Table of Content

31 October 2017, Volume 38 Issue 10

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Contents

2017, 38(10):  0. 

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Paper

Multi-objective Optimization of Gun Barrel Structure Based on Adaptive Neural Network

XIAO Hui， YANG Guo-lai, SUN Quan-zhao, GE Jian-li, YU Qing-bo

2017, 38(10):  1873-1880.  doi:10.3969/j.issn.1000-1093.2017.10.001

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A structure optimization strategy using adaptive radial basis function artificial neural network (RBF ANN) is proposed for the large computational cost, slow convergence and easy to fall into local optimum in the multidisciplinary optimization design of gun. The high and low temperature-pressure curves of gun barrel are calculated based on the interior ballistic theory, as the load of numerical calculation of the finite element analysis model, by the secondary development of ABAQUS, which is used to obtain the optimization objectives. Then a RBF ANN is built to approximate the surrogate model for understanding the nonlinear relationships among the design variables and the optimization objectives. Penalty function method is used to solve the constraint problem, and the genetic algorithm is used to obtain current optimal solution. In the process of optimization, new sampling points are added, and the surrogate model is updated according to all the samples and their responses to improve the approximation accuracy around the local and global optimal solution. The multi-objective optimization strategy is validated by numerical test and the problem of optimization of the gun barrel structure performance to prove the efficiency of this optimization strategy. The results show that , compared to the initial design, the mass of optimized gun barrel is decreased by 6.63%, the structural stiffness is increased by 5.60%, and the maximum Von Mises stress is decreased by 6.34%. Furthermore, compared to GA without surrogate model, the number of function evaluation is decreased by 86.5%, and the total runtime is decreased by 83.3%. Key

Experimental Study of Impingement Spray of Dual-fuel Injector of Opposed Piston Two-stroke Diesel Engine

LIU Yu-hang, ZHAO Zhen-feng, ZHANG Fu-jun, XIE Zhao-yi, LU Yi, CUI Hua-sheng

2017, 38(10):  1881-1890.  doi:10.3969/j.issn.1000-1093.2017.10.002

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Due to the special combustion chamber shape and spray mode of opposed piston two-stroke diesel engine, the fuel injection sprays impinge at the center of combustion chamber. The good matching of combustion chamber shape, spray characteristics and in-cylinder gas flow should be assured to obtain desired gas mixture. For the spray characteristics of combustion chamber in opposed piston two-stroke diesel engine, the schlieren method is used to study the influences of fuel injector position, injection pressure, constant volume bomb pressure and injection duration on spray penetration and spray spatial diffusion rate. The results show that, compared with single injector, the dual-fuel injector has higher spatial diffusion rate and is more beneficial to the atomization of fuel in the case of 75 MPa injection pressure, 2 MPa constant volume bomb pressure and 1.5 ms injection duration. The increase in injection pressure is beneficial to the diffusion of fuel in space, but the fuel distributed in near-wall area would be increased. As a result, the emission will be worsen because of “cylinder wall wetting”. Low constant volume bomb pressure causes a rich mixture near the cylinder wall, while high back pressure makes the fuel concentrate in the center of combustion chamber where the flow is weak. With the increase in injection duration, the increase in spray penetration and spatial diffusion rate becomes less noticeable. Key

Adaptive Fuzzy Sliding Mode Control for the Artillery Modular Charge Transport Servo System

YUE Cai-cheng, QIAN Lin-fang, KONG Jian-shou, LI Ying

2017, 38(10):  1891-1898.  doi:10.3969/j.issn.1000-1093.2017.10.003

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An adaptive fuzzy sliding mode controller (AFSMC) with an integral sliding mode function is proposed for the control of the artillery modular charge transport servo system which has time-varying parameters and chattering problem. The time-varying system parameters are estimated by using adaptive method. The influence of model uncertainty on the control system is reduced. Then, the traditional switching function is replaced by an improved saturation function. This ensures that the process of switching is more continuous and smooth. The coefficient of switching is tuned online by the fuzzy adaptive scheme. In this way, the robustness of system is enhanced, and the chattering of system is restrained. Experimental results show the system has a good position tracking performance under empty-load, half-load and full-load, which can meet the performance index. The proposed AFSMC scheme can overcome the influence of variable loads on the control precision of the system. Key

Research on Barrel Life Test of Revolving Barrel Cannon by Substituting Full Charge Loading with Non-full Charge Loading

ZHANG Pei-zhong, ZHENG Jian-fu, MI Zhong-he, CHEN Guo-li, NING Jin-gui, HUANG Yan-chang

2017, 38(10):  1899-1908.  doi:10.3969/j.issn.1000-1093.2017.10.004

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The technology of substituting full charge loading with non-full charge loading is researched to decrease the ammunition consumption in the barrel life test of revolving barrel cannon. The computing equations of muzzle vibration displacement are established. High-order Fourier series is used to fit the resultant force in bore, and then the frequency equations of resultant force are established. The modal parameters of cannon are obtained by model measuring and analysis, and a frequency response equation of the cannon elevating part is established. The frequency response equation is used to calculate the muzzle vibration displacements in the way of non-full charge loading and full charge loading. The differences among these muzzle vibration displacements are compared. Based on the law that the muzzle vibration displacements of non-full charge loading and full charge loading are consistent, the barrel life test scheme is confirmed. In verification experiment, the barrel life’s consistency is proved. The barrel life test method of less amount ammunition is designed to decrease the ammunition consumption in test. Key

Dynamics Modeling and Simulation of Recoil Reduction of Automatic Weapon by Time-delay Nozzle Device

XIAO Jun-bo， YANG Guo-lai， LI Hong-qiang， QIU Ming， LIAO Zhen-qiang

2017, 38(10):  1909-1917.  doi:10.3969/j.issn.1000-1093.2017.10.005

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In order to reduce the recoil force of automatic weapon system and keep the initial velocity of projectile unchanged, a time-delay nozzle flow recoil-reduction device is presented. The in-bore pressure drop is delayed by opening the gas port of the barrel in an appropriate time-delay, thus keeping the initial velocity of projectile unchanged. A mathematical model considering variable mass effect in interior ballistic and after-effect process is derived, in which the mass and energy transferring process is considered. In addition, a mathematical model describing the relationship between time-delay nozzle gas flow and recoil force is established. The effects of some structural parameters on recoil-reduction efficiency are studied through simulation. The results show that the time-delay nozzle flow device can provide sufficient anti-recoil impulse, and can reduce the recoil force effectively while has less effect on the initial velocity. Key

Simulation and Experimental Study of Tantalum Liner to Form Dual-mode Damage Element by Detonation

FAN Xue-fei, LI Wei-bing, WANG Xiao-ming, GUO Teng-fei, LI Rui

2017, 38(10):  1918-1925.  doi:10.3969/j.issn.1000-1093.2017.10.006

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Based on the problems of tantalum materials in the application of multi-mode warhead, the feasibility study on the formation of dual-mode damage element by detonation-driven tantalum liner is conducted. The dynamic properties of tantalum materials were tested by Hopkinson bar test. The effects of tantalum liner structure parameters (cone angle, radius of curvature and wall thickness) on the formation of EFP and JPC are studied by LS-DYNA finite element software. It is found out that the range of each parameters of optimum dual mode damage element for the formation of the cone angle is 140°-150°, the radius of the arc is 0.45-0.55 times of charge diameter, and the wall thickness is 0.02-0.024 times of charge diameter. The optimum structure parameters of the tantalum liner warhead are determined by the orthogonal design, and X-ray imaging test is carried out. The experimental results are in good agreement with the simulation results, the error are controlled in 15%, and the actual penetration depth is raised to 55.4% compared to Cu. It is proved that Ta is suitable for the liner of multi-mode warhead. Key

Measurement and Modification of Dynamic Friction Coefficient of Pressed Explosive

LUO Yi, LIU Yan, HUANG Feng-lei

2017, 38(10):  1926-1932.  doi:10.3969/j.issn.1000-1093.2017.10.007

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In order to investigate the effect of dynamic friction coefficient on the friction ignition of pressed explosive, 8701 pressed explosive is tested on the friction testing system based on the drop hammer apparatus, and tthe coefficients of dynamic friction between 8701 pressed explosive and 45^# steel at different normal pressures are studied. The experimental results show that, when the normal pressure is increased from 1 MPa to 10 MPa, the dynamic friction coefficient is reduced from 0.28 to 0.10, indicating that the dynamic friction coefficient is dependent on pressure. A calculation model of the friction coefficient is proposed based on the experimental results and introduced into the LS-DYNA through secondary development. The thermo-chemo-mechanical coupling numerical simulation is conducted for the skid test of 8701 pressed explosive. The calculated results show that the improved calculation model of friction coefficient prolongs the ignition delay time, increases the critical ignition velocity and raises the critical ignition temperature. The proposed model can be used to study the non-shock friction ignition problem. Key

Dynamic Deformation and Fracture Fragmentation Behavior of Metal Cylindrical Shell at High Strain Rates

ZHU Jian-jun， LI Wei-bing， LI Wen-bin， WANG Xiao-ming， ZHENG Yu， LU Hai-tao， YUAN Shu-qiang

2017, 38(10):  1933-1941.  doi:10.3969/j.issn.1000-1093.2017.10.008

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To understand the complex dynamic response of deformation and fracture of metal cylindrical shell at high-strain rates loading, the cylinder shells fabricated from 50SiMnVB steel and 40CrMnSiB steel were selected as the objects for study. The ultra-high speed photographic technology and AUTODYN-2D finite element software are applied to research the dynamic deformation of shell at high strain-rates, which obtaine the variation of radial displacement and velocities of outer-wall from the shell, and the fragment mass distribution and fracture fragmentation behavior of the resulting fracture fragments are analyzed. The results reveal that the phase of cracks penetrating the entire casing wall thickness occurs within the time range of 20-25 μs, and the velocity of 40CrMnSiB steel shell is increased by 8.1%, compared with that of 50SiMnVB steel shell. Moreover, the distribution of fragments width is of Gaussian-distribution, the fragmentation degree of fragments formed by 40CrMnSiB steel shell is more serious, and the number of fragments with mass of more than 0.1 g is increased by 49% compared with that of 50SiMnVB steel shell. Key

Interfacial Interaction Between NPBA and HMX

QI Xiao-fei, XIE Wu-xi, YAN Qi-long, LIU Qing, LIU Chun

2017, 38(10):  1942-1949.  doi:10.3969/j.issn.1000-1093.2017.10.009

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In order to explore the interfacial interaction mechanisms of neutral polymeric bonding agent (NPBA) and HMX, which is important for molecular design of NPBA, their interfacial bonding is evaluated by using molecular dynamics simulation. The interfacial tension and the work of adhesion between NPBA and HMX are measured by means of the dynamic contact angle meter and tension meter. The results show that the H-bond and van der Waals force could be formed on the interface among three kinds of NPBA molecules and HMX crystals. In general, the NPBA with —COOCH₃ group has higher interfacial bonding than that containing —COOCH₂CH₂OH group. With the increase in —CN content in NPBA, the interfacial bonding increases as well, resulting in the enhanced tensile strength of the corresponding propellants. Key

Research on Fuzzy Proportional Guidance Law of Air-to-ground Attack Based on Genetic Algorithm

LI Bo， WANG Yuan-xun， GAO Xiao-guang， CUI Si-jie

2017, 38(10):  1950-1956.  doi:10.3969/j.issn.1000-1093.2017.10.010

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At present, one of the development trends of air-to-air missiles is that the missile is used to attack both ground and air targets. On the basis of the three-dimensional proportional guidance law， the genetic algorithm is used to solve the optimal fuzzy control rules, and then the fuzzy control theory is used to control the proportional coefficient component of the three-axis in the proportional guidance law, thus establishing an integrated guidance law that enables the missiles to effectively attack the air and ground targets. The missile air-ground integrated attack guidance law is compared with the traditional three-dimensional proportional guidance law through the simulation experiment. The simulated results show that the proposed navigation law can be used for missile attacking the air-to-ground targets effectively and hasving a greater hit angle in the attack on ground target, so it is suitable for the air-to-ground integrated attack mode.Key

Research on Double Layer Medium Gap Test and Analysis of Shock Initiation Characteristics of Acceptor Explosive

CHEN Chuang， HAO Yong-ping, YANG Li， WANG Xiao-ming， LI Wen-bin， LI Wei-bing

2017, 38(10):  1957-1964.  doi:10.3969/j.issn.1000-1093.2017.10.011

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A calculation model for shock wave energy of acceptor explosive is established to study the shock initiation characteristics of acceptor explosive in double layer medium gap test, in which the effect of lateral rarefaction wave is considered, and a manganin piezoresistive pressure gauge is used for pressure measurement. The effects of sequencing (two kinds of wave impedance sequence), total thickness (30-60 mm), thickness distribution (PMMA thickness ratio of 10%~90% ) of double layer medium consisting of PMMA and LY-12 aluminum on the explosive transmissive shock wave parameters are analyzed, and the transmissive shock wave pressure and shock initiation situation of acceptor explosive are verified by the experiment. The results show that the transmissive shock wave energy is lower when the sequence with increasing wave impedance is applied, which is more beneficial for explosive stability; the transmissive shock wave energy decreases with the increase in medium thickness, and its decreasing amplitude gradually decreases; the change of shock wave energy with thickness distribution is relevant to the total thickness of double layer medium, and the transmissive shock wave energy exhibits a trend of ascending (h=30 mm), and increases first and then decreases (h=40-60 mm) with the increase in PMMA thickness. Key

Ill-condition Analysis and Robust Estimation for Multi-sensor Spatial Registration

PAN Jiang-huai, QIAO Hui

2017, 38(10):  1965-1973.  doi:10.3969/j.issn.1000-1093.2017.10.012

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In order to improve the accuracy and stability of multi-sensor spatial registration, the causes of the ill condition of the multi sensor spatial registration are analyzed based on LS estimation for multi-sensor spatial registration. The analysis result shows that the ill-condition of the Fisher information matrix is the key factor which influences the quality of system error parameter estimation. The conditional index of information matrix is used to measure the ill-condition of spatial registration. A new algorithm of compound modified singular value decomposition (CSVD) for robust estimation is proposed according to the characteristics of trapezia distribution of the information matrix singular values. The algorithm can effectively suppress uncertainty components and retain deterministic components in the observation equation by modifing only minor conditional index, and can effectively solve the multi sensor real time estimation of spatial registration. Two different scenarios of the estimatied results show that CSVD method can be used to significantly improve the estimation accuracy and stability of system error parameters. Key

Research on the Trajectory Characteristics of Supercavitating Vehicle at Preset Rudder Angle

SHI Su-guo， WANG Ya-dong， LIU Le-hua， YANG Xiao-guang

2017, 38(10):  1974-1979.  doi:10.3969/j.issn.1000-1093.2017.10.013

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The turning maneuver trajectory characteristics of the supercavitating vehicle on the horizontal plane are realized by presetting the rudder angles in the head of supercavitating vehicle， and the free motion of vehicle at the preset rudder angles of 0°, 3°and 6° is investigated in experiment. The experiment is done in a pool. The eveluationary process of cavity is observed by using a high-speed video camera， the motion parameters of vehicle are measured using a built-in measuring device，and the turning maneuver trajectory characteristics of supercavitating vehicle on the horizontal plane at different preset rudder angles are acquired. The experimental results show that the side force of vehicle shows a small fluctuation due to the perturbation of the unsteady factors when the preset rudder angle is 0°， but the average value is basically 0. When the preset rudder angle exists， the axial and side forces increase with the increase in the preset rudder angle. The preset rudder angle can be used to control the horizontal turning maneuver of supercavitating vehicle. The larger the preset rudder angle is， the easier the turning maneuver is， but an overlarge preset rudder angle may cause the trajectory destabilization. Key

Research on Variable-depth Motion Control of Supercaviting Vehicle Based on Hybrid Extended Kalman Filter

BAI Tao， JIANG Yun-hua， HAN Yun-tao

2017, 38(10):  1980-1987.  doi:10.3969/j.issn.1000-1093.2017.10.014

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A control method based on hybrid extended Kalman filter is proposed to solve the lose control during variable-depth motion of supercavitating vehicle caused by measured and environmental noises. The math model of supercavitating vehicle is improved based on the measured and environmental noises obtained by experiment in water tunnel. The control law is improved by using hybrid extended Kalman filter for variable-depth motion of supercavitating vehicle. Simulated result shows that the the hybrid extended Kalman filter can be used to improve the motion stability of supercavitating vehicle during variable-depth motion. Key

Numerical Simulation and Verification of Magnetic Signatures of Ship Degaussing Coils

GUO Cheng-bao, ZHOU Wei-chang

2017, 38(10):  1988-1994.  doi:10.3969/j.issn.1000-1093.2017.10.015

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As alternative to commercial electromagnetic field finite element analysis software, the ship magnetic software MagShip based on the magnetic moment method (MMM), the multilevel adaptive cross approximation (MLACA) and the graphical processing unit (GPU) with high parallel processing capability has been successfully used in ship magnetic signatures simulation. However, when the magnetic signatures of the ship degaussing coils are analyzed numerically, the mesh of hull structure near the ship degaussing coils would be finely generated. When the software MagShip is used for this kind of large-scale magnetic field modeling, the computational results may be unstable or distorted. In order to solve this problem, the software MagShip was improved for the modelling of the magnetic field signatures of ship degaussing coils. The improvement measures of MagShip are to average the coupling coefficients of the adjacent elements by using several points in the field elements, subdivide the elements near the degaussing coils, and average the magnetizing fields on the elements near the degaussing coils by using several points in the elements. The improved software MagShip was used to simulate several test examples, including the degaussing coils in and outside the thin spherical shells, and the degaussing coil in the submarine hull. The difference between the calculated results of the proposed method and the commercial FEM COMSOL Multiphysics software is about 1%. The result shows that the proposed method can be used to model the magnetic signatures of ship degaussing coils．Key

Experiment and Simulation Prediction of Grinding Burn of Gear Steel 18Cr2Ni4WA

LIANG Zhi-qiang， HUANG Di-qing， ZHOU Tian-feng， LI Hong-wei， QIAO Zhi， WANG Xi-bin， LIU Xin-li

2017, 38(10):  1995-2001.  doi:10.3969/j.issn.1000-1093.2017.10.016

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18Cr2Ni4WA steel has been widely used to manufacture the heavy-duty gears, such as spiral bevel gear, which is characterized by high toughness and high strength. Grinding burn easily occurs due to the high temperature during grinding, which makes the grinding precision and surface quality difficult to meet the requirements. The surface hardness, hardness gradient and surface morphology of workpiece are analyzed through single factor experiment, and the degree of grinding burn is simulated using the finite element analysis software. The results show that, with the increase in grinding depth, the degree of grinding burn is aggravated, the color of oxide layer is changed from faint yellow to brown, and finally becomes cyan, and the surface morphology is changed from clear texture to heavily coated. The hardness of surface layer decreases and a tempered sorbite is produced due to tempering burn. The measured and simulated values of grinding burn depth are basically identical, which shows that the degree of grinding burn can be predicted by the finite element simulation. Key

Research on Formation of 3-D Micro-surface in Ultrasonic Elliptical Vibration Cutting

ZHANG Guo-hua， LI Dong-dong， LI Mao-wei， ZHANG De-yuan

2017, 38(10):  2002-2009.  doi:10.3969/j.issn.1000-1093.2017.10.017

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In order to find the influence factors and the influence law of the 3-D micro-surface formation of ultrasonic elliptical vibration cutting, the elliptical vibration cutting process and 3-D cutting model are analyzed based on the metal cutting theory. The results show that the different phase difference eigenvalue between two adjacent turns in vibration cutting process has an important influence on the final surface geometry. The existing cutting test results show that the final surface shapes with the eigenvalues of 0 and 0.5 are very different, and the results agree with the theoretically analyzed results. Key

Impact of Abrasive Flow Polishing Temperature on Nozzle Quality under Mesoscopic Scale

LI Jun-ye， WEI Li-li， ZHANG Xin-ming， QIAO Ze-min

2017, 38(10):  2010-2018.  doi:10.3969/j.issn.1000-1093.2017.10.018

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The influence of the polishing temperature on the quality of workpiece during abrasive flow polishing as a precision machining technology has been studied in the macroscopic and microscopic scales, and the simulation in the mesoscopic scale is still rarely involved. By constructing the abrasive grains mainly composed of atomic clusters, the dissipative particle dynamics method is used to study the impact wear behavior of abrasive grains on the inner surface of engine injector at different temperatures. The results show that the higher the temperature is, the better the polishing quality of abrasive flow is, and the best abrasive grain polishing quality at the polishing temperature of 300~310 K is achieved. However, when the polishing temperature is higher than 310 K, the abrasive flow polishing quality is declined. The results show that the abrasive flow polishing technology can be used effectively to achieve the polishing of fine pore structure, and improve the polishing accuracy and surface quality. Key

Evolution Model of Equipment Support System of Systems Based on Complex Network Theory

GAO Long, CAO Jun-hai, SONG Tai-liang, XING Biao, YAN Xu

2017, 38(10):  2019-2030.  doi:10.3969/j.issn.1000-1093.2017.10.019

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The equipment support system of systems (SOS) architecture plays a decisive role in the effectiveness and adaptability of SOS, and the evolution model is a key technology to construct the equipment support SOS architecture. An improved evolution model of equipment support SOS based on the multi-weighted network is proposed for the heterogeneity of the entities in the equipment support SOS and the impact of the support mission requirements on the architecture evolution. The network characteristics of equipment support SOS is analyzed, the complex network theory is introduced to construct the initial weighted network model of the equipment support SOS, and the network evaluation indexes are presented. On this basis, the network evolution rule and the improved evolution model are proposed. In the weighted network model, the support mission requirements are abstracted as the network nodes, and the uncertainty of mission requirements is described by a quaternion, and the fitness index is used to link support mission requirements with the SOS architecture. The heterogeneity of network nodes is characterized by the type and support capability of nodes, and regarded as a major factor in the evolution process. The simulation experimental results show that the improved model can be used to determine the influence of the support mission on the evolution process, improve the adaptability of SOS architecture to the mission, and enhance the SOS effectiveness in a certain range. Key

Research on Pedestrian Navigation Algorithm Based on Zero Velocity Update/Heading Error Self-observation/Geomagnetic Matching

HUANG Xin, XIONG Zhi, XU Jian-xin, XU Li-min

2017, 38(10):  2031-2040.  doi:10.3969/j.issn.1000-1093.2017.10.020

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Nowadays, pedestrian navigation technology is playing an increasingly important role in supermarket shopping, fire rescue and field exploration, and the pedestrian navigation and positioning without global navigation satellite system (GNSS) has become an indispensable link. The self-contained sensors are used as a hardware platform for research on pedestrian autonomous navigation in non-GNSS environment. A zero-speed comprehensive discriminant algorithm based on the “2+2” hierarchical model is studied to improve the accuracy and reliability of zero velocity update (ZUPT). Kalman filter algorithm based on ZUPT designed for inertial navigation system is used to effectively suppress the sensor error divergence. To solve the problem of pedestrian long-term heading divergence, the magnetic heading error self-observation algorithm (MHESO) for pedestrian initial static state and the ZUPT heading error self-observation algorithm (ZHESO) for pedestrian movement are studied. In addition, a geomagnetic matching (GM) algorithm based on multi-layer constraint and K-nearest neighbor algorithm is proposed, and the fusion of ZUPT_HESO-pedestrian navigation algorithm and geomagnetic matching algorithm is realized, which improves the accuracy and reliability of pedestrian navigation. The actual data test proves that the proposed pedestrian navigation algorithm based on ZUPT_HESO_GM effectively improves the positioning accuracy by more than 79%. Key

Interest Point Detection Method Based on Dilation Operation

WANG Qing， DING Chi-biao， FU Kun， REN Wen-juan

2017, 38(10):  2041-2047.  doi:10.3969/j.issn.1000-1093.2017.10.021

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An interest point detection method based on dilation operation (DMDO) is proposed to improve the efficiency and accuracy of interest point detection, in which binarization is used to filter the noise, and the dilation operation is used to replace the clustering approach to enhance the efficiency of algorithm. DMDO is applied to two datasets of open space-AMSA and IMIS3Days. Compared to Density-Based Spatial Clustering of Applications with Noise (DBSCAN) , the accuracy of DMDO is increased by 17.94% on dataset AMSA, and by 19.98% on dataset IMIS3Days, while the efficiency is improved by 6.63 times on dataset AMSA, and by 9.13 times on dataset IMIS3Days. Compared to Ordering Point To Identify the Cluster Structure (OPTICS), the accuracy of DMDO is increased by 20.04% on dataset AMSA, and by 16.60% on dataset IMIS3Days, while the efficiency is improved by 14.61 times on dataset AMSA, and by 42.19 times on dataset IMIS3Days. Experimental results demonstrate that, compared with traditional methods, DMDO has higher accuracy with less time overhead. DMDO is applicable to detect the interest points in the era of big data. Key

Study of Cross-correlation Algorithm-based Weak Signal Extraction Method for Laser Alignment of Large Unit

TANG Chen， ZHANG Mao-yun， CAO Guo-hua， DING Hong-chang

2017, 38(10):  2048-2054.  doi:10.3969/j.issn.1000-1093.2017.10.022

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To improve the laser alignment accuracy of a large unit shafting and reduce the errors caused by position sensitive detector (PSD) that is easily interfered by stray light, a weak signal detection algorithm based on cross-correlation algorithm is proposed, the specific mathematical models are established, and the circuits are designed. The position error compensation of laser alignment instrument for large unit shafting is achieved using the mathematical model of cross-correlation algorithm and circuit. To obtain the data of PSD, a 2-D micro-displacement platform was built to test the system. The repeatability tests were completed using the micro-displacement platform, then the measured data was analyzed. The results indicate that the proposed method can ensure the alignment accuracy of the equipment with the resolution of 0.005 mm, and the anti-noise performance of large unit shafting laser alignment instrument can be effectively improved. Key

Research Notes

Analysis of Structure Parameters of Airflow-induced Vibration Piezoelectric Generator for Fuze

ZOU Hua-jie, ZHANG Jiang-hua, CHEN He-juan, WANG Ze-ping

2017, 38(10):  2055-2061.  doi:10.3969/j.issn.1000-1093.2017.10.023

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In order to meet the requirements of airflow-induced vibration of small piezoelectric generator for fuze, and solve the critical issue of stable excitation force, the key is to effectively control the sensitive parameters of generator structure. The influence of related structural parameters of airflow-induced excitation device on excitation force is analyzed through simulating flow test. The test result shows that the amplitudes of excitation force corresponding to different resonator lengths increase approximately linearly with the airflow velocity, and the longer the length of resonator is, the smaller the slope is, and vice versa. The space between nozzle and resonator and the ring gaps have the complex effects on the amplitude of excitation force , and too big or too small gap would make the amplitude smaller or even no waveform formed. The length of resonator is the main factor impacting on the frequency of excitation force, and the frequency decreases with the increase in the resonator length, presenting an inverse relationship. The space between nozzle and resonator and the ring gaps have less effects on the frequency of excitation force. Therefore, for high airflow velocity, the stable excitation force with high amplitude and frequency can be obtained by short resonator. In addition, reasonable space and ring gaps are also important for ensuring bigger amplitude of excitation force. The resulting sensitive parameter values of sound excitation device can be used as references for engineering design. Key

Robust Labeled Multi-Bernoulli Tracking Algorithm Based on Box Particle Filtering

WEI Shuai, FENG Xin-xi, WANG Quan, LU Chuan-guo

2017, 38(10):  2062-2068.  doi:10.3969/j.issn.1000-1093.2017.10.024

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The standard labeled Bernoulli (LMB) filter cannot guarantee a higher tracking performance, and multitude number of particles leads to the longer operation time of algorithm under the conditions of unknown clutter and detection probability. A robust labeled multi-Bernoulli algorithm based on box particle filtering is proposed. An augmented state space model is established, and the prediction and update state recursion equations with clutter state labels and LMB element labels are derived based on box particle filtering. The state of multi-target is recursively estimated using LMB filter box particles. Simulation reveals that the proposed algorithm has a better performance in target tracking under the conditions of unknown clutter and detection probability, and dramatically reduces the computation time with higher tracking accuracy under the conditions of lower detection probability and higher clutter ratet compared with the conventional algorithm with non-label and non-robustness. Key

Research on Movement Characteristics of Needle Valve in Common Rail Injector for Diesel Engine

QIU Tao， LIU Tian-xiang， AN Xiao-dong， LEI Yan， DAI He-fei

2017, 38(10):  2069-2074.  doi:10.3969/j.issn.1000-1093.2017.10.025

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The movement of needle valve in the common rail injector determines the injection and atomization effect directly. The movement rule of needle valve in the common rail injector is important to improve the structure of injector and the atomization effect. A high-pressure common rail injector simulation system was built, and a calculation model was established for optimizing the flow coefficients in two stages of cavitation and non-cavitation at the oil inlet and outlet holes of high pressure common rail injector and in the ball valve area. The movement characteristics of needle valve in the common rail injector are studied through theoretical analysis and experiments. The results show that the opening process of needle valve can be divided into two stages: slow opening stage and fast opening stage. Two opening stages of needle valve are due to the transfer of the throttled position. However, the needle valve is mainly influenced by the throttled position, so the closure of the needle valve is a single-stage. Rail pressure has an effect on the second fast opening stage, but not on the slow opening stage or the closing process. The opening process speeds up with the rise of the rail pressure. When the rail pressure reaches to a certain value, the fast opening stage of needle valve remains unchanged. Key

Tribological Properties of Rod End Spherical Plain Bearings with Modified Injection Molding Nylon

QIU Ming, LIANG Xia， LI Ying-chun

2017, 38(10):  2075-2080.  doi:10.3969/j.issn.1000-1093.2017.10.026

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Two kinds of rod end spherical plain bearings are tested on a tribo-tester, of which the nylon liners are reinforced by carbon fibers as well as by carbon fibers and PTFE, respectively, and their friction coefficients and wear depths at different contact pressures are investigated. With the help of a scanning electron microscope (SEM), an energy dispersive spectrometer (EDS) and a Fourier transform infrared spectrometer, the microstructures and wear mechanisms of two rod end spherical bearings are compared and analyzed. Experimental results show that the tribological properties of the bearings with the nylon liners reinforced by carbon fibers and PTFE are optimal, and their wear resistances are significantly improved. Slight adhesive wear and abrasive wear occurred on the worn surfaces of the liners reinforced by carbon fibers and PTFE, and severe adhesive wear and abrasive wear occurred on the worn surfaces of theliners reinforced by carbon fibers. Key