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Radial dispersion angle of directional fragments in multi-mode warhead

Jiefangjun Ligong Daxue Xuebao/Journal of PLA University of Science and Technology (Natural Science Edition) 2010年第4期11卷 468-472页

作者： Zhang, Yang-Yi Long, Yuan Yu, Dao-Qiang Ji, Chong Zhong, Ming-Shou Engineering Institute of Corps of Engineers PLA Univ. of Sci. and Tech. Nanjing 210007 China State Key Laboratory of Prevention and Control of Explosion Disaster Beijing Institute of Technology Beijing 100081 China The First Research Institute of the Corps of Engineers Wuxi 214035 China

To investigate the characteristics of directional fragments mode in multi-mode warhead, a charge configuration with an ejectable incisory cover fixed at a proper place before the liners was analyzed. The process of the liner forming directional fragments by passing through two different kinds of incisory covers was simulated using LS-DYNA3D. Simulation results coincided well with the experimental data. This charge structure can form fragments with a definite mass and direction, and a velocity between 1 500 m/s and 2500 m/s. A Formula of the radial dispersion angle (α) of fragments was got. Influences of the diameter (D), the yield strength of the incisory wire and the distance between the incisory cover and the liner (d) on α were discussed. It's proved that the bigger D, the larger α;that the bigger the yield strength, the more benefit to the forming of fragments, yet with little influence on α;and that d should be in a proper range in order to form ideal fragments, and it has an optimum value.

关键词： Yield stress

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Analysis of optical transmission characteristics in the waveguide of side polished fiber

Analysis of optical transmission characteristics in the wave...

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2009 International Conference on Optical Instruments and Technology, OIT'09

作者： Zhe, Chen Zuping, He Fei, Cui Yating, Xiao Jun, Zhang Key Laboratory of Disaster Forecast and Control in Engineering Ministry of Education Jinan University 510632 China Key Lab. of Optoelectron. Info. and Sensing Technologies of Guangdong Higher Educational Institutes Jinan University Guangzhou 510632 China Department of Optoelectronic Engineering Jinan University Guangzhou510632 China

ISBN: (纸本)9780819478948

According to the experimental results of side polished fiber (SPF), a three dimensional optical waveguide model with longitudinal side polished transition zones is built. Based on the model, characteristics of optical transmission are calculated and analyzed by three dimensional finite differential beam propagation method. The model describes the optical transmission characteristics because the calculation based on the model is fitted well with the experiments. The calculation shows that the length of side polished area affects the optical attenuation of optical fiber, but the attenuation does not increased monotonically with the length when the length is less than certain value. The relationship between optical attenuation of SPF and the thickness of residual side polished cladding is not a monotonie one as well. The refractive index of overly on the side polished area has much more effect on the optical attenuation. Both width and thickness of overlay on the side polished area cause the oscillated change of optical power attenuation in the fiber core. © 2009 SPIE.

关键词： Light transmission

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A study on multifactorial prediction model for the road traffic accidents

A study on multifactorial prediction model for the road traf...

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9th International Conference of Chinese Transportation Professionals, ICCTP 2009: Critical Issues in Transportation System Planning, Development, and Management

作者： Liu, Zhao-Hui Key Laboratory of Mine Disaster Prevention and Control of Ministry of Education College of Resources and Environmental Engineering Shandong University of Science and Technology Qingdao 266510 China

ISBN: (纸本)9780784410646

Disharmony of various factors in road system is one of important reasons that cause traffic accidents. In order to study how traffic accidents are influenced by various road factors, it is required to transform traditional linear prediction models into non-linear prediction ones. Considering above-mentioned problems, multifactorial model for road traffic accident prediction based on Grey-Radial Basis Function (RBF) neural networks is put forward by combining virtues of Grey theory that aim at handling "poor" information and weaken undulation of data sequence together with the superior capability of neural networks of adapting non-linear information. Finally, the results of a case study demonstrate that the combined model can effectually overcome the shortcoming that current prediction models only consider influence of one factor on the traffic accidents. The proposed models can also improve efficiency of system modeling and precision of the prediction. © 2009 ASCE.

关键词： forecasting

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Space-time evolution rules study on acoustic emission location in rock under cyclic loading

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Frontiers of Structural and Civil engineering 2009年第4期3卷 422-427页

作者： Jiang XU Xiaojun TANG Shuchun LI Yunqi TAO Yongdong JIANG Key Laboratory for Exploitation of Southwestern Resources and Environmental Disaster Control Engineering Ministry of EducationChongqing UniversityChongqing 400030China Chongqing Industry Polytechnic College Chongqing 400044China

An acoustic emission(AE)location experiment was performed on sandstone using an advanced AE test *** space-time evolution rule regarding damage was analyzed under cyclic loading as well as *** results show that AE on static loading process is consistent with the damage evolution rule of compression and the elastic-plastic deformation phase;at the beginning of cyclic loading with low duration time and energy,AE events came from a small *** location result showed that most events occurred in the core zone forming at the static loading process,and the location points changed *** energy changed little during the metaphase of cyclic *** was a modest increase of location points in every *** tendency of steady development could be predicted from the AE location *** the end of each cyclic loading,the quantity of AE events and energy increased quite rapidly,reaching a maximum at the last *** events had high energy and duration *** events changed quite rapidly and assembled and linked continuously in the core *** the same time,they expanded to the top of specimen.A macroscopic crack finally *** the postfailure process,some AE events still existed due to fracturing of gliding *** to the inner stress balance of rock even after loading stopped,minor AE events still occurred.

关键词： cyclic loading sandstone acoustic emission(AE) location damage evolvement

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Scattering of SH-wave by a shallow U-shaped tunnel

Scattering of SH-wave by a shallow U-shaped tunnel

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Joint Conference of the 2009 Symposium on Piezoelectricity, Acoustic Waves, and Device Applications, SPAWDA 2009 and 2009 China Symposium on Frequency control Technology

作者： Chen, Zhi-Gang Key Lab. of Disaster Forecast and Control in Engineering Department of Mechanics and Civil Engineering Jinan University Guangzhou 510632 China

ISBN: (纸本)9781424449507

In general, analytical solution for the scattering problem of SH plane wave by a cavity in half-space primarily focused on the circular structure case. However, the case for U-shaped cavities, which are similar to the cross-section of the tunnels, was seldom mentioned in former references. The analytical solution for U-shaped cavity in elastic half space is gained by the multi-polar coordinate system and conformal mapping method. A scattering wave function satisfying zero-stress condition on horizontal surface is constructed in the complex plane, the problem can be inverted into a set of algebraic equations to solve coefficients of the scattering wave by least square method. The numerical examples of the dynamic stress concentration around U-shaped cavities and ground motion on subsurface U-shaped cavity impacted by SH-wave are given. The influences of the incident wave number, angle and depth are discussed. The research indicates that the shallow U-shaped tunnel has significant impact on wave propagation, and interaction between the U-shaped tunnel and the horizontal surface will complicate characteristics of ground motion, and will bring about great increase on dynamic stress around cavity. In this situation, enough attention should be paid on the interaction between the subsurface cavity and the horizontal surface in the seismic design of ground and underground structures. © 2009 IEEE.

关键词： Wave propagation

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Scattering of SH-wave by a shallow U-shaped tunnel

Scattering of SH-wave by a shallow U-shaped tunnel

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SPAWDA Symposium on Piezoelectricity, Acoustic Waves, and Device Applications

作者： Zhi-gang Chen Key Lab of Disaster Forecast and Control in Engineering Ministry of Education Department of Mechanics and Civil Engineering Jinan University Guangzhou China

Summary form only given. In general, analytical solution for the scattering problem of SH plane wave by a cavity in half-space primarily focused on the circular structure case. However, the case for U-shaped cavities, which are similar to the cross-section of the tunnels, was seldom mentioned in former references. The analytical solution for U-shaped cavity in elastic half space is gained by the multi-polar coordinate system and conformal mapping method. A scattering wave function satisfying zero-stress condition on horizontal surface is constructed in the complex plane, the problem can be inverted into a set of algebraic equations to solve coefficients of the scattering wave by least square method. The numerical examples of the dynamic stress concentration around U-shaped cavities and ground motion on subsurface U-shaped cavity impacted by SH-wave are given. The influences of the incident wave number, angle and depth are discussed. The research indicates that the shallow U-shaped tunnel has significant impact on wave propagation, and interaction between the U-shaped tunnel and the horizontal surface will complicate characteristics of ground motion, and will bring about great increase on dynamic stress around cavity. In this situation, enough attention should be paid on the interaction between the subsurface cavity and the horizontal surface in the seismic design of ground and underground structures.

关键词： Scattering Stress Surface waves control engineering education Civil engineering Conformal mapping Wave functions Equations Least squares methods

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Effectiveness analysis of methane-drainage by deep-hole controlled pre-splitting blasting for preventing coal and gas outburst

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Journal of Coal Science & engineering(China) 2009年第2期15卷 166-170页

作者： CAO Shu-gang LI Yong LIU Yan-bao ZHANG Li-qiang XU A-meng Key Laboratory for Exploitation of Southwest Resources and Environmental Disaster Control Engineering Ministry of Education Chongqing University Chongqing 400044 China Safety Engineering College North China Institute of Science and Technology Beijing 101601 China

In the study of the application effectiveness of deep-hole controlled pre-splittingblasting technology,it was found through laboratory micro test and field study on a mine insouth China that under the technology,coal masses produce many irreversible ***,the nearer the distance from blasting hole,the larger the BET surface areaand volume ratio of the infiltration pore are;they increased by 11.47%and 5.73%,*** coefficient of air permeability is increased 4 *** 3 months,the gasdrainage rate was increased by 66%.In the first 15 days,the cumulative pumped gas was1.93 times of blasting *** average absolute gas emission decreased by 63.46%.Experimental results show that deep-hole controlled pre-splitting blasting not only preventscoal and gas outburst,but also gives good economic results.

关键词： coal and gas outburst methane-drainage pore structure deep-hole controlled pre-splitting blasting

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A triaxial creep model for coal containing gas and its stability analysis

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Journal of Coal Science & engineering(China) 2009年第3期15卷 248-251页

作者： YIN Guang-zhi WANG Deng-ke HUANG Gun ZHANG Dong-ming WANG Wei-zhong College of Resource and Environmental Sciences Chongqing University Chongqing 400044 China Key Laboratory for the Exploitation of Southwest Resources and the Environmental Disaster Control Engineering Ministry of Education Chongqing University Chongqing 400044 China

Triaxial creep tests on CCG specimens were systematically performed using aself-made creep seepage experimental apparatus for determining the creep law of *** improved triaxial creep model of CCG was established on the basis of a Nishiharamodel and another visco-elasto-plastic model,parameters of which were fitted on test ***,the creep model is validated according to the result of triaxial creep experiments,and the outcome shows that the proposed triaxial creep model can properly characterizethe properties of various creep deformation phases of CCG,especially the acceleratingcreep *** the same time,the instability conditions of CCG were presentedbased on the discussion of the improved model's stability in terms of stability theories ofdifferential equation solution.

关键词： coal containing gas （CCG） triaxial creep model stability creep property failure criterion

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Matter-elements model and application for prediction of ccoal and gas outburst

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Journal of Coal Science & engineering(China) 2009年第3期15卷 273-277页

作者： PENG Shou-jian XU Jiang TAO Yun-qi CHENG Ming-jun Key Laboratory for Exploitation of Southwestern Resources and Environmental Disaster Control Engineering Ministry of Education Chongqing University Chongqing 400030 China

The theory and method of extenics were applied to establish classical field matterelements and segment field matter elements for coal and gas outburst.A matter-element model for prediction was established based on five matter-elements,which includedgas pressure,types of coal damage,coal rigidity,initial speed of methane diffusionand in-situ *** index weight was given fairly and quickly through the improvedanalytic hierarchy process,which need not carry on consistency checks,so accuracy ofassessment can be improved.

关键词： mining engineering coal and gas outburst prediction matter-elements model relational degree

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Method of Green’s function of nonlinear vibration of corrugated shallow shells

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Science China(Physics,Mechanics & Astronomy) 2008年第6期51卷 678-686页

作者： YUAN Hong key laboratory of disaster forecast and control in engineering, Ministry of Education of China, Institute of Applied Mechanics, Jinan University, Guangzhou 510632, China 1. Key Laboratory of Disaster Forecast and Control in Engineering Ministry of Education of China Institute of Applied Mechanics Jinan University Guangzhou 510632 China

Based on the dynamic equations of nonlinear large deflection of axisymmetric shallow shells of revolution, the nonlinear free vibration and forced vibration of a corrugated shallow shell under concentrated load acting at the center have been investigated. The nonlinear partial differential equations of shallow shell were re-duced to the nonlinear integral-differential equations by using the method of Green’s function. To solve the integral-differential equations, the expansion method was used to obtain Green’s function. Then the integral-differential equations were reduced to the form with a degenerate core by expanding Green’s function as a series of characteristic function. Therefore, the integral-differential equations be-came nonlinear ordinary differential equations with regard to time. The ampli-tude-frequency relation, with respect to the natural frequency of the lowest order and the amplitude-frequency response under harmonic force, were obtained by considering single mode vibration. As a numerical example, nonlinear free and forced vibration phenomena of shallow spherical shells with sinusoidal corrugation were studied. The obtained solutions are available for reference to the design of corrugated shells.

关键词： corrugated shells spherical shells Green’s function integral equation nonlinear vibration

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