JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY

Advances in the Theory of Conjugation for Reflecting Prisms in China

Lian Tongshu

1992, 1(1): 1-12.

[Abstract](586) [PDF 523KB](18)

Abstract:
The achievements made in China in the field of the theory of conjugation for reflecting prisms are outlined which mainly includes 6 theorems, 2 corollaries, over 30 formulae, 4 matric operators, 20 characteristic parameters, a new principle for dassification, and a new system of graphical tabulation for reflecting prisms. As an approach to developing the theory, an imaginary physical model called 'rigid body's kinematics model' has been creatively initiated to simulate the real physical phenomena of both image formation and image motion for reflecting prisms. Such a method of treatment has been successfully making the evolving theory more complete, more systematic, more generalized, and unique as well.

Application of Pyrolysis-Gas Chromatography in Explosive and Propellant Analysis

Liu Huwei, Fu Ruonong

1992, 1(1): 13-18.

[Abstract](213)

Abstract:
Applications of pyrolysis-gas chromatography and pyrolysis capillary gas chromatography in explosive and propellant analysis are reviewed, including the identification of explosives and propel- lants, the investigation of the thermal decomposition of nitrocellulose (NC), cyclotetramethylene tetranitramine (HMX)and cyclotrimethylene trinitramine (RDX), and the study of the wear- reducing mechanism of polyurethane additive in propellant gain.

A Study on Gradient Refractive Index Polymer Rods——Mechanism of Diffusion-Copolymerization of Diallyl Phthalate-Methyl Methacrylate

Ge Bingheng, Zhou Xinwo

1992, 1(1): 19-23.

[Abstract](147)

Abstract:
The gel rod, partially polymerized DAP (diallyl phthalate), is immersed in MMA (methyl methacrylate) solution, followed by heat-treatment to yield the GRIN (gradient ref- ractive index) rod. A three-stage mechanism of diffusion-copolymerization process is propo- sed, giving an interpretation to the formation of cracks that are brought about in large-dia- meter GRIN rods.

Study of Beam Scan with Variable Linear Polarisation Directions of Antenna Arrays Using MMIC T/R Modules

Li Zhen, Deng Ciping

1992, 1(1): 24-30.

[Abstract](234) [PDF 333KB](2)

Abstract:
The beam scan with variable linear polarization directions of antenna arrays using MM/C transmit-receive (T/R) modules is explored. It is shown that the beam scan and the polarizations of electric fields can be controlled simultaneously if the forms of module arrangement are chosen properly and the amplitudes and the phases of array excitation are determined by the method presented in this article. Moreover, the calculations of the amplitudes and the phases of array excitation are simplified greatly while using the bounded conditions properly, and the desired beam sweep rate is achieved.

Holographic Goggles Optical System

Chen Huangming

1992, 1(1): 31-34.

[Abstract](150)

Abstract:
Based on the holographic theory, a pair of reflective holographic lenses have been utilized with an aim to improve the optical properties of night vision goggles. The aberration distribution of the holographic lens has been confirmed by experiments and compensated by a conventional symmetrical spherical system. Resulting data of the whole optical system are given.

Expert System for the Design of Single Speed Gear Boxes

Huang Xinyuan, Wan Yaoqing, Xiang Hong, Wang Wenqing

1992, 1(1): 35-41.

[Abstract](189)

Abstract:
Based on the characteristic peculiarities of mechanical design expert systems (MDES), the design process pf gear box and its components is introduced and the gear box design expert systems (GBES)is established. GBES employs the methods of knowledge representation to indicate the knowledge-unit-rule-process, table-vector-process. By taking the advantage of knowledge unit's indicator, it can make the units of knowledge base to to combine to form a whole in the feature of trees and nets so that it can give deduction conveniently. The knowledge base of GBES is organized in hierarchy, which provides the efficient managerial systems of knowledge base. It makes the knowledge base convenient greatly for establishing and using. The assistant modules of GBES are written in FORTRAN and the part of expert systems is written in LISP. It explains the I/O among each module and the forms of independent application. The GBES systems have been put into preliminary, use in practice.

A New Approach to Improve the Matched Responses of High-Speed PWM Mode Electropneumatic Actuators

Wang Shulan, Yu Yang

1992, 1(1): 42-49.

[Abstract](154)

Abstract:
A new approach to improve the matched responses of high-speed PWM mode electro pneumatic actuators is introduced. By modifying the control signal, the matched responses are highly improved. For testing this new approach, an instrument is designed and developed. And the effectiveness of the approch is proved by experiment. The block diagram of the instrument is also presented.

A Kind of PWM Pneumatic Servo Control System——Modulation Methods and Dynamic Responses

Yao Xiaoxian, Chen Hanchao

1992, 1(1): 50-58.

[Abstract](237) [PDF 693KB](3)

Abstract:
Vibrations or dither's are features of the PWM servo control system in their steady outputs. On the grounds of analyses and experiments of a PWM pneumatic servo control system, the paper puts forward four varieties of PWM modulation methods, and concludes on the relationship between dithers and the different methods, and then discusses the influence of friction to the dithers. Results from experiments regarding the dynamic and static responses on the given system support the theories presented.

An Experimental Study on Microcomputer Control of Pump Controlled Motor Systems

Peng Xiudong, Liu Zhigang, Jin Zhili, Hu Youde

1992, 1(1): 59-65.

[Abstract](144) [PDF 361KB](2)

Abstract:
Pump controlled motor electrohydraulic servo systems are much used in circumstances where high power drive is needed. This kind of system has the advantage of energy-saving. But, it also has some defects that have to be improved. Microcomputer control of a pump controlled motor electrohydraulic servo system is studied. A PID controller is first adopted on the closed loop control system, and experimental results are obtained. Then, a model reference adaptive controller is designed and realised on the same system applying a single board microcomputer. Experimental results show that the dynamic properties of the adaptive control system is much better than those of the PID system under different inertia load conditions.

Plasma Surface Modification of Kevlar Fibers

He Hong, Li Rongzhi, Zhu Hesun, Sun Mujin, Hu Baorong

1992, 1(1): 66-74.

[Abstract](184)

Abstract:
Cold plasma techniques were used to treat the surface of Kevlar-49 fibers. The dynamic parameters of wetting, contact-angles and surface energy of the fiber before and alter the treatment were compared to see the changes in the wetting property. ESCA and electron spin resonance were utilized to examine the chemical composition and the attached free radicals of the fiber surface. The results, together with changes in the magnitude of the contact-angle and the number of free radicals with time after the plasma treatment do not show any ageing effect. Single filament test revealed that the tensile strength was not impaired but even improved somewhat after the plasma treatment. The experiment shows that the interlaminar shear strength of Kevlar fiber reinforced epoxy resin compo- site is increased for more than 60％% after the treatment.

1992 Vol. 1, No. 1