O crescente interesse por fontes alternativas de energia, sobretudo por aquelas que consigam mitigar as emissões de gases causadores do efeito estufa (GEE), tem feito com que a produção de biocombustíveis aumentasse significativamente. Neste cenário o etanol produzido a partir da cana de açúcar, tem apresentado vantagem em relação a outros biocombustíveis, uma vez que a energia produzida é relativamente alta quando comparada com a consumida em seu processo produtivo. Neste contexto, as exportações brasileiras, principalmente as da região Centro-Sul, tentam suprir as necessidades mundiais através da produção excedente de etanol no país. No entanto, há gargalos logísticos na distribuição deste produto e isso tem feito que o transporte rodoviário fosse excessivamente utilizado na movimentação do etanol desde a usina até o porto. Diante destes aspectos, esta pesquisa busca investigar alternativas intermodais para a movimentação do etanol destinado à exportação, considerando a viabilidade econômica e energética empregada na cadeia logística deste biocombustível. Para isso, foram gerados quatro cenários utilizando os modos rodoviário, ferroviário, dutoviário e hidroviário. Através dos resultados obtidos, o cenário rodo-ferroviário apresentou uma estimativa de custo da ordem de R$ 654 milhões, valor da mesma ordem de grandeza do cenário rodoviário de referência, que foi de R$ 653 milhões. Já os cenários rodo-dutoviário e rodo-hidro-dutoviário, apresentaram custos maiores, respectivamente da ordem de R$ 661 milhões e R$ 674 milhões respectivamente. Em contrapartida, na análise de mínimo consumo energético o cenário rodo-hidro-dutoviário apresentou um gasto de energia da ordem de 533 mil MJ, cerca de 60% a menos que o consumido no cenário rodoviário, estimado em 1,45 milhões de MJ. Para o cenário rodo-dutoviário obteve-se uma estimativa de 680 mil MJ e para o cenário rodo-ferroviário de 764 mil MJ. Em relação ao porto de destino, São Sebastião foi o que apresentou sistematicamente, a melhor opção para quase todos os cenários analisados. / The growing interest in alternative energy sources, especially for those who can mitigate the emissions of gases causing the greenhouse gases (GHG), has made the production of biofuels increased significantly. In this scenario the ethanol produced from cane sugar, has shown advantages over other biofuels, since the energy generated is relatively high when compared with the consumed in the production process. In this context, brazilian exports, especially the South-Central region, try to supply the global requirements through ethanol production surplus in the country. However, there are logistical bottlenecks in the distribution of this product and it has done that the road transport were excessively used in the ethanol transportation from the plant to the port. Considering these aspects, this research seeks to investigate alternatives to the intermodal transportation of ethanol for export, considering the economic viability and energy used in this biofuel chain logistics. For this, four scenarios were generated using road, rail, pipeline and waterway modes. From the results obtained, the road-rail scenario presented an estimated cost of R$ 654 million, the same order of magnitude of road reference scenario, which was R$ 653 million. Already, the scenarios road-pipeline and road-hydro-pipeline, had higher costs respectively in the order of R$ 661 million and R$ 674 million respectively. In contrast, the analysis of minimum energy consumption the road-hydro-pipeline scenario presented an energy expenditure of approximately 533 thousand MJ, about 60% unless consumed in road scenario, estimated at 1.45 million MJ. For road-pipeline scenario yielded an estimate of 680 thousand MJ and the road-rail scenario of 764 thousand MJ. In relation to the port of destination, São Sebastião was systematically presented, the best option for almost all scenarios analyzed.

Hipóteses teóricas estilizadas apontam para a existência de uma relação em U invertido entre renda e qualidade ambiental, crescente em um primeiro estágio do crescimento econômico e decrescente em um segundo estágio. Relação também conhecida como curva ambiental de Kuznets, do inglês Environmental Kuznets Curve, ou EKC. Diferente de uma infinidade de outras variáveis como o desmatamento e a qualidade da água. Hipóteses empíricas, no entanto, apontam a inexistência para o caso das emissões de poluentes provenientes do consumo de energia (especialmente emissão de carbono). Críticas tanto do ponto de vista teórica quanto da modelagem empírica econométrica apontam para uma série de pontos de falibilidade dos modelos típicos da EKC para tal erro. Essencialmente por serem modelos baseados em hipóteses estilizadas não modeladas que dependem de uma comprovação empírica baseada em modelos pouco robustos. O objetivo do presente é sugerir uma modelagem teórica mais consistente para a relação consumo de energia, qualidade ambiental e crescimento econômico. Para tal objetivo, foi feita uma extensão dos modelos de crescimento de Ramsey-Cass-Koopmans, incorporando as variáveis expressas. / Stylized theoretical hypothesis indicates the existence of an inverted-U shaped relationship between income and environmental quality, up growing in the first step of economic growth and down sloping in a second step. Relationship as well as know as Environmental Kuznets Curve, or simply EKC. However, differently from some other variables such as deforest and water quality, empirical evidences, indicates that for emissions from energy use (specially, carbon emissions) this relationship does not seems to apply. Critics from both views (theoretical and empirical) points up several motivations for EKC fallibility. Essentially because they are models based upon stylized hypothesis (non-proved) and depend upon weak constructed empirical econometrical models. The objective of the present study is suggesting a robust theoretical model for the relationship between economic growth, energy consumption and environmental quality. For the referred objective it has been done a extension of the Ramsey- Cass-Koopmans growth models incorporating the energy and environmental quality.

Tu, Jinlong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 92-95). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese.

"Advances in ubiquitous displays and wireless communications have fueled the emergence of exciting mobile graphics applications including 3D virtual product catalogs, 3D maps, security monitoring systems and mobile games. Current trends that use cameras to capture geometry, material reflectance and other graphics elements means that very high resolution inputs is accessible to render extremely photorealistic scenes. However, captured graphics content can be many gigabytes in size, and must be simplified before they can be used on small mobile devices, which have limited resources, such as memory, screen size and battery energy. Scaling and converting graphics content to a suitable rendering format involves running several software tools, and selecting the best resolution for target mobile device is often done by trial and error, which all takes time. Wireless errors can also affect transmitted content and aggressive compression is needed for low-bandwidth wireless networks. Most rendering algorithms are currently optimized for visual realism and speed, but are not resource or energy efficient on mobile device. This dissertation focuses on the improvement of rendering performance by reducing the impacts of these problems with UbiWave, an end-to-end Framework to enable real time mobile access to high resolution graphics using wavelets. The framework tackles the issues including simplification, transmission, and resource efficient rendering of graphics content on mobile device based on wavelets by utilizing 1) a Perceptual Error Metric (PoI) for automatically computing the best resolution of graphics content for a given mobile display to eliminate guesswork and save resources, 2) Unequal Error Protection (UEP) to improve the resilience to wireless errors, 3) an Energy-efficient Adaptive Real-time Rendering (EARR) heuristic to balance energy consumption, rendering speed and image quality and 4) an Energy-efficient Streaming Technique. The results facilitate a new class of mobile graphics application which can gracefully adapt the lowest acceptable rendering resolution to the wireless network conditions and the availability of resources and battery energy on mobile device adaptively."

Battery life has been the slowest growing resource on mobile systems for several decades. Although much work has been done on designing new chips and peripherals that use less energy, there has not been much work on reducing energy consumption by removing energy intensive tasks from graphics algorithms. In our work, we focus on energy consumption of the ray tracing task because it is a resource-intensive, global-illumination algorithm. We focus our effort on ray tracing dynamic scenes, thus we concentrate on identifying the major elements determining the energy consumption of acceleration structures. We believe acceleration structures are critical in reducing energy consumption because they need to be built inexpensively, but must also be complex enough to boost rendering speed. We conducted tests on a Pentium 1.6 GHz laptop with GeForce Go 6800 GPU. In our experiments, we investigated various elements that modify the acceleration structure build algorithm, and we compared the energy usage of CPU and GPU rendering with different acceleration structures. Furthermore, the energy per frame when ray tracing dynamic scenes was gathered and compared to identify the best acceleration structure that provides a good balance between building energy consumption and rendering energy consumption. We found the bounding volume hierarchy to be the best acceleration structure when rendering dynamic scenes with the GPU on our test system. A bounding volume hierarchy is not the most inexpensive structure to build, but it can be rendered cheaply on the GPU while introducing acceptable energy overhead when rebuilding. In addition, we found the fastest algorithm was also the most inexpensive in terms of energy consumption. We propose an energy model based on this finding.

"Video-based sensor networks can be used to improve environment surveillance, health care and emergency response. Many sensor network scenarios require multiple high quality video streams that share limited wireless bandwidth. At the same time, the lifetime of wireless video sensors are constrained by the capacity of their batteries. Media scaling may extend battery life by reducing the video data rate while still maintaining visual quality, but comes at the expense of additional compression time. This thesis studies the effects of media scaling on video sensor energy consumption by: measuring the energy consumption on the different components of the video sensor; building a energy consumption model with several adjustable parameters to analyze the performance of a video sensor; exploring the trade-offs between the video quality and the energy consumption for a video sensor; and, finally, building a working video sensor to validate the accuracy of the model. The results show that the model is an accurate representation of the power usage of an actual video sensor. In addition, media scaling is often an effective way to reduce energy consumption in a video sensor."

"Due to the dramatic growth in the use of Wireless Sensor Network (WSN) applications - ranging from environment and habitat monitoring to tracking and surveillance, network research in WSN protocols has been very active in the last decade. With battery-powered sensors operating in unattended environments, energy conservation becomes the key technique for improving WSN lifetimes. WSN Medium Access Control (MAC) protocols address energy awareness and reduced duty cycles since the radio is the component that consumes most of the energy. This thesis investigates the performance of two recently published energy-aware MAC protocols, Crankshaft and SCP-MAC. Crankshaft has been shown to be one of the best protocols in terms of energy consumption in dense WSNs while SCP-MAC has a dedicated low duty cycle and low average latencies. The focus of this investigation is to discover techniques for reducing the latency of Crankshaft. Using OMNeT++, an open source and component-based simulation framework, this study investigates possible modifications to Crankshaft to improve its latency. The potential improvements considered include modifications to Crankshaft’s retransmission contention scheme (Sift), adjustments to its inherent settings, and investigating the impact of ACKs. Since OMNeT++ readily provided only a variant of SCP-MAC identified as SCP-MAC*, the simulations results presented involve comparing variants of both protocols (Crankshaft and SCP-MAC*). The performance of these protocols is also analyzed using distinct sensor node communication patterns. It was determined that Crankshaft’s latency depends on its ACK/Retransmission settings. Specifically, Crankshaft has the best latency with No ACKs, without much loss in energy consumption. But the latency can also be improved when ACKs are enabled by reducing the number of retries. Furthermore, the latency and delivery ratio are also directly governed by the WSN traffic pattern and the congestion in the network, as there was a noticeable improvement for both parameters in one-hop traffic, compared to multi-hop convergecast traffic to the sink. Finally, it was observed that Crankshaft’s broadcast performance in flooding traffic can be improved by increasing the number of broadcast slots used, though this is detrimental to its performance in unicast traffic."

O crescente interesse por fontes alternativas de energia, sobretudo por aquelas que consigam mitigar as emissões de gases causadores do efeito estufa (GEE), tem feito com que a produção de biocombustíveis aumentasse significativamente. Neste cenário o etanol produzido a partir da cana de açúcar, tem apresentado vantagem em relação a outros biocombustíveis, uma vez que a energia produzida é relativamente alta quando comparada com a consumida em seu processo produtivo. Neste contexto, as exportações brasileiras, principalmente as da região Centro-Sul, tentam suprir as necessidades mundiais através da produção excedente de etanol no país. No entanto, há gargalos logísticos na distribuição deste produto e isso tem feito que o transporte rodoviário fosse excessivamente utilizado na movimentação do etanol desde a usina até o porto. Diante destes aspectos, esta pesquisa busca investigar alternativas intermodais para a movimentação do etanol destinado à exportação, considerando a viabilidade econômica e energética empregada na cadeia logística deste biocombustível. Para isso, foram gerados quatro cenários utilizando os modos rodoviário, ferroviário, dutoviário e hidroviário. Através dos resultados obtidos, o cenário rodo-ferroviário apresentou uma estimativa de custo da ordem de R$ 654 milhões, valor da mesma ordem de grandeza do cenário rodoviário de referência, que foi de R$ 653 milhões. Já os cenários rodo-dutoviário e rodo-hidro-dutoviário, apresentaram custos maiores, respectivamente da ordem de R$ 661 milhões e R$ 674 milhões respectivamente. Em contrapartida, na análise de mínimo consumo energético o cenário rodo-hidro-dutoviário apresentou um gasto de energia da ordem de 533 mil MJ, cerca de 60% a menos que o consumido no cenário rodoviário, estimado em 1,45 milhões de MJ. Para o cenário rodo-dutoviário obteve-se uma estimativa de 680 mil MJ e para o cenário rodo-ferroviário de 764 mil MJ. Em relação ao porto de destino, São Sebastião foi o que apresentou sistematicamente, a melhor opção para quase todos os cenários analisados. / The growing interest in alternative energy sources, especially for those who can mitigate the emissions of gases causing the greenhouse gases (GHG), has made the production of biofuels increased significantly. In this scenario the ethanol produced from cane sugar, has shown advantages over other biofuels, since the energy generated is relatively high when compared with the consumed in the production process. In this context, brazilian exports, especially the South-Central region, try to supply the global requirements through ethanol production surplus in the country. However, there are logistical bottlenecks in the distribution of this product and it has done that the road transport were excessively used in the ethanol transportation from the plant to the port. Considering these aspects, this research seeks to investigate alternatives to the intermodal transportation of ethanol for export, considering the economic viability and energy used in this biofuel chain logistics. For this, four scenarios were generated using road, rail, pipeline and waterway modes. From the results obtained, the road-rail scenario presented an estimated cost of R$ 654 million, the same order of magnitude of road reference scenario, which was R$ 653 million. Already, the scenarios road-pipeline and road-hydro-pipeline, had higher costs respectively in the order of R$ 661 million and R$ 674 million respectively. In contrast, the analysis of minimum energy consumption the road-hydro-pipeline scenario presented an energy expenditure of approximately 533 thousand MJ, about 60% unless consumed in road scenario, estimated at 1.45 million MJ. For road-pipeline scenario yielded an estimate of 680 thousand MJ and the road-rail scenario of 764 thousand MJ. In relation to the port of destination, São Sebastião was systematically presented, the best option for almost all scenarios analyzed.

Ao se projetar um novo processador, o desempenho não é mais o único objetivo de otimização. Reduzir o consumo de energia também é essencial, pois, enquanto a maior parte dos dispositivos embarcados depende fortemente de bateria, os processadores de propósito geral (GPPs) são restringidos pelos limites da energia térmica de projeto (TDP – thermal design power). Além disso, devido à evolução da tecnologia, a taxa de falhas transientes tem aumentado nos processadores modernos, o que afeta a confiabilidade de sistemas tanto no espaço quanto no nível do mar. Adicionalmente, a maioria dos processadores homogêneos e heterogêneos tem um design fixo, o que limita a adaptação em tempo de execução. Nesse cenário, nós propomos dois designs de processadores que são capazes de realizar o trade-off entre esses eixos de acordo com a aplicação alvo e os requisitos do sistema. Ambos designs baseiam-se em um mecanismo de duplicação de instruções com rollback que detecta e corrige falhas, um módulo de power gating para reduzir o consumo de energia das unidades funcionais. O primeiro é chamado de processador adaptativo e usa thresholds, definidos em tempo de projeto, para adaptar a execução da aplicação Adicionalmente, ele controla o ILP da aplicação para criar mais oportunidade de duplicação e de power gating. O segundo design é chamado processador polimórfico e ele avalia (em tempo de execução) a melhor configuração de hardware a ser usada para cada aplicação. Ele também explora o hardware disponível para maximizar o número de aplicações que são executadas em paralelo. Para a versão adaptativa usando uma configuração orientada a otimização de energia, é possível, em média, economizar 37,2% de energia com um overhead de apenas 8,2% em performance, mantendo baixos níveis de defeito, quando comparado a um design tolerante a falhas. Para a versão polimórfica, os resultados mostram que a reconfiguração dinâmica do processador é capaz de adaptar eficientemente o hardware ao comportamento da aplicação, de acordo com os requisitos especificados pelo designer, chegando a 94.88% do resultado de um processador oráculo quando o trade-off entre os três eixos é considerado. Por outro lado, a melhor configuração estática apenas atinge 28.24% do resultado do oráculo. / Performance is no longer the only optimization goal when designing a new processor. Reducing energy consumption is also mandatory: while most of the embedded devices are heavily dependent on battery power, General-Purpose Processors (GPPs) are being pulled back by the limits of Thermal Design Power (TDP). Moreover, due to technology scaling, soft error rate (i.e., transient faults) has been increasing in modern processors, which affects the reliability of both space and ground-level systems. In addition, most traditional homogeneous and heterogeneous processors have a fixed design, which limits its runtime adaptability. Therefore, they are not able to cope with the changing application behavior when one considers the axes of fault tolerance, performance, and energy consumption altogether. In this context, we propose two processor designs that are able to trade-off these three axes according to the application at hand and system requirements. Both designs rely on an instruction duplication with rollback mechanism that can detect and correct errors and a power gating module to reduce the energy consumption of the functional units The former design, called adaptive processor, uses thresholds defined at design time to allow runtime adaptation of the application’s execution and controls the application’s Instruction-Level Parallelism (ILP) to create more slots for duplication or power gating. The latter design (polymorphic processor) takes the former one step further by dynamically reconfiguring the hardware and evaluating different processor configurations for each application, and it also exploits the available pipelanes to maximize the number of applications that are executed concurrently. For the adaptive processor using an energy-oriented configuration, it is possible, on average, to reduce energy consumption by 37.2% with an overhead of only 8.2% in performance, while maintaining low levels of failure rate, when compared to a fault-tolerant design. For the polymorphic processor, results show that the dynamic reconfiguration of the processor is able to efficiently match the hardware to the behavior of the application, according to the requirements of the designer, achieving 94.88% of the result of an oracle processor when the trade-off between the three axes is considered. On the other hand, the best static configuration only achieves 28.24% of the oracle’s result.

As redes de sensores sem fio (wsns) têm ganhado cada vez mais espaço no monitoramento e controle de processos na indústria. Dentro destas redes, os dispositivos são alimentados por baterias, e a comunicação é feita por radiofrequência. Por conta disto, os rádios dos dispositivos são responsáveis por consumir boa parte da energia armazenada nas suas baterias, e a comunicação dos dispositivos está sujeita à interferência provinda de outras redes e do maquinário industrial. Para sanar estes problemas podem ser empregadas técnicas de controle de potência de transmissão (cpt). Existem diversas técnicas de cpt na literatura, visando os mais diversos objetivos, desde economia de energia e redução de interferência, até controle da topologia da rede. Este trabalho apresenta uma proposta de emprego de (cpt) em uma rede de sensores sem fio através da utilização de controladores proporcionais-integrais (pi). Juntamente com a técnica proposta, são apresentados um procedimento para projeto dos controladores e alguns algoritmos desenvolvidos para o caso ideal e para os casos com saturação dos níveis de potência disponíveis. Este trabalho se diferencia dos trabalhos encontrados na literatura por apresentar uma técnica de controle linear e que depende apenas de informações já disponíveis em cada dispositivo cuja potência será ajustada. Deste modo, esta técnica pode ser empregada em conjunto com protocolos industriais mais restritivos quanto às informações que podem ser trocadas nas mensagens. Além disso, esta técnica reduz ainda mais o consumo e a interferência por evitar transmissões desnecessárias. A proposta apresentada foi validada através de simulações e de um experimento com dispositivos WirelessHART reais, apresentando bons resultados e provando que é possível controlar a potência sem a necessidade das informações extras. / Wireless sensor networks (wsns) are being increasingly adopted in monitor and control tasks in the industry. The devices within these networks are battery-powered, and they communicate through radio frequency. Therefore the radios of the devices account for the most of the consumption of the energy stored in the batteries, and the devices’ communication is subject to interference from other networks and industrial machinery. Transmission power control (tpc) techniques can be employed to cope with these problems. There are several tpc techniques in the literature, aiming at a wide range of objectives, from energy saving and interference reduction, to network topology control. This work presents the proposal of a (tpc) technique in a wireless sensor network that works by employing proportional-integral (pi) controllers. Besides the technique itself, a procedure is presented to design the controllers along some algorithms developed to the ideal case, and the case when there is saturation in the available power levels. This work, unlike the other works found in the literature, presents a linear technique that depends only on information that is already available in each device whose power needs to be adjusted. Therefore, the proposed technique can be employed together with more restrictive industrial protocols that limit the information that can be exchanged in the messages. Besides, it further reduces the power consumption and the interference by avoiding unnecessary transmissions. The proposal was validated through simulations and an experiment using real WirelessHART devices, presenting good results and proving that it is possible to adjust the transmission power without necessarily using the extra information.