12,557 research outputs found

    Evaluating the reliability of NAND multiplexing with PRISM

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    Probabilistic-model checking is a formal verification technique for analyzing the reliability and performance of systems exhibiting stochastic behavior. In this paper, we demonstrate the applicability of this approach and, in particular, the probabilistic-model-checking tool PRISM to the evaluation of reliability and redundancy of defect-tolerant systems in the field of computer-aided design. We illustrate the technique with an example due to von Neumann, namely NAND multiplexing. We show how, having constructed a model of a defect-tolerant system incorporating probabilistic assumptions about its defects, it is straightforward to compute a range of reliability measures and investigate how they are affected by slight variations in the behavior of the system. This allows a designer to evaluate, for example, the tradeoff between redundancy and reliability in the design. We also highlight errors in analytically computed reliability bounds, recently published for the same case study

    Optimal operating conditions and characteristics of acetone/CaF_2 detector for inverse photoemission spectroscopy

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    Performance and characteristics of a band-pass photon detector using acetone gas and CaF_2 window (acetone/CaF_2) have been studied and compared with an ethanol/MgF_2 detector. The optimal operating conditions are found to be 4 mbar acetone pressure and 745+/-20 V anode voltage. The count rate obtained by us is about a factor of 3 higher than what has been reported earlier for the acetone detector. Unlike other gas filled detectors, this detector works in the proportional region with very small dead time (4 micro sec). A detector band-pass of 0.48+/-0.01 eV FWHM is obtained.Comment: Review of Scientific Instruments 76, 066102 (2005

    Exact Solution of Return Hysteresis Loops in One Dimensional Random Field Ising Model at Zero Temperature

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    Minor hysteresis loops within the main loop are obtained analytically and exactly in the one-dimensional ferromagnetic random field Ising-model at zero temperature. Numerical simulations of the model show excellent agreement with the analytical results

    Deuteron Momentum Distribution in KD2HPO4

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    The momentum distribution in KD2PO4(DKDP) has been measured using neutron Compton scattering above and below the weakly first order paraelectric-ferroelectric phase transition(T=229K). There is very litte difference between the two distributions, and no sign of the coherence over two locations for the proton observed in the paraelectric phase, as in KH2PO4(KDP). We conclude that the tunnel splitting must be much less than 20mev. The width of the distribution indicates that the effective potential for DKDP is significantly softer than that for KDP. As electronic structure calculations indicate that the stiffness of the potential increases with the size of the coherent region locally undergoing soft mode fluctuations, we conclude that there is a mass dependent quantum coherence length in both systems.Comment: 6 pages 5 figure

    Nonlinear wave interactions in quantum magnetoplasmas

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    Nonlinear interactions involving electrostatic upper-hybrid (UH), ion-cyclotron (IC), lower-hybrid (LH), and Alfven waves in quantum magnetoplasmas are considered. For this purpose, the quantum hydrodynamical equations are used to derive the governing equations for nonlinearly coupled UH, IC, LH, and Alfven waves. The equations are then Fourier analyzed to obtain nonlinear dispersion relations, which admit both decay and modulational instabilities of the UH waves at quantum scales. The growth rates of the instabilities are presented. They can be useful in applications of our work to diagnostics in laboratory and astrophysical settings.Comment: 15 pages, to appear in Physics of Plasma

    Critical Hysteresis in Random Field XY and Heisenberg Models

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    We study zero-temperature hysteresis in random-field XY and Heisenberg models in the zero-frequency limit of a cyclic driving field. We consider three distributions of the random field and present exact solutions in the mean field limit. The results show a strong effect of the form of disorder on critical hysteresis as well as the shape of hysteresis loops. A discrepancy with an earlier study based on the renormalization group is resolved.Comment: 10 pages, 6 figures; this is published version (added some text and references

    Development Trends in Wind Energy Conversion System: A Review

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    Wind energy for electricity production today is a mature, competitive and virtually pollution-free technology widely used in many areas of the world. Wind energy conversion systems have become a focal point in the research of renewable energy sources. This is not only due to the rapid advances in the size of wind generators but also for the improvement of energy electronics and their applicability in wind energy extraction. This paper deals with the recent developments in wind energy conversion systems, their classifications, choice of generators and their social, economic and environmental advantages and disadvantages, a review of the interconnection issues of distributed resources including wind power with electric power systems. DOI: 10.17762/ijritcc2321-8169.150710

    Advanced Magnetic Resonance Imaging in Glioblastoma: A Review

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    INTRODUCTION In 2017, it is estimated that 26,070 patients will be diagnosed with a malignant primary brain tumor in the United States, with more than half having the diagnosis of glioblas- toma (GBM).1 Magnetic resonance imaging (MRI) is a widely utilized examination in the diagnosis and post-treatment management of patients with glioblastoma; standard modalities available from any clinical MRI scanner, including T1, T2, T2-FLAIR, and T1-contrast-enhanced (T1CE) sequences, provide critical clinical information. In the last decade, advanced imaging modalities are increasingly utilized to further charac- terize glioblastomas. These include multi-parametric MRI sequences, such as dynamic contrast enhancement (DCE), dynamic susceptibility contrast (DSC), diffusion tensor imaging (DTI), functional imaging, and spectroscopy (MRS), to further characterize glioblastomas, and significant efforts are ongoing to implement these advanced imaging modalities into improved clinical workflows and personalized therapy approaches. A contemporary review of standard and advanced MR imaging in clinical neuro-oncologic practice is presented

    Synthesis and characterization of polyurethane microspheres

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    A novel particle forming polymerization technique for the preparation of polyurethane microspheres with particle size in the range 0.1-100 micron is described. The method is general, applicable to wide variety of diols and isocyanates and is very simple. The key to successful particle forming polymerization is the use of novel steric stabilizers, such as, a reactive diol containing two primary hydroxyl groups with a long hydrophobic acrylate ester moiety and an amphiphilic block copolymer. The effect of various reactiorr variables on the particle forming polymerization process will be discussed

    Ab initio Hartree-Fock Born effective charges of LiH, LiF, LiCl, NaF, and NaCl

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    We use the Berry-phase-based theory of macroscopic polarization of dielectric crystals formulated in terms of Wannier functions, and state-of-the-art Gaussian basis functions, to obtain benchmark ab initio Hartree-Fock values of the Born effective charges of ionic compounds LiH, LiF, LiCl, NaF, and NaCl. We find excellent agreement with the experimental values for all the compounds except LiCl and NaCl, for which the disagreement with the experiments is close to 10% and 16%, respectively. This may imply the importance of many-body effects in those systems.Comment: 11 pages, Revtex, 2 figures (included), to appear in Phys. Rev. B April 15, 200
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