This thesis concerns the use of an analogue as an aid to a problem solving program. A -working system, the advantages of the analogue it uses, the mechanisms required, and the interaction of ether forms of knowledge are described. The program, WHISPER, uses a diagram together with procedures for modifying it, as an analogue of a situation involving a stack of arbitrarily shaped rigid bodies. It determines a stack's stability and predicts the motions cf any unstable object by examining the situation's diagram. The analogue is particularly valuable in detecting discontinuities in an object's motion. For example, collisions with other objects or cliffs an object might slide over can be 'seen' in the diagram rather than having to be inferred from a description of the situation. WHISPER uses a simulated parallel processing 'retina' to look at the diagram which is encoded in a two-dimensional array. It consists of a fixed number of processors operating in parallel and communicating only with their immediate neighbours. WHISPER's retina resembles the human retina in some respects. Its resolution decreases away from its center. It can be moved to fixate on different sections of a diagram. A set of domain independent features are extracted from WHISPER's diagrams by procedures, called perceptual primitives, which execute on the parallel processing retina. Example features are: symmetry of an object, similarity of two objects, and contacts of an object with ether objects. In addition to these primitives, the retina can be used to 'visualize1 the rotation of an object without having to move it directly in the diagram The advantages of analogues are classified in terms of two categories according to whether a correspondence exists between the behaviour of the analogue and the behaviour of the external situation, or whether a correspondence exists between the static configurations of the analogue and those of the external situation. Some reasons for the effectiveness of analogues are presented. / Science, Faculty of / Computer Science, Department of / Graduate

No description available.

Wong Chun Kit. / Thesis submitted in: October 2006. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 73-76). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Background and Motivation --- p.1 / Chapter 1.2 --- Objectives --- p.4 / Chapter 1.3 --- Contributions --- p.4 / Chapter 1.4 --- Thesis Outline --- p.5 / Chapter 2 --- Digital Signal Processing --- p.6 / Chapter 2.1 --- Introduction --- p.6 / Chapter 2.2 --- Discrete-time Signals and Systems --- p.7 / Chapter 2.2.1 --- Discrete-time Signals --- p.7 / Chapter 2.2.2 --- Discrete-time Signal Processing Systems --- p.9 / Chapter 2.2.3 --- Linear Time-Invariant (LTI) Systems --- p.10 / Chapter 2.3 --- Finite Impulse Response (FIR) Filters --- p.13 / Chapter 2.3.1 --- Introduction --- p.13 / Chapter 2.3.2 --- Windowing FIR Filter Design Method --- p.15 / Chapter 2.4 --- Infinite Impulse Response (IIR) Filters --- p.17 / Chapter 2.4.1 --- Introduction --- p.17 / Chapter 2.4.2 --- Bilinear Transform IIR Filter Design Method --- p.18 / Chapter 2.4.3 --- Spectral Transformations of IIR Filters --- p.22 / Chapter 2.5 --- Comparison on FIR and IIR Filters --- p.25 / Chapter 2.6 --- Digital Signal Resampling --- p.26 / Chapter 2.6.1 --- Introduction --- p.26 / Chapter 2.6.2 --- Resampling by Decimation --- p.26 / Chapter 2.6.3 --- Resampling by Interpolation --- p.28 / Chapter 2.6.4 --- Resampling by a Rational Factor --- p.29 / Chapter 2.7 --- Introduction to Dual Fixed-point (DFX) Representation --- p.30 / Chapter 2.8 --- Summary --- p.33 / Chapter 3 --- Lyon and Mead's Cochlea Model --- p.34 / Chapter 3.1 --- Introduction --- p.34 / Chapter 3.2 --- Digital Cochlea Model: Cascaded IIR Filters --- p.37 / Chapter 3.2.1 --- Introduction --- p.37 / Chapter 3.2.2 --- Bandwidth and Centre frequencies --- p.38 / Chapter 3.2.3 --- Zeros and Poles --- p.39 / Chapter 3.3 --- Modifications for Decimated Cochlea Model --- p.41 / Chapter 3.3.1 --- Introduction --- p.41 / Chapter 3.3.2 --- Aliasing Avoidance --- p.42 / Chapter 3.3.3 --- Coefficient Modification after Decimation --- p.43 / Chapter 3.4 --- Summary --- p.47 / Chapter 4 --- System Architecture --- p.48 / Chapter 4.1 --- Introduction --- p.48 / Chapter 4.2 --- Hardware Platform and CAD Tools --- p.48 / Chapter 4.3 --- Sequential Processing Electronic Cochlea --- p.51 / Chapter 4.3.1 --- Pipelining - An Interleaving Scheme --- p.53 / Chapter 4.3.2 --- Decimation in Sequential Processing Electronic Cochlea . --- p.54 / Chapter 4.3.3 --- Multiple Sequential Cores --- p.55 / Chapter 4.3.4 --- Architecture of the DFX Filter Computation Core --- p.55 / Chapter 4.4 --- Summary --- p.60 / Chapter 5 --- Experimental Results --- p.61 / Chapter 5.1 --- Introduction --- p.61 / Chapter 5.2 --- Testing Environment --- p.61 / Chapter 5.3 --- Performance of the Sequential Electronic Cochlea --- p.63 / Chapter 5.3.1 --- Comparisons --- p.63 / Chapter 5.4 --- Summary --- p.69 / Chapter 6 --- Conclusions --- p.70 / Chapter 6.1 --- Future Work --- p.72 / Bibliography --- p.73

No description available.

Thesis (PhD) -- University of South Australia, 1998

Reprint of an article by the author bound in at back of volume / vi, 192 leaves : ill., plates ; 27 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Botany, 1974

Thesis (Ph.D.) -- University of Adelaide, Dept. of Botany, 1974. / Reprint of an article by the author bound in at back of volume.

Thesis. 1978. Ocean E.--Massachusetts Institute of Technology. Dept. of Ocean Engineering. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / Ocean E.

This study reports the results of an investigation of the potential pollution hazard of a potash brine disposal pond located near Esterhazy, Saskatchewan. The most serious problems associated with the brine pond are the potential pollution of groundwater resources and the possible contamination of a nearby stream by groundwater discharge. The primary geologic feature is a glacial buried valley aquifer consisting of highly-permeable sands and gravels. A three dimensional electric analog model was constructed to simulate the steady state and transient groundwater flow systems in the buried valley aquifer. The steady state analysis enabled the author to calculate the convective travel times of the brine from the brine pond to the nearby creek. The transient analysis was used to assess the feasibility of reversing the hydraulic gradient in the buried valley aquifer. Steady state results indicate that the most serious potential pollution hazard is brine seepage onto the surface immediately east of the brine pond. At a distance of 5600 feet from the brine pond, this seepage will occur within 30 years; nearer to the brine pond, it will occur sooner. This type of brine seepage could enter the nearby stream as a result of surface drainage. Brine pollution by groundwater discharge directly into the creek will take between 640 to 1260 years, so this mechanism does not pose an immediate pollution hazard. Transient results indicate that low-rate injection wells (up to 50 IGPM) would not reverse the hydraulic gradient in the buried valley aquifer. Injection rates between 370 to 575 IGPM would be required, but fresh water supplies of this magnitude are not available. The design of future brine ponds should include seepage calculations in the initial phases of design instead of after the fact. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

The primary focus of this research is to investigate the non-linear behavior of single crystal and polycrystalline relaxor ferroelectric PMN-xPT and PZN-xPT through experimentation and modeling. Characterization of single crystal and polycrystalline specimens with similar compositions was performed. These data give experimental insight into the differences that may arise in a polycrystal due to local interaction with inhomogeneities. Single crystal specimens were characterized with a novel experimental technique that reduced clamping effects at the boundary and gave repeatable results. The measured experimental data was used in conjunction with electromechanical characterizations of other compositions of single crystal specimens with the same crystallographic orientation to study the compositional effects on material properties and phase transition behavior. Experimental characterization provided the basis for the development of a model of the continuous phase transformation behavior seen in PMN-xPT single crystals. In the modeling it is assumed that a spatial chemical and structural heterogeneity is primarily responsible for the gradual phase transformation behavior observed in relaxor ferroelectric materials. The results are used to simulate the effects of combined electrical and mechanical loading. An improved rate-independent micromechanical constitutive model based on the experimental observations of single crystal and polycrystalline specimens under large field loading is also presented. This model accounts for the non-linear evolution of variant volume fractions. The micromechanical model was calibrated using single crystal data. Simulations of the electromechanical behavior of polycrystalline ferroelectric materials are presented. These results illustrate the effects of non-linear single crystal behavior on the macroscopic constitutive behavior of polycrystals.