Table of Content

20 July 2003, Volume 31 Issue 7

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Modeling Approach and Performance Analysis of Quasi-resonant Converter



Zhao Hongru Wu Jie

2003, 31(7):  1-5. 

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The operation principle of zero-current-switching quasi-resonant boost converter is presented and its nonlinear model is built up using simple analytical techniques based on topological circuit. The relationship between voltage conversion ratio and switching frequency is obtained and analyzed under different load. Simulation results show that the full-wave pulse frequency modulation should be adopted in order to get the required output voltage under different load and different input voltage. The output voltage under step input is also simulated and analyzed. The model is easily implemented by MATLAB, simulation results have shown its accuracy for large-signal transient response.

Influence of Slow Dynamcs on Mid -long Tem Instability Mechanss of Power Systems



Lei Wen Liu Yong-qiang Wu Jie

2003, 31(7):  6-9. 

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Using singular perturbation model,by the example of a simple power system losing stability in big disturbance, this paper analyses the mid-long term instability mechanisms affected by slow dynamics. It points out that fixing slow dynamics randomly in building model may cause incorrect estimation of mid-long term stability. These results are both theoretically and practically significant in the study of mid-long term stability of power system.

Enterprise Information Portal Based on Data Warehouse for Medicine Trade

Tang Dongping Wang Xiaoyu

2003, 31(7):  10-14,18. 

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To solve the problems of medicine trade enterprise' s information construction, and eliminate ' isolated island' of information, this paper designed a structure of medicine trade EIP (Enterprise Information Portal) system, and established a data warehouse-based fundamental model of medicine trade EIP. In this paper, XML is used to mine heterogeneous data, and the medicine trade EIP system is realized by designing the medicine trade decision tree and the clustering algorithm.

An Improved SVM Algorithm and Its Application in the Securities Business

Chen You Zhang Guoji Guo Guoxiong

2003, 31(7):  15-18. 

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On the basis of the traditional support vector machine (SVM) algorithm principle, this paper proposed a new kind of SVM algorithm base on the continuous and procedure algorithm. Compared with the traditional algorithm, it is no longer limited at the only two values, and is a new algorithm of dynamical selection for support vector. This algorithm is applied to the field of securities, result shows that the algorithm is effective and correct.

Similarity in Examination and Approval Assistant System in Urban Planning Field

Zhang Guoji Lin Hao Qiu Yongcan

2003, 31(7):  19-21,51. 

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Urban planning examination is hard to be quantitated. It is influenced by many political and economic factors. Therefore, it is the focus of the urban planning. We attempt to apply CBR technology to the examination and approval to make the current gist of examination in accordance with the history. The design of similarity is the key to implement CBR. In this paper, we designed a feasible scheme taking into account the characteristic of urban planning examination and approval. The scheme has been applied in an office system.

Compact Sinusoidal Representations of Audio for Scalable Compression and Time/Pitch-Scale Modifications

Al-MoussawyRaed Yi Junxun Song Shaopeng

2003, 31(7):  22-27. 

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This paper presents a signal model for scalable perceptual audio coding consisting of Sines + Noise (SN) representations. The paper essentially presents a fundamental enhancement to the sinusoidal modeling component. The enhancement involves an audio signal scheme based on carrying out overlap-add sinusoidal modeling at three successive time scales, large, medium, and small. The sinusoidal modeling is done in an analysis-by-synthesis overlap-add manner across the three scales by using a psychoacoustically based matching pursuits. The sinusoidal modeling residual at the first scale is passed to a couple of smaller scales to allow for modeling of various signal features at appropriate resolutions. This approach greatly helps to correct the pre-echo inherent in the sinusoidal model. The new scheme gives an improved perceptual audio quality compared to our previous work while using the same number of sinusoids.

Realization of DVCC Using Op-amps and Its Applications in Realizing Precision Rectifier

Liang Rongxin Qiu Shuisheng

2003, 31(7):  28-32. 

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A novel realization scheme of differential voltage current conveyor (DVCC) using op-amps is proposed and the DVCC is applied to realizing precision linear rectifier circuits with amplification functions. The proposed rectifier circuits are suitable for small signal measurement and processing. Computer simulation and experimental results have confirmed the proposed novel circuits.

Influence of Hot-Carrier-Effect on Reliability of n-MOSFETs

Zhu Weiling Huang Meiqian Zhang Xiaowen

2003, 31(7):  33-36. 

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Influence of hot-carrier-effect on degradation characteristics of different channel length n-MOSFETs have been investigated. As the channel length of device decreases, the rate of transconductance degradation is fast, especially when its channel length is less than 1 um, the rate of transconductance degradation is faster. These results can be explained by interface state density increased after hot carrier injection.

Thermodynamic Analysis of Earth Cooling System Combined with Adsorption Dehumidifier for Air Conditioning

2003, 31(7):  37-41. 

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An independent earth cooling system worked well for space cooling in summer mainly using renewable ground heat sink in some outdoor air conditions. But for hot climates, earth cooling air may not meet comfortable air conditioning standard. Thus a new air conditioning system, i. e. , earth cooling system combined with adsorption dehumidifier was presented in this paper. An adsorption dehumidifier was coupled before earth cooling system to dehumidify air beforehand. Thermodynamic analysis was also made for comparison of the performance of the systems with or without adsorption dehumidifier on different outdoor air conditions. Results show that the performance and reliability of the earth cooling combined system with adsorption dehumidifier are greatly improved as compared with the independent earth cooling system.

A Numerical Analysis of Thermal Characteristics of Fully- developed Turbulent Flow with the Field Synergy Theory

2003, 31(7):  42-47. 

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The angle θbetween dimensionless time-averaged temperature gradient and velocity vector is one of the main factors to dominate the heat transfer ability of fully-turbulent flow. Numerical investigations are carried out to examine the angle in a 2-D flow passage of two kinds of tubes, transversely corrugated and convergent-divergent tube. The calculated results indicate that the variations of T / cos θ are similar to the local Nusselt number along the stream-wise direction while Reynolds number is constant. The geometrical parameters, for example, rib height or converging length can change the angleθ

Medium Optimization for Oil Degradation by Genetic Algorithm

2003, 31(7):  48-51. 

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Analysis of Seismic In fluence Coefficient of Structres with Active Variable Stiffness Systes#br#

LIUFenTao WEIDeMing WUBo

2003, 31(7):  52-57. 

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Seismic influence coefficients of structures with active variable stiffness (AVS) systems, corresponding to two different control laws, are compared and analyzed. Results show that the effect of control laws on the mean value and the standard deviation of the seismic influence coefficient ratios, corresponding to each mode of a controlled structure, is limited. With an increase in the modal additional stiffness ratio, the mean value and the standard deviation of the seismic influence coefficient ratio tend to

increase. Based on the simulation results, the determining method of the seismic influence coefficient ratio for controlled structures is proposed. Some suggestions on aseismic design of structures with AVS systems are also presented.

On Some Functional Equations Conneted with Polynomials on Abelian Groups (I)

Luan Chang-fu, Zhong Ju-kang

2003, 31(7):  58-69. 

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This paper derived the general solutions of the functional equations f3(x1 + x2 + x3) - [f21(x1 x2) +f22(x1 + x3) + /f23(x2 +x3)] +f11(x1) +f12(x2) +f13(x3) = and f(x1+ x2+...+xn)- =0 on abelian groups.

Properties of Photochemical Vapor Deposition Silicon Dioxide Thin-film Studied by IR and XPS

Liu Yu-rong, Li Guan-qi

2003, 31(7):  61-64. 

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The direct photo-CVD SiO2 thin films were deposited successfully on silicon substrate at low temperature by using the SiH4 and O2 as the reaction gas and the low pressure Xe excited vacuum ultra-violet (VUV) as the photon source. The infrared absorption peaks related to the Si-H and Si-OH bonding do not appear in the FTIR spectrum of films, the absorption peaks related to the Si-O stretching vibration are in the range of 1 055 -1 069 cm-1. The fixed oxide charge density is in the range of 2×1010 ~3×1011 cm -2 by capacitance-voltage ( C-V) characteristics measurements. XPS analysis results show Si(2p) binding energy of the SiO2 film is 103.6 eV, the total amount of Silico-suboxide is 3. 72×1015 cm-2 at the SiO2/Si interface.

Research on the Contemporary Lingnan Architecture Creation

He Jing—tang, Wang Yang

2003, 31(7):  65-69. 

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Based on the analysis of works on contemporary Lingnan architecture creation, this paper discusses the relation between inheritance and innovation, and then concludes that modern architectural creation should display regional characteristics, cultural characteristics and epochal character.

Meaning of Architectural Elements

Deng Tao

2003, 31(7):  70-73. 

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To study the originality of architectural works, with the aim of providing supports on organizations of formal significance and reception theory of formal significance, this paper explores and analyzes the methods of identifying architecture, the relation between the nature of architectural elements and architecture itself, and the organizational ways of formal significance from the cognitive point of view. It categories the architectural elements, characterizes the five basic features of architectural elements, elaborates the relation between these elements and architectural spatial functions and spiritual connotations. Based on the subjects' psychological response to the formal significance, the paper puts forward three enlightening organizational ways of formal significance. It contends that the proper way of controlling architectural elements is to characterize architectural elements. Whether formal, or material, the tendency of architectural elements ought to be purposeful and meaningful.

Some Applications of Markov Chain in the Analysis of Stock Market

Zhang Yu—shan, Liao Qin

2003, 31(7):  74-77. 

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To apply the theory of Markov chain to establishing mathematical model of stock price' s fluctuation and anticipation, the theory of the cycle of stock's motion and maximization of investment' s gain is proposed. Examples proves that this model and its application are feasible.

Factors Affecting the Protoplast Formation of Phaffia Rhodozyma

Tian Xiaoqun, Zhu Ming-yun, Liang Shi

2003, 31(7):  78-81. 

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To study factors affecting the protoplast formation of Phaffia rhodozyma with PEG. Culture time,culture temperature, generation times, medium volume, enzyme concentration, property of osmotic stabilizer, pH, temperature and time of enzyme action,all of which affect the formation of protoplast greatly. The optimum conditions of protoplast formation are as follows; 0 ~2 generations cultivating at 15 or 25℃ for 12 ~ 16 h, medium volume 100 mL, osmotic stabilizer 0. 8 mol/L KCl, enzyme concentration 1% ; temperature ,time and pH for enzyme action are 22℃,16 h and 8.0 respectively.

Preparation and Application of Starch Ester Octenylsuccinate

Luo Fa—xing, Huang Qiang, Yang Yuan-er

2003, 31(7):  82-85. 

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To study the preparation and techniques of serials of DE value products of starch ester octenylsucci-nate. It explores the product' s application in micro encapsulation. In this experiment, lemon oil was used as core material and the starch ester octenylsuccinate as wall material. The results show that optimum processing conditions for microencapsulation are:the mass ratio of wall material to core material is 3:2; the best DE value of starch ester octenylsuccinate is 12. The final product' s microencapsulation productivity and efficiency are close to 100% .

Soluble Trace Metals in Rainwater in Singapore

Hu Gui Ping

2003, 31(7):  86-90. 

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The mass concentrations of trace metals in rainwater in Singapore under a variety of meteorological conditions from January to December 2000 have been monitored in this study. It is found that the mean mass concentrations varied from month to month due to changes in emission intensity and meteorological conditions. The origins of the trace metals in rainwater in Singapore come not only from natural soil/dust but also from anthropogenic sources significantly through comparison with the data from other sites in the world. Some calculation show that fine particulates with insoluble trace metal are scavenged more efficiently in the Singapore atmosphere by more acidic rainwater.

Robust Control for a Class of Linear Uncertain Systems with Multiple Delays#br#

Peng Da, Xu Bu -gong

2003, 31(7):  91-94. 

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The regional robust control for a class of linear uncertain systems with multiple unknown constant delays is studied by using frecency domain techniques in this paper. The stabilization conditions such as that all poles of the closed-loop system under consideration lie in a certain symmetric region in the left-hand side of the complex plane are established. The result only depends on the upper bounds of delays and uncertain parameters, and is presented in the form of linear matrix inequalities (LMIs) so that it is easy to be calculated numerically. An example is also given to illustrate the proposed method.

Chinese Speech Information Coding for a Low-bit-rate Transmission Technique

2003, 31(7):  95-97. 

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To study a technique on Chinese speech information coding. The low-bit-rate coding technique can double the speech processing with wavelet analysis and recognition, and information coding with speech characteristics, which include wavelet package disassembling, speech phoneme and syllable note recognizing, accent character fetching, speech information and character parameter integrated coding.