Este trabajo propone un sistema para reducir las oscilaciones horizontales de edificios (generadas por movimientos sísmicos o por la acción del viento) mediante la acción activa de barras diagonales de arriostramiento formadas por cables (de acero) pretensados. Las fuerzas (horizontales) de control se determinan a partir de una estrategia de control predictivo que tiene en cuenta el tiempo de retardo en la respuesta de los actuadores así como los errores en la estimación de los parámetros estructurales (incluyendo los citados tiempos de retardo). La respuesta dinámica del edificio con los actuadores se determina numéricamente mediante un algoritmo (desarrollado específicamente para este objetivo) que simula el comportamiento en espacio de estado. La exactitud de este modelo se contrasta con resultados experimentales obtenidos de ensayos efectuados en los laboratorios de la "State University of New York" (Buffalo, NY). Se lleva a cabo un estudio paramétrico para estudiar la eficacia del sistema propuesto en reducir la respuesta a acciones sísmicas y del viento. Los resultados obtenidos permiten concluir que el sistema es plenamente eficaz (y robusto frente a distintas situaciones imprevistas). / This work proposes a system to reduce the horizontal oscillations of buildings (generated by seismic motions or by wind gusts) through the active action of diagonal braces constituted by prestressed steel cables (active tendons). The horizontal control forces are determined from a predictive control strategy which accounts the time delay and the identification errors. The dynamic response of the building is determined numerically by an ad-hoc algorithm. This model is calibrated with ad-hoc experimental results obtained in the laboratories of the "State University of New York" (Buffalo, NY). A parametrical numerical study to assess the efficiency of the proposed system (uner wind and seismic actions) is carried out. The results show that the system is fully efficient and robust.

Thesis (M.S. in Information Technology Management)--Naval Postgraduate School, March 2004. / Thesis advisor(s): Norman F. Schneidewind. Includes bibliographical references (p. 51). Also available online.

Thesis (Ph. D.)--University of Hong Kong. / Mimeographed.

Thesis--M. Sc.(Eng.), University of Hong Kong. / Mimeographed.

published_or_final_version / Electrical Engineering / Doctoral / Doctor of Philosophy

Prostate cancer is one of the leading causes of death by cancer for men. Focal therapy is being tested to target only the dominant cancer lesion in the prostate. However, due to the need to ensure that the laser is targeting only the cancer, a real-time treatment monitoring system is required. A combined optical-ultrasound monitoring system is in development at Princess Margaret Hospital based on different optical properties for coagulated versus normal tissue. In this project, we developed a light delivery and collection device that is compatible for use with an existing trans-rectal ultrasound-imaging probe. Computer-aided design software was used to visualize the prototype in relation to the trans-rectal ultrasound probe. This thesis describes the critical tasks necessary to assemble the final prototype, including listing of specifications, selection of device material based on safety and mechanical properties, method of prototype fabrication, positioning and fixation of optical fibers and testing.

Prostate cancer is one of the leading causes of death by cancer for men. Focal therapy is being tested to target only the dominant cancer lesion in the prostate. However, due to the need to ensure that the laser is targeting only the cancer, a real-time treatment monitoring system is required. A combined optical-ultrasound monitoring system is in development at Princess Margaret Hospital based on different optical properties for coagulated versus normal tissue. In this project, we developed a light delivery and collection device that is compatible for use with an existing trans-rectal ultrasound-imaging probe. Computer-aided design software was used to visualize the prototype in relation to the trans-rectal ultrasound probe. This thesis describes the critical tasks necessary to assemble the final prototype, including listing of specifications, selection of device material based on safety and mechanical properties, method of prototype fabrication, positioning and fixation of optical fibers and testing.

Suspension bridges possess a number of advantages, allowing overlapping average and large spans. The basic disadvantage of suspension bridges can be considered their increased deformability, particularly under the action of non-symmetrical and local loads. Deformability depends, in general, on the kinematical character of displacements of a flexible suspension cable. Required rigidity of suspension bridges is achieved, by increasing the height, and consequently the weight of a stiffening girder, by diagonal suspenders or two-cable or combined prestressed systems. Reduction of kinematical displacements of the main cable can also be achieved by a reduction of the sag-to-span ratio, but the smaller the sag of a cable, the greater are the cable thrust forces and the required cross-sectional areas of the cables. One of the ways of suspension systems stabilization is giving certain bending stiffness to the suspension cables. Such structural solution with success is used in suspension roofs. With the aim to increase the stability of suspension bridges the author proposes to use the finite bending stiffness cables. The cables can be made of standard steel profiles or have composite sections. Conventionally, they are called as “rigid cables”. To verify this solution, the investigation on behavior of suspension bridges with rigid cables under loading has to be undertaken.

Suspension bridges possess a number of advantages, allowing overlapping average and large spans. The basic disadvantage of suspension bridges can be considered their increased deformability, particularly under the action of non-symmetrical and local loads. Deformability depends, in general, on the kinematical character of displacements of a flexible suspension cable. Required rigidity of suspension bridges is achieved, by increasing the height, and consequently the weight of a stiffening girder, by diagonal suspenders or two-cable or combined prestressed systems. Reduction of kinematical displacements of the main cable can also be achieved by a reduction of the sag-to-span ratio, but the smaller the sag of a cable, the greater are the cable thrust forces and the required cross-sectional areas of the cables. One of the ways of suspension systems stabilization is giving certain bending stiffness to the suspension cables. Such structural solution with success is used in suspension roofs. With the aim to increase the stability of suspension bridges the author proposes to use the finite bending stiffness cables. The cables can be made of standard steel profiles or have composite sections. Conventionally, they are called as “rigid cables”. To verify this solution, the investigation on behavior of suspension bridges with rigid cables under loading has to be undertaken.

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