数字全息显示中的三维物体信息量及其压缩

从人眼的双目视觉理论出发 ,研究了在双眼所能观察的视觉空间内 ,三维物体的信息量、全息图的信息量以及它们之间的关系问题 ,并给出了具体的计算方法及结果 ,为全息图信息压缩提供了理论依据和压缩途径。     

用AC1056实现对雪崩光电二极管温漂的偏压补偿

雪崩光电二极管(APD)的增益严重地受到温度的影响.AC1056是一款多功能的12位A/D板,具有A/D转换和D/A控制的功能.利用它得到了具有相当精度的对APD偏压和温度的采集和具有高精度的对APD偏压的控制,从而获得了在维持APD增益比较恒定的条件下其温度和偏压之间的关系,并在应用中实现了对APD温度漂移的偏压补偿.     

强激光清除空间碎片的力学行为初探

给出强激光清除空间碎片过程中 ,随推进深度的变化 ,激光功率密度的改变及相应的推进速度。根据流体力学问题 ,推导出强脉冲激光作用在空间碎片上时的烧蚀率 ,及碎片受到的推力。以空间碎片其中的一种成分铝为例 ,模拟计算出在一个强脉冲的作用下 ,激光的烧蚀质量 ,相应的烧蚀率 ,碎片受到的推力 ,及耦合系数等物理量的数值     

嵌入式PC机基于SOCKET通信在DOS下的实现

嵌入式PC安装一般是嵌入到其他设备或系统中,所以体积、功耗、抗震性等方面的特殊要求使其硬件环境与标准PC有所区别:其内存较小、无硬盘、甚至无显示功能或由远端的控制终端进行显示,因此视窗操作系统的强大功能发挥不出来,则DOS以其内核小、操作简单、实时性强就在嵌入式PC领域中占有重要地位。然而,DOS操作系统缺乏类似Win-sock的API,所以在该系统下设计基于TCP/IP协议的应用程序时难度较大,结合实例阐述基于DOS下的嵌入式系统中实现SOCKET通信的一种具体方法和过程。     

EPON测试仪硬件平台的设计与实现

随着基于以太网的无源光网络(EPON)商用规模的逐步扩大,不同厂商设备间的互通测试以及EPON系统的工程验收测试和运行维护变得日益迫切,为此我们设计开发了EPON测试仪.文章分析了EPON测试仪的功能需求,简述了EPON测试仪的总体框架,着重阐述了EPON测试仪硬件平台的设计及其核心功能的现场可编程门阵列(FPGA)的实现.     

On the Meaning of Quantified Maintainability

Maintainability analysis stands today where reliability was ten years ago. Many and varying definitions of maintainability have been proposed; many mathematical approaches to maintainability and its various aspects have been pursued. Nevertheless, there is presently no general agreement on the definition of maintainability or on the technique of its quantification. In addition, there is insufficient meaningful maintainability field and laboratory data. As in the case of reliability, analytical techniques are only a part of the maintainability improvement effort. There is a need for improvement in both the design of the total maintenance system as well as analytical techniques for its evaluation.     

模拟电路阵列及其半定制专用集成电路实现

与门海数字电路阵列相类似 ,模拟电路阵列也是半定制集成电路设计的母体形式的一种。首先介绍了母体单元结构布局 ,然后描述了其电路的实现。在以上模拟电路阵列母体上 ,成功地实现了很多专用的模拟电路     

硅PIN光电二极管光谱响应特性的数值模拟计算

对硅PIN光电二极管的光谱响应特性作了详细的分析计算,得到了硅PIN光电二极管光谱响应的计算公式;给出了器件光谱响应曲线的绘制方法.实测数据与公式计算结果吻合较好.讨论了器件工艺参数变化对光谱响应的影响.     

Iran's Present Telecommunication System and Its Expected Development

By the end of the Fifth Plan, March 21, 1978, Iran will have expanded its telecommunication service threefold, it will be providing educational program and television to nearly 75 percent of its population, and it will be well on its way to accomplishing its longrange goal of a totally integrated telecommunication system. It will have graduated telecommunication engineers and technicians from the PTT College of Telecommunications Engineering. Radio and television production specialists will be graduated from the NIRT College which recently incorporated a Master's Program. It will also have expanded present telecommunication manufacturing capabilities and started new joint ventures. Where it is now, where it intends to be, and how it intends to get there are described in this paper.     

ARM技术参数对攻击性能影响研究

本文在仿真环境下,针对ARM技术参数对攻击性能的影响进行了分析,得出了一些重要结论,对ARM有效打击雷达阵具有重要的指导意义。     

最新网络三层分组交换技术及其应用

分析了局域网中网段划分所带来的网段中子网路由必须依赖传统路由器所造成的网络”瓶颈”问题 ,详细介绍了网络三层分组交换技术的基本原理和拓扑结构 ,给出了其软硬件实现的原理图 ,并指出了它的特点。最后 ,简要讨论了三层分组交换技术在各类网络中的应用及其发展前景     

DDS信号的杂散及抑制分析

DDS（直接数字频率合成器）技术由于有诸多优点而得到广泛的应用。但因其固有的数字特性,使其输出信号存在大量的杂散,如何抑制DDS技术产生的杂散问题,是当前研究的热点问题之一。文中在介绍DDS工作原理的基础上,分析了其输出频谱杂散的来源,进而提出了几种抑制杂散的方法,通过加扰动源破坏杂散的周期性,压缩数据和增大ROM的相对容量等,有效地改善了DDS频谱质量,对基于DDS技术的频率源的设计有一定的实用性和指导意义。     

曝光机双玻璃晒架及其真空系统的设计

曝光机是图形转移中的重要设备。传统的迈拉晒架存在着需要赶气、效率低等缺点,已不能满足现代生产的需要。现今双玻璃晒架已在国外中、高档曝光机上普遍采用,但在国内各厂商还不具备生产能力。设计了散射光曝光机的双玻璃晒架系统,研究了玻璃的固定方式、腔体真空、底片吸附等问题,在实验基础上得出了当膨胀密封圈气压为0.03MPa,腔体真空度和底片吸附分别为40kPa和80kPa时,该晒架系统的真空效果较好。     

Metallization proximity studies for copper spiral inductors on silicon

The impacts of metallization proximity for copper spiral inductors on silicon have been investigated in this paper. Performance of the spiral inductor versus area consumption tradeoff with respect to its core diameter is evaluated quantitatively for the first time. Effects of the inductor's proximate grounded metallization on its overall inductive performance are also analyzed.     

微机在数—模转换器测试自动化中的应用

微机在测试方面的应用已非常广泛。要提高测试速度和实现测试自动化,就应对微机接口进行开发应用;本文将讨论利用微机实现D/A转换器自动测试和在测试专用接口方面的开发应用:即微机总线扩展、微机与测试的隔离、程控电源、继电器开关阵及8—16位数据通道等。     

基于石墨烯的太赫兹光电功能器件研究进展

作为一种新型光电材料,石墨烯独特的能带结构和电子输运特性,使其与太赫兹科学有着密切的内在关系：石墨烯内部的等离子体振荡频率在太赫兹频段;人为调谐石墨烯的禁带宽度在0~0.3 eV时,正好覆盖太赫兹频段;光电导率的外部可控性等,这些特点使得石墨烯有望成为太赫兹频段新一代高性能设备研制的基础。最近的研究显示,石墨烯在太赫兹波产生、调控、检测等光电功能器件的研制中取得了很好的成果。重点介绍了基于石墨烯的太赫兹光电功能器件,包括太赫兹源器件、可控调控器件及检测器研究的最新进展,并对这一快速发展的研究领域进行了展望。     

Proceedings of the IEEE: the first 75 years

The author traces the history of the Proceedings of the IEEE from its inception under the Institute of Radio Engineers to the present. The presentation follows the various stages of the journal's development and discusses its changing roles over the years. Included is commentary on the man who founded the Proceedings and on those who have guided it since     

曲面GRIN光学元件近轴光学参数的通用算法

本文利用矩阵和常数ＫＧ方法推导了曲面梯度折射率光学元件的近轴参数，如焦距、象方截距，焦截距，线放大率与主点位置，角放大率与节点位置的表达式，并讨论了势物面形径向对称曲面ＧＲＩＮ光学元件的成象特性，当度为半周期的整数时，发现了其有趣的现象，得出了一些有益的结论。     

Tracking performance analysis of fractional lower order constant modulus algorithm

The fractional lower-order constant modulus algorithm (FLOS_CMA) has been proven to be an effective blind equalisation method under a-stable noise. But there have been few results in the literature about its performance. The tracking performance of the FLOS_CMA in non-stationary environments is studied. The approximate expression is derived based on the energy-preserving relation and Taylor series expansion. Based on the derived expression, an estimate is obtained for the FLOS_CMA step-size interval to ensure its convergence and stability, when it is initialised sufficiently close to the zero-forcing solution. Simulation studies have been undertaken to support the analysis.     

Steady-state availability of a system with two subsystems working alternately

The authors have considered the reliability aspect of a system with two subsystems working alternately in the previous paper in this issue. As the system was modelled on an electric power system with two subsystems of hydroelectric power supply and thermal electric supply, the steady state availability of the system assumes importance. We have a system consisting of two subsystems working alternately. In model I, no subsystem works in the period of working of the other. In model II, subsystem 2 is switched on when subsystem 1 fails in its working period. When a unit of subsystem 1 is repaired, it continues to work in its period and subsystem 2 is off line. On the other hand if subsystem 2 fails in its working period, subsystem 1 is not switched on. The availability expressions for both models are derived.