40,835 research outputs found

    Airplane wing leading edge variable camber flap

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    The invention and design of an aerodynamic high lift device which provided a solution to an aircraft performance problem are described. The performance problem of converting a high speed cruise airfoil into a low speed aerodynamic shape that would provide landing and take-off characteristics superior to those available with contemporary high lift devices are addressed. The need for an improved wing leading edge device that would complement the high lift performance of a triple slotted trailing edge flap is examined. The mechanical and structural aspects of the variable camber flap are discussed and the aerodynamic performance aspects only as they relate to the invention and design of the device are presented

    Space station internal environmental and safety concerns

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    Space station environmental and safety concerns, especially those involving fires, are discussed. Several types of space station modules and the particular hazards associated with each are briefly surveyed. A brief history of fire detection and suppression aboard spacecraft is given. Microgravity fire behavior, spacecraft fire detector systems, space station fire suppression equipment and procedures, and fire safety in hyperbaric chambers are discussed

    Housing professionalism in the United Kingdom: the final curtain or a new age?

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    The unusually large, predominantly municipal, housing sector in the UK has provided the context for a large occupational grouping of "housing managers" that has claimed professional status. However, within the post-1945 British welfare state this professional project enjoyed limited success and social housing remained a fragile professional domain. This article explores the consequences for housing professionalism of the recent displacement of the bureau-professional "organisational settlement" by that characterising an emerging "managerial state". Managerialism constitutes a clear challenge to established forms of "professionalism", especially a weak profession such as housing management. However, professionalism is temporally and culturally plastic. Hence, the demands of managerialism, within the specific context of New Labour's quest for "community" cohesion, may be providing opportunities for a new urban network professionalism founded on claims to both generic and specific skills and also a knowledge base combining abstraction with local concreteness. The prominence in these networks of erstwhile "housing" practitioners may become the basis for a new, quite different, professional project. This argument is developed through both conceptual exploration and reference to empirical research. The latter involves reference to recent work by the authors on, first, the perception of housing employers of the changing nature and demands of "housing" work and its consequences for professionalism and, secondly, the professional project implications of the increasing prominence of neighbourhood management.</p

    Royale with Cheese: The Effect of Globalization on the Variety of Goods

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    The key result of the so-called “New Trade Theory” is that countries gain from falling trade costs by an increase in the number of varieties available to consumers. Though the number of varieties in a given country rises, it is also true that global variety decreases from increased competition wherein imported varieties drive out some local varieties. This second result is a major issue for anti-trade activists who criticize the move towards free trade as promoting homogenization” or “Americanization” of varieties across countries. We present a model of endogenous entry with heterogeneous firms which models this concern in two ways: a portion of a consumer’s income is spent overseas (i.e. tourism) and an existence value (a common tool in environmental economics where simply knowing that a species exists provides utility). Since lowering trade costs induces additional varieties to export and drives out some non-exported varieties, these modifications result in welfare losses not accounted for in the existing literature. Nevertheless, it is only through the existence value that welfare can fall as a result of declining trade barriers. Thus, for these criticisms of globalization to dominate, it must be that this loss in the existence value outweighs the direct benefits from consumption.firm heterogeneity; tourism

    Simulating study of the interaction between the propulsion and flight control systems of a subsonic lift fan VTOL

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    The possibility of interactions between the propulsion and flight control systems of a three-fan subsonic VTOL aircraft was studied using nonreal time simulation. Time histories of critical internal engine parameters were obtained and possible deleterious effects of engine dynamics on flight control were identified and analyzed. No deleterious effects, with the exception of the effects of the fan actuator deadband, were found. A method of alleviating these effects through feedback of the actuator output to the flight controller was developed

    Direct investment: a doubtful alternative to international debt

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    The paper considers a model in which private foreign investors make direct long-lived capital investments in a small developing country that is subject to stochastic shocks to production. Depending upon the preferences of the host country, we find that expropriation can occur because of either desperation or opportunism. We show that under reasonable assumptions, increased investment makes expropriation less likely to occur and that the level of investment chosen by atomistic foreign investors may be nonoptimal.International finance ; Developing countries

    Optimal Tariffs, Tariff Jumping, and Heterogeneous Firms

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    The majority of research to date investigating strategic tariffs in the presence of multinationals finds a knife-edge result where, in equilibrium, all foreign firms are either multinationals or exporters. Utilizing a model of heterogeneous firms, we find equilibria in which both pure exporters and multinationals coexist. We utilize this model to study the case of endogenously chosen tariffs. As is standard, Nash equilibrium tariffs are higher than the socially optimal tariffs. Unlike existing models with homogeneous firms, we find that non-cooperative tariffs promote the existence of low-productivity firms relative to the socially optimal tariffs. This highlights a new source of inefficiency from tariff competition not found in models of homogeneous firms. In addition, we find that in many cases the Nash equilibrium tariff when FDI is a potential firm structure is lower than when it is not. As a result, FDI improves welfare by mitigating tariff competition.Intra-industry Trade; Trade policy; Firm heterogeneity; Monopolistic competition
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