bob手机在线登陆学报自然版

2019, 39(7): .

Abstract(573) PDF(209)

Abstract:

2019, 39(7): .

Abstract(519) PDF(220)

Abstract:

Feeder Head of Relative Rotary Based on Gas-Solid Two Phase DEM Model

SUN Xiao-xia, MENG Wen-jun, NIU Xue-mei, YUAN Yuan

2019, 39(7): 661-668. doi:10.15918/j.tbit1001-0645.2019.07.001

Abstract(801) PDF(313)

Abstract:
Taking a common relative revolving feeder head as research object, the work mechanism of the feeder head and the material kinematics in the feeder head were analyzed in this paper. Firstly, the gas-solid two phase DEM model and coupled simulation method were studied. Then a 3D model of physical feeder and spread equation of the feeding surface were established. Finally, considering the surface data of the feeder head, the coupling simulation analysis was carried out with EDEM+Fluent software. As a research result, this paper recommends a curve equation of the feeding surface with different friction coefficients, deduces an equation for the transport quantity of the feeder head based on the transport and feeding quantity analysis, and presents an equation for rotate speed of the feeder head. The results provide an important guidance for the feeder head design.

Noise Reduction Method Based on Chaotic Synchronization System and Its Application in Fault Diagnosis of Rolling Bearing

LI Guo-zheng, TAN Nan-lin, SU Shu-qiang, ZHANG Chi

2019, 39(7): 669-675. doi:10.15918/j.tbit1001-0645.2019.07.002

Abstract(781) PDF(727)

Abstract:
A noise reduction method was proposed based on the chaotic synchronization system, and was applied to process the vibration signal of the rolling bearing and to diagnose the bearing fault in combination with the power spectral density. Firstly, analyzing the noise reduction mechanism of the chaotic synchronization system, the influence of the input signal on the phase space trajectory was discussed for different running state. Then, a noise reduction model of the chaotic synchronization system was built based on the Chua's circuit, analyzing its characteristics and comparing with other methods. Finally, taking the actual vibration signals of three different damage modes of rolling bearing as the input of the model, the waveform and the change of power spectrum density of vibration signal and synchronous error signal were compared based on their respective fault characteristic frequencies. Taking advantages of the noise immunity and synchronism of the chaotic system, the problems of parameter setting complexity and the decision difficulty of the system running state can be avoided in the existing chaotic detection methods.The experimental results show that the new chaotic synchronization system can effectively improve the signal to noise ratio of the measured signal, and is suitable for the pre-processing of the signal. And it can be combined with the traditional method to form a new fault diagnosis method.

Path Following Control of Autonomous Vehicles Based on Hamilton Theory

CHEN Te, CHEN Long, XU Xing, CAI Ying-feng, JIANG Hao-bin

2019, 39(7): 676-682. doi:10.15918/j.tbit1001-0645.2019.07.003

Abstract(970) PDF(425)

Abstract:
To solve the problems of low precision and poor reliability in the path following control of autonomous vehicles, a hierarchical path following control strategy was presented basis on Hamilton theory for four wheel independent drive and four wheel independent steering autonomous vehicles. Integrating vehicle dynamic model and path following model, an error model of path following was presented. According to the control target of path following system, the Hamilton theory was applied to design the upper layer vehicle controller, used to achieve the stabilization and convergence of path following error model and improve the accuracy and robustness of vehicle path following system. Moreover, in the lower layer controller, a distribution algorithm was designed for four-wheel longitudinal tire force to meet control demand of upper layer with dynamic orientated distribution of tire force. A simulation model for vehicle path following was established in CarSim and Simulink software and the simulation verification was carried out. The results show that the proposed hierarchical path following control strategy of autonomous vehicles can restrain the lateral offset and heading error during process of path following control, synchronously improve the accuracy of path following and ensure the reliability of path following control system by real-time control of front and rear wheel steering angle and distribution of four wheel tire forces.

Multidisciplinary Design Optimization of Active Suspension with Control Discipline in Loop

CHEN Xiao-kai, LEI Hao, LIU Jia-hui, LI Meng-qiang

2019, 39(7): 683-687. doi:10.15918/j.tbit1001-0645.2019.07.004

Abstract(679) PDF(271)

Abstract:
Taking the design and optimization of active suspension as an example, based on the idea of multidisciplinary design optimization, a multidisciplinary design optimization method was proposed with the control discipline in loop, bring the control discipline into the optimization loop of the system. To achieve better overall optimal results, the collaboration between the system's structural design and control discipline was fully considered. And a quarter-vehicle active suspension model and the LQG controller model were established. Based on the optimization framework of the multidisciplinary feasibility method, multi-disciplines analysis was conducted, and the suspension parameters and controller parameters were optimized at the same time. The optimization results show that this method can coordinate the coupling relationship between suspension dynamic and control discipline to obtain the global optimal solution. The optimized active suspension can reduce the root of mean square (RMS) of vertical body acceleration by 27% under the premise of not consuming more energy, and can ensure that the suspension's working space and tire deformation are within a certain range.

Objective Functional and Numerical Solution Method of Vehicle Optimal Dynamic Performance

GUO Zhi-qiang, WU Wei, LIU Yang, LI Bo, YUAN Shi-hua

2019, 39(7): 688-693. doi:10.15918/j.tbit1001-0645.2019.07.005

Abstract(873) PDF(273)

Abstract:
In order to achieve best dynamic performance of vehicle,a parameter matching method was proposed for vehicle power train. Firstly, the speed ratio of gear box was optimized based on functional analysis theory. Then taking the speed ratios as functional argument, a general functional form of acceleration time was established. The numerical and optimal solutions of speed ratios were obtained based on Euler finite differential method in calculus of variations. Finally, to analyze acceleration performance in different control strategies, a dynamic model of continuously variable transmission was established. Simulation results show that, the acceleration time of 6~60 km/h can decrease by 8.79% in 100% throttle opening based on the functional control strategy, verifying the feasibility of the functional analysis method for optimal ratio control problems in theory.

Energy Consumption Optimal Control Method of Electric Active Stabilizer Bar

PI Da-wei, XIE Bo-yuan, WANG Xian-hui, WANG Hong-liang, WANG Er-lie, LI Jiao, WANG Li-hui

2019, 39(7): 694-698. doi:10.15918/j.tbit1001-0645.2019.07.006

Abstract(1036) PDF(336)

Abstract:
In order to solve the problem of high energy consumption of the electric active stabilizer bar caused by the large torque ripple of the permanent magnet brushless DC motor, a new control algorithm was proposed for three-closed loops. In the outer loop, the PI controller was arranged for motor running angle control. In the middle loop, the PI controller was for the rotate speed control. The optimal control algorithm was used in the inner loop for the stator current control. Based on Simulink softer, 14 DOF vehicle model, electric active stabilizer bar system and its controller model were established and simulated. The simulation results show that the new algorithm can effectively improve the roll stability and ride comfort of vehicle and output performance of motor. The energy consumption of the system is also reduced.

Analysis on Fuel-Saving Factors of Planetary Hybrid Electric Vehicles

ZENG Xiao-hua, CUI Chen, SONG Da-feng, LI Guang-han, DONG Bing-bing, LIU Chi-lin

2019, 39(7): 699-705. doi:10.15918/j.tbit1001-0645.2019.07.007

Abstract(841) PDF(279)

Abstract:
On the base of the internal energy flow of the planetary hybrid system, a theoretical fuel consumption model, a fuel saving model, and a fuel-saving rate model were established to meet the requirement of the fuel saving factor analysis. According to the characteristics of super-capacitor and planetary hybrid system, the coupling relationship among the average fuel consumption rate, the efficiency of each motor and the mechanical efficiency was explored. The quantitative analysis on the direct or indirect effects of the factors on the fuel-saving rate and the principles were presented by decoupling each factor. Results of these analyses clarify the fundamental approaches to saving fuel in the planetary hybrid system and the contribution of each factor to fuel economy, which shows the key points and directions for the depth-saving of hybrid system, and provides great guiding significance for improving the efficiency of the economic optimization of hybrid vehicles.

Cloud Storage Scheme on Attribute Blinding Fuzzy Searchable Encryption

CAO Lai-cheng, WANG Wei-ting, KANG Yi-fan, GUO Xian, FENG Tao

2019, 39(7): 706-713. doi:10.15918/j.tbit1001-0645.2019.07.008

Abstract(945) PDF(244)

Abstract:
In order to protect the attribute privacy of the data users and achieve fuzzy searchable encryption in cloud storage, an attribute blinded fuzzy searchable encryption cloud storage (ABFSECS) scheme was presented. First, each access attribute of the data users was randomly blinded, and then all blinded attributes were polymerized into a complete blinded attribute. Second, through matching computation of the keyword index set and the keyword trapdoor, which was generated by the data user, ABFSECS scheme was arranged to realize fuzzy searchable encryption cloud storage mechanism. Finally, using the strong computing resources of the cloud server, ABFSECS scheme introduced pre-decryption operation, reducing the computing time cost. Security analysis shows that ABFSECS scheme possesses unforgeability, it can resist collusion attack between the data users and cloud storage server, and it does not disclose the attribute privacy information of the data users.

Large-Scale Indoor Pedestrian Density Prediction Based on Neural Network Model

SONG Yu-bo, PENG Chao-yang, SU Yue, LIU Yun-xiao, ZHAO Qian-feng, ZHU Zhen-chao

2019, 39(7): 714-718,769. doi:10.15918/j.tbit1001-0645.2019.07.009

Abstract(1030) PDF(462)

Abstract:
A new indoor crowd density prediction algorithm suitable for large-scale indoor pedestrian flow was proposed. Based on the current crowd density algorithm with wireless signal intensity, a weighted operation was introduced to improve the estimation quality. Further, according to the estimated human flow density in several consecutive time periods, the BP neural network model is used to predict the crowd density in this area at a certain time in the future.According to the simulation model and the data collection and analysis of three months, the accuracy of the prediction model can reach 94.70%.

CP-ABE Based Data Sharing Scheme Supporting Separating Read/Write Permissions

HU Ao-ting, HU Ai-qun

2019, 39(7): 719-724. doi:10.15918/j.tbit1001-0645.2019.07.010

Abstract(721) PDF(248)

Abstract:
In order to solve complex algorithm, huge communication overheads, and security loopholes for CP-ABE-based data sharing scheme problem, a decentralized data sharing system was proposed to custom read and write permissions. The CP-ABE (ciphertext policy-attribute based encryption) algorithm was combined with BLS signature algorithm for the data owner to define read or write strategy of users freely and bind the strategy with ciphertexts, making the matched user decrypt the ciphertexts personally. Experiment results show that, the data sharing scheme can outperform another in computation and communication overheads, number of system parameters, signatures length, and security level.

Design and Application of a Multi-Level Automated Universal Unpack System on Android Platform

JIAN Rong, LI Tong-xin, ZHOU Yuan, LI Zhou-jun, HAN Xin-hui

2019, 39(7): 725-731. doi:10.15918/j.tbit1001-0645.2019.07.011

Abstract(843) PDF(277)

Abstract:
In order to solve the problem that the Android platform application is difficult to perform static code analysis after using the packer service, an automated universal unpack technology was presented. Firstly, a multi-level automated universal unpack system was designed and implemented based on the Android Dalvik virtual machine. And then, a multi-granularity data restoration scheme was proposed to ensure the integrity and validity of data restoration, and to correctly restore the encrypted code content in the packed application. Experiment results show that this system is suitable for mainstream pack services in the market. Evaluating the security of the packed application with this system in the market, more security issues are found in the packed application than in the normal application, which proves the application value of the unpack system.

Robust Face Recognition via Sparse Representation of Multi-Directional Gabor Feature Maps

XU Wang-ming, ZHANG Pei, WU Shi-qian

2019, 39(7): 732-737. doi:10.15918/j.tbit1001-0645.2019.07.012

Abstract(1024) PDF(308)

Abstract:
In order to improve the robustness to variable factors such as illumination, expression, and pose, a novel face recognition method based on sparse representation with multi-directional Gabor feature maps was proposed in this paper. Firstly, multi-directional and multi-scale Gabor transforms were performed on face image, and the obtained Gabor features with different scales in the same direction were fused to generate multi-directional feature maps. Then, Gist features were extracted and adaptive weights were assigned to them for the fused feature maps in each direction. The adaptive-weighted Gist features of all directional feature maps were cascaded to form feature descriptors of face image. Finally, face recognition was implemented with a sparse representation classification method base on the face feature descriptors. Experimental results show that the average recognition rates of the proposed algorithm on Yale, ORL and Extended Yale B face databases are 99.8%, 99.7% and 100.0% respectively.

Automatic Classification of Vulnerabilities Based on CNN and Text Semantics

QU Long-yu, JIA Yi-zhen, HAO Yong-le

2019, 39(7): 738-742. doi:10.15918/j.tbit1001-0645.2019.07.013

Abstract(939) PDF(271)

Abstract:
Vulnerability classification technology is an important basis in information security vulnerability research, and is also an important means for effective management and control of vulnerability resources. In order to solve the problem of large-scale classification of vulnerabilities, an automatic vulnerability classification method was proposed based on convolutional neural network. Referring to the thought of deep learning, relevant local features of vulnerability description were acquired automatically, and the unstable problem of text training was solved through batchnorm normalized data, so as to realize the effective classification of vulnerabilities. Experiments show that compared with the traditional method, the efficiency of automatic classification of vulnerabilities can be improved to a certain degree with the proposed method.

Design of the Security Audit Function for SDN-Based Home Router

WANG Yu, LI Wei, LI Zhou-jun

2019, 39(7): 743-749. doi:10.15918/j.tbit1001-0645.2019.07.014

Abstract(782) PDF(331)

Abstract:
In this paper, a design and implementation method was proposed for the security audit function of wireless router based on OpenFlow protocol in the threat environment such as botnet. It was designed to detect the abnormality of the router's traffic through information entropy calculation and arranged the detection system in SDN (software defined network) architecture to implement the control and display functions. The experimental results show that the entire system can detect the DDoS attack in the network, and the entire system runs only in 8 MB memory, and the network load is only 2.67%.

Method for Measuring Ellipticity Angle of Composite Waveplate

CHENG Yi-bin, HOU Jun-feng, WANG Dong-guang

2019, 39(7): 750-755. doi:10.15918/j.tbit1001-0645.2019.07.015

Abstract(755) PDF(223)

Abstract:
In order to accurately measure the ellipticity angle of composite wave plates, a method was proposed based on Mueller matrix. Firstly, a polarization model of the combined wave plate was established. Then, by measuring its Mueller matrix, three parameters, including retardation, fast axis azimuth and ellipticity angle were obtained simultaneously with non-linear fitting. Finally, the ellipticity angles of the combined zero-order wave plate withλ/4 andλ/2 were calculated and measured respectively by using the Mueller matrix ellipsometry system. The results show that the fitting error based on this method can achieve within 0.004, and the ellipticity angle and fast axis can achieve within 0.004. The measurement error of azimuth angle is 0.11° and that of phase delay is 0.22°. It is also found that the ellipticity angle and fast axis azimuth of the combined zero-order wave plate oscillate with wavelength, and the oscillation amplitudes of the combined zero-order wave plate are 1° and 0.4° respectively. This method is suitable for ellipticity angle measurement of arbitrary combined wave plates and has a wide application range.

Effects of Electromagnetic Interference (EMI) on Information Link of UAV

ZHANG Dong-xiao, CHEN Ya-zhou, CHENG Er-wei, DU Bao-zhou

2019, 39(7): 756-762. doi:10.15918/j.tbit1001-0645.2019.07.016

Abstract(787) PDF(388)

Abstract:
Highly integrating with electronic system and depending on information link, unmanned aerial vehicle (UAV) is vulnerable to external electromagnetic interference (EMI). Due to the large-scale application of UAV in modern electronic warfare, its electromagnetic safety poses a serious challenge. In this paper, analyzing the coupling path to electromagnetic interference, an ideal model of UAV information link to EMI was established to studying the suppression of EMI on work signal of the data link system. Firstly, taking a kind of UAV data link system as the research object, a ground simulating test method was proposed for UAV information link in dynamic flight. Then an experimental system was established to study the EMI injection effect of data link system, and to get the electromagnetic sensitivity criterion. Finally, a series of continuous wave EMI injection experiments were carried out for UAV uplink system. Based on the experiment results, the sensitive frequencies and their electromagnetic sensitivities were found, the mechanism of electromagnetic interference for information link was analyzed, and the relationship among the effect of lost-link, automatic gain control (AGC) voltage and bit error rate (BER) was achieved. The research results can provide an experiential reference for range experiment and electromagnetic interference prediction of UAV.

Influence of Cooperative Self-Defense Coherent Jamming on Mono-Pulse Radar of Dual Stealth Aircraft

BAO Lei, WANG Chun-yang, BAI Juan, ZENG Hui-yong

2019, 39(7): 763-769. doi:10.15918/j.tbit1001-0645.2019.07.017

Abstract(796) PDF(310)

Abstract:
In order to rationally evaluate the performance of angle tracking, distance decoy and detection when detecting and tracking the dual stealth aircraft formation under the condition of cooperative self-defense coherent jamming, a model of cooperative self-defense coherent jamming was proposed based on the hovering track of the formation for stealth aircraft. Firstly, by analyzing the real-time attitude, the formation line-of-sight attitude angle was calculated. Then the dynamic RCS (radar cross section) sequence of formation was acquired based on the static dual-aircraft RCS database in the whole airspace. Finally, the instantaneous error and instantaneous detection probability of radar angle of stealth formation in normal flight and cooperative self-defense coherent jamming were compared and studied by using the angle tracking and detection mechanism of mono-pulse radar under the combined action of target echo signal and coherent jamming, and based on the corresponding joint signal-to-interference ratio analysis model. The simulation results show that the formation self-defense coherent jamming can effectively deceive the monopulse radar angle by 0.26 degrees and reduce the radar detection performance by 34.97%, effectively reducing the loss rate during formation voyage.

Submission System

Author Related

Writing Norms

Links

2019 Vol. 39, No. 7

Archive