Lacking timely access to rescue resources is one of the main causes of casualties in tunnel collapse.To provide timely rescue,this study proposed a multi-objective preallocation model of special emergency resources fo...Lacking timely access to rescue resources is one of the main causes of casualties in tunnel collapse.To provide timely rescue,this study proposed a multi-objective preallocation model of special emergency resources for tunnel collapse based on demand time.Efficiency,multiple coverage,and cost-effectiveness are taken as the key objectives of the model;the demand time service range is used as a coverage decision factor considering the unique nature of tunnel collapse.The weight of potential disaster-affected points and other general factors are also considered in this model in order to thoroughly combine the distribution of disaster points and service areas.Further,we take 15 main tunnel projects under construction in China as an example.When the relative proximity to the ideal point of the selected optimal schemeε_(a)is smaller than 0.5,we will adjust the weight of three objectives and reselect the optimal scheme untilε_(a)>0.5.Compared with the not preallocated case,the number of rescue rigs needed is reduced by 8.3%,the number of covered potential disaster-affected points is increased by 36.36%,the weighted coverage times are increased from 0.853 to 1.383,and the weighted distance is significantly reduced by 99%when the rescue rigs are preallocated,verifying the feasibility and superiority of the proposed model.展开更多
This article proposed a new handover algorithm for beyond the third generation （B3G） systems with an orthogonal frequency division multiple access （OFDMA） downlink. In the proposed algorithm, handover mobile termi...This article proposed a new handover algorithm for beyond the third generation （B3G） systems with an orthogonal frequency division multiple access （OFDMA） downlink. In the proposed algorithm, handover mobile termination （MT） chooses a subchannel set in the candidate cells by a subchannel booking rule, based on the terminal speed and the subchannel＇s channel state information （CSI）. Moreover, the handover decision is made after analyzing if at least one candidate cell can reserve the subchannel set for the handover user. Simulation results show that the algorithm reduces the number of handovers and guarantees the quality of service （QoS） for the handover users. It yields better system performance in the OFDMA systems.展开更多
基金supported by the funding provided by the National Natural Science Foundation of China(Grant no.51908187)。
文摘Lacking timely access to rescue resources is one of the main causes of casualties in tunnel collapse.To provide timely rescue,this study proposed a multi-objective preallocation model of special emergency resources for tunnel collapse based on demand time.Efficiency,multiple coverage,and cost-effectiveness are taken as the key objectives of the model;the demand time service range is used as a coverage decision factor considering the unique nature of tunnel collapse.The weight of potential disaster-affected points and other general factors are also considered in this model in order to thoroughly combine the distribution of disaster points and service areas.Further,we take 15 main tunnel projects under construction in China as an example.When the relative proximity to the ideal point of the selected optimal schemeε_(a)is smaller than 0.5,we will adjust the weight of three objectives and reselect the optimal scheme untilε_(a)>0.5.Compared with the not preallocated case,the number of rescue rigs needed is reduced by 8.3%,the number of covered potential disaster-affected points is increased by 36.36%,the weighted coverage times are increased from 0.853 to 1.383,and the weighted distance is significantly reduced by 99%when the rescue rigs are preallocated,verifying the feasibility and superiority of the proposed model.
基金the National Natural Science Foundation of China（60496312）the Hi-TechResearch and Development Program of China（2006AA012260）and Huawei Company.
文摘This article proposed a new handover algorithm for beyond the third generation （B3G） systems with an orthogonal frequency division multiple access （OFDMA） downlink. In the proposed algorithm, handover mobile termination （MT） chooses a subchannel set in the candidate cells by a subchannel booking rule, based on the terminal speed and the subchannel＇s channel state information （CSI）. Moreover, the handover decision is made after analyzing if at least one candidate cell can reserve the subchannel set for the handover user. Simulation results show that the algorithm reduces the number of handovers and guarantees the quality of service （QoS） for the handover users. It yields better system performance in the OFDMA systems.
