869,822 research outputs found

    Summary results of the Industry Conference on the Commercial Use of Space

    Get PDF
    The future intentions of the Federal Republic of Germany in the area of the commercialization of space are presented. It is shown that significant advances in microgravity research, particulary in the areas of materials science, composite materials, physical chemistry, crystal growth, biology, and process engineering will have an effect on future plans for establishing sponsoring organizations to guide commercial interests in German space research. An organizational and functional outline of a proposed sponsoring organization to promote space commercialization under German supervision, including the objectives, the target group to be served, and the administrative structure, is presented. The role of the DFVLR (German Aerospace Research Establishment) and the BMFT (German Ministry for Research and Technology) as sponsoring organizations representing the interests of the German government is shown

    Thermomechanical behavior of monolithic Sn-Ag-Cu solder and copper fiber reinforced solders

    Get PDF
    Solder joints provide both electrical and mechanical interconnections between a silicon chip and the packaging substrate in an electronic application. The thermomechanical cycling in the solder causes numerous reliability challenges, mostly because of the mismatch of the coefficient of thermal expansion between the silicon chip and the substrate. The actual transition to lead-free solders and the trend towards hotter-running, miniaturized and higher current density chips aggravate this situation. Therefore, improved solder joints, with higher resistance to creep and low cycle fatigue, are necessary for future generations of microelectronics. This study focuses on a thermomechanical behavior comparison between monolithic Sn-Ag-Cu, copper fiber and copper ribbon cylindrical reinforced solders. The composite solders were found to reduce the inelastic strain range of the joint relative to monolithic solder, but at the expense of increased stress range.http://archive.org/details/thermomechanical109452062Approved for public release; distribution is unlimited

    The speed of quantum information and the preferred frame: analysis of experimental data

    Get PDF
    The results of EPR experiments performed in Geneva are analyzed in the frame of the cosmic microwave background radiation, generally considered as a good candidate for playing the role of preferred frame. We set a lower bound for the speed of quantum information in this frame at 1.5 x 10^4 c.Comment: 9 pages including 3 figure

    Comparing Variance/Covariance and Historical Simulation in the Context of the Financial Crisis – Do Extreme Movements Have an Influence onto Portfolio Selection?

    Get PDF
    Portfolio theory and the basic ideas of Markowitz have been extended in the recent past by alternative risk models as historical simulation or even copula functions. The central question of this paper is if these approaches lead to different results compared to the classical variance/covariance approach. Therefore, empirical data of the last 10 years is analysed. Both approaches are compared in the special context of the financial crisis. The worst case optimization and the Value at Risk (VaR) are defined in order to define the minimum risk portfolio before and after the financial crisis. The result is that the financial crisis has nearly no impact onto the portfolio, but the two approaches lead to different results

    Interpretation of the evolution parameter of the Feynman parametrization of the Dirac equation

    Get PDF
    The Feynman parametrization of the Dirac equation is considered in order to obtain an indefinite mass formulation of relativistic quantum mechanics. It is shown that the parameter that labels the evolution is related to the proper time. The Stueckelberg interpretation of antiparticles naturally arises from the formalism.Comment: 6 pages, RevTex, no figures, submitted to Phys. Lett.

    An analysis of design reuse benefits

    Get PDF
    Although the concept of design reuse is accepted as a valid approach to design, little attempt has been made to formalise the elements that constitutes design reuse. The few approaches formalising design reuse, e.g. 'Concept Reuse Approach for Engineering Design Problem Solving', tend to be prescriptive, detailing procedures and functions that have to be carried out in order to reuse designs. Such procedural methods fail to identify the underlying processes and knowledge resources of design reuse and tend to relate to an approach or method of tackling reuse rather than reuse itself. It would seem that the only current model encompassing design reuse is 'The Design Reuse Process Model'. The elements of this reuse process model have been used as a basis upon which to identify and analyse the benefits of design reuse when considering key metrics relating to competitive product development,that is time, cost, quality and performance

    Reuse remix recycle: repurposing archaeological digital data

    Get PDF
    Preservation of digital data is predicated on the expectation of its reuse, yet that expectation has never been examined within archaeology. While we have extensive digital archives equipped to share data, evidence of reuse seems paradoxically limited. Most archaeological discussions have focused on data management and preservation and on disciplinary practices surrounding archiving and sharing data. This article addresses the reuse side of the data equation through a series of linked questions: What is the evidence for reuse, what constitutes reuse, what are the motivations for reuse, and what makes some data more suitable for reuse than others? It concludes by posing a series of questions aimed at better understanding our digital engagement with archaeological data

    Software Reuse in Agile Development Organizations - A Conceptual Management Tool

    Get PDF
    The reuse of knowledge is considered a major factor for increasing productivity and quality. In the software industry knowledge is embodied in software assets such as code components, functional designs and test cases. This kind of knowledge reuse is also referred to as software reuse. Although the benefits can be substantial, software reuse has never reached its full potential. Organizations are not aware of the different levels of reuse or do not know how to address reuse issues. This paper proposes a conceptual management tool for supporting software reuse. Furthermore the paper presents the findings of the application of the management tool in an agile development organization
    corecore