Table of Content

30 August 2009, Volume 15 Issue 4

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Communication and Information

Continuous Clock Synchronization Based on WLAN Beacon

CHEN Jian, YANG Xin-Sui

2009, 15(4):  331-335. 

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The requirement of clock synchronization cannot be met in realtime application based on the timing synchronization function(TSF) of IEEE 802.11 WLAN, which uses offset compensation as the clock synchronization protocol. This paper introduces a continuous clock synchronization algorithm (CCSA) based on the beacon value of WLAN to realize master/slave clock synchronization. The proposed algorithm has the advantages of high synchronized precision, continuous tracking, beacon delay and losing tolerance.

Wrapper Scan Chain Balance and Test Scheduling Co-optimization for Core-Based System-on-chip Test

WANG Jia, ZHANG Jin-Yi, LIN Feng, JIANG Yan-Hui

2009, 15(4):  336-341. 

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A new wrapper scan chain balance algorithm called exchange optimization and a new test scheduling method called local optimization are presented in this paper. These two algorithms collaborate on the IP level and top level according to idle bit percentage on test bus (IBPTB) so as to greatly reduce system-on-chip (SOC) test time. To demonstrate the practicality and validity of both algorithms and their cooperation performance, ITC’02 SOC benchmark circuits are used as the experiment objects. The result on core6 in p93791 shows that exchange optimization can achieve more balanced wrapper scan chains than the classic algorithm of best fit decreasing (BFD) by up to 2.6%. The result on d695 shows that the total test time achieved by local optimization according to IBPTB can be up to 12.7% lower than that by the classic integer linear programming (ILP) algorithm.

Cloud Rendering in Flight Simulation and Its Implementation

HUANG Bing, CHEN Jun-Li, WAN Wang-Gen

2009, 15(4):  342-345. 

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Modeling and rendering clouds is an important problem in virtual reality, particularly for virtual display systems, computer games, and 3D animation. This paper studies simulation of clouds, specifically the modeling method, the lighting model and rendering efficiency. Static cloud is modeled based on a particle system. This reduces complexity of the simulation. A multiple illumination model with forward scattering is then used. Billboard and impostor techniques are used to enhance speed. The result shows that visual effect of 3D cloud scene appears quite natural, which can meet the need of real time animation on a generalpurpose computer.

New Method for Noise Removal Based on Anisotropic Diffusion

LAI Xin-ping, HU Hai-ping

2009, 15(4):  346-350. 

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In this paper, we discuss deficiency of the PeronaMalik scheme and some other schemes derived from it, and propose a new operator. The proposed method can avoid difficulties in choosing parameters encountered in Perona-Malik and You-Kaveh schemes, and overcome the pre-smoothing problems in the Catte scheme. Experimental results show that the new scheme can achieve good results in noise removal and detail preservation in image smoothing.

Mechatronics Engineering and Automation

Maximum Power Point Tracking Control Strategy for VariableSpeed ConstantFrequency Wind Power Generation

WU Guo-xiang, CHEN Guo-cheng, YU Jun-jie, YU Lan, MA Yi-wei

2009, 15(4):  351-357. 

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Vector control technique of grid voltage orientation is often applied in ACexcited variable speed constant frequency (VSCF) wind power generation to implement decoupling control of active power and reactive power. Using this method, maximum wind energy tracking can be realized. However, the net power delivered to the grid in the maximum wind energy tracking mode does not reach the upper limit. In this paper, a novel maximum power point tracking control strategy is presented to deliver a maximum amount of power to the grid. The maximum power point can be tracked automatically without measuring wind speed, and the control is independent of optimal turbine power curve. It has excellent dynamic and static performances and good robustness. Simulation and experimental results confirm validity and accuracy of this technique.

Structure Optimization of Saw-Tooth Microvalve Based on Simulation and Orthogonal Test

GUAN Yan-fang, ZHANG Guo-xian, JIN Jian

2009, 15(4):  358-363. 

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The structure of sawtooth microvalve used in valveless micropump with piezoelectric actuator is designed. The orthogonal design is adopted in optimizing the structure. Using the data of flow rate and pressure loss obtained in computational fluid dynamics (CFD) simulation, the range analysis and variance analysis of the different combination of width, depth, length, taper and diffuser angle are performed. The optimal level combination and signicifance level of several structural parameters are obtained. Availibality of the optimal combination is testified in simulation.

Fuzzy Estimation of Residual Capacity for Lead-Acid Batteries

LI Zhi-hua, ZHANG Qing-chun, LIU Zhen

2009, 15(4):  364-368. 

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Based on analysis of residual capacity estimation methods for lead-acid batteries, this paper realized a capacity fuzzy estimation method using electromotive force (EMF) and internal resistance of lead-acid batteries. An empirical equation is obtained from measured EMF and internal resistance, which can be used as feedback of the fuzzy model. It improves performance and stability of the fuzzy controller. Simulated results show validity of the method. 

Mathematics.Physics and Chemistry

Finite Groups with Some Complemented Subgroups of Prime Power Order

GUO Xiao-Jun, GUO Xiu-Yun

2009, 15(4):  369-374. 

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A subgroup H of a finite group G is said to be complemented in G if there exists a subgroup K of G such that G =HK and H∩K=1. In this paper, new results of the structure and properties of a finite group G are given, provided some minimal subgroups and subgroups of prime power order are complemented in G.

Gaussian Measure of Unit Ball and Gaussian Correlation Inequality

XIAO Xiao-Jian, HE Bin-Wu

2009, 15(4):  375-379. 

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Using the Gaussian measure of the n dimensional Euclidean unit ball, it is shown that the Gaussian correlation inequality is true for two orthogonal double cones ellipsoids. Furthermore, the Gaussian correlation inequality is also true for two double cones ellipsoids if the intersection of their images under rotation transformation is ball.

Two-Stage Flowshop Scheduling Problems with Identical and Batch Processors

WANG Wen-Wei, HE Long-Min, SUN Shi-Jie

2009, 15(4):  380-387. 

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This paper considers a two-stage flowshop scheduling problems with m identical parallel machines at stage one and a batch processor at stage two, and minimizes the total completion time. We get optimal solution in time of the order O(n3) when all jobs have the same processing time at stage one and stage two respectively. In the case that all jobs have same processing time at stage one but have arbitrary processing time at stage two, we analyze the worst-case of an approximation algorithm and show that the problem is strongly NP-hard in this case.

One-Dimensional Piston Problem of Pressure-Gradient Equations

ZHANG Li-Yang, CHENG Mo-Cheng

2009, 15(4):  388-393. 

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This paper uses the improved Glimm scheme to study a one-dimensional problem for the pressure gradient equations when the speed of piston is a constant disturbance. We show existence of the weak solution containing shock waves. Using the modified Glimm scheme, we give global existence of shock front solution to this problem in bounded varition (BV) space. 

Numerical Simulation of Usteady Flows over Gliding Flap of  Multi-element Airfoils

FU Yan-Li, LI Xiao-Wei

2009, 15(4):  394-398. 

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Unsteady viscous flows over gliding flap of multi-element airfoils are simulated and studied by using moving overlapped grids and the dual-time stepping method. In order to verify the numerical method, pressure distributions of multi-element airfoils in a steady case are calculated and compared with experimental data. Effects of oscillation amplitudes and frequencies on drags, lifts and moments of the multi-element airfoils are analyzed with unsteady simulations for different gliding velocity of the flap. The obtained results are useful in the design of motion of the flap. 

Experiments on Viscous Flows around Low-Aspect-Ratio Wing at Low Reynolds Numbers

DI Xi-Bo, DING Jue, WENG Pei-Fen

2009, 15(4):  399-403. 

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To investigate viscous flows around low-aspect-ratio wings of a micro-aerial vehicle (MAV) at low Reynolds numbers, experiments are conducted in a wind tunnel using particle image velocimetry (PIV) and a smoke wire technique. The chord Reynolds number is 0.8×10⁴. The results show that flow on the upper surface begins to separate, and primary vortex is generated at the trailing edge when the angle of attack is 5.0°. As the angle of attack gradually increases, separated vortex moves to the leading airfoil. Separated vortex dominates the whole upper surface of airfoil to make the airfoil stalls when the angle of attack reaches 12.5°. In addition, experimental results of two flow visualiztion techniques agree well with each other. Combination of the two techniques reveals more physical phenomena of the flow field, and better reflects the separation of the flow filed on the airfoil surface at low Reynolds numbers.

Influence of High-Order Gradient on Strain Distribution of Nanofibers

CUI Hong-Wei, XU Kai-Yu

2009, 15(4):  404-409. 

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This paper studies the static strain properties of a gradient nanofiber in tension. A new constitutive model based on gradient elasticity is proposed. The influence of high-order gradient of strain on static analysis of nanofibers is discussed. After neglecting the higher infinitesimal strain along nanofiber’s longitudinal direction, the governing equation of equilibrium is obtained with combination of the basic equation and a proposed variational principle. By using both variational and weighted residuals methods, all classical and nonclassical boundary conditions are determined. Some influences of high-order gradient of stain on size and boundary effects are identified and assessed by analytical expressions. 

Treatment of Domain Integrals Using Cartesian Grids for Solving Poisson Equation with Boundary Point Method

JIA Li-Wei, MA Hang

2009, 15(4):  410-416. 

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The use of Cartesian grids is proposed to treat domain integrals encountered in the numerical solution of Poisson equations with boundary integral equations. Traditionally, domain integrals are treated by using internal cells, which makes the algorithm stable and accurate but takes much human labor. By introducing Cartesian grids, the time for data preparation is greatly reduced while keeping all merits of using internal cells. This is because cells have nothing to do with the handling of boundary conditions and the construction of related shape functions in the boundary type methods, but are only for evaluation of the domain’s influences on the boundary unknowns. Techniques of using Cartesian grids are developed and combined with the newly developed boundarytype numerical method, the boundary point method, to solve the Poisson equations. Several numerical examples are presented to show feasibility and accuracy of the proposed algorithm. The effects of the relation between spacing of Cartesian grids and the support of the boundary points on accuracy are investigated in the computations.

Novel Method for Preparing MoO₃/Polyaniline Layered Composite

XIANG Yi-Xian, DONG Xiao-Wen, PAN Qiang-Yi, CHENG Zhi-Xuan, XU Jia-Jiang

2009, 15(4):  417-420. 

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A novel method is proposed for preparing MoO3/polyaniline composite with layered structure. The composite was prepared first by inserting aniline into MoO3 lattice using dodecylamineintercalated MoO3 as precursor, followed by successful polymerization in air. The composite was characterized by powder XRD, SEM, and TGA-DSC. A possible arrangement of intercalated aniline in the gallery of MoO3 is proposed. Its magnetic property has been studied by VSM at room temperature.

Computer Engineering and Science

Finest Level Data Building for Parallel Multi-level Fast Multi-pole Algorithm

GUO Hai-Lin, HU Yue, TONG Wei-Qi, ZHI Xiao-Li

2009, 15(4):  421-425. 

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The finest level data building of a distributed tree is a foundation of parallel multi-level fast multi-pole algorithm (MLFMA). Whether the finest level data is distributed equally or not will affect load balancing of the whole algorithm and its parallel efficiency. This paper studies building methods of the finest level data for the parallel MLFMA. Instead of parallel bucket sort recommended by some authors, a scheme using parallel regular sampling sort algorithm to construct the finest level data of the distributed tree is presented. Experimental results on some common scattering objects with different numbers of processors show that, in most cases, the improved algorithm can achieve better performance than the original one.

Life Science

Genome-Wide Analysis of ACTIN Families in Arabidopsis Thaliana, Oryza Sativa and Populus Trichocarpa

GUO Jing-Kang, CHEN Qing-Yun, JI Qian, ZHANG Liang-Sheng, WANG Jian

2009, 15(4):  426-431. 

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Actins are structural proteins widely distributed in eukaryotes. In plants, the actin cytoskeleton plays an essential role in many cellular processes including cell division and cytoplasmic streaming. Study of the ACTIN gene family is important for understanding the mechanism of these processes. In this study, bioinformatics analysis identified 20, 18 and 22 ACTIN genes respectively in arabidopsis, rice and poplar. A comprehensive overview of this gene family is presented, including chromosome distribution, gene structure, gene duplication, phylogeny, and conserved motifs. The plant ACTINs are organized into 12 subfamilies based on phylogenetic relationship. These results provide clues for study of gene family evolution, and serve as a solid base for future functional genomic studies of the ACTIN gene families in plants.

Inhibition of Traditional Chinese Medicine Extracts on α-Glucosidase from Yeast and Rat Intestines

SI Xiao-Jing, HUO Shi-Xin, SHI Ya, LU Jing-Ci

2009, 15(4):  432-435. 

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Based on resources of the traditional Chinese medicine (TCM) and large amount of prescriptions for diabetic treatment, 52 medicines were selected, and their aqueous extracts, ethanol extracts (60%~70%) of residues after aqueous extracts and ethanol extracts were tested respectively using α-glucosidase activity assays. Their α-glucosidase inhibition effect from rat small intestines and yeast are compared. TCM including mulberry stalk and raspberry have remarkable inhibition effect on rat’s small intestines and yeast at the concentration of 1 mg·mL-1. Four TCM (thanol extracts of residues after aqueous extracts) including Cortex Mori have strong inhibition both on yeast and ratintestines α-glucosidases. Kinetics of enzyme-catalyzed reactions of Cortex Mori was taken. The inhibition type is noncompetitive inhibition, Km=4.352×10-4 mmol·L-1. The results are valuable in research and discovery of new medicines for treatment of diabetes mellitus.

Management Science

Evaluation and Analysis of Efficiency of Joint-Stock Commercial Banks Using the DEA-Tobit Two-Stage Method

YAO Jin-Lan, MAO Ding-Xiang

2009, 15(4):  436-440. 

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Joint-stock commercial bank has been a principal form of the contemporary commercial bank system. This paper evaluates efficiency of China’s 10 joint-stock commercial banks from 1997 to 2004 using the data envelopment analysis (DEA). The Tobit model is applied to analyze the factors affecting efficiency. The result shows that asset profitability is positively related to efficiency of these banks, while the ratio between loans and deposits is negatively related to the efficiency. Both relations are significant. In order to improve efficiency, banks should improve asset quality and maintain balance between profitability and liquidity. Moreover, performance of listed banks is better than that of non-listed banks in terms of efficiency. Therefore it is beneficial to encourage non-listed banks to go public.