典型信号傅里叶分析及仿真实现

在信号分析和处理过程中,经常遇到时域和频域的对比分析,对于确定性信号,傅里叶变换是解决这类问题的主要手段。这里主要选择三角频谱作为频域带限信号,遵循一定的思路将复杂问题简单化,比如将三角脉冲信号看作两个矩形脉冲信号卷积的结果,或者采用对信号进行先微分、后积分的思想都可以使问题得到简化,从而大大减小了运算量,提高了运算效率。最后用仿真软件给出波形图以利于观察。     

An Efficient Simulation Environment and Simulation Techniques for Bluetooth Device Design

Validation of an System-on-Chip (SoC) design with networking capability needs global simulation of the whole system including the network as well as the SoC design itself. Especially, it is needed to validate the interoperability of SoCs from different vendors. In this paper, we propose a simulation environment and simulation techniques for efficient validation of such SoC designs and apply them to networked Bluetooth SoC designs. The environment enables two types of simulation. One is modular enough to include the simulation of other vendors' Bluetooth devices and the other is optimized to achieve fast simulation in developing in-house Bluetooth devices. Especially, the former is scalable in that it keeps the constant simulation runtime despite the increase of the number of Bluetooth devices. Since multiple simulators are involved, the global simulation is still slow. Thus, the simulation efforts need to be minimized to shorten the design cycle. We present two simulation techniques, a concept called grouped message for reduction in simulation runtime and a system debug scenario called fix–modify–restart for reduction in the number of simulation runs. The former is to reduce inter-process communication overhead between simulators in the global simulation. The latter is to reduce repeated simulation runs in the conventional design cycle. Experimental results show the scalability of the presented simulation environment, reduction in simulation efforts by two simulation techniques.     

具有教学培训和科研功能的模拟变电所实训基地

介绍了西南交通大学建成的教学用模拟变电所实训基地的结构、功能、特点、实践项目。使用表明,该基地具有国内领先技术水平,完善的教学、培训和科研的综合功能。由于采用最新的远程监控技术,该变电所可作为目前铁路牵引变电所技术改造的参考。     

多量子位量子Fourier变换的仿真实现研究

量子Fourier变换(QFT)是许多量子算法的关键子例行程序,核磁共振系统(NMR)是目前最有希望实现量子计算的物理系统之一.在介绍QFT,并对其进行进一步分析,得到了多量子位QFT的实现逻辑线路后,应用多量子算符代数理论,给出了基本量子逻辑门的核磁共振实现,分解了QFT各相应的逻辑操作,设计了相应的核磁共振脉冲序列.并通过量子计算仿真程序进行了实现多量子位QFT的实验验证,证明了所设计的NMR脉冲序列的合理性和实用性.     

利用改进的分步傅里叶算法模拟超连续谱的产生

为提高模拟超连续谱(SC)产生的精度,在不增加计算量的情况下对传统分步傅里叶算法作了一定的改进.传统分步傅里叶算法只考虑初始脉冲中心频率对应的色散系数,而超连续谱的光谱范围很大,当色散系数随波长变化较大时,传统算法会存在较大误差.改进的算法将整个脉冲包络看成由多个单一频率分量组成,对各频率分量分别处理,从而将整个脉冲包络内所有频率分量的色散系数都考虑在内.将改进算法分别用于模拟色散曲线只包含一个和两个零色散点的光子晶体光纤(PCF)中超连续谱的产生,并与传统箅法的模拟结果相比较,结果表明,改进算法在模拟单零色散光子晶体光纤中超连续谱产生时优势不明显,但对模拟双零色散光子品体光纤中超连续谱产生却有一定优势.     

Automatic Decomposition of the Clinical Electromyogram

We describe a new, automatic signal-processing method (ADEMG) for extracting motor-unit action potentials (MUAP's) from the electromyographic interference pattern for clinical diagnostic purposes. The method employs digital filtering to select the spike components of the MUAP's from the background activity, identifies the spikes by template matching, averages the MUAP waveforms from the raw signal using the identified spikes as triggers, and measures their amplitudes, durations, rise rates, numbers of phases, and firing rates. Efficient new algorithms are used to align and compare spikes and to eliminate interference from the MUAP averages. In a typical 10-s signal recorded from the biceps brachii muscle using a needle electrode during a 20 percent-maximal isometric contraction, the method identifies 8-15 simultaneously active MUAP's and detects 30-70 percent of their occurrences. The analysis time is 90 s on a PDP-11/34A.     

Spectral Analysis of Surface Motor Unit Action Potentials and Surface Interference Electromyogram

Surface interference electromyograms (EMG's) were recorded from the tibial muscle of a healthy subject during 50 percent maximal contraction and single motor unit action potentials (MUAP's) were isolated by averaging from the interference pattern. The formation of the EMG was simulated by summing isolated MUAP's according to the statistical properties of the corresponding motor unit discharges. Power spectral density functions (PSDF's) were finally computed for single MUAP's as well as for simulated and experimental EMG's and compared with each other.     

Xilinx Foundation的仿真分析

以一个双向串并/并串收发器的实现为例，运用Xilinx Foundation对此进行了简易仿真和脚本仿真，并对该两种方法的仿真过程和结果做了介绍和比较。结论表明，脚本仿真无疑是硬件设计过程中一种灵活高效的仿真方法。     

增强的无线局域网安全技术分析

文章介绍了无线局域网安全技术的现状，对IEEE802．11i草案中有关认证、密钥管理、加密等方面的增强的无线局域网安全技求进行了分析。提出了基于IPsec(IP安全)的VPN安全解决方案。     

Analysis of financial indices by means of the windowed Fourier transform

The goal of this study is to analyze the dynamical properties of financial data series from nineteen worldwide stock market indices (SMI) during the period 1995–2009. SMI reveal a complex behavior that can be explored since it is available a considerable volume of data. In this paper is applied the window Fourier transform and methods of fractional calculus. The results reveal classification patterns typical of fractional order systems.     

An Investigation of Computerized Tomography by Direct Fourier Inversion and Optimum Interpolation

In this paper an exact interpolation formula forms the basis for reconstructing computerized tomographic (CT) imagery by direct Fourier methods. Practical variations of exact interpolation are compared with other interpolation methods (i.e., nearest neighbor, etc.) and are shown to yield superior imagery. Images produced by the direct Fourier approach using near-exact interpolation are shown to be equal in quality with those produced by filtered convolution backprojection (FCBP). Moreover, the direct Fourier approach computes an image in O(N2 log N) time versus O(N3) for the FCBP method.     

An Analysis and Simulation of Failure in Dower Connectors

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快速傅里叶变换对信号频谱的简单分析

快速傅里叶变换(FFT)是离散傅里叶变换(DFT)的快速算法,广泛运用于故障诊断领域,因每种故障的频率成分不同,FFT可以根据这些独有的频率成分检测出不同的故障来。同时快速傅里叶变换还应用于控制工程、图像处理、机床生产、数据采集和雷达探测等方面,对社会中的工业发展起到很大的作用。本文就FFT对信号的频谱做出简单分析,对不同采样点数进行相应频谱判断,找出理论与频率图像出现误差的原因,以便人们对FFT技术能够进行更好的使用。     

快速傅立叶变换算法概述

快速傅立叶变换（FFT）属于数字信号处理中最基础的运算,已广泛应用于通讯、医学电子学、雷达或无线电天文学等领域。对FFT的主要算法进行了概述 ,并对其特性和运算工作量进行了分析和对比,期望对快速傅立叶变换算法有一个清晰的认识。     

An Application of Dimensional Analysis Techniques in an Industrial

In this research diverse methodologies are applied for identify variations of dimensional controlgenerated during the assembly process of a vehicle, this research analyzes the advantages of use technical of principal components analysis (PCA) by means of artificial neuronal networks and robust statistic in different situations of a process industrial multivariate.     

An Analysis of the Sensitivity of Digital Modulation Techniques to Frequency-Selective Fading

This Paper investigates the sensitivity to frequency-selective fading of different modulation techniques commonly used in digital radio systems. The modulation methods considered are phase-shift-keying (Mary PSK), nonoffset and offset quadrature amplitude modulation (M-ary QAM), and quadrature partial response signaling (QPRS). The performances of these methods during multipath fading are compared on the basis of the "signatures" calculated for idealized systems. Results are presented from which the relative outage probability was determined, assuming a propagation channel with frequency-selective Rician fading.     

集成仿真系统中时间一致性问题分析

在实验室射频-数学集成仿真系统构建的基础上,对仿真系统集成过程中面对的时间一致性问题进行了理论研究,从仿真系统的时间分辨率、时间源和时间推进机制三方面详细分析了导致时间不一致原因,最后在深入分析的基础上,提出了解决时间不一致问题的方法。     

An Analysis and Design of the Virtual Simulation Software Based on Pattern

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Simulation Techniques for the Manufacturing Test of MCMs

Simulation techniques used in the Manufacturing Test SIMulator(MTSIM) are described. MTSIM is a Concurrent Engineering tool used tosimulate the manufacturing test andrepair aspects of boards and MCMs from design concept through manufacturing release. MTSIM helps designers select assemblyprocess, specify Design For Test (DFT) features, select board testcoverage, specify ASIC defect level goals, establish productfeasibility, and predict manufacturing quality and cost goals. A newyield model for boards and MCMs which accounts for theclustering of solder defects is introduced and used topredict the yield at each test step. In addition, MTSIMestimates the average number of defects per board detected at eachtest step, and estimates costs incurred in test execution, faultisolation and repair. MTSIM models were validated withhigh performance assemblies at Hewlett-Packard (HP).     

Microwave Circuit Analysis by Sparse-Matrix Techniques

Linear microwave circuit analysis by sparse-matrix techniques is discussed. Optimum equation ordering and pivoting are proposed to reduce execution time, storage requirement, and to improve accuracy. A direct first-order sensitivity method using sparse-matrix techniques is proposed and compared with the adjoint network method. Details on the implemented program and a numerical example are given.