Table of Content

31 March 2001, Volume 19 Issue 1

Previous Issue    Next Issue

Articles

Synchronizing Chaos via APD and Activeoccasional Coupling

LI Guo-hui, XU De-ming, ZHOU Shi-ping, LAI Jian-wen

2001, 19(1):  1-4. 

Asbtract ( 321 )   PDF (181KB) ( 87 )  

Related Articles | Metrics

We have realized Henon synchronization via APD synchronization, in which we acquired synchronization of identical systems. The nonsynchronization of unidentical systems makes the method potentially useful in secure communication. Because chaos synchronization by coupling continuously is not easy, we realized Henon synchronization by occasional coupling synchronization. As long as the synchronization phases exceed the critical value, synchronizing Henon mapping by occasional coupling can be obtained. The same results have also been achieved by synchronizing Henon-like.

MQAM Digital Communication Adaptive Equalizers Using Wavelet Networks

ZHANG Guo-an, ZHANG Xiao-dong, BI Guang-guo

2001, 19(1):  5-9. 

Asbtract ( 323 )   PDF (218KB) ( 130 )  

Related Articles | Metrics

In this paper, a novel wavelet network based adaptive equalizer (WNBAE) is presented. The structure and stochastic gradient learning algorithm of the WNBAE is given. In the MQAM digital communication reception systems over nonlinear channels the proposed WNBAE has better performance than that of the conventional linear transversal equalizer based on the LMS or the RLS algorithms, as well as that of the decision feedback equalizer based on the RLS algorithm. It outperforms slightly the back propagation network based adaptive equalizer. Several simulations are performed to evaluate the behavior of the WNBAE.

Transmission Characteristics of Taper TEM Cell

CUI Fu-rong, LAI Sheng-li, JI Fei, HU Bing-jie

2001, 19(1):  10-13. 

Asbtract ( 302 )   PDF (174KB) ( 110 )  

Related Articles | Metrics

This paper analyzes a new type of taper TEM cell using FDTD method in the spherical coordinate. The field distribution, field uniform and the upper work frequency have been analyzed. The results prove very important to the design and application of taper TEM cell.

A Trial Research on the Design and Decision Expert System of Land Rational Use

FU Wei

2001, 19(1):  14-19. 

Asbtract ( 272 )   PDF (249KB) ( 80 )  

Related Articles | Metrics

This paper presents the approaches and principles for building design and decision expert system of land rational use (DDES). The system can be used to evaluate and decide the plan on the geo expert level for the rational use of land. Furthermore, several practical suggestions can be obtained by consulting the system, so that the users can select an effective plan for utilizing the land. By citing the formulation of the DDES of the Urumqi River basin as an example, the author expounds the method to express expert knowledge of planning and decision for rational use of the land in the basin as well as the basic rules to express the knowledge contained in the expert system and the organization modes of expert knowledge in the knowledge base. In addition, the author discusses the design principles and organization method of inference rules and the inference algorithms.

An All-digital Receiver for Mobile Satellite Burst Communication

CHEN Yin-jian, LI Li, Li Guo-tong, LIANG Xu-wen, YANG Gen-qing

2001, 19(1):  20-23. 

Asbtract ( 258 )   PDF (183KB) ( 167 )  

Related Articles | Metrics

Mobile satellite burst communication operates under severe noise conditions, large Doppler offset, fast Doppler frequency shifts, and multi-path fading, so synchronization in receiver becomes very difficult, especially when the burst frame is too short. This paper proposes a new all-digital receiver structure, which relies on FFT-based burst acquisition and non-coherent detection. Simulation results demonstrate that the receiver can work under large frequency offset and have short acquisition time, so that can be used in mobile satellite burst communication.

A New Kind of Absorbing Boundary Condition and Its Application for 3-D TLM Method

SHAO Zhen-hai, ZHU Chen-dong, HONG Wei, HE Li-quan

2001, 19(1):  24-28. 

Asbtract ( 294 )   PDF (214KB) ( 88 )  

Related Articles | Metrics

A new kind of absorbing boundary conditions based on the theory of generalized Z-domain absorbing boundary conditions (Z-ABCs) for the 3D TLM SCN method is presented. The results indicate that the Z-ABCs show better performance than Higdon's ABC in suppressing instability caused by spurious modes. The different order coefficients of this new Z-ABCs can be given by a recurrence formula.

The Learning Algorithm of the Second Order HMM and Its Relationship with the First Order HMM

SHI Xiao-xing, WANG Tai-jun, HE Zhen-ya

2001, 19(1):  29-32. 

Asbtract ( 385 )   PDF (169KB) ( 99 )  

Related Articles | Metrics

In this paper, we investigate the learning algorithm of the second order HMM (HMM2), which includes the forward variable algorithm, backward variable algorithm, Viterbi algorithm and Baum-Welch algorithm. Meanwhile, we study the relationship between the HMM2 and the first order HMM (HMM1), and find that for any HMM2 there always exists a HMM1 which is equal to the HMM2. We propose and prove the equivalent theorem of the HMM2 and HMM1.

Paramatric Adaptive Decomposition Based on Gaussian Elementary Functions and Related Adaptive Time-frequency Distribution

MA Shi-wei, DEN Jia-mei, CAO Jia-lin

2001, 19(1):  33-36. 

Asbtract ( 458 )   PDF (177KB) ( 97 )  

Related Articles | Metrics

We propose a method of adaptive signal decomposition based on the linear frequency modulated Gaussian elementary functions and the related adaptive time-frequency distribution that is positive, cross-term interference free and with better time and frequency resolution. The set of the elementary functions is obtained by the successive matching of the signal local nature with the single prototype Gaussian function through regulating its variance, sweep rate, translation and modulation in an adaptive manner. The matched coefficients and the parameters contain all the information of the signal and can be used for the further processing of the signal. The effectiveness of the method has been proved by simulation results.

The Decoupling Problem of a Class of Time-delay Nonlinear Systems

FU Yu-sun, TIAN Zuo-hua, SHI Song-jiao

2001, 19(1):  37-39. 

Asbtract ( 365 )   PDF (131KB) ( 85 )  

Related Articles | Metrics

This paper is concerned with the decoupling problem of a class of time-delay nonlinear systems. A controller is used so that the output is decoupled from the delayed state and disturbance.

The Study and Development of a New Omni-directional Vehicle Applied in the Wall-climbing Robot

TAN Shi-li, ZHANG Hai-hong, GONG Zhen-bang

2001, 19(1):  40-43. 

Asbtract ( 324 )   PDF (171KB) ( 83 )  

Related Articles | Metrics

Considering the special requirements for wall-climbing cleaning robot, a new type of omni-directional mechanism which can cross obstacles has been developed. This omni-directional mechanism can make the wall-climbing robot not only move in all directions on the wall without changing its pose or rotate at any angle at its original place but also overstep the obstacles such as the window frame in its routing.

Discriminating the Existence of Inverse Kinematics Solution of Underfreedom-robot by Neural Network

CHONG Kai, KE Xian-xin

2001, 19(1):  44-47. 

Asbtract ( 314 )   PDF (168KB) ( 83 )  

Related Articles | Metrics

For solving the solvability problem within the work space of underfreedom-robot, a virtual joint method is proposed and BP neural network is used to distinguish the solvable and unsolvable posture space and to determine whether there exists an inverse kinematics solution. The result is proved ideal.

A Study on the Optimization Design of the Grinding Wheel Topography for the High Efficiency Grinding

FU Yu-can, XU Hong-jun

2001, 19(1):  48-52. 

Asbtract ( 302 )   PDF (206KB) ( 93 )  

Related Articles | Metrics

In view of the limitation of the traditional thinking in modeling and simulation of the grinding processes, a new idea is put forward. It is the optimization of the topography in accordance with machining demands and grinding parameters and the optimization of grinding parameters in accordance with the topography and machining demands. In this way, not only the study of modeling and simulation can be realized but also the optimization of the processes can be carried out. Furthermore, a superabrasive slotted grinding wheel is designed as a practical application of the optimization model.

The Application of Random Displacement Method in the Static Buckling of Frame Structure

YANG Ji-xin, CHEN Ding-fang

2001, 19(1):  53-56. 

Asbtract ( 284 )   PDF (169KB) ( 75 )  

Related Articles | Metrics

A new mechanical method, random displacement method, was used to analyse static buckling of frame structure. The basic idea was to discrete the structure and find the load function according to the energy criterion of buckling and the principle of random displacement method. As the critical load is the minimum of the load function, a problem of frame buckling can be transformed into an optimization problem. Therefore, the critical load can be found through solving the optimization problem. The feasibility of the method is discussed on the basis of numerical computing instances.

Structural Design for the Elastic Body of a High Performance Six-axis Wrist Force Sensor

LIU Zheng-shi, LU Yi-min, CHEN Xiao-dong, WANG Guo-tai, GE Yun-jian

2001, 19(1):  57-61. 

Asbtract ( 337 )   PDF (209KB) ( 150 )  

Related Articles | Metrics

A model of static and dynamic characteristics of the elastic body of a wrist force sensor used in space robot is built with finite element method. The stress distribution pattern in various load cases, natural frequencies and vibration shapes of the elastic body are analyzed. The influence of main structure parameters on static and dynamic characteristics is investigated comprehensively by using orthogonal test design. The regression equations between the structure parameters and performances of the sensor are obtained by using step regression analysis on numerical results. And the optimization design of elastic body for the wrist force sensor has been carried out.

Tool-path Generation in the NC Machining of Compound Surfaces

CHEN Tao, CHEN Gang, TANG Jin, ZHONG Yi-fang, ZHOU Ji

2001, 19(1):  62-65. 

Asbtract ( 377 )   PDF (176KB) ( 77 )  

Related Articles | Metrics

An algorithm for tool-path generation in the NC machining of compound surfaces is presented:The compound surfaces are approximated by triangular meshes. The vertices of triangular meshes are offset along the normal direction at the vertices. All offset vertices are then connected to form an offset triangular mesh surface which is sliced by a series of vertical planes to obtain parallel tool-paths. The experimental NC machining results demonstrate the feasibility of the algorithm.

Research on Displacement Flow of Internal Moisture in Porous Media During Rapid Drying Process

WANG Xin, WANG Hai, SHI Ming-heng, YU Wei-ping

2001, 19(1):  66-69. 

Asbtract ( 363 )   PDF (176KB) ( 95 )  

Related Articles | Metrics

In this paper, the authors put forward the idea that the displacement flow in capillary structure under pressure gradient is the main mechanism of high intense and rapid drying process. In this paper, both analytical and experimental studies are carried out to clarify the displacement process and its characteristic. A simplified displacement flow model is proposed and the time of the moisture migration is calculated. A one-dimentional displacement flow test device is built up and a set of experiments under different pressure gradients and temperatures are conducted. Glass beads of 0. 8mm diameter are used as the porous material.
The experiment results show that under a constant temperature, as the pressure gradient is getting greater, the time for moisture to reach the external surface from the internal is getting smaller and the range of time reducing is getting smaller too. On the other hand, under the same pressure gradient, as the liquid temperature increases, the time for moisture from the internal to the external surface decreases.

Experiment on the Shrinkable Character of Material During Convective Drying Process

CAI Liang, YU Wei-ping, SHI Ming-heng

2001, 19(1):  70-72. 

Asbtract ( 265 )   PDF (136KB) ( 82 )  

Related Articles | Metrics

Some material, especially biomaterial, will shrink during the drying process. In the experiment, drying curve and shrinkable curve of fresh pea is measured. Volumetric shrinkable coefficient is also introduced and measured.

Models for the Critical Volume Content of the Reinforcement Phase in Ceramic Materials Based on the Toughening Mechanism of Residual Thermal Stress and Their Applications

XU Chong-hai, DING Wen-lia ng, HUANG Chuan-zhen, DENG Jian-xin, AI Xing

2001, 19(1):  73-76. 

Asbtract ( 310 )   PDF (179KB) ( 76 )  

Related Articles | Metrics

Based on the toughening mechanism of residual thermal-stresses, a model is built for the calculation of the critical volume content of the reinforcement phase in ceramic materials when T_P> T_m. The model has been proved valid through its applications in SiC/TiB₂ ceramic material. Next, two models are established for the determination of the critical volume content of the reinforcement phase when the particle size of the matrix and the ratio of the particle size of the reinforcement phase and the matrix are considered. Models built here will find a practically application in the composition designing and the micro-structural designing of ceramic materials.

A Study on Ni₃Al(Cr)-base in-situ Composite Microcrystalline Alloy

LIN Yi-jian

2001, 19(1):  77-80. 

Asbtract ( 313 )   PDF (179KB) ( 74 )  

Related Articles | Metrics

It was proposed that fabricating intermetallics with the rapid-solidification technique for micro-crystalline alloys would be a promising way to develop high-performance materials. A Ni₃Al(Cr) base micro-crystalline alloy, strengthened and stabilized by M₃B₂ boride particles, was designed and prepared. The alloy has a uniform sub-micron-scale refined micro-structure, which is stable without coarsening even after 1000℃ anneal when subjected to high temperature. It retains a high hardness of HV≈580 from room temperature up to at least 650℃, which is related to the characteristic high temperature strength of Ni₃Al phase and the strengthening effect of M₃B₂ particles.

Research of Numerical Prediction in the Course of the Hyperthermia Treatment of Tumor

HUANG Zhen-kan, GENG Mei-ying, LI Qin-fu

2001, 19(1):  81-84. 

Asbtract ( 301 )   PDF (175KB) ( 75 )  

Related Articles | Metrics

Time series prediction approach is utilized in this paper to predict and analyze the law governing the change of temperature somewhere inside the tumor. The radial power and the marginal temperature of the interface between the probe and the tumor are modified, and the temperature of the body of tumor is controlled according to the result of the prediction in order to achieve the desired curative effect.

A Characterization of Two-heat-source Refrigerators

YANG Hui-shan, YAN Zi-jun

2001, 19(1):  85-88. 

Asbtract ( 343 )   PDF (161KB) ( 72 )  

Related Articles | Metrics

By using finite-time thermodynamic theory, unified description a characterization is made of a class of two-heat-source refrigerators using an ideal gas as working fluid is achieved. The fundamental optimal relation of the refrigerators is derived, and the effect of regenerative loss and regenerative time on the cooling rate and coefficient of performance is discussed. The results obtained here have general significance. They may provide some new theoretical guidance for the manufacture and the optimal design of a class of two-heat-source refrigerators, such as Carnot refrigerators, Stirling refrigerators, Ericsson refrigerators, and so on.

Research Notes

Analysis of the Stabilizability of Two Stabilizers for Plants

YUAN Xiang-yang, SHI Song-jiao, IKEDA Masao

2001, 19(1):  89-91. 

Asbtract ( 389 )   PDF (133KB) ( 65 )  

Related Articles | Metrics

For a linear SISO plant with variable operating condition, whose dynamics is described by a linear interpolation of proper stable coprime factorizations of the transfer functions at two representative operating points, a fixed stabilizer is proposed in[1,2]while an interpolated stabilizer is proposed in[3]. It is demonstrated in this paper that the class of stabilizable plants via the stabilizer proposed in[3]is larger than that via the fixed controllers proposed in[1,2].

A Study on the Bubbling of the Anti-stickiness Coating on ZL102 Casting Al Alloy for Cooking Utensils

HUANG Xu-qiang, LU Chao-yang

2001, 19(1):  92-94. 

Asbtract ( 440 )   PDF (159KB) ( 79 )  

Related Articles | Metrics

The cause of the bubbling of anti stickiness coating on ZL102 casting Al alloy cooking utensils is discussed. By metalloscope and electronic probe, it is found that the bubbling may result from the impurities which remain in the flaws (such as bubbles loose structures etc.) if refiring and modification are inadequate, when cooking utensils are used at high temperature a pressure leading to the formation of bubbles will be produced with the impurities diffusing from inside to the surface.