28,968 research outputs found

    Precision CW laser automatic tracking system investigated

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    Precision laser tracker capable of tracking a low acceleration target to an accuracy of about 20 microradians rms is being constructed and tested. This laser tracking has the advantage of discriminating against other optical sources and the capability of simultaneously measuring range

    Descriptive Proximal Homotopy. Properties and Relations

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    This paper introduces properties and relations for proximal homotopy as well as descriptive proximal homotopy. A number of results are given for the homotopy between Lodato-proximally continuous maps and for the homotopy between descriptive Lodato proximally continuous maps. This paper also introduces homotopic cycles in conjunction with paths in either proximity spaces in general or in descriptive proximity spaces. Three main results in this paper are (1) that the product of descriptive Lodata proximity (dlp) spaces is also a dlp space, (2) every descriptive dlp relation is an equivalence relation and (3) every homotopic cycle has a free group representation.Comment: 16 pages, 4 figure

    Feasibility study of silicon nitride protection of plastic encapsulated semiconductors

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    The application of low temperature silicon nitride protective layers on wire bonded integrated circuits mounted on lead frame assemblies is reported. An evaluation of the mechanical and electrical compatibility of both plasma nitride and photochemical silicon nitride (photonitride) passivations (parallel evaluations) of integrated circuits which were then encapsulated in plastic is described. Photonitride passivation is compatible with all wire bonded lead frame assemblies, with or without initial chip passivation. Plasma nitride passivation of lead frame assemblies is possible only if the chip is passivated before lead frame assembly. The survival rate after the environmental test sequence of devices with a coating of plasma nitride on the chip and a coating of either plasma nitride or photonitride over the assembled device is significantly greater than that of devices assembled with no nitride protective coating over either chip or lead frame

    Development of mathematical techniques for the analysis of remote sensing data

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    There are no author-identified significant results in this report

    A Numerical Renormalization Group approach to Green's Functions for Quantum Impurity Models

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    We present a novel technique for the calculation of dynamical correlation functions of quantum impurity systems in equilibrium with Wilson's numerical renormalization group. Our formulation is based on a complete basis set of the Wilson chain. In contrast to all previous methods, it does not suffer from overcounting of excitation. By construction, it always fulfills sum rules for spectral functions. Furthermore, it accurately reproduces local thermodynamic expectation values, such as occupancy and magnetization, obtained directly from the numerical renormalization group calculations.Comment: 13 pages, 7 figur

    On-the-fly memory compression for multibody algorithms.

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    Memory and bandwidth demands challenge developers of particle-based codes that have to scale on new architectures, as the growth of concurrency outperforms improvements in memory access facilities, as the memory per core tends to stagnate, and as communication networks cannot increase bandwidth arbitrary. We propose to analyse each particle of such a code to find out whether a hierarchical data representation storing data with reduced precision caps the memory demands without exceeding given error bounds. For admissible candidates, we perform this compression and thus reduce the pressure on the memory subsystem, lower the total memory footprint and reduce the data to be exchanged via MPI. Notably, our analysis and transformation changes the data compression dynamically, i.e. the choice of data format follows the solution characteristics, and it does not require us to alter the core simulation code
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