OSCILLATION OF A FORCED SECOND ORDER NONLINEAR EQUATION

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A bivariate exponential distribution arising in random geometry

Summary In this paper a new bivariate exponential distribution, arising naturally in the theory of Poisson line processes, is studied. The distribution has some interesting and useful properties which renders it suitable for use in statistical modelling work. It is presented in the spirit of adding to the repertoire of bivariate exponential forms. It joins other models, such as those of Downton (1970,J. R. Statist. Soc., B,32, 408–417), Marshall and Olkin (1967,J. Appl. Prob.,4, 291–302) and Nagao and Kadoya (1971,Bulletin of the Disaster Prevention Research Institute,20, 3, 183–215), which have their origins in the theory of stochastic processes.     

Differential FBG sensor for temperature-compensated high-pressure (or displacement) measurement

A differential fiber Bragg grating (FBG) sensor with a free active element bulk-modulus for high-pressure (or displacement) measurement is presented. Based on the differential measurement method and an isosceles triangle cantilever structure, problems of cross-sensitivity and chirped signal in FBG sensor are improved both theoretically and experimentally. Preliminary experiments indicate that temperature-compensated measurement results agree well with the theoretical analysis. Displacement measurement sensitivity is 1.75 pm/μm, and the estimated pressure measurement resolution can reach 0.27 MPa in case the wavelength shift measurement resolution is 0.01 nm.     

The effect of noise on the dirac phase of electron in the presence of screw dislocation

The effect of noise on the Dirac phase of electron in the presence of screw dislocation is studied. An uncorrelated noise, which coincides with the nature of thermal fluctuations, is adopted. Results indicate that the Dirac phase is robust against the existing noise in the system.     

First-order Raman scattering in cylindrical wurtzite nanowire

We have presented a theoretical study on electron resonant Raman scattering (ERRS) process associated with the bulk longitudinal optical (LO), surface optical (SO) and quasi-confined (QC) phonon modes in a free-standing wurtzite nanowire (NW). We consider the Fröhlich electron–phonon interaction in the framework of the dielectric continuum model. Numerical calculations on the GaN material reveal that differential cross-section (DCS) is sensitive to the wire size. The bulk LO and high-frequency quasi-confined (QC₊) phonons make main contributions to the DCS and the impact of the SO phonon can be negligible in the ERRS process. Moreover, scattering intensity of the bulk LO phonon is strongly enhanced as the incident photon energy approaches the energy band-gap of the GaN.     

Information,Quantum Mechanics,and Gravity

This is a basically expository article, with some new observations, tracing connections of the quantum potential to Fisher information, to Kähler geometry of the projective Hilbert space of a quantum system, and to the Weyl-Ricci scalar curvature of a Riemannian flat spacetime with quantum matter.Á Denise     

光纤连接器端面几何参量自动测量仪

报道了一种高精度测量光纤连接器端面几何参量的自动测量仪。叙述了光纤连接器的端面几何参量的测量原理。由光纤连接器端面形貌和纤芯中心坐标,可以高精度得到曲率半径、顶点偏移量、端面倾斜角和光纤高度等影响连接器性能的关键端面几何参量。该仪器体积小,自动化程度高,用户界面友好,使用方便,可测量物理接触、角度式物理接触等类型的光纤连接器端面几何参量。实际测量证明,该测量仪有很好的重复测量精度。该测量仪与美国Dorc公司ZX-1 mini PMS测量仪和Norland公司NC3000测量仪相比,测量精度水平相当。该仪器样机已通过华东国家计量测试中心的测试。     

Geodesic connectedness of the causal completion in the Lorentzian geometry

We consider the topology of the BS causal completion, and show that it is not distorted in the causal direction. Using this result, we show that the causal completion with spacelike causal boundary in the sense of the BS construction satisfies the formal definition of the global hyperbolicity. We also show that any two causally related points in the causal completion can be connected by a causal geodesic.