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15 February 2006, Volume 27 Issue 2 Previous Issue    Next Issue
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Design of robust H∞ controller for a class of uncertain systems Sun, Ping (1); Jing, Yuan-Wei (1) 2006, 27 (2):  119-122.  DOI: - Abstract ( 231 )   HTML   PDF (157KB) ( 662 )   The robust H∞ control problem of a class of uncertain systems with matched and unmatched uncertainties is discussed. Based on linear matrix inequality (LMI), the condition of quadratic stabilization is given and the H∞ performance of the systems is analyzed and designed for all admissible uncertainties. The robust H∞ controller which satisfies not only quadratic stabilization but also H∞ performance is developed. A numerical example is given to demonstrate the effectiveness and feasibility of the controller. References | Related Articles | Metrics

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Global asymptotic stability of a class of delayed neural networks Wang, Zhan-Shan (1); Zhang, Hua-Guang (1); Lu, Hua (1) 2006, 27 (2):  123-126.  DOI: - Abstract ( 238 )   HTML   PDF (157KB) ( 659 )   A new sufficient condition is given to provide the uniqueness and global asymptotic stability of the equilibrium point for a class of delayed neural network models of neutral type by constructing a Lyapunov-Krasovskii functional without assuming the boundedness, strict monotonicity and differentiability of neuron excitation function. This stability criterion imposes constraints on the interconnected matrices and derivative of time delays and is independent of the amplitude of time delays, which can be conveniently expressed in the form of linear matrix inequality (LMI) and easy to check. References | Related Articles | Metrics

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Stability domain for a class of nonlinear switched systems Li, Jun-Sheng (1); Yuan, Zhong-Hu (2); Li, Jian-Hua (2); Gao, Li-Qun (1) 2006, 27 (2):  127-130.  DOI: - Abstract ( 239 )   HTML   PDF (2136KB) ( 442 )   The concepts of nonlinear circulant system and nonlinear circulant switched system are proposed and the mathematical models are established, which are extended from hypercycle as biological systems. The two kinds of systems thus have a wide background in practice. The stability domain of both systems are studied separately, and the stability domain of the nonlinear circulant switched system in accordance to arbitrary and certain switching laws is given in terms of the eigenvalues of circulant system matrices. Simulation has verified the results. References | Related Articles | Metrics

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Robust stability of a class of status feedback networked control systems with uncertain time-delay Qiu, Zhan-Zhi (1); Zhang, Qing-Ling (1) 2006, 27 (2):  131-133.  DOI: - Abstract ( 210 )   HTML   PDF (1100KB) ( 611 )   Taking account of the event-driven actuators/controllers, clock-driven sensors, constant sampling period and uncertain time-delay less than one sampling period, the state feedback networked control system (NCS) with control constraints is modeled as a discrete time-variant system with uncertainty. Based on the Lyapunov theory and linear matrix inequality formulation, the sufficient and necessary conditions are derived for the delay-independent robust asymptotic stability of the system. By Matlab LMI toolbox to compute the stability condition, the robust asymptotic stability of the class of NCS can be determined with the robust control law of the stable system obtained. A Matlab simulation shows the effectiveness of the analysis method and stability criterion. References | Related Articles | Metrics

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Using tomographic technique to monitor moisture distribution of grain in barn Shao, Fu-Qun (1); Liu, Xiao-Huan (1) 2006, 27 (2):  134-137.  DOI: - Abstract ( 186 )   HTML   PDF (328KB) ( 715 )   A new method based on electric capacitance tomography (ECT) was proposed to monitor the moisture distribution of grain in a concrete barn with its feasibility studied. The simulation results with corn as example showed that the proposed method is available to monitor the moisture content with a resolution of 0.5% and a spatial resolution of 0.13%. The abnormal moisture part of the grain stored could be monitored by means of that the part was localized at the coordinate of center of figure of the reconstructed images. A regression and analysis was therefore done for the relationship between the grey level of images and the equivalent dielectric constant of moisture-bearing corn so as to predict its moisture content by the grey level of images reconstructed. References | Related Articles | Metrics

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Dynamic programming algorithm and optimization model of charge design for steelmaking Huang, Ke-Wei (1); Lu, Ke-Bin (1); Wang, Ding-Wei (1) 2006, 27 (2):  138-141.  DOI: - Abstract ( 285 )   HTML   PDF (155KB) ( 1047 )   Sometimes the charge design for a converter would consist of some portions as required by different orders in steelmaking process, and they would be combined into one or several melts when scheduling in view of batch production in connection with continuous casting. Some mathematical models are therefore developed to optimize the charge design. To solve the models, a dynamic programming algorithm is proposed to find an optimal solution. The time complexity of the algorithm is analyzed with a simulation example. The computational results show that by the proposed algorithm the optimized charge design for a reasonable time can be obtained to meet the requirements which will minimize the redundant steel and bring steel companies great economic benefits. References | Related Articles | Metrics

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Pricing durable goods in electronic commerce Guo, Zhe (1); Wu, Jun-Xin (1); Wang, Ding-Wei (1) 2006, 27 (2):  142-145.  DOI: - Abstract ( 289 )   HTML   PDF (876KB) ( 532 )   By expert suggestions, durable goods should be priced considering customer expectation of price and their cost in open electronic commerce. Taking account the features of durable goods, such as long service life and time/price-dependent demand of customers, a customer consumption model was developed. Making sure the algorithms in detail, some simulations were conducted to maximize the profit and sales volume on an on-line market. The results showed that for the pricing scheme of durable goods the customer expectation model is preferable to the model only considering cost. The customer expectation pricing scheme provides a reasonable way for pricing durable goods. References | Related Articles | Metrics

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Food-chain algorithm and its application to optimizing distribution network Yu, Hai-Fei (1); Wang, Ding-Wei (2) 2006, 27 (2):  146-149.  DOI: - Abstract ( 258 )   HTML   PDF (180KB) ( 594 )   Emergence and dynamic interaction with the environment are the characteristics of artificial life, i.e. the micro-interaction among individuals in the artificial-life system may result in the emergent colonization. On the other hand, the food-chain appears also an important and widespread phenomenon in the life system. Therefore, a new type of artificial-life algorithm is proposed by defining locally the rules of action at different levels of artificial-life, named the food-chain algorithm. With respect to the distribution network design, the location-allocation problem is one of the main problems. Then, the algorithm was used to solve the location-allocation problem by optimizing the distribution network structure and minimizing the cost of the supply chain. And it effectively figures out the solution to the problems. A reference is thus provided for distribution network design. Furthermore, the food-chain algorithm can be applied to the optimization in logistics, e-commerce, etc. References | Related Articles | Metrics

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Coordinated machine scheduling and conveyance problems of a steel works Guan, Jing (1); Tang, Li-Xin (2) 2006, 27 (2):  150-152.  DOI: - Abstract ( 259 )   HTML   PDF (275KB) ( 437 )   The objective to study on is to minimize the overall cost of both production and in-situ conveyance that should not be ignored in the supply chain scheduling of a steel works. Limited capacity of transporters and limited waiting time of jobs before their processing should be taken into account. To simplify the problem, it is assumed that the machine to use is just a single machine on which the job to be processed has limited time to await with unlimited number of transporters ready for use. Thus, the objective function for scheduling becomes the conventional scheduling function plus conveyance cost. For different objective function, the problem of scheduling is proved strongly NP-hard if a job has limited waiting time before processed on a single machine. As to the solvable case that the capacity of transporters is limited, some polynomial time algorithms are given. References | Related Articles | Metrics

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Improved FP-growth algorithm based on aggregative chains Jiao, Ming-Hai (1); Jiang, Hui-Yan (1); Tang, Jia-Fu (2) 2006, 27 (2):  153-156.  DOI: - Abstract ( 252 )   HTML   PDF (904KB) ( 665 )   An improved frequent pattern FP growth algorithm based on aggregative chains is proposed. A kind of single linked lists named aggregative chain is introduced to the algorithm, thus improving the architecture of FP tree. The new FP tree is a one-way tree and only the pointers to point its children at each node are kept to save the space of tree in comparison with the former one. Route information of different nodes in the same term are compressed into aggregative chains so that the frequent patterns will be produced in aggregative chains without generating node links and conditional pattern bases. Agrawa tests data verified the advantage of time occupancy of the proposed algorithm. References | Related Articles | Metrics

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Storability analysis of object-oriented XML data Zhang, Xiao-Lin (1); Tan, Yue-Sheng (2); Zhang, Jun (2); Wang, Guo-Ren (1) 2006, 27 (2):  157-160.  DOI: - Abstract ( 237 )   HTML   PDF (156KB) ( 491 )   Aiming at the two storage models for object-oriented XML data, i.e. centralized and decentralized, the query algebra for object-oriented XML is designed and implemented on the bases of their respective path repositories of XML structure information and data repositories of XML data. Introducing extended XML-RL query language to support inheritance, the storability of two models is analyzed by four typical queries including polymorphic element, polymorphic reference, monomorphic element and monomorphic reference. The result indicates that the centralized storage model outperforms the decentralized one at polymorphic element and monomorphic element queries and vice at polymorphic reference and monomorphic reference queries. References | Related Articles | Metrics

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Fast blind beamforming algorithm based on neural network Wang, Jin-Kuan (1); Tian, Dan (1); Xue, Yan-Bo (1); Jia, Li-Qin (1) 2006, 27 (2):  161-164.  DOI: - Abstract ( 283 )   HTML   PDF (196KB) ( 1108 )   Defining a new mapping relationship, the generation process of training data is effectively simplified when using the radial basis function neural network (RBFNN) to realize beamforming. The parallel processing with two networks are used to improve the network convergence rate and approximate Wiener solution via post-processing. Computer simulations show that the signal trackability of this algorithm approximates very well to that of the minimum variance distortionless response (MVDR) algorithm. But because this algorithm combines the strong fault tolerability of neural network with the architectural advantage of parallel operation, it can make the computation more rapid and more robust to systematic error in comparison to MVDR algorithm. References | Related Articles | Metrics

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Central DOA estimation based on propagator method for distributed sources Han, Ying-Hua (1); Wang, Jin-Kuan (1); Song, Xin (1) 2006, 27 (2):  165-168.  DOI: - Abstract ( 272 )   HTML   PDF (164KB) ( 512 )   The propagator method is suggested to estimate the central DOA (direction of arrival) of distributed sources especially the incoherently distributed sources. A first order approximation is done for the direction vector by Taylor series so as to obtain the direction vector of distributed source which is similar to point source in form. Then, the proposed method is used to estimate the central DOA, thus solving efficiently the problem of the estimation of DOA of both coherently and incoherently distributed sources, of which the spreading of angle of arrival is small, and the sources are of different angular signal densities. The proposed method is simple in computation and can be applied to the estimation of central DOA of several distributed sources. Simulations clearly demonstrate that it is not only effective but also offers better SNR (signal to noise ratio) performance in comparison with MUSIC algorithm. References | Related Articles | Metrics

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Network characteristics of urban population migration Zhang, Yong-Qing (1); Zhao, Hai (1); Zhang, Wen-Bo (1); Ha, Tie-Jun (1) 2006, 27 (2):  169-172.  DOI: - Abstract ( 308 )   HTML   PDF (254KB) ( 1125 )   Based on the census date of Northeast China and the gravitation model of urban population migration, an urban network was established and the network characteristics of urban population migration were analyzed according to the complex network theory and existing research achievements. The results showed that the urban network is typically scale-free, and the relation between the population and the city where they live in is just like that between the network throughput and the nodes. The migration of urban population has a tendency to preference. So, a preference model was developed. Furthermore, the degree distribution of nodes of the urban network in Northeast China was also discussed. In the light of the node degree of every city, the future development centers in Northeast China is predicted. References | Related Articles | Metrics

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Development of architecture of computer control system for plate rolling process He, Chun-Yu (1); Wu, Di (1); Wang, Jun (1); Wang, Guo-Dong (1) 2006, 27 (2):  173-176.  DOI: - Abstract ( 240 )   HTML   PDF (473KB) ( 808 )   The architecture and functions of the control system we developed for plate rolling process were introduced according to the characteristics of the process. How the data communication is implemented among the modules used was analyzed in detail. Based on the application in site, a conceptual design was suggested for the system software to constitute a two-level software hierarchy of process control of which the communication is separated from the process model. Such a hierarchy meets all the safe and stable requirement for the operation of the process control system and simplifies the debugging procedure and maintenance for the system. Introducing the expandable open design into the software hierarchy, the adaptability of the control system becomes stronger. Such a hierarchy is adaptable to the development of cooling process control as well. References | Related Articles | Metrics

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Design and simulation of repetitive control system for roll eccentricity compensation Li, Yong (1); Wang, Jun (1); Hu, Xian-Lei (1); Liu, Xiang-Hua (1) 2006, 27 (2):  177-180.  DOI: - Abstract ( 265 )   HTML   PDF (198KB) ( 802 )   The conventional PID controller used in roll gap control system may cause great steady-state tracking error when compensating the periodic signal of roll eccentricity, and thus the roll eccentricity compensation often fails. For this reason, a new eccentricity compensation system based on the theory of repetitive control is presented, by which there is no steady-state error when tracking the periodic signal to compensate roll eccentricity. The simulation results show that the new system can respond very well the compensation for roll eccentricity with highly steady accuracy. It outperforms far and away the conventional PID controller system and greatly improves the probability of success of roll eccentricity compensation. References | Related Articles | Metrics

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Precipitation behavior and effects of vanadium carbonitride in V and V-N microalloyed mild steel during multi-pass deformation Wang, Li-Jun (1); Wang, Kai (1); Ren, Hai-Peng (1); Liu, Chun-Ming (1) 2006, 27 (2):  181-184.  DOI: - Abstract ( 297 )   HTML   PDF (543KB) ( 972 )   The microstructure evolution and precipitation behavior of vanadium carbonitride were examined using a Gleeble 1500 thermal simulator, as well as their mutual effect in V and V-N microalloyed mild steel (0.1%C-1.0%Mn) during multi-pass deformation at 860-740°C. The result showed that adding a small amount of N to V microalloyed steel will expedite the precipitation of V(C, N), especially V-N in deformed austenite, and the deformation induced ferrite transformation (DIFT). But the concentration of V dissolved in austenite decreases because of the precipitation of V(C, N), thus weakening the effect of V on suppressing DIFT so as to expedite the ferrite nucleation. Moreover, the precipitation of V(C, N) causes locally the formation of carbon-poor region in austenite, thus expediting the ferrite nucleation further. Comparing with the V microalloyed steel under the same treatment conditions, the precipitation of V(C, N) within ferrites in V-N microalloyed steel requires shorter inoculation time with higher V(C, N) volume fraction, lower growth rate and wider dispersion. References | Related Articles | Metrics

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Microstructure and performance of semi-solid rheoformed alloy ZL201 Zhao, Tao (1); Kang, Hao (2); Shi, Li-Feng (2); Wang, Ping (2) 2006, 27 (2):  185-187.  DOI: - Abstract ( 210 )   HTML   PDF (406KB) ( 433 )   The molten metal of alloy under the action of electromagnetic field was studied for the rheoforming technology, microstructure and performance of the alloy ZL201 in semi-solid state in AC electromagnetic field. The results showed that the semi-solid alloy can be molded up with smooth surface, precise size, compact microstructure and without pores and inclusions under the action of the 18 A/50 Hz electromagnetic field if the temperature of melt is 650 ± 1°C and that of mold is 510 ± 1°C. The hardness of the molded specimen is up to 108 HV5, 1.5 times as high as that of the one being not rheoformed. The results will lay down a foundation for the application of rheoforming technology to semi-solid aluminum alloys. References | Related Articles | Metrics

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Temperature dependence of permeability of nanocrystalline alloy Co51Fe18 Nb6Si15B10 Zhi, Qi-Zheng (1); Dong, Bang-Shao (1); Chen, Wen-Zhi (2); Lian, Fa-Zeng (1) 2006, 27 (2):  188-191.  DOI: - Abstract ( 304 )   HTML   PDF (1124KB) ( 683 )   The effect of annealing temperature on the temperature dependence of initial permeability μi and microstructure of the amorphous alloy Co51Fe18 Nb6Si15B10 was analyzed through Hopkinson effect and X-ray diffraction. It was found that the μi-t curves present in four types including the Hopkinson peak, smooth peak, long tail and monotonous rising, with all measurements of initial permeability conducted during heating. The microstructural transformation could be divided into three phases. According to the change of magnetic parameters in the temperature rising processes of the single-phase amorphous alloy and dual-phase nanocrystalline alloy, the influences of the volume fraction of α/-Fe(Co) nanocrystalline phase, the residual amorphous phase and the magnetic exchange coupling between nanocrystalline grains on the temperature dependence of initial permeability were also discussed. References | Related Articles | Metrics

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Behavior of nonmetallic inclusions in casting slab of BOF bearing steel Wang, Shuo-Ming (1); Lu, Qing (2); Wang, Hong-Li (2); Liang, Mei (3) 2006, 27 (2):  192-195.  DOI: - Abstract ( 263 )   HTML   PDF (258KB) ( 749 )   The distribution and characteristics of nonmetallic inclusion in the bearing steel slabs melted and cast in the process of BOF-LF-VD-CC were explored, with a tracer used to find the origin of inclusion. The aim is to provide a reference for getting rid of inclusions to improve the quality of BOF bearing steel. The results showed that in the high-cleanness slabs the mean value of T[O] is 9.3 × 10-4 wt%, the micro inclusions are 0.031 vol% and the large-size (>50 μm) inclusions are 1.5 mg/10 kg, and most of the inclusions are micro inclusions (<5 μn) whose distribution feature determines the distribution feature of inclusions in casting slab. The micro inclusions are mainly the compounds formed via the adsorption/aggregation of multielement deoxidized compounds and secondarily deoxidized products on tundish liquid level. The rest is mainly the contaminants present in molten steel, which are coming from the liquid level in mold. The liquid level in tundish affects slightly the molten steel. References | Related Articles | Metrics

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Determination of thermal conduction coefficient of refractory and thermal insulation materials Liu, Shi-Ying (1); Yu, Ya-Xin (1); Qiu, Zhu-Xian (1) 2006, 27 (2):  196-198.  DOI: - Abstract ( 304 )   HTML   PDF (155KB) ( 1123 )   An experimental setup was designed to determine the thermal conduction coefficients of refractory and thermal insulation materials on the basis of China's Standard YB/T059-91. The layout of the experimental setup, measuring principle, testing method and results were described. Taking a carborundum brick of which the thermal conduction coefficient was given as specimen, the measuring error is less than 8%. The relative error between the two specimens which were cut off from the same thermal insulating brick is less than 3%. References | Related Articles | Metrics

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Technological mineralogy and manganese occurrence state of a manganese-silver deposit in Guangxi Yang, Hong-Ying (1); Gong, En-Pu (2); Fan, You-Jing (3) 2006, 27 (2):  199-202.  DOI: - Abstract ( 326 )   HTML   PDF (936KB) ( 1138 )   The technological mineralogy of a manganese-silver deposit in Guangxi is studied. Identifying its mineral composition, the metallic minerals are revealed consisting of psilomelane, pyrolusite, pyrite and hematite with a few of arsenopyrite, chalcopyrite and sphalerite. The textures of the manganese-silver ore include aphanitic, colloform, micro-squama and arenaceous textures, and its structures are mainly the vein, colloform and dissemiinated structures. The silver grade of manganese-silver concentration is 3923 g·t-1. The occurrence state of manganese in the deposit is the self-contained manganese mineral including psilomelane and pyrolusite. In the concentration the grain size distribution of psilomelane is 17% in the range 0.152-0.088 mm, 38% in 0.088-0.074 mm and 40% >0.074 mm, while that of pyrolusite is 18% in 0.152-0.088 mm, 35% in 0.088-0.074 mm and 37% >0.074 mm. References | Related Articles | Metrics

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Removal of Cu in wastewater with chitosan Zhang, Ting-An (1); Dou, Zhi-He (1) 2006, 27 (2):  203-205.  DOI: - Abstract ( 300 )   HTML   PDF (209KB) ( 1084 )   To remove Cu from wastewater using chitosan as flocculants, the effects of hydroxides, pH value, mass concentration of Cu2+ and flocculating time/temperature on removal rate were investigated. When pH value is 8 and the mass concentration of Cu2+ in water is lower than 100 mg·L-1, the removal rate of Cu2+ is higher than 99%. Even the original mass concentration is 400 mg·L-1, the residual mass concentration of Cu2+ is still up to China's national wastewater drainage standard. When using NaOH as flocculant the pH value is 11 and the removal rate of Cu2+ reaches 100%, but the consumption of alkali is too much and the acidity cannot meet the required standard for wastewater drainage. References | Related Articles | Metrics

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RTD curves of tubular reactor with stirrer Zhao, Qiu-Yue (1); Zhang, Ting-An (1); Cao, Xiao-Chang (1); Jiang, Xiao-Li (1) 2006, 27 (2):  206-208.  DOI: - Abstract ( 365 )   HTML   PDF (155KB) ( 1835 )   A new-type tubular reactor with a stirrer is designed composed of several vanes which are perpendicular to each other. The residence time distribution (RTD) curves of tubular reactors were determined using NaCl solution as a tracer. The mean value and square deviation of residence time measured at different outlet with different stirring speeds and flow rates were calculated and analyzed by L9(33) orthogonal experiments. The results showed that the flowing state of the fluid in the reactor approaches piston flows, and the mean residence time decreases with increasing flow rate of the fluid and increases with the increasing length of reactor. But, how the mean residence time changes with the varying stirring speed is not obvious. References | Related Articles | Metrics

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Preparation of CuCr alloy by SHS melting and its characterization Dou, Zhi-He (1); Zhang, Ting-An (1); Liu, Chang-Sheng (1); Yang, Huan (1) 2006, 27 (2):  209-212.  DOI: - Abstract ( 192 )   HTML   PDF (828KB) ( 569 )   CuCr alloy was prepared by self-propagating high-temperature synthesis (SHS) melting. How the proportioning of reactants, additive CaF2, different molds and mold preheating temperature affect the alloy composition, macromorphology and microstructure of the alloy specimens were investigated respectively. Experimental results indicated that the reasonable proportioning of the reactants is 100:140:160 of ω(CuO):ω(Cr2O3):ω(Al); the additive CaF2 can not only lower the melting point of slag but also can improve the efficiency of separating metal from slag; the high cooling rate of the alloy in metal mold makes its crystal grains finer; and when casting in the graphite mold, the quality of the alloy can be improved if the preheating temperature is rising, e.g. the compact CuCr alloy is available at a preheating temperature of 500°C. References | Related Articles | Metrics

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Model to predict probability of common cause failure in redundant system Li, Cui-Ling (1); Li, Jian-Feng (2); Xie, Li-Yang (1) 2006, 27 (2):  213-216.  DOI: - Abstract ( 261 )   HTML   PDF (171KB) ( 808 )   According to the mathematical theory of reliability and the physical model of component failure, i.e. the stress-strength interference model, component failure probability is regarded as a random variable complying with a certain distribution. The mathematical expression of a prediction model of the probability of common cause failure in redundant system is thus derived. Using the Monte Carlo simulation method and neural network technique, the distribution type and parameters of the random variable are obtained. Based on the limited failure data, the model can predict the failure probability of arbitrary order for a redundant system, and it can make up for what have been omitted by the traditional models for common cause failure. A typical example is given to illustrate the application of the model with the calculated results compared to those resulting from BFR model. The results show that the proposed approach is more accurate. References | Related Articles | Metrics

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Temporarily-spatially constrained workflow authorization model (TSCWAM) based on RBAC Xu, Hong-Xue (1); Guo, Xiu-Ying (2); Liu, Yong-Xian (1) 2006, 27 (2):  217-220.  DOI: - Abstract ( 274 )   HTML   PDF (253KB) ( 657 )   A temporarily-spatially constrained workflow authorization model (TSCWAM) based on role-based access control (RBAC) was proposed. Differing from the conventional access control authorization models based on subject-object pattern, the model offers a notion of temporal-spatial permission that the workflow authorization based on RBAC is constrained not only temporarily but also spatially, i.e. the authorized user is just permitted to operate a certain task within a certain time and space. Thus, the tasks which form a workflow can only be performed by a user who is assigned to play a special role in operation, and the user can make sure that the authorized flow is coordinated mutually with the spatially dynamic change on the basis of synchronization of both authorized flow and workflow. References | Related Articles | Metrics

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Fully hydraulic thermal exploiting system for viscous crude oil Song, Jin-Chun (1); Dong, Jia-Qing (2); Zhang, Zhi-Wei (1); Cong, Heng-Bin (1) 2006, 27 (2):  221-224.  DOI: - Abstract ( 273 )   HTML   PDF (203KB) ( 601 )   The oil exploiting facility and hydraulic working principle of the fully hydraulic thermal exploiting system for viscous crude oil are introduced with its feasibility analyzed. In the system, the bottom hole fluids are studied thermodynamically by means of developing physical and mathematical models and simulation on computer. It was found that when the bottom hole temperature of crude oil remains unchanged, the heating efficiency of hydraulic oil is equivalent to that of crude oil, and the outlet temperature of crude oil is basically in linear relation to inlet temperature of hydraulic oil. In addition, the hydraulic oil lowest inlet temperature needed for crude oil heat preservation is also basically in linear relation to hydraulic oil flow rate. Thus the way proposed to the system to heat and exalt viscous crude oil is feasible with satisfactory result. The developed models also provide theoretically a basis on which the heat transfer of bottom hole fluids will be studied further. References | Related Articles | Metrics

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- - 2006, 27 (2):  225-229.  DOI: - Abstract ( 223 )   HTML   PDF (1245KB) ( 628 )   - References | Related Articles | Metrics

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Method for multiple criteria decision making with incomplete information Zhang, Yao (1); Fan, Zhi-Ping (1) 2006, 27 (2):  230-232.  DOI: - Abstract ( 258 )   HTML   PDF (153KB) ( 530 )   A new decision analysis is proposed to the multiple criteria decision making problems with incomplete information on criteria weights and values. The types of incomplete information on criteria weights and values are introduced and the corresponding multiple criteria decision making problems with incomplete information are discussed while the calculation steps to solve these problems are given. Of which the kernel is to construct and solve a quadratic programming model so as to determine the criteria weights and values. Then, the appraisal value of every alternative can be calculated to rank alternatives. A numerical example is given to illustrate the application and practicality of the proposed method. References | Related Articles | Metrics

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Coopetition analysis of clustered network supply chain by repetitive game theory Qi, Gui-Qing (1); Yang, Xi-Huai (1); Li, Sen (1) 2006, 27 (2):  233-236.  DOI: - Abstract ( 176 )   HTML   PDF (211KB) ( 993 )   Discussing the characteristics of clustered network supply chain, the repetitive game theory is dynamically applied to analyzing the Coopetition states of the companies between the up-stream and down-stream nodes of a single supply chain belonging to a clustered network supply chain and of the companies between the nodes of the same value on parallel supply chains. The conditions on which the cooperation can be in equilibrium are thus given. A conclusion is drawn that there is a big room for cooperation between the nodes of a single supply chain belonging to a clustered network supply chain, while the room is big for competition but small for cooperation if it is between the nodes of the same value on parallel supply chains. References | Related Articles | Metrics