3,712 research outputs found

    A sequential real-time refinement calculus

    Get PDF
    We present a comprehensive refinement calculus for the development of sequential, real-time programs from real-time specifications. A specification may include not only execution time limits, but also requirements on the behaviour of outputs over the duration of the execution of the program. The approach allows refinement steps that separate timing constraints and functional requirements. New rules are provided for handling timing constraints, but the refinement of components implementing functional requirements is essentially the same as in the standard refinement calculus. The product of the refinement process is a program in the target programming language extended with timing deadline directives. The extended language is a machine-independent, real-time programming language. To provide valid machine code for a particular model of machine, the machine code produced by a compiler must be analysed to guarantee that it meets the specified timing deadlines

    Mechanising an algebraic rely-guarantee refinement calculus

    Get PDF
    PhD ThesisDespite rely-guarantee (RG) being a well-studied program logic established in the 1980s, it was not until recently that researchers realised that rely and guarantee conditions could be treated as independent programming constructs. This recent reformulation of RG paved the way to algebraic characterisations which have helped to better understand the difficulties that arise in the practical application of this development approach. The primary focus of this thesis is to provide automated tool support for a rely-guarantee refinement calculus proposed by Hayes et. al., where rely and guarantee are defined as independent commands. Our motivation is to investigate the application of an algebraic approach to derive concrete examples using this calculus. In the course of this thesis, we locate and fix a few issues involving the refinement language, its operational semantics and preexisting proofs. Moreover, we extend the refinement calculus of Hayes et. al. to cover indexed parallel composition, non-atomic evaluation of expressions within specifications, and assignment to indexed arrays. These extensions are illustrated via concrete examples. Special attention is given to design decisions that simplify the application of the mechanised theory. For example, we leave part of the design of the expression language on the hands of the user, at the cost of the requiring the user to define the notion of undefinedness for unary and binary operators; and we also formalise a notion of indexed parallelism that is parametric on the type of the indexes, this is done deliberately to simplify the formalisation of algorithms. Additionally, we use stratification to reduce the number of cases in in simulation proofs involving the operational semantics. Finally, we also use the algebra to discuss the role of types in program derivation

    Overcoming the Irrational Land Use in Africa and Other Regions of the World - A Critique to the Myths of Nobel Laureate Schultz and Nominee Hirschman

    Get PDF
    Paper presented at the UNU-WIDER (United Nations University – World Institute for Development Economics Research) Project Conference on African Development: Myths and Realities Accra, Ghana, 10-11 December 2009Land Economics/Use,

    Promoting Agricultural Entrepreneurs against Food Shortage, Overproduction and Protectionism in Northern Africa and Other Regions of the World - A Critique to Nobel Laureate Schultz and Nominee Hirschman

    Get PDF
    Paper presented at the International Conference of 'Entrepreneurship and Land and Rural Development' Faculty of Economic and Management Sciences, University of AbouBekr BELKAID TLEMCEN Tlemcen, Algeria, 3-4 December 2008Agribusiness, International Relations/Trade,

    Monitor Energy Markets 2007 - Analysis of developments on the Dutch wholesale markets for gas and electricity

    Get PDF
    The Dutch wholesale markets for energy are still impeded by various bottlenecks, as a result of which the costs for energy consumers are higher than they should be in well-functioning markets. Simply making more efficient use of the import infrastructure could save energy consumers several tens of millions of euros. The bottlenecks occur primarily in the gas market, where various impediments are impeding the quicker introduction of competition.Monitoring, electricity, gas, competition, infrastructure

    The role of fiscal rules and institutions in shaping budgetary outcomes

    Get PDF
    The Workshop "The role of fiscal rules and institutions in shaping budgetary outcomes" organized by the Directorate-General for Economic and Financial affairs of the European Commission on 24 November 2006 in Brussels aimed at enriching the debate on the fiscal arrangements and improving the understanding of their functioning. This Economic Paper contains all the paper presented in this event that was organised in four sessions. A first set of papers mainly focus on the impact of numerical fiscal rules on budgetary outturns. Other paper deal primarily with the appropriate design of fiscal rules and institutions. An additional group of papers addresses the relationship between the fiscal governance approach adopted by the EU Member States and their institutional and political frameworks. Finally the remaining presentations relate more directly to policy experiences. fiscal rules, budget, institutions.fiscal rules, budget, institutions, Ayuso-i-Casals, Deroose, Flores, Moulin

    Numerical modelling of the fluid-structure interaction in complex vascular geometries

    Get PDF
    A complex network of vessels is responsible for the transportation of blood throughout the body and back to the heart. Fluid mechanics and solid mechanics play a fundamental role in this transport phenomenon and are particularly suited for computer simulations. The latter may contribute to a better comprehension of the physiological processes and mechanisms leading to cardiovascular diseases, which are currently the leading cause of death in the western world. In case these computational models include patient-specific geometries and/or the interaction between the blood flow and the arterial wall, they become challenging to develop and to solve, increasing both the operator time and the computational time. This is especially true when the domain of interest involves vascular pathologies such as a local narrowing (stenosis) or a local dilatation (aneurysm) of the arterial wall. To overcome these issues of high operator times and high computational times when addressing the bio(fluid)mechanics of complex geometries, this PhD thesis focuses on the development of computational strategies which improve the generation and the accuracy of image-based, fluid-structure interaction (FSI) models. First, a robust procedure is introduced for the generation of hexahedral grids, which allows for local grid refinements and automation. Secondly, a straightforward algorithm is developed to obtain the prestress which is implicitly present in the arterial wall of a – by the blood pressure – loaded geometry at the moment of medical image acquisition. Both techniques are validated, applied to relevant cases, and finally integrated into a fluid-structure interaction model of an abdominal mouse aorta, based on in vivo measurements

    Enhancement of the Feature Extraction Capability in Global Damage Detection Using Wavelet Theory

    Get PDF
    The main objective of this study is to assess the specific capabilities of the defect energy parameter technique for global damage detection developed by Saleeb and coworkers. The feature extraction is the most important capability in any damage-detection technique. Features are any parameters extracted from the processed measurement data in order to enhance damage detection. The damage feature extraction capability was studied extensively by analyzing various simulation results. The practical significance in structural health monitoring is that the detection at early stages of small-size defects is always desirable. The amount of changes in the structure's response due to these small defects was determined to show the needed level of accuracy in the experimental methods. The arrangement of fine/extensive sensor network to measure required data for the detection is an "unlimited" ability, but there is a difficulty to place extensive number of sensors on a structure. Therefore, an investigation was conducted using the measurements of coarse sensor network. The white and the pink noises, which cover most of the frequency ranges that are typically encountered in the many measuring devices used (e.g., accelerometers, strain gauges, etc.) are added to the displacements to investigate the effect of noisy measurements in the detection technique. The noisy displacements and the noisy damage parameter values are used to study the signal feature reconstruction using wavelets. The enhancement of the feature extraction capability was successfully achieved by the wavelet theory

    Production Engineering and Management

    Get PDF
    The annual International Conference on Production Engineering and Management takes place for the sixth time his year, and can therefore be considered a well - established event that is the result of the joint effort of the OWL University of Applied Sciences and the University of Trieste. The conference has been established as an annual meeting under the Double Degree Master Program ‘Production Engineering and Management’ by the two partner universities. The main goal of the conference is to provide an opportunity for students, researchers and professionals from Germany, Italy and abroad, to meet and exchange information, discuss experiences, specific practices and technical solutions used in planning, design and management of production and service systems. In addition, the conference is a platform aimed at presenting research projects, introducing young academics to the tradition of Symposiums and promoting the exchange of ideas between the industry and the academy. Especially the contributions of successful graduates of the Double Degree Master Program ‘Production Engineering and Management’ and those of other postgraduate researchers from several European countries have been enforced. This year’s special focus is on Direct Digital Manufacturing in the context of Industry 4.0, a topic of great interest for the global industry. The concept is spreading, but the actual solutions must be presented in order to highlight the practical benefits to industry and customers. Indeed, as Henning Banthien, Secretary General of the German ‘Plattform Industrie 4.0’ project office, has recently remarked, “Industry 4.0 requires a close alliance amongst the private sector, academia, politics and trade unions” in order to be “translated into practice and be implemented now”. PEM 2016 takes place between September 29 and 30, 2016 at the OWL University of Applied Sciences in Lemgo. The program is defined by the Organizing and Scientific Committees and clustered into scientific sessions covering topics of main interest and importance to the participants of the conference. The scientific sessions deal with technical and engineering issues, as well as management topics, and include contributions by researchers from academia and industry. The extended abstracts and full papers of the contributions underwent a double - blind review process. The 24 accepted presentations are assigned, according to their subject, to one of the following sessions: ‘Direct Digital Manufacturing in the Context of Industry 4.0’, ‘Industrial Engineering and Lean Management’, ‘Management Techniques and Methodologies’, ‘Wood Processing Technologies and Furniture Production’ and ‘Innovation Techniques and Methodologies
    • 

    corecore