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2018, 38(1): .

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2018, 38(1): .

Abstract(752) PDF(553)

Abstract:

Simulation of Compressible Multi-Material Flows with Large Deformation Based on Gridless Method

WANG Liang, XU Hou-qian, XUE Rui, ZHANG Jun

2018, 38(1): 1-5. doi:10.15918/j.tbit1001-0645.2018.01.001

Abstract(1339) PDF(659)

Abstract:
The dynamic gridless points were used to track the complex deformation of the free movable interfaces, and the least-square gridless method for the compressible multi-material flows was developed. The material interface was treated as a series of dynamic gridless points with a dual definition. The ghost fluid method (GFM) was applied to deal with the interface points and create ghost fluid points, and the multi-material flow was divided into several independent single material flows. In order to restrain spurious numerical oscillations on material interface, the solver of the local Riemann problem on the interface was introduced into updating the flow parameters of the interface points and ghost points. Local cloud rebuilding algorithm was utilized to deal with dynamic clouds of points. AUFS scheme was extended to calculate the numerical convective flux of the Euler equations in the ALE form. The one-dimensional shocktubes problems and two-dimensional complicated problems with large deformation were simulated. The result demonstrates that the proposed gridless method is able to keep track of the material interfaces and the shock waves accurately, and makes a success of rebuilding the local deformable region.

Predictive Modeling of Cutting Force Based on Local Friction Coefficient Model

ZHANG Cheng-yan, ZHANG Fa-ping, YANG Rui-sheng, PANG Lu, LU Ji-ping

2018, 38(1): 6-11,19. doi:10.15918/j.tbit1001-0645.2018.01.002

Abstract(1004) PDF(777)

Abstract:
Considering the friction of dull radius and the flank face at cutting edge, a new cutting force prediction model was established based on local friction coefficient model of steady-state orthogonal cutting. Mathematical stress analysis models were set up respectively for friction zones on rake surface, flank surface and cutting edge surface. A series of orthogonal cutting experiments were conducted with high-speed steel tool (W6Mo5Cr4V2Al) and 20Cr2Ni4 alloy steel. Primary cutting force and radial thrust force were detected by three-dimensional dynamometer. In the end, the effect of cutting speed, cutting depth and tool rake angle on the magnitude of cutting forces were analyzed. Results show that, the predicted cutting forces calculated from the prediction model are consistent with the test data. It turned out that cutting force has a slightly tendency to decrease with the increase of cutting speed and tool rake angle, significantly increased with the increase of cutting depth.

Research on Stratified Mixture Lean Burn of Opposed-Piston Two-Stroke Gasoline Engine

MA Fu-kang, ZHAO Chang-lu, ZHANG Fu-jun, WANG Hao

2018, 38(1): 12-19. doi:10.15918/j.tbit1001-0645.2018.01.003

Abstract(997) PDF(699)

Abstract:
For the characteristics of small bore and long stroke for opposed-piston two-stroke gasoline engine, an asymmetric spray mode on exhaust and intake side was proposed in this paper and the spray direction was optimized with CFD AVL-Fire software to form the homogenous mixture in full load. The effect of two-stage injection strategy with different injection timing and injection ratio on mixture stratification and lean burn organization were simulated based on optimized spray direction. The results show that the increase of injection angle in intake side can improve uniformity index of mixture and the increase of injection angle in exhaust side can reduce fuel evaporation. The second injection ratio affects stratified mixture distribution and the second injection timing affects stratified mixture uniformity. When the injection angle in intake side is 30° and the injection angle in exhaust side is 15°, first injection timing at 220℃A and the second injection timing at 270℃A with 20% total fuel quantity finally lead to ideal in-cylinder mixture stratified distribution. In part load, stratified mixture distribution can shorten 30% time of flame developing period and shorten 15% time of rapid burning period compared with homogeneous mixture.

Engine Fully Variable Valve Parameters Coupling Study Based on Multiple Regression Analysis

LU Yong, HE Feng-shuo, LI Jian, HOU Xiu-qin, LÜ Kun, LI Bo, XIONG Li-jun

2018, 38(1): 20-25. doi:10.15918/j.tbit1001-0645.2018.01.004

Abstract(1316) PDF(576)

Abstract:
To obtain the optimum solution of valve running parameters, the coupling rules among valve parameters were analyzed based on a simulation model of four-cylinder diesel engine, the multivariate regression analysis method, and a valve parameter coupling data base by simulation orthogonal experiments. Further more, an electro-hydraulic fully variable valve model of the engine was built to verify the actual optimal solution. The combined simulation results show that, the optimal solution is improved by 3.8% than the original optimal power, and the average speed of inlet and outlet valve is decreased by 31.1% and 37.5% respectively in the premise of improving the performance of the engine. Finally, the optimal solution of the valve parameters obtained by the regression model satisfies the driving ability of electro-hydraulic driving system and improves the driving efficiency effectively.

High Speed Drive Method of Permanent Magnet Synchronous Motor Based onVoltage Proportional Contraction Harmonic Injection

WANG Lei, JIANG Rui

2018, 38(1): 26-32. doi:10.15918/j.tbit1001-0645.2018.01.005

Abstract(1118) PDF(835)

Abstract:
In order to raise the utilization ratio of permanent magnet synchronous motor bus voltage,and reduce the voltage vector angular deviation, a method with harmonic injection pulse width modulation was proposed based on voltage ratio zoom. In harmonic injection with look-up table type, it was taken as advancing the current respond rate to reduce the harmonic value computation time. A pulse width modulation method of voltage ratio zoom was utilized to eliminate the calculation deflection of voltage vector, and raise the utilization ratio of the bus voltage.The simulation and experimental results show that this kind of pulse width modulation can improve the utilization ratio of the bus voltage and motor response ability under high speed command.

Design and Analysis on the Structure of Imitating Cheetah Quadruped Robot

MA Zong-li, LÜ Rong-ji, LIU Yong-chao, ZHANG Pei-qiang, WANG Jian-ming

2018, 38(1): 33-39. doi:10.15918/j.tbit1001-0645.2018.01.006

Abstract(1401) PDF(735)

Abstract:
In order to meet the requirements of high speed running, the flexible spine and the leg structure with high cushion performance for quadruped robot, a flexible spine and hydraulic driving hind limb structure were designed for the running quadruped robot based on hydraulic pressure technology. The spine was designed with variable cross section beam to form flexible in the middle. The leg structure was designed with hip joint and knee joint, 3 DOFs. The hip joint was designed with two active DOFs, roll-DOF and pitching-DOF; the knee joint was only with passive pitching-DOF. The mechanical performance of flexible spine was analyzed. Stiffness characteristics and kinematics of the leg structure were analyzed. And the bound gait of robot was simulated. The simulation results show that, the quadruped robot with the flexible spine and the leg structure with nonlinear stiffness can run stably with higher speed in Bound gait, and the foot contact force is low, verifying the feasibility of the designed spine and the leg structure.

A Spectral Super-Resolution Method of LCTF Based on Compressive Sensing

WANG Qi, MA Ling-ling, LI Chuan-rong, ZHOU Yong-sheng, TANG Ling-li

2018, 38(1): 40-45,72. doi:10.15918/j.tbit1001-0645.2018.01.007

Abstract(1048) PDF(619)

Abstract:
The liquid crystal tunable filter (LCTF) is used as micro spectrometer in many measuring fields for its simple and efficient light filter function. But the spectral resolution of LCTF is limited by its bandwidth, and the hardware cost and larger measure data are the problem in higher resolution measuring. In this paper, combining the compressive sensing with the LCTF spectral measuring method, a new model was proposed to get the object spectral curve with a superior spectral resolution than the system bandwidth. In the model, the data calculation of LCTF spectral measurement was correlated with its transmittance function of corresponding wavelength. Analysis results show that, the measurement matrix in the proposed model possesses a good incoherence property. The simulation results of real earth object's spectrum show that, the spectral curve of 128 band pearl stone can be reconstructed with only 32 measurements, the mean error of reflectance is only 0.75% with a certain noise repellency, and the spectral details can be distinguished while traditional method cannot work.

Design of Tracking Guidance Law Based on Neighboring Optimal Control

LI Ning-bo, LEI Hu-min, ZHOU Jin, SHAO Lei, WANG Bin

2018, 38(1): 46-51. doi:10.15918/j.tbit1001-0645.2018.01.008

Abstract(1469) PDF(561)

Abstract:
To improve the midcourse guidance process of the interception against hypersonic targets in near space, a novel trajectory tracking guidance law based on neighboring optimal control (NOC) was designed. Firstly, the nominal trajectory satisfying terminal and path constraints were generated by Gauss pseudospectral method. Secondly, in order to track nominal trajectory accurately, the first order necessary conditions were further differentiated to second order to obtain the second-order optimal updating trajectory in the neighborhood of nominal trajectory. Finally, based on indirect Gauss pseudospectral method, the transformed two-point boundary value problem was discretized to algebraic equation for matrix inverse operation at Legendre-Gauss (LG) point and then feedback control law was obtained using nominal trajectory. Simulation results show that this method can eliminate tracking error effectively and satisfy the requirements of on-line implementation.

Formation and Metallization Process Study on High Aspect Ratio Through-Glass-Via (TGV) Within Photosensitive Glass

LIN Lai-cun, WANG Qi-dong, QIU De-long, WU Heng, XUE Kai, YU Da-quan, CAO Li-qiang

2018, 38(1): 52-57. doi:10.15918/j.tbit1001-0645.2018.01.009

Abstract(1116) PDF(755)

Abstract:
The electromagnetic simulations of through glass via (TGV) and through silicon via (TSV) were performed in this paper. Simulated results show that the insertion losses of TGV and TSV at 20GHz are -0.024dB and -1.62dB respectively, representing a much higher performance of TGV. Based on photosensitive glass, 7:1 high aspect ratio of TGV was obtained by using high speed wet etching method, achieving better array profile, uniformity and less 1μm roughness of TGVs. Filling process was simulated under different current densities. Results show that smaller current density is helpful to achieve uniform filling due to the improvement of crowding effect of current density at the top and bottom of TGVs, the development speed of copper layer is more uniform and slow. A verification filling experiments were carried out under the current density of 1ASD. Results show a high filling quality, copper layer develops uniformly in 120μm TGVs, the seams are small in 70μm TGVs.

Design and Optimization of High Speed PLL Based on 90 nm CMOS Process

WANG Zheng-chen, WANG Xing-hua, ZHONG Shun-an

2018, 38(1): 58-62. doi:10.15918/j.tbit1001-0645.2018.01.010

Abstract(1365) PDF(686)

Abstract:
A high speed phase locked loop (PLL) was designed based on TSMC 90nm CMOS process. In order to optimize phase noise and reference spur, the main modules of PLL such as charge pump and LC voltage controlled oscillator (VCO) were analyzed and improved. The design method of multi-modulus divider (MMD) was studied in detail. The layout of the high speed PLL was optimized and whole chip area was arranged in 490μm×990μm. The testing results show that, the in-band phase noise can reach -90dBc at 1MHz frequency offset and the reference spur is -56.797dBc.

SEE Evaluation Method for DFF Cell Based CMOS/SOI Technology

LI Hai-song, JIANG Yi-hu, YANG Bo, YUE Hong-ju, TANG Wei

2018, 38(1): 63-67. doi:10.15918/j.tbit1001-0645.2018.01.011

Abstract(1063) PDF(642)

Abstract:
A dual shift-register chain structure was proposed for D flip-flop (DFF) cell's single-event effect (SEE) evaluation. Based the structure, the SEE performance of radiation-hardened DFF cell with common structure and made of 0.35μm CMOS/SOI technology was evaluated in Beijing Accelerator Nuclear Physics National Laboratory and Lanzhou National Laboratory of Heavy Ion Accelerator. The experimental results show that the DFF cells can be immune from single-event latch-up (SEL) and have high quality for standing up to single-event upset (SEU).

Optimization on Non-Cyanide Pulse Plating Applied to Silicon-Based RF-MEMS Band-Pass Filters

YAN Yang-yang, LIU Bin, WANG Shi-wei, LU Wei, DING Ying-tao

2018, 38(1): 68-72. doi:10.15918/j.tbit1001-0645.2018.01.012

Abstract(950) PDF(774)

Abstract:
RF-MEMS technique, which combines MEMS fabrication technologies and microwave theories, provides a new solution for the development of key components of millimeter-wave radar and advanced communication systems to be much smaller and higher density integrated. In order to optimize the gold layer deposition technique for the silicon-based RF-MEMS band-pass filter fabrication, a pulse plating technique was proposed based on the environment friendly non-cyanide sulfite gold salts solutions. By optimizing key process parameters including current density, duty ratio, positive and negative pulse time ratio, pulse frequency, temperature and stirring speed, the optimized electroplating parameters were obtained and were successfully applied to the fabrication of silicon-based dual-layer self-shielded RF-MEMS band-pass filters. The study provides a fundamental guidance to the fabrication of RF-MEMS correlation devices.

A Semi-Supervised Classification Method for Motor Imagery EEG

WANG Xiang-zhou, GUO Yi-kang, LIN Ying-zi, ZHENG Shu-hua

2018, 38(1): 73-78,84. doi:10.15918/j.tbit1001-0645.2018.01.013

Abstract(1407) PDF(546)

Abstract:
A sequential updating semi-supervised classification based on training iterations was proposed for the two-class motor imagery task in brain-computer interface. Firstly, making use of multiple autocorrelation analysis, the training samples with high confidence were selected as initial training set. Then common average reference and common spatial pattern were used for pre-processing and feature extraction, respectively. Lastly, support vector machine was applied to test new samples. The samples with low confidence were removed successively according to the iterations. The remains were used to retrain the model to optimize the parameters of both feature extractor and classifier. The proposed method was applied to Dataset Ⅱa of BCI Competition IV to verify its validity. The results show that the classification accuracy is higher than other algorithms on the occasion where training samples are not enough. It can provide a new solution for the real-time BCIs.

Research on Wide Range Signal Detection Method for Metal Shell Vibratory Gyro

LIU Ning, SU Zhong, LI Qing

2018, 38(1): 79-84. doi:10.15918/j.tbit1001-0645.2018.01.014

Abstract(999) PDF(543)

Abstract:
Traditional multi-loop angular-rate detection methods cannot meet the need for wide range angular rate detection of metal shell vibratory gyro. A new method was proposed based on adaptive sliding mode controller to detect wide range angular rate signal. Analyzing the dynamic equation of typical metal shell resonator, a state equation was established involving disturbance and perturbation parameter. Getting proportion integral sliding mode surface with exponential approach law, a kind of sliding mode controller was designed for metal shell vibratory gyro to effectively estimate the wide range angular rate. The simulation and experiments results prove that the detection method can steadily control the metal shell resonator's mode shape and effectively measure the wide range angular rate. It is adapt to the wide range of environmental applications for metal shell vibratory gyro.

Near-Duplicate Video Retrieval and Localization Using Relative Levenshtein Distance Similarity

ZHAO Qing-jie, WANG Hao, LIU Hao, ZHANG Cong

2018, 38(1): 85-90. doi:10.15918/j.tbit1001-0645.2018.01.015

Abstract(1533) PDF(535)

Abstract:
To effectively retrieve and locate near-duplicate videos, a novel approach of video retrieval and localization was proposed based on relative Levenshtein Distance similarity (LD). In the algorithm, two major components were included, named local descriptor based video coding and relative Levenshtein Distance similarity-based video retrieval and localization. About the local descriptor based video coding, the video key-frames were extracted firstly from data base; then Root-SIFT feature descriptors were extracted from key-frames and all descriptors were clustered to generate a codebook with the Hierarchical K-Means; lastly, each key-frame was assigned a unique visual word and code. About the relative Levenshtein Distance similarity-based video retrieval and localization, each query video was encoded firstly, and then the near-duplicate videos were filtrated, near-duplicate segments were located, and the retrieved videos were re-ranked with the relative Levenshtein Distance similarity-based algorithm. The experimental results show that the LD algorithm can achieve a 8.55% higher effect on the averageF₁evaluation criterion than the algorithm proposed by Yeh et.al, and the NDCR is reduced to 29%.

A Foreground Detection Method Based on Cross-Covariance Subspace Estimation

QIN Ming, LU Yao

2018, 38(1): 91-95. doi:10.15918/j.tbit1001-0645.2018.01.016

Abstract(870) PDF(708)

Abstract:
In this paper, a novel background modeling method was proposed based on cross-covariance subspace estimation to detect foreground in complex scenarios. The cross-covariance based 2DPCA (2 dimensional principal component analysis) method can preserve more image covariance information, which makes it suitable for background modeling. Therefore the cross-covariance based 2DPCA method was introduced into background modeling field and a correlative incremental algorithm was proposed for adaptively estimating background. Considering the sparsity and the continuity of the foreground, the method was used in foreground detecting accurately. Quantitative experimental and qualitative analysis results show that the proposed method can estimate the background information accurately and robustly in complex scenarios.

Research on Trust Level Model Based on Static Game in the Cloud Environment

ZHANG Guang-hua, PANG Shao-bo, ZHANG Yu-qing, SUN Li-min

2018, 38(1): 96-101. doi:10.15918/j.tbit1001-0645.2018.01.017

Abstract(921) PDF(567)

Abstract:
In order to solve security threats of the system caused by the non-cooperative behavior of individual users in the open cloud environment, a trust model based on "inverted pyramid" classification was proposed. Firstly, the cooperative attitudes of the cloud users were used as a basis for calculating their reputation values. Secondly, the cloud users were managed hierarchically according to their accumulated reputation values. Thirdly, the selection strategies of the users of different levels were judged by complete information static game theory in an interaction process. Simulation results and analysis show that the trust level model can distinguish untrusted users in the system, stimulate cooperative behavior of the users, and improve the ability of system in the prevention of security threats.

Optimized Design of the Navigation Filter in Ultra-Tight GPS/INS Integration

ZHANG Xi, MIAO Ling-juan, SHEN Jun, SHAO Hai-jun

2018, 38(1): 102-107. doi:10.15918/j.tbit1001-0645.2018.01.018

Abstract(1252) PDF(767)

Abstract:
Under extremely high dynamic conditions, GPS receiver cannot exactly track carrier frequency, even if it is equipped with baseband signal pre-filter. Since the tracking errors of different channels are not independent any longer after passing through the traditional navigation filter, the ultra-tight GPS/INS integration may crash. To solve this problem, the pseudorange rate tracking errors were modeled and treated as the state variables of the navigation filter. However, the computational complexity of the filter with expanded dimension is too high. So on the premise of keeping navigation accuracy, dimension reduction was carried out through the use of inter-satellite single-difference and two-stage Kalman filtering algorithm. Finally, a semi-physical simulation, based on the gyro and accelerometer measurements telemetered in a rocket missile test, validates the effectiveness of the proposed methods.

StrongC^*-Algebra-Valued Metric Space and a Fixed Point Theorem

MA Zhen-hua, SHEN Cong-cong, ZHANG Xin

2018, 38(1): 108-110. doi:10.15918/j.tbit1001-0645.2018.01.019

Abstract(1151) PDF(496)

Abstract:
Based on the concept ofC^*-algebra-valued metric spaces, the definition of strongC^*-algebra-valued b-metric spaces was introduced, and furthermore, a corresponding fixed point theorem was proven. As an application, the existence and uniqueness of a kind of operator equation was presented.

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