Table of Content

31 March 2015, Volume 36 Issue 3

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Paper

Design Optimization of Blade Parameters of Dual Torus Hydraulic Retarder

YAN Qing-dong, MU Hong-bin, WEI Wei, LIU Shu-cheng

2015, 36(3):  385-390.  doi:10.3969/j.issn.1000-1093.2015.03.001

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An optimization platform of hydraulic retarder cascade is established to optimize the parameters of the bowed blade of dual torus hydraulic retarder. The parametric modeling of single periodic flow is achieved, and the grid independence is studied to validate the credibility of simulation model. Based on CFD simulation, the design of experiments is adopted to study the influences of blade wrap angles and pressure surface radii on the brake performance. The response surface methodology is built to get the optimum parameters, and the multi-island genetic algorithm is used for global optimization design. Comparison of internal flow field and brake performance before and after optimization shows that the brake performance of hydraulic retarder with the optimum parameters is improved observably, and the braking torque is averagely increased by 42.3%.

Cycle Analysis of the Combined Turbo Piston Engine

HUANG Kai-sheng， ZHANG Yao， ZHANG Yang-jun

2015, 36(3):  391-397.  doi:10.3969/j.issn.1000-1093.2015.03.002

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The combined turbo piston engine is comprised of a diesel and a gas turbine, of which the three operating modes (single diesel mode, single gas turbine mode and the combined diesel and gas turbine mode) can be chosen according to the power need of the vehicle. The engine is assumed to have the advantages of diesel and gas turbine to acquire high thermal efficiency and high power density at the same time. The configuration of the combined engine is presented. The theoretical cyclic thermal efficiency and specific work of the engine under the three modes are studied. The formula of thermal efficiency and work weight ratio are deduced. According to the set parameters of the cycle, the thermal efficiency and work weight ratio of the three modes are calculated. A diesel engine and a gas turbine with similar rated power are chosen to make up the combined turbo piston engine. A simulation model of the combined engine is built in GT-Power, and the performances of the engine under the rated condition are calculated. The results show that the combined turbo piston engine can acquire high thermal efficiency and high power density.

Design of Low Temperature Preheating System of Hybrid Electric Tracked Vehicle Based on Motor Heating

WANG Rui, WANG Yi-chun, FENG Chao-qing, ZHANG Xi-long

2015, 36(3):  398-404.  doi:10.3969/j.issn.1000-1093.2015.03.003

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For the tracked HEV, a new preheating system of powertrain is designed to solve the cold start problem in winter,in which the heat is generated by the drive motor running at very low speed. The new preheating system can meet the need of cold start. In order to get the heat from the power cabin to the outside environment, CFD numerical calculation is done for the heating process. The simulation results are verified through the relevant test. Based on the heat loss of power cabin and the parameters of engine cabin components,a heat transfer model of preheating system is established by using MATLAB. The total energy required for preheating at different ambient temperatures is calculated by this model. The energy losses and heating efficiency are obtained at different heating powers. The results show that the minimum heating power is 70 kW, and total energy is181 MJ.By considering the low temperature discharge rule of power battery, the heating power and battery capacity in the process of preheating are calculated for lithium iron phosphate batteries.The minimum battery capacity is 292 A·h.

Adaptive Sliding Mode Steering Control of Double Motor Coupling Drive Transmission for Tracked Vehicle

GAI Jiang-tao， HUANG Shou-dao , ZHOU Guang-ming, LIU Yi, MA Tian

2015, 36(3):  405-411.  doi:10.3969/j.issn.1000-1093.2015.03.004

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Steering dynamic model of double motor coupling drive transmission for tracked vehicle has the features of MIMO, parameter-uncertainty and nonlinearity. The steering system is transformed into a forward speed control subsystem and a steering speed control subsystem by dynamic decoupling control algorithm.For the forward speed control subsystem, a robustness sliding mode control algorithm is proposed to converge the speed errors based on the desired speed and the current speed. For the steering speed control subsystem, a steering speed control algorithm is designed based on the fuzzy adaptive sliding-mode algorithm to ensure the tracking control of the reference steering speed. The steering tracking control is verified by real-time simulation system.The results show that the proposed control algorithm is effective.

Numerical Simulation of Navigating Pose for Amphibious Vehicle based on Dynamic-mesh Model

ZHAO Bin, ZHANG Min-di, JU Dong-mei

2015, 36(3):  412-420.  doi:10.3969/j.issn.1000-1093.2015.03.005

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A dynamics model for the navigating pose of amphibious vehicle in water is established. The dynamic mesh technology and the hybrid coupled algorithm are used to study the change rule of navigating pose of amphibious vehicle in sailing, and the navigating pose of amphibious vehicles in still water are discussed. The numerical results are consistent with the experimental results. The result shows that the vehicle undergoes a sharp motion and a smooth motion during movement before achieving the ultimate navigating pose. After achieving the ultimate navigating pose, the center-of-gravity and the pitch angle slightly change. During the process of sailing from drainage state to coasting state, the body center of gravity gradually increases; the dynamic buoyancy to support the vehicle weight increases, and the static buoyancy decreases.

Numerical Simulation and Comparative Analysis of Microscopic Frictional Behavior of Composite Sealing Ring

GONG Ran， ZHANG He， CHE Hua-jun， XU Yi

2015, 36(3):  421-426.  doi:10.3969/j.issn.1000-1093.2015.03.006

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According to the characteristics of the material heterogeneity of the composite sealing ring, the microscopic sliding contact is investigated based on the movable cellular automata. The microscopic dynamic responses of sealing surfaces are visualized when loads are applied according to the actual working conditions. The frictional behaviors of the polyimide (PI) and the polytetrafluoroethylene (PTFE) composite sealing rings are analyzed, and the changing processes of friction coefficients are obtained within the simulation time. The results show that the formation and evolution processes of the mechanically mixed layers of PI and PTFE sealing rings are basically the same. The friction coefficient of PI sealing ring is greater than that of PTFE one. The properties and morphology of filler materials determine the microscopic friction behaviors. The friction test is conducted for PI and PTFE sealing rings. The coefficients of friction in the simulations and tests are calculated and compared. The results indicate the effectiveness of microscopic frictional simulations in the mixed lubrication based on the movable cellular automata.

Calibration of Vehicular Three-axis Magnetometer via Truncated Total Least Squares Algorithm

ZHANG Ying， YANG Ren-nong， LI Ming-yang， ZUO Jia-liang， CHEN Xing-yi

2015, 36(3):  427-432.  doi:10.3969/j.issn.1000-1093.2015.03.007

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A regularization three-axis magnetometer calibration algorithm is proposed for vehicular navigation. Due to the constrained manoeuvre of the vehicle, a linear observational equation system for calibration of three-axis magnetometer is severely ill-posed. The traditional calibration methods may result in unreliable solutions in the lack of dealing with ill-posed problem. The ill-posed problem is solved by using the truncated total least squares (TTLS) technique. This method can effectively suppress the errors on both sides of the observation equation. Furthermore, the TTLS method is used to solve the ill-posed problems. A vehicular navigation experiment is conducted to validate the effectiveness of the method．The results show that the proposed algorithm can effectively mitigate the ill-posed problem and obtain more stable numerical solutions. The mean value of the heading angles from the calibrated measurements is equal to 1.5°, which meets the vehicular navigation application.

Structural Multi-objective Optimization of Artillery Recoil Mechanism Based on Genetic Algorithm

ZHOU Le， YANG Guo-lai， GE Jian-li， WANG Fei

2015, 36(3):  433-436.  doi:10.3969/j.issn.1000-1093.2015.03.008

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Recoil resistance and muzzle disturbance are the key factors influencing the firing accuracy. In order to reduce maximum value of recoil resistance and muzzle disturbance, a rigid-flexible coupling system dynamics model is established for a large caliber gun. In the case of recoil mechanism and overall structure, the basic development module of ADAMS is used in conjunction with niche genetic algorithm to solve the multi-objective optimization function for gun recoil mechanism. Maximum value of recoil resistance and muzzle disturbance can be effectively reduced through optimization. The result shows that the proposed optimization method is reasonable and feasible, and can provide reference for optimization design of overall structure and recoil mechanism.

Damage Effects of High Velocity Penetrator on Chemical Submunition Payloads

JIN Xue-ke, YU Qing-bo, ZHENG Yuan-feng, WANG Hai-fu

2015, 36(3):  437-442.  doi:10.3969/j.issn.1000-1093.2015.03.009

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The ground-based experiments of high velocity explosively-formed penetrators impacting the simulated chemical submunition payloads are performed to investigate the effects of different impact positions on the damage effect of chemical submunition. The experimental results show that the typical damage modes of chemical submunitions are denting (no leakage), local cracking ( partial leakage) and fragmenting (complete leakage), and their distribution strongly depends upon the impact positions in the submunition payload. An overlap volume analysis based on perforating trajectory shows that the destruction probability of submunitions, varying with the impact position offset, appears a complex multiple step-like distribution. The analysis result is in agreement with the experimental result. It may be considered that the dynamic behavior and effect, resulting from the direct impact of high velocity penetrator upon the submunitions along the perforation trajectory, are the dominant destruction mechanisms. The other important additional destruction mechanisms, such as skin debris impact, collision among neighboring sunmunitions, submunition debris impact and leaked fluid ejection, significantly enhance the destruction effectiveness against the chemical submunition payloads.

Numerical Simulation on the Effect of Reduction in Ambient Pressure on the Secondary Combustion of Base Bleed

YU Wen-jie， YU Yong-gang

2015, 36(3):  443-450.  doi:10.3969/j.issn.1000-1093.2015.03.010

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In order to investigate the mechanism of the decrease in drag reduction rate of base bleed in the subatmospheric pressure, a mathematical and physical model about the base flow with chemical non-equilibrium of base bleed is established. H₂-CO combustion model which consists of 10 components and 25 reactions is used for secondary combustion. Two-dimensional axisymmetric equations are programmatically computed using a set of uniform numerical process methods. The base flow field of base bleed is simulated. Simulation results are validated with experiment data. On this basis, the base flow field and combustion characteristics are numerically predicted. The results show that the added energy released from secondary combustion is 6.4 times of the added energy of hot base bleed. Secondary combustion is a key for energy increase and drag reduction. With the decrease of the ambient pressure, the combustion efficiency of H₂ decreases gradually in the annular recirculation zone of the tail of the model，meanwhile the intermediate product of H increases gradually. These make the secondary combustion become more and more insufficiency, resulting in decreasing significantly the drag reduction rate of base bleed.

Research on the Influence of Centering Type Sabot on Penetration of Projectile into Concrete

LIU Jian-cheng, HUANG Feng-lei, PI Ai-guo, SHEN Chao

2015, 36(3):  451-456.  doi:10.3969/j.issn.1000-1093.2015.03.011

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In order to optimize the design of the forward and back centering sabots which are commonly used in the Davis Gun system, a penetration model of rigid penetrator with sabot is established based on the Forrestal penetration model, and the influences of the relative sabot mass, the connection strength between sabot component and projectile and the impact velocity on projectile penetration are analyzed. The results indicate that the penetration depth increases obviously with the increase in sabot mass. The effect of the sabot mass on the penetration depth augments gradually while the effect of the connection strength on the penetration depth get smaller with the improvement of the impact velocity.

Optimization Design Method of Fragmenting Warfare Based on Improved Genetic Algorithm

MAO Liang， JIANG Chun-lan， WANG Chao， LU Wei-jing

2015, 36(3):  457-462.  doi:10.3969/j.issn.1000-1093.2015.03.012

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A optimization design method is used to change the “drawing and testing” design model of fragmenting warhead and improve the design efficiency and quality. A mathematical model for optimization design of fragmenting warhead is build by analyzing the objective function, constraint condition and analytic model. The improved genetic algorithm with multi-parent crossover operator is used in the optimization design process of fragmenting warhead. By the way, the traditional optimization algorithm has some disadvantages, such as morbid gradient, high sensitivity to initial value and local convergence. A focusing fragmenting warhead is optimized with the warhead power and mass as the optimization target. The calculated results show that the various performance indexes of final project meet the specifications. The optimized target is greatly improved compared with the original project.

Theoretical and Experimental Study of Penetration of Cuboid Fragments into Gelatin

MO Gen-lin, WU Zhi-lin, FENG Jie

2015, 36(3):  463-468.  doi:10.3969/j.issn.1000-1093.2015.03.013

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The contact conditions of cuboid fragments penetrating into gelatin and the pressure distribution assumptions on the contact surface are established to study the motions of the fragments. On the basis of the assumptions, a six-DOF motion model of the fragments is deduced from the mass center motion equations and Euler motion equations. The change rules of translational displacements and Euler angles with time are obtained by solving the motion equations with Runge-Kutta method. Two cuboid fragments are tested in the experiments. The attack angles, horizontal displacements and vertical displacements are captured by using a high-speed camera. The dynamic coefficient in the motion model is obtained by using try-out method. The calculated results show that the theoretical displacements agree well with the experimental data.

Synthesis， Structure and Detonation Performance of Triaminoguanidinium 55′-bistetrazole-11′-diolate salt

JING Su-ming, LIU Yu-cun, LIU Deng-cheng, GUO Jia-hu

2015, 36(3):  469-474.  doi:10.3969/j.issn.1000-1093.2015.03.014

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A new energetic ionic salt—triaminoguanidinium 5,5′-bistetrazole-1,1′-diolate salt is synthesized based on glyoxal and guanidine hydrochloride. The structure of triaminoguanidinium 5,5′-bistetrazole-1,1′-diolate salt is characterized by using FT-IR，¹H NMR， ¹³C{¹H} NMR spectra and elemental analyses. Its optimized structure，IR spectrum and thermodynamic parameters are obtained at the DFT-B3LYP/6-31+G^**theoretical level. Its detonation properties and thermal decomposition are also predicted by the formula of Kamlet-Jacobs. The results show that the density， heat of formation， detonation velocity and detonation pressure are 1.78 g/cm³，710 kJ/mol， 9.01 km/s and 34.88 GPa，respectively.

Active Defense Nonsingular Terminal Sliding Mode Cooperative Guidance Law

ZOU Xin-guang, ZHOU Di, DU Run-le, LIU Jia-qi

2015, 36(3):  475-483.  doi:10.3969/j.issn.1000-1093.2015.03.015

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The ballistic missiles are easily intercepted by the missile defense systems due to the absence of maneuverability in exo-atomosphere. It is important to design an effective guidance law to improve the success penetration rate of ballistic missile. An active defense nonsingular terminal sliding mode cooperative guidance law is presented. In ballistic missile active defense scenarios, one or more defending missiles, named defenders, accompany the ballistic missile to intercept the incoming interceptor missiles launched from the missile defense systems. The guidance process for the defenders is divided into two phases: Phase 1 and Phase 2. For Phase 1, a line of sight (LOS) based guidance law is designed, by which the defending missile positions itself on LOS between the ballistic missile and the interceptor missile. In this phase, the proposed guidance law can notably reduce the needed maneuverability of defending missile. To simplity the designing, the guidance law uses an approximate relative motion model, of which accuracy is acceptable in Phase 1. For Phase 2, a guidance law based on LOS angular velocity nullifying strategy is proposed. In this phase, the proposed guidance law uses more accurate relative motion models and avoids the increased errors induced by the approximate relative motion model in Phase 2. Simulation results show the high performance of the guidance laws.

A Simplified UKF Algorithm for SINS/GPS/CNS Integrated Navigation System in Launch Inertial Coordinate System

PAN Jia-liang， XIONG Zhi, WANG Li-na, YU Feng, ZHAO Hui, LIN Ai-jun

2015, 36(3):  484-491.  doi:10.3969/j.issn.1000-1093.2015.03.016

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Each state of integrated navigation system is strongly nonlinear and coupled with each other under missile-borne high-dynamic environment. Since the traditional extended Kalman filter algorithm ignors the interaction of higher order terms, its linear expansion may teads to its inaccuracy and the decrease in navigation precision. UKF algorithm can effectively avoid bringing a linearization error, but the real-time of the algorithm can be affected by the complex filtering calculation for a large number of particles in high-dimensional integrated navigation system. A simplified unscented Kalman filter (SUKF) algorithm is proposed for the requirement of high real-time and accuracy for the missile-borne integrated navigation system in launch inertial coordinate system. SUKF can be used to directly estimates the state parameters of the navigation system to achieve the real-time and improve the navigation precision without linearization extension in traditional EKF. The simulation results show that SUKF effectively improves the real-time and filtering precision of algorithm, so SUKF is very suitable for the actual engineering system.

Research on Distributed Multi-vehicle Coordinated Formation Flight Control with Coupling Time-delay and Jointly-connected Topologies

XUE Rui-bin, SONG Jian-mei, ZHANG Min-qiang

2015, 36(3):  492-502.  doi:10.3969/j.issn.1000-1093.2015.03.017

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A distributed formation control algorithm is proposed based on consensus theory for multi-vehicle nonlinear system model with simple kinetics characteristics coupling time-delay and jointly-connected topologies. System stability of multi-vehicle system with time delay is analyzed by using Lyapunov-Krasovskii function, and the stability sufficient condition in terms of LMIs is given. The simulation examples are used to verify the effectiveness of the control algorithm. When the stability condition of time delay, control parameters and network topology is satisfied, the formation control algorithm guide the multi-vehicle system asymptotically to converge to the desired velocity and shape the desired formation.

Analysis and Evaluation of Coaxiality Error of Semi-strapdown Micro Inertial Measurement System

ZHANG Xi, LI Jie, FAN Jian-ying, CHEN Wei, FENG Wei

2015, 36(3):  503-509.  doi:10.3969/j.issn.1000-1093.2015.03.018

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The semi-strapdown micro inertial measurement method is a new solution to high precision attitude measurement of the high-speed rotation ammunition. The complex mechanical structure of semi-strapdown platform causes a non-ignorable coaxiality error. The basic structure and working principle of the system are introduced, and the analytical evaluation methods suitable for the coaxiality evaluation of the outer and inner cylinders of semi-strapdown system are proposed. The evaluation method of outer cylinder is based on the existing standard measurement method. A dynamic evaluation method for the inner cylinder coaxiality of semi-strapdown system is designed in detail based on the deduction of miniature inertial measurement unit（MIMU）output model in consideration of coaxiality error angle. The coaxiality error angle is calibrated using the component in the system, and makes the error compensation for the radial gyro output under the experiment condition. The analysis and evaluation of the coaxiality error of semi-strapdown micro inertial measurement system are performed. The results show that the proposed method is feasible.

Optically-aided Transfer Alignment of Vehicle-launched Missile

LIANG Hao, WANG Dan-dan, MU Rong-jun, CUI Nai-gang

2015, 36(3):  510-515.  doi:10.3969/j.issn.1000-1093.2015.03.019

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The requirements of vehicle-launched missile for the initial alignment in modern warfare are analyzed from the aspects of launch preparation time and alignment accuracy. A new alignment method combining optical collimation and transfer alignment is proposed. A system construction scheme is proposed, and an optical azimuth transitive relation between master inertial navigation system (MINS) and slave inertial navigation system (SINS) is derived. The relative azimuth obtained by optical collimation is introduced into the measurement equation of “ angular rate plus acceleration matching” to estimate the installation angle between MINS and SINS by utilizing the Kalman filter. In the laboratory, the principle experiment is implemented to verify the optical azimuth transfer algorithm. The mathematical simulation for optically-aided transfer alignment is carried out. The simulation results show that the proposed method has fast convergence speed and high alignment accuracy to meet the demand of the initial alignment of modern vehicle-launched missiles.

Analysis of Transverse Vibration Response and Instability of Flexible Spinning Flight Vehicles under Follower Thrust

RONG Ji-li, XU Tian-fu, WANG Xi, YIN Xin-zhe

2015, 36(3):  516-522.  doi:10.3969/j.issn.1000-1093.2015.03.020

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The self-rotation of flexible spinning flight vehicles in the dynamic analysis is emphatically considered. The equations of motion are formulated and the dynamic stability is analyzed by taking into account gyroscopic moment and follower thrust. The flexible spinning flight vehicle is simplified as a non-uniform rotor structure. Timoshenko beam model, which assumes that the shear deformation influences axial displacement, is adopted with consideration of the effects of gyroscopic moment and follower thrust. The equations of motion are established based on the finite element method to analyze the effects of rotating speed and follower thrust on the dynamic response and structural instability under the action of mass eccentric force. The results show that system stiffness and critical spin speed decrease with the increase in follower thrust; the resonance of system occurs when the excitation frequency equals to the critical spin speed frequency; the follower thrust equaling to or being greater than the critical thrust results in system instability; the increase in spin speed will reduce the critical thrust of system; and the structural heterogeneity greatly affects the critical spin speed and critical thrust.

Logistic Regression Analysis of the Explosion Limit of Nicotinic Acid Dust Cloud

LIU Qing-ming, LIU Li-bin, WANG Jian-ping, WANG Bin, ZHANG Yun-ming

2015, 36(3):  523-529.  doi:10.3969/j.issn.1000-1093.2015.03.021

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The regulations and requirements of EN14034-3:2006^\[1\], E1515^\[2\] and GB/T 16425—1996^\[3\] for the measurement methods of lower explosive limit concentration of dust cloud differ from each other. To more precisely research the lower explosive limit of dust cloud, the lower explosive limit of niacin dust with particle size of 96~113 μm is test in 20 L spherical explosion test apparatus according to statistical data collection. Based on logistic regression model, the test results are analyzed using SPSS statistical software to obtain the probability distributions for ignition versus dust concentrations of niacin dust. The scope of dust cloud explosion limit proposed in GB/T 16425—1996 dust cloud explosion limit concentration measurement method is quantified, the influences of different experimental times on the lower explosive limit probability distribution are analyzed. The analysis result shows that the range of the confidence interval is the narrowest with the lower explosive limit of the particularity of 50%. For different number of experiments, the trends of the lower explosive limit probability on both sides of the value are different. Compared with the results obtained by other dust cloud explosion limit concentration measurement methods, the lower explosive limit of niacin dust which is expressed in the probability is more in line with the actual situation.

Modeling and Simulation on GNSS Vector Tracking Loop Based on Extended Kalman Filter

ZENG Guang-yu, SHEN Qiang, LI Dong-guang, HE Xin

2015, 36(3):  530-538.  doi:10.3969/j.issn.1000-1093.2015.03.022

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Considering a limited public information about analysis of GNSS vector tracking algorithm control process, a vector delay/frequency lock loop (VDFLL) tracking model is established, and a derivation on the model’s linearization process is proposed.The sequential control logic of vector tracking algorithmis analyzed. For the fact that VDFLL cannot lock the carrier phase, a message demodulation mode based on series phase-locked loop (PLL) is put forward. And a vector VDFLL model is implemented on the platform of a software receiver. The simulation results indicate that the controlling model not only can output correct and optimal estimate for receiver state information, but also has an excellentdynamic tracking performance.

Rule Acquisition Method and Application of Dominance Decision-making Information System

SUO Zhong-ying， CHENG Si-yi， YUAN Xiu-jiu， LI Yan-ming

2015, 36(3):  539-544.  doi:10.3969/j.issn.1000-1093.2015.03.023

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Inview of the disadvantages of the existing rule acquisition method of dominance decision-making information system, such as small number rule acquirement or low rule accuracy, the decision discernibility set and discernibility matrix are defined, and an attribute reduction method of dominance decision-making information system is prsented. The rough set method based on dominance relation is applied to rank the objects, and then eliminate the unreasonable object compared with the decision attribute, and then the inconsistent dominance decision-making information system is transformed to the consistent one. The rule acquirement method of the consistent dominance decision-making information system is proposed, which conforms to the natural reasoning process and has strongly intuitionistic characteristic. The proposed method fully digs the information from the system and ensures the validity of the rules. This rule acquisition method is applied to radar target threat assessment, which is simple and feasible, and provides a new train of thought to solve the decision problem of which attribute contains “preference information”.

Electrostatic Electric Field Inversion Method for Ship Based on Point Charge Source Model

JIANG Run-xiang， LIN Chun-sheng， GONG Shen-guang

2015, 36(3):  545-551.  doi:10.3969/j.issn.1000-1093.2015.03.024

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For the issue of ship electrostatic field inversion, a method is proposed based on the point charge source. The position of equivalent point charge is set by the priori information. The number and accurate location of equivalent sources are calculated by using the Taylor expansion radius of convergence, and the linear equations for calculating the equivalent point source and the ship's equivalent electric moment are established. The effectiveness of the method is verified by the real data. The results show that the algorithm is high precision with the total error of less than 4%.

Storage Availability Modeling and Cost Analysis for a Repair-replacement Series System

YANG Li, MA Xiao-bing

2015, 36(3):  552-558.  doi:10.3969/j.issn.1000-1093.2015.03.025

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According to the maintenance features of long-term storage products， the transient storage availability models for two typical kinds of components are established, respectively. A kind of component is inspected periodically. A failure may be missed by inspections with a fixed probability, and as soon as the failure is found, the component is repaired to as good as new condition after a period of time. The other kind of component is preventively replaced periodically, and the length of its replacement cycle is an integral multiple of that of the inspection cycle. Subsequently, the transient and average storage availabilities of the system which is composed of these two kinds of components are deduced, and a maintenance cost model for such a storage system is established. The inspection cycle length and replacement cycle length are optimized comprehensively for minimizing the average maintenance cost rate in a fixed storage period. The computed results indicate that the combination of these two variables has a large effect on the cost rate. A conclusion can be drawn that a reasonable schedule of maintenance cycle contributes to the reduction in the maintenance cost for a long-term storage system.

Research Notes

Dynamic Evolution and Effects of Gas Phase in Cavitation of Axial Piston Pump

YUAN Shi-hua, ZHOU Jun-jie, LUO Xian-wei, JING Chong-bo

2015, 36(3):  559-565.  doi:10.3969/j.issn.1000-1093.2015.03.026

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A problem of gas cavitation existing in the operation of axial piston pump is addressed. The current models of evaluating the fluid properties (density, bulk modulus) commonly used in lumped parameter pump models do not consider the dynamic characteristics of gas cavitation. For this reason, a novel cavitation model which accounts for the dynamic characteristics of gas (free air and vapor), including gas evolution, and transport and distribution of gas between connected control volumes, is proposed. The model is integrated in a lumped parameter axial piston pump model, and the cavitation effects are investigated. The simulated results show that the proposed method has an advantage over the classic fluid models which tend to underestimate the effect of cavitation on the outlet flow and pressure of pump. The increase in outlet flow or pressure oscillation and the reduction in average flow rate in cavitating pump are due to the change of fluid compressibility induced by air release.

Test Technology for Operational Effectiveness of Portable Electro-optical Reconnaissance Equipment

SHI Sheng-bing, QIN Shao-gang, CHEN Zhen-xing, ZHANG Jun-sheng, SONG Hong-wei

2015, 36(3):  566-570.  doi:10.3969/j.issn.1000-1093.2015.03.027

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With the changes in war mode and battle style, the traditional performance test is changed to operational test for assessing the capacity of weapon system under the near real combat environment. The evaluation method of operational effectiveness has been widely studied, but little research on operational effectiveness test has been done. For the portable electro-optical reconnaissance equipment, the scheme design ideas of operational effectiveness test are presented based on war environment, index system and test implementation. The operational effectiveness is evaluated with ADC method. The test method is proved to be feasible through operational effectiveness test of two kinds of portable electro-optical reconnaissance equipment, and can be used for operational effectiveness evaluation of other weapon system.

Analysis of Surface-interface of Boronized Layer on Cr12MoV Cold-worked Die Steel

KONG De-jun, XIE Chun-yang

2015, 36(3):  571-576.  doi:10.3969/j.issn.1000-1093.2015.03.028

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The surface of Cr12MoV cold-worked die steel is boronized by the method of hot-dipping, and the surface and interface morphologies and the chemical and phase compositions are analyzed by SEM, EDS and XRD, respectively. The residual stress and retained austenite on the surface are analyzed, and the hot-dipped boronizing mechanism is discussed. The results show that the tiny pores exist on the surface of boronized layer, and are related to the elements which are not solubled in boride. FeB is formed in the diffusion layer that has a preferred orientation in crystal plane (002), and the chemical reactions and mutual diffusion of elements occur in the layer. The surface residual stress is changed from tensile stress to compressive stress, and the retained austenite is transformed into martensite after boronizing, which improves the friction and wear properties of cold-worked die steel.