The effect of the three intrinsic length scales of the medium (the bubble size $R sb0$, the interbubble spacing d and the tube diameter D) on the velocity and structure of the self-sustained reactive waves (SSRW) were investigated experimentally. The gas-liquid system studied consisted of water and stoichiometric or equimolar oxyacetylene. Two different tubes ($D=63mm$ and $D=146mm$) and two different average bubble sizes $R sb0=1mm$ and $R sb0=2mm$) were used, whereas the volumetric void fraction (which affects the bubble spacing d) was varied between 0.4% and 4%. Thus the conditions in the medium are always such that $R sb0<<d<<D$. For these conditions the experimental results indicate that: (1) the bubble size affects the structure but not the velocity of the SSRW; (2) the velocity of the SSRW increases when the bubble spacing is increased; (3) the SSRW is not affected by the tube diameter. / The most important conclusion of this work is that combustion waves in bubbly liquids are not of the thermodynamic type, nor of the reactive-diffusive type. It is suggested that the phenomenon is of the "reactive-dissipative" type, where a dynamic equilibrium occurs between reaction and dissipation in the medium.

This thesis presents a generic model for crossflow heat exchangers with one fluid mixed, suitable for dynamic process simulation. A finite difference technique is used to formulate the coupled flow and energy solutions for arbitrary transients in pressure drop and temperature. / The solution algorithms are presented in two forms: one-way dependence and two-way dependence: for the constant and variable property version of the model, respectively. Variable time step algorithms are also developed to predict the optimal time step for the finite difference solution. The first one uses a first order predictor method and the second one uses a combined first/second order predictor method. / Finally, the generic model is configured to model the economizer and tubular air preheater of an existing boiler. Steady-state tests validate the numerical solution against available theoretical relations and transient tests investigate the parameters in the solution and time step algorithms to determine their effect on simulation speed and accuracy.

This thesis presents a probabilistic model, specifically a nonhomogeneous Markov model, for the description of fatigue crack growth. This model is capable of predicting the statistics of crack growth, the mean crack size and the variance in the crack size, at future times given two empirically determined system parameters, $ lambda$ and $ kappa$, and an initial crack size distribution. Prior to the mathematical development of this model a brief review of existing crack growth models is presented. After the mathematical development of the model has been presented the results from a previous application in the study of pitting corrosion are presented. Following this, the results from the modelling of several existing fatigue data sets are examined in order to determine the necessary empirical material parameters and also to verify the model's applicability. Once the model has been verified and the empirical parameters determined one data set is chosen in order to illustrate the uses of this model for component reliability predictions. These uses include reliability at a future time, inspection optimization and the effect of changes in repair policy on reliability.

Aeroelasticity is concerned with the interaction of aerodynamic forces and the resulting structural deformations for a structure in an airflow. Flutter, which is one example of an aeroelastic phenomena, may result in the catastrophic failure of an aircraft. The traditional methods of predicting the flutter velocity, namely the $U - g$ and $p - k$, have been used with great success. However, in recent years, new methods have been suggested which approximate the unsteady aerodynamic forces and moments by rational functions. The resulting equations are then solved in the Laplace domain. The goals of this work are twofold. Firstly, to solve the equations of motion for an airfoil, in both incompressible and transonic flow, in the Laplace domain using rational functions to approximate the unsteady aerodynamics. Secondly, to implement active control for the airfoil in incompressible flow with the aim of increasing the critical flutter speed. The solution of the aeroelastic equations of motion in the Laplace domain proved to be a powerful tool in the analysis of flutter.

Two series of experiments were conducted to investigate the heat transfer processes from open channel flow to an ice block and an array of ice blocks. The first series of twelve tests were conducted to determine the heat transfer rate from the open channel crossflow to a single isolated ice block. During the experiment the ice block was gradually lowered into the crossflow while maintaining a constant volume of submergence. The ice block which initially had the shape of a circular cylinder, changed gradually to the shape of a cone yielding to the thermal erosion by the crossflow. The heat-transfer rate from the crossflow to the ice cone was greater than the rate to a hemisphere and also the rate to a circular cylinder. This higher heat transfer rate associated with the cone is explained by a 'heat-transfer concentration' phenomenon associated with the tip of the ice cone. / In the second series of experiments, a packed array of ice blocks in the tightest arrangement was used to simulate a brash ice cover in the open channel flow. Six tests were conducted. The heat transfer rate from the open-channel flow to the brash ice cover was significantly higher than the rate to a smooth surface. The increase in heat transfer rate due to the 'roughness effect' was as high as 300 percent. However, due to the 'sheltering effect', the heat transfer rate from the flow to each of the ice cone in the array was only 35 percent of the rate to a single isolated ice cone with the same volume of submergence.

The prediction of fatigue life and evaluation of onset and growth of matrix cracks and delamination for general composite laminates are studied analytically using theories of damage tolerance, residual modulus degradation and residual strength degradation. Damage onset including matrix cracks and edge delamination are predicted by using a total strain energy release rate criterion which accounts for interactive effects of matrix cracks and delamination. The analytical models for modulus degradation, matrix crack density and delamination size growth as function of fatigue stress and fatigue cycles are proposed. The proposed approach provides four choices for predicting tension-tension fatigue life and for assessing fail-safety for structures made of composite laminates. The direct relation of physical damage to fatigue life and analytical equations for calculating residual elastic moduli E$ rm{ sb1, E sb2, v sb{12}}$ and G$ sb{12}$ in terms of fatigue load and fatigue cycles are proposed. The proposed approach enables prediction of fatigue behaviour of general laminates using experimental data of a basic lay-up such as unidirectional laminate. The finite element technique was utilized to model the fatigue failure process of notched laminates. A simple example of a laminate with a central hole under tension-tension fatigue loading was performed.

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