JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY

Agent-Based Data Mining Framework for the High-Dimensional Environment

LI Kan, LIU Yu-shu

2005, 14(2): 113-116.

[Abstract](209)

Abstract:
An agent-based data mining framework for the high-dimensional environment is built instead of the style of classical structural programming or the object-oriented programming. The framework supports the whole process of data mining of the high-dimensional environment. Belief-desire-joint intention agents are designed to fit the characteristic of the high-dimensional environment. At the same time, the syntax, semantics and reasoning rules of the agents are given. In the data mining system of the high-dimensional environment, agents need exchange messages. The cooperation behavior mechanism is adopted to complete the communication through the three-level pattern among agents that have their own fixed roles.

Algorithm to Form Coalition in Multi-Agent Cooperation

CAO Yuan-da, LI Jian

2005, 14(2): 117-120.

[Abstract](153)

Abstract:
In multi-agent systems, autonomous agents may form coalition to increase the efficiency of problem solving. But the current coalition algorithm is very complex, and cannot satisfy the condition of optimality and stableness simultaneously. To solve the problem, an algorithm that uses the mechanism of distribution according to work for coalition formation is presented, which can achieve global optimal and stable solution in subadditive task oriented domains. The validity of the algorithm is demonstrated by both experiments and theory.

Hardware-Software Co-Simulation for SOC Functional Verification

YAN Ying-jian, LIU Ming-ye

2005, 14(2): 121-125.

[Abstract](178)

Abstract:
A hardware-software co-simulation method for system on chip (SOC) design is discussed. It is based on an instruction set simulator (ISS) and an event-driven hardware simulator, and a bus interface model that is described in C language provides the interface between the two. The bus interface model and the ISS are linked into a singleton program--the software simulator, which communicate with the hardware simulator through Windows sockets. The implementation of the bus interface model and the synchronization between hardware and software simulator are discussed in detail. Co-simulation control of the hardware simulator is also discussed.

Study and Implementation of Web Mining Classification Algorithm Based on Building Tree of Detection Class Threshold

CHEN Jun-jie, SONG Han-tao, LU Yu-chang

2005, 14(2): 126-129.

[Abstract](117)

Abstract:
A new classification algorithm for web mining is proposed on the basis of general classification algorithm for data mining in order to implement personalized information services. The building tree method of detecting class threshold is used for construction of decision tree according to the concept of user expectation so as to find classification rules in different layers. Compared with the traditional C4.5 algorithm, the disadvantage of excessive adaptation in C4.5 has been improved so that classification results not only have much higher accuracy but also statistic meaning.

Multicast Routing Based on Hybrid Genetic Algorithm

CAO Yuan-da, CAI Gui

2005, 14(2): 130-134.

[Abstract](173)

Abstract:
A new multicast routing algorithm based on the hybrid genetic algorithm (HGA) is proposed. The coding pattern based on the number of routing paths is used. A fitness function that is computed easily and makes algorithm quickly convergent is proposed. A new approach that defines the HGA's parameters is provided. The simulation shows that the approach can increase largely the convergent ratio, and the fitting values of the parameters of this algorithm are different from that of the original algorithms. The optimal mutation probability of HGA equals 0.50 in HGA in the experiment, but that equals 0.07 in SGA. It has been concluded that the population size has a significant influence on the HGA's convergent ratio when it's mutation probability is bigger. The algorithm with a small population size has a high average convergent rate. The population size has little influence on HGA with the lower mutation probability.

Multipath Source Self Repair Routing Algorithm for Mobile Ad Hoc Networks

WU Dong-ya, HOU Chao-zhen, HOU Zi-feng

2005, 14(2): 135-139.

[Abstract](177)

Abstract:
A multipath source self repair routing (MSSRR) algorithm for mobile ad hoc networks is proposed. By using multiple paths which can be repaired by themselves to transmit packets alternately, the network's load is balanced, the link state in the network can be checked in time, the number of the times the route discovery mechanism starts is decreased. If only one route which will be broken can be used to transmit the packets, the route discovery mechanism is restarted.The algorithm is implemented on the basis of dynamic source routing (DSR). The effect of MSSRR on lifetime of the access from the source to the destination and the overhead is discussed. Compared with the performance of DSR,it can be seen that the algorithm can improve the performance of the network obviously and the overhead almost does not increase if the average hop count is larger.

Flexible Satellite Attitude Control via Adaptive Fuzzy Linearization

GUAN Ping, LIU Xiang-dong, CHEN Jia-bin, LIU Xiao-he

2005, 14(2): 140-144.

[Abstract](246) [PDF 193KB](2)

Abstract:
The adaptive fuzzy control is combined with input-output linearization control to constitute the hybrid controller. The control method is then applied to the attitude maneuver control of the flexible satellite. The basic control structure is given. The rules of the controller parameter selection, which guarantee the attitude stabilization of the satellite with parameter uncertainties, have been analyzed. Simulation results show that the precise attitude control is accomplished in spite of the uncertainty in the system.

Novel Method to Handle Inequality Constraints for Nonlinear Programming

HUANG Yuan-can

2005, 14(2): 145-149.

[Abstract](185)

Abstract:
By redefining the multiplier associated with inequality constraint as a positive definite function of the originally-defined multiplier, say, u2_i, i=1, 2,. .., m, nonnegative constraints imposed on inequality constraints in Karush-Kuhn-Tucker necessary conditions are removed. For constructing the Lagrange neural network and Lagrange multiplier method, it is no longer necessary to convert inequality constraints into equality constraints by slack variables in order to reuse those results dedicated to equality constraints, and they can be similarly proved with minor modification. Utilizing this technique, a new type of Lagrange neural network and a new type of Lagrange multiplier method are devised, which both handle inequality constraints directly. Also, their stability and convergence are analyzed rigorously.

New Rate Allocation Method for MPEG-4 FGS Video Streaming

DONG Hai-yan, LU Han-sheng, LI Sheng-cai, HOU Shan-feng, GAO Zhi-yun

2005, 14(2): 150-153.

[Abstract](185)

Abstract:
A new rate allocation method for fine-granular scalability (FGS) coded bitstreams is presented in order to achieve smooth quality reconstruction of frames under channel conditions with a wide range of bandwidth variation and improve the average PSNR of the whole sequence. Based on a quality weighted bit allocation method, a sliding window rate allocation method is proposed for the first time so that the window can slide along the video sequence with a certain sliding step. Experimental results show that, under dynamic bandwidth conditions, the proposed method can simultaneously satisfy the requirements for improving average PSNR of the whole video sequence greatly and reducing the fluctuations between adjacent frames greatly.

Characteristics of Mesh Wave Impedance in FDTD Non-Uniform Mesh

REN Wu, LIU Bo, GAO Ben-qing

2005, 14(2): 154-157.

[Abstract](197)

Abstract:
In order to increase the evaluating precision of mesh reflection wave, the mesh wave impedance (MWI) is extended to the non-uniform mesh in 1-D and 2-D cases for the first time on the basis of the Yee's positional relation for electromagnetic field components. Lots of characteristics are obtained for different mesh sizes and frequencies. Then the reflection coefficient caused by the non-uniform mesh can be calculated according to the theory of equivalent transmission line. By comparing it with that calculated by MWI in the uniform mesh, it is found that the evaluating error can be largely reduced and is in good agreement with that directly computed by FDTD method. And this extension of MWI can be used in the error analysis of complex mesh.

Rejection of Linear FM Interference in DSSS System Based on Fractional Fourier Transform

QI Lin, TAO Ran, ZHOU Si-yong

2005, 14(2): 158-161.

[Abstract](164)

Abstract:
A new method for the rejection of linear frequency modulation (LFM) interference in direct sequence spread spectrum (DSSS) system based on the fractional Fourier transform is proposed, and the configuration of the receiver with an interference exciser is also presented. Based on the property that the fractional Fourier transform of a signal is equivalent to rotating the signal in the time-frequency plane, the received signal is transform into a certain fractional Fourier domain, this transform will result in the least spectrum overlap between the signal and interference. Then, a narrowband filter is exploited to extract most of the interference energy. The performance analyses show that remarkable improvements in signal-to-noise ratio (SNR) and bit-error-ratio (BER) are obtained.

Simulation on the Models of Small Scale Passive Acoustic Sensor Arrays Based on Time-Delay Estimation Method

LI Jie, LI Zhe, CHEN Wen-cong

2005, 14(2): 162-165.

[Abstract](187)

Abstract:
The passive acoustic localization with planar sensor array is introduced. Based on a method to eliminate the influence of effective sound velocity in passive detection, a new five-sensors solid array and its localization model are put forward. The factors that influence the precision of the localization are analyzed. Considering the errors from the factors synchronously, the simulation compares the solid array with the planar array. It can be proved that the five-sensor solid array is better than the four-sensor planar array in the estimation of bearing elements.

Decoupling Control Method Based on Neural Network for Missiles

ZHAN Li, LUO Xi-shuang, ZHANG Tian-qiao

2005, 14(2): 166-169.

[Abstract](171) [PDF 154KB](2)

Abstract:
In order to make the static state feedback nonlinear decoupling control law for a kind of missile to be easy for implementation in practice, an improvement is discussed. The improvement method is to introduce a BP neural network to approximate the decoupling control laws which are designed for different aerodynamic characteristic points, so a new decoupling control law based on BP neural network is produced after the network training. The simulation results on an example illustrate the approach obtained feasible and effective.

Adaptive Clutch Engaging Process Control for Automatic Mechanical Transmission

LIU Hai-ou, CHEN Hui-yan, DING Hua-rong, HE Zhong-bo

2005, 14(2): 170-174.

[Abstract](214) [PDF 182KB](4)

Abstract:
Based on detail analysis of clutch engaging process control targets and adaptive demands, a control strategy which is based on speed signal, different from that of based on main clutch displacement signal, is put forward. It considers both jerk and slipping work which are the most commonly used quality evaluating indexes of vehicle starting phase. The adaptive control system and its reference model are discussed profoundly. Taking the adaptability to different starting gears and different road conditions as examples, some proving field test records are shown to illustrate the main clutch adaptive control strategy at starting phase. Proving field test gives acceptable results.

New Method for Confirming the Desired Safety Headway Distance and Desired Deceleration in ACC System

ZHANG Jing-bo, LIU Zhao-du, SONG Ming, QI Zhi-quan

2005, 14(2): 175-178.

[Abstract](212)

Abstract:
A new method of confirming the desired safety headway distance and desired deceleration is put forward according to the detected static or moving target and its simulation results in Matlab are also presented. The validity of the algorithm to calculate the reference speeds of both the ACC vehicle and the targeted car according to the vector quadrangle composed of the relative distance, the relative azimuth angle, the relative speeds of the vehicles has also been demonstrated through numerical example in Matlab. New laws to obtain the desired deceleration by estimating the braking force according to the vehicle analyses force equation are established too.

Improving Designs of CA6DF2 Series Diesel Combustion System

LI Wen-xiang, GE Yun-shan, HU Fang, LI Jun

2005, 14(2): 179-183.

[Abstract](193)

Abstract:
The technical improvements are made based on the former CA6110 diesel engine to meet the requirements of Euro Ⅱ emission standards. The performance and emission for CA6DF1 and CA6DF2 are all met the demand of design by improving the fuel, combustion and supercharging systems. The injection system adopts high-pressure pump-pipe-injector injection system. To enhance the injection pressure, the methods of augmenting plunger diameter, decreasing the nozzle hole diameter and reducing the inner diameter of the high-pressure fuel pipe are adopted. The design of combustion chamber and the match of inner fuel distributions with air motion are based on a great deal of experimental database and some simple computer-aided methods, which ensure the optimization of performance and provide the guide for experimental development.

Research on Dynamic Model of the Human Body

ZHANG Chun-lin, WANG Guang-quan, LU Dun-yong

2005, 14(2): 184-187.

[Abstract](206)

Abstract:
After summarizing the current situation of the research on human body modeling, a new dynamic model containing 5 equivalent masses has been proposed and the corresponding dynamic equations has been deduced too. By using this new model, more detailed information about the situation of the human body under impact and vibration can be obtained. The new model solves the problem that transmission functions of forces inside the human body can't be deduced by using 3-equivalent-mass model. It will find its usage in many applications.

Synthesis and Characterization of a Novel Cellulose Nonionic Ether

SHAO Zi-qiang, XU Kun, TIAN Yong-sheng, WANG Fei-jun, WANG Ji-xun

2005, 14(2): 188-191.

[Abstract](133)

Abstract:
A kind of novel cellulose ether-trihydroxybutyl cellulose （THBC） was synthesized. The process includes the steam explosion treatment of cotton cellulose, alkalization, etherification and purification. Sweep electron microscope （SEM）, Fourier transform infrared （FTIR） and X-ray diffraction were used to characterize the cellulose pretreated and the product. The effects of reaction conditions （temperature, time） on the molecular substitution （S_m） were discussed. To obtain a higher degree of molecular substitution, the reaction temperature is 80 ℃, and the reaction time is 4 h.

Effects of External Stresses on the Carbide Precipitation in Bainite Transformation

SU Tie-jian, DENIS S, GAUTIER E

2005, 14(2): 192-195.

[Abstract](174)

Abstract:
TEM observation of carbide precipitates in bainite has been carried out for steel 40CMD8. Specimens transformed at 350 ℃ and 450 ℃ without external stress contain respectively the lower and the upper bainite. No fundamental change in carbide precipitation is observed in specimen transformed at 350 ℃ under stress of 128 MPa. The very fine cementite is found precipitated within the upper bainite plates in specimen transformed at 450 ℃ under stress of 144 MPa, which can be explained as the result of the difficulty of carbon diffusing out of the massive ferrite plate within a much shortened transformation time due to the external stress. For all the specimens examined, Bagaryatskii orientation relationship is found existing between the carbides and ferrite matrix.

Synthesis of 7-Azidoacetamido-4,6-Dinitro-Benzofuroxan

WANG Jian-long, OU Yu-xiang, LV Lian-ying, CHEN Bo-ren

2005, 14(2): 196-198.

[Abstract](152) [PDF 122KB](4)

Abstract:
7-Azidoacetamido-4,6-dinitro-benzofuroxan has been synthesized from the starting materials of chloroacetyl chloride and m-chloroaniline, and has been characterized by elemental analysis, IR, 1H NMR and MS spectroscopies. The title compound was obtained through the reactions of amidation, nitration, azidation and pyrolysis. Azido group was introduced into benzofuroxan derivative to give the energetic compound of high nitrogen content and high enthalpy of formation. It is hopeful that the title compound can be developed into new energetic material and energetic plastic additives.

Ab Initio Quantum Chemistry Study of Nitrogen Cages N₂n（n=12-18）

YIN Peng-gang, ZHAO Jun-fang, GUAN Jun, GAO Feng-xin, XU Wen-guo

2005, 14(2): 199-202.

[Abstract](210)

Abstract:
Ab initio quantum mechanical method has been applied to nitrogen cages N2n （n=12-18）. Full geometry optimization, harmonic vibrational frequency and thermodynamics data for eight structures of nitrogen cages N2n （n=12-18） were performed at the HF/cc-pVDZ level. Cage N24 （D6d ）, N24 （O_h）, N26 （D6d ）, N28 （T_d）, N30 （D5h ）, N32 （D3d ）, N36 （D2d ） and N36 （D6h ） were found to be local minima on the potential energy surfaces. The computational results show that all the bond lengths of the eight structures are close to 0.145 nm and their bond energies EN-N are near to the experimental data of N-N single-bond. In addition, the thermochemical data of these nitrogen cages indicated that they are stable. It suggests that they are candidates for high energy density materials.

Existence of Solution to Multi-Point Boundary Value Problems at Resonance

XUE Chun-yan, GAO Jing, GE Wei-gao

2005, 14(2): 203-207.

[Abstract](170)

Abstract:
A class of second order multi-point boundary value problem at resonance is considered. Under some appropriate conditions, the existence of solutions to the nonlinear problem is obtained by use of the coincidence degree theory of Mawhin.

On Submanifolds in Locally Symmetric and Conformally Flat Riemannian Manifolds

SUN Hua-fei, TANG Li, CHEN Chun

2005, 14(2): 208-211.

[Abstract](100)

Abstract:
Let N n+p be an (n+p)-dimensional locally symmetric and conformally flat Riemannian manifold and Mn be an n-dimensional compact submanifold minimally immersed in N n+p. Instead of (n+p)-dimensional unit sphere, we generalize Pinching Theorems about submanifolds in unit sphere and get theorems about submanifolds in locally symmetric and conformally flat Riemannian manifold.

Formalization and Verification of Business Process Modeling Based on UML and Petri Nets

YAN Zhi-jun, GAN Ren-chu

2005, 14(2): 212-216.

[Abstract](168)

Abstract:
In order to provide a quantitative analysis and verification method for activity diagrams based business process modeling, a formal definition of activity diagrams is introduced. And the basic requirements for activity diagrams based business process models are proposed. Furthermore, the standardized transformation technique between business process models and basic Petri nets is presented and the analysis method for the soundness and well-structured properties of business processes is introduced.

Improved Butterfly Subdivision Scheme for Meshes with Arbitrary Topology

ZHANG Hui, MA Yong-you, ZHANG Cheng, JIANG Shou-wei

2005, 14(2): 217-220.

[Abstract](73)

Abstract:
Based on the butterfly subdivision scheme and the modified butterfly subdivision scheme, an improved butterfly subdivision scheme is proposed. The scheme uses a small stencil of six points to calculate new inserting vertex, 2n new vertices are inserted in the 2n triangle faces in each recursion, and the n old vertices are kept, special treatment is given to the boundary, achieving higher smoothness while using small stencils is realized. With the proposed scheme, the number of triangle faces increases only by a factor of 3 in each refinement step. Compared with the butterfly subdivision scheme and the modified butterfly subdivision scheme, the size of triangle faces changes more gradually, which allows one to have greater control over the resolution of a refined mesh.

Pairings-Based Protocol for Group Key Agreement

LI Ming, WANG Yong, GU Da-wu, BAI Ying-cai

2005, 14(2): 221-224.

[Abstract](88)

Abstract:
An authenticated group key agreement protocol suite (PAGKA) based on pairings is presented in this paper. This suite extends an efficient Diffie-Hellman-based protocol suite by introducing parings on elliptic curves and public-key certificates. The result suite builds its security on the hardness of the bilinear Diffie-Hellman (BDH) problem in the random oracle model, and provides implicit key authentication, perfect forward secrecy and unknown key-share secrecy.

2005 Vol. 14, No. 2