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15 December 2004, Volume 25 Issue 12 Previous Issue    Next Issue
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Fuzzy robust control of a class of uncertain time-delay systems and its stability analysis Wei, Xin-Jiang (1); Jing, Yuan-Wei (1) 2004, 25 (12):  1123-1126.  DOI: - Abstract ( 213 )   HTML   PDF (253KB) ( 595 )   The fuzzy T-S model is used to approximate to time-delay systems with uncertainty. Then, based on Lyapunov stability theory, the robust stabilization of such fuzzy systems that are either observable or unobservable, are discussed. The state feedback controller thus designed is proved to be able to stabilize the systems theoretically and further such stability problems can be transferred into a class of linear matrix inequalities to solve. A simulation exemplifies the effectiveness of the proposed method. References | Related Articles | Metrics

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Dynamic output-feedback robust H∞ control of neutral differential systems with parameter uncertainties Yang, Fan (1); Zhang, Qing-Ling (1); Yang, Jun (2) 2004, 25 (12):  1127-1130.  DOI: - Abstract ( 209 )   HTML   PDF (158KB) ( 654 )   Discusses the design of a dynamic output-feedback robust H∞ controller of a class of neutral differential systems with parameter uncertainties which are assumed real time-varying and norm bounded with constant delay. The problem is to design a dynamic output-feedback control laws so that the closed-loop system is asymptotically stable and the transfer function from exogenous disturbance to output will satisfy a prescribed H∞ performance index for all admissible uncertainties and time delays. Sufficient conditions for the existence of such controllers are derived by way of combining the matrix inequality approach with Lyapunov method. Furthermore, it is shown that the dynamic output-feedback controller can be constructed in terms of the feasible solutions to certain linear-matrix inequalities. The dynamic output-feedback controller derived depends on neither parameter uncertainties nor time delays. References | Related Articles | Metrics

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Quadratic stability study for a class of T-S fuzzy descriptor systems Liu, Guo-Yi (1); Zhang, Qing-Ling (1); Yang, Li (1); Zhai, Ding (1) 2004, 25 (12):  1131-1133.  DOI: - Abstract ( 198 )   HTML   PDF (218KB) ( 828 )   Based on the fuzzy descriptor extreme subsystems, the problems of quadratic stability analysis and nonlinear fuzzy state feedback controller design for a class of continuous-time T-S fuzzy descriptor systems are studied with the fuzzy systems by which the problems of quadratic stability analysis and nonlinear fuzzy controller design for a class of continuous-time T-S fuzzy descriptor systems can be converted into those of quadratic stability and nonlinear fuzzy controller design for its fuzzy descriptor extreme subsystems. A sufficient and necessary condition is given. Then two new stability conditions are proved, through which the accurate upper bound in the sufficient and necessary condition are weakened and become approximate ones so as to relax somewhat the restriction due to the sufficient and necessary condition. References | Related Articles | Metrics

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Performance of fault estimation of a class of adaptive observers Wang, Zhan-Shan (1); Zhang, Hua-Guang (1) 2004, 25 (12):  1134-1137.  DOI: - Abstract ( 232 )   HTML   PDF (310KB) ( 766 )   Based on the H∞ tracking performance, a synthesis procedure is given to the design of a class of adaptive observers. Designing the fault adaptive laws through comparison, several factors influencing the performance of fault estimation of the class of adaptive observers are obtained. The fault estimation error of an adaptive observer thus designed is irrelevant to the fault amplitude and it can be tuned to be as small as possible by adjusting H∞ tracking performance index. A simulation exemplifies the effectiveness of the analysis results. References | Related Articles | Metrics

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Multi-mobile robot's oppositional strategy system based on discrete variable action space Xue, Fang-Zheng (1); Fang, Shuai (1); Xu, Xin-He (1) 2004, 25 (12):  1138-1141.  DOI: - Abstract ( 254 )   HTML   PDF (161KB) ( 448 )   A discrete variable action space is proposed to enhance the intelligence of the robot soccer strategy system at the acceptable expense of its precision in decision-making, thus simplifying the decision-making process of multi-mobile robot's oppositional strategy. The discrete variable action space enables the complex decision-making problem to fall into several simple and independent sub problems, and each of them can be resolved via existing theories. A centralized robot soccer strategy system based on such ideas and methods has been constructed and won the third place in RobotSoccer World Cup 2002. References | Related Articles | Metrics

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Control of flying shears by exit of tandem cold mill Ge, Yan-Jin (1); Zhang, Gui-Qiang (1); Chen, Yan (1) 2004, 25 (12):  1142-1144.  DOI: - Abstract ( 275 )   HTML   PDF (134KB) ( 536 )   The control process and relevant algorithm for cutting strips by flying shears are discussed and developed under conditions that the cut point of strip is positioned near the exit of the last stand of tandem cold mill (TCM). The shear knives' position of the flying shears is controlled by the instructions sent from a cam switch which is coaxial with the motor rotor of the flying shears. The strip sections cut off by such a control procedure and relevant algorithm are proved, and the strips' tensile between this control procedure and conventional rolling process is also given. References | Related Articles | Metrics

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Modeling of integrated production scheduling for seamless steel tube Li, Jian-Xiang (1); Tang, Li-Xin (1); Wu, Hui-Jiang (2) 2004, 25 (12):  1145-1148.  DOI: - Abstract ( 210 )   HTML   PDF (265KB) ( 608 )   Based on an analysis made to the production process of seamless steel tube in Tianjin Pipe Corporation, the integrated production scheduling covering three stages is modeled. A mathematical programming model of tube processing scheduling and that of hot rolling scheduling are both set up, then they are combined with each other to form an integrated model for production scheduling. The integrated model is further combined with existing models integrating steel-making continuous casting and hot rolling processes into one, thus sets up a model of 3-stage integrated production scheduling to adapt to the whole production process of seamless steel tubes. This study is just the first step to develop a scheduling decision support system for the company, and the next one is to design an efficient algorithm for the model. References | Related Articles | Metrics

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Efficient approach to image binarization Dong, Li-Ju (1); Yu, Ge (1) 2004, 25 (12):  1149-1152.  DOI: - Abstract ( 662 )   HTML   PDF (205KB) ( 2022 )   Unlike the usual way to find out automatically a threshold from image histogram, the image binarization is dealt with as an optimization problem where the best threshold could be found out by minimizing a weighted function of error sum of squares, with a fast iterative optimization algorithm given for the purpose. The new approach is compared with a most classic and commonly-used binarization method, and the result shows that the two methods are equivalent in view of either theoretical analysis or experimental data. However, our formulation relevant to the problem enables us to derive up a much more efficient algorithm available to more applications, especially to real-time video monitoring and tracking systems. References | Related Articles | Metrics

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Heuristic virtual topology design method of IP/DWDM optical internet Wang, Xing-Wei (1); Chen, Ming-Hua (1); Wang, Qiang (1); Huang, Min (2) 2004, 25 (12):  1153-1156.  DOI: - Abstract ( 257 )   HTML   PDF (163KB) ( 497 )   A method is proposed to design the virtual topology of IP/DWDM optical Internet so as to minimize the sum of traffic-weighted hop count. Oriented toward the mesh network and based on the given physical topology, the corresponding virtual topology is designed according to specific traffic matrix. Then, the traffic is thus routed on it. Due to its NP-hard nature, the design is decomposed into three subproblems, i.e., the virtual topology construction, wavelength assignment and traffic routing, and each of them is to solve separately with heuristic algorithm. The feasibility and effectiveness of the proposed method have been verified the way that an environment is developed to conduct the relevant in which several actual network topologies are taken as physical ones. References | Related Articles | Metrics

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Improved FGS video coding with additional variable size block motion estimation Wang, Ze (1); Lin, Na (1); Wang, Guang-Xing (1) 2004, 25 (12):  1157-1160.  DOI: - Abstract ( 231 )   HTML   PDF (167KB) ( 454 )   The efficiency of Fine Granularity Scalability (FGS) video coding can be improved obviously when motion estimation was added in enhancement layer. A FGS video coding framework with additional Variable Size Block Motion Estimation (VSBM) in base layer was specified. Macro-block based reference selection method and scale truncation technique of FGS bit-stream were both adopted to optimize the video coding efficiency. The results of experiments show that our framework is superior to the baseline FGS on the full range of variable bit-rates. References | Related Articles | Metrics

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Effect of Z value in sialon phase on microstructure and properties of synthesized sialon-corundum refractory materials Gong, Gan-Lei (1); Ru, Hong-Qiang (1); Sun, Xu-Dong (1); Xue, Xiang-Xin (1) 2004, 25 (12):  1161-1164.  DOI: - Abstract ( 205 )   HTML   PDF (178KB) ( 514 )   Sialon-corundum refractory materials were synthesized directly using silicon powder, aluminum powder and black corundum to investigate the control of Z value in sialon phase and its effect on the microstructure, flexural strength and resistances to thermal shock, oxidation and chemical corrosion. The results showed that, with the increase of Z value in sialon phase, the abilities of anti-oxidation and anti-corrosion of synthesized materials increase and the columnar crystal size of Sialon grows up, while the flexural strength and the resistance to thermal shock decrease. On condition that Z=3, it is possible to obtain such a material that the resistances to both oxidation and corrosion are high in combination with moderate flexural strength and stable thermal shock. References | Related Articles | Metrics

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Impact of mineralizers on titanium carbonitride grains during reductive carbo-nitridation for PANSTEEL BF slag Xue, Xiang-Xin (1); Dong, Zhi-Yuan (1); Yang, He (1); Duan, Pei-Ning (1) 2004, 25 (12):  1165-1168.  DOI: - Abstract ( 232 )   HTML   PDF (780KB) ( 607 )   The titanium compounds in PANSTEEL BF slag were enriched in titanium carbonitride via reductive carbo-nitridation process so as to enable the grain size of titanium carbonitride to grow up properly, thus facilitating the slag benefication and finally the extraction of TiC, TiN and TiO2. After the reductive process, the phase composition and microstructure of slag were characterized by XRD and SEM. The results showed that the titanium components are fully enriched in titanium carbonitride phase, and that adding such mineralizers as CaO, K2CO3 and Na2SO4, in slag which could in the reductive process can modify the liquid slag properties and accelerate effectively the titanium carbonitride grain growth, among which the maximum grain size up to about 30 μm is found in the samples which K2CO3 was added in. Meanwhile, the minimum grain size is found in the samples which no mineralizer was added in and shows no trend of grain aggregation growth. References | Related Articles | Metrics

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Crystallization behavior and property of CaO-MgO-Al2O3-SiO2 glass ceramics Shi, Pei-Yang (1); Jiang, Mao-Fa (1); Liu, Cheng-Jun (1); Wang, De-Yong (1) 2004, 25 (12):  1169-1172.  DOI: - Abstract ( 266 )   HTML   PDF (270KB) ( 2153 )   The most important influencing factors on the property of a glass ceramics are its primary crystal class and grain size. Therefore, by means of XRD, SEM, etc, the action of MgO on CaO-MgO-Al2O3-SiO2 glass ceramics and the effect of content of MgO on their density and hardness were investigated. The results show that the crystallization temperature rises with the increase of MgO content, which is not favorable to the crystallization of glass ceramics but favorable to sintering. On the other hand, the morphology of the samples used transforms from radiative or fiber-like agglomeration to grain-like one so as to increase the density and hardness and improve the properties of the glass ceramics. References | Related Articles | Metrics

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Compositional analysis of neutralized water through bio-oxidation for refractory gold ores Yang, Hong-Ying (1); Gong, En-Pu (2); Chen, Gang (1); Zi, Jian-Wei (2) 2004, 25 (12):  1173-1175.  DOI: - Abstract ( 215 )   HTML   PDF (712KB) ( 495 )   Chemical analysis and X-ray powder crystal analysis were made to neutralized water and crystallization contained in it. It was found that there are a large amount of substances containing magnesium, potassium, sodium and calcium in neutralized water, of which the crystallization is mainly in form of sulphates including MgSO4·3H2O, MgSO4·4H2O, MgSO4·1.25H2O and CaSO4·2H2O. Such a large amount of magnesium sulphates or calcium sulphate come from two processes. One is the bio-oxidation in which the mineral composition of the gold ore used is complicate with many carbonates/silicates bearing magnesium/calcium and part of them dissolve into the solution cumulatively. The other is the neutralization using limestone, after which the residual calcium deposits in the solution. Neutralized water always cause the water pipeline to jam up when it is used cyclically in bio-oxidation process because of the high-concentration magnesium/calcium and, at the same time, the high-concentration magnesium will suppress the growth of bioleaching bacteria then result in adverse effect on bio-oxidation process. References | Related Articles | Metrics

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Preparation of strontium by vacuum aluminothermy reduction Zhang, Ming-Jie (1); Li, Ji-Dong (1); Guo, Qing-Fu (1) 2004, 25 (12):  1176-1178.  DOI: - Abstract ( 240 )   HTML   PDF (103KB) ( 1617 )   On the basis of thermal decomposition of SiCO3 influences of various technological parameters on reduction rate in the process of reduction were investigated. It was found that with the increase of reduction temperature, reduction rate increases up to 82% at 1200°C, and reduction rate increases fast at the beginning (the first 1-3 h) with prolonging reduction time then it increases gently in the successive 1-2 h. With the same activity, the finer the grain size of reducing agent, the higher the reduction rate. Although the reduction rate increases with amount of reducing agent, but there is a peak value of reduction rate and, exceeding it the rate will not increases, but decrease with the increase of the amount of reducing agent. In general reduction rate can be up to 75% even to 82% as maximum. Such a result can meet the requirement of actual production. References | Related Articles | Metrics

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Cu-P weather resistance steel: Influence of rare earths on nonmetallic inclusions and anticorrosivity Yue, Li-Jie (1); Wang, Long-Mei (2); Xu, Cheng-Hai (1); Piao, Xiu-Yu (3) 2004, 25 (12):  1179-1182.  DOI: - Abstract ( 279 )   HTML   PDF (254KB) ( 667 )   Two groups of the RE weathering resistant steel slabs were observed and analyzed for testing with metalloscope and SEM/EMPA. Solid-soluble content of rare earths in steel was analyzed by nonaqueous electroanalysis and ICP. The weathering resistance of the steel and steel Q235 as reference specimen were studied by dry-wet immersion test, with their corrosion rates obtained. The polarization curves of the RE steel and Q235 were measured by electrochemical methods. A conclusion was drawn that when the content of oxygen/sulfur of the steel specimens is about 0.002%/0.004% the optimum content of RE is 0.0065%-0.016%, thus causing the bar-like sulphides to nearly deteriorate and improving gradually the anticorrosity of the steel with the increase of RE content. When the content of oxygen/sulfur is about 0.002%-0.007%/0.004%, the optimum content of RE is 0.005%-0.025%, with near-deterioration of bar-like sulphides observed. References | Related Articles | Metrics

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Study on common cause failure data analysis Li, Cui-Ling (1); Xie, Li-Yang (1) 2004, 25 (12):  1183-1186.  DOI: - Abstract ( 599 )   HTML   PDF (883KB) ( 1167 )   Because of rarity of common cause failure events on a plant-and system-specific basis, some models are difficult to be applied. To solve the difficulty which is general in the common cause failure analysis, a mapping method based on neural network is presented, which is used for common cause failures data analysis. It can translate generic experience event data for plant-specific applications and map the failure data between the systems with different sizes, so it makes up the rarity of common cause failures data and reduce the uncertainties. It can provide reliable data for reliability analysis. At last this article provides an example to illustrate the application. References | Related Articles | Metrics

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Determination of optimum rock excavating height of orebody footwall during sublevel caving Li, Yuan-Hui (1); Sun, Huo-Ran (1); Liu, Wei (1); Liu, Xing-Guo (1) 2004, 25 (12):  1187-1190.  DOI: - Abstract ( 225 )   HTML   PDF (175KB) ( 486 )   Discusses the ore loss process during sublevel caving without pillars. In many cases, due to the limitation of the sloping or gently sloping orebody footwall, lots of ores will generally be left behind when drawing ores from each and every ring is stopped at shut-off point. To recover the residue, an efficient way is to excavate some waste rock of footwall. With the increase of the excavating height of footwall, the quantity of ores drawn in unit height decreases. The optimum rock excavating height of footwall is governed by the ore recovery and economy. The relationship between the ore residue from the footwall and the slope of footwall is studied by numerical simulation. In practice, the optimum excavating height of footwall changes in accordance with the mineral market price and mining cost. The study shows that the numerical simulation is more feasible than physical model experiment in simulating the drawing process, especially in drawing control. References | Related Articles | Metrics

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Experimental investigation on performance of styrene-butadiene-styrene (SBS) modified asphalt Wang, Xiaochu (1); Zhu, Fu-Sheng (1); Wang, Yi-Peng (2) 2004, 25 (12):  1191-1194.  DOI: - Abstract ( 198 )   HTML   PDF (186KB) ( 782 )   Through the testings for different proportioned SBS-modified asphalt, its pavement performance was investigated experimentally including elastic resilience, high-temperature stability and low-temperature property. How the influencing factors, such as dosage of the modifier used exert on the performance was thus analyzed. The optimal dosage of the modifier should be 4% or more. The technical specifications of SBS-modified asphalt available to road construction in Liaoning province is proposed as a reference for engineering applications. References | Related Articles | Metrics

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Wastewater treatment by composite chitosan as biosorbent for repulped papermaking plants Yao, Shu-Hua (1); Shi, Zhong-Liang (2); Song, Shou-Zhi (1) 2004, 25 (12):  1195-1198.  DOI: - Abstract ( 247 )   HTML   PDF (185KB) ( 921 )   The wastewater treatment for repulped papermaking plants using chitosan and its composite chitosan as biosorbents is studied. The effects of pH value, chitosan dosage, stirring speed and resting time on COD removal rate are investigated to obtain the optimal experimental conditions, i.e., pH value range of wastewater: 6.5-6.7, stirring speed: 120 rpm, resting time: 12 hr and chitosan dosage: 0.4 g/L. Under the conditions the COD removal rate of wastewater can be over 66%. The results show that the chitosan is obviously superior to the non-organic flocculant Al2(SO4)3 in biosorption process. Moreover, the chitosan can be used further by combining it with Al2(SO4)3 in a certain proportion to form a new composite purificant or biosorbent to wastewater treatment for repulped papermaking plants, by which the COD removal rate can be up to 83% even more. It will not only improve the COD removal rate but avoid secondary pollution, with better environment protection effect available. References | Related Articles | Metrics

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- - 2004, 25 (12):  1199-1202.  DOI: - Abstract ( 236 )   HTML   PDF (188KB) ( 580 )   - References | Related Articles | Metrics

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- - 2004, 25 (12):  1203-1206.  DOI: - Abstract ( 231 )   HTML   PDF (158KB) ( 552 )   - References | Related Articles | Metrics