Academic literature on the topic 'LD5655.V851 1990.L437'

The convergence rates for the method of Weinstein and a variant method of Aronszajn known as "truncation including the remainder" are derived in terms of the containment gaps between exact and approximating subspaces, using analytical techniques that arise in part in the convergence analysis of finite element methods for differential eigenvalue problems. An example of a one dimensional Schrodinger operator with a potential is presented which arises in quantum mechanics. Examples using the recent eigenvector-free (EVF) method of Beattie and Goerisch are considered. Since the EVF method uses finite element trial functions as approximating vectors, it produces sparse and well-structured coefficient matrices. For these large-order sparse matrix eigenvalue problems, we adapt a spectral transformation Lanczos algorithm for finding a few wanted eigenvalues. For a few particular examples of vibration in beams and plates, convergence behavior is experimentally evaluated.<br>Ph. D.

The classical Fourier analysis of time series data can be used to detect periodic trends that are of sinusoidal shape. However, this analysis can be misleading when time series trends are not sinusoidal. When the time series process of interest is binary or categorical-valued data, it might be more reasonable that the time process be represented by a square or rectangular form of functions instead of sinusoidal functions. The WalshFourier analysis takes this approach using a square form of functions. The Walsh-Fourier analysis is based on the Walsh functions. The Walsh functions are a square form of functions that take on only two values + 1 and -1. But, unlike sinusoidals, the Walsh functions are not periodic. Harmuth (1969) introduced the term sequency to describe generalized frequency to identify functions that are not periodic, such as Walsh functions. The term sequency is interpreted as the nun1ber of zero crossings or sign changes per unit time. While the Walsh-Fourier analysis is reasonable in theory for binary or categorical-valued time series data, the interpretation of sequency is often difficult. In this dissertation, using a sequence of periodic functions, we develop the theory and method that can be applied to binary or categorical-valued data where patterns more naturally follow a rectangular shape. The theory parallels the Fourier theory and leads to a "Fourier-like" data transform that is specifically suited to the identification of rectangular trends.<br>Ph. D.

Fabrication of high-quality composites from thennoplastic prepregs requires careful selection of the processing cycles so that intimate contact at the ply interfaces is achieved resulting in the formation of strong interply bonds and the process-induced residual stress is minimized to ensure superior mechanical performance. The void formation and the consolidation mechanism were studied experimentally. A refined model was developed to relate the processing parameters of pressure, temperature and time to the interply intimate contact of thermoplastic composites. The model was developed by integrating a prepreg surface topology characterization with a resin flow analysis. Both unidirectional and cross-ply lay-ups were modeled. Two-ply unidirectional laminae fabricated from graphite-polysulfone and graphite-PEEK prepregs and [0/90/0]_T laminates were consolidated using different processing cycles. Optical microscopy and scanning acoustic microscopy were used to obtain the degree of intimate contact data. Agreement between the measured and calculated degree of intimate contact was good. A finite element model was developed to analyze residual stresses in thermoplastic composites by combining a plane-strain elasticity analysis and a temperature-dependent matrix properties. The residual stress model takes into account the mismatch of the thermal expansion coefficients and the crystallization shrinkage of the matrix. [O₁₀/90₆]_T graphite-PEEK laminates were manufactured at different cooling rates to verify the model. The induced residual thermal defonnations were measured by a shadow moire system. The model accurately estimated the out-of-plane displacement of the non-symmetrical laminates.<br>Ph. D.

<p>Numerous scholars are outlining design approaches to reweave natural and cultural landscapes together to restore and enhance the quality of both. Typically they identify the following exigent issues within the contemporary landscape which need solving: fragmented, dysfunctional ecosystems;¹ low wildlife and plant diversity; resource consumptive design; divorce of the human/cultural environment from natural ecosystems; infrequent human interaction with the ecosystem; and lost landscape legibility and regional identity. Strategies to solve these issues are varied, however most strategies include the following: reestablish ecosystem balance and function; increase wildlife and plant diversity; enhance and promote regional identity and landscape legibility; reconnect human landscapes with ecosystems; promote human interaction with the ecosystem; use nature as a design model; and redefine aesthetics. Many writers suggest combining identified components within a single design scheme for successful amelioration of cultural and ecosystem damage.</p> <p> Alternative drainageway design projects are typically concerned with ecosystem restoration, enhancement of regional identity features, and civic space design within public landscapes. As such, this design genre offers an idea] venue to actualize criteria outlined by scholars: restore ecosystem health, reconnect people to ecosystems, and promote regional identity. However many alternative drainageway design projects address only ecosystem restoration and ignore public space, while others address public space to the detriment of ecological balance. The potential of alternative drainageway design to address multiple issues at once is tremendous, yet are there existing projects which match demands set forth by scholars?</p> <p> This thesis seeks to answer that question by critical evaluation of a series of built alternative drainageway design projects. Criteria identified by scholars in the literature review are used as a framework to critically analyze and topically discuss selected projects. Because the same set of criteria is shared by reputed scholars, the derived criteria serve as a pertinent benchmark to evaluate the projects. Discussion and comparative analysis illustrates whether the projects embody identified criteria and identify if any projects meet rigorous multiple demands framed by scholars. By critically analyzing and identifying successful, multiple-solution projects, this thesis provides germane information to develop a foundation for twenty-first century drainageway design. The derived framework offers clear stepping stones for designers, based upon current theory and built projects, to effectively address pressing cultural and environmental issues of the late twentieth and early twenty-first century landscape. The derived framework thus forwards a methodology to re-weave natural and cultural landscapes together for the benefit both.</p><br>Master of Landscape Architecture

Binary response data is often modeled using the logistic regression model, a well known nonlinear model. Designing an optimal experiment for this nonlinear situation poses some problems not encountered with a linear model. The application of several optimality design criteria to the logistic regression model is explored, and many resulting optimal designs are given. The implementation of these optimal designs requires the parameters of the model to be known. However, the model parameters are not known. If they were, there would be no need to design an experiment. Consequently the parameters must be estimated prior to implementing a design. Standard one-stage optimal designs are quite sensitive to parameter misspecification and are therefore unsatisfactory in practice. A two-stage Bayesian design procedure is developed which effectively deals with poor parameter knowledge while maintaining high efficiency. The first stage makes use of Bayesian design as well as Bayesian estimation in order to cope with parameter misspecification. Using the parameter estimates from the first stage, the second stage conditionally optimizes a chosen design optimality criterion. Asymptotically, the two-stage design procedure is considerably more efficient than the one-stage design when the parameters are misspecified and only slightly less efficient when the parameters are known. The superiority of the two-stage procedure over the one-stage is even more evident for small samples.<br>Ph. D.