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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.

On minimum time vehicle manoeuvring : the theoretical optimal lap

Casanova, D. January 2000 (has links)
This work is a research on the minimum time vehicle manoeuvring problem, with a particular application to finding the minimum lap time for a Formula One racing car. The proposed method allows to solve the general problem of evaluating the vehicle lateral and longitudinal controls which yield the minimum time required to traverse a lap of a circuit. The minimum time vehicle manoeuvring problem is formulated as one of Optimal Control and is solved using mathematical programming methods. Novel techniques are employed to solve the resulting non-linear programming problem which allow to achieve effective optimisation with satisfactory accuracy, robustness and computational efficiency. Particularly, the proposed solution strategy is generally applicable to any arbitrarily complex vehicle mathematical model. Car and circuit models are set up, and the optimisation program is applied to investigate the sensitivity of the vehicle performance with respect to vehicle design parameters, such as the yaw moment of inertia, the total mass and the weight distribution. Furthermore, the minimum time manoeuvring problem is solved for very different vehicle configurations. The optimisation program accurately quantifies the vehicle performance in terms of manoeuvre time, and the nature of the optimal solution is shown to be always in excellent agreement with the dynamic properties of the vehicle model. A part of the work is devoted to the development of a strategy to obtain an initial estimate of the racing line and of the vehicle lateral and longitudinal controls to be used at the start of the optimisation. Two algorithms to compute the racing line using on board measured data from the real car are presented. A new mathematical model for the vehicle steering control is derived. The model uses multiple preview information of the intended path. Its structure derives from linear optimal preview control theory, but it is adapted to deal with non-linear vehicle operations arising from the inevitable tyre force saturation in vigorous manoeuvring. The excellent path following capability of the model is demonstrated by solving various path following tasks involving moderate manoeuvring and racing speeds.

The performance of passive and semi-active suspension for heavy lorries

Besinger, Frank Helmut January 1992 (has links)
No description available.

An investigation into the loss mechanisms associated with a pushing metal V-belt continuously variable transmission

Akehurst, Sam January 2001 (has links)
No description available.

The acoustic modelling of dissipative elements in automotive exhausts

Kirby, Raymond January 1996 (has links)
The mathematical modelling and experimental testing of both dissipative silencers and catalytic converters is reported here, although dissipative silencers are of primary interest. The models examined are formulated with a view to introducing them into commercial software aimed at the acoustic design of automotive exhaust systems.The porous materials which are commonly employed in dissipative silencers are examined first, and a semi-empirical model is formulated in order to predict the bulk acoustic properties of four different fibrous materials. Perforated tubes are also commonly employed in dissipative silencers separating the central channel from the absorbent, and the effects of both grazing flow and a backing layer of porous material upon the acoustic impedance of a perforate plate are examined.Three different theoretical approaches to modelling dissipative silencers are reported, and the accuracy of each method is assessed in the light of experimental sound transmission loss data measured for five different dissipative silencers. Mean flow in the central channel is a feature of each model, in addition to the use of the new semiempirical models for the perforated tube and the absorbent. A simple fundamental mode model is examined first, employing a straightforward analytical solution. More complex models are then investigated, incorporating finite element numerical methods. First, a fully general finite element model is examined and transmission loss predictions are obtained using both two and three dimensional meshes. A less complex eigenvalue solution, which also employs the finite element method, is examined next but this does not require such a high degree of computational effort. Predictions for finite length silencers are subsequently obtained using three different mode matching formulations. An examination of the accuracy of the predictions obtained using the different mathematical models is then carried out, from which conclusions are made concerning the future usefulness of each model in commercial design software. Finally, the effects of both mean flow and an axial temperature gradient upon the transmission loss of catalytic converters are examined. The relative influence the catalytic converter exerts sound attenuation, as compared to dissipative silencers, is also discussed.

The investigation and modelling of the steel compression V-belt continuously variable transmission

Micklem, J. D. January 1994 (has links)
No description available.

An historical geography of the rural tramways of Loir-et-Cher (France) from c. 1880 to 1934

Turner, Richard Henry January 1998 (has links)
No description available.

An analysis of disc brake noise using holographic interferometry

Fieldhouse, John David January 1993 (has links)
A predominantly experimental approach using the whole body visual technique of holographic interferometry is employed to investigate the mechanisms involved during a noisy brake application. Following the modal analysis of component parts, dynamic trials include the development of the holographic technique, making use of mirrors to permit three orthogonal views of the brake to be recorded simultaneously with smaller inset mirrors allowing for additional areas, such as the ends of the piston pad, to be observed at the same time. These dynamic experiments take the form of changing the operating parameters of the brake through variations in speed, pressure and temperature and through changes in the system geometry by adjustment of pad abutment and pad centre of pressure loading. The tests show that pad abutment plays an important role in the propensity of the system to generate noise and that a relationship between pad abutment, pad material coefficient of friction and interface coefficient of friction between pad-end and calliper-support finger exists which results in an offset in the pad centre of pressure with the spragging angle being satisfied and resulting noise. This is supported by basic theory. Additionally it is shown that the disc/pad interface relationship is complicated and that it is not reasonable to assume mechanical integrity of the pair and as a consequence the use of an "equivalent mass" is not appropriate for high aspect ratio pads. Advancements in the laser triggering process allow for holograms to be taken at specific stages over and along a cycle of excitation by delaying the laser triggering initiation to give variable time delays. The variety of techniques available are used to show that pad excitation plays an important role in the generation of noise and that the piston pad in particular is seen as the initiator leading to system excitation. Mechanical coupling of the component parts is also seen to be fundamental, but not essential, to the generation of noise. The techniques also show that, when complete coupling exists, the disc holds a diametral mode of vibration which travels around the disc at a speed related to the excitation frequency divided by the disc mode order. Results from the application of the techniques also allows component parts to be analysed over a typical cycle of excitation when it is shown that symmetrical components such as the pad are not necessarily excited in a symmetrical manner. Phase relationship between the component parts may also be determined by comparison of related holograms. Holographic interpretations are confirmed and validated by mechanical measurements when it is also demonstrated that noise is often preceded by, or accompanied by, a high frequency excitation which is experienced by the complete brake.

Aerodynamic loads on a railway train in a cross-wind at large yaw angles

Chiu, Tak Wai January 1990 (has links)
No description available.

An investigation of the dynamic interaction between wheeled vehicles and road surfaces

Cebon, D. January 1985 (has links)
No description available.

Ground movements associated with tunnels and trenches

Taylor, R. N. January 1984 (has links)
No description available.

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