906 resultados para Smart material systems


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Federal Transit Administration, Washington, D.C.

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Because the use of filters to sample particulate matter suspended in the upper atmosphere has been investigated and has yielded rather disappointing results, an examination of other methods of upper atmospheric sampling is desirable, and this is the aim of the present report. The nature of any radioactive material, and its relation to the size and composition of the suspended particles is of particular interest.

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Federal Transit Administration, Washington, D.C.

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National Highway Traffic Safety Administration, Office of Research and Development, Washington, D.C.

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Federal Transit Administration, Washington, D.C.

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National Highway Traffic Safety Administration, Office of Research and Development, Washington, D.C.

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"HRDI-04/08-05(1M)E"--P. [4] of cover.

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"Final report for period 1 August 1972 to 30 September 1976."

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Includes bibliographies.

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Layered lithium-vanadium oxide with a composition of LixVyO2 (x = 0.86 and y = 0.8) was prepared by the hydrothermal reaction of V2O3 with LiOH center dot H2O at 180 degrees C. This material corresponds to a layered rhombohedral structure related to alpha-NaFeO2 in which the vanadium ions are disordered in alternate layers of octahedral 3a (0, 0, 0) and 3b (0, 0, 1/2) sites. The electrochemical properties of this Li0.86V0.8O2 material were investigated and compared with those of the layered Li0.96VO2 made by the conventional solid-state reaction. It was found that the electrochemical capacity and reversibility of the Li0.86V0.8O2 material are significantly improved compared to those of the Li0.96VO2 material; the reversible specific capacities of the Li/Li0.86V0.8O2 and Li/Li0.96VO2 systems are similar to 100 and similar to 50 mAh g(-1), respectively, under the current densities of 7.14 mA g(-1) over 20 charge-discharge cycles with a potential window of 1.50-4.50 V. Such a reversibility results from the structural stability of Li0.86V0.8O2, whereas the increase in the reversible specific capacity can be qualitatively interpreted in terms of the presence of vanadium vacancies in the structure. (c) 2005 The Electrochemical Society.

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The amplification of demand variation up a supply chain widely termed ‘the Bullwhip Effect’ is disruptive, costly and something that supply chain management generally seeks to minimise. Originally attributed to poor system design; deficiencies in policies, organisation structure and delays in material and information flow all lead to sub-optimal reorder point calculation. It has since been attributed to exogenous random factors such as: uncertainties in demand, supply and distribution lead time but these causes are not exclusive as academic and operational studies since have shown that orders and/or inventories can exhibit significant variability even if customer demand and lead time are deterministic. This increase in the range of possible causes of dynamic behaviour indicates that our understanding of the phenomenon is far from complete. One possible, yet previously unexplored, factor that may influence dynamic behaviour in supply chains is the application and operation of supply chain performance measures. Organisations monitoring and responding to their adopted key performance metrics will make operational changes and this action may influence the level of dynamics within the supply chain, possibly degrading the performance of the very system they were intended to measure. In order to explore this a plausible abstraction of the operational responses to the Supply Chain Council’s SCOR® (Supply Chain Operations Reference) model was incorporated into a classic Beer Game distribution representation, using the dynamic discrete event simulation software Simul8. During the simulation the five SCOR Supply Chain Performance Attributes: Reliability, Responsiveness, Flexibility, Cost and Utilisation were continuously monitored and compared to established targets. Operational adjustments to the; reorder point, transportation modes and production capacity (where appropriate) for three independent supply chain roles were made and the degree of dynamic behaviour in the Supply Chain measured, using the ratio of the standard deviation of upstream demand relative to the standard deviation of the downstream demand. Factors employed to build the detailed model include: variable retail demand, order transmission, transportation delays, production delays, capacity constraints demand multipliers and demand averaging periods. Five dimensions of supply chain performance were monitored independently in three autonomous supply chain roles and operational settings adjusted accordingly. Uniqueness of this research stems from the application of the five SCOR performance attributes with modelled operational responses in a dynamic discrete event simulation model. This project makes its primary contribution to knowledge by measuring the impact, on supply chain dynamics, of applying a representative performance measurement system.

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This thesis deals with the problematic of the business systems systemic purpose definition. The definition of the systemic purpose, which is regarded as the utmost expression of the system's purposefulness, is to be achieved by ensuring the participation of all the stakeholders, if possible, who affect or they are affected by the business system's operations. The nature of participation, defined as a process of the stakeholders' perceptual exchanges, is deemed to be problematic in itself due to the influence exerted upon it by organisational power, coercion and false consciousness. The main focus of the thesis then is to make aware and provide the stakeholders with an explicit philosophical pedestal and a set of principles upon which a meta- epistemological framework for the enquiry of the business system's purposeful behaviour is developed. In addition, the thesis focuses on the development of a methodology that can be used by the stakeholders to achieve self-knowledge through the critical and systemic examination of their normative presuppositions, about the business system, at both sociological as well as the psychological levels concurrently and the subsequent development of an organisational intrinsically motivated information system. According to the critical systems philosophy and principles, developed in this thesis, normative presuppositions define the stakeholders' perceptions about the purposeful behaviour of the business system they perceived as having a material, an informational and/or an emacipatory stake (human interest) in. The methodology will provide Information Systems that demonstrably improve coordination of organisational activities by enabling the development and maintenance of a single/multifaceted view of purpose throughout organisations.

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The survival of organisations, especially SMEs, depends, to the greatest extent, on those who supply them with the required material input. This is because if the supplier fails to deliver the right materials at the right time and place, and at the right price, then the recipient organisation is bound to fail in its obligations to satisfy the needs of its customers, and to stay in business. Hence, the task of choosing a supplier(s) from a list of vendors, that an organisation will trust with its very existence, is not an easy one. This project investigated how purchasing personnel in organisations solve the problem of vendor selection. The investigation went further to ascertain whether an Expert Systems model could be developed and used as a plausible solution to the problem. An extensive literature review indicated that very scanty research has been conducted in the area of Expert Systems for Vendor Selection, whereas many research theories in expert systems and in purchasing and supply management chain, respectively, had been reported. A survey questionnaire was designed and circulated to people in the industries who actually perform the vendor selection tasks. Analysis of the collected data confirmed the various factors which are considered during the selection process, and established the order in which those factors are ranked. Five of the factors, namely, Production Methods Used, Vendors Financial Background, Manufacturing Capacity, Size of Vendor Organisations, and Suppliers Position in the Industry; appeared to have similar patterns in the way organisations ranked them. These patterns suggested that the bigger the organisation, the more importantly they regarded the above factors. Further investigations revealed that respondents agreed that the most important factors were: Product Quality, Product Price and Delivery Date. The most apparent pattern was observed for the Vendors Financial Background. This generated curiosity which led to the design and development of a prototype expert system for assessing the financial profile of a potential supplier(s). This prototype was called ESfNS. It determines whether a prospective supplier(s) has good financial background or not. ESNS was tested by the potential users who then confirmed that expert systems have great prospects and commercial viability in the domain for solving vendor selection problems.