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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

The adaptive reference-state minimal control synthesis algorithm : with application to the control of shaking-tables

Hatano, Toshiaki January 2014 (has links)
Lessons learnt from the recent catastrophic earthquakes and tsunami across the world motivate research testing using full -scale earthquake shaking-tables. Through this testing avenue, the effects of an earthquake can be reproduced. The dynamic tests involved play significant roles in ensuring the reliability, durability and functionality of engineering systems. This in turn has an impact on lives of people. The fidelity of the results obtained from shaking-tab le tests are largely influenced by the accuracy of the control system. Currently. conventional linear control schemes are widely used on many shaking-tables, but their control performance can significantly deteriorate in the face of dynamic uncertainties, non-linearities and external disturbances. Generally, a feedback control strategy is employed to compensate such disturbances and improve the closed-loop stability of the system. In practice, however, many shaking-tab le facilities have some controller design restrictions: primarily, performance enhancement with in the feedback-loops is explicitly not allowed due to confidentiality and/or safety reasons. Beside these issues, a shaking-tab le system which can generate a large amplitude acceleration (more than -20m/s2)) earthquake wave is in a high demand, due to recent earthquakes recorded in Japan being at such levels of intensity. Nevertheless, most large shaking-tab les cannot reproduce this level of acceleration due to the mechanical limitations in their actuation systems. This thesis describes how a conventional linear controller can be enhanced by a novel, feed forward adaptive control strategy, called the reference-state minimal control synthesis algorithm and its application to the control of shaking-tab les. Furthermore, the development of a new shaking-table configuration. called a multi-stage shaking-table which is used to generate a high-acceleration table motion, is also presented. Comparative simulation and implementation tests show that significant performance improvements are achieved with the new control scheme, in spite of non- linearities and parameter changes in the controlled system.
2

Strain accommodation by magmatism and faulting as rifting proceeds to breakup : seismicity of the Northern Ethiopian Rift

Keir, Derek January 2006 (has links)
No description available.
3

Time-lapse analysis of multi-component seismic data

Al-Naamani, Ali Y. A. January 2004 (has links)
No description available.
4

The effects of stress on the seismic velocities of reservoir rocks

Seymour, Robert Henry January 2005 (has links)
No description available.
5

Analysis of global variations in upper mantle anisotropy from shear wave splitting of SKS phases

Evans, Matthew Stephen January 2006 (has links)
No description available.
6

Estimating signal polarisations in seismic array data : theory and applications

Meersman, Kristof de January 2005 (has links)
No description available.
7

Seismic surface waves in the laterally heterogeneous Earth

Ferreira, Ana Margarida Godinho January 2005 (has links)
No description available.
8

InSAR observations of the earthquake cycle on the Denali Fault, Alaska

Biggs, Juliet January 2007 (has links)
No description available.
9

Enhanced spatial resolution of microseismicity in the investigation of in-situ crack interaction and coalescence

Reyes-Montes, Juan Miguel January 2004 (has links)
No description available.
10

Static problems due to sand dunes in NC151, western Libya

Ushah, Abdurrazag M. Ali January 2004 (has links)
No description available.

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