2007 Vol. 7, No. 4

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Dynamic property analysis of axle shaft of high-speed train
Mi Cai-ying, An Qi, Li Fu
Abstract: Wheel and axle box were simplified to collective quality and inertia of moment, non-uniform axle shaft was simulated by using continuous elastic Timoshenko beam, an elastic wheelset/rail coupling vertical dynamics model was set up, and the relationships between the dynamic stiffness of axle shaft and wheel/track dynamic force, the vibratory characteristics and dynamic stress of axle shaft were analyzed. It is pointed that when the first natural frequency of wheelset reduces from 76.34 Hz to 53.68 Hz and the second natural frequency reduces from 130.03 Hz to 100.02 Hz, the first mode vibration acceleration and elastic vibration displacement of axle shaft increases by 60.12% and 92.91% respectively, wheel/track dynamic force increases by 6.23%, the dynamic stresses on the dangerous section inside wheel seat and on axle neck respectively increase by 39.30% and 34.13%. Analysis result shows that the dynamic force of wheelset and the dynamic stress of axle shaft increase with the dynamic stiffness decrease of axle shaft, so raising the dynamic stiffness of light wheelset can ensure the running safety of high-speed train and enhance the fatigue intensity of axle shaft.More>
2007, 7(4): 1-5.
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Influence of strong crosswind on aerodynamic performance of passenger train running on embankment
Zhou Dan, Tian Hong-qi, Lu Zhai-jun
Abstract: In order to improve the running stability of passenger train in strong crosswind, its running condition on embankment while suffering from strong crosswind was simulated by using 3-D unsteady N-S equations and dynamic mesh technique, the relationships between aerodynamic force and train speed, crosswind speed and embankment tallness, and simulation result was compared with tunnel test result. It is found that their results are accordant, aerodynamic side force increases large with the increase of embankment height when embankment height is less than 20.00 m, but it decreases with the increase of embankment height when embankment height is larger than 20.00 m; aerodynamic force and overturning moment rapidly increase with the speed increase of crosswind when the running speed of passenger train is certain; in the condition that the speed of crosswind is certain, aerodynamic force, lift force and overturning moment increase less when train speed change from 60 km·h-1 to 120 km·h-1.More>
2007, 7(4): 6-9.
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Visual simulation of vehicle-track coupling dynamics system
Yang Ji-zhong, Zhai Wan-ming, Su Hu
Abstract: In order to improve the visual simulation fidelity of wheel-rail coupling dynamics system, wheel contact profile was calculated by using trace-line method, the dynamic contact relation of wheel-rail was displayed by using planar way, rail was regareed as beam to participate in vibration, and rail vibration behavior was simulated through building real-time rail model with vertical, lateral and torsional shapes.Simulation result shows that the simulation system is feasible, the real-time motion regulation of wheel-rail contact point is clearly observed, intricate visual point transformation is avoided in 3-D scene, wheel-rail contact relation is more succinct, and the simulation of rail vibration behavior is more realistic by building real-time rail model.More>
2007, 7(4): 10-14.
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Analysis of parameters' effects on settlement of ballasted track
Gao Jian-min, Zhai Wan-ming, Xu Yong
Abstract: In order to comprehend the occurring and growing mechanism of track settlement, ballast bed settlement was regarded as study object, and the effects of transportation conditions and track structure parameters on ballast settlement were analyzed by using simulation analysis program based on vehicle-track coupling dynamics and track settlement laws. Analysis result shows that vehicle running speed, vehicle axle load and railway traffic are main control factors of track settlement; it benefits to decrease ballast settlement by adopting heavy rail, big size sleeper and high density ballast; big sleeper space and high ballast elastic modulus are disadvantageous to control ballast settlement; the effect of subgrade modulus K30 is complex, ballast settlement increases with the increase of K30 when K30 is less than 90 MPa·m-1, ballast settlement reduces with the increase of K30 when K30 is more than 90 MPa·m-1. Obviously, in order to decrease track settlement, it is important to match track structure parameters and arrange transportation reasonably.More>
2007, 7(4): 15-20.
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Diagnosis method of instantaneous frequency for rotor impact-rub fault of aeroengine
Zhang Zhi-yu, Lu Yan-jun, Zhang Jiu-long, Qin Wei-yang
Abstract: The basal characteristics of impact-rub fault signal for aeroengine rotor were analyzed, and a fault diagnosis method based on the instantaneous frequency of the fault signal was presented. The fault signal was transformed into wavelet domain by using wavelet transform, the instantaneous frequencies were extracted by using the amplitude and phase of wavelet coefficients, the fault was diagnosed by using the characteristics of the instantaneous frequencies, and the diagnosis results of the fault signal gained by using the proposed method and windowed Fourier transform were compared. Comparison result shows that the instantaneous frequency gained by using the proposed method is more precise and comprehensive.More>
2007, 7(4): 21-23.
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Berthing controller of underactuated ship with nonlinear sliding mode
Bu Ren-xiang, Liu Zheng-jiang, Hu Jiang-qiang
Abstract: In order to accurately control typical berthing steering, a dynamic output feedback controller was designed for the automatic berthing of underactuated surface ship with nonholonomic acceleration constraints. The control problems of path planning and following were transformed into the static control problem of scalar zero-order-systems by means of iterative sliding mode control (ISMC), in which nonlinear sliding surfaces were recursively and iteratively designed in augmented state space. Integrating with increment feedback, the controller was proved to stabilize ship's motion in typical berthing steering without estimating systemic uncertainties and the disturbances resulted from current and wind. Numerical simulation result shows that the controller is strongly robust to the variation of the disturbances, and ship's planar trajectory is adjusted by using only one variable due to its simple design procedure.More>
2007, 7(4): 24-29.
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Prediction method of ship impacting bridge based on least square support vector machines
Luo Wei-lin, Zou Zao-jian
Abstract: In order to improve the safety of bridge and ship, an intelligent prediction method of the probability on ship impacting bridge was proposed based on least square support vector machines.The transverse span of piers, current velocity, current direction relative to bridge and waterway curvature were taken as the inputs of the method, while the output is the accident probability of pervoyage, some data samples of 12 bridges over Yangtze River and Heilongjiang River during the periods of flood, normal and low water respectively were chosen, the method was validated by the data, and the prediction results of neural network method and the proposed method were compared.Comparison result shows that the method can accurately predict the probability of ship impacting bridge, its prediction probability is a globally optimal resolution, and its convergent velocity and learning efficiency are better than that of neural network method.More>
2007, 7(4): 30-33.
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Evaluation and decision-making model of waterway net planning based on DEA method
Zhu Jun, Zhang Wei, Yu Jing
Abstract: In order to effectively and objectively evaluate the planning projects of waterway net, the index system of the projects were analyzed by using data envelopment analysis(DEA)method, a new evaluation and decision-making model of waterway net planning was developed, its output indices and input indices were ascertained, and it was solved by using linear programming principium.Computation result shows that the validities of the projects is not only adjusted, but also evaluated and classified by using the model, so that the optimal project is chosen in effective projects; ineffective schemes can be improved into effective schemes by using the model, but their output values are invariant, so the model is scientific and rational, and benefit the planning and management of waterway net.3 tabs, 1 fig, 12 refs.More>
2007, 7(4): 34-38.
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Analysis method of vehicle vibration response caused by pavement roughness
Song Yi-fan, Chen Rong-feng
Abstract: In order to analyze the interaction of pavement and vehicle, an analysis method of couple vibration between 1/2-four-degree vehicle model and rough pavement was proposed.According to the power spectral density function advised by GB/T 7031-1986, the effect of the vehicle natural vibration frequency and velocity was studied, the discrete data of power spectral density within definite frequency range were obtained, the value of pavement roughness was obtained by Fourier reverse transform. The samples were taken as the input disturbances of a 1/2 vehicle vertical dynamics model, and the time-domain response of vehicle system caused by pavement roughness was obtained by numerical simulation. Analysis result shows that the value of dynamic load coefficient increases linearly along with the increase of vehicle velocity, but non-linearly along with the grade increase of pavement roughness, and the grade of pavement roughness is most marked factor of vehicle dynamic effect.More>
2007, 7(4): 39-43.
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Numerical analysis of dynamic response on asphalt pavement
Luo Hui, Zhu Hong-ping, Hao Xing-zhou
Abstract: In order to optimize the structural design of asphalt pavement, non-reflective boundary was introduced, structural dynamics theory was adopted, its dynamic responses under moving loads were analyzed by using finite element method. It is pointed that tensile stress and surface deflection decrease with the increases of base course modulus, friction coefficient, vehicle velocity and surface course damping, but the shear stress ascends with the raises of tire pressure and base course modulus. Analysis result shows that it is not appropriate to simply increase base course modulus and thickness, the base design should be optimized synthetically; good contacting condition and great damping material lead to fine pavement performance; the velocity increase of vehicle can extend pavement service life.More>
2007, 7(4): 44-47.
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Transform domain analysis of rigid pavement dynamic strain response
Zhang Wen-bin, Wang Qi, Ma Song-lin, Liu Wei, Li Xin-kai
Abstract: In order to investigate the dynamic strain responses of rigid pavements subjected to moving constant load and harmonic variation load, pavement was regarded as a plate with infinite extent on a viscoelastic foundation, formulations of moving loads were developed in time-space transform domain by using triple Fourier transform, and the effects of viscous damping, vehicle speed and load on the strain were studied. Experiment environment was simulated by using five embedded strain sensors, pavement dynamic strain response was measured, and measure result was compared with simulation result. Comparison result shows that the responses of rigid pavement to vehicle velocity and viscous damping are larger, the response induced by constant load is less than the response induced by harmonic load, and the response induced by harmonic load is a little larger than experimental result.More>
2007, 7(4): 48-53.
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Performance analysis of asphalt and asphalt mixture with Sasobit
Zhang Rui, Huang Xiao-ming
Abstract: In order to evaluate the temperature-lowered effect of Sasobit and its influence on the road performances of asphalt mixture, penetration test and softening point test for asphalt with Sasobit were done, void ratio test, rutting test, bending-beam test and frost thawing and splitting test were done to asphalt mixture samples without Sasobit mixed in normal temperature and with Sasobit mixed in low temperature, and their performances were analyzed. Test result indicates that the high temperature stability of asphalt with Sasobit increases, the changes of the void ratio, crack resistance stability in low temperature and water stability of mixtures with Sasobit are unobvious, but its high temperature stability enhances, it is feasible that the mixing and molding temperatures of asphalt mixture are lowered by using Sasobit.More>
2007, 7(4): 54-57.
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Calculation method of asphalt film thickness in mixture
Hou Yun, Wei Dao-xin, Tian Bo, Liu Yong-xiang
Abstract: In order to accurately compute the asphalt film thickness of asphalt mixture, the particle-size of mineral, the compaction degree of asphalt mixture and asphalt ratio were considered, the particle-size of mineral was measured by using HORIBA-300 instrument, the particle-size distribution of mineral was analyzed, the concept of asphalt separation film was introduced, and a computation model of asphalt film thickness was put forward.The sample of asphalt mixture was molded by using rotary compaction instrument, and the computation values and measure values of asphalt film thickness were compared. Comparison result shows that the asphalt content range of asphalt mixture is from 4.55% to 4.85% with the new method, the range is from 4.20% to 5.20% with conventional method, measured optimal content is 4.70%, obviously, the computation precision of the proposed method is higher.More>
2007, 7(4): 58-62.
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Hybrid genetic optimization method of pavement maintenance decision-making for expressway
Zou Qun, Yu An-jun, Zou Guo-ping
Abstract: In order to improve the efficiency and stability of pavement maintenance decision-making for expressway, reduce the cost of pavement maintenance, the applicabilities of traditional mathematics programming method and genetic algorithm were analyzed, pseudo-parallel tactic, optimum preservation tactic and self-adapted parameter adjustment were introduced, and a hybrid genetic optimization method of pavement maintenance decision-making for expressway was put forward.Simulation result shows that the convergence speed and searching ability of the method were better than that of simple genetic algorithm, the premature convergence of pavement maintenance decision-making was overcome, the optimum allocations of maintenance funds were realized aimed at the multi-projects of pavement maintenance, and the investment is infinite, so the method effectively solves the optimization problem of pavement maintenance decision-making for expressway.3 tabs, 11 refs.More>
2007, 7(4): 63-66.
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Study actuality summary of backfilling materials behind abutments of highway bridge and culvert
Ge Zhe-sheng, Huang Xiao-ming, Zhang Xiao-ning, Gao Jun-he
Abstract: In order to reduce backfilling diseases behind abutments of highway bridge and culvert, the study actualities of backfilling materials and technologies were summarized. Firstly, the main reasons of backfilling diseases were studied from the aspects of abutment construction differences, subsoil settlements and the compression distortions of backfilling materials. Secondly, general backfilling engineering measures and effects were analyzed, such as bridge end transition slab, subsoil treatment, lean concrete backfilling and back-digging, compact grouting and so on. Thirdly, the properties and effects of common backfilling materials were compared, such as lime-soil, sand gravel, neolian sand, argil fly-ash concrete, foamed concrete, geogrid and geosell reinforcement and EPS.Study result shows that local materials should be used in abutment backfilling engineering, existing backfilling materials should be improved and strengthened by new technologies, and it is suggested that the integrated applying technology of EPS interlayer and geogrid reinforcement should be studied, light-weight backfilling materials should be empoldered, so that the bridgehead-jumping disease is prevented, and highway using performance is improved.More>
2007, 7(4): 67-73.
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Simulation experiment about oversize box culvert jacked into highway subgrade
Feng Zhong-ju, Ren Wen-feng, Xie Fu-gui, He Tao, Men Xiao-xiong
Abstract: In order to make oversize box culvert being jacked into highway subgrade smoothly, the actual friction status of box culvert was simulated, box culvert and surrounding soil were simplified for concrete model and soil model respectively, the mutative rules of friction coefficients between concrete and concrete, concrete and soils with different amounts of water were analyzed after and before diminishing fiction resistance, and the pushing force of box culvert was computed according to friction coefficients. It is found that the average coefficient of gliding friction between concretes is 0.31;the mixture of paraffin and engine oil can reduce the friction between concretes obviously, the average friction coefficient is 0.12, and 61% of the previous friction coefficient is reduced; the amount of water in soil body surrounding box culvert greatly influences the friction coefficient between concrete and soil, the bigger the amount of water is, the smaller the friction coefficient is.Simulation result shows that when box culvert is jacked, it is necessary to explore the geological condition surrounding box culvert in order to hold the engineering characteristic of surrounding soil body in hand and give reasonable technology to diminish fiction resistance.More>
2007, 7(4): 74-78.
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Mechanical behavior of prestressed concrete T beam based on mixed shell element method
Zhang Jian, Ye Jian-shu, Zhang Feng, Zou Li-qiong
Abstract: In order to accurately forecast and estimate the mechanical property of prestressed concrete T beam, its finite element model was set up by using mixed shell elements, and the nonlinear process of its mechanical behavior from wholeness to failure was studied. In T beam, curving prestressed steel was simulated with combined shell element model, its contribution to the stiffness matrix of combined shell element was deduced by using virtual principle, and straight prestressed steel was simulated with layered shell element model; the material nonlinear behavior of concrete was considered with Owen yield criterion and Hinton crushing criterion, and the behavior of steel was depicted with bilinear constitutive model. Analysis result indicates that the computational result of the model is close to experimental result, the stiffness degradation coefficient of T beam in nonlinearity phase is much larger than that in elasticity phase, and the most increase of steel stress is at the bottom of mid-span, so mixed shell element method is efficient and proper to analyze the mechanical behavior of prestressed concrete T beam.More>
2007, 7(4): 79-83.
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Optimization designing and solving of signal based on CTM
Wang Zheng-wu, Luo Da-yong, Huang Zhong-xiang
Abstract: In order to effectively control traffic flow, and synchronously optimize phase, period and green time at intersection, cell transmission model(CTM)and bi-level programming method were studied, and a signal optimization method was proposed. A CTM of entrance traffic flow at intersection was built by modifying cell partition and its state expression, and a bi-level programming method was designed, whose upper programming was to optimize phase scheme, while lower programming was to optimize period and green time. After lower programming was translated by using precision penalty method, an solving algorithm integrated genetic algorithm and chaos optimization algorithm was put forward. Applied result shows that the algorithm not only averts the invalidation problem of chaos optimization algorithm in a large scale, but also increases the local search ability and search precision of genetic algorithm; the method is feasible, the total delay is 270.2 pcu·h, and it is reduced by 5.6% compared with induction control with fixed phases.More>
2007, 7(4): 84-88.
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Stability analysis of vehicle following system with delays based on vector Liapunov function
Ren Dian-bo, Zhang Ji-ye, Sun Lin-fu
Abstract: In order to study the stability of longitudinal following control system of vehicle in automated highway system, the following errors of vehicles were analyzed, a mathematic model of infinite-dimensional nonlinear interconnected large-scale system with delays was constructed, and the stability of the system was studied by applying vector Liapunov function. Under the assumption that the system satisfied holistic Lipschitz condition, the stability conditions of isolated subsystems decomposed from the large-scale system were regarded as base, and a sufficient condition of exponential stability on the large-scale system was obtained.Since the criterion is explicit and independent of the delays, it is easy to be applied in the design of longitudinal vehicle following controllers.More>
2007, 7(4): 89-92.
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Causes and preventive technologies of traffic congestion shift
Jiang Gui-yan, Zheng Zu-duo, Bai Zhu, Zhao Jia-qi, Dai Lei-lei
Abstract: In order to study the influence of traffic guidance information on driver's behavior, the causes of traffic congestion shift under real-time guidance were analyzed from the aspects of guidance proportion, the number of alternative routes, the rationality of alternative route and the traffic distribution of road network, three methods were proposed to prevent from congestion shift, which included escalating guidance proportion, adding disturbance to linkcost data and providing K alternative routes to driver, and the methods were evaluated and compared by using traffic simulation software named Vissim.Simulation result shows that in a road network with local congestions, the methods have the ability to alleviate or eliminate congestion shift, the performance of providing K alternative routes is the best; the performance of escalating guidance proportion is the second; although the performance of adding disturbance to linkcost data is the third, it is much better than the conditions of completely guiding driver and adopting no guiding measurement.More>
2007, 7(4): 93-97.
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Layout planning method for urban passenger intermodal transfer points in cluster cities
Lu Shen, Tian Feng, Li Xu-hong
Abstract: In order to adapt the layout of urban passenger intermodal transfer points(UPITP)to the property of urban land use in Chinese big cities, the relationship between the layout and urban land use, passenger demand corridor and traffic network was analyzed, and a planning method of macroscopic layout and microcosmic location was presented.In macroscopic layout, the overlay zone of UPITP was selected based on the fundamental of transit-oriented development(TOD). In microcosmic location, the transfer efficiency of denizen was regarded as aim, the land use function, average floor area ratio and the distance between the UPTIP and passenger demand corridor were regarded as constraints, and a nonlinear programming model was developed to ascertain the favorable position of the UPITP. Applied result shows that the site zone of UPITP is consistent with that of the layout method of urban land use with multi-center and cluster cities, the number of service population and employment within 500 m radius of the favorable position is highest, and the method reflects the interaction relation between UPITP and urban land use.More>
2007, 7(4): 98-103.
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Computation model of safety level of service for non-signalized intersection
Pan Fu-quan, Lu Jian, Xiang Qiao-jun, Zhang Guo-qiang
Abstract: In order to objectively evaluate the traffic safety performance of non-signalized intersection, the safety level concept of service for intersection was put forward, the influences of objective factors on the safety level of service were analyzed, its evaluation project was given, its main model was build based on the conflict points of power-driven vehicles, non-power-driven vehicles and pedestrians, its correctional model was set up according to minor influencing factors, such as intersection geometry property, traffic signs, etc, and its total model was put forward based on the two models. In order to validate the rationality of the total model, safety level of service was divided into one to four levels according to the data of many intersections. Validated result shows that the risk index value of real intersection is 200.7, its safety level of service is third level, which accords with its real condition, so the model can effectively evaluate the safety of non-signalized intersection.More>
2007, 7(4): 104-111.
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Prediction model of death toll resulted from road traffic accidents
Yuan Wei, Fu Rui, Guo Ying-shi, Han Wen-li
Abstract: In order to scientifically predict the future traffic safety situation in China, a prediction model of traffic accident death toll was built based on the analysis of evaluation indices and main influence factors of Chinese road traffic safety situation, which several factors were taken as parameters, including motor vehicle amount, population, highway mileage, passengers and goods transport volume, and government policy. According to the model, the annual death toll from 1991 to 2004 was calculated, and the future death toll was predicted.Prediction result shows that the precision of the model is higher, the average predicting error is 3.9%;the predicting values of accident death toll in 2010 and 2020 are 14 ten thousand people and 17 ten thousand people respectively; the turning time is during 2010 to 2015 when the death toll changes from rising to descending.More>
2007, 7(4): 112-116.
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Client's decision-making behavior and redistribution of freight flow in affiliated market
Fang Xiao-ping
Abstract: According to the hypothesis that client is rational decision-maker in classic decision theory, the generalized circulating cost model and generalized purchasing cost model of freight, the affiliated degree model among different transportation modes and the sensitive model of generalized purchasing cost relative to transportation price and transportation time were build, and the properties and influence factors of client's decision-making behavior and the redistribution of freight flow were analyzed in affiliated freight market. It is pointed that different modes might produce different generalized circulating transport costs aimed at the same amount freight, client chooses transport model according to generalized circulating cost; when the affiliated degree between two kinds of transportation modes is close to 1, competition increasingly becomes fierce in affiliated freight market; the elasticity coefficients of generalized purchasing cost relative to transportation price and transportation time respectively equal to the ratios of the transport fee and on-way time cost of freight to generalized purchasing cost, the time cost of goods relatively remains stable, so the decision-making behavior of client and the distribution of freight flow are decided by goods attribute and transport technique.More>
2007, 7(4): 117-120.
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Virtual layout method of distribution center of logistics based on simulation
Cheng Ri-sheng, Zhang Yong, Xiang Lu-zhou, Li Xu-hong, Mao Hai-jun
Abstract: In order to improve the layout objectivity of distribution center of logistics and running efficiency of logistics, decrease the disposal cost of logistics, the layout shortcomings of traditional distribution centers of logistics were analyzed, the effects of all kinds of stochastic factors on the layout of distribution center of logistics were studied, and a virtual simulation design method was put forward.According to the coordinated real parameters of the layout, the scale, running processes and planar layout of the center were confirmed, its design schemes were proposed, its running processes were simulated, its spatial efficiency, working capability, running efficiency and running cost were computed, and the schemes were evaluated.Applied result shows that the precision of the method is high, the optimized scheme by using the method accords with real condition.More>
2007, 7(4): 121-126.
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