Table of Content

30 December 2000, Volume 21 Issue 4

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Paper

Design of a Minitype Impulse Radar Transmitter and Antenna

Yue Xin ,Fei Yuanchun

2000, 21(4):  289-292.  doi:10.3969/j.issn.1000-1093.2000.04.001

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Gives the design of a minitype impulse radar transmitter consisting of an ultra-broadband signal generator、omnidirectional broadband antenna and broadband matching networks. The size of transmitter is Φ44mm. The ultra-broadband signal generator chooses a step recovery diode signal- forming circuit, which can generate negative pulses with widths of 0. 6?0. 9ns and amplitudes of — 8V under conditions of low supply voltage and a driving square wave. The broadband antenna adopts, a novel sphere-loading technique and the qdoption of smooth generatrix avoids discontinuity in radius of curvature. Thus it effectively improves impedance characteristic. Theoretical analysis and calculation are performed, by applying the extended moment method. Broadband matching networks bases itself on real frequency technique，which avoids the necessity of designing networks topology in advance and searching for high-rand nonlinearoptimization. The system is of iiigh-resolution，low-cost and is small sized. It can be applied in aiming heads of weapons，smart weapons and earth detecting radars.

Fatigue Reliability Control of Complex Components in the Case of an Integral Aluminum Cylinder Head

1:Shen Guoshan, Liu Wenting;2:Yan Jinglong

2000, 21(4):  293-296.  doi:10.3969/j.issn.1000-1093.2000.04.002

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Reliability study is not only aimed at estimating the reliability life but mainly for controlling the reliability of engineering objects. A method is proposed for the study of fatigue reliability of complex components that is effectively used in the analysis and control on the reliability of integral a- luminum cylinder heads. In order to make use of the wealth of data and information accumulated in the past，based on the fuzzy mathematics，a method is proposed with the help of full scale structure simulation and iailure analysis，for the examination and control of reliability of complex components.

Finite Difference Technique for Heat Conduction in Multi-Layer Gun Barrels

1：School of Materials Science and Engineering, SJTU，200030；2：Department of Materials Science and Engineering, NUST；3：School of Mechanics, NUST

2000, 21(4):  297-300.  doi:10.3969/j.issn.1000-1093.2000.04.003

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finite difference | gun barrel | temperature field

Exterior Ballistic Theory and Computation of Shots

1：Zhou Kedong, Tan Donghan, Xu Cheng；2：Feng Tailin

2000, 21(4):  301-304.  doi:10.3969/j.issn.1000-1093.2000.04.004

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By analyzing and solving the exterior ballistic equations of shots，the paper gives a method for computing the parabolic trajectory, flying velocity curve and rudimental energy curve of shots. Results of computation point to several conclusions. Firstly，the smaller the diameter of the shot, the lower the top of parabolic trajectory and so the shorter the flying distance. Secondly，at the same horizontal 'range, the drops of spots of different diameter are almost the same and can be neglected within 50m range. But when the range is over 50m, the drops will become larger and so the drop difference between shots of different diameters become clearer. And thirdly for the same range the smaller the size of the shot，the lower will be the rudimental flight velocity of the shot，and thus the lower the rudimental energy of the shot.

Performance Analysis of a New Reduced-Dimension SMI Algorithm for Adaptive Arrays

Luo Yi, Gu Hong, Liu Guosui

2000, 21(4):  305-309.  doi:10.3969/j.issn.1000-1093.2000.04.005

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Performance of reduced-dimension adaptive arrays is discussed. It is pointed out that， when covariance matrix of the clutter is known，reduced-dimension adaptive processing can be implemented without any loss in performance compared with that of the full-dimension adaptive processing， provided a specific reduced-dimension transform is applied. When the covariance matrix of the clutter is unknown，reduced-dimension adaptive processing can also be implemented by using a random transform matrix, and its performance can be controlled.

Quartic Convolution Interpolation and Its Application in Digital Maps

Han Zhigang, Sun Longhe, Li Linsen,Li Keji

2000, 21(4):  310-313.  doi:10.3969/j.issn.1000-1093.2000.04.006

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Quartic convolution interpolation (QCI) is a new method in interpolation technology. It possesses a number of desirable features that make it useful in digital mapping，numerical control and image processing.丄 he method can be performed efficiently on a digital computer. Taking cubic splines (CS) and cubic convolution interpolation into consideration, with a new interpolation kernel and appropriate boundary conditions，the method achieves third-order precision and continuous second derivative. It requires less computation and storage than that is needed in cubic splines. A one-dimensional interpolation function is presented in this paper. The interpolation functions of two dimension and fourth-order are applied to this algorithm. The paper concludes with examples of digital maps to illustrate the efficacy of this method，in terms of its performance of computation, precision and reduction in storage.

Sensitivity Electrode Structure of Capacitive Sensors

1：Li GuoLin, Zhang Xu, Zhao Xi；2：Shi Jusheng

2000, 21(4):  314-317.  doi:10.3969/j.issn.1000-1093.2000.04.007

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The influence of electrode structure on the sensitivity of proximity capacitive sensors is studied. The paper presents a kind of capacitive sensor with shielded elecrtode by summing up the relationship between sensitivity and structure of several types of proximity capacitive sensors. The equivalent capacitance is studied before and after a target draws near. Formulation of sensitivity and theoretical analysis is given. Through a series of tests it is verified that the sensor has higher sensitivity and longer detecting range.

Electro Optical Two Stage Stabilization System Control Technique of Channel Blending

Ji Ming

2000, 21(4):  318-321.  doi:10.3969/j.issn.1000-1093.2000.04.008

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The technique of combined coarse/fine stabilization of the line-of-sight is used in some type of products at present. In this way, two inertia stabilized platforms are overlapped, of which the control channels are independent of each other，so that the system cost，volume and weight are greatly increased. A new scheme is put forward in this paper in which the control channels are blended so as to form a coarse/fine loop complex control. As a result of simulation and comparison，the new scheme is seen to possess advantage in its the cost, volume, performance and accuracy, as has been verified by a prototype system.

The Searching Accuracy of Genetic Algorithms with Sharing

Zou Yanming, Ke Youan

2000, 21(4):  322-326.  doi:10.3969/j.issn.1000-1093.2000.04.009

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Sharing methods give genetic algorithms the ability to locate several extremities of an objective function through only a single search. This paper studies the searching accuracy of genetic algorithms with sharing. According to a model of sharing GA，the conclusion is pointed out that the accuracy of searching results sometimes cannot be made arbitrarily high even when the number of gener- ations become infinite. For the population that evolves finite generations, discussions are made about the influence of the shape of share functions and objective functions on the accuracy of the searching results. Based on this, some design rules are proposed which will benefit the accuracy of sharing methods.

Application of Modulation Transfer Function (MTF) in the Formulation of Optical Tolerances

Jiang Huilin, Yang Huamin, Ren Tao ,Li Gongde

2000, 21(4):  327-330.  doi:10.3969/j.issn.1000-1093.2000.04.010

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It is suitable for systems with large aberrations to formulate their optical tolerances using the MTF. The differentiation of MTF with respect to structural parameters can reflect the respective effects of tolerances to the image quality. The relationship between the MTF and the manufacturing errors is generally nonlinear. A method is devised to handle the nonlinearity problem. I he linear expression obtained can be used in deriving the tolerances. In mass production, manufacturing errors obey the law of normal distribution. I he MTF errors also approximately obey the normal distribution. The relationship between the MTF variance and manufacturing errors’ variance in optical system is given. An example of lens products in practical production is given, reflecting appropriateness of the given theory and method.

Displacement Measurement with Nonsymmetrical Double Gratings

Lu haibao, Gao Juliang, Su Shaojing,Luo Wusheng,Yang Huayong

2000, 21(4):  331-333.  doi:10.3969/j.issn.1000-1093.2000.04.011

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The basic principle and characteristics of displacement measurement with nonsymmetrical double gratings (DMNG) are briefly described. DMNG is proved with the theory of Doppler effect and some experimental study is conducted. In the experimental study ,various experimental phenomena are analyzed. The reasons why the Moire fringe is formed are proposed. Effects leading to the Moire fringe are discussed when tlie optical configurations such as the angle of incidence and position of the two gratings are changed. Then the factors affecting the Moire fringe contrast and methods of improving the fringe contrast are analyzed.

Shock Effects from the Dispenser on the Aerodynamic Characteristics of Submunitions

Lin Jingming ,An Fuxing, Yu Debin

2000, 21(4):  334-337.  doi:10.3969/j.issn.1000-1093.2000.04.012

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Presents a numerical simulation of an inviscid supersonic flow over a multi-body configuration of a dispenser with submunitions during dispense，using the overlapDinp grid technique. Euler equations are solved with the employment of NND scheme. The present numerical results show the aerodynamic characteristics of submunitions when they sweep in the proximity of the dispenser.

Application of Diffusion Processes in Simulation

Pan Gaotian, Guo Qisheng, Xie Zhihong,Hu Jiayi

2000, 21(4):  338-342.  doi:10.3969/j.issn.1000-1093.2000.04.013

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Many physical phenomena and actual systems can either be well approsimated by or reasonably modeled as diffusion processes. How to simulate processes of diffusion is a proposition awaiting detailed study. This paper gives a likelihood function method using the property of Markov and transition probability density, based on the statistical inference principle. It discusses not only the differentiation of diffusion processes and estimation of parameters but also checks the model and simula- tion arithmetic. It has its importance in enhancing the speed and reliability analysis of simulation.

On the Optimal Strategy in Fault Isolation Making Use of the Genetic Programming Algorithm

1:Wu Zhuang;2:He Xingui

2000, 21(4):  343-345.  doi:10.3969/j.issn.1000-1093.2000.04.014

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Based on the functional block diagram and the signal flow of an equipment ,its fault information matrix is structured, and a genetic programming algorithm (GPA) is used for finding the best strategy to its fault isolation, which is made up of some ordered, test points. It can be used to isolate the failed component with the fewest test points and the least time.

Micro Ultrasonic EDM of Deep, Small Holes in Titanium Alloys

Wang Zhenlong, Chi Guanxin ,Di Shichun ,Zhao Wangsheng

2000, 21(4):  346-349.  doi:10.3969/j.issn.1000-1093.2000.04.015

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Analyzes key problems in the machining of deep, small holes in titanium alloys. The mechanism of action of ultrasonic vibration on deep and small hole EDM is studied. Based on this，a four-axes linkage EDM machine tool which combines ultrasonic machining and micro-EDM is developed. Using this equipment holes with diameters less than Φ0. 2mm and having depth/diameter ratio higher than 15 can successfully be machined.

Modelling of Microstructure for Castings of Aluminum Alloys

Xiong Wei ,Jing Tao

2000, 21(4):  350-352.  doi:10.3969/j.issn.1000-1093.2000.04.016

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A Probabilistic method has been successfully used to simulate the microstructure of aluminum alloy castings. T shaped aluminum alloy castings have been selected to test the simulation model. The experiment indicates that the simulation results are in good accord with suits.

A Wind Tunnel Study of an Elevated Sustained Elliptic Lamp and Fittings

Zhao Lanshui, Song Xiangeng

2000, 21(4):  353-356.  doi:10.3969/j.issn.1000-1093.2000.04.017

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Presents an experimental method to simulate a pole sustained elliptic lamp in a low speed wind tunnel with a scale of 1:8. The laws of change of forces acting on the lamp and its fitting from winds at various directions are surveyed and analysed. The relative position of the maximum force and the structural factors are found. It provides aerodynamic data for the strength evaluation of similar lamps and fittings.

Experimental Techniques and Analysis

Influence of HMX Particle Size and Gradation on the Shock Sensitivity and Output of a PBX Explosive

Liu Yucun, Wang Zuoshan, Chai Tao, Zhang Jinglin

2000, 21(4):  357-360.  doi:10.3969/j.issn.1000-1093.2000.04.018

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SSGT configuration and procedure have been used to investigate the influence of particle size and gradation of the base explosive HMX on the shock sensitivity and output of a PBX explosive. The particle size of HMX under investigation varies from 1μm to 150μm and the densities of samples adopted are taken at 90% and 95. 5% in TMD. The trend of influence of particle size and gradation of the base explosive upon the shock sensitivity and output of the composition explosive have been revealed. These results are significant in the choice of particle size of base explosives for booster explosives and other explosive compositions.

The Correction of Image Photographed by CCD Image Sensors

Zhang Pizhuang, Lu Hongnian

2000, 21(4):  361-364.  doi:10.3969/j.issn.1000-1093.2000.04.019

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In a digital radiograph (DR) inspection system based on area CCD sensors, the inspection precision is limited severely by the signal-noise ratio of CCD sensor chips. In order to upgrade the SNR of CCD sensors，the characteristics of noise caused by CCD camera is studied. It is discovered that dark current and the non-uniformity of the response to light in different pixels of CCD sensors are the two important factors that affect the quality of images. Relevant correction algorithms are proposed. Finally, an actual image is corrected.

Research Notes

Quasi-Static Compression of High-Energy Solid Propellants and Their Combustion

1:Zhang Taihua, Bai Yilong;2:Wang Shiying, Liu Peide

2000, 21(4):  365-367.  doi:10.3969/j.issn.1000-1093.2000.04.020

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Quasi-static compression tests at T=200C and T = — 50°C were conducted on the NEPE propellants using Instron-4505 material test system, and microstructural variations were observed under a scanning electron microscope (SEM) while the damage characterized with density measure- ments. The effects of damage on combustion were then examined by thermal decomoosition and closed-bomb tests. The results indicate that the microstructural changes and recrystallizations in the propellants are the chief factors affecting their combustion properties.

495Q Methanol (M85) Engine Development and Research

1:Cao Mingrang;2:Sun Liwei

2000, 21(4):  368-371.  doi:10.3969/j.issn.1000-1093.2000.04.021

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Introduces in detail some phases of the process of development of a methanol engine. The cold start ,fuel gas preheating ,fuel pump system modification ,ignition characteristics and compression ratio of the methanol engine are studied through extensive experiments and a methanol engine is developed. Stage tests in laboratory and actual road tests of experimental vehicular engine through prolonged period of time show that the performances regarding power，economy and exhaust analysis of the methanol engine all surpass those of the corresponding gasoline engine.

Use of Dielectric Combination Measurement in Process Analysis

Ren Qian ,Bai Xiangji, Huang Youzhi

2000, 21(4):  372-374.  doi:10.3969/j.issn.1000-1093.2000.04.022

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A dielectric measurement system used to analyze the composition of mixtures during processing is discussed. The method, in which the dielectric constant is used as the chief parameter and insulance as the auxiliary parameter，is based on the difference in microstructures of materials and the factor oi dielectric loss. Many experiments about NaCl solutions have been conducted, and primary math models established. It is seen that the system can be used in the field of on-line analysis.

Feature Modelling of Stamped Parts Based on the Object-Oriented Approach

1：Tang Dunbing, Zheng Li；2：Li Dongbo， Zhang Shiqi

2000, 21(4):  375-377.  doi:10.3969/j.issn.1000-1093.2000.04.023

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Based on an object oriented approach, the taxonomy and relationship of features of stamped parts are described，and other feature models established，embodying integrated semantic information. The modelling technique is not only favorable in the designing of stamped parts，but also convenient for the evaluation of manufacturability of stamped parts. Furthermore, the feature model can furnish full information in the design of succeeding stamping processes.