Table of Content

30 June 2002, Volume 20 Issue 2

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Articles

Multiple Fault Detection for Easily Testable Realizations of Logic Functions

PAN Zhong-liang

2002, 20(2):  111-115. 

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The EXOR-sum-of-products (ESOP) is the most general form of 2-level AND-EXOR networks, it usually requires fewer products than Reed-Muller canonic expressions. A new method of design for testability (DFT) is presented in the paper, which employs AND gates and XOR gates tree to realize the ESOP expression of arbitrary logic functions. The method is able to reduce the delay in the circuits as compared with the approaches using XOR gates cascade. A universal test set which detects multiple faults in the circuit realization is given, it can be generated easily and is independent of the logic function realized. The results have considerable significance on the detection and testable design of multiple faults in the digital circuits.

An Inter leaver with Reduced Storage Memory Requirement for Turbo Codes

ZHAO Guang-ling, WU Le-nan

2002, 20(2):  116-118. 

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This paper presents a new structure of interleaver that saves 50% memories relative to conventional ones. By swapping the odd and even positions, the interleaver has the property of symmetry, and the constraints on the mapping didn't deteriorate the performance of the interleaver. This is important in hardware implementation.

A Study of Turbo Space-time Block Codes

LI Guang-sen, HU Yan-ping, ZHOU Liang-zhu

2002, 20(2):  119-122. 

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Space-time block codes are code technologies which provide a new paradigm for transmit ting over Rayleigh fading channels using multiple antennas. An overview of the space-time codes is made in terms of the system model, encoding and decoding algorithm, design criterion, concatenation of space-time codes and outer codes.

A New Large-scale All-optical Star Coupler for Bidirectional WDM Systems

GAN Chao-qin, SUN Xiao-han, ZHANG Ming-de

2002, 20(2):  123-128. 

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In this paper, a novel large-scale star coupler is presented for the first time. This star coupler can provide a large number of ports for very large-scale single-fiber bidirectional WDM network system in future. The WDM star network composed of star couplers has great flexibility of networking. Its size can be increased conveniently and smoothly on-line by a factor of m. At the same time, the star coupler is still adapted to the single-fiber unidirectional WDM network system being extensively applied nowadays. It provides a good selection for WDM star networks.

Optimized Performance Criterion for STTC and the Serially Concatenated Convolution ally Coded STTC

CHENG Jian, CHEN Ming, CHENG Shi-xin

2002, 20(2):  129-134. 

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In this paper, an improved criterion for STTC construction is discussed. Next a new kind of STTC construction using serially concatenated convolutionally coded modulation with QPSK with Gray mapping is proposed. Simulation shows that Gray mapping is much better than direct mapping, and the serially concatenated convolutionally coded STTCs with Gray mapping outperform the classical STTC proposed by Tarokh or the improved ones proposed by Bäro. The serially concatenated convolutionally coded STTC has good performance and is easy to construct.

A Multi-level DAPSK Performance with Punctured Convolutional Coding

SAYHOOD Khalid Hassan, WU Le-nan

2002, 20(2):  135-140. 

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Punctured convolutional coding with an 8, 16 and 32differential amplitude and phase shift keying (DAPSK) modulation is considered. The performance with an additive white Gaussian noise (AWGN) and Rayleigh fading channels are compared to a coherent 16-quadrature amplitude modulation (QAM). DAPSK modulation parameter such as ring ratio has been optimized for a number of fading conditions. With punctured convolutional coding, the performance of noncoherent 8-DAPSK modulation in an AWGN and Rayleigh fading channels is about 1 dB less than a comparable 16-QAM with a code rate of 8/16 (or 8/24).

Optimization of GMM Based on Hybrid Evolutionary Algorithm and Its Application in Speaker Identification

CUI Yu-hong, HU Guang-rui, HE Xu-ming

2002, 20(2):  141-144. 

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When training data is limited, the performances of speaker identification (SI) system deteriorate owing to the weak generalization of GMM trained by EM algorithm. This paper presents a solution of this problem by using a evolutionary Gaussian mixture model (EGMM) as a modeling method of SI system. Based on evolutionary algorithm, EGMM optimizes both the structure and the parameters of a GMM to better its generalization ability. Also, other speakers' discriminative information is integrated into objective function to increase the accuracy of classification. According to the characteristics of GMM, we design two special evolutionary operators and present a new hybrid evolutionary algorithm using genetic algorithms and evolutionary programming. The preliminary experimental results show that the speaker models based on EGMM have more generalization ability. Compared with traditional GMM, the correct recognition rate of SI system based on EGMM increases by approximate 3%. Furthermore, the GMMS in new system have smaller average size.

A Study of Hi-Bi-NLCFBG Used to Compensate PMD

FENG Xian-jie

2002, 20(2):  145-149. 

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We make a study of a tuning high birefringence nonlinearly chirped fiber Bragg gratings (Hi-Bi-NLCFBG) used to compensate the polarization mode dispersion (PMD) of the high-speed optical fiber communication system and analyze the spectrum characteristics and time-delay for the first time. A method for tuning the Hi Bi NLCFBG by means of PZT is suggested. Finally, we advance a scheme to compensate PMD by a self-adaptive method.

The I-V Character of Tunnel Junction Constituted by Ferroelectric Thin Film PbSrTiO₃

CHEN Hong-wei, MIAO Jiang-ping, ZHAI Ya, WU Zong-han, SUN Cheng-xiu, SUN Ping

2002, 20(2):  150-152. 

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The ferroelectric thin film PbSrTiO 3 is a typical ferroelectric film with wide application. In this paper, the measurement of the I-V characteristics of this thin ferroelectric system, which was prepared by RF magnetron spattering method is reported. We found, for the first time, the negative resistance phenomenon, and interpreted it through the application of the theory of surface plasmon polariton (SPP) and polarized-wave.

The Faulty Systems State Observer and Its Application to Fault Diagnosis in a Class of Nonlinear Systems

CHEN Yu-dong, SHI Song-jiao, WENG Zheng-xin

2002, 20(2):  153-159. 

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The concept of faulty systems state observer (FSSO) is presented for the first time. The difference between FSSO and the traditional observer is analysed, and two possible structures for FSSO are pointed out. A new robust fault diagnosis method based on FSSO for a class of nonlinear systems with bounded uncertainties satisfying Lipschitz condition is proposed and its robustness and sensitivity are also analysed. This method can detect and isolate faults. It can also estimate the characteristics of the fault signal which varies with time. The result of the simulation indicates its validity.

A Study of Chaos Identification Via an On line Training RBF Neural Network

YANG Tao, WANG Xue-lei, SHAO Hui-he

2002, 20(2):  160-164. 

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In this paper, we discuss the online identification of the chaotic system. A novel online training algorithm for RBF neural network is presented. Some problems related to the algorithm are discussed in detail. Simulations show that the algorithm is very effective and can overcome the shortcomings existing in the so-called offline algorithm, We also use this online neural network to identify chaotic systems with good results.

A Design of Object-oriented Data Warehouse Using Snow-star Schema: Its Application in the Power System of Bao Steel Group

ZHENG Bin-xia ng, XI Yu-geng, DU Xiu-hua

2002, 20(2):  165-168. 

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This paper uses the power system of Bao Steel Group as an example and introduces the concepts and characters of the data warehouse. The designing method of data warehouse is given. An OOP data schema based on snowflake schema is given. This paper explains the way of the gathering and visualization of the data.

A Numerical and Experimental Study of the Ventilation of Light-duty Bus

CHEN Jiang-ping, SUN Zhao-pu, QUE Xiong-cai, CHEN Zhi-jiu

2002, 20(2):  169-172. 

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A 3-dimensional ventilation model of a light-duty bus is established by taking the duct into account. The air velocity and temperature inside the passenger compartment are analyzed numerically and experimentally. Both results show that the cooled air flux of discharges are decided by the steady pressure distribution in duct interior. The uniformity of discharge-air can be improved by enlarging the flow area of the duct or using the contractive duct. To simplify the technological process a new duct with 40% flow area enlarged are recommended for the vehicle under study.

B-spline Surface Reconstruction Based on Digitized Section Data

ZHANG Li-yan, ZHOU Lai-shui, CAI Wei-bin, ZHOU Ru-rong

2002, 20(2):  173-177. 

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Digital model reconstruction based on coordinate measuring of existing physical objects is widely used in a variety of situations. The data obtained through popular measuring machines, such as laser scanners, are mostly digitized data organized in sections. In this paper, the problem of B-spline surface fitting based on digitized section data is addressed. An algorithm, which combined bisection and least square method, is put forward. The algorithm can greatly compress the digitized points and generate compact-surface representation while satisfying the given tolerance. Examples in the paper show that the algorithm is effective and practical.

Fuzzy Reasoning Based on Similarity Measure Between the Elements of Vague Sets

LI Fan, XU Zhang-yan, CAI Li-jing

2002, 20(2):  178-182. 

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In this paper, we give a method of similarity measure between the elements of vague sets. When the membership functions (represented by vague sets) of fuzzy terms are continuous functions, we give a one-to-one mapping between the universe of discourse of fuzzy terms in the antecedent of rule and that in the consequent of rule. We also give a method of approximate reasoning based on similarity measure between the elements of vague sets. When the membership functions of vague set are discrete functions, after giving one-to-one mapping between the universe of discourse of fuzzy terms in the antecedent of rule and that in the consequent of rule, we present a method of linear interpolation into the true/false membership functions of the vague sets for the antecedent of rule and fact, converting them into continuous functions. Finally, we provide a method of approximate reasoning based on similarity measure between the elements of vague sets.

Correlation Function of the Highest Lever Sequences of Primitive Sequences over Z₄

LI Chao, FENG Ke-qin, FENG Guo-zhu

2002, 20(2):  183-187. 

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In this paper, possible values of the correlation function of the highest lever sequences of primitive sequences over Z₄ are determined.

A New Method for Choosing the Natural Frequency of the Anti-rolling Tank

LAI Zhi-chang, QU Jia-wen, JIN Hong-zhang, LI Guo-bin

2002, 20(2):  188-192. 

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The natural frequency is one of the parameters characterizing the feature of the anti-rolling tank. Based on the comparative research on the commonly used methods of choosing the natural frequency of the controlled passive anti-rolling tank, this paper develops a new method of choosing the natural frequency for the tank, in which selecting the natural frequency of the anti-rolling tank should be based on the range of variation of wave frequency of the sea area in which the ship operates, the range of the ships rolling frequency and the other dependent factors.

Optimal Inventory Control in Enterprise

YANG Cui-rong, YIN Ping-lin, WANG Ming-zhe

2002, 20(2):  193-196. 

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This article describes how to decide the reasonable stocks in the enterprise inventory management. According to the stochastic stock model, it uses queuing theory to determine the optimal stock and discusses how to decide the queuing model in details. It also adopts the classical stochastic inventory theory to determine the safety stock and combines the queuing theory with inventory theory well to make the stock get the optimal control.

The Distribution of Fluoride in the Natural Environment of the Aksu River Basin and a Chemical Analysis of the Water in Endemic Fluorosis Regions

Fu Wei

2002, 20(2):  197-201. 

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This paper analyses the distribution of fluorine in the natural environment of the Aksu river basin (including quaternary sediment, soil, surface water, underground water, etc.) and researches into the mutual relationship between the morbidity of endemic fluorosis, fluorine and other chemical components in potable water through related analyses and the analyses of the R-clustering system. Basing on this, the author builds the simulated model of multi-variable linear regression between fluorine and the other chemical components in potable water in fluorosis region. Meanwhile, the author also reveals the dominant pathogenetic factors of the morbidity of endemic fluorosis in the region, and expounds the mechanism of how fluorosis pathogeny can be caused by the chemical components in the water and their chemical properties. The result of the scientific research can be used to provide reliable scientific bases for the pathogeny research and pathological treatment of endemic fluorosis caused by drinking fluoric water.

The Theory and Application of Multi-point Flexible Forming for Sheet Metal

CAI Zhong-yi, LI Ming-zhe, YAN Qing-guang

2002, 20(2):  202-206. 

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Multi-point flexible forming (MPF) is an advanced processing technique for sheet metal. In the technique, the functions such as choosing forming path and sectional forming for sheet metal, which can't be realized in traditional method, can be implemented easily. Based on the ideal forming theory, the theory and method to design the optimum forming path for sheet metal in MPF is presented in this paper. The criterion to design the transient area for sectional multi point forming is suggested. The numerical method of elastic plastic large deformation FEM with static implicit scheme for MPF process is established. The optimum forming path of typical 3D-sheet product is calculated by the present method. Using the method and developed software, the MPF process of typical 3D-sheet product is numerically simulated.

A Method for Correcting the Identification Parameters of Grey Prediction Modeling of Dynamic Measurement Errors

GONG Peng, FEI Ye-tai

2002, 20(2):  207-210. 

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In this paper, on the basis of modern error-correction technology, the grey model based on the grey system theory is studied as a short-term predicting model of dynamic measurement errors in order to perform error-correction and improve the accuracy of dynamic measurement. Here, the identification and correction of the parameters of the model are analyzed. Taking the example of long gating measuring system and discussing its dynamic measuring errors, a method is developed for-correcting the model's identification parameters which affect the measurement results during predicting. Therefore, the measurement accuracy is improved.

The Research on and Application of the Slab Design Software for Heavy Plate Production

ZHAO De-wen, DONG Xue-xin, LIU Xiang-hua, WANG Guo-dong

2002, 20(2):  211-214. 

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Based on a lot of spot measurement and trial work, the customary rule of slab design of the heavy plate was modified. According to the modified rule, an expert system software of slab design for plate production was successfully programmed and used in computer. After a year's application of the software, the yield of the plant increased by 1.61% per year and an obvious economic benefit was obtained.

Research Notes

The Technology of Rotating Cone Pyrolysis of Biomass

ZENG Zhong

2002, 20(2):  215-217. 

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In this paper, a biomass flash pyrolysis system with a rotating cone reactor is introduced. As an example, we define the process of pyrogenation and liquefaction of wood-bits and the related technical parameters.

The Corrosion Behavior of the Separator in Molten Carbonate Fuel Cell

SHEN Xia, FANG Jian-hui, ZHU Xin-jian, YAN Li-cheng, CAO Guang-yi, CHEN Nian-yi

2002, 20(2):  218-220. 

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The corrosion behavior of the separator in molten carbonate fuel cells was studied. X ray diffraction (XRD) scanning electron micrographs (SEM) and ion analysis were employed to study the hot corrosion products. It is shown that the chief components of the corrosion products included NiFe₂O₄, LiFeO₂, NiCr₂O₄ etc. Meanwhile, through the measurement of the corrosion dynamics of the bipolar boards as well as the anode and the preliminary discussion of the corrosion mechanism, it is known that their hot corrosion rate is relatively fast, corrosion layers are relatively loose and there is possibility that they have co corrosion effect.