Tracing of the 1st IEC Secretariat Assumed by China

Introduction The IEC central office informed in 7/543/AC that the secretariat of TC 7 would be taken over by the Chinese National Committee on January 10, 2003 and affirmed subsequently in 7/544/AC that the secretariat of TC 7 has been taken over by the Chinese National Committee which appointing secretary in Shanghai Electric Cable Research Institute as no objection has been raised by the Standardization Management Board members. It's the first IEC secretariat that assumed by China, with great significance, just as commented by the media that the commitment indicate undoubtedly China is to play a much more active and important role in the world especially after its entry into world trade organization as well as the trend of global economic integration.     

一种基于空间到达角的卫星电子侦察信号分选方法

在建立简化的卫星电子侦察空间模型的基础上，提出了一种利用空间到达角分选卫星电子侦察信号的新方法。通过仿真实验验证了这种方法的可行性。该方法可用于密集信号的预处理。     

Derivation of a second-order switching surface in the boundary control of buck converters

A second-order switching surface in the boundary control of buck converters is derived in this letter. The formulated switching surface can make the overall converter exhibit better steady-state and transient behaviors than the one with a first-order switching surface. The switching surface is derived by estimating the state trajectory movement after a switching action, resulting in a high state trajectory velocity along the switching surface. This phenomenon accelerates the trajectory moving toward the target operating point. The proposed control scheme has been successfully applied to a 120-W buck converter. The large-signal performance and a comparison with the first-order switching surface have been studied.     

基于移动代理的网络拓扑发现研究

提出了一种基于移动代理的分布式网络管理系统模型,阐述了该系统发现网络拓扑的过程,介绍了具体算法思想,给出了数据结构和算法描述,最后进行了仿真,证明了算法的有效性.     

On the capacities of bipartite Hamiltonians and unitary gates

We consider interactions as bidirectional channels. We investigate the capacities for interaction Hamiltonians and nonlocal unitary gates to generate entanglement and transmit classical information. We give analytic expressions for the entanglement generating capacity and entanglement-assisted one-way classical communication capacity of interactions, and show that these quantities are additive, so that the asymptotic capacities equal the corresponding 1-shot capacities. We give general bounds on other capacities, discuss some examples, and conclude with some open questions.     

基于TMS320VC5410的最小系统设计

TMS320VC5410是TI公司生产的一款定点数字信号处理(DSP)芯片。基于DSP的最小系统是以其简洁的硬件结构来实现DSP的一般功能,广泛应用于工业生产、教学、科研、电子设计等领域。主要介绍了基于TMS320VC5410的最小系统硬件电路设计方案,阐述了重要电路部分的抗干扰设计和软件调试过程中应注意的若干问题。最后提出了简单易行的软件调试方法以及部分程序代码。     

Classification of audio radar signals using radial basis function neural networks

Radial basis function (RBF) neural networks are used to classify real-life audio radar signals that are collected by a ground surveillance radar mounted on a tank. Currently, a human operator is required to operate the radar system to discern among signals bouncing off tanks, vehicles, planes, and so on. The objective of this project is to investigate the possibility of using a neural network to perform this target recognition task, with the aim of reducing the number of personnel required in a tank. Different signal classification methods in the neural net literature are considered. The first method employs a linear autoregressive (AR) model to extract linear features of the audio data, and then perform classification on these features, i.e, the AR coefficients. AR coefficient estimations based on least squares and higher order statistics are considered in this study. The second approach uses nonlinear predictors to model the audio data and then classifies the signals according to the prediction errors. The real-life audio radar data set used here was collected by an AN/PPS-15 ground surveillance radar and consists of 13 different target classes, which include men marching, a man walking, airplanes, a man crawling, and boats, etc. It is found that each classification method has some classes which are difficult to classify. Overall, the AR feature extraction approach is most effective and has a correct classification rate of 88% for the training data and 67% for data not used for training.     

Data-efficient blind OFDM channel estimation using receiver diversity

We investigate non data-aided channel estimation for cyclically prefixed orthogonal frequency division multiplexing (OFDM) systems. By exploiting channel diversity using only two receive antennas, a blind deterministic algorithm is proposed. Identifiability conditions are derived that guarantee the perfect channel retrieval in the absence of noise. In the presence of noise, the proposed method has the desired property of being data efficient-only a single OFDM block is needed to achieve good estimation performance for a wide range of SNR values. The algorithm is also robust to input symbols as it does not have any restriction on the input symbols with regard to their constellation or their statistical properties. In addition, this diversity-based algorithm is computationally efficient, and its performance compares favorably to most existing blind algorithms.     

分布式无线传感器网络通信协议研究

在归纳分布式无线传感器网络研究进展的基础上，给出了综合分布式无线传感器网络技术各个方面的协议体系结构，并在新的体系结构下，系统地阐述了分布式无线传感器网络通信协议研究的进展，介绍了典型的应用案例和国外相关计划的研究情况。最后，指明了这一处于发展初期的研究领域的未来发展方向。     

Phosphorus‐containing polyaryloxydiphenylsilanes with high flame retardance arising from a phosphorus–silicon synergistic effect

Polyaryloxydiphenylsilanes were prepared from phosphorus‐containing diols and diphenydichlorolsilane through solution polymerization. With a stoichiometric imbalance in feed monomers, the resulting polymers exhibited moderate melting points and good processing properties. The polymers prepared showed initial decomposition temperatures above 340 °C, excellent thermal stability, high char yields at 850 °C and very high limited oxygen index values of 56–59. The polymers' char yields and their (P + Si) contents showed linear relationships. © 2003 Society of Chemical Industry