CCD检测激光束折散宽度及在柱面镜曲率半径测量中的应用

本文介绍一种检测柱面镜曲率半径方法。该方法的基本原理是利用准直激光束通过柱面镜产生扇形折射光束,折射光束散开的宽度同柱面镜曲率半径直接相关。利用线阵CCD和微机数据处理系统,可以高精度确定折散光束宽度,进而确定出柱面半径。将这种检测技术应用于汽车灯配光镜柱面半径测量,测量精度达到2%。     

A Paraxial approximation of the problem of formation of nonparaxial conical and toroidal electron beams of an arbitrary cross section

A paraxial solution is constructed for the problem of calculation of forming electrodes for non-paraxial cuts from converging and diverging flows in a spherical diode and a Meltzer flow with circular paths. The solution is expressed in elementary functions for the case of a cone. For example, computations for a square on a sphere (the first approximation of the approximation of a contour) and a toroid with a circular cross section are presented.     

Capacitance of transmission line of parallel cylinders in thepresence of dielectric coating

The paper presents a method for the evaluation of variation of capacitance of a dielectric coated two-wire line of parallel cylinders, each of unit radius with a change in thickness of the dielectric along the radial direction. A conformal transformation is used to transform the conductor and dielectric boundaries to appropriate contours extending over a fixed region along the imaginary axis in the transformed plane. Approximating the continuous curve obtained through transformation of dielectric boundaries by a very large number of discrete steps, the expression for the capacitance is derived in the form of a definite integral. Numerical data on capacitance as a function of width of the dielectric in the absence and presence of a conducting ground plane are presented     

Specific features of photoelectric properties of layered films of amorphous hydrogenated silicon

Temperature dependences of photoconductivity of layered and conventional undoped films of amorphous hydrogenated silicon have been studied within a wide range of temperatures (130–420 K) and illumination intensities (0.1–60 mW cm⁻²). It is established that a higher photosensitivity of layered films compared with conventional films is governed by a low dark conductivity of layered films as a consequence of a deeper position of the equilibrium Fermi level in the band gap and the absence of temperature quenching of photoconductivity in these films. It is shown that these specific features of electrical and photoelectric properties of layered films can be attributed to a low concentration of silicon dangling bonds in comparison with the concentration of oxygen-related acceptor centers, which feature a larger capture coefficient for holes.     

一种红外热像仪模拟训练器的设计

介绍了红外热像仪模拟训练器需求产生的背景,提出了一种基于SOPC的红外热像仪模拟训练器设计思路,并用基于FPGA芯片的NIOS嵌入式系统实现了该样品.该模拟训练器样品具有低成本、低功耗、高仿真度的特点.     

Experimental study of burnout of microwave bipolar transistors under action of a series of electric pulses

Burnout of silicon transistors under the action of a periodic train of electric pulses is experimentally studied. A numerical model and a more physically demonstrative analytical model of the pulse-to-pulse heat accumulation are in qualitative and, to a certain extent, quantitative agreement with the measured results. It is demonstrated that catastrophic failure takes place at a melting point of silicon but additional heat is needed for melting of low-temperature eutectics.     

Analysis of absorbing characteristics of thin-type absorber forgeneralized conditions of incident wave

The treatment of a thin absorber as a boundary condition, taking the arbitrary thickness of the absorber into account, is presented. To verify this approach, the equivalent circuit is applied to the terminal model of a coaxial line and rectangular waveguides. Its validity is verified by changing the medium constant, frequency, and angle and polarization of the obliquely incident wave. To illustrate the application of the approach to a complicated structure, the reflecting and scattering characteristics of an aircraft model are presented     

The k-Diameter of a Kind of Circulant Graph

The terminology and notion in this paper are similar to Ref.[1], all graphs discussed here are finite and simple. The diameter d(G) of a graph G is the maximal distance between pairs of vertices of G. The connectivity of G is the minimum number of vertices needed to be removed in order to disconnect the graph. When a network is modeled as a graph,a vertex represents a node of processor (or a station) and an edge between two vertices is the link (or connection) between those two processors. I…     

Generation of surrogate models of Pareto-optimal performance trade-offs of planar inductors

Systematic design methodologies for wireless transceivers require an efficient design of integrated inductors. Early availability of feasible trade-offs between inductance, quality factor, self-resonance frequency and area, is a key enabler towards the improvement of such design methodologies. This paper introduces such an approach in two steps. First, a Pareto-optimal performance front of integrated inductors is generated by embedding a performance evaluator into a multi-objective optimization tool. Then, starting from the optimal front samples, a surrogate model of the performance front is obtained. Experimental results in a 0.35-μm CMOS technology are provided.     

数字式甲烷测量仪器示值测量结果不确定度评定

作者在建立计量标准时,将多个规程囊括到一个标准项目中,节省人力和物力.简单的介绍了合并后的不确定度分析及评定过程.     

Modeling of magnetic field stimulation of bent neurons

The authors consider a simple model of magnetic stimulation of a long bent neuron located in a semi-infinite volume conductor with a planar interface. It is shown that the stimulating coil characteristics (size, shape and location) and the neuron shape affect the location of the stimulation. The activating function, defined as the electric field derivative along the neuron, has two components. One component depends on the derivative of the electric field along the straight section of the neuron, and the other on the field magnitude. The maximal stimulation point is at the bent part of the nerve and its position depends on the nerve shape and coil parameters. The analysis also has shown a better performance (a stronger stimulus) for a double-circular (figure eight) coil than for a double-square coil     

Analysis of target response of FM-CW radar

Detection and location of different targets buried in ground or constructional walls depends to a great extent on the knowledge of expected target return response. The analysis of the target-radar response for FM-CW ground probing radar is performed with the aid of a signal flow diagram relating the target response and the radar performance. A plane wave model for the radar radiated electromagnetic waves is adopted and the analysis is carried out for two typical targets; a finite thickness slab and a sphere. Computed returns based on this analysis are compared with those obtained experimentally from a 1-2 GHz FM-CW radar scheme and a very close agreement is found. A computational study is conducted on the response of planar target model, and important conclusions are reached upon relevant to ground probing problem.     

Analysis of efficiency of magnetic stimulation

Magnetic stimulation can activate excitable tissues noninvasively. However, this method requires high energy to operate and can produce equipment heat that leads to inefficient stimulation. In this study, a comprehensive optimization of efficiency for magnetic stimulation has been conducted. A total of 16 781 coil designs were tested in order to determine the optimal coil geometry and inductance for neural excitation. Induced electric fields were calculated to find the optimal stimulation site (OSS) of a given coil. The threshold energy of a magnetic pulse for neural excitation was then calculated based on the transmembrane responses of a nerve model. Simulation results show that there exists an optimal inductance, as a consequence of an optimal pulse duration, corresponding to a minimum threshold energy. A longer pulse width is required to obtain the maximum efficiency for axons with slower membrane dynamics, a longer coil-to-fiber distance, and greater values of resistance (R) and capacitance (C) of the resistance-inductance-capacitance circuit. The optimal geometry features a minimum coil height, suggesting a flat coil design for optimal efficiency. The dimension of the optimal coil design increases with the coil-to-fiber distance. Moreover, the cloverleaf design achieves the highest efficiency for infinitely long fibers whereas the butterfly design is optimal for terminating or bending fibers.     

Measurement of broadening of pulses in glass fibres

In the letter is reported the measurement of broadening of pulses in glass fibres using a GaAs injection laser diode as an emitter and a germanium photodiode as a detector. We found broadening of about 5 ps/m for a multimode fibre and 0.6 ps/m for a self-focusing glass fibre.     

Linear coefficients of equation of motion of a drift electron

A simple method of calculating the friction coefficient and the restraining coefficient of a linear equation of motion of a drift electron in an isotropic medium is presented. This new method is applied for an electron in the high-field domain in a magnetically biased Gunn diode as an example.     

Determination of Range of Effectiveness of Transmitter Harmonic Output Filtering

The actual effectiveness of a transmitter harmonic filter, when inserted in the transmission line to the antenna, can vary over a wide range which extends both above and below the standard characteristic-impedance circuit insertion-loss values. The location in this range varies with interconnecting transmission line lengths. An example discussed here shows that the actual insertion loss of a 60 db filter could be anywhere between 10 db and 94 db. Furthermore, the transmitter harmonic power delivered to an antenna, in the absence of a filter, can also vary with the length of the interconnecting transmission line. These effects are produced by changes in mismatch loss which occur as the length of interconnecting transmission line is varied. The purpose of this paper is to show how to determine the range of variation of such effects. Included are some sample calculations and the results of limited experimental tests.     

SAR图像特征数据立方体的构造

图像数据立方体的建立有助于图像数据的基于视觉内容的分析和多种知识的挖掘,包括汇总、分类、比较、关联和聚类.图像数据立方体对于图像分析是很有用的模型.实现一个维数很大的数据立方体是很困难的.但如果维数不够,则会使图像的建模范围过于粗糙、受到限制和不精确的扩展.因此,如何设计出既能满足效率要求,又能有足够的表达能力的图像数据立方体,是个亟待研究的问题.文中借鉴前人的思路和方法,构造了SAR图像立方体的模型.     

New Solution of a Problem of the Dipole Radiation and Quantum Properties of the Electromagnetic Field

The Planck's formula connecting an energy and frequency of quantum is known more than half-century. However there are obscure appearances and processes defining nature of the electromagnetic field quantum and reducing to this formula. The path to a solution of these problems uncloses a new solution of a problem of the dipole radiation. Hertz obtained the first solution describing of a dipole radiator field. However this solution and all subsequent ones are incomplete and they not give a complete exposition of the dipole field. In this paper we will show a possibility of complete exposition of a dipole radiator field by using both a complete set of the electromagnetic field equations obtained in [1] and also solution for a radiator of a longitudinal electromagnetic wave. The obtained solution is of great importance in understanding of a nature of quantum properties of electromagnetic field. The work contains series of assumptions about existence of some constants characterizing electromagnetic field.     

多棒平行平面腔动态工作特性的研究

基于等价腔方法,将高功率固体激光器使用的二棒平行平面腔的结果推广到多棒平行平面腔。推导出了g*参数和等价腔长的解析表达式。对这类光腔的动态工作特性做了详细分析,并给出了数值计算例。研究表明,对两类多棒对称平行平面腔,在g*参数图上的动态特性曲线是过原点的一条直线。若多棒的热焦距有小的偏差,特性曲线不再是直线。然而,用适当调节镜和棒以及棒间距离的方法可以使特性曲线重新成为一条直线。因而采用这种方法可以补偿棒的热焦距偏差,给出了有关的数学公式。     

Optimal algorithm of panoramic sewing of images in the presence of inaccuracies of mutual positioning

An optimal algorithm of panoramic sewing of images in the presence of alignment errors has been synthesized on the basis of the criterion of a posteriori probability maximum. It was shown that in case of stationary images and equal a priori probabilities of image shifts, the shift estimate is determined by a maximum of the cross-correlation function of a pair of overlapping images. The sewing algorithm proposed was illustrated by the sewing of real images.