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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Application of bifurcation analysis to multiple attractor flight dynamics

Lowenberg, Mark H. January 1998 (has links)
No description available.
2

The impact of exchange rates on air traffic demand

Patch, T. J. January 1990 (has links)
No description available.
3

Real-time helicopter modelling using transputers

Lawes, Stephen Thomas January 1994 (has links)
No description available.
4

Transport aircraft programme management

Barfield, N. January 1982 (has links)
No description available.
5

The influence of surface treatments on the fatigue properties of an AL-LI-CU-MG-ZR (8090) alloy

Bolam, Vivienne Jane January 1991 (has links)
No description available.
6

Fatigue crack growth in pin-loaded lugs

Moon, J. E. January 1983 (has links)
No description available.
7

Changes in the air transport industry and the consequences for the region : a case study of three UK airports

Dawson, Catherine Linda January 1989 (has links)
No description available.
8

Design of multi-functional flight controllers for structural load alleviation

Burge, S. E. January 1984 (has links)
No description available.
9

Optimal positioning of a load suspended from a station-keeping helicopter

Tsitsilonis, Lucas January 1981 (has links)
Controlling the position and attitude of a helicopter hovering in the presence of atmospheric turbulence is a difficult task which demands considerable pilot work-load which becomes even more difficult'when a load is suspended from the helicopter, because the oscillations of the load aggravate the situation. Tasks that require a suspended load to be kept fixed relative to a point in space, while the helicopter remains at hover, are extremely difficult to achieve. Several load-positioning systems exist but provide inadequate solutions to the problem. A brief account of such systems and their limitations is given before describing the automatic hovering control system proposed in this thesis. It causes appropriate motion of the helicopter to achieve the desired stationarity of the load. The techniques of modern control theory were employed to design this optimal controller. Digital simulation was used for testing the response of the resulting optimal system. The mathematical model of two connected rigid bodies moving in space (representing the helicopter and suspended load) is described in detail. Several combinations of cable length-load weight were chosen and in each case the response of the closed-loop system was investigated. It was found that considerable reduction of the oscillations of the load can be achieved when suitable cable arrangements are used. The use of winch control of lateral displacement of the load also improves the lateral response of the entire system. An augmented mathematical model was used which included both the dynamics of the control actuators and the models representing atmospheric turbulence and sensor noise. Since many of the state variables of the system cannot be physically measured, it is obvious that only limited information on the state of the system would be available for processing by such a controller. Therefore two solutions to the problem were considered: (i) the use of a state estimator to provide to the controller the lost feedback information; , and (ii) the use of an output regulator which takes into account the fact that limited feedback information is available. The responses of the closed-loop systems using each of these solutions were investigated and compared. The numerical problems encountered in this design are analysed and some means .of overcoming them are suggested. Finally, the best combination of cable arrangement and controller is described with reference to several important factors such as system simplicity and performance.
10

Development of safety and reliability prediction methodology for aircraft systems with common-cause failures

Nam, G. W. January 1996 (has links)
A methodology has been developed for predicting aircraft safety and reliability incorporating both C.C.F.s(Common-Cause Failures), and phased missions. Failure behaviour of an aircraft, or its systems due to both independent failures and C.C.F.s are modelled by the Markov process, and simulated using Monte Carlo method with the robust variance reduction techniques. Prediction of safety and reliability is made through discrete-event simulation of aircraft operations. Validation was made by comparing the predicted safety and reliability results of B767 ETOPS aircraft propulsion system, using the developed methodology, to those obtained from the analysis of real operation data. The credibility and the accuracy of the developed methodology are shown through the comparison of results. A case study was conducted for investigating the safety and reliability of the propulsion system of two-, three- and four-engined aircraft using the developed methodology. The case study produced valuable results concerning the safety of ETOPS flight, which were not previously known. These results were able to be used for further trade studies of aircraft design to decide the number of engines, and also for establishing new regulations for ETOPS flights.

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