6,898 research outputs found

    Space-time code diversity by phase rotation in multi-carrier multi-user systems

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    Code diversity using space-time block codes was developed for single-carrier and single-receiver systems. In this paper, the extension of code diversity by phase rotation to multi-user and multi-carrier systems is proposed and analyzed. We show that code diversity with reduced feedback is possible in this new scenario and the coding gain has a mild logarithmic decrease with the number of users and the number of sub-carriers. In addition, we develop an analytical upper bound for the average error probability whose accuracy is verified by simulation

    Lattice Boltzmann Simulation of Non-Ideal Fluids

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    A lattice Boltzmann scheme able to model the hydrodynamics of phase separation and two-phase flow is described. Thermodynamic consistency is ensured by introducing a non-ideal pressure tensor directly into the collision operator. We also show how an external chemical potential can be used to supplement standard boundary conditions in order to investigate the effect of wetting on phase separation and fluid flow in confined geometries. The approach has the additional advantage of reducing many of the unphysical discretisation problems common to previous lattice Boltzmann methods.Comment: 11 pages, revtex, 4 Postscript figures, uuencode

    Non-Newtonian Couette-Poiseuille flow of a dilute gas

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    The steady state of a dilute gas enclosed between two infinite parallel plates in relative motion and under the action of a uniform body force parallel to the plates is considered. The Bhatnagar-Gross-Krook model kinetic equation is analytically solved for this Couette-Poiseuille flow to first order in the force and for arbitrary values of the Knudsen number associated with the shear rate. This allows us to investigate the influence of the external force on the non-Newtonian properties of the Couette flow. Moreover, the Couette-Poiseuille flow is analyzed when the shear-rate Knudsen number and the scaled force are of the same order and terms up to second order are retained. In this way, the transition from the bimodal temperature profile characteristic of the pure force-driven Poiseuille flow to the parabolic profile characteristic of the pure Couette flow through several intermediate stages in the Couette-Poiseuille flow are described. A critical comparison with the Navier-Stokes solution of the problem is carried out.Comment: 24 pages, 5 figures; v2: discussion on boundary conditions added; 10 additional references. Published in a special issue of the journal "Kinetic and Related Models" dedicated to the memory of Carlo Cercignan

    Implications of the Unitarity Triangle `uc' for J, δ\delta and VCKM|V_{CKM}| elements

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    The Jarlskog rephasing invariant parameter J|J| is evaluated using one of the six Unitarity Triangles involving well known CKM matrix elements \vud, \vus,~\rub, ~\vcd, ~\vcs~ and ~\vcb. With PDG2000 values of \vud~ etc. as input, we obtain J=(2.71±1.12)×105|J|=(2.71 \pm 1.12) \times 10^{-5}, which in the PDG representation of CKM matrix leads to the range 21o to 159o21^o~to~159^o for the CP violating phase δ\delta. The CKM matrix elements evaluated using this range of δ\delta are in agreement with the PDG CKM matrix. The implications of refinements in the input on J|J|, δ\delta and CKM matrix elements have also been studied.Comment: 14 pages, 3 figures (eps), updated in the light of latest PDG2000 dat

    Public sector innovation, e-government, and anticorruption in China and India: insights from civil servants

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    Both China and India are adopting information and communication technologies to facilitate openness and transparency in their governments, and hence reduce corruption. Distinctive from their traditional anticorruption approaches, is the innovative e-government approach an effective solution to corruption in these two large developing countries? This paper addresses the question through comparative in-depth interviews with 44 mid- or senior-level officials in the public sector in these two countries. The first study of its kind, our research shows that civil servants in both countries overall think positively about transparency and technology in reducing corruption. However, to what extent these innovative measures will be effective is conditional on various factors, such as political willingness, income inequality, and infrastructure readiness. What is worth noting is that the Chinese respondents were more positive regarding the role of transparency, whereas the Indian respondents were more positive about the role of technology, which may reflect the different facilitators of corruption and the constraints of anticorruption in China and India

    Measurement of Charged Pion Production Yields off the NuMI Target

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    The fixed-target MIPP experiment, Fermilab E907, was designed to measure the production of hadrons from the collisions of hadrons of momenta ranging from 5 to 120 GeV/c on a variety of nuclei. These data will generally improve the simulation of particle detectors and predictions of particle beam fluxes at accelerators. The spectrometer momentum resolution is between 3 and 4%, and particle identification is performed for particles ranging between 0.3 and 80 GeV/c using dE/dxdE/dx, time-of-flight and Cherenkov radiation measurements. MIPP collected 1.42×1061.42 \times10^6 events of 120 GeV Main Injector protons striking a target used in the NuMI facility at Fermilab. The data have been analyzed and we present here charged pion yields per proton-on-target determined in bins of longitudinal and transverse momentum between 0.5 and 80 GeV/c, with combined statistical and systematic relative uncertainties between 5 and 10%.Comment: 15 pages, 13 figure

    Structural Similarity based Anatomical and Functional Brain Imaging Fusion

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    Multimodal medical image fusion helps in combining contrasting features from two or more input imaging modalities to represent fused information in a single image. One of the pivotal clinical applications of medical image fusion is the merging of anatomical and functional modalities for fast diagnosis of malignant tissues. In this paper, we present a novel end-to-end unsupervised learning-based Convolutional Neural Network (CNN) for fusing the high and low frequency components of MRI-PET grayscale image pairs, publicly available at ADNI, by exploiting Structural Similarity Index (SSIM) as the loss function during training. We then apply color coding for the visualization of the fused image by quantifying the contribution of each input image in terms of the partial derivatives of the fused image. We find that our fusion and visualization approach results in better visual perception of the fused image, while also comparing favorably to previous methods when applying various quantitative assessment metrics.Comment: Accepted at MICCAI-MBIA 201

    Kinetic Theory of a Dilute Gas System under Steady Heat Conduction

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    The velocity distribution function of the steady-state Boltzmann equation for hard-core molecules in the presence of a temperature gradient has been obtained explicitly to second order in density and the temperature gradient. Some thermodynamical quantities are calculated from the velocity distribution function for hard-core molecules and compared with those for Maxwell molecules and the steady-state Bhatnagar-Gross-Krook(BGK) equation. We have found qualitative differences between hard-core molecules and Maxwell molecules in the thermodynamical quantities, and also confirmed that the steady-state BGK equation belongs to the same universality class as Maxwell molecules.Comment: 36 pages, 4 figures, 5 table

    High rate, fast timing Glass RPC for the high {\eta} CMS muon detectors

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    The HL-LHC phase is designed to increase by an order of magnitude the amount of data to be collected by the LHC experiments. To achieve this goal in a reasonable time scale the instantaneous luminosity would also increase by an order of magnitude up to 6.1034cm2s16.10^{34} cm^{-2} s^{-1} . The region of the forward muon spectrometer (η>1.6|{\eta}| > 1.6) is not equipped with RPC stations. The increase of the expected particles rate up to 2kHz/cm22 kHz/cm^{2} (including a safety factor 3) motivates the installation of RPC chambers to guarantee redundancy with the CSC chambers already present. The actual RPC technology of CMS cannot sustain the expected background level. The new technology that will be chosen should have a high rate capability and provides a good spatial and timing resolution. A new generation of Glass-RPC (GRPC) using low-resistivity (LR) glass is proposed to equip at least the two most far away of the four high η{\eta} muon stations of CMS. First the design of small size prototypes and studies of their performance in high-rate particles flux is presented. Then the proposed designs for large size chambers and their fast-timing electronic readout are examined and preliminary results are provided.Comment: 14 pages, 11 figures, Conference proceeding for the 2016 Resistive Plate Chambers and Related Detector
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