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2017, 37(10): .

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2017, 37(10): .

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Calibration of PVDF Pressure Gauge and Its Application in Dynamic Parameters Tests of Similar Materials

WANG Ming-yang, XU Zi-zhang, YUE Song-lin, QIU Yan-yu, LIU Jia-gui

2017, 37(10): 991-997. doi:10.15918/j.tbit1001-0645.2017.10.001

Abstract(1242) PDF(1504)

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As similar materials are more and more frequently used in dynamic model tests, it is significant to measure and analyze the dynamic mechanical parameters of similar materials. Since similar material is soft material, its strength is far lower than rock and concrete, and its wave impedance is also much lower than that is Kolsky bar, which is usually made of steel or aluminum. Therefore, it is impracticable to measure the dynamic mechanical parameters by using the traditional strain measurement system. In this paper, the measurement system in SHPB was improved by utilizing the PVDF piezoelectric gauge, which was based on stress wave theory. By using PVDF gauge to directly measure the two ends of specimen, the dynamic parameterswas obtained, including full stress-strain curve, dynamic modulus of elasticity and the dynamic peak intensity, under different strain rates.

Parameterized Modeling and Thermal Deformation Analysis for Paraboloid Antenna Reflector

RONG Ji-li, XIA Peng, FENG Zhi-wei, XIANG Da-lin

2017, 37(10): 998-1002,1008. doi:10.15918/j.tbit1001-0645.2017.10.002

Abstract(1257) PDF(1146)

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In order to better analyze the influence of thermal deformation on the performance of antenna during the operation of satellite, MSC.PATRAN/NASTRAN was re-developed using the secondary development tool PCL (patran command language).The parameterized modeling, paraboloid fitting and precision analysis were introduced into the finite element calculation. The thermal deformation of large compositeantenna reflector inuniform temperature field was simulated to acquire the best layer-laying method and the performance indexes of antenna after deformation. The simulation results show that the layer design method for reducing heat-distortion and thermal deformation are figured out, and the paraboloid fitting parameters and precision obtained by numerical simulation agree with design requirements, which is suitable for engineering application and provides the foundation for the design of composite antenna reflector.At the same time, numerical simulation solves the problem thatthe universal CAE software is unable to estimate the influence of thermal deformation on the performance of antennas.

Numerical Analysis and Experimental Study of Gun Barrel's Temperature Under Complicated Firing Regulations

FENG Guo-tong, ZHOU Ke-dong, HE Lei, ZHANG Ying-qi, LI Jun-song

2017, 37(10): 1003-1008. doi:10.15918/j.tbit1001-0645.2017.10.003

Abstract(827) PDF(839)

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To deal with the gun barrel life problem caused by transient thermal shock during successive firing under complicated firing regulations, a mathematical model of one-dimensional transient heat transfer for gun barrel was established. Firstly, finite difference schemes of internal nodes and boundary nodes based on energy balance method and ADI (alternating difference implicit) scheme were derived. Secondly, taking the barrel of some 5.8 mm rifle as the study object, the temperature distribution of gun barrel during 150 successive firing rounds was solved by programming on the basis of the numerical results of classical interior ballistic trajectory. Finally, the temperature of gun barrel outside wall was measured by the thermal infrared imager, and the numerical results are consistent well with the experimental results, which demonstrates the validity of the established model and the algorithm used under complicated firing regulations.

Research on Working Condition of Screw-Driving Actuator for Mortar Projectile with Reciprocating Canards

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

2017, 37(10): 1009-1013. doi:10.15918/j.tbit1001-0645.2017.10.004

Abstract(745) PDF(624)

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The time model and dynamic model of the actuator in the stretching process was established to investigate the working condition of screw-driving actuator for mortar projectile with reciprocating canards. The effects of the length and initial angle of the connecting rob on the stretching response time and the output torque of the motor were discussed. The calculated results indicate that when the motor rotation speed is 3 000 r/min, the stretching response time is less than 25 ms and meets the engineering requirements. When the maximum aerodynamic force is 30 N, the actuator can freely control the reciprocation of canards, and the essential motor torque is less than 0.5. The greater the length and initial angle of the connecting rob are, the smaller the value of the motor output torque is and the smoother the fluctuation becomes.

A Multi-Authorities Access Control Scheme Supporting Revocation

LI Yong, LEI Li-nan

2017, 37(10): 1014-1018. doi:10.15918/j.tbit1001-0645.2017.10.005

Abstract(896) PDF(806)

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In recent years, in order to alleviate the pressure on the calculation of a single authorization center, multi-authorities access control schemes were proposed. But these schemes are inefficient in the revocation of user and attribute level. In this paper, a scheme was proposed based on multi-authorities and the key encryption key (KEK) tree was used to achieve revocation. In the scheme, the computation load was distributed to multi-authorities center and partial decryption was transferred to the cloud server. The security proof result shows that the scheme can resist collusion attack, and experiment results show that the scheme can effectively reduce the time consumption of ciphertext and key update in revocation process.

The Application Study on Improved Distributed Genetic Algorithm in Computer Games

LIU Xue-ping, LI You-ru

2017, 37(10): 1019-1023,1030. doi:10.15918/j.tbit1001-0645.2017.10.006

Abstract(808) PDF(1614)

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In order to improve the intelligent of computer games (CGs) system, the efficiency of traditional methods in optimizing training of static evaluation parametric combination and the quality of training, a distributed genetic operator was proposed for clan crossover. The adaptive genetic algorithm was improved in the course of population enlarging and chromosome duplication. Analysis results show that, the ability has been improved with the improved genetic operators, to inherit superior character from parent generation and to explain gene expression. Better training results have been gained in actual optimization of draughts. Besides, simulation experiment has validated the stability and accountability of the algorithm in solving general problems.

On-Line Life Prediction and Health Management of Hydraulic Pumps

WANG Xiang-zhou, YAN He-long, ZHENG Shu-hua

2017, 37(10): 1024-1030. doi:10.15918/j.tbit1001-0645.2017.10.007

Abstract(777) PDF(1201)

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An on-line reliability test and health management system scheme based on electronic controlled hydraulic pump was studied in order to get the real-time health status of the hydraulic pump in this paper. The existing pump controller was improved to collect multiple real-time operating parameters from the pump and send these parameters to cloud data center through industrial ethernet. Cloud data center as the core of data analysis was implemented to complete analysis and processing of the collected parameters, resulting in the realization of online health management, reliability assessment and life prediction of the hydraulic pump. The simulation results show that the system can successfully achieve on-line life prediction and health management of the hydraulic pump with the decrease of time cost and experimental loss.

Hadoop Cloud Platform Dynamic Access Control Based on User Behavior Assessment

YANG Hong-yu, MENG Ling-xian

2017, 37(10): 1031-1035,1042. doi:10.15918/j.tbit1001-0645.2017.10.008

Abstract(813) PDF(716)

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In order to solve the problem that the access control model of the existing Hadoop cloud platform lacks dynamic mechanism, a dynamic access control model based on user behavior assessment (DACUBA) was proposed for Hadoop cloud platform. In this model, a command sequence learning(CSL) algorithm was used to extract user behavior patterns from user instruction sequence, the global pattern library was used to classify user behavior and conduct behavioral assessment of user behavior classification. Then the evaluation value was applied to the access control mechanism of Hadoop cloud platform to implement dynamic access control. The experimental results verify that DACUBA is effective, and compared with other methods, this method has higher efficiency and better stability for cloud request access control.

Signature Extraction and Detection Method of Computer Viruses Based on Immunity and Code Relocation

ZHANG Yu, LIU Qing-zhong, SONG Li-ping, LUO Zi-qiang, CAO Jun-kuo

2017, 37(10): 1036-1042. doi:10.15918/j.tbit1001-0645.2017.10.009

Abstract(954) PDF(1214)

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A novel signature extraction and detection method of computer viruses based on immunity and code relocation was proposed to solve the current infection and threat of computer viruses. Referencing the biology immunity mechanism, some definitions such as self, nonself, antibody, viruses' detectors, and viruses' gene were established. Making use of the code relocation to extract viruses' gene in the computer viruses, a viruses' gene pool was constructed. And the dynamic evolution equations of self and nonself, viruses' gene pool, and viruses' detectors were established. The theoretical analysis and experimental results show that the proposed method can effectively overcome the problem of the self maturity and the integrity of viruses' detectors. Compared with tradition method, the proposed method shows better efficiency and adaptability.

Integrated Guidance and Control Design Based on Integral Backstepping

MA Li-qun, DUAN Chao-yang, ZHANG Gong-ping

2017, 37(10): 1043-1047,1055. doi:10.15918/j.tbit1001-0645.2017.10.010

Abstract(900) PDF(1058)

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The high order of object mode and low robustness are caused generally in the design of integrated guidance and control (IGC) due to much consideration about the rapid response, least time delay and the coupling relation between control and guide. In order to solve the problems and to achieve a high precise tracking in the zero line of sight rate reference and enhance the capability of anti-jamming, an integrated guidance and control algorithm was proposed in this paper based on integral backstepping method, introducing an incremental integral control to the system like a PI controller. High order differential of the line of sight were achieved by constructing high order sliding mode differentiator, while the convergence speed and accuracy of the observed value were ensured. In an attempt to eliminate the adverse influence on the miss distance, the immersion and invariance estimator was designed to estimate the target maneuvering information. Simulation results show that integrated guidance and control can implement a hit-to-kill and have great potential in inhibiting the adverse effects of target maneuver and improving the robustness of the system.

Thermal Runaway Analysis of Lithium-Ion Battery with Overcharge

QI Chuang, ZHU Yan-li, GAO Fei, WANG Song-cen, YANG Kai, NIE Jian-xin, JIAO Qing-jie

2017, 37(10): 1048-1055. doi:10.15918/j.tbit1001-0645.2017.10.011

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In order to study the influence of overcharge current on thermal runaway, numerical model was adopted to calculate the effects of different currents (1C, 2C, 3Cand 4C) on thermal runaway under overcharge conditions. A three-dimensional electrochemical-thermal model based on Multiphysics coupling method was built and critical temperature, critical time and heat distribution of thermal runaway with different currents were calculated. Model feasibility was also verified, the error between simulation and experiment was less than 8%. Overcharge has remarkable effects on the thermal runaway of lithium-ion battery in various ways. Results show that the greater the overcharge current is, the shorter the thermal runaway time will be, the higher the critical temperature will become, and the larger the temperature differences between different parts of and the surface and the interior of the battery will be.

Uncertainty Analysis with Interval Parameters for Flexible Space Manipulator

XIN Peng-fei, RONG Ji-li, XIANG Yang, YANG Yong-tai, XIANG Da-lin

2017, 37(10): 1056-1060,1066. doi:10.15918/j.tbit1001-0645.2017.10.012

Abstract(957) PDF(732)

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Interval uncertainty method of dynamic analysis for the flexible space manipulator was studied in this paper. Absolute nodal coordinate formulation (ANCF), which can describe coupling characteristics of large displacement and large deformation precisely, was utilized to model flexible links of space manipulator. Multibody system dynamic model with uncertainties governed by index-3 differential algebraic equations (DAEs) was established based on ANCF and solved by generalized-αalgorithm. Chebyshev inclusion functions deduced from truncated Chebyshev series were applied to convert dynamic equations with uncertainties into equations at interpolation points of Chebyshev series. Interval dynamic response of the manipulator system was achieved by single uncertainty and multiple uncertainties respectively, which results in a new prediction method of the manipulator endpoint. Compared with the results of Taylor's method, numerical simulations have demonstrated that the proposed method can effectively reduce the emulation workload of the system and errors of the dynamic response prediction value, and quickly obtain the interval dynamic response in a rapid and steady way.

Analysis of Rigid-Flexible Coupling Dynamic Characteristics of Flexible Wing Aircraft

CHEN Yang, WANG Zheng-jie, GUO Shi-jun

2017, 37(10): 1061-1066. doi:10.15918/j.tbit1001-0645.2017.10.013

Abstract(1255) PDF(853)

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For flexible wing aircraft, the elastic motion of flexible wing and the rigid motion of aircraft were strongly coupled; a dynamic model of flexible wing aircraft was established based on the Lagrange equations. In the characteristic points, the dynamic model was linearized based on the small disturbance linearization processing. Coupled with the time-domain unsteady aerodynamic force model, the longitudinal linear equations of motion in state space form was established. The effects of wing structure stiffness on the longitudinal stability of the aircraft and the dynamic characteristics of the aircraft ware analyzed. The results show that the elastic degree of freedom of flexible wing aircraft would have a great impact on the short period mode. With the increase of flight speed, short period mode frequency will increase accordingly, while the first order bending mode frequency will decrease. When the two frequencies tend to be consistent, the body freedom flutter occurs. The body freedom flutter speed is significantly lower than that of the result based on the cantilever wing model.

Optimal Representative Vector Method and Its Application for Glacier Classification

ZENG Yi-liang, ZHANG Sheng

2017, 37(10): 1067-1071. doi:10.15918/j.tbit1001-0645.2017.10.014

Abstract(794) PDF(748)

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The existence of synonyms spectrum phenomenon and the poor sample representativeness and parameter setting in the classification process result in the unstable classification result and poor classification accuracy of hyperspectral images. In order to solve this problem, a novel optimal representative vectors classification algorithm based on sample set optimization was proposed for glacier classification. This algorithm purified original samples in the ROI through an improved density peak clustering method, and selected the optimal representative vectors by clustering the mean vector set of optimized samples as the central vector of each object. Through experimental verification, this algorithm can effectively improve the classification accuracy of the glacier to 90%; it shows that the optimal representative vectors classification method can eliminate the impact of sample differences and improve glacier classification accuracy.

Torque Tracking PID Control for HEV Automatic Diaphragm Spring Clutch

WU Xue-bin, ZHANG Xin, CHEN Hong-wei, YANG Meng

2017, 37(10): 1072-1076,1083. doi:10.15918/j.tbit1001-0645.2017.10.015

Abstract(877) PDF(661)

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Based on the mathematical model of the coaxial parallel hybrid power system and the automatic diaphragm spring clutch, a torque tracking control strategy was presented for automatic diaphragm spring clutch, which include Kalman filter and cascade variable parameter PID controller. A variable parameter torque loop proportional controller was designed, the travel loop PID control parameters were optimized, and some simulation and experimental study on the torque tracking control during the HEV mode switching process were carried out. Results show that the proposed clutch torque tracking control strategy possesses better performance.

Hyperspectral Face Recognition with Spatial-Spectral Fusion Information and Gabor Feature

WEI Dong-mei, ZHANG Li-ren, HU Nan-nan, LIU Lu, MA Na, ZHAO Yue-feng

2017, 37(10): 1077-1083. doi:10.15918/j.tbit1001-0645.2017.10.016

Abstract(988) PDF(1557)

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A hyperspectral face recognition was proposed using the HK-PolyU database in this paper. Twelve spectral bands were chosen from the hyperspectral face image data cubes according the spectral reflection property of skin, and then Gabor features were extracted for each selected spectral gray image respectively. Next, the feature fusion and decision fusion were studied. For the feature fusion, the fusion image was constructed by combining the twelve Gabor-feature vectors, and the weigh coefficients were decided by both the spectral reflection and the recognition accuracy. Maximum voting system was employed in the decision fusion. The validation experiment results show that, the recognition accuracy can reach to 96.5% when three image cubes are selected as training from each class. The recognition speed is more than 3 times of that without band selection. The extensive experiments show that the promising proposed approaches are superior both in the recognition accuracy and in recognition speed.

ECG Feature Analysis Based on Poincaré Plot and Symbolic Dynamics

XIN Yi, ZHAO Yi-zhang, MU Yuan-hui

2017, 37(10): 1084-1089. doi:10.15918/j.tbit1001-0645.2017.10.017

Abstract(768) PDF(1516)

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Heart rate variability (HRV) can be used to predict, prevent heart related diseases and do prognosis evaluation. A method was proposed based on Poincaré plot and symbolic dynamics to analyze ECG feature. Firstly, HRV sequence was extracted from the ECG signal, and presented in Poincaré plot. Then, the splashes in different areas of the plot would be numbered and coded. The entropy of the ECG signal,calculated by the probability of each code, was applied to recognize and classify ECG signal as feature. The experiment results show that, the accuracy rates of classification in normal sinus rhythm and atrial fibrillation, normal sinus rhythm and premature beat are 86.67%, 90% respectively, the method can distinguish normal sinus rhythm from arrhythmia effectively.

Synthesis and Application of Leucine-Based Ionic Liquids as Stationary Phases in Gas Chromatography

JIANG Rui, YANG Shu, SUN Li-quan, LUO Ai-qin

2017, 37(10): 1090-1095. doi:10.15918/j.tbit1001-0645.2017.10.018

Abstract(718) PDF(625)

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A study on the leucine-based ionic liquids as stationary phases in gas chromatography was presented.L-Leucine ethyl ester tetrafluoroborate andL-leucine ethyl ester bis[(trifluoromethyl) sulfonyl] imide were synthesized and used as stationary phases in gas chromatography. Meanwhile, Abraham solvation parameter models at 50,80 and 110℃ were used to evaluate the solvation characteristics. Furthermore, the chromatographic separation performance was evaluated by a Grob test mixture andn-alkanes mixture. The present results demonstrate that the leucine-based ionic liquids stationary phases have good film-forming ability. The system constants indicated that the dipolarity/polarizability and the hydrogen-bond interaction play a major role among five molecular interactions between stationary phases and solute molecules. Leucine-based ionic liquids stationary phases possess excellent chromatographic separation performance, and may be applicable as valuable gas chromatography stationary phases.

Measuring Network Externality in P2P Lending Industry

QIAO Kai, RONG Fang-kun, WU Dao-xin, DONG Pei-wu

2017, 37(10): 1096-1100. doi:10.15918/j.tbit1001-0645.2017.10.019

Abstract(888) PDF(736)

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The attachment curve was used to examine the existence of network externality in P2P lending industry and a model based on supply and demand theory was proposed to measure it. Operational data of 50 domestic P2P lending platforms from June 2015 to May 2016 were collected. With these data, ordinary least square (OLS) regression and dynamic ordinary least square (DOLS) regression were used to measure their network externality. The results show that, there exists a long-term and stable relationship between the number of lenders and that of borrowers; P2P lending industry exhibits positive network externality around 0.1 at the lending side and does not show obvious network externality at the borrowing side. Further Granger Causality Test finds that the growth in the number of lenders is useful in forecasting the growth in the number of borrowers. Therefore, from the perspective of network externality, giving allowance to lenders is a reasonable strategy for P2P lending platforms.

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