Many tasks can easily be posed as the problem of responding to the states of an external world with actions that maximise the reward received over time. Algorithms that reliably solve such problems exist. However, their worst-case complexities are typically more than proportional to the size of the state space in which a task is to be performed. Many simple tasks involve enormous numbers of states, which can make the application of such algorithms impractical. This thesis examines reinforcement learning algorithms which effectively learn to perform tasks by constructing mappings from states to suitable actions. In problems involving large numbers of states, these algorithms usually must construct approximate, rather than exact, solutions and the primary issue examined in the thesis is the way in which the complexity of constructing adequate approximations scales as the size of a state space increases. The vast majority of reinforcement learning algorithms operate by constructing estimates of the long-term value of states and using these estimates to select actions. The potential effects of errors in such estimates are examined and shown to be severe. Empirical results are presented which suggest that minor errors are likely to result in significant losses in many problems, and where such losses are most likely to occur. The complexity of constructing estimates accurate enough to prevent significant losses is also examined empirically and shown to be substantial.

This dissertation studies by experiment and numerical analysis an advanced composite material (Machine Augmented Composite or MAC) for enhancement of the passive damping while maintaining its stiffness. This MAC is composed of a pre-buckled wall structure placed within a viscoelastic matrix. The pre-buckled machine can contain viscous fluids for additional energy dissipation. For the experiments, the MAC was fabricated by using rigid and soft polyurethane as a machine and matrix material respectively. Various viscosity fluids (0.83 ~ 4730 cps) filled the inner-channel of the machine structure. Dynamic properties such as tan ?? and the loss modulus (E") of the composite were measured and compared with those of a homogeneous matrix sample over a frequency range of 0.1 to 100 Hz at room temperature through load-controlled cyclic testing. Measured tan ?? and loss modulus values for the composite were higher than those of the matrix alone in the 1 to 40 Hz range. However the viscous fluid effects on the overall damping properties were small. The performance of a theoretical MAC was explored through numerical analysis. The amount of inner-channel gap closure was calculated for various matrix Poisson??s ratios, for various Young??s modulus ratios between the machine and matrix (Emachine/Ematrix), and for the volume fraction of the machines. The most desirable performance of the composite was obtained when the matrix Poisson??s ratio was 0.49, and there was interaction between the Emachine/Ematrix and the volume fraction of the machines. Also the proper volume fraction range of the machine was predicted to be between 0.15 and 0.2 for the lamina shape MAC. Based upon the analysis, a sandwich structure MAC was fabricated and tested. This composite showed 11 times higher stiffness than the matrix without loosing the matrix damping property. This dissertation shows that the research met these objectives: 1) the MAC concept is effective for passive damping of vibrations, 2) that material combinations studied here had optimal combinations for best performance, and 3) that this is a promising field study for future passive and active materials development.

Abstract The energy crisis makes promotion to the research of renew energy being of great urgency. However, the wind power still belong to unstable energy, for some electrical and control problems need to be improved. Owing to wind power in Taiwan still in the beginning period, the thesis is from the introduction of wind machine and its components to realize the wind¡¦s cause and frequency. That can conduct the wind power equation and property. According to wind machine at present, there are two function types. One is constant velocity and the other is variable velocity. Comparing these two types, we have a simulation to gain the energy. By the induction generation equation conduction and building wind power generation system, we can understand the change of wind to affect the electrical dynamical property.

This dissertation studies by experiment and numerical analysis an advanced composite material (Machine Augmented Composite or MAC) for enhancement of the passive damping while maintaining its stiffness. This MAC is composed of a pre-buckled wall structure placed within a viscoelastic matrix. The pre-buckled machine can contain viscous fluids for additional energy dissipation. For the experiments, the MAC was fabricated by using rigid and soft polyurethane as a machine and matrix material respectively. Various viscosity fluids (0.83 ~ 4730 cps) filled the inner-channel of the machine structure. Dynamic properties such as tan ?? and the loss modulus (E") of the composite were measured and compared with those of a homogeneous matrix sample over a frequency range of 0.1 to 100 Hz at room temperature through load-controlled cyclic testing. Measured tan ?? and loss modulus values for the composite were higher than those of the matrix alone in the 1 to 40 Hz range. However the viscous fluid effects on the overall damping properties were small. The performance of a theoretical MAC was explored through numerical analysis. The amount of inner-channel gap closure was calculated for various matrix Poisson??s ratios, for various Young??s modulus ratios between the machine and matrix (Emachine/Ematrix), and for the volume fraction of the machines. The most desirable performance of the composite was obtained when the matrix Poisson??s ratio was 0.49, and there was interaction between the Emachine/Ematrix and the volume fraction of the machines. Also the proper volume fraction range of the machine was predicted to be between 0.15 and 0.2 for the lamina shape MAC. Based upon the analysis, a sandwich structure MAC was fabricated and tested. This composite showed 11 times higher stiffness than the matrix without loosing the matrix damping property. This dissertation shows that the research met these objectives: 1) the MAC concept is effective for passive damping of vibrations, 2) that material combinations studied here had optimal combinations for best performance, and 3) that this is a promising field study for future passive and active materials development.

Thesis (Ph. D.)--Ohio State University, 2002. / Title from first page of PDF file. Document formatted into pages; contains xvi, 306 p.; includes graphics. Includes abstract and vita. Advisor: Chris Brew, Dept. of Linguistics. Includes indexes. Includes bibliographical references (p. 284-293).

Thesis (M. Phil.)--University of Hong Kong, 1989.

Thesis--M. Phil., University of Hong Kong.

Thesis (Ph. D.)--Oregon State University, 2002. / Typescript (photocopy). Includes bibliographical references (leaves 122-138). Also available on the World Wide Web.

Not available / text

No description available.