Table of Content

25 January 2008, Volume 36 Issue 1

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Computer Science & Technology

Design of an Intelligent Network Disk File System

Zhao Yue-long Wang Wen-feng Zeng Wen-ying Song Wei

2008, 36(1):  1-7. 

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In the common network storage system, each disk drive can not automatically work as an initiator and can not balance the workload. In order to solve this problem, this paper puts forward an intelligent network disk （IND） architecture and a novel design scheme of the intelligent network disk file system （INDFS）. The key technologies of the INDFS, such as the file system organization, the file route table, the system command layer, the basic operation algorithm and the file name space, are then described in detail, and the performances of the INDFS are finally tested. The results indicate that the proposed INDFS is flexible and scaleable because the clients can access the IND storage system at a file level.

Reliability Analysis and Modeling of Space Robot Teleoperation Management System

Zhang Ping Lu Ren-qing Liang Bin

2008, 36(1):  8-12. 

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In order to improve the reliability of the space robot teleoperation management system （ SRTMS）, this paper analyzes the architecture of SRTMS, establishes the corresponding reliability model by adopting the stochastic reward net, and analyzes the influences of all the modules on the reliablility of SRTMS. The results show that the command check-up module is the bottleneck for the reliability of SRTMS.

Design of Component-Based Software Architecture for Multi-Mobile Robots

Zhu Jin-hui Min Hua-qing Feng Fan Sun Guang-cheng

2008, 36(1):  13-17,49. 

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In this paper, a component-based software architecture for multi-mobile robot, which adapts to heterogeneous robots and complex tasks, is presented. In the proposed architecture, different components such as sensor, actuator, data fusion, communication and decision, are integrated into an Agent for a special functional robot, and several Agents complete a task by collaboration. Moreover, components and composite components are selfdescribed with extensible markup language （ XML）, and the latter are used as the containers and managers of internal components. Experimental results show that the presented architecture is reusable and flexible.

Design and Implementation of Virtual Teaching System for Humanoid Robot

Gan Zhi-gang Xiao Nan-feng

2008, 36(1):  18-24. 

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The 3D virtual teaching of humanoid robot via virtual reality technology is very significant for improving the control algorithms of a humanoid robot. In this paper, the inverse kinematic calculations are first presented for the humanoid robot with 7-DOF （Degree of Freedom） arms and 6-DOF legs, and the space trajectory planning of the arms and legs is then implemented by means of cubic polynomial interpolation. Furthermore, a 3D virtual teaching system for the humanoid robot is designed and implemented. By teaching the humanoid robot to dance, it is finally proved that the proposed virtual teaching system is correct and feasible.

Model and Algorithms of Grid Task Scheduling Based on Resource Fusion

Lin Wei-wei Qi De-yu Liu Bo

2008, 36(1):  32-37. 

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In this paper, the scheduling of independent tasks on a tree-based grid-computing platform where resources have different speeds of computation and communication is discussed, and an integer linear programming model for the task scheduling on a fiat tree-based grid-computing platform is presented. Then, by adopting the resource fusion approach, the task scheduling on a multi-level tree-based grid-computing platform is converted into the one on a fiat tree-based grid-computing platform, and the corresponding mathematical model is proposed. Based on the proposed model, two heuristic algorithms for task allocation respectively named OPCH and OPBH are finally presented. Experimental results show that the two presented algorithms are of better performance than the First- Come-First-Served （FCFS） and the Min-min algorithms.

An Improved Explicit Congestion Notification Algorithm

Lai Jun Ye Wu Feng Sui-li

2008, 36(1):  38-43. 

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As the algorithm of explicit congestion notification （ECN） in RFC 3168 recommends the gateway to drop packets when the average queue length in the gateway buffer exceeds the upper queue threshold, the network throughput may be too low. In order to improve the system performance, this paper proposes an algorithm named Long-Queue Random Drop （LQRD）. In the proposed algorithm, the gateway drops packets according to a drop probability function when the average queue length in the gateway buffer exceeds the upper queue threshold, thus limiting the continuous increase in queue length. The drop probability function synthetically considers the average queue length, the buffer size, the link capacity and the average queue delay. Simulated results show that the proposed algorithm ensures high throughput, short delay and robust connectivity for long queue length in the gateway buffer. The analytical model of the proposed algorithm is finally analyzed by using the nonlinearly differential equation.

Query Trimming for Semantic Cache Based on Predicate Classification

Li Dong Yang Xiao-peng Luo Peng-fei

2008, 36(1):  44-49. 

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In order to overcome the high complexity of the traditional query-trimming algorithm in time and space domains, a query-trimming algorithm for semantic cache is proposed based on predicate classification. In the proposed algorithm, all predicates are first divided into two different categories, namely restricted predicate and range predicate, which are then defined as semantic satisfaction, semantic intersection and semantic inclusion. Afterwards, a new query-trimming algorithm is presented, with its complexity being also analyzed. The proposed trimming algorithm is finally compared with the traditional serial trimming algorithm based on predicate model and with the trimming algorithm based on logic rules. Simulated results show that the proposed algorithm greatly improves the query-trimming efficiency, especially in the case of intersection between query and cache.

Electronics, Communication & Automation Technology

A Channel-Decomposing Method for Downlink of Multi-User MIMO System

Sun Li-jun Ye Wu Feng Sui-li

2008, 36(1):  50-54. 

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In the block diagonalization （BD） algorithm, the difference in received noise power between users is ignored. In order to solve this problem, a novel channel-decomposing algorithm for downlink is proposed by combining the block triangularization （BT） of downlink channel and the nonlinear Tomlinson-Harashima precoding （THP）. By using the proposed algorithm, the downlink channel can be decomposed into several single equivalent channels with different spatial transmission diversities, and the ＂worst＂ user can obtain the ＂best＂ equivalent channel via precoding. Simulated results show that the proposed algorithm has better performance than the BD algorithm.

Shape-Adaptive Embedded Wavelet Image-Coding Algorithm

Wo Yan Han Guo-qiang Zhang Yan-qing

2008, 36(1):  55-59,66. 

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This paper proposes a shape-adaptive embedded wavelet image-coding algorithm to code arbitrarilyshaped region. The algorithm introduces the significance state matrixes of coefficient and offspring aggregate according to the LMZC （ Low Memory Zerotree Coding） algorithm to reduce the memory requirement, and applies the maximum amplitude variable to avoid the repeating scan of offspring coefficients. In the coding process, if the coding spending of tree structure is greater than the plus, the bit plane method is adopted to code the wavelet coefficients. Experimental results show that the proposed coding algorithm possesses high implementation speed with small working memory, and that, as compared with LMZC and SPIHT （Set Partitioning in Hierarchical Trees） algorithms at the same comp Signal to Noise Ratio）, th ges with compression ression ratio, it may result in better image reconstruction quality and larger PSNR （Peak us coming to the conclusion that the proposed algorithm can code arbitrarily-shaped imaefficiency.

Emotion-Based Image Semantic Query Through Color Description

Wang Wei-ning He Qian-hua

2008, 36(1):  60-66. 

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In this paper, an emotion-based image semantic query scheme through color description is proposed, which bridges the semantic gaps among the low-level image features, the middle-level semantic indicators and the high-level emotional semantics. In the proposed scheme, images are first segmented into regions through color clustering. Next, some natural language vocabularies are defined to describe the color semantics. Then, the semantic terms for color description are proposed based on several fuzzy membership functions. Finally, by combining the experience of human being about image content and the color description, a high-level emotion-based image semantic query is accomplished by defining a query language. Experimental results show that the proposed scheme is feasible, effective and extensive for the semantic investigation of images.

Active Contour Model and Its Application to Volume Segmentation of Medical Images

Tao Ling Qian Zhi-yu Chen Chun-xiao

2008, 36(1):  67-71,75. 

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In order to overcome the instability and uncertainty of the volume segmentation of medical images via the conventional active contour model, this paper proposes an improved active contour model based on the pertinence of gray scale and space position between medical series images. In the proposed model, an internal energy function is constructed according to the distance between the left neighbor midpoint and the right adjoining midpoint, which is limited by restricting the contour length. Then, an external energy function is constructed according to the local gra- dient information of image as well as the overall information and its pertinence in the local region between series images. The weight parameters are automatically regulated according to the ratio of internal energy to external energy. Experimental results show that the proposed algorithm can detect some corner and concave points and can prevent the object edge from converging to noise and pseudo edge points, thus resulting in good volume segmentation effect.

Automatic Segmentation of Pulmonary Parenchyma in Thoracic CT and Computer-Aided Diagnosis

Guo Sheng-wen Chen Jian Zeng Qing-si

2008, 36(1):  72-75. 

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In order to implement the quantitative analysis and aided diagnosis of emphysema, an aaaputive thresholdsegmenting and contour-tracing method was proposed to automatically extract the information of pulmonary parenchyma from high-resolution CT images, and the region and severity of emphysema were then determined according to the quantitative analysis criterion based on density distribution. Experimental results show that the proposed method can segment the pulmonary parenchyma automatically with accurate and effective results, and can statistically analyze the pathological change regions, thus implementing the quantitative analysis and exact diagnosis of emphysema.

Feature Extraction of Acoustic Emission Signals Based on Fractal Dimension and Independent Component Analysis

Liu Guo-hua Huang Ping-fie Gong Xiang Gu Jiang Zhou Ze-kui

2008, 36(1):  76-80. 

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According to the effect of noises on the fractal dimension of acoustic emission （AE） signals, this paper proposes a method based on fractal dimension and independent component analysis （ICA） to extract the AE signal feature of construction material. In the investigation, the concept of fractal dimension is first introduced, and the effect of noises on the fractal dimension is theoretically analyzed. Then, the ICA is introduced to preprocess AE signals, and the fractal dimension is calculated from the independent signal after ICA process, with the AE source lead simulation being finally performed. The results show that the fractal dimensions in different AE sources and transmission media display distinct features, and that the fractal dimension after de-noising corresponds with the emission event number more precisely than that without de-noising. It is thus concluded that the fractal dimension can be used to identify the AE signal feature of construction materials because it is almost independent of the subjects of researchers and is easy to standardize.

Internet-Based Real-Time Teleoperated Mobile Robot System

Wang Shi-hua Xu Bu-gong Liu Yun-hui

2008, 36(1):  81-88. 

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In order to eliminate the impact of variable network delay on teleoperated systems, this paper presents an Internet-based real-time teleoperated mobile robot system by utilizing the predictive control scheme and introducing an improved Smith predictor. Based on the sensor information exchange between the master and the slave, the system guarantees the master and slave models synchronism through a dynamic model manager and its algorithm. Moreover, according to the many arrivals of end-to-end datagram, a new regulating algorithm for delay buffer is pro- posed to transfer a variable delay into the constant one. Virtual model display is also introduced to enhance the realtime efficiency of the system. The usefulness and effectiveness of the developed method and system are finally validated by the teleoperation experiments through long-distance Internet.

Cylinder-by-Cylinder Fuel-Injecting Model of LPG Engine Based on Vector Rotator Coordinate

Xiao Bing Hu Jing Luo Fei

2008, 36(1):  89-93. 

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As the mean-value engine model can not express the differences between cylinders and the corresponding precision is not high enough to satisfy the strict emission laws, this paper presents a cylinder-by-cylinder fuel-injecting model based on the vector rotator coordinate by taking the single-fuel LPG engine as the object, and then proposes an equation to describe the fuel injection of the six independent cylinders of a 6102LPG engine in a fuel life cycle. Experimental results show that the proposed model can accurately estimate the fuel charge of each cylinder, and that the precision satisfies the application requirements well.

Control of Permanent Magnet Synchronous Motor Based on Immune Network Theory

Yu Rui Mao Zong-yuan

2008, 36(1):  94-98. 

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This paper analyzes the immune network theory of immune system and presents a scheme for the adjustment of Proportional-Integral （PI） controller based on the immune network theory. The scheme is then applied to a direct torque-controlled speed-adjusting system of permanent magnet synchronous motor to overcome the variation of flux controller output and the low speed-adjusting accuracy due to the stator resistance variation. As compared with the conventional PI control and the PI control based on genetic algorithm, the proposed scheme is simpler in calculation and more accurate in control even in great stator resistance variation. The effectiveness of the proposed scheme is also verified by simulation.

Pattern Recognizing Algorithm Based on Artificial Immune Network

Deng Jiu-ying Mao Zong-yuan Luo Ying-hui

2008, 36(1):  99-104. 

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The actually complicated objects are difficult to control due to their unknown mathematical models. In order to overcome this difficulty, a pattern recognition algorithm based on the artificial immune network is proposed, in which the discrete models and learning algorithms of artificial immune network are adopted and the functions of artificial immune system are combined with the framework of artificial neural network. After that, an objectmodel based on artificial immune network is constructed. The proposed algorithm merges the positioning and para- meter adjustment of network nodes as well as the parameter tuning of basis functions, etc. Thus, the two stage tasks of Radial Basis Function （RBF） neural network are effectively accomplished and the recognition accuracy is greatly improved. Simulated results in terms of two object functions finally confirm the high convergence speed and great accuracy of the proposed algorithm.

Architecture & Civil Engineering

Constitutive Relationship of Concrete Core Confined by Square Steel Tube

Cai Jian Sun Gang

2008, 36(1):  105-109. 

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In this paper, the bearing mechanism of square concrete-filled steel tube （CFT） stub column under axial load is analyzed, and a constitutive relationship describing the equivalent single-axis compressive stress of the concrete core confined by square steel tube is put forward based on the typical constitutive model of confined concrete, which takes the restriction of steel tube to concrete as the effective lateral compressive stress. Then, according to the experimental results, several key parameters of the proposed constitutive relationship are analyzed and determined. The parameters include the coefficients of ultimate strain and effective lateral compressive stress, the transverse stress of steel tube and the strength. Moreover, the full-time load-strain curves of the square CFT stub column under axial load are obtained by using the proposed constitutive relationship, good accordance between the calculated results and the experimental ones being revealed. It is thus concluded that the proposed constitutive relationship is feasible in the evaluation of ultimate strength and deformation of square CFT stub columns.

Investigation into Early-Age Cracking of Restrained High-Strength Concrete with Casting Surface Exposed to Dry Environment

Ba Heng-jing Su An-shuang Gao Xiao-jian Tao Qi

2008, 36(1):  110-116. 

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In this paper, two devices were respectively developed for the measurements of early-age shrinkage stress and non-contact shrinkage. Then, by exposing the casting surface to the dry environment, the early-age elastic modulus and free shrinkage of the high-strength concrete with the water-to-cement ratios of 0. 26 and 0. 40 were determined respectively using the two devices. Moreover, the inner shrinkage stress and stress gradient of the restrained specimens were investigated through a modified restrained ring test, and the early-age cracking tendency of the restrained high-strength concrete was finally investigated based on the above-mentioned experiments. The results indicate that, for the high-strength concrete, when the water-to-cement ratio decreases, the early-age free shrinkage, the elastic modulus and the inner shrinkage stress under restrained condition all increase, and that the potential of plastic shrinkage cracking on the drying surface improves. It is thus concluded that the high-strength concrete with a low water-to-cement ratio exhibits high tendency of early-age cracking.

Experimental Investigation into Flexural Behavior of Steel Fiber-Reinforced Ferroconcrete T-Shape Beam

Zhu Jiang Zhao Guo-fan Li Shi-en Li Li-juan Guo Yong-chang

2008, 36(1):  117-121,127. 

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Steel fiber-reinforced ferroconcrete （FC） is a new type of high-strength composite material. In order to reveal the flexural behaviors of FC bending members, twelve T-shape beams reinforced by FC were used to test the flexural behaviors, and the beam crack and its development as well as the bending capacity were analyzed. Then, according to the experimental data, a formula was proposed to calculate the bending capacity of the T-shape beams. Moreover, the parameters affecting the flexural behaviors of FC bending members were analyzed. Tested results show that the combination of steel fiber and steel wire mesh greatly improves the bending performance and crack resistance of reinforced concrete beams.

Light-Soil Casting Technology for Disease Repairing of Houmen Tunnel

Pan Jian Liu Jie-wei Chen Hong-bing Qiao Guo-hua

2008, 36(1):  122-127. 

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As compared with the conventional methods to repair tunnel diseases, the casting of light soil to the cavities at the tunnel lining back is more effective. In this paper, the advantages of casting equipment including MT-FQG wind-pressure pouring bottles were analyzed according to the characteristics of light soil, and the engineering characteristics and parameters for foamed light soil were determined. Moreover, a new up-casting construction technique was proposed, which consists of several key steps such as the boring, the second pouring, the pouring and the checking. The proposed technique was finally applied to the filling construction of large-scale cavities in Houmen Tunnel, the results indicating its economic value.

Finite Element Analysis of Seismic Performance of Steel Plate Shear Walls

Shao Jian-hua Gu Qiang Shen Yong-kang

2008, 36(1):  128-133. 

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In order to investigate the seismic performance of steel plate shear wall （SPSW）, the effects of the height-to-thickness ratio on the hysteretic energy dissipation, the energy dissipation per volume, the energy dissipative coefficient and the maximum out-of-plane deformation at the infill panel center are simulated under low cyclic loading via the finite element method that has been verified by experiments, and the corresponding hysteretic out-of- plane deformations are presented. Moreover, the horizontal bearing capacity, lateral stiffness and ductility at different height-to-thickness ratios are further analyzed according to the skeleton curves. The results show that, with the increase in loading displacement, the energy dissipation efficiency of thin SPSW is higher than that of the thick one, and that, with the increase in height-to-thickness ratio, the lateral stiffness and horizontal ultimate bearing capacity decrease but the ductility increases. A height-to-thickness ratio of 300 is finally suggested for the design of SPSW.

A New Interval Optimization Method for Dynamic Response of Multi-Story Frame Structures

Wu Jie Shangguan Wen-bin

2008, 36(1):  134-138,144. 

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This paper presents a new interval optimization method for the multi-story frame structure with uncertain design parameters. In the proposed method, the uncertain design parameters are characterized as intervals, and the interval optimization problem is transformed into an approximate deterministic one by optimizing the upper bound of the structural interval response. A typical four-story frame structure is then used to perform the interval optimization with frequency constraint. The results show that the proposed interval optimization method may result in optimal design parameters similar to that obtained by the conventional method and may help to obtain the variation range of structural response due to the small variation of optimal design parameters, thus laying theoretical foundations of the reliability analysis of frame structures.

Simplified Calculation of Equivalent Consolidation Degree of Ground in Vacuum Preloading

Chen Ping-shan Mo Hai-hong

2008, 36(1):  139-144. 

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For the prefabricated vertical drain （PVD） ground, most analytical solutions of consolidation are very difficult to solve and too many parameters are involved in the solving process. In order to solve this problem, by taking into account the drain resistance and the smear zone effect, the PVD ground is taken as a natural foundation according to the equivalent average consolidation degree, and the analytical solution of one-dimension consolidation is worked out in terms of vacuum preloading, which considers the variation of pore-water pressure on ground surface with vacuum-pumping. Then, the corresponding program is implemented according to the analytical solution. Moreover, the influences of smear zone and PVD drainage capacity on the consolidation process are investigated, and the relevant results demonstrated in graph forms are finally compared with those obtained via finite element method （FEM） and with the in-site data. It is found that the calculated results accord well with the FEM and in-site resuits, and that the calculation results are more simple and suitable for the engineering application.

Geologic Logging Information System Based on Digital Image for Slope Engineering

Li Hao Du Li-li Jia Xiao-min Yang Biao

2008, 36(1):  145-151. 

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In order to realize the computer-aided working and informationlized management of geologic logging, this paper presents a geologic logging information system based on digital image for slop engineering. The proposed system, which is based on the theory of photogrammetry, integrates the techniques of close-rang photogrammetry, di- gital image processing, engineering geology and geographic information system （GIS）, captures images by common digital camera, and processes geometry information in a photogrammetric way. Thus, it decreases the demands for professional equipment and logging skills, and implements the collection, processing, management, analysis and product-outpuning of geologic logging data. Theoretical results and practical applications show that the proposed geologic logging information system is of a mean square error of less than 0.3m which satisfies the corresponding criterion.

Optimized Design of Stochastic Structure Reliability Based on Hybrid Genetic Algorithm

Jiang Feng-guo An Wei-guang

2008, 36(1):  152-156. 

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Based on randomness appeared in stiffness, external load and strength of a structure system in applying, an optimized design method of a structure system is proposed by considering random factors. In the method, sensitivity analysis of the system reliability index is first carried out. Then, the reliability index is considered as a constraint function to establish an optimized model and structure weight is optimized. Here, hybrid genetic algorithm of the traditional genetic algorithm combined with the optimal vector method is presented, and the Niche technology is introduced to perform structural optimized design. Analytical results indicate that the hybrid genetic algorithm based on Niche technology not only has the strong local searching capacity of the optimal vector method but also has the strong general searching capacity of the genetic algorithm, so convergence performance is greatly improved. Calculated example indicates that hybrid genetic algorithm based on the Niche technology is a high-effective structural optimized method.