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15 January 2003, Volume 24 Issue 1 Previous Issue    Next Issue
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Generalized fuzzy hyperbolic model: A universal approximator Quan, Yong-Bing (1); Zhang, Hua-Guang (1) 2003, 24 (1):  1-3.  DOI: - Abstract ( 345 )   HTML   PDF (128KB) ( 784 )   A generalized fuzzy-hyperbolic model (GFHM) was proposed. The model is a generalization of fuzzy hyperbolic model. The process of fuzziness, fuzzy inference and defuzziness can be expressed in the sum of hyperbolic functions of generalization state variables. Stone-Weierstrass theorem was used to prove that GFHM can approximate any real continuous functions on a compact sets. GFHM is a universal approximates, and can be used to establish the model for complex system. References | Related Articles | Metrics

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Nonlinear backstepping design for TCSC Jing, Yuan-Wei (1); Li, Wen-Lei (1); Liu, Xiao-Ping (1); Kang, Ai-Min (2) 2003, 24 (1):  4-6.  DOI: - Abstract ( 318 )   HTML   PDF (161KB) ( 691 )   Based on a nonlinear second-order model for a single-machine infinite-bus system with TCSC, two kinds of nonlinear controller were designed using backstepping methods. With backstepping, the origin nonlinear system doesn't need to be linearized and the closed-loop error system is guaranteed to be asymptotically stable. When damping coefficients is measured inaccurately, a dynamic feedback controller can be designed using adaptive backstepping containing the real-time estimation of uncertainty parameter. The design procedure reveals that the controller designed by backstepping possesses good performances. References | Related Articles | Metrics

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Branch-and-Price algorithm for CLSP Gao, Zhen (1); Tang, Li-Xin (1) 2003, 24 (1):  11-14.  DOI: - Abstract ( 513 )   HTML   PDF (203KB) ( 1220 )   A Branch-and-Price approach was presented to solve the classical capacitated single-level multi-item dynamic lot-sizing problems, also called as CLSP. Its objective is to minimize the sum of set-up and inventory-holding costs over the horizon under consideration, such as demands, capacity restrictions, etc. CLSP is frequently encountered in the most industry settings and well known as NP-Hard problem. The Branch-and-Price approach, a generalization of branch-and-bound with LP relaxation, allows column generation to be applied throughout explored nodes in the branch-and-bound tree. An implementation of the branch-and-price approach was described in detail. Two groups of examples were computed to verify the correctness and advantages of the suggested approach. References | Related Articles | Metrics

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Model of network management for satellite information network Jiang, Yue-Qiu (1); Feng, Yong-Xin (1); Liu, Zhi-Guo (1); Wang, Guang-Xing (1) 2003, 24 (1):  15-18.  DOI: - Abstract ( 261 )   HTML   PDF (255KB) ( 976 )   On the basis of the characteristics of space network, a hierarchical-hybrid network-management model was proposed. This model includes the organization model, the information model, the function model and so on. Resource management, task scheduler management and space network rebuild were proposed in space network management. The model was provided with flexibility and expansibility and was evaluated on the cost. The network model would change the mode of space network management from chimney into integrated and intelligent management. It also helps to increase the running independence and efficiency of space network. References | Related Articles | Metrics

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Modified simplex algorithm of Dn-optimal exact designs and its application in welding work Chen, Liang-Sheng (1); Li, Zhi-Yong (1); Zhu, Wei-Yong (1) 2003, 24 (1):  19-22.  DOI: - Abstract ( 220 )   HTML   PDF (151KB) ( 607 )   An algorithm for generating Dn-optimal exact design was put forward by using the modified simplex iteration. On the basis of Evans's simplex algorithm, the negative measure and Fibonacci sequence were introduced to generate the new design point. With the multi-circulation method and symmetric theory, a modified simplex algorithm of Dn-optimal exact design was given. Through this algorithm, the multi-component mixture regression models with logarithmic term was studied, and its Dn-optimal exact designs was given. An example of the application in a welding work was given, and it gives an evident proof for the Dn-optimal exact design. References | Related Articles | Metrics

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Study on model and algorithm in computer expert system of continuous casting equipment's synthesis state judgment Lui, Hui-Lin (1); Hao, Pei-Feng (1); Wang, Guang-Xing (1); Zhang, Li (2) 2003, 24 (1):  27-30.  DOI: - Abstract ( 209 )   HTML   PDF (183KB) ( 605 )   A basic mathernatic model of working state for the driving roll system of continuous casting equipment was studied on the collected data. A BP neural network was applied to build the working state model, and the analyzed data was used to train this BP neural network. The even strength value's curve of driving rolls in same time was simulated with the BP model. This BP model was used as casting equipment's conk outs diagnosing model in the expert system for continuous casting driving roll system's computer diagnosis. With the model and algorithm of conk outs judgment, some failure of on-line roll's engine was diagnosed exactly. The bad effects of driving motor troubles on the steel band were avoided. References | Related Articles | Metrics

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Review on optimal algorithms of location-routing problem (LRP) in integrated logistics Zhang, Qian (1); Gao, Li-Qun (1); Hu, Xiang-Pei (2) 2003, 24 (1):  31-34.  DOI: - Abstract ( 316 )   HTML   PDF (183KB) ( 1255 )   The development of Location-Routing Problem (LRP) was summarized and the advance of optimal algorithm of LRP was reviewed. Two common optimal algorithms to solve LRP, exact algorithm and heuristics algorithm, were analyzed. The optimal algorithm for three problems of LRP including location-allocation problems (LA), vehicle routing problem (VRP), and location-routing problem (LRP) were compared and contracted. Some possible paths for further research in this field were presented. The accurate and efficient search method for solving LRP should take the advantages of different techniques. The improved genetic algorithm (GA) provides a way to solve LRP, which is a NP-hard problem. References | Related Articles | Metrics

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Rational structure of multi-layer artificial neural network Hou, Xiang-Lin (1); Hu, Ying (2); Li, Yong-Qiang (1); Xu, Xin-He (2) 2003, 24 (1):  35-38.  DOI: - Abstract ( 308 )   HTML   PDF (164KB) ( 1660 )   Selecting rational hidden structure is very important question on multi-layer neural network in application. Applying optimum algorithm of neural network and algebra equation theory, nonlinear equations, expressing the relationships between computing output and ideal output of neural network were developed. The immanent connection of weights and threshold variables, standard sample numbers and node numbers of output layer are suggested. Hidden structure basis equation is given. A kind of analyzing method of rational construct of multi-layer neural network is proposed. Direct and indirect computing method were studied to compute quantitatively the numbers of hidden layers and the unit numbers per hidden layer. The analysis validity was showed through comparison of rational structure with various passible structures of neural network examples. References | Related Articles | Metrics

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Reliable linear quadratic state feedback control for descriptor systems Yao, Bo (1); Zhang, Qing-Ling (1) 2003, 24 (1):  39-41.  DOI: - Abstract ( 233 )   HTML   PDF (129KB) ( 559 )   Failures of the control components (actuators and sensors) in practice usually results in the unstability of a control system or can not attain the desired performance. Therefore, it is very important to investigate how to achieve the control goal using scanty effective control components. Whether some of the control components in the measurement set are invalid or not the reliable problem is about designing a controller to guarantee the stability and all the desired control performance. A design method of reliable linear quadratic state feedback controller for linear descriptor systems with actuator failure is presented. The designed state feedback controller guarantees systems regular, asymptotically stable and impulse-free against the actuator failure. References | Related Articles | Metrics

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Robust H2 control for uncertain discrete-time descriptor systems Yang, Dong-Mei (1); Zhang, Qing-Ling (1); Chen, Shu-Zhen (2) 2003, 24 (1):  42-45.  DOI: - Abstract ( 170 )   HTML   PDF (158KB) ( 499 )   The robust H2 optimal control problems for uncertain discrete-time descriptor systems were studied. A sufficient condition was presented for the systems to satisfy the robust H2 performance for all admissible uncertainties. The condition can be used to design state feedback controllers, and the resulting closed-loop system is admissible and satisfies the robust H2 performance. A sufficient condition of matrices inequalities was obtained and a stale feedback controller was designed. A numerical example was given to illustrate the results. References | Related Articles | Metrics

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Moving force of rear axle under rough road Wang, Tie (1); Zhang, Guo-Zhong (1); Zhou, Shu-Wen (1) 2003, 24 (1):  50-53.  DOI: - Abstract ( 261 )   HTML   PDF (175KB) ( 787 )   With considering elastic and damping modulus of suspendens and wheels, a vehicular model of system's vibration and a differential equation group of vibration with influence of rough road were built. This differential equation group is a ordinary differential equations and initial conditions can be found or assume. With Laplace change and theory of lineal system, a method of calculable systematical self-frequencies was given, and the analytic result of differential equation was obtained. With the relation between the special solution and common solution of a differential equation, a number result was got. The analytic result lays stress on controlling study and number result lays stress on calculation result. The number result can be used in program and simulink, especially Newton-Raphson method was recommended. These results amend the express styles of rear axle in moving force. A preparedness for finite element in design and simulation was done. References | Related Articles | Metrics

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Al element distribution and the properties of transparent conducting ZAO nanometer film Lu, Feng (1); Xu, Cheng-Hai (1); Sun, Chao (2); Wen, Li-Shi (2) 2003, 24 (1):  54-57.  DOI: - Abstract ( 279 )   HTML   PDF (813KB) ( 636 )   The distribution of Al element in the ZAO nanometer film made by DC(direct current) magnetron reactive sputtering was investigated by means of EDS and XRD. The relationship of Al content on electronic and optical properties of the ZAO film were systematically examined. The results indicate that Al distribution in the ZAO film is uniform. The ZAO film have the structure of ZnO crystal and no aluminum oxides was found. The doping Al replacement of Zn in the ZnO phase is the key factor in improving the conductivity of the ZAO film but no effect on the light transparence. The resistivity of the ZAO film is as low as 4.5 × 10-4 Ω. cm and the transmissivity in visible region is around 80%. References | Related Articles | Metrics

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Preparation and chemical corrosion of behaviour cermet inert anode used in the aluminum smelter Zhao, Qun (1); Gao, Bing-Liang (1); Wang, Zhao-Wen (1); Qiu, Zhu-Xian (1) 2003, 24 (1):  58-60.  DOI: - Abstract ( 249 )   HTML   PDF (153KB) ( 944 )   To understand the complicate corrosion mechanism of NiFe2O4 based cermets inert anode in aluminum electrolysis, the chemical corrosion of the cermets was studied. The preparation process of anode was researched in the experiment and the results illustrated that sintering temperature has significant effect on the property of anode. The oxidation erode is stable by measuring the oxidize-weight rising curve, but there exist fluctuate on the curves which means new chemical reaction occurred and results in fast oxidization. While the results of high temperature molten erosion by emerged sample into molten salt for a long period showed that the erosion-resistance capability of sample varied with the composition of electrolyte. The electrolyte including MgF2 has high corrosion effects, which changed with the content of NaCl. References | Related Articles | Metrics

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Synthesis of complex conducting oxides SrFeCo0.5Ox by citrates sol-gel method Huo, Di (1); Zhang, Jin-Song (2); Yang, Hong-Cai (1); Cao, Xiao-Ming (2) 2003, 24 (1):  61-63.  DOI: - Abstract ( 296 )   HTML   PDF (200KB) ( 1849 )   Conducting oxides SrFeCo0.5Ox powder was prepared by nitrate sol-gel method. Thermal reaction of the gel during heating is investigated by DTA and the crystal structure and morphology of the calcined powder were characterized by x-ray diffraction (XRD) and transmission electron microscope (TEM) respectively. The results show that single perovskite oxide can be formed at 550°C with x=0.64. The oxide size particle is in nanometer grade and very uniform. As the calcined temperature increases up to 850°C, the phase of the sample still does not change but the particles size becomes 100 nm. The polymerization reaction of nitrates sol-gel is also discussed. References | Related Articles | Metrics

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Sintered Nd-Fe-B magnet produced by the strip casting technology Pei, Wen-Li (1); Liang, Fa-Zeng (1); Zhou, Gui-Qin (1); Fu, Men (1) 2003, 24 (1):  64-67.  DOI: - Abstract ( 236 )   HTML   PDF (5066KB) ( 755 )   High performance Nd-Fe-B magnet produced by the strip casting (SC) was investigated. Compared with traditional ingot casting technology, the SC processing refines and homogenizes the columnar structures and suppresses the formation of α-Fe dendrites so that it greatly improves the microstructure in the as-casted alloy. It was found that the Nd-rich phase distributes uniformly along the grain boundaries of fine columnar matrix phase in the speed cooled strip. The columnar grains are about 5-25 μm in mean width. Using the cast strips for powder production, the fine powder with a good particle size distribution can be obtained easily. Due to the optimum distribution of Nd-rich phase, the magnets made from the cast strip shows high density even at a lower sintering temperature. The magnets made by SC technology showed a higher Br,Hci and (BH)max than that made by traditional ingot technology. References | Related Articles | Metrics

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Study on system of NH4NO3 and eutectic mixture of acetamide + urea Tian, Peng (1); Yang, Jia-Zhen (2); Song, Xi-Ming (2); Liang, Zhi-De (1) 2003, 24 (1):  68-70.  DOI: - Abstract ( 209 )   HTML   PDF (204KB) ( 852 )   In a vacuum atmosphere glove-box system filled with dry nitrogen, over all compositions containing NH4NO3 mole fraction in NH4NO3 and the eutectic mixture of binary system acetamide + urea were accurately prepared by weighting. The phase diagram of NH4NO3 and the eutectic mixture of binary system acetamide + urea was constructed by different scanning calorimetry method. Two concepts, the window of room temperature molten salt (RTMS) and depth of RTMS, were given to represent the capability and property of RTMS. According to the phase diagram, the clear evidence for the formation of RTMS was obtained. The area of the window of RTMS is x(NH4NO3)=15%-40%; the depth of RTMS is 32 K. References | Related Articles | Metrics

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High-precision temperature prediction model for plate finishing rolling process Hu, Xian-Lei (1); Jiao, Zhi-Jie (1); Li, Jian-Min (2); Liu, Xiang-Hua (1) 2003, 24 (1):  71-74.  DOI: - Abstract ( 217 )   HTML   PDF (252KB) ( 773 )   Base on the plate finishing rolling process, the temperature predition model of the plate was developed by consideration of the influence of radiation, convection, high-pressure water descaling, roll conductivity and deformation energy. It is shown that plate radiation and convection can be simplified as one-dimensional thermal conductivity. The plate blackness is the function of plate gauge. The influence of high-pressure water descaling was simplified as transient thermal conductivity model of semi-infinite flat body. The roll conductivity was simplified as the thermal conductivity model between Two semi-infinite bodies and the influence of contact thermal resistance was adjusted through correction coefficient. The temperature variation due to deformation energy was considered by adjusting the thermal power efficiency parameter. By comparing with the measure data, good predict precision of the model is proved. References | Related Articles | Metrics

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Oxidation kinetics of cast Ni-base superalloy K35 Li, Yun (1); Yuan, Chao (2); Guo, Jian-Ting (2); Yang, Hong-Cai (1) 2003, 24 (1):  75-78.  DOI: - Abstract ( 252 )   HTML   PDF (230KB) ( 823 )   The oxidation kinetics and the oxidation layer of a cast Ni-base superalloy K35 at 800°C were studied by still TGA method. The results show that oxidation kinetics of the superalloy K35 obeys the parabolic law. The oxidation stage can be divided into two parts within 100 h: the oxidation rate are 2.50×10-7 mg2/cm4·s in first stage and 2.05×10-7 mg2 /cm4 ·s in the other stage. Because the average oxidation velocity is 0.00263 mg/cm·h for 100 h, the oxidation resistance of the superalloy K35 is the first grade. It is suggested that oxidation rate of the superalloy K35 is dependent on the growth dynamics of Cr2O3. The oxide layer was examined by X-ray diffraction, scanning electron microscopy (SEM) and energy spectrum analysis (ESA). The layer is thin and consists of Cr2O3 mainly with a bit of NiCr2O4 and TiO·TiO2. During oxidation at 800°C, the inner oxidation occurs in the superalloy. References | Related Articles | Metrics

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Microstructure and electrochemical performance of HTQAB2.1/ Mg Zr-based nanocomposite hydrogen storage materials Chen, Dong (1); Ma, Chang-Xiang (1); Chen, Lian (2); Chen, De-Min (2) 2003, 24 (1):  79-82.  DOI: - Abstract ( 271 )   HTML   PDF (248KB) ( 739 )   The Zr-based nanocomposite hydrogen storage materials Zr0.9Ti0.1 (Ni0.55V0.12Mn0.28 Co0.05)2.1-X% Mg (X=10, 20) were prepared by two ways: ball-milling + sintering treatment (BMS) and mechanical alloying + sintering treatment (MMS). XRD and TEM-SAED examinations show that microstructure of the materials is composed of MgCu5-type cubic structure C15-Laves phase and hexagonal structure Mg. Their electrochemical performance tests show that the composite electrodes (MMS, BMS) have good activation properties at 60 mA/g current density. The maximum discharge capacity of MMS electrodes is 410 mAh/g(x = 20), while BMS electrodes is 360 mAh/g (x=20). At high current density(≥3000 mA/g), the discharge capacity of BMS electrodes is obviously higher than those of the MMS electrodes. The BMS(HTQAB2.1-10% Mg) electrode shows the best current density discharge performance. Therefore, HTQAB2.1 type Zr-based nanocomposite materials are suitable for not only high-energy NiMH batteries but also high-power NiMH batteries. References | Related Articles | Metrics

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Simulation and experimental research of the extending extruding process of semisolid A2017 alloy Wen, Jing-Lin (1); Guan, Ren-Guo (1); Li, Ying-Long (1); Liu, Xiang-Hua (1) 2003, 24 (1):  83-86.  DOI: - Abstract ( 275 )   HTML   PDF (243KB) ( 633 )   It is shown that mass flow velocity decreases gradually from the center to sides of mould wall during the extending extrusion process of semisolid A2107 alloy. In the middle of the way from the center to the side of the mould, there often is a transitional turbulence zone. These indicate that it is best to design a mould with smaller θ and without step a. Two sides of negative mould should be as equal as possible. When pouring temperature is higher than 790°C, due to thermal stress and alloy adhering on the mould, cracks would occur on the product surface. If pouring temperature is lower than 690°C, waves occur on the surface. The proper pouring temperature should be 710-750°C. A2017 product of 14 mm× 25 mm rectangular transection was achieved with fine surface. The fracture strength and elongation of the product are 100 MPa and 29% higher than normal requirements respectively. References | Related Articles | Metrics

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Theoretical, experimental and numerical studies on deformation and failure of brittle rock in uniaxial compression Xu, Tao (1); Tang, Chun-An (1); Zhang, Zhe (1); Zhang, Yong-Bin (1) 2003, 24 (1):  87-90.  DOI: - Abstract ( 276 )   HTML   PDF (194KB) ( 1633 )   The deformation and failure behavior of brittle rock in uniaxial compression were analyzed to establish a theoretical constitutive damage model based on damage mechanics. The numerical and experimental tests for brittle rock specimens (coal specimens included) in uniaxial compression were also carried out to obtain the complete stress-stain curves of the rocks using numerical testing machine(RFPA) and servo-controlled testing machine (RMT-150B), respectively. Based on the theoretical, numerical and experimental results,the relations and differences of complete stress-strain curves were contrastively investigated. It is concluded that numerical simulation is not a simple duplication for analytical method but an effective method to investigate the complete process of rock deformation and failure. References | Related Articles | Metrics