Table of Content

30 November 2017, Volume 38 Issue 11

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Contents

2017, 38(11):  0. 

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Paper

Resistance Model of Rigid Projectile Penetrating into Reinforced Concrete Target

ZHANG Shuang, WU Hai-jun, HUANG Feng-lei

2017, 38(11):  2081-2092.  doi:10.3969/j.issn.1000-1093.2017.11.001

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Establishing the penetration resistance model of rigid projectile is the primary problem to be solved when the penetration of reinforced concrete target is theoretically modeled. Based on the cavity expansion theory of reinforced concrete^\[3\] and the crater depth model^\[4\], a dynamic response model of reinforcing steel bar under impact load of projectile is proposed by analyzing the movement relationship between projectile and reinforcing steel bar, as well as the force and failure of reinforcing steel bar. On the basis of impact force acting on projectile by a single reinforcing steel bar, a relatively complete resistance model of rigid projectile normally penetrating into reinforced concrete target is established by considering the situations that the projectiles impact different typical positions and simultaneously interact with two reinforced layers. Combining with the experimental data in Ref. \[13-14,18-20\], the proposed theoretical model is verified, and the influences of relevant parameters are analyzed. The results show that the proposed model can reasonably calculate the penetration process and reflect the details of the interaction between projectile and steel bar. Key

Research on Double Margin Coefficient Design Method of Slapper Detonator

GUO Fei, WANG Yao, LYU Jun-jun, FU Qiu-bo, HUANG Hui, SHEN Rui-qi

2017, 38(11):  2093-2097.  doi:10.3969/j.issn.1000-1093.2017.11.002

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In order to improve the design reliability of slapper detonator, the margin coefficients were calculated using input stimulus and flyer velocity as the characteristic parameters based on the action principle of the slapper detonator. It is shown that the design margin characterized by the input stimulus cannot fully reflect the reliability state of the product. The input stimulus and the output margin coefficient characterized by the flyer velocity can be used to truly reflect the quality characteristic of the product．A double margin design method on the basis of inputting stimulus and flyer velocity is presented, which can improve scientific margin coefficient in the design process of slapper detonator. Key

Mass Preparation of Ultrafine Sphere-like AP Particles by Jet Milling and Their Characterization

LI Guang-chao, LIANG Zhen-zong, LIANG Li, GUO Xiao-de

2017, 38(11):  2098-2104.  doi:10.3969/j.issn.1000-1093.2017.11.003

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Ultrafine sphere-like ammonium perchlorate (AP) particles are prepared by using an improved jet mill. The morphologies, particle size distributions, sample compositions and molecular structures of raw, ultrafine non-spherical and sphere-like APs are characterized by using scanning electron microscope, micron laser particle size analyzer, Fourier transform infrared spectrometer and X-ray diffractomer. The thermal decomposition, impact sensitivity and friction sensitivity, bulk density, hygroscopicity and caking of ultrafine sphere-like and non-spherical AP particles with same size are measured. The results indicate that the ultrafine AP particles prepared by jet milling method are basically sphere-like with particle size of 2 μm. The AP particles also have the characteristics of uniform particle size, smooth surface without defect, good dispersion and high purity. Compared with non- spherical AP particles with the same size, the thermal stability of sphere-like AP particles is improved slightly, and their impact and friction sensitivities are decreased by 37.6% and 26.7%, respectively; the apparent bulk density is increased by 10.7%, the tap density is increased by 24%；hygroscopicity and caking are effectively improved. Key

Experimental Investigation about Fast Burning of TNT-RDX-Al Explosive with Shell at Fast Heating Rate

ZHAO Sheng-wei, DING Yang, WANG Chang-li, WU Yu-jiao

2017, 38(11):  2105-2110.  doi:10.3969/j.issn.1000-1093.2017.11.004

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The fast burning of cast-loaded TNT/RDX/Al explosive with metal shell at fast thermal effect was experimented to obtain its thermal response characteristics and ascertain the feasibility of fiber-optic probe to measure the propagation velocity of chemical reaction front. A fast heating equipment is used to fast heat a steel tube, which is 400 mm in length, filled with cast-loaded TNT/RDX/Al explosve, and the propagation velocity and path of chemical reaction front are measured by using the fiber-optic probe. The result shows that the propagation velocity of chemical reaction front is 200~1 000 m/s when the open end of steel tube is covered with an end cap. Its propagation velocity is 200~500 m/s when the open end is not covered with the end cap. The detonation dosen't happen and the state of chemical reaction is fast burning. So the thermal response state of cast-loaded TNT/RDX/Al explosives at fast heating rate is rapid burning. The fiber-optic probe can be used to obtain the propagation velocity of chemical reaction front at less than 1 000 m/s. Key

A High Speed Test and Analysis Method for Information Field Parameters of Beam Riding Guidance

SUN Ce， HAO Qun， YAN Zhen-gang， CAO Jie， LI Jie

2017, 38(11):  2111-2116.  doi:10.3969/j.issn.1000-1093.2017.11.005

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Laser beam riding guidance is an important guidance mode. The accuracy of guidance is affected directly by the quality of laser information field. A testing method based on the spot images of information field is proposed to evaluate the quality of laser information field fastly and intuitively. The proposed method allows the fast setup of a test system in inside and outside fields, and calibrates the system. Based on the principle of transient diffuse reflectance imaging under low illumination, the stripe-shaped spot images are quickly obtained by using low-light-high-speed imaging of laser beam. The rapid image processing technology is used to calculate the spot size, center location, stripe brightness for evaluating the parameters, including optical axis stability and energy uniformity of information field. Experimental results show that the test method can be used to obtain the stripe-shaped spot images of laser information field, and detect the performance of the guidance device rapidly with test accuracy of 1.8 mm and processing time of 0.35 s. Key

Structural Response of Free-free Beam under Oblique Reverse Ballistic Impact

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

2017, 38(11):  2117-2125.  doi:10.3969/j.issn.1000-1093.2017.11.006

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Reverse ballistic impact test has been widely used to research the materials and structural dynamic response, in which the measuring devices can be installed on the free-free beam to obtain the more accurate measured results. The 20° reverse ballistic oblique impact tests of free-free beam are carried out, and the digital image correlation (DIC) technique is used to measure the real-time dynamic response. The failure criterion is introduced and the simulated results are considered to solve the dynamic responses of free-free beam under axial and transverse impact loading. The results show that the calcula-ted bending shape agrees well with the experimental result, and is better than that in Ref［4］. The reverse ballistics is equivalent to the forward ballistics for the reverse ballistic mass ratio m_γ≥10. The proposed method can also be used for solving the dynamic response of projectile during penetration. Key

Perforation Characteristics of Energetic Material Shield Induced by Hypervelocity Impact of Spherical Projectile

WU Qiang， ZHANG Qing-ming, LONG Ren-rong, GONG Zi-zheng

2017, 38(11):  2126-2133.  doi:10.3969/j.issn.1000-1093.2017.11.007

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The metastable energetic materials were prepared for the space debris shield. Hypervelocity impact tests of PTFE/Al energetic material shield under the conditions of different areal densities, projectile diameters, and impact velocities were conducted by using two-stage light gas gun, and the high speed photographs and the signals from optical pyrometer during impacting were obtained. The analysis results show that the shock initiation of PTFE/Al energetic material shield occurs in the instant of hypervelocity impact, and the perforation process can be divided into three stages: shock detonation, fracture and deflagration, and zero reaction and crushing. A dimensionless empirical expression for perforation diameter of PTFE/Al shield is established based on the experimental results of hypervelocity impact. The effect of ambient temperature on the perforation characteristics of energetic material shield is investigated. Key

Research on Blanking Shift-frequency-multi-carrier Jamming against Pulse-compression Radar Based on OS-CFAR

LIU Xiang， LI Dong-sheng, HU Rui

2017, 38(11):  2134-2142.  doi:10.3969/j.issn.1000-1093.2017.11.008

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A multi-false-target jamming method is proposed for the linear frequency modulation pulse compression radar with order-statistic(OS) CFAR detector. According to the principle of OS-CFAR detector, a multi-carrier and blanking shift-frequency shifting Jamming method is proposed. Some key parameters are set by using the characteristics of OS-CFAR. As a result, multiple false targets with the quantity, amplitude and space distribution which can be controlled are produced around the true target. The simulated results show that the jamming method can be used to reduce the detection probability of target effectively. Key

A Cluster Head Coordination-based Time-division Multiple Access Routing Protocol

TANG Yao, LI Bo, YAN Zhong-jiang, YANG Mao, ZUO Xiao-ya

2017, 38(11):  2143-2150.  doi:10.3969/j.issn.1000-1093.2017.11.009

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The broadcasting way for exchange of routing packets in wireless mobile network easily causes the packets lossing. A time division multiple access routing protocol (TDRP) based on cluster head coordination is proposed. The TDRP combines multiple access protocol and routing protocol. The transmission efficiency is improved, and the transmission delay is reduced by ensuring the reliable transmission of routing/control information. A multiple access protocol based on super frame structure is proposed. Under the manage span of the super frame, it uses TDMA for routing information exchange; and under the data span of the super frame, it uses CSMA/CA for data exchange. In order to control the media resources occupied by routing information, it designs the nodes login and logout processes so that the cluster head only distributes time slots for the nodes which have already joined the network successfully. Through the interaction of two-hop routing information between adjacent nodes, all nodes can get the three-hop routing table steadily, and the cluster head can get the complete routing table by the interaction of manage frames. The simulated results show that, compared with the existing AODV/OLSR routing protocol, the proposed protocol can reduce the average delay by 23% and improve the transmission efficiency by 30% under the mode of mobile group. Key

Research on Reliable Transmission Mechanism in Wireless Multi-hop Networks

JIANG Yu-jia， LI Xu， SHAO Xiao-tao，SUN Chen-hua, LI Guo-yan

2017, 38(11):  2151-2158.  doi:10.3969/j.issn.1000-1093.2017.11.010

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The transmissions of information in wireless multi-hop network with multiple relay nodes may easily cause inter- and intra-path interference and bit error accumulation. The reliability-guaranteed mechanism for multi-hop data transmission has been the keystone of research. In the light of the lack of recent research on the performance of reliability mechanism, in which mechanism parameters, business parameters and channel parameters are overall considered, the models of packet delivery ratio and overhead are established, and the influences of basic parameters on the performance of three multi-hop reliability mechanisms, including redundant transmission, retransmission and network coding, are analyzed. The applicable parameters and environment of network coding mechanism are modeled, simulated and analyzed. According to the wireless multi-hop network channel environment, the mechanism parameters of three reliability mechanisms are optimized, and their performances in different environments are compared. Simulated results show that the business parameters have greater impact on the network coding mechanism, and the network coding mechanism can achieve better performance in the case of large traffic. The mechanism parameters have the most significant impact on protocol performance. The target delivery rate performance with smaller overhead can be achieved by optimizing the mechanism parameters according to the channel parameters. Network coding, hybrid automatic repeat request and forward error correction coding schemes have better performances at lower, middle and higher bit error rates. Key

Weak Target Detection of DRM-based Passive Bistatic Radar

ZHAO Zhi-xin， ZHU Si-hang， HONG Sheng， ZHOU Xin-hua， WANG Yu-hao

2017, 38(11):  2159-2165.  doi:10.3969/j.issn.1000-1093.2017.11.011

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Passive radar is confronted with serious multipath clutter problem. Therefore, it is necessary to suppress the direct wave and multipath clutter, and improve the signal-to-noise ratio(SNR) and signal-to-clutter ratio (SCR) of target as much as possible. To solve this problem, a space-time domain combination adaptive technology is proposed based on the establishment of spatial, temporal and carrier-domain signal model for passive radar. In the technology, the spatial domain adaptive beamforming is used to get nulling in the direction of strong multipath clutter. And then a transversal filter is designed to eliminate weak clutter. The proposed space-time domain combination adaptive technology is used to process the simulated and measured data by taking DRM digital AM broadcast based passive bistatic radar for example. And it is proved that the proposed technology is practical, which can overcome the shortcomings of insufficient array degree of freedom and the insufficient clutter nulling depth due to low clutter noise rate in the spatial adaptive beamforming method. Key

An Adaptive Grid-based Clustering Algorithm for Noncooperative Targets

LI Da-peng， LIANG Wei

2017, 38(11):  2166-2175.  doi:10.3969/j.issn.1000-1093.2017.11.012

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The detection equipment of weapon systems is usually used to detect the noncooperative targets, causing the distribution patterns of observed samples to be unpredictable in feature spaces. The irregular cluster shapes, diversified cluster densities and noise bring great challenges to clustering algorithms. A novel adaptive grid-based clustering algorithm, which consists of a k-nearest neighbor method-based gridding method with spatial resolution adaptability, and an adaptive watershed transform-based method for cluster detection and segmentation in the gridded space are presented. The proposed algorithm could process the clusters with noises and significantly diverse densities, meanwhile keeps the advantages of gird-based clustering, including robustness for cluster shape and no need for cluster number as priori parameter. The effectiveness of the algorithm is tested with simulation and artificial datasets. Key

Research on Multi-body Aerodynamic Interference During Torpedo-rocket Separation

BAI Zhi-ning, CAI Wei-jun, ZHOU Jing-jun, WANG Ming-zhou

2017, 38(11):  2176-2183.  doi:10.3969/j.issn.1000-1093.2017.11.013

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The torpedo-rocket separation technology is one of the key technologies for the rocket-assisted torpedo. Research on multi-body aerodynamic interference is fundamental for analysis of torpedo-rocket separation. The multi-body aerodynamic interference is analyzed based on CFD method and wind tunnel tests. The research results show that the high pressure region appears between the forebody and afterbody of torpedo due to the inrush and retardation of airflow once the separating shells stretch, which is beneficial for torpedo-rocket separation. The effect of high pressure region is enhanced with the increase in the open angles of shells, and is weakened with the increase in the space between forebody and afterbody. Thus it's important to optimize the space to improve the safety of torpedo-rocket separation. The separating shells have the effects of converging, extruding and shielding on airflow, which should be taken into consideration in the design of separation scheme seriously. The sideslip angle may cause the stretching asynchronism of the separating shells . For the open angle of 20°, the sideslip angle of 1° results in 11% of difference between the yaw moments of two separating bodies. Key

Research on the Gas Aftereffect and Its Influence on Launch Tube Cover During Underwater Vertical Launching

QI Xiao-bin, WANG Rui, YUAN Xu-long, CAO Zhong-chen, LIU Chuan-long

2017, 38(11):  2184-2189.  doi:10.3969/j.issn.1000-1093.2017.11.014

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When a submarine launched missile is ejected from the launch tube with a gas-steam ejection system, the gas in the launch tube is overflowing under the action of residual pressure in launch tube, and then interacts with seawater to generate the bubbles at the outlet of launch tube. The periodic fluctuation of gas bubble enables the cover to move, which causes the safety issue of the launch tube cover system. Base on CFD software Fluent, dynamic mesh method and Mixture model are used to simulate the evolution process of gas bubble and its effect on the launch tube cover system with flexible-support. The movement law and load characteristics of the launch tube cover are obtained by studying the periodic expansion and contraction process of the bubble at the outlet of launch tube. The simulated result shows that the simulated data agrees with the experimental data, which verifies the validity of the proposed method. Key

Preparation and Performance Measurement of High Performance Underwater Carbon Fiber Electric Field Electrode

SHEN Zhen, SONG Yu-su, WANG Yue-ming

2017, 38(11):  2190-2197.  doi:10.3969/j.issn.1000-1093.2017.11.015

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A novel underwater electric field electrode is prepared with T300 carbon fiber heat-treated at 445 ℃, 465 ℃and 485 ℃. The surface chemical state, electrochemical performance and detection performance of electric field electrode in NaCl solution are measured using X-ray photoelectron spectroscopy (XPS), electrochemical workstation and self-made noise measurement system. The impact of heat treatment on surface group content , cyclic voltammetry (CV) characteristics, exchange current density, response performance and electrode settling time is discussed. The detection mechanism of underwater carbon fiber detection electrode is analyzed. The group CO and COOR content of carbon fiber electrode increase as the heat treatment temperature increases; the heat treatment reduces the capacitance effect of electrode, increases its exchange current density, and improve its linear performance and settling speed. Key

Switching Strategy of Dynamic Sliding Mode Control Based on Multiple Identification Model Set for Unmanned Semi-submersible Vehicle

ZHOU Huan-yin , LIU Ya-ping, HU Zhi-qiang, LIU Kai-zhou， YI Rui-wen

2017, 38(11):  2198-2206.  doi:10.3969/j.issn.1000-1093.2017.11.016

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The control parameters can not be provided for the model-based control algorithm, which leads to the undesirable control performances of the system since the depth motion model parameters regarding the unmanned semi-submersible vehicles (USVs ) BQ-01 are unknown. For this purpose, a multi-identification model-based dynamic sliding mode control algorithm is presented for the investigation of system's control problem on the desired depth. In the proposed algorithm, the average-fitting-error method is used to reduce the excessive redundant model parameters, and thus the optimum model parameters is provided for the control algorithm by switching methods. And the state feedback method is used to bring about the chattering exponential decay of sliding mode controller so as to reduce the settling time. The experimental results of lake trials demonstrates that the proposed algorithm could offer the best model parameters for sliding mode control, and the dynamic sliding mode control with multi-identification models is capable of ensuring BQ-01 system to achieve the ideal control performance. Key

Path Tracking Control of Underactuated Autonomous Underwater Vehicles on Horizontal Plane within Input Saturation Limit

JIANG Meng-jie， LI Jia-wang， LYU Yan-fang， ZHOU Jia-wei， HUANG Han-tao

2017, 38(11):  2207-2213.  doi:10.3969/j.issn.1000-1093.2017.11.017

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A saturation controller is designed for the path tracking control of underactuated autonomous underwater vehicles (AUVs) on the horizontal plane within input saturation limitation. A first-order observer is designed to estimate the tracking errors to avoid complicating the controller expressions due to the direct derivation of tracking errors. An improved error dynamic model is derived. A saturated dynamic control strategy for the actual inputs is proposed by utilizing smooth bounded functions as the estimations of the saturated inputs and introducing a Nussbaum-type even function. The stability analysis via the Lyapunov’s theory shows that the proposed controller can achieve the tracking of arbitrary smooth paths of AUVs on horizontal plane within input saturation limit, and the tracking errors are globally ultimately uniformly bounded. Some simulated results are presented to illustrate the effectiveness and robustness of the proposed controller. Key

An Evaluation Method for Fusion Feature of Digital Pattern Painting Based on Super-efficiency DEA Model

FENG Hai-chao， ZHAO Zhi-yong， ZHANG Jin-yuan， PAN Guo-qiang

2017, 38(11):  2214-2219.  doi:10.3969/j.issn.1000-1093.2017.11.018

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To evaluate the fusion feature of various digital pattern painting in different backgrounds for the camouflage painting of moving target, the optical images are analyzed, the hue-saturation-value (HSV) model is used, and the image features about color, texture, shape, entropy and complexity are extracted from digital pattern painting and background images. On the basis of super-efficient data envelopment analysis (DEA) model, the efficiency values of one-to-one fusion of digital pattern painting and background images are calculated by taking the differences among the above features in digital pattern painting and background images as the inputs of decision-making unit (DMU). And the reciprocal efficiency values are used as the inputs of new DMU unit, and the efficiency values of fusion of digital pattern painting and background are calculated for the evaluation of comprehensive adaptability of digital pattern painting to background. The efficiency values are checked using the saliency index of image, and two digital pattern painting with maximum and minimum efficiency values are used to camouflage the background. The result shows that the former has lower saliency and better integration in background. Key

Research on Annealing Behaviors of Al₂O₃-Dispersion Strengthened Copper

ZHANG Xue-hui， XIE Chen-zhen, LI Xiao-xian， LIU Wei-jiang， YANG Kai， JIANG Miao， ZHU Sheng-jian

2017, 38(11):  2220-2225.  doi:10.3969/j.issn.1000-1093.2017.11.019

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Cu-1.12wt%Al₂O₃ alloy is fabricated by in-situ reactive synthetic technology, and its annealing behaviors are studied by means of mechanical property measurement, fracture morphology observation and microstructure representation, respectively. The results show that the Rockwell hardness and strength of Cu-1.12wt%Al₂O₃ alloy with cold drawing deformation of 50% slightly decrease with the increase in annealing temperature, and its toughness is also improved. The fracture mechanism of the alloy is a typical ductile fracture, the size and depth of dimple increase with the increase in annealing temperature, and many tiny alumina particles are bestrewn inside dimple. The dislocation density of annealed alloy is lower than that of cold-drawn alloy. The alloy microstructure is mainly composed of deformation dislocation cells and dislocation walls at intermediate annealing temperature (873 K). After high temperature annealing (1 223 K), the subgrain structure is formed, and the merging, growth and development of subgrains can be found to be a process of original recrystallization. As a result of the dislocation of fine alumina particles and grain boundary motion, no obvious recrystallized grains exist in the matrix. The Cu-1.12 wt%Al₂O₃ alloy has a high softening resistance at elevated temperature. Key

Dynamic Compensation of Piezoresistive Pressure Sensors Based on Fireworks Algorithm

WANG Xiao, HAN Tai-lin, ZHANG En-kui, ZHANG Yong-li, LIU Xuan, GONG Yu-lin

2017, 38(11):  2226-2233.  doi:10.3969/j.issn.1000-1093.2017.11.020

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In the process of shock wave testing, the test signal is distorted by the limited bandwidth and low resonant frequency of pressure sensor. In order to solve this problem, a pressure sensor dynamic compensation method which is based on fireworks algorithm is presented. And the fitness function for the dynamic compensation is improved to increase the dynamic performance. The transfer function of dynamic compensation of pressure sensor is obtained from the test data of shock tube. The rise time of step pressure signal can be improved to 15.0 μs, and the overshoot is reduced to 8.27% after dynamic compensation by the proposed method. In the actual muzzle shock wave test, the dynamic compensation method can suppress the resonant frequency effectively, and make the pressure sensor test system achieve a better dynamic performance. Key

Optimization Method of Light-screen-array Structure Parameters of Photoelectric Target Based on Orthogonal Test

CHEN Rui， NI Jin-ping

2017, 38(11):  2234-2239.  doi:10.3969/j.issn.1000-1093.2017.11.021

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An optimization method for inversion of light-screen-array structure parameters is presented for their large calibrated errors. An objective function is established by using the square root of difference between measuring coordinates and actual coordinates, many groups of structure parameters are generated within the allowable error range based on orthogonal test, and the optimization method of light-screen-array structure parameters is designed. The simulated results of double-N shaped sky screen target in Matlab shows that the optimized results are affected by the initial value and the allowable error range, and the ball cartridge test results show that the proposed method is feasible and effective. The optimization method provides a new idea for improving the measuring accuracy of photoelectric target measuring equipment. Key

Availability Modeling and Analyzing of Multi-state Control Unit under Condition-based Maintenance

LI Zhi-qiang, XU Ting-xue, GU Jun-yuan, AN Jin, DONG Qi

2017, 38(11):  2240-2250.  doi:10.3969/j.issn.1000-1093.2017.11.022

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A modeling method of control units under condition-based maintenance (CBM) based on multi-state dynamic Bayesian network (DBN)is proposed for describing the dynamic characteristics of system. After defining multi-state components, a state-transition model based on Markov model is established in considering CBM, and absorbing state is introduced. A multi-state DBN model is established to determine the state-transition relationships with non-repair, perfect repair, imperfect repair, CBM and absorbing state. And the conditional probability value is obtained according to the logic relationship of series system and parallel system. A control unit is taken for example. The dynamic fault tree (DFT) and DBN model are established to determine the reliability curves of control unit and its components under different repair modes. And the weak links of reliability design are found through importance analysis. The simulated results show that the control unit under CBM has higher availability than the perfectly and imperfectly repaired control units. The availability of repairable components with degradation states can be predicted, and a maintenance policy can be made accordingly. Key

Research on a Phased Periodic Preventive Maintenance Model Based on Reliability Constraint

XI Qi-chao, CAO Ji-ping, CHEN Gui-ming, CHANG Lei-lei, XIONG Qi, WANG Sai

2017, 38(11):  2251-2258.  doi:10.3969/j.issn.1000-1093.2017.11.023

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In order to maintain the operational reliability of equipment during life cycle, the advantages and disadvantages of the periodic preventive maintenance model and the sequential preventive maintenance model are analyzed. A three-stage periodic preventive maintenance model is proposed based on the equipment maintenance practices. Three models, i.e., periodic preventive maintenance model, sequential preventive maintenance model and three-stage periodic preventive maintenance model, are constructed by taking the minimum cost rate of equipment life cycle under the reliability constraints as the optimization objective. The optimal preventive maintenance frequencies and intervals of equipment life cycle of each model are obtained. The case study results show that, under the same conditions, a high reliability and a low cost rate of equipment during life cycle can be obtained by using the three-stage periodic maintenance model. Moreover, it can also closely integrate the maintenance operation practices, as well as has a good feasibility and generalizability. Key

Research on Energy Absorption of Aluminum Foam-filled Double Circular Tubes under Lateral Impact Loadings

LIU Zhi-fang， WANG Jun， QIN Qing-hua

2017, 38(11):  2259-2267.  doi:10.3969/j.issn.1000-1093.2017.11.024

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The deformation modes and energy absorption of aluminum foam-filled double circular tubes under lateral impact loadings are studied using numerical simulation method. The influences of geometrical parameters of the structure, relative density of foam aluminum material and impact velocities on the mechanical behaviors of structures are analyzed. The simulated results show that the plastic deformation of impact component absorbs the most of energy at the initial moment, and then the plastic bending deformations of the left and right components absorb energy. The specific energy absorption (SEA) of aluminum foam-filled double circular tubes increases with the increase in the diameter of outer tube and the wall thickness of inner tube or the thickness of aluminum foam core. However, the SEA decreases with the increase in the wall thickness of outer tube and the diameter of inner tube. When the impact velocity is less than 30 m/s, the deformation mode is vertically and horizontally symmetrical. The deformation mode is only horizontally symmetrical when the impact velocity is larger than 30 m/s. It can be found that the SEAs of sandwich tubes increase with the increase in the impact velocity. The larger the relative density of aluminum foam core is, the more the SEAs of aluminum foam-filled double circular tubes are. Key

A New Ship Speed Correction Method for Measured Speed Data from Radar onboard Space TTC Ship

XIANG Jie, MAO Yong-xing, GUO Cai-fa

2017, 38(11):  2268-2273.  doi:10.3969/j.issn.1000-1093.2017.11.025

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In traditional speed-measuring method correction method for measured data from radar onboard space tracking, telemetering and command (TTC) ship, the effects of ship waggling, heaving and lateral movement on speed of antenna are ignored. In the traditional method, only the course data and the ship speed data are used to calculate the speed of radar antenna relative to the earth. By analyzing the derivation process of the traditional method, it is found that some systematic errors are ignored, which are found in simplified formula. A speed-measuring correction method is established to eliminate these systematic errors. The proposed method contains two sub-models: inertia navigation platform speed model based on GPS velocity determination, and object speed correction model. The data accuracy and orbit determination are tested in checking flight, near-earth orbit task and far-earth orbit task. The result shows that the proposed speed correction method is superior to the traditional method in the aspect of eliminating random error. Key

Research on Dynamic Stiffness of Vibration Isolator

LI Shi-yao, ZHANG Wei-guo, HOU Jun-zhan, DUAN Wen-bo, CHI Sheng-wei, GUO Bing-tao

2017, 38(11):  2274-2279.  doi:10.3969/j.issn.1000-1093.2017.11.026

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Dynamic stiffness is a crucial characteristic of vibration isolator. A method to calculate the dynamic stiffness of vibration isolator is proposed. The static stiffness is concluded from the experimental deformation-force curve. Dynamic stiffness is calculated by using single degree of freedom (SDOF) dynamic stiffness formula. An experiment is designed to verify the calculated results. Experimental results show that the deviation between calculated result and the experimental result is within 6%. The proposed method is effective and applicable for dynamic analysis of vibration isolators. Key

Vernier Gimballing Magnetically Suspended Spherical Flywheel and Its Rotor Optimization Design

LIU Qiang, HU Deng-liang, WU Bo, REN Yuan, WANG Wei-jie

2017, 38(11):  2280-2288.  doi:10.3969/j.issn.1000-1093.2017.11.027

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To remedy the limitation of the existing outer rotor scheme which increases the unbalance of rotor system due to screw connection, a vernier gimballing magnetically suspended spherical flywheel with inner rotor based on reluctance force and Lorentz force hybrid configuration is presented. The structure and working principle of the flywheel are introduced, and the control model of rotor system is analyzed. It is concluded that the disturbance of translation suspension on radial tilting control can be eliminated and the controller can be simplified as well when the centroid of rotor coincides with the geometrical symmetrical center of rotor and testing center. In consideration of the maximum equivalent stress, the first-order resonance frequency, the ratio of polar moment of inertia to equinoctial inertial moment, the polar moment of inertia, the maximum deformation and the deviation of the centroid of rotor and the sphere center of rotor are increased as constraint condition. The multidisciplinary optimization design of rotor system is performed by taking the high sensitivity parameters as optimal design variables and the minimum rotor mass as the optimization objective. The results indicate that the mass of rotor is decreased from 5.600 kg to 5.389 kg, which is reduced by 3.8%, under the condition satisfying the design requirements. The optimization design method can improve the design efficiency and control torque precision of flywheel system. Key