Consulta: subjectFacets:"Dynamic model"
Registros recuperados: 9
Data/hora: 04/06/2024 15:15:34

BIOMECHANICAL PROPERTIES OF WOLFBERRY PLANT ORGANS
Provedor de dados: 70
Autores: 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

Dynamic model of the short-term variability of microphytobenthic biomass on temperate intertidal mudflats
Provedor de dados: 5
Autores: 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

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
Provedor de dados: 5
Autores: 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

Impacts of Land Rental Markets on Rural Poverty in Kenya
Provedor de dados: 31
Autores: 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

Towards a Theory of Policy Making
Provedor de dados: 31
Autores: 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

A Dynamic Model of Mesh Size Regulatory Compliance
Provedor de dados: 31
Autores: 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

The adoption of innovative cropping systems under price and production risks: a dynamic model of crop rotation choice
Provedor de dados: 31
Autores: 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

A dynamic dual model under state-contingent production uncertainty
Provedor de dados: 31
Autores: 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

Use of the Dynamic Model for the Assessment of Winter Chilling in a Temperate and a Subtropical Climatic Zone of Chile
Provedor de dados: 117
Autores: 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