Table of Content

31 July 2015, Volume 36 Issue 7

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Paper

Comparison of Steady and Dynamic Models for the Bulk Modulus of Hydraulic Oils

WEI Chao, ZHOU Jun-jie, YUAN Shi-hua

2015, 36(7):  1153-1159.  doi:10.3969/j.issn.1000-1093.2015.07.001

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Fluid bulk modulus has important effect on the dynamic characteristics of the hydraulic system, but the existing models still cannot accurately capture the dynamic features when the fluid is compressed or expands rapidly. Four steady-state models (Wylie, Nykanen, Ruan and AMESim) of fluid bulk modulus based on lumped parameter approach are analyzed. Considering the dynamic transport processes of free air and vapor in the oil, a dynamic effective bulk modulus model which is time-dependent is derived. In addition, the difference among the four steady-state models both in the high and low pressure regions is studied. The proposed dynamic model is compared to AMESim model and validated using experimental data. Results show that Wylie model is close to Nykanen model in the whole pressure range since they both assume constant air contents. In the high pressure region, Ruan model predicts a slight larger fluid bulk modulus, while AMESim model performs most differently and is strongly affected by the air apart pressure. In the low pressure region, the values of Ruan Model and Wylie Model are very close, but the effective bulk modulus calculated by AMESim model is nearly zero when the pressure is lower than the vapor saturation pressure, the fluid bulk modulus-pressure curve— predicted by the proposed dynamic model seems more reasonable when Henry’s law is used, although its advantage depends on the coupling with the dynamic transport equations. Finally, the comparison of the results obtained from a fluid compression and expansion test cycle indicates that the proposed model is more precise.

Design Knowledge Representation Technique for Self-propelled Artillery Based on Ontology and Knowledge Components

YANG Liu， QIAN Lin-fang， DING Sheng-chun， XU Ya-dong

2015, 36(7):  1160-1166.  doi:10.3969/j.issn.1000-1093.2015.07.002

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For the problem of that the various design knowledges of self-propelled artillery have not been organized and represented effectively and the existing design knowledge cannot be reused simply during the design process, a knowledge representation method is proposed based on ontology and knowledge components. The organization mode for design ontology of self-propelled artillery and the developing strategy for knowledge components are studied on the base of analyzing the representation requirement of design knowledge of self-propelled artillery, and the mapping relationships among design ontology and knowledge components are established. The representation of design knowledge of self-propelled artillery is achieved. On this basis,a special knowledge retrieval system is developed for designers to quickly reuse the existing design knowledge. The representation and reuse of design knowledge are implemented by taking large-caliber self-propelled artillery for example. The result shows that the proposed method is feasible and valid.

Research on Melted and Rapidly Solidified Layer on the Surface of Crater Penetrated by Long Tungsten Rod

LUO Rong-mei， HUANG De-wu, YANG Ming-chuan, HUANG Hai, LI Fu-ying

2015, 36(7):  1167-1175.  doi:10.3969/j.issn.1000-1093.2015.07.003

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A thin surface layer, called melted and rapidly solidified layer, is formed when tungsten long rod penetrates into armor at high velocity. When the 30CrMnMo target is shot by a small caliber long rod armor piercing projectile at 0°angle, a crater is formed on the target. In order to investigate the morphology characteristics and forming mechanism of MRSL, the surface of the crater is observed by scanning electron microscopy and analyzed by energy spectrum. LS-DYNA is used to simulate the temperature field of the interaction area between penetrator and target. It is shown that MRSL consists of W, Ni and Fe elements, which are contained in long rod material, and Fe, Cr and Mn elements, which are contained in target material. In MRSL, tungsten grains have two kinds of size: the big one is of long and flat shape, and its length is in the range from several micrometers to dozens of micrometers; the small one is dispersed in matrix with 100~400 nm in diameter. The mass consumption of long rod head is happened in the form of “melted and broken”.

Roll Damping Simulation of Missile Body and Anti-rotation Flaps

ZHAO Yang-zheng， JIANG Sheng-ju， DANG Ming-li， ZHU Zhong-gen

2015, 36(7):  1176-1180.  doi:10.3969/j.issn.1000-1093.2015.07.004

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Roll damping derivative is an important aerodynamic parameter which affects the despinning effect of a missile. Steady CFD simulations are used to predict the roll damping characteristics of the missile with anti-rotation flaps at subsonic and transonic speeds. The predicted roll damping derivatives are in good agreement with the experimental data. The variation of the angle of attack and the surface pressure of wings due to rolling and the roll damping moment induced by additional wing lift are explained through numerical analysis. The bending location of the thin wings is shown. From the view of flow field, the influence of spinning on gas flow nearby the body of missile, the bending of surface streamline and the helical-like streamline pattern in the wake are demonstrated.

Noise Reduction of Acoustic Signals from Armored Vehicles Based on CDBI-LPM

DING Kai，QIAN Han-ming，CHEN Guo，RONG Ying-jiao，ZHU Yi-chao，SHI Jun-chao

2015, 36(7):  1181-1187.  doi:10.3969/j.issn.1000-1093.2015.07.005

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A correlation dimension-based iteration-local projective method（CDBI-LPM）is proposed to reduce the noise in the acoustic signals from the armored vehicles and eliminate the harmful effects on feature extraction． 20 dB and 10 dB（SNR）noisy signals are obtained by adding the different Gaussian white noises to the Lorenz sequence of a typical chaos system．The noise reduction simulation results show that the proposed method not only reduces the amount of computation，but also efficiently recovers the dynamic structure of Lorenz system．The application of the method in the noise reduction of actual acoustic signals from tanks and wheeled armored vehicles shows that the noise intensities of sample signals are significantly reduced，the correlation dimensions decrease，and the disorder attractor structures of the signal series get order as well．This indicates that the proposed method could efficiently reduce the noise in the nonlinear signals.

Impact Point Prediction of Terminal Correction Projectile Based on Linear Trajectory Model

LI Xing-long, JIA Fang-xiu, WANG Xiao-ming, YAO Wen-jin, WU Wei

2015, 36(7):  1188-1194.  doi:10.3969/j.issn.1000-1093.2015.07.006

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A method of linearizing the 6 degrees of freedom(DOF) rigid trajectory model is proposed for the rapid impact point prediction of terminal correction projectile in terminal trajectory. The linearized trajectory equations and the analytical solution are obtained, and The analytic formula for rapid impact point prediction is derived in combination with the remaining flight arc length estimation formula. With the reference of 6 DOF trajectory, the prediction accuracy and calculation time of this linear trajectory model prediction method are analyzed at different firing angles and prediction points through simulation. The results show that the impact point prediction error is less than 8 m in cross range direction, the solution speed is improved by an order of magnitude compared to 3DOF numerical integral impact point prediction method. The proposed method provides the basis for rapid ballistic calculation in real-time by onboard computer, and also provides a reference for the engineering application of terminal correction projectile.

Hopf Bifurcation Analysis of Nonlinear Angular Motion Stability of Projectile

ZHONG Yang-wei, WANG Liang-ming, FU Jian, CHANG Si-jiang

2015, 36(7):  1195-1202.  doi:10.3969/j.issn.1000-1093.2015.07.007

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In order to analyze the angular motion stability of projectile, the equations of the nonlinear angular motion are derived, and the Hopf bifurcation analysis method of the nonlinear angular motion of projectile is given. Taking a rocket plateau test as an example, the air density is selected as the bifurcation parameter, and the Hurwitz criterion is used to judge the stability of the system. The bifurcation point is determined. Center manifold theory is proposed to reduce the system dimension, and then a three-order normal form of Hopf bifurcation is calculated by plotting the bifurcation diagram. In addition, the effect of the bifurcation parameter on the swing of the limit cycle is analyzed. The numerical simulations show that the bifurcation analysis method can be used to judge the stability of the system correctly and analyze the motion of limit cycle in the system accurately.

Optimal Guidance Law with Impact Angle Constraints Based on Indirect Gauss Pseudospectral Method

CHEN Qi， WANG Zhong-yuan， CHANG Si-jiang

2015, 36(7):  1203-1212.  doi:10.3969/j.issn.1000-1093.2015.07.008

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A novel optimal guidance law is proposed for the terminal guidance with impact angle constraints by using the combination of the minimal principle and Gauss pseudospectral method. An impact angle coordinate system is defined with an coordinate axis in the direction of the desired impact angle, and the linear engagement kinematics is established using this coordinate system. The control system of missile is simplified into a first-order inertial system. The canonical equation is obtained via the minimal principle, and then translated into a set of algebraic equations by employing the Gauss pseudospectral method. According to the boundary conditions, an analytical solution is finally derived for the optimal guidance law with impact angle constraints without any integral process or solving the Riccati differential equation. Numerical simulations show that the proposed guidance law ensures the much fast convergence of impact angle to the reference line, and has smaller required terminal acceleration compared with other guidance laws. In addition, the proposed guidance law can easily tackle with the guidance problem with complex weighting matrices.

Research on Partial Image Recognition and Tracking in Infrared Imaging Terminal Guidance

LI Cheng， LI Jian-xun， TONG Zhong-xiang， JIA Lin-tong， ZHANG Zhi-bo

2015, 36(7):  1213-1221.  doi:10.3969/j.issn.1000-1093.2015.07.009

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A new method for partial image recognition and tracking in the infrared imaging terminal guidance is proposed for the problem of that the field-of-view of infrared seeker filled with target affects target recognition and tracking. The principle of infrared imaging guidance is analyzed. Five characteristic quantities, such as highlight region proportion, standard deviation of gray value, length-width ratio, compactness and complexity, are used as the criteria of feature extraction and target recognition. A fast target recognition algorithm suitable for missile is proposed. The change of target image projection area on seeker’s focal plane in the infrared imaging terminal guidance is calculated. The effects of missile-target distance and relative velocity on aircraft imaging are analyzed. The switching from centroid tracking to partial image tracking is studied. Considering reliability and real-time, the nose cone of aircraft is selected as the tracking point for partial image tracking. The simulation scene of infrared imaging guidance is built. The simulation results are analyzed. Experimental results show that the proposed method can effectively recognize the targets in the infrared images, decrease the blind area, and realize the steadily tracking in the infrared imaging terminal guidance.

Analysis and Compensation of Installlation Axial Angle Errors of Semi-strapdown IMS

ZHANG Xi, LI Jie, HOU Li-peng, ZHU Jing-de, QIN Li

2015, 36(7):  1222-1227.  doi:10.3969/j.issn.1000-1093.2015.07.010

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The source and gemeration mechanism of installation axial angle errors of semi-strapdown inertial measurement system (IMS ) and their effects on the attitude measuring accuracy are analyzed, and the mathematical expression of the influence is theoretically derived. A graded compensation method is proposed for error compensation. The proposed method is used to compensate the installation angle errors in turn according to their generation principle and effect mechanism. Experiment based on semi-strapdown IMS verified the validity and effectiveness of the method. Experimental results show that the method can effectively reduce the periodic attitude measuring error caused by installation axial angle errors to 0.05° compared with that of 0.32°without compensation.

Dynamic Response of Cold Launching System and Optimization of Hydro-pneumatic Suspension

YAO Lin， MA Da-wei， WANG Xi, ZHU Zhong-ling， HE Qiang

2015, 36(7):  1228-1236.  doi:10.3969/j.issn.1000-1093.2015.07.011

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In order to improve the accuracy of missile launch under the whole tire supporting cold emission mode, the mathematics equations of four-axle-interconnected hydro-pneumatic suspension are derived to verify the correctness of simulation model established by AMESim. A co-simulation model that takes the root-mean-square value of launch tube end as an optimization target is built by using ADAMS/Simulink/AMESim, and the optimized result is obtained by using genetic algorithm. The initial pressure, total volume of the accumulator and the diameter of damper-hole are selected as design variables. The working conditions of that the vehicle slant angle is 0° and the missile erecting angle is 900°are studied. The results show that the RMS of launch tube end is decreased by 61.1%, and the accuracy of missile launch is greatly improved. Besides, the pitching angle and load distribution are more reasonable, which increase the stability of launching system. The accuracy of missile launch and the stability of launching system can be both raised by using co-simulation with multiple softwares based on genetic algorithm.

Static Projective Control of Fly-wing UAV Considering Wind Disturbance

ZHU Yi， CHEN Xin， LI Chun-tao， YANG Yi

2015, 36(7):  1237-1246.  doi:10.3969/j.issn.1000-1093.2015.07.012

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According to the unusual conformation and aerodynamic characteristic of flying-wing UAV, as well as the requirement of control quality, a static projective control system is designed based on robust and optimal theories considering wind disturbance. Both pitch loop of longitudinal motion and bank loop of lateral motion are taken into account with projective controllers. The general principles of projective control are analyzed. Then the robust-servo model is established and an optimal closed loop system is obtained by LQR state feedback method. The eigenvalues and eigenvectors of closed loop system are treated as a reference structure for static projective control. The aim of adopting static projective control is rebuilding the reference structure by output feedback as a substitute for LQR state feedback. The output feedback is used to ensure the measurability of the variables in engineering application. The final simulation acts as a comparison of PID attitude autopilot and static projective controller with three kinds of wind disturbance. The result shows that the designed system has excellent transient performance and satisfactory anti-disturbance ability.

Hot-swap Modular Redundancy and Fault Tolerant Technology for CPCI Measurement and Control Systems of Weapon Equipment

LI Dan, HU Xiao-guang

2015, 36(7):  1247-1255.  doi:10.3969/j.issn.1000-1093.2015.07.013

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The status of domestic and abroad researches on high-availability fault tolerance of measurement and control systems is analyzed, and a design of high-availability hot-swap based on compact PCI (CPCI) bus is proposed to solve the problems in applying and testing the modular redundancy and fault tolerance in the measurement and control systems of weapons. A semi-physical simulation platform that could test the hot-swap and hot-redundant systems is developed to verify and analyze the reliability of a controlled object in experimental hot-swap systems. The result shows that the system is stable and excellent. The observability of different objects in hot-swap and hot-redundant systems is achieved by studying the high-availability hot-swap and hot-redundant systems.

Carrier Sense Random Packet Code Division Multiple Access Protocol and Its Intra-cluster Multiple Access InterferencePerformance Analysis

DU Chuan-bao, QUAN Hou-de, MA Wan-zhi, CUI Pei-zhang, WANG Xiao-ming

2015, 36(7):  1256-1265.  doi:10.3969/j.issn.1000-1093.2015.07.014

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In tactical scenarios, the dual-channel networking scheme designed for a certain type radio can solve the serious waste of code resource significantly, which is caused by the traditional code networking scheme. The random packet CDMA technology is used to enhance the anti-jamming capability of control channel of dual-channel networks, and a new MAC protocol, called carrier sense random packet CDMA, is proposed. A performance analytical model of slotted spread spectrum ad hoc networks based on CSRP-CDMA is established, which provides packet transmission success probability and expressions of network throughput. And the influences of the factors, such as spreading gain, packet header and payload ratio, received signal-noise ratio, on network performance are analyzed. Finally, CSRP-CDMA protocol is compared with the traditional MAC protocol for RP-CDMA by network simulator OPNET. Numerical and simulation results show that CSRP-CDMA protocol has higher network performance than the traditional MAC protocol, and the theoretical normalized network throughput value of CSRP-CDMA can reach 0.75 to guarantee the resource utilization of control channel effectively.

An Time Delay Difference Estimation Algorithm Based on Improved Unscented Particle Filter Suitable for Target Tracking inWireless Sensor Network

ZHU Ming-qiang， HOU Jian-jun, LIU Ying ， LI Xu, TIAN Hong-juan

2015, 36(7):  1266-1272.  doi:10.3969/j.issn.1000-1093.2015.07.015

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For the time delay difference tracking estimation methods based on particle filter in wireless sensor network(WSN) , the key issue is to generate an accurate proposal distribution for particle filter. An time delay difference estimation algorthm based on improved unscented particle filter (IUPF) is proposed to overcome the degeneracy phenomenon of particles. The least square method is used to achive the initial target position, and then the unscented particle filter (UPF) and Gauss-Newton rule are used to incorporate the most current observations and provide more accurate importance density function for the particle filter by introducing a scaled correction factor．Finally, IUPF is applied to the time delay difference localization estimation methods in WSN. The simulation results show that, when the particle number is limited, the proposed algorithm can improves the target tracking accuracy and achieve faster convergence speed under non-Gauss noise environment in WSN.

Dim Moving Target Detection Algorithm Based on Spatial-temporal Sparse Representation

LI Zheng-zhou, HOU Qian, DAI Zhen, FU Hong-xia, GE Feng-zeng, JIN Gang

2015, 36(7):  1273-1279.  doi:10.3969/j.issn.1000-1093.2015.07.016

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A dim moving target detection algorithm based on over-complete spatial-temporal dictionary and sparse representation is proposed. A spatial-temporal adaptive morphological over-complete dictionary is trained and constructed according to infrared image sequence. It can represent the motion information and morphological feature of target and background clutter. The spatial-temporal morphological over-complete dictionary is subdivided into two categories: target over-complete spatial-temporal dictionary for describing moving target, and background over-complete spatial-temporal dictionary for embedding background. The criteria adopted to distinguish the target spatial-temporal redundant dictionary from the background spatial-temporal redundant dictionary is that the atom in target over-complete spatial-temporal dictionary could be decomposed more sparsely over Gaussian over-complete spatial-temporal dictionary. Subsequently, the image sequence is decomposed on the target and background over-complete spatial-temporal dictionaries, respectively. The dim moving target and background clutter can be sparsely decomposed on their corresponding over-complete spatial-temporal dictionary, yet it couldn’t be sparsely decomposed on their background over-complete spatial-temporal dictionary. Therefore, the target and background clutter would be reconstructed effectively by prescribed number of atoms with maximum sparse coefficients in their corresponding over-complete spatial-temporal dictionary, and their residuals would differ so visibly to distinguish target from background clutter. The results show that the proposed approach not only could improve the sparsity more efficiently for dim target image sequence, but also could improve the performance of small target detection.

A Multi-modulus Blind Equalization Algorithm Based on Shuffled Frog Leaping Algorithm

GUO Ye-cai， ZHANG Miao-qing

2015, 36(7):  1280-1287.  doi:10.3969/j.issn.1000-1093.2015.07.017

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For slow convergence speed, large steady mean square error (MSE), and blind phase of the constant modulus blind equalization algorithm (CMA), a multi-modulus blind equalization algorithm based on shuffled frog leaping algorithm (SFLA-MMA) is proposed, which combines the basic idea of intelligent optimization algorithm and introduces the individual own evolution and social behavior among individuals into the blind equalization technology. In the proposed algorithm, the reciprocal of the cost function of multi-modulus blind equalization algorithm (MMA) is defined as the fitness function of the shuffled frog leaping algorithm (SFLA), the position vector of the frog individual in the frog group is regarded as the initial weight vector of MMA. The optimum location vector of the frog groups is searched using the global information sharing mechanism and local depth search ability of SFLA, and used as the initial optimum weight vector of the MMA. The optimal weight vector of MMA is obtained by updating the weight vector of MMA . The proposed SFLA-MMA is simulated with the higher-order multi-modulus QAM and APSK signals. The simulation results show that, compared with CMA, MMA, and the multi-modulus blind equalization algorithm based on particle swarm optimization algorithm (PSO-MMA), the proposed SFLA-MMA has the fastest convergence speed, the smallest MSE, and the clearest constellations of output signals.

Speckle Suppression of Polarimetric Synthetic Aperture Radar Images Based on Sublook Data Correlation

LIU Kun, MA Wen-ping, LIU Hong-ying

2015, 36(7):  1288-1294.  doi:10.3969/j.issn.1000-1093.2015.07.018

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A new non-local filter based on the sublook data correlation is proposed for the speckle suppression of multilook polarimetric synthetic aperture radar (PolSAR). Non-local techniques search for patches similar to the reference patch in a spatially extended neighborhood, and process the image with weighted averaging method based on the similarity. Therefore, similarity measurement plays an important role for non-local approaches.The sublook data of multilook PolSAR samples contain more correlation information than just the samples themselves, which could benefit the effectiveness of the similarity measurement in non-local filters. The proposed filter measures the correlation of two groups of sublook data in order to find the patch-based similarity. Then the homogeneous samples are selected to suppress the speckle based on the similarity. Experimental results and comparison with other filters illustrate an outstanding performance of the proposed filter.

Study of the Magnetic Field Measurement of Electric Cable with Electrodes in Seawater

SHI Jian, LIU Zhong-le, WEN Wu-di

2015, 36(7):  1295-1301.  doi:10.3969/j.issn.1000-1093.2015.07.019

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The shape of electric cable quitely differs from that of straight wire in the process of measuring the magnetic field of electric cable with electrodes in seawater, so it cannot be checked by the models of straight wire. For this question, the formula is improved by analyzing the difference between straight wire and electric cable in seawater, and the original and improved formulas are compared through simulation calculation. Comparison of calculated and measured values shows that the improved formula has smaller error, and it's more applicable to the checking of the magnetic field of electric cable with electrodes in seawater.

Determination and Strategies of Effective Dispersion Time Interval of Chaffs in Outer Space

LIU Yun, ZHANG Cui-xia, YAN Ru-xiang, ZHU De-long

2015, 36(7):  1302-1308.  doi:10.3969/j.issn.1000-1093.2015.07.020

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The diffusive movement and effective dispersion time interval models in multi-radar environment are established to improve the utility efficiency of outer space chaff dispersion in the thin air according to the movement characteristics of chaffs and the detection performance of radar. The numerical calculation about the chaff movement process dispersed at a specific time interval is carried out,and the influence of chaff release time on jamming effect is obtained. The different dispersion time interval strategies based on radar importance are discussed, and the effective dispersion time interval strategies under different conditions are proposed. The results indicate that the variation in dispersion time interval of chaff cloud has a great influence on the chaff working efficiency and the different mission requirements can be met by adjusting the dispersion time.

Identification of Joint Part Parameters of HSK Spindle-toolholder Based on Closed-form Approach

CHEN Jian, TIAN Liang , SHANG Hong-mo , ZHENG Deng-sheng, WANG Gui-cheng

2015, 36(7):  1309-1317.  doi:10.3969/j.issn.1000-1093.2015.07.021

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The basic condition for predicting the dynamic performance of spindle system and keeping the cutting stability is to identify the parameters of HSK spindle-toolholder joint part. HSK spindle-toolholder joint part is simplified as spring-damp model. According to the frequency response function(FRF) matrix of HSK spindle-shrink toolholder system, the stiffness matrix of HSK spindle-toolholder is derived. the FRF matrix of shrink toolholder is obtained based on coupling response method. The FRF matrixes of the tip points of HSK spindle and HSK spindle-shrink toolholder system are got by using finite difference method and experiment. Four stiffness parameters (k_yf, k_θf, k_ym and k_θm) and four damp parameters (c_yf, c_θf, c_ym and c_θm) are identified with the stiffness matrix. FRF of tip point of HSK spindle-toolholder system is achieved by using the coupling response method. The calculated frequency of HSK spindle-toolholder system is compared with the experimental frequency. The maximal difference between theoretical and experimental results is 7.9%.

Stability Analysis of the Separated Longitudinal-torsional Composite Ultrasonic Milling

TANG Jun， ZHAO Bo

2015, 36(7):  1318-1325.  doi:10.3969/j.issn.1000-1093.2015.07.022

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The motion characteristics of separated longitudinal-torsional composite ultrasonic milling are analyzed based on the kinematics synthesis principle，and the essential characteristics of reducing the cutting force, promoting the chip removing and improving the tool life are elucidated. The dynamic model and the stability region analytical model of the separated longitudinal-torsional composite ultrasonic milling are constructed based on the theory of structural dynamics by considering the effects of longitudinal-torsional composite ultrasonic vibration. On the basis of that, the stability lobe diagram of cutting system is obtained by using the software MATLAB 7.1. the carbon fiber composite material is used for the experimental study. The experimental results show a good agreement with the numerical results, thus confirming the correctness of theoretical model and stability lobe diagram.

Research on the Failure Probability Models and Life Probability Characteristics of Systems with Dependent Failure

WANG Zheng, WANG Zeng-quan, XIE Li-yang

2015, 36(7):  1326-1333.  doi:10.3969/j.issn.1000-1093.2015.07.023

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The effect of failure dependence on the failure probability characteristics of systems is taken into account, and the system strength probability distribution models of series system and parallel system are derived from the system level, respectively. The failure probability models of series and parallel systems, which can embody the effects of parameters, such as system composing structure, load, strength, and so on, are developed by taking continuous variable and discrete variable as the life parameters, respectively. The life probability characteristics of series and parallel systems are studied. The results show that the mean time to first failure (MTTFF) of parallel system is not only more than that of series system but also more than those of the components that compose the system, and the MTTFF of series system is less than those of the components.

Research on Two-echelon Spare Parts Inventory Systems with Lateral Transshipments

LIU Shao-wei， GUAN Jiao， WANG Jie， SHU Tao， FENG Gang

2015, 36(7):  1334-1339.  doi:10.3969/j.issn.1000-1093.2015.07.024

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Multi-echelon spare parts inventory systems with lateral transshipments make the traditional tree-like supply mode become a flat structure, which can shorten the average waiting time of spare parts. The multi-echelon spare parts inventory system is analyzed to build a multi-echelon spare parts inventory model with lateral transshipments, and the related important parameters, including spare fill rate, lateral transshipment probability and probability of shortage, are evaluated based on M/M/∞ queue model. A heuristic algorithm is used to minimize system-wide spare parts. The experiment shows that the two-echelon support cost with lateral supply can be reduced by 39.4% by introducing the lateral supply strategy.

Study of Combustion Characteristics of Dimethyl Ether Based on a Rapid Compression Machine

SHI Zhi-cheng, LIU Hao, ZHANG Hong-guang, LU Hai-tao

2015, 36(7):  1340-1346.  doi:10.3969/j.issn.1000-1093.2015.07.025

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In order to investigate the combustion characteristics of dimethyl ether (DME)， the experiments are conducted under the initial temperature of 293 K, the driving gas pressure of 0.6 MPa, the initial pressure of 0.04~0.08 MPa, the nitrogen dilution ratio of 47.29~60.81% and the compression ratio of 8.82~12.02. The effects of the initial pressures， nitrogen dilution ratio and compression ratio on the ignition delay time and peak combustion pressure of the DME-O₂-N₂ mixtures are investigated using a rapid compression machine (RCM). The two-stage heat release and two-stage ignition delay time are observed. The negative temperature coefficient (NTC) behavior of the mixtures is observed with the increase in compression ratio. The temperature in the presence of NTC increases with the increase in initial pressure. The temperature in the presence of NTC decreases with the increase in nitrogen dilution ratio. Under a certain initial pressure， with the increase in nitrogen dilution ratio， the peak combustion pressure and the second ignition delay time show the opposite trend under different compression ratios. Under a certain nitrogen dilution ratio，with the increase in compression ratio，the peak combustion pressure and overall ignition delay time show the opposite trend under different initial pressures.

Study of Friction Torque of Needle Roller Thrust Bearings

DENG Si-er, LI Meng, LU Yu-jia, DAI Yan-bin

2015, 36(7):  1347-1355.  doi:10.3969/j.issn.1000-1093.2015.07.026

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The dynamic differential equations of needle roller thrust bearings are established based on the dynamic theory of rolling bearings. The precise integration method and the predicting-correcting Adams-Bashforth-Moulton multistep method are used to solve the equations, and the friction torque mathematic models of needle roller thrust bearings are built. The influences of working conditions and structural parameters on the friction torque of needle roller thrust bearings are investigated. The results show that the slip friction between roller and raceway is main component of the friction torque of needle roller thrust bearings.the friction between cage and roller also becomes the main component at high speed , and a small pocket clearance is in favor of reducing the friction torque. An optimal speed can be selected, which makes the friction the smallest. The friction torque is in direct proportion to the axial load, and the proportional coefficient decreases with the rise of rotating speed of bearings. The roller profile modification can reduce the friction torque evidently, the full arc profile modification is the most propitious to reduce the friction torque compared to crowned shapes.the friction torque increases with the rise of roller number and effective length , and the friction torque decreases with the rise of the roller diameter. These parameters should be rationally optimized to reduce the friction torque.

Research Notes

Analysis of Kinetic Characteristic Matching of 5.8mm/7.62mm Modularized Rifles

ZOU Yan, XU Cheng, ZHANG Ke

2015, 36(7):  1356-1362.  doi:10.3969/j.issn.1000-1093.2015.07.027

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The matching of alterable caliber rifle is the key problem of the development of alterable caliber modularized rifle system. The numerical simulation models are established for 5.8 mm and 7.62 mm caliber rifles, and the numerical simulation models are verified by comparing the simulation results with the experimental results. The kinetic characteristic matching of bolt carrier, the ammunition feed matching and the ejection matching are analyzed based on the models. The matched-degree principle of the bolt carrier’s kinetic characteristic matching is built, and according to this principle, a reasonable design project is selected. The result shows that the kinetic characteristic matching of the bolt carrier can be achieved well by changing the diameter of the gas chamber; the stability of ammunition feed and the ammunition feed matching can be improved by changing the angle of ammunition feed slope and the rounding edges; and the change in the position of the ejection port is an efficient measure of ejection matching.

Influence of Structure Parameters of Forcing Cone on Small Arms Interior Ballistics During Engraving

LU Ye, ZHOU Ke-dong, HE Lei, LI Jun-song, HUANG Xue-ying

2015, 36(7):  1363-1369.  doi:10.3969/j.issn.1000-1093.2015.07.028

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The working condition of barrel forcing cone is worse during the firing process of small arms. To study the influence of the forcing cone angles on the stress of barrel forcing cone, the three-dimensional finite element models of barrel and projectile at different forcing cone angles are established, in which the structures of barrel and projectile, and nonlinear constitutive relations are considered. The effects of different forcing cone angles on the projectile engraving process are analyzed. The data of engraving resistance is obtained under the condition of different forcing cone angles. A response surface model of engraving resistance is established. The formula and the variation rules of projectile engraving resistance along with the forcing cone angle and engraving displacement are calculated based on the above data by using Hermite polynomial. A dynamic model of projectile engraving process is established in consideration of the engraving resistance. The engraving pressure during the projectile engraving process is solved by programming. The forcing cone angles among 0.11° and 1.13°, which satisfy the requirement of muzzle velocity of the projectile, are obtained, and then the best forcing cone angle of 0.56°, which could reduce the barrel stress to ensure the highest velocity and meet the design range of forcing cone angles in case of satisfying the interior ballistic behaviors, is got.

Analysis of Acquisition Probability of Rocket-assisted Torpedo in Different Salvo Modes

TIAN Heng-dou， HOU Dai-wen， FANG Yi， SUN Wen-hao

2015, 36(7):  1370-1376.  doi:10.3969/j.issn.1000-1093.2015.07.029

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The acquisition probability declines dramatically when the rocket-assisted torpedoes attack a distant target. To solve this problem, the salvo mode of artificial scatter, which is different from traditional salvo, is presented according to the searching mode of rocket-assisted torpedo and the features of antisubmarine operation. The analytical models for two kinds of salvo modes are developed based on the basic idea of total probability. The acquisition probabilities at different shooting ranges under the operation modes of attacking the prepositive point and current point of torpedo are calculated by two models, respectively. The results agree well with the simulation test results. When the current point shooting mode is adopted, the acquisition probability using the salvo mode of artificial scatter is higher than that by traditional salvo at long shooting range.