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15 April 2004, Volume 25 Issue 4 Previous Issue    Next Issue
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Decentralized robust stabilization for uncertain composite system with input saturation Zhai, Ding (1); Zhang, Qing-Ling (1); Chen, Yue-Peng (1); Liu, Guo-Yi (1) 2004, 25 (4):  307-309.  DOI: - Abstract ( 261 )   HTML   PDF (1110KB) ( 547 )   The sufficient conditions enabling an uncertain composite system with input saturation to stabilize its state feedback are obtained by use of decentralized robust linear-state feedback control. A new approach to the design of decentralized robust controller is thus found on input saturation basis. Giving the definitions of saturation function and M-matrix, how to get the decentralized robust stabilization is proposed for composite systems. Then based on M-matrix theory together with a Lyapunov equation constructed, the problem is discussed by virtue of an algebraic Riccati equation. The simplified sufficient conditions are therefore offered for the decentralized robust stabilization of uncertain composite systems with input saturation, as well as the decentralized robust feedback control law of the systems in special cases. References | Related Articles | Metrics

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Passive control of linear singular systems via output feedback Dong, Xin-Zhuang (1); Zhang, Qing-Ling (1) 2004, 25 (4):  310-313.  DOI: - Abstract ( 484 )   HTML   PDF (1604KB) ( 1400 )   The definition of strict passivity is proposed for singular systems and the passive control problem of linear singular systems is discussed via output feedback. By means of linear matrix inequalities, a sufficient condition is derived such that a definite singular system is not only admissible (i.e. regular, stable, impulse-free) but also strictly passive. Based on such a condition, the sufficient conditions for the existence of either static or dynamic output feedback controller are given to make sure that the closed-loop system is admissible and strictly passive. Moreover, under certain conditions, the static and dynamic output feedback control laws are designed in terms of the solution of matrix inequalities. An example was provided to prove the validity of the sufficient conditions. References | Related Articles | Metrics

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Knowledge acquisition by rough set based on incomplete data sets and its application in fault diagnosis for electricity networks Zhang, Tie-Yan (1); Sun, Qiu-Ye (1); Zhang, Hua-Guang (1); Liu, Li (1) 2004, 25 (4):  314-317.  DOI: - Abstract ( 274 )   HTML   PDF (168KB) ( 748 )   A newly reduced algorithm based on rough set (RS) theory is proposed for fault diagnosis in case no complete data are available when the power network failed and then caused possibly the protections/breakers to malfunction and/or the transmission defects in communication. Furthermore, the reduced result can be synthesize into one as a tabulated expert decision library. With fuzzy sets and probability applied to the rules of rough sets, the confidence levels of each rule and relevant equipment are taken into consideration and computed. Another algorithm is also proposed to analyze synthetically the confidence level of a diagnostic conclusion in accordance to the number of rules for a certain decision-making process and the confidence level of each rule, which is also to be put into application to power network fault diagnosis. In the example given as fault diagnosis, the reduction of the tabulated decisions is implemented through the VB-based programming language, of which the results show the effectiveness and practicability of the method proposed here. References | Related Articles | Metrics

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Research on index structure of file system Li, Jing-Jiao (1); He, Jing-Yu (1); Zheng, Mu-Ye (1); Wang, Ai-Xia (1) 2004, 25 (4):  318-321.  DOI: - Abstract ( 181 )   HTML   PDF (555KB) ( 671 )   Based on analyzing the index structure of the file systems in common use, a dynamic storage/index structure of file system, is proposed, i.e. the Hierarchical Hashing Index Model (HIM). It uses dynamic hashing technique to construct a linear hashing table as together with a character mapping function designed to optimize the whole structure of HIM and improve the performance of file systems. HIM as an abstract model for the index structure of file system, can be applied to the design of any file systems. References | Related Articles | Metrics

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Clustering algorithm based on link stability in MANET Zhao, Chun-Xiao (1); Wang, Guang-Xing (1); Liu, Biao (2) 2004, 25 (4):  322-324.  DOI: - Abstract ( 212 )   HTML   PDF (130KB) ( 578 )   Describing briefly the characteristics of a mobile ad-hoc network or MANET and comparing them with related works, a new definition of time degree was given in view of the highly dynamic topology and absence of any fixed infrastructure in MANET. Analyzing the link relationship between two adjacent nodes, a network model based on the link life of the two nodes was set up. Some predicting techniques were investigated and used for the cost of each link so as to gain a more stable link. A distributed clustering algorithm is therefore proposed on the basis of a mobility prediction scheme. Simulation results showed that the algorithm proposed outperforms HD and LCC clustering algorithms. References | Related Articles | Metrics

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Petri net description of a new satellite network management protocol and its verification Zhao, Jian-Li (1); Wen, Ying-You (1); Shang, Rui-Qiang (1); Wang, Guang-Xing (1) 2004, 25 (4):  325-328.  DOI: - Abstract ( 209 )   HTML   PDF (160KB) ( 613 )   Introduces a new management protocol into satellite network, of which the design of service connection/primitives is explained. The way to describe a protocol with Petri net is applied to giving a formal description of the protocol model. Moreover, the analyses of the reachability, S_invariants and T_invariants of Petri nets are utilized to verify the logical correctness of the protocol, thus making sure its boundedness, liveliness, conservation, completeness arid advancement, reducing potential mistakes in protocol designing and laying well a foundation to implement the protocol. References | Related Articles | Metrics

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Fanout splitting multicast scheduling in high performance router Quan, Cheng-Bin (1); Ren, Xiu-Li (1); Fan, Li-Jun (1); Luan, Gui-Xing (2) 2004, 25 (4):  329-332.  DOI: - Abstract ( 203 )   HTML   PDF (160KB) ( 610 )   Analyzing the architecture and queuing management, which the multicast scheduling depend on, some practical fanout splitting algorithms are discussed. A new PGMF (packet greedy match fairness) algorithm is then proposed for multicast scheduling to support length-variable data packets. Thus, the redundant circuits to recombine signal elements and treat disorderly states can be prevented, with scheduling/transmitting throughput increased on fairness basis to support easily QoS management. Simulative analysis showed that more throughput and latency feature the new algorithm and, in view of the complexity of hardware designing, its implementation is of low complexity. Compared with other algorithms, the developmental trend of multicast scheduling algorithm is presented. References | Related Articles | Metrics

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Software architecture of the ubiquitous computing devices Wang, Ji-Yong (1); Zhao, Hai (1); Lin, Tao (1); Wang, Jin-Dong (1) 2004, 25 (4):  333-336.  DOI: - Abstract ( 251 )   HTML   PDF (180KB) ( 607 )   At the core of the problem of the ubiquitous computing devices is the fact that communication has a reciprocal purpose and means with computing. By virtue of the idea implementing embedded Internet, grid computing and Jini, a software architecture is therefore proposed to be configurable statically and dynamically, together with a software development platform which can configurate and prune the architecture components to run on the purpose-specific systems with their unique resource and function constrained. The architecture intends to solve the contradiction between the diversity of services to be provided by ubiquitous computing devices and the resource limitation of the computers embedded in them, thus implementing the communication and collaborative computing when there is a reciprocal purpose and means of communication with computing among the ubiquitous computing devices. References | Related Articles | Metrics

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Embedded internet model based on SIP protocol Lin, Tao (1); Zhao, Hai (1); Wang, Ji-Yong (1); Han, Guang-Jie (1) 2004, 25 (4):  337-340.  DOI: - Abstract ( 235 )   HTML   PDF (656KB) ( 627 )   SIP protocol is introduced into existing embedded Internet field to solve El problems, which belongs to VoIP technology. The interface between SIP and original model is thus implemented on existing architecture. A new embedded Internet location model based on SIP protocol, i. e. ESL model, is also presented to name application layers and meet the increasingly growing high-layer demands. In particular ESL model gains an advantage over others that it enables El systems to be intelligent with security in remote locating process and access of mobile devices. References | Related Articles | Metrics

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Optimal proxy-caching scheme for VOD systems Hu, Yu-Qi (1); Zang, Huai-Quan (2); Gao, Yuan (1) 2004, 25 (4):  341-344.  DOI: - Abstract ( 231 )   HTML   PDF (163KB) ( 528 )   An efficient proxy-caching scheme is presented to minimize network bandwidth utilization of proxy-based distributed VOD system. Furthermore, a global trial technique is developed to seek optimal proxy-caching allocation for various popular video shows. Combining the proxy-caching scheme with traditional show scheduling schemes the effects of the choice policy of cache allocation and proxy cache size on the total transmission cost are explored quantitatively. The caching scheme is thus proved to be effective and practical for server design to provide on-line video show allocations. References | Related Articles | Metrics

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Modeling of the coordinated production planning of a two-stage mineral industry supply chain Li, Jian-Xiang (1); Tang, Li-Xin (1); Wu, Hui-Jiang (2) 2004, 25 (4):  352-355.  DOI: - Abstract ( 243 )   HTML   PDF (1023KB) ( 594 )   The coordinated production planning of a two-stage mineral industry supply chain is studied, in which one open pit mine and one concentrating mill are involved. A linear programming model is then formulated, which covers two characteristics: (1) integrating the production planning of two stages, i.e. the mine and concentrating mill; (2) integrating transportation planning and production planning. The model's objective is to minimize the total cost of the supply chain, and it is very applicable but unlimited to the two-stage mineral industry supply chain or the integrated mining-concentrating enterprise with one mine and one mill. It can easily be extended to the supply chain with multiple mines and mills. An application example is given to illustrate the model. The solution shows that the model can offer decision support for the coordinated production of two stages, reduce the total cost of both production and transportation and has a potential of application. References | Related Articles | Metrics

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Implementation of rapid heating for metal materials Luo, Zong-An (1); Su, Hai-Long (1); Zhang, Dian-Hua (1); Wang, Guo-Dong (1) 2004, 25 (4):  356-359.  DOI: - Abstract ( 349 )   HTML   PDF (230KB) ( 1285 )   A heating process with self-resistance was introduced in the rapid heating system for metal materials during the test of thermo-mechanical simulation. A formula was given first to estimate heating rate. To eliminate the errors of temperature measurement which was affected by an electromagnetic field induced from the high current, a special attention was paid to temperature measurement that they were done through an intermittent power-off procedure at intervals of 10 ms and utilizing synchronous voltages to collect testing data in triggering form. A criterion was proposed in case a measured point deviates from the power-off zone, with a triggering time reset. The application of intelligent control to rapid heating system is briefly described. The experiment results indicated that the rapid heating system is accurate in temperature measurement, and available to high-precision control. References | Related Articles | Metrics

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Simulation on temperature field under ultra fast cooling Peng, Liang-Gui (1); Liu, Xiang-Hua (1); Wang, Guo-Dong (1) 2004, 25 (4):  360-362.  DOI: - Abstract ( 242 )   HTML   PDF (680KB) ( 726 )   Temperature field under ultra fast cooling (UFC) is simulated by finite-difference method. The results show that when a slab which was rolled from 180 mm to 40 mm by 6 passes at an initial temperature 1200°C enters into a UFC zone standing between the roughing mill and finishing mill at 3 m/s, a water cooling rate 70°/s can be obtained if the heat-exchange coefficient is up to 10 kW/(m2·°C). At the same time, the entrance finishing temperature must be corrected because of the strong temperature recovery after UFC. References | Related Articles | Metrics

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Solution to temperature field in plate rolling process by quadratic curve model Qiu, Hong-Lei (1); Hu, Xian-Lei (1); Yu, Feng-Chun (2); Wang, Guo-Dong (1) 2004, 25 (4):  363-366.  DOI: - Abstract ( 252 )   HTML   PDF (172KB) ( 620 )   It is difficult to simulate precisely the temperature field in plate rolling process and the precision of commonly used temperature models are not high. So, a quadratic curve temperature model is developed to computer the temperature field on plate. Based on it, the plate rolling process is simplified to a certain degree to approximate the quadratic curve to the real temperature field along the thickness of plate. Thus, a specific quadratic curve model is obtained with relevant computation method provided. The model has been applied to the temperature field in the rolling process of the Q235A steel slabs. The result indicates that the relative error is within 3%, if using the model to predict related temperatures, which can meat satisfactorily the requirements for on-line plate rolling. The model can also play a role as example in analyzing and controlling other temperature fields in hot rolling. References | Related Articles | Metrics

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Development of one new-style infrared heating equipment Bian, Jun (1); Liu, Xiang-Hua (1); Wang, Guo-Dong (1) 2004, 25 (4):  367-369.  DOI: - Abstract ( 221 )   HTML   PDF (162KB) ( 1545 )   The new-style low heat-inertia fast-heating furnace for metal sample is developed based on its special need. The system adopts infrared lamps as heating radiation source, and achieves fast-heating and fast-cooling of sample in panel shape and bar shape by laying the lamps vertically and horizontally. This system has been proved to be effective by experiment to heat the metal sample on high-temperature and high-speed and quick cool through using infrared. It enlarges the using field of infrared and provides one new means for heat treatment of metals and science development. References | Related Articles | Metrics

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Application of crown-flatness vector method in plate draft schedule Hu, Xian-Lei (1); Zhao, Zhong (1); Qiu, Hong-Lei (1); Liu, Xiang-Hua (1) 2004, 25 (4):  370-373.  DOI: - Abstract ( 213 )   HTML   PDF (262KB) ( 826 )   The crown-flatness vector method is applied to the computation of plates' drafting schedule to control effectively the plate crown/flatness and make full use of mill capacity. Analyzing a simple plate crown model and giving an on-line model relevant to it, the mechanism of crown-flatness vector method is discussed, as well as the related plate rolling technology in lengthening phase. Then, the computation for drafting schedule in the phase can break down as three steps below. Decrease the number of several primary rolling passes by way of taking heavy reduction as possible. Take advantage of crown-flatness Vector method to control the crown/flatness of workpiece for the subsequent 3 or 4 passes. Finally, adjust the total number of passes or the coefficient of ultimate rolling force so as to enable the plate gauge of the exit of last pass to be equal to target gauge. The online applications for long time showed that the method can strongly control the plate shape and is available for on-line control of the plate shape and is available for on-line control of plate rolling process by computer. References | Related Articles | Metrics

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Effect of spraying direction on heat exchange in spray cooling process Mei, Guo-Hui (1); Meng, Hong-Ji (1); Xie, Zhi (1) 2004, 25 (4):  374-377.  DOI: - Abstract ( 291 )   HTML   PDF (115KB) ( 862 )   A spray cooling model was set up taking the impact of spraying droplets as a disturbance due to film boiling in cooling pond, of which the effects of water flow density, droplet size and impact force were taken into account. It was also found that the difference between thickness of water film in different spraying directions is the main influencing factor of spraying direction on the heat-exchange coefficient of continuous-cast ingot surface. The thickness of water film was therefore introduced into the model to analyze the influence of spraying direction on heat-exchange coefficient. The results indicated that the heat-exchange coefficient is maximum if the spraying angle is 90° with ingot surface at low waterflow density and, as a while, the coefficient distribution is symmetrical to the perpendicular spraying direction if the angle is different from 90°. The coefficient will increase greatly with spraying angle if the waterflow density is high. The result, as a theoretical analysis, is much the same with the existing works done in other ways. References | Related Articles | Metrics

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Behavior of thermal decomposition of bastnaesite with rare earth nitrate added to it Wu, Wen-Yuan (1); Chen, Jie (1); Sun, Shu-Chen (1); Tu, Gan-Feng (1) 2004, 25 (4):  378-381.  DOI: - Abstract ( 238 )   HTML   PDF (256KB) ( 848 )   To seek the way to enable bastnaesite to be decomposed at lower temperature, process of thermal decomposition of bastnaesite to which 5% (mass fraction) of rare earth nitrate had been added was developed by TG-DTA, and the phase compositions of different calcined products were investigated by XRD at 430°C and 510°C separately. The results showed that bastnaesite is decomposed partly with no oxidant added to it at 430°C, while it can be decomposed completely with 5% (mass fraction) of the oxidant added to it. The products decomposed are mainly REOF and 2CeO2·CeF3 accompanied with a bit of 4CeO2·Ce2OK3. On the other hand, bastnaesite can be completely decomposed of 510°C on which no apparent effect can be found when adding the oxidant to it. References | Related Articles | Metrics

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Experimental study on cermet as inert anode for aluminium electrolysis Shi, Zhong-Ning (1); Xu, Jun-Li (1); Qiu, Zhu-Xian (1) 2004, 25 (4):  382-385.  DOI: - Abstract ( 276 )   HTML   PDF (911KB) ( 672 )   An experiment of a newly developed cermet used as inert anode for aluminium electrolysis was conducted in cryolite-based molten salt as electrolyte with cryolite mole ratio 2.8 and saturated alumina concentration for 7 h at 960°C, in which the direct current was set to 100 A with an anodic current density 1.0 A/cm2. The results showed that this cermet anode has high resistance to thermal shock, oxidation and corrosion of the molten salt. e. g., the annual corrosion rate is 24 mm, and the purity of aluminium is up to 98%. The back electromotive force is 2.2 V at 960°C as detected by aluminium reference electrode and the evolved anodic gas contains 98%-100% oxygen as analyzed by apparatus. References | Related Articles | Metrics

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Direct kinematic problem based on RBFNN of parallel manipulator Song, Wei-Gang (1); Zhang, Guo-Wei (1) 2004, 25 (4):  386-389.  DOI: - Abstract ( 262 )   HTML   PDF (197KB) ( 1028 )   The kinematic model of parallel manipulators presents an inherent complexity due to their closed-loop structure and kinematic constraints and, correspondingly, the algorithm for the solution to relevant direct kinematic problems is complex. An algorithm of RBFNN for kinematic problems is thus presented in a nearest neighbor-clustering way to solve simply the positions and orientations of Stewart platform with needed precision, of which the process of solution is simple with good result provided. Comparing with the Newton-Raphson algorithm, the errors of neural network are approximatively invariable without the effects of initial values and rated number of cycles on them. The results show that this approach can be used for the in-line control of parallel manipulators. References | Related Articles | Metrics

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Fractal model of rifle-worn surface of bullets Wang, Bing-Cheng (1); Hou, Rong-Tao (2); Ren, Li-Yi (1); Wen, Bang-Chun (1) 2004, 25 (4):  390-393.  DOI: - Abstract ( 197 )   HTML   PDF (1008KB) ( 682 )   The basic relationship between fractal dimension D and the amount of shot bullets was found by collecting the data from actual measurements and analyzing the topography of bullet surfaces worn out by rifle of a gun. A dynamic equation of fractal dimension D was therefore proposed and, based on it, a fractal model for dynamic prediction of surface wear-out condition was given to establish the direct relationship between wear rate and amount of bullets shot. The fractal dimension or wear rate may be used as a characteristic parameter to examine the topography of worn-out by rifle. The dynamic prediction shows its conformity to experiment data and its available to judge the extent of wear-out of a gun through an analysis of the properties of its rifle worn out in turn by the surface of bullet. Therefore, the model is helpful to provide theoretically not only a basis to judge gun failures but a reference to infer the maintenance and applications of a gun for investigating the cases involving guns. References | Related Articles | Metrics

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Negative damping ratio due to tainter gate vibration Liu, Yong-Lin (1); Liu, Bin (1); Ni, Han-Gen (2); Liu, Ya-Kun (2) 2004, 25 (4):  394-397.  DOI: - Abstract ( 168 )   HTML   PDF (1383KB) ( 595 )   A hydraulic expression of negative damping ratio of a tainter gate when a tangential vibration resulting from changing waterflow taking place on such a rigid body is introduced to define the negative damping ratio corresponding to the parametric resonance condition caused by the longitudinal constant force of compressional members and alternating force. Various types of vibration of the tainter gate are simplified into two kinds of compressional members, i.e., two simply supported ends and one simply supported end with one elastically supported end, and the relevant formula of Euler critical load of 1st kind is given. A formula of longitudinal force at member end is thus given approximately through kinetic equation. The reference values of pulsating pressure acting on supporting hinges are also given according to experiments, which will lay a foundation for discussing further the typical case of dynamic instability. References | Related Articles | Metrics

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Research based on BP network for concrete carbonation Cheng, Yun-Hong (1); Liu, Bin (1) 2004, 25 (4):  398-401.  DOI: - Abstract ( 210 )   HTML   PDF (229KB) ( 783 )   The computation and forecast models (3-5-1), which include 3 neurons in input layer, 5 neurons in hidden layer and 1 neuron in output layer, are set up for concrete carbonation depth, based on optimized BP algorithm. In the computation model the water cement ratio, unit cement consumption and sand percentage are taken as inputs with concrete carbonation depth as output. But, in the forecast model the water cement ratio, unit cement consumption and tine for concrete exposure are taken as inputs with the carbonation depths of those concrete constructions/members which have been exposed to the weather for 20 years and 30 years as outputs. The computation results conform with the test results very well, and the forecast results are favorable. References | Related Articles | Metrics

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Isopiestic studies on ternary light rare earth nitrate aqueous solutions Wang, Jun (1); Li, Jun-Li (1); Wang, Zhi-Chang (1) 2004, 25 (4):  406-408.  DOI: - Abstract ( 208 )   HTML   PDF (133KB) ( 472 )   Isopiestic measurements were made for the ternary systems H2O+La(NO3)3+Pr(NO3)3, H2O+La(NO3)3+Nd(NQ3)3 and H2O+Pr(NO3)3+Nd(NO3)3 and their binary sub-systems H2O+La(NO3)3, H2O+Pr(NO3)3 and H2O+Nd(NQ3)3 at T=298.15 K, taking NaCl(aq) and CaCl2(aq) as reference systems. The experimental results showed that their thermodynamic characteristics conform well with the partial ideal solution model and Zdanovskii's rule within the experimental error range, i.e. |Δ|&le0.0010. References | Related Articles | Metrics