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Item Open Access Airline Business Models and their respective carbon footprint: Final report(Manchester Metropolitan University, 2009-01) Mason, Keith J.; Miyoshi, ChikageThe choices that airlines make about the aircraft they fly, the number of seats they have on each aircraft, the routes they fly and the passenger segments they focus on have significant impacts on their environmental performance (which can be assessed in terms of an airline’s CO2 emissions per passenger kilometre, fuel burn or other suitable metric). Each of the main airline business models (network, charter, low cost carrier (LCC), regional) involves practices that may improve or degrade environmental performance. This project analyses the factors that affect each business model’s environmental performance and considers the potential for changes to business models to improve the environmental sustainability of the aviation sector. The evolution of aircraft fuel consumption, average sector length and CO2 emission levels (per passenger kilometre) were investigated. From 1986 to 2004 total fuel consumed by European airlines1 increased by 220%, while the amount of fuel consumed per passenger km has decreased by 27% (or 2% per year). Average distance flown has increased by 21% and the average number of passengers carried per flight by 5%. The CO2 emissions of intra-EU air services from the UK generated by each business model (network, LCC, charter, regional) was established for the years 1997, 2000 and 2006. Emissions were estimated by route, stage length, aircraft type used, number of seats supplied on each aircraft and the distance flown, following the IPCC recommended approach to carbon dioxide calculation. The LCCs share of total emissions has risen to 46% of all intra-EU routes originating in the UK in 2006 from 12% in 1997. At 112g/pkm this group’s CO2 emissions are lower than either network carriers or regional airlines (at 144g/pkms and 216g/pkms respectively) in the EU market. However the lowest emissions level is achieved by charter airlines at 106g/pkm. Some activities airlines have undertaken to reduce on-board weight were also considered. These include reducing water carriage, lowering tankered fuel levels and re-designing the duty free sales process. A calculator that estimates the carbon dioxide emissions that can be prevented by removing weight from a number of aircraft types was developed. It estimates that 456.2 tonnes of CO2 emissions can be prevented if an airline operating a daily North Atlantic service with a Boeing 747-400 could reduce 1 tonne (metric) from its takeoff weight. One of the main policy instruments that can internalise the environmental costs of aviation is the European Emissions Trading Scheme. Prior to its introduction the UK government has increased its Air Passenger Duty as a quasi-environmental taxation measure. The success of such fiscal measures in dampening the demand for air transport will largely depend on the price elasticity of demand and indicative ranges for long and short haul leisure and business passengers are given. A model of air transport CO2 emissions, which was developed to test various scenarios, suggests that should current growth rates continue, emissions for the global aviation market may grow by over 50% between 2009 and 2020. With high growth rates, the share of emissions for low cost carriers would also grow significantly, however, it is also clear that network carrier’s growth of long haul flying also means that the absolute emissions levels of this group is also likely to rise. The output of the model is used to test the sensitivity of changes to business model, such as increasing load factors, increasing the number of seats on board an aircraft, and differing growth rates for each business model. A stakeholder workshop and seminar for this project and a sister Omega project “Passenger Expectations” was held in December 2008. Key outcomes of the seminar was that passengers seem to have little appetite for changes in behaviour (such as willingness to take fewer longer overseas holidays or to holiday within the UK) that might reduce the demand for air services and that further passenger education regarding the relative impact of flying compared to other GHG generating activities is required. Further research is required to assess passenger willingness to forego service levels, timetable frequency, flight times to maximise load factors, minimise aircraft weight and therefore fuel consumption. Future studies may extend this work in two ways: assessing the feasibility of fully adopting the various weight reduction strategies suggested for airlines; and by investigating network carriers’ freight operations as a source of carbon dioxide emissions. Keith Mason and Chikage Miyoshi Cranfield University March 2009Item Open Access Design evaluation and performance assessment of rotorcraft technology by 2050(Netherlands Aerospace Centre (NLR), 2019-09-17) Stevens, Jos; Rademaker, Edward; Scullion, Calum; Vouros, Stavros; van Oosten, Nico; Misté, Gianluigi; Venturelli, Giovanni; Nalianda, Devaiah; Pachidis, Vassilios; Benini, ErnestoThe extended Clean Sky Joint Technology Initiative (JTI) within the EU Horizon 2020 Framework Programme [Ref. 1] proposes to introduce a number of concept aircraft and rotorcraft to replace reference technology counterparts at different time scales (2020/2035/2050). This Clean Sky 2 (CS2) promotes the importance of those concept configurations and their application in the future. An increasing global demand within and outside the European Union (EU) for an efficient air mobility and transportation system (i.e. more flexible, resilient, effective and affordable), and future projected growth for its application, will lead to the requirement for development of highly optimised transportation solutions.Item Open Access Fast non-monotone submodular maximisation subject to a matroid constraint(2017-03-21) Segui-Gasco, Pau; Shin, Hyo-SangIn this work we present the first practical . 1 e −ǫ . -approximation algorithm to maximise a general non-negative submodular function subject to a matroid constraint. Our algorithm is based on combining the decreasing-threshold procedure of Badanidiyuru and Vondrak (SODA 2014) with a smoother version of the measured continuous greedy algorithm of Feldman et al. (FOCS 2011). This enables us to obtain an algorithm that requires O( nr2 ǫ4 . ¯ d+ ¯ d ¯ d .2 log2 ( n ǫ )) value oracle calls, where n is the cardinality of the ground set, r is the matroid rank, and ¯ d, ¯ d ∈R+ are the absolute values of the minimum and maximum marginal values that the function f can take i.e.: − ¯ d ≤fS(i) ≤ ¯ d, for all i ∈E and S ⊆E, where E is the ground set. The additional value oracle calls with respect to the work of Badanidiyuru and Vondrak come from the greater spread in the sampling of the multilinear extension that the possibility of negative marginal values introduce.Item Open Access Optimising UCNS3D, a High-Order finite-Volume WENO Scheme Code for arbitrary unstructured Meshes(Partnership for Advanced Computing in Europe, 2016) Ponweiser, Thomas; Tsoutsanis, PanagiotisUCNS3D is a computational-fluid-dynamics (CFD) code for the simulation of viscous flows on arbitrary unstructured meshes. It employs very high-order numerical schemes which inherently are easier to scale than lower-order numerical schemes due to the higher ratio of computation versus communication. In this white paper, we report on optimisations of the UCNS3D code implemented in the course of the PRACE Preparatory Access Type C project “HOVE” in the time frame of February to August 2016. Through the optimisation of dense linear algebra operations, in particular matrix-vector products, by formula rewriting, pre-computation and the usage of BLAS, significant speedups of the code by factors of 2 to 6 have been achieved for representative benchmark cases. Moreover, very good scalability up to the order of 10,000 CPU cores has been demonstrated.Item Open Access Preliminary guidelines for the rotorcraft certification by simulation process: update no. 1, March 2023(Rotorcraft Certification by Simulation (RoCS), 2023-03) Padfield, Gareth D.; vant' Hoff, Stefan; Lu, Linghai; Podzus, Philip; White, Mark; Quaranta, GiuseppeThis document presents preliminary Guidance for the application of (rotorcraft) flight modelling and simulation in support of certification for compliance with standards CS-27 and CS-29, PART B (Flight) and other Flight related aspects (e.g. CS-29, Appendix B, Airworthiness Criteria for Helicopter Instrument Flight). The Guidance is presented in the form of a structured process, starting from the relevant paragraphs in the Certification Specifications, through a comprehensive description of the assembly of flight simulation requirements, informed by judgements on Influence, Predictability and Credibility, and on into the detailed building of the three major elements of the process: • the flight simulation model (FSM), • the flight simulator (FS), and • the flight test measurement system (FTMS). The FTMS feeds both the flight model and simulator development with real-world test data to support validation and fidelity assessment. A structured and systematic approach to data/configuration management and documentation is recommended, aided by the creation of the Rotorcraft Certification by Simulation (RCbS) project management plan. This is the first update of the RCbS Guidelines and includes modifications based on the first round of feedback received before and after the European Rotors RoCS workshop held in Cologne on November 9th 2022. The Guidelines will continue to be updated, as appropriate, with the next major revision to include exercising the process in case studies based on applicable certification requirements from EASA CS-27 and CS-29 (to appear in Section 10). In the current update, the RoCS team have also addressed the issue of resourcing the RCbS process (within Section 9) and suggested potential next steps for aspiring applicants (new Section 11).