P-N结中的一个新电容模型——光生电荷的常分布电容(英文)

This paper initially suggests a new capacitance model, i.e., the constant distribution capacitance of photogenerated charge (C.D.C.P.C.). The capacitance originating from the distribution of photogenerated charge in a junction region does not connect with alternative electric signals applied on the junction. It essentially distinguishes from the depletion and diffusion differential capacitances as previously known. Since the photo-generated charge, Q, and the photogenerated voltage, V, are connected by the equation, Q-CV, where C is just the C.D.C.P.C. the importance of this new capacitance model is self-evident. In the paper, the expressions of C.D.C.P.C. under the condition of approximately abrupt and graded junctions are deduced respectively at low forward bias. As the examination of the validity of the C.D.C.P.C. model, the deduced results are applied to the contactless test method of the device leakage and a good agreement between the theoretic calculation and experimental results is obtained, which enables the quantitative determination of the device leakage by the high frequency photoconductor decay method to be possible,     

基于微流控的人卵母细胞特性检测

人的卵母细胞特性的研究对于临床医学具有重要意义,可以通过卵母细胞的大小对其活性进行研究。采用微流控平台与MATLAB算法相结合的方法,利用微流控器件的沟道对卵母细胞进行挤压,由于卵母细胞的活性不同对于挤压的反应也不同,活性越好的卵母细胞通过沟道时变形性越好,经检测卵母细胞有很好的活性;拍摄卵母细胞发生形变与卵母细胞通过沟道的视频,利用MATLAB程序进行图像处理得到卵母细胞的大小,测得卵母细胞的直径约为170μm。这种方法有别于传统方法,在一定程度上使用了算法识别,提高了卵母细胞分析统计的准确度,提升了工作效率。由于人的卵母细胞比较珍贵,只进行了初期实验研究,证明此方法确实可行。     

Die EU-Direktive 96/48 für das Hochgeschwindigkeitsnetz der Europäischen Eisenbahnen und die Erweiterung auf das konventionelle Eisenbahnnetz (TEN)

About 10 years ago the European Commission started the process to harmonize the technical and operational standards of the TEN. The first step was the harmonization of the High Speed Lines (EC-Directive 96/48 for infrastructure and trainsets, European law since April 99). The elaboration of the technical standards for the EC-Directive 96/48 was done by A.E.I.F. (European Association for Railway Interoperability), an association of the European Railways (UIC) and the European Railway Industry (UNIFE), mandated by the European Commission. This article gives an overview of the status of the work of A.E.I.F. for the standards for the harmonization of the High Speed Lines of the TEN and the impact on the railways in the transition period. Furthermore an outlook is given for the next step of harmonization, which covers the Conventional Lines of the TEN.     

舰载红外成像探测跟踪系统仿真研究

仿真研究由目标、背景、大气传输和传感器四部分组成．在对目标辐射度的分析中,研究目标温度和发射率的计算方法．计算背景辐射时,重点考虑了海水本身的热辐射特性,并将天空背景的辐射等价于探测器路径上的大气辐射．对大气中的传输研究采用了LOWTRAN模型．仿真中考虑了传感器的影响,包括光学系统和红外探测器．在动态图像生成过程中,采用了多媒体定时器实现了仿真的实时性．仿真的结果可以减少外场试验的次数,从而节省大量试验费用．     

不同像素尺度下太阳表面米粒结构相关跟踪算法的有效性分析

在太阳自适应光学系统中,观测系统探测器所探测到的太阳米粒结构的对比度与探测器像素尺度（探测器的像素尺寸与系统焦距之比）有关。根据互相关因子算法和绝对差分算法的原理,通过比较理想情况时探测器所探测到的太阳表面米粒结构对比度与提取整体倾斜信号后长曝光图像的对比度,考察了不同像素尺度下相关跟踪算法的有效性,并给出了根据所采集的图像得出的实验结果。结果表明探测器的像素尺度越小,利用相关跟踪算法矫正像差越有效。     

Valve timing and valve lift control mechanism for engines

A new type engine valve control system has been presented, in which both the valve lift and valve timing are controlled directly by electric motors. A mechanism of the valve timing control system is made of planetary gears. The outer gear is the timing pulley which has a timing belt driven by the crankshaft of an engine. Two planetary gears are inside of the pulley. The gears engage with the inner gear of the pulley. The center of the disc, which has centers of the planetary gear, is connected to the camshaft. Then, the crank rotation is transmitted to the camshaft, and rotations of sun gear are added to the rotations of camshaft. This means that when rotation angle of the sun gear is controlled, the phase between the inlet valve and the exhaust valve can be controlled. The lift control system is made of linear slider and ball screw. The cam shape of this system is three-dimensional. The height of the cam varies along the axis of the shaft. When the ball screw rotates, the camshaft slides in the axial direction, so that the lift of the cam varies. The control method is presented for the mechanism, in which valve phase and the lift are controlled continuously. Experimental tests have been carried out for the system.     

基于微球透镜远场超分辨率成像方法研究

在可见光波段,传统光学显微镜的成像分辨率被限制到200nm。为了突破衍射极限,采用了将微球与传统光学显微镜相结合的方法来获得远场超分辨率成像。首先通过理论分析平行光通过微纳结构物体后物光波在空气中的传输,进而分析微球将倏逝波转换成传输波实现远场超分辨的成像机理;其次通过仿真研究了微球的光纳米喷射特性,可知微球光纳米喷射的半径尺寸小于入射光波长的一半;最后搭建了基于微球与传统光学显微镜相结合的超分辨率成像实验系统。结果表明,将蓝光光盘作为被测物体,通过该成像系统可获得100nm的远场超分辨率成像; 该成像系统可以对微纳元件结构进行检测。这一结果对光刻技术、生物医学等领域是有帮助的。     

磁头内置DFH控制元件可靠性的有限元分析

 磁头内置DFH控制元件的可靠性设计评估十分重要,目前工艺上多采用经验数据指导的方法,误差十分大,理论上是根据传统流体力学的基本原理,利用Matlab软件实现模拟评估的,由于元件尺寸限制,模拟算法会随着舍入误差的叠加而失效.本文使用ANSYS软件,通过实验获得建立模型的基本参数,选择了合适的单元类型、材料属性,给出了磁头的有限元模型.利用模型对元件进行的寿命预测实验表明,有限元模型分析DFH控制元件的设计可靠性问题是有效的,并且得出以下结论:在50Ω的新型DFH计算结果中,其热效应强度比传统屏蔽层大10%以上,实际的寿命失败样品问题区域都在线路的转角处.     

基于单通道SAR多子孔径空频处理的动目标检测算法

该文提出了一种基于单通道多子孔径空频自适应处理的运动目标检测方法:首先给出了基于方位频谱划分获取子孔径的处理过程,构造出类似于多通道的子图像。详细分析了多子孔径空时等效信号的原理,将不同合成中心时刻的子孔径序列所获得的回波信号等效成同一时刻不同空间位置所获得的回波信号,利用时延差异来获取空间信息,建立起后续处理的2维信号模型。在此基础上,结合多通道杂波抑制的思想,提出了采用多子孔径间空频自适应处理实现杂波抑制与运动目标检测的算法。最后,仿真实验验证了该方法的有效性。     

Field Theory Treatment of H--Plane Waveguide Junction with Triangular Ferrite Post

This paper presents an exact field theory treatment for the H-plane waveguide junction with three-sided ferrite prism. The treatment is general, being independent of the geometrical symmetry of the junction, the number of ports, and the location of the ferrite post inside the junction. The solution of the wave equations in the ferrite post and in the surrounding region is written in the form of an infinite summation of cylindrical modes. The fields at the ferrite-air interface are matched using the point-matching technique. This results in two amplitudes for the cylindrical modes describing the fields in the air region in the form of a matrix. The fields at the arbitrary boundary between the air region and the waveguides are also matched using the point-matching technique. This results in a finite system of nonhomogeneous equations in the field amplitudes. The three-port waveguide junction circulator with central triangular ferrite post is analyzed using this technique. Two specific arrangements are considered. In the first arrangement, the points of the triangles are in the centers of the waveguides, and in the second, the sides of the triangles are in the centers of the waveguides. The method used in this paper can also be applied to study the effect of the ferrite-post geometry on the circulator performance in order to seek the best possible circulator structure. Excellent agreement has been found between published experimental measurements and the numerical results obtained by this technique in the case of a waveguide junction circulator with cylindrical ferrite post.     

激光微细加工中微小曝光区域的计算机温度测量系统

在半导体的激光微细加工技术里，微小曝光区域的温度分布是关键的工艺参数，必须得到精确的测量。而为了使温度测量不影响曝光区的温度分布，需采用不接触测量方法。研制了计算机温度测量系统，实现了微小激光曝光区温度的实时不接触测量。系统中，InGaAs／InP光探测器将微小高温区的温度信号转换为光电流．再经信号放大及模／数转换后输入计算机。结合温度定标实验，对测得的温度数据进行插值运算，在实验中可以实时显示出曝光区的温度值。系统的温度分辨率可达到0．2℃，测量区域的最小直径可达到18μm。同时设计了搜索算法，使温度数据采集和精密位移平台的移动相配合，实现了温度分布的测量和最高温度区的准确定位。     

基于 G.722.1 的分布式语音编码

在语音通信网络中，为获得良好的语音通信质量，抗丢包技术不可或缺。为此，本文基于 ITU G.722.1 语音编码器，提出一种分布式语音编码方法。该方法在 G.722.1 编码器的基础上，构建一个互补编码器；然后在编码端，对同一帧语音分别用 G.722.1 编码器和其互补编码器进行语音编码，并发送编码结果；在解码端，在接收到其中任一语音码流时，用 G.722.1 解码器进行解码，其语音质量不低于 G.722.1 编码器的解码结果，而在接收到两个语音码流时，用 G.722.1 解码器先分别对两个语音码流进行解码，然后对解码结果进行联合处理，其最终的语音质量有明显提升，即有一定编码增益。仿真实验结果表明，本文分布式语音编码方法的抗丢包效果明显，相对于原始编解码器其语音质量进一步提升。      

Control of polishing of diamond films using microactuation and an atmospheric pressure plasma

In this work, the diamond deposited by hot filament chemical vapor deposition (CVD) is polished using an atmospheric pressure plasma. In order to position the film relative to the plasma, a microactuator system is designed using a stack of domed piezoelectric actuators. A dynamic model based on the physical system is developed and the model parameters are measured experimentally. A system based on laser triangulation is used to measure the position of the diamond film relative to the plasma. Control techniques are used to reduce the oscillations during actuation and to eliminate the steady state positioning error. With the application of feedback control, the overshoot is reduced to 2% and the settling time is reduced to 0.3 s. A preliminary set of experiments is performed to relate process parameters to the final surface roughness of the diamond film. The parameters studied include the film's time of exposure to the plasma, the height of the film relative to the plasma, and the distance from the film to the center of the plasma. It is found that the optimum exposure time is 15 min and the reduction of surface roughness is greatest when the distance between the film and the plasma is at a minimum. The best results are obtained when the top of the film is even in elevation with the tip of the top electrode. The diamond film is translated laterally along the plasma. When feedback control is not used, there is no change in the surface roughness. With feedback control implemented, the surface roughness of the diamond film is reduced by 33%.     

Heat Transfer & Thermal Stress Analysis of Plastic-Encapsulated ICs

Analytic approaches of thermal stress in plastic-encapslated ICs reliability have been studied using a simple, 2-dimensional model of the cross section of ICs by the finite-element method. To test the validity of the model, the actual stress within the silicon chip was measured using piezoresistive devices. The calculated stress in the silicon chip agreed with the experimental values. The stress distributions were changed by lead-frame properties. Package cracking, and delamination between the molding plastic and the lead-frame were qualitatively explained. We estimated the effect of the plastic properties on stress quantitatively. Furthermore, to test the validity of this model, the temperature change at the silicon chip was measured using the Vf temperature dependency of a diode. The calculated temperature change at the silicon chip agreed with the observed values. A very high temperature gradient was observed near the surface of the plastic immediately after solder dipping. The non-uniform temperature distributions produced different thermal stress distributions than those observed in the steady-state. This result indicated that rapid thermal shock could delaminate the plastic from the lead-frame. We believe that these results can guide the development of an optimum low-stress plastic.     

矢量涡旋光束经光阑-透镜系统的OAM与偏振特性

与标量涡旋光束不同,矢量涡旋光束同时具有各项异性的空间偏振分布和螺旋相位分布,并携带与相位分布有关的轨道角动量(Orbital angular momentum,OAM)。根据柯林斯衍射积分理论,得到了傍轴近似条件下矢量涡旋光束的OAM密度,实验采集了矢量涡旋光束通过光阑-透镜系统后的光场,详细讨论了光阑截断参数以及光阑-透镜间距等参数对矢量涡旋光场及其OAM密度的影响。结果表明:相比标量涡旋光束,矢量涡旋光束OAM通过光阑系统后随传输距离的衰减更慢,受光阑截断参数影响更小。矢量涡旋光束偏振态不受光阑-透镜系统影响,截断参数大于4.2时,轨道角动量密度和光强不受截断参数影响。在透镜焦点位置处,OAM密度达到最大值。研究结果为矢量涡旋光束OAM特性的应用提供理论依据。     

一种基于滑动窗能量检测的OFDM符号同步算法

文章提出了一种基于滑动窗能量检测来实现OFDM符号定时同步的算法。为了避免码间干扰（ISI）,通常在帧的起始位置添加保护间隔。该算法正是利用该保护间隔信号能量最小的特点来寻找符号定时同步点。该算法分为粗同步和细同步,通过改变滑动窗的长度,两次寻求滑动窗内信号能量的最小值,来确定最佳的符号定时起点。文中给出了算法的具体步骤。仿真结果表明,该算法具有良好的估计精度。     

野外复杂背景下红外图像的目标检测

野外复杂背景下红外图像序列目标检测是红外野外监视中的重点问题。大量的背景物增加了目标检测的难度。文中针对野外复杂背景下红外图像序列的特点,提出了一种实用的运动目标检测算法。该算法包括两个处理步骤：首先,在场景配准后利用帧间差图像提取目标的运动信息,并据此进行目标的粗检测;其次,合目标运动在时间和空间上的相关性进行精检测。粗检测的低漏判度和精检测的低误差率保证了算法的可靠性。在检测的同时算法确定了目     

双波长激光驱动接收专用集成电路设计

双色激光引信在克服云烟干扰方面具有重要价值。为了减小引信体积,保障导弹内部空间的充裕性,设计了一种基于BCD工艺的双色激光引信专用集成电路芯片。首先,对现有双色激光引信的结构和工作原理做出了详细介绍,引出了单芯片设计的思路和方法,并给出了该芯片集成的子电路的设计方法和仿真结果。该芯片使用0.25 m的BCD工艺制造。经测试使用该芯片驱动双色激光器,芯片供电电压5 V,激光器支路供电电压27 V时,红外激光器输出峰值功率可达30 W,紫光激光器输出峰值功率达25 W,脉宽50～500 ns可调,重复频率1～100 kHz可调,窗口时间1～10 s可调,红外和紫光回波信号在接收部分实现了分离,在功能上成功取代了原系统的4块芯片,实现了系统的简化。     

中间件技术在遗留系统改造中的应用

遗留系统是企业建立新信息系统时,面临的首要问题。在简单介绍了中间件技术的基础上,提出利用中间件技术通过构件化实现对遗留系统改造的方法,改造过程包括4个阶段:恢复遗留系统的软件体系结构;设计目标系统的软件体系结构;重新构造目标系统的构件;实现基于构件的目标系统。实践证明,该方法对遗留系统的再工程具有较大的实用价值。