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Table of Content

    22 April 2009, Volume 15 Issue 2
    Communication and Information
    Second Order Statistics of an Extended SUZUKI Mobile Fading Channel Model
    LI Ying-Chun, CHEN Jian, SONG Yang-Xiong, LIN Ru-Jian
    2009, 15(2):  111-115. 
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    The statistics of an extended SUZUKI mobile fading channel model are studied. Closed-form expressions for the secondorder statistics of the envelope process for the analytical model, i.e., the level-crossing rate (LCR) and average duration of fades (ADF) are given. Since the Rayleigh fading channel is a special case of the proposed model, the derived expression can be verified by comparison with results for the Rayleigh fading channel. A numerical optimization procedure has been used to fit the statistics of the proposed analytical model to an equivalent mobile channel for light and heavy shadowing environments. Theoretical and simulation results show that the extended SUZUKI mobile fading channel has excellent performance.

    Dynamic Collaborative Merging Scheme for VOD Service over 3Tnet
    SHI Hai, TIAN Li
    2009, 15(2):  116-120.  doi:TN925.5
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    China’s high performance broadband information network, named 3Tnet, is a new network with large-scale video services. Based on the architecture of VOD service over 3Tnet, a new dynamic collaborative merging scheme is proposed. This scheme employs a dynamic collaborative merging scheduling algorithm based on a patching multicast policy to further reduce bandwidth requirement of the edge network for VOD service over 3Tnet. Simulation results show that, with 3 000 movies, the proposed scheme can save about 28.2% bandwidth of the edge network and 47.2% bandwidth of the residential network, respectively, compared with a peer-to-peer chaining policy. Moreover, compared with the patching multicast policy, this scheme can save about 17.6% bandwidth of the edge network by slightly increasing bandwidth (about 3.8%) of the residential network.

    Dual-Band Radio Frequency Identification Printed Antenna
    GU Jian-Hui, ZHONG Shun-Shi, CHEN Kuang-Da
    2009, 15(2):  121-124.  doi:TN82
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    A new design of dual-band radio frequency identification (RFID) printed antenna fed by a coplanar waveguide (CPW) is proposed, which operates in both 2.45 GHz and 5.80 GHz RFID bands. Its two measured impedance bandwidths are 32.0% at 2.45 GHz and 9.8% at 5.80 GHz respectively. The antenna has a simple structure sized 40 mm×40 mm, which is easy to be integrated with active devices and monolithic microwave integrated circuits. Details of the proposed antenna design and the measured results are presented and discussed.

    Channel Mismatch Effects in Time-Interleaved A/D Converters
    HONG Liang, ZHANG Jun-Jie
    2009, 15(2):  125-129. 
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    Bandwidth mismatch effect in time-interleaved A/D converter (TIADC) is studied. Formulas of the signal-to-noise-and-distortion ratio (SINAD) for combination of four different channel mismatches and quantization errors are proposed. The derived formulas can be used for calibration to compensate for the channel mismatch effects. Simulation results are presented to verify the formulas.

    Ultra-Wideband Wide-Slot Printed Antenna with Inverted π-Shaped Feed
    XUE Ling-Long, ZHONG Shun-Shi
    2009, 15(2):  130-133. 
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    A new ultra-wideband wideslot printed antenna with an inverted π-shaped feed is introduced, which is fed by a coplanar waveguide (CPW). The characteristics of the proposed antenna are investigated both numerically and experimentally, then the return loss curve and radiation patterns of the antenna are presented. The experimental results show that the antenna has an impedance bandwidth of approximately 120% (S11≤-10 dB), covering 3.0~12.0 GHz frequency range. Compared with some reported antennas of the same-type, it is noted that the size of the proposed antenna is the smallest among them.

    Mathematics.Physics and Chemistry
    High Order Compact Finite Difference Schemes for Linear Wave Equations
    LUO Bai-Hua
    2009, 15(2):  134-141. 
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    Low-dissipation and low-dispersion high-order compact finite difference schemes are studied for computation of wave motion. An optimized seven-point sixth order accurate compact finite difference scheme (CO6) is obtained to approximate spatial derivatives, and is compared with the C6 (sixthorder compact) and C8 (eighth-order compact) schemes. For time marching scheme, the fourth order explicit Runge-Kutta methods (RK4 and LDDRK or RK46) are used. The effective wave-number ranges of the spatial schemes, the numerical errors of the various schemes, and the minimum point numbers per wavelength (ppw) for long distance propagation calculation of waves are studied. Based on the comparison, suggestions are given in using these schemes. Finally, a few numerical tests are presented to show accuracy of the schemes in simulation of wave motion.

    CdTe Quantum Dots Fluorescence-Quantum Yield and Biological Labeling
    CHEN Li-Xia, ZHANG Jian-Cheng, SONG Zhen-Wei, YOU Chen-Xia, DING Yi-Min, SHEN Yue, GUO Jing-Kang
    2009, 15(2):  142-146. 
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    CdTe quantum dots (QDs) were synthesized in an aqueous solution with thioglycolic acid (TGA) as a stabilizing agent to actualize water solubility of semiconductor nanocrystals. The carboxylic acid groups of thioglycolic acid (TGA) stabilizing CdTe quantum dots can form amido bonds with the amine groups of bovine serum albumin by the coupling action to label the protein.Before and after labeling bovine serum albumin (BSA), the change of emission and absorption spectra of CdTe quantum dots as well as their fluorescence-quantum yield were studied by fluorescence and UV-vis spectrophotometer. CdTe-BSA was confirmed by gel electrophoresis after being purified by dialysis.

    Automated Photoelasticity Stress Analysis
    HAN Yong-Sheng, ZHANG Dong-Sheng, CUI Yang, LIANG Qiu-Sheng
    2009, 15(2):  147-152. 
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    Phase shift is applied to calculate parameters from photoelastic fringe patterns. Stress components are determined with shear stress differential methods. In planar polariscope, four fringe patterns with specific angles are acquired and the phase map of the orientation of principal stresses derived from isoclinics according to four-step phase stepping. A method is proposed to determine orientation of the first principal stress in the entire field. Similar to Tardy compensation, isochromatic fringe patterns are analyzed in 8 discrete directions. In each direction, phase shift is achieved by rotating the analyzer in the circularly polarized field. With information of the orientation of the first principal stress, the phase map of isochromatics for the entire field is constructed from the 8 phase maps. Thus, stress components within the photoelastic model can be determined. An example is given to illustrate the merits of the proposed methods.

    Bayesian Estimate of Stochastic Intensity of Mixed -Poisson Random Varia
    YU Mei-Ling, ZHAO Fei
    2009, 15(2):  153-155. 
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    This paper studies estimation of stochastic intensity from observed values of mixed Poisson random variables. Characteristics of the Bayesian estimate of the stochastic intensity of a class of mixed Poisson distributions are given, which are then extended to a more general case. This result is an extension of Johnson’s results.

    Analysis of Two-Photon Ionization and Photoelectron Imaging -Spectrometry for Potassium Atoms
    CHEN Fa-Tang, LIU Juan, FAN Rong, LI Yong-Fang
    2009, 15(2):  156-159. 
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    Based on principle of photoelectron angular distribution imaging spectrometry, with potassium atoms as an example, the interference pattern of angular distributions of photoelectrons are obtained using a single photon resonant excitation and two-photon ionization. The angular distribution of photoelectrons is closely related to interference. The interference pattern and information of the atomic energy states are discussed in detail.

    Numerical Analysis of Axial Flow Pump Arrangement
    LIANG Xue-Jie, CHEN Hong-Xun, WEI Pei-Ru
    2009, 15(2):  160-163. 
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    Based on ANSYS CFX 10.0, full 3D numerical simulations of axial-flow pump arrangement are carried out under different operating conditions using two different turbulent models to solve the Reynolds-averaged NavierStokes equations. The head and hydraulic efficiency of pump arrangement are computed, and comparisons made between the calculated and measured results. The trend of calculated results agrees with the experimental results. In the vicinity of the highest efficiency point, the head relative error computed using the standard  k-ε  is the smallest. The computed head is higher than the experimented head with increasing discharge. It is lower than the experimented head with decreasing discharge.

    Parallel Molecular Dynamics Simulation of Crack on Parallel Clusters
    LU Hong-Quan, ZHANG Jun-Qian
    2009, 15(2):  164-168. 
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    By discussing the parallel algorithm of molecular dynamics and describing construction of a parallel simulation cluster, the process of parallel molecular dynamics (PMD) programming and its implementation are studied. Installation and application of Lammps, a code of PMD, on the parallel cluster Ziqiang 3000 are introduced. The crack PMD simulation is checked.

    Computer Engineering and Science
    Distance Measurement Using BinocularCamera with Adaptive Focusing
    XU Jie, CHEN Yi-Min, SHI Zhi-Long
    2009, 15(2):  169-174. 
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    The method of depth measurement by using binocular-camera is based on the principle of parallax, which provides a new solution to distance measurement by seeking the match point in the 2D-image. In this paper, an improved method is presented to extend the length of depth measurement with adaptive focusing. A concept of sensitivity is presented, which is an important factor for efficient and accurate depth measurement. According to the sensitivity function, an improved algorithm is presented, which is well-performed in the measurement test.

    Collaborative Manufacturing Oriented Task Planning Configuration -Management and Collaborative Control
    ZHAO Zheng-De, ZHAOYu-Liang, YANG Li-Chao
    2009, 15(2):  175-180. 
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    By analyzing the principle requirements and implementation of collaborative manufacturing (CM), this paper proposes general system construction, the corresponding function of task planning, configuration management, and collaborative control. A series of tasks can be accomplished including management modeling of collaborative manufacturing in task allocation, collaborative strategy of personnel allocation management, task planning, task implementation, business process, and collaborative control of personnel during the reviewing phase. This enables the leader of alliance (LA) and out-manufacturers (OMs) to work together and complete production process with high efficiency and speed.

    Mechatronics Engineering and Automation
    Motion Restricted Condition and Singular Configuration for Mecanum -Wheeled Omni-Directional Motion System
    WANG Yi-Zhi, CHANG De-Gong
    2009, 15(2):  181-185. 
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    Though kinematics analyzing for Mecanum wheeled omni-directional motion system, the restricted conditions of the system to move in omnidirections are presented. These conditions include relationships of the wheel structure, wheels number and the system lay-out to system to move in omni-direction. The singular configuration of the system is showed out from two class system layouts, it is presented that how to decrease or avoid the singular configuration of the system to move in omnidirections.

    Error Analysis and Compensation of Plane Electronic Compass
    MA Cheng-Yao, QIAN Jin-Wu, SHEN Lin-Yong, ZHANG Ya-Nan
    2009, 15(2):  186-190. 
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    The principle of plane electronic compass is introduced, and the possible error and the error sources are analyzed. The deflection caused by local magnetic influence, for both the source and components, is analyzed. Based on the study, a deflection equation is obtained. The least square method is used for compensation, resulting in a maximum azimuth error of less than 1° so that the accuracy is increased. The results indicate that the methods of compensation can be widely used in similar applications.

    Civil Engineering
    Simulation of Fluctuating Wind Fields around Two Kinds of Civil-Engineering Structures
    XU Xu, QU Ying-Hui, LIU Yu
    2009, 15(2):  191-198. 
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    Using a spectral representation method in the theory of stochastic simulation, and the fast Fourier transform (FFT) technology, fluctuating wind fields around two typical structures are simulated with MATLAB. Time-history curves of fluctuating wind at some nodes are presented. Correlation of different points on the structure is considered. Various methods have been used to verify correctness of the numerical results. The program is showed to be very efficient with the FFT. Meanwhile, precision of the traditional spectral representation is preserved. It is found that the simulation results of fluctuating wind well meet the requirement of engineering analysis.

    Mathematics.Physics and Chemistry
    Interaction between Soil and Inclusions in Retaining Wall Reinforced -with Horizontal and Vertical Inclusions
    PENG Meng-Yuan, HUANG Chao, PENG Ji-Min, ZHANG Meng-Xi
    2009, 15(2):  199-204. 
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    In conventional reinforced soils, the reinforcements are often laid horizontally in the soil. A novel concept of soil reinforced with horizontal and vertical (H-V) reinforcements is proposed in this paper. In the proposed H-V reinforced soil, besides conventional horizontal reinforcements, some vertical reinforcing elements are also placed in the soil. The finite element method is used to analyze the interaction between soil and reinforcements. The strength reduction method is used to study instability of the retaining wall. With the method of c-tanφreduction, comparisons between H-V reinforced soil and traditional reinforced soil in the safety factor and plastic strain distribution are made when the finite element method (FEM) models reach instability.

    Civil Engineering
    High Frequency Fatigue Accelerated Life Test of Concrete
    LIU Kai, LUO Ren-An, ZHENG Ping, TONG Kai
    2009, 15(2):  205-210. 
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    Fatigue strength of highway- and railway- bridges under repeated cyclic loads of vehicles is receiving great concerns from engineers and researchers. However few researches are carried out on high fatigue behavior of concrete. Based on the basic principle of the strength theory of rock and the theory of vibration, a method of high vibration testing is applied to non-metallic fatigue damage mechanics such as rock or concrete. In this paper, plain concrete cylinder specimens were tested under high frequency fatigue loads with constant amplitude. The destructive mechanism of concrete is explained by analyzing the rule of frequency variation curve, and a model for nonlinear fatigue damage accumulation under axial compressive loads is established. By taking survival rate and failure probability into account, a fatigue equation is proposed in a double logarithm form. 

    Life Science
    Effects of Ultra High Static Magnetic Fields on Antioxidation -and Immune Function of Mice
    ZHANG Lu, WANG Yi, HU Jun, WENG Xin-Chu
    2009, 15(2):  211-215. 
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    This study is focused on the antioxidation and immune effect of the strong static magnetic fields on mice. Mice were exposed to ultra static magnetic fields at 12 T for 8, 12, 16 hours respectively. After exposure for 6, 12, 24 hours, their livers were taken to measure the activities of CAT, GSH-Px and content of MDA. Their thymus and spleens were used to measure the index of thymus and spleens and the proliferation of splenic lymphocyte. The results showed that activities of CAT and GSH-Px were increased significantly, but the MDA content was decreased. These phenomena indicated enhancement of antioxidation ability and reduction of the production of lipid peroxidation. Furthermore, proliferation of splenic lymphocyte was increased remarkably and indexes of thymus and spleens were also increased. The results showed that the strong static magnetic fields can improve antioxidation and immune function of the body, thus enhanced the ability to resist diseases and delay aging process.

    Catalytic Activity and Isozyme Patterns of Superoxide Dismutase in Four Species of Capsicums under Cd2+ Stress
    DENG Zhi-Rui, LUO Lin
    2009, 15(2):  216-220. 
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    Catalytic activity and isozyme patterns of superoxide dismutase (SOD) were studied in four species of capsicums at different times under series concentration of cadmium (Cd). The results show that Cd2+ can affect catalytic activity of SOD remarkably and dissimilarly according to its concentration. The highest catalytic activity is 1.4 times higher compared to the control (No.1 species, 100 mg/L for 3 d) while the lowest is only 60% of that of control
    (No.2 species, 150 mg/L for 6 d). Besides, Cd2+ can also affect isozyme patterns of SOD, especially in No.1 species. Two new isozyme bands are induced.