Optimization and integration of high‐performance ground penetrating imaging radar system: A research prototype

This paper reports the design, development, and field experimentation of a new ground penetrating imaging radar system. This research prototype unit features full system optimization, which successfully integrates the key components of antenna sensitivity, data‐acquisition waveforms, synthetic‐aperture scan, and image reconstruction algorithms, for optimal system performance.© 2006 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 15, 220–223, 2005     

Data mining technique for fast retrieval of similar waveforms in Fusion massive databases

Fusion measurement systems generate similar waveforms for reproducible behavior. A major difficulty related to data analysis is the identification, in a rapid and automated way, of a set of discharges with comparable behaviour, i.e. discharges with “similar” waveforms. Here we introduce a new technique for rapid searching and retrieval of “similar” signals. The approach consists of building a classification system that avoids traversing the whole database looking for similarities. The classification system diminishes the problem dimensionality (by means of waveform feature extraction) and reduces the searching space to just the most probable “similar” waveforms (clustering techniques). In the searching procedure, the input waveform is classified in any of the existing clusters. Then, a similarity measure is computed between the input signal and all cluster elements in order to identify the most similar waveforms. The inner product of normalized vectors is used as the similarity measure as it allows the searching process to be independent of signal gain and polarity. This development has been applied recently to TJ-II stellarator databases and has been integrated into its remote participation system.     

基于Lorenz混沌调频的水下正交波形集设计

针对网络水下航行器组联合探测情况下各网络节点间信号会互相干扰的问题,基于Lorenz混沌模型,提出一种混沌调频(Chaos Frequency Modulation,CFM)的正交波形集设计方法。首先建立基于Lorenz序列的CFM信号模型,对其进行相关特性分析和正交特性研究,包括CFM正交波形集的个数和波形长度对波形集正交性能的影响,提出对混沌序列进行加窗函数处理的CFM波形集正交性优化方法;然后构造网络水下航行器组分别发射线性调频(Linear Frequency Modulation,LFM)信号和CFM信号的回波模型,对比分析了匹配滤波器对回波信号的处理结果。仿真结果表明,该设计方法简便、灵活、高效,产生的CFM正交波形集性能良好,且相对于常规信号在水下信号检测方面具有明显的优势。     

非正弦波交流电参量实时测量系统的研究

研究了非正弦波交流电信号的采样测量方法,分析了同步误差的两个主要来源.采用同步误差补偿法,并结合三点法,实时跟踪信号频率变化并调整采样周期,较好地解决频率变化时采样不同步以及测量精度下降的问题;采用步进采样法来扩宽测量信号的频率范围;讨论了无外部采样保持器时的采样时序.设计了以16位超低功耗单片机MSP430F449为微处理器的硬件系统.实验结果证明本设计能有效提高软件同步采样测量精度.     

串扰最小化的网格模式下的双层通道布线

超深亚微米IC设计中互连线的串扰情况与详细布线方案和信号波形密切相关。基于这一事实，在网格模式下的通道布线算法中建立了最小化串扰的目标函数。提出获得最小化串扰布线方案的方法。与以往算法不同的是，本方法将相邻平行线间信号跳变的方式和频度作为目标函数中的影响因子。可以更准确地估计出布线区内串扰总和的大小。并且通过构造布线生成树的方法求得精简的布线方案。有效地减少了求解具有最小串扰的布线方案的计算量。     

On the using of modal curves for radar waveforms classification

Recent advances in nonparametric functional data analysis allow to define the notion of mode for a sample of curves. A kernel-type estimator is proposed for estimating this modal curve. In addition, other centrality curves can be easily extended to the functional case, namely mean and median curves. A nonparametric unsupervised classification method which is also a cluster analysis is investigated. This is based on the comparison between the modal curve with another centrality curve for measuring some heterogeneity index. The main point is to show the good practical behaviour of this hierarchical classification on a sample of radar waveforms registered from the satellite Topex/Poseidon upon the Amazonian basin. In addition, a few theoretical advances are provided.     

应用模式识别进行波形分析

根据测试器需要,利用子空间模型识别对测试波形进行分析,并将波形参数与妈调波形进行比较,按匹配给出测试波形特征。     

Selection of suitable fuzzy operators for representative power factor evaluation in non-sinusoidal situations

Power factor is well defined in sinusoidal situations, however, in the presence of harmonics, different power factors exist and they may provide different values in which case, evaluation becomes problematic. In Morsi and El-Hawary (2008) [1], [2] and [3], fuzzy systems have been used by the authors to develop a representative index that quantifies the power factor in different operating conditions including sinusoidal and non-sinusoidal situations. However, since different fuzzy operators can be used in the fuzzy system, which will affect the measured output power factor index, this paper investigates the implementation of different fuzzy operators when applied to the developed fuzzy system-based power factor evaluation, in different operating conditions. It is found that the use of the ‘algebraic product-sum’ operation offers the most suitable connection method, while the ‘algebraic product’ is the most preferred as an implication method and the ‘maximum’ operation is best suited for the aggregation operation. These combinations offer the most suitable means for establishing a representative power factor under non-sinusoidal conditions with the least computational burden.     

基于微处理器和PWM的交流可调稳压电源的研究

直流稳压电源的类型很多,比较而言交流稳压相对较少.在物联网中传感器类型较多,其中交流电桥检测电路如电容式压力检测电桥、电感式物位检测电桥的应用较多,为提高检测精度都需要频率和幅值都很稳定的交流电源.交流电源的负载有容性、感性、电阻性三种情况,本文首先对电阻性负载构建合适的稳压框架结构,再针对RL负载,分析并设计相应的输...