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Home>Products>Journal and Reviews>I.RE.AS.E.>Latest issue International Review of Aerospace Engineering - August 2008 - Papers
International Review of Aerospace Engineering - Papers
Abstract - The rationale behind the formation of airline alliances includes the reaping of scale and scope economies and the acquisition of marketing and branding advantages. To really add value to the airline customer, however, alliances should consider the purpose of travel, i.e. they should appreciate and understand the derived nature of the airline product. The relevant literature seems to understate this issue or at best focus on business passengers. Given the rising importance of leisure travel and tourism in the world economy, its implications should be explicitly assessed. The emergence of low cost carriers and the subsequent simplifications in the holiday packages offered by charter airlines have played a major role in boosting leisure travel in Europe at least. Still, the intelligent management of frequent flyer programmes and the creation of a seamless network in long haul (or even intercontinental) air travel may induce leisure passengers to opt for an allied airline instead. This paper addresses the topic by undertaking primary research in the form of semi-structured interviews with airline executives and structured questionnaires addressed to passengers. The interviewees are supportive of the view that alliances of network carriers may offer benefits to leisure passengers although they do recognise the competitive threat posed by low cost carriers. Similarly, the statistical analysis of the questionnaire results reveals that frequent flyers and more affluent respondents are more knowledgeable about strategic alliances and have a tendency to prefer allied carriers for long-haul but not for short-haul flights. This outcome may add to the understanding of airline alliances and consumer behaviour and have important implications for airline strategy at a global level. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: airline alliances, leisure travel, FFP, network, consumer behaviour.
Abstract - This paper presents, in the first part, the design and fabrication of a mini quadrotor helicopter for outdoor applications. The proposed autonomous flying object called XSF has some particularities such as oriented rotors, a large autonomy and a stable maneuverable aerial platform. The dynamic model proposed takes into account the gyroscopic and aerodynamic effects. In the second part, we present a stabilization strategy around a position of equilibrium. The model is highly nonlinear, we use a methodology based on the linearization and the backstepping control. The dynamic of the system involves six control inputs which will be computed to stabilize the engine with regard to external perturbations. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: micro UAV, design, modeling, simulation, stabilization.
Abstract - A 3D optimal trim trajectories planner algorithm for an autonomous plane is presented in this paper. This planner can generate a sequence of 3D elementary trajectories for a set of predefined waypoints in space. The proposed algorithm uses a sequence of five elementary trim trajectories to generate a three dimensional global trajectory in space. The trim property reduces significantly the complexity of the dynamical model and thus the resolution of the trajectory planning and tracking problems. This approach is based on the Bang-Zero-Bang strategy, taking into account the state and inputs constraints due to the vehicle dynamics, flight envelope and the actuators limitations. In this study, we demonstrate that this strategy satisfies the necessary optimality condition of Pontryaguin. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Autonomous plane, Trajectory generation, Ttrim conditions.
by G. Ngo Boum, P. Kulisa, S. Aknouche
Abstract -
Based on numerical simulations,
the losses mechanisms generated in supersonic turbine rotors are studied.
The flow pattern is mainly characterized by the presence of shock waves
which are responsible of the most part of the losses. The contributions
of aerodynamic conditions and geometrical parameters are evaluated for
different typical rotor blade. The study concludes that the shock waves
are the main origin of the losses.
Keywords: losses, supersonic flow, turbine, numerical simulation.
Abstract - This paper deals with a nonlinear feedback control method based on Lie derivatives for the navigation guidance of unmanned aerial vehicles (UAVs). The paper proposes a modelling concept for planar and three-dimensional navigation together with proven algorithms to cope with the autonomous navigation along waypoints and on loiters. The steps that were performed in order to validate the autonomous navigation method are clearly described. The method was successfully validated on various realistic navigation scenarios for unmanned aircraft. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Navigation Guidance, UAV, Nonlinear Contol, Lie Derivatives, Waypoints, Loiters.
Abstract - A consortium of organizations has proposed an experiment to map Earth’s high-latitude electric field. The High-latitude Dynamic E-Field (HiDEF) Explorer will observe poorly understood magnetosphere, ionosphere, and thermosphere phenomena. Utah State University Space Dynamics Laboratory is responsible for systems engineering and mission planning for achieving science objectives. A constellation of 90 pico-satellites is deployed at high latitudes over a range of inclinations and altitudes increments that evolve from a densely-packed cluster to a fully global high-latitude coverage over a period of approximately 18 months. Planned constellation “fold-out” allows measurements of high latitude electric fields over wide spatial and temporal scales. Launch and deployment analysis including operational constraints, constellation foldout, and orbit lifetime predictions are described. The deployment analysis recommends a lowest-risk option using Orbital Sciences Corporation Pegasus XL launch vehicle with the Hydrazine Auxiliary Propulsion System (HAPS) system as an upper stage. Pegasus deploys the payload into an initial orbit, and the HAPS delivers the constellation elements to desired initial orbits using a series of 10 burns including an initial trim burn, on-orbit maneuvers, and de-orbit. The paper concludes that using the Pegasus/HAPS option, the required orbits can be achieved with reasonable weight-growth margins but little ΔV margin. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: magnetosphere, thermosphere, ionosphere, electric field, pico-satellite.
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