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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.
241

Composição e configuração da cobertura florestal na bacia hidrográfica e seus efeitos nos serviços hidrológicos / Effects of forest cover composition and spatial configuration in hydrological services at catchment scale

Lara Gabrielle Garcia 09 October 2018 (has links)
Programas de restauração florestal e pagamento por serviços ecossistêmicos vêm sendo incentivados em várias regiões que apresentam problemas de abastecimento hídrico, com objetivo de recuperação e manutenção dos recursos hídricos. Embora se considere que a cobertura florestal é benéfica para a conservação dos recursos hídricos, esta relação é complexa e dependente de vários fatores físicos, assim como da proporção e da configuração espacial da cobertura florestal na bacia hidrográfica. Diante deste contexto, o objetivo geral do presente estudo foi avaliar os efeitos da proporção e configuração espacial da cobertura florestal na bacia hidrográfica no aumento ou manutenção dos serviços hidrológicos. Para tal, um modelo hidrológico distribuído de base física foi calibrado e validado para permitir a simulação hidrológica dos diferentes usos da terra. A parametrização do modelo teve como base uma bacia hidrográfica monitorada (deflúvio e precipitação) de características agrícolas (pastagem e cana-de-açúcar). Após calibrado e validado o modelo (R2 de 0,65 e 0,62 respectivamente), os cenários a serem simulados foram gerados modificando-se a composição da paisagem (proporção de cobertura florestal) e a configuração espacial da cobertura florestal. É importante ressaltar que as modificações no modelo para cada uso foram referentes diretamente aos processos de evapotranspiração e escoamento superficial e seus desdobramentos. Não foram modificados os processos referentes ao solo (e.g. infiltração e percolação), uma vez que a influência do uso na estrutura do solo ainda é um ponto conflitante. Os serviços hidrológicos considerados foram os de disponibilidade hídrica e proteção. Os indicadores para análise da disponibilidade hídrica foram o deflúvio anual (Q), vazões mínimas (Q95) e índice de fluxo base (BFI); e os indicadores de proteção foram as vazões máximas (Q5) e índice de velocidade (IF). O efeito da proporção da cobertura florestal foi testado por meio de cenários com aumento aleatório de 10% na cobertura florestal (CF), iniciando com o cenário referência de 0% CF até o cenário referência de 100% (11 cenários simulados). As hipóteses testadas foram de que (i) o aumento da cobertura florestal diminui o serviço hidrológico de disponibilidade hídrica, e (ii) o aumento da cobertura florestal aumenta o serviço hidrológico de proteção. Ambas as hipóteses foram aceitas, uma vez que, apesar de os resultados terem apresentado diferenças relativas entre os cenários, não foi possível obter diferença estatística para todos os indicadores. Foi constatada diminuição dos indicadores de Q e Q95 e aumento nos valores de Q5 seguidos de aumento da cobertura florestal. A diferença estatística ocorreu para os indicadores Q e Q5, sendo que em ambos foi possível perceber um limiar de 50% CF, a partir do qual o deflúvio anual e o índice de máximas passaram a ser estatisticamente diferentes do cenário 0% CF. O efeito da configuração espacial foi testado por meio de simulações de cenários com a mesma proporção de cobertura florestal, mas com alterações quanto a sua configuração espacial. Foram simulados quatro cenários: CF no terço inferior (INF); CF no terço médio (MED); CF no terço superior (SUP) da bacia hidrográfica; e CF aleatoriamente distribuída na área (ALE). As hipóteses testadas foram que (i) a configuração espacial da cobertura florestal na bacia hidrográfica não tem influência no serviço hidrológico de disponibilidade de água; e (ii) a configuração espacial da cobertura florestal nas áreas próximas aos corpos hídricos (terço inferior) tem influência positiva no serviço de proteção, ou seja, no aumento deste serviço. Os resultados permitiram aceitar parcialmente as hipóteses, uma vez que apesar de relativamente ocorrer diferenças no serviço hidrológico de disponibilidade hídrica esta não foi estatisticamente significativa, o mesmo ocorrendo para o serviço de proteção. Assim como anteriormente, os resultados permitiram perceber um trade-off entre os serviços testados, pois o cenário com maior redução nos valores de Q e Q95 (INF) foi o que apresentou as maiores reduções no índice de vazão máxima. No entanto, mesmo com a diminuição nos indicadores de disponibilidade hídrica, o cenário com cobertura florestal na parte inferior da bacia hidrográfica foi considerado o mais próximo a um ótimo em relação aos serviços hidrológicos. Diante dos resultados encontrados, pode-se observar que ao se tratar de serviços hidrológicos a cobertura florestal pode apresentar trade-off entre os mesmos, sendo necessário aos programas de restauração e pagamento de serviços ambientais conhecerem esta dinâmica para maximizarem o serviço hidrológico de interesse. / Water resources recovery and maintenance are the main objectives of restoration cover forest programs and payment for ecosystem services. These programs are gaining force and incentives, especially in water crises regions. However, water resources recovery and maintenance are attributed in many cases to forest cover effects on hydrological processes and, consequently, on hydrological services. In this context, our aim in this study was to evaluate if forest cover restoration can result in increase or maintenance of hydrological services. Therefore, firstly it was necessary to calibrate and validate a distributed hydrological physical base model to simulate different land use at the catchment scale. The model parameterization was done on a monitored catchment (flow and precipitation) of agricultural characteristics (pasture and sugar cane). After calibrating and validating the model (R2 of 0.65 and 0.62, respectively), the land use scenarios were generated based on two landscape approaches: forest cover proportion and spatial configuration on catchment scale. The hydrological services used were water supply and protection; indicators for analysis were annual flow (Q), minimum flows (Q95), base flow index (BFI); maximum flows (Q5) and velocity index (IF). Q, Q95 e BFI correspond to water supply, the others are flood protection service. The first approach objective was tested forest cover proportion scenarios with a random increase in forest cover (CF) of 10%, starting with 0% CF reference scenario to 100% CF reference scenario (total of 11 simulated scenarios). The hypotheses tested were that (i) the random increase in forest cover decreases the hydrological service of water supply, and (ii) the random increase in forest cover increases the hydrological protection service. Both hypotheses were partially accepted. Since the results showed relative differences between the scenarios without statistical difference. There was a decrease in Q and Q95 indicators and an increase in Q5 values followed by an increase in forest cover. The statistical difference happened only for Q and Q5 indicators. For both hydrological services it is possible to perceive a threshold of 50% CF, from which the flow annual and the maximum index become statistically different from the 0% CF scenario. The second approach was the simulations of same forest cover proportion scenarios, however with changes in their spatial configuration. Four scenarios were simulated: CF in the lower land (LOW); CF in the middle land (MIDD); CF in the upper lands (UPP) of the river basin; and CF randomly distributed in the area (RAN). The hypotheses tested were (i) the forest cover spatial configuration has no influence on water supply hydrological service; and (ii) the forest cover spatial configuration in areas near the water bodies (lower land) has a positive impact on protection hydrological service. Our results allowed partially accepting the hypotheses, since there are relative differences in the water supply hydrological service after scenarios simulation, there was no statistically significant difference, the same occurring for the protection hydrological service. The results allow us to highlight a trade-off between hydrological services tested in this study, for example, the scenario with the greatest reduction in Q and Q95 values (LOW) also presented the greatest reductions in Q5. However, even with the decrease in water supply indicators, the LOW scenario was considered the closest to an optimum scenario to hydrological services. In view of this, we can be observed that forest cover can present hydrological services trade-off, being necessary to restoration and payment of environmental services programs to know dynamics to maximize the hydrological service of interest. It is important to emphasize that these results and analyses simulations were based on land use change scenarios (related to the evapotranspiration and surface runoff processes) and their unfolding, however, were not modified (e.g. infiltration and percolation). However, land use effects on the soil structure are still not proved a point, possibly these being key processes to forest cover restoration and hydrological services trade-off.
242

Análise e priorização das dimensões competitivas da estratégia de produção das grandes empresas da indústria moveleira de Bento Gonçalves

Luchese, Juliane 22 January 2016 (has links)
Submitted by Patrícia Valim Labres de Freitas (patricial) on 2016-03-16T15:48:14Z No. of bitstreams: 1 Juliane Luchese_.pdf: 2295311 bytes, checksum: 55706fd6328fe1f0f72ca1f58af46674 (MD5) / Made available in DSpace on 2016-03-16T15:48:14Z (GMT). No. of bitstreams: 1 Juliane Luchese_.pdf: 2295311 bytes, checksum: 55706fd6328fe1f0f72ca1f58af46674 (MD5) Previous issue date: 2016-01-22 / Nenhuma / As decisões tomadas em relação à escolha das dimensões competitivas, da estrutura e da infraestrutura, juntamente com as capacidades organizacionais, são a base para a construção de uma estratégia de produção competitiva, e uma forma de diferenciação das empresas perante seus concorrentes. Neste contexto, este estudo se propõe a identificar quais são as principais dimensões competitivas que orientam a estratégia de produção das grandes empresas da indústria moveleira do polo de Bento Gonçalves- RS sob a percepção dos gerentes de produção das mesmas. Para que seja possível alcançar o objetivo principal, foi definido alguns objetivos específicos tais como como: a) analisar o comportamento estratégico em relação as dimensões de competição das quatro empresas fabricantes de móveis de grande porte de Bento Gonçalves; b) Identificar e analisar as prioridades quanto as dimensões competitivas enfatizadas pelas empresas bem como identificar como cada empresa está estruturada em relação as áreas de decisão estruturais e infra estruturais; c) identificar sinergias e trade-offs entre as principais prioridades atribuídas nas quatro empresas. A abordagem metodológica adotada foi o estudo de caso múltiplos aplicado no principal polo moveleiro do Rio Grande do Sul, o polo da Serra Gaúcha. A escolha deste polo ocorreu devido a sua importância na geração de empregos e por sua representatividade no mercado em que essas organizações estão inseridas. Como resultado, a pesquisa evidenciou similaridade entre três empresas pesquisadas quanto a escolha das dimensões competitivas destacando a importância para as dimensões: entregas quanto a pontualidade, flexibilidade de volume, qualidade, entregas quanto a velocidade, flexibilidade de design e tecnologia de processo. Ademais, a pesquisa pretendeu servir de suporte aos gestores das pequenas e médias empresas e pesquisadores para compreender sobre a estratégia de competição em relação as dimensões competitivas adotadas pelas empresas moveleiras de grande porte. / The decisions regarding the choice of the competitive dimensions of the structure and infrastructure, along with the organizational capabilities are the foundation for building a competitive manufacturing strategy, and a way to differentiate the company to its competitors. In this context, this study aims to identify what are the main competitive dimensions that guide the production strategy of large companies in the furniture industry in Bento Gonçalves- RS, under the same perception of the production managers. To be able to achieve the main goal was set some specific goals such as :a) analyze the strategic behavior regarding the dimensions of competition of the four major furniture manufacturers of Bento Gonçalves; b) Identify and analyze the priorities for the competitive dimensions emphasized by the companies as well as identify how each company is structured in relation to the structural and infrastructural decision areas; c) identify synergies and trade-offs among the top priorities assigned in the four companies. The methodological approach adopted was the multiple case study applied in the main furniture center of Rio Grande do Sul, the center of Serra Gaucha. The choice of this center was due to its importance in the employment generation and its share of the market in which those organizations are located. As a result, the survey showed similarity between the three companies surveyed as the choice of competitive dimensions highlighting the importance for dimensions: punctuality deliveries, volume flexibility, quality, speed delivery, design flexibility and process technology. Furthermore, the research intended to provide support to small and medium companies’ managers and researchers to understand the competition strategy on the competitive dimensions adopted by large furniture companies.
243

Multifractal traffic generator modeled at the transaction level for integrates systems performance evaluation. / Gerador de tráfego multifractal modelado no nível de transações para a avaliação de desempenho de sistemas integrados.

José Eduardo Chiarelli Bueno Filho 10 February 2017 (has links)
The present work aims to provide a contribution to improve the efficiency the design flow of integrated systems, focusing, specifically, on the performance evaluation of its communication structures. The use of Transaction Level Modeling (TLM) is proposed, in order to take advantage of the reduction of design effort and time. Within the performance evaluation approaches, the utilization of traffic generators instead of full system simulations started to be adopted due to its higher time efficiency. Initial works on on-chip traffic generation focused on Poisson processes and classic Markovian models, which are unable to capture Long Range Dependence (LRD). This fact led to the adoption of fractal/self-similar models. Later advancements have shown that the traffic produced in multiprocessed systems can show higher degrees of complexity, what can be attributed to the presence multifractal characteristics. In this work, a methodology to evaluate the on-chip traffic and to the development of a transaction level traffic generator is proposed. The main contributions of this work are a detailed analysis of traffic time series obtained by TLM simulations and the study of the effects of the traffic generator on these simulations, concerning, mainly, the speedup-accuracy trade-off. The proposed analysis follow the multifractal paradigm, allowing system developers to (1) understand the statistical nature of on-chip traffic, (2) to obtain accurate representations of this traffic and (3) to build traffic generators that mimic processing elements realistically. Another contribution of this work is a comparison of the performance, considering the accuracy of the obtained synthetic traffic time series, between monofractal and multifractal models. All of the mentioned contributions were grouped throughout the detailed methodology presented on the present document, for which experiments were carried out. / O presente trabalho visa oferecer uma contribuição para o aumentar a eficiência do fluxo de projeto de sistemas integrados, focando, especificamente, na avaliação do desempenho de suas estruturas de comunicação. É proposta a utilização de simulações com modelos no nível de transações (TLM), com o objetivo de se obter vantagens da redução de esforço e tempo de projeto oferecidos por esta abordagem. Dentro das propostas de análise de desempenho, a utilização de geradores de tráfego ao invés simulações de sistema completo tem sido adotada devido a sua maior eficiência no tempo. Trabalhos iniciais na geração de tráfego intrachip focaram-se em processos de Poisson e em modelos de Markov clássicos, os quais não capturam Dependência de Longa Duração (LRD). Este fato levou a adoção de modelos fractais/auto-similares. Avanços posteriores mostraram que o tráfego produzido pelos elementos de sistemas multiprocessados podem apresentar maior grau de complexidade, que pode ser atribuída à presença de características multifractais. Neste trabalho, é proposta uma metodologia para a avaliação de tráfego intrachip para o desenvolvimento de um gerador de tráfego TLM. As principais contribuições deste trabalho são uma análise detalhada das séries temporais de tráfego obtidas nas simulações TLM e o estudo dos efeitos que o gerador de tráfego exerce sobre estas simulações, se concentrando, principalmente, na relação entre precisão e aceleração da simulação. As análises propostas se baseiam no paradigma multifractal, o qual permite (1) um maior entendimento da natureza estatística do tráfego pelos desenvolvedores de sistemas, (2) a obtenção de uma representação precisa deste tráfego e (3) a construção de geradores de tráfego que substituam elementos processantes de maneira realista. Outra contribuição deste trabalho é a comparação do desempenho, no que concerne a precisão das séries de tráfego sintéticas obtidas, de modelos monofractais e multifractais. Todas as contribuições mencionadas foram agrupadas na metodologia detalhada, apresentada no presente documento, sobre a qual experimentos foram realizados.
244

Essays on Capital Structure of Nations

Perez, Giovanni 20 December 2018 (has links)
No description available.
245

Samhällsnyttan av vattenverksamheter : Hur tillämpas samhällsnyttokravet i 11 kap. 6 § miljöbalken vid tillståndsprövning av vattenverksamheter?

Österlund, Ida January 2010 (has links)
<p>Denna uppsats handlar om hur den särskilda tillåtlighetsregeln i 11 kap. 6 § miljöbalken tillämpas vid tillståndsprövning av vattenverksamheter. Av paragrafen följer att en vattenverksamhet endast får bedrivas om den samlade nyttan av verksamheten överväger de kostnader samt skador och olägenheter som verksamheten medför. Syftet med paragrafen är att hindra vattenverksamheter som inte är <em>samhällsekonomiskt motiverade</em> samt utgöra ett extra skydd för miljön utöver miljöbalkens generella miljökrav.</p><p>Syftet med studien är undersöka hur denna paragraf tillämpas i praktiken – både i rättspraxis och i ansökningsförfarandet. Studien bygger i första hand på rättsvetenskaplig metod men ger även en mer allmän introduktion till samhällsekonomiska analysmetoder. Studien visar att det är mycket svårt att finna vägledning i praxis för <em>hur</em> en bedömning av samhällsnyttan bör gå till. Praxis visar dock att även faktorer som verksamhetens överensstämmelse med olika miljökvalitetsmål, art- och områdesskydd och estetiska värden kan få betydelse vid samhällsnyttobedömningen. Från sökandenas sida riktas generellt ett för stort fokus mot den privata eller företagsekonomiska nyttan av verksamheten. Sammantaget medför detta en risk för att miljövärden inte värderas på ett korrekt sätt när de vägs mot en mer konkret uttryckt monetär nytta. Ett bredare perspektiv på bedömningen bör därför antas. Vidare diskuteras även hur tillämpningen av bestämmelsen skulle kunna förbättras mot bakgrund av olika värderingsmetoder.</p> / <p>The subject matter of this Bachelor’s thesis is the special permit condition applying to water operations in accordance with chapter 11 section 6 of the Swedish Environmental Code. The article states that water operations may only be undertaken if the benefits, from the point of view of public and private interests, are greater than the costs and damages associated with them. The purpose of the regulation is to prevent water operations that are not socially efficient and to provide an additional protection for the environment, in excess of the general rules of consideration in the Code.</p><p>The purpose of this study is to look into how this particular article is applied in practice. This is done by analysing the legal usage as practiced by the court as well as by the applicants. The general rule is that the applicant has to show that the operation, for which the permit is being sought, is in compliance with the obligations associated with the activity. The study shows that it is very difficult to find guidance from case law on <em>how</em> an assessment of the social efficiency is to be carried out. Court practice indicates that circumstances such as whether the operation is in compliance with certain environmental objectives can be used to weight different aspects in the social efficiency assessment. However, the assessments carried out by the applicants are in general focused on the economic benefits for the applicant. This practice might entail a risk for environmental values not being properly valued when weighted against more tangible monetary benefits. A broader perspective is therefore called for. Potential improvements on the practice of the article are discussed against different valuation methods.</p>
246

Software Techniques for Distributed Shared Memory

Radovic, Zoran January 2005 (has links)
<p>In large multiprocessors, the access to shared memory is often nonuniform, and may vary as much as ten times for some distributed shared-memory architectures (DSMs). This dissertation identifies another important nonuniform property of DSM systems: <i>nonuniform communication architecture</i>, NUCA. High-end hardware-coherent machines built from large nodes, or from chip multiprocessors, are typical NUCA systems, since they have a lower penalty for reading recently written data from a neighbor's cache than from a remote cache. This dissertation identifies <i>node affinity</i> as an important property for scalable general-purpose locks. Several software-based hierarchical lock implementations exploiting NUCAs are presented and evaluated. NUCA-aware locks are shown to be almost twice as efficient for contended critical sections compared to traditional lock implementations.</p><p>The shared-memory “illusion”' provided by some large DSM systems may be implemented using either hardware, software or a combination thereof. A software-based implementation can enable cheap cluster hardware to be used, but typically suffers from poor and unpredictable performance characteristics.</p><p>This dissertation advocates a new software-hardware trade-off design point based on a new combination of techniques. The two low-level techniques, fine-grain deterministic coherence and synchronous protocol execution, as well as profile-guided protocol flexibility, are evaluated in isolation as well as in a combined setting using all-software implementations. Finally, a minimum of hardware trap support is suggested to further improve the performance of coherence protocols across cluster nodes. It is shown that all these techniques combined could result in a fairly stable performance on par with hardware-based coherence.</p>
247

The pricing of corporate bonds and determinants of financial structure

Thorsell, Håkan January 2008 (has links)
This thesis contain three chapters. Default Risk in Corporate Bond Pricing. This chapter provides a model for how the corporate bond default risk influences the systematic risk and an empirical analysis of the systematic and idiosyncratic parts of U.S. corporate bond returns during 2001-2005. The average corporate bond beta is low and positive (0.06). Investment grade bonds have negative betas (between - 0.01 and -0.13) and non-investment grade bonds have positive betas (between 0.11 and 1.48), but both groups have similar within groups systematic risks. When controls for interest rate and liquidity risks are introduced there are still remaining default probabilities, implying that the default risk is in part systematic and in part idiosyncratic.   Returns to Defaulted Corporate Bonds.   In the second chapter short term excess returns in a sample of 279 defaulted US corporate bonds are tested for using multiple regression analysis. There are robust excess returns after controlling for market and liquidity risk. The expected recovery rate during 2001-2006 is estimated to be, on average, four percentage points lower the first month after default than the present value of the recovery rate after nine months. Capital Structure Choices.   The trade-off and pecking order theories are tested using both established tests from the literature and new tests. The main contributions of this chapter are the new tests of financing of operating net assets (for the pecking order theory), the mean reversion tests (for the trade-off theory) and the test of mean reversion and trends. These tests allow for extended conclusions on the validity of the pecking order versus the tradeoff theory. / <p>Diss. Stockholm : Handelshögskolan, 2008 Sammanfattning jämte 3 uppsatser</p>
248

Samhällsnyttan av vattenverksamheter : Hur tillämpas samhällsnyttokravet i 11 kap. 6 § miljöbalken vid tillståndsprövning av vattenverksamheter?

Österlund, Ida January 2010 (has links)
Denna uppsats handlar om hur den särskilda tillåtlighetsregeln i 11 kap. 6 § miljöbalken tillämpas vid tillståndsprövning av vattenverksamheter. Av paragrafen följer att en vattenverksamhet endast får bedrivas om den samlade nyttan av verksamheten överväger de kostnader samt skador och olägenheter som verksamheten medför. Syftet med paragrafen är att hindra vattenverksamheter som inte är samhällsekonomiskt motiverade samt utgöra ett extra skydd för miljön utöver miljöbalkens generella miljökrav. Syftet med studien är undersöka hur denna paragraf tillämpas i praktiken – både i rättspraxis och i ansökningsförfarandet. Studien bygger i första hand på rättsvetenskaplig metod men ger även en mer allmän introduktion till samhällsekonomiska analysmetoder. Studien visar att det är mycket svårt att finna vägledning i praxis för hur en bedömning av samhällsnyttan bör gå till. Praxis visar dock att även faktorer som verksamhetens överensstämmelse med olika miljökvalitetsmål, art- och områdesskydd och estetiska värden kan få betydelse vid samhällsnyttobedömningen. Från sökandenas sida riktas generellt ett för stort fokus mot den privata eller företagsekonomiska nyttan av verksamheten. Sammantaget medför detta en risk för att miljövärden inte värderas på ett korrekt sätt när de vägs mot en mer konkret uttryckt monetär nytta. Ett bredare perspektiv på bedömningen bör därför antas. Vidare diskuteras även hur tillämpningen av bestämmelsen skulle kunna förbättras mot bakgrund av olika värderingsmetoder. / The subject matter of this Bachelor’s thesis is the special permit condition applying to water operations in accordance with chapter 11 section 6 of the Swedish Environmental Code. The article states that water operations may only be undertaken if the benefits, from the point of view of public and private interests, are greater than the costs and damages associated with them. The purpose of the regulation is to prevent water operations that are not socially efficient and to provide an additional protection for the environment, in excess of the general rules of consideration in the Code. The purpose of this study is to look into how this particular article is applied in practice. This is done by analysing the legal usage as practiced by the court as well as by the applicants. The general rule is that the applicant has to show that the operation, for which the permit is being sought, is in compliance with the obligations associated with the activity. The study shows that it is very difficult to find guidance from case law on how an assessment of the social efficiency is to be carried out. Court practice indicates that circumstances such as whether the operation is in compliance with certain environmental objectives can be used to weight different aspects in the social efficiency assessment. However, the assessments carried out by the applicants are in general focused on the economic benefits for the applicant. This practice might entail a risk for environmental values not being properly valued when weighted against more tangible monetary benefits. A broader perspective is therefore called for. Potential improvements on the practice of the article are discussed against different valuation methods.
249

Hybrid Particle Swarm Optimization Algorithm For Obtaining Pareto Front Of Discrete Time-cost Trade-off Problem

Aminbakhsh, Saman 01 January 2013 (has links) (PDF)
In pursuance of decreasing costs, both the client and the contractor would strive to speed up the construction project. However, accelerating the project schedule will impose additional cost and might be profitable up to a certain limit. Paramount for construction management, analyses of this trade-off between duration and cost is hailed as the time-cost trade-off (TCT) optimization. Inadequacies of existing commercial software packages for such analyses tied with eminence of discretization, motivated development of different paradigms of particle swarm optimizers (PSO) for three extensions of discrete TCT problems (DTCTPs). A sole-PSO algorithm for concomitant minimization of time and cost is proposed which involves minimal adjustments to shift focus to the completion deadline problem. A hybrid model is also developed to unravel the time-cost curve extension of DCTCPs. Engaging novel principles for evaluation of cost-slopes, and pbest/gbest positions, the hybrid SAM-PSO model combines complementary strengths of overhauled versions of the Siemens Approximation Method (SAM) and the PSO algorithm. Effectiveness and efficiency of the proposed algorithms are validated employing instances derived from the literature. Throughout computational experiments, mixed integer programming technique is implemented to introduce the optimal non-dominated fronts of two specific benchmark problems for the very first time in the literature. Another chief contribution of this thesis can be depicted as potency of SAM-PSO model in locating the entire Pareto fronts of the practiced instances, within acceptable time-frames with reasonable deviations from the optima. Possible further improvements and applications of SAM-PSO model are suggested in the conclusion.
250

Optimal kapitalstruktur : En undersökning tillämpad på skandinaviska och tyska företag

Wallberg, Martin, La, David January 2011 (has links)
This paper describes and develops a trade off model of optimal capital structure by Bradley et al. (1984). The model is then tested to examine how changes in corporate tax rates affect the optimal capital structure of firms. Based on theoretical implications of the model, four hypotheses are derived stating that firms’ optimal debt-to-value ratio is (1) negatively related to financial distress costs, (2) negatively related to non-debt tax shields, (3) negatively related to firm volatility and (4) positively related to the corporate tax rate. Based on the results of two regression models applied on 753 Scandinavian and German firms, we find empirical support for hypothesis 1 and 3 while we find no empirical support for hypothesis 2 and 4. These results can be explained by problematic empirical proxies and in the light of the pecking-order theory.

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