Table of Content

25 January 2010, Volume 38 Issue 1

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Electronics, Communication & Automation Technology

Multi-Partition and Double-Direction Shrink QR Algorithm for Singular Value Decomposition of Large-Scale Matrix

Zhao Xue-zhi Ye Bang-yah Chen Tong-jian

2010, 38(1):  1-8.  doi:10.3969/j.issn.1000-565X.2010.01.001

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Aimed at the essential reason of the algorithm when it is used to process the singular non-convergence of the traditional QR （Quadrature Right-triangle） value decomposition （SVD） of some large-scale matrixes, a doubledirection shrink and multi-partition method is proposed. In this method, the line dislodgment algorithms of nonzero element from left to right and from down to up, which greatly influence the accuracy of SVD, are investigated, and a searching algorithm for the first and the last rows of the sub-matrix is put forward to realize the partition of the main matrix. Thus, a multi-partition and double-direction shrink QR algorithm for the SVD of large-scale matrix is implemented. An example is then presented to reveal the difference of convergence speed between the non-partition and the multi-partition QR algorithms. The results indicate that the proposed algorithm realizes a smooth iteration process with less iteration number and high convergence speed, overcomes the non-convergence of the traditional QR algorithm, and realizes the high-speed SVD computation of any large-scale matrix.

An Improved Distributed Power Control Algorithm for Readers

Dai Hong-yue Yao Xi-fan Liang Shuang

2010, 38(1):  9-13.  doi:10.3969/j.issn.1000-565X.2010.01.002

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As the parameter setting, available power control algorithms for readers exist uncertain random backoff and insufficient in this paper presents an improved distributed power control algorithm marked as EDPC. In this algorithm, the working time sequence of the reader is reasonably set and the selection mechanism of working time slot is improved, thus increasing the efficiency and reliability of power control. Simulated results indicate that, as compared with the existing DAPC and PPC algorithms, the proposed algorithm enlarges the detection range of the reader, shortens the detection time, and improves the integrated performance of the reader system.

Modified Model of Threshold Voltage for Thin-Film Transistors with Low-Doped Polysilicon

Yao Ruo-he Ou Xiu-ping

2010, 38(1):  14-17,43.  doi:10.3969/j.issn.1000-565X.2010.01.003

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In this paper, first, the surface potential of thin-film transistors with light-doped polysilicon is analyzed. Next, the gate voltage, which corresponds to the channel current that quickly increases when the surface potential deviates from the sub-threshold region, is considered as the threshold voltage. Then, by taking into consideration the single-exponential distribution of trap state density, the surface potential of the transistor is derived, and an ana- lytical model of the threshold voltage is presented. Finally, a numerical simulation is performed to verify the model. The results indicate that the threshold voltage obtained by the proposed model perfectly matches that extracted by the second-derivative method.

A Way to Complexity Analysis of Chaotic Pseudorandom Sequence

Luo Song-jiang Qiu Shui-sheng Chen Xu

2010, 38(1):  18-21.  doi:10.3969/j.issn.1000-565X.2010.01.004

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In order to measure the random essential of chaotic pseudorandom sequences, a method based on the intensive statistical complexity is proposed and is used to analyze the complexity of a chaotic pseudorandom sequence. Then, based on the chaotic sequence and the octal chaotic pseudorandom sequence produced by both the Logistic map and the coupled map lattice, an example is persented to demonstrate how the method works. Moreover, an improvement of permutation patterns is performed to make the method applicable to binary chaotic pseudorandom sequences. Experimental results indicate that the proposed method well presents the related structure and reflects the random essential of the sequence, and that it is suitable for the complexity measurement of different chaotic pseudorandom sequences produced by the chaotic system with simple computation.

Design and Analysis of Asymmetric IDMA Interleaver

Luo Zhi-feng Qiu Shui-sheng

2010, 38(1):  22-25.  doi:10.3969/j.issn.1000-565X.2010.01.005

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In an interleave division multiple access （IDMA） system, different interleavers are used for different users, and all the users employ a common spreading sequence to spread the spectrum. Hence, interleaver plays a key role in the IDMA secure communication. As there are no interleaver designs for IDMA secure communications, this paper proposes a design scheme of an asymmetric IDMA interleaver based on the discrete Arnold map, which implements the secure communication via the method similar to the asymmetric encryption scheme. Simulated results show that the proposed interleaver is of the performance as good as that of the pseudo random interleaver, and that it is effective in performing secure communications.

Subchip Multipath Search for DSSS Receiver Based on Fractional Fourier Transform

Tang Xun Sha Xue-jun Wen Rong-hui

2010, 38(1):  26-30.  doi:10.3969/j.issn.1000-565X.2010.01.006

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To improve the energy efficiency of muhipath signals, a subchip muhipath search method based on the fractional Fourier transform （FrFT） is proposed, in which Chirp signals are used as pilot signals and muhipath Chirp signals are processed by FrFT at receiver side. Then, according to the linear relationship between the multipath relative delay in time domain and the difference in peak positions of muhipath Chirp signals in FrFT domain, the relative delays between muhipath Chirps are calculated after detecting the peak positions, with a search resolution equal to the reciprocal of the bandwidth of Chirp signals. Thus, the Chirp signal with a bandwidth lager than that of direct sequence spread spectrum （DSSS） signal can be used to search subchip muhipath. Simulated results show that the proposed method helps to effectively calculate the relative delays of subchip multipath and greatly improves the BER （ Bit Error Rate） performance of DSSS receiver after the equal-gain-combining process of the recognized subchip multipath.

A Novel Cooperative Scheme for Multiple-Access Relay Channel

Han Chun-lei Ge Jian-hua Wang Yong Gao Ming

2010, 38(1):  31-37.  doi:10.3969/j.issn.1000-565X.2010.01.007

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As for the conventional multiple-access relay cooperation scheme, the coding gain is limited and users cannot assist each other. In order to solve these problems, a novel cooperative scheme based on network and channel coding is proposed. In this scheme, the coding redundancy of different users is simultaneously forwarded through network coding at the relay node, and, once the codes of one user are correctly decoded at the destination, the coding redundancy of other users can be retrieved. The approximations of outage probability and bit error rate of the proposed scheme are then deduced by analyzing the error event probability. Simulation results show that the proposed scheme is of better performance than the coded cooperation scheme in terms of outage probability and bit error rate when the signal to noise ratio （SNR） is getting higher, and that the performance of the user with low SNR can be improved with the help of the user with high SNR.

Collaborative Detection Algorithm of Idle Spectrum in Cognitive Radio

Shi Lei Jiang Wei-lin Zhang Zhong-zhao

2010, 38(1):  38-43.  doi:10.3969/j.issn.1000-565X.2010.01.008

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In order to improve the detection performance of sensing users for primary users with weak signals in the cognitive radio environment, a distributed optimal collaborative detection algorithm with multiple sensing users is proposed. In this algorithm, with the known probability dist.ributions of primary user＇ s signals and noises, both the optimal fusion rule of the detection system and the optimal decision threshold of each sensing user are obtained via the sequential quadratic programming in the optimization theory, which makes the collaborative detection probability maximum. Being independent of the detection form of the receiver, the proposed algorithm possesses high convergence rate of numerical solution. Simulated results indicate that, with five sensing users, 255 cumulative correlated symbols, 10% false alarm of the fusion center and the same signal-to-noise ratio of all sensing users, the proposed algorithm is superior to the existing best detection algorithm based on the fixed fusion rule in both the additive white Gaussian noise and the fiat Rayleigh fading channels ,with an improved collaborative detection probability by 13% and 5% , respectively.

Anti-Jamming System for Cognitive Radio Based on Fractional Fourier Transform

Liu Xin Tan Xue-zhi

2010, 38(1):  44-48.  doi:10.3969/j.issn.1000-565X.2010.01.009

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As the confliction between two cognitive radio （CR） systems and the interference among authorized users may degrade the performance of CR systems, an anti-jamming system for CR based on fractional Fourier transform （FrFT） is proposed. In this system, Chirp signal whose energy concentrates in FrFF domain is used as the base-band signal of CR, and the original data are restored via the filtering in FrFT domain and some correlative calculations. Simulated results show that the proposed system can extract the energy of expected signals and effectively suppress muhipath interference and the interference of other cognitive users, and that, when the interference is a cosine signal, bit error rate of the proposed system is lower than that of the system without FrFT.

Delay Analysis of 802.11 DCF Based on G/G/1 Queuing Model

Xie Li-ying Wang Hong-fiang Wei Gang

2010, 38(1):  49-53,58.  doi:10.3969/j.issn.1000-565X.2010.01.010

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As the existing models analyzing the back-off scheme in 802. 11 DCF can not effectively consider the neighbor nodes, this paper proposes a new approach to the performance analysis of unsaturated 802.11 DCF protocol, deduces the formulae of the MAC （Medium Access Control） layer delay and its delay in unsaturated single-hop 802.11 DCF network, and analyzes the effects of packet arrival rate, node number and collision window size on the MAC-layer transmission collision probability, the delay and the delay jitter. Simulated results indicate that the transmission collision probability, the delay and the delay jitter all increase with the packet arrival rate and the node number, and that the delay and the delay jitter both decrease with the minimum collision window size of DCF, following by an increase in the transmission collision probability.

Overhearing-Based Estimation Algorithm of Available Bandwidth in Wireless Sensor Networks

Chen Chen Gao Xin-bo Pei Qing-qi

2010, 38(1):  54-58.  doi:10.3969/j.issn.1000-565X.2010.01.011

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Available bandwidth plays an important role in routing selection, load balance, multi-sink deployment and priority transmission in wireless sensor networks. This paper focuses on the available bandwidth and proposes an overheating-based estimation scheme of available bandwidth in S-MAC protocol-based wireless sensor networks. When the overhearing mechanism is enabled in S-MAC, the network allocation vectors stored in the RTS/CTS/DATA/ ACK packets of neighbour nodes are recorded in the buffer in the form of a table, and the available bandwidth is thus calculated. Simulated results show that the proposed method can accurately estimate the network load and cornpetition level regarding the investigated S-MAC nodes

802.16 Cross-Layer Interaction Management Based on Modularization of Network Protocol Stack

Guo Hua Ye Wu Feng Sui-li Zhuang Hong-cheng

2010, 38(1):  59-64.  doi:10.3969/j.issn.1000-565X.2010.01.012

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In order to improve the software architecture perspective of cross-layer design, a cross-layer interaction management algorithm considering the modularization of network protocol stack is proposed and is marked as CLIM. In this algorithm, DSA and message queue mechanisms are both employed to manage cross-layer interactions, thus implementing cross-layer interactions more flexibly and maintaining the good architecture of network protocol stack. Simulated results show that CLIM helps to reduce the time cost to running cross-layer interactions, and that, by combining with IEEE 802.16 signaling mechanism, CLIM makes it possible to use multiple cross-layer designs in an 802.16 terminal.

Vision-Based Inspection Algorithm for Chip Components

Zhang Wu-jie Li Di Ye Feng

2010, 38(1):  65-69,86.  doi:10.3969/j.issn.1000-565X.2010.01.013

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In order to automatically inspect chip components, a vision-based method is proposed to calculate the geometrical parameters of the components. In this method, first, the coarse location of chip components and the edge point sorting are realized by means of the maximum external rectangle method, and the precise location of the edge is implemented by using the Canny operator and the Zernike moment operator. Next, the edge points are sorted into 4 parts according to sorting points, which are then fitted respectively via line and arc fittings to obtain the corresponding accurate values. Moreover, the stripe direction of the transverse image of chip components is correctly judged according to the image characteristics obtained via the fast Fourier transform （FFT）. Finally, an experiment is carried out, with a subpixel location precision of 0.03 pixel, a line fitting precision of O. 03 pixel, an arc fitting precision of 0. 05 pixel and a stripe direction accuracy of the transverse image of 100% being obtained. The results indicate that the proposed inspection method is of strong stability, high precision and excellent real-time perfor- mance, which is helpful in the automatic Vision-based inspection of chip components.

Wavelet Scalogram Reassignment and Matching Detection for LFM Echoes of Underwater Target

Wang Qiang Pan Xiang Wang Xiao-wei

2010, 38(1):  70-75.  doi:10.3969/j.issn.1000-565X.2010.01.014

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In order to improve the detection performance of small-scale underwater targets in a shallow-water reverberation-limited environment, broadband linear frequency-modulated （LFM） signals containing vast target information and weak reverberation background correlation are used to perform a time-frequency spectrogram reassignment and a matching detection for the target broadband echoes. Then, the time-frequency features of target echo respectively obtained by the short-time Fourier transform （STFY） and by the wavelet scalogram reassignment are compared, finding out that the reassignment helps to effectively separate the target signal and the coupled reverberation signal. Moreover, a time-frequency matching detector based on wavelet scalogram reassignment is designed according to the matched filter features. Simulated and test results indicate that the proposed method is superior to the traditional matched filtering method with a gain increase of about 4 dB, and that it can accurately locate the underwater targets in reverberation-limited area with strong side-lobe suppression.

Computer Science & Technology

Effective Connectivity of Brain Network Based on Granger Causality and PCA

Zhong Yuan Wang Hui-nan Jiao Qing Zhang Zhi-qiang Zheng Gang Yu Hai-yan Lu Guang-ming

2010, 38(1):  76-80.  doi:10.3969/j.issn.1000-565X.2010.01.015

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In order to improve the detection reliability of effective connectivity in brain network, an fMRI （Functional Magnetic Resonance Imaging） analytical approach of effective connectivity is proposed based on the Granger causality （GC） and the principle component analysis （PCA）. In this approach, first, temporal principal components are extracted via the PCA from the fMRI signals in the region of interest, and the patterns are considered as temporal reference information. Next, the Granger causality between the reference region and each of other voxels of the brain is calculated. Then, the results are mapped into the whole brain and a Granger causality map （GCM） is thus obtained. Moreover, a theoretical derivation is performed to verify the effectiveness of the proposed approach. The proposed approach is finally used t＇o analyze the GCM of a manual movement task-induced activation in the motor area, the results verifying the correctness of theory of motor-function neural network

An efficient Network Intrusion Detection Feature Extraction Method

Zhang Xue-qin Gu Chun-hua

2010, 38(1):  81-86.  doi:10.3969/j.issn.1000-565X.2010.01.016

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In order to eliminate redundant features, reduce the system burden of storage and computation, and improve the performance of the classifier for network intrusion detection, a method to extract network intrusion detection feature is proposed based on the Fisher score and the support vector machine （SVM）. Then, in accordance with KDD^,99 network intrusion detection dataset, the feature significance rankings for the mixed attack and four single attacks are respectively obtained by using the proposed method. By extracting important features, a SVM classifier is thus constructed. Experimental results show that, as compared with the classifier constructed based on all features, the new classifier is of approximately equivalent accuracy and dramatically low training and testing time cost.

Semi-Supervised Classification Based on Regularization of Minimum Entropy

Liu Xiao-lan Hao Zhi-feng Yang Xiao-wei Ma Xian-heng

2010, 38(1):  87-91.  doi:10.3969/j.issn.1000-565X.2010.01.017

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As the generative model needs modelling complex joint probability density and evaluating many parameters, a discriminant semi-supervised classification algorithm based on the regularization of minimum entropy is proposed. This algorithm uses Havrda-Charvat＇s structural α-entropy as the regularization item of the objective and employs the quasi-Newton method to solve the objective, which makes the algorithm discriminative and inductive and reduces the dependence of the algorithm on the model. At the same time, the algorithm can predict the labels of the out-of-sample data points easily. Simulated results of several UCI datasets demonstrate that the proposed algorithm is of low classification error even with few labeled data.

Performance-Efficiency Balanced Optimization based on Sequential Game in Grid Computing

Zheng Mei-guang Hu Zhi-gang Zhang Kai

2010, 38(1):  92-96,107.  doi:10.3969/j.issn.1000-565X.2010.01.018

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In order to optimize the executing performance of applications and improve the resource utilization efficiency of a system, this paper deals with the resource mapping in grid environments and proposes a novel optimization strategy based on the sequential game. In this strategy, a balanced idea is used to divide the mapping process into two stages, namely the activity distribution and the processor allocation, and an optimal solution is obtained after a limited stage gaming. Moreover, trust degree, an important parameter to measure the executing performance of applications, is dealt with, and the corresponding calculating method is presented. Experimental results indicate that, as compared with the Min-Min strategy, the proposed optimal strategy is of lower time complexity, better executing performance of applications and higher resource utilization efficiency.

A Method of Dynamic Power Management for Hard Disk

Liu Fa-gui Wu Ze-xiang Mai Wei-peng

2010, 38(1):  97-101.  doi:10.3969/j.issn.1000-565X.2010.01.019

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Hard disk consumes about 20% of power of a portable system. In order to reduce the power consumption and prolong the service time of portable systems, a method of dynamic power management for hard disk, including the hard-disk state conversion by reading and writing hard disk registers, the load acquisition by reading interrelated kernel structures, and the design and implementation of high-performance policy optimization algorithms, is devised. Experimental results indicate that the dynamic power management of hard disk helps to significantly reduce the power consumption of portable systems, and that the proposed management method is feasible.

Automotive Engineering

Dynamics of Urban-Rail Magnetic Levitation Vehicle with Five Bogies

Han Qiang Yang Yi-peng Yao Xiao-hu Liu Xiao-ming Hu Bo-ren

2010, 38(1):  102-107.  doi:10.3969/j.issn.1000-565X.2010.01.020

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In order to reveal the dynamic characteristics of urban-rail magnetic levitation vehicle with five bogies, a virtual prototype model of the vehicle is established with software Catia and ADAMS after a reasonable simplification. Then, a dynamic simulation of the model is carried out in two different operating conditions. The results indicate that, when the vehicle is statically levitated, the carriage body vibrates in lateral, longitudinal and especially vertical directions. Moreover, by analyzing the vertical vibration parameters, it is found that the vehicle is of good ride comfort. The proposed model is proved correct by the consistency of simulated results with the calculated ones when the vehicle goes through a R70 m curve.

Traction Control of Four-Wheel Drive Vehicles Based on Inter-Axle Torque Distribution

Hu Jian-jun Wang Yin Qin Da-tong Ding Hua

2010, 38(1):  108-112,118.  doi:10.3969/j.issn.1000-565X.2010.01.021

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In order to improve the traction performance of vehicles, a mathematical model describing the acceleration process of four-wheel drive vehicles is established through the analysis of inter-axle torque distribution, and an integrated control strategy is proposed to control both the engine throttle and the inter-axle torque distribution. Then, an engine throttle control system and a current control system for inter-axle torque distribution are designed based on the PI control. Finally, a simulation is performed to compare the vehicle performances with and without traction control on both low-adhesion and docking roads. The results indicate that the proposed traction control system for four-wheel drive vehicles effectively prevents the driving wheel from excessively spinning and improves the dynamic performance of vehicles.

Mechanical Engineering

Modeling of Time Property and Analysis of Real-Time Optimization for Virtual Instruments

Xu Qin-gui Liu Gui-xiong Gao Fu-rong

2010, 38(1):  113-118.  doi:10.3969/j.issn.1000-565X.2010.01.022

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In multitasking environment, the response time is unpredictable because the execution speed of measurement and control tasks is uncertain. In order to solve this problem, first, a response time model is put forward based on the virtual instrument architecture and the real-time working conditions. Next, real-time measuring indicators are exactly computed via the timing measurement at a microsecond level. Then, the main approaches to real- time performance optimization are proposed and experimentally verified based on the derivation of data-processing delay formula. Finally, an estimation formula for the highest data acquisition frequency is presented based on the analysis of experimental results, which enables virtual instruments to maintain stable response time under the system load as high as that with 80% CPU usage, and thus realizes the constrained optimization of real-time performance.

Improved Predictor-Corrector Real-Time NURBS Interpolation Algorithm

Liu Ning Wang Gao

2010, 38(1):  119-123,127.  doi:10.3969/j.issn.1000-565X.2010.01.023

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As the current methods of two-order predictor in real-time NURBS interpolation process can not ensure the monotonicity of parameter u, the interpolation direction may reverse in some conditions, and the iterative interpolation process in the comer of NURBS curves is not always convergent. In order to solve these problems, this paper proposes a one-order predictor-corrector algorithm, in which a one-order prediction formula is used to calculate parameter u, and an iterative calculation is performed to obtain the coordinates of NURBS curves up till a satisfying interpolation precision. Test results show that the proposed algorithm ensures the monotonicity of parameter u in the interpolation process and eliminates the interpolation direction reverse, and that it is of a velocity precision as high as that of the two-order predictor though more iteration cycles are needed.

Multi-Robot Collision Avoidance Algorithm Based on Generalized Potential Field

Zhao Dong Zheng Shi-xiong

2010, 38(1):  124-127.  doi:10.3969/j.issn.1000-565X.2010.01.024

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As the existing multi-robot collision avoidance algorithm is of high computational complexity and poor applicability, a new algorithm based on the generalized potential field and the traditional artificial potential field-based algorithm, which takes into consideration the consult and desire of the robot, is proposed for the motion planning of multi-robot system. In this algorithm, a repellence potential field is built based on the obstacles in the physical space, a gravitation potential field is built based on the desire, and a generalized artificial potential field is built by the topological product of the repellence and the gravitation potential fields. By solving the motion trend of the mini- cells in the established artificial potential field, a road planning can be successfully implemented. Experimental re- sults indicate that, as compared with the traditional artificial potential field-based algorithm, the proposed algorithm is also simple in structure and is superior in terms of optimal path planning and mobile collision avoidance.


Numerical Simulation of High-Speed Spinning of Thin-Wall Copper Tube with Axial Micro-Grooves

Li Yong Xu Ze-chuan Tang Yong Zeng Zhi-xin

2010, 38(1):  128-133.  doi:10.3969/j.issn.1000-565X.2010.01.025

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In this paper, a simplified 1/4 rotational symmetrical model is built with the aid of finite element software MSC. Marc, and the high-speed steel-ball spinning process of thin-wall copper tube with axial micro-grooves is simulated. Afterwards, the forming characteristics, as well as the distributions of the equivalent stress and strain and of the residual stress, is analyzed. The results show that the metal rebound occurring in the forming process may result in forming gaps at the tooth root, that both the equivalent and the three-direction stress and strain arrange in layers in the axial direction, that the equivalent stress on the exterior wall surface, which is greater than the yield stress of the material, leads to the emergence of copper scale and fracture, that the equivalent stress and strain as well as the residual stress at the groove bottom are larger than those at the tooth tip and those on the exterior wall surface, and that larger residual stress may result in material embrittlement and surface cracks.

A 3D Anti-Bird System with Gradually-Distributed Complexity for Airport

Lu Long-sheng Tang Biao Bai Peng-fei

2010, 38(1):  134-138.  doi:10.3969/j.issn.1000-565X.2010.01.026

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The traditional anti-bird methods for airports are inefficient due to their singleness. In order to solve this problem, an anti-bird system which disturbs the learning procedure of birds is presented. In the investigation, the anti-bird functional space is plotted into several parts, and a 3D anti-bird model with gradually-distributed complexity in height is established, by which a 3D system marked as A552 with the complexity being consistent with the bird distribution in height is proposed. The system includes such modules as artificial human, scaring eyes, broadcasting, electronic gun and artillery. Thus, it can drive birds in the aspects of vision, hearing and smell, and reduces the bird impact probability by more than 57 %.

Mechanism of Glass Cutting by Using Single-Straight Tool with Big Inclination Angle

Wan Zhen-ping Huang Zhi-cheng Tang Yong

2010, 38(1):  139-143,148.  doi:10.3969/j.issn.1000-565X.2010.01.027

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Functional glasses are mainly hard and brittle, and are difficult to machine because cracks and concavities are easily form on the machined surface. In order to solve this problem, a glass-cutting process by using a singlestraight tool with big inclination angle is proposed, which helps to obtain integral surface without cracks and concavities in a cutting depth at sub-millimeter level. The corresponding cutting mechanism, as well as the effects of tool parameters and cutting parameters on the surface quality, is then analyzed. Experimental results indicate that, by using the single-straight tool with big inclination angle, the roughness Ra of machined surface is less than 0. 21 um and the integrity of the surface is better than that of the surface machined by the conventional precision grinding, and that there exist suitable ranges of tool and cutting parameters for high-quality machined surface.

Numerical Analysis of Multi-Pass Rough Rolling Process of H-Beam

He Qing-qiang Sun Jia Yuan Bao-min Zhao Jun-you Jin Tao

2010, 38(1):  144-148.  doi:10.3969/j.issn.1000-565X.2010.01.028

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In order to analyze the reasonability of the existing shaped-metal rolling process, the microstructure evolution and the rolling force must besynthetically considered. This paper proposes an integrated numerical analysis procedure to simulate the multi-pass rough rolling process of H-beam, establishes a high-temperature yield stress model and an austenite-grain evolution model based on the thermal simulation and the metallographic observation, and presents a multi-pass simulation method through a re-meshing procedure. Simulated results of an 11-pass rough rolling process of a typical-size H-beam show that the calculated rolling force accord well with the measured ones, and that the austenite grains at the web can be apparently fined after the rough rolling.