Table of Content

21 September 2018, Volume 39 Issue 9

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Contents

2018, 39(9):  0. 

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Paper

Modeling and Experimental Validation of Drag Torque of Wet Multi-disk Clutch with Spline Connected Restriction in Full SpeedRange

SHI Lu-qi， MA Biao， LI He-yan， WU Jun-feng， LI Hui-zhu， YAN Xu， CHANG Fu-xiang

2018, 39(9):  1665-1674.  doi:10.3969/j.issn.1000-1093.2018.09.001

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A theoretical model is established for the analysis of offset state of friction elements under the condition of low speed difference based on the gyro effect. As for the gap shrinkage under the condition of high speed difference, a negative pressure contraction model for friction pairs is built by analyzing the oil film and the pressure on friction plates. The dynamic change of gap between the friction pairs in the whole variation range of the relative speed is then investigated. Finally, an improved model, considering the influence of dynamic change of gap between the friction pairs, is proposed to study the drag torque. The simulated and test results indicate that, under the condition of the same lubrication, the drag torque of the wet multi-plate clutch increases first and then decreases and finally increases with the rise of the rotational speed difference. The main factors influencing the drag torque are the offset of friction plate under the condition of the low speed difference (0-1 000 r/min), and the gap shrinkages under the condition of the middle and high speed differences (>1 000 r/min). Through the comparison of test results and the simulated results obtained from the improved model, the average relative error is only 6.34% under the condition of medium and high speed differences (>1 000 r/min), which can greatly improve the estimation accuracy of drag torque of wet multi-plate clutch.Key

Longitudinal and Lateral Path Following Coordinated Control Method of Tracked Vehicle Based on Double-layer Driver Model

WANG Bo-yang， GONG Jian-wei， GAO Tian-yun， ZHANG Rui-zeng, CHEN Hui-yan， XI Jun-qiang

2018, 39(9):  1675-1682.  doi:10.3969/j.issn.1000-1093.2018.09.002

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A longitudinal and lateral joint path following coordinated control method based on double-layer driver model is proposed to solve the path following control problem of tracked vehicle with clutch and brake steering structure. The first layer of driver model is based on the Gaussian mixture model and hidden Markov model. The desired path is taken as an input. The aim is to predict the steering mode sequences and switch the control mode according to the sequences. The second layer of driver model is established by using the fuzzy logic to reflect the skilled driver’s longitudinal and lateral operation experience. The longitudinal and lateral control commands are calculated according to the desired deviation of course. The results show that the driving experience can be utilized effectively to settle a challenge due to longitudinal and lateral combined vehicle dynamic characteristic and steering uncertainty in the proposed control method. The lateral control accuracy is less than 1.0 m under the particular scenario.Key

Planetary Gearbox Fault Feature Extraction Based on Parameter Optimized Variational Mode Decomposition and Partial Mean ofMulti-scale Entropy

YANG Da-wei， ZHAO Yong-dong， FENG Fu-zhou， JIANG Peng-cheng， DING Chuang

2018, 39(9):  1683-1691.  doi:10.3969/j.issn.1000-1093.2018.09.003

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A fault feature extraction method based on parameter optimized variational mode decomposition（VMD）and partial mean of multi-scale entropy is proposed for the extraction of planetary gearbox fault features. The particle swarm optimization（PSO） is used to optimize VMD parameters to overcome the drawback of subjectively selecting the parameters, and the signal is processed by parameter-optimized VMD. The effective components are selected by mutual information to reconstruct signal. Multi-scale entropy can be used to analyze the complexity of signal under different scale factors, and partial mean can be used to reflect the mean value and variation trend of data. Based on multi-scale entropy, the partial mean of multi-scale entropy is used to measure the operating states of planetary gearbox, thus extracting the fault features. The processed results of planetary gearbox experimental data show that the proposed method can be more effective for planetary gearbox fault extraction.Key

Numerical Simulation of the Influence of Boundary Shape on the Expansion Stability of Four Combustion-gas Jets

FENG Bo-sheng， XUE Xiao-chun

2018, 39(9):  1692-1700.  doi:10.3969/j.issn.1000-1093.2018.09.004

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The influence of boundary shape on the expansion stability of four combustion-gas jets under cold conditions is discussed to study an approach to improve the combustion stability of bulk-loaded liquid propellant gun. High-speed digital video recording system is used to record the expansion process of four combustion-gas jets in a five-stage cylindrical stepped-wall type observation chamber. On this basis, a three-dimensional unsteady mathematical model of gas-liquid interaction is established to simulate the expansion processes of four combustion-gas jets in a five-stage cylindrical stepped-wall type, conical and cylindrical observation chambers. The three-dimensional two-phase distribution chart, pressure and temperature distribution chart of jet field were obtained. The results show that the simulated results of axial displacements of four combustion-gas jets in the five-stage cylindrical stepped-wall type chamber coincide well with the experimental results. Both the cylindrical stepped-wall type chamber and the conical chamber can enhance the radial expansion of combustion-gas jet and effectively suppress Taylor cavity and Helmholtz instability; due to gradual induction of stepped-wall in the cylindrical stepped-wall type chamber, the temperature field near the nozzle has no severe pulsation and the jet expansion is more stable. Key

Ballistic Range Correction Algorithm Based on an Improved Unscented Kalman Filter

LEI Xiao-yun, ZHANG Zhi-an, DU Zhong-hua

2018, 39(9):  1701-1710.  doi:10.3969/j.issn.1000-1093.2018.09.005

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For the ballistic range correction projectiles utilizing GPS as the projectile-borne detection system, the received dynamic data is susceptible to contamination from measurement noise and system noise, and data loss and exception happen in the high-overload environment. An improved unscented Kalman filter (UKF) based on Newton interpolation method is proposed to reduce the measurement error, thereby decreasing the predicted error during range correction. Data sets with abnormal errors are distinguished and reestimated. The improved UKF algorithm is used to reduce the influence of abnormal measurements and data loss on filtering effect, and more sensitive to measurement error. The improved unscented Kalman filter is designed to be adopted in an ballistic range correction algorithm. The simulated and test results indicate that the preprocessing effect could be maximized if the step size of system discretization is equal to the GPS update interval; the improved correction algorithm is able to reduce the correction errors induced by GPS data. The sample size of GPS data in preprocessing is related to the correction moment and GPS update interval, and it is not restricted by the algorithm effect.Key

Recognition of Jamming and Target Signal for Pulse Doppler Fuze Based on FCM Algorithm with Incremental Update

DAI Jian, YAN Qi, YAN Xiao-peng, LI Ping, LI Ze

2018, 39(9):  1711-1718.  doi:10.3969/j.issn.1000-1093.2018.09.006

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A fuzzy c-means (FCM) method with self-adaptive update function is proposed to improve the target recognition accuracy of pulse Doppler (PD) fuze in the complex electromagnetic environment. Based on the analysis of the output signal from fuze range-gate, the time domain and frequency domain entropies of signal are used for the recognition of target signal and jamming by means of FCM method. A modified incremental update algorithm is used to update and adjust the FCM classification model when the signal-to-jamming ratio decreases. The simulated results indicate that the modified incremental update algorithm can not only reduce the time-consuming, but also keep the recognition accuracy of target signal and jamming at 96.43% at -15 dB SNR, which significantly improves the anti-active noise jamming ability of pulse Doppler fuze. Key

Effect of Forming Process on Casting Quality of 24-Dinitroanisole-based Casting Explosive

MENG Jun-jiong， ZHOU Lin, JIN Da-yong， NIU Guo-tao, WANG Qin-hui

2018, 39(9):  1719-1726.  doi:10.3969/j.issn.1000-1093.2018.09.007

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Pressure casting and vacuum casting are used to improve the charge quality of DNAN-based melt-cast explosives, and the influences of casting precess on the temperature field, shrinkage porosity, relative density and tensile strength of DNAN-based melt-cast explosive are investigated. The results show that pressure casting can shorten the solidification time of DNAN-based melt-cast explosive and reduce its shrinkage cavity and porosity. When the molding pressure reaches 0.8 MPa, the relative density and tensile strength of DNAN/HMX explosives are increased by 6.4% and 9.9%, respectively, and no cracks are found in the grain. As for DNAN/RDX explosives, the relative density can be increased by 2.7%, and the tensile strength can be reduced by 40.8%, but the cracks exist in the grain. Although vacuum casting has no effect on the temperature field in solidification process, it can reduce the shrinkage cavity and porosity. When the vacuum degree reaches 0.08 MPa, the relative density and tensile strength of DNAN/RDX explosives are increased by 2.0% and 14.3%, respectively, and no cracks are found in the grain. Therefore, pressure casting and vacuum casting can be used respectively to improve the charge quality of DNAN/HM explosives and DNAN/RDX explosives.Key

Research on Autocatalytic Thermal Decomposition Properties and Thermal Safety of NTO

WANG Kai, WANG Jun-lin, XU Dong, GUO Tian-ji, WANG Wei, TU Jian

2018, 39(9):  1727-1732.  doi:10.3969/j.issn.1000-1093.2018.09.008

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Differential scanning calorimetry (DSC) technique is used to study the thermal decomposition and safety parameters of 3-nitro-1,2,4-triazol-5-one (NTO). The “interruption and rescanning” and Swiss methods are used to evaluate the autocatalytic effect during thermal decomposition of NTO, which was verified by isothermal DSC experiments. The decomposition kinetic parameters of NTO are determined by using the Friedman isoconversional method. The kinetic parameters with heat balance are analyzed and used to estimate the time to the maximum reaction rate under adiabatic conditions (TMR_a). The results show that the initial thermal decomposition temperature of NTO is in the range of 249.4- 271.2 ℃ at the heating rates of 2, 5, 10 and 20 ℃/min, and the decomposition reaction of NTO is an autocatalytic reaction. Thermal history has significant influence on the thermal stability of NTO, where the preheating would decrease its initial thermal decomposition temperature and the peak temperature. T₈ and T₂₄ of NTO are 166.1 and 152.1 ℃, respectively. Key

Anti-disturbance Control for Hypersonic Vehicles Based on Acceleration Measurement

ZHANG Shen， WANG Qing， DONG Chao-yang， YANG Ge

2018, 39(9):  1733-1740.  doi:10.3969/j.issn.1000-1093.2018.09.009

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An anti-disturbance backstepping control scheme based on acceleration measurement is proposed for the complexity and uncertainty of the aerodynamic characteristics of air-breathing hypersonic vehicle（AHV）. The control scheme includes both internal and external loop designs. The external loop introduces the measured acceleration signals of sensor in the backstepping method. And a nonlinear disturbance observer is designed to observe and compensate the composite disturbance. The dynamic inversion method based on singular perturbation theory is used for the internal loop design. The Lyapunov theory is used to prove the uniformly ultimately bounded stabilization. In this scheme, the control signal is totally constituted by signals which can be directly measured by sensors. The controller has high robustness for the uncertainty of aerodynamic parameters. Moreover, the anti-disturbance capacity is improved by the disturbance observer. The simulated results demonstrate that the control scheme can obtain desired control performance considering high uncertainty and external disturbance. Key

Finite-time Convergent Guidance Law against Multipath Interference

CHEN Feng, HE Guang-jun

2018, 39(9):  1741-1748.  doi:10.3969/j.issn.1000-1093.2018.09.010

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When the radar seeker overlooks and detects an ultra-low altitude target, the tracking precision is greatly reduced because of the existence of multipath interference. In order to minimize the interference, the line-of-sight (LOS) angle must be constrained to Brewster’s angle. A nonsingular fast terminal sliding mode guidance law is designed based on the terminal sliding mode control method. Aiming at the problem that the target acceleration is difficult to be accurately obtained using the guidance law, a sliding mode disturbance observer (SMDO) is designed to estimate the target acceleration. A composite nonsingular fast terminal sliding mode guidance law is designed by introducing the estimated value of the observer and the sign function with switches coefficient into the nonsingular fast terminal sliding mode guidance law. It is proved by Lyapunov theory that the proposed composite guidance law enables the LOS angle to converge quickly to the Brewster angle and the LOS angular rate to converge to a small neighborhood near zero in finite time. Simulated results show that the miss distance is reduced within the kill radius when the proposed guidance law is used in the ultra-low altitude target interception. Compared with the traditional sliding mode guidance laws, the convergence time of the system state can be reduced about 4 s by the proposed guidance law.Key

Error Analysis and Rotation Scheme Research of Single-axis Rotary SINS

LIU Sheng-pan， WANG Wen-ju， RAO Xing-qiao

2018, 39(9):  1749-1755.  doi:10.3969/j.issn.1000-1093.2018.09.011

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The error modulation principle and rotation scheme of single-axis rotary strapdown inertial navigation system (SINS) are studied, and the rotary modulation compensation of errors is analyzed. Single- axis unidirectional continuous rotation scheme, more than 360° two-position rotation-stop scheme, and less than 360° four-position rotation-stop scheme are designed. A long time navigation simulation of two- and four-position rotation-stop schemes is carried out under the swing state. The simulated results show that the positioning accuracies of the two- and four-position rotation-stop schemes are nearly the same. The four-position rotation-stop scheme is selected for engineering application. The rotary SINS using the four-position rotation-stop scheme is verified through the turntable and vehicle-mounted experiments, respectively. The results meet the initial design indexes of system and have reference value for engineering. Key

Test and Simulation of Deployment Process of Missile Folding-wings during Launching

ZHEN Wen-qiang, YANG Qi, JI Yong-qiang, SHI Yun-guo

2018, 39(9):  1756-1761.  doi:10.3969/j.issn.1000-1093.2018.09.012

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The deployment process of missile folding-wing during launching is studied. The real launching processes of test missiles are simulated, two kinds of folding-wings with different stiffness are tested, and some images and trajectory data of the test missiles are obtained. A dynamic model of deployment process of folding-wings, including the angle of attack and the velocity of test missile, is established, in which the change in angle of attack of test missile is due to launching disturbance. The comparison of the proposed dynamic model and CFD method shows a good agreement for the large rotating angle of airfoil surface. In the test, the deployments of the little stiffness folding-wings are unsynchronized, the deployments of the lower wings are lagged obviously. The proposed dynamic model gives the results of the deployment process by using the measured velocity and angle of attack. Key

A Network Control-based QoS-enhanced MAC for UAV Cloud

GAO Ang, DUAN Wei-jun, LI Li-xin, ZHANG Hui-sheng, HU Yan-su

2018, 39(9):  1762-1771.  doi:10.3969/j.issn.1000-1093.2018.09.013

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Unmanned aerial vehicle (UAV) cloud can greatly enhance the intelligence of unmanned system by dynamically uploading the compute-intensive applications to the cloud. The different UAV missions may have different quality of service (QoS) requirements due to the uncertainty of UAV missions and the fast-changing battlefield environment. A BP neuron network-based feedback differentiated control approach for QoS-aware (BPFD)-MAC in UAV cloud is proposed, which can support both absolute and relative QoS guarantees with the consideration of energy saving. The hardware experiments demonstrate the feasibility of BPFD-MAC. Under heavy loads, BPFD has better throughput and power use efficiency; and under light load, BPFD has lower total energy consumption.Key

Simulation Study of Ventilated Supercavity in a Periodic Gust Flow

WANG Wei, WANG Cong, DU Yan-feng, LI Cong-hui

2018, 39(9):  1772-1779.  doi:10.3969/j.issn.1000-1093.2018.09.014

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A flow field model is established to obtain the multiphase flow characteristics in a periodic gust flow. The proposed model is verified by comparing with the experimental data. Based on the proposed model, the characteristics of ventilated supercavity in a periodic gust flow are numerically simulated. The results show that the gust generator with periodic oscillation flow placed upstream can produce gust flow in the downstream flow field, and the wavelength of gust flow decreases and its amplitude increases with an increase in frequency; the wavelength and amplitude increase with an increase in flow velocity. Ventilated supercavity in the downstream of flow field is deformed by the gust, and the deformation is more obvious with an increase in frequency. The shape of supercavity is more stable with an increase in flow velocity. The wavelength of gust is equal to the ratio of flow velocity to gust frequency, and the effect of long wave on the shape of supercavity is smaller than that of the short wave. The cavitation number periodically changes by the influence of gust flow, and the mode of gas leakage also changes. The momentum of the supercavity tail increases with an increase in the cavitation number, which affects the mode of gas leakage in the double vortex tube of cavity tail. Key

Research on the Trajectory Characteristics of Supercavitating Vehicle Obliquely Entering into Water at Preset Rudder Angle

CHEN Cheng， YUAN Xu-long， XING Xiao-lin， DANG Jian-jun

2018, 39(9):  1780-1785.  doi:10.3969/j.issn.1000-1093.2018.09.015

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A series of experiments of supercavitating vehicle at the entry angle of 20° are carried out to investigate the trajectory characteristics of supercavitating vehicle at preset rudder angle during oblique water-entry. An air cannon is set up to provide the initial velocity of supercavitating vehicle. The flow pattern in water-entry cavity is captured by using a high-speed video camera, and the variations of the motion parameters and tail pressure are recorded by using a built-in measuring system. The experimental results of supercavitating vehicle navigating at the preset rudder angles of 0° and 20° are analyzed in detail, and the water-entry trajectory characteristics of supercavitating vehicle are given. The influences of different preset rudder angles on the trajectory are further studied. The experimental results show that the vehicle moves along a straight line in a supercavitation state when the preset rudder angle is 0°; a remarkable tail-slapping phenomenon arises, and the axial force and the normal force increase when the preset rudder angle is 20°, thus causing the trajectory to bend to the surface of the water. The vehicle eventually navigates in the state of double-cavity, with enhancing the trajectory deflection. Increasing the preset rudder angle can improve the deflection ability of the vehicle. Key

Research on Dispersion Characteristics of Scholte Wave in Shallow Sea

LUO Xia-yun, CHENG Guang-li, ZHANG Ming-min, LIU Yan-chun

2018, 39(9):  1786-1794.  doi:10.3969/j.issn.1000-1093.2018.09.016

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In order to study the dispersion characteristics of Scholte wave propagation in shallow sea, the characteristic equation of Scholte wave is deduced based on the seabed semi-infinite space model. The dispersion characteristics of Scholte wave under the condition of several kinds of typical elastic solid seabed are simulated. The frequency band of Scholte wave energy concentration is found by using the wavelet transform method to analyze the experimental data. The dispersion characteristics of Scholte wave are studied by using moving window analysis method. From the analysis of experimental data it is found that the energy of Scholte wave is mainly concentrated in 5-15 Hz, and there is obvious dispersion phenomenon in 5-10 Hz. The results show that the expermental results of the lake are consistent with the theoretically simulated results in the law of dispersion, and the moving window analysis method can be used to analyze the dispersion characteristics of Scholte wave. Key

Research on Ant Colony Strategy with Multi-constraint and Multi-response for Three-dimensional Route Planning of UnderwaterPlatforms

XIA Wei-xing， YANG Xiao-dong

2018, 39(9):  1795-1803.  doi:10.3969/j.issn.1000-1093.2018.09.017

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An ant colony strategy for three-dimensional path planning of underwater platforms is designed to improve the effectiveness and applicability of path planning algorithm, overcome the limitations of traditional single performance index optimization and terrain constraint, and realize the full application of three-dimensional marine environmental factors from the aspects of safety, concealment and rapidity. All kinds of constraint factors and performance indexes，such as performance of underwater platform, terrain, marine environment and mission constraints, are considered in the ant colony strategy. The grid model is introduced to describe the three-dimensional marine space, and the multi-constraint heuristic function and multi-index evaluation function are designed. The algorithm is simulated and verified. The result shows that the algorithm fully considers the influence of marine environment, and the three-dimensional navigation planning with different performance indexes and different mission constraints can be realized by setting the planning coefficient flexibly based on multi-constraint heuristic function and multi-index evaluation function, which can better achieve the navigation requirement of underwater platform.Key

Micromachining Processes for Si Microchannel Plates

WANG Guo-zheng, YUAN Yun-long, YANG Chao, LING Hai-rong, WANG Ji, YANG Ji-kai, LI Ye, DUANMU Qing-duo

2018, 39(9):  1804-1810.  doi:10.3969/j.issn.1000-1093.2018.09.018

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Microchannel plate (MCP) is a two-dimensional electronic multiplier widely used for detecting and imaging of electrons, ions, UV radiation, and X-ray. A method for fabricating Si-MCP was proposed and studied. Silicon microchannel arrays (SMA) are prepared by dry etching technology and electrochemical etching process, respectively. The characteristics of multiplex inductively coupled plasma (ICP) etching and photo-electrochemical etching are investigated and discussed. The results indicate that Si photo-electrochemical etching can be used to easily fabricate high aspect ratio microchannel arrays with smooth sidewall and sloped channel, and is more suitable for the preparation of Si-MCP. Si microchannel arrays with 6 μm spacing and more than 50 aspect ratio of microchannel were prepared. The insulation of Si-MCP substrate is solved using thick-layer oxidation. The continuous dynode is prepared by atomic layer deposition (ALD) process. Si-MCP samples were prepared. The measured results indicate that the electron gain of Si-MCP based on micromachining process is feasible.Key

Analysis of Double-layer Eastic Mechanics and Machining Characteristics of Pneumatic Grinding Wheel

ZENG Xi， PAN Ye， ZHANG Li， JI Shi-ming， CHEN Guo-da， HANG Wei

2018, 39(9):  1811-1819.  doi:10.3969/j.issn.1000-1093.2018.09.019

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The double-layer elastic mechanics theory of pneumatic grinding wheel with softness consolidation abrasives (SCA) is analyzed for improving the finishing of freeform surface of laser hardened mould with high hardness. Under the circular uniformly distributed stress, the ratio factor m of elasticity modulus of abrasives layer to that of rubber layer and the ratio n of abrasives layer thickness to radius of stress are introduced to establish a machining force model and deformation formula of double-layer elastic wheel. And then a double-layers elastic model of wheel is established by using ANSYS, and the machining process is simulated. Stress distribution and deformation rule are given through simulation. In the experiment, the fiber is used to reinforce the inner rubber layer, and the binder is used to hold the abrasive particles. Microcosmic analysis demonstrates the analytical hypothesis of double-layer elastic mechanics. A machining platform is set up. The experimental results show that the freeform surface of laser hardened mould can be efficiently finished by using the pneumatic grinding wheel. The pneumatic grinding wheel with lower factor n can help to decrease R_a for concave surface, and the pneumatic grinding wheel with higher factor n can improve the machining efficiency of convex surface.Key

Estimation of Parameters and Order of Fractional Order Transfer Function in Fractional Order Model of Thermocouple

LI Wen-jun， WANG Xiao-nan， ZHENG Yong-jun

2018, 39(9):  1820-1828.  doi:10.3969/j.issn.1000-1093.2018.09.020

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The fractional order model of thermocouple is used to study the dynamic characteristics of thermocouple. In dynamic system temperature measurement, a delay of temperature response exists when the thermocouple is used to measure the transient temperature. The process of measurement is a time-delay process or genetic process. When thermocouple wires come into contact with an object being measured, the heat transfer occurs through the wires. The temperature on measuring junction results from the heat transfer between medium and measuring junction and the heat conduction between measuring junction and wires. A fractional order model of semi-infinite solid heat conduction is established based on the theory of fractional calculus. The proposed model describes the heat transfer between the measuring junction and the measured medium, including the heat transfer between the measuring junction and the wire. A fractional order transfer function is obtained by fractional Laplace transform. The transfer function describes the time lag of thermal inertia and the phase delay of thermal diffusion. An experimental system for measuring the surface temperature by thermocouple is built to collect the input and output data of thermocouple under the step perturbationed. Based on measured input and output data, the parameters and order of fractional order transfer function are estimated by using the new Luus-Jaakola algorithm. The experimental and calculated results show that the fitting results of variable fractional order transfer function are better than those of invariable fractional order transfer function.Key

Evaluation Method for Equipment Importance Considering Bi-layer Coupled Complex Network

LIU Yan, CHEN Chun-liang, ZAN Xiang, CHEN Wei-long

2018, 39(9):  1829-1840.  doi:10.3969/j.issn.1000-1093.2018.09.021

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A new equipment importance evaluation method considering a bi-layer coupled complex network is proposed to deal with the problem that the current equipment importance evaluation methods ignore the features of equipment functional structure and the influence of equipment attribute. Based on the analysis of equipment importance evaluation system, the spatial relationship between the equipment and the command and control, and the cooperative relationship between equipment functions are considered, and a bi-layer coupled complex network is established. A relevant node importance evaluation method is designed. In consideration of the importances of equipment node and equipment attribute, the coupling intensity and comprehensive evaluation of equipment importance are confirmed by improved group analytic hierarchy process. Rationality and effectuality of the proposed method are validated through an example. Key

Comprehensive Review

Research on Evaluation of Contribution Rate of a New Intelligent Armoured Combat System to Army Weapon System-of-systems

CHEN Wen-ying， ZHANG Bing-zhi， SHI Li-chen， ZHAO Qing-song

2018, 39(9):  1841-1849.  doi:10.3969/j.issn.1000-1093.2018.09.022

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In allusion to the problem that contribution rate evaluation of weapon equipment system has highly complexity and great difficulty due to multitudinous relation factors, a research framework is proposed based on the systematic analysis of contribution rate conception. For the contribution rate evaluation of a new intelligent armoured combat system, an evaluation index system is established from the viewpoints of functional completeness, architecture optimization, operational capability enhancement and technological progress. The contribution rate evaluation of a new intelligent armoured combat system is systematically studied by using an evidential reasoning approach based on the belief rule base. The result shows that the contribution rate of weapon equipment system is a comprehensive characteristic parameter describing the position and function of weapon equipment system, its evaluation must be systematically studied from multiviewpoints and multilevels, and the evidential reasoning approach based on the belief rule base is an effective, scientific and practical method for solving the contribution rate evaluation of weapon equipment system. Key

Research Notes

Parameter Analysis and Optimization of Finite Frequency H_∞ Control with Time Delay for Active Suspension

ZHANG Jin-qiu, WANG Xing-ye, JIA Jin-feng, SUN Yi-quan, LI Xin

2018, 39(9):  1850-1857.  doi:10.3969/j.issn.1000-1093.2018.09.023

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A finite frequency H_∞ controller with input delay is designed based on the linear matrix inequality method. In the design of finite frequency H_∞ controller, the increase in ride comfort of vehicle and the reduction in car body acceleration are taken as the control target, and the suspension stroke being less than the maximum allowable travel, the wheel keeping well contacted with the ground, and the actuator output being less than the maximum output are taken as the three constraints of control. The influences of control parameters on solving result are analyzed. To solve the problems of that the optimal solution of controller can not be derived from the empirical parameter values, and the parameter values are not universal under different time delay conditions, an optimal design method based on genetic algorithm is proposed, and the performance of controller is analyzed through numeral simulation. The simulated results show that the new proposed finite frequency H_∞ controller optimized by the genetic algorithm can effectively reduce the influence of time delay on control and improve the riding comfort of vehicles in the frequency band of 4-8 Hz. The finite frequency H_∞ controller is obviously superior to the empirically designed controller and the controller without considering the input delay in the control effect. Key

A New Structure of Linear Rotating Accelerated Coilgun

HE Yong-hai, WANG Yu, TAN Cheng, LU Fa-long, JIANG Ming-yang, YAN Zhong-ming

2018, 39(9):  1858-1863.  doi:10.3969/j.issn.1000-1093.2018.09.024

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In order to realize the acceleration and rotation of the projectile by the coilgun, a new type of drive coil is proposed, and the projectile armature matching with it is designed. For the launching process of the coilgun, the acceleration force of the armature is theoretically analyzed from the point of electromagnetic field. The launching effects under different initial voltage levels are studied through the combination of simulating calculation and launching test verification, and the possible causes of its error are analyzed. The results show that the new electromagnetic coilgun can realize the linear and rotational accelerations of projectile, and the linear and rotation speeds of projectile increase with the increase in the initial voltage level. The exit index of projectile can be adjusted by changing the initial voltage. Key

Comb Jamming Mitigation in Frequency-hopping Spread Spectrum Communications via Block Sparse Bayesian Learning

ZHANG Yong-shun， ZHU Wei-gang， MENG Xiang-hang， JIA Xin， ZENG Chuang-zhan， WANG Man-xi

2018, 39(9):  1864-1872.  doi:10.3969/j.issn.1000-1093.2018.09.025

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Comb jamming is a common interference pattern in frequency-hopping spread spectrum (FHSS) communications. Comb jamming mitigation is a very important issue to ensure the effectiveness of FHSS communications. The existing comb jamming mitigation algorithms for FHSS communications are confined to the high sampling rate. In order to solve the problem above, the compressive sensing (CS) is applied to the comb jamming mitigation in FHSS communications. A comb jamming mitigation model based on block sparse Bayesian learning (BSBL) is established using the different features of FHSS signal and comb jamming in compressed domain and the block sparsity feature of comb jamming in frequency domain. A FHSS communications comb jamming mitigation algorithm based on BSBL_EM is designed using the expectation maximization (EM) algorithm. The algorithm uses the BSBL_EM to reconstruct the comb jamming from the compressed data, and then cancel the interference in time domain. Simulated results demonstrate that the proposed methods can effectively suppress the comb jamming in FHSS communications, and significantly outperform other conventional methods. The jamming mitigation performance is mainly affected by the variety of interference intensity, comb jamming bandwidth and compression rate. Under the condition of same interference intensity, the narrower the comb jamming bandwidth is and the greater the compression rate is, the better the jamming mitigation performance is. Key