bob手机在线登陆学报自然版

2019, 39(5): .

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2019, 39(5): .

Abstract(558) PDF(284)

Abstract:

Absolute Length Measurement Based on Three Frequency-Stabilized Lasers

CHEN Qiang-hua, LIU Bin-chao, LUO Hui-fu, LUO Jun, LÜ Wei-wei, WANG Feng

2019, 39(5): 441-446. doi:10.15918/j.tbit1001-0645.2019.05.001

Abstract(1092) PDF(410)

Abstract:
To measure absolute length, the synthetic wavelength methods must construct a long enough synthetic wavelength made use of several single wavelengths, and make integer of the interference order be zero or a deterministic value. However, it is not easy to find corresponding wavelengths with appropriate values and high wavelength stability in practice. In this paper, a synthetic wavelength absolute measurement method was presented, adopting three high frequency stability lasers to form the synthetic wavelength chain. The measurement equations as well as the transition conditions between grades were derived. And a corresponding phase shift interference optical path was built to make high precision measurement for the absolute length value of the sample. The experiment and error analysis results show the measurement uncertainty is about 3 nm (at 0.3 m sample). In this method the requirement for initial measurement accuracy of the length is low and the measurement range is only limited by the length of the interferometric optical path.

Multi-Objective Lightweight Collaborative Optimization and Design for Latent Parametric BIW Structure

LÜ Tian-tong, WANG Deng-feng, WANG Chuan-qing

2019, 39(5): 447-453. doi:10.15918/j.tbit1001-0645.2019.05.002

Abstract(912) PDF(309)

Abstract:
A parametric model was established with SFE-CONCEPT software for a BIW (body in white). Firstly, the static bending-torsion stiff and the lower-order modal of BIW were simulated based on finite element method, and the results were compared with tests. Then connecting the parametric BIW with power train and chassis, the crash safety performances were simulated based on finite element method and compared with tests. The comparison results between simulation and test validate the parametric model of BIW. Secondly, the lightweight and safety of BIW structure were optimized. Due to the safety simulation analysis belongs to non-linear analysis, the optimization process can't fully achieve automatic, needing manual intervention to extract safety performances in tradition way. In order to achieve the optimization process automation, a batch file was compiled to extract safety performances. The lightweight optimization results show that, the bending stiff can increase 0.15%, the torsion stiff can reduce 0.03%, torsion modal frequency can increase 1.30%, bending modal frequency increased 0.09%. And under the condition that the crash safety performances keep no changing, the weight of lightweight optimization BIW can reduce 24.17 kg, the reduction rate reaches 7.63%. The multi-objective collaborative optimization can provide obvious lightweight effect for BIW.

A Genetics-Based Conceptual Design Methodology of Unmanned Probe Cars

LI Pan, REN Yan-zhao, WANG Guo-xin

2019, 39(5): 454-459. doi:10.15918/j.tbit1001-0645.2019.05.003

Abstract(834) PDF(317)

Abstract:
In order to solve the problem of fuzzy design constraints and incompleteness of key information in conceptual design stage, a conceptual design method based on product genes was proposed, overcoming some blindness in design process and improving the feasibility of designed schemes. Firstly, a conceptual design process model was established. Based on this, a new definition and composition of product genes was put forward. Then, a product gene coding method based on functional elements was proposed. Finally, a genetics-based conceptual design method was described with an unmanned probe car as an example. The results show that this method can clarify the key information of products in the conceptual design process, and reduce the blindness of design so as to improve the feasibility of design schemes and the design efficiency.

Drag Torque Model for Conical Friction Element Based on the Analysis of the Influencing Factors

WANG Yan-zhong, WU Xiang-yu, SONG Yu-huan

2019, 39(5): 460-465. doi:10.15918/j.tbit1001-0645.2019.05.004

Abstract(729) PDF(290)

Abstract:
Conical friction element is a novel friction structure, being capable of improving the torque transfer capability of friction element. In order to reduce the drag power loss of strap transfer mechanism, taking three-cone friction element as example and considering the effects of surface tension and surface structure, a drag torque analysis model was established for conical friction element. The influences of lubricating oil viscosity, friction element separation gap, lubricating oil flow rate and conical structure parameters on drag torque of the conical friction pairs were studied based on numerical analysis method. The results show that the drag torque is increased until reaching maximum value and then decreased afterwards with the relative rotating speed. The effects of viscosity-temperature characteristics of lubricating oil, lubricating oil flow rate, friction element separation gap and cone angle on the drag torque are significant. Unequal cone angle structure can reduce the drag torque of conical friction element.

Design and Experimental Research of Water Hydraulic Large Flow and Fast Response On/Off Valve

ZHANG Jing-xiu, NIE Song-lin, YIN Fang-long, JI Hui

2019, 39(5): 466-472. doi:10.15918/j.tbit1001-0645.2019.05.005

Abstract(949) PDF(344)

Abstract:
In order to meet the demand of large flow and fast response electro-hydraulic control system, a large flow and fast response on/off valve driven by a linear motor was developed. The basic principle was that, integrating the linear motor drive technology with the pilot valve structure closely, the pilot valve and main valve spool were direct driven respectively by a high power linear motor. Firstly, a model was established with AMESim simulation software for the hydraulic quick opening valve to optimize the key structural parameters and to get its static and dynamic characteristics. Then the motion plan was programmed with Matlab/Simulink software for both the position loop and the speed loop of the linear motor to control the movement state of the on/off valve pilot spool and the main spool, to achieve a precise digital control of the valve opening and improve the control accuracy of the fast response and large flow valve. Finally, a prototype of the on/off valve was developed, and the trajectory test of linear motor was carried out. The results show that the linear motor possesses a better following performance and can achieve the planned motion curve. The experiment and simulation results are basically consistent, which proves that the characteristics of the developed hydraulic valve can satisfy the need of large flow and fast response.

Fault Diagnosis of Rolling Bearing Based on Multifractal Descending Algorithm and Improved K Means Clustering

ZHANG Xin, ZHAO Jian-min, NI Xiang-long, LI Hai-ping, SONG Wei-xing

2019, 39(5): 473-479. doi:10.15918/j.tbit1001-0645.2019.05.006

Abstract(950) PDF(316)

Abstract:
To improve the nonlinear and non-stationary characteristics of rolling bearing vibration signal, a multifractal descending algorithm was proposed to calculate the multifractal spectrum parameters. Taking the multifractal spectrum parameters as characteristic parameters, the advantages and disadvantages of multifractal descending fluctuation analysis method and multifractal descending moving average method were compared and analyzed for bearing fault feature extraction. An improvedKmean clustering analysis was used to classify the feature parameters extracted from the multifractal descending algorithm, so as to realize the purpose of bearing fault diagnosis. The rolling bearing data were used to verify the proposed method, and the time domain characteristics and multifractal spectrum parameters were compared and analyzed. And the effects of two multifractal descending algorithms were compared and analyzed. The results verify the combination effectiveness of multifractal descending wave analysis and improvedKmeans clustering for bearing fault diagnosis, and provide a new attempt for bearing fault diagnosis.

Design of a Visual Odometry and Localization Based on Point and Line Features Fusing

ZHAO Jia-heng, LUO Xiao, ZHONG Xin-liang, HAN Bao-ling, HUANG Yu-tong

2019, 39(5): 480-485. doi:10.15918/j.tbit1001-0645.2019.05.007

Abstract(1224) PDF(378)

Abstract:
Point features are mostly extracted in feature based visual simultaneous localization and mapping to estimate camera poses when a robot moves in an unfamiliar environment. However,camera trajectories cannot be estimated accurately if the environment information is not abundant. In this paper, a visual odometry was proposed based on point and line features for RGB-D camera in the environment lacking of feature points. Bundle adjustment (BA) is widely used in estimating camera poses and feature positions. An unavoidable problem of BA with Euclidean coordinates or inverse depth is ill convergence under certain conditions. So a solution was proposed, that integrates parallax bundle adjustment and BA with line features to minimize back-project error. Finally, the proposed approach was compared with other feature based simultaneous localization and mapping (SLAM) system on the dataset TUM. The experiment results show that the proposed approach improves the performance in real scenes lack of point features.

Configuration Design and Dynamic Analysis of Face Gear Axle Assemblies

WANG Yan-zhong, ZHAO Wei-qiang, CHU Xiao-meng, LIU Yang, SU Guo-ying

2019, 39(5): 486-490,496. doi:10.15918/j.tbit1001-0645.2019.05.008

Abstract(846) PDF(301)

Abstract:
A novel design scheme was put forward for full face gear axle, taking the excellent characteristics of face gear drive, such as simple structure, low noise, low sensitive to installation errors and high interchangeability and so on. Firstly, the working principle and characteristics were analyzed. Secondly, based on face gear forming principle and structural conditions, a 3D model and virtual prototype for face gear axle were built. Then the kinematics and dynamics simulation were carried out with ADAMS/View2013 software for the face gear drive in straight driving condition and turning driving condition to analyze the torque and angular velocity. Finally, the machining test of face gear was carried out and face gear test bench was set up. Meanwhile, the differential performance experiments of axle were completed. The simulation results are consistent well with the experimental results, demonstrating the validity of the design scheme. These contributions would improve engineering applications of face gear axle.

Research on the Aerodynamic Characteristics of Formula SAE Under Crosswind

ZHANG Ying-chao, YANG Chao, ZHAN Da-peng, ZHANG Zhe, WANG Da

2019, 39(5): 491-496. doi:10.15918/j.tbit1001-0645.2019.05.009

Abstract(856) PDF(380)

Abstract:
In order to study the aerodynamic characteristics of the racing car under the crosswind effects, a yawing model method was proposed for the simulation and experiment of the 2015 Jilin University's Gspeed racing car. Analyzing the flow field velocity and pressure distribution under different crosswind, the differences of aerodynamic force and the tail flow field were studied to get corresponding aerodynamic coefficients. The results show that the drag coefficient and side force coefficient of the racing car increase with the yaw angle, however, the lift coefficient changes without the linear change of yaw angle. And the down force of the racing car is mainly provided by the front and the rear wings. With the increasing of the yaw angle, the down force of the rear wings decreases and the down force of the bottom floor increases. The drag provided by the car body is more sensitive with the yaw angle. There is a difference of the vortex behind the racing car at different yaw angles.

Research on Electric Vehicle Drive Control Strategy Based on Taguchi Robust Optimization

HUANG Wan-you, WANG Guang-can, YU Ming-jin, LI Yan-hua, ZHANG Ji-cheng

2019, 39(5): 497-501. doi:10.15918/j.tbit1001-0645.2019.05.010

Abstract(847) PDF(298)

Abstract:
In order to improve the dynamic and economy performance of the drive system of electric vehicle (EV), a battery discharge efficiency model, a drive motor system efficiency model and a EV acceleration model were used to build comprehensive objective function. Distributing the weights of the dynamic and economic performance of comprehensive objective function according to the characteristics of city roads, an orthogonal test table was established with the motor torque-motor speed and motor torque-accelerator pedal opening change rate as the signal factors, and with the driving motor temperature and battery pack state of charge as the limit factors. According to the signal to noise ratio of Taguchi robust control, the controller output torque of whole vehicle was optimized. A actual vehicle test was carried out according to the electric vehicles energy consumption and range test procedures in GB/T 18386-2017. The test results got in an urban road cycle show that, compared with previous drive control strategy, the method based on motor torque-motor speed orthogonal table can save energy consumption by 9%; the method based on motor torque-accelerator pedal opening change rate orthogonal table can save energy consumption by 4%.

Scattering Center Model of Electrically Large Deep Rectangular Cavity

LI Qi-feng, GUO Kun-yi, SHENG Xin-qing

2019, 39(5): 502-508. doi:10.15918/j.tbit1001-0645.2019.05.011

Abstract(970) PDF(409)

Abstract:
Rectangular cavity is an essentially geometric structure of aircraft target, like inlet duct. As deep rectangular cavity is one of the most important scattering sources of concealed aircraft and the important identifying characteristics of this kind of target, it has significant meaning and practical applications in the research of scattering center modeling. In this paper, to design a high-precision scattering center model, a scattering center model of electrically large deep rectangular cavity was studied, utilizing ray tracing to determine the location of the multiple reflections of equivalent scattering centers, using the data of full-wave numerical method to accurately estimate the amplitude parameters of the scattering centers. In this model, there set some physical properties and a direct relationship between its parameters and the geometric parameters of cavity for the actual usage of model easily. The validated results indicate that scattering center model can precisely simulate the wave of the radar cross section and the high resolution range profiles of the electrically large deep rectangular cavity targets.

K-Band Two-Channel Integrated CMOS Transmitter Frond-End Chip

QI Quan-wen, ZHONG Shun-an, WANG Zheng-chen, LI An-an

2019, 39(5): 509-513. doi:10.15918/j.tbit1001-0645.2019.05.012

Abstract(1158) PDF(534)

Abstract:
A front-end chip with phase shift function was designed for K-band two-channel integrated transmitter and implemented in TSMC 90 nm CMOS technology. The chip consists of a power divider, two sets of active phase shifters and power amplifiers with different parameters. And a digital block was integrated on the chip to control phase shifters. Measurement results show that, at the center frequency 25 GHz, the gains of two channels are 19.1 dB and 18.9 dB, the output power 1 dB compression points of two channels are 9.57 dBm and 8.41 dBm, and the phase errors of two channels are 1.38° and 1.47° respectively. The power consumption is 0.32 W when the supply voltage is 1.2 V. The total chip area occupies 2.20 mm×1.25 mm.

Analysis of SSN Suppression Characteristics of a New Copier EBG Power Supply Layer with Different Width Polyline Connection Lines

WANG Peng, LU Hao, WANG Zi-yuan, LIU Jin-zhi, XUE Qian-nan

2019, 39(5): 514-519. doi:10.15918/j.tbit1001-0645.2019.05.013

Abstract(1227) PDF(307)

Abstract:
A new type of flip-line coplanar electromagnetic band-gap (EBG) power supply layer structure was proposed in this paper, and the SSN suppression characteristic simulation analysis and practical application test were carried out. Maintaining the metal connection line gap width of 0.2 mm unchanged, four coplanar EBG power supply layer structures were designed with the design width of 0.1, 0.2, 0.3, 0.4 mm respectively. The simulation results show that the cutoff frequency of the coplanar EBG power supply layer with the width of 0.2 mm is the lowest, and the relative band width is higher and the relative characteristic is the best. A coplanar EBG power supply layer with a metal cable width of 0.2 mm was used to fabricate a PCB based on the printed circuit board process. And the actual test was carried out by the vector network analyzer (VNA). The suppression characteristic curve obtained is basically consistent with the trend of the simulation curve, verifying the validity of the design.

Dictionary Learning Algorithm for Compressed-Sensing Based on the Entropy of Image Patches

LIU Lian, WANG Xiao-tong

2019, 39(5): 520-523. doi:10.15918/j.tbit1001-0645.2019.05.014

Abstract(977) PDF(391)

Abstract:
The traditional dictionary learning algorithm doesn't take the internal and external characteristics of the image into account in pre-process. A novel algorithm about image entropy was proposed based on gray-gradient co-occurrence matrix solution. Calculating the entropy of image patches by gray-gradient co-occurrence matrix, each image patch was classified and each type of patches was combined into training set. All kinds of sub-dictionaries were updated by singular value decomposition algorithm based on coefficient matrix. The reconstruction experiment was carried out based on the sparse representation coefficient of the test image. The simulation results show that the algorithm can effectively produce adapted sparse dictionary and significantly improve the accuracy of the reconstruction of image.

Research on Satellite Selection Algorithm of GNSS Repeater Deception Jamming

SHI Peng-liang, JIN Wen-xin, WU Shun-xiao

2019, 39(5): 524-531. doi:10.15918/j.tbit1001-0645.2019.05.015

Abstract(1131) PDF(462)

Abstract:
In modern electronic warfare, the GNSS repeater deception jamming has been an important method of jamming. With the research on satellite selection algorithm of GNSS repeater deception jamming, the jamming ability of repeater deception jamming can be improved. A satellite selection algorithm was proposed based on the satellite selection method of common GNSS positioning and PDOP contribution of single satellite. The simulations were carried out based on the pseudorange single positioning method with the least-squares algorithm, under the static and dynamic conditions respectively. And the receiver attacked by repeater deception jamming with single satellite was simulated under both static and dynamic conditions. The simulation results show that the satellite selection algorithm for repeater deception jamming proposed in this paper can provide the theoretically optimal star selection result with high probability.

Fracture Surface Matching Method of Terracotta Based on Geometric Features

ZHOU Peng-bo, ZHAO Fu-qun, WU Zhong-ke

2019, 39(5): 532-538. doi:10.15918/j.tbit1001-0645.2019.05.016

Abstract(1368) PDF(392)

Abstract:
In order to solve the problems of large noise and defective fracture surface in the 3D data model of Terracotta blocks, a fracture surface matching method based on geometric features of Terracotta was proposed. Firstly, the fracture surfaces were segmented and recognized from the outer surface of Terracotta blocks; Secondly, the concave and convex feature regions of the fracture surface were extracted, and the coarse matching of blocks was completed according to the similarity of feature regions; Lastly, the geometry features including curvature, surface normals and point cloud density were calculated, and the fine matching of blocks was completed using the improved iterative closest point (ICP) based on the geometry features, thus the Terracotta blocks were matching accurately. A great number of Terracotta blocks were used to validate the proposed matching method. The results show that the proposed matching method can complete the Terracotta blocks matching. Especially the proposed fine matching algorithm, compared with ICP and MICP, the matching accuracy can increase by about 40% and 10% respectively, and the time consuming can decrease by 50% and 25% respectively. So the matching method based on geometric features is an effective Terracotta blocks matching method.

Fuzzing Test Data Generation Method Based on Dynamic Construction of Mutation Strategy

JIAO Long-long, LUO Sen-lin, CAO Wei, PAN Li-min, ZHANG Ji

2019, 39(5): 539-544. doi:10.15918/j.tbit1001-0645.2019.05.017

Abstract(1260) PDF(345)

Abstract:
The test data generated by random mutation in fuzz testing destroys the input specification of the target program, which leads to the failure of test data verification and low code coverage. Aiming at this problem, a fuzzing test data generation method was proposed based on dynamic construction of mutation strategy. The method was designed to use the feedback information of instrumentation to dynamically construct the control mutation strategy and the keyword mutation strategy, and to guide the fuzzer to generate test data with high coverage. Experimental results show that compared with random mutation, this method can improve the code branch coverage by about 40% on average. This method can effectively improve the efficiency of fuzz testing, and has a strong practical value.

Active Forensics Technology of Honeypot Based on OpenFlow

YANG Tian-shi, DIAO Pei-jin, LIANG lu-lu, CHANG Zhen

2019, 39(5): 545-550. doi:10.15918/j.tbit1001-0645.2019.05.018

Abstract(1191) PDF(363)

Abstract:
To provide customers with Internet remote services, cloud computing focuses on a large number of computing resources, storage resources and software resources. As cloud computing users, information resources are highly centralized, so the risk of cloud computing security incidents is much higher than the traditional application. Honeypot system can effectively capture the cloud traffic in the attack traffic. However, it is still difficult to develop seductive, protective, and deceptive honeypot systems for cloud computing security development. In this paper, a way was proposed to automatically isolate attack traffic from a real cloud computing server for a honeypot server. The honeypot system was isolated from the real cloud server by creating a virtual machine for a honeypot network server, allowing the honeypot server to have the same memory and storage devices as real cloud computing servers and monitoring the network traffic through OpenFlow. When a visitor visits the server normally, the switch can route the visitor's access request to the real server. When a visitor is marked as a suspicious attacker by IDS, the switch can recalculate the routing path and route the attacker's request to the developed honeypot.

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