贝叶斯估值理论在小子样批次设备检测中的应用

本文针对机载无线电设备故障诊断定位率低的问题，提出利用先验故障信息指导批次定检的思想,通过研究批次定检设备的失效规律，运用贝叶斯理论估计小子样定检设备各模块的故障概率，并且提出了故障检测的4种指导方法．仿真试验结果表明可显著提高故障的一次定位准确率，减少故障查找时间，提高故障诊断效率．     

An Efficient Algorithm for Optimal Design of Diagnostics

Even though much work has been done in developing models to design diagnostic tests for fault isolation in electronic systems, there is still a lack of efficient, fast procedures. A new approach to the cost-effective design of fault isolation procedures is investigated. It is oriented specifically toward built-in-test (BIT) diagnostic subsystems for modular electronic equipment. The problem is formulated as a search tree. A branch and bound technique is used to find the optimal sequence of tests for the automatic BIT diagnostic to isolate a single malfunctioned unit among a group of Line Replaceable Units (LRUs). Dominance and branching rules are developed, and the algorithm is presented. An example problem is solved to illustrate the efficiency of the branch and bound algorithm. Computational results are given and discussed. The following conclusions can be drawn. 1. The branch and bound approach can be used successfully in designing a cost-effective fault-isolation procedure. Because of the branching and dominance rules, many of the non-optimal solutions are eliminated early in the solution procedure which could efficiently reduce the size of the required search tree, as well as the time and storage needed to find the optimal solution. 2. The proposed branch and bound algorithm is efficient in solving problems of size up to eight LRUs. 3. Even though the size of problems solved efficiently by the algorithm is limited to eight LRUs, this size is still greater than the size of any problem reported to be solved optimally in any previous work.     

An Investigation of the Use of Microwave Radiation for Pulmonary Diagnostics

This communication describes a new technique in which penetrating microwave radiation is used for the diagnosis and monitoring of pathological cardiopulmonary conditions, such as pulmonary edema. Edema causes changes in the electromagnetic characteristics of the lung tissue, which in turn produces a change in the reflected and transmitted microwave radiation. Both the amplitude and phase changes of the microwave signals are measured.     

An Estimate of the Capacity of the Meteor Burst Channel

An estimate of the capacity of the meteor burst communication channel is given. The model takes into account both overdense and underdense trails as well as the effects of wind-induced trail warping.     

一种全数字化载波频偏估计器算法

本文提出一种适合ＱＡＭ调制信号的全数字经载波频偏观测器算法,它用于不再采用锁相环同步器的全数字接收机中直接测量频偏的大小,文中提出了频偏观测器算法,接着引入频偏的卡尔曼滤波算法,最终把频偏观测器与卡尔曼滤波器相结合构成了频偏估计器,为存在较大偏的移动通信信道中解决载波同步问题提供了一种实现方案。     

An Estimate for the Time Congestion for Overflow Processes

The paper presents an estimate of time congestion for overflow process. The approximation is derived from the Markovian formulation under classical assumptions (Poissonian traffic offered to the first choice route and exponential service time). Numerical experiments show the accuracy and the limitations of the proposed estimate.     

一种改进的基于导频的OFDM信道估计算法

文中对OFDM（正交频分复用）系统中基于导频的信道估计技术进行了研究。MMSE（最小均方误差估计）算法有很好的性能但复杂度大,LS（最小二乘法估计）算法复杂度低但性能受到限制,在综合考虑性能和复杂度的情况下介绍了两种改进方法。并针对基于梳状导频的二项插值算法的缺陷,提出了一种改进的算法,计算机仿真证明了改进算法的误码率性能在高信噪比条件下高于原算法。     

An Empirical Estimate of the Contribution of Terrain Reflections to Interfering Signal Distributions

This paper is a report on a problem which is thought to have rather general interest in the field of radar and communications systems. This is the problem of interference caused by the reflection of pulsed radar signals from the terrain in the transmitter-receiver environs. This problem has proved to be rather intractable to handle analytically and therefore the empirical approach presented in this paper might be of special interest to those who have tried some analytic approach. Basically, the problem to which this paper addresses itself is as follows: Suppose it is desired to predict the number of pulses and their power levels, arriving at an unintended receiver from a radar transmitter. The task of predicting the direct pulses is difficult, but can be approached analytically; however, what can be done about predicting those pulses reflected from the terrain (or other objects) in the vicinity, especially when no detailed terrain information is available? during the study from which this paper arose, measured data was obtained at several selected sites in the San Diego area by tuning a test receiver to one of the identified, operating radar transmitters at a time. The number of pulses and their power levels were measured by the test equipment and recorded. This procedure was reported for several different transmitters at three test sites. At the same time, a computer program (called MSS-1) has been developed to predict the number of direct pulses and their power levels.     

Diagnostics of the quality of MOSFETs

The excess noise behaviour of silicided p-channel MOSFETs is investigated. Due to contact problems, generation-recombination noise spectra are observed. Analysis of the current noise spectra versus the current on a single device, showed that the generation-recombination noise was due to trapping of carriers in the source and drain contacts. An analysis of an L-array is not necessary to distinguish between channel and contact contribution. The classical geometry and current dependence of the noise is no longer valid if the noise in the series resistance is dominant. Large generation-recombination noise components, with the dependence S_I ∝ I⁴, point to poor device contact quality.     

一种基于可变禁忌长度的多用户检测方法

CDMA系统的性能很大程度上受多用户干扰影响。多用户检测是抑制多用户干扰的有效方法。文中介绍一种基于可变禁忌长度的多用户检测方法。该方法以传统匹配滤波器的判决输出为初始解,采用禁忌长度可变的禁忌搜索(TS)算法,使禁忌长度与搜索空间的崎岖程度相适应,以避免搜索限入局部最优。仿真实验证明,该方法具有较好的误比特性能和抗远近效应能力,并具有多项式复杂度。     

An Algorithm to Estimate Time Offset between Measurement Devices

1　Introduction　Internethasbeguntosupportkindsofreal timeservices .Theseservicesputforwardgreatchallengesoncurrentnetwork .Notonlytheyneedcertaintransmissionbandwidth ,butalsotheyhavestrictdemandsonone waydelay .Accordingto[1～ 3] ,thedelaytoleranceofaudioserviceshouldbelessthan1 5 0mstoachieveacceptablequality .Asaudioen coderwouldneed 30～ 80mstocompletecodinganddecoding,soone waydelaycausedbyInternetshouldnotexceed 70msor 1 2 0ms.Bymeasuringone waydelay ,wecanjudgewhethercurrentInter net…     

一种用于TD-LTE系统CP类型估计的改进算法

TD-LTE系统中循环前缀(CP)有防止符号间干扰的作用,接收端只有确定CP类型才能确定准确的FFT解调窗口位置.本文提出了基于CP的相关算法和能量差算法,主要利用CP为该符号尾端数据的复制这一特性,通过不同CP长度间相关系数比值和能量差值系数比值来估计CP类型.同时考虑到算法的复杂度和DSP实现的简易程度,进一步改进了以上算法,提出了基于部分序列的相关能量差算法,仿真结果和算法原理表明了该算法的实用性和低复杂度等优点.     

一种改进的扩频BPSK信号载频检测估计方法

检测与估计扩频信号的载波频率是截获扩频通信的重要手段,在分析直扩 BPSK 信号特点和传统平方载波检测方法的基础上,根据对称相关变换的性质,提出了一种改进的基于对称相关变换的平方载波检测扩频信号检测与参数估计方法.通过平方检测器,信号在载波的倍频处产生离散线谱,检测离散线谱可实现扩频信号的检测与载波估计.为了提高算法的检测性能,通过对称变换,进一步抑制噪声,有效地改善了输出信噪比,实现了低信噪比下直扩信号的检测.仿真结果验证了所提出方法的有效性.     

An Estimate of the Steady Magnetic Field Strength Required to Influence Nerve Conduction

The effects of steady magnetic fields upon the conduction of a nerve impulse are considered. Microscopic chemical effects as well as those due to induced fields are ignored. Arguing from an analysis of transport properties, we show that the minimum magnetic field required to produce observable effects is quite large. For the best case, the rield required to produce a 10 percent reduction in conductivity is roughly 24 T.     

基于广义逆矩阵的分规格成本核算方法

文章以某铸管公司的分规格成本核算系统为例,对比传统的成本核算方法,用矩阵的广义逆来解决多种规格产品的成本核算问题,并提出可比综合成本的概念,使企业在多种规格并行生产时,可以准确了解每天的成本起伏,使这种方法可以广泛应用于大规模流水线型生产企业。     

基于间隔估计法的RFID防碰撞算法

多个应答器的碰撞问题是影响超高频射频识别(RFID)系统读取效率的一个关键问题。从EPC Class1 Generation2(C1G2)RFID系统帧长受约束特点出发,分析了帧时隙ALOHA防碰撞机制及其经典应答器估计方法的特点。提出了应答器间隔估计方法(IEM)以及基于该方法的EPC C1G2 RFID防碰撞算法,并给出了仿真结果。与现有基于经典应答器估计方法的射频识别系统防碰撞算法相比较,提出的防碰撞算法减少了识别时间,提高了系统的识别效率。     

An Estimate for the Nonradiative Linewidths of the Quasibound Electron-Hole Pairs in Narrow Quantum Wells

Semiconductors - The energies and the nonradiative linewidths of the electron-hole quasibound states in narrow GaAs-based quantum wells are calculated by the exterior complex-scaling technique....     

基于LDPC编码及LS估计的OFDM系统

OFDM具有并行数据传输与子信道交叠的特性，在无线局域网、HDTV中得到广泛应用。LDPC作为一种具有良好纠错能力的分组编码方案，性能几乎接近Shannon极限。本文给出一个基于LDPC编码，线性LS信道估计的OFDM系统，兼有两者的优点。     

估算晶圆有效芯片数的椭圆公式

IC生产线开发新品和核算成本时,需要估算晶圆上有效芯片数。靠经验公式估算通常有较大误差。作者曾提出一个精确的计算晶圆上有效芯片数的椭圆公式[1],适合于大规格晶圆和高成品率的生产线上应用。本文给出了椭圆公式的推导过程。     

Diagnostics of the models of the diode barrier capacitance

The model characteristics of the barrier capacitance of the p-n junction at an arbitrary distribution of impurities in the base are studied. It is demonstrated that the simulation of the C-V characteristic of the nonlinear capacitance can be supplemented with the analysis of its first two derivatives. The identification of the model parameters using the least-squares method is considered.