Table of Content

30 April 2011, Volume 32 Issue 4

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Paper

Study on Transient Response of Diesel Engine Cooling System

LUO Qing-guo， FENG Jian-tao， LIU Guo-fu， GUI Yong

2011, 32(4):  385-390.  doi:10.3969/j.issn.1000-1093.2011.04.001

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A simulation model for diesel engine cooling system was established. The backwater temperature response under variable operating conditions was simulated numerically. The effects of system parameters on the backwater temperature were analyzed. The results show that, changing different single parameters, the time taken for the backwater temperature to reach to steady is different, but relatively short; and if multiple parameters are changed, the time will be longer. Referred to the thermal balance test, the simulation results are validated.

Time Domain Analysis on Shock Response of Main Componets of Diesel

JI Chen, WANG Yu, YANG Li, FENG Lin-han

2011, 32(4):  391-396.  doi:10.3969/j.issn.1000-1093.2011.04.002

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Considered many non-linear contact relationships between the main components in diesel, a time domain simulation method was applied to assessment its shock response. In the assessment, some modeling principles of complex mechanical systems, such as diesel, were given. Also, the finite element models of main components in V6 diesel were established, and then, their shock response characteristics were analyzed in time-domain on the basis of BV043/85 criterion. The stress responses of main components showed the shock vulnerability spots, and the motion response and results of oil film on bearing indicated the work ability. Theanalysis results show that the assessed diesel meet BV043/85 standard on impact security level of A-grade equipments.

Simulation on Plateau Performance of Diesel Engine Matched with Two-stage Sequential Turbocharging System

SHI Xin , LI Wen-xiang

2011, 32(4):  397-402.  doi:10.3969/j.issn.1000-1093.2011.04.003

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A two-stage sequential turbocharging system was proposed in order to meet the power output requirements for diesel engine within the altitude range from zero to 5 500 meters. Based on the required power recovery of CA6DL2 engine, the specific parameters of the turbocharging system were calculated and the low-pressure turbocharger was chosen. The software GT-Power was used to calculate the engine's performance at different altitudes. The simulation results show that, due to a good match with the two-stage sequential turbocharging system, the engine power can be recovered to 80 percent at 5 500 meters while keeping no change at sea level.

Research on Optimization Method for Shift Schedule of Tracked Vehicle with Hydrodynamic-mechanical Transmission

WEI Wei， QU Jing-yao， WU Jing-yan， YAN Qing-dong

2011, 32(4):  403-407.  doi:10.3969/j.issn.1000-1093.2011.04.004

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A kind of automatic shift schedule optimization method was provided for a tracked vehicle with hydrodynamic-mechanical transmission in order to improve its dynamic performance. The dynamic model of the transmission assembly was built in MATLAB/Simdriveline environment, and optimum shift schedule was derived by using iSight software to call the dynamic model above, then the gear-shifting schedule was achieved after optimization. Simulation results show that the method is significant to improve dynamic performance and gear-shifting smoothness theoretically and practically.

Gas-operated Automatic Weapon Variable-mass Thermodynamics Calculation Model

RAN Jing-lu， XU Cheng， ZHAO Yan-jun

2011, 32(4):  408-413.  doi:10.3969/j.issn.1000-1093.2011.04.005

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Aimed at the fact that the energy and mass exchange phenomena existing between barrel and gas-operated device when automatic weapon shooting, for describing the dynamics characteristic of the automatic weapon interior ballistics and gas-operated device accurately, a new variable-mass thermodynamics model was built. It was used to calculate the automatic mechanism velocity of an automatic weapon, and the calculation results were consistent with the experiment results better, thus, the validity of the model was proved. The influences of structure parameters on gas-operated device dynamic characteristics were discussed. It shows that the model is valuable for design and accurate performance prediction of gas-operated automatic weapon.

Study on Vibration Characteristics of Barrel Subjected to Moving Projectile Considering Inertia Effect

SHI Yue-dong， WANG De-shi

2011, 32(4):  414-420.  doi:10.3969/j.issn.1000-1093.2011.04.006

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For investigation of the vibration characteristic of barrel impacted by projectile during firing, its transverse vibration equation considering the inertia effect was established. By using a small parameter method, its series analytical solution was given. For the projectiles with and without mass-unbalance, the vibration characteristics of barrel were numerically simulated for different moving parameters. Some quantitative analysis results were presented, and finally, the response to continual projectile excitation in burst fire was discussed. The simulation results show that the projectile velocity in bore should be reasonably controlled in order to suppress the muzzle vibration in firing. The modeling and analytical methods adopted in this paper are also available for other engineering vibration problems induced by moving loads.

Researches on Safety Assessment Model of Ammunitions

DONG San-qiang, FENG Shun-shan, JIN Jun

2011, 32(4):  421-425.  doi:10.3969/j.issn.1000-1093.2011.04.007

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The main development trend of future ammunitions will be safety. The ammunition safety criteria was proposed on the basis of the effect of main environmental stimulus on the ammunitions safety. A general model for ammunition safety assessment was developed and a parameter of safety degree was introduced to rank the safety of the assessed ammunitions. With the model, the safety of a modified insensitive conventional bomb Mk-82 and the effect of terminal self-failing design for unexploded ordnance (UXO) were analyzed. The results show that the terminal self-failing design can observably improve the safety level of the ammunition. The model in this paper can reflect the safety performance of ammunitions and provides a reference for safety design and evaluation of ammunitions.

A Qualification Test Method for Firing Reliability of Initiator with Small Samples

TIAN Yu-bin， WANG Dian-peng

2011, 32(4):  426-431.  doi:10.3969/j.issn.1000-1093.2011.04.008

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Aiming at the requirement in the initiator's firing reliability，the upper limit of 100% p firing level and the confidence interval of the function margin were given on basis of an optimal experiment design for estimating 100% p firing level. Then, a qualification method for the firing reliability of initiator was provided. Simulation study shows that, based on the optimal experiment design with small sample size, the estimation of 100% p firing level is precise and the result of reliability qualification is reliable but conservative a little bit.

Analysis and Comparison of Pulse Broadening Caused by Atmospheric Turbulence and Dispersion

LU Hong-qiang, ZHAO Wei, XIE Xiao-ping

2011, 32(4):  432-438.  doi:10.3969/j.issn.1000-1093.2011.04.009

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The temporal broadening of optical pulses in satellite-earth laser communication systems. The expression of turbulence-induced pulse width broadening was given, in which the turbulent atmosphere index-of-refraction structure constant, propagation distance, zenith angle and original pulse width were considered. Based on the measured datum of atmospheric parameters, the refractive index in 1.55 μm was derived and the relationship of dispersion-induced pulse broadening to the spectral width, propagation distance, zenith angle, original pulse width and the wavelength of optical signal was obtained. The simulation results show that the turbulence-induced pulse broadening can be neglected for the pulse width greater than 0.5 ps, however, the dispersion-induced pulse broadening can be neglected for the pulse width larger than 20 ps. The received pulse width and maximum achievable bandwidth are calculated in this paper under certain conditions.

A Fast H.264 Inter-frame Prediction Algorithm for Special Mode

LIU Peng-yu, HE Xu, JIA Ke-bin

2011, 32(4):  439-444.  doi:10.3969/j.issn.1000-1093.2011.04.010

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Aimed at higher computational complexity of H.264/AVC due to searching all inter-fame modes based on rate-distortion optimization (RDO), a fast and optimized encoding algorithm was proposed. Analyzed the statistical probability characteristics of different modes appeared in inter-frame，the predictions for special inter-frame modes were carried out to stop unnecessary searching and computing RDO and reduce the encoding time. The simulation results show that the proposed algorithm can reduce total encoding time about 70% averagely, holding almost the same PSNR, bit-rate and output stream structure, compared with the standard H.264 scheme.

A Method for Tracking Object in Infrared and Visible Image Based on Multiple Features

ZHAO Gao-peng, BO Yu-ming， CHEN Yi

2011, 32(4):  445-451.  doi:10.3969/j.issn.1000-1093.2011.04.011

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Aimed at poor stability of tracking object in image by using single feature, a new method was presented for tracking objects in infrared and visible images based on multiple features. It extracted the brightness features in infrared image, the color and texture features in visible image, established an multiple feature object model represented by a set of histogram quantized by kernel function. Then the object representation was combined with the mean shift scheme to realize image tracking, and these features were adaptively fused to obtain a more robust and accurate result according to the similarity measure of Bhattacharyya coefficient. Furthermore, a selective model update mechanism was presented to alleviate the model drift. Experiment results show that the proposed method is effective in complex environment.

Research on Filtered Multi-tone Modulation Underwater Acoustic Communication

RAN Mao-hua， HUANG Jian-guo， HAN Jing

2011, 32(4):  452-458.  doi:10.3969/j.issn.1000-1093.2011.04.012

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In the underwater acoustic OFDM communication, the channel variations may induce inter-carrier interference (ICI) and degrade the system performance significantly. In order to avoid this problem, a novel method named filtered multi-tone modulation (FMT) was introduced to the multi-carrier underwater acoustic communication. FMT can utilize its high spectrum containment to avoid ICI and the inter-symbol interference (ISI) can also be removed by using the fractional DFE equalization method based on the channel estimation in the receiver. Simulations were carried out on the basis of real underwater acoustic channel. The results demonstrate that FMT can get better performance than OFDM under the time-varying underwater acoustic channel and be especially applied to the high data rate communication on the moving platforms.

Research on Sky Polarized Light Distribution

GUAN Gui-xia， YAN Lei， CHEN Jia-bin， WU Tai-xia， Wu Bo

2011, 32(4):  459-463.  doi:10.3969/j.issn.1000-1093.2011.04.013

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Many animals are able to use sky polarized light for navigation. They have a visual nervous system which is extremely sensitive to the sky polarized light, and there exists a perceptible polarization distribution in the sky. However, weather conditions, sun’s position and detection wavelength will affect the polarization pattern in a certain extent. They will cause the instability of the sky polarization distribution. As a result, it will reduce the polarization navigation usability. In this paper, we focus on the relationship between these factors and the sky polarization distribution. Using full-sky polarization instrument, we measured sky in full-band, red, blue, purple bands under different weather conditions. The results show that the sky polarization distribution is closely related to the sun altitude, weather conditions and detection band. The distributions of sky polarized light are different under different weather conditions and detection bands. The blue band is more suitable for the polarization navigation. This study will provide not only the basic theory to improve the precision of the polarized light navigation, but also a reference for atmosphere polarization remote sensing detection.

Design and Analysis for Magnetic Field Configuration of Electromagnetic Coil Launcher

ZHU Ying-wei, LI Hai-tao, YAN Zhong-ming, FU Lei, WANG Yu

2011, 32(4):  464-468.  doi:10.3969/j.issn.1000-1093.2011.04.014

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The magnetic field configuration design of driving coil is the basic and key technique in electromagnetic coil launcher. This paper firstly presents the concept of magnetic field configuration and indicates the design guidelines. The expression of acceleration force is deduced. Using the finite element method, the magnetic field configurations of solenoids with different ratios of thickness to length are simulated numerically. The mutual inductance between driving coil and projectile is calculated and the electromagnetic force is considered along with position change. The magnetic field configurations of solenoids with different geometrical sections are calculated and compared. The influence of geometrical section on electromagnetic force is analyzed. The result indicates that the solenoid with square section has the biggest acceleration force at the same ampere-turn in the magneto-static field.

An Effective Method of Threshold Selection for Small Object Image

WU Yi-quan, WU Jia-ming, ZHAN Bi-chao

2011, 32(4):  469-475.  doi:10.3969/j.issn.1000-1093.2011.04.015

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Segmentation difficulties of small object images often occur in target detection and recognition, where the object is much smaller than its background. The existing threshold methods almost fail. Thus, a threshold selection method is proposed on the basis of the area difference between background and object and within-class variance. The threshold selection formulae according to one-dimensional histogram, two-dimensional histogram vertical segmentation and two-dimensional histogram oblique segmentation are given. A fast recursive algorithm of threshold selection in two-dimensional histogram oblique segmentation is derived. The segmented images and processing time of the proposed method are given in experiments. It is compared with some fast algorithms, such as Otsu, maximum entropy and Fisher threshold selection methods. The experiment results show that the proposed method can effectively segment the small object images and has better anti-noise property.

Study on a Novel Capacitive Pressure Sensor

LI Xin-e， ZU Jing， MA Tie-hua, XU Peng

2011, 32(4):  476-481.  doi:10.3969/j.issn.1000-1093.2011.04.016

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As the electronic pressure gauge shell is an elastic component, it can be used as an elastic sensitive component to design a novel capacitive pressure sensor. The working principle and structure design of the sensor are elaborated in this paper, and its mechanical properties, capacitance are calculated teoretically and simulated by using ANSYS, Finally, the experiment validation is carried out. The results show that the capacitive pressure sensor has very good linearity and its sensitivity is about 0.096 pF/MPa.

Design on Integral Cathode and ECM Device with Multiple Workplaces

FAN Zhi-jian， ZHAO Gang-gang， ZHANG Li-juan

2011, 32(4):  482-486.  doi:10.3969/j.issn.1000-1093.2011.04.017

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A electrochemical machining (ECM) device with an integral cathode was designed to realize machining and shaping contemporaneously for complex groove in multiple workplaces. The structure parameters were optimized after experiments. Based on Laplacian inverse problem of cathode design, the gap potential distribution was calculated by using software ANSYS 8.0 from rudiment cathode obtained according to cosθ method. The cathode boundary was modified according to the difference between the calculation and actual results, and the iteration was carried out repeatedly. The experiment results indicate that the machined workpiece coincides well with the blueprint.

Effects of Tangential Ultrasonic Vibration on Grinding Force of Single Abrasive Grit

ZHANG Hong-li, ZHANG Jian-hua

2011, 32(4):  487-492.  doi:10.3969/j.issn.1000-1093.2011.04.018

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Based on the kinematics analysis and the cutting depth calculation for single abrasive grit, the mathematical models of the dynamic cutting force and the average cutting force were established by introducing the unit grinding force F_u. And the formula of the average cutting force in the grinding zone was derived. The experiments were conducted in the conventional grinding (CG) mode and tangential ultrasonic vibration assisted grinding (TUAG) mode. The results show that the unit grinding force in TUAG is lower than that in CG under the same machining condition; the grinding force ratio decreases due to the tangential ultrasonic vibration of the workpiece. It is helpful to improve the machinablity of the hard-brittle material. The simulation results of the model give a good agreement with the experiment results, and the correctness of the model is verified.

Research Notes

Application of Adaptive Backstepping Sliding Mode Controlin in Alternative Current Servo System of Rocket Gun

GUO Ya-jun, WANG Xiao-feng, MA Da-wei, LE Gui-gao

2011, 32(4):  493-497.  doi:10.3969/j.issn.1000-1093.2011.04.019

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A adaptive backstepping sliding mode control approach was introduced to control the pitch motion of a rocket gun. Its control law was proposed to guarantee that the control system was ultimately bounded in a Lyapunov sense and make the servo system could track the instruction of reference position globally and asymptotically. In addition, the sliding mode control can restrain effects of parameter uncertainties and external disturbance. The functions of adaptive mechanism and sliding mode control were analyzed by using simulation under different conditions. The simulation results illustrate that the method is applicable and robust.

Complex Refraction Indices of Expanded Graphite Deduced from Its Reflection Spectra in Infrared Band

DOU Zheng-wei, LI Xiao-xia, ZHAO Ji-jin

2011, 32(4):  498-502.  doi:10.3969/j.issn.1000-1093.2011.04.020

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The expanded graphite (EG) with good extinction performance can be used as elect

Reconnaissance Technology of Catadioptyic Panoramic Vision for Combat Robot

MA Zi-ling, WANG Jian-zhong

2011, 32(4):  503-507.  doi:10.3969/j.issn.1000-1093.2011.04.021

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To meet the demands of real-time panoramic reconnaissance, the catadioptric panoramic vision was investigated. A model of hyperboloidal catadioptric panoramic vision was built, and equations of correlative parameters were obtained by analyzing their relations, the relationship between distance and resolution was analyzed. Some values of parameters were set according to the background and the present techniques to quantitatively analyze the relations among system parameters. Simulation and experiment were carried out. The results indicate that the targets in farther position can be detected by using this technique panoramically.

A Estimation Method for Kill Probability Based on Random Residence Time Series

LIU Chao, WANG Jun , GUO Zhi

2011, 32(4):  508-512.  doi:10.3969/j.issn.1000-1093.2011.04.022

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The relations between statistical residence time series and effective shooting were analyzed in accordance with the properties of random residence time of maneuver target crossing shot area in a fixed time. An estimation method for kill probability was proposed, according to the probability of number of residence times satisfied effective shooting in given time. The expressions and their approximating formula of kill probability were derived, under known the distribution of residence time series. Theoretical analysis and simulation results show that this method is suitable for evaluating the hit ability of fire system for shooting maneuver targets in random shooting.