SITE GAINS AND ITS ESTIMATION METHOD OF A LIGHTNING LOCATION SYSTEM

We discuss a new concept in lightning location system (LLS). Specitically,it is anoptimum method of lightning signal strength and a parameterization method of the site gaincurve estimation in LLS. Site gain correction curves for all DFs for 1989 were found byusing the data observed in an LLS of three direction finders (DFs) in Beijing region. Theresult shows that the curves, as a function of measured bearing, only include the one- andtwo-cycle sinusoidal components. It also indicates that the larger the site errors which DFhas, the larger the amplitude of the site gain curve. In this LLS, the ranges of site gainare 0.9--1.2, 0.85--1.05, 0.9--1.1 for DF1, DF2 and DF3 respectively. For discussion, we suggested a model for site gains due to dipole radiation. This modelcan be used to reasonably explain the characteristics of structure of site gain curves.     

Scattering of plane acoustic waves by a transversely isotropic cylindrical shell—application to material characterization

Scattering of obliquely incident plane acoustic wave by an air-filled, transversely isotropic cylindrical shell immersed in water is investigated theoretically and experimentally. The normal mode expansion technique is employed for analyzing the scattering field, and then resonance modes of the shell appearing in modal scattering form functions are identified performing the resonance scattering analysis. Dispersion curves for Sholte-Stoneley, SH and Lamb waves are obtained and their characteristics are interpreted. Calculated backscattering and resonance spectra as well as dispersion curves are compared with those from ultrasonic experiments for two composite samples having the same nominal composition but fabricated under different conditions. Sensitive change of the dispersion curves is observed for both normal and oblique incidences, which demonstrates the feasibility of systematic inverse evaluation of damage or elastic constants of the composite shell using data from the acoustic scattering measurements.     

Precession and Interference in the Aharonov–Casher and Scalar Aharonov–Bohm Effects

The ideal scalar Aharonov–Bohm (SAB) and Aharonov–Casher (AC) effect involve a magnetic dipole pointing in a certain fixed direction: along a purely time dependent magnetic field in the SAB case and perpendicular to a planar static electric field in the AC case. We extend these effects to arbitrary direction of the magnetic dipole. The precise conditions for having nondispersive precession and interference effects in these generalized set ups are delineated both classically and quantally. Under these conditions the dipole is affected by a nonvanishing torque that causes pure precession around the directions defined by the ideal set ups. It is shown that the precession angles are in the quantal case linearly related to the ideal phase differences, and that the nonideal phase differences are nonlinearly related to the ideal phase differences. It is argued that the latter nonlinearity is due to the appearance of a geometric phase associated with the nontrivial spin path. It is further demonstrated that the spatial force vanishes in all cases except in the classical treatment of the nonideal AC set up, where the occurring force has to be compensated by the experimental arrangement. Finally, for a closed space-time loop the local precession effects can be inferred from the interference pattern characterized by the nonideal phase differences and the visibilities. It is argued that this makes it natural to regard SAB and AC as essentially local and nontopological effects.     

Noise effects of reducing traffic flow through a Spanish city

Towards the end of 1999, the building of one of the main communication routes in Spain was finished, the A-3 motorway, which connects Madrid and Valencia. So far, this road was running through the town Motilla de Palancar, province of Cuenca. The opening of the last section of the motorway on 3 December 1999, re-routes all the traffic passing through the town. This study makes a comparative of the noise levels before and after the opening of the motorway that goes through Motilla de Palancar.     

五象限法声源自动跟踪器

介绍由两同心圆组成的等投影面积五象限声－电测量装置的工作原理。当声波与声－电转换器的主要测象限垂直时，其声波在主要测象限内产生的声－电电压最强。根据声－电电压的变化大小来确定声源的方向，实现自动跟踪。     

Influence of Data Acquisition Environment on Accuracy of Acoustic Voice Quality Measurements

Accuracy of acoustic voice analysis is influenced by the quality of recording. Lately, articles have suggested that soundcards perform equivalently to specialized professional-grade data acquisition (DA) systems. The purpose of this study was to investigate the influence of DA environment (DA system and microphone) on acoustic voice quality measurement (VQM) while balancing for gender, age, intersubject and intrasubject variability, and analysis software. More specifically, the relative performance of different hardware environments and the relationship between their technical characteristics and VQM performance was investigated. The discretization error and the effective dynamic range of the different DA environments were measured. We used 3 software systems to record and measure separately 2000 acoustic samples of sustained phonation for fundamental frequency, jitter, and shimmer. Analyses of variance (ANOVA) were performed with these parameters as the dependent variables. The results of the study suggested that professional-grade DA hardware is strongly recommended to provide accurate and valid voice assessment. The fundamental frequency measurement differences across DA environments were highly correlated to the discretization error (r=1.00), whereas jitter and shimmer were highly correlated to the effective dynamic range of the DA environments (r=-0.68 and r=-0.86, respectively).     

The aΔg→XΣg magnetic dipole transition of S2

Emission spectra of the 0-0 band of the a¹Δ_g→X³Σ⁻_g magnetic dipole transition of S₂ have been observed in the near-infrared spectral region near 4400 cm⁻¹. The S₂ molecules were generated in a fast-flow system by passing S_x or S₂Cl₂ vapor in Ar carrier gas through a microwave discharge and were excited by electronic-to-electronic energy transfer from metastable singlet oxygen O₂(a¹Δ_g). Medium-resolution spectra of the b¹Σ⁺_g→X³Σ⁻_g and a¹Δ_g→X³Σ⁻_g transitions of S₂ were measured with a Fourier-transform spectrometer. By comparing the bandshape of the 0-0 band of the a→X system with a computer simulation calculated with literature data of the rotational constants of the X and a states, the origin of the 0-0 band was determined to be ν₀=4394.25±0.2 cm⁻¹.     

混合结构的闭环光纤陀螺研究

提出并研制了混合结构的闭环光纤陀螺系统。详细分析了该系统的结构特点、信号检测方法以及反馈信号对系统的影响。该系统具有低损耗、长期低漂移特性。实现了３００ｄｅｇ．／ｓ的动态范围及小于３００×１０－６的线性误差。     

Dipole-Dipole Interaction and the Directional Motion of Brownian Motors

The electric field of the microtubule is calculated according to its dipole distribution. The conformationalchange of a molecular motor is described by the rotation ofa dipole which interacts with the microtubulc. The mricalsimulation for the particle current shows that this interaction helps to produce a directional motion along the microtubule.And tte average displacement executes step changes that resemble the experimental result for kinesin motors.