Table of Content

31 March 1998, Volume 16 Issue 1

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Articles

A Reliability Model for RealTime Multitasking Software

LEI HANG, XIONG GUANGZE, LIU JINDE

1998, 16(1):  1-5. 

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By taking the task modulars as a basic testing unit, an evaluation model of the real-time multitasking software is presented in this paper. Since the parameters in the model are easy to be analysed and tested, this model is useful in evaluating the reliability of the real-time multitasking software.

An Image Edge Detection Algorithm Based on Two-Dimensional Wavelet Transforms

XIE MEI, MA ZHENG, GU DEREN

1998, 16(1):  6-11. 

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The sharp variation of gray levels of an image, measured at different scales, can be detected from the local maxima of its wavelet transform. In this paper we describe an algorithm that can extract the edges of an image. The model is based on the two-dimensional dyadic wavelet transform. It provides information of the image boundaries by determining the local maxima of the two-dimension wavelet transform of an image at dyadic scale. Experimental results shows that this method is quite effective.

Applications of Exponential Sums to Spreading Sequences Designs

LI CHAO

1998, 16(1):  12-17. 

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Let p be an odd prime, n,e,m and r be integers satisfying the following conditions:n=em,1 ≤ r ≤ e-1,(r,e)=1. Let k be a complex primitive pth root of unity and J:z→k^trm₁(z) be the nontrivial addition character of the finite field F_q(q=p^m). For every pair a,b∈F_q^e,Let e_(a,b) denote the exponential sum:e_(a,b)=∑_x∈Fq^eJ[tr_mⁿ(ax+bx^qr+1)], where tr_mⁿ(°) denotes the trace function of F_q^e over F_q. In this paper we determined the values of the exponential sum e_(a,b) and discussed the applications of exponential sums in spreading sequences designs.

A Polynomial Time Algorithm for Maximum Lateness in Single Machine Scheduling with Batching

SUN SHIJIE, ANDREWS BOADI, LIU ZHAOHUI

1998, 16(1):  18-23. 

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N jobs arrive at same time and need to be processed in batches by the same machine. The jobs in the same batch are processed successively and the completion time of all the jobs in the same batch is defined as the completion time of the batch they belong to. There exists a set up time whenever the machine begins to process a new batch. Taking the maximum lateness as objective function, this paper develops a polynomial time algorithms for the processing sequence of the n jobs given or not given.

A Continuum Percolation Model of Cubic Particles for Dispersed Ionic Conductor The Effects of Particle Size on Critical Threshould and Conductivity

PANG QIANJUN

1998, 16(1):  24-31. 

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A continuum overlapping model of cubic particles is introduced based on ge neralized lattice model of discrete overlapping particles for the dispersed ionic conductors. By using this model, the relationship between the concentration and the density of DIC system is found out. With the effective medium approximation(EMA), the effects of the particle size on the critical threshould and condutivity are studied and discussed.

Single Chip FPGA-Based Data Acquisition Module for Multichannel VFC Signals

GONG XIANGDONG

1998, 16(1):  32-36. 

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The hardware design and implementation of a data acquisition module for 8 channel voltage-to-frequency conversion (VFC) signals are described. This module is mainly comprised of a counting-buffering unit, a FIFO RAM, a RS232C serial communication port and a control unit. The module is implemented in a single chip Xilinx field programmable gate array (FPGA). With Xilinx FPGA, the benefits from the design such as short time to market, high reliability and compactness for the whole system can be obtained.

“Fictitious Circuits” and Its Applications in the Solution of Large-Scale Networks by Tearing

LI FENG, DENG TIEJUN

1998, 16(1):  37-43. 

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Fictitious Circuits——a new concept is presented for analyzing large-scale networks by tearing. The concept unifies branch tearing, node tearing and hybrid tea ring, i. e. the concept is more general and includes all the previous tearing as special ca ses. Based on fictitious circuits, the tearing equations of Bordered Brock Diagonal form can be founded conveniently and directly. The method presented in this paper is usable for the solution of large-scale networks by any kind of tearing.

Micromagnetic Calculation of the Magnetic Pro perties for the Nanometerscale TwoPhase Exchange-Coupling Permanent

YANG SHIQING, HE SHIGUANG, WANG HAOCAI, ZHANG WANLI

1998, 16(1):  44-50. 

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Based upon micromagnetics and variational method of the total free energy of the magnets, we derived Brown equation of the magnetization for the aligned nanom-eterscale two-phase exchange-coupling permanent. For the case of the aligned two-phase exchange-coupling permanent, this Brown equation is similar to static Schrdinger equation. By means of the method of resolving the central-field problem, we obtained the dependence of the nucleation fields of the two-phase exchange-coupling permanents vary with the particle sizes of hard magnet phase. It's shown that the excellent magnetic properties of permanents are obtained when the sizes of the twophase crystals are smaller than the critical sizes, respectively. The present calculation results can be used to explain the known experimental results and provide the theoretical reference for the preparing of the giant-magnetic energy product permanents.

Macromodel of MCM Interconnection Delay and Its Physical Scaling

LAI JINMEI, LIN ZHENGHUI

1998, 16(1):  51-55. 

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Macromodel of MCM interconnection delay is developed in this paper. With this model it is shown that the most important parameters dominating the performance of MCMs are the average distance between the chips and the size of the load capacitance.

Influence of the Stochastic Factors in Soliton Transmission System and Its Suppression

CHEN MINGHUA, WEN YANGJING, YANG XIANGLIN

1998, 16(1):  56-61. 

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Transmission properties of soliton system influenced jointly by stochastic variation of fiber parameters, ASE noise of amplifiers and interaction between neighboring solitons are considered in this paper. It is shown that stochastic variation of fiber parameters can change only the amplitude and energy of solitons when it exists alone in system and the arrival time jitter can be denied. However, when it exists with ASE noise and interaction, arrival time jitter of soliton becomes serious. It is proven that the jitter can be suppressed by filters.

Deforming Force Relationship Between Axisymmetric State and Plane Strain State in Extrusion Technology

LI SHUANGYI, ZHOU LIHUA, MENG FANZHEN

1998, 16(1):  62-67. 

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Except slip line solution for plane strain state, there is no accurate solution for axisymmetric state in plastic forming problem so that it is quite difficult to find the deforming force relationship between the two kinds of states. After a great amount of investigation, analysis and experiments of numeric solution formula in extrusion technology, corrcspondent optimal formula are put forward in this paper. Moreover, by means of formula comparison method, the deforming force relationship is found to be 1.7~2 for forward extrusion and 1.75~2.2 for compound extrusion.

Study on the Directivity of Gauss Beam Generated Thermoelastic Ultrasound in Non-Metallic Solids

WU YAPING, SHI DUFANG, HE YULONG

1998, 16(1):  68-73. 

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The directivity of Gauss beam generated ultrasound in non-metallic solids are stutied theoretically. We solve the thermoelastic wave equations by means of the integral transform mathod and obtain analytic expressions of the wave displacements in the far-field. We also present directivity patterns of both longitudinal and shear waves, discuss the effects of optical absorption coefficient on the diretivity of the ultrasound waves and compare them with the experimental results.

AnalysisofLaminarFlowand Heat Transfer of Falling Liquid Film Along a Vertical Plate in the Developing Region

SHI JINSHENG, SHI MINGHENG

1998, 16(1):  74-80. 

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The characteristics of laminar flow and heat transfer of falling liquid film along a vertical plate in the developing region are analyzed by using the boundary layer similarity solution. The relationship between the developing length of hydrodynamic and thermal boudary layer and heat transfer coefficient for constant surface temperature are obtained.

Study on Neural Network Diagnosis System Based on Characteristics of Flame Image

YANG HONGMIN, TANG XIAOJUN, LIU YONG, GU FAN, XU YIQIAN

1998, 16(1):  81-87. 

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The image characteristics of gas flame and pulverized coal flame is studied experimentally and theoretically by using computer digital image processing technology. Based on flame characteristic extraction, the theory of neural network is applied to study the flame recognition. The method of flame combustion recognition is proposed and a practical intelligent flame diagnosis system is developed.

Phase Diagrams and Relationships Between Energetic Parameter f(r) and Ratio of Crystallization for Nine LiCl-M'Cl₂-MF Molten Salt Systems

YAN LICHENG, FANG JIANHUI, LU WENCONG, YANG JINXIU, XU JINGYAN

1998, 16(1):  88-93. 

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In this paper, the relationship between the energetic parameter f(r) of molten salt system and the ratio of primary crystallization compound has been exa mined. A number of multi component molten salt systems of LiCl-M'Cl₂-MF have been tested and their corresponding phase diagrams have been obtained.

De-Amine (Tetraethylammonium) Effects of Microwave on the Structure and Acidity of Zeolite β

YANG XINGBIN, HE JING, LI FENG, DUAN XUE, WANG ZUOXIN

1998, 16(1):  94-99. 

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The effects of the thermal decomposition of tetraethylammonium (template) by microwave on the surface acidity and structure of zeolite β are studied by TPDE,TPD and XRD. Results show that (1) the most part of template is eliminated after zeolite β has been irradiated for 40 minutes by microwave, (2) the surface acid amount evidently increases and β has three types of acidic sites which are of different strength, and (3) the strength of strong acid sites remarkly decreases compared with the traditional method. In addition, the method to remove the template can successfully maintain the crystallinity of zeolite β.

Investigation of Far Region Fields Scattered From Fractal Surfaces in Frequency and Time Domain

WANG MINXI, LI JING, REN LANG

1998, 16(1):  100-105. 

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In this paper, fractal function is used to model the rough surface for investigating the interaction of incident plane wave and rough surface in frequency and time domain. The different characteristics for different parameters of the fractal function in time domain are presented.

Collision Detection Between Convex Polyhedra:a Foundation for Collision -Free Path Planning

ZHU XIANGYANG, ZHONG BINGLIN, XIONG YOULUN

1998, 16(1):  106-111. 

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This paper deals with the collision detection problem by investigating the distance function between 3-D convex polyhedra in the sense of L₁ metric and L_∞ metric. The characteristics of both the L₁ distance and L_∞ distance, such as their topological property, Lipschitz continuity, equivalence to the Euclidean distance, etc, are investigated. The linear programming based approaches for the evaluating of L₁ distance and L_∞ distance are also proposed. The results of this paper form a basis of collision free path planning for robot manipulators.

The Engineering Improvement for Weakening the Bad Effect of Natural Wind on the Dry Cooling Towers

HAO ZHENGUO, SHI JINLING, WEI QINGDING, ZHANG BOYIN

1998, 16(1):  112-120. 

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The bad effect of natural wind on dry cooling towers (Heler type) is studied. And an engineering improvement is suggested to weaken this effect.

Calculation of the Speed -Temperature Relationship in Axisymmetric Extrusion Process

HUANG XIANG, LIAO WENHE, ZHOU RURONG

1998, 16(1):  121-126. 

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A finite difference model of heat balance in axisymmetric extrusion process is constructed. In this model, a kinematically admissible velocity field is adapted and a rise in temperature is calculated by considering the heat generation due to deformation and friction, heat transfer and material flow, etc. Using this model, not only the rise in temperature during constant speed -extrusion process is calculated, but also the profile of ram speed temperature for simulant constant exit temperature extrusion and constant temperature extrusion under a specified exit temperature is calculated. The results are well in agreement with those of the experiments. The model can be used to optimize process parameters of hot extrusion.