This thesis addresses the need for adaptability in vision systems that measure system state information in a sensory feedback role for the control and coordination of flexible discreteitem materials handling operations, such as those performed by a robotic palletising system. In addition, this thesis addresses the need for vision systems that are more easily configured by users, such as factory technicians and operators, who have lower skill levels than those generally required to (re-)configure a machine vision system. In response, a unique coupling mechanism and intuitive human-computer interface have been developed, hiding the complexity of image analysis from the end-user and simplifying the way that a machine vision system is configured. The mechanism couples machine vision-related "visual checks” to materials handling tasks in a generic framework of materials handling activities. Visual checks which define what control information is required are implicitly linked to image analysis functions which define how that information is extracted from digitised images of a materials handling system. Consequently, this research has developed a set of task - visual check "building blocks" that can be used in various combinations to define the sequence of actions and image analysis required to perform a variety of materials handling operations. In addition, a number of pre-defined task – visual check combinations and mechanisms for manipulating them have been developed, providing solution templates that can be used immediately or modified to suit application-specific requirements. These developments have been realised together with several aesthetic, ergonomic and functional features in a machine vision configuration interface, known as SlyVision. SlyVision's modularity, extensibility and upgradeability expressed to both the end-user and the system developer through its underlying object oriented architecture and intuitive user interface design make important contributions to its overall adaptability. Demonstrations involving a typical palletising and a de-palletising operation have shown how SlyVlsion is used to specify visual checks and configure the associated machine vision components without requiring the end-user to select or apply image analysis techniques or functions. In addition, the relative simplicity of the configuration process is demonstrated. Consequently, these developments assist people with limited understanding of machine vision technology to set up and maintain a vision system, thereby improving their ability to keep pace with frequent changes in their materials handling operations, while limiting the cost in time, money and effort required to (re-)configure a vision system. / Whole document restricted, but available by request, use the feedback form to request access.

Although the current thermoacoustic theory has so far proved successful in allowing us to analyse and understand thermoacoustic systems, there are inherent limitations associated with it. These are related to the fact that this theory is based on linear approximations. As designers search for ways to increase the efficiency and power density of thermoacoustic devices the accuracy of the linear theory decreases significantly, as a variety of non-linear effects start to become important. For example, when the pressure amplitude is increased, in order to increase the power density. This thesis concentrates on the non-linear effect of acoustic streaming. Acoustic streaming is a steady flow that is superimposed upon the acoustic Oscillations. An expression for the streaming velocity is developed for a parallel plate channel having an arbitrary gap width, so that the solution is valid for both thin and wide boundary layers. The solution includes thermal effects arising from the presence of an axial temperature gradient along the channel, and arbitrary phase between the pressure and velocity. An essential feature of the streaming velocity is the generation of circulating loops, which can cause heat to be convected within the channel. An expression for the transverse steady state temperature was also derived, for similar conditions as outlined for the streaming velocity. It was found that when an axial temperature gradient is present the magnitude of the transverse steady state temperature increases significantly as the width of the channel increases. The implication of this is that a significant amount of heat can be convected along the channel due to the action of the streaming velocity. When no axial temperature gradient is present, the transverse steady state temperature reduces to a small constant value outside the boundary layer. A numerical finite difference scheme was developed to model non-linear flow within the two-dimensional channel. The model solves for the conjugate fluid-solid problem enabling the temperature difference induced along the channel to be predicted. The model compared very well to experimental data. It was also found to be in excellent agreement with the analytical solutions for the streaming velocity and the transverse steady state temperature. The effect of streaming on the energy flux density was examined for a wide channel, having a temperature gradient along its length. A fourth-order expression was developed, which yielded a solution in terms of the transverse steady state temperature and second-order mass flux, which for certain conditions could be of a similar magnitude as the second-order terms. For a thermoacoustic core, it was proposed that a toroidal flow could form and convect heat from one heat exchanger to the other. To analysis this effect toroidal flow was incorporated into an expression for the temperature difference induced across a thermoacoustic couple. This result was found to be in excellent agreement with experimental data. The effect of toroidal streaming on the thermoacoustic core was also considered. In addition, a second-order expression for the work flux was derived that included a previously ignored term due to acoustic streaming.

A new theoretical characterisation is developed for the off-axis stiffness of FRP materials. The theoretical model treats an off-axis unidirectional ply as an inhomogeneous material, and considers the effect of rigid body rotations of the fibres within the matrix material. Linear analytical, and nonlinear finite element solutions are developed for the model. The differences between the new model and the traditional homogenous orthotropic characterisation are functions of both the strain level, and the relative modulus ratio (Ef/Em) of the constituent materials. For relative constituent moduli typical of most common FRP materials, there are significant differences between the new Rigid Body Motion (RBM) model and homogenous orthotropic characterisations at strains greater than 1%. In a 30° case with Ef/Em = 100 and a strain level of 2%, the RBM theory predicts a longitudinal modulus 11% higher than the linear orthotropic theory. At small strain levels the RBM theory reduces to the homogenous orthotropic approximation. A simple and reliable methodology is developed and verified for the experimental characterisation of off-axis tensile FRP specimens. The method applies a tensile load to a thin walled tubular specimen through a high strength, small diameter length of steel wire. The low torsional stiffness of the wire allows one end of the tube to rotate, thus preventing any torsional constraint. Analytical and experimental verifications both indicate that the required tensile load can be applied to tubular specimens without significant torsional constraint. The wire based testing method is used to measure the off-axis stiffness properties of carbon/epoxy tubular specimens at a range of fibre orientations.

This dissertation introduces the Artificial Computer Expert (ACE), a system designed to assist non-computer skilled personnel utilise complex computer software through the use of artificial intelligence in the creation, selection and execution of programs. The system comprises three parts: 1. A graphical interface and conceptual framework which allows an expert to define the structure of his knowledge relating to his field. 2. A compiler to work through such a structure, forming partial solution paths which indicate the relationships that exist in the structure. 3. An interpreter to run through the solution process, joining together the partial solution paths and creating instances of data files as required in order to reach the overall goal. The ACE system is presented in the context of an industrial application, demonstrating how it may be used to form sawmill cutting patterns (which indicate how lumber is to be milled from a set of logs). This application belongs to a class of scheduling problems known as ‘cutting stock problems’, which for anything other than small or simple cases typically require the presence of an on-site scheduling expert. The application developed produces acceptable cutting patterns without the need for such a scheduling expert, using the same software tools currently used by mill management to plan their production. / Whole document restricted, but available by request, use the feedback form to request access.

Diffuser Augmented Wind Turbines (DAWTs) are one of many concepts to have been proposed to reduce the cost of renewable energy. As the most commercially viable, they have been the focus of numerous theoretical, computational, and experimental investigations. Although intimated in these studies to be able to augment the power output of a wind turbine, the extent of this power increase, or augmentation, the factors influencing DAWT performance, the optimal geometric form and their economical benefit remained unanswered. It is these issues that have been addressed in this investigation. In reviewing historic investigations on DAWTs it has been identified that excessive wind tunnel blockage, inappropriate measurement technique, varied definitions of augmentation, and the inclusion of predicted performance based on incorrect assumptions have in general led to the overstatement of DAWT performance in those studies. In reassessing the performance of the most advanced of those DAWT designs, Grumman's DAWT 45, it has been calculated that the actual performance figures for the 2.62 exit-area-ratio and 0.488 length-to-diameter ratio DAWT were an available augmentation of 2.02, a shaft augmentation of 0.64 and a diffuser efficiency of 56%. By contrast, the development of the Mo multi-slotted DAWT in this investigation has yielded a design whose shaft augmentation of 1.38 was achieved by a diffuser with exit-area-ratio of only 2.22 and overall length-to-diameter ratio of 0.35. Such performance improvement has been obtained by gaining both an understanding of the flow characteristics of DAWTs and the geometric influences. More specifically it has been shown that: the velocity across the blade-plane is greater than the free-stream velocity and increases towards the rotor periphery; that the rotor thrust or disc loading impacts upon diffuser performance by altering the flow behaviour through it; and that DAWTs are able to maintain an exit pressure coefficient more negative than that attainable by a conventional bare turbine. The net result is that DAWTs encourage a greater overall mass-flow as well as extract more energy per unit of mass-flow passing through the blade-plane than a conventional bare turbine. The major drivers of DAWT performance have been shown to be the ability of the design to maximise diffuser efficiency and produce the most sub-atmospheric exit pressure possible. Parametric investigation of the various DAWT geometric components has shown peak performance to be obtained when: the external flow is directed radially outward by maximising the included angle of the external surface in conjunction with a radially orientated exit flap; by applying boundary-layer control to a trumpet shaped diffuser via a pressurised cavity within the double-skin design of the multi-slotted DAWT; having an exit-area-ratio of the order of 2.22; and by employing an inlet contraction with inlet-area-ratio matched to the mass-flow passing through the DAWT under peak operating conditions. To translate the available augmentation into shaft power a modified blade element method has been developed using an empirically-derived axial velocity equation. The resulting blade designs whose efficiencies reached 77%, twice those of Grumman, highlight the accuracy of the modified blade element method in calculating the flow conditions at the blade-plane of the multi-slotted DAWT. It was also noted that the rotor efficiencies remain below 'best practice' and therefore offer the potential for further increases in shaft augmentation. However, in order to achieve such gains, a number of limitations present in the current method must be addressed. In assessing the likely commercial suitability of the multi-slotted DAWT a number of real-world influences have been examined. Shown to have little if any effect on DAWT performance were Reynolds number, ground proximity and wind shear. Turbulence in the onset flow on the other hand had the beneficial effect of reducing separation within the diffuser. Finally, DAWT performance was assessed under yaw misalignment where it was shown that the multi-slotted DAWT performed favourably in comparison to that associated with a conventional bare turbine. The major drawback identified in the DAWT concept by this investigation was its drag loading and the fact that drag and augmentation were interdependent. The result is that the cost of a conventional DAWT is dictated by the necessity to withstand an extreme wind event despite the fact that augmentation is only required up to the rated wind speed. The overall conclusion drawn was that in order to optimise a DAWT design economically, and therefore make the DAWT concept a commercial reality, a creative solution that minimises drag under an extreme wind event would be required.

The mechanical properties of glassy poly (methyl methacrylate) have been examined by means of constant strain-rate tests at differing strain-rates and temperatures. Both fast-cooled and slow-cooled samples have been examined in order to determine the effect the rate of cooling has upon the mechanical properties. The ß and α’ relaxations were revealed in the experimental results. The difference in mechanical properties of fast- and slow-cooled samples could not be satisfactorily explained by the theory of Rusch.

This thesis addresses the need for adaptability in vision systems that measure system state information in a sensory feedback role for the control and coordination of flexible discreteitem materials handling operations, such as those performed by a robotic palletising system. In addition, this thesis addresses the need for vision systems that are more easily configured by users, such as factory technicians and operators, who have lower skill levels than those generally required to (re-)configure a machine vision system. In response, a unique coupling mechanism and intuitive human-computer interface have been developed, hiding the complexity of image analysis from the end-user and simplifying the way that a machine vision system is configured. The mechanism couples machine vision-related "visual checks” to materials handling tasks in a generic framework of materials handling activities. Visual checks which define what control information is required are implicitly linked to image analysis functions which define how that information is extracted from digitised images of a materials handling system. Consequently, this research has developed a set of task - visual check "building blocks" that can be used in various combinations to define the sequence of actions and image analysis required to perform a variety of materials handling operations. In addition, a number of pre-defined task – visual check combinations and mechanisms for manipulating them have been developed, providing solution templates that can be used immediately or modified to suit application-specific requirements. These developments have been realised together with several aesthetic, ergonomic and functional features in a machine vision configuration interface, known as SlyVision. SlyVision's modularity, extensibility and upgradeability expressed to both the end-user and the system developer through its underlying object oriented architecture and intuitive user interface design make important contributions to its overall adaptability. Demonstrations involving a typical palletising and a de-palletising operation have shown how SlyVlsion is used to specify visual checks and configure the associated machine vision components without requiring the end-user to select or apply image analysis techniques or functions. In addition, the relative simplicity of the configuration process is demonstrated. Consequently, these developments assist people with limited understanding of machine vision technology to set up and maintain a vision system, thereby improving their ability to keep pace with frequent changes in their materials handling operations, while limiting the cost in time, money and effort required to (re-)configure a vision system. / Whole document restricted, but available by request, use the feedback form to request access.

Although the current thermoacoustic theory has so far proved successful in allowing us to analyse and understand thermoacoustic systems, there are inherent limitations associated with it. These are related to the fact that this theory is based on linear approximations. As designers search for ways to increase the efficiency and power density of thermoacoustic devices the accuracy of the linear theory decreases significantly, as a variety of non-linear effects start to become important. For example, when the pressure amplitude is increased, in order to increase the power density. This thesis concentrates on the non-linear effect of acoustic streaming. Acoustic streaming is a steady flow that is superimposed upon the acoustic Oscillations. An expression for the streaming velocity is developed for a parallel plate channel having an arbitrary gap width, so that the solution is valid for both thin and wide boundary layers. The solution includes thermal effects arising from the presence of an axial temperature gradient along the channel, and arbitrary phase between the pressure and velocity. An essential feature of the streaming velocity is the generation of circulating loops, which can cause heat to be convected within the channel. An expression for the transverse steady state temperature was also derived, for similar conditions as outlined for the streaming velocity. It was found that when an axial temperature gradient is present the magnitude of the transverse steady state temperature increases significantly as the width of the channel increases. The implication of this is that a significant amount of heat can be convected along the channel due to the action of the streaming velocity. When no axial temperature gradient is present, the transverse steady state temperature reduces to a small constant value outside the boundary layer. A numerical finite difference scheme was developed to model non-linear flow within the two-dimensional channel. The model solves for the conjugate fluid-solid problem enabling the temperature difference induced along the channel to be predicted. The model compared very well to experimental data. It was also found to be in excellent agreement with the analytical solutions for the streaming velocity and the transverse steady state temperature. The effect of streaming on the energy flux density was examined for a wide channel, having a temperature gradient along its length. A fourth-order expression was developed, which yielded a solution in terms of the transverse steady state temperature and second-order mass flux, which for certain conditions could be of a similar magnitude as the second-order terms. For a thermoacoustic core, it was proposed that a toroidal flow could form and convect heat from one heat exchanger to the other. To analysis this effect toroidal flow was incorporated into an expression for the temperature difference induced across a thermoacoustic couple. This result was found to be in excellent agreement with experimental data. The effect of toroidal streaming on the thermoacoustic core was also considered. In addition, a second-order expression for the work flux was derived that included a previously ignored term due to acoustic streaming.

A new theoretical characterisation is developed for the off-axis stiffness of FRP materials. The theoretical model treats an off-axis unidirectional ply as an inhomogeneous material, and considers the effect of rigid body rotations of the fibres within the matrix material. Linear analytical, and nonlinear finite element solutions are developed for the model. The differences between the new model and the traditional homogenous orthotropic characterisation are functions of both the strain level, and the relative modulus ratio (Ef/Em) of the constituent materials. For relative constituent moduli typical of most common FRP materials, there are significant differences between the new Rigid Body Motion (RBM) model and homogenous orthotropic characterisations at strains greater than 1%. In a 30° case with Ef/Em = 100 and a strain level of 2%, the RBM theory predicts a longitudinal modulus 11% higher than the linear orthotropic theory. At small strain levels the RBM theory reduces to the homogenous orthotropic approximation. A simple and reliable methodology is developed and verified for the experimental characterisation of off-axis tensile FRP specimens. The method applies a tensile load to a thin walled tubular specimen through a high strength, small diameter length of steel wire. The low torsional stiffness of the wire allows one end of the tube to rotate, thus preventing any torsional constraint. Analytical and experimental verifications both indicate that the required tensile load can be applied to tubular specimens without significant torsional constraint. The wire based testing method is used to measure the off-axis stiffness properties of carbon/epoxy tubular specimens at a range of fibre orientations.

This dissertation introduces the Artificial Computer Expert (ACE), a system designed to assist non-computer skilled personnel utilise complex computer software through the use of artificial intelligence in the creation, selection and execution of programs. The system comprises three parts: 1. A graphical interface and conceptual framework which allows an expert to define the structure of his knowledge relating to his field. 2. A compiler to work through such a structure, forming partial solution paths which indicate the relationships that exist in the structure. 3. An interpreter to run through the solution process, joining together the partial solution paths and creating instances of data files as required in order to reach the overall goal. The ACE system is presented in the context of an industrial application, demonstrating how it may be used to form sawmill cutting patterns (which indicate how lumber is to be milled from a set of logs). This application belongs to a class of scheduling problems known as ‘cutting stock problems’, which for anything other than small or simple cases typically require the presence of an on-site scheduling expert. The application developed produces acceptable cutting patterns without the need for such a scheduling expert, using the same software tools currently used by mill management to plan their production. / Whole document restricted, but available by request, use the feedback form to request access.