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
Classical risk-based or game-theoretic security models rely on assumptions from reliability theory and rational expectations economics that are not applicable to security threats. Additionally, these models suffer fro...Classical risk-based or game-theoretic security models rely on assumptions from reliability theory and rational expectations economics that are not applicable to security threats. Additionally, these models suffer from serious deficiencies when they are applied to software-intensive, socio-technical systems. A new approach is proposed in this paper that applies principles from control theory to enforce constraints on security threats thereby extending techniques used in system safety engineering. It is applied to identify and mitigate the threats that could emerge in critical infrastructures such as the air transportation system. Insights are provided to assist systems engineers and policy makers in securely transitioning to the Next Generation Air Transportation System (NGATS).展开更多
To overcome the disadvantages of displacement ventilation( DV) and traditional mixing ventilation( MV) system,a new ventilation system known as impinging jet ventilation system( IJVS)has been developing. The warm air ...To overcome the disadvantages of displacement ventilation( DV) and traditional mixing ventilation( MV) system,a new ventilation system known as impinging jet ventilation system( IJVS)has been developing. The warm air can be supplied with impinging jet ventilation( IJV), while the DV is only used for cooling.However,the flow and temperature field of IJV under heating scenario has had few references. The paper is mainly focused on computational fluid dynamics( CFD) and developing an adequate correlation between the distance L that warm air can reach and different parameters in the warm IJVS by using response surface methodology( RSM). The results indicate that L decreases as the supply velocity υ decreases but increases as the supply temperature difference ΔT or the discharge height h decreases. In the variable air volume( VAV) system, it is necessary to determine supply parameters both under the maximum-heat-load condition and the small-heat-load condition. Unlike the VAV system,the constant air volume( CAV) system has no need to study the small-heat-load condition. Draught discomfort near the nozzle becomes the issue of concern in IJVS, thus the suitable discharge height is of great importance in design and can be calculated based on the predictive model.展开更多
Sulfur dioxide (SO2) and nitrogen dioxide (NO2) emissions generated at coal burning power plants and from transport are a leading cause of acid deposition and chemical smog in many parts of the world. Sulfur dioxide e...Sulfur dioxide (SO2) and nitrogen dioxide (NO2) emissions generated at coal burning power plants and from transport are a leading cause of acid deposition and chemical smog in many parts of the world. Sulfur dioxide emitted by thermal power plants and from transport in Kosovo is transported via prevailing winds to other locations. Through its journey, this SO2 gas undergoes a series of chemical reactions that ultimately transform it into sulfuric acid (H2SO4) which is deposited as acid rain. As a consequence of NO2 emissions from electricity production and transport in Kosovo the ozone (O3) is formed as photochemical smog due to sunlight, which triggers the breakdown of NO2. We modeled the impact of SO2 and NO2 emissions from energy system and transport in Kosovo on acid deposition and chemical smog locally. In model we consider the role of SO2 and NO2 pollution control technologies on mitigating these impacts.展开更多
The air transportation network, one of the common multilayer complex systems, is composed of a collection of individual airlines, and each airline corresponds to a different layer. An important question is then how ma...The air transportation network, one of the common multilayer complex systems, is composed of a collection of individual airlines, and each airline corresponds to a different layer. An important question is then how many airlines are really necessary to represent the optimal structure of a multilayer air transportation system. Here we take the Chinese air transportation network (CATN) as an example to explore the nature of multiplex systems through the procedure of network aggregation. Specifically, we propose a series of structural measures to characterize the CATN from the multilayered to the aggregated network level. We show how these measures evolve during the network aggregation process in which layers are gradually merged together and find that there is an evident structural transition that happened in the aggregated network with nine randomly chosen airlines merged, where the network features and construction cost of this network are almost equivalent to those of the present CATN with twenty-two airlines under this condition. These findings could shed some light on network structure optimization and management of the Chinese air transportation system.展开更多
The homogeneity analysis of multi-airport system can provide important decision-making support for the route layout and cooperative operation.Existing research seldom analyzes the homogeneity of multi-airport system f...The homogeneity analysis of multi-airport system can provide important decision-making support for the route layout and cooperative operation.Existing research seldom analyzes the homogeneity of multi-airport system from the perspective of route network analysis,and the attribute information of airport nodes in the airport route network is not appropriately integrated into the airport network.In order to solve this problem,a multi-airport system homogeneity analysis method based on airport attribute network representation learning is proposed.Firstly,the route network of a multi-airport system with attribute information is constructed.If there are flights between airports,an edge is added between airports,and regional attribute information is added for each airport node.Secondly,the airport attributes and the airport network vector are represented respectively.The airport attributes and the airport network vector are embedded into the unified airport representation vector space by the network representation learning method,and then the airport vector integrating the airport attributes and the airport network characteristics is obtained.By calculating the similarity of the airport vectors,it is convenient to calculate the degree of homogeneity between airports and the homogeneity of the multi-airport system.The experimental results on the Beijing-Tianjin-Hebei multi-airport system show that,compared with other existing algorithms,the homogeneity analysis method based on attributed network representation learning can get more consistent results with the current situation of Beijing-Tianjin-Hebei multi-airport system.展开更多
European air transport network(EATN)and Chinese air transport network(CATN),as two important air transport systems in the world,are facing increasingly spatial hazards,such as extreme weathers and natural disasters. I...European air transport network(EATN)and Chinese air transport network(CATN),as two important air transport systems in the world,are facing increasingly spatial hazards,such as extreme weathers and natural disasters. In order to reflect and compare impact of spatial hazards on the two networks in a practical way,a new spatial vulnerability model(SVM)is proposed in this paper,which analyzes vulnerability of a network system under spatial hazards from the perspectives of network topology and characteristics of hazards. Before introduction of the SVM,two abstract networks for EATN and CATN are established with a simple topological analysis by traditional vulnerability method. Then,the process to study vulnerability of an air transport network under spatial hazards by SVM is presented. Based on it,a comparative case study on EATN and CATN under two representative spatial hazard scenarios,one with an even spatial distribution,named as spatially uniform hazard,and the other with an uneven spatial distribution that takes rainstorm hazard as an example,is conducted. The simulation results show that both of EATN and CATN are robust to spatially uniform hazard,but vulnerable to rainstorm hazard. In the comparison of the results of the two networks that only stands from the points of network topology and characteristics of hazard without considering certain unequal factors,including airspace openness and flight safety importance in Europe and China,EATN is more vulnerable than CATN under rainstorm hazard. This suggests that when the two networks grow to a similar developed level in future,EATN needs to pay more attention to the impact of rainstorm hazard.展开更多
Aerosols represent an important source of terrestrial organic carbon(OC)from the East Asian continent to the China marginal seas,thus their provenance and transport play important roles in the global carbon cycle.Fift...Aerosols represent an important source of terrestrial organic carbon(OC)from the East Asian continent to the China marginal seas,thus their provenance and transport play important roles in the global carbon cycle.Fifty samples of total suspended particle were collected seasonally from the nearshore Huaniao Island(HNI)in East China Sea(ECS)from April 2018 to January 2019;and they were analyzed for total organic carbon(TOC)content and stable carbon isotope(δ^(13)C),as well as terrestrial bio-markers including n-alkanes(C_(20)-C_(33)),n-alkanols(C_(20)-C32)and n-fatty acids(n-FAs,C_(20)-C30),to distinguish the seasonal variabili-ties of terrestrial OC sources and reveal the influence of the long-range air mass transport on these sources.The TOC-δ^(13)C values(range from−27.3‰to−24.3‰)and molecular distributions of terrestrial biomarkers both suggested that terrestrial OC contribu-tions to aerosols had significant seasonal variations.The source indices of terrestrial biomarkers(e.g.,Fossil%=82.8%for n-alkanes)revealed that the fossil fuel OC contributions,including coal burning and vehicular emission,were higher in winter,mainly because of the long-range air mass transport from the north of the East Asian continent.The terrestrial plant OC contributions were higher in summer(e.g.,Wax%=32.4%for n-alkanes),likely due to local vegetation sources from HNI and East Asian continental air masses.Cluster analysis of air mass backward-trajectories clearly showed that transport pathway plays an important role in determining the organic constituents of aerosols in China marginal seas.A comparison of these terrestrial OC contributions from different air mass origins suggested that fossil fuel OC showed less variations among various air mass origins from northern China in winter,while terrestrial plant OC sources from northern and southern China in summer contributed more than that from the air masses transported through the ECS.These results provided a basis for future quantification of terrestrial OC from different origins in marine aerosols,by combining biomarker index and carbon isotopes.展开更多
In every emergency medical situation,access to emergency medical services is an inalienable right of any citizen.The average acceptable time to provide first aid assistance is 60 minutes.In this paper,the possibility ...In every emergency medical situation,access to emergency medical services is an inalienable right of any citizen.The average acceptable time to provide first aid assistance is 60 minutes.In this paper,the possibility of using helicopters for air travel in mountainous areas was examined for the first time for all of Greece and especially for a mountainous and isolated area such as the Municipality of Agrafa.Initially,the time distance-virtual distance,from the hospitals was calculated at the national level of Greece,with an acceptable first contact time of 60 minutes(golden hour),i.e.,less than two hours from the nearest hospital to the incident and back to the hospital and the relevant conclusions are drawn.Then,the case study of Municipality of Agrafa,one of the most mountainous areas in Greece,was examined.The time distance of the settlements from the nearest primary health point,namely the Primary Health Centre(PHC)of West Fragkista,was calculated and the transportation by ground means was compared with the corresponding time by flying means,to investigate the contribution of air transportation or not,of the timely arrival of the patients in the appropriate health structure.Finally,possible helicopter landing locations were identified,using a geographic information system to facilitate the process of air medical transportation in the Municipality of Agrafa.展开更多
The tourist industry, as global mass phenomenon, is inextricably linked to the evolution of air transport systems and air carriers, in turn, depends on tourism to ensure stability in routes and prices. Therefore, both...The tourist industry, as global mass phenomenon, is inextricably linked to the evolution of air transport systems and air carriers, in turn, depends on tourism to ensure stability in routes and prices. Therefore, both sectors must face the new challenges together, the transport industry is heading a problem of energy and cost overruns, that inevitably will affect tourism in the short term. The first energy crisis that they are starting to live, has been mitigated by changes in three parameters: (1) the international regulation of commercial aviation; (2) the connectivity and business (birth of low cost companies) models; and (3) the new policies for climate change and gas emission. So far, the rapid growth of the tourist industry has being held on a fast and cheap access to transport energy resources based on the false belief of unlimited access to energy. The article is a review of the state of the art, and the research papers published on air transportation, relating to tourism and the emergence of low cost airlines, in order to give a global vision for the decision makers of mass destinations, as it is the case of the Canary Islands that we will use as a reference.展开更多
After China's entry into WTO, our industries will be confronted with fiercer competition. How to strengthen their international competitiveness to seek for survival and development has become a very urgent problem. T...After China's entry into WTO, our industries will be confronted with fiercer competition. How to strengthen their international competitiveness to seek for survival and development has become a very urgent problem. This paper first simply discusses the meaning and theo^es of industrial international competitiveness, then chooses proper indexes according to some principles, explains the factor analysis method of industrial international competitiveness, and finally makes empirical analysis on China air transport industry.展开更多
Regulations of Busi- ness Licensing for Route of Foreign Air Transport Enterprises(CCAR- 287),which were passed at the executive meeting of Civil Aviation Ad- ministration of China on May 19,2008,were hereby promulgat...Regulations of Busi- ness Licensing for Route of Foreign Air Transport Enterprises(CCAR- 287),which were passed at the executive meeting of Civil Aviation Ad- ministration of China on May 19,2008,were hereby promulgated and became effective as of July 11,2008.展开更多
The traditional triangular fuzzy fault tree prediction model adopts the linear approximation method.Therefore,the accident prediction error is large.Based on the analysis of the error sources and the fuzzy set,the pre...The traditional triangular fuzzy fault tree prediction model adopts the linear approximation method.Therefore,the accident prediction error is large.Based on the analysis of the error sources and the fuzzy set,the precise calculation method of the event at the top of the fault tree is given.By using the numerical calculation software,an accurate calculation method of nonlinear triangular fuzzy accident prediction was adopted to predict lithium battery air transport fire accidents,and the fuzzy importance of the cause event was calculated.展开更多
Assessment of harmful impacts and risks of air pollution in case of accidents as well as of long lasting exposition is an important challenge of chemical transport modeling. Sad confirmation of this statement unexpect...Assessment of harmful impacts and risks of air pollution in case of accidents as well as of long lasting exposition is an important challenge of chemical transport modeling. Sad confirmation of this statement unexpectedly has come from the nuclear power plant accident in Fukushima which occurred while this paper was finalized. Two strategies to comply with the task of impact and risk assessment in extended regions like Central Europe or the Balkans are described. The first one is characterized by application of a single model system to an extended domain. The other one is based on the combined application of several chemical transport models designed for the use in various sub-domains in the region under consideration. Advantages and disadvantages exist for both approaches. For instance, the single model strategy allows unified and harmonized assessment of risks in a larger region, whereas the combined model strategy may pro-vide faster and locally more specific response in emergency cases. The single model approach is treated exploiting applications of the EURAD model system. The combined model approach is a novel way of joint use of chemical transport model systems developed for the Balkans. The models are described and the accuracy of simulations carried out with them is briefly demonstrated by comparison of simulated and observed concentrations of air pollutants. Applications regarding the search of sources for high pollution events and the assessment of risks through known sources are exem-plarily discussed.展开更多
The Asian monsoon(AM) region is a well-known region with prevailing stratosphere–troposphere exchange(STE).However,how the STE across this region changes with the weakening AM remains unclear.Here,we particularly dia...The Asian monsoon(AM) region is a well-known region with prevailing stratosphere–troposphere exchange(STE).However,how the STE across this region changes with the weakening AM remains unclear.Here,we particularly diagnose the air mass transport between the planetary boundary layer(PBL) and the stratosphere over the AM region during 1992–2017 using the Lagrangian particle dispersion model FLEXPART based on the ERA-Interim reanalysis data.The results show that both the downward and upward deep STEs exhibit a detectable increasing trend,while the latter,namely,the deep troposphere-to-stratosphere transport(DTST),is relatively more significant.Further analysis reveals that the long-term trend of DTST over the AM region could be partly attributed to changes in the Pacific Walker circulation and the air temperature(especially at upper levels).Additionally,it is found that DTST increases markedly over the tropical oceanic regions,while the increasing DTST into the stratosphere can be attributed to the enhanced air masses originated from the PBL over the terrestrial regions,where large amounts of pollutant emissions occur.The results imply that the influence of the DTST on the chemical composition and the climate of the stratosphere over the AM region is expected to become increasingly important,and is thereby of relevance to climate projection in an evolving climate.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Classical risk-based or game-theoretic security models rely on assumptions from reliability theory and rational expectations economics that are not applicable to security threats. Additionally, these models suffer from serious deficiencies when they are applied to software-intensive, socio-technical systems. A new approach is proposed in this paper that applies principles from control theory to enforce constraints on security threats thereby extending techniques used in system safety engineering. It is applied to identify and mitigate the threats that could emerge in critical infrastructures such as the air transportation system. Insights are provided to assist systems engineers and policy makers in securely transitioning to the Next Generation Air Transportation System (NGATS).
基金National Natural Science Foundation of China(No.51278094)the Innovation Foundation of Shanghai Education Commission,China(No.13ZZ054)
文摘To overcome the disadvantages of displacement ventilation( DV) and traditional mixing ventilation( MV) system,a new ventilation system known as impinging jet ventilation system( IJVS)has been developing. The warm air can be supplied with impinging jet ventilation( IJV), while the DV is only used for cooling.However,the flow and temperature field of IJV under heating scenario has had few references. The paper is mainly focused on computational fluid dynamics( CFD) and developing an adequate correlation between the distance L that warm air can reach and different parameters in the warm IJVS by using response surface methodology( RSM). The results indicate that L decreases as the supply velocity υ decreases but increases as the supply temperature difference ΔT or the discharge height h decreases. In the variable air volume( VAV) system, it is necessary to determine supply parameters both under the maximum-heat-load condition and the small-heat-load condition. Unlike the VAV system,the constant air volume( CAV) system has no need to study the small-heat-load condition. Draught discomfort near the nozzle becomes the issue of concern in IJVS, thus the suitable discharge height is of great importance in design and can be calculated based on the predictive model.
文摘Sulfur dioxide (SO2) and nitrogen dioxide (NO2) emissions generated at coal burning power plants and from transport are a leading cause of acid deposition and chemical smog in many parts of the world. Sulfur dioxide emitted by thermal power plants and from transport in Kosovo is transported via prevailing winds to other locations. Through its journey, this SO2 gas undergoes a series of chemical reactions that ultimately transform it into sulfuric acid (H2SO4) which is deposited as acid rain. As a consequence of NO2 emissions from electricity production and transport in Kosovo the ozone (O3) is formed as photochemical smog due to sunlight, which triggers the breakdown of NO2. We modeled the impact of SO2 and NO2 emissions from energy system and transport in Kosovo on acid deposition and chemical smog locally. In model we consider the role of SO2 and NO2 pollution control technologies on mitigating these impacts.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11405118,11401448 and 11301403
文摘The air transportation network, one of the common multilayer complex systems, is composed of a collection of individual airlines, and each airline corresponds to a different layer. An important question is then how many airlines are really necessary to represent the optimal structure of a multilayer air transportation system. Here we take the Chinese air transportation network (CATN) as an example to explore the nature of multiplex systems through the procedure of network aggregation. Specifically, we propose a series of structural measures to characterize the CATN from the multilayered to the aggregated network level. We show how these measures evolve during the network aggregation process in which layers are gradually merged together and find that there is an evident structural transition that happened in the aggregated network with nine randomly chosen airlines merged, where the network features and construction cost of this network are almost equivalent to those of the present CATN with twenty-two airlines under this condition. These findings could shed some light on network structure optimization and management of the Chinese air transportation system.
基金supported by the Natural Science Foundation of Tianjin(No.20JCQNJC00720)the Fundamental Research Fund for the Central Universities(No.3122021052)。
文摘The homogeneity analysis of multi-airport system can provide important decision-making support for the route layout and cooperative operation.Existing research seldom analyzes the homogeneity of multi-airport system from the perspective of route network analysis,and the attribute information of airport nodes in the airport route network is not appropriately integrated into the airport network.In order to solve this problem,a multi-airport system homogeneity analysis method based on airport attribute network representation learning is proposed.Firstly,the route network of a multi-airport system with attribute information is constructed.If there are flights between airports,an edge is added between airports,and regional attribute information is added for each airport node.Secondly,the airport attributes and the airport network vector are represented respectively.The airport attributes and the airport network vector are embedded into the unified airport representation vector space by the network representation learning method,and then the airport vector integrating the airport attributes and the airport network characteristics is obtained.By calculating the similarity of the airport vectors,it is convenient to calculate the degree of homogeneity between airports and the homogeneity of the multi-airport system.The experimental results on the Beijing-Tianjin-Hebei multi-airport system show that,compared with other existing algorithms,the homogeneity analysis method based on attributed network representation learning can get more consistent results with the current situation of Beijing-Tianjin-Hebei multi-airport system.
基金This work was supported in part by the National Key Research and Development Program of China(No.2018YFC0823706-02)the Fundamental Research Funds for the Central Universities of China(No.3122019057).
文摘European air transport network(EATN)and Chinese air transport network(CATN),as two important air transport systems in the world,are facing increasingly spatial hazards,such as extreme weathers and natural disasters. In order to reflect and compare impact of spatial hazards on the two networks in a practical way,a new spatial vulnerability model(SVM)is proposed in this paper,which analyzes vulnerability of a network system under spatial hazards from the perspectives of network topology and characteristics of hazards. Before introduction of the SVM,two abstract networks for EATN and CATN are established with a simple topological analysis by traditional vulnerability method. Then,the process to study vulnerability of an air transport network under spatial hazards by SVM is presented. Based on it,a comparative case study on EATN and CATN under two representative spatial hazard scenarios,one with an even spatial distribution,named as spatially uniform hazard,and the other with an uneven spatial distribution that takes rainstorm hazard as an example,is conducted. The simulation results show that both of EATN and CATN are robust to spatially uniform hazard,but vulnerable to rainstorm hazard. In the comparison of the results of the two networks that only stands from the points of network topology and characteristics of hazard without considering certain unequal factors,including airspace openness and flight safety importance in Europe and China,EATN is more vulnerable than CATN under rainstorm hazard. This suggests that when the two networks grow to a similar developed level in future,EATN needs to pay more attention to the impact of rainstorm hazard.
基金This study was supported by the National Natural Science Foundation of China(No.U1706219).This is MCTL(Key Laboratory of Marine Chemistry Theory and Technology)contribution#237.
文摘Aerosols represent an important source of terrestrial organic carbon(OC)from the East Asian continent to the China marginal seas,thus their provenance and transport play important roles in the global carbon cycle.Fifty samples of total suspended particle were collected seasonally from the nearshore Huaniao Island(HNI)in East China Sea(ECS)from April 2018 to January 2019;and they were analyzed for total organic carbon(TOC)content and stable carbon isotope(δ^(13)C),as well as terrestrial bio-markers including n-alkanes(C_(20)-C_(33)),n-alkanols(C_(20)-C32)and n-fatty acids(n-FAs,C_(20)-C30),to distinguish the seasonal variabili-ties of terrestrial OC sources and reveal the influence of the long-range air mass transport on these sources.The TOC-δ^(13)C values(range from−27.3‰to−24.3‰)and molecular distributions of terrestrial biomarkers both suggested that terrestrial OC contribu-tions to aerosols had significant seasonal variations.The source indices of terrestrial biomarkers(e.g.,Fossil%=82.8%for n-alkanes)revealed that the fossil fuel OC contributions,including coal burning and vehicular emission,were higher in winter,mainly because of the long-range air mass transport from the north of the East Asian continent.The terrestrial plant OC contributions were higher in summer(e.g.,Wax%=32.4%for n-alkanes),likely due to local vegetation sources from HNI and East Asian continental air masses.Cluster analysis of air mass backward-trajectories clearly showed that transport pathway plays an important role in determining the organic constituents of aerosols in China marginal seas.A comparison of these terrestrial OC contributions from different air mass origins suggested that fossil fuel OC showed less variations among various air mass origins from northern China in winter,while terrestrial plant OC sources from northern and southern China in summer contributed more than that from the air masses transported through the ECS.These results provided a basis for future quantification of terrestrial OC from different origins in marine aerosols,by combining biomarker index and carbon isotopes.
文摘In every emergency medical situation,access to emergency medical services is an inalienable right of any citizen.The average acceptable time to provide first aid assistance is 60 minutes.In this paper,the possibility of using helicopters for air travel in mountainous areas was examined for the first time for all of Greece and especially for a mountainous and isolated area such as the Municipality of Agrafa.Initially,the time distance-virtual distance,from the hospitals was calculated at the national level of Greece,with an acceptable first contact time of 60 minutes(golden hour),i.e.,less than two hours from the nearest hospital to the incident and back to the hospital and the relevant conclusions are drawn.Then,the case study of Municipality of Agrafa,one of the most mountainous areas in Greece,was examined.The time distance of the settlements from the nearest primary health point,namely the Primary Health Centre(PHC)of West Fragkista,was calculated and the transportation by ground means was compared with the corresponding time by flying means,to investigate the contribution of air transportation or not,of the timely arrival of the patients in the appropriate health structure.Finally,possible helicopter landing locations were identified,using a geographic information system to facilitate the process of air medical transportation in the Municipality of Agrafa.
文摘The tourist industry, as global mass phenomenon, is inextricably linked to the evolution of air transport systems and air carriers, in turn, depends on tourism to ensure stability in routes and prices. Therefore, both sectors must face the new challenges together, the transport industry is heading a problem of energy and cost overruns, that inevitably will affect tourism in the short term. The first energy crisis that they are starting to live, has been mitigated by changes in three parameters: (1) the international regulation of commercial aviation; (2) the connectivity and business (birth of low cost companies) models; and (3) the new policies for climate change and gas emission. So far, the rapid growth of the tourist industry has being held on a fast and cheap access to transport energy resources based on the false belief of unlimited access to energy. The article is a review of the state of the art, and the research papers published on air transportation, relating to tourism and the emergence of low cost airlines, in order to give a global vision for the decision makers of mass destinations, as it is the case of the Canary Islands that we will use as a reference.
文摘After China's entry into WTO, our industries will be confronted with fiercer competition. How to strengthen their international competitiveness to seek for survival and development has become a very urgent problem. This paper first simply discusses the meaning and theo^es of industrial international competitiveness, then chooses proper indexes according to some principles, explains the factor analysis method of industrial international competitiveness, and finally makes empirical analysis on China air transport industry.
文摘Regulations of Busi- ness Licensing for Route of Foreign Air Transport Enterprises(CCAR- 287),which were passed at the executive meeting of Civil Aviation Ad- ministration of China on May 19,2008,were hereby promulgated and became effective as of July 11,2008.
基金supported by Shanghai University New Teacher Training Research Project.
文摘The traditional triangular fuzzy fault tree prediction model adopts the linear approximation method.Therefore,the accident prediction error is large.Based on the analysis of the error sources and the fuzzy set,the precise calculation method of the event at the top of the fault tree is given.By using the numerical calculation software,an accurate calculation method of nonlinear triangular fuzzy accident prediction was adopted to predict lithium battery air transport fire accidents,and the fuzzy importance of the cause event was calculated.
文摘Assessment of harmful impacts and risks of air pollution in case of accidents as well as of long lasting exposition is an important challenge of chemical transport modeling. Sad confirmation of this statement unexpectedly has come from the nuclear power plant accident in Fukushima which occurred while this paper was finalized. Two strategies to comply with the task of impact and risk assessment in extended regions like Central Europe or the Balkans are described. The first one is characterized by application of a single model system to an extended domain. The other one is based on the combined application of several chemical transport models designed for the use in various sub-domains in the region under consideration. Advantages and disadvantages exist for both approaches. For instance, the single model strategy allows unified and harmonized assessment of risks in a larger region, whereas the combined model strategy may pro-vide faster and locally more specific response in emergency cases. The single model approach is treated exploiting applications of the EURAD model system. The combined model approach is a novel way of joint use of chemical transport model systems developed for the Balkans. The models are described and the accuracy of simulations carried out with them is briefly demonstrated by comparison of simulated and observed concentrations of air pollutants. Applications regarding the search of sources for high pollution events and the assessment of risks through known sources are exem-plarily discussed.
基金Supported by the National Key Research and Development Program of China (2023YFC3010700)Second Tibetan Plateau Comprehensive Scientific Expedition and Research Program (2019QZKK0105)Science and Technology Development Fund of Chinese Academy of Meteorological Sciences (2023KJ027 and 2024KJ012)。
文摘The Asian monsoon(AM) region is a well-known region with prevailing stratosphere–troposphere exchange(STE).However,how the STE across this region changes with the weakening AM remains unclear.Here,we particularly diagnose the air mass transport between the planetary boundary layer(PBL) and the stratosphere over the AM region during 1992–2017 using the Lagrangian particle dispersion model FLEXPART based on the ERA-Interim reanalysis data.The results show that both the downward and upward deep STEs exhibit a detectable increasing trend,while the latter,namely,the deep troposphere-to-stratosphere transport(DTST),is relatively more significant.Further analysis reveals that the long-term trend of DTST over the AM region could be partly attributed to changes in the Pacific Walker circulation and the air temperature(especially at upper levels).Additionally,it is found that DTST increases markedly over the tropical oceanic regions,while the increasing DTST into the stratosphere can be attributed to the enhanced air masses originated from the PBL over the terrestrial regions,where large amounts of pollutant emissions occur.The results imply that the influence of the DTST on the chemical composition and the climate of the stratosphere over the AM region is expected to become increasingly important,and is thereby of relevance to climate projection in an evolving climate.