In this study the stabili ty and stress distribution of anisotropic jointed rock slopes under external loading were examined. The influence of joint orientation and mechanical characteristics on the engineering behaviour of jointed rock slopes were included in the investigation. A total of four physical models were developed by using blocks of light-weight concrete and gypsum mortar to simulate intact rocks and joints respectively. The models were built within a confining frame such that plane strain conditions were maintained throughout the experiments. The stress-strain relationship and the strength of the model blocks were determined from laboratory tests. An empirical equation was established to represent the strength envelope of the model material and rocks in general. The normal and shear properties of the model rock JOints were examined, and were described by mathematical expressions in order to facilitate the numerical studies. Results from the physical modelling studies showed that localised failure regions were induced and three types of failure modes were identified. The stability and stress distribution wi thin the models were found to be significantly influenced by the properties and system of the jointing. Two computer programs were developed based on the Finite Element Method and Coupled Finite-Boundary Element Method in order to simulate the behaviour of jointed rock masses and assessments of their application were made in comparison with the physical modelling results. A special finite joint element was developed to incorporate the non-linearity and anisotropy behaviour of rock joints. The finite element program was successfully executed and gave reasonable results in which the principal stress distributions were generally in agreement with those obtained from the physical models. The finite-boundary element program on the other hand introduced boundary incompatibility in the system and therefore led to divergency.

Developmental delays are known to exist in children with autism when compared to their typically developing peers. Foundations of these delays stem from the cognitive and motor performance realm, but information regarding specific characteristics, such as postural stability and sensory integration, are less defined. In this study, postural stability differences were investigated between children with autism and neurotypical children. Past research has shown the role of sensory integration during postural sway has been a strong indicator in showing developmental progress. Due to the focus of the protocol being on static balance, the Modified-Central Test of Sensory Interaction for Balance was used to measure postural stability. The age range for this study is set between 3 and 5 years of age and follows CTSIB protocol to assess 32 neurotypical developing children and compare their results to an archived data set containing CTSIB results from a sample of children with autism. Results from the study indicate that when the autism and neurotypical groups were compared, no significant main effect was found. Developmental differences were found across age groups in that 5 year olds displayed more stability than 4 year olds, but there was no difference between 3 and 4 year olds or 3 and 5 year olds. Further analyses of these developmental results indicated that children in the neurotypical group follow an expected developmental progression while children in the autism group display a divergence from this typical progression. Findings of this research add to the existing literature that children with autism display inconsistent developmental patterns which have a strong relationship with the delayed activity levels of these children. The knowledge and understanding of these delays will allow practitioners to implement specially designed programs to ensure that these children receive the activity that they need and deserve. / text

published_or_final_version / Civil and Structural Engineering / Doctoral / Doctor of Philosophy

No description available.

The thermal stability of two distinct blended polymer systems was examined. A model for polyethylene was used to investigate the vulnerability of polyethylene to premature crosslinking in industrial crosslinking conditions. Careful experiments were conducted to gather evidence of the interaction between a peroxide crosslinking agent and a specific antioxidant additive. Multiple lines of evidence were combined to propose a complete mechanism of interaction between the two species. The mechanism was further tested and a hypothesis was proposed for the reduction in premature crosslinking exhibited when the two species are present in polyethylene blends. A specific aspect of the proposed mechanism warranted further investigation on its own. The acid-catalyzed degradation of the peroxide initiator was thoroughly investigated. The thermal degradation of polyvinyl chloride was also studied. Model compounds were reacted with carboxylates to determine the relative rates of stabilization at various polymer defect sites. These model studies were combined with weight loss and color change investigations of bulk polymer systems. The knowledge gained from the model and polymer studies allowed for the proposal and examination of two novel stabilizing salt systems. The efficacy of the new stabilizers is presented.

No description available.

The goal of this study was to develop a simple means of estimating the cosolvent/water solubility profile using just the available properties (logKow, dielectric constant etc.) of the solute, cosolvent and water. Ethanol was used as the model cosolvent.One of the most commonly used polarity indicators is the octanol/water partition coefficient (logKow). Numerous programs are used to predict the logKow. The calculated values of logKow from three of the most commonly used programs ClogP®, ACD/logPdb® and KowWin® were compared to experimental values. It was found that all three programs have a user friendly interface but ClogP appears to be more accurate.While the ethanol/water solubility profiles of very polar and very non-polar drugs are monotonic, many semi-polar drugs show a maximum solubility at an ethanol volume fraction (fmax) between zero and one. A new empirical function that describes this deviation from linearity was applied to the experimental data forfifty-one compounds. The proposed model was a more accurate predictor of the co-solvent solubility profile than a general third order polynomial with the samenumber of parameters. The fmax value was also accurately predicted from the first derivative of the model.A sigmoidal relationship was observed between the value of fmax and logKow of the solute. Combining this sigmoidal relationship with the previously reportedlinear relationship between logKow and the initial slope of the plot of log solubility vs. ethanol composition enables the estimation of the totalethanol/water solubility profiles of semi-polar compounds from just logKow.A new bilinear function was also introduced to address the deviation from linearity. This model accounts for both the initial and terminal slopes in theethanol/water solubility profiles of semi-polar solutes. The proposed model is dependent only on logKow and an empirical constant that is cosolvent specific. It is also more accurate than the log-linear model and a general parabolic model.A solubility case study using Antalarmin, a novel stress inhibitor was performed.This study illustrates the use of cosolvents as solubility enhancers as well as pH,surfactants, complexants and lipid based systems.

No description available.

Teleoperation systems broaden human ability to perform a task in a real or virtual, local or remote environment. An emerging application of such systems is in dual-user teleoperation or haptic simulation systems in which two users collaboratively perform a task in a shared real or virtual environment. Examples of this application are in human haptic guidance for rehabilitation therapy and medical surgical training. In such collaborative systems, users interact with each other and a user's decision is affected by the other user's decisions. This interaction between users bring out the need for new control architecture design methods. In addition, the controller should maintain system stability and achieve desired performance under various operational conditions, including contact with a wide range of environments and being interfaced with two users displaying highly variable arm dynamics. To this purpose, a class of shared control architectures for human haptic guidance has been developed. The architectures feature a dominance factor that adjusts the supremacy of the trainer over the trainee in the execution of a task. To tackle the stability issue, a novel robust stability analysis framework for unconditional stability analysis of multi-user teleoperation/haptic systems has been proposed. In terms of performance these systems have been evaluated kinesthetically, referring to the dynamics felt by the users, or task-based, referring to the quantities that measure task efficiency and effort. For kinesthetic performance evaluation of dual-user systems as opposed to the single-user systems, there are two users interacting with the environment and with each other. In these systems it may be desirable for a user to not only feel the environment but also to sense the other user dynamics. Hence, some of the previously defined performance measures for single-user systems have been extended for dual-user systems. Furthermore, two novel performance measures for multilateral dual-user systems have been introduced. Finally, to assess the task-based performance of the proposed architectures, a user study has been conducted for trajectory following tasks on a developed dual-user haptic simulation testbed under various environmental conditions, such as different environment geometries, environment view points and environment dynamics. / Thesis (Ph.D, Electrical & Computer Engineering) -- Queen's University, 2010-11-22 18:38:05.142

The objective of this work is to develop mathematical models for predicting the thermal stability of commercial diagnostic assays. These assays are a product of the Point of Care division of Abbott laboratories, and are used for analyzing patient blood samples for specific substances. The accuracy of the results from these diagnostic tests relies on the activity of specific biological and/or chemical components of the sensors. Mathematical models that describe the stability of these active components are useful for supporting product shelf-life claims and for the design and implementation of accelerated testing protocols. In the thesis, the stability of two diagnostic assay systems of interest to Abbott Point of Care is investigated using mathematical modeling. For the first assay system investigated, the biosensor associated with the assay is identified as an important factor for product stability. A second-order dynamic model is developed to describe the thermal stability of this biosensor. The model corresponds to a reversible reaction followed by an irreversible reaction, with rate coefficients having Arrhenius temperature dependencies. The second-order dynamic model provides improved predictions relative to a first-order dynamic model, based on a comparison between model fits for two experimental datasets, and a comparison of predictive ability for a validation dataset. The second-order dynamic model is used to extend the concept of Mean Kinetic Temperature concept from the pharmaceutical industry to systems with higher-order dynamics. For the second assay system investigated, the calibration fluid is identified as a key factor in assay stability. A first-order model is developed to describe the stability of the analyte within the calibration fluid. The first-order model captures most of the trend present in the data from calibration fluid incubation experiments. Finally, model predictions are used to investigate the amount of change in assay response that can be attributed to changes in concentration of analyte in the calibration fluid (after storage at elevated temperatures). The results show that the changes observed in assay responses are consistent with the magnitude of changes in calibrant analyte concentrations predicted by the model. / Thesis (Master, Chemical Engineering) -- Queen's University, 2011-02-02 00:09:23.758