Network Aggregation Process in Multilayer Air Transportation Networks

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.

Medical transportation and the contribution of air medical evacuation in isolated mountainous areas of Greece-Case study,Municipality of Agrafa

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.

Analysis of the Chinese air route network as a complex network

The air route network, which supports all the flight activities of the civil aviation, is the most fundamental infrastructure of air traffic management system. In this paper, we study the Chinese air route network （CARN） within the framework of complex networks. We find that CARN is a geographical network possessing exponential degree distribution, low clustering coefficient, large shortest path length and exponential spatial distance distribution that is obviously different from that of the Chinese airport network （CAN）. Besides, via investigating the flight data from 2002 to 2010, we demonstrate that the topology structure of CARN is homogeneous, howbeit the distribution of flight flow on CARN is rather heterogeneous. In addition, the traffic on CARN keeps growing in an exponential form and the increasing speed of west China is remarkably larger than that of east China. Our work will be helpful to better understand Chinese air traffic systems.

Multi-objective Collaborative Optimization for Scheduling Aircraft Landing on Closely Spaced Parallel Runways Based on Genetic Algorithms

A scheduling model of closely spaced parallel runways for arrival aircraft was proposed,with multi-objections of the minimum flight delay cost,the maximum airport capacity,the minimum workload of air traffic controller and the maximum fairness of airlines′scheduling.The time interval between two runways and changes of aircraft landing order were taken as the constraints.Genetic algorithm was used to solve the model,and the model constrained unit delay cost of the aircraft with multiple flight tasks to reduce its delay influence range.Each objective function value or the fitness of particle unsatisfied the constrain condition would be punished.Finally,one domestic airport hub was introduced to verify the algorithm and the model.The results showed that the genetic algorithm presented strong convergence and timeliness for solving constraint multi-objective aircraft landing problem on closely spaced parallel runways,and the optimization results were better than that of actual scheduling.

Seasonal Variations of Terrestrial OC Sources in Aerosols over the East China Sea: The Influence of Long-Range Air Mass Transport

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.

An Analysis of the Air Parcel Trajectories of Long-Range Transport at Shanghai

1.INTRODUCTION Acid rain observations show that acid cloud water in Shanghai region appears not only

Regulations of Business Licensing for Route of Foreign Air Transport Enterprises

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.

Prediction Analysis on the Transport Distance of Supply Air in Warm Air Heating Room with Impinging Jet Ventilation Systems

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.

Application of Nonlinear Triangular Fuzzy Fault Tree Algorithm in Predicting Lithium Battery Air Transport Accidents

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.

Dynamic Modeling of Air Pollution and Acid Rain from Energy System and Transport in Kosovo

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.

Research on the evolutionary game of the supervision of civil aviation dangerous goods transportation training

This study is carried out to promote the precise supervision of dangerous goods transportation training,improve the efficiency of civil aviation supervision and further ensure the safety of air transportation.First,from the perspective of behaviour interaction and interest demands,evolutionary game theory is used to construct a tripartite evolutionary game model of dangerous goods transportation training institutions,the Civil Aviation Administration of China(CAAC)and the public.Then,the evolutionary game equilibrium of the system is further analysed under the joint action of the three parties.Finally,the influences of important parameters of the model on the behavioural strategy selection of the three parties are investigated via MATLAB numerical simulation.The conclusions reveal that the system has three evolutionarily stable strategies under different parameters,namely(non-compliant training,supervision,non-participation in supervision),(non-compliant training,supervision,participation in supervision)and(compliant training,supervision,non-participation in supervision).Moreover,the CAAC supervision cost,the fine amount,the supervision cost of public participation,the supervision success rate and the reporting reward amount are the main parameters that affect the behavioural strategy selection of the tripartite game players.The conclusions and suggestions of this study provide a decision-making basis and guidance for the supervision and management of civil aviation dangerous goods transportation training.

Optimization Method for Departure Flight Scheduling Problem Based on Genetic Algorithm

Except for the bad weather or other uncontrollable reasons,a reasonable queue of departure and arrival flights is one of the important methods to reduce the delay on busy airports.Here focusing on the Pareto optimization of departure flights,the take-off sequencing is taken as a single machine scheduling problem with two objective functions,i.e.,the minimum of total weighted delayed number of departure flights and the latest delay time of delayed flight.And the integer programming model is established and solved by multi-objective genetic algorithm.The simulation results show that the method can obtain the better goal,and provide a variety of options for controllers considering the scene situation,thus improving the flexibility and effectivity of flight plan.

Engine Selection Based on Utility Theory

Since an engine is seen as the″heart″of an airplane,the objective and scientific evaluation of it is significant to ensure normal operation of airlines.Aiming at the limitations of current studies on selecting engines,a quantitative comprehensive evaluation system of engine options was established and an optimization model based on the utility theory and analytic hierarchy process(AHP)was proposed.Considering the judgement of different customers on the balance between income and risk,the utility of each evaluation index was determined by utilizing the piecewise utility function.The AHP was used to analyze individual demands of customers.Finally,the optimal scheme was selected through calculating the weighted utility value.According to the actual needs of a domestic airline,the utility of three engine options was calculated.The results showed that the value of risk factor can be set to determine the selection scheme based on the degree of preferences(conservative type,neutral type or adventurous type).

A Hybrid Method Combining Improved K-means Algorithm with BADA Model for Generating Nominal Flight Profiles

A high-precision nominal flight profile,involving controllers′intentions is critical for 4Dtrajectory estimation in modern automatic air traffic control systems.We proposed a novel method to effectively improve the accuracy of the nominal flight profile,including the nominal altitude profile and the speed profile.First,considering the characteristics of trajectory data,we developed an improved K-means algorithm.The approach was to measure the similarity between different altitude profiles by integrating the space warp edit distance algorithm,thereby to acquire several fitted nominal flight altitude profiles.This approach breaks the constraints of traditional K-means algorithms.Second,to eliminate the influence of meteorological factors,we introduced historical gridded binary data to determine the en-route wind speed and temperature via inverse distance weighted interpolation.Finally,we facilitated the true airspeed determined by speed triangle relationships and the calibrated airspeed determined by aircraft data model to extract a more accurate nominal speed profile from each cluster,therefore we could describe the airspeed profiles above and below the airspeed transition altitude,respectively.Our experimental results showed that the proposed method could obtain a highly accurate nominal flight profile,which reflects the actual aircraft flight status.

Probability Distribution of Edge in Adjacent Matrix of Aviation Network of China and Algorithm of Searching Non-overlap Community Structure Based on Complex Network

In order to discover the probability distribution feature of edge in aviation network adjacent matrix of China and on the basis of this feature to establish an algorithm of searching non-overlap community structure in network to reveal the inner principle of complex network with the feature of small world in aspect of adjacent matrix and community structure,aviation network adjacent matrix of China was transformed according to the node rank and the matrix was arranged on the basis of ascending node rank with the center point as original point.Adjacent probability from the original point to extension around in approximate area was calculated.Through fitting probability distribution curve,power function of probability distribution of edge in adjacent matrix arranged by ascending node rank was found.According to the feature of adjacent probability distribution,deleting step by step with node rank ascending algorithm was set up to search non-overlap community structure in network and the flow chart of algorithm was given.A non-overlap community structure with 10 different scale communities in aviation network of China was found by the computer program written on the basis of this algorithm.

Automatic interval management for aircraft based on dynamic fuzzy speed control considering uncertainty

A novel real-time autonomous Interval Management System(IMS)is proposed to automate interval management,which considers the effect of wind uncertainty using the Dynamic Fuzzy Velocity Decision(DFVD)algorithm.The membership function can be generated dynamically based on the True Air Speed(TAS)limitation changes in real time and the interval criterion of the adjacent aircraft,and combined with human cognition to formulate fuzzy rules for speed adjusting decision-making.Three groups of experiments were conducted during the en-route descent stage to validate the proposed IMS and DFVD performances,and to analyze the impact factors of the algorithm.The verification experimental results show that compared with actual flight status data under controllers’command,the IMS reduces the descent time by approaching 30%with favorable wind uncertainty suppression performance.Sensitivity analysis shows that the ability improvement of DFVD is mainly affected by the boundary value of the membership function.Additionally,the dynamic generation of the velocity membership function has greater advantages than the static method in terms of safety and stability.Through the analysis of influencing factors,we found that the interval criterion and aircraft category have no significant effect on the capability of IMS.In a higher initial altitude scenario,the initial interval should be appropriately increased to enhance safety and efficiency during the descent process.This prototype system could evolve into a realtime Flight-deck Interval Management(FIM)tool in the future.

Collision risk assessment of reduced aircraft separation minima in procedural airspace using advanced communication and navigation

With the advancement of Communication,Navigation and Surveillance(CNS)technolo-gies such as space-based Automatic Dependent Surveillance-Broadcast/Contract(ADS-B/C),large separation minima may be reduced in procedural airspaces.It is of great significance to know the upper limit of the Reduced Separation Minima(RSM)for a procedural airspace and the corre-sponding consequences on collision risk with specifics of the advanced ADS-B and control interven-tion model.In this work,an interactive software is first developed for collision risk estimation.This software integrates the International Civil Aviation Organization(ICAO)collision risk models for lateral and longitudinal collision risk calculation for the Singapore procedural airspace.Results demonstrate that the lateral and longitudinal collision risk of Singapore procedural airspace with respect to current control procedures meets the ICAO Target Level of Safety(TLS)standard.Moreover,the feasibility of reducing the horizontal separations implemented in the Singapore pro-cedural airspace with respect to advanced CNS techniques is investigated.It is found that if advanced CNS technologies are applied,then the current 50-NM lateral and longitudinal separa-tion standards can be reduced to 22 NM(1 NM=1.825 km)and 20 NM,respectively,to meet the TLS standards based on current demand.A method is then devised to expand the traffic demand by p for p∈[10%,200%].It is found that the minimum lateral and longitudinal separa-tions can be reduced from 50 NM to be within the range of[23,31]NM,and 20 NM,respectively,for p∈[10%,200%],while the collision risk still meets the TLS standards.

A review of the technology and applications of methods for evaluating the transport of air pollutants

A variety of methods based on air quality models,including tracer methods,the bruteforce method(BFM),decoupled direct method(DDM),high-order decoupled direct method(HDDM),response surface models(RSMs)and so on forth,have been widely used to study the transport of air pollutants.These methods have good applicability for the transport of air pollutants with simple formation mechanisms.However,differences in research conclusions on secondary pollutants with obvious nonlinear characteristics have been reported.For example,the tracer method is suitable for the study of simpli?ed scenarios,while HDDM and RSMs are more suitable for the study for nonlinear pollutants.Multiple observation techniques,including conventional air pollutant observation,lidar observation,air sounding balloons,vehicle-mounted and ship-borne technology,aerial surveys,and remote sensing observations,have been utilized to investigate air pollutant transport characteristics with time resolution as high as 1 sec.In addition,based on a multi-regional input-output model combined with emission inventories,the transfer of air pollutant emissions can be evaluated and applied to study the air pollutant transport characteristics.Observational technologies have advantages in temporal resolution and accuracy,while modeling technologies are more?exible in spatial resolution and research plan setting.In order to accurately quantify the transport characteristics of pollutants,it is necessary to develop a research method for interactive veri?cation of observation and simulation.Quantitative evaluation of the transport of air pollutants from different angles can provide a scienti?c basis for regional joint prevention and control.

Robustness analysis metrics for worldwide airport network：A comprehensive study

Robustness of transportation networks is one of the major challenges of the 21 st century.This paper investigates the resilience of global air transportation from a complex network point of view,with focus on attacking strategies in the airport network,i.e.,to remove airports from the system and see what could affect the air traffic system from a passenger＇s perspective.Specifically,we identify commonalities and differences between several robustness measures and attacking strategies,proposing a novel notion of functional robustness：unaffected passengers with rerouting.We apply twelve attacking strategies to the worldwide airport network with three weights,and evaluate three robustness measures.We find that degree and Bonacich based attacks harm passenger weighted network most.Our evaluation is geared toward a unified view on air transportation network attack and serves as a foundation on how to develop effective mitigation strategies.

A survey of safety separation management and collision avoidance approaches of civil UAS operating in integration national airspace system

Recent years have witnessed a booming of the industry of civil Unmanned Aircraft System(UAS).As an emerging industry,the UAS industry has been attracting great attention from governments of all countries and the aviation industry.UAS are highly digitalized,informationized,and intelligent;therefore,their integration into the national airspace system has become an important trend in the development of civil aviation.However,the complexity of UAS operation poses great challenges to the traditional aviation regulatory system and technical means.How to prevent collisions between UASs and between UAS and manned aircraft to achieve safe and efficient operation in the integrated operating airspace has become a common challenge for industry and academia around the world.In recent years,the international community has carried out a great amount of work and experiments in the air traffic management of UAS and some of the key technologies.This paper attempts to make a review of the UAS separation management and key technologies in collision avoidance in the integrated airspace,mainly focusing on the current situation of UAS Traffic Management(UTM),safety separation standards,detection system,collision risk prediction,collision avoidance,safety risk assessment,etc.,as well as an analysis of the bottlenecks that the current researches encountered and their development trends,so as to provide some insights and references for further research in this regard.Finally,this paper makes a further summary of some of the research highlights and challenges.