Table of Content

10 December 2003, Volume 21 Issue 4

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Articles

The RCS Analysis and Synthesis of the Elementary Scatterers

SHI Zhen dong, TANG Pu, LIU Hong wei, HU Yan

2003, 21(4):  331-333. 

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A general expression for the radar cross section(RCS) of an arbitrarily simple shaped scatterer is synthesized after analyzing the scattering characteristics of the simple shaped scatterers. This is a theoretical basis not only for the deduction of RCS values in the model measurement of the complex scatterer under the non ideal scaling conditions and the extrapolation of RCS frequency characteristic curve of the complex scatterer, but also for identifying radar targets through RCS frequency characteristics.

A Novel Method for Designing Dual-Frequency Slot Patch Antennas with Two Polarizations

WU Di, OHISHIBASHI Hidekazu, SEO Kazuyuki, INAGAKI Naoki

2003, 21(4):  334-338. 

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This paper presents a new method for designing a dual frequency patch antenna with circular and linear polarizations. Dual frequency operations are behaved by etching two narrow slots close to the radiating edges of a rectangular patch. The circular polarization at the lower resonant frequency of the dual frequency antenna can be achieved by setting a perturbation segment at an appropriate location in the patch element, and placing the feed point on the diagonal axis. Several experimental results of a designed antenna show the good characteristics for circular and linear polarizations at both resonant frequencies.

A Passenger Train Information Monitoring System Employing SSC-DPIM Power Line Communication Technique

JIANG Xiao-hua, ZHANG Zhan-mei

2003, 21(4):  339-343. 

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Train power lines provide a readily available and easily accessible network for measurement and control of unit communications within trains. The communication characteristics of passenger train power line channels are analyzed and found to suffer from highly variable, changing, and unpredictable signal to noise ratios. Power line transceivers usually operate in environments containing both background and strong impulse noise. To reduce the effects of the power noise and interference, a power line spread spectrum carrier communication system using digital pulse interval modulation (SSC DPIM) is proposed. In the system, a swept frequency spread spectrum carrier is used to generate pulses of the DPIM. A mathematical model to describe the signaling and the data transmission rate of the SSC DPIM system is given. The error ratio performance of the SSC DPIM system is compared with that of the established techniques of power line communications using both theoretical analysis and experimental results. The SSC DPIM transceiver is implemented by a micro processor and used successfully in a train fault monitoring system based on power line communications. In the monitoring system, the running parameters of trains such as axle temperature, miles operated, power load, sensor states and so on, are measured on the spot and transmitted into a train signal monitoring center simultaneously by power line channels.

A Novel Beamforming Algorithm in CDMA

FU Yong-sheng, SHEN Lian-feng

2003, 21(4):  344-348. 

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A novel method for beamforming is proposed in a CDMA mobile communication environment and a beamformer rake receiver is formed on this basis. The method based on maximum signal to interference and noise ratio (MSINR) criteria converts the conventional two steps pro blem of seeking the invertion of matrix after knowing the signature vector to computing the largest generalized eigenvector directly. The main advantages of the new technique are that the computation load is reduced, the storage memory is compressed and the training signals and reference signal are not necessary in the procedure. Compared with the code filter algorithm, it is superior to the pilot aided method and its computation load is lower than that of the code filter method. It will be applied in the beamforming of fast fading environment in the third generation mobile communi cation. Back

Capacity Analysis of CDMA System with Different Combining Schemes Under Multipath Fading Channels

FANG Xin, GAO Xi-qi, YOU Xiao-hu, Woogoo Park

2003, 21(4):  349-352. 

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In this paper, the capacity region of downlink DS CDMA system under frequency selective fading channels is derived. Closed form solution of the optimum resource allocation schemes for multi user is obtained assuming that the channel information is known by both transmitter and receiver. The equation shows that a nonuniform service distribution, which is obtained by allocating more resource to a better channel quality, leads to a higher capacity. Numerical results show that the capacity of CDMA system changes with different diversity combining schemes and different priorities. MRC has the best system capacity.

A Study on the Chinese Continuous Speech Recognition Unsupervised Speaker Adaptation Based on Maximum a Posteriori Algorithm

ZHAO Li, ZOU Cai-rong, WU Zhen-yang

2003, 21(4):  353-356. 

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Aiming at Chinese continuous speech recognition, a novel unsupervised speaker adaptation method based on maximum a posteriori algorithm is presented in this paper, together with a simple effective formula which can give a satisfying result with only a few data. It has been proved to be an effective method to apply.

A Web Site Navigation Based on Ant Colony Algorithm

YE Ning, LIANG Zuo-peng, DONG Yi-sheng

2003, 21(4):  357-361. 

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A web site navigation algorithm based on the ant colony algorithm is proposed in this paper, First the algorithm is trained against the previous web log. As a result, a directed graph is obtained with each vertex containing a set of users' navigation rules and each edge containing the linking probability between adjacent pages. Next we forecast users' navigation according to the directed graph. Finally, the recommended pages based on the predicted navigation can be obtained. The experiment result was satisfactory.

Horizontally Partitioning the Data Warehouse Views Based on OLAP Queries

HU Kong-fa, DONG Yi-sheng, XU Li-zhen, ZHAO Qing-jian

2003, 21(4):  362-366. 

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OLAP querying is a complex process and the volume of data involved is so large that query response time has become an important warehousing issue. We can select data warehouse views to parttion horizontally in an efficient manner so that OLAP queries will scan fewer fragments and in turn scan fewer rows in the original view. Based on the minterm predicates of OLAP queries, the paper proposes a method for selecting and efficient horizontal partitioning of warehouse cube views in order to improve the efficiency of the OLAP queries.

Fast Incremental Updating of Frequent Itemsets

YANG Ming, SUN Zhi-hui, SONG Yu-qing, CHEN Geng

2003, 21(4):  367-372. 

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Mining frequent itemsets is a major problem in the data mining field with numerous practical appilcations. Efficient incremental updating of discovered frequent itemsets is the key problem. The existing incremental updating algorithms employ the same framework as Apriori, which need to generate a lots of candidate sets and repeatedly scan the database, especially when there exist many patterns and/or long patterns. In this paper, we propose an incremental updating algorithm of frequent itemsets (FIUA) mainly for the updating of frequent itemsets as a time when the minimum support threshold adjusts dynamically. In worst case, FIUA only scans transaction database once and need not generate candidate sets, which saves effectively storage space. Therefore, FIUA is efficient and effective.

The Fuzzy Association Rule and Mining Algorithm

LIU Yao-he, HU Bao-qing

2003, 21(4):  373-376. 

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This paper elucidates the relationship between the data of transaction through defining the fuzzy transaction database with the fuzzy concept. It proposes and defines the concept of fuzzy association rules. It also investigates into the nature of fuzzy association and gives a new mining algorithm on the basis of the fuzzy association rules.

An Analysis of the Technique and Economics of the Geothermal-Source Heat Pump Air-Conditioning System

XU Yu-dang, LEI Fei, WANG Fan

2003, 21(4):  377-380. 

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The low temperature of the geothermal water about 10℃ can be promoted to 45℃~60℃ by the heat pump technique. The application of geothermal heat pump technique is a new method of using the energy of low enthalpy. The technical economics of the geothermal heat pump system and the beneficial effects on energy saving and environmental protection are analy sed. It is found that the geothermal heat pump technique is an economical system engineering with low pollution and a good future.

A Similarity Solution to the Momentum and Heat Transfer of the Developing Section of the Non-Newtonian Environmental Falling Liquid Film

SUN Fu-tao, LIU Zhi-jun, LIU Feng-xia, SHI Qi-cai

2003, 21(4):  381-384. 

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A mathematical model based on the momentum and heat transfer in the gravity driven falling liquid film of non Newtonian environmental flow is established. Similarity theory is applied to transform the problem into one of the similarity between boundary layers by introducing appropriate similarity transform. Shooting method is applied to get numerical results which are analyzed with the developing section of the falling film.

A Study on Using the SPW Sensor to Detect Temperature

CAO Zhen-xin, WU Le-nan, LIANG Da-kai

2003, 21(4):  385-387. 

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The working principle of the optic fiber surface plasmon wave (SPW) sensor is based on the resonance of the surface plasmon. A layer of the electronic gas exits on the surface of the sensor. When the environment temperature rises, the density of the electronic gas will increase and the kinetic energy of electronic gas will become stronger. Finally, the resonant frequency of the electronic agglomerate will change. The relationship between the resonant wavelength and the environment temperature is found through experiments and the error is analyzed. the application of the optic fiber SPW sensor is thus broadened.

An Elimination-Reduction Algorithm for Airflow Pressure Pulsation in Multi-Degree-of-Freedom Piping System

LÜ Lin-tao, ZHANG Jing, LI Jun-huai, ZHANG Fa-cun, LÜ Hui

2003, 21(4):  388-392. 

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In order to avoid resonance in the airflow pulsation of multi degree of freedom piping system, a mesh geometric model and a mesh elimination reduction algorithm for airflow pressure pulsation fluctuation is proposed based on the theories of wavelet analysis, of applied mathematics, of fluid mechanics and of solid mechanics. The software system based on this algorithm is being applied in the fluctuation analysis of piping systems, it is found that its calculation data coincide with the experimental results very well. Therefore, it has both theoretical and practical values in designing the new piping system or rebuilding the old piping system in petroleum, chemical and electric power industries.

An Analysis of the Process of Axial Vibration Drilling and Chip Length

ZHANG Ping-kuan, WANG Hui-lin, WANG Gui-cheng

2003, 21(4):  393-396. 

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The theory of axial vibration drilling is systematically analyzed. The relation of each parameter and its effect on the machining process is discussed. The conditions of broken chip and the method of calculating chip length are given. The actual result is always smaller then the theoretical value in every cutting condition, but the difference is small. This lays down a theoretical foundation for quick selection of right axial vibration drilling parameters and successful automatic machining of deep holes.

A Study on the Mix Design of Frame Structures Based on Controllability/Robustness

ZHOU Xing-de, CHEN Guo-rong

2003, 21(4):  397-400. 

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In order to acquire the biggest controllability and the best robustness for active vibration control of frame structures, a mix design which combine structural design with controller design is considered. Original structures are redesigned to get a better control involved. Considering the complexity of the calculation in the mix design and the amount of work during the optimization of the structures, a mended genetic algorithm is used to search for optimal designs results. Finally, a numerical example is provided to show the effectiveness of the method.

A Quantitative Prediction Method for Controlling the Maintenance Cost of Civil Aviation Aircraft Engines

SUN You-chao, ZUO Hong-fu, WANG Wei

2003, 21(4):  401-405. 

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Most Chinese airlines are operating at high costs and small profits. Their flying and maintenance costs are much higher than those of foreign airlines. This is due to the lack of scientific and effective management and control. In this paper, the quantitative prediction method for controlling maintenance costs of aircraft engines is discussed. The classification of engine maintenance cost units is suggested, the calculating formulae of engine maintenance costs are established, and the software realizing method and technology is given. The research will provide the senior managers of airlines with scientific guidance for better control of aircraft engine maintenance costs and support in decision making.

A Research on the 3D Reconstruction of the shape of the Endoscope

YANG Dong-ying, WU Jia-qi, QIAN Jin-wu

2003, 21(4):  406-410. 

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This paper presents a method for the 3D model reconstruction of the endoscope's body to meet the need of endoscopic inspection. First, the paper introduces the moving coordinate system based on the curve tangent vector and the curvature component vectors. Next, the total curvature vector is composed and the osculating plane determined in the moving coordinate system. The curve bending is then calculated and the recursion analysis made on the osculating plane. Finally, the correlative formulas are deduced and the method is validated by examples.

A Comparative Analysis on EEG Complexity of AD Patients

ZHAO Li, WAN Bai-kun, QI Hong-zhi, YANG Chun-mei

2003, 21(4):  411-415. 

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The complexity characteristics of the electroencephalogram (EEG) of Alzheimer's disease (AD) patients were analyzed and compared with healthy persons of the same age by using nonlinear dynamics theory. The preliminary results showed that the EEG complexity values of AD patients in all leads are clearly lower than the corresponsive values of healthy persons. It indicated that the complexity could be used as a specific parameter for the clinical diagnostic of AD.

A Design for Spiral Wound Clutch Facing

FANG Pei-chen, LI Feng, YANG Shu-hua

2003, 21(4):  416-418. 

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In this paper, we propose a mathematic model and on the basis of this model we suggest a design for spiral wound clutch facing.

Effects of Metal Ions and Oxidants on the Photochemical Degradation of 4 Chlorophenol

YU Zhi-yong, SONG Lin, ZHU Yan, SUN Zhen, TANG Xiao-chun

2003, 21(4):  419-422. 

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Under experimental conditions, Mn²⁺/Fe²⁺/Cu²⁺/Zn²⁺/Al³⁺/Y³⁺/La³⁺(especially for Y³⁺and La³⁺),KMnO₄/K₂S₂O₈/KClO₃/KClO₄/KBrO₃/KIO₃ can accelerate the photochemical degradation of 4chlorophenol(4CP), and this acceleration effect increases with the increase of concentration of metal ions and oxidants. KIO₄ can inhibit the photochemical degradation of 4CP, and this inhibition effect increases with the increase of the concentration of KIO₄. Cooperative effect of KClO₃/KBrO³⁺Y³⁺ on the photochemical degradation of 4CP is more striking. Without illumination, KMnO₄, KIO₄+Mn²⁺/Fe²⁺ can cause 4CP to be oxygenated at once, the effects of KMnO₄ and KIO₄+Mn²⁺ are especially striking.

Modeling and Analyzing the Substrate Temperature Field in the Large Area Hot-Filament CVD System

SONG Sheng-li, ZUO Dun-wen, WANG Min

2003, 21(4):  423-426. 

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In this paper, the substrate temperature field is modelled by using heat transfer theory to study the large area hot filament CVD system. In order to meet the requirement for proper magnitude and uniformity of the substrate temperature during the formation of the diamond film, the work to optimize the parameters of the substrate temperature field is performed. Sensitivity analysis is then used to search the key factor which deeply influences the substrate temperature field.

Optimal Reservation Guard Channel in Wireless System

GONG Wen-bin, GAN Zhong-min

2003, 21(4):  427-430. 

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This paper analyzes the performance of reservation guard channel with handoff priority. For blocking rate and dropping rate are two discrepant variables, we propose a variable of service grade that integrates the two variables as metrics for system service quality. The result shows that the service grade can trade off well between the blocking rate and dropping rate, and can also decide the optimal number of reservation guard channel and the system maximum load.

A Sufficient Condition and a Study of Hamilton-Connected Graphs

ZHAO Ke-wen, ZENG Ke-yang

2003, 21(4):  431-434. 

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Let G=(V,E) be the simple graph of order n, this shows a new sufficient condition HN ≥ n which imply the three improves and generalizes basic sufficient conditions of Dirac, Ore and neighborhood union. A study of the Hamiltonian, Hamilton connected graphs with HN ≥ n has also been made.