Consulta: subjectFacets:"Diffusion"
Registros recuperados: 48
Data/hora: 07/06/2024 10:30:31

Effective diffusivity and convective mass transfer coefficient during the drying of bananas
Provedor de dados: 70
Autores: Silva,Cleide M. D. P. da S. e; Silva,Wilton P. da; Farias,Vera S. de O.; Gomes,Josivanda P.
In this article, a methodology is used for the simultaneous determination of the effective diffusivity and the convective mass transfer coefficient in porous solids, which can be considered as an infinite cylinder during drying. Two models are used for optimization and drying simulation: model 1 (constant volume and diffusivity, with equilibrium boundary condition), and model 2 (constant volume and diffusivity with convective boundary condition). Optimization algorithms based on the inverse method were coupled to the analytical solutions, and these solutions can be adjusted to experimental data of the drying kinetics. An application of optimization methodology was made to describe the drying kinetics of whole bananas, using experimental data available in...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Drying kinetics; Algorithm optimization; Diffusion; Porous media.
Ano: 2012
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-69162012000200014

Documento orientador da pesquisa em difusão de tecnologia.
Provedor de dados: 14
Autores: EMBRAPA.
bitstream/item/23583/1/Documento-Orientador.pdf
Tipo: Documentos (INFOTECA-E)
Palavras-chave: Difusão.; Tecnologia.; Diffusion; Technology.
Ano: 1983
URL: http://www.infoteca.cnptia.embrapa.br/infoteca/handle/doc/89269

Experimentação e validação de tecnologias em meio real: alguns elementos a partir da experiência de Massaroca (Juazeiro,BA).
Provedor de dados: 14
Autores: TONNEAU, J. P.; SABOURIN, E.
Princípios e enfoques; Massarroca: métodos de aprendizagem e de apoio à inovação; Os ensinamentos do projeto Massaroca.
Tipo: Capítulo em livro técnico (INFOTECA-E)
Palavras-chave: Adocao de inovacao; Difusao; Bahia; Massaroca; Familiar farms; Small farmers; Methods; Desenvolvimento rural; Agricultura Familiar; Aprendizagem; Método; Pequeno Produtor; Tecnologia; Rural development; Diffusion; Education; Innovation adoption; Technology.
Ano: 2000
URL: http://www.infoteca.cnptia.embrapa.br/infoteca/handle/doc/134114

Anais...
Provedor de dados: 14
Autores: ENCONTROS REGIONAIS SOBRE DIFUSÃO DE TECNOLOGIA, 1986, Brasília, DF.
Programacao dos encontros; Marco conceitual da difusao de tecnologia e organizacao do DDT; Propostas apresentadas pelo DDT; Problemas e sugestoes prioritarias por regioes.
Tipo: Documentos (INFOTECA-E)
Palavras-chave: Difusao; Policy; Articulation; Communication; Agricultura; Articulação; Comunicação; Política; Tecnologia; Agriculture; Diffusion.
Ano: 1990
URL: http://www.infoteca.cnptia.embrapa.br/infoteca/handle/doc/85151

Mapeamento morfologico em areas do Tropico Semi-Árido.
Provedor de dados: 14
Autores: MANTOVANI, L. E.; RICHE, G. R.
Foram selecionadas diferentes areas do tropico semi-arido para fins de cartografia morfopedologica visando apoiar operacoes de pesquisa e extensao rural. A tecnica empregada utiliza interpretacao detalhada em fotografias aereas ou mosaicos de radar feita apos um reconhecimento previo das zonas mapeadas.
Tipo: Fôlder / Folheto / Cartilha (INFOTECA-E)
Palavras-chave: Natural resource.; Cartografia; Extensão Rural; Geomorfologia; Pesquisa; Recurso Natural.; Diffusion; Geomorphology; Cartography; Research.; Natural resources.
Ano: 1983
URL: http://www.infoteca.cnptia.embrapa.br/infoteca/handle/doc/132504

Proposta para reestruturação organizacional da área de difusão de tecnologia do CNPGC.
Provedor de dados: 14
Autores: CARVALHO, E. G. de; SOARES, M. R. J.; SANTOS, M. A. U. C. de O.; MARIANTE, A. da S.; CARDOSO, E. E.; SILVEIRA, E. C.; OLIVEIRA, J. P. de; OLIVEIRA, J. N.; SILVA, M. M. F. da; BARBOSA, W. D.
Tecnologia; Difusão.
Tipo: Documentos (INFOTECA-E)
Palavras-chave: Agropecuária; Difusão.; Tecnologia.; Diffusion; Technology.
Ano: 1987
URL: http://www.infoteca.cnptia.embrapa.br/infoteca/handle/doc/317231

ALVES, E. R. de A. Fundamentos sobre sistema de produção.
Provedor de dados: 14
Existe num dado momento do tempo um estoque de conhecimentos que podem ser classificados em dois grupos. No primeiro grupo estão os conhecimentos "Sistematizados" ou seja podem ser deduzidos de um pequeno conjunto de princípios fundamentais. No segundo grupo estão os conhecjmentos que não foram ainda sistematizados. Estão a espera que se construa uma teoria que possa unificá-los.
Tipo: Documentos (INFOTECA-E)
Palavras-chave: Technical assistance; Rural extension.; Sistema de produção; Agricultura; Assistência Técnica; Extensão Rural; Transferência de Tecnologia.; Tecnologia; Diffusion; Technology.
Ano: 1985
URL: http://www.infoteca.cnptia.embrapa.br/infoteca/handle/doc/90974

Geração e difusão de inovações agropecuárias no Brasil: a experiência da EMBRAPA com ênfase na pequena produção.
Provedor de dados: 14
Autores: BEZERRA, F. F.
Missao institucional e prioridades da EMBRAPA; Modelo institucional/articulacao pesquisa x extensao rural; O enfoque da EMBRAPA em relacao ao pequeno produtor.
Tipo: Documentos (INFOTECA-E)
Palavras-chave: Agropecuaria; Geracao; Difusao; Generation; EMBRAPA.; Tecnologia.; Diffusion; Agriculture; Technology.; Small farms.
Ano: 1988
URL: http://www.infoteca.cnptia.embrapa.br/infoteca/handle/doc/91052

Guia de referência para jornalistas: produção de soja em sistemas sustentáveis.
Provedor de dados: 14
Autores: NASCIMENTO, L. L. do.
bitstream/item/191847/1/Guia-referencia-Jornalistas-OL-1.pdf
Tipo: Fôlder / Folheto / Cartilha (INFOTECA-E)
Palavras-chave: Jornalismo; Soja; Difusão de Tecnologia; Soybeans; Diffusion; Journalists.
Ano: 2019
URL: http://www.infoteca.cnptia.embrapa.br/infoteca/handle/doc/1105251

PROGRAMA de difusão da cultura da soja no nordeste do Brasil.
Provedor de dados: 14
bitstream/item/100437/1/Programa-de-difusao-da-cultura.pdf
Tipo: Documentos (INFOTECA-E)
Palavras-chave: Difusao; Programa; Brasil; Regiao nordeste; Soybean; Program; Northeast region.; Soja.; Diffusion; Brazil.
Ano: 1981
URL: http://www.infoteca.cnptia.embrapa.br/infoteca/handle/doc/96418

A self-regularising DVM–PSE method for the modelling of diffusion in particle methods
Provedor de dados: 5
Autores: Mycek, Paul; Pinon, Gregory; Germain, Gregory; Rivoalen, Elie.
The modelling of diffusive terms in particle methods is a delicate matter and several models have been proposed in the literature. The Diffusion Velocity Method (DVM) consists in rewriting these terms in an advective way, thus defining a so-called diffusion velocity. In addition to the actual velocity, it is used to compute the particles displacement. On the other hand, the well-known and commonly used Particle Strength Exchange method (PSE) uses an approximation of the Laplacian operator in order to model diffusion. This approximation is based on an exchange of particles strength.  Although DVM is particularly well suited to particle methods since it preserves their Lagrangian aspect, its major drawback stems in the fact that it suffers from severe...
Tipo: Text
Palavras-chave: Particle method; Diffusion; DVM; PSE.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00159/27006/25254.pdf

Underwater vehicle navigation using diffusion-based trajectory observers
Provedor de dados: 5
Autores: Jouffroy, J; Opderbecke, Jan.
This paper addresses the issue of estimating underwater vehicle trajectories using gyro-Doppler (body-fixed velocities) and acoustic positioning signals (earth-fixed positions). The approach consists of diffusion-based observers processing a whole trajectory segment at a time, allowing the consideration of important practical problems such as different information update rates, outages, and outliers in a very simple framework. Results of contraction theory are used to prove that the observers are convergent, i.e., stable in the incremental sense. Simulation and experimental results are presented to illustrate the potential of application of the method.
Tipo: Text
Palavras-chave: Underwater vehicles; Underwater navigation; Trajectory observers; Trajectory estimation; Observers; Diffusion; Cartography.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/publication-4967.pdf

Characterization of sea water ageing effects on mechanical properties of carbon/epoxy composites for tidal turbine blades
Provedor de dados: 5
Autores: Tual, Nicolas; Carrere, N.; Davies, Peter; Bonnemains, T.; Lolive, E.
In recent years, many tidal turbine projects have been developed using composites blades. Tidal turbine blades are subject to ocean forces and sea water aggressions, and the reliability of these components is crucial to the profitability of ocean energy recovery systems. The majority of tidal turbine developers have preferred carbon/epoxy blades, so there is a need to understand how prolonged immersion in the ocean affects these composites. In this study the long term behaviour of different carbon/epoxy composites has been studied using accelerated ageing tests. A significant reduction of composite strengths has been observed after saturation of water in the material. For longer immersions only small further changes in these properties occur. No...
Tipo: Text
Palavras-chave: Carbon; Seawater ageing; Diffusion; Mechanical testing.
Ano: 2015
URL: http://archimer.ifremer.fr/doc/00278/38964/37504.pdf

A numerical scheme for coastal morphodynamic modelling on unstructured grids
Provedor de dados: 5
Autores: Guerin, Thomas; Bertin, Xavier; Dodet, Guillaume.
Over the last decade, modelling systems based on unstructured grids have been appearing increasingly attractive to investigate the dynamics of coastal zones. However, the resolution of the sediment continuity equation to simulate bed evolution is a complex problem which often leads to the development of numerical oscillations. To overcome this problem, addition of artificial diffusion or bathymetric filters are commonly employed methods, although these techniques can potentially over-smooth the bathymetry. This study aims to present a numerical scheme based on the Weighted Essentially Non-Oscillatory (WENO) formalism to solve the bed continuity equation on unstructured grids in a finite volume formulation. The new solution is compared against a classical...
Tipo: Text
Palavras-chave: Morphodynamic modelling; Unstructured grid; WENO; Diffusion; Coastal environments; Exner equation.
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00606/71851/70480.gif

Diffusion parameters of grain-growth inhibitors in WC based hardmetals with Co, Fe/Ni and Fe/Co/Ni binder alloys
Provedor de dados: 5
Autores: Buchegger, Christoph; Lengauer, Walter; Bernardi, Johannes; Gruber, Jakob; Ntaflos, Theo; Kiraly, Franz; Langlade, Jessica.
The diffusion behaviour of the grain-growth inhibitors (GGI) Cr and V during early sintering stages from 950-1150 °C was investigated by means of diffusion couples of the type WC-GGI-binder/WC-binder. Besides Co, also alternative Fe/Ni and Fe/Co/Ni binder alloys were investigated. It was found that the diffusion in green bodies differs significantly from sintered hardmetals. Diffusivities in the binder phase were determined from diffusion couples prepared from model alloys and were found to be almost equal for Co and alternative binder alloys. The diffusion parameters determined from green bodies allowed to estimate the GGI distribution in a hardmetal during heat up. This was subsequently used to estimate an appropriate grain size of VC and Cr3C2 in...
Tipo: Text
Palavras-chave: Hardmetal; Early sintering stage; Grain-growth inhibitor; Diffusion; Alternative binder.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00194/30491/28896.pdf

ユーラシア大陸乾燥地帯における乳文化圏二元論
Provedor de dados: 19
Autores: 平田, 昌弘; HIRATA, Masahiro.
日本西アジア考古学会より了承を得て転載
Palavras-chave: 乳文化圏; 乳加工体系; 牧畜; 伝播; ユーラシア大陸; Milk cultural sphere; Milk processing system; Pastoralism; Diffusion; Eurasia.
Ano: 2003
URL: http://ir.obihiro.ac.jp/dspace/handle/10322/3182

Efficiency and sustainability gains from adoption of short-duration pigeonpea in nonlegume-based cropping systems
Provedor de dados: 30
Autores: M.C.S.
Palavras-chave: Pigeonpeas; Millets; Grain legumes; Tropical zones; Wheats; Soil fertility; Diffusion; Cropping systems; Legumes; Electrophoresis.
Ano: 1999
URL: http://agropedia.iitk.ac.in/openaccess/?q=node/4212

Assessing Adoption Potential of New Groundnut Varieties in Malawi
Provedor de dados: 30
Autores: H.A.
Palavras-chave: Gene banks; Variety trials; Groundnuts; On-farm research; Economic indicators; Diffusion; Research methods; Sowing rates; Early maturation; Agronomy.
Ano: 2002
URL: http://agropedia.iitk.ac.in/openaccess/?q=node/3746

Efficiency and sustainability gains from adoption of short-duration pigeonpea in nonlegume - based cropping systems
Provedor de dados: 30
Autores: M.C.S.( editor ).
Palavras-chave: Pigeonpeas; Millets; Grain legumes; Tropical zones; Wheats; Soil fertility; Diffusion; Cropping systems; Legumes; Electrophoresis.
Ano: 1999
URL: http://agropedia.iitk.ac.in/openaccess/?q=node/3147

Returns to research and diffusion investments on wilt resistance in pigeonpea
Provedor de dados: 30
Autores: M.C.S.
Palavras-chave: Pigeonpeas; Diffusion; Sowing rates; Variable costs; Seed production; Land management; Genotypes; Agricultural statistics; Budgets; Sampling.
Ano: 1996
URL: http://agropedia.iitk.ac.in/openaccess/?q=node/4192

Assessment of the economic impact of sorghum variety S 35 in Chad
Provedor de dados: 30
Autores: A.M.
Palavras-chave: Variable costs; Sorghum; Diffusion; Extension activities; Sowing date; Fixed costs; Repellents; Seed dressing; Farm inputs; Costs.
Ano: 1999
URL: http://agropedia.iitk.ac.in/openaccess/?q=node/4206

Impact of germplasm research spillovers: the case of sorghum variety S 35 in Cameroon and Chad
Provedor de dados: 30
Autores: A.M.
Palavras-chave: Sorghum; Diffusion; Germplasm; Grain; Breeds (animals); Pure lines; Sowing date; Early maturation; Land management; Costs.
Ano: 1999
URL: http://agropedia.iitk.ac.in/openaccess/?q=node/4207

Analysis of the economic impact of sorghum and millet research in Mali
Provedor de dados: 30
Autores: A.M.
Palavras-chave: Millets; Sorghum; Breeds (animals); Diffusion; Early maturation; Budgets; Cereals; Germplasm; Introduced varieties.
Ano: 2000
URL: http://agropedia.iitk.ac.in/openaccess/?q=node/4219

Potassium supply to cotton roots as affected by potassium fertilization and liming
Provedor de dados: 86
Autores: Rosolem,Ciro Antonio; Silva,Rosemeire Helena da; Esteves,José Antonio de Fátima.
Cotton (Gossypium hirsutum) is known to have a high requirement for K and to be very sensitive to low soil pH. Most of K reaches plant roots by diffusion in the soil. As K interacts with Ca and Mg, liming can interfere in K movement in the soil, affecting eventually the plant nutrition. The objective of this work was to study the effect of dolomitic lime and 0, 15, 30, 45 and 60 g kg-1 of K on the supply of K to cotton roots. Cotton plants were grown up to 40 days in 5 L pots containing a Dark Red Latosol (Typic Haplusthox) with 68% and 16% of sand and clay, respectively. There was an increase in dry matter yields and in K accumulation due to K fertilization. Root interception of soil K was also increased by K application, but was not affected by lime....
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Gossypium hirsutum; Mass; Diffusion; Liming materials; Roots; Growth; Plant nutrition.
Ano: 2003
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-204X2003000500012

THE CHOICE BETWEEN CONVENTIONAL AND ORGANIC FARMING – A HUNGARIAN EXAMPLE
Provedor de dados: 31
Autores: Ferto,   Imre; Forgacs,   Csaba.
The organic agriculture represents a promising alternative for the future of European agriculture. It is consistent with the notion of sustainable development set forth already in the 1992 CAP Reform. Despite of increasing importance of organic farming, the research on organic farming is still limited. This scarcity of the research is especially true for New Member States of the enlarged EU. This paper investigates the choice between conventional and organic production technologies for individual farmers in Hungarian agriculture. We apply a model that explicitly accounts for the effects of farm-specific variables like age and education on the expectations farmers have on the utility of both production technologies. In addition we take into account the...
Tipo: Conference Paper or Presentation
Palavras-chave: Innovation; Attitudes; Organic production; Diffusion; Agribusiness; Crop Production/Industries; Food Consumption/Nutrition/Food Safety.
Ano: 2009
URL: http://purl.umn.edu/57488

Metro, Micro, and Non-Core:  A 3-year Portrait of Broadband Supply and Demand in Oklahoma
Provedor de dados: 31
Autores: Whitacre,   Brian E.
Rural communities suffer from both supply and demand-side disadvantages when dealing with Internet access.  Telecommunications companies are less likely to provide them with needed infrastructure due to lower population densities, and they also tend to have lower levels of specific factors known to influence the access decision such as education and income.  This study looks at the broadband Internet setting in Oklahoma over a 3-year period, examining the diffusion of both infrastructure and access rates.  A non-linear decomposition technique allows for measurement of how specific characteristics, including the availability of infrastructure, contribute to observed metropolitan – micropolitan or metropolitan – noncore “digital divides.”  The results...
Tipo: Conference Paper or Presentation
Palavras-chave: Broadband; Internet; Diffusion; Rural; Community/Rural/Urban Development; R11; O18; C1.
Ano: 2009
URL: http://purl.umn.edu/55929

THE ROLE OF SOCIOECONOMIC FACTORS AND LIFESTYLE VARIABLES IN ATTITUDE AND THE DEMAND FOR GENETICALLY MODIFIED FOODS
Provedor de dados: 31
Autores: Heiman,   Amir; Just,   David R.; Zilberman,   David.
Consumer resistance is a key barrier to the diffusion of genetically modified foods (GMFs). Several studies have shown that consumers in general have a negative attitude toward GMFs. Through analysis of a survey conducted in Israel, we find consumer attitudes toward GMFs to be context specific, differing based on the available alternatives. Consumers responded positively to genetically modified meats when given the alternative choice of meats produced with hormones or dyes.  We also address the importance of gender, education, and being religious on the consumer's attitude toward GMFs. Both education and being religious have significant effects on attitude, while gender does not.
Tipo: Journal Article
Palavras-chave: Biotechnology; Consumer attitudes; Diffusion; Genetically modified foods; Food Consumption/Nutrition/Food Safety; Research and Development/Tech Change/Emerging Technologies.
Ano: 2000
URL: http://purl.umn.edu/14713

Naive Learning in Social Networks: Convergence, Influence and Wisdom of Crowds
Provedor de dados: 31
Autores: Jackson,   Matthew O.; Golub,   Benjamin; Jackson,   Matthew O.
We study learning and influence in a setting where agents communicate according to an arbitrary social network and naively update their beliefs by repeatedly taking weighted averages of their neighbors' opinions. A focus is on conditions under which beliefs of all agents in large societies converge to the truth, despite their naive updating. We show that this happens if and only if the influence of the most influential agent in the society is vanishing as the society grows. Using simple examples, we identify two main obstructions which can prevent this. By ruling out these obstructions, we provide general structural conditions on the social network that are sufficient for convergence to truth. In addition, we show how social influence changes when some...
Tipo: Working or Discussion Paper
Palavras-chave: Social Networks; Learning; Diffusion; Bounded Rationality; Institutional and Behavioral Economics; D85; D83; A14; L14; Z13.
Ano: 2007
URL: http://purl.umn.edu/9101

How Homophily Affects Learning and Diffusion in Networks
Provedor de dados: 31
Autores: Golub,   Benjamin; Jackson,   Matthew O.
We examine how three different communication processes operating through social networks are affected by homophily - the tendency of individuals to associate with others similar to themselves. Homophily has no effect if messages are broadcast or sent via shortest paths; only connection density matters. In contrast, homophily substantially slows learning based on repeated averaging of neighbors' information and Markovian diffusion processes such as the Google random surfer model. Indeed, the latter processes are strongly affected by homophily but completely independent of connection density, provided this density exceeds a low threshold. We obtain these results by establishing new results on the spectra of large random graphs and relating the spectra to...
Tipo: Working or Discussion Paper
Palavras-chave: Networks; Learning; Diffusion; Homophily; Friendships; Social Networks; Random Graphs; Mixing Time; Convergence; Speed of Learning; Speed of Convergence; Institutional and Behavioral Economics; D83; D85; I21; J15; Z13.
Ano: 2009
URL: http://purl.umn.edu/50718

Policy-Induced Technology Adoption: Evidence from the U.S. Lead Phasedown
Provedor de dados: 31
Autores: Kerr,   Suzi; Newell,   Richard G.
The theory of environmental regulation suggests that economic instruments, such as taxes and tradable permits, create more effective technology adoption incentives than conventional regulatory standards. We explore this issue for an important industry undergoing technological responses to a dramatic decrease in allowed pollution levels - the petroleum industry's phasedown of lead in gasoline. Using a panel of refineries from 1971 to 1995, we provide some of the first direct evidence that alternative policies affect the pattern of adoption in expected ways. Importantly, we find that the tradable permit system used during the lead phasedown provided incentives for more efficient technology adoption decisions. Where environmentally appropriate, this suggests...
Tipo: Working or Discussion Paper
Palavras-chave: Technology; Adoption; Diffusion; Environment; Regulation; Lead; Gasoline; Tradable permit; Incentive-based policy; Research and Development/Tech Change/Emerging Technologies; C41; L71; O31; O33; Q28; Q48.
Ano: 2001
URL: http://purl.umn.edu/10834

Marketing via Friends: Strategic Diffusion of Information in Social Networks with Homophily
Provedor de dados: 31
Autores: Chuhay,   Roman.
The paper studies the impact of homophily on the optimal strategies of a monopolist, whose marketing campaign of new product relies on a word of mouth communication. Homophily is a tendency of people to interact more with those who are similar to them. In the model there are two types of consumers embedded into a social network, which differ in friendship preferences and desirable design of product. Consumers can learn about the product directly from an advertisement or from their neighbors. The monopolist chooses the product design and price to influence a pattern of communication among consumers. We  find a number of results: (i) for low levels of homophily the product attractive to both types of consumers is preferred to specialized products; (ii) the...
Tipo: Working or Discussion Paper
Palavras-chave: Networks; Word of Mouth; Viral Marketing; Homophily; Diffusion; Social Networks; Random Graphs; Monopoly; Pricing Strategy; Product Design; Marketing; Advertisement; Environmental Economics and Policy; D21; D42; D60; D83; L11; L12.
Ano: 2010
URL: http://purl.umn.edu/96667

The Partnership and Network Strategy
Provedor de dados: 31
Autores: Clark,   Richard A.
The theory and practice of sustainable improvement and innovation partnerships and networks design and management can be enhanced in agricultural industries. The BPP project can contribute to enhanced real-world practices, and the research and development of better mechanisms, for the design and management of innovation partnerships and networks. The Partnership and Network Strategy is designed to accelerate the rate, scale and impact of valuable improvements and innovations in the beef industry by involving key players in the industry and ensuring support for all partners.
Tipo: Article
Palavras-chave: Partnerships; Networks; Clusters; Networking; Support; Dissemination; Diffusion; Farm Management.
Ano: 2008
URL: http://purl.umn.edu/122183

Evaluation de la diffusion et de l’adoption des variétés de riz NERICA en Guinée
Provedor de dados: 31
Autores: Diagne,   Aliou; Sogbossi,   Marie-Josee; Diawara,   Sekou; Diallo,   Abdoulaye Sadio; Barry,   Alpha Bacar.
L’objectif de la présente étude est d’évaluer la diffusion et l’adoption des variétés de riz NERICA en Guinée cinq années après leur introduction. Les données collectées en 2002 sont relatives à  1535 paysans choisis dans 79 villages des quatre régions naturelles de la Guinée. L’approche d’estimation du taux d’adoption utilisée dans ce papier se fonde sur les théories modernes  d’évaluation au niveau micro-économique des impacts d’interventions politiques.  Nos résultats montrent que 39% de la population guinéenne connaissaient au moins une variété NERICA en 2001 avec 23% pour le taux d’adoption observé au sein de la population de riziculteurs. Plusieurs facteurs socio-économiques déterminent les taux de diffusion et d’adoption. Par ailleurs bien que le...
Tipo: Conference Paper or Presentation
Palavras-chave: Mots clés Riz; NERICA; Diffusion; Adoption; Average Treatment Effect; Guinée; Agricultural and Food Policy; Consumer/Household Economics; Demand and Price Analysis; Farm Management; Food Consumption/Nutrition/Food Safety; Food Security and Poverty; Institutional and Behavioral Economics; International Relations/Trade; Land Economics/Use; Production Economics; Research and Development/Tech Change/Emerging Technologies.
Ano: 2008
URL: http://purl.umn.edu/52153

Markets, Contracts, or Integration? The Adoption, Diffusion, and Evolution of Organizational Form
Provedor de dados: 31
Autores: Sykuta,   Michael E.; Klein,   Peter G.; James,   Harvey S., Jr.
The rise of contract farming and vertical integration is one of the most important changes in modern agriculture. Yet the adoption and diffusion of these new forms of organization has varied widely across regions, commodities, or farm types, however. Transaction cost theories and the like are not fully effective at explaining the variation of adoption rates of different organizational forms, in part because of their inherent static nature. In order to explain the adoption, diffusion and evolution of organizational form, a more dynamic framework is required. This paper lays out such a framework for understanding the evolution of organizational practices in U.S. agriculture by drawing on existing theories of economic organization, the diffusion of...
Tipo: Conference Paper or Presentation
Palavras-chave: Contracting; Vertical integration; Organizational innovation; Diffusion; Institutional and Behavioral Economics; L14; L22; Q13; O33.
Ano: 2005
URL: http://purl.umn.edu/19390

Potential Adoption of Genetically Modified Rapeseed in France, Effects on Revenues of Farmers and Upstream Companies: an ex ante evaluation
Provedor de dados: 31
Autores: Desquilbet,   Marion; Lemarie,   Stephane; Levert,   Fabrice.
In this paper, we conduct an empirical investigation of potential adoption of herbicide-tolerant (HT) genetically modified (GM) rapeseed in France. Our aim is to study ex ante the potential impact of their adoption in France, in terms of adoption level, economic gains, and distribution of these gains between farmers and input suppliers. We use French survey data about current plant protection practices, in order to compute pesticide costs with conventional (i.e., non GM) crops for individual farms. Then, based on results of technical studies about GM variety trials in France, we compute a predicted pesticide cost with the GM variety. Next, we study adoption rates and gains or losses of farmers (adopters and non adopters) and upstream companies (sellers of...
Tipo: Conference Paper or Presentation
Palavras-chave: Genetically modified organisms; Innovation; Diffusion; Rapeseed; Consumer/Household Economics.
Ano: 2002
URL: http://purl.umn.edu/24975

ADOPT: a tool for predicting adoption of agricultural innovations
Provedor de dados: 31
Autores: Kuehne,   Geoff; Llewellyn,   Rick S.; Pannell,   David J.; Wilkinson,   Roger; Dolling,   P.; Ewing,   Michael A.
A wealth of evidence exists about the adoption of new practices and technologies in agriculture but there does not appear to have been any attempt to simplify this vast body of research knowledge into a model to make quantitative predictions across a broad range of contexts. This is despite increasing demand from research, development and extension agencies for estimates of likely extent of adoption and the likely timeframes for project impacts. This paper reports on the reasoning underpinning the development of ADOPT (Adoption and Diffusion Outcome Prediction Tool). The tool has been designed to: 1) predict an innovation‘s likely peak extent of adoption and likely time for reaching that peak; 2) encourage users to consider the influence of a structured...
Tipo: Conference Paper or Presentation
Palavras-chave: Adoption; Diffusion; Prediction; Research and Development/Tech Change/Emerging Technologies.
Ano: 2011
URL: http://purl.umn.edu/100570

Is organic farming a chance for family farms to survive?
Provedor de dados: 31
Autores: Ferto,   Imre; Forgacs,   Csaba.
The paper investigates the choice between conventional and organic production technologies for individual farmers in Hungarian agriculture. We employ sequential logit model on a cross-section data set of Hungarian farmers for the period 2007. Our estimations reveal that age of farmers has negative, whilst being full time farmers and having more diversified production structure have positive impact on the intention for being organic farmers. Furthermore, it appears that education, being full time farmers and more diversified production structure positively influence the final decision between conventional and organic farming.
Tipo: Conference Paper or Presentation
Palavras-chave: Innovation; Attitudes; Organic production; Diffusion; Agricultural and Food Policy; Institutional and Behavioral Economics; Political Economy.
Ano: 2010
URL: http://purl.umn.edu/90800

Is organic farming a chance for family farms to survive?
Provedor de dados: 31
Autores: Ferto,   Imre; Forgacs,   Csaba.
The paper investigates the choice between conventional and organic production technologies for individual farmers in Hungarian agriculture. We employ sequential logit model on a cross-section data set of Hungarian farmers for the period 2007. Our estimations reveal that age of farmers has negative, whilst being full time farmers and having more diversified production structure have positive impact on the intention for being organic farmers. Furthermore, it appears that education, being full time farmers and more diversified production structure positively influence the final decision between conventional and organic farming.
Tipo: Conference Paper or Presentation
Palavras-chave: Innovation; Attitudes; Organic production; Diffusion; Agribusiness; Agricultural and Food Policy.
Ano: 2009
URL: http://purl.umn.edu/52862

THE CHOICE BETWEEN CONVENTIONAL AND ORGANIC FARMING. A HUNGARIAN EXAMPLE
Provedor de dados: 31
Autores: Ferto,   Imre; Forgacs,   Csaba.
The paper deals with organic produce in one of the largest and, concerning organic production one of the most diffused counties in Hungary, Pest County located in the north-central part of the country. Factors influencing farmers’ decision on adopting or not e.g. farm size, farm type, location, structure, market for organic products, existence of organic AEM were analysed. Hypotheses based on previous empirical literature were tested by a model explicitly accounting for the effects of farm-specific variables like age, education, size of farms and share of rented land. Logit model was estimated on a cross-section data set of Hungarian farmers for the period 2007. It appears that education has a positive impact on the choice between conventional and organic...
Tipo: Journal Article
Palavras-chave: Innovation; Attitudes; Organic production; Diffusion; Agri-environmental measures; Agricultural and Food Policy; Crop Production/Industries; Food Consumption/Nutrition/Food Safety.
Ano: 2009
URL: http://purl.umn.edu/53568

Effective diffusivity in yacon potato cylinders during drying
Provedor de dados: 91
Autores: Lisboa,Cícera G. C. de; Gomes,Josivanda P.; Figueirêdo,Rossana M. F. de; Queiroz,Alexandre J. de M.; Diógenes,Adelino de M. G.; Melo,João C. S. de.
ABSTRACT The aim of this study was to obtain the effective diffusivity of yacon potato in fixed-bed dryer at different temperatures (50, 60 and 70 ºC) and drying air velocities (1.0, 1.5 and 2.0 m s-1). Non-linear regression analysis was performed by the Quasi-Newton method using the program Statistica 7.0, where the parameters of the models were estimated as a function of the drying air temperature. Approximation of Diffusion, Two Terms, Henderson &amp; Pabis, and Page models fitted well the experimental data. Drying air temperature and speed influenced the drying time of the samples. The effective diffusivity increased with increasing temperature, ranging from 1.18 x 10-9 to 2.15 x 10-9 m2 s-1.
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Smallanthus sonchifolia; Mathematical modelling; Diffusion.
Ano: 2018
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-43662018000800564

Transport coefficients for low and high-rate mass transfer along a biological horizontal cylinder
Provedor de dados: 91
Autores: Barreto,Alberto A.; Fortes,Mauri; Ferreira,Wanyr R.; Crespo,Luiz C. A.
Knowledge of heat and mass transfer coefficients is essential for drying simulation studies or design of food and grain thermal processes, including drying. This work presents the full development of a segregated finite element method to solve convection-diffusion problems. The developed scheme allows solving the incompressible, steady-state Navier-Stokes equations and convective-diffusive problems with temperature and moisture dependent properties. The problem of simultaneous energy, momentum and species transfer along an infinite, horizontal cylinder under drying conditions in forced convection is presented, considering conditions normally found in biological material thermal treatment or drying. Numerical results for Nusselt and Sherwood numbers were...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Drying; Heat transfer; Convection; Diffusion.
Ano: 2006
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-43662006000200027

Physical-chemical characterization of yellow mombin (Spondias mombin L.) foam-mat drying at different temperatures
Provedor de dados: 91
Autores: Freitas,Bheatriz S. M. de; Cavalcante,Maisa D.; Cagnin,Caroline; Silva,Richard M. da; Plácido,Geovana R.; Oliveira,Daniel E. C. de.
ABSTRACT The objective of this work was to perform foam-mat drying of yellow mombin pulp, verifying the kinetics and mathematical modeling of the process, and characterizing the obtained product with respect to physical and chemical characteristics, compared with the fresh pulp. Foam-mat drying was carried out with the aid of the foam agent Emustab®, at temperatures of 50, 60, 70 and 80 °C. The drying data were analyzed and fitted to four mathematical models (Wang &amp; Singh, Verma, Page and Midilli). Effective diffusion coefficient and activation energy were determined. Titratable acidity, pH, soluble solids content and vitamin C content, as well as the solubility in water of yellow mombin powder and color variance (L*, a*, b*) were analyzed in both...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Drying kinetics; Diffusion; Mathematical modeling.
Ano: 2018
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-43662018000600430

Indices of movement behaviour: conceptual background, effects of scale and location errors
Provedor de dados: 103
Autores: Almeida,Paulo J. A. L.; Vieira,Marcus V.; Kajin,Maja; Forero-Medina,German; Cerqueira,Rui.
A fundamental step in the emerging Movement Theory is the description of movement paths, and the identification of its proximate and ultimate drivers. The most common characteristic used to describe and analyze movement paths is its tortuosity, and a variety of tortuosity indices have been proposed in different theoretical or empirical contexts. Here we review conceptual differences between five movement indices and their bias due to locations errors, sample sizes and scale-dependency: Intensity of Habitat use (IU), Fractal D, MSD (Mean Squared Distance), Straightness (ST), and Sinuosity (SI). Intensity of Habitat use and ST are straightforward to compute, but ST is actually an unbiased estimator of oriented search and ballistic movements. Fractal D is...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Diffusion; Fractal dimension; Oriented search; Random walk; Search behaviour.
Ano: 2010
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1984-46702010000500002

DRYING KINETICS OF UNRIPE PLANTAIN CHIPS USING CHARCOAL FUELLED CABINET DRYER.
Provedor de dados: 111
Autores: Famurewa, John Alaba Victor.
This study presents the thin layer drying behavior of unripe plantain slices (Musa paradisiaca) in a developed biomass cabinet dryer. The developed dryer provided an environment with an optimum operating temperature between 50 - 700C meant for drying agricultural materials. The use of thin layer drying mechanisms and equations contribute to better understanding of drying food materials. The thin layer drying behaviour of agricultural products was identified based on the mathematical models which describe the heat and mass transfer phenomena of the products. In order to select a suitable drying model, fourteen different thin layer drying models were fitted to experimental data. Fick’s second law was used to calculate the moisture diffusivity with some...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Food Engineering Thin layer; Mathematical modelling; Diffusion; Drying  biomass fuel.
Ano: 2015
URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/3028

Determination of drying characteristics and kinetics of bitter kola (garcinia kola) using page’s model
Provedor de dados: 111
Autores: Chinaka, Ehiem James.
Single-layer drying characteristics and kinetics of garcinia kola was studied with slice thicknesses of 1mm, 3mm, 5mm and 7mm at temperatures 45oC, 55oC, 65oC and 75oC using natural convention laboratory oven . The results obtained revealed that garcinia kola slices dried in the falling rate period. Moisture ratio, characteristics drying rate constant, drying time, effective diffusivity and activation energy were significantly (p
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Agricultural &amp; Bioresources Engineering/Postharvest Processing and Storage Engineering Garcinia kola; Kinetics; Diffusion; Activation energy; Page’s model.
Ano: 2014
URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/2987

A new analytical formulation of retention effects on particle diffusion processes
Provedor de dados: 42
Autores: Bevilacqua,Luiz; Galeão,Augusto C.N.R.; Costa,Flavio P.
The ultimate purpose of this paper is to present a new analytical formulation to simulate diffusion with retention in a reactive medium under stable thermodynamic conditions. The analysis of diffusion with retention in a continuum medium is developed after the solution of an equivalent problem using a discrete approach. The new law may be interpreted as the reduction of all diffusion processes with retention to a unifying phenomenon that can adequately simulate the retention effect namely a circulatory motion. It is remarkable that the governing equation requires a fourth order differential term as suggested by the discrete approach. The relative fraction of diffusion particles β is introduced as a control parameter in the diffusion-retention law as...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Diffusion; Retention; Constitutive law; Discrete approach; Population dynamics; Fourth order differential equations.
Ano: 2011
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652011000400031

Diffusion Signal in Magnetic Resonance Imaging: Origin and Interpretation in Neurosciences
Provedor de dados: 48
Autores: CHABERT,STEREN; SCIFO,PAOLA.
Diffusion Magnetic Resonance Imaging provides images of unquestionable diagnostic value. It is commonly used in the assessment of stroke and in white matter fiber tracking, among other applications. The diffusion coefficient has been shown to depend on cell concentration, membrane permeability, and cell orientation in the case of white matter or muscle fiber tracking; yet a clear relation between diffusion measurements and known physiological parameters is not established. The aim of this paper is to review hypotheses and actual knowledge on diffusion signal origin to provide assistance in the interpretation of diffusion MR images. Focus will be set on brain images, as most common applications of diffusion MRI are found in neuroradiology. Diffusion signal...
Tipo: Journal article
Palavras-chave: Diffusion; Magnetic Resonance Imaging; Interpretation; Non Gaussian.
Ano: 2007
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602007000500003

Tomato Infrared Drying: Modeling and some Coefficients of the Dehydration Process
Provedor de dados: 117
Autores: Cesar Corrêa,Paulo; Horta de Oliveira,Gabriel Henrique; Machado Baptestini,Fernanda; Martins Silva Diniz,Mayra Darliane; Almeida da Paixão,Aline.
Infrared dehydration is more advantageous than the convective system under similar conditions, and studying this process is important to further develop equipment and procedures. Thus, the aim of this work was to study the dehydration process of tomato (Solanum lycopersicum L.) slices obtained by infrared drying at three different maturity stages throughout two different procedures: Firstly, the drying model was determined by applying the mass and energy balances under wet bulb temperature for the constant drying rate period and secondly, the mass effective diffusion coefficient was determined throughout the experimental data and the theory of diffusion of the liquid phase for the decreasing drying rate period. Tomato fruits cv. Santa Cruz were used. Three...
Tipo: Journal article
Palavras-chave: Critical moisture content; Diffusion; Finite element method; Heat and mass transfer; Mathematical modeling.
Ano: 2012
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-58392012000200015