Theoretical and experimental studies of real-time interrogation of fiber Bragg grating (FBG) sensors based on chirped pulse compression with increased interrogation resolution and signal-to-noise ratio are presented. Two interrogation systems are proposed in this thesis. In the first interrogation system, a linearly chirped FBG (LCFBG) is employed as the sensing element. By incorporating the LCFBG in an optical interferometer as the sensor encoding system, employing wavelength-to-time mapping and chirped pulse compression technique, the correlation of output microwave waveform with a chirped reference waveform would provide an interrogation result with high speed and high resolution. The proposed system can provide an interrogation resolution as high as 0.25 μ at a speed of 48.6 MHz. The second interrogation system is designed to achieve simultaneous measurement of strain and temperature. In this system, a high-birefringence LCFBG (Hi-Bi LCFBG) is employed as a sensing element.

The development of communications technologies has led to an ever-increasing requirement for a wider bandwidth of microwave signal processing systems. To overcome the inherent electronic speed limitations, photonic techniques have been developed for the processing of ultra-broadband microwave signals. A dispersive delay line (DDL) is able to introduce different time delays to different spectral components, which are used to implement signal processing functions, such as time reversal, time delay, dispersion compensation, Fourier transformation and pulse compression. An electrical DDL is usually implemented based on a surface acoustic wave (SAW) device or a synthesized C-sections microwave transmission line, with a bandwidth limited to a few GHz. However, an optical DDL can have a much wider bandwidth up to several THz. Hence, an optical DDL can be used for the processing of an ultra-broadband microwave signal. In this thesis, we will focus on using a DDL based on a linearly chirped fiber Bragg grating (LCFBG) for the processing of broadband microwave signals. Several signal processing functions are investigated in this thesis. 1) A broadband and precise microwave time reversal system using an LCFBG-based DDL is investigated. By working in conjunction with a polarization beam splitter, a wideband microwave waveform modulated on an optical pulse can be temporally reversed after the optical pulse is reflected by the LCFBG for three times thanks to the opposite dispersion coefficient of the LCFBG when the optical pulse is reflected from the opposite ends. A theoretical bandwidth as large as 273 GHz can be achieved for the time reversal. 2) Based on the microwave time reversal using an LCFBG-based DDL, a microwave photonic matched filter is implemented for simultaneously generating and compressing an arbitrary microwave waveform. A temporal convolution system for the calculation of real time convolution of two wideband microwave signals is demonstrated for the first time. 3) The dispersion of an LCFBG is determined by its physical length. To have a large dispersion coefficient while maintaining a short physical length, we can use an optical recirculating loop incorporating an LCFBG. By allowing a microwave waveform to travel in the recirculating loop multiple times, the microwave waveform will be dispersed by the LCFBG multiple times, and the equivalent dispersion will be multiple times as large as that of a single LCFBG. Based on this concept, a time-stretch microwave sampling system with a record stretching factor of 32 is developed. Thanks to the ultra-large dispersion, the system can be used for single-shot sampling of a signal with a bandwidth up to a THz. The study in using the recirculating loop for the stretching of a microwave waveform with a large stretching factor is also performed. 4) Based on the dispersive loop with an extremely large dispersion, a photonic microwave arbitrary waveform generation system is demonstrated with an increased the time-bandwidth product (TBWP). The dispersive loop is also used to achieve tunable time delays by controlling the number of round trips for the implementation of a photonic true time delay beamforming system.

The field of X-ray imaging and X-ray diffraction have been combined in a new technique called Tomographic Energy Dispersive Diffraction Imaging (TEDDI). This diffraction imaging technique allows 3D sample images to be obtained, non-destructively, where each imaged point contains the atomic structural information associated with its diffraction pattern. The main drawback of the TEDDI technique is the long collection times needed to produce the images. In order to overcome this obstacle the rapid TEDDI (rTEDDI) system has been developed at the University of Manchester's Material Science Centre. The research and development of rTEDDI has been the focus of this PhD thesis. A proof of concept for the rTEDDI imaging technique was obtained using thin samples on station 7.6 SRS Daresbury. In this case a first generation array collimator was used in conjunction with an energy resolving Si pixelated detector. Structural information such as lattice parameters, crystal system and phase identiffcation were obtained for metal, polymer and deer antler bone samples. The use of high Z semiconductor detector material was investigated in order to increase the potential of TEDDI for larger and more dense samples. To enable penetration of larger samples high energy X-rays needed to be utilized. In order to detect these higher energies with a good efficiency the detector media was changed from Si to CdZnTe (CZT).The second generation rTEDDI, using CZT as the detection media, was intended to be used under high flux/high energy synchrotron radiation conditions. Testing of the system under these conditions on station 16.3 SRS Daresbury showed an inability to produce diffraction imaging. An in depth investigation into detector and collimator array performance showed a two fold cause. The ERD2004 detector was unable to handle the high countrates experienced during high flux/high energy synchrotron radiation conditions. The MK1.2 collimator array was found to become partially transparent to X-ray energies around the absorption edge of W resulting in the swamping of the diffraction signal under high flux/high energy synchrotron radiation conditions. A new detector Application Specific Integrated Circuit (ASIC) design, developed by the detector division and the Rutherford Appleton Laboratory, and Data Aquisition (DAQ) system, developed by Aspect Systems, as well as a number of new collimator array designs were developed and tested. Testing of the new collimator array structures have shown positive results and the new HEXITECdetector which was designed to be able to handle high countrates, have shown an unprecedented inter pixel uniformity and energy resolution which have been attributed to the ASIC performance and the use of better quality CZT material.

The aim of this thesis is to investigate the methodology of three dimensional chemical imaging of nanoparticles through the use of scanning transmission electron microscope (STEM) – energy dispersive X-ray (EDX) spectroscopy. In this thesis, an absorption correction factor is derived for spherical nanoparticles that can correct X-ray absorption effects. Quantification of EDX spectra of nanoparticles usually neglects X-ray absorption within the nanoparticle but may lead to erroneous results, thus an absorption correction is important for accurate compositional quantification. The absorption correction presented is verified through comparison with experimental data of Au X-ray peaks in spherical Au nanoparticles and is found to agree excellently. This absorption correction allows accurate compositional quantification of large ( > 100 nm) particles with STEM-EDX.Three dimensional chemical mapping is achievable through the use of EDX spectroscopy with electron tomography. Here, the methodology of STEM-EDX tomography is fully explored, with a focus on how to avoid artefacts introduced through detector shadowing and low counts per pixel. A varied-time acquisition scheme is proposed to correct for detector shadowing that is shown to provide a more constant intensity over a series of projections, allowing a higher fidelity reconstruction. The STEM-EDX tomography methodology presented is applied to the study of AgAu nanoparticles synthesized by the galvanic replacement reaction. The elemental distribution as a function of the composition of the as-synthesized nanoparticles is characterised and a reversal in the element segregated to the surface of the nanoparticles is found. The composition at which the reversal takes place is shown to correlate with a peak in the catalytic yield of a three component coupling reaction. It is hypothesized that a continuous Au surface results in the optimum catalytic conditions for the reaction studied, which guides the use of galvanically prepared AgAu nanoparticles as catalysts.

The aim of this diploma thesis was create a natural BB cream that, in addition to sufficient hydration, would protect the skin from sunlight, unify its colour tone and at the same time sufficiently cover any imperfections. After proposition a suitable recipe, it was necessary to determine the stability of the prepared BB creams. The stability was evaluated by comparing the results from the dispersion analyser LUMiSizer at various temperatures and current load tests in an oven. The pseudoplastic properties were confirmed by the rheology characterization of the flow properties, which makes the BB cream a continuous layer on the skin after it is spread. In order to protect against sunlight, it was necessary to determine the SPF and measure the colour shades of the prepared BB creams for comparison with commercially available preparations.

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Electric and hybrid vehicles uses regenerative braking, where application of the brake triggers the electric motor to work as a generator to produce electricity, which in turn charges the battery. This results in much less use of the friction brake, changing the corrosion and wear behavior of the rotor surface. There is a need for research on this topic, since fully electric or hybrid vehicles are replacing combustion engines due to concerns about global warming and climate change. Here the corrosion behavior of coated cast iron vehicle rotors in 3.5wt% NaCl is studied. The corrosion study has been performed using electrochemical methods such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). All the coated samples were provided by Pure Forge Rotors. Based on the results from SEM and EDX, the coating is atomic forge proprietary coating, and the base material is gray cast iron. Our primary objective is to study the corrosion behavior of coated, non-coated and friction-tested samples. CV experiments indicate a shift in the corrosion potential and corrosion current density due to changes in the nature of the exposed surface. Cross-sectional SEM showed the thickness of the coating to be 16-23 µm. After friction testing, the friction layer created by rubbing the brake pad over the rotor plays a role in corrosion resistance, but this depends on the type of brake pad material (i.e. semi-metallic, non-asbestos organic and low metallic). Results showed that friction film that forms after testing against non-asbestos organic pads provides the highest corrosion resistance amongst the three brake pad materials.

This thesis presents an analytical treatment of surface waves inside a dielectric slab loaded with a conductive and spatially dispersive semiconductor-like substrate. The work is primarily focused on the modelling of the substrate and getting the field solutions out from the Helmholtz equation. Appropriate boundary conditions have been used in order to get a unique dispersion relation. The surface wave modes are then extracted from the relation by using a root-searching algorithm, which in this work is the MATLAB Genetic Algorithm toolbox. Many different substrate configurations have been considered, starting from the very basic isotropic case to the most complex spatial dispersion case. In between, anisotropicity has also been added to the substrate by turning the static magnetic field on. The permittivity tensors are derived from the fluid transport equations and through the course of the thesis, extra terms such as plasma oscillations, damping, cyclotron resonance, and density perturbations are added. Many assumptions, approximations, and limitations of this analytical treatment have also been addressed. Simulations results have been shown to see the effects of these various terms. The substrates analyzed in the chapters are only a theoritical approximation of an actual substrate. The main idea behind this study is to get a feel for how the transport equations can be utilized to obtain properties that might be on a macroscopic scale. The physical significance of this expose has also been discussed in the last chapter. Issues such as scalability to space plasmas and future ramifications are also included. The study done thus far will be useful in investigating such plasma mediums.

Left ventricular diastolic dysfunction (LVDD) is any abnormality in the filling of the left ventricle (LV).  Despite the prevalence of this disease, it remains difficult to diagnose, mainly due to inherent compensatory mechanisms and a limited physical understanding of the filling process.  LV filling can be non-invasively imaged using color m-mode echocardiography which provides a spatio-temporal map of inflow velocity.  These filling patterns, or waves, are conventionally used to qualitatively assess the filling pattern, however, this work aims to physically quantify the filling waves to improve understanding of diastole and develop robust, reliable, and quantitative parameters. This work reveals that LV filling waves in a normal ventricle act as dispersive waves and not only propagate along the length of the LV but also spread and disperse in the direction of the apex.  In certain diseased ventricles, this dispersion is limited due to changes in LV geometry and wall motion.  This improved understanding could aid LVDD diagnostics not only for determining health and disease, but also for distinguishing between progressing disease states. This work also identifies a limitation in a current LVDD parameter, intra ventricular pressure difference (IVPD), and presents a new methodology to address this limitation.  This methodology is also capable of synthesizing velocity information from a series of heartbeats to generating one representative heartbeat, addressing inaccuracies due to beat-to-beat variations.  This single beat gives a comprehensive picture of that specific patient's filling pattern.  Together, these methods improve the clinical utility of IVPD, making it more robust and limiting the chance for a misdiagnosis. / Master of Science

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