Switching characteristics of diamond-based m-i-p+ diodes in power electronic applications

Modeling and numerical analysis of diamond m-i-p+ diode have been performed for static and transient analysis using TCAD Sentaurus platform. The simulation results are compared with experimental measurements. Prediction of transient turn-off characteristics of diamond m-i-p+ diode at high temperature is performed for the first time. It was found that unlike conventional Si diode, peak reverse current in diamond m-i-p+ diode reduces with increasing temperature while on-state voltage drop increases. © 2011 IEEE.

软件属性保障中的源代码静态分析技术研究

随着硬件性能的不断提升，计算机正在被赋予越来越艰巨的任务，运行其上的软件作为沟通人类思维和底层硬件的桥梁，其重要性日益增加。与此同时，软件系统的规模也在不断变大，所涉及的逻辑也更为复杂，这导致开发人员难免会由于疏漏在软件设计实现的过程中引入缺陷、埋下隐患。所以,如何检验、确保软件的属性就成为时下一个亟待解决的热点问题。而在此背景下，源代码静态分析技术由于恰好可以弥补现有测试方法的不足，已经开始在这一研究领域崭露头角。有鉴于此，本文为了推进安全信息系统的研发，分别围绕源代码静态分析技术在软件属性保障中两个最主要的应用场景展开研究，涉及高等级安全操作系统开发过程中的源代码自动化审计，以及分布式信息系统中平台间互信建立时针对软件属性所进行的远程验证，其中，前者是为从深度上将现有安全操作系统向更高等级推进提供助力，而后者是为了从广度上将信息安全领域现有的围绕单机平台的研究成果向分布式架构推广建立基础。具体来说，本文选择针对编程接口规范的一致性检验和应用静态分析的软件属性远程验证作为研究的切入点，探讨了应用源代码静态分析技术检验、确保软件属性的方法和用途，主要取得以下几个方面的成果： 第一，本文给出了一个基于值等价类的别名分析方法。该方法依据相关的传值操作维护一个值等价类空间，可以在编程接口规范一致性检验的过程中按需推导变量符号间的等值关系，不仅有能力支持上下文相关、路径相关的全局分析，还可以有效应对C代码中因结构、指针等构件所衍生出来的大量变量符号。 第二，针对大部分现有代码静态分析工具分析规模受限的问题，本文围绕编程接口规范的一致性检验给出了可以与别名分析有效结合的性能优化方案。该方案不仅能通过剔除与分析无关的执行分支和引入缓存机制提高分析效率，还可以尽量确保分析的准确性少受影响。 第三，我们设计、实现了一个C代码静态分析工具ABAZER（A Bug AnalyZER）。该工具可以依据用户使用有限自动机模型描述的编程接口规范，对操作系统内核级别的软件进行全局分析，指出代码中可能有悖于规范的部分。我们使用ABAZER实际考查了FreeBSD内核中锁机制以及GCC 4.x中库GNU Libiberty的使用情况，从中发现了若干真实的缺陷。 第四，本文针对现有应用可信计算技术、基于完整性信息进行远程验证的方案在灵活性和实用性上所存在的不足，给出一个扩展方案。该方案通过引入虚拟机技术，在软件构建过程中收集举证信息，应用静态分析方法分析软件功能模块间的相关性，划分出与验证相关的模块，有效控制用户定制软件验证时所要依赖的可信列表的规模，使其有能力适应当今网络环境中的大量异质平台和各种安全需求。此外，它还可以为自身所依赖的可信计算基的替换和更新提供支持。 第五，本文针对Flask架构的特点，给出了一个既能检验强制访问控制实现正确性，又能最大限度保留软件灵活性、使得用户可以在一定程度上对软件进行定制的远程验证方案。该方案依赖源代码静态分析技术界定软件中无需基于完整性进行验证的模块，在进一步缩减可信列表规模的同时，使用代码改写技术在这些模块中自动化地插入监控代码约束软件的动态行为，以达到确保强制访问控制实现正确性的目的。该方案初步展现了源代码静态分析技术在远程验证中广阔的应用前景。

3自由度并联柔索驱动变刚度操作臂的刚度控制

利用柔索的弹性及驱动冗余性构造了一种3自由度并联柔索驱动变刚度操作臂,在静力学与刚度分析的基础上,进行刚度控制研究。首先,将柔索驱动力映射到关节空间,并分析等效关节力与柔索张力和外力的关系, 提出该操作臂的三维力矢量闭合原理。根据微分变换原理进行刚度分析,得到关节刚度矩阵及操作手刚度矩阵, 并进行数值算例分析,结果表明:刚度与柔索的张力有关,调节柔索张力可以改变系统刚度。最后,采用位置与张力混合控制的策略,对该变刚度操作臂进行了刚度控制,并进行了仿真验证。

An Efficient Correspondence Based Algorithm for 2D and 3D Model Based Recognition

A polynomial time algorithm (pruned correspondence search, PCS) with good average case performance for solving a wide class of geometric maximal matching problems, including the problem of recognizing 3D objects from a single 2D image, is presented. Efficient verification algorithms, based on a linear representation of location constraints, are given for the case of affine transformations among vector spaces and for the case of rigid 2D and 3D transformations with scale. Some preliminary experiments suggest that PCS is a practical algorithm. Its similarity to existing correspondence based algorithms means that a number of existing techniques for speedup can be incorporated into PCS to improve its performance.

Crafting analytical tools to study institutional change

Most powerful analytical tools used in the social sciences are well suited for studying static situations. Static and mechanistic analysis, however, is not adequate to understand the changing world in which we live. In order to adequately address the most pressing social and environmental challenges looming ahead, we need to develop analytical tools for analyzing dynamic situations -particularly institutional change. In this paper, we develop an analytical tool to study institutional change, more specifically, the evolution of rules and norms. We believe that in order for such an analytical tool to be useful to develop a general theory of institutional change, it needs to enable the analyst to concisely record the processes of change in multiple specific settings so that lessons from such settings can eventually be integrated into a more general predictive theory of change. Copyright © The JOIE Foundation 2010.

Batching decisions for assembly production systems

The two-stage assembly scheduling problem is a model for production processes that involve the assembly of final or intermediate products from basic components. In our model, there are m machines at the first stage that work in parallel, and each produces a component of a job. When all components of a job are ready, an assembly machine at the second stage completes the job by assembling the components. We study problems with the objective of minimizing the makespan, under two different types of batching that occur in some manufacturing environments. For one type, the time to process a batch on a machine is equal to the maximum of the processing times of its operations. For the other type, the batch processing time is defined as the sum of the processing times of its operations, and a setup time is required on a machine before each batch. For both models, we assume a batch availability policy, i.e., the completion times of the operations in a batch are defined to be equal to the batch completion time. We provide a fairly comprehensive complexity classification of the problems under the first type of batching, and we present a heuristic and its worst-case analysis under the second type of batching.

An exploratory study of Principal Investigator roles in UK University Proof-of-Concept processes: an Absorptive capacity perspective

The increasing emphasis on academic entrepreneurship, technology transfer and research commercialisation within UK universities is predicated on basic research being developed by academics into commercial entities such as university spin-off companies or licensing arrangements. However, this process is fraught with challenges and risks, given the degree of uncertainty regarding future returns. In an attempt to minimise such risks, the Proof-of-Concept (PoC) process has been developed within University Science Park Incubators (USIs) to test the technological, business and market potential of embryonic technology. The key or the pivotal stakeholder within the PoC is the Principal Investigator (PI), who is usually the lead academic responsible for the embryonic technology. Within the current literature, there appears to be a lack of research pertaining to the role of the PI in the PoC process. Moreover, Absorptive Capacity (ACAP) has emerged within the literature as a theoretical framework or lens for exploring the development and application of new knowledge and technology, where the USI is the organisation considered in the current study. Therefore, the aim of this paper is to explore the role and influence of the PI in the PoC process within a USI setting using an ACAP perspective. The research involved a multiple case analysis of PoC applications within a UK university USI. The results demonstrate the role of the PI in developing practices and routines within the PoC process. These practices and processes were initially tacit and informal in nature but became more explicit and formal over time so that knowledge was retained within the USI after the PIs had completed the PoC process. © 2010 The Authors. R&D Management © 2010 Blackwell Publishing Ltd.

Impact of operator experience on information feedback and reusability

Keeping a record of operator experience remains a challenge to operation management and a major source of inefficiency in information management. The objective is to develop a framework that enables an explicit presentation of experience based on information use. A purposive sampling method is used to select four small and medium-sized enterprises as case studies. The unit of analysis is the production process in the machine shop. Data collection is by structured interview, observation and documentation. A comparative case analysis is applied. The findings suggest experience is an accumulation of tacit information feedback, which can be made explicit in information use interoperatability matrix. The matrix is conditioned upon information use typology, which is strategic in waste reduction. The limitations include difficulty of participant anonymity where the organisation nominates a participant. Areas for further research include application of the concepts to knowledge management and shop floor resource management.

Inference and Declaration of Independence in Task-Parallel Programs

The inherent difficulty of thread-based shared-memory programming has recently motivated research in high-level, task-parallel programming models. Recent advances of Task-Parallel models add implicit synchronization, where the system automatically detects and satisfies data dependencies among spawned tasks. However, dynamic dependence analysis incurs significant runtime overheads, because the runtime must track task resources and use this information to schedule tasks while avoiding conflicts and races.
We present SCOOP, a compiler that effectively integrates static and dynamic analysis in code generation. SCOOP combines context-sensitive points-to, control-flow, escape, and effect analyses to remove redundant dependence checks at runtime. Our static analysis can work in combination with existing dynamic analyses and task-parallel runtimes that use annotations to specify tasks and their memory footprints. We use our static dependence analysis to detect non-conflicting tasks and an existing dynamic analysis to handle the remaining dependencies. We evaluate the resulting hybrid dependence analysis on a set of task-parallel programs.

Landmark Cases in Property Law

This book explores the development of basic principles of property law in leading cases. Each paper considers a case on land, personal property or intangibles, discussing what that case contributes to the dominant themes of property jurisprudence - how are property rights acquired? What is the content of property rights? What are the limits or boundaries of property? How are property rights extinguished? Individually and collectively, the papers identify a number of important themes for the doctrinal development of property institutions and their broader justification. These themes include: the obscure and incremental development of seemingly foundational principles, the role of instrumentalism in property reasoning, the influence of the law of tort on the scope of property doctrines, and the impact of Roman legal reasoning on the common law of property. One or more of these themes (and others) is revealed through careful case analysis in each paper and they are collected and critically explored in the editors' introduction. This makes for a coherent and provocative collection.

Application of disturbance management principles in fresh food supply chains

The desire for more robust supply chains has led to a growth in theoretical and practical interest in the application of both preventive and impact reductive disturbance management principles. This application should ultimately lead to less vulnerable and more competitive supply chains. Based on the extant literature we identify fresh food supply chain's contextual factors (products, processes, supply chain networks and supply chain business environment) and their corresponding characteristics, as well as the main disturbance management principles used. To analyse their influence on the selection and application of disturbance management principles in fresh food supply chains we conducted three case studies. In each case we collected data on the relevant contextual factors, disturbance management principles applied and company background. As an underlying methodology, we first conduct within-case analysis and then expand the analyses to a cross-case context. Based on the findings from these case studies, propositions are built concerning the nature of contextual factors and their characteristics, and their influence on the selection and application of disturbance management principles in fresh food supply chains. Our main findings are related to the identification of contextual characteristics of fresh food supply chains that are either critical vulnerability sources, critical enablers or conditionals and as such require, facilitate or condition selection and application of disturbance management principles.

Realistic evaluation of EWS and ALERT: factors enabling and constraining implementation.

Realistic Evaluation of EWS and ALERT: factors enabling and constraining implementation Background The implementation of EWS and ALERT in practice is essential to the success of Rapid Response Systems but is dependent upon nurses utilising EWS protocols and applying ALERT best practice guidelines. To date there is limited evidence on the effectiveness of EWS or ALERT as research has primarily focused on measuring patient outcomes (cardiac arrests, ICU admissions) following the implementation of a Rapid Response Team. Complex interventions in healthcare aimed at changing service delivery and related behaviour of health professionals require a different research approach to evaluate the evidence. To understand how and why EWS and ALERT work, or might not work, research needs to consider the social, cultural and organisational influences that will impact on successful implementation in practice. This requires a research approach that considers both the processes and outcomes of complex interventions, such as EWS and ALERT, implemented in practice. Realistic Evaluation is such an approach and was used to explain the factors that enable and constrain the implementation of EWS and ALERT in practice [1]. Aim The aim of this study was to evaluate factors that enabled and constrained the implementation and service delivery of early warnings systems (EWS) and ALERT in practice in order to provide direction for enabling their success and sustainability. Methods The research design was a multiple case study approach of four wards in two hospitals in Northern Ireland. It followed the principles of realist evaluation research which allowed empirical data to be gathered to test and refine RRS programme theory. This approach used a variety of mixed methods to test the programme theories including individual and focus group interviews, observation and documentary analysis in a two stage process. A purposive sample of 75 key informants participated in individual and focus group interviews. Observation and documentary analysis of EWS compliance data and ALERT training records provided further evidence to support or refute the interview findings. Data was analysed using NVIVO8 to categorise interview findings and SPSS for ALERT documentary data. These findings were further synthesised by undertaking a within and cross case comparison to explain the factors enabling and constraining EWS and ALERT. Results A cross case analysis highlighted similarities, differences and factors enabling or constraining successful implementation across the case study sites. Findings showed that personal (confidence; clinical judgement; personality), social (ward leadership; communication), organisational (workload and staffing issues; pressure from managers to complete EWS audit and targets), educational (constraints on training; no clinical educator on ward) and cultural (routine task delegated) influences impact on EWS and acute care training outcomes. There were also differences noted between medical and surgical wards across both case sites. Conclusions Realist Evaluation allows refinement and development of the RRS programme theory to explain the realities of practice. These refined RRS programme theories are capable of informing the planning of future service provision and provide direction for enabling their success and sustainability. References: 1. McGaughey J, Blackwood B, O’Halloran P, Trinder T. J. & Porter S. (2010) A realistic evaluation of Track and Trigger systems and acute care training for early recognition and management of deteriorating ward–based patients. Journal of Advanced Nursing 66 (4), 923-932. Type of submission: Concurrent session Source of funding: Sandra Ryan Fellowship funded by the School of Nursing & Midwifery, Queen’s University of Belfast

Situated regional university incubation: A multi-level stakeholder perspective

From a macro perspective, it is widely acknowledged that University incubation models within a region are important stimulants of economic development through innovation and job creation. With the emergence of quadruple helix innovation ecosystems, universities have had re-evaluate their University incubation activity and models to engage more fully with industry and end users. However, within a given region, the type of University may influence their ability to engage with quadruple helix stakeholders and consequently impact their incubation activity. To date there is a scarcity of research which explores this 'meso' environment and its subsequent impact on University incubation models. Therefore, the aim of this paper is to use a stakeholder lens to explore University Incubation models within unique regional and organisational characteristics and constraints. The research methodology employed was based on a comparative case analysis of incubation of two different Universities within a UK peripheral region. It was found that variances existed in relation to the two universities incubation models which were found to result from both regional (macro environment) and organisational (meso environment) influences (i.e. university type). This research contributes to both regional and national agendas by empirically illustrating the need for appropriate design and tailoring of university incubation models (via acknowledgement of quadruple helix stakeholder influence) to incorporate contextual influences rather than adopting a best practise approach.

Avaliação da gestão curricular da matemática : cursos profissionais III

No mundo do trabalho, designadamente na indústria, acentua-se o défice de competências matemáticas nos profissionais da indústria, particularmente a Modelação Matemática, facto que constitui uma preocupação crescente à escala mundial e, obviamente, do sistema educativo português e da comunidade matemática nacional. Este défice é justificado pela falta de formação dos professores em contexto industrial e, de acordo com a National Council of Teachers of Mathematics, pela incapacidade que muitos docentes têm em apresentar a Matemática aplicada a situações laborais. Face à relevância social, económica e política da problemática descrita, centrou-se o presente estudo na Avaliação da Gestão Curricular da Matemática nos Cursos Profissionais de nível III do ensino secundário em Portugal, com enfoque na Modelação Matemática que, segundo os referentes internacionais, é simultaneamente uma competência e uma metodologia de ensino promotora do desenvolvimento de competências matemáticas nos profissionais da indústria. No contexto da gestão do currículo da Matemática para os cursos profissionais de nível III em escolas secundárias portuguesas, desenvolveu-se o presente estudo para se responder à questão de investigação: Em que medida a gestão curricular da Matemática, instituída, intencional e implementada nos cursos profissionais de nível III contempla situações-problema, suscetíveis de promover o desenvolvimento de competências no aluno, relevantes para o seu desempenho profissional? Construiu-se um referencial de avaliação, centrado na dimensão ecológica, segundo o modelo teórico Enfoque Ontosemiótico, abarcando um conjunto de sub-dimensões sobre as quais foram definidos critérios e respetivos indicadores. De realçar, ainda, que o referencial, além de ter servido de instrumento de avaliação da gestão curricular da Matemática nos cursos profissionais de nível III do ensino secundário, serviu, também, como guia orientador no desenho das sete situações-problema de natureza de Modelação Matemática no estudo de funções. O enquadramento metodológico do presente estudo assentou no método Estudo de Caso. Para analisar o caso, selecionaram-se sete unidades integradas de análise, a saber: a gestão curricular da Matemática de cada um dos seis professores participantes e a gestão curricular da Matemática instituída pelos normativos oficiais (programa da componente de formação científica da disciplina de Matemática para os cursos profissionais). Para a análise dos dados empíricos, respeitantes à gestão instituída, recorreuse à análise de conteúdo e teve essencialmente como propósito avaliar em que medida as orientações curriculares, emanadas no Programa da componente de formação científica disciplina de Matemática para os cursos profissionais de nível III, estão em conformidade com os referenciais teóricos. Sequencialmente, a operacionalização da avaliação intencional consubstanciou-se nos planos das aulas cedidos previamente a cada observação. A análise de conteúdo, como técnica de tratamento dos dados empíricos, foi a forma de se aceder às intenções de cada professor participante no estudo. A observação de aulas sucedeu à avaliação do plano de aula, constituindo a forma de avaliar in loco a gestão curricular da Matemática implementada, permitindo avaliar a coerência das observações com as intenções expressas nas planificações. Os registos das observações foram concretizados sob a forma de notas de campo que incluem uma componente descritiva e outra reflexiva que se dirigem para a análise dos dados empíricos recolhidos. Em termos de resultados, a avaliação da gestão curricular instituída foi reveladora de que o postulado pelos referentes para o desenvolvimento de competências tem a sua representação nas orientações curriculares expressas no Programa da componente de formação científica da disciplina de Matemática para os cursos profissionais de nível III. Contrariamente, a gestão curricular da Matemática pelos professores participantes revelou-se muito condicionada ao cumprimento dos conteúdos propostos pelo programa da disciplina. Por conseguinte, a gestão curricular da Matemática por competências, enfatizada no Programa (gestão instituída), encontrou, neste estudo, pouca tradução na gestão curricular intencional e implementada dos professores participantes, na medida em que a mesma não refletiu uma articulação com a componente de formação técnica do curso, visando uma metodologia proactiva no desenho de situações-problema promotoras de desenvolver, nos alunos, competências profícuas para a sua profissão, nomeadamente a Modelação Matemática. De salientar, ainda, que uma percentagem muito significativa de situações-problema propostas pelos professores não são, no geral, pertinentes para os respetivos cursos, não sendo, neste sentido, promotoras do estabelecimento de ligação com a futura performance profissional dos alunos. Tal lacuna parece ter resultado da ausência de trabalho colaborativo entre os professores de Matemática e os restantes docentes que constituem a equipa formativa do curso, lacuna que dificulta a articulação e coordenação em prol de um ensino contextualizado, ou ainda pela ausência de formação contínua pelos professores, no âmbito de temáticas inerentes à gestão curricular a cursos profissionais.

Assigning real-time tasks on heterogeneous multiprocessors with two unrelated types of processors

A preliminary version of this paper appeared in Proceedings of the 31st IEEE Real-Time Systems Symposium, 2010, pp. 239–248.