Table of Content

25 October 2018, Volume 39 Issue 10

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Contents

2018, 39(10):  0. 

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Paper

Research on Control Method for Improving Low Speed Performance and Stable Precision of Electro-optic Servo System

QI Chao, FAN Shi-xun, XIE Xin, CHEN Ning, FAN Da-peng, JIANG Xian-liang

2018, 39(10):  1873-1882.  doi:10.3969/j.issn.1000-1093.2018.10.001

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Servo mechanism is the core component of electro-optic stabilized platform，and its low speed performance and stable precision are the key technical indicators. The satisfactory performance of electro-optic stabilized platform is always difficult to be achieved due to the nonlinear disturbance，which cannot be eliminated by linear close-loop method, such as PID control law. A control method based on the state augmented Kalman filter (SAKF) is proposed to suppress the torque disturbance. The numerous groups of experiments were conducted for method verification, which shows a well compensation for the torque disturbance and the significant improvements of low speed performance and stable precision by the SAKF-based control method. Key

Research on Equivalent Air Leakage Area Detection Model of Heavy Vehicle Diesel Engine

YANG Shao-qing, ZHAI Zhen-dong, WANG Xian-cheng, WANG Xue

2018, 39(10):  1883-1891.  doi:10.3969/j.issn.1000-1093.2018.10.002

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A double-ring geometric simplified model of the leakage process of diesel engine cylinder-piston ring is established for quantitatively detecting the leakage condition of diesel engine in the non-dismantling state. The mathematical expression of leakage area of piston ring is deduced by analyzing the flow and pressure changes of the cylinder air during compression stroke. The influence of thermal defor- mation of piston ring on the leakage is analyzed, and an equivalent air leakage area detection model of cylinder- piston ring is established. The results show that the equivalent air leakage area is consistent with the wear condition of diesel engine cylinder liner, the correlation with the working condition of diesel engine is low, and the proposed model can reflect the current leak condition of diesel engine. Key

Profile Design and Seizure Analysis of Piston Pin Bearing of a Diesel Engine

ZHANG Li-min, WANG Gen-quan, WANG Yan-rong, ZHAO Zhi-qiang, ZHANG Zhong-wei, SONG Xian-hao

2018, 39(10):  1892-1900.  doi:10.3969/j.issn.1000-1093.2018.10.003

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For the seizure failure of piston pin bearing in the preliminary structural design, the heat transfer of piston is simulated and its temperature field is calibrated, and the thermo-mechanical deformation of piston at state is analyzed. The analytic results show that the non-compatible deformation of piston pin bearing is main reason leading to wear. Accordingly, the profile matching of piston pin boss bearing under thermo-mechanical condition is presented. On this basis, the profile of piston pin boss bearing is optimized, and the optimized profile is validated by simulation and engine test. The barrel-shaped, exponential and hyperelliptic profiles of the connecting rod small end bearing are compared to investigate the influences of those profiles on the load distribution of the bush. Results show that exponential and hyperelliptic profiles are more suitable for improving the load distribution of the connecting rod small end bearing.Key

Numerical Simulation on Concentration Distribution of Dust Caused by Tank Moving

CHEN Hui-min, FENG Xing-tai, WANG Feng-jie, LIU Wei-bo, YANG Shang-xian

2018, 39(10):  1901-1909.  doi:10.3969/j.issn.1000-1093.2018.10.004

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The changes of outflow field caused by tank moving and the concentration distribution of dust at different wind speeds and mass flow rates are simulated using ANSYS Fluent software based on the theory of gas-solid two-phase flow. The generation mechanism of dust caused by tank moving in a typical battlefield and the laws of dust concentration distribution under the influences of different factors are studied, which can provide theoretical support and data reference for laboratory simulation of dust caused by tank moving. The results indicate that a large number of turbulent eddies generated at its tail and sides during tank moving are one of the main reasons to cause the movement of dust particles. The greater the wind speed is, the lower the dust concentration at the center of tank tail is, the higher the dust concentration at the sides of the tank tail is, and the more rapidly the concentration changes. When the dust flow rate is higher, the dust diffuses more fastly, and the average dust concentration increases linearly with the increase in the mass flow rate. The average dust concentration at other mass flow rates can be calculated based on the average dust concentration data at a certain mass flow rate. Key

The influence of Correction Fuze’s Structure Parameters on the Stability of Spin-stabilized Projectile

WANG Yu， YU Ji-yan， WANG Xiao-ming， FENG Bin

2018, 39(10):  1910-1918.  doi:10.3969/j.issn.1000-1093.2018.10.005

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The stability criteria related to the structure parameters of correction fuze are derived based on the simplified model and engineering methods for the aerodynamic characteristics of wing-body combinations, Murphy’s complex variable method and the Hurwitz stability theory. The influence of structure parameters of correction fuze on the stability of spin-stabilized projectile is analyzed for the design and optimization of correction fuze. The stability analysis demonstrates that the forward movement of mass point of the combinations through the balance weight or the structure optimization of correction fuze is in favor of stability when the boundary dimensions of correction fuze (except for the canards) are the same; the increase in the deflection angles of canards is better than the extension of wingspan in order to increase the correction force while reducing the effect on stability. The simulations and experiments verify that the flight stability of projectile can be enhanced by moving the mass point of the combinations forward. Key

A Calibration Method of Magnetometer-aided Two-axis Gyro Sensor in the Projectile-borne Environment

JU Tan, YU Ji-yan, WANG Xiao-ming, GU Xiao-hui

2018, 39(10):  1919-1926.  doi:10.3969/j.issn.1000-1093.2018.10.006

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A calibration method of magnetometer-aided two-axis gyro sensor is studied for the three-axis calibration of two-axis gyro sensor in the projectile-borne environment. A measurement error model of two-axis gyro sensor is established, and the problem that the roll angular rate of low spinning projectile at x-axis, which is obtained from the single-axis geomagnetic signal, cannot be measured by the gyro sensor due to its limited measurement range is solved. The calibration methods of the linear least square model and the Kalman filter model for calculating the related parameters of two-axis gyro sensor are studied, and the influences of the calculation error of x-axis angular rate of projectile and the measurement noise of gyroscope sensor on the calibrated result are analyzed through numerical simulation. The application of two-axis gyro sensor in engineering is simulated, and the correction effect of calibration method of magnetometer-aided two-axis gyro sensor is studied in the hardware-in-the-loop simulation. The numerically simulated results prove that, when the calculated error of x-axis angular rate of projectile is within 0.261 8 rad/s and the measured noise of gyro sensor is within 0.001 6 rad/s, the corrected errors of the y-axis and z-axis angular rates of projectile are less than 0.01 rad/s. The results of the hardware-in-the-loop simulation show that the two correction models can decrease the measured error range of gyro sensor from -0.30- -0.05 rad/s to -0.02-0.02 rad/s when the calculated error of x-axis angular rate of the projectile is within 0.8 rad/s. The numerical simulation and the hardware-in-the-loop simulation prove that the magnetometer-aided calibration method has a good correction effect on the two-axis gyro sensor. Key

Evaluation of Damage Efficiency of Terminally Sensitive Submuinition Scanning in the Ascent on Tank Target

YU Tao, HAO Yong-ping, ZHENG Bin, LI Jian-wei, LI Guang-lin

2018, 39(10):  1927-1935.  doi:10.3969/j.issn.1000-1093.2018.10.007

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A scheme to evaluate the damage efficiency is presented for studying the damage efficiency of terminally sensitive submunition scanning in the ascent. A damage efficiency evaluation model is proposed by establishing a scanning recognition model, a hitting model and a tank target damage model for terminally sensitive submunition scanning in the ascent, and the damage efficiency evaluation process based on Monte Carlo method is presented. The scanning recognition probability and hit probability of terminally sensitive submunition scanning in the ascent under the conditions of different initial disturbance, rotation speed, missile-target distance and target speed are calculated, and the damage efficiency of terminally sensitive submunition scanning in the ascent is evaluated. The change rules of the damage effectiveness of terminally sensitive submunition scanning in the ascent with initial disturbance, rotation speed, missile-target distance and target speed are obtained. The analysis results show that the scanning recognition probability decreases with the increase in initial disturbance and target speed, and increases with the increase in rotation speed. When the initial disturbance is not more than 0.5 rad/s and the speed is not less than 20 r/s, the recognition probability of tank target is more than 97.5%. The hit probability decreases with the increase in target distance and speed. The damage probability of terminally sensitive submunition scanning in the ascent against tank targets at different speeds is greater than 70%. Key

Acoustic Sources Localization Using Propagator Method in Spherical Harmonic Domain

PAN Xi, TONG Ying， WANG Hua-yang

2018, 39(10):  1936-1944.  doi:10.3969/j.issn.1000-1093.2018.10.008

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In order to obtain the better direction of arrival (DOA) estimation and reduce the amount of computation for the wideband acoustic source under the condition of low signal-to-noise ratio, the ortho- gonal propagator algorithm is now applied to the spherical harmonic domain. Based on the establishment of a spherical array acoustic field model, two spherical harmonic propagator orientation algorithms are proposed, including the algorithm in which the spherical Fourier transform component is used to obtain the propagator and the algorithm in which the cross spectrum matrix with the spherical Fourier transform component is used to obtain the propagator. The frequency adaptation range of spherical arrays with different radii is analyzed, and the problem of multi-bandwidth acoustic source frequency adaptability is solved. The DOA estimation performances of the two algorithms and the spherical harmonic domain multiple signal classification algorithm under different SNRs are compared and analyzed. Acoustic source orientation experiments were performed, and the DOA estimation time of the three algorithms was test. Experiments show that both algorithms have the characteristics of small computation, less time and accurate orientation. Key

Extrapolation Algorithm Based on the Seven-state Inverse Unscented Kalman Filter

XIE Kai, QIN Peng-cheng

2018, 39(10):  1945-1950.  doi:10.3969/j.issn.1000-1093.2018.10.009

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An “inverse” unscented Kalman filter (UKF) algorithm with seven-dimensional state vector is proposed to solve the problems of low target positioning accuracy and poor fire direction ability of firefin-der radar. A state model is established by taking the ballistic coefficient as the state parameter and incorporating it into the filtering process. The UKF algorithm is used to improve the nonlinear estimation accuracy. The model error accumulates due to the long extrapolated distance of forward filtering. In the proposed algorithm, an inverse filtering is used, the first point measured by radar is used as the end point of the filter, and the artillery position is extrapolated using the fourth-order Runge-Kutta equation. The simulation results show that the proposed algorithm can effectively improve the extrapolation accuracy of artillery locating and fire correction radar. Key

Muzzle Blast Recognition Based on Multi-scale Subband Energy Set

XIE Meng-rui， ZHAO Zhao， LI Yang， XU Zhi-yong

2018, 39(10):  1951-1957.  doi:10.3969/j.issn.1000-1093.2018.10.010

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A recognition method based on a multi-scale subband energy feature set for muzzle blast is proposed to detect gunshot in real complicated acoustic environment. After muzzle blast signal is enhanced with a group of low-frequency subband filters, the muzzle blast detection followed by a crest search procedure is applied to determine the start position of candidate muzzle blast. Based on the start position, a set of nested data fragments with different lengths are segmented from the candidate muzzle blast and its subband components, and the short-time energies of data fragments and the corresponding energy ratios are then obtained to form the multi-scale subband energy set. The energy set is used as the feature vector for either support vector machine (SVM) or k-nearest neighbor (kNN) classifiers for the classification of muzzle blast and non-muzzle blast. The experimental results with 372 field recordings of gunshot demonstrate that both the precision and recall ratios of the proposed method are larger than 93%, and F1 score is better than 0.95. The proposed method shows less difference in recognition performances in using both SVM and kNN classifiers, with feature dimension and time consumption being much lower than those of the traditional wavelet-based means, indicating that it is more approaching practical applications. Key

Research on In-situ Superfine Dispersion of Water Soluble Oxidizer in Microporous Ball Propellant

MOU Ke-sai， GU Yong-jun， LIN Xiang-yang， ZHENG Wen-fang， PAN Ren-ming

2018, 39(10):  1958-1964.  doi:10.3969/j.issn.1000-1093.2018.10.011

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In order to explore the feasibility of in-situ superfine dispersion of water-soluble oxidizer in microporous ball propellant, the oxidizers with various concentrations are added to aqueous solution in the process of preparing the microporous ball propellant, which enables the oxidizers to disperse uniformly by filling them in the internal pores of ball propellant. Scanning electron microscope, X-ray diffraction and X-ray photo electron spectrometer are used to characterize the ball propellants which contain various oxidizers and dispersed oxidizer particulates. The result indicates that the micro-porous ball propellant which is filled with uniformly dispersed oxidizer particulates could be prepared by adding water-soluble oxidizers with concentration of less than 30%. The mean particle size is not greater than 3 μm. The fill rate of oxidizer in microporous ball propellant increases observably with the rising of oxidizer concentration. The superfine dispersion of water-soluble oxidizer in microporous ball propellant could be achieved by means of in-situ dispersing.Key

Solubility of Supercritical Carbon Dioxide in Oblate Spherical Propellants

WU Wen-long, DING Ya-jun, YING San-jiu

2018, 39(10):  1965-1970.  doi:10.3969/j.issn.1000-1093.2018.10.012

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In order to study the solubility of SC-CO₂ in double-base propellant, the dissolution and diffusion coefficients of SC-CO₂ in oblate spherical propellants with different arc thicknesses are investigated by the static method and the Fick diffusion law, and the effect of co-solvent on the amount of dissolution and diffusion coefficient is studied. The results show that the dissolved amount of SC-CO₂ in the double-base oblate spherical propellant increases with the increase in saturation time and is stabilized after 8 h, reaching 16%. It increases with the increase in saturation pressure. However, the dissolved amount of SC-CO₂ decreases with the increase in saturation temperature, and the dissolved amount is higher at 40 ℃. The addition of co-solvent has a positive effect on the increase in dissolved amount of SC-CO₂, and the dissolved amount is increased to 22.6%. The thickness of oblate spherical propellants has no effect on the saturated dissolved amount of SC-CO₂. The desorption diffusion coefficient under ambient conditions is much larger than the adsorption coefficient under supercritical conditions. The saturated dissolved amount of SC-CO₂ reaches 16% without adding co-solvent. After adding co-solvent, the saturated dissolved amount of SC-CO₂ reaches at least 22.6%, which is increased by 41.3%. The dissolution of SC-CO₂ in oblate spherical propellants can be increased effectively by adjusting the process parameters and adding the co-solvents. Key

Low Side-lobe Beam-forming Method Based on All-phase Preprocessing

ZHENG En-ming, CHEN Xin-hua, SONG Chun-nan

2018, 39(10):  1971-1978.  doi:10.3969/j.issn.1000-1093.2018.10.013

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In order to reduce the impacts of the side-lobe level and background noise due to conventional beam-forming on weak target detection, a low side-lobe beam-forming method based on all-phase preprocessing is proposed according to the features of the output value of directivity function on the direction of arrival (DOA) of target wave being 1 and the output value of directivity function being less than 1 on DOA of non-target wave. In the proposed method, the data received from linear array is divided into groups, the phase shift pretreatment for the data of each group is made based on the search angle, and then the results of phase shift pretreatment are combined to obtain a new set of data. The value of beam corresponding to the search angle can be obtained by phase shifting and summing of the new data. The theoretically analyzed, numerically simulated and experimental results show that the proposed method is used to make the phase shift treatment for the data of each group, thus changing the directivity function, improving the side-lobe level more than 13 dB and the signal to noise ratio by 1.7 dB, reducing the impacts of side-lobe level and background noise on weak target detection, and eliminating the phase inconsistency when the direction of arrival is unequal to search angle. The method improves the directivity function only by phase shift pretreatment for the data of sub-array.Key

Structral Design and Test of a New High Power Cam Piston Engine

XU Qin-chao, LI Shan-jun, LIAN Yong-qing, WANG Shu-zong

2018, 39(10):  1979-1987.  doi:10.3969/j.issn.1000-1093.2018.10.014

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A design scheme of a new cam engine with double crest cam and 7 cylinders is proposed to meet the power needs of a lightweight underwater vehicle. The structures and parameters of the main components in cam piston engine，such as cam，cylinder， valve mechanism and piston，are determined with considering the mechanical strength requirements. A prototype was manufactured. A test scheme was designed, and a test system was built. The performance of the prototype was tested, and the test results were analyzed. The test results show that the design scheme of high power cam piston engine is practicable, and the choice of engine materials is reasonable. The prototype is reliable in starting, and stable in operation. Shaft power of engine is up to 92 kW which achieves the goal of high power design.Key

Dynamics Performances of Polyurea-woven Fiberglass Mesh Composite Reinforced Steel Plate Subjected to Shock Waves

LIAO Yu, SHI Shao-qing, LIANG Chao-ke, WANG Wen-kang

2018, 39(10):  1988-1996.  doi:10.3969/j.issn.1000-1093.2018.10.015

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The technical measures of adding woven fiberglass meshes into the traditional pure polyurea reinforcing layer are proposed to improve the shock resistance of pure polyurea reinforced steel plate. FEM method is used to study the shock resistance of steel plates reinforced by pure polyurea and polyurea- woven fiberglass mesh composite reinforcing layers, respectively. The test results of large shock tube are used to verify the reliability of numerical simulation. The results show that the woven fiberglass meshes can be used to improve the reinforcing performance of pure polyurea reinforcing layer and reduce the overall deformation and kinetic energy of pure polyurea reinforced steel plate. In the range of allowable addition of woven fiberglass mesh layers, the peak kinetic energy of steel plate can be reduced by 28% by using the polyurea-woven glass fiber composite reinforcing layer compared with the pure polyurea reinforcing layer. The internal of energy in polyurea-woven glass fiber composite reinforcing layer can reach up to 2.75 times of that in the pure polyurea reinforcing layer with the same thickness. Key

Research on Laser Crack-precontrolling Technology for 50SiMnVB

SHI Yan, LIU Dong-wei, LIU Jia, LI Ling-yu

2018, 39(10):  1997-2005.  doi:10.3969/j.issn.1000-1093.2018.10.016

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The cracks in 50SiMnVB steel are experimentally controlled by using high power CO₂ laser to improve the processing efficiency and subsequent processing of fracture splitting groove. The laser deeper melting zone of micro-structure, fracture morphology and micro-hardness distribution are analyzed by means of metallographic microscope, scanning electron microscope and micro-hardness tester, respectively. The numerical simulation software SYSWELD is used to simulate the distributions of temperature field and stress field in 50SiMnVB steel during laser deeper melting. The results show that the hardened brittle cracks are generated in the deeper melting zone due to temperature and stress gradient. The cracking mechanism is that the pores and micro-cracks arise at the bottom of the deeper melting zone, and the cracks expand along the center to form the macroscopic cracks. The optimal range of processing parameters is obtained by the experiment and simulation with laser power of 3.0 kW, and scanning speed of 1.0- 4.5 m/min. The corresponding depth range of prefabricated crack is about 3-7 mm. Key

Analysis of Drum-shaped Instability of Spinning in Thinning of Thin-walled Cylindrical Part with Large Diameter-to-thicknessRatio

WEN Xue， TAN Jian-ping， LI Xin-he， LIU Su-qi

2018, 39(10):  2006-2015.  doi:10.3969/j.issn.1000-1093.2018.10.017

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In order to eleminate the spinning instability caused by drum-shaped instability in the spinning process of ultra-thin cylindrical parts, the key factors and laws affecting the stability are studied and determined on the basis of the analysis of the mechanism of drum type formation and instability. Combining with the characteristics of drum-shaped instability during the spinning of thin-walled cylinder, the boundary constraint, metal rheology and stress field in spinning contact area are analyzed to obtain the forming mechanisms of drum and mode-locked ring during spinning process. Based on the numerically simulated results of multiple sets of parameters, the influences of clearance between workpiece and mould, thinning rate, feed rate and diameter-to-thickness ratio on drum shape ratio and drum stiffness are analyzed, and the selection range of the corresponding parameters is determined by using the drum shape ratio and drum stiffness as the parameters of drum shape state. The spinning parameter adaptability and long-stroke spinning experiments of thin-walled cylinder with 2.00 mm in thickness and 398 mm in outer diameter were carried out on a three-roller spinning machine. After 3 passes of spinning, the wall thickness of the thin-walled cylinder was reduced from 2.00 mm to 0.53 mm, and its length was extended from 1 030 mm to more than 3 800 mm. Through the study of drum formation and influencing factors, it provides theoretical and experimental basis for the development of spinning parameters and long-range stability spinning of large-diameter ultra-thin cylindrical parts. Key

Comprehensive Review

A Review on the Study of Debris Cloud Produced by Normal Hypervelocity Impact upon a Thin Plate

DI De-ning, CHEN Xiao-wei,WEN Ken, ZHANG Chun-bo

2018, 39(10):  2016-2047.  doi:10.3969/j.issn.1000-1093.2018.10.018

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Debris cloud can be produced by hypervelocity impact of a projectile on a thin plate, which has been used in protection against meteoroid/orbital debris. The study of debris cloud during normal impact is reviewed to summarize the research progress and insufficiency in recent thirty years, including the formation process, distribution characteristic, modeling and penetration performance of debris cloud. According to the current lacks of research contents on debris cloud, some suggestions are also made for coming studies. Key

Research Notes

Comprehensive Evaluation Method for Combat Effectiveness of Machine Gun Considering Interval Uncertainty

YU Jun， MING Zhen-jun， YAN Yan， WANG Guo-xin， HUANG Jing

2018, 39(10):  2048-2055.  doi:10.3969/j.issn.1000-1093.2018.10.019

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A comprehensive-criterion-based machine gun design evaluation method in which interval-uncertainty is considered is proposed to address the incompleteness and uncertainty related to the indices for evaluating the combat effectiveness of machine gun designs. The initial indices for evaluating the combat effectiveness of machine gun designs based on interval number are established from the technical and tactical requirements of machine guns. Based on the interval uncertainty functions of the initial evaluation indices, the combined weights of the evaluation indices are determined using interval entropy method and analytic hierarchy process (AHP). Based on the grey relational analysis (GRA) method and the technique for order preference by similarity to an ideal solution (TOPSIS) in terms of interval numbers, the different machine gun designs are compared, and a gray correlation degree based on Euclidean distance is defined to characterize the similarity between the alternatives, thus effectively solving the problem of interval uncertainty. An example is given to demonstrate the effectiveness of the proposed method. Key

Optimization of Rotation Vector of Guided Projectile Attitude Based on Hermite Interpolation

DENG Zhi-hong, WANG Jin-wen, SHANG Jian-yu, ZHANG Xiang

2018, 39(10):  2056-2065.  doi:10.3969/j.issn.1000-1093.2018.10.020

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The angular incremental extraction accuracy has a significant effect on the attitude resolving accuracy in the attitude algorithm of guided projectiles. A Hermite interpolation-based extraction algorithm of two-sample angular increment is presented, and the coefficient of Hermite interpolation formula is optimized further. Then a Hermite interpolation algorithm for two-sample angular increment extraction is proposed. In the cone dynamic environment, the proposed algorithm is compared with the Lagrange interpolation three-sample angular increment extraction algorithm. The results show that the accuracy of attitude estimation using the proposed algorithm is better than that of Lagrange interpolation. The optimization of the Hermite interpolation is more suitable for the actual situation of guided projectile attitude algorithm. The algorithm not only adapts to the high dynamic environment of projectile, but also reduces the sampling frequency of attitude updating under the same precision condition and reduces the requirement of navigation computer. Key

Design and Research of the Fast Rise Time Electromagnetic Pulse Protection Module Based on PIN Diode

LI Ya-nan, TAN Zhi-liang

2018, 39(10):  2066-2072.  doi:10.3969/j.issn.1000-1093.2018.10.021

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The fast rise time electromagnetic pulse (FREMP) is an important cause of damage to electronic equipment, and the PIN diode can effectively suppress electromagnetic pulse. In order to investigate the transient response of PIN diodes to FREMP, a time-domain equivalent circuit model based on PIN diodes is adopted. And the transient voltage characteristic of PIN diode circuit under the effect of FREMP is analyzed. Considering the parasitic components of PIN diodes and the bonding wire inductance, the whole physical structure of FREMP protection module is set up based on Butterworth low pass filter model. A FREMP protection module is realized. The measured insertion loss of protection module is lower than 0.38 dB in 1-250 MHz. At large signal condition with input square wave pulse of 4 000 V, the response time is less than 2 ns and the output level is lower than 30 V, which meets the protection requirement of FREMP. Key

Optimization of Laser Cladding Process Parameters of 35CrMoV Piston Rod Based on Grey Correlation Analysis

ZHAO Dan-dan, JIAO Feng

2018, 39(10):  2073-2080.  doi:10.3969/j.issn.1000-1093.2018.10.022

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The laser cladding technology for repairing the worn surface of substrate with 35CrMoV is studied to optimize reasonably the laser cladding process parameter and obtain the cladding layer with excellent compactness and stronger abrasion resistance. The experimental data are processed on the basis of the theoretical model of grey system and the orthogonal test data, of which the scanning speed, laser power and speed of powder delivery are variable. The analytic hierarchy method is used to calculate the multi-target weight, and the grey correlation theory is used to calculate the correlation coefficient of each process parameter for the ideal single target value and the correlation degree to the multiple target value. Single target parameter optimization is converted to the integrate parameter optimization. The scanning line speed is 100 mm/s, the powder delivery speed is 42.8 g/min, and the laser power is 1.8 kW. The optimized results are verified experimentaly. The research shows that, under the the condition of optimal process parameters, the quality of cladding layer is obviously improved, and the wear resistance is increased by 43%. Key