JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY

Completely Invariant Domains of Holomorphic Self-Maps on C

Fang Liping

1997, 6(3): 187-191.

[Abstract](155) [PDF 251KB](7)

Abstract:
Let/(z) be a holomorph.self-map on C.-G-(0) with essential singularities 0 and It is proved that f(z) has a completdy invariant domain.D.F(f),then D is doubly connected and D contains all the singularities of the inverse of f(z),moreover,if f is of the finite type, then D=F(f). This result implies that f(z) has at most one completely invariant domain in F(f).

Existence of Solutions to Differential-Iterative Equation

Ge Weigao, Mo Yuren

1997, 6(3): 192-200.

[Abstract](240)

Abstract:
The existence and the behavior of solutions to the differential-iterative equation arestudied without the restriction that f is monotone An error in and available paper is correctedhere.

Uniqueness of Solutions to Differential-Iterative Equation

Ge Weigao

1997, 6(3): 201-207.

[Abstract](203)

Abstract:
Conditions for the uniqueness of solutions to the differential-iterative equations x'(t)=f(x(x(t))) are given by use of fixed point theorems.

On Accuracy of Lax-Friedrichs Scheme for Discontinuous Solutions of Convection Equations

Ding Lijuan

1997, 6(3): 208-212.

[Abstract](286)

Abstract:
Derive L-2-error bounds for Lax-Friedrichs schemes for discontinuous solutions oflinear hyperbolic convection equations.It is known that the Lax-Friedrichs scheme is a firstorder scheme.Analyzes convergent rate of the scheme through its modified equations andshows that the first order Lax-Friedrichs scheme to approach BV solutions of the convectionequation has L￣2-error bounds of O(△x￣(1/4)),where △x is the discrete mesh length.Nemericalexperiments are presented and numerical results justify the theoretical analysis.

Connections on Phase Space of AutonomousMechanical Systems with Constraints

Guo Yongxin, Mei Fengxiang

1997, 6(3): 213-220.

[Abstract](228)

Abstract:
The covariance of a dynamical flow with respect of a connection on tangent burdle is put forward The connection of an autonomous constrained mechanical system is found whose geodesic equations are equations of motion of the systems The connection is determined by dynamical functions and constraints of the system of the system and is reduced to the usual dynarmical connection of the dynamical flow is second drder homogmogeneous one.

The Noether's Theory of Constrained Birkhoffian System

Shang Mei, Mei Fengxiang

1997, 6(3): 221-228.

[Abstract](160) [PDF 366KB](3)

Abstract:
By using the synmeby and the qusi-symmetry of the infinitesimal transformation of the transformation group G1 and by imposing restrictions of constraints on the transformation, the Noether's theory of constrained Birkhoffian system has been established. The theory includes the generalized Noether's theorem obtaining the first integrals from the known symmetry and quasi-symmetry and its inverse obtaining the corresponding symmetry and quasi-symmetry from the known first integrals for the systerm.

On the Lie Symmetries of the NonholonomicMechanical Systems

Wu Runheng, Mei Fengxiang

1997, 6(3): 229-235.

[Abstract](159)

Abstract:
The Lie symmetries of nonholonomic mechanical systems are corsidered. Some defmi tions and criteria on the Lie symmetries, and the conservation laws of the systems are given.And some examples to illustrate the application of the results are provided.

Study of Energy Resolved Mass Spectraof DNT Isomers

Deng Lin

1997, 6(3): 236-238.

[Abstract](151)

Abstract:
Energy raolved mass spectra (ERMS) of 2, 3-DNT and 3, 5-DNT isomers was mported. The fragmentation of this pair of DNTisomers was studied by ERMS in electron impact (EI),and their breakdown curves were discussed , These nitraromaic isomers can be characterized according to the differences between their ERMS in MS/MS

Enantioseparation of Several PharmaceuticalRacemates with High PerformanceCapillary electrophoresis

Li Fang, Jin Hui, Dai Rongji, Gu Junling, Fu Ruonong

1997, 6(3): 239-243.

[Abstract](186)

Abstract:
With high performance capillary electrophoresis using -cyclodextrin or its deriveatives as the chiral selectors, five pairs of drug enantiomers were separated, The PH of the back- gmund electrolyte and the chiral selector concentrations were optimized; and the effect of organic modifier on separation of chlorpheniramine enantiomers was also inver

Some Regularities in Cracking Phenomenonof the Earth Crust

Zheng Lianda

1997, 6(3): 244-252.

[Abstract](149)

Abstract:
The cracking phenomenon of the vast underground rock stratum that has been accumulated for long years due to earghquakes is basically similar to the cracking process of the focus of an seism or a rock specimen.

The Course of Time in the Cracking of Earth CrustCaused by Earthquake of Magnitude 8

Zheng Lianda

1997, 6(3): 253-257.

[Abstract](182)

Abstract:
The world,the continent and the large country at all times have similar distribution of intervals between recurrences of the great earthquakes,depending on the earthquake sequence. lt indicates that how the force source of world scale changes with time and space.

Multi-Sensor Intelligent System for On-Line and Real-Time Moneitoring Tool Cutting State in FMS

Xu Chunguang, Wang Xinyi, Xing Jishou, Yang Dayong

1997, 6(3): 258-266.

[Abstract](179)

Abstract:
The principle and the constitution of an intelligent system for on-line and real-time montitoring tool cutting state were discussed and a synthetic sensors schedule combined a new type fluid acoustic emission sensor (AE) with motor current sensor was presented. The parallel communication between control system of machine tools, the monitoring intelligent system,and several decision-making systems for identifying tool cutting state was established It can auto - matically select the sensor way ,monitoring mode and identifying method in machining process- ing so as to build a successful and effective intelligent system for on -line and real-time moni- toring cutting tool states in FMS.

An Elliptical-Beam Reflector Antenna forSatellite Communication System

Liu Gang, Gao Bending, Wang Yue

1997, 6(3): 267-273.

[Abstract](190)

Abstract:
An offset elliptical reflector antenna suitable for satellite application was designed and investigated when it was fed by a rectangular horn partially filled.with a dielectric..The.reflector antenna exhibits high gain, low cross polarization. low sidelines and an elliptical beam. Al- though this study has been carried out in view of possible satellite applications, it is clear that this. antenna. is also suitable for use in radar antennas.

Recovery of Transient Signals in Noise by OptimalThresholding in Wavelet Domain

Mei Wenbo, Shark Lik-Kwan

1997, 6(3): 274-279.

[Abstract](150)

Abstract:
The recpvery of transient signals corrupted by additive white Gaussian noise means of the discrete wavelet transform was studied. An optimum threshold scheme in the discrete wavelet domain-presented, which involved a hypothesis testing for wavelet coef Fcients. This threshold was designed using likelihood ratio, Neyman-Pearson criterion and the minimum mean-squared error. The effectiveness of the proposed optimum threshold was demonstrated by computer simulations of signal recovery in poor signal一to-noise ratio scenarios.

Radar Target Discrimination based on waveletPackets for Reduced data Storage

Jiang Wenli, Tang Baiyu, Ke Youan

1997, 6(3): 280-286.

[Abstract](151)

Abstract:
In order to storage resource of a radar recognition system, schemes for reducing data storage and for correlation discrimination of radar based on wavelet packets were proposed Experiment results at various signal-to-noise ratios were given The given.ability of the reduced data method's validity are supported by experimental results. Using optimal basis can get higher successful recognition rate using rigid wavelet basis.

An Interruptable Lock and Unlock Algorithm

Wu Jianguo, Liu Mingye, Yao Lingzhong, Song Hantao

1997, 6(3): 287-291.

[Abstract](202)

Abstract:
Generally, Lock and Unlock statements are primitives that should be wholly imple- mented,i.e.,the test of lock state and the operation of locking must be executed continuously without being interrupted. Different from nmormal lock operations, the lock and Unlock algorithm Presented in this paper can be interrupted anywhere by other processes The value of the algorithm in the implementation of concurrent control and mutually-exclusive operations was elucidated with one application of the algorithm in a heterogeneous datedbase united system.

Influence of Tire Slip Angle on Adhesion CoefficientCharacteristic of Road Vehicles

Liu Zhaodu, Ding Nenggen

1997, 6(3): 292-298.

[Abstract](242) [PDF 337KB](6)

Abstract:
Tire slip angle has a great influence on peak values of both logitudinal and lateral adhesion coefficients as well as optimal slip ratios. Regression equations based on the experi- mental data from several countries are given to describe their dependencies. The peak value of longitudiinal adhesion coefficient has a linear relationship with tire slip angle, but peak value of lateral has a complicated relationship; the optimal slip ratio of longitudinal has an exponent function relationship, the optimal slip ratio of lateral almost has nothinng to do with tire slipangle.

1997 Vol. 6, No. 3