Table of Content

31 March 2016, Volume 37 Issue 3

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Paper

Analysis of Dynamic Matching Factors of High-power Diesel Engine and Hydrodynamic Torque Converter

LIU Shu-cheng, YAN Qing-dong, XING Qing-kun

2016, 37(3):  385-393.  doi:10.3969/j.issn.1000-1093.2016.03.001

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In order to study the dynamic matching of hydrodynamic transmission system for armored vehicles, the influence factors of the dynamic matching of high-power diesel engine and hydrodynamic torque converter are analyzed. The reasonable definitions of dynamic matching power and economic indexes of the system consisting of diesel engine and hydrodynamic torque converter are given. A calculation program for dynamic matching performance of diesel engine and hydrodynamic torque converter is established by combining the neural network model of diesel engine based on finite test data with computational fluid dynamics simulation model of converter based on the hybrid flow channel method. The structural factors of influencing the matching performance are analyzed through design of experiment, and the main effect and interaction effect of which the effective diameter of converter and the intermediate drive ratio affect the matching performance are obtained. The influences of throttle opening and torque converter’s locking ratio on the optimal dynamic matching region are also analyzed. The results show that the structural factors are the main factors which affect the dynamic matching performance, and the application factors are the relative secondary factors. However, the application factors can cause a change in the location of optimal matching region and the values of optimal indexes to a certain extent.

Analysis of Indicated Work Effect Factors of Hydraulic Free-piston Diesel Engine

ZHANG Shuan-lu， ZHAO Chang-lu， ZHONG Ke, ZHAO Zhen-feng

2016, 37(3):  394-399.  doi:10.3969/j.issn.1000-1093.2016.03.002

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The force applied on piston during the compression and expansion stroke is analyzed based on the experimental bench of a two-stroke single-piston hydraulic free-piston diesel engine (HFPDE) prototype. The main factors of affecting the indicated work of HFPDE are obtained, such as fuel-injection quantity, piston position at the beginning of fuel injection, and opening moment of exhausts valve. In order to analyze the effects of the factors on the indicated work of HFPDE, the effects of different fuel injection moments and fuel-injection quantity on cyclic indicated work are analyzed. It turned out that the effect of starting moment of fuel injection on the indicated work derives from the fluctuation in piston velocity during compression stroke. The effect of fuel-injection quantity on the indicated work behaves as the fluctuation of top dead center at the working pressure of 25 MPa. The effects of different opening moments of exhaust valve on the indicated work of HFPDE are analyzed. It is found that the earlier opening of exhaust valve leads to lower mean indicated effective pressure, resulting in the reduction in thermal efficiency.

Optimization Design of Blade Top Arcs of Dual Torus Hydrodynamic Retarder

MU Hong-bin, WEI Wei， YAN Qing-dong， LIU Cheng

2016, 37(3):  400-407.  doi:10.3969/j.issn.1000-1093.2016.03.003

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In order to improve the braking efficiency of dual torus hydrodynamic retarder, the parameter optimization design of blade top arcs is studied. A numerical model of internal flow passage is established based on the parametric modeling method of blade top arcs. The computational fluid dynamics method is used for design of experiments with the radius and distance of blade top arcs as design variables, and the sensitivity analysis of two parameters having the effect on brake performance is made. A gradient optimization algorithm is used to get the optimum result by building an approximate model of braking torque. The influence of design parameters on internal flow field and external brake performance is analyzed, and the simulated results are compared with the experimental data. The results show that the brake performance of hydrodynamic retarder after optimization is significantly improved, the braking torque is increased by 70.8%, and the blade structure meets the strength requirement.

New Method of Dynamic Flight Simulation Experiment for Anti-aircraft Weapon

DING Tian-bao， YANG Dong， HE Zhao， WANG Kun

2016, 37(3):  408-413.  doi:10.3969/j.issn.1000-1093.2016.03.004

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A new principle of dynamic flight simulation experiment for anti-aircraft weapon is presented for the simulation experiment of anti-aircraft weapon in laboratory. A mathematical model of obtaining the tagart truth values and a mathematical model of obtaining the truth values of pitch and roll positions of tracker are established. The dynamic flight simulation experiment principle and the mathematical models are verified through dynamic flight simulation experiment. The principle and the key technologies of simulating dynamic flight experiment are valuable for dynamic flight simulation experiment of anti-aircraft weapons, which will promote the research and development of new anti-aircraft weapons. The proposed method is used to establish the theoretical basis of the dynamic flying experimental system, which can be used for data processing and error analysis.

Initial Thermal Decomposition of TNT/C₁₀H₈ Cocrystal: Reactive Molecular Dynamics Simulations

LIU Hai, HE Yuan-hang

2016, 37(3):  414-423.  doi:10.3969/j.issn.1000-1093.2016.03.005

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The discussion of shock initiation and detonation with ReaxFF reactive force field has centered nearly around conventional energetic materials. The comprehensive molecular dynamics of thermal decomposition of condensed phase TNT/C₁₀H₈ cocrystal with the ReaxFF/lg potential function are studied, which adds a long range correction term to the total energy expression of original ReaxFF. The thermal decomposition of TNT single crystal is performed similarly to determine the main effect of C₁₀H₈ on the overall thermal characteristics of cocrystal. Furthermore, the activation energies associated with endothermic and exothermic stages of cocrystal thermal decomposition are found to be 35.7 kcal/mol and 56.1 kcal/mol, respectively. Its activation energy at primary endothermic stage is compatible with that of TNT single crystal, but the activation energy at secondary exothermic stage is higher than the value calculated for TNT. In addition, the heat output calculated during the exothermic step of TNT/C₁₀H₈ cocrystal is less than that of TNT at the same temperature. The decay rate of reactants by curve fitting shows that C₁₀H₈ inhibits the decomposition of TNT in cocrystal. NO₂, NO and HONO are major primary decomposition products by the way of identification analysis. The distribution of NO₂ /TNT_—NO2, NO/TNT_—NO, HONO/TNT_—HONO shows that the decomposition proceeds via bimolecular reaction. Main final products of cocrystal are N₂,H₂O,CO₂, and CO, and the initial decomposition routes of C₁₀H₈ is C—H bond dissociation as a result of C—C bond dissociation energy of C₁₀H₈ in cocrystal is higher than C—H bond, and this process may promote the formation of H₂O.

Effect of Functional Agents on the Performance of 2， 4-dinitroanisole-based Melt-cast Explosives

MENG Jun-jiong， JIANG Zhen-ming， ZHANG Xiang-rong， ZHOU Lin

2016, 37(3):  424-430.  doi:10.3969/j.issn.1000-1093.2016.03.006

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In order to obtain the system of functional agents for 2,4-dinitroanisole（DNAN）-based melt-cast explosives and improve the performance of its charge, Tween 60 and cellulose acetate butyrate（CAB）are chosen as the preferred agents according to the calculated works of adhesion. The influences of functional agents on tensile strength, shear strength, impact sensitivity, friction sensitivity, shock sensitivity and charge density of DNAN 20/HMX 80 melt-cast explosive are analyzed by using Brazil test, static shear test, determination of friction sensitivity-explosion probability method, determination of impact sensitivity-explosion probability method, small scale gap test and hydrostatic weighing method. The results show that, when 1wt% Tween 60 and 1wt% CAB are added in DNAN 20/HMX 80 melt-cast explosive, its tensile strength is increased by 6.25%，10.3% and 47.8% at -40 ℃, 20 ℃ and 60 ℃, respectively; its shear strength are increased by 23.5%，27.8% and 45.1% at -40 ℃, 20 ℃ and 60 ℃, respectively；its friction sensitivity, impact sensitivity and shock sensitivity are decreased by 14.29%, 4.76% and 3.11%, respectively；and its relative density is increased by 0.2%. Therefore, Tween 60 and CAB can be used to improve the mechanical properties and safety performance of DNAN-based melt-cast explosives.

Cooperative Guidance Law with Impact Angle and Impact Time Constraints for Networked Missiles

ZHANG Chun-yan, SONG Jian-mei, HOU Bo, ZHANG Min-qiang

2016, 37(3):  431-438.  doi:10.3969/j.issn.1000-1093.2016.03.007

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Cooperative biased proportional guidance law with impact angle and impact time constraints is presented for cooperative attack of networked missiles. The biased proportional guidance law with impact angle constraints is proposed, and the expression of time-to-go in this guidance law is deduced. The proportional coefficient is adjusted by the difference of the time-to-go of each missile in the network. And the cooperative biased proportional guidance law with impact angle and impact time constraints is presented. It is proved theoretically that the multiple missiles trend to have the same time-to-go by the guidance law. Finally, the mathematical simulation of guidance system of networked missiles illustrates the validity of the proposed guidance law and the expression of time-to-go.

Application of Rotating Vector in Equations of Motion for All-attitude Aircrafts

WANG Hong-hui， YANG Shao-qing， WU Cheng-fu， HAO Feng, CHE Xiao-tao

2016, 37(3):  439-446.  doi:10.3969/j.issn.1000-1093.2016.03.008

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A mathematical framework to apply a rotation vector in the equations of motion for all-attitude aircrafts is established based on the basic idea of that the rotation vector is to express an equivalent rotation corresponding to the change in angular position rather than the angular position. This idea is stimulated by the rotating vector in the strapdown attitude algorithm. The rotation vector method is available for all-attitude solution while the Euler angle method is not. Meanwhile, compared with the quaternion method, the rotation vector method can improve the efficiency of attitude solution. The non-commutative errors in the rotation vector method, the quaternion method and the Euler angle method are analyzed in detail. A rotation vector method based on the quasi-body frame is developed to improve the efficiency of attitude solution for axial-symmetry aircrafts of which a single channel has high dynamic characteristics. The digital simulations based on the equations of motion for some rolling missile show the effectiveness and generality of the rotation vector method.

Experimental Simulation of Aerosol Source Term of Surrogate Plutonium Produced by High-explosive Detonation

LIU Wen-jie， MA Qing-peng， TIAN Li-zhi， WANG Peng-lai

2016, 37(3):  447-454.  doi:10.3969/j.issn.1000-1093.2016.03.009

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An experimental method is developed to simulate the plutonium aerosol source term in the circumstance of high-explosive detonation with ordinary surrogate metals on an aerosol test facility consisting of a confinement vessel and a non-viable aerosol sizing sampler. Five kinds of metals, including silver (Ag), tungsten (W), tin (Sn), cerium (Ce) and vanadium (V), are detonated in confinement vessel. Aerosol samples with aerodynamic diameter of smaller than 10 μm are collected. The cumulative mass and size distribution of each metal aerosolized in experiment are investigated and compared to the plutonium aerosol source term obtained from operation roller coaster-double tracks experiment of USA. The results show that the silver aerosol can simulate the plutonium aerosol source term in the laboratory environment, of which the cumulative mass distribution is in good agreement with that of plutonium, while the aerosol source terms of other four metals are quite different from that of plutonium. Two samples of the silver aerosol in confinement vessel are collected at different time after detonation, which are compared based on energy spectrum analysis and scanning electron microscope characterization. A solid sample on the bottom of confinement vessel is also collected, and the scanning electron microscope method is used to analyze the size distribution of the sediments. The results show that the AD of silver aerosol obtained just after detonation is in the range from 1.1 μm to 2.1 μm, while the aerosol size is larger for the late sample, suggesting that settlement and combination of the silver aerosol take place with time in confinement vessel.

Effect of Turbulence on Explosion Characteristics of Aluminum Dust/Air

SHEN Shi-lei, ZHANG Qi, MA Qiu-ju, LI Dong, YAN Hua

2016, 37(3):  455-461.  doi:10.3969/j.issn.1000-1093.2016.03.010

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The dispersion and explosion processes of aluminum dust in 20 L spherical confined chamber are numerically simulated based on computational fluid dynamics theory. The influence of turbulence intensity on the explosion characteristics of aluminum dusts with different concentrations at various ignition delay times is studied. The results indicate that the ignition delay time has a significant effect on maximum explosion pressure and maximum rate of pressure rise of aluminum dust explosion, and there exists an optimum ignition delay time for p_max. With the increase in the concentration of aluminum dust in the chamber, the optimum ignition delay time increases first and then remains unchanged, therefore a single ignition delay time cannot accurately reflect the explosion powers of aluminum dusts with different concentrations. Both turbulence intensity and distribution of dust cloud have the influences on maximum explosion pressure and maximum rate of pressure rise. The uniformity of dust distribution has a greater effect on maximum explosion pressure than the turbulence intensity, while the turbulence intensity has a greater effect on maximum rate of pressure rise than the uniformity of dust distribution.

Parameter Estimation of Unknown Envelope Multicomponent LFM Signal

XU Zhou, ZHANG Hao, CHENG Shui-ying

2016, 37(3):  462-470.  doi:10.3969/j.issn.1000-1093.2016.03.011

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For the estimation of unknown envelope multicomponent linear frequency modulation(LFM) signal in radar reconnaissance, the methods for the estimation of pulse number, frequency modulation rate, center frequency, delay and pulse width are proposed based on time-frequency analysis and coherent accumulation. A rough estimation is done for the parameters of pulse number as well as frequency modulation rate by time-frequency analysis, after which a fine estimation is conducted based on fractional Fourier transform(FRFT). Then some parameters, such as center pulse, delay and pulse width, can be extracted by coherent accumulation. Simulation results show that the weak pulse parameters estimation may be affected by strong pulse, which can be solved by filtering in FRFT domain. At last, Cramer-Rao low bounds of parameters are derived, and the estimation errors of parameters are analyzed. Results show that the estimation accuracy of width of weak pulse can be improved significantly after strong pulse filtering.

Trajectory Tracking Control of an Underactuated Unmanned Marine Vehicle Based on Asymmetric Model

DONG Zao-peng， WAN Lei， SUN Yu-shan， LIU Tao， LI Yue-ming， ZHANG Guo-cheng

2016, 37(3):  471-481.  doi:10.3969/j.issn.1000-1093.2016.03.012

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Trajectory tracking control problem of an underactuated unmanned marine vehicle (UMV) is addressed, and an integral backstepping control method based on asymmetric model is proposed. A horizontal motion model of incomplete symmetry underactuated UMV with port/starboard symmetry and without fore/aft symmetry is established, in which the off-diagonal elements of damping coefficient matrix and inertia coefficient matrix are considered to be non-zero. A feedback transformation of virtual state and control input is designed to relax the well-known persistent exciting conditions of yaw velocity in trajectory tracking control of UMV, and then a general trajectory tracking controller for both straight line path and curve path is obtained. The global stable convergence rate of UMV system is improved by introducing an integral item of tracking errors into trajectory tracking controller. The stability of the system is proved by Lyapunov theory and Barbalat’s lemma. With the help of the semi physical simulation platform, the advantages of the asymmetric model-based underactuated UMV trajectory tracking control method proposed in this paper is demonstrated in simulation experiments by comparing with the traditional symmetric model-based method.

A Detecting Test of Seismic Waves Caused by Random Ships in Shallow Water with Sandy Bottom

LU Zai-hua, ZHANG Zhi-hong, GU Jian-nong

2016, 37(3):  482-488.  doi:10.3969/j.issn.1000-1093.2016.03.013

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Elastic wave in the seabed caused by low frequency noise radiated from ship is a so-called ship-induced seismic wave which can be used to identify the ship target in shallow sea. In order to investigate the detecting range and signal feature of ship-induced seismic wave in shallow sea with thick sandy bottom, a detecting test of seismic waves caused by random ships in inland river with thick sandy bottom is carried out with a three-component seismometer for weak seismic wave detection. The seismic waves caused by several random ships are obtained. According to the calculated time-frequency spectrum of the seismic waves, the propagation characteristics of seismic waves caused by ships in shallow water with thick sandy bottom are analyzed. The vertical component of seismic wave can propagate to a far distance compared with the horizontal component. The signal received by seismometer in far field is mainly caused by the noise radiated from the propeller because the line spectrum of the detected signal is almost the same as that of the propeller and always has a double frequency of the propeller's rotation frequency. The detecting ranges of most random ships are above 1 km based on the line spectrum of propeller.

Signal Processing of Laser Screen Fragments Velocity Measurement Based on Wavelet Transform and Correlation Analysis

ZHANG Bin, LI Jia-lu, ZHAO Dong-e, LIU Ji, LI Yuan, SHI Xiao-jun

2016, 37(3):  489-495.  doi:10.3969/j.issn.1000-1093.2016.03.014

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A signal processing method based on the automatic identification algorithm for wavelet transform and correlation analysis is proposed for the large fluctuation noise and the impossible automatic discrimination of the laser screen warhead fragment velocity measuring signals. The proposed method removes the noises from the original signals by using the multi-resolution analysis and band-pass filtering of discrete waveform transform and the wavelet threshold denoising method. The time of the fragment flying through the laser screen can be obtained by the peak detection. And the automatic waveform identification of the same fragment is realized according to the correlation analysis of the signals of the same fragment flying through two laser screens. Twelve groups of the collected waveforms are processed. The results show that the proposed algorithm can remove the noises perfectly, 96.9% of recognition rate of fragments can be achieved, and the automatic identification rate of the corresponding waveform of the same fragment is 87.2%.

Research on Optimization of Two-dimensional Imperfect Preventive Maintenance Intervals of Products

HAN Yu-cheng, JIA Xi-sheng, BAI Yong-sheng, LI Xin-yue

2016, 37(3):  496-504.  doi:10.3969/j.issn.1000-1093.2016.03.015

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For the products of which the failures are affected by the calendar time and service time, the traditional one-dimensional preventive maintenance can’t meet the actual demand. A concept of two-dimensional preventive maintenance is proposed. The two-dimensional preventive maintenance decision is made according to calendar time and service time. A failure rate function expression of two-dimensional maintenance is established, and the process of two-dimensional imperfect preventive maintenance is analyzed in detail. A cost model of two-dimensional imperfect preventive maintenance is proposed to minimize the consumer’s total expected cost in finite life span. An optimal two-dimensional imperfect preventive maintenance interval is derived through examples, and the the applicability and validity of the proposed model are verified through comparison and analysis. A brief discussion about future research area of two-dimensional maintenance is presented.

Reliability Assessment for Device with Only Safe-or-failure Pattern Based on Bayesian Hyprid Prior Approach

ZHANG Wen-jie， YANG Hua-bo， ZHANG Shi-feng

2016, 37(3):  505-511.  doi:10.3969/j.issn.1000-1093.2016.03.016

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For the reliability evaluation of device with only safe-or-failure pattern, a hyprid prior approach is introduced, and the posteriori probability distribution function of reliability parameter is deduced by Bayesian method. The influence of prior distribution parameters on the posterior estimation is considered, and the general rules of choosing these parameters are summarized. The parameter posterior estimates of traditional Bayesian method and hyprid prior approach are compared. The results indicate that the hyprid prior approach can avoid the problem of that the prior data inundate the posteriori data effectively. The analysis of posteriori mean square error demonstrates that the hyprid prior approach can improve the performance of estimation to some extent. Through the comparison with power prior approach, it is proved that the estimation effect of hyprid prior approach is better than that of power prior approach, especially when prior sample size is larger.

Ground Robot Multi-scale Road Perception Based on Semantic Tree MRF Model

DU Ming-fang, WANG Jun-zheng, LI Duo-yang, HE Yu-dong

2016, 37(3):  512-517.  doi:10.3969/j.issn.1000-1093.2016.03.017

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Road real-time perception is the key technology of autonomous ground mobile robot to realize autonomous navigation. But it is difficult to develop a road sensing algorithm because of the complexity and uncertainty of outdoor road environment. A multi-scale biomimetic road sensing algorithm in wavelet domain based on semantic tree Markov model is proposed. In time-space domain, the three-dimensional random field is used to express the road image sequence collected by robot. A road model named road best tree-Markov random field (RT-MRF) using the semantic tree structure Markov random field (MRF) is proposed. The genetic algorithm is used to optimize the supervised RT-MRF model for image segmentation of road sequences. The road recognition and autonomous navigation are realized through tracking segmentation boundary. An independently developed quadruped bionic robot is used as the research and experiment platform. The experimental results show that the proposed algorithm is a robust road image sequence segmentation method, which can be used under the poor detection conditions, such as shadow, cracks, holes, uneven and illumination change. And the real time of the algorithm is enough high to meet the demand of outdoor mobile robot autonomous navigation.

Numerical Prediction of Heat transfer Characteristics of Rotating Multi-connected Internal Cooling Channels

LI Xiang-yang, CHEN Wan-qiang, ZHAO Shu, DU Jian-hong, MI Guo-ji, WANG Wei, QING Lyu-jun

2016, 37(3):  518-524.  doi:10.3969/j.issn.1000-1093.2016.03.018

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To better understand the effect of rotation on the heat transfer characteristics of internal channels, the flow and heat transfer in an internal channel with 90° ribs are investigated using three-dimensional numerical simulation method. The Reynolds number of channel inlet is 17 000, and the mass flow rates of three outlets are 25%, 50%, and 25%, respectively. The rotating number and the hydraulic diameter divided by radius of gyration range from 0 to 0.09 and 0 to 69.6, respectively. The influences of rotation number and radius of gyration on heat transfer coefficient are achieved. Results show that the pressure coefficient increases along radial outflow and decreases along radial inflow due to rotational force. In the trailing surface, Nusselt number (Nu) in radial outflow passages increases and Nu number in radial inflow passage decreases with the augment of the rotation number. The variation of Nu in the leading surface is contrary to that of the trailing surface. The Nu numbers along the flow direction in trailing and leading surfaces are slightly enhanced when the ratio of gyration radius to hydraulic diameter increases. The surface heat transfer coefficient is affected by the variable radius of gyration.

Comprehensive Review

Research Progress in Inerter and Inerter-spring-damper Suspension

MAO Ming， WANG Le， CHEN Yi-jie， LEI Qiang-shun， DU Fu

2016, 37(3):  525-534.  doi:10.3969/j.issn.1000-1093.2016.03.019

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The appearance of inerter and its device greatly promote the development of electrical and mechanical analogy and inerter-spring-damper（ISD）suspension. The concept, background and characteristics of the inerter and ISD suspension are introduced. The structure types, dynamics, frequency responses, nonlinear characteristics and breakdown phenomena of the existing inerters at home and abroad are described. The research progress of ISD suspension are systematically explained by summarizing its structure types, performance, network synthesis theory and application, layout and integrated design. Five aspects of future application of inerter and ISD suspension, including innovative design of inerter, inerter nonlinear research, ISD suspension network synthesis, application and integrated design of ISD suspension, are presented.

Research Notes

Experimental Study of Internal Excitation and Vibration of an Integrated Transmission Device

ZHANG Xiao-ping， WANG Yu-lin， DU Ming-gang， YANG Yang

2016, 37(3):  535-540.  doi:10.3969/j.issn.1000-1093.2016.03.020

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The life and reliability of integrated transmission device may be significantly affected by the vibration, harshness and quality of the device. The relationship between the internal excitation and vibration of the device is one of the important research works. An experimental scheme is presented to obtain the relationship between the internal excitation and vibrations of an integrated transmission device. A coupling signal analysis method is also proposed to investigate the signals from the multiple measurement points and experimental conditions. The relationship between the internal excitation and vibration of the device is obtained based on the proposed experimental method, which can provide some guidance for the structure optimization of the device. The results show that the experimental analysis method can be used to not only determine the vibration source location of the integrated transmission device, but also find the dominant frequency which should be controled, which can provide some guidance for the structure optimization of the device.

Research on the Influence of Linear Vibration of a Tank Chassis on On-the-move Shooting Accuracy

WANG Guo-sheng, YAO Ling-yu, WEI Lai-sheng, PIAO Yan, GU Liang

2016, 37(3):  541-546.  doi:10.3969/j.issn.1000-1093.2016.03.021

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Three factors leading to the lower shooting accuracy for a tank moving at a high speed are analyzed based on the linear vibration of its chassis. The efects of the factors on the shooting accuracy are studied from the real test data. The research result shows that the lateral shooting deviation caused by the linear vibration of chassis is too small to reduce the shooting accuracy significantly. Although the linear vibration of chassis has some impact on the imaging quality of sighting telescope, it basically does not affect the sighting effect. Since the linear vibration of crew seat is larger and its ride comfort is poor, it is hard for the crew in the tank to precisely manipulate the sighting telescope, and then the sighting effect would be affected. Therefore, the influence of the linear vibration of tank chassis on the shooting accuracy is mainly through its impact on the ride comfort, and the ride comfort is an important reason of affecting on-the-move shooting accuracy.

The Preparation of Sub-micron Spherical Phloroglucinol-Fe and Its Effects on Thermal Decomposition of Hexanitrohexaazaisowurtzitane

SONG Nai-meng, ZHANG Tong-lai, GAO Hong-xu, YANG Li

2016, 37(3):  547-552.  doi:10.3969/j.issn.1000-1093.2016.03.022

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Sub-micron spherical phloroglucinol-Fe is prepared by spray drying. The morphology, particle size and composition of products are characterized by using TG-DSC, SEM and FTIR. The effect of phloroglucinol-Fe on thermal decomposition and kinetic parameter of hexanitroheraazaisowurtyzitane (CL-20) is studied by means of DSC. The research results show that the products are spherical and diffusive. Particle size is in the range from 500 nm to 1 000 nm. The product can obviously promote the decomposition performance of CL-20 so that the first decomposition peak temperature is shifted 15.1 ℃ ahead. The activation energy of CL-20/ phloroglucinol-Fe is increased by 81.4 kJ/mol compared with CL-20.

Experimental Demonstration of Underwater Acoustic Communication Based on Bidirectional Decision Feedback Equalizer

HAN Xiao， SHENG Xue-li， YIN Jing-wei， LIU Bing

2016, 37(3):  553-558.  doi:10.3969/j.issn.1000-1093.2016.03.023

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A robust single carrier underwater acoustic communication system is designed by combining bidirectional decision feedback equalizer (DFE) with passive time reversal mirror (PTRM). At the receiver, PTRM is used to suppress the multipath spread and focus the signal energy. And then the bidirectional DFE is used to combine the outputs from the traditional DFE and the backward DFE, decreasing the errors brought by a wrong decision and improving the robustness of traditional DFE. The data processing results from a shallow water experiment in underwater acoustic channel stable environment show that the bidirectional DFE could get some processing gain, and the output signal-to-noise ratios are increased by 2.74 dB, 2.36 dB, and 1.54 dB at 5 km, 7 km, and 10 km, respectively. The decoding performance is effectively improved compared with the traditional DFE.

Modeling Technology of Camouflage Screen Target Characteristics Based on SAR Images

PANG Hai-yang， WANG Yan-fei， ZHANG Jian

2016, 37(3):  559-564.  doi:10.3969/j.issn.1000-1093.2016.03.024

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A camouflage target characteristic model is lack for the threat of high resolution polarimetric synthetic aperture radar (SAR). The characteristic parameters of SAR images are chosen to set up the feature vectors. On this basis, the quadrant coordinate system and the coefficient of variation are used to analyze the regular pattern between polarization mode and characteristic parameter, establish the relations of parameter value and stability, and implement the qualitative description of camouflage screen target characteristic model. The research results show that the feature vectors can characterize different targets. The proposed model can be used to analyze and predict the characteristics of camouflage screen target, which lays a foundation for camouflage target detection and camouflage effectiveness evaluation.

Bayesian Acceptance Test Scheme for Reliability of Binomial Products

LIU Hai-tao, ZHANG Zhi-hua, DONG Li

2016, 37(3):  565-569.  doi:10.3969/j.issn.1000-1093.2016.03.025

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For the acceptance test of binominal products in the production definition phase, an information transition model for type approval phase and batch production phase is established using competition-failure method in order to properly use the prior information of the type approval phase. The prior distribution of batch products’ reliability is presented. On this basis, the calculation method of posterior distribution and risk is given, and a Bayesian acceptance test scheme is proposed. The experimental results show that the proposed method can be used to enormously reduce the acceptance test, and has preferable stability.

Effect of Additive on Performance of On-board Hydrogen Generator with Different Mass Fractions of KOH Liquor

JI Chang-wei, FENG Yu, WANG Shuo-feng, ZHANG Bo, XU Pu-yan, YU Meng-hui

2016, 37(3):  570-576.  doi:10.3969/j.issn.1000-1093.2016.03.026

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In view of the low efficiency of on-board hydrogen generator used in the vehicle with hydrogen-blended gasoline engine, the effect of additive on the performance of on-board hydrogen generator with different mass fractions of KOH liquor is tested on a hydrogen generator testing bench. The experiment is carried out under the conditions of electrolytic current of 40 A, initial temperature of 23.7 ℃ and initial pressure of 0.1 MPa. The mass fractions of KOH are kept at 20%, 30% and 40% in the KOH liquor. For each KOH mass fraction, the effect of addition of 0.3 g K₂Cr₂O₇ on the electrolytic voltage and hydrogen production efficiency is investigated. The experimental results indicate that, when 20%, 30% and 40% KOH liquors are added into K₂Cr₂O₇, respectively, the electrolytic voltages are reduced by 0.16 V, 0.19 V and 0.09 V, the hydrogen efficiencies are increased by 2.14%, 2.78% and 1.46%, respectively, and the hydrogen efficiency ratios are increased by 5.23%,6.71% and 3.47%. The hydrogen production efficiency is effectively increased by adding 30% KOH liquor into K₂Cr₂O₇.