Table of Content

30 November 2015, Volume 36 Issue 11

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Paper

Research on Electropneumatic Brake for Unmanned Wheeled Vehicle

ZHU Min, CHEN Hui-yan, XIONG Guang-ming

2015, 36(11):  2017-2023.  doi:10.3969/j.issn.1000-1093.2015.11.001

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The electronic control brake technology for unmanned driving is researched based on a 4×4 manned light tactical wheeled vehicle. An electropneumatic brake system is designed according to the structure and characteristics of the original vehicle air brake, which realizes an electronic control brake function in unmanned driving mode, and reserves the manual brake function in manual driving mode. The two modes can be switched freely. The control characteristics of solenoid valve, vehicle rolling resistance coefficient on different roads, and the relationship among vehicle deceleration, speed and control input of electronic control brake are identified through vehicle test. The test results show that the electropneumatic brake system can rapidly and accurately respond to the braking request, and the user can flexibly switch between manual braking and electronic-controlled braking. The electropneumatic brake system can be used for the commercial vehicles.

Dynamics Analysis of Helicoid Pushing Chain Mechanism for Automatic Ammunition Loading System

ZHANG Lei-yu, YANG Yang

2015, 36(11):  2024-2031.  doi:10.3969/j.issn.1000-1093.2015.11.002

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The helicoid pushing chain mechanism is a novel telescopic mechanism used to push objects from one position to another one rapidly.It occupies a minimal amount of space in the contact status. In constrained space the helicoid chain case adopted may store as many links as possible for acquiring a long telescopic distance. In order to analyze the influences of polygon effect and meshing impact on the dynamic properties and pushing stability of the unidirectional chain, the dynamics models are established for the processes of extracting the unidirectional chain from the helicoid chain case and it meshing with the sprocket. Meanwhile, the extended part is simplified as a multi-spring-damping system, and the dynamics model of pushing process is deduced. The full dynamics models is numerically simulated by using MATLAB software and Rung-Kutta method. The simulation results show that the drawing force acted on the unidirectional chain in the chaincase drops down to zero concussively over time, and the change of the thrust force transits form drastic oscillation to smooth fluctuation. Besides, the pushing velocity of the chain is nearly constant during the pushing process. Hence this mechanism has an excellent pushing stability. In addition, the established dynamics models are verified by the experimental measurement of the pushing velocity.

Research on Non-dimensional Characteristics of Centrifugal Compressor under Altitude Environment

ZHANG Hong， WU Gang， WEI Ming-shan, ZHANG Hang

2015, 36(11):  2032-2037.  doi:10.3969/j.issn.1000-1093.2015.11.003

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A vehicular diesel turbocharger working in altitude environment is studied. Based on the theory analysis of non-dimensional characteristics of centrifugal compressor, the effects of plateau conditions and low Reynolds number on compressor characterisitics are investigated using numerical simulation method. The performance of compressor is analyzed with the use of non-dimensional flow rate and non-dimensional speed by changing compressor inlet parameters.The influences of the changes in inlet temperature and pressure on the equivalent characteristics of compressor are discussed, and the change rule of compressor non-dimensional characteristics under altitude environment was obtained. The results show that the reduction in compressor inlet pressure leads to low Reynolds number on plateau to make the change of compressor internal flow, which is the main reason to reduce the comprossor performance.

Dynamic Constitutive Model of Gun Steel Material and Its Verification

ZENG Zhi-yin, GAO Xiao-ke, LIU Peng-ke, YU Hua-sa

2015, 36(11):  2038-2044.  doi:10.3969/j.issn.1000-1093.2015.11.004

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The static and dynamic SHPB (split Hopkinson pressure bar) tests are made on a gun steel material at the temperature of 88~573 K and the strain rate of 0.001~2 000 s^-1. The preliminarily obtained parameters of constitutive model of some gun steel material are verified and confirmed by the optimization procedure and Taylor impact test. The difference between the predicted and experimental results is less than 5%. The experimental results show that the proposed dynamic constitutive model can reflect the dynamic response of gun steel material under loads effectively.

Experimental Research on Three-powder Chamber Launch Device with Secondary Acceleration Function

WU Jun, XIAO Ling, ZHUANG Tie-shuan, ZHAO Qian

2015, 36(11):  2045-2052.  doi:10.3969/j.issn.1000-1093.2015.11.005

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How to increase initial velocity is an eternal subject matter for tube weapon technology. An operating principle is put forward for three-powder chamber launch device with secondary acceleration function, and the launch test is made. The characteristic of the device is that two accessory powder chambers are added on the barrel, which are at a distance from the primary powder chamber. When a projectile passes through the entrance of accessory powder chambers, the charges in the accessory powder chambers are ignited by high-heat and high-compressed power gas. The gas generated by accessory power burning can slow up the space pressure and keep the projectile base at high pressure, achieving the objective of secondary acceleration . The interior ballistic analysis and launch test result show that the initial velocity is increased by 15% in the case of indistinctively increased chamber pressure.

Tracking Control for Electro-hydraulic Positioning Servo System Based on Disturbance Observer

LIU Long， YAO Jian-yong， HU Jian， MA Da-wei， DENG Wen-xiang

2015, 36(11):  2053-2061.  doi:10.3969/j.issn.1000-1093.2015.11.006

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A kind of modeling uncertainties compensation control strategy based on sliding mode is proposed for electro-hydraulic positioning servo system with matched and unmatched modeling uncertainties. A sliding mode observer is designed to estimate the matched and unmatched modeling uncertainties of electro-hydraulic positioning servo system and compensate the uncertainties during the design of the sliding mode controller, thus effectively weakening the discontinuous term gain. The sliding surface of observer is introduced to the sliding surface of controller to construct a new controller sliding surface and eliminate the estimation error of uncertainties so that the good dynamic performance of the controller can be ensured. Besides, the deterioration of tracking performance, which comes from the measured noise, can be reduced without system acceleration. Finally, the global stability of the closed-loop system is verified by the Lyapunov stability theory. Simulation results show that the matched and unmatched modeling uncertainties of the electro-hydraulic positioning servo system can be compensated by the proposed method compared with the integral sliding model control strategy. At the meantime, the chattering of sliding mode control is weakened, and the system possesses good tracking performance and strong robustness.

Research on Operation Process and Firing Range of Base Bleed Projectile Based on Computational Fluid Dynamics Coupledwith Particle Trajectory

ZHUO Chang-fei, YAO Wen-jin, WU Xiao-song, XU Wen-ke, FENG Feng

2015, 36(11):  2062-2072.  doi:10.3969/j.issn.1000-1093.2015.11.007

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Based on the advantages of computational fluid dynamics and the firing range prediction of base bleed projectile, the flight ballistic trajectory of base bleed projectile is solved by using the computational aerodynamics coupled with particle trajectory, and the change laws of operating parameter, operating state, and flow filed of base bleed projectile with time are obtained. The results show that the base bleed parameters of the base bleed projectiles launched at different altitudes increase with the increase in time in early drag reduction stage, but it varies slowly with the increase in time in the late drag reduction stage; with the increase in altitude for launching, the drag coefficient of the base bleed projectile increases slowly with the increase in time in the drag reduction stage, and even it decreases with the time. For the base bleed projectile launching at altitude of 0 km, the base bleed device in the early drag reduction stage operates in the mode of base bleed. And in the late stage, the base bleed device operates between base bleed mode and rocket mode.

Research on Projectile-target Encounter Algorithm for Six-quadrant Scanning Laser Proximity Fuze Sensor

LI Yuan, LI Yan-hua, LI Luo, GUO Hai-chao, ZHANG Yan-mei, WEN Yu-quan

2015, 36(11):  2073-2079.  doi:10.3969/j.issn.1000-1093.2015.11.008

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Based on the fuze sensor and detonation control system of an aimiable warhead of a spinning rocket, the construction and functional mechanism of the six-quadrant scanning laser fuze sensor is analyzed. A method of measuring the rocket rotational speed based on the spiral angle of laser beam is proposed. A mathematic model of rotational speed and a projectile-target relative motion equation are deduced, which can be solved by iterative decoupling algorithm. Simulation based on the Fortran program is conducted, and the optimal detonation time delay, optimal detonation azimuth angle and miss distance are obtained. The error analysis shows that the detected azimuth error meets the requirement of detecting accuracy.

Effect of Tempering Temperature on the Forming Properties of Fragments of 50SiMnVB Steel Shell

ZHU Jian-jun， LI Wei-bing， WANG Xiao-ming， CHENG Xing-wang， LI Wen-bin, LU Hai-tao

2015, 36(11):  2080-2086.  doi:10.3969/j.issn.1000-1093.2015.11.009

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In order to acquire the effects of different tempering temperatures on the forming properties of shell fragments, 50SiMnVB steel is used as shell material, and is tempered at 3 different temperatures. The forming velocity and mass distribution of 50SiMnVB steel shell fragments are researched through the initial velocity test and the fragment recovering well test, and the expanding and breaking processes of 50SiMnVB steel shell, and the variation rules of fragment velocity and fragment mass distribution are numerically simulated by using AUTODYN-3D finite element analysis software. The results shows that，with the increase in tempering temperature，the breaking degree of 50SiMnVB steel shell decreases and the total number of fragments reduces gradually，but the fragments which mass is more than 1.0 g increase gradually，which is increased by 77.4%; however，the tempering temperatures have less influence on the initial velocity of 50SiMnVB steel shell fragments.

Influence of Coating on Resistance of Fuze Springs

LIU Li-bin, WANG Yu-shi, WEN Quan

2015, 36(11):  2087-2092.  doi:10.3969/j.issn.1000-1093.2015.11.010

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In order to reveal the influence of coating on the resistance of fuze springs, the relation among coating material, coating thickness and fuze springs’ resistance is analyzed by theoretical derivation and finite element analysis. The calculated results of two methods are compared and verified by experiment. The results show that the thickness of coating is the main factor influencing the resistance of fuze springs for the same kind of coating material; and the yield strength of coating material is the main factor influencing the resistance of fuze spring for the different kind of coating materials. The conclusion shows that the coating material and its thickness are very important to control the resistance of fuze springs.

Cooling Crystallization Method for Preparation of Millimeter-scale Spheroidized RDX

ZHANG Mao-lin, JIA Hong-xuan, WU Wen-li, LIU Bo, LU Ming

2015, 36(11):  2093-2098.  doi:10.3969/j.issn.1000-1093.2015.11.011

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The millimeter-scales pheroidized RDX is prepared by cooling crystallization using cyclopentanone as a solvent. The effects of process parameters, such as solution concentration, addition of seed, crystallization temperature, cooling rate, and stirring rate, are investigated. The crystal density, axial ratio, bulk density, and mechanical sensitivity are tested. The results show that the millimeter-grade spheroidized RDX has smooth crystal surface and compact structure. The crystal density is 1.813 g/cm³, the axial ratio is less than 1.21, and the bulk density is 1.26 g/cm³. Its mechanical sensitivity is obviously lower than that of ordinary RDX, the friction sensitivity is decreased from 82% to 62%, and the impact sensitivity is decreased from 80% to 52%.

Influence of Recrystallization Method on Crystal Properties and Performance of LLM-105

XU Rong, LIAO Long-yu, WANG Shu-cun, ZHANG Yong

2015, 36(11):  2099-2103.  doi:10.3969/j.issn.1000-1093.2015.11.012

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LLM-105 is recrystallized in DMSO and 65% HNO₃ using falling temperature method, direct and inverse solvent/nonsolvent precipitation methods and supersonic-assisted recrystallization method, respectively. The results show that LLM-105 crystal shape obtained using falling temperature method is anomalistic in any solvents. The smooth-faced granular crystals without twin crystal are achieved using supersonic-assisted recrystallization method. The purity is up to 98%. LLM-105 particles obtained in 65% HNO₃ by inverse precipitation have moderate size, small span of particle size and lower impact sensitivity.

Error Analysis of Instantaneous Frequency Estimation Based on Short-time Fractional Fourier Transform

DENG Bing， LUAN Jun-bao， TANG Guang-sheng

2015, 36(11):  2104-2110.  doi:10.3969/j.issn.1000-1093.2015.11.013

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As an important content on radar signal processing, instantaneous frequency estimation plays an essential role in target detection and recognition. The higher time-frequency resolution of short-time fractional Fourier transform (STFRFT) is used to analyze the relationship among window function, window width and the instantaneous frequency estimation precision of cubic phase non-LFM signal. The result shows that, when Gauss window is used, the estimation precision is the highest; the prime window width L, the product of pulse width and band width σ_tσ_f and the frequency fluctuation rate k should meet L=33σtσf/2k. Finally, the result is verified through simulation.

Analysis of Fluxgate Excitation Model

LIU Wen-jun, XU Zhen-feng, LI Shen-gao, LIU Bo

2015, 36(11):  2111-2116.  doi:10.3969/j.issn.1000-1093.2015.11.014

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In order to explore the influence of excitation circuit parameters on the current of probe of three-tips fluxgate magnetometer, and provide a proper theoretical foundation for designing transformer parameters, a novel mathematical model is proposed based on transformer coupling and probe’s self-inductance through numerical analysis. The numerical results and the actual tests are matched. The proposed method provides a powerful help to design parameters of excitation circuit, and make further study on the relationship between circuit parameters and excitation current.

Simulation and Evaluation of Zero Fly Test in Complex Optical Environment

CHEN Zhi-qiang, WANG Xiao-man, ZHU Yong, JING Wen-bo, LIU Min-shi

2015, 36(11):  2117-2121.  doi:10.3969/j.issn.1000-1093.2015.11.015

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No reliable experimental parameters can be used as basis and guidance for the calibration test of anti-aircraft gun weapon system. For the question, the conditions of test in the complex optical environment should be simulated and assessed before zero-fly test. A simulation and assessment model, including test environment, transmission environment, camera parameter and test condition, is presented. In the proposed model, the simulation results are used as the theoretical foundation of zero-fly test, and the errors of zero-fly test results are analyzed. The results show that the model can improve the benefit and accuracy of zero-fly test.

Measurement of Jamming Effect of Smoke on Laser Guided Weapon Based on Semi-physical Simulation

SHEN Tao， YANG Wei-jun, YAO Min-li, LIU Zhi-guo

2015, 36(11):  2122-2127.  doi:10.3969/j.issn.1000-1093.2015.11.016

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In order to measure the jamming effect of smoke on laser guided weapon, an interference effect semi-physical simulation measurement system is established. The evaluation rules of jamming effectiveness are presented according to the connotation of the test and evaluation of smoke jamming, and the smoke jamming evaluation method is discussed. It is determined whether a jamming is effective or not according to the changing of the tracking error, guidance accuracy of electro-optical guidance system or hit probability. The test result of the smoke screen jamming laser guided weapons under typical weather environment and different bomb release modes are given. Experimental results show that the jamming effectiveness changes with smoke transmissivity.

DOA Estimation of Acoustic Vector Sensor Array Based on Multi-stage Wiener Filter

ZHANG Ke, CHENG Ju-ming, FU Jin

2015, 36(11):  2128-2134.  doi:10.3969/j.issn.1000-1093.2015.11.017

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Traditional high-resolution DOA estimation algorithm for acoustic vector sensor array(AVSA) is computational intensive and difficult to realize in engineering. To solve this problem, a fast DOA estimation algorithm based on MSWF is proposed, which is also called V-MSWF. V-MSWF algorithm selects an output from sound pressure channel of reference array element of AVSA as its desired signal. The signal subspace can be achieved by MSWF recursively. V-MSWF algorithm does not need to calculate cross-covariance matrix and eigen-decomposition. It has a good performance for DOA estimation at high SNR. Computer simulation and experiment in anechoic water tank show the favorable performance of V-MSWF algorithm.

Research on Safe Distance of Ship-based Laser Deflection Decoy Jamming System

ZHANG Shuang, ZHANG Xiao-Hui, SUN Chun-sheng

2015, 36(11):  2135-2140.  doi:10.3969/j.issn.1000-1093.2015.11.018

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Based on the operational mechanism of ship-based laser deflection decoy jamming system and the impulsive factor damage standard for underwater explosion, a calculational method of safe distance for ship-based laser deflection decoy jamming system is investigated. The safe distance of ship-based laser deflection decoy jamming system from different laser guidance weapons is calculated based on the proposed calculation method, and the results are analyzed. The effects of flight velocity, water entry angle and explosive loading of laser guided weapons on the safe distance are discussed. The calculated results show that the flight velocity and explosive loading of laser guidance weapons are the main factors of affecting the safe distance. The safe distance increases with explosive loading of laser guidance weapons, and changes dramatically with water entry angle at increased flight velocity. The results give support to the selection of safe distance of ship-based laser deflection decoy jamming system.

Research on Milling Process of Aramid Fiber Reinforced Composite Materials in Cryogenic Conditions

WANG Feng-biao, ZHANG Jin-bao, MA Yu-yong, HOU Bo, WANG Yong-qing

2015, 36(11):  2141-2148.  doi:10.3969/j.issn.1000-1093.2015.11.019

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In order to reduce the defects of fluff and high temperature ablation of aramid fiber reinforced materials during milling, and to improve the cutting performance and machining quality, the material is processed by CNC milling machine. The liquid nitrogen is used as a cryogenic cutting fluid. The ultra-deep microscope digital microscope,3D surface contourgraph and dynamometer are used to measure the surface morphology, surface roughness and cutting force of cut specimens, respectively. A material model of milling process is established. The defects of dry milling are analyzed,and the liquid nitrogen cryogenic cutting mechanism is discussed. The results show that the machining quality of cryogenic cutting is excellent compared to dry ones at the same cutting speed. In two kinds of cutting conditions, the main cutting force declines with the increase in speed, and for the cryogenic one the trend is more obvious. At the same speed, the main cutting force in cryogenic milling is higher than that in dry milling. For the adhesive point of fiber woven it is lower cutter stress tolerance, and the fiber has automatic collision avoidance and elongation properties at high temperature and pressure, which lead to the inaccurate controll of milled surface quality. Besides the improvement of cryogenic cutting force and cutting temperature drop have played a positive role for the improvement of the aramid fiber cutting defects.

Research on Efficient Electrical Discharge Milling of TC4 Titanium Alloy

GUO Cheng-bo, DI Shi-chun, WEI Dong-bo, SONG Yun-long, WU Xiang

2015, 36(11):  2149-2156.  doi:10.3969/j.issn.1000-1093.2015.11.020

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Titanium alloy has been widely used in the aerospace manufacturing industry due to its excellent mechanical properties. The application promotion of titanium alloy is limited because its poor cutting properties have not been solved. The efficient processing of titanium alloy was realized by using the electrical discharge milling. The influences of processing parameters, such as pulse-on time, pulse-off time, peak current, electrode rotating speed, flush pressure and depth of cut, on the processing efficiency of titanium alloy are studied through orthogonal experiment in which a power supply with long pulse-on time and high current is used. The processing parameter optimization, range analysis and significance analysis methods are used in this study. The maximum processing efficiency of electrical discharge milling is predicted using processing efficiency prediction formula. The processing efficient of titanium alloy reaches to 9 000 mm³/min with pulse duration of 2 000 μs, pulse interval of 100 μs, peak current of 635 A, electrode rotary speed of 800 rpm, flushing pressure of 1.5 MPa, and cutting depth of 3 mm based on the orthogonal experimental analysis. The heat-affected layer of titanium alloy processed surface was tested using SEM, and the feasibility of titanium alloy high efficiency machining using electrical discharge milling is verified. Although ED-milling of TC4 titanium alloy has a low machining precision and poor surface quality, it can reduce the cost of machining by 90% compared to traditional cutting method.

Numerical Simulation of Cu Particles Impacting on Medium Steel in Laser-assisted Cold Spraying

LUO Fang, ZHAO Bing, YAO Jian-hua

2015, 36(11):  2157-2163.  doi:10.3969/j.issn.1000-1093.2015.11.021

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The 3D simulation of Cu particles impacting on medium steel substrate in the laser-assisted cold spray process is performed using the finite element analysis software ANSY/LS-DYNA based on Johnson-Cook material model and bilinear isotropic hardening material model. The process parameters, such as particle impact velocity, deposition temperature, are simulated to obtain the deformation contours, crater depth and so on. The results show that Cu particles can be deposited on medium steel effectively at the velocity of 800 m/s in room temperature environment and at the velocity of 500 m/s at 850 ℃. In addition, the two material models both can be used to predict the process parameters for the laser-assisted cold spraying.

Optimization Strategy of Preventive Maintenance in Finite Time Horizon

GAI Jing-bo, KONG Yao

2015, 36(11):  2164-2172.  doi:10.3969/j.issn.1000-1093.2015.11.022

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Mechanical devices are repairable. Taking an effective preventive maintenance and reasonably arranging the preventive maintenance activities are very important to decrease the failure frequency and improve the utilization ratio. The mechanical device working in finite time horizon is studied. Maintenance cost and comprehensive consideration of maintenance cost and reliability are modeled, a nonlinear optimization software is used to solve the optimization model, and the optimal times and cycles of preventive maintenance in finite time horizon are determined. The examples show that the method of forecasting the preventive maintenance frequency and cycle is feasible. This optimization policy model can provide references for making the preventive maintenance program and predicting the service life of mechanical devices.

Simulation and Optimization of Expanding Device of an Assembled Steel Bridge Based on VirtualPrototyping Technology

ZENG Fan-qi， WANG Qiang， HE Xiao-hui

2015, 36(11):  2173-2179.  doi:10.3969/j.issn.1000-1093.2015.11.023

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To improve the working capability of the bridge expanding device during the bridging and withdrawing process of an assembled steel bridge, the parameterized models of the bridge expanding device and bridge sections are established based on the virtual prototyping technology, and 4 key design variables which have significant effects on the performance of the expanding device are chosen and verified. The optimization design of the device is further carried out by the limit loads of hydraulic cylinders being selected as the optimization target. It is found that , when the bridge expanding device is increased by 9.19% in size according to the optimization project, the maximum loads of its linkage rods can be effectively reduced by 28.6%, and the stress states of the key rods are improved, then the overall performance of the assembled steel bridge expanding device is significantly improved.

Research Notes

Experimental Study of Influences of Input Modes of Vehicle-mounted Display and Control Terminal onCrew's Information Processing Capability

LIU Wei-ping， FU Bin-he， LIU Xi-xia， JIN Yi

2015, 36(11):  2180-2184.  doi:10.3969/j.issn.1000-1093.2015.11.024

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Based on self-developed operation simulation and performance test system of vehicle-mounteddisplay and control terminal, the influences of input modes, i.e., touch and mouse, on crew's information processing capability are analyzed by taking task completion time and error rate as evaluation indicators. The results show that the influences of different input modes on crew's information processing could be effectively discriminated by using the proposed method, and the touch mode should be regarded as the test mode of real operation performance test. However, the training effects of two input modes on mastering system operation functions are the same. The results can provide reference for the input mode selection of vehicle-mounted display and control terminal and the training of armored vehicle crews.

The Structural Dynamic Response of Projectile-borne Optoelectronic Devices during Launching

NING Quan-li, JIANG Bin-an, LIANG Xi, LI Jun

2015, 36(11):  2185-2189.  doi:10.3969/j.issn.1000-1093.2015.11.025

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In order to study the anti-high-overload mechanism of projectile-borne optoelectronic devices, a numerical simulation model of projectile-borne opto- electronic devices is established according to the artillery launching environmental characteristics. A theoretical analysis model of projectile-borne optoelectronic devices is also established to solve the stress, strain and relative velocity of projectile-borne opto-electronic devices. The result shows that the numerically calculated results are in good agreement with the simulated results to verify the correctness of the theoretical analysis model. The proposed model can be used for the reseasch on the dynamic characteristics of the projectile-borne devicess and the theoretical analysis of anti-high-overload design.

Research on Hybrid Case-based Reasoning Technique for Self-propelled Artillery Variant Design

YANG Liu， QIAN Lin-fang， DING Sheng-chun， YIN Qiang

2015, 36(11):  2190-2195.  doi:10.3969/j.issn.1000-1093.2015.11.026

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In order to improve the design quality and efficiency of self-propelled artillery in consideration of a large number of variant design problems existing in self-propelled artillery design, the case-based reasoning technology is introduced into the solution procedure for self-propelled artillery variant design problem. The process of hybrid case reasoning is determined according to the characteristics of self-propelled artillery design case and the requirements of variant design. The ontology-based case representation technique is studied, and a self-propelled artillery design case ontology is built.The similarity calculation formulas for different scenarios are determined for the self-propelled artillery case retrieval. On this basis, the solution of design parameters for variant design problem is achieved by using neural network-based parameter prediction technique. The feasibility and effectiveness of the proposed method are demonstrated by taking recuperator design for example.

A Jamming Approach to SAR Based on Inter-pulse Subsection Random Frequency-shift Technique and Its Application

CAI Xing-fu, ZHANG Xiong-mei, SONG Jian-she, CHANG Zhen

2015, 36(11):  2196-2202.  doi:10.3969/j.issn.1000-1093.2015.11.027

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In order to ensure the safety of intelligence in important place, a jamming approach to synthetic aperture radar (SAR) based on inter-pulse subsection random frequency-shift technique is presented. The technique can produce several noise-like jamming swathes in range direction, of which number is determined by the number of inter-pulse subsection. The position and width of the jamming swathe are determined by frequency shift. The proposed technique overcomes the defect of the conventional fixed frequency-shift jamming which can’t protect distributed target, and produces several jamming swathes compared with random frequency-shift technique which can produce only one jamming swathe. Meanwhile, because of the random change in frequency shift, it is difficult for SAR to find the frequency shift rule and take the corresponding countermeasures. An application model is established, and the implementation steps and method of the technique are provided. The availability and advantages of this method are proved through the simulation experiments.

A Fuzzy Efficiency Evaluation Method for SOAP Flooding Attack

FENG Yong-xin, ZHAO Yun-tao, SU Guang-nan, HUANG Ying-chun

2015, 36(11):  2203-2208.  doi:10.3969/j.issn.1000-1093.2015.11.028

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In view of SOAP flooding attack threats to networks and services with the inherent protocol security vulnerability, especially the limitations of grey evaluation technology, the fuzzy evaluation method is studied according to the efficiency evaluations for the demand on network system security and reliability. Therefore, a fuzzy efficiency evaluation model for SOAP flooding attack is proposed, the focus of which is on attack evaluation matrix description, membership degree matrix selection, weight configuration and comprehensive evaluation. Moreover, the evaluation example with the SOAP flooding attack samples is presented on the basis of the proposed attack efficiency evaluation model. The results show that the fuzzy efficiency evaluation method for SOAP flooding attack has better adaptability than grey evaluation, and can draw the certain evaluation conclusions, as well as supply the scientific and sensible discrimination of attack efficiency.