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Digital Imaging Reconstruction from Multiple Angle Diversity Using Digital Filtering Technique

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Journal of Systems Engineering and Electronics 1991年第1期2卷 67-73页

作者： Wu Chuanjie and Li ShizhiDept. of Electronic Engineering, Beijing Institute of Technology p.o. box 327, Beijing 100081, China Dept. of Electronic Engineering Beijing China of Technology P.O. Box 327 Beijing 100081 China

Microwave diffraction tomography is a process to infer the internal structure of an objectfrom multiple angle views of microwave diffraction shadow. Being sensitive to variations in refractive index of the object, the procedure can be used to measure permittivity distributions within dielectric objects and to image soft tissues for biomedical applications. The optimal resolution distance obtainable is half a wavelength, but this can rarely be achieved because of practical limitations. Some procedures, however, are available to improve the practical resolution. one, which is suitable for microwave tomography, is to use multiple angle views data and to combine the resulting images. The other, which is suitable for improving the image reconstruction resolution, is to use the digital filtering technique and the filtered backpropagation algorithm. A system operating over the X-band microwave frequency is described and some experimental results for objects in air are given.

关键词： Digital filtering Digital image reconstruction Microwave diffraction tomography.

Radar Imaging Based on Iterative Algorithms

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Journal of Systems Engineering and Electronics 1991年第2期2卷 91-99页

作者： Qiangfu Zhao, Zhong Wang and Youan KeDept. of Electronic Eng., Beijing Institute of Technology, p.o.box 327, Beijing 100081, China Dept. of Electronic Eng. Beijing Institute of Technology P.O. Box 327 Beijing 100081 China

It has long been realized that the problem of radar imaging is a special case of image reconstruction in which the data are incomplete and noisy. In other fields, iterative reconstruction algorithms have been used successfully to improve the image quality. This paper studies the application of iterative algorithms in radar imaging. A discrete model is first derived, and the iterative algorithms are then adapted to radar imaging. Although such algorithms are usually time consuming, this paper shows that, if the algorithms are appropriately simplified, it is possible to realize them even in real time. The efficiency of iterative algorithms is shown through computer simulations.

关键词： Radar imaging Computerized tomography Discrete model Iterative reconstruction algorithm Algebraic reconstruction technique.

oN DISCoNTINUoUS REINFoRCED NiAl-BASED CoMpoSITES

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Acta Metallurgica Sinica(English Letters) 1995年第Z1期8卷 589-595页

作者： CHENG Tianyi (Metal Materials Section, Beijing Institute of Technology, p.o.box 327, China,International Centre for Materials physics, Academia Sinica, Shenyang 110015), China

Mechanically alloyed NiAl-TiB_2-Y_2o_3 composite (volume percentage of dispersoids about 15v%) was prepared by hot pressing. The compressive properties of the composite from 300 K to 1360 K were tested and the microstructures were studied mainly by TEM. The yield strengths of the composite at room temperature and high temperatures are considerably higher than that of monolithic NiAl and also is higher than similar NiAl-based composites which contained higher content of dispersoids but showed coarser microstructure. The possible strengthening mechanisms working in the composite are discussed.

关键词： NiAl composite strength

Application of High Burning Rate propellant to Impulsive Microthruster

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Application of High Burning Rate Propellant to Impulsive Mic...

2003年国际推进剂、炸药、烟火技术秋季研讨会

作者： LI Shipeng & ZHANG ping (School of Mechano-Electronics Engineering Beijing Institute of Technology p o box 327 Beijing 100081 China)

＜正＞ To explore the application capability of high burning rate solid propellant available in China to the attitude control of hypervelocity flight vehicle, some exploratory test has been conducted and the two application examples of it are discussed. The reason of the application of high burning rate propellant- to an impulsive microthrusters is also introduced. It is shown from tests that even if the propellant burning rate is not high enough, the demand of burning time within 10ms can be still satisfied if the appropriate grain design technology are adopted;and the math performance of igniter and propellant grain is the keypoint of getting the satisfied internal ballistics of an impulsive microthruster.

关键词： solid propellant impulsive microthruster high burning rate ignition

RECENT DEVELopMENT oN CoMpUTATIoNAL ELECTRoMAGNETICS IN CHINA

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RECENT DEVELOPMENT ON COMPUTATIONAL ELECTROMAGNETICS IN CHIN...

The 1994 International Conference on Computational Electromagnetics and Its Applications

作者： Li Shi Zhi Department of Electronic Engineering Beijing Institute of Technology p. o. box 327 Beijing 100081 China

＜正＞ This is the first conference devoted to Computational Electromagnetics and its applications in China. This conference has been oriented to give a wide presentation of topics concerning Computational Electromagnetics and modeling problems. on behalf of the Scientific program Committee I extend a very warm welcome to delegates to The 1994 ’ ICCEA Conference and give a brief introduction of recent development on Computational Electromagnetics in China especially in this conference.

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Study on the Fuzzy AHp of Safety Assessment in pyrotechnics production Systems

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Study on the Fuzzy AHP of Safety Assessment in Pyrotechnics ...

2003年国际推进剂、炸药、烟火技术秋季研讨会

作者： ZHENG Heng & WANG peilan( State Key Laboratory of prevention and Control of Explosion Disasters Beijing Institute of Technology p o box 327 Beijing 100081 China)

＜正＞ Fuzzy Analytical Hierarchy process （Fuzzy AHp） is derived from the traditional AHp , considering the fact that people’s estimation for a complicated business is fuzzy in nature. In this paper, the main theory and solving steps of fuzzy AHp are introduced for assessing the pyrotechnics production systems’ safety status. By means of the quantitative calculation in the fuzzy AHp, the experts’ fuzzy estimation for variants safety indexes in pyrotechnics production systems can be transformed into weights of the factors that have influence on the system’s safety state, hence the reasonable safety assessment result can be achieved.

关键词： pyrotechnics production systems safety assessment fuzzy ahp fuzzy consistent matrix preference relation matrix weights

Experiment Study and Numerical Simulation of Tungsten Alloy Ball penetrating Vertically the Ceramic/Aluminum Combined Target

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Experiment Study and Numerical Simulation of Tungsten Alloy ...

2003年国际推进剂、炸药、烟火技术秋季研讨会

作者： JIANG Chunlan LI Ming JIANG Jianwei & WANG Zaicheng(State Key Laboratory of prevention and Control of Explosion Disasters Beijing Institute of Technology p o box 327 Beijing 100081 China)

＜正＞ In this paper, on the basis of the experimental research and numerical simulation, the systematical study on the tungsten ball penetrating normally the lightweight ceramic armors is performed. The ballistic limit velocity of tungsten ball penetrating vertically the targets is measured. A series of physical pictures of interaction between the ball and targets are obtained. The results are quite agreement between tungsten ball and ceramic/Al target obtained by experiment and simulation calculating.

关键词： tungsten ball ceramic armor perforation experiment simulation

Theoretical Study on the Rod Broken under Sliding Detonation

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Theoretical Study on the Rod Broken under Sliding Detonation

2003年国际推进剂、炸药、烟火技术秋季研讨会

作者： WANG Shushan JI Congsheng JIN Jiabo & MA Feng(State Key Laboratory of prevention and Control of Explosion Disasters Beijing Institute of Technology p o box 327 Beijing 100081 China)

＜正＞ The integrity of pre-made rods driven by the explosive products is a key problem for the design of discrete-rod warhead. In this paper, the mathematic models of both the flow field of explosive products and the axial tension stress of rod under sliding detonation are established, and the analytical method of the rod broken is obtained. Making use of the models, a certain discrete-rod warhead configuration is studied. The results are useful for the design of discrete-rod warhead.

关键词： sliding detonation discrete-rod warhead rod broken

Study on Size of Aluminum particle in Single Event Fuel -Air- Explosive

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Study on Size of Aluminum Particle in Single Event Fuel -Air...

2003年国际推进剂、炸药、烟火技术秋季研讨会

作者： LUo Aimin ZHANG Qi BAI Chunhua YAN Hua & LI Jianping(State Key Laboratory of prevention and Control of Explosion Disasters Beijing Institute of Technology p o box 327 Beijing 100081 China) .

＜正＞ Temperature response model of aluminum particle is developed when single event fuel-air-explosive （FAE） detonates. Expansion process of FAE products is analyzed with KoDAK EKTApRo EM Motion Analyzer. Thermal penetrating depth and its corresponding temperature of aluminum are obtained so as to evaluate ignition possibility of aluminum particle. The results shows that, more thermal energy is absorbed by aluminum particle during expansion process than detonation zone;spherical aluminum particle of diameter 2.2μm could ignite instantly behind detonation zone;spherical aluminum particle of diameter 9.4μm could ignite behind detonation zone and expansion process.

关键词： Ignition and combustion Temperature response model of aluminum Motion analyzer Single event fuel-air-explosive