Table of Content

29 January 2016, Volume 37 Issue 1

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Paper

Simulation Analysis on Jet Flow Field Structure Characteristic of Static Scattering Combustion Gasbag of Submunition

NING Hui-jun， HUANG Kai， WANG Jin-long， ZHANG Cheng, TAO Ru-yi, WANG Hao

2016, 37(1):  1-9.  doi:10.3969/j.issn.1000-1093.2016.01.001

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A three-dimensional dynamic model of the combustion gasbag rupture projector structure is established to research the rupture of gasbag and its influence on projectile motion during the test of the combustion gasbag. The gasbag rupture jet flow field is simulated by using computational fluid dynamics, and software Fluent the six degrees of freedom equation of rigid body motion is coupled with the fluid governing equation. The variation rule of the internal pressure of gasbag is obtained by comparing the jet flow structure characteristics of free jet and the gasbag rupture jet generated in the dispersal process of submunition. The gasbag rupture jet with different ruptured position at gasbag is simulated, the variation of the internal pressure of gasbag and its influence on projectile motion is obtained. The calculated results show that the existence of the projectile had a great effect on the jet space, and the gasbag rupture jet flow structure is very different from the free jet flow structure. When the gasbag is ruptured at the center position, it has the greatest impact on the internal pressure of gasbag; and when the gasbag is ruptured at the center or at the short side, it has the greatest impact on the attitude of projectile.

A Design Method of Cooling System Principle Scheme Based on Directed Graph

LUO Qing-guo， YIN Hong-tao， NING Xing-xing

2016, 37(1):  10-16.  doi:10.3969/j.issn.1000-1093.2016.01.002

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A new optimization design method for principle scheme based on directed graph is proposed for the design of principle scheme of cooling system in electric transmission armored vehicle. The simplified models of thermal parts, radiator and pump are established. Basic rules of using directed graph to represent the principle scheme of cooling system are put forward. A practical example is used to verify the proposed method, which indicates that, compared with the principle schemes of which all thermal parts are assembled in parallel and which all thermal parts are assembled in series, the fitness function value of the optimized scheme is reduced by 62.6% and 54.5%, respectively. This research has a certain reference value for the design of principle scheme of cooling system.

Experimental Research on Combustion System with Double ω Combustion Chamber for ZS1100M Diesel Engine

WEI Sheng-li, LU Hong-kun, LENG Xian-yin, LIANG Yu, CHEN Liang, WANG Fei-hu

2016, 37(1):  17-22.  doi:10.3969/j.issn.1000-1093.2016.01.003

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In order to improve the spatial distribution of injection spray and the mixture formation quality for diesel engines, a combustion system with double ω combustion chamber is proposed to strengthen the motion of airflow in the combustion chamber. The preliminary performance test of combustion system with double ω combustion chamber is made on ZS1100M diesel engine. The results show that the geometrical shape of double ω combustion chamber has a great influence on the fuel consumption and emission performance of combustion system for diesel engine. The fuel consumption and soot emission of 57-type combustion chamber are the lowest under the rated operating condition. Compared with the original combustion chamber, the fuel consumption and soot emission of 65-type double ω combustion chamber are reduced by 2.2% and 8.3%, respectively, at rated operating condition while the NO_x emission remains basically unchanged. 65-type combustion chamber with 2.6 mm nozzle height possesses the optimal fuel consumption and soot emission performance at the rated rotating speed. At the rotating speed of 1 500 r/min, the double ω combustion chamber with double-row nozzle holes shows better fuel consumption rate under the small and medium loads. The proper increment of the upper-row nozzle holes and a decrease in throat diameter could further reduce the fuel consumption rate.

A Study of Driving Force Optimal Control of Multi-wheel Independent Electric Drive Vehicle

YANG Gui-bing, LIAO Zi-li, MA Xiao-jun, LIU Chun-guang

2016, 37(1):  23-30.  doi:10.3969/j.issn.1000-1093.2016.01.004

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In order to improve the power performance of multi-wheel independent electric drive vehicle, a hierarchical control structure is established to realize the optimal control of the whole vehicle driving force. This kind of control structure includes an predistribution control of load on each axis, the acceleration slip regulation (ASR) and the redistribution based on state of vehicle. The ASR is the core layer which adopts a slip mode control method based on the road’s optimal slip rate, and an abnormal fault detector based on cumulative sum (CUSUM) statistical control is designed. The optimal estimation of slip rate can be realized based on μ-λ figure. The hierarchical control structure can be used to achive the optimal distribution of drive force between axis and driving motor based on the output control of single wheel’s optimal control. The control structure is proven by a real-time simulation in hardware in loop (HIL) in order to improve the vehicle’s performances, including climbing ability, directly accelerating ability, and trafficability.

Test and Analysis of Dynamic Response Characteristics of Pistol Shooter

YANG Yang, WANG Ya-ping, ZHANG Wei, XU Cheng

2016, 37(1):  31-36.  doi:10.3969/j.issn.1000-1093.2016.01.005

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The purpose of the study is to investigate the response characteristics of pistol shooter who stands to continuously shoot without support. A three-dimensional motion capture system and a plantar pressure test system are used to get the shooter-pistol motion trajectory and plantar pressure. The results show that the pistol motionis closely related with the foot force/pressure center position during the continuous shooting.A shooter should go through the passive and active responses when he fires in standing posture without support. A shooter takes 250 ms (SD=62.9 ms) to make an active response. Weak postural control occurrs with the increase in consecutive shots, which results in reduced gun control ability.The analysis results show that the testing systems can be used to analyze the response characteristics of shooter, provide a new way to study the discipline of human-pistol motion and develop the human-pistol dynamics model.

Research on the Algorithm for Firing Efficiency of Naval Gun Weapon System against Group Targets on Island

QIU Zhi-ming， CAO Yuan, GUO Yong

2016, 37(1):  37-41.  doi:10.3969/j.issn.1000-1093.2016.01.006

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Naval gun weapon system of navy formation has a special advantage when attacking the group targets on the island. The analytic formulae for mathematical expactation of damaged target number under the conditions of concentrated fire and uniform distribution fire are built based on the fire characteristics of weapon system. The mathematical expectation of the damage degree for the group targets can be got. The numerical calculation steps are presented through the parameter resolution. The proposed method has been used for the efficiency analysis of a naval gun. The calculated results are compared with the experimental data. The results show that the proprosed method is effective.

A Note on the Dynamic Spherical Cavity Expansion of Concrete with Shear Dilatancy

ZHANG Xin-xin, YAN Lei, WU Hai-jun, HUANG Feng-lei

2016, 37(1):  42-49.  doi:10.3969/j.issn.1000-1093.2016.01.007

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Considering the compression and dilatation of the concrete,a model of dynamic spherical cavity expansion is constructed, where the complete response of target is densification region-dilatation region-crack region-elastic region, and the dilatant-kinematic relation is used for the dilatation region. The expression of cavity stress and expansion speed is obtained with the theory above, and the depths of penetration in different conditions are calculated. The effects of the concrete strength and dilatation on penetration depth are analyzed. The results indicate that the proposed model is reasonable to predict the depth of penetration; the stress hardening parameter has a great influence on the depth of penetration, and the shear saturation should be considered with the increase in the projectile volecity; with the decrease in the densification parameter, the condition of the concrete turns into dilatation from compression, resulting in the increase in cavity stress and the decrease in depth of penetration.

PreparationCharacterization and Electrostatic Properties of GAP-coated Zirconium Composite Particles

JIANG Han-yu, ZHAO Feng-qi, HAO Hai-xia, QU Wen-gang, XU Si-yu, AN Ting, LI Meng

2016, 37(1):  50-55.  doi:10.3969/j.issn.1000-1093.2016.01.008

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Zirconium metal prepared as powder is of interest as an energetic material due to its good combustion performance, and high density, which affords the opportunity to use zirconium powders as fuel in solid propellants. Unfortunately, the application of current zirconium powders is limited due to its high electrostatic discharge sensitivity, making the zirconium powders more pyrophoric and less amenable to functionalization. Glycidyl azide polymer (GAP), a kind of energetic binder as coating material, is selected to improve the security, and coated on the surface of zirconium powder directly to obtain Zr/GAP composite particles with reduced electrostatic discharge sensitivity. The measured results show that 50% firing energy (E₅₀) of Zr/GAP is increased from 5.13 mJ to 24.91 mJ, meanwhile the good combustion performance and high density of Zr powder are also reserved. This work provides technology support for its application in high density propellant.

Influence of Alignment of Moving Base for INS on Acquisition Probability of Homing Radar for Ship-to-ship Missile

GAO Qing-wei, ZENG Jia-you, WU Fang, ZHANG Qian-yu

2016, 37(1):  56-63.  doi:10.3969/j.issn.1000-1093.2016.01.009

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The shipborne ship-to-ship missile with INS is an important attacking weapon in naval battle. Therefore，the rapid and accurate initial alignment of ship’s INS (SINS) on moving ship becomes one of the critical technologies for the shipborne anti-ship missiles. As the initial error of SINS, the alignment error is accumulating over time, which can make the missile dispersion and yaw error angles increase, resulting in the decrease in the acquisition probability of homing radar. Considering the effect of initial alignment error on auto-control terminal error, a calculation model of acquisition probability for ship-to-ship missile is established based on the model of target position error. The influence of initial error of a certain ship-to-ship missile on target acquisition probability is analyzed by setting the different conditions and parameters. The results show that the probability is decreased linearly with 4.2%~6.5% of static alignment.

Study of Flight Path Tracking and Control of an UAV in 3D Space

GUAN Jun, YI Wen-jun, CHANG Si-jiang, LIANG Zhen-dong, LYU Yi-pin

2016, 37(1):  64-70.  doi:10.3969/j.issn.1000-1093.2016.01.010

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A flight path tracking problem is studied for underactuated UAV in 3D space. The question of flight path tracking is transformed into way-point tracking by choosing a serious point on flight path. A mathematic model is established.The speed frame is alined to the desired frame so that position tracking is converted into attitude tracking. The guidance law is also deduced, and the theories of sliding variable structure and back-stepping are used to design the attitude controller and velocity controller. The direction of velocity vector is aligned to the position of a way-point by using the attitude controller. The speed of UAV is controlled by the velocity controller to make the UAV closing to a way-point. The guidance and control systems are simulated. The result shows that the designed controller is perfect in tracking and have a strong robustness.

Research on Control Strategy of Large Hydraulic Erecting System Based on Adaptive Fuzzy Sliding Mode

LI Liang, LI Feng, FENG Yong-bao, YAO Xiao-guang

2016, 37(1):  71-76.  doi:10.3969/j.issn.1000-1093.2016.01.011

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The large hydraulic erecting system has strong nonlinearities and uncertainties due to heavy external load, variable circumstance, oil leakage, oil viscousness and external disturbance. All of these lead to the degradation of control performance in position tracking control of erecting process. An adaptive fuzzy sliding mode controller is designed to overcome these problems. A fuzzy system is developed to approximate the equivalent control of the sliding mode controller, and an adaptive law is presented by Lyapunov stability analysis method. However, the adaptive parameters cannot be precisely confirmed. So the genetic algorithm is applied to optimize the adaptive parameters. Simulation results show that the proposed control method has good robustness and tracking performance to improve the stability of the erecting process.

Experimental Research on Fracture of Metal Case under Loading at High Strain Rate

REN Guo-wu, GUO Zhao-liang, TANG Tie-gang, SU Hong-mei, WEN Shang-jie, JIN Shan

2016, 37(1):  77-82.  doi:10.3969/j.issn.1000-1093.2016.01.012

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A new Dopple detection system (DPS) array and a high-speed framing camera are used to test the surface dynamics and local velocity profiles of the expansion, fracture propagation and rupture of TC4 case initiated by high explosive for the research on complex dynamic response of metal case at high-strain rate. The engineering strain at the moment of surface crack initiation and explosion product leakage is estimated through comparative analysis, and the surface crack mode and the influence of crack initiation on velocity profiles are observed. Furthermore, The fracture property of metal case is confirmed from the fracture morphologies of recovered fragments.

Node Selection and Source Localization of Four-node Wireless Acoustic Array in Wireless Sensor Network

ZHU Hai-yang， ZHANG He， MA Shao-jie， PAN Han

2016, 37(1):  83-90.  doi:10.3969/j.issn.1000-1093.2016.01.013

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Instead of using microphone array, each sensor node in the sensor network uses only a single microphone as its sensing device in low-cost and miniature wireless acoustic sensor network (WASN). According to the energy decay model and geometric positioning mechanism， an external acoustic source localization estimation method with four-node wireless microphone array is presented for the application in randomly deployed WASN. Major error sources, such as sound attenuation coefficient and array shape, of the localization method are analyzed, and Y-type array model is selected as sensing model. The location error is less than 1m when the angle between the central axis of Y-type array and the target is 60°～100°. A node selection algorithm is proposed, and the experiment of source localization is done. The experimental result shows that Y-type wireless acoustic array can warn about target at 50m away from the wireless sensor network（WSN）.

Application of Sample Selection and PDS-PLS Algorithms in Near Infrared Spectra Analysis Model Transfer

WANG Ju-xiang, MENG Fan-lei， LIU Lin-mi， CUI Wei-cheng

2016, 37(1):  91-96.  doi:10.3969/j.issn.1000-1093.2016.01.014

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A transfer method of near infrared (NIR) spectra analysis model is studied in order to enable one instrument (reference instrument) and the other one (target instrument) to share the model. The transfer set samples are selected with Mahalanobis distances by taking an analysis model of mixed-amine fuel for example, and the algorithm of piecewise direct standardization (PDS) combined partial least squares (PLS) is used to set the spectral correction matrix between the reference and target instruments. The number of transfer samples, the number of prime factors of PLS regression and the window width of PDS are confirmed based on the average of root mean square (ARMS) of corrected spectra of transfer samples. The corrected rate of spectra of transfer samples reachs 96.5% with transfer sample number of 12 and prime factor number of 1 and window width of 39. Standard deviation of prediction set (SEP) of every analysis item on target instrument is near SEP on reference instrument after the analysis model of mixed-amine is transferred, the transferred model can predicate triethylamine content, xylidine content, water content and density accurately. The results indicate that the sample selection based on Mahalanobis distances and PDS-PLS algorithms can deduct the difference of NIR spectra among instruments and improve the analytical accuracy of NIR model.

Improved Genetic Algorithm for Solving Firepower Distribution

DONG Chao-yang， LU Yao， WANG Qing

2016, 37(1):  97-102.  doi:10.3969/j.issn.1000-1093.2016.01.015

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An improved genetic algorithm for solving firepower distribution is proposed. The fitness function is constructed based on relative value of objective function. Compared with the conventional finitude construction method, this measure can incarnate the differences among the chromosomes more significantly and the fine chromosomes are selected more easily, thus improving the convergence precision of algorithm. The heuristic genetic operator based on the similarity of father chromosomes is used to optimize the genetic operation and do crossover or mutation to the father chromosomes with agility and pertinence. It can prevent the local optimization and guarantee the optimization speed of population. The contrast results of simulation examples show that the improved algorithm have more efficient search ability.

Research on 3D Dynamic Imaging Algorithm for Digital Camouflage

WU Guo-jing, LYU Xu-liang，XU Wei-dong, LI Ling, WENG Xiao-di

2016, 37(1):  103-108.  doi:10.3969/j.issn.1000-1093.2016.01.016

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The current digital camouflage is not able to withstand the future high-tech reconnaissance and monitoring due to its planarity and inalterability. To address the issue， a 3D dynamic imaging algorithm based on lenticular raster is proposed. The proposed algorithm fully takes the biological characteristics of human binocular stereo imaging and the optical characteristics of splitting light and imaging of lenticular raster into account to describe the feasibility of 3D dynamic digital camouflage. On this basis, the parallax design principle of 3D dynamic imaging for digital camouflage is deduced, and the multiple sequence diagrams are generated according to depth information of background. The comb function is used to sample and synthesize the sequence diagrams. The resultant raster image could be mounted on the back of a grating plate to achieve 3D dynamic imaging. The simulation results show that the proposed algorithm can be used for the 3D dynamic imaging of digital camouflage.

Investigation of Capturing Technique for Fatigue Crack of Plasma Sprayed Fe-based Coating

PIAO Zhong-yu， ZHAO meng-meng， XU Bin-shi, WANG Hai-dou， WEN Dong-hui

2016, 37(1):  109-113.  doi:10.3969/j.issn.1000-1093.2016.01.017

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Fe-based coatings are deposited by plasma spraying technique. The fatigue wear experiments of the coatings are on-line monitored to capture the dynamic information of the cracks by using acoustic emission (AE) technique. The typical signal model is summarized. The micro-damages on the coating surface are characterized by oil whiting test. The micro-damages on the coating surface are analyzed by FIB-SEM, and its failure mechanism is investigated. Results show that the AE signal model during the fatigue wear process is divided into 3 stages, namely run-in period, stable period, and mutation period. Penetrating test technique is introduced to confirm the micro-damages on the coating surface. The reliability of AE monitoring can also be proved. The results show that the fractures in the coating can be accurately captured by AE signals. The micro-defects are considered to be the origins of coating failure based on the results of FIB-SEM analysis.

Vehicle Equipment Support Transport Net Optimization Model Based on Monte Carlo Simulation and Genetic Algorithm

CHEN Chun-liang, QI Ou, WEI Zhao-lei, LIU Yan

2016, 37(1):  114-121.  doi:10.3969/j.issn.1000-1093.2016.01.018

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The vehicle equipment support transport net is the key segment that impacts the mission completion of the military operation other than war. The tranditional method may result in the unstable results in its application in the optimization of vehicle equipment support transport net are obtained because of the poor ability of to describe the random and discontinuous support needs. An optimization model of vehicle equipment transport net is proposed based on Monte Carlo simulation and genetic algorithm. The boundary condition, support resource scheduling optimization function and support resource restraint condition are set according to the support feature of military operation other than war. An optimization model of vehicle equipment transport net is constructed. Finally, the efficiency of the proposed model is verified by residual analysis.

Optimization of Carried Spare Parts Based on Monte Carlo Simulation and Parallel Particle Swarm Optimization Algorithm

ZHANG Yong-qiang, XU Zong-chang, SUN Han-bing, HU Chun-yang

2016, 37(1):  122-130.  doi:10.3969/j.issn.1000-1093.2016.01.019

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In order to enhance the veracity of model and the accuracy of solution for carried spare parts scheme, several improvements are raised under the background of naval fleet. An improved model is established, which is based on multi-constraints including carrying capacity, spare parts cost, availability of equipment, and serviceability rate of the same type equipment. Particle swarm optimization(PSO) is used to optimize the spare parts scheme, and Monte Carlo simulation is used to calculate its performance. PSO is concurrently computed on the designed gloud platform, which could improve global optimization ability by hardware parallel computation, and the ordinary particles in PSO are transformed to the quantum particles in special conditions, which could avoid PSO trapping in local optimum. The example shows that these improvements are feasible and effective.

A Comprehensive Reliability Allocation Method for Numerical-controlled Lathes Based on Copula Function

YANG Zhou, ZHU Yun-peng, ZHANG Yi-min, REN Hong-rui

2016, 37(1):  131-140.  doi:10.3969/j.issn.1000-1093.2016.01.020

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An allocation method which considers fault correlation is proposed for the reliability allocation of series systems based on the non-linear transform functions of failure mode and effects analysis (FMEA). In consideration of the multiple factors that affect the reliability allocation, an reliability allocation matrix is established by employing the significance factors. The non-linear transform laws of failure severity and failure frequency are established to address the limitation of FMEA. A coefficient matrix of fault correlation is established based on Gumbel Copula function and Kendall correlation coefficients, and the correlated failure severities of subsystems are calculated. The equation of calculating the reliability of series system is derived based on Copula function. This equation is employed to guide the reliability allocation. Finally, the characteristics of the method are analyzed by taking a spindle system of a computerized numerical controlled (CNC) lathe for example. The allocation results are compared, which consideres dependent and independentfaults of subsystems. The result shows that the the allocation method with fault correlation can be used to provide the lower reliability allocation of subsystems, thus reducing the processing and maintenance costs.

Fluid-structure Interaction Modelling of Airdrop Cargo Platform Swinging

TANG Jian-hua，QIAN Lin-fang，XU Ya-dong

2016, 37(1):  141-148.  doi:10.3969/j.issn.1000-1093.2016.01.021

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A platform-sling model is established to study the dynamic response of airdrop platform. An uniform equivalent point Newton-Rapshon iteration method is presented. In order to study the unsteady fluid behavior, the time domain is discretized, and an ALE base finite volume method is used to solve the NS equations. The aero-force is obtained and imposed on the platform. The equivalent point method is validated through commercial software RECURDYN. The results show that the equivalent point method can well represent the slack-taut cases of the sling system. It can also be found that the laminar flow model is used to describe the acting force of fluid on plate well at low Reynolds number. Finally, the comparisons are made between the steady and unsteady FSI models. The time history of unsteady fluid force displays severe oscillation while the steady fluid force varies evenly.

Research on Dynamic Characteristics of Aerostatic Thrust Bearings Based on Perturbation Method

LU Zhi-wei, MA Fang-jie, LIU Bo, ZHANG Jun-an

2016, 37(1):  150-155.  doi:10.3969/j.issn.1000-1093.2016.01.022

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An aerostatic thrust bearing with pressure-equalizing groove with variable sectional area is designed to research the dynamic characteristics of aerostatic thrust bearing. Based on the mechanical vibration model of gas bearings, the dynamic control equations of gas bearings is established by using perturbation method, and the dynamic control equations are sovled to obtain the dynamic stiffness and damping of gas bearings by the finite difference method. The results show that the dynamic and static stiffness values of aerostatic thrust bearings are equal when the vibration is small, and the dynamic and static stiffnesses of gas bearings reach the optimum value when the gas film thickness is about 5.5 μm; the dynamic damping decreases nonlinearly with the increase in gas film thickness at the same air supply pressure, and the gas film thickness greatly affects the dynamic damping coefficients of air bearings.

Modified Modal Strain Energy Method for Analysis of Modal Loss Factors of Viscoelastic Structure

SUN Bao, SUN Da-gang, LI Zhan-long, YAN Bi-juan, WANG Jun

2016, 37(1):  155-164.  doi:10.3969/j.issn.1000-1093.2016.01.023

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In order to study the damping characteristics of viscoelastic structures, a calculation model of the viscoelastic structure structure loss factor is established using the traditional deformation energy method, and the optimized analysis is carried out on the relevant damping parameters. A modified modal strain method is proposed by analyzing the principles and correlation of the traditional modal strain method and several improved methods. In the proposed modified method, the modifying factor of the viscoelastic constrained damping structure changes with the amplitude of modal loss factor. The prototype system with four parameters is selected as the basis, and the calculated errors of the proposed modified modal strain method and other methods are analyzed, respectively. The results show that calculated error of the proposed method is the least. Two examples are selected to calculate the modal loss factor and natural frequency of the viscoelastic composite structure. The calculated results of the modified modal strain energy method, the deformation energy method, the traditional modal strain energy method and the finite element method show that the modified modal strain energy method can meet the requirements of engineering design, and the calculation error is the least. The modified modal strain energy method can provide a theoretical reference for the research on the damping characteristics of viscoelastic structures and structural design.

Comprehensive Review

A Comparative Research on Optical Principles and Methods of One-point-to-multi-point Space Laser Communication

ZHANG Ya-lin, AN Yan, JIANG Hui-lin, WANG Chao, JIANG Lun, HU Yuan,

2016, 37(1):  165-171.  doi:10.3969/j.issn.1000-1093.2016.01.024

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One-point-to-multi-point laser communication is the key to establish an integrated space-ground information network system, and also is the necessary prerequisite of realizing the inter-satellite communication link. The optical principles and methods of one-point-to-multi-point laser communication are comparied and researched. The fields of view and energy efficiencies of three-concentric sphere structure and rotating parabolic structure are analyzed. The result shows that the horizontal and vertical fields of view of the three-concentric sphere structure are 120°, and the horizontal and vertical fields of view of the rotating parabolic structure are 360° and 100°, respectively. With the increase in the field of view, the energy efficiency of three-concentric sphere structure decreases rapidly. However, the energy efficiency of the rotating parabolic structure is more stable than that of the three-concentric sphere structure in the range of 80°.

Development of Multi-joint Exoskeleton-assisted Robot and Its Key Technology Analysis: an Overview

SONG Qiu-zhi， WANG Xiao-guang， WANG Xin， WANG Yang

2016, 37(1):  172-185.  doi:10.3969/j.issn.1000-1093.2016.01.025

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The exoskeleton-assisted robot has broken through the limit of that the traditional vehicle is influenced by the terrain conditions easily, show the wide application prospect in the military and civilian fields, and became a research hotspot. The domestic and international developing status of the multi-joint exoskeleton-assisted robots is reviewed in terms of load exoskeletons and rehabilitation exoskeletons. The key technologies of the multi-joint exoskeleton-assisted robots are also summarized and analyzed in the areas of human-machine matching, driving mode, gait detection, control strategy of human-machine cooperation movement, and power-assisted evaluation. The future research direction and focus of the multi-joint exoskeleton-assisted robots are suggested.

Research Notes

Study of Digital Pattern Generation Method Based on Fractal Brown Model

CAI Yun-xiang， XUE Shi-qiang， ZHOU Zhi-yong， HUANG Yun

2016, 37(1):  186-192.  doi:10.3969/j.issn.1000-1093.2016.01.026

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Painting camouflage is an important camouflage technique. Digital camouflage is an effective means against high-resolution imaging reconnaissance. How to achieve the effectiveness，precision and intelligence of camouflage design technology is always a reseach focus. The texture features of background image are extracted based on FBM fractal dimension estimation method, and the dominant color features of background image are extracted based on pyramid structure fuzzy C-means cluster (FCM) clustering algorithm. The digital camouflage patterns conforming to the characteristics of background are generated based on the improved diamond-square algorithm. The simulation results show that the proposed algorithm is used to achieve the preferable results of pattern generation in desert, jungle, forest land backgrounds.