JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY

Zhu Tongjiang

1995, 4(2): 99-105.

[Abstract](156)

Abstract:
Let and denote respectively the functionswhere λ≥1, The author discusses the similarity transformation of the regularizing functionals of these functions and the similar property of their Fourier transformation.

On the Coefficients of Polynomials with Positive Real Part in the Unit Disk

Shen Dawei

1995, 4(2): 106-110.

[Abstract](160)

Abstract:
Let Q be the class of real coefficient polynomials of degree 2 with positive real part in the unit disk and constant term equal to 1. aam coefficient region of polynomials in Q is found and some sharp coefficient estimates for the polynomials with positive real part in the unit disk are established in this paper.

An Upper Bound for Total Domination Number

Sun Liang

1995, 4(2): 111-113.

[Abstract](321) [PDF 203KB](28)

Abstract:
Let G=(V, E) be a simple graph without an isolate. A subset T of V is a total dominating set of G if for any there exists at least one vertex such that .The total domination number γ1(G) of G is the minimum order of a total dominating set of G. This paper proves that if G is a connected graph with n≥3 vertices and minimum degree at least two.

Chromatically Equivalent Graphs with P(G, λ) = (λ- λ₁)(λ-λ₂)λ￣(n+1)

Han Botang

1995, 4(2): 115-122.

[Abstract](221)

Abstract:
The author finds out all of the graphs with the same chromatic polynomial and proves some relevant theorems and corollaries.

Poisson's Theory of the Chaplygin's Equations

Mei Fengxiang, Shi Rongchang, Zhang Yongfa

1995, 4(2): 123-129.

[Abstract](182)

Abstract:
Puts forward an algebraic structure of the Chaplygin's equations of nonholonomic systems, establish the Poisson's theory of the integration equations and gives an example for illustrating the application of the result.

On the Existence of Periodic Solutions for n-Dimensional Li nard Equations with Delay

Dong Qinxi, Huang xiankai, Qin Xiaomei

1995, 4(2): 130-134.

[Abstract](311) [PDF 283KB](5)

Abstract:
The present article considers the existence of T-periodic solutions for the following Lienard equation with delay.where h≥0 is a constant, (Rn, R), (Rn, R), (R, Rn), p(t+T)=p(t) for a constant T>0 and . By use of V-function and coincidence degree. The result proposed by Ge Weigao is extended to the case of delay-differential system in the papee. One feature of our result is that the delay has a notable impact on the existence of periodic soultion.

Analytic Expression of Meso-Criterion on Dynamic Fracture

Fan Tianyou, Li Chunsu

1995, 4(2): 135-139.

[Abstract](146)

Abstract:
This study presents a meso-criterion of dynamic fracture, on the basis of stress in integral form In such way the difficulty due to the singularity of stress distribution at the crack tip is overcome. A micro-parameter, the atom radius, is introduced into the criterion.Meanwhile a characteristic time concept is taken into account for describing the inertia effect of material. The criterion reveals The criterion reveals the effects of loading rate, defect and sample geometry,material constants including the micro-structure parameter.

The Effect of the Atmosphere on the Formation of Fullerene

Tang Guangshi, Zhang Hengjian, Cao Chuanbao, Li Rongzhi, Zhu Hesun

1995, 4(2): 141-147.

[Abstract](166)

Abstract:
The effects of He, Ar and N2, as the working gas, on the formation of Fullerenes were studied respectively. The experimental results indicated that the different inert gases greatly affect both the productivity and the composition of Fullerenes and for the same gas the different pressures also affect the productivity. It was also found that no Fullerenes can be obtained without a working gas. It indicates that the gas of a difinite pressure may be necessary to the formation of Fullerenes. A new possible mechanism of the Fullerenes formation was suggested.

Capillary Zone Electrophoretic Separation of Proteins in Polymer Coated Capillaries

Liu Yu, Gu Junling, Fu Ruonong

1995, 4(2): 148-155.

[Abstract](165)

Abstract:
Fused-silica capillaries used in capillary zone electrophoresis were statically coated with γ- glycidoxypropyltrimethoxysilane and epoxy polymer in order to suppress wall adsorption in the separation of proteins. It has been shown that a significant decrease in adsorption was obtained and eletroosmotic flow was the diminished in the pH range 3-5. However with higher pH values, appreciable peak deformation and decreases in the resolving power were observed. Under pH 5, the epoxy polymer coating was shown to be quite stable and exhibited reproducible separations from run-to-run and day-to-day over a period of time.

Tomographic Principle of Multiconjugate Correction in Adaptive Optics

Yan Jixiang, Yu Xin, Zhao Dazun, Zhou Renzhong

1995, 4(2): 156-159.

[Abstract](186)

Abstract:
A wavefront sensing and correction correction is proposed that would allow the field of view (FOV) of an adaptive optics spstem to be increased in size by a factor of several tens. This concept is based on the idea of placing multiple deformable mirrors (DMs) at locations that are conjugate to corresponding. layers of atmospheric turbulence. In order to control properly each DM, a tomographic method for determining the phase distortion contributed by each atmospheric layer has been developed and used in dealing with the circumstance of two layers.

Prediction and Reduction of StructureBorne Noise in Vehicle

Wang Yanping, Zheng Muqiao

1995, 4(2): 160-166.

[Abstract](188)

Abstract:
The structure and the acoustic medium of a passenger vehicle are modeled using the finite element method(FEM), and the interior noise is studied the help of the modal synthesis method (MSM). Sound pressure level (Lp) of the noise is calculated in several conditions of the models, and has good agreements with its test results. The MSM am be consequently used for predicting the vehicle interior noise in dssign stage so that the structure may be optimized for the Purpose of the most reduction of noise.

An Experimental Study of Cutting Performance of Ti(C, N) Based Cermet Cutting Tool

Pang Siqin, Yu Qixun

1995, 4(2): 168-173.

[Abstract](236) [PDF 348KB](7)

Abstract:
Through systematic cutting experiments, characteristics of the cutting performance of Ti(C, N) based cermets is identified. The experiments were designed to study their resistance,toughness, cutting force, tool-chip friction coefficient and machining quality by comparing them with those of WC based cemented carbides. The cutting data and the regressed empirical formulae would be useful to promote proper application of cermet cutting tool materials.

Dynamic Analysis of Floating-Ring Gas Bearings

Wang Yunfei, Mao Qiande

1995, 4(2): 174-181.

[Abstract](147)

Abstract:
The dynamic performances of floating-ring bearing with hydrodynamic/hydrostatic gas lubrication are studied theoretically and some calculated charts of dynamic coefficients are given in the paper. The method of stability analysis is also presented and it is proved that the high speed stability of such bearings is better than other types of gas bearings.

The Key Techniques of VHDL Parser's Automatic Generation

Niu Zhendong, Song Hantao, Liu Mingye

1995, 4(2): 182-187.

[Abstract](264)

Abstract:
VHDL and its supporting environment are active domain in the field of logic design.In the paper the design principle and some key techniques to solve the problems on the implementation of the VHDL parser are introduced. According to the methods discussed in the paper, the VHDL parser based on VHDL IEEE 1076 standard version is implemented and a series of strict tests are done. This VHDL parser is front-end tool of the VHDL high level synthesis and mixed level simulation system developed by the Research Center of ASIC of BIT.

Automatic Generation of Schematic Diagrams in High-Level Synthesis

Zuo Jingyan, Liu Mingye

1995, 4(2): 188-197.

[Abstract](202)

Abstract:
The automatic schematic diagram generator of BIT (ASG-BIT) discussed here is a subsystem of the VHDL high-level synthesis and mixed-level simulation system (HLS-BIT). It can abstract netlists from the result of logic synthesis and generates functionally readable and aesthetically pleasing diagrams within reasonable execution time. The partitioning, placement and routing of schematic diagram are discussed .and some results including several diagrams generated by ASG-BIT system are presented in the finale of this paper.

The Outer-Performance Distortion of the Suspension Shock Absorber and Its Critical Velocity

Yu Defu, Fu Zhao

1995, 4(2): 198-206.

[Abstract](181)

Abstract:
On the basis of analysing the outer performance degradation of shock absorber on suspenson and from the relationship between outer and inner performances of the shock absorber, an internal relationship between the structure design and degradation of the shock absorber is discussed in the paper. From dynamic property, analysed the dynamic cause for degradation, the paper proposes a technical method of improving outer performance and a concept of critical velocity, and discusses what effects the critical velocity and the outer performance mance degradation has.

A New Simulation Method for 3D Propellant Grain Burn Analysis of Solid Rocket Motor

Fang Shuzhou, Hu Kexian, Zhang Ping

1995, 4(2): 207-214.

[Abstract](214)

Abstract:
Describes a new computer program (Regress-3D) to simulate the regression of complex 3D grain cavity and calculate the burning surface area. It has a large region of applicability in solid rocket motor design and has made new improvements compared with other available codes. User can easily and rapidly build his initial grain shapes and then obtain geometric information of his design. Considering with the calclulting results, redesigning can be performed as desire until reaching at the satisfied result. Advantages and disadvantages of this method are also discussed.

Launching and Travelling Dynamic Analysis of Rocket Launcher System ──The Study of a Unified Model

Wang Chunfeng, Song Tinglun

1995, 4(2): 215-221.

[Abstract](205)

Abstract:
A unified model which is used to study the launching and travelling dynamic properties of a rlcket/launcher system is established. In this model, the rocket, the launcher,and the launching vehicle are considered as an interacting dynamic system in order to study the dynamic interaction between the various parts of the system and the optimal parameter matching among the above mentioned parts. The following random factors are taken into account in this paper. road surface excitation. rocket mass center misalignment, thrust misalignment, dynamic of the rocket, and the cross wind. Based on this unified model, a computer simulation software is developed, some simulation work has been carried out, and certain beneficial results have been achieved.

1995 Vol. 4, No. 2