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The field of energy absorption is definitely one the most important in engineering design, as many types of static and dynamic structures, designed and built for different purposes and tasks, require energy absorption capabilities under loading conditions. This thesis is aimed at the introducing experimental and theoretical analyses of a novel and revolutionary technique to dissipate unwanted energy in engineering systems. An extensive literature review on existing energy absorbers was undertaken in relevant application fields such as structural and personal protection. Hence, devices attached to buildings and designed to dissipate energy due to severe earthquakes have been discussed and compared. Types considered, in this review, are mainly based on friction, viscoelasticity and material yielding mechanisms. Furthermore, methodologies to strengthen structures against impacts such as those used in armoured walls are described, and their capabilities assessed. In addition techniques to protect the human body against dangerous loads were reviewed, and important issues for chest and head protection, leg defences in football and safety in motorcycles have been investigated. Experimental results about energy absorption in crash tests have been studied. Also, as an example the use of current technologies to dissipate energy during landing operations in aircrafts have been considered. A classified chart of energy absorption devices in different applications has been produced and referenced. In general most energy absorption devices were shown to be capable to eventually dissipate dangerous and unwanted energy, but poor reusability and predictability after impact were not part of the design process. The research base in this thesis is a novel energy dissipation technique capable of designing Universal Reusable Energy Absorption Devices (UREAD). This technique exploits the principles and working mechanisms that are used in extrusion of deformable materials through intersecting channels. Such mechanism of deformation is known in literature as Equal Channel Angular Extrusion (ECAE). ECAE is one of the severe plastic deformation processes. A theoretical analysis of internal pressure and stresses developed at the interface with the tools has been presented for channels of different geometrical parameters. In addition, energy absorption capabilities have been analysed by the Upper Bound ii method. Also, a numerical solution based on the implementation of the Finite Element Analysis, in ANSYS commercial package was obtained to show the intensity of stress distribution in the deforming material and the tools surrounding it. UREAD devices of different dimensions and geometries were designed, manufactured and tested using an experimental set up constructed for this work. Circular and square cross-sectional channels were tested using various deformable materials. Experimental results were compared with theoretical distributions, and several analogies were highlighted and discussed. Special tools were designed and manufactured to study experimentally the normal stresses at contact surfaces using the so called “Pressure Pin Technique”. Also, an experimental apparatus has been built to simulate the potential implementation of UREAD devices against the occurrence of heavy impacts and the effect of the energy absorber was experimentally measured at the instant of ground impact.

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Process modelling is the activity of constructing and analyzing models, which are applicable and useful to solve predefined problems. It allows engineering process to be analyzed, and consequently leads to quality and efficiency improvement. As metrology becomes increasingly important in modern manufacturing, process modelling based on measurement techniques and operations becomes necessary and valuable. Measurement uncertainty, which is obtained from measurement operation, is regarded as a key factor in metrology-based process modelling. By analyzing measurement uncertainty, metrology-based process models can tangibly improve manufacturing quality and efficiency, improve the actualize communication between design and manufacturing, and, ultimately, achieve product lifecycle integration between design, manufacturing and verification functions. Digital measurement models can simulate measurement process, and predict task-specific measurement uncertainty in the digital environment, before carrying out capital-consuming physical measurements. However, the integration between digital and physical measurement environments is not fully approved. Measurement uncertainty predicted by the digital measurement model may show little practical significance with that obtained from physical measurements. The quality of digital measurement result highly relies on input quantities loaded into the digital measurement model. And it is hardly possible to verify digital measurement results for all of the measurement scenarios because of the high variability and complexity of inspected features and measurement tasks. This research has reviewed the fundamental technologies relating to measurement process modelling and measurement uncertainty evaluation in a digital environment, especially for coordinate measurement machines (CMMs). An initial verification work has been carried out by ‘measuring’ small features on a large-volume component in a realistic shop floor environment. This verification work has realized the limitations of the digital measurement model, and the challenge of integrating digital and physical measurement environments. Based on the initial verification work, a Measurement Planning and Implementation Framework has been proposed, aiming to analyse and improve the relationship between digital and physical measurement environments. The Framework is deployed with the statistics methods to analyse measurement uncertainty obtained from the digital and the physical measurement environments, and quantitatively predict influence levels of measurement uncertainty contributors. The verification work of the Framework has been carried out in a finely-control laboratory environment with environmental control. The robustness of the Framework has been evaluated, indicating the potential of deploying statistical methods for measurement uncertainty analysis, which extends the utilization of measurement uncertainty for decision-making processes. The contributions to knowledge of the research include: (1) Verification of the performance of a digital CMM model under meaningful measurement scenarios; (2) Development of a metrology-based process modeling framework to integrate digital and physical measurement environments through quantitative measurement uncertainty analysis.

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Mechanical properties of biological tissue are involved in a wide range of modern advances of medical science and technology. The mechanical property of biological tissue is directly related to the functionalities of tissue or organ, hence the in-depth knowledge of tissue mechanical property could lead to many benefits in medical research and health care. In clinical practice, accurate estimation of tissue mechanical property may facilitate to predict any possible pathological alterations, or to propose artificial intervention approaches. With the purpose of a quantitative, directly visualized estimation of biological tissue mechanical property, numerous research works in elastography have been conducted and had been successfully applied to countless clinical applications. Elastography techniques had been always rooted in medical imaging technique, classified into a range of scales, based on their imaging depth and resolution performance. In the scale of tissue micro structure, elastography is still a relatively new field, enabled by the recent advances in high-resolution medical imaging techniques e.g. high-frequency ultrasound imaging and Optical Coherence Tomography (OCT). The quantitative elastography technique based on OCT, known as quantitative optical coherence elastography (OCE) is a new research field, promising high-resolution quantitative elastography information with minimal contact that is not achievable by other imaging modalities. The aim of the thesis is to develop a multiple-functional OCT system to image the microstructure of biological tissue, meanwhile quantify localised mechanical property in the region of interest, and further apply it for pre-clinical research applications. Starting from the numerical model of mechanical waves, the behaviours of shear waves and surface waves in biological tissue is studied. Contact mechanical stimulations, as well as non-contact ultrasound and pulsed lasers are utilised to generate transient waves in biological samples. High speed shear wave imaging technique is developed and optimized based on a Phase-sensitive OCT (PhS-OCT) system to capture the transient wave propagation in samples, and the inversion algorithm for mapping localized shear modulus is proposed. The experimental results indicated that the Shear Wave Imaging OCT (SWI-OCT) technique is capable to provide abundant temporal and spatial resolution to capture the shear waves in tissuemimicking phantoms and in vivo biological samples. Quantitative elastography results were obtained from mouse skin and cornea samples, suggesting potential diagnostic and therapeutic clinical applications.

A steady-state model of a binary distillation column is derived from material balance considerations and a digital computer programme is described which calculates the vapour and liquid flow-rates at each plate in the column. Theoretical and experimental results are shown to agree closely, and a dynamic model of the column is derived which, when programmed on a digital computer enables the transient behaviour for large disturbances to be calculated. Agreement with plant data is presented both for step and P.R.B.S. disturbances in the column operating variables. It is further shown how to simplify the complex system of describing equations to a 2nd-order discrete time form, a simplification which is validated by plant measurements. The use of these models in designing closed-loop controllers is discussed and their implementation by a digital computer used to regulate the top-product composition by controlling the Reflux Ratio is described. The same control algorithms are also used to change the set-point of the top-product composition.

This work explores the prospects of polymeric micro and nanofibres as drug delivery systems intended to facilitate transport of progesterone across vaginal mucosa by mucoadhesion. These fibres, due to their physical attributes, ability to improve drug solubility and high adsorption efficiency may be adapted for improved trans-mucosal drug delivery. Mucoadhesion on the other hand is being explored for improved dosage form residence times, targeting and therapeutic efficacy. Notwithstanding the potential utility of mucoadhesion and nanofibres, generating substantial amounts of mucoadhesive fibres is fraught with many challenges. In this work, pressurised gyration, a novel approach combining centrifugal force and pressure was used to produce fibres from combinations of polyethylene oxide (PEO), carboxymethyl cellulose sodium (CMC), sodium alginate and polyacrylic acid; polymers with inherent mucoadhesive properties. Nanofibres generated were characterised using scanning electron microscopy, infra-red and x-ray diffraction analyses to determine their morphology, size distribution and molecular composition. Furthermore, they were assessed by texture analyser and atomic force microscope for mucoadhesive performance after which PEO/CMC blends were selected for drug (progesterone) loading. The progesterone-loaded fibres were assessed, mainly for drug release and mucoadhesion. A new methodology based on classical mucoadhesion theories, where atomic force microscopy was used to map interfacial roughness and voids in adhering surfaces was developed for quantifying mucoadhesive properties of systems produced. In conclusion, this work has demonstrated the possibility of generating drug-loaded fibres as potential constructs for developing vaginal dosage forms for improved performance facilitated by mucoadhesion. Furthermore, a new approach to quantifying mucoadhesion between fibres and mucosa by AFM was developed, with outcome correlating favourably with forces required to detach interacting surfaces measured by texture analyser.