TransportRN: Air Transportation Systems (Topic)最新文献

{"title":"Cross-Contaminations in Powder Bed Fusion: Influence of Copper Alloy Particles in Nickel-Base Alloy Feedstock on Part Quality","authors":"M. Horn, L. Langer, S. Dietrich, G. Schlick, C. Seidel, G. Reinhart","doi":"10.2139/ssrn.3724208","DOIUrl":"https://doi.org/10.2139/ssrn.3724208","url":null,"abstract":"When two or more different metal powders are processed on a single additive manufacturing (AM) machine, cross-contaminations can occur. This is particularly relevant to the consecutive processing of different materials on a powder bed fusion (PBF) machine through material changes as well as simultaneous processing of different materials via multi-material PBF. However, uncertainty about tolerable foreign particle percentages in metal powder feedstock limits the applicability of material changes and multi-material PBF. Two alloys which are of particular relevance to the aerospace industry are nickel-base alloy 2.4668 and copper alloy CW106C. In multi-material applications, 2.4668 mainly serves as a structural, load-bearing material. Therefore, this study investigates the influence of defined quantities of copper alloy particles in nickel-base alloy feedstock on metallurgical structure and static tensile strength. Foreign particle inclusions were dissolved in the matrix material and formed a solid solution. No material deteriorations were observed for contamination levels up to 20 particle percent (part.%). Etching revealed a nonhomogeneous solid solution with Cu-rich areas. Contamination levels up to two particle part.% CW106C in 2.4668 showed no influence on ultimate tensile strength and a limited influence on fracture elongation. At five part.% contamination, both properties deteriorated and inferior material qualities were observed. Fractography showed a similar fracture behavior for all of the contamination levels examined. Implications for the aerospace industry by the material combination examined are made on the basis of the results presented.","PeriodicalId":151146,"journal":{"name":"TransportRN: Air Transportation Systems (Topic)","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124463945","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of Support Structures on the Microstructure and Mechanical Properties of Case Hardening Steel in Laser Powder Bed Fusion","authors":"M. Schmitt, Maximilian Bösele, G. Schlick, G. Reinhart","doi":"10.2139/ssrn.3724368","DOIUrl":"https://doi.org/10.2139/ssrn.3724368","url":null,"abstract":"Additive manufacturing, especially laser powder bed fusion (LPBF), enables the manufacturing of complex and lightweight parts. LPBF is a technology with high geometric degrees of freedom, but there are production restrictions, e.g., with regard to overhangs. One strategy to produce these components despite the restrictions is the use of support structures. \u0000 \u0000After the LPBF process the support structures are removed by hand or through machining before general post-processing, e.g., manufacturing of functional surfaces or heat-treatments are concluded. However, support structures change the local process conditions during LPBF depending on the parts geometry (no support structures vs. use of support structures). The influence is mainly caused by the changed heat dissipation of the support structures compared to dense part material. In this contribution, the influence of support structures on the resulting microstructure and the mechanical properties are determined for the case hardening steel 16MnCr5. Case hardening steels are used for gearings and pinions for wide applications in the aerospace industry, e.g., engine gear boxes for helicopters or UAVs (unmanned aerial vehicles). It can be seen that the height of the applied support structures has great influence on the microstructure. Mechanical properties are determined through notched bar impact testing showing an increase in toughness in the as-built state with increasing support structure height. The findings correspond with the increasing content of ferrite seen in the microstructure. The effect of subsequent heat treatments (stress relief annealing and case hardening) on the mechanical properties is also investigated. Furthermore, generalized operating principles for the influence of support structures and the occurring insitu heat treatment in LPBF are presented and described based on the results shown.","PeriodicalId":151146,"journal":{"name":"TransportRN: Air Transportation Systems (Topic)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130446840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fault Detection for Aircraft Fuel System with Neural Network","authors":"Nithya Subramanian, Hongmei He, I. Jennions","doi":"10.2139/ssrn.3718044","DOIUrl":"https://doi.org/10.2139/ssrn.3718044","url":null,"abstract":"The technological advances in the aircraft industry in the last decade have increased the complexity of aircraft systems. This, in turn, makes the fault detection, diagnosis and modification/ repair processes more difficult. The presence of a fault within a system can result in changes to system function, reduce system performance and cause operational downtime. Due to this reason Condition Based Maintenance (CBM) which predicts the state of the component on based upon data gathered is widely used in aircraft MRO industries. CBM uses diagnostics and prognostics models to make decisions on appropriates maintenance actions based upon the remaining used life (RUL) of the components. \u0000 \u0000In this research, we applied a Neural Network model to solve the fault detection problem, and the experimental results demonstrated the neural network model can obtain excellent performance. Fault diagnosis is a more complicated problem, and it requires diagnosing the type of fault. Therefore, fault diagnosis becomes a classification problem. More importantly, the fault state of a fuel system may relate to the previous state of the fuel system. Therefore, a Recurrent Neural Network model could be developed for fault diagnosis.","PeriodicalId":151146,"journal":{"name":"TransportRN: Air Transportation Systems (Topic)","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114850393","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Structural Remedies in Network Industries: An Assessment of Slot Divestitures in the American Airlines/US Airways Merger","authors":"Yongjoon Park","doi":"10.2139/ssrn.3710262","DOIUrl":"https://doi.org/10.2139/ssrn.3710262","url":null,"abstract":"Asset divestitures are often negotiated to alleviate anticompetitive concerns created by horizontal mergers. I develop a structural model to evaluate the effectiveness of alternative slot divestiture schemes in the US airline industry, focusing on the divestiture of slots at Ronald Reagan Washington National Airport (DCA), which the government required as a condition of the American/US Airways merger. Departing from the existing literature, my model accounts for how the number of slots allocated to a route segment affects carrier costs, how passengers going to many different destinations may use the same segments, and how carriers choose to allocate slots to segments. I use counterfactuals to show that slot divestitures can result in the re-allocation of surplus between consumers; to estimate the proportion of slots that the merged American would have needed to divest to maximize total welfare; and, to evaluate the effects of allocating divested slots to different types of carriers. I find that the proposed divestiture raised consumer surplus significantly ($112M per year) compared to approving the merger without divestiture, but that it re-allocated surplus between consumers in different markets. I also find that the policy of only allowing the slots to be divested to low-cost carriers raised consumer surplus relative to the policy of only allowing the slots to be divested to legacy carriers.","PeriodicalId":151146,"journal":{"name":"TransportRN: Air Transportation Systems (Topic)","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127449648","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Selecting the Mutual Arrangement of the Engine and Wing in a Transport Aircraft for Short Take-off and Landing","authors":"V. Kudryavtsev, Borys Strigun, Volodymyr Shmyrov, V. Loginov","doi":"10.15587/1729-4061.2020.208639","DOIUrl":"https://doi.org/10.15587/1729-4061.2020.208639","url":null,"abstract":"In order to maintain the competitive advantage of the medium short take-off and landing transport aircraft, the task must be solved of ensuring take-off and landing on the ground runways with a length of 600‒800 m when installing a turbojet engine. When the engines are installed on the pylons under the wing, this is achieved by using a «forced» turn of the jet of engines when the flaps are released at an angle of 60°. We have found the mutual location of the wing and the engine on its stagger, based on the position relative to the construction plane of the wing and the angle of installation. A reciprocal arrangement has been determined, making it possible to maximize the lift force owing to the turn of the jet stream. It has been shown that this achieves the continuous flow around the sections of the flaps when they are deflected at a 60-degree angle. We have analyzed the temperature effect of the jet stream on the mechanization and the aircraft wing at the stages of take-off and landing at different positions of engines under the wing, at different flight speeds and angles of attack. The effect of mechanization on the distribution of jet stream speeds and temperatures has been analyzed. It is shown that decreasing the distance between the engine nozzle and the lower surface of the wing leads to an increase in the angle of the jet stream deviation. We have identified those tail section zones of the flap, which require special execution to operate at temperatures above 400 °C. The impact of the jet stream on aircraft’s drag in the cruising configuration has been analyzed, as well as the scheme of engine arrangement on the aircraft’s electrically dependent systems. We have shown the absence of the impact of the jet stream on the aircraft’s drag in the cruising configuration, the reduction of fuel consumption at cruising modes, as well as the favorable impact exerted on the electrically dependent systems due to the significant reduction of gas-dynamic losses along the power plant tract. Ways to modernize the transport aircraft type of An-70 have been proposed to ensure its superiority in its class","PeriodicalId":151146,"journal":{"name":"TransportRN: Air Transportation Systems (Topic)","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116770092","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Combining Economic and Search-Request Variables to Predict Local Airline Market Shares: A Comparison of Forecasting Methods","authors":"Paul Chiambaretto, Guillaume Coqueret","doi":"10.2139/ssrn.3636233","DOIUrl":"https://doi.org/10.2139/ssrn.3636233","url":null,"abstract":"Our aim in this article is to predict local airline market shares in the United States at the company level combining traditional economic indicators (at the national and local levels) with Google search engine requests. We resort both to simple econometric models and to more sophisticated machine learning tools (random forests, neural networks and support vector machines) and compare their respective predictive power. Using data from the American market for the period 2004-2018, our study bears three key findings. First, we highlight the usefulness of combining search-engine requests with other traditional economic indicators as explanatory variables to predict local airline market shares. Second, the comparison of the different forecasting techniques reveals that tree methods consistently outperform the alternative forecasting tools. Third, in line with the growing literature dedicated to frugal forecasting, we show that no advanced model is able to beat our heuristic benchmark, which consists in rolling increments of annual variations, such that variations in market shares are best predicted by past variations.","PeriodicalId":151146,"journal":{"name":"TransportRN: Air Transportation Systems (Topic)","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124921843","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Effects of Employee Hours-of-Service Regulations on the U.S. Airline Industry","authors":"Alexander Luttmann, Cody Nehiba","doi":"10.2139/ssrn.3099918","DOIUrl":"https://doi.org/10.2139/ssrn.3099918","url":null,"abstract":"Maximum employee work-hour restrictions are implemented to reduce accidents. However, because they decrease the stock of work-hours available to employers, they may also have detrimental effects. A quasi-experiment suggests that pilot hours-of-service reforms, which decreased the number of flights and hours a pilot may work, reduced consumer choice and increased fares in the airline industry. We find that regional and low-cost carriers reduced scheduled flight frequency, while less constrained legacy carriers (and potentially their wholly owned subsidiaries) were unaffected. Further, we find evidence that market concentration increased on many routes, implying that fare increases may be due to a decrease in competition. These findings illustrate a situation where a policy implemented to correct one market failure, airlines not internalizing the full social costs of accidents by allowing dangerously fatigued pilots to fly, exacerbated another market failure by decreasing competition.","PeriodicalId":151146,"journal":{"name":"TransportRN: Air Transportation Systems (Topic)","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123359646","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Систематизация антимонопольных рисков на рынках пассажирских авиаперевозок с учетом особенностей бизнес-стратегий авиакомпаний (Systematization of Antitrust Risks in the Passenger Air Transportation Markets Taking Into Account the Peculiarities of Airline Business Strategies)","authors":"A. Meleshkina, O. Markova","doi":"10.2139/ssrn.3596014","DOIUrl":"https://doi.org/10.2139/ssrn.3596014","url":null,"abstract":"<b>Russian Abstract:</b> Статья посвящена анализу реакции авиакомпаний-конкурентов на вход нового игрока на рынок. Данная проблема является актуальной в свете дискуссий вокруг методов стимулирования конкуренции на рынках пассажирских авиаперевозок. Решение назревших проблем в сфере гражданских авиаперевозок применительно к вопросам конкуренции требует переформатирования подходов отраслевой и антимонопольной политики. Перед регулятором стоит вопрос соблюдения баланса интересов авиакомпаний, поставщиков аэропортовых услуг и конечных потребителей – пассажиров. При этом необходимо определить направление реформирования – дерегулирование или государственное субсидирование. Данное исследование представляет собой попытку систематизации конкурентных стратегий, выбираемых авиаперевозчиками в ответ на изменение условий конкуренции. Результаты анализа могут иметь интерес с точки зрения построения прогнозов поведения авиакомпаний на разных маршрутах (рынках) при дерегулировании отрасли и увеличении числа конкурентов.<br><br><b>English Abstract:</b> The article is devoted to the analysis of the reaction of competing airlines to the entry of a new player into the market. This problem is relevant in the light of discussions around methods to stimulate competition in the passenger air transportation markets. Decision urgent problems in the field of civil air transportation in relation to competition issues require reformatting of approaches to industry and antitrust policies. The regulator is faced with the question of balancing the interests of airlines, airport service providers and end-users - passengers. In this case, it is necessary to determine the direction of reform - deregulation or state subsidies. This study is an attempt to systematize the competitive strategies chosen by air carriers in response to changing competition conditions. The results of the analysis may be of interest from the point of view of building forecasts of airline behavior on different routes (markets) with deregulation of the industry and an increase in the number of competitors.","PeriodicalId":151146,"journal":{"name":"TransportRN: Air Transportation Systems (Topic)","volume":"2014 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134040244","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Strategies of Anticompetitive Common Ownership","authors":"C. Hemphill, Marcel Kahan","doi":"10.2139/ssrn.3210373","DOIUrl":"https://doi.org/10.2139/ssrn.3210373","url":null,"abstract":"Scholars and antitrust enforcers have raised concerns about anticompetitive effects that may arise when institutional investors hold substantial stakes in competing firms. Their concern rests on empirical evidence that such common concentrated ownership is associated with higher prices and lower output. This evidence sharply challenges both antitrust orthodoxy and corporate governance scholarship. \u0000 \u0000In this Article, we examine the causal mechanisms that might link common ownership to anticompetitive effects. We consider whether the current empirical evidence supports the existence of these mechanisms and whether institutional investors would plausibly employ them. \u0000 \u0000Our main conclusion is that most proposed mechanisms either lack significant empirical support or else are implausible. Notably, some widely discussed mechanisms—for example, cartel facilitation and passive failures to encourage competition among portfolio firms—are not empirically tested. Moreover, institutional investors’ incentives to increase portfolio value are weak, reducing the likelihood that these investors will pursue mechanisms that carry significant reputational or legal risks. We find, however, that a different mechanism, which we call \"selective omission,\" is both consistent with the evidence and plausibly employed by institutional investors. Looking ahead, our analysis suggests paths for future research and provides a guide for further investigation into how common owners and firms may interact to produce anticompetitive effects.","PeriodicalId":151146,"journal":{"name":"TransportRN: Air Transportation Systems (Topic)","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115350067","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Whether, When and Which: Modelling Advanced Seat Reservations by Airline Passengers","authors":"Shuai Shao, G. Kauermann, M. Smith","doi":"10.2139/ssrn.3325346","DOIUrl":"https://doi.org/10.2139/ssrn.3325346","url":null,"abstract":"Motivated by the growing importance of ancillary revenues in the airline industry, we propose a statistical model for Advanced Seat Reservation (ASR). We focus on the questions of whether, when and which seats are selected by passengers. To answer these questions, we employ a discrete time duration model, combined with a multinomial choice model with varying consideration set. Unknown smooth covariate effects are used, along with seat-specific random effect terms for seat selection. The model is applied to a rich dataset of 485,279 bookings on five intercontinental routes, extracted from the complete booking database of a major European airline. We find strong evidence of ‘middle seat avoiding’ and ‘front seat preferring’ effects, along with substantial additional seat-specific heterogeneity. We also show that the probability of making an ASR depends on its price in relation to the ticket price, the distribution channel, the number of days to departure and seasonal effects. These and other insights allow for product differentiation and variable pricing in ASR for each and every seat. In addition, simple variations of the statistical model can also be used for other ancillary products—such as on-board dining and preferential baggage checking—that are purchased in the same way as ASR.","PeriodicalId":151146,"journal":{"name":"TransportRN: Air Transportation Systems (Topic)","volume":"158 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122854859","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}