Recent diversification of the telecommunications industry has resulted in the adaptation of optical materials and their associated fabrication technologies for use in the bioanalytical sensor industry. Flame hydrolysis deposited (FHD) planar silica is one such material. Capable of producing high quality films for optical waveguides, the chemical inertness of the deposited silica makes it an ideal substrate from which to fabricate a biological fluorescence sensor. The aim of the work contained in this thesis was to utilise the FHD silica in optical - fluorescence sensors suitable for use at visible and in particular red wavelengths where several fluorophores can be excited, and background fluorescence from the silica is small. New technologies for producing waveguides have been evaluated in the context of their usefulness in optical sensors, with the intention of producing devices with as few fabrication steps as possible to reduce fabrication time and cost. The design, fabrication and testing of a number of sensor configurations is described, in which optical waveguides were interfaced with microfluidic chambers to provide excitation of a fiuorophore in solution. New waveguide fabrication technologies were used for the first time in sensor systems with integrated microfluidic circuits. Waveguides, written by electron beam densification were evaluated in terms of their performance in splitting an excitation signal into several different components, as would be appropriate for excitation of multiple microfluidic chambers - an 'array sensor'. Both Y-branch waveguides and multimode interference (MMI) splitters were successfully used to split the excitation signal. In addition to electron beam densification, UV irradiation at a wavelength of 157 nm was used to write waveguides in FHD silica. The application of a metal surface mask to define the waveguide structures is described. To allow sensitive detection and identification of fluorophores from FHD silica sensor chips, a single chamber device was successfully interfaced to a system to make time resolved fluorescence measurements, a technique known as time correlated single photon counting (TCSPC). The use of TCSPC allowed measurement of the decay time of the fluorescent dye, by which different fluorescent molecules could be identified, as well as the possibility of low concentration measurements. The research has allowed new technologies for creating waveguides in FHD silica to be adapted for sensing purposes, leading to a platform for creating devices in a number of different configurations.

Smart grid has been advocated in both developing and developed countries in many years to deal with large amount of energy deficit and air pollutions. However, many literatures talked about some specific technologies and implementations, few of them could give a clear picture on the smart grid implementations in a macro scale like what is the main consideration for the smart grid implementations, how to examine the power system operation with communication network deployment, how to determine the optimal technology scheme with consideration of economic and political constraints, and so on. Governments and related institutions are keen to evaluate the cost and benefit of new technologies or mechanisms in a scientific way rather than making decision blindly. Decision Support System, which is an information system based on interactive computers to support decision making in planning, management, operations for evaluating technologies, is an essential tool to provide decision makers with powerful scientific evidence. The objective of the thesis is to identify the data and information processing technologies and mechanisms which will enable the further development of decision support systems that can be used to evaluate the indices for smart grid technology investment in the future. First of all, the thesis introduces the smart grid and its features and technologies in order to clarify the benefits can be obtained from smart grid deployment in many aspects such as economics, environment, reliability, efficiency, security and safety. Besides, it is necessary to understand power system business and operation scenarios which may affect the communication network model. This thesis, for the first time, will give detailed requirements for smart grid simulation according to the power system business and operation. In addition, state of art monitoring system and communication system involved in smart grid for better demand side management will be reviewed in order to find out their impacts reflecting to the power systems. The methods and algorithms applied to the smart grid monitoring, communication technologies for smart grid are summarized and the monitoring systems are compared with each other to see the merits and drawbacks in each type of the monitoring system. In smart grid environment, large number of data are need to be processed and useful information are required to be abstracted for further operation in power systems. Machine learning is a useful tool for data mining and prediction. One of the typical machine learning artificial algorithms, artificial neural network (ANN) for load forecasting in large power system is proposed in this thesis and different learning methods of back-propagation, Quasi-Newton and Levenberg-Marquardt, are compared with each other to seek the best result in load forecasting. Bad load forecasting may leads to demand and generation mismatch, which could cause blackout in power systems. Load shedding schemes are powerful defender for power system from collapsing and keep the grid in integral to a maximum extent. A lesson learned from India blackout in July 2012 is analyzed and recommendations on preventing grid from blackout are given in this work. Also, a new load shedding schemes for an isolated system is proposed in this thesis to take full advantage from information sharing and communication network deployment in smart grid. Lastly, the new trend of decision support system (DSS) for smart grid implementation is summarized and reliability index and stability scenarios for cost benefit analysis are under DSS consideration. Many countries and organizations are setting renewable penetration goals when planning the contribution to reduce the greenhouse gas emission in the future 10 or 20 years. For instance, UK government is expecting to produce 27% of renewable energies EU-wide before 2030. Some simulations have been carried out to demonstrate the physical insight of a power system operation with renewable energy integration and to study the non-dispatchable energy source penetration level. Meanwhile, issues from power system reliability which may affect consumers are required to take into account. Reliability index of Centralized wind generations and that of distributed wind generations are compared with each other under an investment perspective.

Thermoelectric generators (TEGs) convert the thermal energy flowing through them into DC electrical energy in a quantity dependant on the temperature difference across them and the electrical load applied, with a conversion efficiency of typically 5%. Nonetheless, they can be successfully employed to recover energy from waste heat and their use has increased rapidly in recent years, with applications ranging from microwatts to kilowatts, due to energy policy legislations and increasing energy cost determined by climate change, environmental issues and availability of energy sources. The performance of TEGs, subject to thermal and electrical effects, can vary considerably depending on the operating conditions, therefore it is necessary to measure and characterise their performance, and to understand their dynamic behaviour and interaction with the other parts of the system. Based on this knowledge it is then desired to develop an effective electronic system able to control these devices so as to maximise the power generated and increase the overall efficiency of the system. Several TEGs can be electrically connected in series and/or parallel (forming an array) to provide the required voltage and/or current. However, TEGs are usually employed in environments with time-varying temperatures, thermal powers and electrical loads. As a consequence in most TEG systems the individual thermoelectric devices can be subject to temperature mismatch due to operating conditions. Therefore it is of relevant importance to accurately simulate the evolution of thermoelectric systems during thermal and electrical transients. At the same time accurate experimental performance data are necessary to permit precise simulations. Unfortunately, there is still no standardised method to test the electrical and thermal performance of TEGs. This thesis tackles these key challenges and contributes to the pool of existing knowledge about TEGs dealing with four main topics: testing of thermoelectric generators, simulation of thermoelectric generating systems, design and production of power electronic converters for thermoelectric generators, and physical applications of thermoelectric generators. After an introduction to the physical phenomena underlying the operation of TEGs, this thesis describes the innovative test system built at the University of Glasgow to assess the performance of TEG devices in the ”real-world”. The fixture allows a single TEG device to be tested with thermal input power up to 1 kW and hot temperature up to 800◦C with minimal thermal losses and thermal shock; the mechanical clamping force can be adjusted up to 5 kN, and the temperatures are sensed by thermocouples placed directly on the TEGs surfaces. A computer program controls all the instruments in order to minimise errors and to aid accurate measurement and test repeatability. The test rig can measure four TEGs simultaneously, each one individually controlled and heated. This allows testing the performance of TEG arrays under mismatched conditions, e.g., dimensions, clamping force, temperature, etc. Under these circumstances experimental results and a mathematical analysis show that when in operation each TEG in the array will have a different electrical operating point at which maximum energy can be extracted and problems of decreased power output arise. This thesis provides the transient solution to the one-dimensional heat conduction equation with internal heat generation that describes the transfer and generation of heat throughout a thermoelectric device with dynamic exchange of heat through the hot and cold sides. This solution is then included in a model in which the Peltier effect, the thermal masses and the electrical behaviour of the system are also considered. The resulting model is created in Simulink and the comparison with experimental results from a TEG system confirms the accuracy of the simulation tool to predict the evolution of the thermoelectric system both in steady-state and during thermal or electrical transients. This thesis presents an investigation of the optimum electrical operating load to maximise the power produced by a TEG. Both fixed temperature difference and fixed thermal input power conditions are considered. Power electronic converters controlled by a Maximum Power Point Tracking (MPPT) algorithm are used to maximise the power transfer from the TEG to the load. The MPPT method based on the open-circuit voltage is arguably the most suitable for the almost linear electrical characteristic of TEGs. An innovative way to perform the open-circuit voltage measurement during the pseudo-normal operation of the power converter is presented. This MPPT technique is supported by theoretical analysis and used to control an efficient synchronous Buck-Boost converter capable of interfacing TEGs over a wide range of temperatures. The prototype MPPT converter is controlled by an inexpensive microcontroller, and a lead-acid battery is used to accumulate the harvested energy. Experimental results using commercial TEG devices demonstrate the ability of the MPPT converter to accurately track the maximum power point during steady-state and thermal transients. This thesis also presents two practical applications of TEGs. The first application exploits the thermal energy generated by a stove to concurrently produce electrical energy and heat water, while the second application recovers the heat energy rejected to ambient by a car’s exhaust gas system to generate electrical energy for battery charging.

This work has as main objective the integration of planar Gunn diodes and high electron mobility transistors (HEMTs) on the same chip for the realisation of high-power oscillators in the millimeter-wave regime. By integrating the two devices, we can reinforce the high frequency oscillations generated by the diode using a transistor-based amplifier. The integration of the planar Gunn diode and the pseudomorphic HEMT was initially attempted on a combined gallium arsenide (GaAs) wafer. In this approach, the active layers of the two devices were separated by a thick buffer layer. A second technique was examined afterwards where both devices were fabricated on the same wafer that included AlGaAs/InGaAs/GaAs heterostructures optimised for the fabrication of pHEMTs. The second approach demonstrated the successful implementation of both devices on the same substrate. Planar Gunn diodes with 1.3 μm anode-to-cathode separation (Lac) presented oscillations up to 87.6 GHz with a maximum power equal to -40 dBm. A new technique was developed for the fabrication of 70 nm long T-gates, improving the gain and the high frequency performance of the transistor. The pHEMT presented cut-off frequency (fT) equal to 90 GHz and 200 GHz maximum frequency of oscillation (fmax). The same side-by-side approach was applied afterwards for the implementation of both devices on an indium phosphide (InP) HEMT wafer for the first time. Planar Gunn diodes with Lac equal to 1 μm generated oscillations up to 204 GHz with -7.1 dBm maximum power. The developed 70 nm T-gate technology was applied for the fabrication of HEMTs with fT equal to 220 GHz and fmax equal to 330 GHz. In the end of this work, the two devices were combined in the same monolithic microwave integrated circuit (MMIC), where the diode was connected to the transistor based amplifier. The amplifier demonstrated a very promising performance with 10 dB of stable gain at 43 GHz. However, imperfections of the material caused large variations at the current density of the devices. As a consequence, no signals were detected at the output of the complete MMIC oscillators.

The core of this thesis is a thorough investigation of the scaling properties of conventional nano-CMOS MOSFETs, their physical and operational limitations and intrinsic parameter fluctuations. To support this investigation a well calibrated 35 nm physical gate length real MOSFET fabricated by Toshiba was used as a reference transistor. Prior to the start of scaling to shorter channel lengths, the simulators were calibrated against the experimentally measured characteristics of the reference device. Comprehensive numerical simulators were then used for designing the next five generations of transistors that correspond to the technology nodes of the latest International Technology Roadmap for Semiconductors (lTRS). The scaling of field effect transistors is one of the most widely studied concepts in semiconductor technology. The emphases of such studies have varied over the years, being dictated by the dominant issues faced by the microelectronics industry. The research presented in this thesis is focused on the present state of the scaling of conventional MOSFETs and its projections during the next 15 years. The electrical properties of conventional MOSFETs; threshold voltage (VT), subthreshold slope (S) and on-off currents (lon, Ioffi ), which are scaled to channel lengths of 35, 25, 18, 13, and 9 nm have been investigated. In addition, the channel doping profile and the corresponding carrier mobility in each generation of transistors have also been studied and compared. The concern of limited solid solubility of dopants in silicon is also addressed along with the problem of high channel doping concentrations in scaled devices. The other important issue associated with the scaling of conventional MOSFETs are the intrinsic parameter fluctuations (IPF) due to discrete random dopants in the inversion layer and the effects of gate Line Edge Roughness (LER). The variations of the three important MOSFET parameters (loff, VT and Ion), induced by random discrete dopants and LER have been comprehensively studied in the thesis. Finally, one of the promising emerging CMOS transistor architectures, the Ultra Thin Body (UTB) SOl MOSFET, which is expected to replace the conventional MOSFET, has been investigated from the scaling point of view.

The project is concerned with the development of methods for the fabrication of magnetic sensor devices on Atomic Force Microscopy (AFM) probes and their characterization. The devices use the principle of the Hall effect (based on the Lorentz force) to sense the magnetic properties of a magnetized specimen. In the past Hall bar sensors have been fabricated using semimetals such as Bismuth, or using 2-d electron gas material based on heterojunctions in III-V material. The former probes are limited by low sensitivity. The latter are limited by the difficulty encountered when trying to integrate the device with a force-sensing cantilever. The highest spatial resolution reported for a Hall bar operating at room temperature is 50 nm. Due to quantum effects (long mean free path), scaling down devices based on high mobility material results in a drop in sensitivity. For magnetic material studies of current interest higher resolutions are required. To achieve this goal in a material system which is compatible with micromachining the proposed approach utilises silicon as the sensing material. Silicon Hall bars have already been reported to work for large scale devices. This thesis presents the development of p-type enhancement mode MOSFET transistor fabrication process on a tip of Atomic Force Microscope (AFM) probe. The active device fabrication process was developed in order to allow fabrication of a magnetic sensor for Scanning Hall Probe Microscope (SHPM). The Hall bar was constructed on the apex of the AFM tip of attractive mode probes. The fabrication is performed in batches by using common semiconductor techniques leading to micromachining of the Si substrate, formation of the active device and cantilever release step. The transistor characteristics are presented, compared with expected performance of the modelled device and the reasons for differences are discussed. In this work, a method for application of spin-on-dopant on highly topographic structures is developed. Other encountered process incompatibilities are dealt with to finally present a full process for p-type enhancement mode MOSFET transistor on AFM tip fabrication.

In order to meet greenhouse gas emissions targets, the Great Britain (GB) future electricity supply will include a higher fraction of non-dispatchable generation, increasing opportunities for demand side management (DSM) to maintain a supply/demand balance. Domestic electricity demand is approximately a third of total GB demand and has the potential to provide a significant demand side resource. An optimization model of UK electricity generation has been developed with an objective function to minimize total system cost (£m/year). The models show that dispatchable output falls from 77% of total output in 2012 to 69% in 2020, 41% in 2030 and 28% in 2050, supporting the need for increased levels of future DSM. Domestic demand has been categorised to identify flexible loads (electric space and water heating, cold appliances and wet appliances), and projected to 2030. Annual flexible demand in 2030 amounts to 64.3TWh though the amount of practically available demand varies significantly on a diurnal, weekly and seasonal basis. Daily load profiles show practically available demand on two sample days at three sample time points (05:00, 08:00 and 17:30) varies between 838MW and 6,150MW. Access to flexible demand for DSM purposes is dependent on the active involvement of domestic consumers and/or their acceptance of appliance automation. Analysis of a major quantitative survey and qualitative workshop dataset shows that 49% of respondents don’t think very much or not at all about their electricity use. This has implications for the effectiveness of DSM measures which rely on consumers to actively modify behaviour in response to a signal. Whilst appliance automation can be a practical solution to realising demand side potential, many consumers are reluctant to allow remote access. Consumers are motivated by financial incentives though the low value of individual appliance consumption limits the effectiveness of solely financial incentives. A range of incentives would be required to encourage a wide cross-section of consumers to engage with their electricity consumption.

The main aim of this project is to investigate the influence of the inter-laminar short circuit faults on the performance of magnetic cores and develop a non-destructive method to detect these kinds of defects. The eddy current path in magnetic laminations which is magnetised by time varying magnetic field was modelled by an equivalent resistor network to calculate and predict the eddy current power losses in magnetic laminations. The model was validated over a wide range of magnetisation conditions. Based on the developed model, the influence of a wide range of magnetising frequency and peak flux density on the magnetic properties of electrical steels was studied. An experimental-analytical technique was developed to separate magnetic loss components over a wide range of magnetisation. Two electrical steel laminations, Conventional Grain Oriented (CGO) and Non-Oriented (NO), were used in the experimental work of the relevant studies. 2-D FE based modelling was performed to simulate inter-laminar faults on stacks of laminations and visualise the distribution of eddy currents in the faulted laminations. The influence of inter-laminar faults on the eddy current power loss was experimentally investigated by introducing artificial short circuits of different configurations on stacks of Epstein size laminations of GO steel. A non-destructive test method was developed to detect inter-laminar fault between the laminations of the magnetic cores by means of Flux Injection Probe (FIP). A prototype model of a FIP was developed and its application to quality assessment of transformer core laminations was investigated. The research presented here can be utilised by electrical steel manufacturers and electrical machine designers to survey the effect of inter-laminar faults on the magnetic properties of magnetic cores and their quality assessment, to reduce the risk of core damage or machine failure caused by the inter-laminar faults.

Solar energy has been extensively used in the renewable technology field, especially for domestic applications, either for heating, electrical generation or for a combination of heat and power (CHP) in one system. For CHP system solar photoelectric/thermal (PV/T) is the most commonly used technology for roof top applications. However, combination between solar hot water and thermoelectric generators has become an attractive for CHP system, this is due to its simplicity of construction and its high reliability. Moreover, this technology does not rely simply on sunlight and it can work with any other heat source, such as waste heat. However, its main drawback is its low efficiency. Recent publications by Kraemer et al (2011) and Arturo (2013) have shown that the efficiency of solar thermoelectric systems has improved dramatically, especially when combined with a solar concentrator system, as well as within a vacuum environment. The project recorded in this thesis focused on the design, construction and investigation of an experimental solar thermoelectric system based on a flat plate solar absorber. The aim was to study the technical feasibility and economical viability of generating heat and electric power using a solar thermoelectric hot water system. The design procedure involved on determining the heat absorbed and emitted, as well as the electrical power that was generated by the system. It began by obtaining the efficiency of the solar absorber, including selecting its paint, this was done through an experimental technique to determine the heat absorbed by the absorber, and the results obtained were verified by direct measurements of the light intensity. xvi An intensity meter was used, and results from both the experimental and theoretical models showed good agreement. The process also included calculating the heat from the system that was gained, lost and generated, as well as the electrical power provided. This was done to provide the system optimal size optimization to obtain the best and most economical system. Further improvement was made to the system by assembling a vacuum cavity, to improve the system’s efficiency. Although the maximum electrical efficiency obtained was relatively low (0.9%), compared to results recorded in the literature (Kraemer et al ,2011 and Arturo, 2013). However, the results of the electrical power output, under a vacuum level of 5 x 10-2mbar, increased approximately three times compared to the results obtained under normal (atmospheric) conditions. Additionally, the thermal power increased by 37% at this level of vacuum. The process involved determining the best thermoelectric geometries to achieve the optimum power outcome under different environmental conditions. The results showed that the system, which included the Thermoelectric device (TEG) with a larger geometric size, produced the best thermal power among other sizes. It was concluded that the system with the smallest TEG geometric size provided the best electrical power output.

This thesis, addresses some aspects of the well-known, problem, experienced by designer of radio frequency power amplifiers (RFPA): the efficiency/linearity trade-off. The thesis is focused on finding and documenting solution to linearity problem than can be used to advance the performance of radio frequency (RF) and microwave systems used by the wireless communication industry. The research work, this was undertaken by performing a detailed investigation of the behaviour of transistors, under complex modulation, when subjected to time varying baseband signals at their output terminal: This is what in this thesis will be referred to as “baseband injection”. To undertake this study a new approach to the characterisation of non-linear devices (NLD) in the radio frequency (RF) region, such as transistors, designated as device-under-test (DUT), subjected to time varying baseband signals at its output terminal, was implemented. The study was focused on transistors that are used in implementing RF power amplifiers (RFPA) for base station applications. The nonlinear device under test (NL-DUT) is a generalisation to include transistors and other nonlinear devices under test. Throughout this thesis, transistors will be referred to as ‘device’ or ‘radio frequency power amplifier (RFPA) device’. During baseband injection investigations the device is perturbed by multi-tone modulated RF signals of different complexities. The wireless communication industry is very familiar with these kinds of devices and signals. Also familiar to the industry are the effects that arise when these kind of signal perturb these devices, such as inter-modulation distortion and linearity, power consumption/dissipation and efficiency, spectral re-growth and spectral efficiency, memory effects and trapping effects. While the concept of using baseband injection to linearize RFPAs is not new the mathematical framework introduced and applied in this work is novel. This novel approach NOVEL POWER AMPLIFIER DESIGN USING NON-LINEAR MICROWAVE CHARACTERISATION AND MEASUREMENT TECHNIQUES CARDIFF UNIVERISTY - UK ABSTRACT vi has provided new insight to this very complex problem and highlighted solutions to how it could be a usable technique in practical amplifiers. In this thesis a very rigorous and complex investigative mathematical and measurement analysis on RFPA response to applied complex stimulus in a special domain called the envelope domain was conducted. A novel generic formulation that can ‘engineer’ signal waveforms by using special control keys with which to provide solution to some of the problems highlighted above is presented. The formulation is based on specific background principles, identified from the result of both mathematical theoretical analysis and detailed experimental device characterisation.