Table of Content

26 February 2021, Volume 42 Issue 2

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Contents

Contents

2021, 42(2):  0. 

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Paper

Impact Temperature Rise Law of Porous Aluminum-rich PTFE/Al Energetic Material

CAI Shangye, JIANG Chunlan, MAO Liang, WANG Zaicheng, HU Rong, YE Sheng

2021, 42(2):  225-233.  doi:10.3969/j.issn.1000-1093.2021.02.001

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In order to obtain the influence of porosity on the temperature rise effect of aluminum-rich PTFE/Al energetic materials, an one-dimensional viscoplastic cavity collapse model considering the melting effect is used to theoretically analyze the impact temperature rise of the material. A micro-discrete model of aluminum-rich PTFE/Al with porosity of 10%, 20%, and 30% was established, and the numerical simulation was performed with the help of AUTODYN nonlinear dynamic finite element software to analyze the pore compression and temperature rise of porous aluminum-rich PTFE/Al energetic materials under impact loading. In addition, the numerically simulated result was validated through a split Hopkinson pressure bar (SHPB) experiment. The results show that the internal temperature of the material generally increases intermittently with the periodic loading of the incident bar; during the compression process, the temperature rise of porous aluminum-rich PTFE/Al energetic materials is mainly affected by the hole inner diameter velocity a· and the yield strength Y; compared with 20% and 30% porosity aluminum-rich PTFE/Al energetic materials, the 10% porosity aluminum-rich PTFE/Al energetic materials have the highest temperature rise during material compression.

Influences of Intelligent Design and Information Processing Modality Complexity on Occupant Mental Workload

GUO Sinan， WANYAN Xiaoru， LIU Shuang， LIANG Chaoran， CHEN Hao

2021, 42(2):  234-241.  doi:10.3969/j.issn.1000-1093.2021.02.002

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Rational intelligent and information design of armored vehicles is of great significance to reduce the mental workload and improve the effectiveness of armored vehicle occupants. In order to investigate the influences of intelligent design and complexity of information processing modality on occupant mental workload, and based on a new armored vehicle simulation platform, 20 subjects were selected to carry out a comprehensive experiment on the influencing factors of occupant mental workload according to the typical operational task of armored vehicle commander. The test results show that the NASA-TLX rating scale score, alpha band absolute power and task false operation rate under the condition of high-intelligent task are lower than those under the condition of low-intelligent task, and the saccade average peak speed under the condition of high-intelligent task is higher than that under the condition of low-intelligent task; in the audio-visual dual modalities task, higher NASA-TLX rating scale score, theta band absolute power and average pupil diameter are observed compared with the single visual modality task. The occupant mental workload under the condition of high-intelligent design is significantly lower than that under the condition of low-intelligent design, and the automation operation and intelligent human-computer interaction mode can effectively reduce the occupant workload of occupant under the high demand for information. The occupant mental workload under the condition of audio-visual dual modalities task is significantly increased compared with the single visual modality task, while the use of dual audio-visual modalities information processing mode is conducive to ensure a better performance under multi-task demands. In addition, the different physiological measurement indices have distinguished sensitivity and diagnostic ability to the influencing factors of mental workload.

State Estimation of Suspension System Based on Interacting Multiple Model Unscented Kalman Filter

WANG Zhenfeng， LI Fei， WANG Xinyu， YANG Jiansen， QIN Yechen

2021, 42(2):  242-253.  doi:10.3969/j.issn.1000-1093.2021.02.003

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The accuracy estimation of suspension state under the conditions of time-varying road excitation and model parameter uncertainty is realized to effectively solve the issue that the state estimation of the nonlinear suspension system cannot be accurately achieved under complex driving conditions. The state estimation of suspension system is studied. Based on the models of road profile excitation and nonlinear suspension system, a novel interacting multiple model unscented Kalman filter (IMMUKF) algorithm is designed using the interacting multiple model algorithm and Markovchain Monte Carlo theory. IMMUKF algorithm is used to estimate the movement state of suspension system under various working conditions. The stability conditions of the proposed algorithm is validated using the stochastic stability theory. The accuracy of the nonlinear suspension movement state was estimated in real-time by comparing the traditional unscented Kalman filter (UKF) algorithm with the proposed IMMUKF algorithm under the various road inputs, and the suspension system was tested and verified. Experimental and simulated results show that the higher accuracy of the proposed algorithm can be obtained, and the maximum root mean square error of state estimation of the proposed algorithm in simulation is less than 8%.

Global Sensitivity Analysis of a Self-propelled Gun's Structural Parameters for Position and Attitude of Projectile at Muzzle

LUO Zhongfeng, GUAN Xiaorong, XU Cheng

2021, 42(2):  254-267.  doi:10.3969/j.issn.1000-1093.2021.02.004

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The influences of the structural parameters of self-propelled gun on the position and attitude of projectile at muzzle should be reasonably assessed to improve the firing accuracy of self-propelled gun. An integral launch dynamics model of a self-propelled gun is established to solve the problem above. Then an approach of global sensitivity analysis is presented, which is based on the Rosenblatt transformation. In the approach, the first-order and total sensitivity coefficients of an independent variable are estimated with the help of a random continuous independent variable, and the first-order and total sensitivity coefficients of independent variables are estimated with the help of a set of random continuous independent variables. The global sensitivity analysis of a self-propelled gun's structural parameters for position and attitude of projectile at muzzle is conducted lastly based on the proposed model and the suggested approach. The results show that the longitudinal moment of inertia of chassis in the vertical plane is a main factor influencing the position and attitude of projectile at muzzle at the maximum range.

Ergonomic Evaluation and Optimization of Handwheel Size of Sighting Device for Towed Gun-howitzer

ZHAO Yiqian， WU Tianyu， GU Sen， LI Qingchen， LI Yajun

2021, 42(2):  268-280.  doi:10.3969/j.issn.1000-1093.2021.02.005

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Based on human-machine simulation and human-machine comprehensive evaluation methods, the diameter of handwheel, the height difference of mounting axis and the sectional dimension of grip were studied to improve the ergonomics of aiming operation of towed gun-howitzer. In the simulation evaluation, the dynamic operation behavior of gunner was simulated, and his operating posture was evaluated by using multiple indexes. During comprehensive evaluation, the real samples of 4 shapes of grips, i.e., spindle-shaped, clinder-shaped, pear-shaped and cone-shaped, were grasped and evaluated with the reference of the comment set. According to the logic of simulation and comprehensive evaluation,the theoretical model of evaluating and optimizing the handwheel of sighting device was derived and constructed from up-to-down in terms of application layer, evaluation layer, data layer and knowledge layer. The result shows that the optimization design of handwheel size should first adopt a wheel diameter of 250 mm and the height difference between the mounting axes of two wheels should be 200 mm. If the grip is in the shape of a spindle, cylinder or pear, the sectional diameter should is considered 30 mm in priority. If the grip is cone-shaped, its sectional diameter can refer to 34 mm. The sectional diameter can be flexibly adjusted within a reasonable range to well fit for the size of the gunner’s hands. The proposed theoretical model aims to accurately capture the optimal reference range of handwheel elements through rapid evaluation and is used to support the optimized design for the purpose of relieving the fatigue on hands, upper limbs, shoulders and back, reducing the risk of injury and thus improving the comfort.

The Evolution of Gun Barrel Damage and Its Relation with Elliptic Hole

XUE Jun, WANG Guanghua, QIAO Ziping, LI Junsong, ZHENG Qiu, HU Chundong

2021, 42(2):  281-288.  doi:10.3969/j.issn.1000-1093.2021.02.006

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The life firing experiment was carried out to investigate the damage evolution law of 12.7 mm large caliber machine gun barrel and its influence on elliptic hole. Optical microscope, scanning electron microscope, endoscope and caliber gauge were used to observe and measure the damaged barrel, and the damage rule of barrel bore during its life cycle was obtained. The results show that three typical barrel damage regions of 12.7 mm machine gun are at the initial position of refiled bore, the high bore pressure zone and the muzzle of barrel. The damage rates and modes are different in these three regions. The Cr layer in the initial region of refiled bore has a high shedding rate, leading to a high expansion rate of the inner diameter. In the early stage of the high bore pressure zone, the Cr layer remains intact, but in the later stage of life, the Cr layer falls off faster. The Cr layer at the muzzle of barrel is almost not shed, and the damage is mainly caused by wear. The barrel life of machine gun ends in the way of keyhole of bullet exceeding the standard. The forming reason of keyhole of bullet is that the refiling lands are damaged and stripped, which weakens the driving ability of refiling and makes the warhead rotate at a low speed, thus leading to the keyholes of bullet.

Analysis Method for Elastic Modulus of Typical Gun-propellant under Impact Loading

LIU Jihua， ZHAO Hongli， HE Changhui， JIN Jianwei， ZHANG Zouzou, WANG Qionglin, ZHAO Baoming

2021, 42(2):  289-296.  doi:10.3969/j.issn.1000-1093.2021.02.007

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The experimental research on drop hammer impacting of gun-propellant was made to obtain an effective analysis method for the elastic modulus of typical gun-propellant under impact loading. The stress and strain curves of gun-propellant during drop hammer impact test were obtained through high-speed photography and digital image correlation method. On this basis, the linear-elastic, nonlinear-elastic and viscoelastic analysis methods are used to get the change laws of elastic modulus of DAGR125-21/19 with impact energy and velocity at normal and low temperatures. The results show that the elastic modulus of gun-propellant changes slightly at normal and low temperatures with the increase in the impact velocity. Furthermore, the magnitude of elastic modulus from viscoelastic analysis is least, the results from linear elastic analysis are close to those from nonlinear elastic analysis, and the elastic modulus of gun-propellant at low temperature is much greater than that at normal temperature. The elastic modulus of SF-3 double-base gun-propellant was studied. It is found that the elastic modulus of SF-3 double-base gun-propellant is equivalent to that of DAGR125-21/19 at normal temperature, but the elastic modulus of the former is much bigger than that of the latter at low temperature. The reliable and accurate elastic modulus of gun-propellant can be derived by using viscoelastic analysis based on digital image correlation method.

Influence of Atmospheric Turbulence on Detection Accuracy of Laser Spot

LI Haiting, HU Xin, ZENG Shuang, LI Shaobo, ZHOU Guojia, GAO Zhifeng

2021, 42(2):  297-307.  doi:10.3969/j.issn.1000-1093.2021.02.008

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The mechanism of light intensity flicker, beam drift, angle of arrival fluctuation and beam spread effect to reduce the position accuracy of received laser spot is studied to analyze the influence of atmospheric turblence on the detection accuracy of laser spot in semi-active laser guidance. A quantitative measurement method is proposed for the parameter of atmosperic turbulence intensity (atmospheric refractive index constant). Based on this method, a prototype test was conducted. The speckle image information on the targets recorded under differeent weather conditions is used to calculate the arrivasl angle fluctuation variance and the structure constants of atmospheric refractive index at the irradiation distance of 1 km and 4 km. The laser spot position coordinate data from the output of seeker was tested under the different structure constants of atmospheric refractive index, and the statistical distribution of test data and standard deviation under different experimental conditions were given. The experimental results show that the greater the atmospheric refractive index constant is, the worse the spot detection accuracy is, and the atmospheric refractive index constant is not only related to the atmospheric turbulence intensity, but also related to the irradiation distance, which proves the effectiveness of the proposed method.

Complex Analysis for Angular Motion of a Spinning Projectile with One Pair of Canards

CHEN Cheng, ZHAO Liangyu, XIE Haoyi, HAO Xiaobing

2021, 42(2):  308-319.  doi:10.3969/j.issn.1000-1093.2021.02.009

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The stability of coning motion of spinning projectile with one pair of canards cannot be directly analyzed by the analytic method due to the aerodynamic asymmetry. The angular motion model and complex analysis method for the spinning projectile are studied. A complex angle-of-attack motion equation is established, and a scaling factor is introduced to the asymmetric aerodynamic term in the equation. On this basis, the analytical expressions of complex angle-of-attack motion equation under different actuator deflection angles are obtained. The convergence process, steady state and resonance of the model are analyzed. The validity of complex angle-of-attack motion equation is confirmed through numerical simulation, and the cause of resonance instability under sinusoidal actuator deflection is revealed.

The Influence of Blated Products of Pure Carbon/carbon Materials on Plasma Flow Field around Aircraft

NIE Chunsheng, YUAN Ye, ZHOU Yu, HUANG Jiandong, CHEN Xuan, ZHANG Qingqing

2021, 42(2):  320-326.  doi:10.3969/j.issn.1000-1093.2021.02.010

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The heat-resistant materials on the surface of high-speed aircraft may be decomposed and ablated under the high temperature generated by aerodynamic heating. After the ablated products enter the flow field, they react with the high-temperature air in the flow field, thus affecting the component concentration and plasma distribution in the air flow field around the aircraft. A high-temperature supersonic air flow is generated by high-frequency induction heating in a high-frequency plasma wind tunnel. A high-temperature flow field is formed around a pure carbon-carbon material model and a water-cooled copper model with the same shape. The electron number density at the different heights of distance model was measured by using Langmuir probe. The experimental results show that, when the pure carbon-carbon material model is in an obvious ablation state, the ablated products affect the electronic number density in the flow field, which is less than that in the pure air flow field of the water-cooled copper model; and the electronic number density in the flow field of multiple samples of the pure carbon-carbon material model after ablation decreases with the increase in the mass ablation rate. The ablated products only affect the electron number density in the flow field at a certain distance from the wall, and the electron number density in the flow field far away from the wall is close to that in the pure air flow field.

Ignition Reaction Rate Model of RDX-based Aluminized Explosives under Shock Waves

WANG Hongfu， BAI Fan， LIU Yan， DUAN Zhuoping， HUANG Fenglei

2021, 42(2):  327-339.  doi:10.3969/j.issn.1000-1093.2021.02.011

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The shock initiation of aluminized explosives was experimented and simulated to investigate the influence of constituent aluminum powder sizes on shock ignition and establish a microscopic reaction rate model for shock ignition of the RDX-based aluminized explosives. Four explosive formulae with the same initial component ratio and RDX particle size but with different aluminum grain sizes (5 μm, 16 μm, 40 μm and 100 μm) were designed, and the shock initiation experiments were conducted for these four RDX-based aluminized explosives. At the same time, a microscopic ignition model of RDX-based aluminized explosives was proposed by reasonable assumption, a microscopic reaction rate model considering the ignition growth was established, and the above experiments were numerically modeled by using this microscopic reaction rate model and I&G model of aluminized explosives. The experimental and simulated results show that 0.80%, 2.45%, 3.20% and 4.15% of aluminum are involved in the reaction for RDX-based aluminized explosives with 100 μm, 40 μm 16 μm and 5 μm aluminum powders in front of the CJ plane, respectively; with the decrease in aluminum powder sizes in aluminized explosives, the reaction rate of aluminum powders in front of the CJ plane increases, the faster the propagation velocity of the precursory shock wave increases, the greater the peak pressures in aluminized explosives are, and the time interval between the occurrence time of the peak pressure and the arrival time of the precursory shock wave are shorter, the explosive impact sensitivity increases. The pressure calculated using this microscopic reaction rate model are more reasonable agreement with the experimental results compared with I&G model. The microscopic model is applicable for simulating the reaction characteristics of large size aluminum powder in RDX-based aluminized explosives (the diameter of aluminum powder is larger than 1/10 of the explosive particle size) for the shock ignition process. For RDX-based aluminized explosives with 100 μm and 40 μm aluminum powders, the maximum error between the calculated parameters and the experimental results for arrival time of precursory shock wave, peak-pressure time and peak pressure at each Lagrange position is less than 10%.

A Numerical Scheme for Fluid-solid Interactions Based on Multi-medium Riemann Problem and Its Application in Explosion andImpact Problems

YAO Chengbao, FU Meiyan, HAN Feng, YAN Kai, LEI Yu

2021, 42(2):  340-355.  doi:10.3969/j.issn.1000-1093.2021.02.012

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In order to improve the accuracy of numerical simulation of multi-medium large deformation under explosive and impact loading, a general and robust multi-medium Riemann solver is proposed to solve the multi-medium interactions for the highly non-linear Mie-Grüneisen equation of state and hydro-elastoplastic constitutive equation. The solver can be used to improve the calculation accuracy of physical quantities at material interface. A numerical system is established to simulate the large deformation of compressible fluid and elastoplastic solid under extreme conditions by using the compressible multi-medium flow scheme. The fluid-solid Riemann problem, solid-solid Riemann problem, underground explosion problem, air blast problem and high-speed impact problem were simulated. The numerical results agree well with the analytical and experimental data, which reveals the capacity of the proposed algorithm in solving multi-medium flows, such as typical explosion and impact problems.

Fault Diagnosis of Analog Circuits Based on Improved Multilayer Kernel Extreme Learning Machine

ZHU Min， XU Aiqiang， XU Qing， LI Ruifeng

2021, 42(2):  356-369.  doi:10.3969/j.issn.1000-1093.2021.02.013

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A multi-layer simplex optimized kernel extreme learning machine (ML-SOKELM) method is proposed based on the testability application framework of simulation-based diagnostic model, which combines the deep learning and kernel-based method. ML-SOKELM method is used to to improve the practicability and accuracy of multi-fault diagnosis of analog circuits. The multi-layer kernel extreme learning machine (ML-KELM) extracts the fault features layer by layer and gets the diagnosed results with original data after primary selection. During the training process, the proposed method is used to optimize the kernel parameters of all layers. The diagnosed results show that, compared with the common deep learning methods, ML-SOKELM methed is less dependent on subjective experience and achieves considerable accuracy while greatly shortening the training time. ML-SOKELM can achieve higher diagnostic accuracy under different ambiguity thresholds in comparison with popular kernel-based methods.

A Surface and Point Sound Sources Combined Method for Calculating Radiated Noise

LIU Bao， HU Jinhua， CHENG Guangli

2021, 42(2):  370-378.  doi:10.3969/j.issn.1000-1093.2021.02.014

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The non-uniqueness of sound field solution at corresponding structural internal characteristic frequencies and the high sensitivity of the solution to the point sound source positions exist in virtual point sound source method. A method is proposed to utilize the surface sound sources and point sound sources to model the sound field, thus achieving the uniqueness of solution and the high calculation accuracy in the whole wavenumber domain. According to wave superposition principle, the virtual surface sound sources and point sound sources are simultaneously arranged inside the structure to disperse the sound fields. The surface sound sources are located on a surface conformal to the structural boundary in order to match the sound pressure and vibration velocity of the structural surface. The point sound sources are located inside the virtual surface.A sound radiation impedance matrix was constructed using the linearized Euler equation, and the acoustic parameters of the structure, such as surface sound pressure and vibration velocity, were obtained. Taking pulsating spherical source and transverse vibration spherical source as examples, on the basis of comparing the calculation accuracies of using surface sources and point sources, the accuracy and uniqueness of the proposed method are illustrated by comparing the results with the analytical solutions.

Effect of Intermediate Annealing on the Corrosion Resistance of Hot-rolled 5059 Aluminum Alloy

LIN Hongcai, ZHU Qingfeng, SHI Ruwen, JIA Tao, ZHANG Enge, ZHAO Zhihao

2021, 42(2):  379-387.  doi:10.3969/j.issn.1000-1093.2021.02.015

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The 5059 aluminum alloy plates, such as hot-rolled plate, hot-rolled annealed plate, direct cold-rolled plate and cold-rolled annealed plate, were prepared with intermediate annealing and cold rolling to study the effect of intermediate annealing on the corrosion resistance of the alloy. The intergranular corrosion properties of different plates were analyzed according to U.S. ASTM G67-2013 standard. The results show that the partial recrystallization happens and the corrosion resistance of the plate is significantly improved after the annealing treatment of hot-rolled plate at 400 ℃ for 2 h. With annealing at 400 ℃ for 2 h, the corrosion weight loss of the hot-rolled plate decreases from 8.9 mg/cm² to 3.1 mg/cm², and the depth of corrosion channel on L-S cross-section decreases from 70 μm to 6 μm. The cold-rolled plates prepared with different states of the hot-rolled plates (with and without annealing) show quite different level of corrosion resistance. The corrosion weight losses of the cold-rolled plates with and without intermediate annealing are 17.3 mg/cm² and 9.5 mg/cm², and the depths of corrosion channel on L-S cross-section of the corresponding plates are 65 μm and 45 μm, respectively. The L-T and T-S cross-sections of hot-rolled plate present exfoliation corrosion morphology, and the L-T cross-section shows gully corrosion morphology. After annealing 400 ℃ for 2 h, the corrosion morphologies of 3 cross-sections are all transformed into pitting morphology.

Small Sample Circular Error Probable Estimation Based on Fusing Simulation and Flight Test Data

NING Xiaolei, WU Yingxia， ZHAO Xin

2021, 42(2):  388-398.  doi:10.3969/j.issn.1000-1093.2021.02.016

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When Bayes method is used to evaluate the circular error probable (CEP), the simulation data is easy to “submerge” the live ammunition flight test data, which often leads to the ineffectiveness or even mistake of evaluated results. To solve this problem, a flight and simulation data fusion algorithm based on “effective sample” and a small sample CEP evaluation method for fusing simulation data and flight data are proposed. The evaluation model of sampling efficiency in importance sampling method is used to measure the deviation between the simulation prior distribution and the overall distribution, and the simulation prior distribution considering the deviation of simulation prior information is established. In the process of fusion evaluation, the weights of simulation samples are calculated according to the deviation between the prior distribution and the overall distribution and the sample size, instead of the original method only relying on the test times of prior test. Experiments and application cases show that the proposed method is significantly better than the traditional method in CEP estimation, which can effectively solve the problem of small sample CEP evaluation in equipment evaluation and validation test.

Simulation Dataset Usability Evaluation Algorithm Based on Correlation Analysis for the Command Information System

TIAN Xiangxuan, LI Junqi, JIN Liya, LIU Zhengren, SHI Zhiqiang

2021, 42(2):  399-407.  doi:10.3969/j.issn.1000-1093.2021.02.017

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A correlation analysis-based usability evaluation algorithm (CA-UEA) of the simulation dataset for the command information system is proposed for assessing the usability of simulation dataset for the command information system based on correlation analysis. The relevance evaluation criteria of the simulation dataset are defined. The basic information matrix, redundancy tensor and interaction tensor are constructed separately. Approximate formulas for calculating interactive information and redundant information are proposed. The correlation tensor of dataset is solved by Einstein summation constraints. And the error distance between the generated and original dataset usability tensors is calculated based on the loss function in deep learning. The simulated results show that the proposed algorithm can better represent the usability of dataset and provide the identification basis of the data generation algorithm.

Architecture of Theater Logistics and Equipment Support Command Information System Based on UAF

LIU Jingting， GUO Jikun， SHAO Fang

2021, 42(2):  408-421.  doi:10.3969/j.issn.1000-1093.2021.02.018

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The command information system is the “nervous system” that combines the elements and releases the effectiveness of the system's joint operations in theater logistics and equipment support command. Starting from the “network-cloud-end” structure that the military information system relies on, it combines the principle of the recently released unified architecture framework (UAF) method. The specific domain models are selected, which meet the requirements of our military's theater joint operations logistics and equipment support command information system, and a development process is designed. And then the corresponding domain metamodel element relationships are “cut + modified + merged” as needed while unifying the connotation of the model. Finally, the domain metamodel is used as a constraint to analyze the theoretical mechanism and model integration construction of the logistics and equipment support command information system from five key perspectives: capability, function, structure, service, and security. According to the scenario of joint operations in theater, the Objects Petri Net method is used to verify the dynamic model of command information system. The result shows that the system integration design structure is reasonable and the process logic is correct, which can meet the needs of command information service.

Research Notes

Design and Performance of Electro-hydraulic Full Hydraulic Brake System for 8×8 All-electric Drive Off-road Vehicle

CHEN Jinshi， LIU Siyuan， WANG Tongjian， HUO Dongyang， ZHANG Meirong， ZHANG Fei

2021, 42(2):  422-429.  doi:10.3969/j.issn.1000-1093.2021.02.019

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A principle and scheme of a electro-hydraulic full hydraulic brake system for 8×8 electric drive off-road vehicle is designed according to the performance index requirements of brake system for independent electric drive vehicle. In considering the influence of the system's long pipeline characteristics on the output braking performance, a test platform with the whole vehicle components and pipeline arrangement at ratio of 1∶1 was built, and the output characteristics of the whole hydraulic brake system under different working conditions were studied. The results show that the output braking force and braking response time of the new electro-hydraulic full hydraulic brake system meet the requirements of braking performance index (braking force of 12.0 MPa, and response time of 0.2 s-0.3 s); the braking output pressure is linearly related to the displacement and change rate of the brake pedal; when the electric control system fails, the whole hydraulic brake system can still meet the braking demand of the whole vehicle.

Antiaircraft Firing Strategy of Electromagnetic Railgun with Adjustable Muzzle Velocity of Projectile

ZHANG Zhiyong, WANG Tuantuan, GUO Hao, WANG Yafei

2021, 42(2):  430-437.  doi:10.3969/j.issn.1000-1093.2021.02.020

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The firing strategy of electromagnetic railgun against an air target within line-of-sight range is studied based on the adjustable characteristics of projectile speed. A 6-DOF exterior ballistic equation set and a hit probability model for single-shot and whole-route continuous-shot firing on air targets are established. The impacts of target distance and muzzle velocity on hit probability in the cases of single-shot firing and whole-route continuous-shot firing are analyzed. The results show that, during the single shot firing, the higher the muzzle velocity is, the higher the hit probability is. In the whole-route continuous-shot firing, the cumulative hit probability increases first and then decreases with the increase in muzzle velocity, but there is local step-decreasing phenomena. A whole-route balanced firinging strategy, which is from the near to the distant, the highest single shot hit probability within effective range and multiple multiround simultaneous impact on the far side, can take into account the whole-route cumulative hit probability and the naval strike cost, and obtain a better operational effectiveness at a lower strike cost.

Influence of Angle of Attack on Initial Ejection Trajectory of Missile

ZHANG Bing, HOU Ming, WANG Dianyu, DONG Youliang

2021, 42(2):  438-448.  doi:10.3969/j.issn.1000-1093.2021.02.021

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For the instability of separation process of missile, the influence of angle of attack on the initial ejection trajectory of air-to-air missile is analyzed by solving fluid dynamics equations and 6DOF equations of rigid body. Referring to American AEDC's captive trajectory system (CTS) testing, in which uses a generic wing/pylon/finned store model, a similar geometric model is established and numerical calculation is carried out. The feasibility of the numerical calculation method is verified by comparing the numerical results and the CTS results in Ref.［29］. The method is used to calculate and analyze the initial trajectory of an air-to-air missile launched from a fourth-generation fighter under different angles of attack. The following laws are revealed by the analysis: under supersonic condition, 6DOF motion of missile is apparently influenced by the angle of attack at the initial ejection stage. With the increase in the angle of attack, the pitch motion of missile becomes more intense, the roll angle becomes larger, and the yaw angle becomes smaller. The velocity of missile-separation from aiacraft decreases obviously, and the safety of missile-separation from aiacraft decreases gradually.