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2018, 38(9): .

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2018, 38(9): .

Abstract(546) PDF(315)

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Process Parameters Influence of Cross-Wedge Rolling on Interface Shear Strength of Laminated Shaft Made from 42CrMo/Q235

PENG Wen-fei, ZHU Jian, SUN Bao-shou, HUANG Guang-xing, SHU Xue-dao

2018, 38(9): 881-887. doi:10.15918/j.tbit1001-0645.2018.09.001

Abstract(982) PDF(441)

Abstract:
Through rolling experiments and interface shear strength tests of cross-wedge rolled of laminated shaft made from 42CrMo/Q235 composites,the effect laws of process parameters including forming angleα,spreading angleβ,area reductionΨ,rolling temperatureTand core material diameterdon the interface shear strength were analyzed.The research results show that the influencing sequence of process parameters on the interface shear strength is theΨ,T,d,β,andαin turn.With the increase of area reductionΨ,rolling temperatureTand core material diameterd,the shear strength also increases,but the higher rolling temperature and the bigger core material diameter will decrease the shear strength.However,with the increase of spreading angleβand forming angleα,the shear strength decreases.The research results provide a basis for the optimal design of cross wedge laminated mold and strengthening the properties of interface bonding.

Research on the Burr Forming Characteristics of Ultrasonic Assisted Micro-Milling Process

HAN Guang-chao, PAN Guang-feng, WU Wen, XU Lin-hong

2018, 38(9): 888-892,898. doi:10.15918/j.tbit1001-0645.2018.09.002

Abstract(996) PDF(393)

Abstract:
Tiny burrs are the key influence factors on the forming quality of micro parts,which are generated in the micro cutting process.In this paper,a horizontal ultrasonic vibration was superimposed on workpiece by double-slotted rectangular hexahedron sonotrode.The ultrasonic micro milling experiments with horizontal workpiece vibration were applied to machine micro grooves on 304 Austenitic Stainless steel sheets and the burr forming characteristics of ultrasonic micro milling process with different experimental parameters was studied.The experimental results show that the horizontal ultrasonic vibration of workpiece can change the burr shape from elongated flocculent structure to continuous flake structure,which is located on the top of micro grooves.With the increasing of ultrasonic vibration amplitude,the height of flake burr decreases gradually and turns into tiny fragments.On the other hand,the horizontal ultrasonic vibration of workpiece can also be helpful to reduce the burr length of micro milling groove. When the tooth feed rate of micro-milling cutter is slightly larger than its minimum cutting thickness,the decrease of burr length will be the most obvious.

Delay Arming Time Control of Safe and Arming Device Using Magnetorheological Fluid

HU Ming, WANG Jiong, LIU Bin, WANG Jun-hong, YAO Chi

2018, 38(9): 893-898. doi:10.15918/j.tbit1001-0645.2018.09.003

Abstract(846) PDF(386)

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To solve the universal problem of fuze arming device using magnetorheological fluid (MRF) for small caliber artillery,the integrated influence of device structure,characteristics of MRF and environment parameter on delay arming time was analyzed,and the control ability was confirmed through equivalent rotation experiment.In the analysis of the structure of the hole,the hole pattern,aperture and hole length were analyzed,and the aperture was designated as control parameter.In the analysis of characteristic of MRF,through the viscosity equation deduced based on the Herschel-Bulkey model and viscosity-temperature experiment,the influence factors of the viscosity were determined when MRF discharged.Finally,through changing the aperture and configuration of MRF,the ability to control delay arming time was well studied under 60 000~90 000 r/min rotation speeds in equivalent rotation experiment.The results indicate that the delay arming time can be controlled effectively when the configuration of MRF is 7:1、8:1、9:1 and aperture is 0.26~0.30 mm,and the device has good universality under these conditions under 60 000~70 000 r/min rotation speed.

Analysis for Global Performance Index of 5UPS-RPS Parallel Mechanism Based on Jacobian Matrix

WANG Xue-lei, ZHANG Bin, LI Chuan-jun, HUANG jie, Wu Tai-yu, CHENG Yong

2018, 38(9): 899-904. doi:10.15918/j.tbit1001-0645.2018.09.004

Abstract(838) PDF(347)

Abstract:
A novel 5UPS-RPS 5-dof parallel mechanism with one RPS-type constraint leg and five of the same UPS-type active legs was presented.First,the characteristics of this PM were introduced,the first-order and second-order comprehensive influence coefficient matrix were derived by virtual mechanism method,and analytic formulas for solving the velocity and acceleration of this PM were derived systematically.Second,the velocity global performance index for the optimization of this parallel mechanism in the workspace was derived based on the condition number of Jacobian matrix. Then the dimensions of the fixed base and moving platform with good kinematic performances were derived in the workspace. Furthermore, theoretical analysis on velocity global performance index provides a foundation for the optimization design of this parallel mechanism in the future work.

Effect of Ambient Temperature on the Performance and Peak Load Regulation of the E-Stage Gas-Steam Combined Cycle Unit

QIAN Jiang-bo, ZHOU Wei-wei, GU Qing-feng, ZHANG Wei, ZHANG Nan, ZHOU Pei, SHAO Li-wei, ZHANG Li

2018, 38(9): 905-911. doi:10.15918/j.tbit1001-0645.2018.09.005

Abstract(841) PDF(425)

Abstract:
Taking a cycle combined with PG9171E gas turbine as the benchmark unit, a gas-steam combined cycle off-design model was established. By changing the ambient temperature and the corresponding boundary conditions, the design/off-design performance and peak load regulation of the combined cycle was analyzed. The results show that, basing the performance guarantee condition as the benchmark condition, with lower temperature as winter condition, the unit exhibits a better off-design performance, with the efficiency increment of 1.69%~3.75%, and its net power output will increase by 11.48%~11.57%. On the contrary, with higher temperature as summer condition, the unit shows lower off-design performance with the efficiency decrement of 2.56%~5.08%, and its net power output will decrease by 10.44%~10.58%. For the peaking load capacity of the unit, with higher temperature the capacity is less and the maximum and minimum generating loads is 47.63 MW and 242.62 MW at -20℃,at 40℃ is 39.14 MW and 172.12 MW respectively; and the peak load in the whole year temperature range is 132~194 MW.

Experimental Study on Terrain Classification Based on Acoustic Signal for Tracked Robot

ZHAO Kai, DONG Ming-ming, LIU Feng, WANG Yu-shuai, SUN Jin-wei, GU Liang

2018, 38(9): 912-916. doi:10.15918/j.tbit1001-0645.2018.09.006

Abstract(744) PDF(373)

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In order to extend terrain classification methods and improve accuracy,a terrain classification method based on acoustic signal was proposed.An acoustic pressure sensor was installed to acquire acoustic signal resulted from tracked robot-terrain interaction.The modified MFCC+△MFCC feature vector was extracted.Finally,a tuned support vector machine(SVM)was adopted to perform classification.The results indicate that the information carried by the acoustic signal is able to characterize terrain type.The modified MFCC+△MFCC feature vector is obviously superior to features extracted from amplitude domain,frequency domain and time-frequency domain.The highest accuracy of 89.5% is achieved in campus environment.When the SNR is higher than 20 dB,accuracies around 80% can be achieved in various background environments.Acoustic-based method is proved to be effective in terrain classification application.

Trot Gait Planning Method for Improving the Stability of Quadruped Robot

HAN Bao-ling, WANG Qing-qiang, JIA Yan, LUO Qing-sheng, ZHU Chen

2018, 38(9): 917-920,926. doi:10.15918/j.tbit1001-0645.2018.09.007

Abstract(932) PDF(381)

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To solve the unstable problem of the walking quadruped robot destabilized with trot gait,a new method was proposed by changing the initial position of the support foot.Firstly,combined with the principle of zero moment point (ZMP),the optimal initial knee joint angleθ₁and the hip forward joint angleθ₂were calculated,and then the optimal initial position was figured out.Simulation results show that the stability of quadruped robot can be different with different initial position.Taking the optimal initial position,the robot body can show the smallest deflection,getting the best stability.It is proved that the stability of the quadruped robot can be effectively improved by adjusting the initial state of the support foot,which is of high practical value in the quadruped robot walking with trot gait.

Numerical Analysis of the Vortex Cavitation Around the Revolution Body with Cone-Shaped Headforms

KONG De-cai, HUANG Biao, WEI Hai-peng, YOU Tian-qing

2018, 38(9): 921-926. doi:10.15918/j.tbit1001-0645.2018.09.008

Abstract(754) PDF(435)

Abstract:
The objective of the paper is to simulate the vortex cavitation around the revolution body with cone-shaped headforms.The numerical results show that when water flow around revolution body,the separate vortices formed at the geometry inflexion point.The separate vortices was simplified into two-dimension elliptic vortices in this paper,and the streamline and pressure distribution in the vortices were analyzed base on boundary layer and vortex flow theory,the relationship between the separation vortex and the cavitation inception was obtained.The flow structure and the geometrical characteristics of the cavitations were analyzed by numerical simulation when the cavity developed.

Control of High-Speed Vehicle Crosswind Stability Based on the Dynamic Two-Way Coupled Method

HUANG Tai-ming, GU Zheng-qi, WAN Zhong-min, FENG Cheng-jie, WANG Yi-ping

2018, 38(9): 927-933. doi:10.15918/j.tbit1001-0645.2018.09.009

Abstract(838) PDF(405)

Abstract:
Aiming at the aerodynamic stability of vehicles with high speed in crosswind environment, a dynamic two-way coupled method was proposed based on large eddy simulation (LES) and 5 degree of freedom model, coupling vehicle aerodynamics and vehicle dynamics. The influence of active front steering (AFS) on the crosswind stability of high-speed vehicle was considered. The robustness of the two-way coupled method was verified by adjusting the center of gravity of the vehicle. The comparison of the vehicle motion and flow characteristics was conducted with or without driver and with or without AFS control. The results show that the lateral velocity and yawing angular velocity have an important influence on the aerodynamic stability of high-speed vehicle under crosswind condition. And without the control of driver the vehicles can return to the normal path with the help of AFS, while the vehicle without AFS can't. The maximum lateral displacement of the vehicle with the driver is 1.1 m without the control of AFS, which is 0.47 m with the AFS. The results show that the AFS can help to improve the vehicle crosswind stability.

Tire Slip Energy Application in Electric Vehicles Control

ZHAO Bin, XU Nan, GUO Kong-hui, LI Xiao-yu

2018, 38(9): 934-939. doi:10.15918/j.tbit1001-0645.2018.09.010

Abstract(821) PDF(390)

Abstract:
Since there is less research on the effect of the minimizing tire slip energy, different opinions are resulted on the key issues in vehicle stability control area. In this paper, a new method was proposed for the control structure and torque distribution on 4 in-wheel driven electric vehicle to take into account the tire slip energy. Combining the advanced chassis control HCC structure with optimal theory, the vehicle stability was achieved by optimally controlling the active front wheel steering and direct yaw moment, separated from HCC structure. More importantly, an increment minimization method of slip energy torque distribution was also proposed for HCC structure, and its related dynamic simulation was carried out based on UniTire slip energy model. Compared with the traditional control structure, that the vehicle is unstable without adjusting the front wheel steering and yaw moment, the structure proposed in the dissertation can ensure the lateral stability with minimizing the tire workload usage or minimizing the tire slip energy.

Stiffness Sensitivity Analysis and Vibration Energy Decoupling of Powertrain Mounting System

GAO Pu, LIU Hui, XIANG Chang-le, ZHOU Han, CUI Jin

2018, 38(9): 940-945. doi:10.15918/j.tbit1001-0645.2018.09.011

Abstract(788) PDF(370)

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Based on the 6 degrees of freedom(DOFs) vibration coupling model of the powertrain mounting system, the sensitivity analysis method was used to calculate the sensitivity of each natural frequency to the mounting stiffness in each direction. It is to identify the key rubber stiffness that affects the vibration in a certain direction, and to provide a theoretical guide for the improvement of the vibration characteristics in a certain direction. Then, taking the decoupling rate of each direction as the objective function, considering the drive shaft excitation, the sensitive vibration frequency region of the human body and the each direction vibration coupling conditions for the optimal constraint condition determination, a optimization algorithm was used to extract the optimal stiffness value of each direction and to improve vibration isolation performance of the mounting system. Aiming at the vibration deterioration of a certain powertrain system, a mounting system was designed by means of the sensitivity analysis method and vibration energy decoupling method. Finally, a vibration bench test was applied on the mounting system to verify the availability of the optimization design.

Non-Intrusive Polynomial Chaos Methods and its Application in Verification and Validation of Electromagnetic Models

WU Yue-qian, BAO Xian-feng, ZHOU Hai-jing

2018, 38(9): 946-952. doi:10.15918/j.tbit1001-0645.2018.09.012

Abstract(896) PDF(360)

Abstract:
A quantification analysis method was studied to verify and validate the electromagnetic models in this paper. Concretely, the non-intrusive polynomial chaos method was used to analyze the uncertainty response quantification of the simulation outcomes caused by the uncertainty input parameters of electromagnetic model. Based on the arithmetic and main procedures analyses, numerical experiment results confirm that the proposed method can be taken as a valuable tool to simulate the propagation of uncertainties and uncertainty quantification for electromagnetic models. Finally, taking a metallic crate with apertures as the electromagnetic model, the effect of uncertainty quantification of the incident angle input parameter on the electric field in the center of the mode was analyzed with the proposed method. Then the feature selective validation (FSV) was used to compare and evaluate the experimental and optimal simulation data, forming the evaluation grade.

The Technology Evaluation of S-Band Business Test Dual Polarization Radar(CINRAD/SA-D)

SHAO Nan, BU Zhi-chao, LI Bai, CHEN Yu-bao

2018, 38(9): 953-958. doi:10.15918/j.tbit1001-0645.2018.09.013

Abstract(785) PDF(385)

Abstract:
Taking the domestic first S-band business test dual polarization radar (CINRAD/SA-D) produced from Beijing Metstar Company as a study object, a comparison analysis was carried out with WSR-88D dual polarization radar from the aspects, including hardware upgrade, online/offline calibration method, signal processing and software technology. And the long-term calibration with internal signal source method and the results of the whole link calibration with light rain method were analyzed. The results show that the statistical variance of the differential reflectivity factor ZDR and the differential propagation phase DP with signal source method are 0.205 3 dB and 1.135 8°, respectively. The standard deviation of the ZDR can be controlled within 0.5 dB with light rain data selected from the key parameters. These results are comparable to WSR-88D weather radar. This work has a very important significance to guide the domestic dual polarization radar upgrade.

An Equivalent Test Method for the Critical Radiated Interference E-field Strength in Uniform fields and Reverberation Chambers

HU De-zhou, WEI Guang-hui, PAN Xiao-dong, JI Kai-fu

2018, 38(9): 959-965. doi:10.15918/j.tbit1001-0645.2018.09.014

Abstract(737) PDF(347)

Abstract:
In order to solve the problem of the poor correlation of the critical radiated interference E-field strength (CRIS) test results between reverberation chambers and uniform fields, a new CRIS test method was proposed for reverberation chambers, based on the equivalence of EUT received power under different test environment. The calculation formula of the CRIS in reverberation chambers was derived, and then verified under ideal conditions by building the model of a reverberation chamber and a uniform field with the electromagnetic simulation software FEKO. An experiment was designed in reverberation chamber and the open area with the ETS 3142E antenna as equipment under test. The results show that the CRIS obtained with the new method can be well consistent with the uniform field. With the omnidirectional radiation electromagnetic environment consideration, the relative errors are greatly reduced.

Research on the Rapid Preparation and Evaluation Method of Small Evolved Wire Antenna

HAN Guang-chao, HUANG He-jun, SUN Ming, ZENG San-you

2018, 38(9): 966-971. doi:10.15918/j.tbit1001-0645.2018.09.015

Abstract(766) PDF(334)

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Possessing the advantages of high gain, wide bandwidth, conformal and small volume, the small evolved wire antenna shows a extensive application prospect in the field of aerospace. Electromagnetic property test for the prototype of evolved antenna is an effective method to evaluate the rationality of its structural design. But the complex space geometry structure of the evolved antenna can seriously affect the manufacturing quality and efficiency of the evolved antenna prototype. According to the requirements of performance evaluation for the evolved antenna prototype during the structure designing process of small evolved wire antenna, the rapid prototyping technologies were studied to make small evolved wire antenna. Then two wire antenna prototypes were tested in feed voltage characteristics, which had been made by two methods such as metal rapid prototyping and non-metallic rapid prototyping combined with surface chemical copper plating. The results show that the feed voltage characteristic of small evolved wire antenna prototypes made by both kinds of rapid prototyping technologies can meet the requirement of design verification. It is completely feasible to rapidly fabricate the small evolved antenna prototype with complex space geometry structure by rapid prototyping method and evaluate its performance quickly.

Feature-Aided Tracking Association Algorithm for High Resolution Radar

LIU Hai-bo, LIU Yang, WANG E

2018, 38(9): 972-976,984. doi:10.15918/j.tbit1001-0645.2018.09.016

Abstract(854) PDF(346)

Abstract:
A tracking association algorithm based on points distribution feature was proposed to solve adjacent targets tracking problem of high range resolution radar. Combining the state information of the target with the distribution feature information extracted by standard deviational ellipse, the algorithm was designed to solve the problem of false tracking association of adjacent targets. The experimental result shows that the proposed algorithm can improve association accuracy and track quality.

Research on Parallel Processing Model for Block Cipher Based on Amdahl's Law

YAN Ying-jian, WANG Shou-cheng, XU Jin-hui, LI Gong-li

2018, 38(9): 977-984. doi:10.15918/j.tbit1001-0645.2018.09.017

Abstract(944) PDF(313)

Abstract:
In order to carry out the theoretical research and quantitative analysis of block cipher parallel processing, a block cipher parallel processing model based on Amdahl's law was established. Introducing data level parallelism in block, instruction level parallelism in block, data level parallelism among blocks and instruction level parallelism among blocks, a multiple dimension parallel processing model was developed to study the effects of algorithm parameters and parallelism parameters on cipher processing performance. The results show that, the algorithms with large parallel ratio possess a larger performance improvement space, and the development of any parallelism can improve the performance. But resource allocation and parallelism development should be carried on according to the algorithm structure and work modes for the specific application scenarios. This model can be taken as the guidance for the parallel processing architecture design, resource allocation and parallelism development of block cipher.

Theft Prediction Method Based on Ensemble Features Selection

SHI Tuo, JIANG Wei, ZHANG Jing-jing, WEI Xin-lei

2018, 38(9): 985-990. doi:10.15918/j.tbit1001-0645.2018.09.018

Abstract(776) PDF(361)

Abstract:
Theft crime is a difficult problem which shows a high occurrence and low breaking situation. It is an effective way to prevent the crime by predicting the cases in advance. So a new method was proposed based on bagging, following standards of accuracy and differences in feature selections, with the principle of high accuracy rate and difference rate. Heterogeneous learners were used to construct an ensemble learner to identify the occurrence factors, then the efficiency crime prediction was improved with less dimensions of factors. The results show that the proposed SEFV_Bagging algorithm can provide better generalization ability and stability, also its prediction accuracy is better. In addition, the algorithm needn't transcendental knowledge to set the feature subset dimensions manually, which shows obvious advantages in the application of criminal data analysis and forecasting.

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