Table of Content

30 June 2000, Volume 18 Issue 2

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Articles

Display of 3D Chemical Structure on the Internet

HE Min, ZHOU Jia-ju

2000, 18(2):  95-100. 

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A program——VRMLMaker has been developed for the 3D chemical structure display on the Internet in our chinese drug database retrieval system (CDDBRS). VRMLMaker can convert a molecular MOL2 or ML2 format file to VRML format files in four different styles:wire frame, capped sticks, ball-and-stick, and a CPK space-filling model. VRMLMaker is developed based upon molecular model and virtual reality modeling language(VRML) techniques. The working procedures of VRMLMaker are described. The utility of VRMLMaker is illustrated by an example and four style VRML scenes are also given for demonstrating the function of VRMLMaker. It is shown that the usage of VRML is a very efficient and powerful method for the transport of 3D molecular models on the Internet.

Inverse Question of Period Distribution of Cyclic Codes

LI Chao, XIE Dong-qing

2000, 18(2):  101-103. 

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This paper studies the inverse question of period distribution of cyclic codes——whether there exists some[n,k]-cyclic codes over finite field F_q for a given positive integer n and a nonnegative integer sequence {A₁,A₂,…,A_n},so that the period distribution of these codes is exactly {A₁,A₂,…,A_n}.

Application of Piezoelectric Micro-actuator in Computer Hard-disk Drive

LI Guo-rong, CHEN Da-ren, ZHANG Shen, SHEN Wei, YIN Qing-rui, BI Chao, GUO Wei, ZHENG Guang-de

2000, 18(2):  104-108. 

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Hard-disk drive is one of the most important parts in the computer. A new type actuator with dual -track system controlled by a multilayer piezoelectric actuator has been designed and fabricated. The time dependence and frequency response of the driver are measured by laser detecting system and the performance of the actuator with hard-disk dual -track system is discussed on the basis of the characterization of the piezoelectric actuator and finite element method.

An Authentication and Encryption Method Suitable for Intelligent Memory IC Card

YU Lin, GAN Jun-ren

2000, 18(2):  109-113. 

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For the application of intelligent memory IC card, it is critical to design a suitable method of authentication and encryption. The characteristic of intelligent IC card and the principle of authentication and encryption method are discussed in this paper. After comparing the merits and demerits of some popular encryption algorithms, a new authentication and encryption method, which can be realized in chip economically is presented. The chief features of the method, the authentication procedure between IC card and IC card interface device and realization of our encryption algorithm are also discussed.

Superresolution of Chirp Signals and Its Applications to Three Dimensional Imaging of Maneuvering Targets

ZHANG Qun, MA Chang-zheng, ZHANG Shou-hong

2000, 18(2):  114-116. 

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For a maneuvering target, the Doppler of scatterers take the form of LFM signals after movement compensation. Superresolution methods are based on the models of both the signal and the noise. In this paper, we extend the Relax algorithm to the case of LFM signals and apply it to monopulse three-dimensional imaging. Simulation results shows that the images thus formed are superior to those formed by the traditional dechirping method.

Target Location and Speed Estimation Based on a Multistatic Radar System Using the Maximum Likelihood Approach

WEI Chong-yu, XU Shan-jia, WANG Dong-jin

2000, 18(2):  117-121. 

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This paper describes a short range target location and speed estimation system based on the range difference of a T-Rⁿ multistatic radar system with FMCW signals.The maximum likelihood method for target location and speed estimation by using the high resolution of wide band FMCW signals is discussed. Formulae independent of the transmitter position are derived for target location and speed estimation. System performances are simulated with the proposed algorithm and the results are given for various situations.

An Iterative Algorithm for Locating a Hole in Semi-infinite Planar Conductive Medium

GUO Fei, MA Xi-kui, QIU Guan-yuan

2000, 18(2):  122-126. 

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A novel method concerning the problem of locating a hole in two-dimensional semiinfinite plane is presented. The relationship between surface metrical potential and the parameter of object shape and location is obtained by using the boundary integral equation. On the basis of that, the mathematical expression about the influence of tiny object parameter change upon surface potential distribution is derived with the reference of Newton-Kantorovich method used to solve the problem of electromagnetic inverse scatter. In the condition of initial values available, the two equations can be figured out iteratively and the true value can be approached gradually. In order to solve the ill posed equations, the damping least square method is used by choosing a proper damping factor to make the result stable. Compared with the hybrid method of finite element method and least square method for this problem, the proposed method here is more efficient.

A Study of Simulation Techniques Used in the RF Receptive System for Radio Paging

WU Jian-hui, GE Jun, SHI Long-xing

2000, 18(2):  127-130. 

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Computer is usually used to help the design of radio paging's RF receptive system. In this paper the difficulties involved in using MATLAB directly to simulate RF receptive system are discussed, and the solutions to these difficulties are also proposed. Finally, simulation is carried out to verify the application of the method to radio paging's FSK demodulation.

Getting the Fractal Characteristics of Rough Surface by Scattering Coefficient

WANG Min-xi, LI Jing, REN Lang

2000, 18(2):  131-134. 

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A method of getting the fractal characteristics of rough surfaces i.e. Hausdorff dimension by scattering coefficient is presented. The concept of "scaling range" and the fractal interpolation are discussed. In this method, the characteristics of fractal function is fully considered when it is used to characterize the rough surfaces and the method makes the work getting the fractal characteristics of rough surfaces simple and clear.

A Study of Pulse Waves and the Method of Function Combination and Approximation

CHANG Chang-yuan, LUO Xuan, MIAO Bing-you, WEI Tong-li

2000, 18(2):  135-138. 

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The formative mechanism of pulse waves is studied in this paper. The method of function combination and approximation is adopted to analyze arteriosclerosis and the characteristic parameter of pulse waves through its change of waveform is obtained. Preliminary clinic application shows that the concept contained in this method is clear, intuitive and effective.

The Genetic Optimization Method for the Inverse Reconstruction of Temperature Distribution in Bio-heat Control

SHI Yu, LU Ming-zhu, NIE Zan-kan

2000, 18(2):  139-142. 

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For inverse reconstruction of temperature fields in bio -heat transfer control, it is very important to estimate the parameters, such as thermal conductivity K, blood perfusion rate W_b etc. In bio -heat transfer Pennes equation. A new method of parameter identification by means of the genetic algorithm is proposed in this paper to carry out inverse reconstruction of temperature fields. The application of this method to the model of hyperthermia is also suggested.

MR-CGS: A Minimal Residual CGS Method and Its Application in DDM

ZHAO Jia-bao, SHENG Zhao-han, WEI Tong-li

2000, 18(2):  143-147. 

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Due to the instability of the residuals aroused in the conjugate gradient square method, we present a new method named MR-CGS, which has the minimal residual property while retaining the square converging property. Finally, an example is given to exhibit the application of the improved algorithm in solving the DDM model.

A Study of Mechanical Reliability Design with Fuzzy Information and Its Applicatioin

DONG Yu-ge, CHEN Xin-zhao, WANG Chun-xian, ZHU Wen-yu

2000, 18(2):  148-152. 

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By means of the transformation from fuzzy reliability design into general reliability design, this paper gives some elemental formulae which can be used in simulating failure probability with random stress and fuzzy strength, and studies its application in mechanical design.

Tolerance and Fit Design in Consideration of Thermal and Assembling Deformation

HU Peng-hao, FEI Ye-tai, HUANG Qi-sheng

2000, 18(2):  153-155. 

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Thermal and assembling deformation seriously affects journal bearing accuracy. With the aid of heat transfer theory and elastodynamics, the paper makes a thorough analysis of the deformation in journal bearing and provides a theoretical basis for designing tolerance and ensuring working accuracy.

Application of Integral Imaging Method in Motion Measurement

BAI Shun-ke, WANG Feng-quan

2000, 18(2):  156-160. 

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Based upon the linear integral imaging mechanism of the CCD image sensor, this paper presents a new method for measuring the motion of a moving object. By this new method, for determining the motion of a rigid body, only two time integral pictures are captured for a LED attached onto the surface of the body; the first picture was recorded when the body was in static state and the second picture was captured when the body was in motion. Experimental results have shown that the method can be used to determine displace -time and velocity -time functions of a moving object with reasonable accuracy. The method can also record the motion orbit of the moving object.

Study on a New Ultrasonic Vibration Cutting lnstrument

WEN Ren-lin, YAN Jing-ping

2000, 18(2):  161-163. 

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Power of ultrasonic vibration cutting (UVC) is analysed and calculated. The author suggests a new method, in which a new vibration cutting instrument equipped with a piezoelectric transducer and cutting tools driven directly is adopted. Experimental results show that this method can improve the surface quality and precision of precision machining.

A Study of the Method to Increase the Production Rate of Ultrafine Ni and Cu Powders

SUN Wei-min, JIN Shou-ri, LI Zhi-jie

2000, 18(2):  164-166. 

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The effect of high -melting-point metals W and Mo on the production rate in the preparation of ultrafine Ni and Cu powder using "hydrogen plasma-metal" reaction method is investigated. It is indicated that the production rate has been improved. And the ultrafine powders hardly contain any W and Mo. The causes of high production rate are also discussed.

Numerical Analysis and Experimental Confirmation of Underground Temperature Field of Vertical Double Spiral Coil for Ground Source Heat Pumps

BI Yue-hong, CHEN Lin-gen

2000, 18(2):  167-170. 

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The underground two-dimension symmetry temperature field of a vertical double spiral coil heat exchanger designed by the authors for the ground source heat pumps is calculated by using the volume-control method. The calculation results are consistent with the experimental results obtained. The mathematical model presented here may provide design guidance for the design of underground heat exchanger for ground source heat pumps.

Study on the Preparation of Nanometer Ferric Oxide in Terms of SCFD Technique

CAN Wei-liang, ZHANG Jing-chang, SHI Jin-hua, YU Ding-xin

2000, 18(2):  171-174. 

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Nanometer ferric oxide were prepared by sol-gel and supercritical fluid drying (SCFD) method. The nanometer ferric oxide powders were characterized in terms of XRD, and TEM techniques. The dependence of particle size on preparation conditions was also investigated. It was found that the drying and crystal can be achieved in one step by the SCFD technique.

A Study on the Synthesis and Character and Application of K₅[(H₂O)Al(or Ga)(ZrW₁₁O₃₉)]°XH₂O

WANG Wei, NING Fei

2000, 18(2):  175-178. 

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This paper deals with the methods involved in the synthesis of K₅[(H₂O) Al(or Ga)(ZrW₁₁O₃₉)]°XH₂O which is charaterized by IR, UV, XRD, XPS, TG-DTA and chemical analysis. The results indicated that the complexes are the derivatives of Keggin structure complexes. Their function as corrosion inhibitors of iron is also studied.

A Study of Cylindrical MH/MnO₂ Rechargeable Battery

GUO Zai-ping, XIA Xi

2000, 18(2):  179-182. 

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The AA -type MH/MnO₂ rechargeable battery is briefly described. The problems involved in making the battery and its solution are also discussed. Many tests of AA -type MH/MnO₂ rechargeable battery have been carried out, the test results indicate that the MH/MnO₂ cell has a better cyclic performance than that of the Zn/MnO₂ rechargeable battery. And its storage performance is obviously superior to that of the MH/Ni cell, thus it has a promising future.

Effect of Concentration Gradient of Vacancies on Diffusion in Double Glow Plasma Surface Alloying

LI Zhong-hou, LIU Xiao-ping, XU Zhong

2000, 18(2):  183-185. 

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In double glow plasma surface alloying(DGPSA), high vacancy concentration, high dislocation density and high concentration gradient of vacancies are produced at a definite depth under surface by ion bombardment.
This paper derives the expression of the diffusivity of molybdenum from diffusion flow. Based on vacancy mechanism, it also analyzes the effect of the high vacancy concentration and high concentration gradient of vacancies on diffusion of metal atoms. It points out that these are the main reason why the penetrating velocity of DGPSA is higher than that of conventional diffusion processes.

Fabrication and Characteristic Study of V-P-Fe CTR

SUN Jian, GAN Chao-qin, LIU Ying, WU Zong-han

2000, 18(2):  186-188. 

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In this paper, a method of fabrication of V-P-Fe's CTR was described. Ψ, R_c, T_c of specimens with different composition were measured. The composition with optimum characterization was determined.