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15 December 2003, Volume 24 Issue 12 Previous Issue    Next Issue
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- - 2003, 24 (12):  1123-1125.  DOI: - Abstract ( 191 )   HTML   PDF (269KB) ( 772 )   - References | Related Articles | Metrics

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Reliable control of regional stability for a class of uncertain linear systems Wang, Fu-Zhong (1); Yao, Bo (2); Zhang, Si-Ying (1) 2003, 24 (12):  1126-1129.  DOI: - Abstract ( 315 )   HTML   PDF (189KB) ( 856 )   The reliable placement of disk pole with actuator failure was discussed for the constant linear system with uncertainty. Based on a more common and actual model of actuator failure, the sufficient conditions were given to the reliable control when allocating the pole into an assigned circular disk. A reliable state-feedback controller was designed through solving linear matrix inequality. A simulation test was carried out to verify the practicability of such a design procedure. Compared with the system taking no account of failure and uncertain factor, the necessity of allocating reliably the pole to a system was proved further. References | Related Articles | Metrics

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Adaptive control of a class of nonlinear composite systems using dynamic neural networks Liu, En-Dong (1); Jing, Yuan-Wei (1); Zhang, Si-Ying (1) 2003, 24 (12):  1130-1133.  DOI: - Abstract ( 240 )   HTML   PDF (171KB) ( 515 )   A design process is presented for a class of nonlinear composite systems to which the dynamic neural network is used to approximate. Nonlinear composite systems are identified by means of dynamic neural network, i.e., use dynamic neural network to approximate to the unknown and interconnected terms of a system. Then design a controller to enable state of the actual system to track the locus of reference model. Based on Lyapunov's stability theory, the tracking error and other signals are proved uniform and bounded eventually. The practicability of such a design process is verified by a simulative example of nonlinear system. A conclusion is drawn that the design process can solve most complicated problems of interconnected terms in a composite system. A law of adaptive control is suggested on neural network basis. References | Related Articles | Metrics

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Study on velocity reference of flying shear Ge, Yan-Jin (1); Gao, Feng (1); Chen, Dong (1) 2003, 24 (12):  1137-1140.  DOI: - Abstract ( 260 )   HTML   PDF (226KB) ( 868 )   The relation between primary and actual velocity reference of a flying shear is discussed during three successive phases including start-up acceleration, as-sheared constant velocity and after-shear returning/positioning. Such technological indices as shearing precision and positioning accuracy of flying shear and smoothness of cut end face of workpieces all depend on the relation between the two velocity references. The relation shall be calculated and output on computer, and it has been applied to some steel rolling mills. The applications show that the actual velocity reference of flying wheel is easy to implement on computer and quite accurate. References | Related Articles | Metrics

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Cluster-based fault diagnosis algorithm in ad-hoc networks Li, Dong-Ni (1); Wang, Guang-Xing (1) 2003, 24 (12):  1145-1148.  DOI: - Abstract ( 221 )   HTML   PDF (127KB) ( 598 )   The issue of fault diagnosis for mobile hosts in ad-hoc networks was studied. The cluster-based comparison diagnosis algorithm is proposed to use in hierarchical ad-hoc networks so as to replace comparison-based fault diagnosis algorithm. Making use of the concentrative control function of cluster heads within clusters, this algorithm can reduce greatly the overhead expenses for the diagnosis to a system in comparison to the comparison-based fault diagnosis algorithm and break through the limitation that the network topology must be fixed in the process of diagnosis. Simulation results indicate that it has a better performance with lower cost than the comparison-based fault diagnosis algorithm. References | Related Articles | Metrics

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Application of association rules and clustering analysis to personalized recommendation Bao, Yu-Bin (1); Wang, Da-Ling (1); Yu, Ge (1) 2003, 24 (12):  1149-1152.  DOI: - Abstract ( 501 )   HTML   PDF (115KB) ( 1338 )   Combining the association rules discovered from pageviews with clustering analysis of access patterns, two methods are presented for personalized recommendation. The first is to take the clustering analysis as a pre-processing procedure for association rules discovery, and the second is to have the association rules supplement clustering analysis. A comparison of the measure of recommendation is made between the two methods and using separately the association rules from pageviews or the clustering analysis of access patterns. The result of comparative testing shows that the first method can improve greatly the precision rate of recommendation, whereas the second one has comparatively high coverage rate of recommendation. Combining the association rules with clustering analysis is unable to improve both the measure precision and coverage rate of recommendation simultaneously. References | Related Articles | Metrics

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Research and implementation of intelligent public telephone system platform Lin, Na (1); Wang, Ze (1); Zhao, Jian-Li (1); Wang, Guang-Xing (1) 2003, 24 (12):  1153-1156.  DOI: - Abstract ( 241 )   HTML   PDF (162KB) ( 395 )   The intelligent public telephone system platform is composed of three sub-platforms including the voice connection, digital running and value-added services. The system combines PSTN with IP network in order to supply varied value-added services for intelligent public telephone. The system adopts the idea of softswitch which separates the calling control from service carrying. The value-added services platform can increase new value-added services through service providers' interface at any time to meet public requirements of new services. Expounding the design and implementation of intelligent public telephone system, the performance of the system is analyzed. References | Related Articles | Metrics

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Fractal image compression based on error threshold Song, Chun-Lin (1); Chi, Dong-Xuan (1); Deng, Xue-Gong (1); Zhu, Wei-Yong (2) 2003, 24 (12):  1161-1164.  DOI: - Abstract ( 205 )   HTML   PDF (171KB) ( 376 )   Starting from reducing the unnecessary computation, the basic fractal image compression algorithm introduced by A.E. Jacquin is improved with a fractal image compression algorithm proposed on error threshold basis. A fixed error threshold is given to compute the total accumulative pixel error of corresponding finite pixels between the child blocks and father blocks, which is then used to find the father block most similar to child block. Experiments indicate that the proposed algorithm can obviously shorten the time of fractal image compression with little changes in compression and signal-to-noise ratios. References | Related Articles | Metrics

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Multicast routing algorithm in IP/DWDM optical internet Wang, Xing-Wei (1); Cheng, Hui (1); Li, Jia (2); Huang, Min (2) 2003, 24 (12):  1165-1168.  DOI: - Abstract ( 236 )   HTML   PDF (163KB) ( 625 )   An integrated QoS multicast routing algorithm in IP/DWDM optical Internet was discussed. Given multicast request and users QoS requirements, an algorithm was proposed on genetic algorithm basis to address the issue routing and wavelength assignment in an integrated manner, construct a flexible QoS multicast tree and assign wavelengths to the tree, based on the wavelength graph method. Thus, both the cost of QoS multicast tree and users satisfaction of QoS approach to optimum. The proposed algorithm also considers load balancing in IP/DWDM optical Internet. Simulation results show that the proposed algorithm is feasible and effective. References | Related Articles | Metrics

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Resource-service efficiency of lead in lead-acid battery Mao, Jian-Su (1); Lu, Zhong-Wu (1) 2003, 24 (12):  1173-1176.  DOI: - Abstract ( 212 )   HTML   PDF (191KB) ( 713 )   The regularity of lead reserve consumption for lead-acid batteries system was studied. Taking the resource-service efficiency as an index and the lead flow diagram of lead-acid batteries life cycle as reference, and how the resource-service efficiency of lead in lead-acid batteries changes was found. The results show that to keep a higher recycling rate, lower lead emission rate, and proper lead-output growth rate are the effective ways to raise resource-service efficiency greatly. The resource-service efficiency in China and Sweden were calculated for comparison to analyze the reasons why the resource-service efficiency is low in China, with some countermeasures proposed to improve the resource-service efficiency. References | Related Articles | Metrics

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Effect of B addition on thermal stability of bulk Zr-Ti-Ni-Cu-Be metallic glasses Wu, Xiao-Feng (1); Zhang, Hai-Feng (2); Yang, Hong-Cai (1); Hu, Zhuang-Qi (2) 2003, 24 (12):  1177-1180.  DOI: - Abstract ( 228 )   HTML   PDF (171KB) ( 480 )   The effect of B addition on forming, crystallization and thermal stability of Zr-Ti-Ni-Cu-Be amorphous alloys was investigated by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and optical microscopy. The results indicate that B addition significantly changes the glass transition temperature (Tg), crystallization temperature (Tx) and supercooled liquid region (▵Tx) of the alloy. When y(B)&le3at%, B addition can keep it in bulk shape with ▵Tx extended and Tg/Tx increased to improve its thermal stability. When y(B)≥6at% , B addition can induce the precipitation of lots of Zr2Cu/ZrB2 coarse crystals which can not reinforce the metallic glass because they are non-nanocrystals in big size and irregular shape. References | Related Articles | Metrics

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Development of multifunction thermomechanical simulator Luo, Zong-An (1); Su, Hai-Long (1); Zhang, Dian-Hua (1); Wang, Guo-Dong (1) 2003, 24 (12):  1181-1183.  DOI: - Abstract ( 272 )   HTML   PDF (140KB) ( 593 )   A new multifunction thermomechanical simulator was developed, by which about 20 functional tests may be fulfilled including tension, compression, torsion, combination of compression with torsion, combination of tension with torsion, etc. With the LabVIEW RT full development system applied to the newly-developed simulator for programming, the high-responsibility control and high-accuracy rapid measurements are available and prove not lower than those of domestic/foreign similar advanced systems. The designed functions, construction, man-machine interface, control system and main performance indices of the simulator are described. References | Related Articles | Metrics

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Application of search system to materials processing technology on mobile Internet Cai, Xiao-Hui (1); Zhai, Xue-Gang (2); Zhang, Li (3) 2003, 24 (12):  1184-1187.  DOI: - Abstract ( 235 )   HTML   PDF (167KB) ( 489 )   A wireless search system WAPSEEKER is integrated on the platform of Windows2000 server terminal. Based on the communication principle between wireless data and Internet, such functional modules as the objective expression of search web pages, automatic query of document information, segment browsing of result information and receiving/sending of user information were implemented by using the embedded programming languages Active Server Page 3.0, VBScript and WMLScript as well as the object-oriented database techniques. Thus, the requirement to access the information on materials processing technology on mobile Internet comes true by GPRS or WAP handset. References | Related Articles | Metrics

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Microstructures and properties of thixoformed pieces of semi-solid A356 alloy Wang, Ping (1); Lu, Gui-Min (1); Cui, Jian-Zhong (1) 2003, 24 (12):  1188-1191.  DOI: - Abstract ( 194 )   HTML   PDF (252KB) ( 1152 )   Heated in a resistance furnace, the solution aging treatment was conducted to the specimens of thixoformed pieces of semi-solid A356 alloy, and the microstructure and properties were investigated. The results show that the strengthening phase is dissolved sufficiently, the alloy elements are distributed uniformly in lattices and the strength is improved along with the prolonging time for solution-aging treatment at 535°C. If aging at 180°C, the strength can be improved further along with the prolonging time for aging till reaching its maximum value. When exceeding the time point, the time prolongs continuously, and the alloy specimens start softening. The occurrence of the distortion zone in thixoforming process plays an important role in alloy strengthening. References | Related Articles | Metrics

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Microwave synthesized LiCoO2 as cathode material for lithium ion battery Zhai, Xiu-Jing (1); Fu, Yan (1); Wang, Yun-Xia (1); Yu, Yong-Li (1) 2003, 24 (12):  1192-1194.  DOI: - Abstract ( 218 )   HTML   PDF (159KB) ( 771 )   Specimens of cathode material LiCoO2 for lithium ion battery were prepared by microwave synthesis to investigate the microstructure, morphology and electrochemical behaviors by means of XRD, SEM and DC-5C battery tester. The results show that a high-purity layered LiCoO2 can be obtained just in a 10-min reaction process at 900 W and 2.45 GHz, The charging capacity is up to 140 mAh/g, and both the platform charging curve and time for charging/discharging demonstrate the electrochemical activity of the microwave synthesized LiCoO2. Testing experimentally the effect of the molefraction of Li to Co on the microstructure of specimens, the optimal Li/Co molefraction should be 1.05/1. References | Related Articles | Metrics

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Lubricating behavior of some sulfuretted fats in rape-seed oil Ma, Jiang-Bo (1); Hu, Jun-Hong (1); Ding, Jin-Yuan (1); Ma, Xian-Gui (1) 2003, 24 (12):  1195-1198.  DOI: - Abstract ( 245 )   HTML   PDF (178KB) ( 684 )   The effect of some sulfuretted fats as additives on the tribochemical properties of rape-seed oil was investigated on a four-ball friction wear tester with refined rape-seed oil taken as base oil. It was found that these fats can improve the load-carrying capacity and antiwear antifriction ability of rape-seed oil, with the wear spot diameters reduced if the small amount of additive increases to a certain extent. The wear spot diameters increase if increasing further the additive amount. The pB and the PD values also increase with the increase of additive amount. In particular the effect of additive RC2540 on sinter charge is so obviously that adding 3% RC2540 enable the pD value to up to 7845 N. The results of SEM and SEDX analysis show that the sulfuretted fats can cause tribochemical reactions in the friction process to form an extreme pressure protection film containing active sulfur element, which plays the role of antiwear and antifriction. References | Related Articles | Metrics

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Kinematic modeling of two parallel manipulators in cooperation Li, Shu-Jun (1); Zhu, Tian-Xu (1) 2003, 24 (12):  1199-1202.  DOI: - Abstract ( 259 )   HTML   PDF (738KB) ( 630 )   An approach to improve the operational performance of single parallel manipulator in form of cooperation of two or more parallel manipulators are introduced. The equivalent close-loop kinematic model and kinematic equation of two parallel manipulators in cooperation are built to lay a foundation for the kinematic analysis and control of parallel manipulators in cooperation by employing the idea of instantaneous cooperating point and instantaneous constraint of workpiece and tool, thus transforming the kinematic problems of two parallel manipulators in cooperation into a solution to the kinematic problems of two single parallel manipulators, on which these parameters are restrained by the workpiece and tool. The computation for an instance has verified the correctness of the model and the validity of developing useful working space by the manipulators in cooperation. References | Related Articles | Metrics

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Elastoplastic bending of bolted moderately thick plates with monoside restraints Li, Ying-Mei (1); Huang, Bao-Zong (1); Li, Gui-Wen (2) 2003, 24 (12):  1203-1206.  DOI: - Abstract ( 213 )   HTML   PDF (167KB) ( 528 )   Considering the contact action by monoside restraints and based on Mindlin's plate transverse shear theory and the support characteristics of bolted moderately thick plates in thin-walled structure, a method to analyze load bearing capacity of bolted moderately thick plates was proposed. The elastoplastic bending of plates supported on two edges of linearly hardened material was studied by FEM method, of which whether the peripheral stress of bolt contacting area goes into the plastic region is taken as a criterion so as to calculate the load bearing capacity. Experiments taking titanium alloy as specimens were conducted for determining the load bearing capacity of the bolted plates and verifying the validity of the proposed method. References | Related Articles | Metrics