Considerable changes have taken place in commercial passenger air transport since the enactment of the 1978 Airline Deregulation Act in the US and the deregulation of airline networks that has occurred elsewhere. The ...Considerable changes have taken place in commercial passenger air transport since the enactment of the 1978 Airline Deregulation Act in the US and the deregulation of airline networks that has occurred elsewhere. The commercial and operational freedoms have led most of the larger carriers to develop hub-and-spoke networks, within which certain cities or metropolitan areas emerge as key nodes possessing tremendous advantages over other locations in the air transport system. This paper examines the nature of hub-and-spoke operations in air transportation services, and the benefits that accrue to a city or geographical region that is host to an airline hub. In particular, it looks into linkages between the air service hub and local economic development. Four potential types of impact of airports on the regional economy are defined and discussed. As an example, the assessment of the economic impacts of Cincinnati-Northern Kentucky International Airport (CVG), a major Delta Airlines hub, is introduced.展开更多
1930s was the golden age for the flying-boat airlines in the world, notably the Pan Am Clipper transpacific and transatlantic routes, and the （British） Imperial Airways UK-Africa and UK-Australia/Far East routes. Th...1930s was the golden age for the flying-boat airlines in the world, notably the Pan Am Clipper transpacific and transatlantic routes, and the （British） Imperial Airways UK-Africa and UK-Australia/Far East routes. The major advantage of the flying boats was its endless runway （i.e., ocean or lake） and resultant possibilities for larger aircrafts than land-based airliners. Airlines such as Pan Am made large investments in the 1930s for flying boats, their special terminals by the water, and the worldwide flying-boat air route network. However, in the late 1940s to early 1950s, the flying boats suddenly disappeared due to the rapid development of land-based large airliners and long runways, according to the previous studies. The author conducted historical research on this topic, and found another reason： rapid decline in the high-income population who used to travel by flying boat scheduled flights. Also found was a recent surge of the luxury market, and steady increase in the cruise-ship passengers. Hence, there could be implications for revival of the flying boat flights as luxury cruise, rather than as scheduled flights.展开更多
The article aims to study the possible correlation between the presence and intensity of rainfall X- and T-radiation and low energy neutrons at one specific location in S[io Jos6 dos Campos, SP, Brazil. Monitoring of ...The article aims to study the possible correlation between the presence and intensity of rainfall X- and T-radiation and low energy neutrons at one specific location in S[io Jos6 dos Campos, SP, Brazil. Monitoring of these parameters was carried out from end February to half of June 2013 just in Physics Department of ITA （Technological Institute of Aeronautics）. By correlating the data of measurements of intensity of X and ）,-radiations with the rainfall it has been found that this meteorological parameter had a significant influence on the background of these radiation profile. A possible reason for this fact is associated with the presence of radon gas in the environment that is dragged to the surface during the occurrences of local rainfall. In relation neutrons, it was possible to note that the rainfall has small influence on this parameter measures.展开更多
A rapid approach to hypersonic aeroheating predictions in the stagnation region and downstream is developed in the present paper.The engineering method is used to calculate inviscid hypersonic flowfields to reduce tim...A rapid approach to hypersonic aeroheating predictions in the stagnation region and downstream is developed in the present paper.The engineering method is used to calculate inviscid hypersonic flowfields to reduce time cost,and a combination of the mass flow balance technique and the axisymmetric analog is proposed to account for the entropy swallowing effects.A three-dimensional linear method is derived to fit the vehicle surface flowfields.Then a new axisymmetric analog method based on linear flowfields and linear surface equations is developed,with the complexity and computational cost reduced dramatically.In the stagnation region,an implicit surface fitting is introduced to approximate the primary curvatures and a robust aeroheating prediction method is constructed.The proposed approach is verified on a variety of configurations including spherically blunted cone,double ellipsoid and aerospace vehicle.Numerical results indicate the followings:1)The approach predicts aeroheating in about one second and the results agree well with CFD simulations and wind-tunnel measurements;2)with the help of entropy correction,the precision is further improved in the streamline diverging regions on the vehicle surface,while little improvement is found after entropy correction in the regions where the streamlines do not diverge.展开更多
Based On the online reverse auction formalism in Priceline.com, In this paper,the use of online reverse auctions in airline companies revenue management is highlighted.This research examines the process of online reve...Based On the online reverse auction formalism in Priceline.com, In this paper,the use of online reverse auctions in airline companies revenue management is highlighted.This research examines the process of online reverse auctions in detail, point out the potential benefits of online reverse auctions. At last we examines how the online reverse auction mechanism design for optimal allocation.展开更多
基金Under the auspices of Intramural Research Incentive Grant from the Office of the Senior Vice President for Research atUniversity of Louisville
文摘Considerable changes have taken place in commercial passenger air transport since the enactment of the 1978 Airline Deregulation Act in the US and the deregulation of airline networks that has occurred elsewhere. The commercial and operational freedoms have led most of the larger carriers to develop hub-and-spoke networks, within which certain cities or metropolitan areas emerge as key nodes possessing tremendous advantages over other locations in the air transport system. This paper examines the nature of hub-and-spoke operations in air transportation services, and the benefits that accrue to a city or geographical region that is host to an airline hub. In particular, it looks into linkages between the air service hub and local economic development. Four potential types of impact of airports on the regional economy are defined and discussed. As an example, the assessment of the economic impacts of Cincinnati-Northern Kentucky International Airport (CVG), a major Delta Airlines hub, is introduced.
文摘1930s was the golden age for the flying-boat airlines in the world, notably the Pan Am Clipper transpacific and transatlantic routes, and the （British） Imperial Airways UK-Africa and UK-Australia/Far East routes. The major advantage of the flying boats was its endless runway （i.e., ocean or lake） and resultant possibilities for larger aircrafts than land-based airliners. Airlines such as Pan Am made large investments in the 1930s for flying boats, their special terminals by the water, and the worldwide flying-boat air route network. However, in the late 1940s to early 1950s, the flying boats suddenly disappeared due to the rapid development of land-based large airliners and long runways, according to the previous studies. The author conducted historical research on this topic, and found another reason： rapid decline in the high-income population who used to travel by flying boat scheduled flights. Also found was a recent surge of the luxury market, and steady increase in the cruise-ship passengers. Hence, there could be implications for revival of the flying boat flights as luxury cruise, rather than as scheduled flights.
文摘The article aims to study the possible correlation between the presence and intensity of rainfall X- and T-radiation and low energy neutrons at one specific location in S[io Jos6 dos Campos, SP, Brazil. Monitoring of these parameters was carried out from end February to half of June 2013 just in Physics Department of ITA （Technological Institute of Aeronautics）. By correlating the data of measurements of intensity of X and ）,-radiations with the rainfall it has been found that this meteorological parameter had a significant influence on the background of these radiation profile. A possible reason for this fact is associated with the presence of radon gas in the environment that is dragged to the surface during the occurrences of local rainfall. In relation neutrons, it was possible to note that the rainfall has small influence on this parameter measures.
基金supported by the Doctorate Creation Foundation of Northwestern Polytechnical University (Grant No. CX200902)
文摘A rapid approach to hypersonic aeroheating predictions in the stagnation region and downstream is developed in the present paper.The engineering method is used to calculate inviscid hypersonic flowfields to reduce time cost,and a combination of the mass flow balance technique and the axisymmetric analog is proposed to account for the entropy swallowing effects.A three-dimensional linear method is derived to fit the vehicle surface flowfields.Then a new axisymmetric analog method based on linear flowfields and linear surface equations is developed,with the complexity and computational cost reduced dramatically.In the stagnation region,an implicit surface fitting is introduced to approximate the primary curvatures and a robust aeroheating prediction method is constructed.The proposed approach is verified on a variety of configurations including spherically blunted cone,double ellipsoid and aerospace vehicle.Numerical results indicate the followings:1)The approach predicts aeroheating in about one second and the results agree well with CFD simulations and wind-tunnel measurements;2)with the help of entropy correction,the precision is further improved in the streamline diverging regions on the vehicle surface,while little improvement is found after entropy correction in the regions where the streamlines do not diverge.
文摘Based On the online reverse auction formalism in Priceline.com, In this paper,the use of online reverse auctions in airline companies revenue management is highlighted.This research examines the process of online reverse auctions in detail, point out the potential benefits of online reverse auctions. At last we examines how the online reverse auction mechanism design for optimal allocation.
