973 resultados para Rational use of energy
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The further development of the use of NMR relaxation times in chemical, biological and medical research has perhaps been curtailed by the length of time these measurements often take. The DESPOT (Driven Equilibrium Single Pulse Observation of T1) method has been developed, which reduces the time required to make a T1 measurement by a factor of up to 100. The technique has been studied extensively herein and the thesis contains recommendations for its successful experimental application. Modified DESPOT type equations for use when T2 relaxation is incomplete or where off-resonance effects are thought to be significant are also presented. A recently reported application of the DESPOT technique to MR imaging gave good initial results but suffered from the fact that the images were derived from spin systems that were not driven to equilibrium. An approach which allows equilibrium to be obtained with only one non-acquisition sequence is presented herein and should prove invaluable in variable contrast imaging. A DESPOT type approach has also been successfully applied to the measurement of T1. T_1's can be measured, using this approach significantly faster than by the use of the classical method. The new method also provides a value for T1 simultaneously and therefore the technique should prove valuable in intermediate energy barrier chemical exchange studies. The method also gives rise to the possibility of obtaining simultaneous T1 and T1 MR images. The DESPOT technique depends on rapid multipulsing at nutation angles, normally less than 90^o. Work in this area has highlighted the possible time saving for spectral acquisition over the classical technique (90^o-5T_1)_n. A new method based on these principles has been developed which permits the rapid multipulsing of samples to give T_1 and M_0 ratio information. The time needed, however, is only slightly longer than would be required to determine the M_0 ratio alone using the classical technique. In ^1H decoupled ^13C spectroscopy the method also gives nOe ratio information for the individual absorptions in the spectrum.
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This thesis is concerned with the use of the synoptic approach within decision making concerning nuclear waste management. The synoptic approach to decision making refers to an approach to rational decision making that assumes as an ideal, comprehensiveness of information and analysis. Two case studies are examined in which a high degree of synoptic analysis has been used within the decision making process. The case studies examined are the Windscale Inquiry into the decision to build the THORP reprocessing plant and the Nirex safety assessment of nuclear waste disposal. The case studies are used to test Lindblom's hypothesis that a synoptic approach to decision making is not achievable. In the first case study Lindblom's hypothesis is tested through the evaluation of the decision to build the THORP plant, taken following the Windscale Inquiry. It is concluded that the incongruity of this decision supports Lindblom's hypothesis. However, it has been argued that the Inquiry should be seen as a legitimisation exercise for a decision that was effectively predetermined, rather than a rigorous synoptic analysis. Therefore, the Windscale Inquiry does not provide a robust test of the synoptic method. It was concluded that a methodology was required, that allowed robust conclusions to be drawn, despite the ambiguity of the role of the synoptic method in decision making. Thus, the methodology adopted for the second case study was modified. In this case study the synoptic method was evaluated directly. This was achieved through the analysis of the cogency of the Nirex safety assessment. It was concluded that the failure of Nirex to provide a cogent synoptic analysis supported Lindblom's criticism of the synoptic method. Moreover, it was found that the synoptic method failed in the way that Lindblom predicted that it would.
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Shropshire Energy Team initiated this study to examine consumption and associated emissions in the predominantly rural county of Shropshire. Current use of energy is not sustainable in the long term and there are various approaches to dealing with the environmental problems it creates. Energy planning by a local authority for a sustainable future requires detailed energy consumption and environmental information. This information would enable target setting and the implementation of policies designed to encourage energy efficiency improvements and exploitation of renewable energy resources. This could aid regeneration strategies by providing new employment opportunities. Associated reductions in carbon dioxide and other emissions would help to meet national and international environmental targets. In the absence of this detailed information, the objective was to develop a methodology to assess energy consumption and emissions on a regional basis from 1990 onwards for all local planning authorities. This would enable a more accurate assessment of the relevant issues, such that plans are more appropriate and longer lasting. A first comprehensive set of data has been gathered from a wide range of sources and a strong correlation was found between population and energy consumption for a variety of regions across the UK. In this case the methodology was applied to the county of Shropshire to give, for the first time, estimates of primary fuel consumption, electricity consumption and associated emissions in Shropshire for 1990 to 2025. The estimates provide a suitable baseline for assessing the potential contribution renewable energy could play in meeting electricity demand in the country and in reducing emissions. The assessment indicated that in 1990 total primary fuel consumption was 63,518,018 GJ/y increasing to 119,956,465 GJ/y by 2025. This is associated with emissions of 1,129,626 t/y of carbon in 1990 rising to 1,303,282 t/y by 2025. In 1990, 22,565,713 GJ/y of the primary fuel consumption was used for generating electricity rising to 23,478,050 GJ/y in 2025. If targets to reduce primary fuel consumption are reached, then emissions of carbon would fall to 1,042,626 by 2025, if renewable energy targets were also reached then emissions of carbon would fall to 988,638 t/y by 2025.
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The aim of the research project was to gain d complete and accurate accounting of the needs and deficiencies of materials selection and design data, with particular attention given to the feasibility of a computerised materials selection system that would include application analysis, property data and screening techniques. The project also investigates and integrates the three major aspects of materials resources, materials selection and materials recycling. Consideration of the materials resource base suggests that, though our discovery potential has increased, geologic availability is the ultimate determinant and several metals may well become scarce at the same time, thus compounding the problem of substitution. With around 2- to 20- million units of engineering materials data, the use of a computer is the only logical answer for scientific selection of materials. The system developed at Aston is used for data storage, mathematical computation and output. The system enables programs to be run in batch and interactive (on-line) mode. The program with modification can also handle such variables as quantity of mineral resources, energy cost of materials and depletion and utilisation rates of strateqic materials. The work also carries out an in-depth study of copper recycling in the U.K. and concludes that, somewhere in the region of 2 million tonnes of copper is missing from the recycling cycle. It also sets out guidelines on product design and conservation policies from the recyclability point of view.
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The use of the pyrolysis process to obtain valuable products from biomass is amongst the technologies being investigated as a source for renewable energy. The pyrolysis process yields products such as biochar, bio-oil and non condensable gases. The main objective of this project is to increase energy recovery from sewage sludge by utilising the intermediate pyrolysis process. The intermediate pyrolysis has a residence time ranging from 5 to 10 minutes. The main product yields from sewage sludge pyrolysis are 50 wt% biochar, 40 wt% bio-oil and 10 wt% non condensable gases. The project was carried out on a pilot plant scale reactor with a load capacity of 20 kg/h. This enabled a high yield of biochar and bio-oil. The characterisation of the products indicated that the organic phase of the bio-oil had good fuel properties such as having high energy content of 39 MJ/kg, low acid number of 21.5, high flash point of 150 and viscosity of 35 cSt. An increase in pyrolysis experiments enabled large quantities of pyrolysis oil production. Co-pyrolysis of sewage sludge was carried out on laboratory scale with mixed wood, rapeseed and straw. It found that there was an increase in bio-oil quantity with rapeseed while co-pyrolysis with wood helped to mask the smell of the sludge pyrolysis oil. Engine test were successfully carried out in an old Lister engine with pyrolysis oil fractions of 30% and 50% blended with biodiesel. This indicates that these pyrolysis oil fractions can be used in similar engine types without any problems however long term effects in ordinary engines are unknown. An economic evaluation was carried out about the implementation of the intermediate pyrolysis process for electricity production in a CHP using the pyrolysis oil. The prices of electricity per kWh were found to be very high.
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Grape is one of the world's largest fruit crops with approximately 67.5 million tonnes produced each year and energy is an important element in modern grape productions as it heavily depends on fossil and other energy resources. Efficient use of these energies is a necessary step toward reducing environmental hazards, preventing destruction of natural resources and ensuring agricultural sustainability. Hence, identifying excessive use of energy as well as reducing energy resources is the main focus of this paper to optimize energy consumption in grape production.In this study we use a two-stage methodology to find the association of energy efficiency and performance explained by farmers' specific characteristics. In the first stage a non-parametric Data Envelopment Analysis is used to model efficiencies as an explicit function of human labor, machinery, chemicals, FYM (farmyard manure), diesel fuel, electricity and water for irrigation energies. In the second step, farm specific variables such as farmers' age, gender, level of education and agricultural experience are used in a Tobit regression framework to explain how these factors influence efficiency of grape farming.The result of the first stage shows substantial inefficiency between the grape producers in the studied area while the second stage shows that the main difference between efficient and inefficient farmers was in the use of chemicals, diesel fuel and water for irrigation. The use of chemicals such as insecticides, herbicides and fungicides were considerably less than inefficient ones. The results revealed that the more educated farmers are more energy efficient in comparison with their less educated counterparts. © 2013.
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Dwindling oil reserves and growing concerns over carbon dioxide emissions and associated climate change are driving the utilisation of renewable feedstocks as alternative, sustainable fuel sources. Catalysis has a rich history of facilitating energy efficient, selective molecular transformations, and contributes to 90% of current chemical manufacturing processes. In a post-petroleum era, catalysis will be pivotal in overcoming the scientific and engineering barriers to economically feasible bio-fuels. This perspective highlights some recent developments in heterogeneous catalysts for the synthesis of biodiesel from renewable resources, derived from plant and aquatic oil sources. Particular attention will be paid to the importance of catalyst pore architecture, surface polarity and acid and base properties, in meeting the challenge of transforming highly polar and viscous bio-based reactants. © 2012 The Royal Society of Chemistry.
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Sol-gel-synthesized bioactive glasses may be formed via a hydrolysis condensation reaction, silica being introduced in the form of tetraethyl orthosilicate (TEOS), and calcium is typically added in the form of calcium nitrate. The synthesis reaction proceeds in an aqueous environment; the resultant gel is dried, before stabilization by heat treatment. These materials, being amorphous, are complex at the level of their atomic-scale structure, but their bulk properties may only be properly understood on the basis of that structural insight. Thus, a full understanding of their structure-property relationship may only be achieved through the application of a coherent suite of leading-edge experimental probes, coupled with the cogent use of advanced computer simulation methods. Using as an exemplar a calcia-silica sol-gel glass of the kind developed by Larry Hench, in the memory of whom this paper is dedicated, we illustrate the successful use of high-energy X-ray and neutron scattering (diffraction) methods, magic-angle spinning solid-state NMR, and molecular dynamics simulation as components to a powerful methodology for the study of amorphous materials.
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A tanulmány a hazai kis- és középvállalati szektorban 2006-ban elvégzett, majd 2010-ben megismételt kérdőíves felmérések eredményei alapján igyekszik bemutatni a racionális vállalati gazdálkodás sajátosságait. Vizsgálatunk fő kérdése, hogy e szektor vállalkozásainak gazdálkodását milyen tényezők teszik ésszerűvé, s hogy a 2006-2010 között eltelt időszakban milyen változások figyelhetők meg a gazdálkodói magatartásuk alakulásában. Eredményeink alapján megállapíthatjuk, hogy a mai napig megtalálhatók a kisvállalkozói - háztartási szemléletű, megélhetésorientált - gazdálkodás nyomai, de a racionális gazdálkodás általunk használt mutatói szerint e vállalkozások körében szakszerűbbé vált a gazdálkodás. Ebben a folyamatban szerepet játszott a gazdasági válság, amely által előidézett helyzethez kénytelenek voltak alkalmazkodni a kis- és közepes vállalkozások: felismerték, hogy célravezetőbb a hatékonyság és a költségek szempontjából a racionális pénzpiaci magatartás követése, s ezzel összhangban a válság miatti zavarok elhárítására kiadáscsökkentő eszközök alkalmazása. A kis- és közepes vállalkozások gazdálkodásával kapcsolatos racionális döntések előmozdításában elsősorban a korszerű pénzügyi ismereteknek és a szakmai tudásnak van szerepe. / === / The study seeks to identify the attributes of rational business operation, using a questionnaire survey of small and medium-sized firms made in 2006 and a repeat of it in 2010. The main questions addressed are what factors contribute to rational operation in the firms in the sector and what changes over the 2006-10 period can be discerned in business behaviour. The findings show that traces of small business-style operation (a household or livelihood orientation) could still be found, but the indicators of rationality employed in the survey show that the operation of the firms became more rational. A role in the process was played by the economic crisis, which forced small and medium-sized businesses to adapt: they recognized that it was better from the point of view of efficiency and costs to follow rational money-market behaviour, and in line with that, use spending-reduction tools to evade the disturbances of the crisis. The main factors behind the shift towards rational decision-making in the running of small and medium-sized firms are up-to-date financial information and professional expertise.
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Current energy systems are in most instances not fully working sustainably. The provision and use of energy only consider limited resources, risk potential or financial constraints on a limited scale. Furthermore, the knowledge and benefits are only available for a minor group of the population or are outright neglected. The availability of different resources for energy purposes determines economic development, as well as the status of the society and the environment. The access to energy grids has an impact on socio-economic living standards of communities. This not fully developed system is causing climate change with all its related outcomes. This investigation takes into consideration different views on renewable energy systems — such as international discussions about biomass use for energy production, “fuel versus food”, biogas use — and attempts to compare major prospects of social acceptance of renewable energy in Europe and Africa. Can all obstacles to the use of renewable energy be so profound that the overall strategy of reducing anthropogenic causes of climate change be seriously affected?
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Current energy systems are in most instances not fully working sustainably. The provision and use of energy only consider limited resources, risk potential or financial constraints on a limited scale. Furthermore, the knowledge and benefits are only available for a minor group of the population or are outright neglected. The availability of different resources for energy purposes determines economic development, as well as the status of the society and the environment. The access to energy grids has an impact on socio-economic living standards of communities. This not fully developed system is causing climate change with all its related outcomes. This investigation takes into consideration different views on renewable energy systems — such as international discussions about biomass use for energy production, “fuel versus food”, biogas use — and attempts to compare major prospects of social acceptance of renewable energy in Europe and Africa. Can all obstacles to the use of renewable energy be so profound that the overall strategy of reducing anthropogenic causes of climate change be seriously affected?
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Changing demographics impact our schools as children come from more linguistically and culturally diverse backgrounds. The various social, cultural, and economic backgrounds of the students affect their early language learning experiences which expose them to the academic language needed to succeed in school. Teachers can help students acquire academic language by introducing words that are within their Zone of Proximal Development and increasing exposure to and use of academic language. This study investigated the effects of increasing structured activities for students to orally interact with informational text on their scientific academic language development and comprehension of expository text. ^ The Academic Text Talk activities, designed to scaffold verbalization of new words and ideas, included discussion, retelling, games, and sentence walls. This study also evaluated if there were differences in scientific language proficiency and comprehension between boys and girls, and between English language learners and native English speakers. ^ A quasi-experimental design was used to determine the relationship between increasing students' oral practice with academic language and their academic language proficiency. Second graders (n = 91) from an urban public school participated in two science units over an 8 week period and were pre and post tested using the Woodcock Muñoz Language Survey-Revised and vocabulary tests from the National Energy Education Project. Analysis of covariance was performed on the pre to post scores by treatment group to determine differences in academic language proficiency for students taught using Academic Text Talk compared to students taught using a text-centered method, using the initial Florida Assessment for Instruction in Reading test as a covariate. Students taught using Academic Text Talk multimodal strategies showed significantly greater increases in their pre to posttest means on the Woodcock Muñoz Language Survey-Revised Oral Language Totals and National Energy Education Development Project Vocabulary tests than students taught using the text-centered method, ps < .05. Boys did not show significantly greater increases than girls, nor did English language learners show significantly greater increases than the native English speakers. ^ This study informs the field of reading research by evaluating the effectiveness of a multimodal combination of strategies emphasizing discourse to build academic language.^
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Acknowledgements We are grateful to the United Kingdom Economic and Social Research Council Nexus Network for funding this work.
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Acknowledgements We are grateful to the United Kingdom Economic and Social Research Council Nexus Network for funding this work.
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We thank Orkney Islands Council for access to Eynhallow and Talisman Energy (UK) Ltd and Marine Scotland for fieldwork and equipment support. Handling and tagging of fulmars was conducted under licences from the British Trust for Ornithology and the UK Home Office. EE was funded by a Marine Alliance for Science and Technology for Scotland/University of Aberdeen College of Life Sciences and Medicine studentship and LQ was supported by a NERC Studentship. Thanks also to the many colleagues who assisted with fieldwork during the project, and to Helen Bailey and Arliss Winship for advice on implementing the state-space model.