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15 November 2004, Volume 25 Issue 11 Previous Issue    Next Issue
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Design of sliding mode observer for disturbed time-delay system Mi, Yang (1); Jing, Yuan-Wei (1); Wei, Xin-Jiang (1) 2004, 25 (11):  1021-1023.  DOI: - Abstract ( 206 )   HTML   PDF (133KB) ( 580 )   An observer design method is proposed for a class of time-delay nonlinear systems. The observer design for the systems without external disturbance is considered first and then the systems with uncertain external disturbance. The delay-time is entirely owing to time variation, and the disturbance is composed of two parts, i.e., a nonlinear term which is assumed to satisfy global Lipschitiz conditions and an uncertain bounded term. The sliding mode theory is applied to stabilizing the error estimation system, based on Lyapunov stability theory. Then, the stability problem can be transferred into the solution to a class of linear matrix inequalities. A simulation example is given to illustrate the feasibility of the presented method. References | Related Articles | Metrics

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Sufficient condition for quadratic stability of switched linear systems Sun, Wen-An (1); Sun, Xi-Ming (1); Zhao, Jun (1) 2004, 25 (11):  1024-1026.  DOI: - Abstract ( 259 )   HTML   PDF (1061KB) ( 657 )   An interval matrix is constructed to transform the switched linear system into interval system. Then, a sufficient condition is presented in terms of matrix inequality for the quadratic stability of switched linear systems under any switching laws. This condition is equivalent to the critical condition for common quadratic Lyapunov function to all subsystems, while it is much simpler than the latter because it needs only one matrix inequality to solve but the latter involves several LMIs with immense computation to do if there are not a few subsystems. A numerical example illustrates the effectiveness of the method. References | Related Articles | Metrics

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Control of pulse synchronization for a class of chaotic systems Huang, Wei (1); Zhang, Hua-Guang (1) 2004, 25 (11):  1027-1029.  DOI: - Abstract ( 208 )   HTML   PDF (1090KB) ( 555 )   Based on the stability theory of impulsive differential equation, a pulse synchronization control method for a class of chaotic systems is proposed. The global asymptotical synchronization of two chaotic systems is realized simply by using the linear error feedback from the state variables of drive and response systems as pulse control signal. Two criterions are thus given to guarantee the global asymptotical synchronization of the two chaotic systems, which could be simplified in case their pulse control matrices and pulse intervals are the same. The method is applicable to a large class of chaotic systems. A controller is therefore designed with Lorenz chaotic system as an example, which is simple and easy to implement with high convergence rate. The theoretic analysis and numerical simulation verified the effectiveness of the method. References | Related Articles | Metrics

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Design and control of bionic limb of biped robot with heterogeneous legs Gao, Cheng (1); Wang, Bin-Rui (1); Xie, Hua-Long (1); Xu, Xin-He (1) 2004, 25 (11):  1030-1033.  DOI: - Abstract ( 243 )   HTML   PDF (261KB) ( 1150 )   On the suggestion that a biped robot is equipped with heterogeneous legs of which one is bionic and the other is artificial, a mechanism scheme of multi-axis knee joint of the bionic leg is proposed, i.e., a four-bar linkage with instantaneous rotating center and bio-imitability. A dynamic model was thus established for the solution to inverse dynamic problem so as to obtain the control moments of knee joint for optimum gait patterns. Acquiring corresponding gait information by sensors, a moment control program was selected on computer, from which each and every gait pattern could be obtained by learning system. The bionic leg supported by MR damper responses rapidly and acts swiftly, especially is more symmetrical and harmonious than the gait of the artificial leg. The effectiveness of such a control has been proved by experiments. References | Related Articles | Metrics

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Real-time kinematics simulation for driver training of wheeled gun vehicles Wang, Yu (1); Cong, De-Hong (1); Xu, Xin-He (1); Hao, Li-Na (1) 2004, 25 (11):  1034-1037.  DOI: - Abstract ( 240 )   HTML   PDF (172KB) ( 691 )   A kinematics model of wheeled gun vehicles is established on the basis of that of common motor vehicles, to which a solution is given for the posture of moving vehicle using the theory of homogeneous matrix. A kind of 3-RPS and 3-DOF parallel robotic mechanisms is used as motion-sensible platform to implement the motion simulation, with a speed formula of actuator given so as to ensure the drive-controllable actuators to move at a preset speed and enable the motion-sensitive platform to perform a real-time simulation of the moving posture of a wheeled gun vehicle in running. The feasibility of the model and the validity of such a system were verified by the simulation. References | Related Articles | Metrics

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Efficient algorithm for computing reliability of acyclic directed networks Sun, Yan-Rui (1); Zhang, Xiang-De (1) 2004, 25 (11):  1038-1041.  DOI: - Abstract ( 229 )   HTML   PDF (249KB) ( 889 )   The relation between node partition and cut set of an acyclic directed network was studied. The minimal cutsets could be obtained directly by partitioning the node set of network into two parts satisfying certain conditions. By the inclusion of the sets corresponding to the node portition, several cancellation rules for the terms in the expression of inclusion-exclusion principle were presented and proved to the network reliability. Using these rules, a formula expressing inclusion-exclusion principle and an algorithm for evaluating the reliability of acyclic directed networks were presented. The algorithm could give directly all the noncancellable terms in the inclusion-exclusion formula, of which the validity was illustrated by examples. References | Related Articles | Metrics

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Security strategy in softswitch Lin, Na (1); Wang, Ze (1); Wang, Guang-Xing (1) 2004, 25 (11):  1042-1045.  DOI: - Abstract ( 227 )   HTML   PDF (149KB) ( 646 )   A feasible solution is proposed to the security problem of SIP protocol in softswitch since no security strategy has been defined by SIP itself. The function characters and working mechanism of SIP protocol in softswitch, especially its existing security problem are described briefly. Then the security strategy, encryption process, security and performance of PGP (Pretty Good Privacy) which is originally designed for encryption and signature of e-mail are analyzed in detail. The widely-used highly secure PGP security strategy is thus introduced into SIP protocol to meet the security requirements of SIP message transmission. Expatiates the implementation of PGP in SIP protocol is expatiated and the formats of SIP INVITE message with PGP encryption and with digital PGP signature is examplified. References | Related Articles | Metrics

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Research and implementation of IC card read-write device with USB interface Li, Ying (1); Wang, Xin (1); Wu, Xiao-Bo (1); Wang, Guang-Xing (1) 2004, 25 (11):  1046-1049.  DOI: - Abstract ( 231 )   HTML   PDF (643KB) ( 726 )   The paper introduces a new solution to the problem of communication between host and IC card read-write device using RS232 interface by way of using USB interface instead. The process how to read and write data through IC card using the I2C bus protocol and the communication process between the USB interface chip PDIUSBD12 and PC host are described. The USB architecture of firmware and the way to develop the function driving program is explained. The IC card read-write device uses USB interface to communicate with host and supports the function of plug and play, thus improving obviously the data transmission rate and ensuring the reliability and portability of the system. The device has been developed and put into applications successfully with its practicability proved. References | Related Articles | Metrics

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Auxiliary table-driven routing algorithm in ad-hoc networks Li, Dong-Ni (1); Wang, Ya-Sha (2); Feng, Jin (1); Wang, Guang-Xing (1) 2004, 25 (11):  1050-1053.  DOI: - Abstract ( 243 )   HTML   PDF (257KB) ( 712 )   After studying the characteristics of moving hosts in an ad-hoc wireless network, a new traffic pattern, namely the rapid-passing pattern, is defined, based on the three traditional traffic patterns. The routing agent algorithm is thus proposed for rapid-passing pattern under which the frequent changes in network topology will lead to heavy overheads for bandwidth and computation and, at the same time, prolong the time delay in the services to be done. As a supplement to current table-driven routing protocols, the routing agent algorithm shall dramatically reduce the packet overheads of route-updating messages due to the change of rapid-moving hosts. The simulation results show that it greatly shortens the time delay required for sending data to the rapid-moving host, thus improving the routing efficiency. References | Related Articles | Metrics

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Fault-tolerant routing mechanisms in IP/DWDM optical internet Wang, Xing-Wei (1); Li, Jia (1); Lin, Wei-Hua (1); Huang, Min (2) 2004, 25 (11):  1054-1057.  DOI: - Abstract ( 317 )   HTML   PDF (696KB) ( 1311 )   Different fault-tolerant routing mechanisms in IP/DWDM optical Internet are discussed. The problem of routing and wavelength assignment with dynamic single/multiple point failures in demand of dynamic traffic is dealt with, such as link/ node/channel failure. The proposed routing algorithm takes load balancing into account, and a heuristic wavelength assignment algorithm is proposed to reduce the end-to-end delay. Based on preventive and reactive schemes, four fault-tolerant mechanisms are put forward. Simulation results have shown that the proposed mechanisms are feasible and effective. References | Related Articles | Metrics

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OS-ESPRIT algorithm Liu, Fu-Lai (1); Wang, Jin-Kuan (1); Yu, Ge (1) 2004, 25 (11):  1058-1060.  DOI: - Abstract ( 292 )   HTML   PDF (218KB) ( 641 )   An OS-ESPRIT algorithm is proposed on the basis of analyzing the features and performances of DOA estimation algorithms of multipath propagation narrow-band signals in wireless network communication environment. The sampling date is virtued of the idea of space smoothing, and by making use of them, the array manifold estimation is transferred to rotational matrix estimation, and only one-step eigenvalue decomposition is needed to estimate DOA. Compared with S-ESPRIT algorithm, the solution process using the proposed approach is simpler with smaller estimation error especially it exhibits higher robustness to the change in signal-to-noise ratio (SNR). It is more available to a lower SNR communication environment. The simulation results show the effectiveness of the algorithm. References | Related Articles | Metrics

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Manchu character recognition post-processing based on bayes rules and substitution set confusion matrix Li, Jing-Jiao (1); Zhao, Ji (1) 2004, 25 (11):  1061-1064.  DOI: - Abstract ( 267 )   HTML   PDF (166KB) ( 569 )   After combining of organically the recognition information on single Manchu characters from relevant system with the information on phrases to set up a statistical information database of Manchu phrases and underdetermined word sets, Bayes rules are used to synthesize the prior probability of underdetermined Manchu word sets and posterior probability of phrases. A data construction is thus developed to improve efficiently the recognition rate, which is rational and easy to implement especially available to detect and correct those rejected and incorrectly recognized words output from the SCR single character recognition system. Experiment shows that the post-processing performance depends on not only the language model but the accurate estimate of posterior probability. In addition, the higher the recognition rate of SCR, the stronger the rectifiability of postprocessing. References | Related Articles | Metrics

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Thermodynamic calculation of austenite decomposition in Fe-C-X alloys Zhu, Li-Juan (1); Wu, Di (1); Zhao, Xian-Ming (1) 2004, 25 (11):  1065-1068.  DOI: - Abstract ( 203 )   HTML   PDF (2278KB) ( 731 )   The introduces the modified KRC and LFG models in association with a superelement model to calculate the equilibrium mole fraction of C at interphase interface, transforming force and temperature of phase equilibrium of γ&rarrα+ γ' and γ&rarrα+ cem transformations. The results show that there is no appreciable difference between the values obtained from the two activity models. The equilibrium mole fraction and phase equilibrium temperature will increase by adding such ferrite stabilizers as Si and Al, but decrease by adding such austenite stabilizers as Mn and Ni. The absolute value of transforming force and phase equilibrium temperature will increase after austenitic deformation. References | Related Articles | Metrics

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Local corrosion rate of conventional tubing steels Li, Jian-Ping (1); Zhao, Guo-Xian (2); Hao, Shi-Ming (1); Lu, Min-Xu (3) 2004, 25 (11):  1069-1071.  DOI: - Abstract ( 287 )   HTML   PDF (210KB) ( 1022 )   The local corrosion rate of tubing steels N80, P105 and SM110, which were usually used in a domestic oil were studied via simulation. The results show that all of the tubing steels exhibit high corrosion rate and that the flow-rate and ratio of crude to water affect most evidently the local corrosion rate. When the water content is up to 100%, the corrosion rates of steel N80 are 15 times and 5 times larger than those when the water content is 30% and 70%, respectively in this respect the steels P105 and SM110 are similar to N80, especially the corrosion rate of PI 05 when water content is 100% is 50 times larger that when water content is 30%. Moreover, it is found that the CO2 partial pressure and Cl- concentration also affect the corrosion rate to a certain extent. References | Related Articles | Metrics

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Structure and magnetic properties of nanocrystalline Fe-Nb-B alloys Zhi, Qi-Zheng (1); Wang, Ji-Jie (1); Chen, Wen-Zhi (2); He, Kai-Yuan (1) 2004, 25 (11):  1072-1075.  DOI: - Abstract ( 327 )   HTML   PDF (165KB) ( 763 )   The effects of annealing temperature on nanocrystallization behavior and magnetic properties of amorphous Fe-Nb-B alloys were investigated by X-ray diffraction, differential scanning calorimeter and static magnetism measurement. It is found in experiment that the magnetic hardening takes place somewhat at the beginning of nanocrystallization process, which is manifested differently by the deterioration of coercive force and maximum permeability. The softer magnetic behavior features the alloys, of which the nanocrystallization structure is composed of α-Fe solid solution and amorphous matrix just before the precipitation of borides (e. g. Fe2B and Fe3B). The magnetic softening was observed increasing with the increase of the volume fraction of nanocrystallization phase, which can be explained by the reason that the decrease in the distance between nanocrystals will result in stronger exchange coupling. References | Related Articles | Metrics

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Thermodynamics of irreversible processes in reaction of hydrogen peroxide Wang, Jin-Xia (1); Zhai, Yu-Chun (1) 2004, 25 (11):  1076-1079.  DOI: - Abstract ( 413 )   HTML   PDF (1062KB) ( 761 )   Thermodynamics of irreversible process offers linear expressions among different physical quantities when there are physical-chemistry changes in the systems close to equilibrium. Extending such existing linear expressions to those systems which are not only far from equilibrium but without dissipative structure formed, a general nonlinear equation is given to express the chemical reaction rate that is the only one in a heterogeneous system. The equation is applied to the catalytic reaction of hydrogen peroxide, i.e., a classical thermodynamic problem, some quartic expressions are obtained in conformity to the experiment data at 298 K and 308 K correspondingly. It shows that the thermodynamics of irreversible process can be applied to those chemical reacting systems which are far from equilibrium if taking the higher terms into consideration. In the higher degree approximation process, however, the different degrees of higher terms require different reactive conditions depending on how far away they are from equilibrium. The extensional application of linear thermodynamic expressions thus provides a new approach to the study on the chemical reactions far from equilibrium. References | Related Articles | Metrics

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Preparation of ultrafine nodular silica powder and its sintering behavior Li, Qing-Hai (1); Zhai, Yu-Chun (1) 2004, 25 (11):  1080-1083.  DOI: - Abstract ( 291 )   HTML   PDF (212KB) ( 1707 )   Ultrafine nodular silica powder was prepared by the controlled hydrolysis of sodium silicate in chlorination ammonia solution at befitting temperature and pH value. The relationships between the time required for powder formation and reacting temperature, pH value, concentration of sodium silicate solution and its flowrate were discussed with some parameters determined for the preparation, i.e., pH value 9, reacting temperature 60°C and concentration of sodium silicate 0.6 mol·L-1. In addition, the relevant sintering behavior at different temperatures for SiO2 was investigated. The results revealed that the ultrafine silica powder would be sintered when the temperature is over 900°C. The structure of nodular powder particles was characterized by TEM and SEM, and the results showed that the silica powder was really of nodular nano-meter particles. References | Related Articles | Metrics

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Thermodynamic study on a quinary solution in equilibrium with a solid cadmium-containing complex Wang, Jun (1); Yang, Dong-Mei (1); Wang, Zhi-Chang (1) 2004, 25 (11):  1084-1087.  DOI: - Abstract ( 273 )   HTML   PDF (151KB) ( 592 )   Aimed at thermodynamic study, isopiestic experiments were carried out at 298.15 K for the quinary aqueous solution (water + potassium chloride + cadmium chloride + mannitol + sorbitol) and its two quaternary sub-systems (water + potassium chloride + cadmium chloride + mannitol) and (water + potassium chloride + cadmium chloride + sorbitol) to equilibrate them with a solid complex containing cadmium chloride and potassium chloride, with sodium chloride (aq) taken as reference solution to determine the osmotic coefficients of the quinary aqueous solution at different aqua activities. The results showed that the isopiestic behavior of the quinary system related to its quaternary sub-systems are well represented by the ideal-like solution model within permissible error range. References | Related Articles | Metrics

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Preparation of Al-Ti alloy by electrolysing TiO2 in aluminium bath Yu, Xu-Guang (1); Qiu, Zhu-Xian (1) 2004, 25 (11):  1088-1090.  DOI: - Abstract ( 271 )   HTML   PDF (184KB) ( 578 )   Al-Ti alloys were produced by molten salt electrolysis using the molten Na3AlF6-Al2O3 system as electrolyte with TiO2 added to it. The morphology and chemical composition of such products were analysed using SEM. The results indicated that the Ti-mass fraction in alloys could be over 9% which exceeded that had been reported by earlier works. The morphological observation showed that Al and Ti existed in form of compounds. Such products can be used as master alloys. The mechanism of preparing Al-Ti alloys by molten salt electrolysis was discussed and regarded as similar to Al-Si alloy formation, because TiO2 was reduced by Al and both Ti and Al were precipitated simultaneously on cathode. So, keeping certain conditions constant will enable the whole electrolysis process to end up. References | Related Articles | Metrics

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Model of dryer HOQ templet automatic generation based on RBFANN Ren, Zhao-Hui (1); Chen, Yi-Zeng (1); Wen, Bang-Chun (1) 2004, 25 (11):  1091-1094.  DOI: - Abstract ( 254 )   HTML   PDF (793KB) ( 553 )   Quality function deployment (QFD) is a well-known customer-driven methodology for new dryer product development, using house of quality (HOQ) to translate customer requirements into all developing stages of dryer products. To solve the QFD problem of conventional dryers, the artificial intelligence theory is introduced in QFD to form new concept, namely intelligent QFD (IQFD). As a key to IQFD, the technology of dryers' HOQ temple automatic generation is studied in depth so as to set up a relevant model based on the radius basis function and artificial neural network (RBF-ANN). An illustrative example shows that the proposed model can convert customer requirements into corresponding engineering characteristics automatically as supported by the knowledge and date bases. As a result, the complication in application of dryers' QFD lowers and the dependence on experience and knowledge of design team is reduced, thus improving deployment efficiency and taking fully the advantage of QFD. References | Related Articles | Metrics

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Optimized job shop scheduling based on genetic algorithm for discretely concurrent production Cui, Hong-Wen (1); Sui, Tian-Zhong (1); Wang, Bin-Rui (1); Jin, Ying-Lian (1) 2004, 25 (11):  1095-1098.  DOI: - Abstract ( 276 )   HTML   PDF (183KB) ( 565 )   By analyzing the scheduling process of discretely concurrent production in CIM system and based on the genetic algorithm, a mathematical model is developed with the intention of optimizing the job shop scheduling to minimize the time required for the whole manufacturing process, the crossover and variation operator of the genetic algorithm designed with the code and each and every integral parts are described in detail. The data base technology was used to develop a visual software for realizing genetic algorithm so as to implement the integration of the scheduling system with other CIMS modules in actual applications. The theoretic analysis and practice indicate that such a genetic algorithm is simple, clear, practical and effective, and the optimization sequencing solved via the algorithm can be taken as a guidance to job-shop scheduling for concurrent production. References | Related Articles | Metrics

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Assembling capacity evaluation based on FNN Yang, Hui-Lin (1); Yan, Yun-Hui (1); Zong, Zhen-Qi (1); Zhang, Hai-Yan (1) 2004, 25 (11):  1099-1102.  DOI: - Abstract ( 238 )   HTML   PDF (241KB) ( 577 )   An evaluation method is proposed on FNN basis for those products which are featured with a big amount of information on assembling process with complicated influencing factors and lots of parameters relying on human judgment/reasoning especially the deficiencies of most of existing evaluation methods to them. According to the characteristic type of a product to assemble, the method shall be done in such a sequence, i.e., construct a database of all assembly information; process fuzzily the conventional 3-level BP network; set up an FNN model for assembling capacity evaluation of which both the inputs and weights have been fuzzed up. Then the weight distribution for optimum neuronal continuity of assembling process are available after a training to the evaluation network in accordance to preset rules. An exemplification shows the applicability and stability of the FNN model. References | Related Articles | Metrics

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Analytic solution based on engaging angle function to disk cam profile with roller-follower Zhang, Wei-Hua (1); Lin, Jing (2); E, Xiao-Yu (1) 2004, 25 (11):  1103-1106.  DOI: - Abstract ( 263 )   HTML   PDF (190KB) ( 825 )   Based on an engaging angle function and introducing the solution to conjugate tooth profile of a pair of gears, the geometrical relation between the working profile of a disk cam and that of relevant roller-follower is investigated at a contact point. A direct analytic solution is thus obtained on the basis of engaging angle function, including the working profile of disk cam, pressure angle and radius of curvature. The solution proposed will provide analytically a new simple and efficient approach to the design of cam mechanism especially a reliable mathematic model available to the CAD/CAM of the pairs of disk cam and roller-followers. References | Related Articles | Metrics

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Soil contamination from heavy metals in west Liaoning coastal multiplex mining area Zhou, Xiu-Yan (1); Wang, En-De (1); Jiang, Li (1); Wang, Hong-Zhi (2) 2004, 25 (11):  1107-1110.  DOI: - Abstract ( 265 )   HTML   PDF (155KB) ( 521 )   Based on the methods of environmental geochemistry, an investigation was carried out on the soil contamination from heavy metals in the multiplex metal mining area and adjacent tilled land in West Liaoning Coastal Zone. The result indicates that highest contents in mass fraction of Cu, Pb, Zn and Cd are up to 0.0236%, 0.0535%, 0.1473% and 0.0012%, respectively. The contents in mass fraction of Cu, Pb, Zn and Cd in top soil are mostly higher than the corresponding background values of the zone, i.e., 1.34-10.67, 1.20-25.59, 0.49-23.31 and 1.87-82.8 times as larger as the background values, respectively. It is proved that there is a comparatively close exponential correlation between the mass fraction of the four elements and those of them leached out in 5% HNO3 solution. In the zone the sources of soil contamination from heavy metals are mainly the free dust during mining, tailings and waste sludge, and the mass fractions of such heavy metals in top soil decrease with the increasing distance away from the contamination sources. References | Related Articles | Metrics

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Design of outer-ring beam of squat reinforced concrete shell silo Wang, Feng-Chi (1); Zhang, Guo-Lian (1); Liu, Shu-Yu (1); Zhu, Fu-Sheng (1) 2004, 25 (11):  1111-1113.  DOI: - Abstract ( 215 )   HTML   PDF (126KB) ( 488 )   The paper use the calculating method of ring structures to analyze the internal forces of an outer-ring beam and simplifies the calculation of shell moment theory to analyze the displacements and turning corners under the actions of membrane force and fringe force. According to the condition under which the displacements at the beam can be coordinated, some formulas are given to calculate the forces and moments of outer-ring beam and their distributions on the shell of squat silo, thus providing a theoretical method for the design of such projects. The analysis indicates that the moments near the outer-ring beam are bigger and become smaller away from the beam. In comparison to the result of finite element analysis and field measurements, the calculating method proposed shows reliable precision. References | Related Articles | Metrics

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Effect of accelerants on adhesion of EPDM to metals Teng, Ya-Di (1); Zhao, Gui-Lin (3); Zhang, Bao-Yan (1); Li, Xu-Ri (2) 2004, 25 (11):  1118-1121.  DOI: - Abstract ( 233 )   HTML   PDF (166KB) ( 912 )   The paper investigates the effect of four different accelerants contained in adhesives, i.e., N-cyclohexyl-2-benzothiazole sulphenamide (CZ), N, N-dicyclohexyl-2-benzothiazole sulphenamide (DZ), dibenzothiazole disulfide (DM) and N, N'-m-phenylene digmaleemide (PDM) on the adhesion of EPDM rubber to metals as well as the effects of their different dosages used on their adhesives. The results indicate that such accelerants contained in adhesives can increase adhesive strength of EPDM rubber to metals. Among them the thiazole accelerants are more effective than imides, but the best one is DM. It is found that the best mass fraction of thiazole is 0.5%, of which the max shear strength is 1.059 MPa. References | Related Articles | Metrics