The Fan Coil Unit (FCU) is an integral part of heating, ventilation and air conditioning systems used in residential and commercial buildings. One main component of this device is a multi-tube and fin heat exchanger. Improvement of thermal performance in such heat exchangers is vital for improved performance of FCU. Performance improvements in the FCUs are mainly limited by available technology, manufacturing capabilities and overall cost effectiveness of the design. Better thermal performance usually comes at a cost of higher pressure drop or more expensive materials and manufacturing costs. In this thesis, a global framework for design and optimisation was developed taking into account overall costs of design, manufacturing and operation. Full 3D CFD models of multi-tube and fins heat exchanger were developed to investigate complex and non-uniform flow on water and air sides of the device. The CFD models were developed to enable local heat transfer analysis within the FCU. Experimental setup to evaluate performance of the heat exchanger has been designed and built. Different configurations of heat exchanger were tested experimentally and numerically, including the baseline configuration, so called plain fins. More efficient design of louvre fins and and fins with vortex generating mechanism (perforation in the fin surfaces) were also investigated. Best thermal performance was found to be for the perforated louvre fins. CFD model was validated against experimental results and obtained data was used to create a novel semi-analytical prediction model for Fanning friction factor (f) and Colburn factor (j). Appropriate costs calculation model was also developed and employed for total costs estimation of the FCU over the period of 15 years. The framework proposed in this thesis for optimised design and development strategy of heat exchangers resulted in development of a novel design which offers significant improvements in comparison to the current design. This new optimised design of the heat exchanger (with perforation in louvre fins) increased thermal performance by additional 10% while the total costs increased by only 6%.

Rapid depletion of energy resources has immensely affected the transportation industry, where the cargo transportation prices are going considerably high. Efforts have been made to develop newer economic and environmental friendly modes of cargo transportation. One such mode is the use of energy contained within fluids that flows in the pipelines for transportation of bulk solids. Bulk solids can be transported for long distances effectively in pipelines. Raw materials can be stored in spherical containers (commonly known as capsules) transported through the pipeline. For economical and efficient design of any transportation mode, both the local flow characteristics and the global performance parameters need to be investigated. Published literature is severely limited in establishing the effects of local flow features on system characteristics of Hydraulic Capsule Pipelines (HCPs). The present study focuses on using a well validated Computational Fluid Dynamics (CFD) based solver to numerically simulate capsule flow in HCPs for both onshore and offshore applications, including pipe bends. A novel numerical model has been employed in the present study with the aid of the dynamic mesh technique for calculating the pressure and the velocity variations within HCPs with respect to time. The numerical model for capsule flow yields realistic results for the global flow parameters as compared to the experimental data from the test rig developed for capsule flow in the present study. In order to develop knowledge base covering a wide range of HCPs operating conditions, both horizontal and vertical pipelines including bends have been considered for numerical analysis. The numerical analysis is supported by experimental investigations. After carrying out detailed numerical analysis at component-level, a system-level optimisation study has been carried out in order to optimally design HCPs based on Least-Cost Principle.

The main objective of this research was to examine the effects that relative density and stratification have on greenfield soil displacements above tunnels in sandy ground. Data from a series of plane-strain centrifuge tests on tunnels in silica sand are presented. The relative density of the sand samples ranged from 90% to 50% in the tests. The soil displacement data were examined to determine features of greenfield settlement, both surface and subsurface. The effects that relative density and stratification have on the settlement trough shape is demonstrated and discussed. Some interesting features of tunnelling in sandy ground are revealed in the analysis.

The sustainability issues in pavement materials and design form a strong incentive for the present work. Using recycled materials in pavements is a sustainable practice that is gaining adoption, particularly for flexible (bituminous) pavements. One approach is to incorporate large quantities of Reclaimed Asphalt Pavement (RAP) into base and sub-base applications for pavement construction. Numerous studies have reported that RAP can be reused as an aggregate in Hot Mix Asphalt (HMA) as well as in cold mix asphalt, granular base, sub-base, and subgrade courses. Cold recycling technology, like hot mix technology, has also become popular in various countries for rehabilitation of damaged bituminous pavements. RAP stabilized with bitumen emulsion and foamed bitumen has been used as a base layer. The present study focuses on Foamed Bitumen treated Mixes (FBMs). Most of the agencies which use FBMs have their own mix design procedures which are the result of numerous efforts over decades. In spite of all these efforts, Foamed Bitumen application in cold recycling in the United Kingdom suffers from the lack of a standardised mix design procedure. To overcome this, the present research objective was to develop a mix design procedure by identifying critical mix design parameters. The mix design parameters that were optimised were Foamed Bitumen content, mixing water content (MWC), and compaction effort. Special attention was given to the simplest yet crucial mix design consideration of FBMs; curing. The thesis also attempted to simulate what should be expected in terms of the performance of flexible pavements containing FBMs as road base. The mix design parametric study was initially carried out on FBMs with virgin limestone aggregate (VA) without RAP material and a mix design procedure was proposed. Optimum MWC was achieved by optimising mechanical properties such as Indirect Tensile Stiffness Modulus (ITSM) and Indirect Tensile Strength (ITS-dry and ITS-wet). A rational range of 75-85% of Optimum Water Content (OWC) obtained by the modified Proctor test was found to be the optimum range of MWC that gives optimum mechanical properties for FBMs. The proposed methodology was also found to apply to FBMs with 50% RAP and 75% RAP. It was also found that the presence of RAP influenced the design FB content, which means that treating RAP as black rock in FBM mix design is not appropriate. This work also evaluated the validity of the total fluid (water + bitumen) concept which is widely used in bitumen-emulsion treated mixes. The present work was also intended to better understand the curing mechanism of FBMs and to lessen the gap between laboratory curing and field evolution of these mixtures. This was achieved by evaluating different curing regimes that are being followed by different agencies and researchers, as well as identifying important parameters that affect curing. In achieving this, a link was established between laboratory mix design and field performance by evaluating applicability of the maturity method. The curing regime study provided a valid investigation into the behaviour of FBM taking into account the effect of temperature, curing conditioning (Sealed or Unsealed), curing duration and the influence of cement with different curing regimes. It was found that the temperature is as important a parameter as time, as temperature has a greater influence on curing rate and also on bitumen properties. Moreover, higher curing temperatures resulted in higher rate of stiffness gain. This trend is not only because of rapid water loss but also implies an increase in binder stiffness at higher curing temperatures. Though the presence of RAP improved the early stage stiffness of FBMs, it slowed down the rate of water loss from the specimens which resulted in smaller stiffness values at a later stage. The experimental results also indicated that cement addition has no influence on water loss trends, but improved the stiffness significantly during all stages of curing. The study also evaluated the applicability of the maturity method as a tool to assess the in-situ characteristic of FBM layers in the pavement. It was found that replacing the time term with an equivalent age term in the maturity function aided in estimating stiffness rather than relative stiffness. This was possible because of the characteristic curing of FBM in which the limiting stiffness these mixtures reach strongly depends on the curing temperature at least for the length of the curing stages considered in the present study. A strong correlation was found between maturity and the stiffness values obtained from the laboratory tests which resulted in development of maturity-stiffness relationships. The application of the method to assess the in-situ stiffness was presented using three hypothetical pavement sections. The results showed the influence of ambient temperature and the importance of cement addition to FBMs. The permanent deformation resistance was assessed by performing RLAT tests on cylindrical specimens compacted by gyratory compactor. The RLAT test results indicate that both test temperature and stress level have significant influence on permanent deformation characteristics as expected. The effect of stress on permanent deformation was increased with increase in test temperature. It was also found that from limited tests and mixture combinations, RAP content has only a slight influence on permanent deformation of FBMs. However, the presence of cement led to significant improvement. FBMs were also found to be less temperature susceptible than HMA in terms of permanent deformation and, within FBMs, mixtures with cement were found to be more sensitive than FBMs without any cement. For assessing the fatigue performance of FBMs, the ITFT was initially used to investigate the effect of cement on the fatigue life. The ITFT tests results showed that the FBMs without cement (50%RAP-FBM) have lower fatigue life than HMA (DBM90) at any initial strain level. Nevertheless, similar to permanent deformation, the fatigue life was improved with the addition of 1% cement to FBMs. However, the above discussion was not found to be completely valid when uniaxial tests were carried out. In stress controlled uniaxial tests, a sinusoidal load of 1Hz frequency was applied axially to induce tensile strain in the radial direction. The failure criterion considered in the study was the number of cycles to reach 50% stiffness and this was plotted against the measured initial strain values. Results indicated that there was not much difference in fatigue life among different mixtures and also between FBM and HMA. However, stiffness evolution curves showed that FBMs fail in a different pattern compared to HMA. Unlike HMA, which showed a three stage evolution process, for FBMs the stiffness actually increased initially to reach a maximum and decreased at a slower rate until failure. It was also found that by plotting curves according to Hopman et al.,(1989) which identifies the fatigue failure transition point, use of the 50% stiffness criterion for fatigue life evaluation is not a conservative approach. Uniaxial tests also revealed that, although in fatigue the FBMs were found to behave differently from HMA, in terms of permanent deformation, FBMs behave similarly to HMA in that a steady state strain rate was achieved.

In construction buildings, use of thermal insulating materials is essential and beneficial not only by reducing the cooling/heating cost and the structural element sizes but also reducing the pollution of the environment which results from heavy use of fuel. Foamed concrete is a lightweight material. In this research, by using the preformed foam method, foamed concrete mixes with/without lightweight aggregate (LWA), which are suitable for semi-structural or structural purposes with good insulation and durability properties, were designed and produced. Then, their behaviour and the effect of microstructure on their macro properties were established. As a result, the mechanical, thermal and permeation performance as well as damage behaviour of foamed concrete, associated with changes in its microstructure that result from inclusion of superplasticizer, additives (silica fume and fly ash) and LWA, were investigated. The results showed that, for a given density, although the additives in combination led to increased void numbers, both void size and connectivity were reduced by preventing their merging and this resulted in a narrow void size distribution. As a result, the mineral admixtures (silica fume and fly ash) and superplasticizer combination provides improvement in the strength properties of foamed concrete. In addition, due to their making the cement paste denser and less porous, addition of additives and superplasticizer in combination led to slightly increased thermal conductivity in the dry state. However, owing to reduced water absorption, the thermal conductivity in the saturated state was slightly lower for mixes with additives than conventional mixes. Adding additives (individually or in combination) helped in reducing the water absorption, sorptivity and permeability of foamed concrete. However, inclusion of LWA resulted in increased sorptivity and permeability compared to the same density mixes, conventional or with additives in combination. From elasticity, fracture and fractal points of view, it was found that brittleness increases with additives while it reduces with inclusion of LWA. However, at a micro level, less damage occurred in mixes with LWA and the bond microcracks percentage increased with inclusion of additives. Finally, although the findings of this study are encouraging for the potential of using modified foamed concrete with additives in semi-structural and structural applications, it was recommended that using it in reinforced structural elements such as beams, columns, slabs and reinforced walls or load bearing masonry walls needs to be experimentally examined and evaluated.

Asphalt mixture, the most common road construction material, comprises bitumen, filler, fine and coarse aggregates, and air voids. Traditionally and for simplification, the mixture is treated as a continuous and homogenous material confined in the domain of linear behaviour. The demand for more durable roads, particularly with the progressive growth in traffic volumes and loads, has raised the requirement for improved design methods. Wisely, before the complex adoption of the nonlinear behaviour, understanding the nature of the internal stress-strain relationships at different scales and determining their linearity limits is essentially required taking into consideration the time and temperature dependency. So far, most experimental programs have been concerned with testing either asphalt mixture or bitumen in isolation. This thesis is intended to establish a systematic experimental investigation from binder to the asphalt mixture scale in terms of permanent deformation behaviour. Preliminary conclusions of the components contributions, their interactions, and the effect on the total macroscopic response are drawn from the experimental observations. Investigation of the fillers influence on the viscoelastic property of the mastic (filler +bitumen) binder in the dynamic shear rheometer (DSR), results exhibited that binder behave nonlinearly at high shear stress levels and the linearity range reduces with increasing filler content and/or raising the temperature. Although filler inclusion increased the deformation resistance (stiffness) of the binder, its recoverability decreased. Consequently, a new binder rutting evaluation test was designed to distinguish between the two rutting resistance mechanisms; stiffness and recovery. Results from the new test indicated that the linearity of the modified binders begins after an initial inherent nonlinearity stage and before a secondary nonlinearity stage triggered by the applied state of stresses in the DSR. A new designed mortar type was developed from the mastic and originated from a standard asphalt mixture. The focus of this part in the research emphasised on measuring the stiffening effect of fine aggregates utilising a constitutive stress-strain relationship and determining the influence on the viscoelastic behaviour. Results indicated that the stiffening effect varies depending on the stress condition (uniaxial, triaxial, or shear), temperature, fine aggregate gradation, and binder with filler content. The stress linearity limit was also found to vary at different degrees with the previous parameters. Uniaxial compression constant stress and strain rate tests were conducted on asphalt mixtures of different aggregate gradations at 30 and 500C. X-ray CT was incorporated to characterise the coarse aggregates and air voids through advanced image analysis techniques. The test was shown to be insensitive to the asphalt mixture type in terms of air voids uniformity. Mixtures of coarse aggregates produced larger size and smaller number of air voids, opposite to the fine aggregate ones. Comparing the stiffening effect between fine and coarse aggregates, it was revealed that the air void content is a key factor. Finally, the radial strain as measured along the height followed the pattern of air void distribution in the specimen and exhibited both tensile and compressive forms.

The rolling element bearing is a key component of many machines. Accurate and timely diagnosis of its faults is critical for proactive predictive maintenance. The research described in this thesis focuses on the development of techniques for detecting and diagnosing incipient bearing faults. These techniques are based on improved dynamic models and enhanced signal processing algorithms. Various common fault detection techniques for rolling element bearings are reviewed in this work and a detailed experimental investigation is described for several selected methods. Envelope analysis is widely used to obtain the bearing defect harmonics from the spectrum of the envelope of a vibration signal. This enables the detection and diagnosis of faults, and has shown good results in identifying incipient faults occurring on the different parts of a bearing. However, a critical step in implementing envelope analysis is to determine the frequency band that contains the signal component corresponding to the bearing fault (the one with highest signal to noise ratio). The choice of filter band is conventionally made via manual inspection of the spectrum to identify the resonant frequency where the largest change has occurred. In this work, a spectral kurtosis (SK) method is enhanced to enable determination of the optimum envelope analysis parameters, including the filter band and centre frequency, through a short time Fourier transform (STFT). The results show that the maximum amplitude of the kurtogram indicates the optimal parameters of band pass filter that allows both outer race and inner race faults to be determined from the optimised envelope spectrum. A performance evaluation is carried out on the kurtogram and the fast kurtogram, based on a simulated impact signal masked by different noise levels. This shows that as the signal to noise ratio (SNR) reaches as low as -5dB the STFT-based kurtogram is more effective at identifying periodic components due to bearing faults, and is less influenced by irregular noise pulses than the wavelet based fast kurtogram. A study of the accuracy of rolling-bearing diagnostic features in detecting bearing wear processes and monitoring fault sizes is presented for a range of radial clearances. Subsequently, a nonlinear dynamic model of a deep groove ball bearing with five degrees of freedom is developed. The model incorporates local defects and clearance increments in order to gain the insight into the bearing dynamics. Simulation results indicate that the vibrations at fault characteristic frequencies exhibit significant variability for increasing clearances. An increased vibration level is detected at the bearing characteristic frequency for an outer race fault, whereas a decreased vibration level is found for an inner race fault. Outcomes of laboratory experiments on several bearing clearance grades, with different local defects, are used herein for model validation purposes. The experimental validation indicates that the envelope spectrum is not accurate enough to quantify the rolling element bearing fault severity adequately. To improve the results, a new method has been developed by combining a conventional bispectrum (CB) and modulation signal bispectrum (MSB) with envelope analysis. This suppresses the inevitable noise in the envelope signal, and hence provides more accurate diagnostic features. Both the simulation and the experimental results show that MSB extracts small changes from a faulty bearing more reliably, enabling more accurate and reliable fault severity diagnosis. Moreover, the vibration amplitudes at the fault characteristic frequencies exhibit significant changes with increasing clearance. However, the vibration amplitude tends to increase with the severity of an outer race fault and decrease with the severity of an inner race fault. It is therefore necessary to take these effects into account when diagnosing the size of a defect.

This present thesis proposes a novel approach for coupling finite element and boundary element formulations using a Loop subdivision surface discretisation to allow efficient acoustic scattering analysis over shell structures. The analysis of underwater structures has always been a challenge for engineers because it couples shell structural dynamics and acoustic scattering. In the present work, a finite element implementation of the Kirchhoff-Love formulation is used for shell structural dynamic analysis and the boundary element method is adopted to solve the Helmholtz equation for acoustic scattering analysis. The boundary element formulation is chosen as it can handle infinite domains without volumetric meshes. In the conventional engineering workflow, generating meshes of complex geometries to represent the underwater structures, e.g. submarines or torpedoes, is very time consuming and costly even if it is only a data conversion process. Isogeometric analysis (IGA) is a recently developed concept which aims to integrate computer aided design (CAD) and numerical analysis by using the same geometry model. Non-uniform rational B-splines~(NURBS), the most commonly used CAD technique, were considered in early IGA developments. However, NURBS have limitations when used in analysis because of their tensor-product nature. Subdivision surfaces discretisation is an alternative to overcome NURBS limitation. The new method adopts a triangular Loop subdivision surface discretisation for both geometry and analysis. The high order subdivision basis functions have $C^1$ continuity, which satisfies the requirements of the Kirchhoff-Love formulation and are highly efficient for the acoustic field computations. The control meshes for the shell analysis and the acoustic analysis have the same resolution, which provides a fully integrated isogeometric approach for coupled structural-acoustic analysis of shells. The method is verified by the example of an acoustic plane wave which scatters over an elastic spherical shell. The ability of the presented method to handle complex geometries is also demonstrated.

Functional surfaces interact with surrounding substances, such as another solid, a liquid, gas, acoustic or electromagnetic waves etc., in order to achieve a required effect. Surfaces are increasingly required with complex forms and ever-increasing precision, can be very challenging to make. In particular, mid-spatial frequency (MSF) ripples are difficult to avoid for various reasons, but especially the changing misfit between a polishing tool as it moves across a complex workpiece surface. Current surface processing techniques are limited in their ability effectively to control or remove MSF errors for the reasons: i) lack of the ability to conform to the complex working surfaces, including grinding and lapping; ii) low material removal rate, such as Magnetorheological finishing and fluid jet polishing; iii) high cost (typically for ion beam figuring); iv) constrains for the size of the workpiece, such as stressed lap polishing and stressed mirror polishing. This thesis reports on the development of enhanced techniques, both to understand the formation of MSF errors on aspherical surfaces, and to mitigate them, increasing overall production efficiency. This has been achieved by: 1) Development of a novel stressed mirror technique providing a universal platform for aspheric experiments. 2) Results and analysis of kinetic simulations to understand the working mechanism of the non-Newtonian material under different stress conditions. 3) Developing a non-Newtonian tool, used in a novel way, to manage misfit between an aspherical workpiece and the tool surface. Peak-to-valley MSF error on an off-axis aspheric part better than 10 nm has been achieved. 4) Using bonded diamond pads, with various diamond sizes in a ‘grolishing’ (hybrid between grinding and polishing) procedure to achieve extremely high material removal rates (up to 267 mm3 /min), and control MSF errors 10 nm peak-to-valley, on flat and spherical surfaces. 5) Providing an aspherical surface after grolishing by a 3-microns diamond pad, with texture of sufficiently quality to be measured directly by an interferometer, which usually be achieved only after polishing.

In this thesis, various features of the RoF supported mmW communication for future wireless systems have been analysed including photonic generation of mmW for MIMO operation, performance analysis of mmW MIMO to achieve spatial diversity and spatial multiplexing with analog RoF fronthaul, and multi-user transmission in the 60 GHz-band using multiplexing-over-fibre transport and frequency-selective antenna. A low cost mmW generation system for two independent MIMO signals has been presented, consisting of a single optical Phase Modulator (PM). The different aspects of experimental analysis on RoF-supported mmW MIMO in this thesis, which were not considered before, include use of specific MIMO algorithm to understand the amount of improvement in coverage and data rate for a particular MIMO technique, performance comparison with SISO at several user locations, and verification of optimum RAU physical spacing for a particular transmission distance with the theoretical results. The results show that flexible and wider RAU spacings, required to obtain optimum performance in a mmW MIMO system, can be achieved using the proposed analog RoF fronthaul. The investigation was extended to verification of a method to individual measurement of mmW channel coefficients and performing MIMO processing, which shows that mmW channels are relatively static and analysis can be extended to much longer distances and making projections for N×N MIMO. For mmW multi-user transmission, a novel low cost, low complexity system using single RoF link and single RF chain with single transmitting antenna has been presented and characterized, which was based on large number of RF chains and multiple antenna units previously. The setup involves generation and RoF transport of a composite SCM signal, upconversion at the RAU and transmission of different frequency channels towards spatially distributed users using a frequency-selective Leaky-Wave-Antenna (LWA), to convert Frequency Division Multiplexing (FDM) in to Spatial Division Multiple Access (SDMA). Analysis on low user-signal spacing for the SCM shows the feasibility to serve a large number of users within a specific transmission bandwidth and experimental demonstration to achieve sum rate of 10Gb/s is shown by serving 20 users simultaneously. Furthermore, investigation on SNR degradation of high bandwidth signals due to beamsteering effect of the LWA and theoretical calculations of the sum data rate for different number of users is performed, which shows that the proposed system can provide much higher sum rates with high available SNR. It was also experimentally demonstrated that improvement in coverage and spectral efficiency is obtained by operating multiple LWAs using single RF chain. Finally, an experimental demonstration of a DWDM-RoF based 60 GHz multi-user transmission using single LWA is presented to show the feasibility to extend the setup for a multiple RAU based system, serving each at distinct optical wavelength and performing direct photonic upconversion at the RAU for low cost mmW generation.