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15 May 2006, Volume 27 Issue 5 Previous Issue    Next Issue
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Active queue management algorithm based on fuzzy sliding mode control Yin, Feng-Jie (1); Jing, Yuan-Wei (1); Yang, Hui (1) 2006, 27 (5):  473-476.  DOI: - Abstract ( 293 )   HTML   PDF (1332KB) ( 669 )   Based on fuzzy sliding mode control (FSMC), an active queue management (AQM) algorithm adaptable to the change of dynamic network flow is presented to solve the problems of dynamic network congestion. With the fuzzy control introduced in, the arrival time is shortened and the jitter from sliding mode control is improved. The algorithm shows its high robustness to the nonlinear control problems in TCP/IP networks, such as modeling uncertainties, fluctuation of time-varying parameters and jitter of network due to the flow unadaptive to TCP model. Simulation results demonstrated that this method enables the queue length to converge at a preset value quickly and keeps the queue oscillation small and, in particular, the algorithm proposed outperforms the conventional PI control, fuzzy control and sliding mode control if the network conditions change. References | Related Articles | Metrics

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Guaranteed cost control with quadratic stability of uncertain discrete-time switched systems Sun, Wen-An (1); Feng, Jia-Xin (2); Zhong, Wei-Song (1); Zhao, Jun (1) 2006, 27 (5):  477-480.  DOI: - Abstract ( 280 )   HTML   PDF (184KB) ( 596 )   Explores the problem of the robust guaranteed cost control with quadratic stability of uncertain discrete-time switched systems under arbitrary switching laws, based on LMIs. Constructing LMIs using Schur complement lemma, several sufficient conditions are given in terms of LMIs for the problem. With these less conservative conditions the quadratic stability are easy to check and the upper bound of cost index can be satisfied. The effectiveness of the method has been illustrated by a numerical example. References | Related Articles | Metrics

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Approach to data mining based on rough sets and decision tree Wu, Cheng-Dong (1); Xu, Ke (2); Han, Zhong-Hua (2); Pei, Tao (2) 2006, 27 (5):  481-484.  DOI: - Abstract ( 285 )   HTML   PDF (790KB) ( 954 )   Rough sets and decision tree have complementary characteristics. A new approach to data mining is thus proposed combining both advantages. Taking the detected data of plywood defects as example, the defects are recognized as follow using eigen information in the database of plywood on the basis of rough sets theory. Decentralizes the data in the database by the algorithm of center-of-gravity distance of pedigree cluster, then reduces the conditional attribute by use of rough sets to obtain the low dimensional sample data. Decision rules are finally obtained by decision tree. The experimental result shows that, in this way, the original characteristics of data remained unchanged, and the knowledge acquisition process become speedier so as to improve the classification accuracy of model and interpretability of rules. Comparing with other the methods, such as rough sets or precision-varied rough sets, the method is proved more satisfactory. References | Related Articles | Metrics

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Integration technologies for design of aero-gas turbine Wang, Cheng-En (1); Liu, Zhen (1) 2006, 27 (5):  485-488.  DOI: - Abstract ( 258 )   HTML   PDF (191KB) ( 1291 )   Aero-engine design involves a number of software packages, to which the integration of design data with application system is of highly technological and industrial significance. The component-based COM is introduced in integrating the multidisciplinary computing packages applicable to the design of aero-gas turbine, with the agent objects used to pack a number of aerodynamic, thermodynamic and structural computing packages so as to provide the trans-processing request-response service on the basis of COM call mechanism. The COM-based integration system provides a variety of functions, such as computing package registration, running control, parameter mapping, design specification management and knowledge management. The system can also support the visualized design simulation and on-line collaboration among single project designers, thus improving the efficiency and quality of design and shortening effectively the time required for design. References | Related Articles | Metrics

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Control, model optimization for logistics center to stock goods in time-dependent demand Liu, Bao-Zheng (1); Liu, De-Bao (1); Gao, Li-Qun (1) 2006, 27 (5):  489-492.  DOI: - Abstract ( 214 )   HTML   PDF (996KB) ( 587 )   Studies the stocking quantity locus on the conditions that there is redundancy in inventory in logistics center and the distribution system demands time-dependent goods, with the intention of keeping its inventory to satisfy the demands of retailers in time and upgrade the level of their service. The inventory management cost can be reduced if stocking locus is behind demanding locus. Analyzing the logistics system and then based on the optimal control theory, the Hamilton function and co-state equation are used to develop an optimal stocking tactic so as to keep satisfactory inventory, thus predicting the data available to control the stocking quantity needed by logistics center. In this way the stocking procedure can be scheduled to satisfy inventory to the utmost extent. An example is given to show the validity of the control tactic proposed. References | Related Articles | Metrics

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Tabu-hierarchy genetic QoS multicast routing algorithm in NGI Wang, Xing-Wei (1); Hou, Mei-Jia (1); Yi, Xiu-Shuang (2); Huang, Min (1) 2006, 27 (5):  493-496.  DOI: - Abstract ( 278 )   HTML   PDF (1014KB) ( 473 )   A non-NP QoS (quality of service) multicast routing algorithm in IP/DWDM optical Internet, which is one of the main networking technique of NGI (next generation Internet) backbone, is proposed to construct an optimized QoS multicast routing tree based on THGA (tabu-hierarchy genetic algorithm). The algorithm imitates the biologic propagation process and adopts the hierarchical coding scheme with two tabu operators (tabu crossover and tabu mutation) introduced to improve the genetic operation, taking account of user's requirements for QoS and network cost to benefit the balance in network load. Simulation results showed that the proposed algorithm is both feasible and effective in overcoming the specific shortcomings in the QoS multicast routing algorithm just based on the classical GA to a certain extent, such as prematurity and slow convergence. It not only improves the efficiency and performance of algorithm but provides a better way to construct the QoS multicast routing tree in IP/DWDM optical Internet. References | Related Articles | Metrics

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Numerical simulation of M-EMS for bloom continuous casting Li, Jian-Chao (1); Cui, Jian-Zhong (1); Wang, Bao-Feng (2); Ma, Yong-Lin (2) 2006, 27 (5):  497-500.  DOI: - Abstract ( 285 )   HTML   PDF (689KB) ( 694 )   A numerical simulation was conducted at 600 A/2 Hz for the M-EMS behavior of a bloom during continuous casting by virtue of the FEA software ANSYS. The comparison showed that the calculated results conform basically with the experimental data. Discusses emphatically the relationship between the magnetic filed induction or node magnetic force at the centre of bloom and the changing current/frequency. The results show both magnetic induction and node magnetic force at the centre of bloom increase with the current also the frequency, of which the maximum value is found at 8 Hz. References | Related Articles | Metrics

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Strategy for finishing temperature setting for hot-rolled strip Li, Hai-Jun (1); Xu, Jian-Zhong (1); Wang, Guo-Dong (1); Liu, Xiang-Hua (1) 2006, 27 (5):  501-504.  DOI: - Abstract ( 601 )   HTML   PDF (200KB) ( 1710 )   Based on several exiting mathematical models, an off-line temperature simulation software was developed to improve the control effect on strip head temperature in finishing rolling process and draw up a more reasonable inter-stand spray water cooling scheme. Simulating computation was done off-line for the strips of various sizes and results conformed well to those measured, which showed its accuracy. Then a strategy was designed for finishing temperature and used to work out two quite distinct types of the control logic of inter-stand spray water cooling. The results showed that the range of target finishing temperature can be provided and kept on in an energy-saving manner with lower frequency of spray nozzle opening if opening reversely but closing forwardly the cooling valve for inter-stand spray during water cooling. References | Related Articles | Metrics

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Thermal performance of continuous heating regenerative furnace Tian, Hong (1); Cai, Jiu-Ju (1); Zhao, Wei-Guo (1) 2006, 27 (5):  505-508.  DOI: - Abstract ( 248 )   HTML   PDF (344KB) ( 590 )   Develops a mathematical model for flame furnaces. Then the influence of changing operation parameters on production indexes is investigated with the structural parameters of flame furnaces kept constant to obtain and compare the Q-P equations and b-P equations of both continuous heating regenerative furnace and heat-exchange furnace. The results show that during normal production the thermal load of continuous heating regenerative furnace increases linearly with its productivity but the specific energy consumption reduces very slowly and approximately linearly. At the same time, the change in temperature of exhaust gas and thermal efficiency almost keep constant and linear. As to the heat-exchange furnace, the thermal load of furnace and temperature of exhaust gas increase gradually, and the specific energy consumption decreases first then increases with the thermal efficiency changing vice versa. Comparing the two types of furnaces with each other, the regenerative one shows a much wider operation range and is more suitable for the production with widely changed output. References | Related Articles | Metrics

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Numerical simulation of gas flow distribution in pelletizing shaft furnace Dong, Hui (1); Cai, Jiu-Ju (1); Wang, Guo-Sheng (2); Yang, Jun (1) 2006, 27 (5):  509-512.  DOI: - Abstract ( 334 )   HTML   PDF (394KB) ( 711 )   According to the dynamics of gas-solid packed beds, a mathematical model of gas flow in an air internal vertical channels (IVAC)/drying bed palletizing shaft furnace (PSF) is developed with certain boundary conditions. Using a manual program to solve the gas flow velocity field, the law of gas flow distribution in the PSF is investigated to discuss how the operating parameters affect the gas flow distribution. It is revealed that both the roasting and cooling air flow run radially at inlets and then run slantingly upwards or downwards into roasting-preheating zone inside IVAC. And the gas flow in the whole soaking zone is weakened. There are possibly three gas flow patterns in PSF, which are mainly dependent on the ratio of inflow, i.e., the greater the ratio is, the higher the downward roasting air flowrate and the lower the upward air flowrate will be. The critical ratio of inflow mainly depends on the constructional parameters and packed bed conditions of PSF. References | Related Articles | Metrics

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Thermodynamics of electrolytic Al-Zr master alloys Cao, Da-Li (1); Shi, Zhong-Ning (1); Wang, Ji-Kun (2); Qiu, Zhu-Xian (1) 2006, 27 (5):  513-516.  DOI: - Abstract ( 351 )   HTML   PDF (161KB) ( 492 )   The prominent effect of Zr on Al and Al-based alloys is briefly introduced. The process scheme of manufacturing Al-Zr master alloy by electrolysis of ZrO2 in cryolite-alumina melt cell is put forward. The feasibility of the scheme is analyzed thermodynamically, and the activity coefficient of Zr in Al-Zr master alloys has been calculated by Miedema's model. The results reveal that both Al and Zr can jointly be precipitated and the solubility of ZrO2 in molten cryolite is approximately up to 0.55% and the activity coefficient of Zr in Al-Zr master alloy near to 1 at 1223 K. In addition, the Al-Zr master alloy containing about 2wt% is available to get directly in cell. References | Related Articles | Metrics

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Preparation of aluminum foam sandwich and foam cell Zhang, Min (1); Zu, Guo-Yin (1); Yao, Guang-Chun (1); Duan, Shui-Liang (1) 2006, 27 (5):  517-519.  DOI: - Abstract ( 312 )   HTML   PDF (730KB) ( 722 )   A new way to compact powder is proposed for preparation of aluminum foam sandwich, i.e., two metal plates are stacked and rolled together with Al-Si-Ca powder containing 1wt% TiH2 foaming agent between them, which is then foamed in heating furnace. The new way not only gets rid of the disadvantage of adhesive bonding, so as to enable the metallurgical bonding to come true but also shortens the technological process and saves the energy. The morphology of the foam cell is investigated to analyze the enrichment of titanium and furrows on cell wall. The results show that rolling the powder together with steel plates can successfully form the structure of aluminum foam sandwich (AFS). The consolidation of pores and formation of the micro-pores are the main influencing factor on cell structure. The enriched titanium grains attaching to the cell wall serve a stabilization function for foam cell in foaming process, and the curved and/or furrowed cell walls are found in solidification process. So it is very important to control the solidification process. References | Related Articles | Metrics

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Nonlinear dynamic behavior of coupling rubbing faults in sliding bearing-rotor-stator system Yuan, Hui-Qun (1); Wu, Ying-Xiang (1); Li, Dong (1); Wen, Bang-Chun (2) 2006, 27 (5):  520-523.  DOI: - Abstract ( 257 )   HTML   PDF (493KB) ( 938 )   Based on a certain type of aero-engine, 4-mass nonlinear dynamic model is developed for the behavior of rubbing faults in a sliding bearing-rotor-stator system, with which the synthetic effect of nonlinear reactive force and viscous shearing force of oil film and rubbing force on the response to the coupling rubbing faults of the system is analyzed. The bifurcation and chaos of the system are then analyzed via a numerical simulation with the viscous shearing force of oil film taken into account, thus revealing some practical graphic representations in the domain of actual parameters with nonlinear response for the system. It follows that when the system response occurs within a wideband frequency range it includes not only the dividing periodic motion but also the quasi-periodic motion and chaotic motion in the system, and a great number of narrow-band periodic windows are found in the chaotic motion region. The chaotic motion in the system is affected by the viscous shearing force of oil film, which should be taken into account in exploring the chaotic motion of the whole system. References | Related Articles | Metrics

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Precise diagnosis of rotor rubbing fault based on modal expansion and harmonic decomposition Yu, Tao (1); Han, Qing-Kai (1); Sun, Wei (1); Wen, Bang-Chun (1) 2006, 27 (5):  524-527.  DOI: - Abstract ( 172 )   HTML   PDF (178KB) ( 610 )   An FEM model of rotor-bearing system was set up for a single-span-two-disc test rig to obtain such model parameters as the first and second order natural frequency and vibration mode vectors. Based on the assumption of periodic rubbing force in rotor system, the rubbing forces onto each node of rotor system are estimated by modal expansion technique and the sub-harmonic decomposition of residual matrix between faulty and faulty-free vibration signals of rotor system through FFT (fast Fourier transformation). The rubbing position is identified through time serials, frequency spectrum and equivalent magnitude of rubbing force on each node, with corresponding extent of rubbing fault evaluated qualitatively. The method proposed is tested on the single-span-two-disc test rig and proved efficient in precise diagnosis of periodic rubbing force in rotor system, and it also provides a reference for other fault diagnosis of rotor-bearing system. References | Related Articles | Metrics

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Stochastic response to impact/rub acted on rotor-stator box system in rotary machine Su, Su-Ying (1); Zhang, Yi-Min (1); Li, He (1); Wen, Bang-Chun (1) 2006, 27 (5):  528-531.  DOI: - Abstract ( 278 )   HTML   PDF (317KB) ( 754 )   Based on the impact/rub dynamic equation for Jeffcott rotor in a rotary machine with mass eccentricity, the stochastic response to the impact/rub acted on a rotor-stator box system is systematically investigated by way of Kronecker algebra, matrix calculus, second order moment analysis of vector-valued and matrix-valued functions, matrix perturbation theories and probability statistics methods. The generalized mathematical expressions of both first order and second order moments in the stochastic response are thus derived with numerical solutions given. Analyzes the stochastic responses to the random parameters of the rotor-stator box system, such as the shaft stiffness and damping, stator stiffness and damping, eccentricity and radial stiffness of stator. The results indicate that in the rotor system a strong vibration takes place initially, to which the response amplitude is greater than the radial clearance between rotor and stator, thus leading to impact/rub. References | Related Articles | Metrics

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Application of three-in-one design criterion in overall evaluation of product quality Li, Xiao-Peng (1); Ren, Zhao-Hui (1); Song, Nai-Hui (1); Wen, Bang-Chun (1) 2006, 27 (5):  532-535.  DOI: - Abstract ( 267 )   HTML   PDF (1312KB) ( 557 )   Puts forward a multi-level fuzzy model for overall evaluation of product quality grade, which combines the dynamic optimization, intellectualization and visualization into one in design on fuzzy theory basis. This model consists of a set of factors relating to product quality grades, including construction, serviceability and process technology as evaluation indices, by which a decisive evaluation set is formed in terms of different quality grades. The primary fuzzy evaluation is done by each and every index as listed in the related set of different factors, then the secondary fuzzy evaluation is done on the basis of the primary evaluation results and decisive evaluation set. Such evaluation results are also available to judge if the design of a product satisfies the requirements for product quality. Taking a new-type hydraulic pile driver/extractor as example, its quality is evaluated overall by the evaluation model proposed and, by the way, its design is verified. References | Related Articles | Metrics

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Signal de-noising research based on new threshold function via dyadic wavelet transform Liu, Jie (1); Zhu, Qi-Bing (1); Li, Yun-Gong (1); Ying, Huai-Qiao (2) 2006, 27 (5):  536-539.  DOI: - Abstract ( 286 )   HTML   PDF (1214KB) ( 809 )   There is a certain redundancy in the primary function of wavelet for dyadic wavelet transform. So, the de-noising result by dyadic wavelet transform is better than that by discrete wavelet transform. How to estimate the noise threshold and select the threshold function exactly will affect obviously the de-nosing accuracy. Analyzing the characteristics of the dyadic wavelet transform of Gaussian noise, a new approach to signal de-noising is proposed to improve the dyadic wavelet transform by introducing a new threshold to get rid of the constant error when using Donoho's soft threshold to estimated and decompose the wavelet coefficients. Simulation results indicate that the new approach will not only suppress effectively the pseudo-Gibbs phenomena at the singular point of signal waveform, but provide a higher de-noising accuracy than Donoho's hard and soft-threshold methods. References | Related Articles | Metrics

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Strategic capacity planning based on networked manufacturing for supply chain Dong, Hai (1); Wang, Wan-Shan (1); Gong, Ya-Dong (1); Li, Yan-Ping (2) 2006, 27 (5):  540-543.  DOI: - Abstract ( 294 )   HTML   PDF (158KB) ( 537 )   Defines the supply chain network system as at three levels, i.e., supplier, manufacturer and retailer, and takes the costs for the capacities of supply, manufacture and transport of the three levels as a target function to minimize the costs. As a result, a strategic capacity planning model for supply chain is developed to respond rapidly to the dynamic changes of market at minimal cost. Using heuristic algorithm to find out a feasible solution as an upper limit of branch-and-bound algorithm, an optimal solution is got iteratively. A numerical example demonstrates that the implement of strategic capacity planning in an enterprise as a node of supply chain can optimize the utilization rate of its resource and reduce its inventory to the utmost extent, as well as the maturity of the optimization objective and the validity of the model and algorithm. References | Related Articles | Metrics

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Key technology of individualizing customization to be oriented toward networked manufacturing Liu, Jia (1); Xu, Feng (1); Yu, Tian-Biao (1); Wang, Wan-Shan (1) 2006, 27 (5):  544-547.  DOI: - Abstract ( 310 )   HTML   PDF (954KB) ( 645 )   Investigates the production mode available to individualize the customized products, then puts forward an individualized customization system framework that is oriented toward networked manufacturing under the production of small batch even single piece, with the operation procedure of the system analyzed. In the system, Bayesian method is introduced to infer what state the design of a product is in when it is doing jointly by a client, designer and technologist at different places according to the prior knowledge they have grasped and relevant statistics. Java3D is used as a 3D display technique to generate 3D objects driven by design parameters input by client. The system software is developed by Java language according to the system transplantability and supporting network communication. Through such a system, clients and designers can customize jointly the products to meet customers' requirements. References | Related Articles | Metrics

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Role delegation authorization model for CSCD system Xu, Hong-Xue (1); Liu, Yong-Xian (1); Guo, Xiu-Ying (2); Sheng, Zhong-Qi (1) 2006, 27 (5):  548-551.  DOI: - Abstract ( 203 )   HTML   PDF (155KB) ( 583 )   According to the definite characteristics of the computer-supported cooperative design (CSCD) system, the characteristics of role delegation authorization (RDA) were analyzed and deduced, and a set of fitful status was found out. Because of the diversified characteristics of RDA features in different systems, the RDA model has multi-varying status. Introducing the basic model of role-based access control (RBAC), some basic characteristics of RDA was summed up. Then, the characteristics of RDA were recombined together according to the definite characteristics of CSCD system to develop a RDA model that is adaptable to CSCD system and different from the conventional role authorization models of RBAC, i.e., takes up the decentralized authorization management instead of centralized one in CSCD system to make it more flexible. This RDA model is verified through a CSCD example. References | Related Articles | Metrics

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Numerical simulation on dynamic rock spalling Zhu, Wan-Cheng (1); Pang, Ming-Zhang (1); Huang, Zhi-Ping (1); Tang, Chun-An (1) 2006, 27 (5):  552-555.  DOI: - Abstract ( 338 )   HTML   PDF (1333KB) ( 675 )   The capability and principle of the software RFPA (rock failure process analysis) to simulate dynamic failure of rock are briefly summarized, and then RFPA is used to study the spalling of rock specimens under dynamic loadings. The capability of RFPA in simulating the dynamic rock spalling is validated by reproducing the different spalling characteristics of homogeneous bar under the stress waves with different amplitudes and by comparing it with theoretical and experimental results. Then, RFPA is used to simulate the spalling failure process of heterogeneous rock specimens subjected to stress waves with different amplitudes and three failure patterns are numerically predicted. In addition, the dynamic failure strengths of rock specimens under such stress waves are also numerically predicted and show higher values than the static tensile strength, which actually indicates that the heterogeneity is one of factors that lead to the increase in dynamic strength of rock. References | Related Articles | Metrics

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Numerical simulation of mechanical-electrical relationship in failure process of graphite concrete Wu, Xian (1); Wu, Bo (2); Qin, Gui-Juan (3); Tang, Chun-An (1) 2006, 27 (5):  556-558.  DOI: - Abstract ( 254 )   HTML   PDF (845KB) ( 1029 )   An analogue between mechanical and electrical fields of conductible graphite concrete was done through numerical simulation to investigate the whole failure process of uniaxial compression members by use of the numerical code software MFPA (material failure process analysis). The concrete is regarded as a composite material made from cement mortar matrix and coarse aggregate. The whole process simulated includes the loading conditions and deformation of members, formation/propagation of their internal cracks and how they finally come to failure, from which the mechanical field of uniaxial compression model of graphite concrete is worked out with the same size of real concrete members. Then, the analogous relationship between mechanical and electrical quantities is obtained according to the curves of measured secant modulus-strain and conductivity-strain, thus converting the mechanical field into electrical field. It is a new way to get the electrical relationship of conductible concrete and will provide a new approach to safety monitoring for structures. References | Related Articles | Metrics

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Numerical simulation and analysis of deformation and failure of jointed rock slopes by RFPA-slope Li, Lian-Chong (1); Tang, Chun-An (1); Xing, Jun (1); Tang, Lie-Xian (1) 2006, 27 (5):  559-562.  DOI: - Abstract ( 341 )   HTML   PDF (1296KB) ( 786 )   The stability analysis of jointed rock slope was conducted by using the software RFPA-Slope that is incorporated with strength reduction theory. The failure surface of slope and relevant safety factor were thus displayed directly. The influences of joint connectivity, location, obliquity and rock bridge length on the failure mode and magnitude of safety factor were investigated. It was proved that the joints were the major influencing factor on the failure mode of jointed rock slope. In addition, the failure process as shown by RFPA-Slope is significantly meaningful for the investigation of failure mechanism of jointed rock slope. The case study indicates that RFPA-Slope can rather rationally predict both safety factor of slope and the corresponding shape and position of the potential slip surface. Accordingly, practical applicability of the proposed technique to complicated cases is verified. References | Related Articles | Metrics

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Application of support vector regression in rock and soil engineering Yang, Cheng-Xiang (1); Feng, Xia-Ting (1) 2006, 27 (5):  563-566.  DOI: - Abstract ( 278 )   HTML   PDF (180KB) ( 776 )   For the extremely complex relationships among influencing factors in geotechnical engineering, the support vector machine (SVM) was introduced in and the basic algorithm of support vector regression (SVR) was presented for complex geotechnical system modeling predicting in practical applications. The powerful capabilities of SVR for efficient self-learning over, small data sets and solving highly nonlinear problems were illustrated with an estimation of structural response to the mining-induced blast vibration of structures around a mine. The satisfactory results showed that the method proposed provides a feasible and promising alternative to deal with the complexities in geotechnical engineering. In addition, some experiments were performed to examine the sensitivity of parameter selection in SVR, with some important conclusion and advice obtained for further applications. References | Related Articles | Metrics

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Behavior of tendon profile and distribution of prestressed internal load Zhang, Dao-Ming (1); Liang, Li (1); Li, Ming (1) 2006, 27 (5):  567-570.  DOI: - Abstract ( 341 )   HTML   PDF (1297KB) ( 740 )   A cubical spline interpolation function is put forward to show the tendon profile of prestressed bars because the tendon profile can't be accurately expressed by the quadric parabola. With the cubical spline, the spatial location of tendon's inflexion and the way to calculate prestressed internal load are both given theoretically and the nonlinear distribution of prestressed internal load is revealed. In addition, two samples of prestressed RC frames of single floor and span are tested with a numerical simulation done by ANSYS. The results of experiments and numerical simulation are very near. Thus, a conclusion is drawn that the tendon profile shows a cubical spline interpolation curve and that the prestressed internal load is distributed nonlinearly. References | Related Articles | Metrics

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Nonlinear analysis of flexural members of steel reinforced high-strength concrete Mu, Guang-Bo (1); Wang, Lian-Guang (1) 2006, 27 (5):  571-574.  DOI: - Abstract ( 250 )   HTML   PDF (948KB) ( 584 )   To investigate further the working performance of flexural members of steel-reinforced high-strength concrete under monotonic loading, a full-range nonlinear analysis is made through the finite ribbon method based on flat section assumption. By computation, the moment-curvature and load-deformation relationships are obtained, as well as those among concrete strength, volumetric percentage of steel, load and deformation of a flexural member. It is obvious that a concrete member cracks in tensional area as the external load comes to 14% of its ultimate load or so. On the same loading condition the ductility of the member is less than that of conventional steel-reinforced concrete members. However, on the same deformation condition, the bearing capacity of the flexural members of steel-reinforced high-strength concrete increase obviously with the increasing volumetric percentage of steel. References | Related Articles | Metrics

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On the algorithm for VRPBTW (vehicle routing problem with backhauls and time windows) Guo, Fu (1); Long, Ying (1) 2006, 27 (5):  575-578.  DOI: - Abstract ( 563 )   HTML   PDF (106KB) ( 1884 )   Taking backhaul into consideration in the haul process, the vehicle routing problem with time windows (VRPTW) becomes the vehicle routing problem with backhaul and time windows (VRPBTW), which is more practical than normal VRPTW. The new problem VRPBTW is therefore proposed to improve the VRPTW so as to get rid of the limitation of haul/backhaul sequence by designing some parameters corresponding to the sequence and available to avoid its rescheduling. Furthermore, the costs of vehicle running, handling/waiting time and other services are all taken into account in defining the objectives, thus providing a definite solution to those objectives. According to the features of the problem, an algorithm is proposed for VRPBTW, of which the routing is feasibly determined via the branch and bound and genetic algorithm and then a solution is given by use of integral programming. An instance is given to prove its validity. References | Related Articles | Metrics

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Cooperation/transshipment discussion based on multiple newsboy model Zhong, Lei-Gang (1); Lin, Lin (1); Liu, Xiao-Qin (1); Zhang, Cui-Hua (1) 2006, 27 (5):  579-582.  DOI: - Abstract ( 292 )   HTML   PDF (226KB) ( 997 )   Discusses the cooperation in a transshipment alliance consisting of n retailers. Assuming that each of them is facing to a market demand that is attributed to the multiple newsboy problem, i.e., the commodities that are wanted to be sold out are all of perishable goods with short shelf-life, the alliance organized by those retailers can make more profits they jointly expect through negotiatory orders and cooperative transshipments. Based on the multiple newsboy model and analyzing the case of n retailers who are co-ordinating their efforts in their joint orders and associated reallocation, a cooperative game is defined as 'general newsboy game' of which the features and their effects on the corresponding cooperative alliance are discussed. A conclusion is thus drawn that all the general newsboy games have a nonempty core and an alliance based on cooperation enables each and every retailer to make more profits expected. References | Related Articles | Metrics

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Dual-channel model on e-market and H∞ control strategies for its bullwhip effect Yan, Ni-Na (1); Huang, Xiao-Yuan (1) 2006, 27 (5):  583-586.  DOI: - Abstract ( 273 )   HTML   PDF (187KB) ( 851 )   An inventory control model of the dual-channel on e-market is developed including the dynamic controlling process for both Internet and traditional channels, where the inventory level is a state variable and the product output and supply are controlling variables. Describing quantitatively the bullwhip effect of the dual-channel and analyzing its control mechanism, an H∞ control strategy is proposed according to control theories to control the bullwhip effect when the demand's disturbance is worst. Combining with the practices of e-business in Shanghai Baosteel Yichang Co., a simulating calculation is done to analyze the bullwhip effect, which verifies the controlling effect of H∞ control algorithm for the dual-channelon e-market. References | Related Articles | Metrics

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- - 2006, 27 (5):  587-590.  DOI: - Abstract ( 287 )   HTML   PDF (1862KB) ( 674 )   - References | Related Articles | Metrics