5,771 research outputs found

    Comparison of solar system measured data for various sample rates

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    The results of solar house data for sample rates of 50, 100, 250, 300, and 600 seconds were compared. The data considered for summer days were the heat incident on the collectors, the heat used by the air conditioner generator, and the heat used by the auxiliary heater. For winter days, the heat incident, the heat collected and the heat used by the heat exchanger were computed. These data were compared for different weather days such as clear days, partly cloudy days, cloudy days, and very cloudy days. Also, data for the integration of all these weather days were compared. The precentage differences for these data, using 50 second sample rate as a base, are also presented

    Analysis of thermal environment in the thrustor cavity of space vehicles

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    Wind tunnel tests to determine the mechanisms involved in producing the high local heating rates in and around the thrustor nozzle in a non-firing condition are reported. The geometry of a typical nozzle installation is described. Procedures for reducing the effects of hypersonic flow interactions in order to prevent excess local heating are explained

    Static and non-static quantum effects in two-dimensional dilaton gravity

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    We study backreaction effects in two-dimensional dilaton gravity. The backreaction comes from an R2R^2 term which is a part of the one-loop effective action arising from massive scalar field quantization in a certain approximation. The peculiarity of this term is that it does not contribute to the Hawking radiation of the classical black hole solution of the field equations. In the static case we examine the horizon and the physical singularity of the new black hole solutions. Studying the possibility of time dependence we see the generation of a new singularity. The particular solution found still has the structure of a black hole, indicating that non-thermal effects cannot lead, at least in this approximation, to black hole evaporation.Comment: 10 pages, no figure

    Charge transfer in nanocrystalline-Au/ZnO nanorods investigated by x-ray spectroscopy and scanning photoelectron microscopy

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    [[abstract]]O K- and Zn and Au L3-edge x-ray absorption near-edge structure (XANES), x-ray emission spectroscopy (XES), and scanning photoelectron microscopy (SPEM) are performed to investigate the electronic structure of ZnO nanorods with nanocrystalline (nc)-Au particles grown on the surfaces. The XANES spectra of nc-Au/ZnO nanorods reveal the decrease of the number of both O 2p and Zn 4s/3d unoccupied states with the increase of the nc-Au particle size. The number of Au 6s/5d unoccupied states increases when the size of nc-Au particle decreases, indicating that the deposition of nc-Au particles on the surface of ZnO nanorods promotes charge transfer from the ZnO nanorods to nc-Au particles. Excitation energy dependent XES and SPEM spectra show that the number of electrons in the valence band of O 2p-Zn 4sp hybridized states decreases as the nc-Au particle size increases, revealing that more electrons are excited from the valence band to the conduction band of ZnO nanorods and the storage of electrons in nc-Au particles.[[journaltype]]國外[[incitationindex]]SCI[[cooperationtype]]國內[[booktype]]紙本[[countrycodes]]US

    Foldy-Wouthuysen transformation for a Dirac-Pauli dyon and the Thomas-Bargmann-Michel-Telegdi equation

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    The classical dynamics for a charged point particle with intrinsic spin is governed by a relativistic Hamiltonian for the orbital motion and by the Thomas-Bargmann-Michel-Telegdi equation for the precession of the spin. It is natural to ask whether the classical Hamiltonian (with both the orbital and spin parts) is consistent with that in the relativistic quantum theory for a spin-1/2 charged particle, which is described by the Dirac equation. In the low-energy limit, up to terms of the 7th order in 1/Eg1/E_g (Eg=2mc2E_g=2mc^2 and mm is the particle mass), we investigate the Foldy-Wouthuysen (FW) transformation of the Dirac Hamiltonian in the presence of homogeneous and static electromagnetic fields and show that it is indeed in agreement with the classical Hamiltonian with the gyromagnetic ratio being equal to 2. Through electromagnetic duality, this result can be generalized for a spin-1/2 dyon, which has both electric and magnetic charges and thus possesses both intrinsic electric and magnetic dipole moments. Furthermore, the relativistic quantum theory for a spin-1/2 dyon with arbitrary values of the gyromagnetic and gyroelectric ratios can be described by the Dirac-Pauli equation, which is the Dirac equation with augmentation for the anomalous electric and anomalous magnetic dipole moments. The FW transformation of the Dirac-Pauli Hamiltonian is shown, up to the 7th order again, to be also in accord with the classical Hamiltonian.Comment: 18 page

    Thermal performance evaluation of Solar Energy Products Company (SEPCO) 'Soloron' collector tested outdoors

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    The test article, Model EF-212, Serial Nr. 002, is a single glazed collector with a nonselective absorber plate, using flowing air as the heat transfer medium. The absorber plate and box frame are aluminum and the insulation is one inch isocyanurate foam board with thermal conductivity of 0.11 (BTU/sq ft Hr0/ft.) The tests included the following. (1) time constant test, (2) collector efficiency test, (3) collector stagnation test, (4) incident angle modifier test, (5) load test, (6) weathering test, and (7) absorber plate optical properties test. The results of these tests are tabulated, graphed, or otherwise recorded

    Measuring the Value of Strategic Alliances in the Wake of a Financial Implosion: Evidence from Japan's Financial Services Sector

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    This paper examines the wealth effects of financial-institution strategic alliances on the shareholders of the newly allied firms. Our paper is different from previous studies of non-financial joint ventures, financial and non-financial mergers and acquisitions, and non-financial strategic alliances in three important aspects/ways: First, we focus on financial institutions that form strategic alliances. Second, while most related studies use U.S. data, this paper employs Japanese data for the late 1990s, directly testing financial theory in a different setting. Finally, we study whether different types of alliances result in differing magnitudes of stock market responses. Our primary results are as follows: First, we find that a strategic alliance, on average, increases the value of the partner firms. This is consistent with the “synergy” hypothesis. Second, the gains from the alliance are spread more widely among the partners than would be suggested by a random alternative, supporting a “win-win” hypothesis. Third, smaller partners tend to experience larger percentage gains, which is consistent with a “relative size” hypothesis. Fourth, the market values inter-group alliance announcements more than intra-group alliance announcements; the latter may well be seen as redundant. This is consistent with an “inter-group synergies” hypothesis. Fifth, we do not find a significant difference in the abnormal returns showed by domestic-foreign alliances and domestic-domestic alliances, although both sets of alliances show significantly positive returns. We thus do not find support for a “foreign firm superior” hypothesis. Finally, we find that an investment-banking alliance has a strong positive effect on abnormal returns, indicating that investment banking, which has been underdeveloped in Japan relative to the U.S., may be a promising business for financial institutions. Overall, this paper complements the existing literature in that we analyze the value of financial institution alliances. Our analysis reconfirms that strategic alliances are value-enhancing. This is consistent with previous studies that find increased value in the announcement of a strategic alliance or a merger. Our results are consistent with the notion that financial deregulation tends to increase competition, which, in turn, encourages firms to adopt aggressive corporate strategies. This is viewed as a positive move by investors, as evidenced by the average gains of the shareholders of these alliance-forging firms

    A study of forced flow separation in rocket nozzle

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    The characteristics of flow profile in a rocket nozzle during the start transient were investigated as well as possibilities of reducing the side-load thrust by sticking trip wires in the nozzle. To simplify the geometry of flow configuration around the trip wire, it was assumed that the flow is passing through square steps instead of round wires. Since a purely analytic solution is not available, a series of semiempirical solutions was proposed
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