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15 July 2004, Volume 25 Issue 7 Previous Issue    Next Issue
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Reliable control with variance constraints for linear uncertain systems Wang, Fu-Zhong (1); Yao, Bo (2); Jing, Yuan-Wei (1); Zhang, Si-Ying (1) 2004, 25 (7):  613-616.  DOI: - Abstract ( 232 )   HTML   The design of state feedback reliable control of linear uncertain system is studied. The reliable control guarantees the closed-loop poles within a specified area and steady-state variance. A more practical and common actuator fault model than outage is adopted. Using linear matrix inequalities (LMI) approach, the existence conditions of such reliable controller are derived without introducing additional conservation. A acceptable variance upper bound is guaranteed in case of actuator fault, and the performance index is optimized in the normal case. An example is given to illustrate the proposed design procedure. Simulation results show the effectiveness of the design method. The normal controller and the reliable controller are compared to show the necessity of reliable control. References | Related Articles | Metrics

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Discriminatory condition for weak controllability of nonlinear large-scale system Han, Zhi-Tao (1); Duan, Xiao-Dong (2); Zhang, Si-Ying (3) 2004, 25 (7):  617-620.  DOI: - Abstract ( 186 )   HTML   PDF (358KB) ( 719 )   The controllability of large-scale nonlinear system is discussed by virtue of the weak controllability of common nonlinear system to define the weak controllability of large-scale nonlinear system, while the large-scale nonlinear system is weakly controllable since the nonlinear subsystems are the same. The necessary and sufficient condition of a weakly controllable large-scale nonlinear system is that every subsystem of the large-scale nonlinear system is weak controllable. It is proved that a large-scale nonlinear system is weak controllable if only every Lie Algebraic expression of controllability of subsystem can satisfy its controllability rank condition, regardless of the controllability of the large-scale nonlinear system, as well as a nonlinear system that is weak controllable if its Lie Algebraic expression of controllability can satisfy its controllability rank condition. References | Related Articles | Metrics

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Delay-dependent H∞ control of linear neutral delay systems Zhang, You (1); Qi, Li (1); Jing, Yuan-Wei (1); Zhang, Si-Ying (1) 2004, 25 (7):  621-624.  DOI: - Abstract ( 204 )   HTML   PDF (361KB) ( 573 )   The design of H∞ static feedback controller is studied for a class of linear neutral delay system. Based on the concept of H∞ performance in time domain, Lyapunov-Krasovskii stability theorem and linear matrix inequalities are used to establish a delay-dependent stability criterion, then a sufficient condition is derived to stabilize asymptotically the neutral system under consideration and satisfy the desired H∞ bound constraint on the disturbance attenuation. A sufficient condition is given to the existence of a H∞ memoryless state-feedback controller with the conceptual design. The conclusion shows less conservation in comparison with the delay-independent H∞ controller of the system. The numerical simulation verifies the validity and effectiveness of the proposed approach. References | Related Articles | Metrics

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H∞ control for a class of nonlinear singular systems Dong, Xin-Zhuang (1); Zhang, Qing-Ling (1) 2004, 25 (7):  625-628.  DOI: - Abstract ( 175 )   HTML   PDF (1270KB) ( 672 )   The design of static state feedback H∞ controllers is discussed for a special class of nonlinear singular systems of which the state equation can be divided into linear part and nonlinear part. By means of the generalized Lyapunov function and Lyapunov equation, a sufficient condition that a nonlinear singular system is zero solution asymptotically stable is given. A sufficient condition is derived in terms of algebraic Riccati inequality which makes the nonlinear singular system zero solution asymptotically stable with a H∞ norm constraint. The existence condition of a state feedback H∞ controller is presented, guaranteeing that the resulting closed-loop system has above performance. The design method of such a controller is provided in terms of the solution to Lyapunov equation. An example is given to prove the validity of the results. References | Related Articles | Metrics

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Criterion for finite fixed modes in singular symmetric systems Wang, Jing (1); Zhang, Qing-Ling (1); Liu, Wan-Quan (2) 2004, 25 (7):  629-632.  DOI: - Abstract ( 196 )   HTML   PDF (295KB) ( 626 )   Defining the singular symmetric systems and singular state-space symmetric systems, their fixed polynomials are analyzed. The criterion for the existence of finite fixed modes of the singular systems with symmetric structure is investigated by analyzing the relation of inequality of matrix rank, and the relationship between uncontrollable and unobservable modes is obtained. A solution is thus given to the finite fixed modes. The results show that the finite fixed mode set in singular symmetric system is composed of all the finite uncontrollable and unobservable modes. Compared with the results known before, the proposed method is more effective and simpler. References | Related Articles | Metrics

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Fuzzy adaptive control scheme Zhang, Ming-Jun (1); Zhang, Hua-Guang (1) 2004, 25 (7):  633-636.  DOI: - Abstract ( 223 )   HTML   PDF (1074KB) ( 527 )   A fuzzy adaptive control scheme based on generalized fuzzy hyperbolic model (GFHM) for unknown nonlinear uncertain systems was proposed. Using GFHM as an identifier model for unknown nonlinear object, it can provide the gradient information necessary to the parameter self-adjusting of fuzzy adaptive controller. Comparing GFHM with other identifiers, the number of unknown parameters and identification complexity of GFHM are both less, while the accuracy of approximation is easy to be improved. Gradient algorithm of adaptive controller enables the output of controlled object to track the expected output very well. The simulation results show that the proposed scheme has powerful adaptive tracking ability for the signal input of unknown nonlinear system. References | Related Articles | Metrics

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Heuristic algorithm for location-allocation problem in integrated distribution Zhang, Qian (1); Gao, Li-Qun (1); Hu, Xiang-Pei (2) 2004, 25 (7):  637-640.  DOI: - Abstract ( 289 )   HTML   PDF (159KB) ( 716 )   A model of location allocation was set up to approach further to the actuality of goods/service distribution, based on the conventional 0-1 mixed programming model by Baumol-Wolfe. A heuristic algorithm was proposed to combine different customers' demands into a minimum wrap-net for the location of distribution centers in accordance to the assumption that in every defined service area of a distribution center the aggregate demand of a group of customers is equal or near to the integral multiple of unit vehicle capacity. The minimum wrap is formed by taking a distribution center as a basis point and connected to other centers with straight lines as distances. Making bisectors vertical to these lines and forming a minimum wrap are envoloped, in which all the tangent points of the circles taking relevant half of such distances as radii, so that a shortest distance is available to a defined group of customers to go to a nearest center as they are within its service area. The algorithm has the advantage of taking account of not only the different distances among customers but also their different distance demands. The model will benefit the solution to actual location-allocation problem. The computer simulation proves the validity of this method. References | Related Articles | Metrics

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Basic time rotation model used for constructing data warehouse Xia, Xiu-Feng (1); Cong, Li-Hui (2); Yu, Ge (1) 2004, 25 (7):  641-644.  DOI: - Abstract ( 226 )   HTML   PDF (141KB) ( 722 )   Analyzing some conventional ways to construct data warehouse, a time rotation model that can be used to construct data warehouse is developed. The concept and implementation principle of basic time rotation mechanism are introduced and characteristics of this model are analyzed. The method of constructing a basic time rotation model based on rough time set and related operations are described with its application exemplified. Compared with conventional data warehouse construction strategies, the time rotation mechanism can provide the idempotence for data totaling and is more serviceable for on-line analytical processing, data mining and decision supporting system. The data extraction efficiency, data storage efficacy and operation convenience of data warehouse constructed by the time rotation model will be improved obviously. References | Related Articles | Metrics

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Kind of VLAN model based on service Wang, Xiao-Ying (1); Zhao, Hai (1); Zhang, Wen-Bo (1) 2004, 25 (7):  645-648.  DOI: - Abstract ( 224 )   HTML   PDF (662KB) ( 452 )   Drawbacks and limitations of previous virtual local area network (VLAN) implementation methods in Ethernet environment are analyzed. Then a kind of VLAN administration strategy based on service is proposed to set up the virtual local area network (VASS) administration strategy system architecture, i.e., a fairly integrated VLAN architecture based on service. A simulation and UDP video transmission experiment were conducted and the results show that VASS can properly control broadcast traffic and decrease local area network route traffic flow to a great extent so as to improve network system's ability to withstand broadcasting storm. The distribution of network resource adaptable to the model is more flexible and effective than before with the network service efficiency improved. References | Related Articles | Metrics

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WebitX: A real-time operating system for embedded Internet applications Guan, Mo (1); Han, Guang-Jie (1); Zhang, Wen-Bo (1); Zhao, Hai (1) 2004, 25 (7):  649-652.  DOI: - Abstract ( 257 )   HTML   PDF (152KB) ( 584 )   An embedded real-time operating system WebitX is proposed and implemented on the basis of micro-kernel architecture to meet various complicated requirements of developing the embedded Internet applications. WebitX's kernel, as a preemptive real-time and multi-task one based on priority, can provide such system services as task scheduling, synchronization and communication, priority inversion, real-time clock and network protocols to achieve its real-time performance and reliability of embedded Internet applications. The experimental results show that WebitX can meet the demands of developing the Internet applications in most embedded systems and decrease greatly the R and D difficulty of embedded software. WebitX provides the technical assistance for implementation of network and intelligent management in embedded devices. References | Related Articles | Metrics

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Fault assessment /diagnosis based on fuzzy expert system Su, Yu (1); Zhao, Hai (1); Su, Wei-Ji (1); Zhang, Xiao-Dan (1) 2004, 25 (7):  653-656.  DOI: - Abstract ( 378 )   HTML   PDF (187KB) ( 1313 )   A method of fault assessment/diagnosis that combines fuzzy logic with expert system is put forward to the uncertainty problems to be solved in equipment fault diagnosis. It is done in the way the rules originated from fuzziness are introduced in fuzzy expert system to express knowledge obtained with fuzzy matching procedure adopted in the uncertainty reasoning process to implement the diagnosis based on knowledge through a strategy to resolve conflicts with the confidence level taken as criterion. The functional components and implementation of the fuzzy expert system are introduced, which has been applied to the fault diagnosis using gas chromatography for power transformers. The percentage of accuracy of the method is up to 95.7% as proved by the practical diagnosis done in site near 100 times, verifying the fact that applying the fuzzy expert system to the diagnosis for power transformers is applicable. References | Related Articles | Metrics

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Fusion algorithm for uncertain information by fuzzy decision tree Zhang, Xiao-Dan (1); Zhao, Hai (1); Wang, Gang (1); Wei, Shou-Zhi (1) 2004, 25 (7):  657-660.  DOI: - Abstract ( 353 )   HTML   PDF (192KB) ( 1098 )   Aiming at acquiring new knowledge, a method is proposed. It takes advantage of the ID3 algorithm of fuzzy decision tree to analyze and process comprehensively numerous multi-source information data in test space, develops an accurate evaluation model and extracts its implied rules. The method has been applied to the examination system of a numerical simulation system in Fengman Hydropower Station, Jilin. Experimental results indicate that such a method for knowledge extraction represents the information fusion idea solving the question of multi-source data, and the high efficiency in processing numerous disorderly and uncertain data. References | Related Articles | Metrics

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Scheduling scheme for proxy-assisted video-on-demand Hu, Yu-Qi (1); Zang, Huai-Quan (2); Gao, Yuan (1) 2004, 25 (7):  661-664.  DOI: - Abstract ( 258 )   HTML   PDF (248KB) ( 565 )   To utilize network bandwidth efficiently, a video-scheduling scheme named CMP (client multicast patching) is proposed for distributed proxy-assisted video-on-demand. When an appointed client plays out a video, it is also acting as a server to transmit the patching segments via multicast for subsequent clients in local area network. The abundant resource of the network bandwidth can be utilized fully instead of remote server and backbone network bandwidth, without extra I/O bandwidth needed by the appointed client and with instantaneous services provided for client requests. The scheme is adaptive to video popularity and supports all client request rates without bandwidth bottleneck. A simulation shows that significant network resource can be saved by using the scheme. References | Related Articles | Metrics

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Recrystallization texture of grain-oriented silicon steel thin strip under magnetic field Sha, Yu-Hui (1); Liu, En (2); Xu, Jia-Zhen (1); Zuo, Liang (1) 2004, 25 (7):  665-667.  DOI: - Abstract ( 249 )   HTML   PDF (162KB) ( 710 )   The commercial grain-oriented silicon steel was reduced to thin strips via symmetric and asymmetric cold rolling, which were annealed with and without magnetic field. The effects of magnetic field and asymmetric rolling on primary recrystallization textures were investigated. It was found that magnetic annealing can significantly increase Goss texture component ({100}<100>) in symmetrically rolled thin strip but decrease it in asymmetrically rolled thin strip. Asymmetric rolling can increase Goss component after ordinary annealing but decrease it obviously after magnetic annealing. The effect of magnetic field on recrystallization texture can be explained in terms of the change in grain boundary migration caused by magnetocrystalline anisotropy energy and magnetic ordering. References | Related Articles | Metrics

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Preparation of Ti-alloy matrix composite with bioactive glass-ceramic coating Ren, Xiao-Yu (1); Zhang, Xiao-Bin (1); Sun, Xiang-Yun (1); Liu, Chang-Sheng (1) 2004, 25 (7):  668-670.  DOI: - Abstract ( 235 )   HTML   PDF (144KB) ( 547 )   The bioactive glass-ceramic powder A-W in which the phosphorite and wollastonite are contained is used to coat twice the Ti-alloy TC4 by way of enamaling process so as to prepare the Ti-alloy matrix composite with bioactive glass-ceramic coating. The effects of mass fraction of the powder A-W and entrapped bubbles in primary coating on the bonding strength between matrix and coating after sintering were investigated. The results show that when the A-W mass fraction in primary coating is 50%, the amount of fused neutral glass in the coating is enough to wet down the matrix so as to bond firmly the powder A-W to the matrix, and the entrapped bubbles in the coating are so small and even as to buffer the sintering stress. It was found that the bonding strength between matrix and coating is higher than 10 MPa. The secondary coating is all of pure powder A-W to ensure the bioactivity of the composite. References | Related Articles | Metrics

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Roll eccentricity analysis and simulation based on wavelet transform Zhang, Yan-Hua (1); Liu, Xiang-Hua (1); Wang, Guo-Dong (1) 2004, 25 (7):  671-673.  DOI: - Abstract ( 281 )   HTML   PDF (611KB) ( 614 )   In view of the intrinsic imperfection in identifying roll eccentricity by way of the fast Fourier transform, a method is proposed to identify the roll eccentricity, based on wavelet transform to improve the delivery gauge of hot-rolled strips, etc., the difference of transmission characteristics of the maximum wavelet modulus between singular signal and random noise in multiscale space is utilized to analyze the signals from rolling load and thickness deviation so as to separate the signal from random noise and realize the dynamic compensation for roll eccentricity. The simulation results show that the roll eccentricity compensation based on wavelet transform is better than the fast Fourier transform or its modification for improving delivery gauge of which the thickness fluctuation due to roll eccentricity can be reduced by more than 90%. The proposed method is more effective and adaptive to outside interference especially to real-time dynamic compensation control of roll eccentricity. References | Related Articles | Metrics

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Effect of rolling parameters on plane shape of plates Liu, Hui (1); Wang, Guo-Dong (1); Liu, Xiang-Hua (1) 2004, 25 (7):  674-677.  DOI: - Abstract ( 261 )   HTML   PDF (201KB) ( 812 )   An analog computation was carried out with the FEM (finite element method) software ANSYS-DYNA for the edge, spread and finish rolling processes of thick/medium plates which were rolled with different rolling parameters. The results show that after spread rolling the front end of slab plane changes to dishing from bulging with increasing edge reduction but its back end always keep the slab plane in bulging form, and the length and width fluctuations of both front and back end crops of the slab are similar to that after spread rolling. Less width fluctuation is available via edge rolling if the proportional spread is big. In order to get a favorable plane shape of plate after the whole rolling process, both the longitudinal edges of the slab after spread rolling will be kept in straight or slightly convex. The results of analog computation thus provide a theoretical reference to match rationally the edge reduction, proportional spread and elongation in finish rolling. References | Related Articles | Metrics

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Experimental study on heat-resistant tube blank by electromagnetic centrifugal casting Qiu, Yi-Qing (1); Jia, Guang-Lin (2); Teng, Zhi-Yuan (3); Liu, Xiang-Hua (1) 2004, 25 (7):  678-681.  DOI: - Abstract ( 255 )   HTML   PDF (229KB) ( 466 )   The solidification structure and mechanical properties of 1Cr25Ni20Si2 tube blank were investigated, which was acquired through the joint fields of electromagnetic and centrifugal force. The results show that if a steady magnetic field of appropriate magnetic induction is applied in centrifugal casting process, the solidification structure of the blank can be improved markedly with its impact toughness and elongation improved correspondingly. But the mechanical properties of the blank will drop if increasing the magnetic induction further after it reaches >0.04 T. By analysis, it was concluded that electromagnetic stirring, induced due to interaction between steady magnetic field and rotating metal melt, is radical reason that solidification structure and mechanical properties of heat-resistant tube blank are improved. References | Related Articles | Metrics

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Movement of metallic impurity particles in aluminum melt in steady magnetic field Zhang, Lei (1); Yao, Guang-Chun (1); Jiao, Wan-Li (1) 2004, 25 (7):  682-684.  DOI: - Abstract ( 217 )   HTML   PDF (821KB) ( 501 )   A force analysis was made to the impurity particles in Al melt in steady magnetic field to set up the movement models of these particles in different flow field, thus determining their final velocities under the action of magnetic force by theoretic calculation. According to the different flow states of aluminum melt, the models of piston flow and trajectory were used to obtain the separating efficiency of impurity particles under the action of magnetic field, respectively. The results show that the motional velocity and separating efficiency of inclusion particles relate closely to their volume, flow state, magnetic susceptibility of inclusions, magnetic field intensity and the width of separation passage. The larger impurity particles have higher separating efficiency with the same motional velocity of Al melt, and reducing the motional velocity of Al melt benefits the separating efficiency. References | Related Articles | Metrics

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Implementation of reconfigurable production line based on agent and holon Huang, Xue-Mei (1); Wang, Yue-Chao (2); Tan, Da-Long (2); Zhao, Ming-Yang (2) 2004, 25 (7):  685-688.  DOI: - Abstract ( 257 )   HTML   PDF (148KB) ( 788 )   With a production line of large-scale series production taken as industrial background, the intelligent manufacturing technology of multi-agent and holonic manufacturing methodologies is applied to the construction of reconfigurable production line to improve the flexibility and reconfigurability of manufacturing system. Focusing on self-decision, the cooperation/coordination mechanism of intelligent entities in multi-agent and holonic manufacturing methodologies and the implementation/operation mechanism of manufacturing system are studied, as well as the application techniques in actual industrial background, e.g., the machining/assembly line which has been investigated by other researchers aiming at improving flexibility and reconfigurability. An assembly line of automotive transmission is taken as a case study from the viewpoint of planning and operating a production line, then the infrastructure construction by intelligent manufacturing cell and implementation methods in control, reconfigurable algorithms, product description and migration of system configuration are discussed. References | Related Articles | Metrics

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Genetic algorithm in compound form for structural optimization with discrete variables Zhu, Chao-Yan (1); Liu, Bin (1); Zhang, Yan-Nian (1); Guo, Peng-Fei (2) 2004, 25 (7):  689-691.  DOI: - Abstract ( 268 )   HTML   An approach for the generation of initial point is proposed for discrete compound form. In view of the theory of imitative full-stress, the optimization results of discrete compound form are searched further, so as to improve fully the local searching capability of discrete compound form. A compound form operator is imbedded in genetic algorithm so as to improve the local searching capability of genetic algorithm to make up for the shortage of genetic algorithm. The operation of standard genetic algorithm is also improved, e.g., a high cross rate is taken in the early stage of evolution to pick out the best individual as fast as possible with a high mutation rate taken for the worst individual to approach to optimal solution. A hybrid genetic algorithm is set up for structural optimization with discrete variables. The results by exemplification show that the hybrid genetic algorithm, as an efficient optimal method having the advantages of both standard genetic algorithm and improved compound form approach without their disadvantages, is superior to either one. References | Related Articles | Metrics

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Application of improved genetic algorithm in optimum design of building structures Zhang, Yan-Nian (1); Liu, Bin (1); Dong, Jin-Kun (1); Guo, Peng-Fei (2) 2004, 25 (7):  692-694.  DOI: - Abstract ( 241 )   HTML   PDF (164KB) ( 1153 )   In view of that the standard genetic algorithm (SGA) has such frequent shortcomings as premature convergence, oscillation and over-randomization in iterative process, a genetic operator named transgenic operator is proposed to improve SGA. The transgenic operator can make good use of the information of which the adaptability has been calculated, keep the best individual from missing, and improve the adaptability of every chromosome in the population. The improved genetic algorithm (IGA) including the transgenic operator could be used directly to work out the optimum structural design with discrete variables to constrain both stress and crass-section area and could be dealt with the discrete structural optimization featured with multi-loading, multi-constraints and multi-variables. The results by exemplification show that the performance of convergence and optimization results of IGA are superior to that of SGA and it is an ideal method for optimum design of building structures. References | Related Articles | Metrics

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Evolutionary neural network constitutive model for complete stress-strain relationship of rock under chemical corrosion Chen, Bing-Rui (1); Feng, Xia-Ting (1); Ding, Wu-Xiu (2); Yang, Cheng-Xiang (1) 2004, 25 (7):  695-698.  DOI: - Abstract ( 237 )   HTML   PDF (268KB) ( 678 )   An evolutionary neural network constitutive model is proposed to describe the whole stress-strain process of rock under chemical corrosion. Differing from other conventional models, the model reflects the whole stress-strain process of rock under chemical corrosion in terms of its network topology and weights and it is constituted by genetic algorithm with favorable prediction function. After training with samples in which sufficient stress-strain information are involved, the model will indicate the complete stress-strain relationship of a mineral that is the same to the sample which has been corroded by different chemical solutions. This has been proved by a practical example. The model is recommended to apply for prediction of the whole stress-strain process of a rock that would not participate in the training by evolutionary neural network. References | Related Articles | Metrics

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Integrity detection of foundation piles driven into oozy ground base Xu, Bai-Shan (1); Jin, Cheng-Zhu (1); Tian, Gang (2); Huang, Hang (2) 2004, 25 (7):  699-702.  DOI: - Abstract ( 256 )   HTML   PDF (201KB) ( 835 )   GPR (ground penetrating radar) technique has the advantages of quick, accurateness and real-time processing/display especially available to collect continuously high-resolution sections of underground pile. Investigating quantitatively and qualitatively the relationship of GPR information to the pile integrity including shape and length of macadam, powder spray pile and bottom expansion pile, a complete set of applications of GPR technique and relevant operation procedures was and proposed as supplement to the conventional detection procedure. The characteristics of testing and detection technique were discussed and evaluated under different conditions, with proposed method exemplified to verify its feasibility and usefulness. The results show that GPR technique will provide a big amount of detailed reliable information to the engineering quality inspection of underground piles of composite foundation structures. References | Related Articles | Metrics

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- - 2004, 25 (7):  703-706.  DOI: - Abstract ( 216 )   HTML   PDF (242KB) ( 814 )   - References | Related Articles | Metrics

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- - 2004, 25 (7):  707-710.  DOI: - Abstract ( 270 )   HTML   PDF (302KB) ( 835 )   - References | Related Articles | Metrics

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- - 2004, 25 (7):  711-714.  DOI: - Abstract ( 186 )   HTML   PDF (302KB) ( 657 )   - References | Related Articles | Metrics