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2019, 39(9): .

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2019, 39(9): .

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Numerical Simulation of A320 on the Rigid Target and Verification of the Impact Load Engineering Model

WEN Li-jing, ZHANG Chun-ming, GUO Chao, GAO Yu, DUAN Pu, OU Zhuo-cheng, DUAN Zhuo-ping

2019, 39(9): 881-886. doi:10.15918/j.tbit1001-0645.2019.09.001

Abstract(1029) PDF(499)

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The impact process of an Airbus A320 airplane upon a rigid target under different initial impact velocities was simulated numerically with LS-DYNA analysis software. Comparing the impact load results of numerical simulated and calculated directly with the modified Riera equation, the correction coefficientαwas determined for both of the modified Riera impact load equation and the impact load engineering model. According to the impulse ratio of the crushing load to the impact load, the coefficientγwas determined for the engineering model. Moreover, the empirical formulas to predicate and the coefficientγin the impact load engineering model under different initial impact velocities were proposed, respectively. Results show that, the impact loads calculated with the engineering model are matching with the numerical simulation results, verifying the rationality of the impact load engineering model and providing a basis for the impact load curve of the Airbus A320 airplane and the other large commercial aircraft similar to A320.

Excitation Mechanism of Time-Varying Instantaneous Center of Speed Integrated Gears and Its Torsional Vibration Characteristics

LIU Da-wei, GU Dan-dan, BA Yan-bo

2019, 39(9): 887-893. doi:10.15918/j.tbit1001-0645.2019.09.002

Abstract(749) PDF(410)

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The speed integrated gear is a new kind of high-efficiency and lightweight transmission component, possessing both of circular and noncircular gear functionalities. Aiming to the special transmission mode, the dynamical characteristics of the new gear pair with the excitation of time-varying instantaneous center was studied. Firstly, the transmission principle of the speed integrated gear was illustrated, getting the change rule of the instantaneous center and the drive ratio equation. Then on the basis of separation of the elastic rotation angle, analyzing time-varying instantaneous center, stiffness, damper and error, the excited mechanism of the instantaneous center on the gear was revealed to build a torsional vibration model. Finally, the vibration feature of the speed integrated gear under different conditions was analyzed based on Runge-Kutta method. The calculation results indicate that the compound excitations of the instantaneous center and the stiffness can lead to complex multi-frequency phenomenon, and the instantaneous center excitation will be more over the stiffness excitation to the torsional vibration with the amplitude increasing of the instantaneous center, becoming the primary cause of the torsional vibration.

Motion Analysis of Bearing Rotor System and Phase Control of Spindle Vibration

YU Zhe, CHEN Shu-jiang, MA Jin-kui, LU Chang-hou, LI Hao

2019, 39(9): 894-899. doi:10.15918/j.tbit1001-0645.2019.09.003

Abstract(830) PDF(358)

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In order to limit the vibration of the shaft bearing subsystem and improve the machining accuracy of machine tool in the high-speed movement, a method was proposed based on controlling the amplitude and phase of the rotor of the tilting pad bearing to reduce the amplitude in the front end of the spindle. Firstly, a five-degree-freedom vibration model was established for the rigid rotor system and a differential equation was conducted to solve rotor system vibration. Then,a flow balance method was used to obtain the feed flux, a discrete Renault equation was taken to analyze the oil film force of the tilting pad bearing, an Euler method was used to get the rotor trajectory of the tilting pad bearing, and a linear equation of space was taken to obtain the trajectory of the front rotor of the spindle. Finally,an electromagnetic actuator was used as an auxiliary control device to adjust the tangential acceleration and normal acceleration of the tilting pad bearing rotor. The simulation results show that, the rotor trajectory can converge to a circle and can reduce the phase difference of the front and rear bearings. The amplitude of the front end of the spindle can be reduced by 60.26%.

An Adaptive Control Algorithm for Quadruped Robot Trotting on a Slope

CHANG Qing, HAN Bao-ling, QIAO Zhi-xia, LI Qian

2019, 39(9): 900-906. doi:10.15918/j.tbit1001-0645.2019.09.004

Abstract(1212) PDF(399)

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Inspired by the quadruped locomotion, an adaptive control algorithm was proposed to adjust the trot gait of a quadruped robot on a slope automatically. The transverse and longitudinal displacement compensation adjusted by policy gradient via the signed derivative (PGSD) was introduced in the trajectory of the center of mass (COM) of the robot. The displacement compensation was arranged to reduce the robot's turning moment and time difference between the two diagonal legs landing, and to improve the stability of robot locomotion. The simulation of the robot locomotion was performed with a simulation software Webots. The simulation results show that the adaptive control algorithm proposed in this paper can effectively improve the locomotion stability of the quadruped robot on a slope.

Application Analysis of GIS on UGV Autonomous Navigation

WANG Mei-ling, LUO Jian-heng, YANG Yi, LIU Tong, LI Ya-feng

2019, 39(9): 907-911. doi:10.15918/j.tbit1001-0645.2019.09.005

Abstract(1116) PDF(448)

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To meet the requirements of unmanned ground vehicle (UGV) autonomous navigation in complex urban environments, a positioning navigation method was proposed based on geographic information system (GIS) with strong information storage and management capabilities. It includes GIS database construction, map matching and path planning, as well as capture prior and real-time information of the traffic and surrounding environment. The developed method has been successfully used in the IN2BOT UGV that fulfilled the Chinese Intelligent Vehicle Future Challenge sponsored by the National Natural Science Foundation, and the Unmanned Ground System Challenge held by the Army Equipment Department for several times. Outstanding results achieved in many similar national competitions demonstrate the superior performance of the proposed method.

Research on Collaborative Motion Simulation Environment for Vehicle Rollover

FU Tiao-qi, WANG Xian-hui, ZHANG Ming, GONG Biao, ZHAO Dong, SUN Xiao-wang

2019, 39(9): 912-917,990. doi:10.15918/j.tbit1001-0645.2019.09.006

Abstract(843) PDF(405)

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In order to solve the problem of computational efficiency and accuracy of finite element simulation in vehicle rollover research, multi-rigid-body dynamics and finite element simulation of vehicle rolling were carried out respectively based on the test conditions of FMVSS208 platform vehicles in the United States. Considering the kinematic data exchange between the two simulation methods of vehicle movement attitude in the rolling process, a cooperative simulation method of the motion attitude of vehicle rolling was presented. The results show that the method can take the advantage of multi-rigid body dynamics simulation to replace some kinematic calculation process in finite element simulation, improve the efficiency of finite element simulation on the basis of finite element simulation accuracy, and provide a new technology way for the study of vehicle rollover safety.

Study on the Control Mechanism of Clutch-to-Clutch Power Downshift Process

LI Chun-fu, XI Jun-qiang, CHEN Hui-yan

2019, 39(9): 918-924. doi:10.15918/j.tbit1001-0645.2019.09.007

Abstract(711) PDF(331)

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The control mechanism and control strategy of the clutch-to-clutch power downshift process of automotive automatic transmission were studied. Firstly, the power conversion mechanism between the two clutches in the power downshift process was theoretically clarified, and a method was proposed to achieve the ideal power lap between the two clutches, and verified by simulation and real vehicle test. Then the mechanism of generating a shift shock at the clutch fully engaged was revealed, and a strategy was presented for reducing such a shock. Finally, based on the mechanism research, a piecewise control strategy was proposed for the target trajectory of the input shaft speed. The results of the simulation and real vehicle test show the correctness of the mechanism analysis and the feasibility of the control strategy.

Temperature Rise Characteristic of Friction Disc in Wet Clutch Considering the Local Heat Dissipation on the Contact Surface

WU Jian-peng, MA Biao, LI He-yan, LIU Ji-kai

2019, 39(9): 925-932. doi:10.15918/j.tbit1001-0645.2019.09.008

Abstract(930) PDF(441)

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The friction temperature rise state of friction components in wet clutch is closely related to vehicle performance. In this paper, a numerical model of temperature field was optimized, considering the groove cooling, local heat dissipation and time-varying friction coefficient on the contact surface, and introducing a heat exchange coefficient of equivalent convection between discs and an equivalent gain coefficient. The optimization model was solved and verified based on a finite difference method and experiment. Results show its better accurate and validity than the traditional model. During the stable period, the influence of rotational speed and oil pressure on the temperature field was also analyzed with an optimization model of the sliding temperature field. The influence of lubrication flow on the temperature rise characteristic of sliding friction was experimentally analyzed, and the temperature rise characteristics in deformation failure process were measured. The research results can provide a guiding for the fine simulation and control of the friction components in wet clutch.

Dynamic Modeling and Trajectory Tracking of Intelligent Vehicles in Off-Road Terrain

LIU Kai, WANG Wei, GONG Jian-wei, CHEN Hui-yan, CHEN Shu-ping

2019, 39(9): 933-937. doi:10.15918/j.tbit1001-0645.2019.09.009

Abstract(1030) PDF(588)

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The dynamic modeling and trajectory tracking control of intelligent vehicles in the off-road terrain was presented. First, a vehicle dynamic model considering the road bank angle was developed. And then a zero-moment-point based rollover constraint was derived. Taking these vehicle dynamics and safety constraints into account, a model predictive based intelligent vehicle trajectory tracking controller was designed. Simulation results show that the proposed method can effectively adapt to the complex off-road terrains, ensuring collision-free trajectories while preventing rollover hazard.

A Driving Game Model for Manned and Unmanned Vehicles at Intersection

CHENG Ying, GAO Li, CHEN Xue-mei, ZHAO Ya-nan

2019, 39(9): 938-943. doi:10.15918/j.tbit1001-0645.2019.09.010

Abstract(1092) PDF(398)

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To make a coordinated control for the conflict between manned and unmanned vehicles at intersections, a coordination algorithm was designed based on game theory, regarding the manned and unmanned vehicles at intersections as participants in the game with the thought of intelligent connected vehicle. Firstly, taking the speed change scheme as the game strategy, a profit matrix was constructed for both sides. And then, driving revenue function was determined by introducing the benefits of driving safety, driving efficiency and driving comfort. The Nash equilibrium of the game model was solved as the optimal driving strategy combination of both sides to complete the collaborative optimization of multi-vehicle conflict at intersections. Finally, the diversity of driver types was introduced into the simulation model,validating the proposed algorithm with Matlab software. The simulation results show that, the unmanned vehicle can adjust its behavior strategy according to the behavior of human driver. Compared with conflict table algorithm, the coordination algorithm can reduce the time of conflict resolution obviously. It can be seen that the model not only effectively avoids the collision risk, but also improves crossing efficiency at intersections.

The Adaptive Two-Dimensional Time Delay Estimation Algorithm of Passive Intermodulation Interference

HAN Hang-cheng, CHENG Zhi-heng, SUN Can-can, TIAN Lu

2019, 39(9): 944-949. doi:10.15918/j.tbit1001-0645.2019.09.011

Abstract(873) PDF(397)

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Due to the effect of time-varying passive intermodulation on the performance of communication receivers, the passive intermodulation interference was modeled based on power series. Three adaptive two-dimensional time delay estimation algorithms were proposed according to the practical engineering application. The time delay estimation implementation methods of binary search, fast binary search and parallel search were described, simulated and compared. The simulation results indicate that all the three search methods can work after different iterative learnings. Among them, the two-dimensional time delay estimation algorithm based on fast binary search is more suitable for hardware implementation with less resource and faster tracing speed. The experimental results show that, the prototype with the two-dimensional time delay estimation algorithm based on fast binary search can estimate the two-dimensional time delays accurately and achieve a good performance.

Pulse-Sorting Algorithm Based on Correlation Peak Detection with Adjustable Parameters

ZHAO Di, DENG Zhong-liang, YANG Zhi-yong

2019, 39(9): 950-956. doi:10.15918/j.tbit1001-0645.2019.09.012

Abstract(1101) PDF(455)

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The conventional pulse sequence detection algorithms do not consider the feature information of the pulse repetition interval (PRI) in different work modes, bring about some disadvantages of larger detection error in low signal-to-noise ratio circumstance and higher computational complexity with TACAN. To solve this problem, an algorithm based on correlation peaks' positions with adjustable parameters was proposed for pulse sequence detection and sorting. Firstly, determining the optimal objective in virtue of the signal cross-correlation detection model, a negative definite Hermitian Matrix was developed for detecting pulses. The pulse sequences, not conforming to PRIs, were filtered out by detecting the correlation peaks' positions in the matrix. Then the interference components caused by signal fading were eliminated using pulse blanking. And the problem of missing pulses in incomplete period was solved by using the pulse sort method of cyclic queue. Simulation results show that, the proposed algorithm can improve the detection accuracy of the pulse time of arrival (PTOA) and the detection accuracy of the benchmark pulse sequence while improving the signal-to-noise ratio.

Survey of Constraint Solving Techniques Research Progress in Symbolic Execution

ZOU Quan-chen, WU Run-pu, MA Jin-xin, WANG Xin, XIN Wei, HOU Chang-yu, LI Mei-cong

2019, 39(9): 957-966. doi:10.15918/j.tbit1001-0645.2019.09.013

Abstract(1700) PDF(427)

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In symbolic execution, constraint solving is mainly responsible for path reachability prediction and test input generation, but due to the path explosion problem and the limited power of the SMT solver, constraint solving occupy high overhead in symbolic execution, and this problem has become one of the bottlenecks in symbolic execution. This paper first introduces the basic concepts of symbolic execution, constraint solving, and analyzes the origin of the constraint solving problem. Second, this paper divides the optimization techniques in recent years into three stages:pre-solving, in-solving and post-solving. The related techniques include slicing, simplification, fast unsatisfiability check, multi-solver support, etc. Finally, the conclusions and prospects are made. It is proposed that the future work should focus on the improvements in respect of constraint reduction, constraint solutions reuse, parallel solving, solving configuration prediction, etc.

Research on Workflow Technology for Vulnerability Management

YANG Shi-yu, SU Li-li, HOU Yuan-wei, HAO Yong-le, LI Wei-ping

2019, 39(9): 967-973. doi:10.15918/j.tbit1001-0645.2019.09.014

Abstract(987) PDF(370)

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With the growing threat of network vulnerability, cyberspace is confronted with numerous dangers and the vulnerability management agencies play an increasingly significant role therefore. Vulnerability management is supposed to be institutionalized, standardized, and streamlined, which is an indispensable cornerstone for effectively reducing vulnerability risk. To improve the efficiency of vulnerability management, general vulnerability management processes were proposed, and a workflow technology was used to model and run these processes. BPMN (business process model and notation) was used to model the management processes and a workflow management system was built to run them. Practices show that, the workflow technology based vulnerability management can improve the efficiency of vulnerability management and effectively remove and control the vulnerability threat.

Analysis of Android Application Component Exposure Vulnerability Based on Machine Learning

SHAO Shuai, WANG Mei-lin, CHEN Dong-qing, WANG Ting, JIANG Xin

2019, 39(9): 974-977. doi:10.15918/j.tbit1001-0645.2019.09.015

Abstract(809) PDF(372)

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There are many automated vulnerability detection methods for Android applications. However, existing vulnerability detection solutions still rely on prior knowledge and lead to high false positive rates. To improve the existing vulnerability detection methods, a machine learning based method was proposed to identify the component exposure vulnerability of Android applications. Analyzing Android application software structure and component exposure vulnerability model, a new machine learning system was established to perform the Android vulnerability features extraction, data cleaning and vectorized operation. Utilizing manual analysis and verification, 1 000 Android APK sample sets were established. Through a large number of training, the system can detect the component exposure vulnerabilities automatically, achieving the accuracy up to 90%.

Intrusion Detection System Based on One-Class Support Vector Machine of COME Module

ZHANG Lei, XIE Lun, JIN Liang-chen, WANG Zhi-liang

2019, 39(9): 978-986. doi:10.15918/j.tbit1001-0645.2019.09.016

Abstract(1046) PDF(392)

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According to the industrial control system (ICS) behavior, COM-Express Module and finite state characteristics, combined with the data packet protocol deep analysis and industrial control system process control model, a control instruction rule-matching detection algorithm of process control and a specific intrusion detection model of detection schemes were designed. Several executive technologies were introduced, including the process control rule of One-Class Support Vector Machine (OCSVM) classification, sample feature extraction of the intrusion detection model, the generation process of single classifier, and the transformation of detection algorithm. Considering the model training accuracy of distributed control system (DCS) and the simulation experiment data of intrusion detection, simulation experiments accompanied with usage of COM-E Module demonstrate the effectiveness of the model for anomaly intrusion detection in ICS network. Results show its huge practicability and promotion value.

Based on Memory of Key Information Infrastructure Security Detection Technology

LI Juan, CUI Jia, SHI Lei

2019, 39(9): 987-990. doi:10.15918/j.tbit1001-0645.2019.09.017

Abstract(811) PDF(354)

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A key information infrastructure security detection technology was proposed based on "memory" to overcome the limitations of the traditional IDS (intrusion detection technology) and WAF (web application firewall) technology in Web attack detection,in this paper. Analyzing comprehensively the three processes of the Web application attack cycle, an attack chain technology based method was used to be able to analyze the real-time data and historical data of Web data bidirectionally, detect various fragmented and persistent attack means, and simultaneously perceive all kinds of vulnerabilities when hackers use attacks, so as to understand and grasp the status of network risk in real time.

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