5,468 research outputs found

    Ultraviolet instrumentation for orbital remote sensors

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    Ultraviolet instrumentation for orbital remote sensor

    Energy Efficiency in Multi-hop CDMA Networks: A Game Theoretic Analysis

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    A game-theoretic analysis is used to study the effects of receiver choice on the energy efficiency of multi-hop networks in which the nodes communicate using Direct-Sequence Code Division Multiple Access (DS-CDMA). A Nash equilibrium of the game in which the network nodes can choose their receivers as well as their transmit powers to maximize the total number of bits they transmit per unit of energy is derived. The energy efficiencies resulting from the use of different linear multiuser receivers in this context are compared, looking at both the non-cooperative game and the Pareto optimal solution. For analytical ease, particular attention is paid to asymptotically large networks. Significant gains in energy efficiency are observed when multiuser receivers, particularly the linear minimum mean-square error (MMSE) receiver, are used instead of conventional matched filter receivers.Comment: To appear in the Proceedings of the Workshop on Multi-Layer Modelling and Design of Multi-Hop Wireless Networks (MLMD 06), Minneapolis, MN, July 12 - 15, 200

    Advanced evaluation of vacuum UV detector- spectroscopy systems for capsule reentry measurements

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    Vacuum ultraviolet detector evaluation - spectroscopy systems for capsule reentry measurement

    Electron capture to continuum in collisions of bare projectiles with Ne targets

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    Abstract. We have investigated the cusp resulting from electron capture to the continuum of 1.25-5 MeV m u- ' fully stripped hydrogen and oxygen as a function of the collision energy and the detector angular resolution B o. It is revealed that the characteristic cusp shape parameters depend strongly on the experimental resolution. Our experimental data are "pared with the second-order Born theory and the impulse approximation. Both theories mnhrm the 8, dependence of the shape parameters and gjve a reasonable descrip-lion of the cusp asymmetry. However, theory tends to overestimate the absolute cross sections, in particular in the case of oxygen. 1

    ALERT: FARMERS NEED TO SIGN UP FOR ACRE!

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    Corn, soybean and wheat producers are facing serious financial challenges. And it is even worse for livestock producers, most of who are also crop producers and are therefore eligible for ACRE. Crops are behind in maturity, some areas of the state need rain, product prices have fallen substantially, and USDA Counter Cyclical payments do not start until 2.35oncorn,2.35 on corn, 5.36 soybeans and $3.40 on wheat. Chances of prices that low are around 10-15%, but at that point ACRE payments would be much, much bigger. Many producers do not understand ACRE and the benefits available; most of the reasons given for not participating are invalid.Crop Production/Industries, Farm Management,

    Conical Correlations, Bragg Peaks, and Transverse Flow Deflections in Jet Tomography

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    We use (3+1)-dimensional ideal hydrodynamics to describe a variety of different jet energy loss scenarios for a jet propagating through an opaque medium. The conical correlations obtained for fully stopped jets, revealing a Bragg peak, are discussed as well as results from pQCD and AdS/CFT. Moreover, we investigate transverse flow deflection. It is demonstrated that a double-peaked away-side structure can be formed due to the different contributions of several possible jet trajectories through an expanding medium.Comment: 4 pages, 3 figures - To appear in the conference proceedings for Quark Matter 2009, March 30 - April 4, Knoxville, Tennessee, revised versio

    From kinetic theory to dissipative fluid dynamics

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    We present the results of deriving the Israel-Stewart equations of relativistic dissipative fluid dynamics from kinetic theory via Grad's 14-moment expansion. Working consistently to second order in the Knudsen number, these equations contain several new terms which are absent in previous treatments.Comment: 7 pages, proceedings of the Erice School on Nuclear Physics "Heavy Ion collisions from the Coulomb Barrier up to the Quark Gluon Plasma", Erice, Sicily, Sep. 16 - 24, 200

    Jet Propagation and Mach Cones in (3+1)d Ideal Hydrodynamics

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    The observation of jet quenching and associated away--side Mach cone--like correlations at RHIC provide powerful ``external'' probes of the sQGP produced in A+A reactions, but it simultaneously raises the question where the jet energy was deposited. The nearly perfect bulk fluidity observed via elliptic flow suggests that Mach cone--like correlations may also be due to rapid local equilibration in the wake of penetrating jets. Multi-particle correlations lend further support to this possibility. However, a combined study of energy deposition and fluid response is needed. We solve numerically 3--dimensional ideal hydrodynamical equations to compute the flow correlation patterns resulting from a variety of possible energy-momentum deposition models. Mach--cone correlations are shown to depend critically on the energy and momentum deposition mechanisms. They only survive for a special limited class of energy--momentum loss models, which assume significantly less longitudinal momentum loss than energy loss per unit length. We conclude that the correct interpretation of away--side jet correlations will require improved understanding and independent experimental constraints on the jet energy--momentum loss to fluid couplings.Comment: 4 pages, 3 figures, To appear in the proceedings of Quark Matter 200
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