8 research outputs found

    Transition Faults and Transition Path Delay Faults: Test Generation, Path Selection, and Built-In Generation of Functional Broadside Tests

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    As the clock frequency and complexity of digital integrated circuits increase rapidly, delay testing is indispensable to guarantee the correct timing behavior of the circuits. In this dissertation, we describe methods developed for three aspects of delay testing in scan-based circuits: test generation, path selection and built-in test generation. We first describe a deterministic broadside test generation procedure for a path delay fault model named the transition path delay fault model, which captures both large and small delay defects. Under this fault model, a path delay fault is detected only if all the individual transition faults along the path are detected by the same test. To reduce the complexity of test generation, sub-procedures with low complexity are applied before a complete branch-and-bound procedure. Next, we describe a method based on static timing analysis to select critical paths for test generation. Logic conditions that are necessary for detecting a path delay fault are considered to refine the accuracy of static timing analysis, using input necessary assignments. Input necessary assignments are input values that must be assigned to detect a fault. The method calculates more accurate path delays, selects paths that are critical during test application, and identifies undetectable path delay faults. These two methods are applicable to off-line test generation. For large circuits with high complexity and frequency, built-in test generation is a cost-effective method for delay testing. For a circuit that is embedded in a larger design, we developed a method for built-in generation of functional broadside tests to avoid excessive power dissipation during test application and the overtesting of delay faults, taking the functional constraints on the primary input sequences of the circuit into consideration. Functional broadside tests are scan-based two-pattern tests for delay faults that create functional operation conditions during test application. To avoid the potential fault coverage loss due to the exclusive use of functional broadside tests, we also developed an optional DFT method based on state holding to improve fault coverage. High delay fault coverage can be achieved by the developed method for benchmark circuits using simple hardware

    A cumulative index to Aeronautical Engineering: A special bibliography

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    This publication is a cumulative index to the abstracts contained in NASA SP-7037 (80) through NASA SP-7037 (91) of Aeronautical Engineering: A Special Bibliography. NASA SP-7037 and its supplements have been compiled through the cooperative efforts of the American Institute of Aeronautics (AIAA) and Space Administration (NASA). This cumulative index includes subject, personal author, corporate source, contract, and report number indexes

    An appraisal of the Poverty Reduction Strategy (PRS) Initiative

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    In late 1999, the World Bank and International Monetary Fund (IMF) jointly launched the Poverty Reduction Strategy (PRS) Initiative, under which low income countries (LICs) would be supported to develop multi-sectoral economic and social development plans. As such, these national PRSs would serve as the effective policy conditionality for concessional lending and the allocation of debt relief. Heralded by many as path breaking, the Initiative refocused attention on the role of the State and identified poverty reduction, as opposed to growth alone, as the primary goal of policy. However, from the outset, PRSs have been controversial. The most trenchant critics have described these plans as merely re-formulated structural adjustment packages. Other, more considered accounts, have questioned whether PRSs’ are capable of overcoming the agency problems inherent to donor-recipient relationships, and their ability to succeed in the weak policy environment typified by most LICs.In spite of the passage of some ten years, a rigorous evaluation of performance has yet to be published. This thesis aims to provide such an appraisal drawing on both quantitative and qualitative evidence. It employs cross-sectional statistical and econometric methods to examine poverty, growth and inequality outcomes based on a specially constructed dataset; and two detailed analytical case studies (for Mongolia and Vietnam) to probe the causal processes.Although some aggregate evidence is found of performance gains (relating to both poverty reduction and growth), these effects are partial and statistically fragile. Moreover, while no direct evidence is found of dis-inflationary policy biases, it is possible to detect a new narrowness within PRS policymaking. This reflects an orthodox policy consensus which favours growth over distributional improvements and places emphasis on a managed liberalization process. Additionally, it proved very difficult to find a causal link been PRS adoption and beneficial outcomes. The case study materials underline the pivotal role played by the IFIs in the design and management of PRSs, and their transitory and limited impact on actual national policy responses. Conclusions support many of the propositions put by the critical literature, and find that PRSs are poorly adapted to local institutional frameworks and neglect national political economies. As a result, their substance and longer term effectiveness is in doubt.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

    The Limits of Legal Evolution: Knowledge and Normativity in Theories of Legal Change

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    Over the last forty years, legal theory and policy advice have come to draw heavily from an ‘evolutionary’ jurisprudence that explains legal transformation by drawing inspiration from the theoretical successes of Darwinian natural selection. This project seeks to enrich and critique this tradition using an analytical perspective that emphasizes the material consequences of concepts and ideas. Existing theories of legal evolution depend on a positivist epistemology that strictly distinguishes the objects of social life — interests, institutions, systems — from knowledge about those objects. My dissertation explores how knowledge, and especially non-legal expertise, acts as an independent site and locus of transformation, mediating the interaction between law and social phenomena and acting as a catalyst of legal innovation. Prior work by Simon Deakin has integrated insights from systems theory to show how the interaction between law and economic institutions can only be properly understood by attending to the epistemic frame law uses to interpret economic practice. Using a case study on the impact of ‘law and finance’ literature on World Bank policy advice and, consequentially, on legal reforms adopted by many developing countries between 2000 and the present, I show that such attention to legal knowledge is inadequate. The case points, first, to the contingency of the intellectual tools used to understand legal institutions. Rather than deploying a determinate rationality, private and public actors address legal, economic, and ethical problems using a variety of paradigms: viewpoints are not determined by realities. More fundamentally, the cases suggest that successful paradigms, rather than economic or political realities alone, shape the dynamics of socio-legal change. My conclusions address some normative questions that arise when researchers in a social scientific mode are implicated in the processes they seek to document

    A multiscale analysis of frictional interaction between human skin and nonwoven fabrics

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    Various hygiene products, notably incontinence pads, bring nonwoven “topsheet” fabrics into contact with individuals’ skin. This contact can damage the skin in various ways, including abrading it by friction, a mechanism enhanced by the presence of moisture. In recent years skin-nonwoven friction has been the subject of significant experimental study in the Continence and Skin Technology Group, UCL, in the course of which methods have been developed which can detect differences in friction between a chosen nonwoven and equivalent skin sites on different individuals under fixed conditions. The reasons for these differences are unknown; their elucidation is one focus of this work. The other is to establish the influence of coarse geometry on the dynamics of a tense nonwoven sheet sliding over a substrate and interacting with it by friction. The first part of this work (“microfriction”) is primarily experimental in nature, and involves two separate experiments. The first involves using a microscope with a shallow depth of field to determine the length of nonwoven fibre in contact with a facing surface as a function of pressure; the second consists of measuring friction between chosen nonwovens and a skin surrogate at a variety of pressures and speeds whilst simultaneously observing the behaviour of the interface down a microscope. Both techniques were extensively validated, and the data from the two experiments were then compared. It had originally been intended to conduct the friction experiment on skin (the other experiment does not require it), and though all equipment was developed with this in mind and all relevant permission was sought and obtained, it was not eventually possible. Instead, a skin friction surrogate (Lorica Soft) established in the literature was used. Data from this show that Amontons’ law (with respect to load) is obeyed to high precision (R2 > 0.999 in all cases), though there is the suggestion of sublinearity at low loads. Detailed consideration of the friction traces suggests that two different friction mechanisms are important, and comparison with the contact data suggests tentatively that they may correspond to adhesion between two different populations of contacts, one “rough” and one “smooth”. Further work applying these techniques to skin is necessary. The second aspect of the work is “geometric friction”; that is, the relationship between the geometry of a surface (on the centimetre scale and upwards) and the friction experienced by a compliant sheet (such as nonwoven topsheet) laid over it in tension. A general equation of motion for slippage between sheet and surface has been derived which in principle allows for both objects to deform and interact according to any plausible friction law. This has then been solved in integral form for Amontons’ law and a low density strip exhibiting no Poisson contraction sliding over any surface with zero Gaussian curvature; closed form solutions for the specific cases of a prism and a circular cone have then been derived and compared. Experimental verification has been provided by a colleague, which shows very good agreement between theory and experiment. It has also been shown that, taking a naïve approach, the classic model for a rigid cylinder can be applied even to a quite extreme cone with experimentally negligible error. NB All prior copyrighted material (diagrams in all cases) has been removed from this edition to facilitate electronic distribution. They have been replaced with boxes of the same size, so pagination is identical with the complete version

    A methodology for topside design and integration in preliminary warship design.

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    This thesis investigates warship topside design and integration and proposes a methodology that provides, during the preliminary design stages, an enhanced topside design capability above that currently available. The feasibility of such a system is demonstrated through a number of individual investigations and ship design studies for both conventional and unconventional naval vessels. A recommended implementation of the methodology, integrating it with the recently produced layout system, is proposed as the way forward. Topside design is a complex task resulting from the requirement to locate all the necessary equipment on the weatherdeck and superstructure of a warship whilst minimising interactions. The current tools and design methodologies fail to cohesively address design issues at the concept stage. This is often due to the specialist nature of the analyses, which require detailed definitions only available later in the design process as well as expert knowledge in the application of the techniques. The proposed methodology provides guidance as different design solutions are developed and evaluated, allowing earlier identification of potential problems. It operates in an 'open' manner providing the naval architect with the flexibility to investigate and analyse the design as it evolves without dictating design decisions or requiring expert application knowledge. The major issues that need to be considered during preliminary warship design are discussed. Current design methods and the shortfalls associated with each of them are considered. A methodology is outlined detailing the principles that are applicable and the important components and characteristics of any solution identified. The major aspects in topside integration are investigated and design tools proposed and evaluated. A framework for the integration of these tools is developed which is suitable for implementation using current computer technology. The suitability of this framework to incorporate other less complex but important topside design issues is evaluated and appropriate techniques identified

    The French-Anglophone divide in lithic research: A plea for pluralism in Palaeolithic Archaeology

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    In this provocative study, Shumon T. Hussain engages with the long-standing issue of French-Anglophone research conflicts in Palaeolithic archaeology. By examining a range of well-selected case studies and discursive contexts, the author shows that French and Anglophone approaches in lithic analysis are anchored in opposing cognitive frameworks. He argues that the mainstays of this division can be elucidated by calling upon the marginalised work of American philosopher Stephen C. Pepper, who captured the totality of credible Western thought in terms of four equitable world hypotheses. Based upon his insights, the dissertation demonstrates that French lithic research gravitates towards ‘contextualistic’ and ‘organicistic’ modes of inquiry, while Anglophone approaches tend to rely on ‘formistic’ and ‘mechanistic’ styles of reasoning. Hussain carefully lays out the implications of this condition for mutual understanding and critical practice. He contends that the French-Anglophone divide can only be overcome if scholars endorse scientific pluralism and begin to seriously take into consideration both the strengths and shortcomings of different cognitive frameworks, including their own. Human Origin
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