35 resultados para Galois extensions of local commutative rings
Resumo:
We describe a polygeneration system that can run on neat plant oils, such as Jatropha and Pongamia, or standard diesel fuel. A prototype has been constructed using a compression ignition engine of 9.9 kW shaft output. It consumes 3 L/h of fuel and will produce 40 kg/h of ice by means of an adsorption refrigerator powered from the engine jacket heat. Steaming of rice, deep and shallow frying, and other types of food preparation heated by the exhaust gas have been demonstrated. In addition, the feasibility of producing distilled water by means of multiple-effect distillation powered by the engine waste heat is shown. Overall plant efficiency and potential savings in greenhouse gas emissions are discussed. © 2012 Elsevier Ltd.
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We show that, with suitable optics in the arm of a Michelson interferometer, orthogonal galvo-scanning mirrors build a sampling function in the form of Newton rings when the two interferometer arms are matched. Using a low-coherence source, one can obtain transversal depth-resolved images. A fast display procedure using a storage oscilloscope was devised based on this method.
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Purpose: Development of effective disaster risk reduction (DRR) strategies for communities at risk of being affected by natural disasters is considered essential, especially in the wake of devastating disaster events reported worldwide. As part of a wider research study investigating community perspectives on existing and potential strategies for enhancing resilience to natural disasters, community perspectives on infrastructure and structural protection requirements were investigated. The paper aims to discuss these issues. Design/methodology/approach: Patuakhali region in South-Western Bangladesh is a region significantly at risk of multiple natural hazards. In order to engage local communities and obtain their perspectives, focus group discussions were held with local community leaders and policy makers of at-risk communities in Patuakhali region, South-Western Bangladesh. Findings: Infrastructure and structural protection requirements highlighted included multi-purpose cyclone shelters, permanent embankments and improved transport infrastructure. Much of the discussions of focus group interviews were focused on cyclone shelters and embankments, suggesting their critical importance in reducing disaster risk and also dependence of coastal communities on those two measures. Originality/value: The research design adopted sought to answer the research questions raised and also to inform local policy makers on community perspectives. Local policy makers involved in DRR initiatives in the region were informed of community perspectives and requirements, thus contributing to community engagement in implementing DRR activities.
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The traditional use of global and centralised control methods, fails for large, complex, noisy and highly connected systems, which typify many real world industrial and commercial systems. This paper provides an efficient bottom up design of distributed control in which many simple components communicate and cooperate to achieve a joint system goal. Each component acts individually so as to maximise personal utility whilst obtaining probabilistic information on the global system merely through local message-passing. This leads to an implied scalable and collective control strategy for complex dynamical systems, without the problems of global centralised control. Robustness is addressed by employing a fully probabilistic design, which can cope with inherent uncertainties, can be implemented adaptively and opens a systematic rich way to information sharing. This paper opens the foreseen direction and inspects the proposed design on a linearised version of coupled map lattice with spatiotemporal chaos. A version close to linear quadratic design gives an initial insight into possible behaviours of such networks.
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We investigate quantum vortex ring dynamics at scales smaller than the inter-vortex spacing in quantum turbulence. Through geometrical arguments and high-resolution numerical simulations, we examine the validity of simple estimates for the mean free path and the structure of vortex rings post-reconnection. We find that a large proportion of vortex rings remain coherent objects where approximately 75% of their energy is preserved. This leads us to consider the effectiveness of energy transport in turbulent tangles. Moreover, we show that in low density tangles, appropriate for the ultra-quantum regime, ring emission cannot be ruled out as an important mechanism for energy dissipation. However at higher vortex line densities, typically associated with the quasi-classical regime, loop emission is expected to make a negligible contribution to energy dissipation, even allowing for the fact that our work shows rings can survive multiple reconnection events. Hence the Kelvin wave cascade seems the most plausible mechanism leading to energy dissipation
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The generative topographic mapping (GTM) model was introduced by Bishop et al. (1998, Neural Comput. 10(1), 215-234) as a probabilistic re- formulation of the self-organizing map (SOM). It offers a number of advantages compared with the standard SOM, and has already been used in a variety of applications. In this paper we report on several extensions of the GTM, including an incremental version of the EM algorithm for estimating the model parameters, the use of local subspace models, extensions to mixed discrete and continuous data, semi-linear models which permit the use of high-dimensional manifolds whilst avoiding computational intractability, Bayesian inference applied to hyper-parameters, and an alternative framework for the GTM based on Gaussian processes. All of these developments directly exploit the probabilistic structure of the GTM, thereby allowing the underlying modelling assumptions to be made explicit. They also highlight the advantages of adopting a consistent probabilistic framework for the formulation of pattern recognition algorithms.
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It is often assumed that foreign MNEs are the driving force behind technological development in developing economies but it has become evident in recent years that the actions of MNEs in isolation from the domestic economy. The study, therefore, examines the determinants of local firms' decisions to undertake technological effort, not only in isolation, but also in the context of linkages between domestic firms and MNEs. There is evidence that linkages between MNEs and local firms are important in explaining technological effort by local firms but direct technological assistance from MNEs does not seem to play a major role in fostering increased technological effort by local firms.
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The way in which employed senior elites in English local government exercise their agency in the practice of local democracy and local governance is considered in this thesis. The research posits the notion that elite Officers act as Local Democracy Makers as they draw on their own traditions and ideologies in responding to the dilemmas of changing policy and politics in the public realm. The study is located in the latter part of New Labour?s term of office and applies an interpretive and reflexive approach to three studies of the exercise of well being powers. The approach is one of applied ethnography through the examination of literature reviews, interviews and observations of decisions taken in the exercise of the powers of economic, environmental and social well-being are used to examine how and why the Local Democracy Makers make sense of their world in the way that they do. The research suggests that, despite prevailing narratives, local governance arrangements depend on a system of hierarchy, employed elites and local politics. The challenges of re-configuring local democracy and attempts at "hollowing out" the state have secured an influential role for the non-elected official. How officials interpret, advise, mediate and manage the exercise of local governance and local democracy presents a challenge to assumptions that public services are governed beyond or without local government. New narratives and reflections on the role of the local government Officer and the marginalisation of the elected Councillor are presented in the research. In particular, how the senior elite occupy managerial, strategic and political roles as Local Democracy Makers, offers an insight into the agency of strategic actors in localities. Consequently, the success of changes in public policy is materially influenced by how the practitioner responds to such dilemmas. The thesis concludes by suggesting that integral to the design and success of public policy implementation is the role of the Officer, and especially those practitioners that advise governing arrangements and democratic practice.
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The pattern of illumination on an undulating surface can be used to infer its 3-D form (shape-from-shading). But the recovery of shape would be invalid if the luminance changes actually arose from changes in reflectance. So how does vision distinguish variation in illumination from variation in reflectance to avoid illusory depth? When a corrugated surface is painted with an albedo texture, the variation in local mean luminance (LM) due to shading is accompanied by a similar modulation in local luminance amplitude (AM). This is not so for reflectance variation, nor for roughly textured surfaces. We used depth mapping and paired comparison methods to show that modulations of local luminance amplitude play a role in the interpretation of shape-from-shading. The shape-from-shading percept was enhanced when LM and AM co-varied (in-phase) and was disrupted when they were out of phase or (to a lesser degree) when AM was absent. The perceptual differences between cue types (in-phase vs out-of-phase) were enhanced when the two cues were present at different orientations within a single image. Our results suggest that when LM and AM co-vary (in-phase) this indicates that the source of variation is illumination (caused by undulations of the surface), rather than surface reflectance. Hence, the congruence of LM and AM is a cue that supports a shape-from-shading interpretation. © 2006 Elsevier Ltd. All rights reserved.
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This research is concerned with the development of distributed real-time systems, in which software is used for the control of concurrent physical processes. These distributed control systems are required to periodically coordinate the operation of several autonomous physical processes, with the property of an atomic action. The implementation of this coordination must be fault-tolerant if the integrity of the system is to be maintained in the presence of processor or communication failures. Commit protocols have been widely used to provide this type of atomicity and ensure consistency in distributed computer systems. The objective of this research is the development of a class of robust commit protocols, applicable to the coordination of distributed real-time control systems. Extended forms of the standard two phase commit protocol, that provides fault-tolerant and real-time behaviour, were developed. Petri nets are used for the design of the distributed controllers, and to embed the commit protocol models within these controller designs. This composition of controller and protocol model allows the analysis of the complete system in a unified manner. A common problem for Petri net based techniques is that of state space explosion, a modular approach to both the design and analysis would help cope with this problem. Although extensions to Petri nets that allow module construction exist, generally the modularisation is restricted to the specification, and analysis must be performed on the (flat) detailed net. The Petri net designs for the type of distributed systems considered in this research are both large and complex. The top down, bottom up and hybrid synthesis techniques that are used to model large systems in Petri nets are considered. A hybrid approach to Petri net design for a restricted class of communicating processes is developed. Designs produced using this hybrid approach are modular and allow re-use of verified modules. In order to use this form of modular analysis, it is necessary to project an equivalent but reduced behaviour on the modules used. These projections conceal events local to modules that are not essential for the purpose of analysis. To generate the external behaviour, each firing sequence of the subnet is replaced by an atomic transition internal to the module, and the firing of these transitions transforms the input and output markings of the module. Thus local events are concealed through the projection of the external behaviour of modules. This hybrid design approach preserves properties of interest, such as boundedness and liveness, while the systematic concealment of local events allows the management of state space. The approach presented in this research is particularly suited to distributed systems, as the underlying communication model is used as the basis for the interconnection of modules in the design procedure. This hybrid approach is applied to Petri net based design and analysis of distributed controllers for two industrial applications that incorporate the robust, real-time commit protocols developed. Temporal Petri nets, which combine Petri nets and temporal logic, are used to capture and verify causal and temporal aspects of the designs in a unified manner.
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The study examines the contribution of the Greens to the changing nature of West Germany's local politics in the 1980s. The changes correspond broadly to the politicisation and parliamentarisation of a sphere of government traditionally perceived as being "unpolitical". Building upon theories of the New Politics, it is suggested that the varying pace of socio-economic change across the Federal Republic underlies the nonuniform development of its local party systems. The party systems of localities which have witnessed rapid social and economic change are found to be more susceptible to the emergence of a New Politics dimension than those of communities in which change has occurred less rapidly. The thesis continues by addressing aspects of the Greens' role in the development of local party systems across the Federal Republic. Despite the fact that marked differences in the Greens' approach to local political participation are registered in communities of varying socio-economic types, it is argued that the Greens are largely responsible for the introduction of a "New Local Politics" dimension into West Germany's local party systems. In a comprehensive study of the Greens' role in the Mainz party system, the conflicting styles and practices of the Greens and the established political parties in the city are depicted. The failure of the Green Party to form an alliance with the SPD in the city council is attributed to the cleavage between the Greens' New Politics and the SPD's Old Politics approaches. A detailed analysis of the parliamentary initiatives introduced by the four parties represented in the Mainz council between 1984 and 1987 also supports the contention that a New Politics dimension exists in the city's party system. This dimension is identified as representing a significant source of conflict during the period of analysis.
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The thesis compares two contrasting strategies employed with the aim of combating particular forms of racism within contemporary Britain. Both are assessed as political strategies in their own right and placed within the broader context of reformist and revolutionary political traditions. The sociology of social movements is examined critically, as are Marxist and post-Marxist writings on the role of human agency within social structures and on the nature of social movements. The history of the Anti Nazi League (ANL) in the late 1970s and its opposition to the National Front is considered as an example of anti-racist social movement based on the Trotskyist model of the United Front. The degree to which the Anti Nazi League corresponded to such a model is analysed as are the potential broader applications for such a strategy. The strategy with which the ANL is compared is the development of anti-racist and equal opportunities policies within local government in the 1980s, primarily by Labour-controlled local authorities. The theory of the local state and the political phenomenon of municipal socialism are discussed, specifically the role of various groups operating in and around local authorities in the formation and implementation of anti-racist policy and practice. Following this general discussion, two case studies in each of the areas of local authority housing, education and employment are explored to consider in depth the problems of specific anti-racist policies. In summation the efficacy of the two strategies are considered as parts of wider political currents in tandem with their declared specific objectives.
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The decade since 1979 has seen the most rapid introduction of microelectronic technology in the workplace. In particular, the scope offered for the application of this new technology to the area of white collar work has meant that it is a sector where trade unions have been confronted with major challenges. However the application of this technology has also provided trade unions with opportunities for exerting influence to reshape traditional attitudes to both industrial relations and the nature of work. Recent academic research on the trade union response to the introduction of new technology at the workplace suggests that, despite the resources and apparent sophistication of modern trade unions, they have not in general been able to take advantage of the opportunities offered during this period of radical technological change,the argument being that this is due both to structural weaknesses and the inappropriateness of the system of collective bargaining where new technology issues are concerned. Despite the significance of the Public Sector in employment terms, research into the response of public sector white collar trade unions to technological change has been fairly limited. This thesis sets out the approach of the National and Local Government Officers Association (NALGO), the largest solely white collar union in the world with over three quarters of a million members employed in a wide range of public service industries. The thesis examines NALGO's response at national level and, through detailed case studies, at local level in respect of Local Government and Water Industry NALGO members. The response is then evaluated and conclusions drawn in terms of a framework based upon an assessment of the key factors relevant in judging the ability of NALGO to respond effectively to the challenges brought about by the technological revolution of the last ten years.
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The study addresses the introduction of an innovation of new technology into a bureaucratic profession. The organisational setting is that of local authority secondary schools at a time at which microcomputers were being introduced in both the organisational core (for teaching) and its periphery (school administration). The research studies innovation-adopting organisations within their sectoral context; key actors influencing the innovation are identified at the levels of central government, local government and schools.A review of the literature on new technology and innovation (including educational innovation), and on schools as organisations in a changing environment leads to the development of the conceptual framework of the study using a resource dependency model within a cycle of the acquisition, allocation and utilisation of financial, physical and intangible resources. The research methodology is longitudinal and draws from both positivist and interpretive traditions. lt includes an initial census of the two hundred secondary schools in four local education authorities, a final survey of the same population, and four case studies, using both interview methods and documentation. Two modes of innovation are discerned. In respect of administrative use a rationalising, controlling mode is identified, with local education authorities developing standardised computer-assisted administrative systems for use in schools. In respect of curricular use, in contrast, teachers have been able to maintain an indeterminate occupational knowledge base, derived from an ideology of professionalism in respect of the classroom use of the technology. The mode of innovation in respect of curricular use has been one of learning and enabling. The resourcing policies of central and local government agencies affect the extent of use of the technology for teaching purposes, but the way in which it is used is determined within individual schools, where staff with relevant technical expertise significantly affect the course of the innovation.