JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY

Perturbation Theorems for Nash Point Equilibria in the Calculus of Variations

Jiang Ming

1992, 1(2): 75-86.

[Abstract](250)

Abstract:
The perturbation problems for Nash point equilibria are studied.By the careful analysis of the singular point set related to a weakly convergent function se-quence.The quasiconvex condition is used to wipe out the obstruction to strong con-vergence or weak lower semi-continuity in proving two perturbation theorems for Nash point equilibria.

Cross-Linked Crown Ether-SE-54 as Stationary Phase for Open-Tubular Column Gas Chromatography

Zhu Rongping, Fu Ruonong, Ge Jilong, Wang Hongju, Zhu Jiya, Huang Zaifu, Zhang Bin

1992, 1(2): 87-93.

[Abstract](196)

Abstract:
The cross-linking of crown ether-SE-54 in fused-silica capillary columns were initiated by dicumyl peroxide（DCUP）, azo-bis-isobutyronitrile （AIBN）and ozone（O₃）.Parameters of evaluation such as polarity,selectivity, phase transition temperature and thermal stability were studied and compared with those of poly（crown ether）stationary phase.

Forward Displacement Analysis of a Class of the 6-6 Stewart Platforms

Wang Guozhen

1992, 1(2): 94-102.

[Abstract](175)

Abstract:
A special form of the Stewart platform is presented in which the top platform and base platform are similar and corresponding vertices are connected by six prismatic joints.A closed-from solution for the forward displacement analysis of this mechanism is developed.When the six vertices of the top platform are in a quadratic curve,this mechanism becomes singular.This new theoretical result is confirmed with a numerical example.

Shape Optimal System for Linear Elastic Structures

Xing Jie, Cai Ping

1992, 1(2): 103-110.

[Abstract](223)

Abstract:
An integrated system FSOP2D,including modules for the shape optimal modeling,structural analysis,sensitivity analysis,optimal method library and post-processing,is developed.By selecting fictitious loads as the design variables that has a linear relationship with the grid point locations and using design sensitivity analysis of the domain method,it is easier to solve the velocity field.In the course of optimal iterations,mesh distortion is kept to a minimum,sensitivity derivatives of object function,stress constraints and displacement constraints are derived.Computation of sensitivity analysis is achieved in the system.Two engineering examples are used to prove the system's effectiveness,the optimal results can successfully be obtained by lesser number of iterations.

A Study on the Dynamic Performance of Hydroviscous Driyes

Cai Dujing, Wei Chenguan

1992, 1(2): 111-121.

[Abstract](152)

Abstract:
Gives a dynamic mathematical model of a typical type of multiple discs hydroviscous drive device which has been proved to be correct through tests.Utilizing the method of root-locus analysis the dynamic performance of this device is studied according to the model.Theoretical analysis and test re-suits show that the dynamic performance of the object of study can be greatly improved by speed negative feedback.

Linearity of Removal in the Proeess of Optical Element Polishing

Xin Qiming

1992, 1(2): 122-131.

[Abstract](130)

Abstract:
In the light of some assumptions that are very close to the practical working conditions,a very complicated polishing process of optical element can be simplified as a linear and shift invariant system that is relatd only to the speed,pres-sure and time of processing.In polishing,the removed material can be represented and entreated by the convolution of the removal function of polishing head and the dwell function.The properties of removal function are presented.The assumptions and methods given by the author have been shown to be correct and applicable by experiments using a ring lap to polish the optical surfac.

Calculation of Vapour Pressure of Metals by Statistical-Mechanical Method With the Debye Model

Wang Zhenggang, Luo ling

1992, 1(2): 132-138.

[Abstract](209)

Abstract:
Statistical expression of vapour pressure equations of metals is derived from the Debye model.The statistical distribution of T_-pensemble is presented in an in-elab-orate mode and the partition function is defined.The vapour pressure of eleven metals have been calculated with the Debye equation and compared with those given by the E-instein equation and empirical equation.Comparison of results of calculation from dif-ferent methods show their evident accordance within the same orders of magnitude.

On-Line Monitoring of Cutting Tool Fracture & Wear

Wang Xinyi, Xiao Dingguo, Song Xinmin

1992, 1(2): 139-150.

[Abstract](137)

Abstract:
A technique of detecting cutting tool fracture and ultimate wear by si-multaneously monitoring both the spindle motor current and cutting process related acoustic emission(AE)in the cutting process is reported.The technique can detect breakage of drills having diameter over 0.8mm,turning cutter crack of area over 0.2mm,and the ultimate wear.The principle,system construction,experimental method and result of the technique are discussed.The ratio of success in detection approaches 96% or higher.

A Study on the Monitoring System for the FMS

Qiu Guanghua, Lu Shiyi, Wang Xinyi

1992, 1(2): 151-157.

[Abstract](205)

Abstract:
Introduces a new monitoring method in FMS explicated in some detail by means of the MSF(Monitoring System of FMS)under development by the au-thors.In order to push FMS technology forword,enhance machining flexibility and the flexibility of human operaters and equipment in a FMS,the authors have made some breakthroughs in traditional ways of single item,unit monitoring and self-han-dling,and suggested the idea of integrated inspection and put the MSF into more practicability.The working status of FMS can be monitored on the CRT of a micro-computer of the MSF,system troubles will be shown with icons,by the flash of the system characteristic symbol or by alarming,and so on.This explores a new way for FMS inspection in a wholly integrated manner.

Application of the Monte Carlo Method in Simulative Generation Test Problems Simulative Generation Test Problems

Huang Xinyuan, Wan Yaoqing

1992, 1(2): 158-165.

[Abstract](151)

Abstract:
An approach for generating test problems by a computer using the Monte Carlo method based upon user-given characterizations is described.A single point X^*is prespocified by the user to be a solution of the test problems.The approach is flex-ible enough to specify function values,gradients,Hesse,degeneracy degree and ill-conditioned degree at the point X^*.Other numerical features such as indefiniteness, convexity are also under user's control.

Signal Filtering in Multizone Systems of Image Analysis of Image Analysis

Bykov R E

1992, 1(2): 166-178.

[Abstract](165)

Abstract:
Principles of color space generation for multizone optical registration systems are presented;conformity between different color spaces is defined;algo-rithms of the multizone image registrator signal processing and a generalized algo-rithm for analysis are given.Procedures are discussed for plotting the color spaces that are used in the analysis of the Earth and other planets.It is shown that estimates made in such spaces are interrelated and that spectral reflections of objects under study should be available in order to compare—in terms of color discrimination-several automatic recorders with different spectral sensitivities.Examples are given to illustrate color spaces having such properties.Circuits of chromaticity filters are also presented.

The Outer Performance Degradation of Shock Absorber and Its Effect on Ride Comfort and Driving Safety

Fu Zhao, Yu Defu

1992, 1(2): 179-190.

[Abstract](149)

Abstract:
Based on the well-known quarter car representation of the automobile suspension,this paper deals with the effect of shock absorber outer performance degradation(OPD)on vehicle ride comfort and driving safety.Based on an elastici-ty model of a flat circular plate having a central hole,a program for the determina-tion of shock absorber outer performance(SOP)has been developed. Based on a hy-drodynamic theory,principles for the inter performance design of shock absorbers are presented to ensure expected SOP and the concept of critical velocity for the pre-vention of OPD is studied.By analysing the mechanism of degradation,a method for the elimination of shock absorber degradation is offered for practical structural design,i.e,the structural design of dual-tube gas charge shock absorbers.A good deal of experimental data,are presented to prove the theoreticaly studies.

1992 Vol. 1, No. 2