland taro; Harvest index; Dynamic model; Three-phase piecewise linear function; Seasonal variation [[classification]]6.
Ano: 1999
Registros recuperados: 12
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