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2017 Vol. 37, No. 1

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Mechanical Engineering
Numerical Study on the Cavitating Flow in a Rotary Cavitation Generator
LIU Ying, LI Xian-lin, CHEN Tai-ran, WANG Guo-yu, HUANG Biao
2017, 37(1): 1-4,14. doi:10.15918/j.tbit1001-0645.2017.01.001
Abstract(1408) PDF(1643)
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In order to investigate the mechanism of cavitation in an inner hole rotary cavitation generator, a numerical method was proposed to analyze the effect of different hole structures on the cavitation flow. Results show that when the pressure was reduced to the saturated vapor pressure of the water, cavitation will occur in the hole. Due to the high speed rotation of the rotor, there exist significant mass transfer between the water and vapor. The structural parameters of the cavitation generator, the depthL, diameterDand inclination angleαof hole directly affect the cavitation area and the transfer process between water and vapor. At a certain speed, an optimum value of the structural parameters exists. Under the condition of rotational speed of 2 850 r/min, the cavitation area and the transfer process between water and vapor seems more significant when the inclination angle of hole is 30 degree, the diameter is 23 mm and the depth is 35 mm.
Resonant Frequency of Cavitation Bubble in Grinding Fluid Under Ultrasonic Honing
GUO Ce, ZHU Xi-jing, WANG Jian-qing, LIU Guo-dong
2017, 37(1): 5-9. doi:10.15918/j.tbit1001-0645.2017.01.002
Abstract(1238) PDF(922)
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To reveal the resonance characteristics of cavitation bubble in the grinding fluid during ultrasonic honing, experimental observations on the grinding fluid of oilstone surface were carried out firstly using microscope VHX-600ESO. The cavitation bubble in the resonance state was observed. Based on the bubble dynamics, the resonant frequency equation was established for cavitation bubble in the grinding fluid during ultrasonic honing. The effect of ambient bubble radius,ambient pressure,gas content and ambient temperature of water and kerosene on bubble resonant frequency in the grinding fluid was numerically simulated respectively. The coordination relationship of ultrasonic frequency and cavitation bubble resonance frequency was verified by analyzing the displacement of a cavitation bubble. The results show that the resonance cavitation bubble occurs more easily in water than in kerosene at the same conditions, which is an important reason that water can be selected in coarse honing and kerosene can be chosen in fine honing.
A Planar Eddy Current Probe Based on Fractal Geometry
CHEN Guo-long, ZHANG Wei-min, PANG Wei-han, QIN Feng, GUO Yan
2017, 37(1): 10-14. doi:10.15918/j.tbit1001-0645.2017.01.003
Abstract(932) PDF(1519)
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A Koch geometry curve exciting eddy current probe was proposed based on fractal geometry and self-similar structure equipment. The FEMs were simulated with COMSOL multi-physics software. And an experiment platform was built to validate the eddy current probe. Compared with the circular exciting coils, the Koch geometry curve exciting eddy current probe can induce higher partial eddy current density in conductor and improve the distribution pattern of eddy current so as to improve the sensitivity of eddy current probe for small defect. Experiments validate that, the planar Koch curve exciting eddy current probe is useful in flexibility eddy current probe and can supply detection data for the system SHM.
Stationary Clearance Link Algorithm for Solving the Counter-Force in the Clearance Revolute Joint of Crank Slider System
CHEN Wei, YU Ru-fei, LI Pei
2017, 37(1): 15-18. doi:10.15918/j.tbit1001-0645.2017.01.004
Abstract(980) PDF(669)
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To accurately predict the performance of mechanisms with clearance joint and estimate its life, it is very critical to efficiently and accurately calculate the counter-force in the clearance revolute joint. In this paper, an independent and efficient algorithm, stationary clearance link algorithm, was proposed to calculate the force in the clearance bearing of crank slider system based on a clearance revolute joint model. Differing from Li's simplified algorithm based on the force in the ideal revolute joint, the stationary clearance link algorithm is only based on a clearance revolute joint model, it is not necessary to solve the reaction-force in the ideal revolute joint and nonlinear equation group. Initializing the stationary clearance link and simplifying the clearance counter-force in the clearance model, the practical clearance counter-force could be obtained by using the stationary clearance link algorithm with more efficient than Li's method. At the end, the feasibility and high-efficiency of the stationary clearance link algorithm are demonstrated by an example.
Study on Idling Characteristics of Hydraulic Torque-Retarder Assembly
WU Jing-yan, YAN Qing-dong, WEI Wei, AN Yuan-yuan
2017, 37(1): 19-23. doi:10.15918/j.tbit1001-0645.2017.01.005
Abstract(928) PDF(823)
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Definition of boundary conditions of hydraulic torque-retarder assembly (HTRA) in different working conditions is the basic of computational fluid dynamics (CFD). The performance of stator in locking condition was calculated by CFD based on some given hypotheses. In order to analyze the idling in traction and braking work condition of HTRA, combined with factorial design and quadratic-multinomial fitting, the prediction of rotation speed of brake impellers was obtained and the variation of brake impeller torque with impeller speed in traction condition was studied. In addition, the idling speed of stator impeller in braking condition was studied also. The prediction of traction and braking characteristics based on three-dimensional flow theory was verified feasibly and accurately by bench test.
Effects of Screw Arris Cross Section Shapes in the Melt Conveying Section of Single-Screw Extruder
FAN Tao, CHEN Zuo-bing, TANG Shuai, DONG Rui-jia, DU Jia-jia
2017, 37(1): 24-29. doi:10.15918/j.tbit1001-0645.2017.01.006
Abstract(969) PDF(998)
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A numerical analysis method was used to study the effects of the screw arris cross section shapes on the melting process in the melt conveying section in a PVC wood-plastics single-screw extruder. Several rheological experiments were taken to obtain the material viscosity of PVC wood-plastics. The power law model and an approximate Porto Nix model were employed together to get the viscosity model. Polyflow Polymat module was used to fit experimental data and to obtain the rheological parameters of required material in the numerical analysis. A three-dimensional model was developed with Pro/E and the corresponding mesh file was established by GAMBIT and Polyflow mesh superposition techniques (MST). Then the numerical analysis model was established after determining material parameters and boundary conditions. Based on the simulation results, the effects of screw arris cross section shapes on the flow field in melt conveying section of the PVC wood-plastics single-screw extruder was analyzed.
Optimal Selection of Task Allocation Schemes for the Multi-Crew Cabin Based on Mental Workload Prediction Technology
NIE Jun-feng, LIU Wei-ping, LIU Xi-xia, MA Jin
2017, 37(1): 30-36. doi:10.15918/j.tbit1001-0645.2017.01.007
Abstract(994) PDF(1170)
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In view of the basic trend that the number of armored vehicle cabin crew gradually has reduced under the informationized condition, the operational characteristic for armored vehicle cabin crew was analyzed and the mental workload prediction model was built based on multiple resource theory (MRT). A task allocation method under the mental workload prediction theory was proposed and the effectiveness of this method was illustrated by a case simulation analysis to solve the problem of armored vehicle crew cabin task allocation under the emergency condition for the warship formation. The results indicate that this method can describe the change of crew's mental workload clearly during the whole task. With this method, the selection of task allocation schemes can be quantized. It is an effective and feasible approach for scheme selection.
The Fluid-Structure Interaction Influence on the Vibro-Acoustic Characteristics of the Oil Pan
LIU Rui-jun, HAO Zhi-yong, ZHENG Xu, YANG Wen-ying, XIONG Fei, JIANG Hong-feng
2017, 37(1): 37-41,66. doi:10.15918/j.tbit1001-0645.2017.01.008
Abstract(1382) PDF(978)
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Calculations and experiments of free modes, constraint modes and wet modes were proceeded for a sandwich steel plate oil pan. Their well matching results show that, a coupled model is feasible. The comparison between coupled and uncoupled modes demonstrates that the modal shapes change and the entire modal frequencies decrease when taking the oil into account. The ordinary least square method was applied to fit the Rayleigh damping scale factors of the oil pan with and without oil, which indicated that the oil could hardly affect the damping of the sandwich steel plate oil pan. The vibration responses of coupled and uncoupled models calculated by multi-body dynamic method indicate that the entire acceleration amplitude is close to the experimental one as well as the variation trend. It is shown that the entire vibration of the coupled model is weaker, and is prominent below 500 Hz, especially in the vicinity of 330 Hz. Besides, the peak frequencies and the trend of the coupled model coincide with the experimental result much better. Furthermore, the comparison of the radiation noise calculated by the boundary element method demonstrates that an evident entire decline occurs after considering the oil in the range of 0~3 000 Hz except 333 Hz.
Analysis on Gas-Liquid Two-Phase Flows Characteristics Around a Plane
WANG Guo-yu, CUI Zhen-yu, HUANG Biao, GAO De-ming
2017, 37(1): 42-45. doi:10.15918/j.tbit1001-0645.2017.01.009
Abstract(1141) PDF(1041)
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Combining experiment and numerical simulation, the gas-liquid two-phase flow characteristics of plane were studied in this paper. Ventilated two-phase flows phenomenon was observed by a high-speed photograph, and its flow field was simulated by using the Level Set method and RNGk-εturbulence model. The results show that, the pressure of air layer coverage area is an important parameter to evaluate the formation of air layer:the location that high pressure between bubbles disappears is the initial location of air layer; when the air layer forms, the pressure tends to be consistent. Vortex structure has different characteristics during the air layer forming process. During the initial location kidney-shaped vortexes disappear gradually. When the air layer is formed, the vortexes regenerate. With the increase of space between pores, the forming locations of air layer move downstream due to transverse distance increases, but the interaction region changes little.
Research on Bang-Bang Control of EPB System in Vehicle Hill Start
WANG Hong-liang, GU Wen-hao, ZHANG Qing-ke, WANG Er-lie
2017, 37(1): 46-49. doi:10.15918/j.tbit1001-0645.2017.01.010
Abstract(1154) PDF(1234)
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Due to the difficulty of vehicle hill-starting operation, a hill-start strategy of pneumatic electronic parking brake (EPB) was proposed based on a Bang-Bang control. Analyzing the force change of hill-start, pneumatic EPB principle and the working characteristics of the solenoid valve, a control method combined with pulse width modulation (PWM) and pulse frequency modulation (PFM) was put forward to carry out the control of solenoid valve of EPB. The corresponding relationship between the driving torque and braking force during hill-start was studied. Ideal control target of the demand pneumatic pressure in hill-start was presented. The Bang-Bang control algorithm was taken as the core algorithm of the system control strategy to control the solenoid valve of EPB. Experiments carried out on the test vehicle show the better control effect and the feasibility of the control strategy.
Detection System Based on Open Multimedia Platform for Vehicle Safety
LIAN Jing, ZONG Yun-peng, LI Lin-hui
2017, 37(1): 50-55. doi:10.15918/j.tbit1001-0645.2017.01.011
Abstract(799) PDF(850)
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A hardware platform, a computer vision-based vehicle safety system was proposed, taking TI's DaVinci chip as the core processor and taking the embedded Linux in conformity to hardware configuration as the software development platform. The system was provided with some functions, including overspeed warning, vehicle distance judgment, accident assistance, vehicle position determination and vehicle anti-theft. Highway test results show that the missing rate of the algorithm is less than 5% and the false detection rate is less than 0.5%. Due to small size, low power consumption, high usability, high expansibility and upgradeability, this system can be widely used in various vehicles.
Dynamic Energy Programming Management Based on Smart Home for PEV Energy Storage
WU Xiao-hua, ZOU Yuan, YIN Xiao-feng, ZHANG Long
2017, 37(1): 56-60. doi:10.15918/j.tbit1001-0645.2017.01.012
Abstract(911) PDF(1187)
Abstract:
The on-board energy storages in PEVs (plug-in electric vehicles) make a new challenge and opportunity for the sustainable and distributed energy supply study. An energy management strategy of the smart home was proposed based on the dynamic programming method for PEVs energy storage. The power flow and the PEV batteries were modeled to adapt the specific home energy consumption structure. Constrained by the home energy demand and PEV charging power request, the electricity minimum consumption problem was formulated as the dynamic programming paradigm based on the time-varying electricity price and time-varying home power demand. Simulation results show the economy efficiency of the proposed method in different house power demand and the different drive condition. The daily total electric cost of smart home with PEV energy storage is 50% less than that of non-PEV case in summer weekdays, and 27% in winter weekdays.
Informatics and Control
Comparison of Positive and Negative Ionic Wind in Needle-to-Plate Corona Discharge
MIAO Jin-song, CHEN Yang, ZHANG Yu, JIN Zhen-gang
2017, 37(1): 61-66. doi:10.15918/j.tbit1001-0645.2017.01.013
Abstract(1096) PDF(2284)
Abstract:
The needle-to-plate configuration was employed in this paper to investigate the characteristics of ionic wind in corona discharge. The wind velocity and wind pressure were measured experimentally under different conditions including the voltage polarity, the applied voltage, the electrode spacing and the radius of needle tip and so on, to analyze the effect of these factors on ionic wind. The results show that the velocity increases linearly with the over-voltage. Under the same conditions the inception voltage of the positive corona is higher than the negative. The wind velocity of positive corona is higher than the negative at the same over-voltage and electrode spacing. And the polarity effect comes from the difference of developing mechanism between the positive and negative corona.
Fast Fixed-Point Simulation Technology for SAR Real-Time Imaging System
LI Bing-yi, XIE Yi-zhuang, DU Qing, CHEN He, YANG Chen
2017, 37(1): 67-70,76. doi:10.15918/j.tbit1001-0645.2017.01.014
Abstract(1115) PDF(1300)
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Fixed-point processing optimization can reduce the storage, improve the computing speed, is an effective way to reduce power consumption and storage, improve the real-time performance of synthetic aperture radar (SAR) real-time imaging system. Taking the well-known chirp scaling (CS) algorithm as example, the count of computations was analyzed in this paper. Radix-22algorithm of fast Fourier transform (FFT) as the main part of computations was adopted for fixed-point processing optimization, realized through a reasonable scale strategy with SystemC. Thus rapid system-level simulation of CS algorithm was implemented to provide a standard basis for FPGA implementation. Finally, test images from the raw lattice and area target data (16 384×16 384) were analyzed using fixed-point CS algorithm with 24 bits input word lengths. The simulation results meet the requirements of system indicators.
Real-Valued Two-Dimensional Propagator Method Using Cross-Correlation Matrix
LI Lei, LI Guo-lin
2017, 37(1): 71-76. doi:10.15918/j.tbit1001-0645.2017.01.015
Abstract(1072) PDF(1185)
Abstract:
In order to improve the accuracy of direction of arrival(DOA) estimation and decrease calculation capacity with low SNR, a new real-valued propagator method(PM) for 2-D DOA estimation algorithm using cross-correlation matrix (UC-PM) was proposed. Instead of array received data, cross-correlation matrix was constructed to suppress the effect of noise, and eigen-decomposition was replaced by a linear operator with low calculation capacity. Meanwhile, for reducing the complexity further, a new real-valued rotational invariance matrix was constructed to change eigen-decomposition and total least problems into real ones by unitary transformation. The simulation results showed that, being similar performance with 2-D ESPRIT algorithm, the performance of UC-PM is better than conventional PM algorithm with low SNR, and it has much lower calculation capacity than 2-D ESPRIT algorithm, which made the proposed algorithm of high practical value.
Time and Frequency Synchronization Algorithms for OFDM-UWB System Based on IEEE802.15.3c Standard
XUE Qian-nan, GE Li-jun, TAO Jin, LI Yue, ZHAO He
2017, 37(1): 77-82,92. doi:10.15918/j.tbit1001-0645.2017.01.016
Abstract(1173) PDF(1207)
Abstract:
In this paper, an intact time and frequency synchronization scheme was presented based on the preamble and the pilots for the OFDM UWB system specified in the IEEE802.15.3c standard. An anti-multipath separated sliding correlation detection (SSCD) method was proposed based on the Gray complementary sequences, and the positions of the correlation peaks were averaged to increase the anti-noise capability of timing. A sampling frequency synchronization method was also presented for doing phase equalization combined with integer sampling deviation pre-correction (PE-ISDPC), which could exploit the tolerance of the cyclic prefix to the integer sample deviation, reducing the implementation complexity. Simulation results show that the system has a better performance of time and frequency synchronization, and the complexity of overall scheme is low.
An Inter-Cell Scheduling Approach Based on Negotiation of Multi-Agent Coalitions
LI Dong-ni, ZHOU Peng-yu, TIAN Yun-na, ZHENG Dan
2017, 37(1): 83-87. doi:10.15918/j.tbit1001-0645.2017.01.017
Abstract(1326) PDF(1197)
Abstract:
To solve the problem of the workpiece inter-cell move in inter-cell scheduling for the cellular manufacturing system, an inter-cell scheduling method was proposed based on multi-agents coalitions (MAC). Considering the flexible inter-cell processing routes, a distributed negotiation mechanism was adopted to form grading coalitions and to carry out negotiation scheduling, so as to improve the performance of global optimization as well as reduce the communication. Experiments were taken to verify the proposed algorithm. The results show that the proposed algorithm can provide better performance with respect to the mean delay than the widely used combinatorial heuristic rules.
A Novel Algorithm on Adaptive Image Compressed Sensing with Sparsity Fitting
WANG Xiao-hua, XU Xue, WANG Wei-jiang, GAO Dong-hong
2017, 37(1): 88-92. doi:10.15918/j.tbit1001-0645.2017.01.018
Abstract(1282) PDF(1887)
Abstract:
When the image is compressed adaptively with compressed sensing theory, the determination of sampling rate and sparsity threshold were highly subjective. In order to solve the problem, an accurately adaptive sampling algorithm with sparsity fitting was proposed in this paper. This algorithm determines the minimum sampling rate under certain sparseness to meet the PSNR requirements by iteration, and an optimal objective function of sparsity-sampling rate choices was obtained with the method of least squares fitting sparsity and sampling rate data. The adaptive sampling algorithm was simulated based on TVAL3. Experimental results show that the PSNR values of reconstructed images are higher than that with the same fixed sampling rate algorithm, and the PSNR difference of clear texture distinction images can reach more than 3.5 dB. Compared to the roughly adaptive algorithm, when the average sampling rate is lower than that, the reconstructed image obtains a higher PSNR value.
Police Patrol Path Planning Using Stackelberg Equilibrium Based Multiagent Reinforcement Learning
XIE Yi, GU Yi-jun
2017, 37(1): 93-99. doi:10.15918/j.tbit1001-0645.2017.01.019
Abstract(1177) PDF(1979)
Abstract:
The patrol path planning has been simplified with state-of-art algorithm into two-person game in grid world, ignoring the existence of attackers. In order to deal with the problem of realistic patrol path planning, a novel multi-agent reinforcement learning algorithm was proposed. An optimum patrol path was planned in a circumstance that multiple defenders and attackers formed the multi-target configuration. Considering the asynchronism of the actions taken by many defender and attacker, a strong Stackelberg equilibrium was taken as the action selection of players in the proposed algorithm. To verify the proposed algorithm, several patrol missions were tested. The qualitative and quantitative test results prove the convergence and effectiveness of the algorithm.
A Fast Calibration Method for the RF Relative Measurement Sensor
MU Wei-qing, LIU Rong-ke, YANG Xin-xin, WANG Zi-jie
2017, 37(1): 100-105. doi:10.15918/j.tbit1001-0645.2017.01.020
Abstract(1159) PDF(875)
Abstract:
In formation flying system, the relative position and attitude of spacecraft can be measured by the radio frequency (RF) relative measurement sensor.In order to verify its measurement precision, a calibration method of RF relative measurement sensor calibration was proposed based on laser tracker. In the process of frame building, methods of fitting sphere and circle to determine coordinate origin and axis based on the least squares were proposed,to solve the problem of larger fitting error. The inherent relationship of coordinate system was taken to design a fast conversion method of relative coordinate. The simulation experiment results show that origin fitting errorσRMS=0.120 764 mm, axis fitting errorσRMS=0.207 093 mm, the scope of coordinate frame conversion error 0.30~0.75 mm, they can satisfy the requirement of RF relative sensors calibration.
Design of Mars Repeat Sun-Synchronous Orbit Based on the Multi-Approximate Revisit Period
DU Bu-zhi, GAO Fei, ZHANG Xu-qi, JIA Xiao
2017, 37(1): 106-110. doi:10.15918/j.tbit1001-0645.2017.01.021
Abstract(1582) PDF(1465)
Abstract:
Based on the analysis of the mathematical model of Martian repeat Sun-synchronous orbit, an approximately revisit cycle algorithm of return period was designed. Rounding processing the repeat factor,combining with the revisit characteristic function of the return track and judging the number of revisiting pitches spacer, the optimal approximate and suboptimal approximate revisit cycle were designed to achieve higher time resolution and cover the surface of the Mars. Further the relationship between the optimal regression cycle family and equatorial surface coverage of Mars was analyzed, and the orbit parameters corresponding to optimal regression cycle family was computed. It provides a reference for the track design for the initial exploration of Mars.

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