• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 43
  • 39
  • 5
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 109
  • 35
  • 30
  • 30
  • 26
  • 25
  • 21
  • 19
  • 16
  • 15
  • 14
  • 13
  • 12
  • 11
  • 10
  • 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.
81

Análise de sistemas para o resfriamento de leite em fazendas leiteiras com o uso do biogás gerado em projetos MDL. / Analysis of systems for cooling milk on dairy farms using the biogas generated in CDM projects.

Giancarlo Obando Diaz 04 October 2006 (has links)
O setor leiteiro brasileiro caracterizado por um grande número de produtores, que, porém, apresentam baixos índices de produtividade e qualidade. Em relação à qualidade, necessária a implantação de sistemas de resfriamento e conservação do leite na fazenda. Contudo, o investimento nesse tipo de equipamento muitas vezes inviabilizado pelos baixos volumes de produção, bem como pela não disponibilidade de energia elétrica na área rural. Nesse contexto, o objetivo deste trabalho determinar qual a configuração ótima para o sistema de resfriamento de leite de uma fazenda leiteira de pequeno ou médio porte, que será inserida em um projeto de digestão anaeróbica no âmbito do Mecanismo de Desenvolvimento Limpo do Protocolo de Kyoto, implementado por uma empresa interessada na comercialização dos créditos de carbono. Como esse projeto disponibilizará ao produtor um insumo energético renovável e de baixo custo (o biogás resultante da digestão), a determinação da configuração ótima considerou dois possíveis cenários: o de um produtor que ainda não conta com um sistema para resfriamento de leite in loco, e o de um produtor que já conta com esse sistema, acionado por energia elétrica, e estuda a viabilidade de investir na geração de energia usando o biogás na substituição da energia elétrica adquirida da rede pública de distribuição. Foram analisados os aspectos técnicos ligados ao dimensionamento das configurações, avaliação do consumo dos diferentes insumos energéticos e quantificação dos créditos de carbono, bem como os aspectos econômicos envolvidos (investimentos, custos operacionais e de manutenção, recursos advindos da comercialização dos créditos de carbono). Foi também avaliado o impacto da introdução do sistema de refrigeração nos custos de produção do litro do leite e nos valores recebidos pelo produtor na venda do produto. A análise mostra que a utilização de um gerador acionado por um motor de combustão interna de ciclo Otto movido a biogás a melhor configuração para um novo sistema. Para sistemas já existentes, a substituição da compra de energia elétrica por geração in loco também uma alternativa interessante, ainda que apresente um tempo de retorno de investimento relativamente elevado para os padrões brasileiros. / The Brazilian dairy sector is characterized by a great number of producers, presenting low productivity and product quality. Concerning to quality, it is necessary the implantation of cooling systems for milk and conservation on farm. However, a low milk production level and the electric power availability on rural areas sometimes make unfeasible investments on these types of coolers. In this context, the goal of this work is to determine the best configuration of a milk cooling system for small and medium-scale dairy farms to be included in an anaerobic digestion project based on the Clean Development Mechanism of the Protocol of Kyoto. Such project is to be implemented by a company interested in commercialize the carbon credits generated. Once the project will provide to the farmer a renewable and low-cost energy resource (the biogas resulting of the anaerobic digestion), it was considered two possible sceneries: a producer that does not count on a cooling system, and a producer that may want to replace purchased electricity by a generation system based on a biogas-fueled engine to power an already existing system for milk cooling. The work analyzed several technical aspects connected to cooling system sizing, feasible configurations for supplying the cooling demand, evaluation of the consumption of the different energy inputs (electricity and biogas) of considered configurations. It was evaluated the carbon credits generation, as well as the involved economical aspects (investments, operational and maintenance costs, earnings from commercialization of carbon credits). It was also evaluated the impact of introducing the cooling system on milk production costs and values received by the producer. The analysis shows that a biogas-fueled Otto-engine electrical generator is the best configuration for a new system, and that the replacement of the electric power purchase for generation on farm is also an interesting alternative, although its payback time is relatively high for Brazilian standards.
82

O USO DE BIODIGESTORES EM PEQUENAS E MÉDIAS PROPRIEDADES RURAIS COM ÊNFASE NA AGREGAÇÃO DE VALOR: UM ESTUDO DE CASO DA REGIÃO NOROESTE DO RIO GRANDE DO SUL / THE USE OF BIO-DIGESTERS IN SMALL AND MEDIUM RURAL PROPERTIES WITH EMPHASIS ON VALUE ADDING: A CASE STUDY FROM NORTHWESTERN REGION OF RIO GRANDE DO SUL STATE

Barichello, Rodrigo 27 August 2010 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / From the duration of the Kyoto Protocol, there has been a renewed interest in technology of bio-digesters. As they allow a reduction in the emission of greenhouse gases compared to other waste treatment methods, their deployment can permit the marketing of carbon credits, resulting in money. The present study aims to analyze the process of dissemination of this technology in Santa Rosa, situated in the northwestern of Rio Grande do Sul state, especially powered by private companies. The profile properties that have these installed equipment, in addition to an examination of possible difficulties encountered by land owners, towards the deployment and use of this technology, with the contribution of biodigesters, on the energy issue and mitigation of environmental pollution in these areas. Through a revision of the existing literature and application of questionnaires some information about the installation of bio-digesters were taken, noticing if they contribute as alternatives in order to add value to the breeding properties and as viable alternative to the solution of environmental problems involved in the process. This study revealed that 33.33% of installed equipment is disabled. The work also presents a case study of isolated electric power generation using biogas as a fuel in an internal combustion engine of Otto cycle, in conjunction with CDM project, installed in a midsize property of pig breeding. The generation plant consists of a stationary Otto cycle engine, adapted to operate with biogas, coupled to an electric generator nominal 30 kVA three-phase. Through the study of the economic and financial feasibility, it was concluded that the application for generating electricity is viable and the overall efficiency of the system is satisfactory. Through another point of view, it presents a second case study, on the insertion of a property in a project of clean development mechanism (CDM) in pig production. / A partir da vigência do Protocolo de Kyoto, houve um interesse renovado pela tecnologia dos biodigestores. Como eles permitem uma redução na emissão de gases do efeito estufa, em relação a outros métodos de tratamento de dejetos, a sua implantação pode permitir a comercialização de créditos de carbono, resultando em valores monetários. O presente trabalho tem como objetivo analisar o processo de disseminação desta tecnologia na microrregião de Santa Rosa, situada na mesorregião do Noroeste Riograndense, impulsionada, especialmente, por empresas privadas. Estudou-se o perfil das propriedades que possuem estes equipamentos instalados, além de uma análise das possíveis dificuldades encontradas pelos proprietários rurais, no sentido de implantação e utilização dessa tecnologia, verificando-se a contribuição dos biodigestores, referente à questão energética e minimização da poluição do meio ambiente nessas áreas. Através da revisão da literatura existente e aplicação de questionários, foram levantadas diversas informações acerca da instalação de biodigestores, observando se contribuem como alternativa de agregação de valor às propriedades criadoras e como alternativa viável para a solução dos problemas ambientais envolvidos no processo. O presente estudo revelou que 33,33% dos equipamentos instalados encontram-se desativados. O trabalho também apresenta um caso prático de geração de energia elétrica isolada, utilizando biogás como combustível em um motor à combustão interna do Ciclo Otto, em conjunto com projeto de MDL, instalado em uma propriedade de médio porte, para criação de suínos. A planta de geração consiste de um motor estacionário de Ciclo Otto, adaptado para operar com biogás, acoplado a um gerador elétrico trifásico de 30 kVA nominal. Através do estudo da análise de viabilidade econômico-financeira, concluiu-se que a aplicação para a geração de energia elétrica é viável e a eficiência global do sistema é satisfatória. Numa outra visão, apresenta-se um segundo caso prático, na inserção de uma propriedade em um projeto de mecanismo de desenvolvimento Limpo (MDL) na suinocultura.
83

UNIFIED SECONDARY AND TERTIARY CREEP MODELING OF ADDITIVELY MANUFACTURED NICKEL-BASED SUPERALLOYS

Harshal Ghanshy Dhamade (11002041) 05 August 2021 (has links)
<div>Additively manufactured (AM) metals have been increasingly fabricated for structural applications. However, a major hurdle preventing their extensive application is lack of understanding of their mechanical properties. To address this issue, the objective of this research is to develop a computational model to simulate the creep behavior of nickel alloy 718 manufactured using the laser powder bed fusion (L-PBF) additive manufacturing process. A finite element (FE) model with a subroutine is created for simulating the creep mechanism for 3D printed nickel alloy 718 components.</div><div><br></div><div>A continuum damage mechanics (CDM) approach is employed by implementing a user defined subroutine formulated to accurately capture the creep mechanisms. Using a calibration code, the material constants are determined. The secondary creep and damage constants are derived using the parameter fitting on the experimental data found in literature. The developed FE model is capable to predict the creep deformation, damage evolution, and creep-rupture life. Creep damage and rupture is simulated as defined by the CDM theory.</div><div>The predicted results from the CDM model compare well with experimental data, which are collected from literature for L-PBF manufactured nickel alloy 718 of creep deformation and creep rupture, at different levels of temperature and stress. </div><div><br></div><div>Using the multi-regime Liu-Murakami (L-M) and Kachanov-Rabotnov (K-R) isotropic creep damage formulation, creep deformation and rupture tests of both the secondary and tertiary creep behaviors are modeled.</div><div>A single element FE model is used to validate the model constants. The model shows good agreement with the traditionally wrought manufactured 316 stainless steel and nickel alloy 718 experimental data collected from the literature. Moreover, a full-scale axisymmetric FE model is used to simulate the creep test and the capacity of the model to predict necking, creep damage, and creep-rupture life for L-PBF manufactured nickel alloy 718. The model predictions are then compared to the experimental creep data, with satisfactory agreement.</div><div><br></div><div>In summary, the model developed in this work can reliably predict the creep behavior for 3D printed metals under uniaxial tensile and high temperature conditions.</div>
84

Road transportation impact on Ghana's future energy and environment

Faah, George 24 July 2009 (has links)
This research work explored the environmental and socio-economic benefits derived, if some proportion of daily passenger trips made using private cars in Ghana could be shifted to the use of public transport. The research applied the computer software COPERT III in estimating road transport Greenhouse gas (GHG) emissions and fuel consumption in Ghana for the base year 2005 and forecast years 2010 and 2020. The research reveals that if no major change occur in policies or economic determinants in meeting road transport and energy in Ghana, then the 2005 total emissions value is expected to rise by 36% in 2010 and over double in 2020 i.e. from 4.6 to 6.25 in 2010 and to 9.77 Mt CO2e in 2020. However, if just 10% of daily passenger trips using private cars can be shifted towards the use of public transport, then the end results in reduction in emissions could earn Ghana about $USD 6.6million/year under the Kyoto Protocol CDM initiative. The research also demonstrated that with a further 10% daily passenger trip shift, the outcome could be more promising, increasing to $USD 13million/year.
85

Impacts on sustainable development of two CDM projects : A comparison using AHP method

Qirui, Yang January 2010 (has links)
Nowadays the mitigation of climate change and the reduction of greenhouse gases are one of the priorities in the international affairs. Clean Development Mechanism (CDM) is one of the products generated according to this request. For China, CDM brings advanced technologies in terms of energy saving and emission reduction, and driving forces for sustainable development, hereby the development of CDM projects is in full swing in China so far. However, it is not easy to decide which type of CDM projects is suitable for a certain city or region, which project contributes more to sustainable development compared with others, when it comes to several alternatives. In this case, decision-makers require a tool to help make a rational decision. As one of the approaches of assisting in making decisions, the Analytic Hierarchy Process (AHP) is able to provide assistance for decision-makers to compare the contribution of discrepant CDM projects to sustainable development. Moreover, a case study is taken between two typical CDM projects: HFC23 decomposition project and small-scale hydropower project, so as to check if AHP is useable. The result of the case study indicates that HFC23 decomposition project contributes more than small-scale hydropower plant project to sustainable development, which is not in line with China’s CDM development trend for these two projects (NCCCC, 2005), due to the different represented interests of the study group and the real decision-makers. Nevertheless, the result is rational and valid since there is nothing wrong with the AHP method and its application. In addition, in order to improve the effect of assisting in decision making, AHP was tried to be improved in three respects: impairing subjectiveness, avoiding rank reversal and improving accuracy. Even though for AHP itself, DEA/AHP approach could successfully eliminate the subjectiveness, however when it comes to this very case: compare CDM projects in terms of contribution to sustainable development in China, it cannot play an effective role. Moreover, PCA/AHP method cannot eliminate the subjectiveness at the root either. The framework method provides a possibility in theory to increase objectiveness. Two expects provided a feasible way to avoid rank reversal in their article, and the two pathways of improving results accuracy mentioned in this thesis are considered inappropriate in this case. On the other side, concerning AHP application, how to covert realistic issues to AHP structure, how to get desirable initial information, and how to avoid limitation generated by considerable criteria, sub-criteria and alternatives are considered as the difficulties which should be paid attention. In future, AHP could be applied frequently and effectively concerning providing assistance in making decisions in China, if the stakeholders as many as possible are involved in decision-making process.
86

Design, Characterization And Compact Modeling Of Novel Silicon Controlled Rectifier (scr)-based Devices For Electrostatic Discha

Lou, Lifang 01 January 2008 (has links)
Electrostatic Discharge (ESD), an event of a sudden transfer of electrons between two bodies at different potentials, happens commonly throughout nature. When such even occurs on integrated circuits (ICs), ICs will be damaged and failures result. As the evolution of semiconductor technologies, increasing usage of automated equipments and the emerging of more and more complex circuit applications, ICs are more sensitive to ESD strikes. Main ESD events occurring in semiconductor industry have been standardized as human body model (HBM), machine model (MM), charged device model (CDM) and international electrotechnical commission model (IEC) for control, monitor and test. In additional to the environmental control of ESD events during manufacturing, shipping and assembly, incorporating on-chip ESD protection circuits inside ICs is another effective solution to reduce the ESD-induced damage. This dissertation presents design, characterization, integration and compact modeling of novel silicon controlled rectifier (SCR)-based devices for on-chip ESD protection. The SCR-based device with a snapback characteristic has long been used to form a VSS-based protection scheme for on-chip ESD protection over a broad rang of technologies because of its low on-resistance, high failure current and the best area efficiency. The ESD design window of the snapback device is defined by the maximum power supply voltage as the low edge and the minimum internal circuitry breakdown voltage as the high edge. The downscaling of semiconductor technology keeps on squeezing the design window of on-chip ESD protection. For the submicron process and below, the turn-on voltage and sustain voltage of ESD protection cell should be lower than 10 V and higher than 5 V, respectively, to avoid core circuit damages and latch-up issue. This presents a big challenge to device/circuit engineers. Meanwhile, the high voltage technologies push the design window to another tough range whose sustain voltage, 45 V for instance, is hard for most snapback ESD devices to reach. Based on the in-depth elaborating on the principle of SCR-based devices, this dissertation first presents a novel unassisted, low trigger- and high holding-voltage SCR (uSCR) which can fit into the aforesaid ESD design window without involving any extra assistant circuitry to realize an area-efficient on-chip ESD protection for low voltage applications. The on-chip integration case is studied to verify the protection effectiveness of the design. Subsequently, this dissertation illustrate the development of a new high holding current SCR (HHC-SCR) device for high voltage ESD protection with increasing the sustain current, not the sustain voltage, of the SCR device to the latchup-immune level to avoid sacrificing the ESD protection robustness of the device. The ESD protection cells have been designed either by using technology computer aided design (TCAD) tools or through trial-and-error iterations, which is cost- or time-consuming or both. Also, the interaction of ESD protection cells and core circuits need to be identified and minimized at pre-silicon stage. It is highly desired to design and evaluate the ESD protection cell using simulation program with integrated circuit emphasis (SPICE)-like circuit simulation by employing compact models in circuit simulators. And the compact model also need to predict the response of ESD protection cells to very fast transient ESD events such as CDM event since it is a major ESD failure mode. The compact model for SCR-based device is not widely available. This dissertation develops a macromodeling approach to build a comprehensive SCR compact model for CDM ESD simulation of complete I/O circuit. This modeling approach offers simplicity, wide availability and compatibility with most commercial simulators by taking advantage of using the advanced BJT model, Vertical Bipolar Inter-Company (VBIC) model. SPICE Gummel-Poon (SGP) model has served the ICs industry well for over 20 years while it is not sufficiently accurate when using SGP model to build a compact model for ESD protection SCR. This dissertation seeks to compare the difference of SCR compact model built by using VBIC and conventional SGP in order to point out the important features of VBIC model for building an accurate and easy-CAD implement SCR model and explain why from device physics and model theory perspectives.
87

Multi-Scale Physics Based Modeling of Tire Rolling Resistance Considering Aging

Alkandari, Waleed M. M. A. 22 March 2022 (has links)
Every moment of every day, at least hundreds of thousands of tires roll across a surface throughout the world. Tires are indisputably important in our daily life. The tire's primary component is rubber, which consumes energy when it rotates on a substrate due to the viscoelastic material's internal friction: a phenomenon referred to as rolling resistance. The interaction between the tire and the road surface is one of the most intricate and crucial phenomena in an automobile, because it is responsible for creating forces, moments, and deformation in the tire. Additionally, the road's roughness interacts with the tire and contributes significantly to its performance. This dissertation aims to develop a comprehensive physics-based model for predicting the rolling resistance of a viscoelastic material due to dynamic deformations caused by tire rotation using an analytical approach. The model was developed by proposing a Gaussian wave function propagating across a tire circumference's viscoelastic medium. The wave function was selected to describe the displacement field produced by tire-road interaction. Additionally, by adopting a multi-scale modeling technique, the model was upgraded to estimate rolling resistance while taking into account surface roughness at all length scales, from macroscopic to microscopic. Additionally, another mathematical model was developed using the Fourier series approach to evaluate the steady-state stress response and energy dissipation for any harmonic and non-harmonic periodic strain signals. Additionally, the dissertation strove to build a continuum damage mathematical model using a combined testing/modeling methodology to predict the aging of Styrene-Butadiene Rubber (SBR) after continuous exposure to the atmosphere. The obtained model was developed through the implementation of optimization techniques while formulating a mathematical model, which was then combined with a physics-based model to predict rolling resistance while taking into account rubber aging. Calibration of hyperelastic and viscoelastic material models with testing data was performed using an optimization technique that yielded sufficient results. The results of all mathematical models obtained in this dissertation are reported subsequently. The stress response of a viscoelastic material under harmonic and non-harmonic strain input yielded good agreement with the FEA model obtained using ABAQUS. The rolling resistance behavior under various operating conditions, including texture and aging effects, was reported, and the results aligned with the experimental results found in the literature. / Doctor of Philosophy / Every moment of every day, hundreds of thousands of automobile tires roll across a surface somewhere in the world. A tire is an undeniably important part of everyday life. Rubber is the tire's main component, and when it rotates on a surface, it loses energy, resulting in a force that resists motion, known as rolling resistance force. The contact between the tire and the road is one of the most complicated and important phenomena that happens in an automobile because it is responsible for the vehicle's dynamic performance in areas such as acceleration, stopping distance, and stability. Another factor that affects tire and car performance and should be taken into account is the road's roughness. This dissertation used an analytical method to come up with an accurate physics-based model for predicting the rolling resistance force of a viscoelastic material caused by tire rotation. The model was developed by assuming a Gaussian wave function would move across the tire circumference. Additionally, using a multi-scale modeling technique, the model was improved so that it could calculate the value of rolling resistance force considering surface roughness in all lengths of scale. This project also developed an additional mathematical model using the Fourier series method to determine how the stress response and energy dissipation would behave for any harmonic and nonharmonic periodic strain signals. Additionally, the dissertation presents the developing of a continuum damage mathematical model that could predict the material property of styrene-butadiene rubber (SBR) after being exposed to the air for a long time (i.e., aged). The model was developed based on experimental data and optimization techniques. This model was then combined with a physics-based model to predict rolling resistance force while taking aging into account. The material models were defined using an optimization method that yielded good results. The stress response of a viscoelastic material when it was subjected to harmonic and non-harmonic strain was in good agreement with the Finite Element Analysis (FEA) model made with ABAQUS. Rolling resistance behavior was observed, and the results were consistent with those found in the literature.
88

O Protocolo de Kyoto e os países em desenvolvimento: uma avaliação da utilização do Mecanismo de Desenvolvimento Limpo / Kyoto Protocol and developing countries: analyses of Clean Development Mechanism adoption

Godoy, Sara Gurfinkel Marques de 14 February 2011 (has links)
Com base na Nova Economia Institucional, o foco desta pesquisa foi o de identificar os custos de transação existentes nos projetos de MDL (Mecanismo de Desenvolvimento Limpo) e investigar se eles são barreiras para o desenvolvimento do projeto, e se podem afetar a eficiência de projetos já implantados. Mais especificamente, foram analisadas as variáveis que afetam as diferenças entre as reduções de emissões estimadas nos projetos de MDL e as reduções realmente verificadas (Sucesso de Redução - SR), depois do projeto implantado e monitorado. A fim de cumprir esse objetivo, esta pesquisa contou com levantamento de dados secundários relativos aos projetos de MDL realizados em todo o mundo, e dados primários relativos aos projetos brasileiros de MDL. A análise das informações mostrou que os países mais relevantes em número de projetos são Índia, China, Brasil, mas este ranking se altera dependendo da variável analisada (por exemplo, volume de emissão reduzida ou estimada). Os setores mais relevantes em volume de redução são de HFC, N2O, mas este perfil se altera quando analisado o número de projetos, ficando em primeiro lugar biomassa, hidroelétrica e energia eólica. Em relação ao SR, a maior parte dos projetos não apresenta eficiência satisfatória. No entanto, em volume de reduções a maior parte dos projetos cumpre mais que 91% de SR. Os setores mundiais mais eficientes são N2O e HFC (Brasil N2O e troca de energia fóssil), e os setores de resíduos sólidos e agricultura (Brasil, agricultura e resíduos sólidos) são os menos eficientes. Finalmente, esta pesquisa conclui que custos de transação afetam o sucesso da redução de MDL, e os mais importantes são os custos ex-ante, resultantes de problemas de falhas de informação (como, por exemplo, problemas com as organizações que intermedeiam o processo dos MDLs) e problemas de mensuração (problemas relacionados com metodologias dos MDLs). / Based on the New Institutional Economics, the focus of this research was to identify transaction costs in CDM projects (Clean Development Mechanism) and investigate if they can affect project efficiency, and also if they create project development barriers. More specifically, this research analyzed the variables that could affect the differences between CDM estimated emission reduction projects and actual reductions obtained (Reduction Success - RS) after the project has been implemented and monitored. To fulfill this goal, this research included a secondary global CDM projects data survey, and primary data survey related to Brazilian CDM projects. Data analysis showed that the most important countries in terms of number of projects are India, China, Brazil, but depending on the variable analyzed (for instance, emission reduction volume) this ranking could change. The most relevant sectors in emission reduction volume were HFCs, N2O, but this would change when we analyze number of projects, where biomass would come first, followed by hydroelectric and wind energy. When considering RS, most projects do not show satisfactory performance. However, in terms of emission reductions amount, most of the projects achieve more than 91% RS. The most efficient sectors in the world are HFC and N2O (in Brazil, N2O and fossil fuel), and the least efficient sectors are solid waste and agriculture (in Brazil, agriculture and solid waste). Finally, this research concludes that transaction costs affect the success of CDM reductions, and the most relevant are ex-ante costs, resulting from information problem gaps (these problems relate to parties involved in the CDM process) and measurement problems (CDM methodologies).
89

Principais aspectos do ciclo biogeoquímico do elemento carbono e seu contexto na atualidade / Main aspects of the global biogeochemical carbon cycle and context at the present time

Tonello, Victor Manoel Marques 04 May 2007 (has links)
O presente trabalho consistiu na produção de uma síntese sobre os principais aspectos do ciclo biogeoquímico do carbono, envolvendo aspectos recentes do efeito estufa na atmosfera, sendo também contextualizadas as políticas públicas e seus mecanismos sócio-econômicos; inserida num contexto atual, das mudanças climáticas, intimamente relacionadas à Convenção-Quadro das Nações Unidas sobre Mudança do Clima, Protocolo de Kyoto e Mecanismos de Desenvolvimento Limpo. Os ecossistemas terrestres prestam enorme contribuição de serviços ambientais ao homem na forma de oferta de água, alimentos e insumos gerais. Estes ganhos são sustentáveis na medida em que haja um equilíbrio estável entre a entrada e saída de certas variáveis. Ainda não se entende satisfatoriamente a funcionalidade dos ecossistemas naturais e sua plena interação com o clima, nas escalas local, regional e global; portanto, é uma responsabilidade social antecipar o entendimento dessa relação, antes que tudo se transforme. Não se sabe ao certo todas as conseqüências do aumento excessivo na temperatura terrestre, mas são esperadas alterações profundas em diversos ecossistemas, por exemplo: descongelamento das calotas polares e o conseqüente alagamento de regiões costeiras, alterações de intensidade e freqüência de chuvas, e alteração do metabolismo vegetal. São também previstas conseqüências na mudança das zonas climáticas e agrícolas e o desaparecimento de espécies sensíveis a esta mudança de temperatura. Procurando atingir o objetivo final da Convenção-Quadro das Nações Unidas sobre Mudança do Clima, em Kyoto &#150; Japão, foi proposto o Protocolo de Kyoto, no sentido de possibilitar alcançar a estabilização das concentrações de gases de efeito estufa na atmosfera, num nível que não interfira perigosamente no sistema climático. Estabelece metas e prazos para controlar num primeiro esforço os principais gases de efeito estufa. Foram estabelecidos três mecanismos para auxiliar os países desenvolvidos no cumprimento de suas metas de redução ou limitação de emissões de gases de efeito estufa. Um desses mecanismos foi definido como Mecanismo de Desenvolvimento Limpo - MDL, sua implementação interessa particularmente aos países em desenvolvimento, pois permitirá a transferência de recursos e tecnologias para a redução de emissões. Neste contexto, exigi-se da classe cientifica respostas mais precisas e rápidas do entendimento de todos os processos envolvidos. O acompanhamento de projetos é importante, gerando informações para análises técnicas, científicas, sociais, ambientais e econômicas, que serão demandadas nas futuras negociações relativas à mitigação da mudança do clima. / The present work intends to present a synthesis of the information which is distributed in several areas. It approaches the main aspects of the global carbon cycle, including the recent greenhouse effect in the atmosphere, also including the political argumentation and the socioeconomic mechanisms associated. The work also brings a critical revision of the framework related to the United Nations Framework Convention on the Climate Change, the Kyoto Protocol and the Clean Development Mechanism. The terrestrial ecosystems provide enormous contribution of environmental services to the human beings in terms of water, foods, and general inputs supplies. The sustainability of this provision relies on the maintenance of the input/output equity of matter and energy throughout time. There is still no clear understanding of the natural ecosystems functioning and their interactions with climate in a broad perspective, from local to regional and global scales. Therefore it is a social responsibility to anticipate the understanding of this relation, before everything changes. The effects on the ecosystems of the temperature increase in the Earth surface are not fully understood, but strong changes are expected and some are already being measured in several ecosystems, for instance: mountain glaciers and the ice cap in the North Pole are declining, with foreseeable consequences of increasing sea level and flooding of coastal areas; changes in the cycle and intensity of rain events; changes in plant metabolism and distribution of agricultural species, interfering in food production and safety. The Kyoto Protocol was proposed aiming to achieve the objectives of the United Nations Framework Convention on the Climate Change, building the legal and political background for the Nations to lessen and stabilize the concentrations of greenhouse gases in the atmosphere. The Protocol established mechanisms for reduction and mitigation of greenhouse gases emissions including developed and developing countries. In terms of economical and technological gains, the Clean Development Mechanism &#150; CDM, was one of the proposed mechanism of the Kyoto Protocol, which is particularly interesting to the developing countries. This mechanism allows resources and technologies transference for the reduction of GHG emissions in developing countries. In this context, the scientific community is an important component to bring more precise and fast answers to the understanding of all of the processes related to the actual influence of the Human kind in the planet.
90

Mensuração contábil dos créditos de carbono no Brasil, China e Índia / Accounting measurement of carbon credits in Brazil, China and India.

Souza, Valdiva Rossato de 09 April 2015 (has links)
A presente pesquisa teve como objetivo identificar a incidência de impactos econômicos no patrimônio das empresas brasileiras, chinesas e indianas provocados pela mensuração e reconhecimento ao valor justo dos ativos provenientes de Reduções Certificadas de Emissões (RCEs) geradas em seus processos produtivos, com a implementação de projetos de Mecanismos de Desenvolvimento Limpo (MDLs), durante o período de 2005 a 2012. Consideraram-se os estímulos oferecidos com as diretrizes do Protocolo de Quioto e a representatividade de implementações de projetos de MDLs da China, da Índia e do Brasil, para apresentar, com base em pesquisas descritiva, analítica e quantitativa, uma proposta de mensuração contábil das RCEs, capaz de evidenciar os fluxos futuros de seus benefícios econômicos, partindo-se do modelo de Ratnatunga, Jones e Balachandran (2011). Para tanto, trabalhou-se com a hipótese de que as RCEs não estão sendo mensuradas ao valor justo enquanto ativo, fato este que tem inviabilizado a evidenciação dos efeitos patrimoniais dos fluxos de caixa futuros. Descreveu-se a teoria da mensuração contábil como suporte ao valor justo; discutiu-se os padrões contábeis existentes nos países mencionados e as principais características que envolvem as adoções das International Financial Reporting Standards (IFRSs) em cada um deles, com foco na mensuração contábil ao valor justo, aceita pelo International Accounting Standards Board (IASB). As orientações contábeis internacionais emanadas para contabilização das RCEs foram apresentadas para analisar o cenário atual de desenvolvimento do tratamento contábil atribuível ao ativo em questão. Assim, detectou-se que a mensuração das RCEs tem sido pouco discutida. Sugeriu-se que com a efetivação do registro dos projetos de MDLs junto ao Conselho Executivo da United Nations Framework Conference on Climate Change (UNFCCC), as RCEs passem a ser reconhecidas ao valor justo e como ativos intangíveis desenvolvidos internamente por parte das entidades hospedeiras dos projetos de MDLs, em contrapartida ao Patrimônio Líquido (PL), até o momento de sua realização. A base para mensuração do valor justo proposta foi os valores de mercados ativos. Em função do lapso temporal que estarão gerando benefícios econômicos, realizou-se projeção financeira sobre as quantidades potenciais constantes estimadas de Reduções Esperadas (REs) para todo o período de desenvolvimento das atividades dos projetos, utilizando-se uma taxa Euribor para desconto de seus valores futuros ao presente. De posse dessas variáveis, os valores justos das REs de 31 projetos de MDLs brasileiros, 379 chineses e 318 indianos, foram projetados sobre o valor do PL de 15 empresas brasileiras, 56 chinesas e 183 indianas componentes da amostra da pesquisa, com apoio do teste estatístico não-paramétrico Wilcoxon. Os resultados da pesquisa forneceram indícios de que a mensuração ao valor justo das RCEs, e seu reconhecimento enquanto ativo intangível, poderia ter representado um impacto positivo no grupo de contas patrimoniais das empresas participantes da pesquisa. Assim, a aplicabilidade empírica da mensuração ao valor justo das RCEs embasada em discussões teóricas já existentes, possibilitou a realização de avaliações desse ativo enquanto item patrimonial capaz de gerar efeitos econômicos positivos no patrimônio das entidades localizadas em países em desenvolvimento, durante a primeira fase do Protocolo de Quioto. / This research aimed to identify the incidence of economic impacts on equity of Brazilian, Chinese and Indian companies caused by the measurement and recognition at fair value of the assets from Certified Emission Reductions (CER) generated in their production processes, with the implementation of Clean Development Mechanisms (CDM) projects from 2005 to 2012. It was considered the incentives offered to the guidelines of the Kyoto Protocol and the representativeness of CDM projects implementation of China, India and Brazil, to present, based on descriptive, analytical and quantitative research, a proposal for accounting measurement of CER, able to enhance the future flows of its economic benefits, based on the Ratnatunga, Jones and Balachandran (2011) model. Therefore, it worked with the hypothesis that the CER are not measured at fair value as assets, a fact that has made impossible the disclosure of balance sheet effects of future cash flows. It was described the theory of accounting measurement as support at fair value. It was discussed existing accounting standards in those countries and the main characteristics that involve the adoption of International Financial Reporting Standards (IFRS) in each of them, focusing on accounting measurement at fair value, accepted by the International Accounting Standards Board (IASB). The international accounting guidelines issued for accounting of CER were presented to analyze the current scenario of development of the accounting treatment attributable to the asset. Thus, it was found that the measurement of CERs has been little discussed. It was suggested that with the realization of the registration of CDM projects with the Executive Council of the United Nations Framework Conference on Climate Change (UNFCCC), CER start to be recognized at fair value as intangible assets developed internally by the host entities of CDM projects, in contrast to Equity, until the moment of its realization. The basis for measuring fair value proposition was the values of active markets. Depending on the time gap that will generate economic benefits, a financial projection on potential constants estimated quantities of Expected Reductions (ER) for the whole period of development of project activities was carried out, using a Euribor rate to discount their future values to the present. With these variables, the fair values of ER from 31 Brazilian CDM projects, 379 Chinese and 318 Indians were simulated on the value of equity of 15 Brazilian companies, 56 Chinese and 183 Indian components of the survey sample, with test support statistical non-parametric Wilcoxon. The survey results provided evidence that the fair value measurement of CER, and its recognition as an intangible asset, could have represented a positive impact on the group balance sheet accounts of the participating research companies. Thereby, the empirical applicability of the fair value measurement of CER grounded in existing theoretical discussions, made it possible to carry out assessments of this asset as a heritage item capable of generating positive economic effects on equity of entities located in developing countries, during the first stage of the Kyoto Protocol.

Page generated in 0.0476 seconds