21,147 research outputs found

    Customer Concerns about Uncertainty and Willingness to Pay in Leasing Solar Power Systems

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    Although solar power systems are considered as one of the most promising renewable energy sources, some uncertain factors as well as the high cost could be barriers which create customer resistance. Leasing instead of purchase, as one type of product service system, could be an option to reduce consumer concern on such issues. This study focuses on consumer concerns about uncertainty and willingness to pay for leasing solar power systems. Conjoint analysis method is used to find part worth utilities and estimate gaps of willingness to pay between attribute levels, including various leasing time lengths. The results show the part worth utilities an d relative importance of four major attributes, including leasing time. Among concerns about uncertainties, government subsidy, electricity price, reliability, and rise of new generation solar power systems were found to be significantly related to the additional willingness-to-pay for a shorter leasing time. Cluster analysis is used to identify two groups standing for high and low concerns about uncertainty. People with more concerns tend to pay more for a shorter lease time

    A statistical mechanics framework for multi-particle production in high energy reactions

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    We deduce the particle distributions in particle collisions with multihadron-production in the framework of mechanical statistics. They are derived as functions of x, P_T^2 and the rest mass of different species for a fixed total number of all produced particles, inelasticity and total transverse energy. For P_T larger than the mass of each particle we get the behaviour \frac{dn_i}{dP_T} \sim \sqrt{P_T} e^{-\frac{P_T}{T_H}} Values of _\pi, _K, and _{\bar{p}} in agreement with experiment are found by taking T_H=180MeV (the Hagedorn temperature).Comment: 9 pages, RevTe

    Stochastic self-assembly of incommensurate clusters

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    We examine the classic problem of homogeneous nucleation and growth by deriving and analyzing a fully discrete stochastic master equation. Upon comparison with results obtained from the corresponding mean-field Becker-D\"{o}ring equations we find striking differences between the two corresponding equilibrium mean cluster concentrations. These discrepancies depend primarily on the divisibility of the total available mass by the maximum allowed cluster size, and the remainder. When such mass incommensurability arises, a single remainder particle can "emulsify" or "disperse" the system by significantly broadening the mean cluster size distribution. This finite-sized broadening effect is periodic in the total mass of the system and can arise even when the system size is asymptotically large, provided the ratio of the total mass to the maximum cluster size is finite. For such finite ratios we show that homogeneous nucleation in the limit of large, closed systems is not accurately described by classical mean-field mass-action approaches.Comment: 5 pages, 4 figures, 1 tabl

    Momentum Distribution for Bosons with Positive Scattering Length in a Trap

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    The coordinate-momentum double distribution function ρ(r,p)d3rd3p\rho ({\bf r}, {\bf p}) d^{3}rd^{3}p is calculated in the local density approximation for bosons with positive scattering length aa in a trap. The calculation is valid to the first order of aa. To clarify the meaning of the result, it is compared for a special case with the double distribution function ρwd3rd3p\rho_{w}d^{3} rd^{3}p of Wigner.Comment: Latex fil

    ^{59}Co NMR evidence for charge ordering below T_{CO}\sim 51 K in Na_{0.5}CoO_2

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    The CoO2_{2} layers in sodium-cobaltates Nax_{x}CoO2_{2} may be viewed as a spin S=1/2S=1/2 triangular-lattice doped with charge carriers. The underlying physics of the cobaltates is very similar to that of the high TcT_{c} cuprates. We will present unequivocal 59^{59}Co NMR evidence that below TCO51KT_{CO}\sim51 K, the insulating ground state of the itinerant antiferromagnet Na0.5_{0.5}CoO2_{2} (TN86KT_{N}\sim 86 K) is induced by charge ordering.Comment: Phys. Rev. Lett. 100 (2008), in press. 4 figure

    Deep shower interpretation of the cosmic ray events observed in excess of the Greisen-Zatsepin-Kuzmin energy

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    We consider the possibility that the ultra-high-energy cosmic ray flux has a small component of exotic particles which create showers much deeper in the atmosphere than ordinary hadronic primaries. It is shown that applying the conventional AGASA/HiRes/Auger data analysis procedures to such exotic events results in large systematic biases in the energy spectrum measurement. SubGZK exotic showers may be mis-reconstructed with much higher energies and mimick superGZK events. Alternatively, superGZK exotic showers may elude detection by conventional fluorescence analysis techniques.Comment: 22 pages, 5 figure

    EXITE2 Observation of the SIGMA Source GRS 1227+025

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    We report the EXITE2 hard X-ray imaging of the sky around 3C273. A 2h observation on May 8, 1997, shows a \sim260 mCrab source detected at 4σ\sim4\sigma in each of two bands (50-70 and 70-93 keV) and located \sim30' from 3C273 and consistent in position with the SIGMA source GRS1227+025. The EXITE2 spectrum is consistent with a power law with photon index 3 and large low energy absorption, as indicated by the GRANAT/SIGMA results. No source was detected in more sensitive followup EXITE2 observations in 2000 and 2001 with 3σ\sigma upper limits of 190 and 65 mCrab, respectively. Comparison with the flux detected by SIGMA shows the source to be highly variable, suggesting it may be non-thermal and beamed and thus the first example of a ``type 2'' (absorbed) Blazar. Alternatively it might be (an unprecedented) very highly absorbed binary system undergoing accretion disk instability outbursts, possibly either a magnetic CV, or a black hole X-ray nova.Comment: 12 pages, 4 figures, accepted for publication in Ap

    Baryon Magnetic Moments and Proton Spin: A Model with Collective Quark Rotation

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    We analyse the baryon magnetic moments in a model that relates them to the parton spins Δu\Delta u, Δd\Delta d, Δs\Delta s, and includes a contribution from orbital angular momentum. The specific assumption is the existence of a 3-quark correlation (such as a flux string) that rotates with angular momentum Lz\langle L_z \rangle around the proton spin axis. A fit to the baryon magnetic moments, constrained by the measured values of the axial vector coupling constants a(3)=F+Da^{(3)}=F+D, a(8)=3FDa^{(8)}=3F-D, yields Sz=0.08±0.13\langle S_z \rangle = 0.08 \pm 0.13, Lz=0.39±0.09\langle L_z \rangle = 0.39 \pm 0.09, where the error is a theoretical estimate. A second fit, under slightly different assumptions, gives Lz=0.37±0.09\langle L_z \rangle = 0.37 \pm 0.09, with no constraint on Sz\langle S_z \rangle. The model provides a consistent description of axial vector couplings, magnetic moments and the quark polarization Sz\langle S_z \rangle measured in deep inelastic scattering. The fits suggest that a significant part of the angular momentum of the proton may reside in a collective rotation of the constituent quarks.Comment: 16 pages, 3 ps-figures, uses RevTeX. Abstract, Sec. II, III and IV have been expande

    Experimental evidence for a two-gap structure of superconducting NbSe_2: a specific heat study in external magnetic fields

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    To resolve the discrepancies of the superconducting order parameter in quasi-two-dimensional NbSe_2, comprehensive specific-heat measurements have been carried out. By analyzing both the zero-field and mixed-state data with magnetic fields perpendicular to and parallel to the c axis of the crystal and using the two-gap model, we conclude that (1) more than one energy scale of the order parameter is required for superconducting NbSe_2 due to the thermodynamic consistency; (2)delta_L=1.26 meV and delta_S=0.73 meV are obtained; (3) N_S(0)/N(0)=11%~20%; (4) The observation of the kink in gamma(H) curve suggests that the two-gap scenario is more favorable than the anisotropic s-wave model to describe the gap structure of NbSe_2; and (5)delta_S is more isotropic and has a three-dimensional-like feature and is located either on the Se or the bonding Nb Fermi sheets.Comment: 16 pages, 4 figure

    General linear dynamics - quantum, classical or hybrid

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    We describe our recent proposal of a path integral formulation of classical Hamiltonian dynamics. Which leads us here to a new attempt at hybrid dynamics, which concerns the direct coupling of classical and quantum mechanical degrees of freedom. This is of practical as well as of foundational interest and no fully satisfactory solution of this problem has been established to date. Related aspects will be observed in a general linear ensemble theory, which comprises classical and quantum dynamics in the form of Liouville and von Neumann equations, respectively, as special cases. Considering the simplest object characterized by a two-dimensional state-space, we illustrate how quantum mechanics is special in several respects among possible linear generalizations.Comment: 17 pages; based on invited talks at the conferences DICE2010 (Castiglioncello, Italia, Sept 13-17, 2010) and Quantum Field Theory and Gravity (Regensburg, Germany, Sept 28 - Oct 1, 2010
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