859 resultados para Design for flexibility in use


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This thesis reviews the main methodological developments in public sector investment appraisal and finds growing evidence that appraisal techniques are not fulfilling their earlier promise. It is suggested that an important reason for this failure lies in the inability of these techniques to handle uncertainty except in a highly circumscribed fashion. It is argued that a more fruitful approach is to strive for flexibility. Investment projects should be formulated with a view to making them responsive to a wide range of possible future events, rather than embodying a solution which is optimal for one configuration of circumstances only. The distinction drawn in economics between the short and the long run is used to examine the nature of flexibility. The concept of long run flexibility is applied to the pre-investment range of choice open to the decisionmaker. It is demonstrated that flexibility is reduced at a very early stage of decisionmaking by the conventional system of appraisal which evaluates only a small number of options. The pre-appraisal filtering process is considered further in relation to decisionmaking models. It is argued that for public sector projects the narrowing down of options is best understood in relation to an amended mixed scanning model which places importance on the process by which the 'national interest ' is determined. Short run flexibility deals with operational characteristics, the degree to which particular projects may respond to changing demands when the basic investment is already in place. The tension between flexibility and cost is noted. A short case study on the choice of electricity generating plant is presented. The thesis concludes with a brief examination of the approaches used by successive British governments to public sector investment, particularly in relation to the nationalised industries

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In this article, a social theory framework is developed to explain the common themes of recursive and adaptive practice underpinning the existing strategic management literature. In practice, there is a coexistent tension between recursive and adaptive forms of strategic action that spans multiple levels from macro-institutional and competitive contexts to within-firm levels of analysis to individual cognition. This tension may be better understood by examining how management practices are used to put strategy into practice. Such practices span multiple levels of context and are adaptable to their circumstances of use, serving to highlight both general characteristics and localized idiosyncrasies of strategy as practice. The article develops the concept of management practices-in-use into a research agenda and nine broad research questions that may be used to investigate empirically strategy as practice.

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DUE TO COPYRIGHT RESTRICTIONS ONLY AVAILABLE FOR CONSULTATION AT ASTON UNIVERSITY LIBRARY AND INFORMATION SERVICES WITH PRIOR ARRANGEMENT

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Virus-specific CD8+ T cells are known to play an important role in the control of HIV infection. In this study we investigated whether there may be qualitative differences in the CD8+ T cell response in HIV-1- and HIV-2-infected individuals that contribute to the relatively efficient control of the latter infection. A molecular comparison of global TCR heterogeneity showed a more oligoclonal pattern of CD8 cells in HIV-1- than HIV-2-infected patients. This was reflected in restricted and conserved TCR usage by CD8+ T cells recognizing individual HLA-A2- and HLA-B57-restricted viral epitopes in HIV-1, with limited plasticity in their response to amino acid substitutions within these epitopes. The more diverse TCR usage observed for HIV-2-specific CD8 T cells was associated with an enhanced potential for CD8+ expansion and IFN- production on cross-recognition of variant epitopes. Our data suggest a mechanism that could account for any possible cross-protection that may be mediated by HIV-2-specific CD8+ T cells against HIV-1 infection. Furthermore, they have implications for HIV vaccine development, demonstrating an association between a polyclonal, virus-specific CD8+ T cell response and an enhanced capacity to tolerate substitutions within T cell epitopes.

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This material is based upon work supported by the National Science Foundation through the Florida Coastal Everglades Long-Term Ecological Research program under Cooperative Agreements #DBI-0620409 and #DEB-9910514. This image is made available for non-commercial or educational use only.

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This thesis discusses market design and regulation in electricity systems, focusing on the information exchange of the regulated grid firm and the generation firms as well as the regulation of the grid firm. In the first chapter, an economic framework is developed to consistently analyze different market designs and the information exchange between the grid firm and the generation firms. Perfect competition between the generation firms and perfect regulation of the grid firm is assumed. A numerical algorithm is developed and its feasibility demonstrated on a large-scale problem. The effects of different market designs for the Central Western European (CWE) region until 2030 are analyzed. In the second chapter, the consequences of restricted grid expansion within the current market design in the CWE region until 2030 are analyzed. In the third chapter the assumption of efficient markets is modified. The focus of the analysis is then, whether and how inefficiencies in information availability and processing affect different market designs. For different parameter settings, nodal and zonal pricing are compared regarding their welfare in the spot and forward market. In the fourth chapter, information asymmetries between the regulator and the regulated firm are analyzed. The optimal regulatory strategy for a firm, providing one output with two substitutable inputs, is defined. Thereby, one input and the absolute quantity of inputs is not observable for the regulator. The result is then compared to current regulatory approaches.

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In the current Cambodian higher education sector, there is little regulation of standards in curriculum design of undergraduate degrees in English language teacher education. The researcher, in the course of his professional work in the Curriculum and Policy Office at the Department of Higher Education, has seen evidence that most universities tend to copy their curriculum from one source, the curriculum of the Institute of Foreign Languages, the Royal University of Phnom Penh. Their programs fail to impose any entry standards, accepting students who pass the high school exam without any entrance examination. It is possible for a student to enter university with satisfactory scores in all subjects but English. Therefore, not many graduates are able to fulfil the professional requirements of the roles they are supposed to take. Neau (2010) claims that many Cambodian EFL teachers do not reach a high performance standard due to their low English language proficiency and poor background in teacher education. The main purpose of this study is to establish key guidelines for developing curricula for English language teacher education for all the universities across the country. It examines the content of the Bachelor‘s degree of Education in Teaching English as a Foreign Language (B Ed in TEFL) and Bachelor‘s degree of Arts in Teaching English to Speakers of Other Languages (BA in TESOL) curricula adopted in Cambodian universities on the basis of criteria proposed in current curriculum research. It also investigates the perspectives of Cambodian EFL teachers on the areas of knowledge and skill they need in order to perform their English teaching duties in Cambodia today. The areas of knowledge and skill offered in the current curricula at Cambodian higher education institutions (HEIs), the framework of the knowledge base for EFL teacher education and general higher education, and the areas of knowledge and skill Cambodian EFL teachers perceive to be important, are compared so as to identify any gaps in the current English language teacher education curricula in the Cambodian HEIs. The existence of gaps show what domains of knowledge and skill need to be included in the English language teacher education curricula at Cambodian HEIs. These domains are those identified by previous curriculum researchers in both general and English language teacher education at tertiary level. Therefore, the present study provides useful insights into the importance of including appropriate content in English language teacher education curricula. Mixed methods are employed in this study. The course syllabi and the descriptions within the curricula in five Cambodian HEIs are analysed qualitatively based on the framework of knowledge and skills for EFL teachers, which is formed by looking at the knowledge base for second language teachers suggested by the methodologists and curriculum specialists whose work is elaborated on the review of literature. A quantitative method is applied to analyse the perspectives of 120 Cambodian EFL teachers on areas of knowledge and skills they should possess. The fieldwork was conducted between June and August, 2014. The analysis reveals that the following areas are included in the curricula at the five universities: communication skills, general knowledge, knowledge of teaching theories, teaching skills, pedagogical reasoning and decision making skills, subject matter knowledge, contextual knowledge, cognitive abilities, and knowledge of social issues. Additionally, research skills are included in three curricula while society and community involvement is in only one. Further, information and communication technology, which is outlined in the Education Strategies Plan (2006-2010), forms part of four curricula while leadership skills form part of two. This study demonstrates ultimately that most domains that are directly and indirectly related to language teaching competence are not sufficiently represented in the current curricula. On the basis of its findings, the study concludes with a set of guidelines that should inform the design and development of TESOL and TEFL curricula in Cambodia.

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Three experiments explore the hypothesis that due to linguistic and cultural factors, metaphor usage – or thinking in terms of what something is like – differs across cultures. In Experiment 1, a lexical decision task supported the hypothesis that perception of what something is like tends to be faster and more automatic in Latino participants than in Anglo participants. In Experiment 2, Anglo participants were less able to solve a problem framed metaphorically than Latino participants were. To ensure that a preference for metaphor is not applicable to all bilingual populations, we included bilingual Asian participants in Experiment 3. In this study, Latino participants rated arguments presented with metaphors as more persuasive than arguments that did not have metaphors, while the opposite pattern was found in Anglo and Asian participants. The findings from these three studies provide support for the hypothesis that the Latino preference for metaphor is real and pervasive. Implications in the domains of education and public health interventions are briefly noted.

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By providing vehicle-to-vehicle and vehicle-to-infrastructure wireless communications, vehicular ad hoc networks (VANETs), also known as the “networks on wheels”, can greatly enhance traffic safety, traffic efficiency and driving experience for intelligent transportation system (ITS). However, the unique features of VANETs, such as high mobility and uneven distribution of vehicular nodes, impose critical challenges of high efficiency and reliability for the implementation of VANETs. This dissertation is motivated by the great application potentials of VANETs in the design of efficient in-network data processing and dissemination. Considering the significance of message aggregation, data dissemination and data collection, this dissertation research targets at enhancing the traffic safety and traffic efficiency, as well as developing novel commercial applications, based on VANETs, following four aspects: 1) accurate and efficient message aggregation to detect on-road safety relevant events, 2) reliable data dissemination to reliably notify remote vehicles, 3) efficient and reliable spatial data collection from vehicular sensors, and 4) novel promising applications to exploit the commercial potentials of VANETs. Specifically, to enable cooperative detection of safety relevant events on the roads, the structure-less message aggregation (SLMA) scheme is proposed to improve communication efficiency and message accuracy. The scheme of relative position based message dissemination (RPB-MD) is proposed to reliably and efficiently disseminate messages to all intended vehicles in the zone-of-relevance in varying traffic density. Due to numerous vehicular sensor data available based on VANETs, the scheme of compressive sampling based data collection (CS-DC) is proposed to efficiently collect the spatial relevance data in a large scale, especially in the dense traffic. In addition, with novel and efficient solutions proposed for the application specific issues of data dissemination and data collection, several appealing value-added applications for VANETs are developed to exploit the commercial potentials of VANETs, namely general purpose automatic survey (GPAS), VANET-based ambient ad dissemination (VAAD) and VANET based vehicle performance monitoring and analysis (VehicleView). Thus, by improving the efficiency and reliability in in-network data processing and dissemination, including message aggregation, data dissemination and data collection, together with the development of novel promising applications, this dissertation will help push VANETs further to the stage of massive deployment.

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DEA models have been applied as the benchmarking tool in operations management to empirically account operational and productive efficiency. The wide flexibility in assigning the weights in DEA approach can result on indicators of efficiency who do not take account the relative importance of some inputs. In order to overcome this limitation, in this research we apply the DEA model under restricted weight specification. This model is applied to Spanish hotel companies in order to measure operational efficiency. The restricted weight specification enables us to decrease the influence of assigning unrealistic weights in some units and improve the efficiency estimation and to increase the discriminating potential of the conventional DEA model.

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This master's thesis investigates different aspects of Dual-Active-Bridge (DAB) Converter and extends aspects further to Multi-Active-Bridges (MAB). The thesis starts with an overview of the applications of the DAB and MAB and their importance. The analytical part of the thesis includes the derivation of the peak and RMS currents, which is required for finding the losses present in the system. The power converters, considered in this thesis are DAB, Triple-Active Bridge (TAB) and Quad-Active Bridge (QAB). All the theoretical calculations are compared with the simulation results from PLECS software for identifying the correctness of the reviewed and developed theory. The Hardware-in-the-Loop (HIL) simulation is conducted for checking the control operation in real-time with the help of the RT box from the Plexim. Additionally, as in real systems digital signal processor (DSP), system-on-chip or field programmable gate array is employed for the control of the power electronic systems, and the execution of the control in the real-time simulation (RTS) conducted is performed by DSP.

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There is an increased interest in constructing Pre-Cast (PC) Twin and Triple Reinforced Concrete Box (RCB) culverts in Iowa due to the efficiency associated with their production in controlled environment and decrease of the construction time at the culvert sites. The design of the multi-barrel PC culverts is, however, based on guidelines for single-barrel cast-inplace (CIP) culverts despite that the PC and CIP culverts have different geometry. There is scarce information for multiplebarrel RCB culverts in general and even fewer on culverts with straight wingwalls as those designed by Iowa DOT. Overall, the transition from CIP to PC culverts requires additional information for improving the design specifications currently in use. Motivated by the need to fill these gaps, an experimental study was undertaken by IIHR-Hydroscience & Engineering. The goals of the study are to document flow performance curves and head losses at the culvert entrance for a various culvert geometry, flow conditions, and settings. The tests included single-, double- and triple-barrel PC and CIP culverts with two span-to-rise ratios set on mild and steep slopes. The tests also included optimization of the culvert geometry entrance by considering various configurations for the top bevel. The overall conclusion of the study is that by and large the current Iowa DOT design specifications for CIP culverts can be used for multi-barrel PC culvert design. For unsubmerged flow conditions the difference in the hydraulic performance curves and headloss coefficients for PC and CIP culverts are within the experimental uncertainty. Larger differences (specified by the study) are found for submerged conditions when the flow is increasingly constricted at the entrance in the culvert. The observed differentiation is less important for multi-barrel culverts as the influence of the wingwalls decreases with the increase of the number of barrels.