[Truncated abstract] The feasibility of using interlocked light gauge sheet piles to form a deep cross-sectional wall embedded in a residual slope or with a berm support is explored. This thesis compares the performance of a large section modulus sheet pile wall as an alternative to a concrete diaphragm wall, acting as an embedded cantilever wall on a slope (ECWS) by means of experimental centrifuge tests, numerical models and analytical methods. Abaqus (Hibbitt, Karlsson and Sorensen Inc, 1997) was used to conduct extensive numerical trials on the structural performance of the sheet pile wall model prior to the actual physical testing. The Abaqus results showed that the integrity of the interlock and reduced modulus action (RMA) due to slippage along the interlocked joint did not cause premature buckling of the thin wall even at the ultimate load. Further, a comparative study using centrifuge tests on 1:30 scaled models and Plaxis analysis demonstrated that under the worst condition with high water table, the rigid sheet pile wall of 1.32 m cross-sectional width carried a higher ultimate surcharge load with a much lower top of wall deflection, compared to a more flexible 0.6 m thick cracked concrete diaphragm wall. The analysis of the wall/soil/slope interactions for an ECWS involves many inter-dependent variables in addition to the complications of considering an adjacent slope or a berm support. It is difficult for existing analytical approaches to take all these factors into account, and some form of numerical analysis, calibrated through field data and results from centrifuge model tests is necessary. From the observations of the centrifuge tests and finite element analysis, major assumptions about the failure of a stiff ECWS in a rotational mode were deduced and adopted in the proposed limiting equilibrium method (Leq). The plane strain Leq ECWS Abstract ii analysis is based on the framework of minimum upper bound limiting equilibrium with planar failure planes and a Mohr-Coulomb soil model. As compared to the traditional limit equilibrium analysis, the Leq method is a fully coupled analysis using the shear strength reduction technique (SSR). New formulations are proposed for the development of horizontal active and passive pressure distributions based on the experimental and FE models. The proposed active pressure profile used is derived by combining the Coulomb and Krey method, and empirically back-figured to curve-fit the centrifuge tests by Morris (2005). The proposed passive pressure profile of a rigid rotational wall in failure is adjusted to allow for an adjacent slope or berm support through a presumed elasto-plastic deformation instead of a linear rigid translation of the passive wedge. ... A parametric study was later undertaken using the Leq method to develop a series of non-dimensionalised graphs to study and draw summarised conclusions on the behaviour of the ECWS. The final conclusions on the comparative study of the centrifuge tests, Plaxis and Leq analyses demonstrated that the alternative light gauge steel sheet pile performed very well as an ECWS. A key factor in the performance of the sheet pile wall was attributed to the large 1.32 m cross-sectional width of the interlocked sections. This provided high bending stiffness and high moment stability from shear stresses acting on the back and front faces of the wall.

The purpose of the research reported in this thesis is to investigate the occurrence and recognition of “limit experience” among some Catholic High School students in their final year at selected secondary colleges in Brisbane. “Limit” experience was defined as an experience that reveals a reality of life beyond the self, beyond the here and now. It may be recognition of our own fragility and vulnerability as much as a joyous awareness of a reality beyond our normal encounter with life.” The research work of the Alistair Hardy Research Centre and of Hay (1987) in particular has centred on the question, asked in various ways: Have you ever been aware of, or influenced by, a presence or power, whether you call it God or not, which is different from your everyday life? The survey instrument for this research was designed to divorce questions on such experiences from the direct reference to the term “religious”, although individuals might indeed interpret them as “religious”. To approach the issue, an extensive open-ended survey was administered to senior high school students. It was designed first to determine the extent of recognition of such experiences among the students and second to examine whether factors such as home background, regular religious practice, type of school, subject choice or co-curricula activities may make a difference in enhancing the awareness of such experience. This research has also been designed to enable comparison with similar studies. Major research in Australia by Flynn (1975, 1985, 1993) highlighted the factors above as influencing student achievement. Flynn also made connections to religious practice and attitudes to church but not to religious experience as such. Robinson and Jackson (1987) had undertaken extensive research on religious experience in Great Britain that also has important parallels to this research. Some of the techniques of both studies and in some cases actual questions have formed part of this research instrument. This research has gone further than both studies by incorporating the Hay (1987) categorisation of types of religious experience to form the basis for direct questions on student experience. The data gathering, treatment and analysis focused on four catholic secondary schools in the Brisbane Archdiocese. While the research focus was by definition limited, and while the results have of necessity to be treated with some caution before wider generalisation, the outcomes of the research do illuminate some of the important issues identified in the literature. The results of the survey showed that over 90% of the respondents could affirm some association with a “limit” experience along the lines of the Hay (1987) framework. With significant strengthening of criteria to allow for meaningful statistical analysis, this reduced to 76% of respondents. Results for this smaller group were shown to be essentially independent of home background, type of school attended, co-curricula programs and level of religious practice. With the significant exception of religious education, their recognition of “limit” experience was also independent of subject choice. This last is in contrast to the earlier work of Robinson and Jackson (1987). Exploratory analyses of the data enabled comparisons to be made with a suggested framework for “spiritual sensitivity” and the context of “relational consciousness”, both of which were first proposed by Hay and Nye (1998). This suggests some possible directions for further research into adolescent spirituality. The exploratory analyses also highlight some of the conflict between the reality of these experiences for students and their experience of dissonance with institutional religion.

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

Limit Cycle Oscillation is a type of aircraft wing structural vibration caused by the non-linearity of the system. The objective of this thesis is to provide a numerical study of this aeroelastic behavior. A CFD solver is used to simulate airfoils displaying such an aeroelastic behavior under certain airflow conditions. Two types of airfoils are used for this numerical study, including the NACA64a010 airfoil, and the supercritical NLR 7301 airfoil. The CFD simulation of limit cycle oscillation (LCO) can be obtained by using published flow and structural parameters. Final results from the CFD solver capture LCO, as well as flutter, behaviors for both wings. These CFD results can be obtained by using two different solution schemes, including the Roe and Zha scheme. The pressure coefficient and skin friction coefficient distributions are computed using the CFD results for LCO and flutter simulations of these two airfoils, and they provide a physical understanding of these aeroelastic behaviors.

The author examines nonlinear aeroelastic responses of air vehicle systems. Herein, the governing equations for a cantilevered configuration are developed and the methods of analysis are explored. Based on the developed nonlinear bending-bending-torsion equations, internal resonance, which is possible in future air vehicles, and the possible cause of limit cycle oscillations of aircraft wings with stores are investigated. The nonlinear equations have three types of nonlinearities caused by wing flexibility, store geometry and aerodynamic stall, and retain up to third-order nonlinear terms. The internal resonance conditions are examined by the Method of Multiple Scales and demonstrated by time simulations. The effect of velocity change for various physical parameters and stiffness ratio is investigated through bifurcation diagrams derived from Poinar´e maps. The dominant factor causing limit cycle oscillations is the stiffness ratio between in-plane and out-of-plane motion.

No description available.

This thesis, which consists of four chapters, focuses on three topics: discriminating between stationary and nonstationary time series, testing the constancy of the error covariance matrix of a vector model, and estimating density functions over bounded domains using kernel techniques. In Chapter 1, “Testing the unit root hypothesis against the logistic smooth transition autoregressive model”, and Chapter 2, “A nonlinear alternative to the unit root hypothesis”, the joint hypothesis of unit root and linearity allows one to distinguish between random walk processes, with or without drift, and stationary nonlinear processes of the smooth transition autoregressive type. This is important in applications because steps taken in modelling a time series are likely to be drastically different depending on whether or not the unit root hypothesis is rejected. In Chapter 1 the nonlinearity is based on the logistic function, while Chapter 2 considers the second-order logistic function. Monte Carlo simulations show that the proposed tests have about the same or higher power than the standard Dickey-Fuller unit root tests when the alternative exhibits nonlinear behavior. In Chapter 1 the tests are applied to the seasonally adjusted U.S. monthly unemployment rate, giving support to the hypothesis that the unemployment rate series follows a smooth transition autoregressive model rather than a random walk. Chapter 2 considers testing the so called purchasing power parity (PPP) hypothesis. The test results complement earlier studies, giving support to the PPP hypothesis for 44 out of 120 real exchange rates considered. Chapter 3. “Testing the constancy of the error covariance matrix in vector models”Estimating the parameters of an econometric model is necessary for any use of the model, be it forecasting or policy evaluation. Finding out thereafter whether or not the model appears to satisfy the assumptions under which it was estimated should be an integral part of a normal modelling exercise. This chapter includes the derivation of a Lagrange Multiplier test of the null hypothesis of constant variance in vector models when testing against three specific parametric alternatives. The Monte Carlo simulations show that the test has good size properties, very good power against a correctly specified alternative, but low or only up to moderate power in cases for a misspecified alternative hypothesis. Chapter 4. “ Estimating confidence regions over bounded domains”Nonparametric density estimation by kernel techniques is a standard statistical tool in the estimation of a density function in situations where its parametric form is assumed to be unknown. In many cases, the data set over which the density is to be estimated exhibits linear, or nonlinear, dependence. A solution to this problem is to apply a one-to-one transformation to the considered data set in such a way that the dependence in the data vanishes, but too often such a unique transformation does not exist. This chapter proposes a method for estimating confidence regions over bounded domains when no one-to-one transformation of the considered data exists, or if the existence of such a transformation is difficult to verify. The method, simple kernel estimation over a nonlinear grid, is illustrated by applying it to three data sets generated from the GARCH(1,1) model. The resulting confidence regions cover a reasonable area of the definition space, and are well aligned with the corresponding data sets. / Diss. Stockholm : Handelshögsk., 2003

Directional selection is prevalent in nature yet phenotypes tend to remain relatively constant, suggesting a limit to trait evolution. The genetic basis of evolutionary limits in unmanipulated populations, however, is generally not known. Given widespread pleiotropy, opposing selection on a focal trait may arise from the effects of the underlying alleles on other fitness components, generating net stabilizing selection on trait genetic variance and thus limiting evolution. Here, I look for the signature of stabilizing selection for a suite of cuticular hydrocarbons (CHCs) in Drosophila serrata. Despite strong directional sexual selection on CHCs, genetic variance differed between high and low fitness individuals and was greater among the low fitness males for seven of eight CHCs. Univariate tests of a difference in genetic variance were non-significant but have low power. My results implicate stabilizing selection, arising through pleiotropy, in generating a genetic limit to the evolution of CHCs in this species.

Due to lack of soil sampling during a conventional cone penetration testing (CPT), it is necessary to classify soils based on recorded tip and sleeve friction and pore pressure (if available) values. However, currently available soil classification models are based on deterministic and judgemental determination of soil classification boundaries which do not address the uncertainties intristic to the problem. Moreover, size and quality of databases used in the development of these soil classification models are undocumented and thus questionable. Similar limitations do also exist in the development of SPT-CPT correlations which are widely used in SPT dominated design such as soil liquefaction triggering. To eliminate these discussed limitations, within the confines of this study it is attempted to present (1) a new probabilistic CPT- based soil classification methodology, and (2) new SPT-CPT correlations which address the uncertainties intrinsic to the problems. For these purposes, a database composed of 400 CPT/SPT boring data pairs was compiled. It is intended to develop probabilistic models, which will correlate CPT tip and sleeve friction values to actual soil classification and CPT tip resistance to SPT blow count N. The new set of correlations, model parameters of which estimated by implementing maximum likelihood methodology, presented herein are judged to represent a robust and defensible basis for (1) prediction of soil type based on CPT data and, (2) estimation of SPT-N value for given CPT data.

Workpieces during cold forging fail basically due to ductile fracture. Ductile fracture can be predicted by damage models. In this study, various damage models such as Cockcroft &amp / Latham, McClintock, Freudenthal, Rice &amp / Tracy, Oyane, Ayada, Brozzo are investigated for their applicability to three workpiece materials: bearing steel (100Cr6), stainless steel (X5CrNiMo1810) and brass (CuZn39). The damage material parameters have been obtained by various tests such as tensile, standard compression, ring compression, compression with flanges and conical compression tests. The characterization has been assisted by finite element simulation of the various tests. It has been shown that the available damage models can predict the location of failure satisfactorily but are no able to predict the onset of failure quantitatively. Keywords: Formability Limit, Failure Criteria, Cold Forming, Surface Cracks, Finite Element Analysis