During its service life, concrete experiences volume changes. One of the types of deformation experienced by concrete is shrinkage. The four main types of shrinkage associated with concrete are plastic, autogeneous, carbonation and drying shrinkage. The volume changes in concrete due to shrinkage can lead to the cracking of the concrete. In the case of reinforced concrete, the cracking may produce a direct path for chloride ions to reach the reinforcing steel. Once chloride ions reach the steel surface, the steel will corrode, which itself can cause cracking, spalling, and delamination of the concrete. The development of concrete shrinkage performance specifications that limit the amount of drying shrinkage for concrete mixtures typically used by the Virginia Department of Transportation (VDOT) were assessed. Five existing shrinkage prediction models were also assessed to determine the accuracy and precision of each model as it pertains to the VDOT mixtures used in this study. The five models assessed were the ACI 209 Code Model, Bazant B3 Model, CEB90 Code Model, Gardner/Lockman Model, and the Sakata Model. The percentage length change limits for the portland cement concrete mixtures were 0.0300 at 28 days, and 0.0400 at 90 days. For the supplemental cementitious material mixtures, the percentage length change limits were 0.0400 at 28 days, and 0.0500 at 90 days. The CEB90 Code model performed best for the portland cement concrete mixtures, while the Gardner/Lockman Model performed best for the supplemental cementitious material mixtures. / Ph. D.

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Given the recent popularity and clear evidence of wide applicability of wavelets, this thesis is devoted to several statistical applications of Wavelet transforms. Statistical multiscale modeling has, in the most recent decade, become a well-established area in both theoretical and applied statistics, with impact on developments in statistical methodology. Wavelet-based methods are important in statistics in areas such as regression, density and function estimation, factor analysis, modeling and forecasting in time series analysis, assessing self-similarity and fractality in data, and spatial statistics. In this thesis we show applicability of the wavelets by considering three problems: First, we consider a binary wavelet-based linear classifier. Both consistency results and implemental issues are addressed. We show that under mild assumptions wavelet-based classification rule is both weakly and strongly universally consistent. The proposed method is illustrated on synthetic data sets in which the truth is known and on applied classification problems from the industrial and bioengineering fields. Second, we develop wavelet shrinkage methodology based on testing multiple hypotheses in the wavelet domain. The shrinkage/thresholding approach by implicit or explicit simultaneous testing of many hypotheses had been considered by many researchers and goes back to the early 1990's. We propose two new approaches to wavelet shrinkage/thresholding based on local False Discovery Rate (FDR), Bayes factors and ordering of posterior probabilities. Finally, we propose a novel method for the analysis of straight-line alignment of features in the images based on Hough and Wavelet transforms. The new method is designed to work specifically with Transmission Electron Microscope (TEM) images taken at nanoscale to detect linear structure formed by the atomic lattice.

Geosynthetic Clay Liners (or GCLs) are often used in conjunction with a geomembrane for landfills and heap-leach pads, where their function is to minimize leakage that may occur through holes in the geomembrane. GCLs are installed with overlapping panels and powdered bentonite placed between the overlaps to provide a better seal. Recent field exhumations of GCLs installed beneath a geomembrane left exposed to solar radiation have shown panel shrinkage; in some cases, this shrinkage was enough to leave exposed areas unprotected by the GCL. One hypothesized cause of this shrinkage is cyclic wetting and drying of the GCL. To investigate the hypothesis that wet/dry cycles have the potential to cause irrevocable shrinkage of GCL panels, a total of 8 different products were tested under idealised conditions in the laboratory. Shrinkage was measured using both hand measurements and digital image correlation techniques. A number of variables were tested for their effects on panel shrinkage, including mass per unit area, size and aspect ratio, restraint, moisture content and wetting conditions, and GCL type. Wet/dry cycles were found to cause sufficient shrinkage to explain the shrinkage observed in all but one field case. The shrinkage of any particular product was found to be variable. In particular the shrinkage was found to be sensitive to the distribution of the mass of bentonite within a specimen with the highest shrinkage being observed when there was the greatest variability in mass distribution. It is shown that some GCL products are more prone to shrinkage than others. Consideration is also given to the potential effectiveness of heat-tacking of GCL seams to reduce panel shrinkage in the field. Specimens of GCL which had been heat-tacked in the field were tested under similar cyclic conditions as used in the abovementioned laboratory tests, and the shrinkage response noted. The results indicate that such a technique has promise as a method of inhibiting shrinkage of the two products found to exhibit loss of panel overlap in published field situations. However, more work is required to confirm that this does not create other problems. / Thesis (Master, Civil Engineering) -- Queen's University, 2009-05-31 22:58:36.59

This thesis is concerned with the early-life behaviour of concrete industrial ground floors. Advances in construction methods are placing increased demands on the performance of industrial floors and pushing the limits of the current design guidance. Uncertainties about the true behaviour of industrial floors have been addressed by a programme of in-situ monitoring. An in-situ instrumentation methodology has been developed to monitor the slab and the local climate. Vibrating wire strain gauges and demecs were used to collect concrete shrinkage and joint performance data, whilst thermocouple arrays and thermistors in the strain gauges recorded the slab temperature. This allowed the effects of the cement hydration and the impact of ambient conditions on the slab to be assessed. The use of an automated data collection system allowed the timing as well as the magnitude of the movements to be measured helping identify cause and effect. Floor slabs covering long strip and large area pour construction, jointed and jointless detailing and mesh fabric and fibre reinforcement have been investigated. The data has shown the strong thermal influence on the behaviour of the slabs. Initial joint opening was found to be triggered by the cooling of the slab, whilst the effects of seasonal temperature changes in the first couple of months after construction could be as large if not larger than the drying shrinkage. Frictional resistance was found to reduce the measured movement, whilst the restraint arising from adjacent pours was also found to be significant. Finite element models of the temperature development have been produced using material property data found in the literature. Calibration and verification were carried out using the temperature data collected from site with good agreement. Structural models were then developed using the temperature and degree of hydration output from the thermal analysis as input. These models were used to determine the theoretical stress distribution in slabs at early-ages, and to conduct a parametric study. This demonstrated that the warping stresses present in a slab are generally greater than those from frictional restraint. The thesis concludes with recommendations for the design and construction of industrial ground floors.

The use of stereolithography tools for injection moulding allows plastic parts to be produced in a very short time due to the speed of mould production. The process's greatest advantage is that it can provide a low volume of parts that are produced in the same material and process as parts that would be produced by the conventional hard tooling, but in a fraction of the time and cost. However, this work has demonstrated different rates of polymer shrinkage are developed by parts produced by stereolithography tools and conventional tooling methods. These revelations defy the greatest advantages of the stereolithography injection moulding tooling process—the moulded parts do not replicate parts that would be produced by conventional hard tooling. The aim of this work is to acquire an understanding of the mechanisms in stereolithography tooling that induce these different part properties and develop a modification of the process that could change these, which would allow the moulded parts to demonstrate characteristics like those produced by conventional means.

This investigation involved creep and moisture movement measurements for about six months on 13-course clay (Engineering class B) and calcium silicate brickwork, and 5-course concrete blockwork, consecutively. Four different geometries of masonry were built, namely: single-leaf wall, cavity wall, hollow pier and solid pier, respectively having volume/surface area (V/S) ratios of 44,51,78 and 112 mm. Deformations were also measured on one-brick wide 5 or 6-stack high model brickwalls which were partly sealed to simulate the V/S ratios of the corresponding 13-course brickwork. At the same time, deformations were also measured on individual mortar prisms and brick or block units in order to verify composite model expressions for predicting masonry movements. Simulation of moisture diffusion of the corresponding mortarjoints and embedded bricks or block were made in terms of V/S ratio by partial sealing of the individual mortar prisms and brick or block units. The tests reveal that the modulus of elasticity to be independent of masonry geometry. However, there is a clear influence of geometry on the vertical ultimate creep and moisture movement of all the masonry types i,.e. creep and shrinkage increase with a decrease of V/S ratio. A similar trend occurs for horizontal shrinkage except for the clay brickwork which undergoes moisture expansion. Deformations of the model walls show reasonable agreement with the 13-course brickwork. When results of individual mortar and brick/block specimens are inserted in composite models,the predicted strains show good agreement with the measured strains, particularly in the vertical direction. There is no consistent pattern in the distribution of load and moisture strains for the different masonry geometries, and the measurements reveal that actual strains can be up to 100% higher than the average strains.

Ordinary Least Squares (OLS) models are popular tools among field scientists, because they are easy to understand and use. Although OLS estimators are unbiased, it is often advantageous to introduce some bias in order to lower the overall variance in a model. This study focuses on comparing ridge regression and the LASSO methods which both introduce bias to the regression problem. Both approaches are modeled after the OLS but also implement a tuning parameter. Additionally, this study will compare the use of two different functions in R, one of which will be used for ridge regression and the LASSO while the other will be used strictly for the LASSO. The techniques discussed are applied to a real set of data involving some physiochemical properties of wine and how they affect the overall quality of the wine.