Table of Content

01 October 2012, Volume 33 Issue 10

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Paper

Study on Nonlinear Vibration Behavior of Simple Single Stage Planetary Gears in Multiple Work Conditions

LIU Hui, CAI Zhong-chang, ZHU Li-jun, XIANG Chang-le, HUO Chun-jing

2012, 33(10):  1153-1161.  doi:10.3969/j.issn.1000-1093.2012.10.001

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A nonlinear simple single stage planetary gears dynamic model that contained multiple backlashes and multiple time-varying parameters was established, wherein the backlash, time-varying mesh stiffness and its engaging phase difference, gear mesh composite errors and time-varying planet position angle were considered. According to different input rotational speed and torque, operational terms were categorized into four work conditions. The vibration behaviors were described in detail by frequency spectrum, dynamic load coefficient and load sharing coefficient. The results demonstrate that the changes of nonlinear vibration behaviors represent diverse characteristics in different work conditions. The change of nonlinear behavior that is generated by ascending rotational speed worsens vibration more clearly in light load condition than heavy load condition. At the same time, the change that is brought by increased load improves vibration more obviously in high speed state than low speed state. The change of nonlinear behavior is staged similar in frequency spectrum, each vibration characteristic parameters also have staged similar character that is consistent with frequency spectrum. It provides reference for the design of planetary gears in complicated work conditions.

Design of Hydrogen Enriched Compressed Natural Gas Engine Fuel System and Test Research

ZHANG Chao-shan， XIONG Shu-sheng， REN Xiao-shuai， YAO Hong，

2012, 33(10):  1162-1167.  doi:10.3969/j.issn.1000-1093.2012.10.002

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This paper put forward a device installed into the fuel system, which used the sliding electric arc to electrolyze the natural gas to make hydrogen and then blend them into the fuel pipe for final combustion. We could re-equip the compressed natural gas (CNG) engine to hydrogen enriched compressed natural gas (HCNG) engine easily. The test research of the engine emissions characteristics using different hydrogen-CNG ratios was conducted when the excess air ratios and the spark advance angles were different. The results show that HC and CO emissions of engine fueled with HCNG reduce when NOx emissions increase. The NOx emissions are reduced greatly with the increase of the excess air ratio or the decrease of the spark advance angle. Comparative experiments of the performance characteristics of engine burned with HCNG whose volume hydrogen-CNG ratio was 20% and CNG were conducted under wide open throttle operating conditions. The results show that the torque output is unchanged when 20%HCNG is burned compared with CNG engine, but the fuel consumption is reduced and the fuel economy is improved.

Semi-analytic Solution of Nature Frequency of Transverse Vibration of a Barrel

CHEN Guang-song， QIAN Lin-fang， XU Ya-dong， CHEN Long-miao

2012, 33(10):  1168-1172.  doi:10.3969/j.issn.1000-1093.2012.10.003

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To obtain more accurate result of transverse natural vibration of barrel, a barrel was simplified to several segments of Timoshenko beams with variable cross-sections in consideration of the shear distortion and the moment of inertia, establishing the transverse vibration equations. The Chebyshev orthogonal polynomial was applied to deploy the differential equations. As a result, a set of transverse nature vibration equations of the barrel was obtained by assembling the boundary and collection equations. The natural vibration characteristic of barrel with variable cross-section was got by solving the equations. The results of numerical examples show that the method is effective, accurate, and could adapt to various boundary conditions.

Preparation and Mechanical Properties of Cellulose Nanowhisker/Nitrocellulose Nanocomposites

WANG Wen-jun， FENG Lei， SHAO Zi-qiang， WANG Fei-jun， LI Yong-hong

2012, 33(10):  1173-1177.  doi:10.3969/j.issn.1000-1093.2012.10.004

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A simple chemical modification route was demonstrated using cellulose nanowhiskers (CNW) prepared by sulfuric acid hydrolysis as raw material and a mixture of nitric acid and dichloromethane as nitrification agent. The bulk degree of substitution (DS) of modified CNW was quantified by elemental analysis. The structure of modified CNW was analyzed by FT-IR and X-ray diffraction. The modified CNW can be well dispersed readily in solvents with low polarity, such as acetone, and retain their original integrity and size. Nitrocellulose nanocomposite films with different CNW contents were processed by solution casting. The tensile strength, modulus and strain at break of the nanocomposites filled with 2.0%，3.5%，5.0% and 7.0wt% modified CNWs are improved compared to the neat matrix. The tensile strength, modulus and elongation at break of the composite film filled with 3.5wt% CNW are increased by 21.7%, 32.7% and 123.6%, respectively.

An Improved Isometric Mapping Algorithm Based on New Geodesic Distance and Its Application in theFeature Extraction of Acoustic Targets

LIU Hui, YANG Jun-an, WANG Yi, CAI Xue-liang

2012, 33(10):  1178-1184.  doi:10.3969/j.issn.1000-1093.2012.10.005

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A drawback of the isometric mapping (ISOMAP) algorithm is topological instability, that is, the algorithm is sensitive to the noise, which makes ISOMAP do a bad performance when used in the feature extraction of acoustic targets in the battlefield. To solve the problem, this paper proposes a new method for more robust approximation of the geodesic distances of ISOMAP using a viewpoint of electric circuits. The charge times are used to construct new distance measures. In this way, we achieve both the stability of local methods and the global approximation property of global methods. Experimental results prove that the new distance measures can achieve significant advancement over the former method, which can improve the system performance effectively.

Comparative Study of Two Velocity Update Algorithms for SINS

LIN Yu-rong， CHEN Liang， FU Zhen-xian

2012, 33(10):  1185-1193.  doi:10.3969/j.issn.1000-1093.2012.10.006

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Both traditional and dual quaternion-based velocity update algorithms for strapdown inertial navigation system (SINS) are comparatively studied. The leading cause of difference in accuracy between the two algorithms is analyzed and determined in principle. By defining both truncation and approximate integral errors, the difference in accuracy can be not only described qualitatively but also computed quantitatively. The validity of theoretical analysis and derivation is verified through simulation testing. The significant superiority of the dual quaternion algorithm over the traditional one in accuracy is demonstrated through simulation results under highly-dynamic and large-maneuver conditions. Comparison results under both ideal and real dynamic conditions show that the dual quaternion algorithm is superior to the traditional one in overall performance.

Dynamic Modeling and Control of an In-plane 2-DOF Morphing Wing

SHI Rong-qi， SONG Jian-mei， ZHANG Ming-liang

2012, 33(10):  1194-1201.  doi:10.3969/j.issn.1000-1093.2012.10.007

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The dynamic equation of the morphing wing was obtained based on Lagrange method of analytical mechanics. The skin elastic forces and the aerodynamic load acting on the leading edge were taken into account. Since the morphing wing was a strongly coupled, over-actuated nonlinear system with multi-input and multi-output, a control system of the morphing wing, including control allocator, dynamic inversion controller and PID controllers, was designed. The control allocator was obtained by the pseudo inverse method; the dynamic inversion controller was applied to make the original system decoupled into two independent linear systems; two classical PID controllers were adopted for the linearlized systems. The mathematical model of the morphing wing was verified via ADAMS simulation. The control system was tested by system simulation using Matlab. The results show that the combination of Lagrange equation, pseudo inverse allocation, dynamic inversion control and classical PID method can effectively solve the dynamic modeling and control problems of the in-plane 2-DOF morphing wing.

Calibration of Strapdown Three-axis Magnetometer and Measurement Error Compensation of GeomagneticField Based on Total Least Squares

WU Zhi-tian, WU Yuan-xin, HU Xiao-ping, WU Mei-ping

2012, 33(10):  1202-1209.  doi:10.3969/j.issn.1000-1093.2012.10.008

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A method of simultaneous magnetometer calibration and measurement error compensation of geomagnetic field was proposed. A parameterized model comprising sensor calibrating error and measurement error of geomagnetic field was constructed by an error analysis through the measurement. Those parameters in the model were estimated using total least squares (TLS) based algorithm, according to the spread of measurement noise. Compared with the traditional least squares (LS) based algorithm, both simulated results and experimental results show that the TLS based algorithm achieved higher estimated precision and better compensation.

Research on Close Air Combat Modeling of Differential Games for Unmanned Combat Air Vehicles

FU Li， WANG Xiao-guang

2012, 33(10):  1210-1216.  doi:10.3969/j.issn.1000-1093.2012.10.009

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Based on a six-degree-of-freedom model of unmanned combat air vehicles（UCAVs）, a differential countermeasure was combined with computer game for the problem of autonomous decision of UCAVs in air combat. The traditional differential game model which uses “angle advantage” as payoff function was improved by introducing “changing value” in the computer game for reference. When UCAV is in different air combat situation, the model embodies the real air combat situation of that the different incomes are obtained with the change of the same angle, so it makes the air combat strategies more intelligent and more reasonable. The simulation results show that the algorithm is rational and effective.

Research on Environmental Factor of Exponential Product Based on F Distribution

CHENG Hong-wei， TAO Jun-yong， ZHANG Yun-an， CHEN Xun

2012, 33(10):  1217-1221.  doi:10.3969/j.issn.1000-1093.2012.10.010

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A method of calculating the environmental factor of exponential product based on F distribution was studied for a reliability assessment of complex system according to the small-scale samples and experimental data from different test environments and samples. The analysis result shows that the environmental factor is also applicable to the test data of variable population. For small-scale sample, the shortcoming of existing method on the selection of benchmark environment was analyzed, and the rule of choosing benchmark environment was given. Based on the analysis result above, a new algorithm containing correction factors was proposed for small-scale sample. Finally, the validity of the proposed method was proved using simulation data.

Robust Adaptive Beamforming Based on Vector Optimization

SONG Hai-yan， PIAO Sheng-chun， QIN Jin-ping

2012, 33(10):  1222-1229.  doi:10.3969/j.issn.1000-1093.2012.10.011

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When an arbitrary unknown signal steering vector mismatch occurs or the training sample size is small, the performance of standard Capon beamforming (SCB) will be severely degraded. The existing algorithms are mostly made for the steering vector errors, with little considering the situations of small training sample size. In this paper, we develop a new approach, which is called vector optimization robust beamforming (VORB), to robust adaptive beamforming in the presence of an arbitrary unknown signal steering vector mismatch and small training sample size. Our approach is based on the vector optimization concept. It is shown that the proposed algorithm can be reformulated in a convex form as the so-called second-order cone (SOC) program and solved efficiently using the well-established optimization tool, Sedumi. It is also shown that the proposed technique can be interpreted in terms of diagonal loading, and how the optimization value of the diagonal loading is affected by different factors. Theory analysis and computer simulations show better performance of our robust beamformer as compared with existing adaptive beamforming algorithms: under different snapshots, SNRs and steering vector uncertainties, VORB can improve the output SINRs about 5 dB; under certain conditions, VORB has sharper spectrum peaks and lower sidelobe level (below -15 dB). Finally, experimental results show that when VORB is applied to the spatial spectrum estimation in practical engineering, the robust high-resolution bearing estimation results can be obtained.

Simulation Study on Drag Reduction Characteristics of Bionic Jet Flow Based on Shark Gill

GU Yun-qing, ZHAO Gang, ZHAO Hua-lin, ZHENG Jin-xing, WANG Fei, XIAO Lei, LIU Wen-bo

2012, 33(10):  1230-1236.  doi:10.3969/j.issn.1000-1093.2012.10.012

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A bionic jet model based on the feature of shark gill was established for the characteristics of flow field on the bionic jet surface. The drag reduction characteristics and drag reduction mechanisms of bionic jet flow based on shark gill were studied using numerical simulation method at the main flow field velocity of 3 m/s and the jet velocity of 0.02~1 m/s. The results show that: the bionic jet flow based on shark gill has a drag reduction effect when the jet velocity u is more than 0.1 m/s, and the drag reduction rate increases with jet velocity. The bionic jet flow based on shark gill affects the drag reduction characteristics of model by changing the frictional resistance and pressure drag. The mechanism of bionic jet flow influencing on frictional resistance is that the thickness of viscous sublayer at the downstream of jet outlet increases and the velocity gradient reduces. And a reverse eddy forms, which makes the flow field have a stable large vortex structure and reduce the influence of turbulent fluctuation on the wall. The mechanism of bionic jet flow influencing on pressure drag is that the jet velocity, as an additional power, inhibits the differential pressure resistance, resulting in its decline.

Research on a Novel Parallel Hydraulic Haptic Master Servo Control System

FENG Shi-zhu, XU Ming, ZHAO Ding-xuan, SU Bo

2012, 33(10):  1237-1242.  doi:10.3969/j.issn.1000-1093.2012.10.013

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Using a parallel hydraulic Stewart-6-DOF platform as a force reflecting haptic master, the force based model is deduced and the general predictive control (GPC) theory is used for the design of the controller to control the 6-DOF parallel hydraulic force reflecting haptic master. The servo control system test bench has been set up by using a piece of the 6-DOF master. The test results show that the control system overcomes the model error and uncertainty and gain better both dynamic and static respondence. It is of certain significance for parallel hydraulic haptic master control system design.

Research on Numerical Simulation and Modification of Combustion System in a Diesel

YOU Guo-dong, SU Tie-xiong, SUN Li-wei， WANG Qiang, XU Chun-long

2012, 33(10):  1243-1250.  doi:10.3969/j.issn.1000-1093.2012.10.014

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The combustion system in a high specific power diesel was studied. Firstly, 3D numerical simulation of the combustion process in the chamber was carried out by AVL-Fire. The WAVE model, the Dukowicz model and the Eddy Break Up model were utilized to predict the fuel atomization, evaporation and combustion processes, respectively, and the k-ε two-equation turbulence model was employed to predict the turbulent flow. The predicted average pressure and effective power agree well with the measured ones, verifying the employed numerical models. Secondly the detailed analysis of the numerical three-dimensional flow field, thermal field and oil distribution during the combustion process were carried out, and the disadvantages of the original combustion system were found out.. The structure of combustion system was modified on the basis of the above-mentioned analysis. Then The modified combustion system was also numerically simulated by using the same numerical models as the original chamber. Finally the numerical results of the original and the modified combustion system show that the performance of the combustion system is significantly affected by the shape of the combustion chamber, and that the combustion organization of the modified combustion system is significantly improved compared with that of the original one, resulting in great increase in the effective power and heat release rate of the combustion system.

Improved-Layered-Marginal Algorithm to Optimize Initial Spare Part Configuration Project

RUAN Min-zhi， LI Qing-min， LI Cheng， HUANG Ao-lin

2012, 33(10):  1251-1257.  doi:10.3969/j.issn.1000-1093.2012.10.015

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Optimization of spare parts configuration project is critical for increasing support effectiveness as well as reducing equipment life cycle cost, but the spare parts model solution under the multi-echelon maintenance supply is a large scale and non-linear NP-hard problem, in order to improve the model algorithm’s optimization efficiency. The initial spare parts inventory configuration model based on equipment availability is established and researched. According to the traditional marginal algorithm, the layered optimization method is introduced to improve the algorithm’s optimization efficiency. The detailed design and optimization flow of the algorithm is given, and its calculation efficiency is analyzed in theory. The numerical result of the given example shows that the computation result of the improved layered marginal optimization algorithm is identical with the traditional algorithm, besides, the calculation efficiency increase nearly three times. The research results can provide a new idea for spare parts optimization method in engineering application.

Research Notes

Consumption Forecasting of Missile Spare Parts Based on Rough SetEntropy Weight and Improved SVM

ZHAO Jian-zhong, XU Ting-xue, LIU Yong,YIN Yan-tao

2012, 33(10):  1258-1265.  doi:10.3969/j.issn.1000-1093.2012.10.016

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On the basis of analyzing systemically present research condition of forecast method toward weapon and equipment spare parts and consumption characteristic of missile spare parts, the paper brought forward the thought of applying forecast model composed of rough set (RS), entropy weight (EW), and weighted least squares support vector machine (WLS-SVM) with adaptive particle swarm optimization (APSO) to consumption forecasting of missile spare parts. Firstly, the paper presentes basic theory, improves on search mode of APSO and weighted method of least squares support vector machine(LS-SVM); secondly , the consumption forecasting model of missile spareparts is established based on RS, EW and WLS-SVM with APSO, and realization process is analyzed. The example results show that the combinatorial forecasting model has better forecast precision and important applied value in the course of consumption forecasting of missile spare parts.

Study on Composable Modeling and Simulating Technology for Equipment Battlefield Damage

WANG Guang-yan, HU Qi-wei, LIU Wei

2012, 33(10):  1266-1275.  doi:10.3969/j.issn.1000-1093.2012.10.017

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In order to integrate equipment battlefield damage models of many levels into one large model, and describe equipment battlefield damage characteristics from resolving power of microcosmic, moderate, and macroscopical angles, composable modeling and simulating technology is studied. The hiberarchy of equipment battlefield damage models is researched from the sides of physical alteration level, function degradation level, and equipment cluster battle effectiveness degradation level. The relations among those different level models are analyzed. The mapping relation between physical alteration battlefield damage model and function degradation battlefield damage model is researched, the function description method based on equipment characteristic is presented, as well as the aggregation/disaggregation method for physical alteration battlefield damage model and function degradation battlefield damage model. The mapping relation between function degradation battlefield damage model and equipment cluster battle effectiveness degradation battlefield damage model is researched, the aggregation/disaggregation method for function degradation battlefield damage model and equipment cluster battle effectiveness degradation battlefield damage model is presented. At last a case of equipment battlefield damage composable modeling is researched. The research result shows that equipment battlefield damage composable modeling and simulating technology can realize high resolving power output for macroscopical model, and it helps to research equipment battlefield damage roundly.

Configuration Parameter Identification and Error Analysis of Mobile 6-DOF Parallel Mechanism

YAN Hao， LI Chang-chun， SUN Hui-peng

2012, 33(10):  1276-1280.  doi:10.3969/j.issn.1000-1093.2012.10.018

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To solve the configuration identification problem of mobile 6-DOF parallel mechanisms, the absolute coordinates of an arbitrary measuring point were measured under various configuration conditions, and a system of kinematics equations was built and solved optimally to identify the configuration parameters of a parallel mechanism at an unknown location and compute the coordinates of the measuring point. The adjustment value of each actuator can be obtained according to the target coordinates of measuring point. Consequently the motion control of parallel mechanism can be performed. The redundant equations were solved by using Trust-Region Dogleg algorithm，and the validity of this method was confirmed by experiment. The simulation and experiment show that the identification accuracy of measuring point is higher than that of parallel mechanism location. When the movement error of the parallel mechanism is no more than 0.02mm, its positioning error in the absolute coordinate system can be limited within 0.3mm using this method.