No description available.

Designing successful commercial aircraft is a difficult business; the stakes are high and the risks numerous. Researchers in the past have developed methods that assist the designers in reducing these risks. In recent years such methods have benefited from improvements in computer technology. The work described in this thesis extends these methods to the design of commuter aircraft. These aircraft are more sensitive to operational requirements than other types due in part to their high zero-fuel mass ratio. It is essential that, for such aircraft, the best information possible is available to the designers. The identification of the optimum aircraft configuration and mission characteristics constitutes a vital part of this knowledge. A review of literature, involving both modem computer-based and traditional search methods, has shown continuing interest in aircraft project design methods from the earliest times to the latest conference. The work presented in this thesis is seen to compliment this interest in computer methods and to apply these techniques to the relatively neglected area of commuter aircraft design. A survey of commuter operation and aircraft types revealed the often conflicting requirements and regulations which govern the design process in this area. Detailed statistical analysis on a collection of commuter aircraft showed no consistent data patterns, but did indicate the bouyant state of the market. Earlier research work on the design of twin-engined turbo-prop aircraft had provided some experience in the design of short-haul aircraft. The new work improves these methods and applies them to larger and faster turbo-fan commuter aircraft. Since the turbo-prop work, the optimiser developed at RAE (Farnborough) has been rewritten to work more efficiently and allow larger problems to be tackled. This new optimiser s linked to a new synthesis routine which simulates turbo-fan aircraft design. The synthesis program was calibrated against industrial design calculations and shown to give acceptably accuracte predictions. The resulting design program is fully described and computer listings are presented. To illustrate the use of the optimisation methods in the devleopment of a new aircraft, a series of industrially related design studies is presented. These studies range from the selection of the initial baseline configuration, through various parameters sensitivity investigations, to the evaluation of aircraft and engine stretch options. To demonstrate more general types of design study, a series of optimisations in which the engine size is variable was conducted. This provides the designer with a knowledge of the absolute (optimum) design surface and allows him to judge the 'penalties' inherent in his chosen configuration.

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Vertical/Short Take-Off arid Landing (V/STOL) fighter aircraft are characterised by increased control complexity caused by the extra degree ol freedom. This can result in a high pilot workload which may be alleviated with the careful application of active flight control. However, the advent of control configured vehicles demands that the controller design must be part of a fully integrated and iterative aircraft design; hence it must allow the two-way flow of design information. In this thesis a suitable controller design method is developed to solve this two-fold problem. The method is based upon a singular perturbation analysis which is used to expose the underlying dynamics of a closed-loop state-space system. developments are described which allow high-order, dynamically complex parasitics, such as actuators, to be included in the design. Furthermore, the method gives the designer insight into the problem allowing tuning and engineering trade-offs to be performed intelligently with a two-way flow of design information. The end result is a robust high-gain multivariable controller. In order fully to develop arid analyse the method it has been applied to a representative non-linear time-varying aircraft simulation model. This LS supplied by the Royal Aerospace Establishment, Bedford. The necessary slate-space matrices are otitairted by lirLearisirig the model at several different flight cases. This occurs over a wide flight envelope, from hover to 300 Kts, and consequently the multivariable control laws are implemented using gain scheduling. Finally, task tailored control and handling qualities requirements are derived for a V/STOL aircraft in the form of a design brief. This design brief is then fulfilled by designing a controller which alleviates pilot workload during transitions from jet-borne to fully wing-borne flight (and vice versa).

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This thesis introduces the application of discrete Principal Component Analysis (PCA) to corporate governance research. Given the presence of many discrete variables in typical governance studies, I argue that this method is superior to standard PCA that has been employed by others working in the area. Using a dataset of 244 companies listed on the London Stock Exchange in the year 2002-2003, I find that Pearson's correlations underestimate the strength of association between two variables, when at least one of them is discrete. Accordingly, standard PCA performed on the Pearson correlation matrix results in biased estimates. Applying discrete PCA on the polychoric correlation matrix, I extract from 28 corporate governance variables 10 significant factors. These factors represent 8 main aspects of the governance system, namely auditor reputation, large shareholder influence, size of board committees, social responsibility, risk optimisation, director independence level, female representation and institutional ownership. Finally, I investigate the relationship between corporate governance and a firm's long-run share market performance, with the former being the factors extracted. Consistent with Demsetz' (1983) argument, I document limited explanatory power for these governance factors.

Thesis (Ph. D.)--University of Hong Kong, 2000. / Includes bibliographical references (leaves 278-292).

Thesis (M.S.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains vi, 67 p. : ill. (some col.), col. maps. Includes abstract. Includes bibliographical references (p. 65-67).

Thesis (Ph. D.)--Lehigh University, 2006. / Includes vita. Includes bibliographical references (leaves 163-173).