968 resultados para Energy needs


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"General, misc., & progress report (nonnuclear) TID-4500."

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Sunset project manager : Terry H. Stoica.

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Foam-filled conical tubes have recently emerged as efficient energy absorbing devices to mitigate the adverse effects of impacts. The primary aim of this thesis was to generate research and design information on the impact and energy absorption response of empty and foam-filled conical tubes, and to facilitate their application in energy absorbing systems under axial and oblique loading conditions representative of those typically encountered in crashworthiness and impact applications. Finite element techniques supported by experiments and existing results were used in the investigation. Major findings show that the energy absorption response can be effectively controlled by varying geometry and material parameters. A useful empirical formula was developed for providing engineering designers with an initial estimate of the load ratio and hence energy absorption performances of these devices. It was evident that foam-filled conical tubes enhance the energy absorption capacity and stabilise the crush response for both axial and oblique impact loading without a significant increase in the initial peak load. This is practically beneficial when higher kinetic energy needs to be absorbed, thus reducing the impact force transmitted to the protected structure and occupants. Such tubes also increase and maintain the energy absorption capacity under global bending as well as minimise the reduction of energy absorption capacity with increasing load angle. Furthermore, the results also highlight the feasibility of adding a foam-filled conical tube as a supplementary device in energy absorbing systems, since the overall energy absorption performance of such systems can be favourably enhanced by only including a relatively small energy absorbing device. Above all, the results demonstrate the superior performance of foam-filled conical tube for mitigating impact energy in impact and crashworthiness applications.

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The biomass resources, existing utilization levels and the efficiency of its use have been analyzed for a South Indian village. A biomass based energy efficient strategy has been devised to meet all the energy needs of the village, including substitution of fuels such as electricity and kerosene used in specific activities. Results indicate that the potential as well as the technologies exist for such substitutions. The proposed strategy will lead to an increase in the efficiency of energy use, reduce human drudgery and make villages more self reliant.

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The decentralized power is characterised by generation of power nearer to the demand centers, focusing mainly on meeting local energy needs. A decentralized power system can function either in the presence of grid, where it can feed the surplus power generated to the grid, or as an independent/stand-alone isolated system exclusively meeting the local demands of remote locations. Further, decentralized power is also classified on the basis of type of energy resources used-non-renewable and renewable. These classifications along with a plethora of technological alternatives have made the whole prioritization process of decentralized power quite complicated for decision making. There is abundant literature, which has discussed various approaches that have been used to support decision making under such complex situations. We envisage that summarizing such literature and coming out with a review paper would greatly help the policy/decision makers and researchers in arriving at effective solutions. With such a felt need 102 articles were reviewed and features of several technological alternatives available for decentralized power, the studies on modeling and analysis of economic, environmental and technological asibilities of both grid-connected (GC) and stand-alone (SA) systems as decentralized power options are presented. (C) 2009 Elsevier Ltd. All rights reserved.

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Present work shows the feasibility of decentralized energy options for the Tumkur district in India. Decentralized energy planning (DEP) involves scaling down energy planning to subnational or regional scales. The important aspect of the energy planning at decentralized level would be to prepare an area-based DEP to meet energy needs and development of alternate energy sources at least-cost to the economy and environment. The geographical coverage and scale reflects the level at which the analysis takes place, which is an important factor in determining the structure of models. In the present work, DEP modeling under different scenarios has been carried out for Tumkur district of India for the year 2020. DEP model is suitably scaled for obtaining the optimal mix of energy resources and technologies using a computer-based goal programming technique. The rural areas of the Tumkur district have different energy needs. Results show that electricity needs can be met by biomass gasifier technology, using biomass feedstock produced by allocating only 12% of the wasteland in the district at 8 t/ha/yr of biomass productivity. Surplus electricity can be produced by adopting the option of biomass power generation from energy plantations. The surplus electricity generated can be supplied to the grid. The sustainable development scenario is a least cost scenario apart from promoting self-reliance, local employment, and environmental benefits. (C) 2010 American Institute of Chemical Engineers Environ Prog, 30: 248-258, 2011

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One of the critical problems currently being faced by agriculture industry in developing nations is the alarming rate of groundwater depletion. Irrigation accounts for over 70% of the total groundwater withdrawn everyday. Compounding this issue is the use of polluting diesel generators to pump groundwater for irrigation. This has made irrigation not only the biggest consumer of groundwater but also one of the major contributors to green house gases. The aim of this thesis is to present a solution to the energy-water nexus. To make agriculture less dependent on fossil fuels, the use of a solar-powered Stirling engine as the power generator for on-farm energy needs is discussed. The Stirling cycle is revisited and practical and ideal Stirling cycles are compared. Based on agricultural needs and financial constraints faced by farmers in developing countries, the use of a Fresnel lens as a solar-concentrator and a Beta-type Stirling engine unit is suggested for sustainable power generation on the farms. To reduce the groundwater consumption and to make irrigation more sustainable, the conceptual idea of using a Stirling engine in drip irrigation is presented. To tackle the shortage of over 37 million tonnes of cold-storage in India, the idea of cost-effective solar-powered on-farm cold storage unit is discussed.

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In the last fifty years, Nunavut has developed a deep dependence on diesel for virtually all of its energy needs, including electricity. This dependence has created a number of economic, environmental and health related challenges in the territory, with an estimated 20% of the territory’s annual budget being spent on energy, thereby limiting the Government of Nunavut’s ability to address other essential infrastructure and societal needs, such as education, nutrition and health care and housing. One solution to address this diesel dependency is the use of renewable energy technologies (RETs), such as wind, solar and hydropower. As such, this thesis explores energy alternatives in Nunavut, and through RETScreen renewable energy simulations, found that solar power and wind power are technically viable options for Nunavut communities and a potentially successful means to offset diesel-generated electricity in Nunavut. However, through this analysis it was also discovered that accurate data or renewable resources are often unavailable for most Nunavut communities. Moreover, through qualitative open-ended interviews, the perspectives of Nunavut residents with regards to developing RETs in Nunavut were explored, and it was found that respondents generally supported the use of renewable energy in their communities, while acknowledging that there still remains a knowledge gap among residents regarding renewable energy, stemming from a lack of communication between the communities, government and the utility company. In addition, the perceived challenges, opportunities and gaps that exist with regards to renewable energy policy and program development were discussed with government policy-makers through further interviews, and it was discovered that often government departments work largely independently of each other rather than collaboratively, creating gaps and oversights in renewable energy policy in Nunavut. Combined, the results of this thesis were used to develop a number of recommended policy actions that could be undertaken by the territorial and federal government to support a shift towards renewable energy in order to develop a sustainable and self-sufficient energy plan in Nunavut. They include: gathering accurate renewable resource data in Nunavut; increasing community consultations on the subject of renewable energy; building strong partnerships with universities, colleges and industry; developing a knowledge sharing network; and finally increasing accessibility to renewable energy programs and policies in Nunavut.

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The suitability of models specifically re-parameterized for analyzing energy balance data relating metabolizable energy intake to growth rate has recently been investigated in male broilers. In this study, the more adequate of those models was applied to growing turkeys to provide estimates of their energy needs for maintenance and growth. Three functional forms were used. They were: two equations representing diminishing returns behaviour (monomolecular and rectangular hyperbola); and one equation describing smooth sigmoidal behaviour with a fixed point of inflexion (Gompertz). The models estimated the metabolizable energy requirement for maintenance in turkeys to be 359-415 kJ/kg of live-weight/day. The predicted values of average net energy requirement for producing 1 g of gain in live-weight, between 1 and 4 times maintenance, varied from 8.7 to 10.9 kJ. These results and those previously reported for broilers are a basis for accepting the general validity of these models.

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Summary 1. Agent-based models (ABMs) are widely used to predict how populations respond to changing environments. As the availability of food varies in space and time, individuals should have their own energy budgets, but there is no consensus as to how these should be modelled. Here, we use knowledge of physiological ecology to identify major issues confronting the modeller and to make recommendations about how energy budgets for use in ABMs should be constructed. 2. Our proposal is that modelled animals forage as necessary to supply their energy needs for maintenance, growth and reproduction. If there is sufficient energy intake, an animal allocates the energy obtained in the order: maintenance, growth, reproduction, energy storage, until its energy stores reach an optimal level. If there is a shortfall, the priorities for maintenance and growth/reproduction remain the same until reserves fall to a critical threshold below which all are allocated to maintenance. Rates of ingestion and allocation depend on body mass and temperature. We make suggestions for how each of these processes should be modelled mathematically. 3. Mortality rates vary with body mass and temperature according to known relationships, and these can be used to obtain estimates of background mortality rate. 4. If parameter values cannot be obtained directly, then values may provisionally be obtained by parameter borrowing, pattern-oriented modelling, artificial evolution or from allometric equations. 5. The development of ABMs incorporating individual energy budgets is essential for realistic modelling of populations affected by food availability. Such ABMs are already being used to guide conservation planning of nature reserves and shell fisheries, to assess environmental impacts of building proposals including wind farms and highways and to assess the effects on nontarget organisms of chemicals for the control of agricultural pests. Keywords: bioenergetics; energy budget; individual-based models; population dynamics.

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The domestic dog has undergone extensive artificial selection resulting in an extreme diversity in body size, personality, life‐history, and metabolic traits among breeds. Here we tested whether proactive personalities (high levels of activity, boldness, and aggression) are related to a fast “pace of life” (high rates of growth, mortality, and energy expenditure). Data from the literature provide preliminary evidence that artificial selection on dogs (through domestication) generated variations in personality traits that are correlated with life histories and metabolism. We found that obedient (or docile, shy) breeds live longer than disobedient (or bold) ones and that aggressive breeds have higher energy needs than unaggressive ones. These correlations could result from either human preference for particular trait combinations or, more likely, correlated responses to artificial selection on personality. Our results suggest the existence of a general pace‐of‐life syndrome arising from the coevolution of personality, metabolic, and life‐history traits.

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Tumour necrosis factor (TNF)-α has been found to be increased in malnourished chronic obstructive pulmonary disease (COPD) patients; however, the main cause of this phenomenon remains undetermined. In normal subjects, TNF-α production may be induced by dietary energy deprivation. The aim of this study was to investigate if stable COPD patients present alterations of inflammatory mediators after 48 h of dietary energy restriction. Fourteen COPD patients were admitted to the hospital while receiving an experimental diet with an energy content of approximately one-third of their energy needs. Clinical evaluation, nutritional assessment and serum levels of interleukin (IL)-6, TNF-α and C-reactive protein, and secretion of TNF-α by peripheral blood monocytes were assessed on admission and after the experimental diet. For reference values of the laboratory parameters, blood was collected from 10 healthy, elderly subjects. COPD patients showed significantly higher serum concentrations of IL-6 than control subjects, however, the experimental diet was not associated with statistically significant changes in the inflammatory mediators. The findings of this study, although preliminary because of the limited degree and duration of the energy restriction, suggest that the elevated levels of tumour necrosis factor-α, previously described in undernourished or weight-losing chronic obstructive pulmonary disease patients, may not be linked to a decrease of dietary energy intake.

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Predictions about electric energy needs, based on current electric energy models, forecast that the global energy consumption on Earth for 2050 will double present rates. Using distributed procedures for control and integration, the expected needs can be halved. Therefore implementation of Smart Grids is necessary. Interaction between final consumers and utilities is a key factor of future Smart Grids. This interaction is aimed to reach efficient and responsible energy consumption. Energy Residential Gateways (ERG) are new in-building devices that will govern the communication between user and utility and will control electric loads. Utilities will offer new services empowering residential customers to lower their electric bill. Some of these services are Smart Metering, Demand Response and Dynamic Pricing. This paper presents a practical development of an ERG for residential buildings.

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For many years the European Union has been improving the efficient use of energy resources and yet the demand for energy in the EU continues to increase. When Europe belonged to one of the world’s key energy markets with relatively easy access to energy resources, growing energy needs were not seen as a source of concern. Today, however, as the competition for energy resources is intensifying and the global position of the EU energy market is being challenged by growing economies in the developing countries, above all China and India, the EU needs to adopt bold policies to guarantee the sustainable supply of energy. This report argues the EU needs to develop a fully-fledged external energy policy; i.e. a common, coherent, strategic approach that build bridges between the interests and needs of the EU integrated energy market on the one hand and supplier countries on the other. The EU’s external energy policy has two main objectives. The first one is to ensure a sustainable, stable and cost-effective energy supply. The second is to promote energy market integration and regulatory convergence with neighbouring countries (often but not always this supports the achievement of the first objective). However, in order to improve its effectiveness, the EU’s external energy policy needs to be seen in a broader economic and political context. Any progress in energy cooperation with third countries is contingent upon the EU’s general stance and offer to those countries.