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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Avaliação de impacto do Proagro Mais: um estudo de caso / Impact evaluation of Proagro Mais: a case study

Carlos Andres Oñate Paredes 18 March 2016 (has links)
Esta pesquisa avalia o impacto do \"Programa de Garantia da Atividade Agropecuária\" para agricultores familiares, conhecido como Proagro Mais. A relevância do trabalho fundamenta-se no considerável tamanho do Programa dentro do contexto das políticas de gestão de risco agrícola no Brasil. Além disso, é a primeira pesquisa desse tipo na literatura científica do país. A amostra é formada por produtores de milho do Estado do Paraná, tendo como linha base o ano de 2003, uma vez que é o ano anterior ao lançamento do Proagro Mais, e o ano de 2005 como ano de impacto. A base de dados utilizada neste estudo foi fornecida pelo Tribunal de Contas da União (TCU), cujas variáveis relevantes incluem características da cultura e dos agricultores familiares, como área financiada, atividades agrícolas complementares, educação e rendimento esperado. Adicionalmente, a partir de outras fontes públicas, foram adicionadas variáveis meteorológicas e regionais para controlar a localização da fazenda. O objetivo da pesquisa é avaliar o impacto do Proagro Mais sobre o montante de crédito por hectare concedido aos beneficiários do Programa. As metodologias usadas incluem o Propensity Score Matching (PSM), a Diferença das Diferenças (DID) e dois estimadores condicionais do DID com PSM usando dados em painel e repeated cross-section. As estimativas econométricas mostram que o Efeito Médio do Tratamento nos Tratados (EMTT) teve sinal negativo na maioria dos modelos revelando que, após o período de perda de rendimento, o grupo de controle teve um valor médio mais elevado de crédito por hectare do que os beneficiários do Proagro Mais. Os resultados sugerem a existência de mecanismos que poderiam complementar ou substituir o Proagro Mais como instrumento de gestão de risco agrícola, mas também podem sugerir que o Programa avaliado não cubra todos os riscos do setor. / This research evaluates the impact of the \"Farm Activity Guarantee Program for Smallholders\" or Proagro Mais. The relevance of this research relies on the considerable size of the program within the context of agricultural risk management policies in Brazil. This research is also the first of its kind in the scientific literature in Brazil. It was used a sample of small-scale corn producers from the State of Paraná. It was assumed 2003 as the baseline since it is the year prior to the launch of Proagro Mais, and 2005 as the endline. The database used in this study was provided by the Federal Accounting Court of Brazil (TCU). The relevant variables include crop and growers characteristics such as area financed, complementary agricultural activities, education, and expected yield. It was also added meteorological and regional variables from other public sources to control farm location. The main objective of the research is to evaluate the impact of Proagro Mais on the amount of credit per hectare granted to the beneficiaries of the Program. The methodology includes Propensity Score Matching (PSM), Difference-in-Difference (DID), and two conditional DID along PSM estimators, using longitudinal and repeated cross-sections data. The econometric estimates show that the Average Treatment Effect on the Tread (ATET) was negative. This suggests that after the yield loss period, the control group got a higher average amount of credit per hectare than Proagro Mais beneficiaries. Thus, the question that arises is whether there may be other agricultural risk management mechanisms more suited for smallholders than Proagro Mais, or whether the evaluated program could not achieve its main goal because it does not cover all risks faced by its beneficiaries.
12

A Power Saving Mechanism for Web Traffic in IEEE 802.11 Wireless LAN

Jiang, Jyum-Hao 26 July 2010 (has links)
Web browsing via Wi-Fi wireless access networks has become a basic function on a variety of consumer mobile electronic devices, such as smart phones, PDAs, and the Apple iPad. It has been found that in terms of energy consumption, wireless communications/networking plays an important role in mobile devices. Since the power-saving mode (PSM) of the IEEE 802.11 a/b/g standard is not tailored for the HTTP protocol, we propose a novel power saving scheme that exploits the characteristics of web applications. After sending HTTP requests, the proposed power saving scheme updates the estimated value of RTT based on the information contained in the TCP timestamp header field. Next, the proposed scheme adjusts the value of the listening period based on the estimated value of RTT. When all TCP connections have been closed, the wireless network card could enter the deep-sleeping mode. In this case, the value of the listening period could be larger than one second, since the user is reading the webpage and is unlikely to send another HTTP request within one second. The usage of the deep-sleeping mode can significantly reduce the power consumption of mobile devices.
13

Placering av Phase Change Material i en yttervägg för minskning av köpt energi? : Fallstududie Ljusbo prototyphus

Nilsson, Marcus, Lindström, Magnus January 2018 (has links)
I dagens samhälle använder vi stora mängder energi och denna energi kommer huvudsakligen från fossila bränslen. Byggnadssektorn står för ca 40% av den totala energianvändningen och den termiska komforten har stor betydelse för hur mycket energi vi använder till byggnaden. Resultat från tidigare forskning visar att fasomvandlingsmaterial (PCM) kan lagra värme och kyla och på så sätt balansera temperaturen i en byggnad så att den termiska komforten blir bättre. Dagens samhälle är beroende av att förnybara energikällor skall börja användas för att främja en hållbar utveckling. Genom att sammankoppla PCM med solenergi skulle en hållbar energikälla kunna uppnås. Ljusbo Green Building satsar på att bli ett så kallat plushus, där man producerar mer energi än vad som görs av med. Syftet med studien var att studera om PCM kan bidra till att minska en byggnads energianvändning genom att placera ett PCM i ytterväggkonstruktion. Frågeställningen var om energibehovet minskar till byggnaden genom att inkludera PCM i en vägg enligt Ljusbos standard? Med simuleringar i COMSOL Multiphysics 5.3 utförs en fallstudie på Ljusbos prototypbyggnad för att se om ett PCM-material som placeras i en ytterväggkonstruktion kan minska energianvändningen hos byggnaden. PCM-materialet värms med varm uteluft dagtid eller soluppvärmd uteluft, så att värmen som tillförts uteluften minskar transmissionsförlusten genom ytterväggen. Resultatet visar att då PCM placeras i mitten av en yttervägg minskar värmeflödet från byggnaden under kallare perioder då uppvärmd luft tillförs i väggen. Det ger samma effekt oberoende på vilken fasförändringstemperatur som väljs på PCM:et. Studiens slutsats var att PCM kan minska värmeflödet från byggnaden under kallare perioder, men ger ingen effekt under varmare perioder.
14

The Role of Institutional Antecedents in Public Service Motivation and the Impact of Altruism, Empathy, and Public Service Motivation on Prosocial Behavior among Local Government Employees

Emerson, Melissa C 17 May 2014 (has links)
The purpose of this dissertation is twofold: first, this research aims to contribute to the understanding of the roots of public service motivation and explore whether it is appropriate to ground the public service motivation concept in institutional theory; second, this research will analyze the relationship between altruism, public service motivation, empathy levels, and prosocial behavior. The field of public administration has witnessed a proliferation of research in public service motivation, both internationally and across the United States. A substantial amount of research has been conducted at the federal and state levels on public service motivation, leaving the local level of government largely underrepresented. Researchers have developed and refined measurement techniques for the public service motivation construct and have extensively examined the consequences of public service motivation as they pertain to public management techniques and approaches. However, the role institutions play in the development of public service motivation is largely unexamined. Additionally, the impact of public service motivation on prosocial behavior has not been thoroughly examined. This research attempts to fill these gaps in the literature. Using data derived from survey responses from 903 employees of ten local governments in Mississippi, this research examines an underrepresented group in public service motivation literature. This research analyzes the role that various institutional antecedents play in the development of public service motivation among local government employees, finding that four out of the seven institutional antecedents studied were significant: educational level, parenting status, parental modeling, and spirituality. It also analyzes the impact of public service motivation, empathy, and altruism levels on the prosocial behavior of local government employees in society. Results show that public service motivation is positively correlated to prosocial behavior; whereas empathy and altruism are not statistically significant.
15

Adaptive Similarity of XML Data / Adaptive Similarity of XML Data

Jílková, Eva January 2014 (has links)
In the present work we explore application of XML schema mapping in conceptual modeling of XML schemas. We expand upon the previous efforts to map XML schemas to PIM schema via a decision tree. In this thesis more versatile method is implemented - the decision tree is trained from a large set of user- annotated mapping decision samples. Several variations of training that could improve the mapping results are proposed. The approach is evaluated in a wide range of experiments that show the advantages and disadvantages of the proposed variations of training. The work also contains a survey of different approaches to schema mapping and description of schema used in this work. Powered by TCPDF (www.tcpdf.org)
16

Solução numérica do modelo constitutivo KBKZ-PSM para escoamentos com superfícies livres / Numerical solution of the KBKZ-PSM constitutive model for flows with free surfaces

Bertoco, Juliana 29 November 2016 (has links)
Escoamentos viscoelásticos não estacionários com superfícies livres são comuns em muitos processos industriais e diversas técnicas numéricas têm sido empregadas para reproduzir computacionalmente estes processos. A maioria dos modelos empregados utiliza equações diferenciais na definição do tensor de tensões. Porém, para alguns grupos de fluidos complexos, por exemplo, fluidos de Boger, os modelos integrais mostram-se mais capacitados em fornecer uma boa aproximação para os comportamentos não lineares desses fluidos. Este trabalho trata da solução numérica do modelo constitutivo integral KBKZ-PSM para escoamentos transientes bidimensionais com superfícies livres. O método numérico proposto é uma técnica numérica que utiliza diferenças finitas para simular escoamentos com superfícies livres na presença de paredes sólidas. As principais características do método numérico proposto são: solução das equações de conservação de quantidade de movimento e massa utilizando um método semi-implícito; a condição de contorno na superfície livre é acoplada à equação de Poisson, o que garante conservação de massa; a discretização do tempo t é realizada por uma nova técnica numérica; o tensor de Finger é calculado pelo método dos campos de deformação e avançado no tempo pelo método de Euler modificado. Essa nova técnica é verificada em escoamentos cisalhantes e elongacionais. Adicionalmente, uma solução analítica desenvolvida para escoamentos em canais bidimensionais é empregada para verificar e analisar a convergência do método proposto. Com relação a escoamentos com superfícies livres, a convergência é verificada por meio de refinamento de malha nas simulações de um jato incidindo sobre placa rígida e no problema do inchamento do extrudado. Finalmente, o método é aplicado para investigar os problemas jet buckling e inchamento do extrudado de fluidos KBKZ-PSM. / Unsteady viscoelastic free surface flows are common in many industrial processes and a variety of numerical techniques have been employed to simulate these flows. The majority of constitutive models employed are based on differential equations to define the extra stress tensor. However, for some complex fluids, for instance, Boger fluids, integral models are more adequate to approximate the nonlinear behaviour of these fluids. This work deals with the numerical solution of the integral constitutive model KBKZ-PSM for two-dimensional unsteady free surface flows. The proposed numerical method is a numerical technique that employs finite differences to simulate moving free surface flows that interact with solid walls. The main features of the method are: numerical solution of the momentum and mass equations by an implicit method; the pressure condition on the free surface is implicitly coupled with the Poisson equation for obtaining the pressure field from mass conservation; a novel scheme for defining the past times t is employed; the Finger tensor is calculated by the deformation fields method and is advanced in time by the modified Euler method. This new technique is verified by solving shear and uniaxial elongational flows. Moreover, an analytic solution for channel flows is obtained that is used in the verification and convergence analysis of the proposed methodology. For free surface flows, the assessment of convergence lies on the mesh refinement on the simulation of a jet impinging on a flat surface and the extrudade swell problem. Finally, the new method is applied to investigate the jet buckling phenomenon and extrudate swell of KBKZ-PSM fluids.
17

Solução numérica do modelo constitutivo KBKZ-PSM para escoamentos com superfícies livres / Numerical solution of the KBKZ-PSM constitutive model for flows with free surfaces

Juliana Bertoco 29 November 2016 (has links)
Escoamentos viscoelásticos não estacionários com superfícies livres são comuns em muitos processos industriais e diversas técnicas numéricas têm sido empregadas para reproduzir computacionalmente estes processos. A maioria dos modelos empregados utiliza equações diferenciais na definição do tensor de tensões. Porém, para alguns grupos de fluidos complexos, por exemplo, fluidos de Boger, os modelos integrais mostram-se mais capacitados em fornecer uma boa aproximação para os comportamentos não lineares desses fluidos. Este trabalho trata da solução numérica do modelo constitutivo integral KBKZ-PSM para escoamentos transientes bidimensionais com superfícies livres. O método numérico proposto é uma técnica numérica que utiliza diferenças finitas para simular escoamentos com superfícies livres na presença de paredes sólidas. As principais características do método numérico proposto são: solução das equações de conservação de quantidade de movimento e massa utilizando um método semi-implícito; a condição de contorno na superfície livre é acoplada à equação de Poisson, o que garante conservação de massa; a discretização do tempo t é realizada por uma nova técnica numérica; o tensor de Finger é calculado pelo método dos campos de deformação e avançado no tempo pelo método de Euler modificado. Essa nova técnica é verificada em escoamentos cisalhantes e elongacionais. Adicionalmente, uma solução analítica desenvolvida para escoamentos em canais bidimensionais é empregada para verificar e analisar a convergência do método proposto. Com relação a escoamentos com superfícies livres, a convergência é verificada por meio de refinamento de malha nas simulações de um jato incidindo sobre placa rígida e no problema do inchamento do extrudado. Finalmente, o método é aplicado para investigar os problemas jet buckling e inchamento do extrudado de fluidos KBKZ-PSM. / Unsteady viscoelastic free surface flows are common in many industrial processes and a variety of numerical techniques have been employed to simulate these flows. The majority of constitutive models employed are based on differential equations to define the extra stress tensor. However, for some complex fluids, for instance, Boger fluids, integral models are more adequate to approximate the nonlinear behaviour of these fluids. This work deals with the numerical solution of the integral constitutive model KBKZ-PSM for two-dimensional unsteady free surface flows. The proposed numerical method is a numerical technique that employs finite differences to simulate moving free surface flows that interact with solid walls. The main features of the method are: numerical solution of the momentum and mass equations by an implicit method; the pressure condition on the free surface is implicitly coupled with the Poisson equation for obtaining the pressure field from mass conservation; a novel scheme for defining the past times t is employed; the Finger tensor is calculated by the deformation fields method and is advanced in time by the modified Euler method. This new technique is verified by solving shear and uniaxial elongational flows. Moreover, an analytic solution for channel flows is obtained that is used in the verification and convergence analysis of the proposed methodology. For free surface flows, the assessment of convergence lies on the mesh refinement on the simulation of a jet impinging on a flat surface and the extrudade swell problem. Finally, the new method is applied to investigate the jet buckling phenomenon and extrudate swell of KBKZ-PSM fluids.
18

Motivationens modererande effekt på stress i offentlig sektor

Ericsson, Emma, Günther, Matilda January 2019 (has links)
Denna uppsats bidrar till forskning kring hur motivation påverkar relationen mellan stressorer och arbetsrelaterad stress. Specifikt studeras hur offentliganställdas motivation att arbeta för samhället, deras Public Service Motivation (PSM) påverkar den effekt kvoten mellan ansträngning och belöning har på deras stress. Sambandet mellan stress och kvoten av ansträngning och belöning (E/R-kvoten) förutspås av Effort Reward Imbalance-modellen. Denna modell tar dock enbart hänsyn till extern belöning, utgångspunkten är att individer med hög PSM är starkt motiverade av interna belöningsfaktorer, vilket antas ha en modererande effekt på modellens samband. Uppsatsen undersöker därmed den modererande effekten av PSM på sambandet mellan E/R-kvoten och stress hos svenska socionomer. Frågeställningen undersöktes genom en enkätstudie med 172 respondenter. Resultaten ger stöd för uppsatsens hypotes och visar att PSM har en negativ modererande inverkan på E/R-kvotens effekt på stress. Dessa resultat stöder delvis tidigare forskning men öppnar också nya möjligheter för framtida studier.
19

Evaluating and Improving the Performance of MPI-Allreduce on QLogic HTX/PCIe InifiniBand HCA

Mittenzwey, Nico 30 June 2009 (has links) (PDF)
This thesis analysed the QLogic InfiniPath QLE7140 HCA and its onload architecture and compared the results to the Mellanox InfiniHost III Lx HCA which uses an offload architecture. As expected, the QLogic InfiniPath QLE7140 HCA can outperform the Mellanox InfiniHost III Lx HCA in latency and bandwidth terms on our test system in various test scenarios. The benchmarks showed, that sending messages with multiple threads in parallel can increase the bandwidth greatly while bi-directional sends cut the effective bandwidth for one HCA by up to 30%. Different all-reduce algorithms where evaluated and compared with the help of the LogGP model. The comparison showed that new all-reduce algorithms can outperform the ones already implemented in Open MPI for different scenarios. The thesis also demonstrated, that one can implement multicast algorithms for InfiniBand easily by using the RDMA-CM API.
20

An Apache Hadoop Framework for Large-Scale Peptide Identification

Donepudi, Harinivesh 01 July 2015 (has links)
Peptide identification is an essential step in protein identification, and Peptide Spectrum Match (PSM) data set is huge, which is a time consuming process to work on a single machine. In a typical run of the peptide identification method, PSMs are positioned by a cross correlation, a statistical score, or a likelihood that the match between the trial and hypothetical is correct and unique. This process takes a long time to execute, and there is a demand for an increase in performance to handle large peptide data sets. Development of distributed frameworks are needed to reduce the processing time, but this comes at the price of complexity in developing and executing them. In distributed computing, the program may divide into multiple parts to be executed. The work in this thesis describes the implementation of Apache Hadoop framework for large-scale peptide identification using C-Ranker. The Apache Hadoop data processing software is immersed in a complex environment composed of massive machine clusters, large data sets, and several processing jobs. The framework uses Apache Hadoop Distributed File System (HDFS) and Apache Mapreduce to store and process the peptide data respectively.The proposed framework uses a peptide processing algorithm named CRanker which takes peptide data as an input and identifies the correct PSMs. The framework has two steps: Execute the C-Ranker algorithm on Hadoop cluster and compare the correct PSMs data generated via Hadoop approach with the normal execution approach of C-Ranker. The goal of this framework is to process large peptide datasets using Apache Hadoop distributed approach.

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