JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY

Research on Volume Identification with the Method of Discharging at the Velocity of Sound

2002, 11(1): 1-4.

[Abstract](203)

Abstract:
The method of volume identification in pneumatics was studied through theoretical analysis and experimental investigation. Regarding discharging from a container as a thermodynamic process with invariable index the dependence of the container's volume on the pressure in the container and the index, during discharging at the velocity of sound, is deduced. Then through a lot of experiments, the value of index n of the process is found with a given precision and a specified volume range. Furthermore, the feasibility and practicability of this method are verified by experiments.

Two Adaptive Control Algorithms in Semi-Active Suspension System

HUANG Hong, HOU Chao zhen, GAO Xin

2002, 11(1): 5-9.

[Abstract](176)

Abstract:
To reduce the vibration in the suspension, semi active suspension system was employed. And its CARMA model was built. Two adaptive control schemes, the minimum variance self tuning control algorithm and the pole configuration self tuning control algorithm, were proposed. The former can make the variance of the output minimum while the latter can make dynamic behavior satisfying. The stability of the two schemes was analyzed. Simulations of them show that the acceleration in the vertical direction has been reduced greatly. The purpose of reducing vibration is realized. The two schemes can reduce the vibration in the suspension and have some practicability.

Target Seeker Gyro and Controls

WANG Bo, GAO Hong min, HAO Ai fang, DONG Ming jie

2002, 11(1): 10-13.

[Abstract](183)

Abstract:
A composite target seeker gyro with dual spectral range infrared rays and millimeter waves, and the associated control methodology are developed. The static pressure air floated ball bearing is used to sustain the outer frame, the optical fiber and wave guide are used to transmit these two kinds of signals to the rear part of the gyro, and the stator coils are used to get non contact angular measurement. Composite guiding, scanning, tracing and controlling can be achieved, the maximum tracing angular velocity can be as high as 16(°)/s.

Modeling of the Multi-Target Locating and Tracking in the Field Artillery System

YANG Guo sheng, DOU Li hua, CHEN Jie, HOU Chao zhen

2002, 11(1): 14-18.

[Abstract](269) [PDF 192KB](20)

Abstract:
A method for the multi target locating and tracking with the multi sensor in a field artillery system is studied. A general modeling structure of the system is established. Based on concepts of cluster and closed ball, an algorithm is put forward for multi sensor multi target data fusion and an optimal solution for state estimation is presented. The simulation results prove the algorithm works well for the multi stationary target locating and the multi moving target tracking under the condition of the sparse target environment. Therefore, this method can be directly applied to the field artillery C 3I system.

Approximation Property of the Modified Elman Network

REN Xue mei, CHEN Jie, GONG Zhi hao, DOU Li hua

2002, 11(1): 19-23.

[Abstract](165)

Abstract:
A new type of recurrent neural network is discussed, which provides the potential for modelling unknown nonlinear systems. The proposed network is a generalization of the network described by Elman, which has three layers including the input layer, the hidden layer and the output layer. The input layer is composed of two different groups of neurons, the group of external input neurons and the group of the internal context neurons. Since arbitrary connections can be allowed from the hidden layer to the context layer, the modified Elman network has more memory space to represent dynamic systems than the Elman network. In addition, it is proved that the proposed network with appropriate neurons in the context layer can approximate the trajectory of a given dynamical system for any fixed finite length of time. The dynamic backpropagation algorithm is used to estimate the weights of both the feedforward and feedback connections. The methods have been successfully applied to the modelling of nonlinear plants.

Robust Stability Analysis of Edge Polynomials with Variable Length

WU Qing he

2002, 11(1): 24-28.

[Abstract](139)

Abstract:
The concept of edge polynomials with variable length is introduced. Stability of such polynomials is analyzed. Under the condition that one extreme of the edge is stable, the stability radius of edge polynomials with variable length is characterized in terms of the real spectral radius of the matrix H -1 ( f 0) H (g), where both H (f 0) and H (g) are Hurwitz like matrices. Based on this result, stability radius of control systems with interval type plants and first order controllers are determined.

Application of Maximum Probability Approach to the Fault Diagnosis of a Servo System

MA Dong sheng, HU You de, DAI Feng zhi

2002, 11(1): 29-32.

[Abstract](155)

Abstract:
In an actual control system, it is often difficult to find out where the faults are if only based on the outside fault phenomena, acquired frequently from a fault system. So the fault diagnosis by outside fault phenomena is considered. Based on the theory of fuzzy recognition and fault diagnosis, this method only depends on experience and statistical data to set up fuzzy query relationship between the outside phenomena (fault characters) and the fault sources (fault patterns). From this relationship the most probable fault sources can be obtained, to attain the goal of quick diagnosis. Based on the above approach, the standard fuzzy relationship matrix is stored in the computer as a system database. And experiment data are given to show the fault diagnosis results. The important parameters can be on line sampled and analyzed, and when faults occur, faults can be found, the alarm is given and the controller output is regulated.

Adaptive Modification of the Rolling Force Prediction

YAO Xiao lan, ZHANG Di sheng, LIANG Qi hong, HU Hao ping

2002, 11(1): 33-36.

[Abstract](173)

Abstract:
In rolling process, the rolling force is an important parameter. The precision of the predicted rolling force will directly affect the precision of the finished product. By using adaptive control theory and fusing the measured and predicted data, the precision of the predicted rolling force is gradually improved. This system has been used in plant for more than one year, and the result of the application shows that the system has steady and reliable performance, and high precision.

Application of the Plate Crown Prediction

YAO Xiao lan, ZHANG Di sheng, LIANG Qi hong

2002, 11(1): 37-40.

[Abstract](98)

Abstract:
The program of the plate crown optimal prediction applied in the plate mill of Wuhan Iron and Steel(Group) Co. Ltd. is described. Optimal prediction is programmed in ALPHA 4000. The original profile, wear, expansion and deformation of work rolls are introduced into the program. The plate crown is controlled by the original profile of work rolls and the draft whose objective is the optimal plate crown. The run schedule is also optimized through the optimal prediction of the plate crown.

Design and Study of a High Security ATM System

FAN Rui xia, ZHAO Ze xiang, ZHANG Jun

2002, 11(1): 41-44.

[Abstract](194)

Abstract:
Based on the characteristics of ATM system and the special requirement of financial transaction, an overall design of hardware and software structure of ATM was made. For software structure, the pattern of modules and table? drive is adopted to realize the security of financial transaction and the diagnosis of communication fault. A new method, which is based on the application layer, transport layer and network layer, is used for diagnosing communication fault. Supporting both magnetic card and IC card, the system has been put into use in real financial systems, and has brought about both economic and social effects.

Study of Controlling Clutch Engagement for AMT Based on Fuzzy Logic

TANG Xia qing, HOU Chao zhen, CHEN Yun chuang

2002, 11(1): 45-49.

[Abstract](185)

Abstract:
The control of the clutch engagement for an automatic mechanical transmission in the process of a tracklayer getting to start is studied. The dynamic model of power transmission and automatic clutch system is developed. Using tools of Simulink, the transient characteristics during the vehicle starting, including the jerk and the clutch slip time, are provided here. Based on the analyses of the simulation results and driver's experiences, a fuzzy controller is designed to control the clutch engagement. Simulation results verify its value.

Data Analysis and Modeling of Fiber Optic Gyroscope Drift

MIAO Ling juan, ZHANG Fang sheng, SHEN Jun, LIU Wei

2002, 11(1): 50-55.

[Abstract](204)

Abstract:
A data gathering system is designed for the interferometric fiber optic gyroscope (IFOG) of land strapdown inertial system. IFOG is tested and the testing curve is given. The test data of IFOG are analyzed with Allan variance method and each error coefficient is identified. Furthermore, a random drift error model for IFOG is built by the method of time series analysis. The conclusion provides supports for improving IFOG design and compensating for errors of IFOG in practice.

Experiment Study on the Ending Criteria of Charge and Discharge of Nickel-Hydride Battery

SUN Feng chun, CHEN Yong, HE Hong wen, ZHANG Cheng ning

2002, 11(1): 56-60.

[Abstract](184) [PDF 209KB](4)

Abstract:
Charge and discharge characteristics of Ni/MH batteries are investigated with experiments. During battery's working, the voltage, capacity, temperature and internal resistance were recorded, corresponding curves were depicted. Variations of the aforementioned four parameters are differently obvious. Ending criteria of charge and discharge of Ni/MH batteries are discussed on the basis of the curves. Voltage, capacity and temperature of a battery can be used as ending criteria during charge. When discharge takes place, voltage, capacity and internal resistance can be chosen as ending criteria. As a whole, capacity is more suitable for being used as ending criteria of charge and discharge than the other three parameters. At last, the capacity of a battery is recommended to be ending criteria of charge and discharge. The conclusions will provide references to different capacity Ni/MH batteries for electric vehicles.

Modeling for Action of Recovering from Erroneous Driving Condition Based on Revised Decision Tree

WANG Wu hong, SHEN Zhong jie, DU Qiu

2002, 11(1): 61-65.

[Abstract](187)

Abstract:
Driving behavior modeling is very important in the research area of road traffic systems safety analysis. The characteristics of action of recovering from erroneous driving condition underlying road traffic accident or incident scenarios is quantitatively analyzed, the model of action of recovering from erroneous driving condition is set up according to the identification of erroneous driving condition and the measurement of correction from erroneous driving condition. And then, the probability of action of recovering from erroneous driving condition has been measured based on a revised decision tree. The measure process uses a combination of test data and subjective judgments of driving behavior. It can provide a very helpful theoretical basis for the further analysis of driving behavior in road traffic system.

Processing of 8-Channel Synchronous Electro-Cardiograph

ZHAO Jie, HAN Yue qiu

2002, 11(1): 66-70.

[Abstract](137)

Abstract:
A real time algorithm is presented here to recognize and analyze 8 channel simultaneous electro cardiograph(ECG). The algorithm transforms 8 channel simultaneous ECG into three orthogonal vectors and spatial velocity first, then forms the spatial velocity sample, and uses this spatial velocity sample to recognize each beat. The algorithm computes the averaged parameters by using averaged spatial velocity and the averaged ECG and the current parameters by using the current beat period and current width of QRS. The algorithm can recognize P, QRS and T onsets and ends of simultaneous 12 lead ECG precisely, and some arrhythmias such as premature ventricular beat, ventricular escape beat, R on T, bigeminy, trigeminy. The algorithm software works well on a real 8 channel ECG system and meets the demands of designing.

Analysis of Test Methods for Parts to Follow Relative Requirements

PAN Shu qing

2002, 11(1): 71-74.

[Abstract](152)

Abstract:
Testing the parts of mechanical products and ensuring their accuracy to the design requirements are essential to products' quality, market competitiveness and manufacturers' maximum economical benefits from these products. One of the latest subjects of study in the area of precision measurement is the testing of parts to follow the relative requirements, viz. design requirements for the size tolerance of size features and related geometrical tolerances of the central feature, including the envelope requirement, maximum material requirement and least material requirement. The article analyzes test methods for parts to follow the envelope requirement or maximum material requirement, as well as further requirements of geometrical tolerances for its central feature. The method is effective in improving product quality and rejecting unqualified parts.

Investigation on the Shock Response of Vitreous Carbon

WU Cheng

2002, 11(1): 75-80.

[Abstract](187)

Abstract:
The dynamic response of vitreous carbon to uniaxial strain loading has been investigated by means of the plate impact experiments. The two x cut shorted quartz gauges assembled with impactor and target were used to obtain the wave speeds in material and the stress histories at the sample gauge interface. The wave speed and stress histories were analyzed to determine the peak state in the sample. For compressive stress up to 4 0 GPa, the wave profiles were observed to be simple and steady, the uniaxial strain response is essentially nonlinear elastic, and no inelastic deformation has been found. All the experiment results indicate that the Hugoniot curve of vitreous carbon is concave downward just like that of fused silicon. There is no shock wave but the compressed wave propagating in the impacted samples.

Accessing Web Heterogeneous Databases Based on CORBA

LIU Jian, LIANG Yun rong, YANG Jun

2002, 11(1): 81-84.

[Abstract](96)

Abstract:
The future usage of heterogeneous databases will consist of the WWW and CORBA environments. The integration of the WWW databases and CORBA standards are discussed. These two techniques need to merge together to make distributed usage of heterogeneous databases user friendly. In an environment integrating WWW databases and CORBA technologies, CORBA can be used to access heterogeneous data sources in the internet. This kind of applications can achieve distributed transactions to assure data consistency and integrity. The application of this technology is with a good prospect.

Uniform Representation Model for Metadata of Data Warehouse

WANG Jian fen, CAO Yuan da

2002, 11(1): 85-88.

[Abstract](146)

Abstract:
A uniform metadata representation is introduced for heterogeneous databases, multi media information and other information sources. Some features about metadata are analyzed. The limitation of existing metadata model is compared with the new one. The metadata model is described in XML which is fit for metadata denotation and exchange. The well structured data, semi structured data and those exterior file data without structure are described in the metadata model. The model provides feasibility and extensibility for constructing uniform metadata model of data warehouse.

Radial Based Probabilistic Roadmap Motion Planning Method in Sparse Environment

GAO Chun xiao, LIU Yu shu, ZHENG Jun

2002, 11(1): 89-92.

[Abstract](170)

Abstract:
A new dynamic path planning method in high dimensional workspace, radial based probabilistic roadmap motion (RBPRM) planning method, is presented. Different from general probabilistic roadmap motion planning methods, it uses straight lines as long as possible to construct a path graph, so the final path obtained from the graph is relatively shorter and straighter. Experimental results show the efficiency of the algorithm in finding shorter paths in sparse environment.

Some Theorems About Unitons of Harmonic Maps into U(N)

CHENG Qi yuan

2002, 11(1): 93-96.

[Abstract](97)

Abstract:
By using the simplified method of factorization given by Valli, and the correspondence between the harmonic map φ∶S 2→U(N) and U(N) uniton bundle ν(φ) with energy corresponding to the bundles' second Chern class, which is established by Anand, the energy in a case φ∶S 2→U(N) is investigated in order to estimate the energy of a uniton using the uniton number. It is proved that Uhlenbeck's factorization is energy decreasing. And a method of estimating the energy of a uniton by the uniton number is given.

Robustness of Minimum Norm Quadratic Unbiased Estimator of Variance Under the General Linear Model

ZHANG Bao xue, LUO Ji, LI Xin

2002, 11(1): 97-100.

[Abstract](208)

Abstract:
Necessary and sufficient conditions for equalities between a 2 y′(I-P Xx)y and minimum norm quadratic unbiased estimator of variance under the general linear model, where a 2 is a known positive number, are derived. Further, when the Gauss? Markov estimators and the ordinary least squares estimator are identical, a relative simply equivalent condition is obtained. At last, this condition is applied to an interesting example.

Exact Wave Function and Coherent States for a Time-Dependent Harmonic Oscillator

PENG Yan ze, PENG Song qing, FAN Tian you, SUN Ying fei

2002, 11(1): 101-104.

[Abstract](125)

Abstract:
By using a trial wave function, the exact wave function for a harmonic oscillator with time? dependent mass, frequency, damping and driving is obtained. And then by defining a unitary operator, coherent states for the system of interest are found. These coherent states have most, but not all, of the properties the time independent oscillator. And all the results obtained can be reduced to the usual ones when both the mass and frequency are constants and the driving is absent.

Computation of Diffusion Activation Energies of C, N in γFe

SU Wen yong, ZHANG Rui lin, SHAO Bin

2002, 11(1): 105-108.

[Abstract](227)

Abstract:
A structure relaxation model based on the empirical electron theory of solids and molecules is developed to compute the diffusion active energies of C, N in γFe. First, adding a restriction, the lattice maintains rigidity when solute atom migrates to the saddle point. In this step, the hybridization classes of every atom do not change. Then, the restriction is loosed and the atoms are relaxed under the coulomb repulsive forces. It is supposed that the energy needed in the first step would be compensated partly by the second step. In this way, the diffusion active energies of C, N in γFe are computed. Compared with the experiment data, the relative errors are less than 5%, which are good results in the computation of activation energy of diffusion.

Energies and Transition Rates of Low-Lying Excited States for Beryllium

HAN Li hong, GOU Bing cong, WANG Fei

2002, 11(1): 109-112.

[Abstract](116)

Abstract:
Low lying excited states of beryllium are calculated with multiconfiguration interaction method. The relativisitic corrections and mass polarization are included. The oscillator strength and radiation rates are also calculated. Our results are in good agreement with other theoretical data.

2002 Vol. 11, No. 1