Running safety assessment and tracking irregularity parametric sensitivity analysis of high-speed maglev train-bridge system are of great concern,especially need perfect refinement models in which all properties can b...Running safety assessment and tracking irregularity parametric sensitivity analysis of high-speed maglev train-bridge system are of great concern,especially need perfect refinement models in which all properties can be well characterized based on various stochastic excitations.A three-dimensional refined spatial random vibration analysis model of high-speed maglev train-bridge coupled system is established in this paper,in which multi-source uncertainty excitation can be considered simultaneously,and the probability density evolution method(PDEM)is adopted to reveal the system-specific uncertainty dynamic characteristic.The motion equation of the maglev vehicle model is composed of multi-rigid bodies with a total 210-degrees of freedom for each vehicle,and a refined electromagnetic force-air gap model is used to account for the interaction and coupling effect between the moving train and track beam bridges,which are directly established by using finite element method.The model is proven to be applicable by comparing with Monte Carlo simulation.By applying the proposed stochastic framework to the high maglev line,the random dynamic responses of maglev vehicles running on the bridges are studied for running safety and stability assessment.Moreover,the effects of track irregularity wavelength range under different amplitude and running speeds on the coupled system are investigated.The results show that the augmentation of train speed will move backward the sensitive wavelength interval,and track irregularity amplitude influences the response remarkably in the sensitive interval.展开更多
Based on the characteristics of the air alliance environment saving transport mileage,the hub location problem of the air cargo network was studied.First,the air alliance selection probability model was introduced to ...Based on the characteristics of the air alliance environment saving transport mileage,the hub location problem of the air cargo network was studied.First,the air alliance selection probability model was introduced to determine the alliance self-operation or outsourcing probability in different segments.Then,according to the location center rule,with the goal of minimizing the total cost,the hub location model was built.The improved immune chaos genetic algorithm was used to solve this model.The results show that the improved algorithm has stronger convergence and better effect than the immune genetic algorithm.When the number of hubs increases,the fixed cost increases,but the transportation cost decreases.The greater the discount factor,the fixed cost,and the self operating cost sharing coefficient,the higher the total network cost.The airline which joins the air alliance can greatly reduce the operating cost of airlines.Therefore,airlines should consider joining the alliance.展开更多
The time-dependent solution of reduced air-sea coupling stochastic-dynamicmodel is accurately obtained by using the Fokker-Planck equation and the quantum mechanical method.The analysis of the time-dependent solution ...The time-dependent solution of reduced air-sea coupling stochastic-dynamicmodel is accurately obtained by using the Fokker-Planck equation and the quantum mechanical method.The analysis of the time-dependent solution suggests that when the climate system is in the groundstate, the behavior of the system appears to be a Brownian movement, thus reasoning the foothold ofHasselmann's stochastic climatic model; when the system is in the first excitation state, the motionof the system exhibits a form of time-decaying, or under certain condition a periodic oscillationwith the main period being 2.3 yr. At last, the results are used to discuss the impact of thedoubling of carbon dioxide on climate.展开更多
基金Project(2023YFB4302500)supported by the National Key R&D Program of ChinaProject(52078485)supported by the National Natural Science Foundation of ChinaProjects(2021-Major-16,2021-Special-08)supported by the Science and Technology Research and Development Program Project of China Railway Group Limited。
文摘Running safety assessment and tracking irregularity parametric sensitivity analysis of high-speed maglev train-bridge system are of great concern,especially need perfect refinement models in which all properties can be well characterized based on various stochastic excitations.A three-dimensional refined spatial random vibration analysis model of high-speed maglev train-bridge coupled system is established in this paper,in which multi-source uncertainty excitation can be considered simultaneously,and the probability density evolution method(PDEM)is adopted to reveal the system-specific uncertainty dynamic characteristic.The motion equation of the maglev vehicle model is composed of multi-rigid bodies with a total 210-degrees of freedom for each vehicle,and a refined electromagnetic force-air gap model is used to account for the interaction and coupling effect between the moving train and track beam bridges,which are directly established by using finite element method.The model is proven to be applicable by comparing with Monte Carlo simulation.By applying the proposed stochastic framework to the high maglev line,the random dynamic responses of maglev vehicles running on the bridges are studied for running safety and stability assessment.Moreover,the effects of track irregularity wavelength range under different amplitude and running speeds on the coupled system are investigated.The results show that the augmentation of train speed will move backward the sensitive wavelength interval,and track irregularity amplitude influences the response remarkably in the sensitive interval.
基金The National Social Science Foundation of China(No.17XGL013)。
文摘Based on the characteristics of the air alliance environment saving transport mileage,the hub location problem of the air cargo network was studied.First,the air alliance selection probability model was introduced to determine the alliance self-operation or outsourcing probability in different segments.Then,according to the location center rule,with the goal of minimizing the total cost,the hub location model was built.The improved immune chaos genetic algorithm was used to solve this model.The results show that the improved algorithm has stronger convergence and better effect than the immune genetic algorithm.When the number of hubs increases,the fixed cost increases,but the transportation cost decreases.The greater the discount factor,the fixed cost,and the self operating cost sharing coefficient,the higher the total network cost.The airline which joins the air alliance can greatly reduce the operating cost of airlines.Therefore,airlines should consider joining the alliance.
基金Project supported jointly by the National Natural Science Foundation of China under Grant Nos. 40275031 and 40231006 andthe State Key Development Program for Basic Research of China under Grant No. 2006CB400503.
文摘The time-dependent solution of reduced air-sea coupling stochastic-dynamicmodel is accurately obtained by using the Fokker-Planck equation and the quantum mechanical method.The analysis of the time-dependent solution suggests that when the climate system is in the groundstate, the behavior of the system appears to be a Brownian movement, thus reasoning the foothold ofHasselmann's stochastic climatic model; when the system is in the first excitation state, the motionof the system exhibits a form of time-decaying, or under certain condition a periodic oscillationwith the main period being 2.3 yr. At last, the results are used to discuss the impact of thedoubling of carbon dioxide on climate.
