JOURNAL OF BEIJING INSTITUTE OF TECHNOLOGY

Impact Responses of the Carbon Fiber Fabric Reinforced Composites

JIANG Chun-lan, LI-Ming, ZHANG Qing-ming, MA Xiao-qing

2000, 9(3): 225-230.

[Abstract](179)

Abstract:
To study the response characteristics of the carbon fiber fabric reinforced composites under impact loading, one dimensional strain impact test, multi gauge technique and Lagrange analysis method are used. The decaying rule of the stress σ , strain ε , strain rate ε^˙and density ρ with time and space is obtained. By the theory of dynamics, the impact response characteristics of the material is analyzed and discussed.

Computations of Cross-Link Forces and Vibrations for the Test Bed of the Full Channel Gas

LAO Da-zhong, ZHANG Ping

2000, 9(3): 231-236.

[Abstract](188)

Abstract:
In order to control the cross-link forces and the vibration frequencies of the test bed of the full channel gas within the allowable ranges, the analyses of forces and deformation of the test bed was done, for the variously restrained elastic movable frame and the rigid one, the vi-bration frequencies were computed respectively by means of the methods of mechanics of materi-als, elasticity and vibration mechanics, the cross link forces and the vibration frequencies of the test bed were tested. The results of theoretical computation comparatively approach the experimental results. The computational methods could be used to availably estimate the design parameters relevant to the test bed of the full channel gas.

Experimental Research on Amplitude Change of Blasting Seismic Wave with Topography

ZHANG Qi, BAI Chun-hua, LIU Qing-ming ZHANG Yu-ming, ZHANG Yu-ming, GUO Yan-yi, WANG Zhong-qi

2000, 9(3): 237-242.

[Abstract](293)

Abstract:
The propagation characteristics of the amplitude of the blasting seismic wave under the conditions of various topographies are approached by means of experiments. Some factors affecting the effects of quake insulation groove, such as the size, the depth and the position of the quake insulation groove, are studied. The amplitudes of the blasting seismic waves under the conditions of the different sizes of the quake insulation groove are measured. According to the experiments, the effects of the quake insulation groove are related to the position, the distance, the energy of the explosion source and the size of the quake insulation groove itself. The farther it is from the explosion source, the smaller the energy is. The lower its position is and the larger its size is, the more remarkable the effects of the quake insulation groove are.

Experimental Study on Damage Properties of Rocks Under Dynamic Loading

YANG Jun, GAO Wen-xue, JIN Qian-kun

2000, 9(3): 243-248.

[Abstract](205)

Abstract:
The damage properties of two types of rocks under dynamic loading are studied. The shock induced experiments are done using planar impact technique on the one-stage light gas gun, and the ultrasonic tests on the damaged rocks have been made by use of the ultrasonic pulse-transmission method. The shock induced damage of rock is related to the shock speed and the attenuation coefficient of sonic wave, and the latter reflects the damage degree in rock fairly well. The attenuation coefficient α can be used as main damage parameter for constructing damage model of rock under dynamic loading.

Characterization Method of Explosion Seismic Wave

LIN Da-chao, BAI Chun-hua, ZHANG Qi, WANG Zhong-qi

2000, 9(3): 249-254.

[Abstract](182)

Abstract:
A new characterization method of explosion seismic wave is suggested on the basis of the analysis of experimental measured results. The seismic wave function is resolved into amplitude modulation part and random one. For the latter, the fractal dimension and the relevant characterization parameters are yielded by using the Weirstrass Mandelbrot (W-M) fractal function. In contrast with conventional statistical parameters, the new set of parameters is independent of the chosen time length scales and the measuring instruments. A modeling example is presented which shows that the theoretical results are in agreement with the experimental results.

Dynamic Stress Intensity Factor and Scattering of SH Wave by Circle Canyon and Crack

REN Yun-yan, HAN Feng, SHI Shou-xia

2000, 9(3): 255-261.

[Abstract](210) [PDF 232KB](3)

Abstract:
The dynamic stress intensity factor (DSIF) and the scattering of SH wave by circle canyon and crack are studied with Green's function. In order to solve the problem, a suitable Green's function is constructed first, which is the solution of displacement fields for elastic half space with circle canyon under output plane harmonic line loading at horizontal surface. Then the integral equation for determining the unknown forces in the problem can be changed into the algebraic one and solved numerically so that crack DSIF can be determined. Last when the medium parameters are altered, the influence on the crack DSIF is discussed partially with the displacement between circle canyon and crack.

Purification of Ultrafine Diamond Synthesized by Detonation

TONG Yi, MA Feng, YUN Shou-rong, HUANG Feng-lei

2000, 9(3): 262-266.

[Abstract](230)

Abstract:
Ultrafine diamond (UFD) is produced at high pressure and high temperature generated by explosive detonation. We manage to search for a new technology to purify the UFD by using potassium permanganate and concentrated sulfuric acid as oxidant. The experiment results show that, compared with others, the purifying effect by this technology is satisfactory and is a more efficient, cheaper, and safer purification technology with less pollution and less investment. It can be put into commercial use. The related principle of the technology is discussed. It is believed that the atomic state oxygen produced during the reaction mechanism is an active substances which would react with the graphite——the main impurity existing in the detonation soot, and the reaction temperature is the key factor in the process.

New Resolution to Coupling Loss Factor of Beam Plate Structure

LIU Jing-quan, YAO De-yuan

2000, 9(3): 267-272.

[Abstract](248)

Abstract:
The transmission of transverse vibrational energy of a vertically rigid beam plate coupled structure is analyzed to get the theoretical results of coupling loss factor(CLF), a very important parameter in statistical energy analysis(SEA). The modal analysis method is used to discuss the vibration energy of the typical model, as well as the power flow between the two subsystems. Furthermore, the resolution to the coupling loss factor is also derived and compared with the measured values. The analytical results of the coupling loss factor agree with the measured ones fully, this new resolution is significant for the application of SEA.

Cluster Warhead Dispersing Technique and Its Interior Ballistic Calculation

TAN Da-cheng, YUAN Zeng-feng

2000, 9(3): 273-277.

[Abstract](263)

Abstract:
Cluster warhead dispersing technique is analyzed with gas dynamic theory. It is seen that the front cover opening and two stage dispersing system is suitable for guided sub missiles whose number is not so large. The interior ballistic performances of this system are calculated with numerical calculation method. The performances such as the pressure in the pressure chambers and the velocity of the sub missiles are obtained in curve form.

Simulation Research on Structure Changing Control over the Follow Up System of the Smart Mine

LI Jie, WANG Lin, MENG Jia-you, LI Shi-yi

2000, 9(3): 278-282.

[Abstract](191)

Abstract:
By analyzing the target's motion pattern, in terms of the requirement for the performance indexes of the follow up system, the structure changing control and time optimal theory is proposed. The system's control scheme from three different aspects(the dynamic response simulation, compound control simulation and dynamic tracking simulation) is also studied. And all the results proved the feasibility of the synthetical utilization of the open loop control, speed decreased control and position closed loop control.

Bayes Estimation of Parameter for the Safety Component Failure Model of the Safe Arming System of Missile

CHEN Fang, GAO Pei-wang, MA Xiao-qing

2000, 9(3): 283-286.

[Abstract](107)

Abstract:
A Bayesian method is used to evaluate the component safety failure model parameter of the safe arming system of an air faced missile in flight. It was proved that Bayes estimation of the model parameter is coincident with the physical explanation of the prior probability density distribution of the random parameter.

Modeling Technology in Finite Element Analysis of Electrostatic Proximity Fuze Problem

LI Yin-lin, SHI Ju-sheng

2000, 9(3): 286-290.

[Abstract](178)

Abstract:
In order to analyze the electrostatic field concerned with electrostatic proximity fuze problem using the available finite analysis software package, the technology to model the problem with a scale reduction object and boundary was presented. The boundary is determined by the maximum distance the sensor can detect. The object model is obtained by multiplying the terms in Poisson's equation with a scale reduction factor and the real value can be reconstructed with the same reverse process after software calculation. Using the finite element analysis program, the simulation value is close to the theoretical value with a little error. The boundary determination and scale reduction method is suitable to modeling the irregular electrostatic field around air targets, such as airplane, missile and so on, which is based on commonly used personal computer (PC). The technology reduces the calculation and storage cost greatly.

Distributing Characteristics of the Charge on the Bomb Body with Capacitance Fuze

DENG Jia-hao, ZHAN Yi, SHI Ju-sheng

2000, 9(3): 291-285.

[Abstract](195)

Abstract:
For establishing the equation of the capacitive target detection accurately, the distributing characteristics of the charges on the bomb body with capacitance fuze were explored. Continuous charges were analyzed dispersively. Based on the Coulomb's law, the dynamic equilibrium equations of the inducing charges on the bomb body were set up. For the four cases ofd₀/L(the ratio between the electrode distance and the bomb length), the curves of the charge's distribution were given. It was concluded that: ① the charge density decreases steadily from the end near the frontal electrode to the bomb tail; ② the declining rate of the density is governed byd₀/L, the larger the value ofd₀/L,the higher the declining rate, and vice versa.

Variable Structure Proportional Navigation for Homing Missile

SONG Jian-mei, ZHANG Tian-qiao

2000, 9(3): 296-301.

[Abstract](232)

Abstract:
The purpose of this paper is to design control loop and guidance loop for the homing missile, to prove that the modified variable structure proportional navigation (VSPN) can be used in passive homing guidance system, and to compare the VSPN with the proportional navigation (PN). Angular rate and linear acceleration are fed back to improve the stability and robust of autopilot, VSPN and PN are compared in mathematics simulation of homing missile in attacking tanks and helicopters. The damp and the stability of the missile body are increased. The VSPN cuts down the overload of guidance phase dramatically, makes the ballistic trajectory straighter than PN and leads to smaller missdistance. The VSPN can be used for passive homing guidance system, and is especially suitable for attacking helicopter.

Estimation of IFOV of Rosette Scan System

GUO Ying-hui, QI Zai-kang

2000, 9(3): 302-306.

[Abstract](205)

Abstract:
The methods of estimating the minimum allowed value of IFOV (instantaneous field of view) of the detector in a rosette scan system are investigated. The common method for the estimation of IFOV is described. A new method which uses the maximum distance between two neighboring petals as the estimated value of IFOV is developed and a comparison between the common method and the new method is given. It is concluded that the minimum allowed value of IFOV of rosette scanning is over estimated by the common method while this value can be calculated accurately with the new method.

Measurement of Angular and Linear Accelerations Using Linear Accelerometers

XIONG Yong-hu, MA Bao-hua, PENG Xing-ping

2000, 9(3): 307-311.

[Abstract](243) [PDF 275KB](6)

Abstract:
In order to solve the problem, which may be encountered by those former schemes, such as six accelerometer, nine accelerometer configuration, under specific conditions, a ten accelerometer configuration was presented to compute the rotational and translational accelerations of a rigid body, based on well known kinematics principles. The theoretical analysis shows that the configuration can meet the requirement. The simulation results of this scheme show promise for measuring a rigid body's rotational and translational accelerations.

Feature Extraction of Acoustic/Seismic Signal of Target

ZHANG Zhong-min, LI Ke-jie, LI Gui-tao, SHANG Ya-ling

2000, 9(3): 312-317.

[Abstract](293)

Abstract:
A microphone and a seismic sensor always become a basic unit of UGS(unattended ground sensors) system. The mechanism of acoustic and seismic property of target and its propagation are described. The acoustic and seismic signals of targets are analyzed with time frequency distribution according to its non stationary property. Narrow band energy function (NEF) and local power spectral density (LPSD) are proposed to extract features for target identification. Experiment results show that local power spectral density indicates corresponding target clearly.

Robotic Electrotactile Feedback Glove for Tele Presence System

ZHANG Hong-fen, LI Ke-jie, AI Jun-bo, SHEN Yan-tao

2000, 9(3): 318-323.

[Abstract](276)

Abstract:
Progress is described regarding the development of a new electrotactile feedback glove designed for application to dexterous robot. The sensitivity of operator's finger against electrical stimulus pulse is considered. It is found that frequency, duty ratio, and voltage amplitude of electrical stimulus pulse determine the sensitivity of finger. The effects of materials, sizes, arrangements and shapes of electrodes on sensitivity of finger are analyzed. Finally, the tactile tele presence system is designed to experimentally confirm that the robot with electrotactile feedback glove can manipulate dexterous robotic multi fingered hand and identify and classify three sorts of objects.

Property Analyses and Experiment Studies of a Kind of PWM System

YAO Xiao-xian, YANG Shu-xing, DENG Yi-feng

2000, 9(3): 324-329.

[Abstract](217)

Abstract:
The properties and the design of PWM systems are discussed. The relations among the orifice areas of the valves, initial times and the rate of piston areas are deduced. Also a PWM system is designed and some experiments are done. The experiment results agree with those of theory analyses. It can be shown that the relations are correct and the conclusion of theory analyses is reasonable.

Computer Simulation of Compensation Method for Infrared Focal Plane Array

KANG Chang-geng

2000, 9(3): 330-334.

[Abstract](268)

Abstract:
A major motivation for this work is to investigate a method of computer simulation for compensating fixed pattern noise of the infrared focal plane arrays. A mathematical model of the output signal of focal plane array was established; a compensating algorithm utilizing reference source was derived and simulating programs were designed. The images of compensating process verify the influence of nonuniformity of responsibility and offset on fixed pattern noise. The result show that simulating method of investigating compensation technology for focal plane arrays is feasible, the generated images and methods can be used to the study of image recognition.

Method of Edge Extraction Based on Wavelet Transform for the Image of Mechanical Engineering Drawings

WU Lin-rui, CHEN Jiong-bai, YUAN Zeng-feng

2000, 9(3): 335-340.

[Abstract](225)

Abstract:
A method, by which the broken edge of mechanical engineering drawings being binarised can be eliminated and the whole edge of mechanical engineering drawing can be got, is given. To all points of a connected area on the image of the modular maximum value of wavelet transform at scale 2², the averaging grey value method is used to their grey values, then the edge of the dim place is continuous after the maximum variance threshold method is used. All these methods are fast, they can be used for all linear graphics having nothing to do with the grey value, its application scope is wide.

Detonation Behavior of Intermolecular Explosives EAR

WANG Ting-zeng, XU Geng-guang, XU Jun-pei, LIU Yun-jian

2000, 9(3): 341-346.

[Abstract](212)

Abstract:
In order to find out the detonation mechanism of intermolecular explosives (IMX), the EAR15 explosive is studied by the experiments and numerical modeling. The results show that EAR15 is a nonideal explosive, since in the detonation reaction zone both reacted and unreacted ammonium nitrate (AN) absorb the energy through the interface, resulting in the charac-teristic of nonideal detonation. In our tests, only 19%-49% active AN takes part in reaction, the rest behaves as the inert at the detonation wave front.

Experimental Investigation on Basic Prototype of Solid Propellant Impulsive Microthrusters

LI Shi-peng, ZHANG Ping

2000, 9(3): 347-352.

[Abstract](199)

Abstract:
A new type of impulsive microthruster and its measurement system were designed for the aim of testing the performance of a basic prototype of solid propellant impulsive microthruster. Two sets of tests were conducted. The tests show that the ignitor and the main charge of the microthruster match well, the dynamic and static capability of the test and mea-surement meets the test requirement and the result is creditable. The measured technical charac-teristics of the microthruster are that the ignition delay time is shorter than 0.3 ms, the total impulse is over 3 N·s, the operational time is shorter than 16 ms and the mass ratio of the thruster is 0.216.

2000 Vol. 9, No. 3