99,988 research outputs found

    The Casimir effect for parallel plates at finite temperature in the presence of one fractal extra compactified dimension

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    We discuss the Casimir effect for massless scalar fields subject to the Dirichlet boundary conditions on the parallel plates at finite temperature in the presence of one fractal extra compactified dimension. We obtain the Casimir energy density with the help of the regularization of multiple zeta function with one arbitrary exponent and further the renormalized Casimir energy density involving the thermal corrections. It is found that when the temperature is sufficiently high, the sign of the Casimir energy remains negative no matter how great the scale dimension δ\delta is within its allowed region. We derive and calculate the Casimir force between the parallel plates affected by the fractal additional compactified dimension and surrounding temperature. The stronger thermal influence leads the force to be stronger. The nature of the Casimir force keeps attractive.Comment: 14 pages, 2 figure

    A similarity law for stressing rapidly heated thin-walled cylinders

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    When a thin cylindrical shell of uniform thickness is very rapidly heated by hot high-pressure gas flowing inside the shell, the temperature of material decreases steeply from a high temperature at the inside surface to ambient temperatures at the outside surface. Young's modulus of material thus varies. The purpose of the present paper is to reduce the problem of stress analysis of such a cylinder to an equivalent problem in conventional cylindrical shell without temperature gradient in the wall. The equivalence concept is expressed as a series of relations between the quantities for the hot cylinder and the quantities for the cold cylinder. These relations give the similarity law whereby strains for the hot cylinder can be simply deduced from measured strains on the cold cylinder and thus greatly simplify the problem of experimental stress analysis

    A computer solution for the dynamic load, lubricant film thickness, and surface temperatures in spiral-bevel gears

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    A computer method for determining the dynamic load between spiral bevel pinion and gear teeth contact along the path of contact is described. The dynamic load analysis governs both the surface temperature and film thickness. Computer methods for determining the surface temperature, and film thickness are presented along with results obtained for a pair of typical spiral bevel gears

    Implications of Recent Bˉ0→D(∗)0X0\bar{B}^0\to D^{(*)0}X^0 Measurements

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    The recent measurements of the color-suppressed modes Bˉ0→D(∗)0π0\bar B^0\to D^{(*)0}\pi^0 imply non-vanishing relative final-state interaction (FSI) phases among various Bˉ→Dπ\bar B\to D\pi decay amplitudes. Depending on whether or not FSIs are implemented in the topological quark-diagram amplitudes, two solutions for the parameters a1a_1 and a2a_2 are extracted from data using various form-factor models. It is found that a2a_2 is not universal: ∣a2(Dπ)∣=0.40−0.55|a_2(D\pi)|= 0.40-0.55 and ∣a2(D∗π)∣=0.25−0.35|a_2(D^*\pi)|= 0.25-0.35 with a relative phase of order (50−55)∘(50-55)^\circ between a1a_1 and a2a_2. If FSIs are not included in quark-diagram amplitudes from the outset, a2eff/a1effa_2^{eff}/a_1^{eff} and a2effa_2^{eff} will become smaller. The large value of ∣a2(Dπ)∣|a_2(D\pi)| compared to ∣a2eff(Dπ)∣|a_2^{eff}(D\pi)| or naive expectation implies the importance of long-distance FSI contributions to color-suppressed internal WW-emission via final-state rescatterings of the color-allowed tree amplitude.Comment: 17 pages. The Introduction is substantially revised and the order of the presentation in Sec. 2 is rearranged. To appear in Phys. Re

    On the Casimir effect for parallel plates in the spacetime with one extra compactified dimension

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    In this paper, the Casimir effect for parallel plates in the presence of one compactified universal extra dimension is reexamined in detail. Having regularized the expressions of Casimir force, we show that the nature of Casimir force is repulsive if the distance between the plates is large enough, which is disagree with the experimental phenomena.Comment: 7 pages, 3 figure

    Final stare interaction enhancement effect on the near threshold p\bar p system in B^\pm\to p\bar p \p^\pm decay

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    We discuss the low-mass enhancement effect in the baryon-antibaryon invariant mass in three-body baryonic B decays using final state interactions in the framework of Regge theory. We show that the rescattering between baryonic pair can reproduce the observed mass spectrum.Comment: 7 pages, 11 figure

    Design of Novel Algorithm and Architecture for Gaussian Based Color Image Enhancement System for Real Time Applications

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    This paper presents the development of a new algorithm for Gaussian based color image enhancement system. The algorithm has been designed into architecture suitable for FPGA/ASIC implementation. The color image enhancement is achieved by first convolving an original image with a Gaussian kernel since Gaussian distribution is a point spread function which smoothen the image. Further, logarithm-domain processing and gain/offset corrections are employed in order to enhance and translate pixels into the display range of 0 to 255. The proposed algorithm not only provides better dynamic range compression and color rendition effect but also achieves color constancy in an image. The design exploits high degrees of pipelining and parallel processing to achieve real time performance. The design has been realized by RTL compliant Verilog coding and fits into a single FPGA with a gate count utilization of 321,804. The proposed method is implemented using Xilinx Virtex-II Pro XC2VP40-7FF1148 FPGA device and is capable of processing high resolution color motion pictures of sizes of up to 1600x1200 pixels at the real time video rate of 116 frames per second. This shows that the proposed design would work for not only still images but also for high resolution video sequences.Comment: 15 pages, 15 figure

    Quantum superchemistry in an output coupler of coherent matter waves

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    We investigate the quantum superchemistry or Bose-enhanced atom-molecule conversions in a coherent output coupler of matter waves, as a simple generalization of the two-color photo-association. The stimulated effects of molecular output step and atomic revivals are exhibited by steering the rf output couplings. The quantum noise-induced molecular damping occurs near a total conversion in a levitation trap. This suggests a feasible two-trap scheme to make a stable coherent molecular beam.Comment: 3 figures, accepted by Phys.Rev.A (submitted to prl in July, transferred to pra in Sep. and accepted in Nov.

    A review of personal communications services

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    This article can be accessed from the link below - Copyright @ 2009 Nova Science Publishers, LtdPCS is an acronym for Personal Communications Service. PCS has two layers of meaning. At the low layer, from the technical perspective, PCS is a 2G mobile communication technology operating at the 1900 MHz frequency range. At the upper layer, PCS is often used as an umbrella term that includes various wireless access and personal mobility services with the ultimate goal of enabling users to freely communicate with anyone at anytime and anywhere according to their demand. Ubiquitous PCS can be implemented by integrating the wireless and wireline systems on the basis of intelligent network (IN), which provides network functions of terminal and personal mobility. In this chapter, we focus on various aspects of PCS except location management. First we describe the motivation and technological evolution for personal communications. Then we introduce three key issues related to PCS: spectrum allocation, mobility, and standardization efforts. Since PCS involves several different communication technologies, we introduce its heterogeneous and distributed system architecture. IN is also described in detail because it plays a critical role in the development of PCS. Finally, we introduce the application of PCS and its deployment status since the mid-term of 1990’s.This work was supported in part by the National Natural Science Foundation of China under Grant No. 60673159 and 70671020; the National High-Tech Research and Development Plan of China under Grant No. 2006AA01Z214, and the Engineering and Physical Sciences Research Council (EPSRC) of UK under Grant EP/E060722/1
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