Support vehicles are part of the main body of airport ground operations,and their scheduling efficiency directly impacts flight delays.A mathematical model is constructed and the responsiveness of support vehicles for...Support vehicles are part of the main body of airport ground operations,and their scheduling efficiency directly impacts flight delays.A mathematical model is constructed and the responsiveness of support vehicles for current operational demands is proposed to study optimization algorithms for vehicle scheduling.The model is based on the constraint relationship of the initial operation time,time window,and gate position distribution,which gives an improvement to the ant colony algorithm(ACO).The impacts of the improved ACO as used for support vehicle optimization are compared and analyzed.The results show that the scheduling scheme of refueling trucks based on the improved ACO can reduce flight delays caused by refueling operations by 56.87%,indicating the improved ACO can improve support vehicle scheduling.Besides,the improved ACO can jump out of local optima,which can balance the working time of refueling trucks.This research optimizes the scheduling scheme of support vehicles under the existing conditions of airports,which has practical significance to fully utilize ground service resources,improve the efficiency of airport ground operations,and effectively reduce flight delays caused by ground service support.展开更多
In 2000, the United Nations (UN) developed Millennium Development Goals (MDG) with one of its aim being to improve access of potable water supply by 2015 in developing countries. This study thus focused on Kenya’s Gi...In 2000, the United Nations (UN) developed Millennium Development Goals (MDG) with one of its aim being to improve access of potable water supply by 2015 in developing countries. This study thus focused on Kenya’s Gilgil constituency which lies in both arid and semi-arid zones and experiences bimodal rains which are neither heavy nor reliable. With persistent shortages, water management and monitoring became essential and in current times the use of Geographic Information Systems (GIS) is being incorporated due to its capability as an effective tool in water resources management. The study’s aim was to provide knowledge about accessible areas and gaps using cost surface analysis as well as identify other factors that influence settlement. The study utilized walk speeds as an impedance to determine cost surfaces followed by creation of service areas from water facilities using time as a measurement of access. The study established that surface friction may not have major influence on accessibility and service areas while logistic regression established that other factors strongly influence settlement apart from water availability. The study also reveals that 77% of the semi-permanent households in Gilgil have a hard time accessing water as they are outside the 30-minute walk time.展开更多
为保证城市轨道交通运营安全,迫切需要整合车地无线通信生产业务的承载需求,建立基于城市轨道交通专用无线频段的车地通信系统。利用我国自主知识产权的TD-LTE(time division long term evolution,分时长期演进)技术,设计出基于LTE(long...为保证城市轨道交通运营安全,迫切需要整合车地无线通信生产业务的承载需求,建立基于城市轨道交通专用无线频段的车地通信系统。利用我国自主知识产权的TD-LTE(time division long term evolution,分时长期演进)技术,设计出基于LTE(long term evolution,长期演进)的城市轨道交通车地通信综合承载系统(LTE-M),在北京的国家铁道实验中心环形道进行全球第1个LTE-M系统的试验段测试。整个测试过程完全复制列车的实际运行场景,包括真实的车辆、设备以及高架、隧道等实际通信场景。大量的测试结果表明,所设计的LTE-M系统抗干扰能力强、综合承载能力强、频谱利用率高,能够满足轨道交通业务需求。LTEM系统用于承载轨道交通综合业务,在保障CBTC(基于通信的列车控制)业务高可靠传输的同时,能够为CCTV(车辆视频监控)和PIS(乘客信息系统)等业务提供有效的传输通道。展开更多
基金the Science and Technology Cooperation Research and Development Project of Sichuan Provincial Academy and University(Grant No.2019YFSY0024)the Key Research and Development Program in Sichuan Province of China(Grant No.2019YFG0050)the Natural Science Foundation of Guangxi Province of China(Grant No.AD19245021).
文摘Support vehicles are part of the main body of airport ground operations,and their scheduling efficiency directly impacts flight delays.A mathematical model is constructed and the responsiveness of support vehicles for current operational demands is proposed to study optimization algorithms for vehicle scheduling.The model is based on the constraint relationship of the initial operation time,time window,and gate position distribution,which gives an improvement to the ant colony algorithm(ACO).The impacts of the improved ACO as used for support vehicle optimization are compared and analyzed.The results show that the scheduling scheme of refueling trucks based on the improved ACO can reduce flight delays caused by refueling operations by 56.87%,indicating the improved ACO can improve support vehicle scheduling.Besides,the improved ACO can jump out of local optima,which can balance the working time of refueling trucks.This research optimizes the scheduling scheme of support vehicles under the existing conditions of airports,which has practical significance to fully utilize ground service resources,improve the efficiency of airport ground operations,and effectively reduce flight delays caused by ground service support.
文摘In 2000, the United Nations (UN) developed Millennium Development Goals (MDG) with one of its aim being to improve access of potable water supply by 2015 in developing countries. This study thus focused on Kenya’s Gilgil constituency which lies in both arid and semi-arid zones and experiences bimodal rains which are neither heavy nor reliable. With persistent shortages, water management and monitoring became essential and in current times the use of Geographic Information Systems (GIS) is being incorporated due to its capability as an effective tool in water resources management. The study’s aim was to provide knowledge about accessible areas and gaps using cost surface analysis as well as identify other factors that influence settlement. The study utilized walk speeds as an impedance to determine cost surfaces followed by creation of service areas from water facilities using time as a measurement of access. The study established that surface friction may not have major influence on accessibility and service areas while logistic regression established that other factors strongly influence settlement apart from water availability. The study also reveals that 77% of the semi-permanent households in Gilgil have a hard time accessing water as they are outside the 30-minute walk time.
文摘为保证城市轨道交通运营安全,迫切需要整合车地无线通信生产业务的承载需求,建立基于城市轨道交通专用无线频段的车地通信系统。利用我国自主知识产权的TD-LTE(time division long term evolution,分时长期演进)技术,设计出基于LTE(long term evolution,长期演进)的城市轨道交通车地通信综合承载系统(LTE-M),在北京的国家铁道实验中心环形道进行全球第1个LTE-M系统的试验段测试。整个测试过程完全复制列车的实际运行场景,包括真实的车辆、设备以及高架、隧道等实际通信场景。大量的测试结果表明,所设计的LTE-M系统抗干扰能力强、综合承载能力强、频谱利用率高,能够满足轨道交通业务需求。LTEM系统用于承载轨道交通综合业务,在保障CBTC(基于通信的列车控制)业务高可靠传输的同时,能够为CCTV(车辆视频监控)和PIS(乘客信息系统)等业务提供有效的传输通道。
