29,774 research outputs found

    New line-interactive UPS system with DSP-based active power-line conditioning

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    On the constrained KP hierarchy

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    An explanation for the so-called constrained hierarhies is presented by linking them with the symmetries of the KP hierarchy. While the existence of ordinary symmetries (belonging to the hierarchy) allows one to reduce the KP hierarchy to the KdV hierarchies, the existence of additional symmetries allows to reduce KP to the constrained KP.Comment: 7pp, LaTe

    Improved real-time imaging spectrometer

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    An improved AOTF-based imaging spectrometer that offers several advantages over prior art AOTF imaging spectrometers is presented. The ability to electronically set the bandpass wavelength provides observational flexibility. Various improvements in optical architecture provide simplified magnification variability, improved image resolution and light throughput efficiency and reduced sensitivity to ambient light. Two embodiments of the invention are: (1) operation in the visible/near-infrared domain of wavelength range 0.48 to 0.76 microns; and (2) infrared configuration which operates in the wavelength range of 1.2 to 2.5 microns

    Use of FBG optical sensors for structural health monitoring: Practical application

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    This paper describes the development of FBG Optical sensors for their practical application on structural health monitoring. The sensors were installed on the Tsing Ma Bridge for a trial run. The results using FBG sensors were in excellent agreement with those acquired by the bridge WASHMS

    XOR multiplexing technique for nanocomputers

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    In emerging nanotechnologies, due to the manufacturing process, a significant percentage of components may be faulty. In order to make systems based on unreliable nano-scale components reliable, it is necessary to design fault-tolerant architectures. This paper presents a novel fault-tolerant technique for nanocomputers, namely the XOR multiplexing technique. This hardware redundancy technique is based on a numerous duplication of faulty components. We analyze the error distributions of the XOR multiplexing unit and the error distributions of multiple stages of the XOR multiplexing system, then compare them to the NAND multiplexing unit and the NAND multiplexing multiple stages system, respectively. The simulation results show that XOR multiplexing is more reliable than NAND multiplexing. Bifurcation theory is used to analyze the fault-tolerant ability of the system and the results show that XOR multiplexing technique has a high fault-tolerant ability. Similarly to the NAND multiplexing technique, this fault-tolerant technique is a potentially effective fault tolerant technique for future nanoelectronics

    On Goldstone bosons decoupling from high-lying hadrons

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    In this paper, we discuss a decoupling of the Goldstone bosons from highly excited hadrons in relation to the restoration of chiral symmetry in such hadrons. We use a generalised Nambu-Jona-Lasinio model with the interaction between quarks in the form of an instantaneous Lorentz-vector confining potential. This model is known to provide spontaneous breaking of chiral symmetry in the vacuum via the standard selfenergy loops for valence quarks. For highly excited hadrons, where the typical momentum of valence quarks is large, the loop contributions represent only a small correction to the chiral-invariant classical contributions and asymptotically vanish. Consequently the chiral symmetry violating Lorentz-scalar dynamical mass of quarks vanishes. Then the conservation of the axial vector current in the chiral limit requires, via the Goldberger-Treiman relation, that the valence quarks decouple from the Goldstone boson. As a consequence, the whole hadron decouples from the Goldstone boson as well, which implies that its axial constant also vanishes.Comment: RevTeX4, 21 pages, 5 Postscript figures, uses epsfig.sty, new chapter with numerical estimates added, to appear in Phys.Rev.

    Chiral symmetry restoration in excited hadrons, quantum fluctuations, and quasiclassics

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    In this paper, we discuss the transition to the semiclassical regime in excited hadrons, and consequently, the restoration of chiral symmetry for these states. We use a generalised Nambu-Jona-Lasinio model with the interaction between quarks in the form of the instantaneous Lorentz-vector confining potential. This model is known to provide spontaneous breaking of chiral symmetry in the vacuum via the standard selfenergy loops for valence quarks. It has been shown recently that the effective single-quark potential is of the Lorentz-scalar nature, for the low-lying hadrons, while, for the high-lying states, it becomes a pure Lorentz vector and hence the model exhibits the restoration of chiral symmetry. We demonstrate explicitly the quantum nature of chiral symmetry breaking, the absence of chiral symmetry breaking in the classical limit as well as the transition to the semiclassical regime for excited states, where the effect of chiral symmetry breaking becomes only a small correction to the classical contributions.Comment: RevTeX4, 20 pages, 4 Postscript figures, uses epsfig.sty, typos correcte

    Charmless Three-body Decays of B Mesons

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    Charmless 3-body decays of B mesons are studied in the framework of the factorization approach. The nonresonant contributions arising from BP1P2B\to P_1P_2 transitions are evaluated using heavy meson chiral perturbation theory (HMChPT). The momentum dependence of nonresonant amplitudes is assumed to be in the exponential form e^{-\alpha_{NR}} p_B\cdot(p_i+p_j)} so that the HMChPT results are recovered in the soft meson limit pi,pj0p_i, p_j\to 0. In addition, we have identified another large source of the nonresonant signal in the matrix elements of scalar densities, e.g. , which can be constrained from the decay Bˉ0KSKSKS\bar B^0\to K_SK_SK_S or BKKSKSB^-\to K^-K_SK_S. The intermediate vector meson contributions to 3-body decays are identified through the vector current, while the scalar meson resonances are mainly associated with the scalar density. Their effects are described in terms of the Breit-Wigner formalism. Our main results are: (i) All KKK modes are dominated by the nonresonant background. The predicted branching ratios of K+KKS(L)K^+K^-K_{S(L)}, K+KKK^+K^-K^- and KKSKSK^-K_SK_S modes are consistent with the data within errors. (ii) Although the penguin-dominated B0K+KKSB^0\to K^+K^-K_{S} decay is subject to a potentially significant tree pollution, its effective sin2β\sin 2\beta is very similar to that of the KSKSKSK_SK_SK_S mode. However, direct CP asymmetry of the former, being of order -4%, is more prominent than the latter. (iii) For BKππB\to K\pi\pi decays, we found sizable nonresonant contributions in Kπ+πK^-\pi^+\pi^- and Kˉ0π+π\bar K^0\pi^+\pi^- modes, in agreement with the Belle measurements but larger than the BaBar result.Comment: 39 pages, 2 figures, version to appear in PR
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