260,102 research outputs found

    Symmetric Composite Laminate Stress Analysis

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    It is demonstrated that COSMIC/NASTRAN may be used to analyze plate and shell structures made of symmetric composite laminates. Although general composite laminates cannot be analyzed using NASTRAN, the theoretical development presented herein indicates that the integrated constitutive laws of a symmetric composite laminate resemble those of a homogeneous anisotropic plate, which can be analyzed using NASTRAN. A detailed analysis procedure is presented, as well as an illustrative example

    Quantum speed limit for relativistic spin-0 and spin-1 bosons on commutative and noncommutative planes

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    Quantum speed limits of relativistic charged spin-0 and spin-1 bosons in the background of a homogeneous magnetic field are studied on both commutative and oncommutative planes. We show that, on the commutative plane, the average speeds of wave packets along the radial direction during the interval in which a quantum state evolving from an initial state to the orthogonal final one can not exceed the speed of light, regardless of the intensities of the magnetic field. However, due to the noncommutativity, the average speeds of the wave packets on noncommutative plane will exceed the speed of light in vacuum provided the intensity of the magnetic field is strong enough. It is a clear signature of violating Lorentz invariance in quantum mechanics region.Comment: 8 pages, no figures. arXiv admin note: text overlap with arXiv:1702.0316

    Measuring dark energy with the EisoEpE_{\rm iso}-E_{\rm p} correlation of gamma-ray bursts using model-independent methods

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    In this paper, we use two model-independent methods to standardize long gamma-ray bursts (GRBs) using the EisoEpE_{\rm iso}-E_{\rm p} correlation, where EisoE_{\rm iso} is the isotropic-equivalent gamma-ray energy and EpE_{\rm p} is the spectral peak energy. We update 42 long GRBs and try to make constraint on cosmological parameters. The full sample contains 151 long GRBs with redshifts from 0.0331 to 8.2. The first method is the simultaneous fitting method. The extrinsic scatter σext\sigma_{\rm ext} is taken into account and assigned to the parameter EisoE_{\rm iso}. The best-fitting values are a=49.15±0.26a=49.15\pm0.26, b=1.42±0.11b=1.42\pm0.11, σext=0.34±0.03\sigma_{\rm ext}=0.34\pm0.03 and Ωm=0.79\Omega_m=0.79 in the flat Λ\LambdaCDM model. The constraint on Ωm\Omega_m is 0.55<Ωm<10.55<\Omega_m<1 at the 1σ\sigma confidence level. If reduced χ2\chi^2 method is used, the best-fit results are a=48.96±0.18a=48.96\pm0.18, b=1.52±0.08b=1.52\pm0.08 and Ωm=0.50±0.12\Omega_m=0.50\pm0.12. The second method is using type Ia supernovae (SNe Ia) to calibrate the EisoEpE_{\rm iso}-E_{\rm p} correlation. We calibrate 90 high-redshift GRBs in the redshift range from 1.44 to 8.1. The cosmological constraints from these 90 GRBs are Ωm=0.230.04+0.06\Omega_m=0.23^{+0.06}_{-0.04} for flat Λ\LambdaCDM, and Ωm=0.18±0.11\Omega_m=0.18\pm0.11 and ΩΛ=0.46±0.51\Omega_{\Lambda}=0.46\pm0.51 for non-flat Λ\LambdaCDM. For the combination of GRB and SNe Ia sample, we obtain Ωm=0.271±0.019\Omega_m=0.271\pm0.019 and h=0.701±0.002h=0.701\pm0.002 for the flat Λ\LambdaCDM, and for the non-flat Λ\LambdaCDM, the results are Ωm=0.225±0.044\Omega_m=0.225\pm0.044, ΩΛ=0.640±0.082\Omega_{\Lambda}=0.640\pm0.082 and h=0.698±0.004h=0.698\pm0.004. These results from calibrated GRBs are consistent with that of SNe Ia. Meanwhile, the combined data can improve cosmological constraints significantly, comparing to SNe Ia alone. Our results show that the EisoEpE_{\rm iso}-E_{\rm p} correlation is promising to probe the high-redshift universe.Comment: 10 pages, 6 figures, 4 table, accepted by A&A. Table 4 contains calibrated distance moduli of GRB

    A note on modular forms and generalized anomaly cancellation formulas

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    By studying modular invariance properties of some characteristic forms, we prove some new anomaly cancellation formulas which generalize the Han-Zhang and Han-Liu-Zhang anomaly cancellation formula

    Constraining the bulk Lorentz factor from the photosphere emission

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    We propose a direct and model-independent method to constrain the Lorentz factor of a relativistically expanding object, like gamma-ray bursts. Only the measurements, such as thermal component of the emission, the distance and the variable time scale of the light curve, are used. If the uncertainties are considered, we will obtain lower limits of the Lorentz factor instead. We apply this method to GRB 090618 and get a lower limit of the Lorentz factor to be 22. The method can be used to any relativistically moving object, such as gamma-ray bursts, blazars, and soft gamma-ray repeaters, providing the thermal component of the emission being observed.Comment: 10 pages, 1 figur

    Mission analysis data for inclined geosynchronous orbits, part 1

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    Data needed for preliminary design of inclined geosynchronous missions are provided. The inertial and Earth fixed coordinate systems are described, as well as orbit parameters and elements. The complete family of geosynchronous orbits is discussed. It is shown that circular inclined geosynchronous orbits comprise only one set in this family. The major orbit perturbation and their separate effects on the geosynchronous orbit are discussed. Detailed information on the orbit perturbation of inclined circular geosynchronous orbits is given, with emphasis on time history data of certain orbital elements. Orbit maintenance delta velocity (V) requirements to counteract the major orbit perturbations are determined in order to provide order of magnitude estimates and to show the effects of orbit inclination on delta V. Some of the considerations in mission design for a multisatellite system, such as a halo orbit constellation, are discussed
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