Table of Content

20 January 2005, Volume 41 Issue 1

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Linear Estimation of the Number of Zeros of Abelian Integrals for Cubic Isochronous Centers

LIANG Shuang

2005, 41(1):  1-11. 

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It is studied that the number of limit cycles that bifurcate from the periodic orbit of cubic isorhronous centers, formed by conics, when perturbing such systems inside the class of all polynomial systems of degree n.

The Application of Strong Bands Decomposition

YU Jianping,SUN Yongli,LI Shizheng

2005, 41(1):  12-14. 

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On the defination of strong bands, the structures of some normal bands are mainly discussed.

On Sylow Intersection Conjugacy Classes

WANG Baoshan

2005, 41(1):  21-26. 

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Suppose that G is a finite group and p is a prime such that p||G|. This paper studies the group invariant n_p(G), the number of G-orbits of Sylow intersections, which plays an important role in the research of block theory and indecomposable modules of finite groups. The paper shows some properties for finite groups with n_p(G)=2, in particular, it gives some necessary and sufficient conditions which show when a finite group G with n_p(G)=2 has the unique maximal normal p-subgroup as an intersection of two distinct Sylow p-subgroups.

A Note on Almost Perfect Arrays

CAO Xiwang,ZHU Yiquan,TANG Cui'e

2005, 41(1):  15-20. 

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The conception "almost perfect arrays" is proposed and it is shown that the existence of an almost perfect binary array is equivalent to the existence of a certain divisible difference set. Some methods of constructing perfect arrays are provided. In addition, three conjectures on the existence of perfect arrays are also presented.

Construction and Enumeration for Periodic Quasi-Perfect Sequences and Multiplier Groups of Cyclic Hadamard Difference Sets of Type(II)

QIU Weisheng,CAI Kai

2005, 41(1):  27-35. 

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Periodic quasi-perfect sequences are very important in CDMA mobile communication and in stream ciphers. The relation between periodic quasi-perfect sequences and cyclic Hadamard difference sets of type (Ⅱ) is studied, the enumerating formula for periodic quasi-perfect sequences is given,the multiplier groups of some cyclic Hadamard difference sets of type (Ⅱ) are determined, and the numbers of some periodic quasiperfect sequences corresponding to cyclic Hadamard difference sets of type (Ⅱ) are obtained.

The Spectral Transformation of CMC Surfaces in S³

ZANG Yingyun,CHEN Weihuan

2005, 41(1):  36-46. 

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It is studied that the CMC surfaces in the sphere space of dimension 3 by means of integrable system and its spectral transformation is given.

The Riemann-Hilbert Problem for Linear Degenerate Elliptic Complex Equations of First Order

WEN Guochun

2005, 41(1):  47-54. 

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The Riemann-Hilbert problem for first order linear elliptic complex equation with parabolic degeneracy is dealed with here. Firstly, the formulation and representation of solutions of the above boundary value problem are given, and then the existence and uniqueness of solutions for the above problem are proved, in which the complex analytic method is used.

Solving Wave Propagation along Axis Direction in Piezoelectric Hollow Cylinder by Integral Average Method

WEI Jianping,SU Xianyue

2005, 41(1):  76-81. 

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The wave propagation along axis direction in piezoelectric hollow cylinder is studied. Using integral average method, the author derives a group of differential equations, which are about displacements and electric potential. It shows that when wave propagates along axis direction, the displacements of radial, axis direction and the change of electric field are coupling each other, and there is dispersing phenomenon, and the displacement of circle direction can figure out independently, it has not dispersing phenomenon. At last the instantaneous responses under a stress pulse at the end are simulated numerically. The effect of the radius'ratios of the hollow cylinder to the wave propagation is also discussed.

A New Compact Pipeline Leak Detection and Location Monitoring System with the GPRS Wireless Communication Technology

SHI Ketian,SUN Zhili,YAN Dachun,LI Hongmei,YE Zongmei,SHANG Jiaoqing,FU Hongli,SONG Xuefeng

2005, 41(1):  82-85. 

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A new pipeline leak detection and location monitoring system is introduced. Some digital technology are applied to this system, such as pocket PC data processing system and GPRS wireless communication system. The monitoring system has the advantage of compactness, easiness of installing and fast speed of communication. The pipeline leak detection and location monitoring system can be widely applied to water pipeline, oil pipeline and gas pipeline.

Influences of Structures on Urban Ventilation: A Numerical Experiment

JIANG Yujun,SANG Jianguo,LIU Huizhi,ZHANG Boyin

2005, 41(1):  86-92. 

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The disturbed flow caused by three six-storied residential buildings and a twenty-storied tall tower, respectively, as well as the distribution of traffic tail gas from a nearby road, are simulated by using an urban climate model. The results show that with the same built areas the ventilation ability of the atmospheric environment around the tall tower is better than that around the multi-storied buildings.

Kinetic Energy Buget of Typhoon During Extratropical Transition

ZHU Peijun,ZHENG Yongguang,TAO Zuyu

2005, 41(1):  93-103. 

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Typhoon Winnie (1997) was studied by kinetic energy budget during its transformation and reintensification. The time evalution of kinetic energy about divergent wind in lower troposphere corresponds well to that of cyclone center pressure. The generation of kinetic energy by divergent wind is the primary fact or to the change of cyclone intensity. In transforming stage the intruding of cold air intensifies convergence in lower level, which makes for kinetic energy generation and favors to cyclone maintaining. In reintensifying stage the effect of upper jet increases kinetic energy generation by divergent wind in lower level, which causes baroclinic developing in cyclone. At last the type of cyclone reintensification was discussed. It is a compound process of type A and type B extratropical cyclone, so it is an interaction process between transformed cyclone in lower level and trough in upper level.

Research on Noise Compensation for Text-Independent Speaker Identification

QIU Hong,WU Shuzhen

2005, 41(1):  115-121. 

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When background noise exists in the testing environment, the performance of most current speaker Identification Systems is seriously affected because the noise leads a mismatch between the training environment and the testing environment. In order to improve the identification rate, this paper studies a kind of method that makes the compensated VQ codebooks approach the codebooks trained in the testing environment by compensating the codebooks in the linear spectral domain. The experiments in the conditions with different SNRs have been done to compare compensation method with common one. The result shows the noise compensation method can improve the identification rate a lot .

Comparison of Characteristics of Ozone Vertical Distribution above Lin'an, Kunming, and Hong Kong during Spring 2001

ZHENG Yongguang,CHEN Luyan,CHEN Zunyu,CUI Hong,ZHENG Xiangdong,QIN Yu

2005, 41(1):  104-114. 

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The ozone experiment at three sities (LinAn, KunMing and Hong Kong) was simultaneously conducted for the first time in China during March-April 2001. Based on the ozone data obtained by this experiment and the ozone sounding data of Hong Kong from 1994 to 2000, we analyzed and compared the characteristics of ozone vertical distribution above these three sites. The results show that there exist different and general characteristics among the three sites ozone vertical distributions. The main difference of the three sites ozone vertical distributions is as follows: both the maximum ozone partial pressure and its altitude are different; the ozone concentration at 10～16km height of Lin'an is much higher than that of Kunming and Hong Kong; there exists one high ozone concentration layer over the Hong Kong and Kunming, but Hong Kong is more obvious; in the upper troposphere there is no lower ozone distribution over Lin'an. Based on the NCEP analyzed data, the atmospheric circulations of March 2001 reveals that the different atmospheric circulations can lead to the different ozone vertical distribution above these three sites.

Gene Selection Based on Fast Fisher Optimization Model

FENG Jufu,SHI Jianxin

2005, 41(1):  122-128. 

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Gene selection is a very important problem in microarray data analysis and has critical implications for the discovery of genes related to serious diseases. A fast algorithm based on Fisher Optimization Model (FOM) for gene selection was proposed. The computational complexity of the algorithm relies on the number of the samples not the huge number of genes. Experiments in public data demonstrated the proposed algorithm is effective and efficient.

The Influence of Assembling Methods on the Field Emission Properties of Carbon Nanotubes

CHEN Changqi,CHEN Xianxiang,ZHENG Wenfeng

2005, 41(1):  129-133. 

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Carbon nanotubes(CNTs) need to be either directly grown or assembled on a conducting substrate for the measurement of their field emission properties. CNTs was assembled onto tungsten tips using the physical method and the chemical method, respectively. The influence of the two methods on the field emission properties was also studied.

An Overview of Study on Atmospheric Environment in Urban Street Canyons

WANG Baomin,KE Yongdong,SANG Jianguo

2005, 41(1):  146-153. 

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High pollution levels often occurred in urban street canyon due to the increased traffic emissions and reduced natural ventilation. The main methods for studying the atmospheric environment in street canyons include field observations, reducedscale physical models and mathematical models. Field observations and physical models may be used to investigate pollutant transportation and dispersion within urban canyons and validate numerical models. On the other hand, validated numerical models are often applied to simulate in detail atmospheric dispersion within the urban canopy. The numerical results in combination with physical model and/or field data may be used to assess urban air quality and support decisionmaking for pollution control strategies and traffic planning. This article provides an overview of studying on atmospheric environment within street canyons in the latest decades.

Research Progress in Software Testing

SHAN Jinhui,JIANG Ying,SUN Ping

2005, 41(1):  134-145. 

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Software testing is one of the most important techniques used to assure the quality of software products. Software testing keeps a high proportion during the whole software life cycle. Gradually, software testing develops towards the former phase of software development and inosculates with the design and coding phases of software development. This paper introduces the basic ideas of software testing from the techniques and the process of software testing, persistent software testing, adequate criteria of software testing and so on. Then, this paper discusses some problems in software testing, including automated path-wise test data generation, test oracle, automated expected results generation, regression testing and so on. At last, this paper explores the development tendency of software testing, such as component testing, software testability, design by contract for testability in components and Web Services testing.

A Review of Study on Relation Between Well Logging Data and Seismic Attributes

LU Baokun,SHI Ge

2005, 41(1):  154-160. 

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The well logging data and seismic data are two most important data in the seismic prospecting. There are three important methods to study the relation between the well logging data and seismic attributes. Because the synthetic seismic record and the seismic record data got in the surface are not well matching caused by the dispersion of seismic wave, frequent correction between them must be done before use. Under control of well logging data, there are two important methods to get wave impedance from seismic data inversion: wave impedance inversion method based on convolution model and wave impedance inversion method based on wave equation. Using seismic data attributes can predict the information of logs.

Abel Transform of Equilibrium Equation of Axisymmetric Problem

GAO Yang,WANG Minzhong

2005, 41(1):  62-65. 

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The equilibrium equation of irrotational axisymmetric problem is converted into equilibrium equation of plane strain problem by using Abel transform directly rather than Алексадаров complex formula, thus it is proved that any axisymmetric problem is derived from plane problem by rotating.

About the General Solution of Elasticity Equations in Respect of Stresses

XU Baixiang,WANG Minzhong

2005, 41(1):  66-69. 

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A new method is introduced to derive the general solution of elasticity equations in terms of stresses. Different from Bлох, the general solution is obtained by substituting the general solution of stress compatibility equations into equilibrium equations. This solution is identical with Bлох's.

An Experimental Investigation on the Effect of Single Two Dimensional Roughness Elements on Boundary Layer Transition

LI Yiming,YAN Dachun

2005, 41(1):  70-75. 

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An experimental investigation on the transition in the boundary layer of horizontal plane with and without single two-dimensional roughness elements has been carried out in the wind tunnel. The distribution in normal and stream-wise directions of intensity of T-S wave excited by vibrating beam was measured in every condition. Neutral curves were obtained by measuring the growth of the T-S wave at the normal critical location along the stream-wise direction. Comparing with the neutral cave on the smooth plane that was thumb-like and opened at the bottom, the neutral caves on the plane with single roughness elements were closed circles. With the growing of roughness element's height, the closed circle became smaller.

Necessary and Sufficient Conditions for the Existence of a Positive Definite Solution of the Matrix Equation X + A ^* X^-2 A = I

CHENG Mingsong

2005, 41(1):  55-61. 

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The matrix equation X + A ^* X^-2 A = I is studied. Some necessary and sufficient conditions for the existence of a positive definite solution of this equation are derived. Based on them, some properties of the coefficient matrix A are presented when the matrix equation has a positive definite solution.