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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.
161

Probabilistic Seismic Demand Model and Fragility Estimates for Symmetric Rigid Blocks Subject to Rocking Motions

Bakhtiary, Esmaeel 02 October 2013 (has links)
This thesis presents a probability model to predict the maximum rotation of rocking bodies exposed to seismic excitations given specific earthquake intensity measures. After obtaining the nonlinear equations of motion and clarification of the boundaries applied to a rocking body to avoid sliding, a complete discussion is provided on the estimation of approximate period and equivalent damping ratio for the rocking motion. Thereafter, instead of using an iterative solution, which was previously proven defective, a new approximate technique is developed by finding the best representative ground motion intensities. Suitable transformation and normalization are applied to these intensities, and the Bayesian Updating approach is employed to construct a probability model. The proposed probability model is capable of accurately predicting the maximum rotation of a symmetric rocking block given displacement design spectra, peak ground acceleration, peak ground velocity, and arias intensity of an earthquake. This probabilistic model along with the approximate capacity of rocking blocks are used to estimate the fragility curves for rocking blocks with specific geometrical parameters. At the end, a comprehensive and practical form of fragility curves and numerical examples are provided for design purposes.
162

Turbo-generator responses due to the Alford force, the steam excitation force and the dominant unbalanced magnetic pull

Cai, Zhemin, Mechanical & Manufacturing Engineering, Faculty of Engineering, UNSW January 2009 (has links)
In turbomachinery, extra excitation forces may result from non-idealised operation conditions and may sometime cause excessive vibrations and unsteady rotor motions. The goal of this thesis is to investigate the effects of such excitation forces. The extra excitation forces investigated here are the Thomas/Alford force due to the blade tip clearance change, the steam excitation force caused by the variation of inlet steam speed and state blade trailing wake and the dominant magnetic pull force due to dynamic eccentricity of the rotor. The main research results in this thesis include: (1) The modelling of the Jeffcott rotor and the 600MW steam-turbine generator. The used in-house ??transient?? program can only handle the circular short bearings with the modified short bearing method while the simulated steam-turbine should be supported by tilting pad bearings. The first critical speeds of systems supported by tilting pad bearings are more approaching to the lab data for all four rotor models while that of journal bearing supported systems are normally lower than the real operating critical speed. (2) Applying three sorts of excitation forces into the single-stage rotor-bearing system. The numerical simulation shows that for the model with each single excitation force, all of these three forces need to reach some limit to force the system into the unsteady state. For all the three forces, higher limits are needed if the machine runs at lower running speeds. Furthermore, unbalance loading also can influence the system behaviours. As the unbalance increases, the system will still stay steady while the spectra become noisier, though the amplitude still low comparing to harmonics. (3) Combing three types of excitation forces into the assembled rotor-bearing system. The numerical simulation shows that the assembled system presents similar vibration responses as the single stage rotor-bearing system. Furthermore, these three forces cannot cancel each other and the combination will unstabilise the system. Meanwhile, the influence of the dominant magnetic pull force is less than other two forces.
163

Mathematical and computer modelling of the enteric nervous system

Thomas, Evan Alexander January 2001 (has links) (PDF)
The enteric nervous system (ENS) runs within the intestinal wall and is responsible for initiating and enacting several reflexes and motor patterns, including peristalsis and the complex interdigestive motor programs, known as migrating motor complexes (MMCs). The ENS consists of several neuron types including intrinsic sensory neurons, interneurons and motor neurons. A great deal is known about the anatomy, pharmacology and electrophysiology of the ENS, yet there is almost no understanding of how enteric neural circuits perform the functions that they do and how they switch from one function to another. The ENS contains intrinsic sensory neurons (ISNs) that connect to every neuron type in the ENS, including making recurrent connections amongst themselves. Thus, they are likely to play a key role, not just in sensory transduction, but in coordination of reflexes and motor patterns. This thesis has explored how these functions are performed by developing and analysing mathematical and computer models of the network of ISNs. (For complete abstract open document)
164

Superdeformation : a tool to study fusion-evaporation reactions /

Nieminen, John Matti. January 1998 (has links)
Thesis (Ph.D.) -- McMaster University, 1998. / Includes bibliographical references (leaves 83-94). Also available via World Wide Web.
165

Collectivity in A ~ 60 nuclei : superdeformed and smoothly terminating rotational bands /

Svensson, Carl Edward. January 1998 (has links)
Thesis (Ph.D.) -- McMaster University, 1998. / Includes bibliographical references (leaves 241-264). Also available via World Wide Web.
166

In vivo electrical stimulation of motor nerves /

Szlavik, Robert Bruce. January 1999 (has links)
Thesis (Ph.D.) -- McMaster University, 1999. / Includes bibliographical references (leaves 154-160). Also available via World Wide Web.
167

Core excitation of some organometallic and organosilicon molecules.

Wen, Alex T. Hitchcock, Adam P. Unknown Date (has links)
Thesis (Ph.D.)--McMaster University (Canada), 1992. / Source: Dissertation Abstracts International, Volume: 54-08, Section: B, page: 4153. Adviser: Adam P. Hitchcock.
168

Excitation contraction coupling of ventricular myocyte in septic shock role of a change in calcium cycling system /

Lau, Chun-hung, Barry. January 2007 (has links)
Thesis (M. Phil.)--University of Hong Kong, 2008. / Also available in print.
169

Electron capture into excited states by helium ions

Wolterbeek Muller, Lambert, January 1971 (has links)
Thesis--Rijksuniversiteit te Leiden. / Summary also in Dutch. Includes bibliographies. Also issued in print.
170

Excitation contraction coupling of ventricular myocyte in septic shock : role of a change in calcium cycling system /

Lau, Chun-hung, Barry. January 2007 (has links)
Thesis (M. Phil.)--University of Hong Kong, 2008. / Also available online.

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