1000 resultados para Aeronàutica


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The ability to reproduce reduced gravity conditions for long periods is one of the reasons why the orbiting laboratory is so attractive. In this paper several fluid dynamics problem areas are reviewed in which zero-gravity conditions are of great importance. Although emphasis is placed on space processing, there are some older problems also in which gravity masks the phenomcna, impeding a reasonably simple approach to the solution. Three problems are considered: Thermal convection under reduced gravity. The dumping effect ofsurface gravity waves at the outset of convection induced by surface tractions is discussed in particular. The existence of convection is of concern for some satellite thermal control techniques presently used, and for most of the proposed manufacturing processes. Whereas convection should be normally avoided, problems related to the containerless stirring ofa melt constitute an exception. Secondly, gravity and chemical reactions. Although chemical reactions are independent of gravity because of the small mass of the molecules and atoms involved, in many cases the reaction rate dcpends on the arrival of the species to the reaction zone. When the arrival process is buoyancy-controlled, the net specd of the reaction will be affected by the gravity. Thirdly, two-phase flows under reduced gravity provkle interesting problems from boiling heat transfer to degasslng of melts. This part of the paper deals only with the measurement of sound veiocity in a liquid containing bubbles. It is suggested that such measurements should be mude under reduced gravity to provide reliable residís.

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Some floating-liquid-zone experiments performed under reduced-gravity conditions are reviewed. Several types of instabilities are discussed, together with the relevant parameters controlling them. It is shown that the bounding values of these parameters could be increased, by orders of magnitude in several instances, by selecting appropriate liquids. Two of the many problems that a Fluid-Physics Module, devised to perform experiments on floating zones in a space laboratory, would involve are discussed: namely (i) procedures for disturbing the zoneunder controlled conditions, and (ii) visualisation of the inner flow pattern. Several topics connected with the nonisothermal nature and the phase-changes of floating zones are presented. In particular, a mode of propagation through the liquid zone for disturbances which could appear in the melting solid/liquid interface is suggested. Although most research on floating liquid zones is aimed at improving the crystal-growth process, some additional applications are suggested.

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El concepto de seguridad ha estado siempre ligado al de aeronáutica pues no existe prácticamente ningún otro sector en el que ésta posea mayor relevancia. El concepto de certificación surge como extensión del anterior, culmina y garantiza la total seguridad de la aeronave.La certificación comenzó aplicándose a las aeronaves (certificado tipo de aeronave)hasta llegar a nuestro días en los que la certificación como Operador se ha convertido en un requisito indispensable para la operación o constitución de cualquier aerolínea. Es aquí donde se enmarca el objetivo del presente estudio. IOSA es una normativa certificación de aerolíneas creada por la IATA. IATA es un organismo regulador del transporte aéreo por un grupo de compañías aéreas. IOSA supone un programa de auditoría reconocido internacionalmente, que está abierto a todas las compañías aéreas. Desde 2008, ha sido obligatoria para todos los miembros de la IATA. Su objetivo es mejorar la seguridad y reducir el númemero de autitorías que mejora la industria. Los estudios realizados por IATA en la última década revelan que las compañías aéreas certificadas con IOSA han superado a las que no han aplicado este certificado en materia de seguridad.

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The aeronautical charts are a convenient means to provide aeronautical information in a manageable, condensed, and coordinated way. Despite having an extensive regulatory legislation backed by the International Civil Aviation Organization (ICAO), this kind of specialized mapping is defined by a marked symbolical disparity between the different editions published by countries and publishers. This implies not to follow the uniformity and consistency principles that ICAO have identified as essential to help ensure the safety of international civil aviation. Plans for the implementation of a global interoperability of aeronautical information require urgently rethink the way in which, so far, this information has been published and disseminated. A single, transverse, and independent symbolical specification would contribute to the generation of a well defined final-product that provides general purpose aeronautical information for an unequivocal interpretation. The contribution of this article is the verification of the real possibilities for the definition of a general specification that provides the mechanisms for a reliable, indisputable, and legible reading of aeronautical charts under any operational circumstances and conditions. Such conditions must be aligned with the specificities of any country, publishers or crew.

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Aeronautical charts underlie the representation of aeronautic geographic information that supports pilots in flight. Nevertheless, charts become complex due to the high density of data and the different kinds that support each phase of flight. These features make difficult using them on board. After conducting a study that aims to understand and to evaluate pilot’s needs related to Geographic Information, it is proposed a solution to implement a platform based on geographic information standards (OGC, ISO) and supported by a distributed Web architecture. This platform facilitates the use, retrieval, updating of information and its exchange among different institutions through private and public users. As a first element to ensure interoperability and the harmonisation of information, we propose an aeronautical metadata profile that sets guidelines and elements for its description. This profile meets the standards set by ICAO, Eurocontrol and ISO. The platform offers three levels of access to data through different types of devices and user profiles. This paper suggests an alternative and reliable way for distributing aeronautical geoinformation, focusing on specific functions or displaying and querying.

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The aeronautical information plays an essential rolein air safety, chief objective of the aeronautical industry. Community policies and projects are being currently developed for the adequate management of a single European air space. To make this possible, an appropriate information management and a set of tools that allow sharing and exchanging this information, ensuring its interoperability and integrity, are necessary. This paper presents the development and implementation of a metadata profile for description of the aeronautical information based on international regulations and recommendations applied within the geographic scope. The elements taken into account for its development are described, as well as the implementation process and the results obtained.

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Aeronautical charts underlie the representation of aeronautic geographic information that supports pilots in flight. Nevertheless, the charts become complex due to the high density of data and the different kinds of charts that support each phase of flight. These features make difficult using them on board. After conducting a study, with civil Spaniard pilots, that aims to understand and to evaluate their needs related to Geographic Information, it is proposed a solution to implement a platform based on geographic information standards (OGC, ISO) and supported by a distributed Web architecture. This platform facilitates the use, retrieval, updating of information and its exchange among different institutions through private and public users. As a first element to ensure interoperability of information, we suggest an aeronautical metadata profile that sets guidelines and elements for its description. The metadata profile meets the standards set by ICAO, Eurocontrol and ISO. The platform offers three levels of access to data through different types of devices and user profiles. Thus, aeronautical institutions could edit data while pilot is on board accessing digital aeronautical charts through a laptop or Table PC. This paper suggests an alternative and reliable way for distributing aeronautical geoinformation, focusing on specific functions or displaying and querying.

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Cadmium has been widely used as a coating to provide protection against galvanic corrosion for steels and for its natural lubricity on threaded applications. However, it is a toxic metal and a known carcinogenic agent, which is plated from an aqueous bath containing cyanide salts. For these reasons, the use of cadmium has been banned in Europe for most industrial applications. However, the aerospace industry is still exempt due to the stringent technical and safety requirements associated with aeronautical applications, as an acceptable replacement is yet to be found. Al slurry coatings have been developed as an alternative to replace cadmium coatings. The coatings were deposited on AISI 4340 steel and have been characterized by optical and electron microscopy. Testing included salt fog corrosion exposure, fluid corrosion exposure (immersion), humidity resistance, coating-substrate and paint-coating adhesion, electric conductivity, galvanic corrosion, embrittlement and fatigue. The results indicated that Al slurry coatings are an excellent alternative for Cd replacement.

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Innovations in the current interconnected world of organizations have lead to a focus on business models as a fundamental statement of direction and identity. Although industry transformations generally emanate from technological changes, recent examples suggest they may also be due to the introduction of new business models. In the past, different types of airline business models could be clearly separated from each other. However, this has changed in recent years partly due to the concentration process and partly to reaction caused by competitive pressure. At least it can be concluded that in future the distinction of different business models will remain less clear. To advance the use of business models as a concept, it is essential to be able to compare and perform analyses to identify the business models that may have the highest potential. This can essentially contribute to understanding the synergies and incompatibilities in the case of two airlines that are going in for a merger. This is illustrated by the example of Swiss Air-Lufthansa merger analysis. The idea is to develop quantitative methods and tools for comparing and analyzing Aeronautical/Airline business models. The paper identifies available methods of comparing airline business models and lays the ground work for a quantitative model of comparing airline business models. This can be a useful tool for business model analysis when two airlines are merged