Table of Content

19 November 2018, Volume 39 Issue 11

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Contents

2018, 39(11):  0. 

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Paper

Analysis of Melting Erosion Characteristic on the Contact Interface between U-shaped Armature and Rails for Multiturn Serial-parallel Railgun

XING Yan-chang, LYU Qing-ao, LEI Bin, XIANG Hong-jun, CHEN Jian-wei, YUAN Xi-chao

2018, 39(11):  2081-2091.  doi:10.3969/j.issn.1000-1093.2018.11.001

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An electromagnetic-structure-thermal multi-physics coupling model is established to study the melting erosion on the contact interface between U-shaped armature and rails of a multiturn serial-parallel railgun, and the armature velocity, contact pressure and temperature of interface in the case of different current peaks and shrink ranges are analyzed. The related verification experiments were made to obtain the melting erosion characteristic of contact interface. The simulated and experimental results show that the contact pressure between armature and rails varies with current fluctuation during launching. The friction heat power varies directly with the contact pressure, but Joule thermal power caused by contact resistance varies inversely with the contact pressure. The ambient temperature of the sliding contact interface can be further improved by reasonable design of armature shrink range. Due to the inevitable wear during sliding, the melting area of armature contact surface gradually transfers from the initial contact area to the tail of armature. The experimental results validate the effectiveness of the simulation method. Key

Experimental Investigation of a Novel Single Cylinder Free Piston Expander-linear Generator

TIAN Ya-ming, ZHANG Hong-guang, LI Jian, ZHAO Teng-long, WANG Yan

2018, 39(11):  2092-2099.  doi:10.3969/j.issn.1000-1093.2018.11.002

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A single cylinder free piston expander-linear generator (FPE-LG) used for organic Rankine cycle (ORC) waste heat recovery system is developed to improve the energy efficiency of the internal combustion engines. FPE-LG can operate continuously and stably under the condition of high driven pressure, which indicates that the working principle of single cylinder FPE-LG is feasible. The effects of driven pressure and external load resistance on the output characteristics of single cylinder FPE-LG are investigated through experiment. The experimental test results show that the power output of FPE-LG exhibits a regular sinusoidal fluctuation, and the peak power output can reach 58.7 W when the driven pressure is 0.6 MPa and the external load resistance is 50 Ω. The increase in driven pressure can increase the RMS voltage and peak current significantly. However, it has little effect on the power-electric conversion efficiency of FPE-LG. When the external load resistance is less than 60 Ω, the power-electric conversion efficiency η of FPE-LG increases from 13.4% to 24.7% with the increase in external load resistance. When the external load resistance is 60 Ω, actual expansion work (AEW), W_AEW, of the single cylinder FPE-LG is the largest and the power-electric conversion efficiency is the best. The continuous increase in the external load resistance value has little effect on W_AEW and η. Key

Fault Detection for an Electro-hydraulic Position Servo System of Vehicle-mounted Howitzer Based on Unknown Input Observer

TIAN Ling-fei， QIAN Lin-fang， CHEN Long-miao， YUE Cai-cheng

2018, 39(11):  2100-2108.  doi:10.3969/j.issn.1000-1093.2018.11.003

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For large inertia, load nonlinearity, parameter uncertainty and disturbance in the electro-hydraulic position servo system of vehicle-mounted howitzer, a fault detection scheme based on nonlinear unknown input observer is proposed. After modeling the system, a nonlinear observer design is utilized to generate the residual signals required for fault detection. The observer's stability is proved and its existing conditions is given by Lyapunov stability theory. The observational ability and fault detection ability of observer are detected online on a fault detection test rig. A dynamic threshold failure decision mechanism based on statistics is designed, which eliminate the false alarm of fixed threshold in transition stage. The experimental examples are investigated to demonstrate the effectiveness of the proposed fault detection scheme, which can be applied for the online fault detection of the electro-hydraulic position servo system. Key

Dynamics Modeling and Analysis of Open Chain Drive Transmission for a Ramming Mechanism

LIU Tai-su, QIAN Lin-fang, CHEN Guang-song, JI Lei

2018, 39(11):  2109-2117.  doi:10.3969/j.issn.1000-1093.2018.11.004

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In order to analyze the kinematic accuracy and dynamic characteristics of open chain drive transmission for a ramming mechanism, the geometrical relationship and contact modes of roller and sprocket as well as the contact between chain links are described in detail, and then the normal contact force model and the plane contact force model are established for different contact modes. An accurate dynamic model of open chain drive transmission mechanism is established. The characteristics of contact between roller and sprocket are analyzed, and the effect of the change in clearance between roller and sprocket on kinematic accuracy and the dynamic characteristics is discussed. The results show that the clearance between roller and sprocket has great influence on the dynamic characteristics of open chain drive transmission mechanism of the ramming mechanism. The clearance between roller and sprocket should be controlled in reason during the engineering. Key

Numerical Study of Asymmetrical Load on the Body of Dual-spin Projectile

FENG Bin, YU Ji-yan, JU Tan, WANG Xiao-ming, WANG Yu

2018, 39(11):  2118-2126.  doi:10.3969/j.issn.1000-1093.2018.11.005

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The load on dual-spin projectile's body has an asymmetrical characteristic because of the influence from asymmetrical wake flow of canards. The asymmetrical load on the projectile body is studied. The results form computational fluid dynamics (CFD) simulation and wind tunnel test are compared to prove the effectiveness of the CFD method. The dual-spin projectile models with control surface angles of 0°, 2°and 4° are simulated at various Mach numbers and angles of attack. The flow field is qualitatively analyzed by drawing the streamline diagrams of tail flow of canards and the pressure coefficient contour map of projectile body. The asymmetry of force of the projectile body is quantitatively analyzed by comparing the pressure coefficient of body section and the lateral force coefficient of body. The result shows that the body section pressure coefficient of the model with control surface angle of 0° is symmetrical, and the body section pressure coefficients of the model with control surface angles of 2°and 4°are asymmetrical. The projectile body's normal force coefficient curves of three models coincide with each other as the change in the angle of attack at a given Mach number; and the lateral force coefficient is near 0 for the model with control surface angle of 0°, but is approximately linear with the angle of attack for the models with control surface angles of 2° and 4°, and is first ascended and then descended with the Mach number. When the angle of attack is given, the peak value of the model with control surface angle of 4° is about 2 times that of the model with control surface angle of 2° . Key

Analysis of Transmitting Waveform of Radio Fuze Modulated by Chaotic Bi-phased Code and Hybrid Linear FrequencyModulation

CHEN Qi-le, YAN Qi, HAO Xin-hong, DU Han-yu

2018, 39(11):  2127-2136.  doi:10.3969/j.issn.1000-1093.2018.11.006

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A scheme of modulating the transmitting waveform of radio fuze by chaotic bi-phased code and hybrid linear frequency modulation is proposed to improve the anti-jamming performance of radio fuze in complex battlefield electromagnetic environment. The ambiguity function of the transmitting waveform is derived theoretically, the influence factors of the distance and velocity resolutions are calculated and analyzed quantitatively, and the anti-interception factor is also calculated. The anti-jamming performance of the radio fuze is tested in the ECCM experiments of the fuze prototype and the jamming system. The simulated and experimental results show that the proposed waveform has the better resolution performances and anti-jamming performance compared with the traditional transmitting waveform. Key

Recovery Experiment Study of Cylindrical 40CrMnSiB Steel Shell in Intermediate Phase of Expanding Fracture Processes

CHEN Zhi-chuang， LI Wei-bing， ZHU Jian-jun， WANG Xiao-ming， LI Wen-bin

2018, 39(11):  2137-2144.  doi:10.3969/j.issn.1000-1093.2018.11.007

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To understand the influence of tempering temperature on the dynamic process of expansion and fracture of cylindrical metal shell, a recovery experiment is designed to recover the fracture morphologies of metal shells at the intermediate phase of explosion. The 40CrMnSiB steels tempered at 200 ℃, 350 ℃, 500 ℃, and 600 ℃ are used as the research objects. The intermediate states of fractures of cylindrical metal shells at four different tempering temperatures were obtained through the recovery experiment. On this basis, the effects of different tempering temperatures on the fracture pattern, crack initiation, propagation and distribution are analyzed, and the influence rule of tempering temperatures on the macroscopic fracture characteristics of cylindrical 40CrMnSiB steel shells is revealed. The result shows that, as the tempering temperature is increased from 200 ℃ to 600 ℃, the fracture characteristic parameters of shell are influenced by the improvement in dynamic plasticity and fracture toughness and change significantly at the initial stage; at the later stage, the effect caused by the decrease in the dynamic strength of material is more prominent, so these parameters are essentially constant. The fracture strain of metal shell tempered at 500 ℃ is maximal, which is increased by 48.1% compared with that tempered at 200 ℃. Key

A Nozzle Contour Optimization Method Considering the Change in Fuel Gas Properties

SUN De-chuan， YU Ze-you

2018, 39(11):  2145-2152.  doi:10.3969/j.issn.1000-1093.2018.11.008

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Space rocket engine nozzle usually has large area ratio, and the improvement in its performance is one of the goals of engine design. A design method for divergent section considering the changes in properties of the real fuel gas in nozzle is proposed based on the Rao's method. For an apogee rocket engine, the Rao's method is used to design an original nozzle contour, and then the function of specific heat of the real fuel gas is calculated and a new nozzle contour of divergent section of nozzle is designed. The vacuum specific impulses of the new nozzle contour and the original one are compared through numerical simulations. Simulated results show that the calculation method of fuel gas specific heat can be used for the nozzle flow simulation; the specific heat of fuel gas has great effect on the nozzle contour design; for the nozzles with the same length, the nozzle contour designed by considering the change in specific heat capacity has smaller exit area ratio, but has higher vacuum specific impulse; and for the space engine which has not too large thrust, the increase in vacuum specific impulse is less then 1s, and the gain of performance by the boundary layer displacement is very small. Key

Influences of Mass Effect and Thermal History on Thermal Decomposition of Ammonium Nitrate

CAO Xiong, ZHANG Yun, CAO Wei-guo, ZHANG Yu-long, DAI Peng, XUE Chen-lu, TAN Ying-xin

2018, 39(11):  2153-2158.  doi:10.3969/j.issn.1000-1093.2018.11.009

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The differential scanning calorimetry (DSC), microcalorimeter and cook-off (CO) oven are used to study the influence of mass on the thermal decomposition characteristics of ammonium nitrate (AN), and DSC and microcalorimenter are used to study the effect of thermal history on the thermal decomposition characteristics of AN. The results show that the mass has a significant effect on the thermal stability of AN, and the measured decomposition temperatures of samples, including onset decomposition temperature and peak decomposition temperature, decrease with the increase in their mass sizes. The large mass sample is easy to explode, which ultimately decreases the thermal stability of AN. The decomposition temperatures drifts to low temperature direction greater and greater with the increase in temperature. This is mainly due to the autocatalytic chemical reactions which generate intermediate products during heating. It is necessary to avoid the storage of large mass of AN and keep the heat source off the storage location in the process of industrial production and storage.Key

Dynamics Modeling of Spinning Missiles Considering the Rigid-elastic Coupling Effect

CHEN Er-kang, LIAO Xin, GAO Chang-sheng, JING Wu-xing

2018, 39(11):  2159-2171.  doi:10.3969/j.issn.1000-1093.2018.11.010

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Considering the interaction between flexible and rigid modes caused by the increased aspect ratio and elasticity of spinning missile, the nonlinear equations of motion for elastic spinning missile are developed. The transient coordinate system, in which vibration mode is used to describe the missile’s elastic deformation, is introduced. The slice theory is used to establish an aerodynamics model. Lagrangian equation is used to derive the complete inertial coupling model of elastic spinning missiles. In the model, the influence of elastic deformation on the mass property is considered, and the coupling effect between flexible and rigid modes are fully described. Under different assumptions, the complete inertial coupling model can be simplified to obtain the simplified inertial and non-inertial coupling models. Numerical simulations demonstrate that the main difference on the attitude motion is not negligible, while the difference on the flexible mode is negligible. The influence of inertial coupling must be considered in the modeling and analysis of elastic spinning missile. Key

Back-stepping-fault-tolerant Control for Keeping the Formation of Unmanned Aerial Vehicles

LI Bing-qian, DONG Wen-han, MA Xiao-shan

2018, 39(11):  2172-2184.  doi:10.3969/j.issn.1000-1093.2018.11.011

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A back-stepping-fault-tolerant control is proposed for keeping the formation of leader-follower unmanned aerial vehicles(UAV) under the conditions of actuator fault, uncertain aerodynamic parameters and external disturbance. The forward, lateral and altitude distance error models are described. An UAV motion model with actuator fault, external disturbance, and uncertain aerodynamic parameters is described. An inner loop fault-tolerant control system is designed to track the command signal produced by the outer loop formation controller. The inner loop fault-tolerant control system is consisted of three parts:one is the fault detection and identification (FDI) mechanism to locate the fault actuator and estimate the fault parameters; one combines back-stepping control with fault parameters and an adaptive disturbance observer to compensate for actuator faults, external disturbance, and uncertain aerodynamic parameters; the other one is the stability analysis of the inner loop controller system. The simulated results show that the proposed control method can be used for the fault-tolerant control of UAV formation. Key

Optimization Design of Wideband Digital Beamforming for Radar Jamming Based on SOCP

ZHANG Hong-wei, TANG Jian-long, FENG Zong-sheng, KE Xiao-mei

2018, 39(11):  2185-2191.  doi:10.3969/j.issn.1000-1093.2018.11.012

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The present wideband digital beamforming method has some disadvantages in engineering application of radar jamming, such as single applicable signal, poor jamming effect and high implementation difficulty. A wideband digital beamforming method for radar jamming based on second-order cone programming (SOCP) theory is adopted. The amplitude and phase of wideband jamming signal are modulated using a corresponding wideband finite impulse response filter in each channel of beamformer. In order to obtain the best filter coefficient, a linear constrained minimum power criterion is adopted to design and optimize the beamformer. The optimization difficulty is reduced by eliminating the frequency dependence of side lobe constraint and transforming the analytical form of filter coefficient solution into the corresponding SOCP form. The simulated results show that the proposed approach can be used to solve the optimal design issue. Key

Optimization Deployment of Multi-sensors in Complex Terrain Based on Multi-objective LM-AQPSO Algorithm

XU Gong-guo , DUAN Xiu-sheng, SHAN Gan-lin, TONG Jun

2018, 39(11):  2192-2201.  doi:10.3969/j.issn.1000-1093.2018.11.013

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A method of multi-objective multi-sensor deployment based on multi-objective local aberrance and adaptive quantum particle swarm optimization (LM-AQPSO) is proposed to study the deployment of multi-sensors in complex terrain. The complex terrain is modeled by multi-attribute grid technology, and the sensor detection model and optimization objectives are given. The QPSO algorithm is improved by utilizing local aberrance and adaptive strategy and a multi-objective LM-AQPSO algorithm is proposed for solving Pareto optimal solution. In considering the requirement of multi-objective deployment, a multi-sensor optimization deployment model based on Pareto optimal solution is established. Simulated results show that the Pareto optimal solutions obtained by LM-AQPSO algorithm have better convergence and distribution, and the optimization time is shorter compared with the classical non-dominated sorting genetic algorithm II. The proposed model can effectively deal with the multi-objective multi-sensor deployment problem, and can provide more decision-making options. Key

Three-dimensional Focusing Inversion of Magnetic Target in the Presence of Significant Remanence

LI Jin-peng, ZHANG Ying-tang, FAN Hong-bo, LI Zhi-ning, ZHANG Guang

2018, 39(11):  2202-2210.  doi:10.3969/j.issn.1000-1093.2018.11.014

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A three-dimensional focusing inversion approach of magnetic target is proposed for the effect of remanent magnetization on the true magnetization direction in the process of inversion. For an isolate magnetic source, its magnetization direction is estimated, and then the estimated magnetization direction is incorporated into an inversion algorithm. For multi-magnetic sources, the direct inversion of the total modulus data is made. Total modulus data depends weakly upon magnetization direction. In the iterative process, the depth weighting matrix and minimal support matrix are added in the inversion model of Tikhonov regularization theoretical framework to obtain the objective function and avoid the multiple solutions of inversion problem. Objective function is calculated by singular value decomposition, and the unbiased predictive risk estimator principle is used to adaptively determine the regularization parameter in the iterative process, thereby realizing the iterative process automation. Simulated and experimental results show that the proposed inversion method can reflect the outline form of magnetic anomaly and has good model resolution in the presence of significant remanence. Key

Parameter Optimization of Magnetic Shielding Device Based on Combination Optimization Method

LYU Zhi-feng, ZHAO Xin, ZHANG Jin-sheng, WANG Shi-cheng, LI Ting

2018, 39(11):  2211-2219.  doi:10.3969/j.issn.1000-1093.2018.11.015

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An “analytic+numerical” optimization method is proposed for the structural parameter optimization of magnetic shielding device, which combines the calculation simplicity of analytic method and the high calculation accuracy of numerical method. First, it is necessary to judge whether there is an analytical expression for the calculation of magnetic shielding performance. If it is difficult to obtain the analytical expression, the artificial neural network can be used to establish a calculation model, and a “black box analytical expression” is obtained. The intelligent optimization algorithm is used for quick “rough” optimization for analytical expression or “black box analytical expression” in a short time. And then the numerical method is used for the fine scanning calculation based on the “rough” optimal solution to achieve a “fine” optimization. The credibility of the optimized results is confirmed by cross-validation. The structural parameter optimization of double layer cylindrical and single layer rectangular magnetic shielding devices were simulated. The simulated results show that the coarse-to-fine optimization method is correct, and has higher reliability than pure analytical optimization. Key

Analysis of Optimal Inner-cluster Hop Number of Multi-hop Cluster-based Ad Hoc Network

ZHANG Wen-qing， LI Xu， HUANG Wen-jun

2018, 39(11):  2220-2227.  doi:10.3969/j.issn.1000-1093.2018.11.016

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Multi-hop cluster-based ad hoc networks suffer from poor scalability and large overhead. The selection of inner-cluster hop number is the key to the performance of cluster network. In considering the overhead of routing layer maintenance and MAC layer scheduling, the interference and capacity of network are derived out using hard-core Poisson point process (HCPP). A network throughput and channel utilization rate model is further established. With the goal of the maximizing throughput and the constraint of channel utilization rate, the optimal inner-cluster hop number is obtained. Simulated results show that the proposed model can effectively reflect the impacts of inner-cluster hop number, node density and other parameters on interference intensity, throughput and channel utilization rate. The optimal inner-cluster hop number depends on path loss coefficient and node density. Key

Research on the Characteristics of Supercavitating Flows Caused by Underwater Continuously Fired Projectiles

SHI Hong-hui, ZHOU Dong-hui, SUN Ya-ya, JIA Hui-xia, HOU Jian

2018, 39(11):  2228-2235.  doi:10.3969/j.issn.1000-1093.2018.11.017

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Based on the FLUENT software and the dynamic grid technology controlled by user-defined function, the supercavitation flows of the continuously fired projectiles were numerically studied to analyze the characteristics of supercavitating flows. The numerical results of the supercavity shape and the drag coefficient of projectiles are effectively consistent with the experimental results, which indicates that the numerical simulation is exact, and the drag coefficient of projectile presents an increasing trend with the decrease in velocity of projectile. The mechanisms of supercavitations of two and three continuously fired projectiles are studied. The change rule of non-dimensional length is concluded, and the variation curve of velocity in flow field and the velocity vector are analyzed. The results show that, after the supercavity fusion of two projectiles, a high velocity re-entrant jet and many vortices are found in the aft of supercavitation. The vortices can lead to the rapid collapse of projectile supercavitation, which also indicates the extreme instability of supercavitation. The drag coefficient of two projectiles can reach to the minimum value when the two projectiles enter in a supercavitation. When the supercavitations of two continuously fired projectiles pass through the disturbance field, the supercavitations are disturbed, thus resulting in the increase and decrease in their drag coefficients. Key

Acoustic Scattering Characteristics of Underwater Elastic Corner Reflectors

CHEN Xin， LUO Yi， LI Ai-hua

2018, 39(11):  2236-2242.  doi:10.3969/j.issn.1000-1093.2018.11.018

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The multiple scattering of sound waves and the fluid-structure interaction should be taken into account to calculate the acoustic scattering of underwater elastic corner reflectors. The scattering acoustic field of underwater elastic corner reflectors in far field is simulated by using structure finite element method (FEM)/fluid indirect coupled boundary element method (IBEM). The influences of plate material and thickness, incident angle and the type of corner reflector on target strength and the scattering mechanism are analyzed when the incident wave frequency varies from 5.0 kHz to 20.0 kHz. The results show that the scattering acoustic field of underwater elastic corner reflectors has a strong frequency characteristic. It varies with plate material and thickness,and incident wave frequency. The multiple scattering of sound waves has important contributions to the backscattering acoustic field of corner reflectors. The simulated results are in good agreement with the experimental results. The structure design and optimization method of corner reflectors are presented. Key

Localization of Moving Acoustic Source in Shallow Layer of Deep Ocean Based on the Time Difference of Arrival between theFirst and Second Waves

GAO Fei， SUN Lei

2018, 39(11):  2243-2248.  doi:10.3969/j.issn.1000-1093.2018.11.019

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In order to eliminate the effects of the ocean environmental uncertainty, the accidental errors due to acoustic signal receiving and processing on positioning accuracy, the localization of a moving sound source is realized using EKF method based on the time difference of arrival between the first and second arrival waves. The acoustic waves arriving from multiple paths are identified using Butterworth band pass filtering method and Bellhop ray model, and their relative energies are also compared. And the first and second arrival waves with bigger signal-to-noise ratio (SNR) are studied. The time difference of arrival between the first and second arrival waves is calculated using time domain correlation method by taking single frequency signal as a matched sequence. The time difference of arrival is set to be a measured value, and the acoustic source is localized based on extended Kalman filter (EKF) method, thus obtaining the depth, horizontal range and speed of the moving acoustic source. When the acoustic source and hydrophone are on the surface layer in deep water acoustic channel, the direct and reflected waves overlap each other, and the energies of the first arrival wave and the first wave reflected from the bottom of the sea are higher than the others. The research work shows that the calculated results are in good agreement with the experiment data, which proves that EKF method is well fit for the localization of the underwater moving acoustic source. Key

Research on Attenuation Law of Elastic Resistance of UHMW PE Material Soft Bulletproof Vest

SUN Fei, QU Yi, XU Cheng

2018, 39(11):  2249-2255.  doi:10.3969/j.issn.1000-1093.2018.11.020

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Ultra-high molecular weight polyethylene (UHMWPE) is a material widely used for soft body armor. But the bulletproof property of UHMWPE material during aging has not been fully known, and has not been predicted quantitatively by using formulas. In order to analyze the effects of circumstance and storage conditions on the bulletproof property of soft body armor, the artificially accelerated aging experiments are conducted in the conditions of elevated temperature, hygrothermal circumstance and irradiating with xenon arc lamp. The ballistic tests are conducted toacquire the ballistic limit velocity, thus obtaining the effect law of artificially accelerated aging on bulletproof property. The results indicate that the effect law can be predicted more accurately by equation of linear regression. The ballistic limit velocity attenuation formulas of imported and domestic UHMWPEs were acquired by regression analysis in different aging procedures. The formulas can be used to predicte the variation trend of bulletproof property, and provide the estimation for long-term use and storage of UHMWPE soft body armor. Key

Multivariate Nonlinear Regression Analysis Model of Weld Bead Shaping of 50CrV Steel by Laser Welding with Filler Wire

ZHANG Chuan, ZHANG Fu-long, LI Yue-feng, LIU Shuang-yu, BO Hong-yu, ZHANG Hong, LI Yan-qing

2018, 39(11):  2256-2266.  doi:10.3969/j.issn.1000-1093.2018.11.021

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The weld penetration should be precisely controlled at 2 mm when welding 50CrV steel plates. The response surface design method is used to meet the requirement. The experimental design of laser filler wire welding process for 50CrV steel is made by using Design-Expert 8.0 software. During the experiment, the laser power, welding speed, wire feeding speed and defocusing distance are presumed as the welding process parameters, and the specific weld penetration (2 mm), minimized weld width and weld reinforcement are considered as the process responses. Weld bead measurements are carried out to generate the response dataset of describing weld characteristics, and the mathematical models correlating the process parameters with the responses are developed. The accuracy of the established mathematical model is determined by variance test. The result shows that the laser power, welding speed, wire feeding speed and defocusing distance have significant influence on the weld bead geometry. According to the optimizated results, the laser power of 3.17-3.33 kW, welding speed of 1.30-1.40 m/min, wire feeding speed of 4.0-4.23 m/min, and defocusing distance of 3.1-4.5 mm are identified as the optimal process parameters. Under these process conditions, the weld penetration, weld width and weld reinforcement meet the welding requirement. The verification experiment shows that the predicted results are consistent with the actual welding results. Key

An Assessment Model of Operational Readiness Rate in Mission Interval Considering Multiple Support Factors

GAO Long, SONG Tai-liang, CAO Jun-hai, XING Biao, YAN Xu

2018, 39(11):  2267-2279.  doi:10.3969/j.issn.1000-1093.2018.11.022

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A scientific and reasonable operational readiness assessment is of great significance for accurately grasping the actual combat capabilities of the army, optimizing the architecture of the equipment support system of systems (SOS), and improving the operational capabilities of equipment and the effectiveness of support SOS. The current assessment models focus on the maintenance support factors but ignore the supply support factors and fail to deal with the equipment and support SOS with the complex architecture and states. A new comprehensive operational readiness rate assessment model considering multiple support factors in mission interval is proposed. The interactive relationship and support process of equipment SOS and support SOS are analyzed. An operational readiness rate assessment model of individual equipment combat unit in the equipment SOS is constructed from the perspective of equipment support requirements, and an operational readiness rate assessment model of multiple equipment combat units sharing the same support SOS is further established on this basis. In the models, the the same and different support requirements of the equipment combat units are considered, respectively. For the problem that the equipment SOS states are difficultly determined when the model is solved, a method of determining the states of the equipment SOS based on vector universal generating function is presented. The validity and superiority of the proposed models to assess readiness quantificationally are verified by the example analysis. Key

Research Notes

A Novel Feature Extraction Method for the Slice of Ambiguity Function Main Ridge of Radar Signals Based on Graphic Contours

TIAN Chun-jin， PU Yun-wei， GUO Yuan-pu， SHI Yu

2018, 39(11):  2280-2288.  doi:10.3969/j.issn.1000-1093.2018.11.023

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Extracting effective characteristic parameters from the complex radar emitter signals is an effective method to solve the problem of complex radar signal sorting. Because the slice of ambiguity function main ridge of signal can be used to descript the ambiguity energy distribution information of signal, a feature extraction method of the ambiguity function main ridge slice based on graphics contours is proposed. The proposed method can extract two novel features, i.e., cumulated angle and unit cumulative length, which describe the intensity of change and the inherent characteristics of graphics contour, respectively. The experimental results of fuzzy C-means clustering show that the sorting success rate of six types of radar signals, such as normal signal, chirp signal, binary phase shift keying, quaternary phase shift keying, M pseudo-random series, and binary frequency shift keying, is 100% when signal-to-noise ratio (SNR) is no less than 12 dB; and the average success rate of signal sorting is up to 93.5% even if SNR is as low as 0 dB. When SNR changes from 0 dB to 20 dB, the average success rate of signal sorting can reach to 98.9%. The theoretical analysis and the comparative experiment of time consumption for signal sorting show that the proposed method has lower complexity, effectiveness and timeliness.Key