bob手机在线登陆学报自然版

2017, 37(3): .

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2017, 37(3): .

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Application of Matrix Theory in Acoustic Testing Method for Interfacial Debonding of Adhesive Structure

DING Jun-cai, WU Bin, HE Cun-fu

2017, 37(3): 221-226,249. doi:10.15918/j.tbit1001-0645.2017.03.001

Abstract(1271) PDF(1080)

Abstract:
It is a difficult and challenging subject for ultrasonic inspection to test and evaluate the debonding interface of adhesive structure. Assuming, the debonding interface layer to be a fluid thin layer, the acoustic reflection and transmission coefficient expressions were derived based on the transfer matrix method for the body waves striking debonding structure with fluid-solid (gas-solid and liquid-solid) coupling interfaces. Firstly, this method was applied to a two-layered structure and the correctness of the method was verified by comparing with the existing results. Then, the influences of the incident angle and frequency changes of the acoustic wave on the body wave propagation characteristics were analyzed for adhesive structure with rigid interfaces and debonding structure with fluid-solid coupling interfaces. The results show that the propagation modes of the body waves in the multilayered structure mainly dependent on the incident angle, frequency and other parameters. The rigid interfaces, gas-solid and liquid-solid coupling interfaces can be distinguished in the case of the incident angle and frequency of the acoustic wave are appropriate. The research results provide a theoretical reference for identifying the adhesive interface debonding with ultrasonic spectrum technique.

Geometry Design and Analysis of Eccentric Curved-Face Gear Pair

LIN Chao, WU Xiao-yong, ZENG Dong

2017, 37(3): 227-232. doi:10.15918/j.tbit1001-0645.2017.03.002

Abstract(1138) PDF(897)

Abstract:
A kind of curved-face gear pair was proposed to transfer rotation and movement of the intersecting axes. According to the theories of gear transmission, the transmission ratio of eccentric curved-face gear pair was designed, and the pitch curve of eccentric curved-face gear pair was deduced. Through the principle of gear engagement, the meshing equation and tooth surface equation were built, and the change law of pressure angle of gear pair was studied, besides, a 3D model of eccentric curved-face gear pair was built with API in SolidWorks. The results validate the correctness of the design method of eccentric curved-face gear pair, and show that it can realize larger transmission ratio and pressure angle, and the gear pair can meet more potential engineering application.

Effects of Hold Down Device on the Slipper's Dynamic Characteristics

LIU Hong, HU Ji-bing, PENG Zeng-xiong, ZHAO Hong-mei

2017, 37(3): 233-238. doi:10.15918/j.tbit1001-0645.2017.03.003

Abstract(1270) PDF(743)

Abstract:
The effects of hold down device on the slipper's dynamic film was presented. Considering slipper's tilt and pressure-elasticity effect of slipper's lubrication surface, introducing the interaction between slipper and different hold-down device and according to the external forces and moments on slipper, the dynamic equations to describe micro-movement of slipper were established. Variation laws of the slipper's film thickness within a complete rotating period of the barrel were obtained by solving the kinetic equation and lubrication governing equation simultaneously. The different hold-down device's effect on slipper's dynamic characteristics was discussed. The results show that oil-film thickness decreases if the hold down device with central spring is used to alleviate the slipper's tilt. Hold down device with fixed clearance doesn't influence the oil-film's thickness during the delivery region and slipper's minimum film can be increased at suction region. Therefore the effect to alleviate the slipper's tilt is remarkable.

Plasticity of Fully Carburized Material 18CrNi4A Under High Temperature and Strain Rate

WANG Yan-zhong, CHEN Yan-yan, WANG Zeng-qiang, WANG Guo-cheng

2017, 37(3): 239-243. doi:10.15918/j.tbit1001-0645.2017.03.004

Abstract(1085) PDF(1269)

Abstract:
To evaluate the residual stresses on the ground surfaces of gears made of carburized 18CrNi4A and improve the fatigue life, fully carburized specimens were prepared and tested by the split Hopkinson pressure bar(SHPB) method, achieving a series of stress-strain curves under several combinations of temperatures and strain rates. Then parameters of the Johnson-Cook (J-C) plasticity model were fitted and applied to a numerical model of a grinding process. The simulation result agrees well with the relevant test.

Study on the In-Cylinder Flow Process of Diesel Free-Piston Linear Generator

SONG Yu, FENG Hui-hua, LI Lin-ke, ZUO Zheng-xing

2017, 37(3): 244-249. doi:10.15918/j.tbit1001-0645.2017.03.005

Abstract(1103) PDF(979)

Abstract:
As the piston movement is of great importance to the in-cylinder flow process, the piston movement characteristics of the diesel free-piston linear generator (FPLG) were analyzed with the equivalent speed transform method. Based on the analysis results, the influence of the piston movement on the in-cylinder flow was studied by using theoretical calculation and three-dimensional numerical simulation respectively. The results demonstrate that compared with the traditional engine, the equivalent speed of FPLA is higher both near TDC and BDC, but lower at the midterm of the stroke. It leads to a higher peak value of squish flow, shorter duration and different curves of mean turbulence kinetic energy.

Stability Control System of Distributed Drive Electric Vehicles Using Linear Active Disturbance-Rejection Control

LIU Gang, JIN Li-qiang

2017, 37(3): 250-254. doi:10.15918/j.tbit1001-0645.2017.03.006

Abstract(1131) PDF(1061)

Abstract:
An electric vehicle stability control strategy based on hierarchical control strategy was proposed in this paper. The linear active disturbance rejection control (LADRC) was adopted to calculate the desired yaw moment based on the yaw rate and side-slip angle. The right value of objective function was adjusted for control allocation based on vehicle state and road condition. A quadratic programming method was designed to calculate the motor output torque. Finally, the proposed control strategy was validated under the hardware-in-the-loop (HIL). The results show that the variables of the proposed controller can track the target parameter well. Comparing the vehicle under the PID control with no control, the vehicle under the proposed control can improve vehicle stability effectively with good convergence.

New Processing Algorithm Using Spatial Correlation Threshold Filtering for Faint Laser Signal Through Foggy Media

YAO Guo-zhong, WANG Zheng-jiang, SHEN Li-zhong, WANG Gui-yong

2017, 37(3): 255-259,273. doi:10.15918/j.tbit1001-0645.2017.03.007

Abstract(1005) PDF(1111)

Abstract:
In order to overcome the difficulty of extracting the faint laser signal feature in foggy environment, a wavelet spatial correlation threshold filtering method was proposed based on the study of wavelet filtering algorithm. The idea and principle of the spatial correlation threshold filter were elaborated, and a method was studied particularly for filtering threshold selection. Comparing with spatial correlation filtering method, the new spatial correlation threshold filtering method shows better filtering effect for the faint laser signal in foggy environment. The experiments results in different fog density and different signal to noise ratio (SNR) show that, the spatial correlation threshold filtering can effectively rule out most of the noise and maintain weak laser signal characteristics. The spatial correlation threshold filtering method is more suitable for processing faint laser signal and feature extraction in fog media.

Application of Spatial Statistical Analysis in Decomposition of Machining Errors for Free-Form Surfaces

CHEN Yue-ping, JIN Long, LU Hai-yan, FENG Zhi-jun, CHEN Yan-hui

2017, 37(3): 260-266. doi:10.15918/j.tbit1001-0645.2017.03.008

Abstract(1056) PDF(930)

Abstract:
To analyze machining errors of free-form surfaces, a spatial statistical analysis method was presented for the machining errors decomposition, forming systematic errors and random errors. Firstly, the machining errors were analyzed with the method to judge the spatial autocorrelation of these errors. Then a regression model was built based on B-spline surfaces for the deterministic surface. And the adequacy of the regression model was analyzed through calculating the residual errors of all the measured points. Once the residual errors were of spatial independence, the residual errors could be treated as random errors, and the systematic errors were easily obtained. A free-form surface simulation was taken to validate the method. Results show that the error decomposition is accurate and effective. According to the systematic errors of the process system obtained in the surface machining on a NC machining center, the compensation made for the machining error has significantly improved the machining accuracy of free-form surface.

The Impacts of Upstream Linear Bus Stop on Car Delays

LIANG Shi-dong, ZHAO Shu-zhi, MA Ming-hui, LIU Hua-sheng, LU Chun-xiu

2017, 37(3): 267-273. doi:10.15918/j.tbit1001-0645.2017.03.009

Abstract(1211) PDF(844)

Abstract:
To analyze the impact of linear upstream bus stop on traffic efficiency, the shockwave theory was employed to estimate car delays caused by linear upstream bus stop, when the traffic flow was stable. The car delays consist of two parts which take place at immediate upstream of bus stop and at signalized intersection. The additional car delays can be obtained as the difference between traffic flow effected by bus stop or not. Finally, the additional car delay model based on shockwave theory was implemented by the numerical analysis to get the relationship between additional car delays and some traffic parameters including traffic flow, bus dwell time, signal cycle and green ratio quantificationally. The results of numerical analysis show that the additional car delay increases along with the growing dwell time and traffic flow, and with the decreasing of signal cycle and green ratio. More specially, bus dwell time and traffic flow are major factors.

An Algorithm of Asymmetric Three Workshops Integrated Scheduling with Batch Equalization Processing

XIE Zhi-qiang, ZHENG Fu-ping, XIA Ying-chun

2017, 37(3): 274-280. doi:10.15918/j.tbit1001-0645.2017.03.010

Abstract(1099) PDF(564)

Abstract:
Aiming at the schedule problem of complex products in the asymmetric three workshops, an algorithm was proposed based on batch equalization processing for three workshops integrated scheduling. In the proposed algorithm all devices were classed into three categories, asymmetric, local symmetric and symmetric resources according to workshop attribute that devices belonged to. For the asymmetric resources that the process occupied, the process was assigned to the workshop the device belonged to, and others were adopted according to batch processing. On the one hand a part of processes were following the association process strategy to determine workshop, on the other hand the processes that were uncertain of work-shop, composed a cache set. Then according to balanced arrangement strategy some processes of cache set could conform to a workshop for convergence process. The processes, that had conformed to some workshop, would determine each workshop scheduling order based on long path strategy and so on, and then the processing time were determined according to process constraint conditions. Example analysis results show that the proposed algorithm can improve utilization of asymmetric devices and solve asymmetric three workshops integrated scheduling in the quadratic complexity.

Defensive Data Destruction Mechanism for Cloud-P2P Computing

XU Xiao-long, GONG Pei-pei

2017, 37(3): 281-286. doi:10.15918/j.tbit1001-0645.2017.03.011

Abstract(913) PDF(1072)

Abstract:
In order to fully tap various resources from network center cluster servers and edge nodes in cloud-P2P computing, that integrates cloud computing and peer-to-peer computing organically; to implement the data security and the remote data destruction in the cloud-P2P computing environment, after introducing the dynamic network edge nodes; furthermore, to prevent some malicious subjects with illegal tamper behaviors from uploading data, a defensive data destruction mechanism was proposed based on mobile agent for cloud-P2P systems. With the mechanism, the mobile agent can be used to detect data, the HASH values of the encrypted data can be put at the end of the ciphertext, and the data can be detected doubly at regular time, the normal data modification can be distinguished effectively from illegal tampering. The prediction of the attack possibility can be realized for related data, and the data, which have been or will be illegally tampered, can be deal with in time. A prototype system was designed and constructed based on the defensive data destruction mechanism. The experimental results show that the defensive data destruction mechanism based on mobile agent has the ideal performance in detection accuracy, safety and time cost.

A CMOS Receiver Front-End for K-Band Low-Noise System-on-Chip

LI Xiao-ran, ZHONG Shun-an

2017, 37(3): 287-291. doi:10.15918/j.tbit1001-0645.2017.03.012

Abstract(1187) PDF(1348)

Abstract:
The Si-base technology can help SOC (system-on-chip) to achieve smaller size, lower cost and low power consumption. In this paper, a fully integrated K-band CMOS receiver front-end was designed based on TSMC 90nm CMOS technology. The receiver front-end consisted of a 2-stage differential cascode low noise amplifier (LNA) and a double balanced Gilbert cell down-conversion mixer. The RF input, LO input and between the LNA and mixer were matched with on-chip transformer Balun. Measurement results show that, when RF is at 23.2GHz, the conversion gain can reach 27.6dB, the noise figure just is 3.8dB, and a high isolation can be got. The receiver chip consumes 35mW with a 1.2V power supply, and only occupies a chip area of 1.45×0.60mm².

Frequency Estimation of Sinusoid Based on the Dual-Threshold Decision Modified Rife Algorithm

CUI Song-qi, WANG Ai-hua, TANG Le, YANG Li-li

2017, 37(3): 292-296,303. doi:10.15918/j.tbit1001-0645.2017.03.013

Abstract(865) PDF(897)

Abstract:
In order to make a good tradeoff between the complexity and performance for frequency estimation of sinusoid, a frequency estimation algorithm with high estimation accuracy and low computation was proposed based on the dual-threshold decision fixed Rife algorithm. The frequency was divided into three domains with different processing schemes, which would be suitable for low power consumption and low-delay applications. Simulation results show that the method overcomes the inherent flaw of the classic Rife algorithm, and the RMS (root mean square) error for the estimated frequency is only 0.5 dB from the CRB (Cramer-Rao Bound). Compared with other improved Rife algorithms, the new approach can significantly reduce the required computation under the premise of guaranteeing the performance of estimation, be propitious to the engineering.

RAMP and An Improved Algorithm For Sparse Channel Estimation in MIMO-OFDM System

GAO Fei, MEI Li-dan, PAN Hong-yun, XUE Yan-ming

2017, 37(3): 297-303. doi:10.15918/j.tbit1001-0645.2017.03.014

Abstract(1117) PDF(862)

Abstract:
The sparse channel estimation in multiple input multiple output orthogonal frequency division multiplexing (MIMO-OFDM) systems was examined. Regularized adaptive matching pursuit (RAMP) was applied to the channel estimation, and the algorithm's iteration termination condition was improved by taking the difference between the residual energy less than the set threshold to terminate the iterative process, ultimately obtain a more accurate estimation of the channel sparsity and improve the estimation accuracy of sparse channel. Simulation results demonstrate that compared to the sparsity adaptive matching pursuit (SAMP) and RAMP, the improved algorithm can obtain better MSE performance. Under the premise of unknown sparsity, the improved algorithm can reach the same MSE performance with orthogonal matching pursuit (OMP).

Massive Machine-Type Communication Performance Analysis Based on Long Term Evolution (LTE) System

FEI Ze-song, XIAO Ling-ling, LIU Ting

2017, 37(3): 304-309. doi:10.15918/j.tbit1001-0645.2017.03.015

Abstract(997) PDF(1475)

Abstract:
One of the distinctive characteristics of machine-type communication(MTC)is the huge amount and high density of devices. This paper mainly studied the performance of massive machine-type communication based on long term evolution(LTE) system. Firstly, the characteristics of MTC were introduced and the limits of LTE system were analyzed to support for massive MTC communication by the case of meter reading in Urban Beijing scenario. And then it was deduced that random-access resources and scheduling resources would be limited in massive MTC communication by using LTE system, which would lead to a loss of MTC subscribers. At last a MTC system-level simulation platform was set up to simulate the influence of different amount of devices and scheduling resources on the system throughput, delay, access collision probability, etc. Simulation results verified the conclusion of theoretical analysis.

Extended Suzuki Model with Double-End Truncated Power Spectral Density for Land Mobile Satellite Channel

WANG Ai-hua, JIA Jing-hui, ZHANG Mi, WANG Xing-yuan

2017, 37(3): 310-313,324. doi:10.15918/j.tbit1001-0645.2017.03.016

Abstract(995) PDF(1425)

Abstract:
In order to make channel model reflect real channel propagation characteristics more accurately, an extended Suzuki model with double-end truncated power spectral density for land mobile satellite channel was proposed according to the distribution characteristic of Doppler spread power spectral density in frequency domain. It was assumed in the model that, the power spectral density of the received signal was truncated in the low and high frequency region. The probability density function and level crossing rate of the model were derived, and compared with the experimental data. The simulation results indicate that the model can fit the experimental data better, reflect real channel propagation characteristics more accurately compared with the single side truncated model. It can be converted to other narrow-band satellite channel models when some parameters are given, and the model has a wide range of applicability.

Design and Performance Analysis versus Error Rate of Fountain Code-Based File Delivery Protocol for Deep Space

FANG Jia-cong, ZHANG Yu, LIU Yi, LI Qian

2017, 37(3): 314-317. doi:10.15918/j.tbit1001-0645.2017.03.017

Abstract(1000) PDF(1103)

Abstract:
The efficiency of automatic repeat quest (ARQ) based transmission protocols decrease due to the high delay and high error rate of deep space communication. Fountain code-based transmission protocols can be adopted to improve the transmission efficiency under such circumstances. In this paper, a central limit theorem was employed to analyze the performance versus error rate of the fountain code-based file delivery protocol. A simulation was conducted in accordance with the probability model of central limit theorem. The result shows that the central limit theorem probability model is close to the actual situation. The central limit theorem can be taken as the principle of protocol design. An expression of packets sent by normal quantile function-based protocol was derived. This expression ensures if the number of packets sent is not less thann, then the successful rate is not less thanδ.

Micro-Motion Parameter Measurement of Rigid Targets with Translation Based on Instantaneous Frequency Rate

WANG Cai, XU Cheng-fa, FENG Qi, GAO Mei-guo

2017, 37(3): 318-324. doi:10.15918/j.tbit1001-0645.2017.03.018

Abstract(1194) PDF(682)

Abstract:
In order to estimate the micro-motion parameters of rigid targets with second-order translation, a parameter measurement method based on short-time cubic phase function (CPF) and inverse Radon transform (IRT) was proposed. Based on the typical rotation micro-motion model, the instantaneous frequency rate (IFR) representation was first derived and analyzed after primary translation compensation. The short-time CPF was then used to obtain the two-dimensional time-IFR plane of radar echoes. Finally, based on the two-dimensional time-IFR plane, the translation compensation velocity error, acceleration error and micro-motion parameters were measured by taking advantage of the sinusoid curve measuring principle based on IRT. The simulations validate the effectiveness of the proposed method.

Phase Center Correction for GNSS Adaptive Anti-Jamming Antenna Array

WANG Da-wei, LI Jia-qi, ZHOU Xin-peng, WU Si-liang

2017, 37(3): 325-330. doi:10.15918/j.tbit1001-0645.2017.03.019

Abstract(1325) PDF(1153)

Abstract:
To implement precise position and measurement of location and attitude in the presence of interference, the error induced by antenna array phase center offset should be reduced as much as possible. A phase center compensation model was established for anti-jamming antenna array. Taking every element of the array as antenna of the multiple phase center, a calculation method was derived to get the equivalent phase center position of adaptive anti-jamming antenna array. And the error induced by phase center offset in anti-jamming RTK system was analyzed. Phase center offset of antenna array was corrected by compensating carrier phase observable. Simulation results show that the position of equivalent phase center of antenna array varies with interference and adopted algorithms. Correspondingly, error induced by phase center offset cannot be compensated using fixed lookup table, but can be compensated with the carrier phase observable corrected by the anti-jamming calculation result in real time.

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