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%。     

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     

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.     

非线性反馈移位寄存器串联分解唯一性探讨

非线性反馈移位寄存器(NFSR)是目前序列密码研究的热点问题之一。假定一个NFSR可以分解为更低级数NFSR的串联,该文讨论此分解是否唯一的问题。首先,对线性反馈移位寄存器(LFSR)而言,其串联分解等价于二元有限域F2上单变元多项式的分解,因而是唯一的。其次,针对给定NFSR可以分解为更低级数NFSR到LFSR串联的情形,该文给出了此NFSR具有这样分解的一个充分必要条件,并据此指出所有这样分解中级数最大的LFSR是唯一的。该文的最后构造了一类反例,此类反例表明对一般情形而言,NFSR的串联分解并不唯一。     

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.     

Enumeration of trees of a graph

The enumeration of the trees having the same number of edges as the rank of the characteristic submatrix Bf12 of a graph by a computer program is described, using the fact that the non-singular submatrices of the characteristic part of the fundamental cutset matrix relative to a tree uniquely correspond to the other trees of a graph.     

Control ability of spin coating planarization of resist filmand optimal control of developers

The issue of how to transfer a pattern onto a wafer during photolithography is very important. Normally, the resist is treated as a pattern-transferring medium. Such a medium should have a very smooth surface to reduce the focus error. In this experiment, spin coating is used. The velocity of the center differs from that of the outer edges of a rotating disk, so a perfectly smooth surface cannot be obtained. Therefore, resist temperature, cooling temperature, heating temperature, cup temperature, cup humidity and exhaust pressure were controlled to eliminate this imperfection to yield an acceptable error. A lower cooling temperature yields a thicker center, such that the surface of the wafer protrudes at the center. A lower cooling temperature also corresponds to a thicker center, with the same effect. The cup temperature was set to the cooling temperature so that thickness distribution would be the same as. A higher heating temperature yields a thinner wafer. Higher humidity yields a thinner wafer.     

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.     

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.     

Enumeration of all trees of a graph

The nonsingular submatrices of the characteristic part of the fundamental cutset matrix relative to a tree uniquely correspond to the other trees of a graph G. Using this principle, a method of listing, without duplication, all trees of G is presented. For implementation of the method on a computer, a large memory is not required.     

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.     

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.     

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.     

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.     

Modeling of TE cooling of pump lasers

The pump laser is a key module in optical amplifiers for long-haul fiber optic telecommunication systems. Its core component is a semiconductor laser diode mounted on a thermoelectric cooler. It is of crucial importance to maintain the laser diode temperature in a narrow range during operation in order to achieve satisfactory performance and reliability of the module. Therefore, a proper thermal management solution is very important to the pump module design. In this paper, a three-dimensional finite element analysis on thermoelectric cooling is presented. The modeling results show good agreement with the experimental results obtained by IR thermometry. When the heat source has a high power dissipation and a small footprint compared to the size of the heat sink, the spreading resistance becomes important. To analyze the maximum performance of the heat sink, both single and dual pump module configurations are considered.     

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.     

The Effect of Bandlimiting Filters on Probability of Error of MSK

Minimum Shift Keying (MSK) is a method of modulation which can be viewed as a special case of Frequency Shift Keying or a special form of Offset Quadrature Phase Shift Keying; therefore, it can be detected either by a discriminator or with a pair of matched filters. In the latter case, the system is optimal, provided there are no bandlimiting filters in the transmitter and receiver. These filters introduce intersymbol interference and hence degrade the performance of the system. In this paper we investigate analytically the effect of a bandlimiting filter in the receiver on the error probability of the system, presenting numerical results when that filter is of the Butterworth type. It is shown that a very simple suboptimal detector outperforms the matched filter detector so long as2W/R_{b} < 1.3, where Rbis the bit rate andWis the single sided 3 dB bandwidth of the bandlimiting filter.     

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.     

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.     

Determination of the age distribution of sea ice from Lagrangianobservations of ice motion

A procedure for monitoring the local age distribution of the Arctic sea ice cover is presented. The age distribution specifies the area covered by ice in different age classes. In the authors' approach, a regular array of grid points is defined initially on the first image of a long time series, and an ice tracker finds the positions of those points in all subsequent images of the series. These Lagrangian points mark the corners of a set of cells that move and deform with the ice cover. The area of each cell changes with each new image or time step. A positive change indicates that ice in a new age class was formed in the cell. A negative change is assumed to have ridged the youngest ice in the cell, reducing its area. The ice in each cell ages as it progresses through the time series. The area of multiyear ice in each cell is computed using an ice classification algorithm. Any area that is not accounted for by the young ice or multiyear ice is assigned to a category of older first-year ice. The authors thus have a fine age resolution in the young end of the age distribution, and coarse resolution for older ice. The age distribution of the young ice can be converted to a thickness distribution using a simple empirical relation between accumulated freezing-degree days and ice thickness, or using a more complicated thermodynamic model. The authors describe a general scheme for implementing this procedure for the Arctic Ocean from fall freeze-up until the onset of melt in the spring. The concept is illustrated with a time series of five ERS-1 SAR images spanning a period of 12 days. Such a scheme could be implemented with RADARSAT SAR imagery to provide basin-wide ice age and thickness information