Demand response (DR) is able to contribute to the secure and efficient operation of power systems. The implications of adopting the residential DR through smart appliances (SAs) were investigated from the perspective of three actors: customer, distribution network operator, and transmission system operator. The types of SAs considered in the investigation are: washing machines, dish washers and tumble dryers. A mathematical model was developed to describe the operation of SAs including load management features: start delay and cycle interruption. The optimal scheduling of SAs considering user behaviour and multiple-rates electricity tariffs was investigated using the optimisation software CPLEX. Further, the financial benefits for SA users subscribing to multiple-rates electricity tariffs were investigated. The savings are mainly a result of the appliances’ load shifting feature and are sensitive to user settings. The savings averaged at 7% of the household annual electricity bill. For households in the United Kingdom, the SAs had a payback period of less than three years and a net present value of up to £206. Furthermore, the operation of distribution networks with different uptake rates of SAs was investigated. A simulation containing a load modelling method and a network model determines, through time series power flow analysis, the network branch loading and voltage profile. The thermal ratings and voltage limits were exceeded on the LV network due to deterioration in the temporal diversity of the appliance utilisation. A regional controller for SAs was developed which effectively limited the network peak demand and voltage drop. A framework was introduced which enabled transmission system operators to access demand response from SAs in a timeframe suitable for operating reserve. A multiple time-step simulation was developed that assessed the load reduction from a number of households as a response to a reserve instruction. The instruction was modelled as a price increase with a short notification period. It was estimated that up to half of the current operating reserve requirements of Great Britain’s power system can be obtained with 20% uptake of SAs.

Foreseen expansion and increasing complexity of power distribution networks will increase demand for accurate metering of electric energy flow. The current transformer (CT) is widely used in measurement systems and has direct effect on the overall accuracy of electric power measurement. Therefore, its design and performance are of great importance. A steady state model of a CT is proposed to relate its performance to basic magnetic properties of its core. It enables a CT amplitude and phase errors to be predicted from the magnetic permeability and power loss of its core. Therefore it can be easily implemented at the design stage of these devices. The accuracy of the model has been verified against experimental data and the predicted CT errors were found to be in a good agreement with measured values. A negligible leakage reactance design CT is considered in this work, but an additional parameter would have to be considered for gapped cores or non– uniformly distributed windings. CT errors are determined by magnetic properties of its core in a wide flux density range. Measurement of magnetic properties at very low flux densities can be extremely challenging due to low signal-to-noise ratio. An accurate, low flux density measurement system has been developed for the investigation of CTs. It features digital triggering, cycles and moving averaging techniques, innovative digital compensation, customised digital feedback algorithm and is capable of measuring magnetic properties of materials at flux densities as low as few µT. This setup can be used for testing variety of ferromagnetic materials for other low flux density applications such as magnetic shielding.

This thesis presents Computational Fluid Dynamics (CFD) simulations of renewable turbines akin to those used for wind, hydro, and tidal applications. The models developed took the form of actuator discs with the solution of incompressible Reynolds-Averaged Navier-Stokes equations with the k-ω SST turbulence models. Simulations were initially conducted of a single turbine in water and air and then two axially aligned turbines to study the flow field interactions. These models were compared with previous theoretical, experimental and numerical data evident in the literature. Generally, good agreement was found between these models and other analogous data sources in terms of velocity profiles in the far wake. The actuator disc method was underpinned using the transient actuator line method, which showed good agreement from a quantitative and qualitative viewpoint. However, it required significant additional computational time when compared to the actuator disc method. Each of the models were developed and solved using complimentary commercially available CFD codes, ANSYS-CFX and ANSYS-Fluent. For this type of study, a critical evaluation of these codes was in all probability performed for the first time, where it is shown that for the studies investigated in this thesis ANSYS-CFX performed better than ANSYS-Fluent with respect to the computational effort (i.e. time and lines of code).

The endurance of an aircraft can be increased in the presence of failures by utilising flight control systems that are tolerant to failures. Such systems are known as fault tolerant flight control systems (FTFCS). FTFCS can be implemented by developing failure detection, identification and accommodation (FDIA) schemes. Two of the major types of failures in an aircraft system are the sensor and actuator failures. In this research, a sensor failure detection, identification and accommodation (SFDIA); and an actuator failure detection, identification and accommodation (AFDIA) schemes are developed. These schemes are developed using the artificial neural network (ANN). A number of techniques can be found in the literature that address FDIA in aircraft systems. These techniques are, for example, Kalman filters, fuzzy logic and ANN. This research uses the fully connected cascade (FCC) neural network (NN) for the development of the SFDIA and AFDIA schemes. Based on the study presented in the literature, this NN architecture is compact and efficient in comparison to the multi-layer perceptron (MLP) NN, which is a popular choice for NN applications. This is the first reported instance of the use of the FCC NN for fault tolerance applications, especially in the aerospace domain. For this research, the X-Plane 9 flight simulator is used for data collection and as a test bed. This simulator is well known for its realistic simulations and is certified by the Federal Aviation Administration (FAA) for pilot training. The developed SFDIA scheme adds endurance to an aircraft in the presence of failures in the aircraft pitch, roll and yaw rate gyro sensors. The SFDIA scheme is able to replace a faulty gyro sensor with a FCC NN based estimate, with as few as 2 neurons. In total, 105 failure experiments were conducted, out of which only 1 went undetected. In the developed AFDIA scheme, a FCC NN based roll controller is employed, which uses just 5 neurons. This controller can adapt on-line to the post failure dynamics of the aircraft following a 66\% loss of wing surface. With 66\% of the wing surface missing, the NN based roll controller is able to maintain flight. This is a remarkable display of endurance by the AFDIA scheme, following such a severe failure. The results presented in this research validate the use of FCC NNs for SFDIA and AFDIA applications.

The increasing size and flexibility of large wind turbine blades introduces significant aeroelastic effects, which are caused by fluid-structure interaction. These effects might result in aeroelastic instability problems, such as edgewise instability and flutter, which can be devastating to the blades and the wind turbine. Therefore, developing a reliable and efficient aeroelastic model to investigate the aeroelasticity characterisation of large wind turbine blades is crucial in the development of large wind turbines. There are several aeroelastic models available today for wind turbine blades. Almost all of them are linear models based on assumption of small blade deflections, and do not take account of large deflection effects on modelling responses and loads. However, with the increasing size and flexibility of large wind turbine blades, this assumption is not valid anymore because the blades often experience large deflections, which introduce significant geometric nonlinearities. Additionally, existing cross-sectional analysis models, which are used to extract cross-sectional properties of wind turbine composite blades for aeroelastic modelling, are either time-consuming or inaccurate. This thesis aims to provide a reliable and efficient aeroelastic modelling of large wind turbine blades through developing 1) a cross-sectional model, which can extract cross-sectional properties of wind turbine composite blades in a reliable and efficient way; and 2) a nonlinear aeroelastic model, which is capable of handling large blade deflections. In this thesis, a cross-sectional analysis model for calculating the cross-sectional properties of composite blades has been developed by incorporating classical lamination theory (CLT) with extended Bredt-Batho shear flow theory (EBSFT). The model considers the shear web effects and warping effects of composite blades and thus greatly improves the accuracy of torsional stiffness calculation. It also avoids complicated post-processing of force-displacement data from computationally expensive 3D finite-element analysis (FEA) and thus considerably improves the computational efficiency. A MATLAB program was developed to verify the accuracy and efficiency of the cross-sectional analysis model, and a series of benchmark calculation tests were undertaken. The results show that good agreement is achieved comparing with the data from experiment and FEA, and improved accuracy of torsional stiffness calculation due to consideration of the shear web effects is observed comparing with an existing cross-sectional analysis code PreComp. Additionally, a nonlinear aeroelastic model for large wind turbine blades has been developed by combining 1) a blade structural model, which is based on a mixed-form formulation of geometrically exact beam theory (GEBT), taking account of geometric nonlinearities; and 2) a blade load model, which takes account of gravity loads, centrifugal loads and aerodynamic loads. The aerodynamic loads are calculated based on combining the blade element momentum (BEM) model and the Beddoes-Leishman (BL) dynamic stall model. The nonlinear aeroelastic model takes account of large blade deflections and thus greatly improves the accuracy of aeroelastic analysis of wind turbine blades. The nonlinear aeroelastic model was implemented in COMSOL Multiphysics, and a series of benchmark calculation tests were undertaken. The results show that good agreement is achieved when compared with experimental data, and its capability of handling large deflections is demonstrated. After the validation, the nonlinear aeroelastic model was applied to the aeroelastic simulation of the parked WindPACT 1.5MW wind turbine blade and to the stability analysis of the blade. Reduced flapwise deflection from the nonlinear aeroelastic model is observed compared to the linear aeroelastic code FAST. The calculated damping ratio of the edgewise mode is much lower than the calculated damping ratio of the flapwise mode, indicating that edgewise instability is more likely to occur than flapwise instability. It is also demonstrated that improper rotor rotational speeds can result in edgewise instability.

The overall aim of this research is to devise a climate change engagement modelling with an associated platform that would contribute to successfully engage the public and prompt them to move away from anti-environmental behaviour and closer to a sustainable lifestyle. The research model relies on the creation of new types of online social networks (‘Blended Social Network (BSN)), which comprises the new type of online social network with featured ICT techniques, including: context-aware user profiling, individual social marketing, social learning, location-based services and the ‘attraction modules’. The new model are able to support a bottom-up approach through adopting persuasive techniques that will likely lead to an enhanced public acceptance of environmental sustainability. The methodology design has four main phases, which are the literature review and conceptual model development, followed by three empirical stages: the empirical field study of public perceptions survey, development of prototype platform and the testing and validation of the conceptual model of the study. The first phase undertaken: (i) to identify a gap in the research, conceptualise a research engagement model, identify the key perception constructs that are used in phase two of this research, formulate the comprehensive theoretical validation framework to check the validity of the conceptual model, and measure the influence of the model on people’s intentions to change negative behaviour to be compatible with a sustainable lifestyle. In the second phase, the large survey (n=1173), was conducted to investigate public perception to provide information about public understanding towards sustainability issues and their perceptions related to components of the conceptual model in general. The outcomes were employed to underpin the model with necessary aspects of engagement in local context and revised it to reflect the real situation. In the phase three, a new prototype ‘Blended Social Network’ (BSN) platform was developed to assist and enable the researcher to explain and validate all of the concepts involved in the conceptual model. The prototype platform was used to assess the capability of the BSN platform to engage people to adopt a new and sustainable lifestyle. The research hypotheses, thesis conceptual model, and its components were assessed and validated using both quantitative and qualitative approaches. The findings of the empirical study reveal that the conceptual model, is preliminarily accepted by the respondents and has potential positive effects to bridge most of the apparent barriers. For instance, the Blended Social Networks and the ICT modules proposed in this research model may assist people in overcoming most of the obstacles regarding cognition, affective and intention to change behaviour attributes including facilitating conditions and perceived behaviour control. This provides evidence of the significant role of the proposed the BSN platform and the ICT techniques in engaging people toward sustainability. The detailed validation results of this study show that the three engagement constructs considered in the model account for 71% of the dependent variable of users’ preparedness to engage, relying on the use of the BSN itself, 69% for the dependent variable of users’ preparedness to engage relying on Context-aware technique, 72.8% rely on Place-based technique, 51.3% rely on Social learning technique,73.2% rely on Individual social marketing technique, 34.5% rely on Profile-sustainable-labelling technique, 69.2% rely on Participate-current-trends technique and 76.2% rely on the Permanent-incentive technique within the integrated BSN. Variance in a person’s perceptions towards the overall effect of innovation on preparedness to engage was entirely explained by cognitive (ranging between 39.2% and 69.1%), affective factors (ranging between 37.9% and 72.0%) and the intention to change behaviour (ranging between 37.6% and 73.9%).

Balanced and symmetric laminates are pervasive in design practice for the simple reason that thermal warping distortions are associated with non-symmetric laminate designs. Design practice, particularly in the Aerospace sector, has become entrenched and risk averse, hence the reluctance to move away from this simple design rule. However to unlock the full potential of composite laminates, the coupling interactions between in-plane and out-of-plane, must now be considered. Thermally stable laminates can now be achieved through sophisticated tailoring design strategies, leading to mechanically coupled materials properties with immunity to thermal warping distortion. This unique quality is known as the hygro-thermally curvature-stable (HTCS). The Extension-Twisting (and Shearing-Bending) coupled laminate is one particular class of coupled laminate with HTCS properties, which is an enabling technology for tilt-rotor aircraft. This class of laminate may be derived using standard ply angle orientations i.e. 45, 45, 0 and 90°, which in comparison to free form angle ply orientations, developed through an optimisation technique, will facilitate the requirement for ply terminations, whilst preserving the Extension-Twisting coupling behaviour within the entire laminate tapered design. Free form angle laminates make thickness tapering virtually impossible, particularly if maintaining consistent coupling behaviour within the entire laminate is a design constraint. Extension-Twisting coupled laminates derived from standard angle orientations with HTCS properties are shown to exist only for 8-, 12-, 16- and 20-ply number groupings, and an assessment of the configurations for each twist magnitude and buckling load strength is presented for each case. The limited number of groupings these coupled laminate solutions is shown to be the result of employing unidirectional material. The above restrictions for UD material may be relaxed for laminates with balanced Plain weave material, which are shown to be inherently thermally curvature stable. Balanced Plain weave material results in a broader design space for mechanically coupled laminates; irrespective of the ply angle orientations and ply number grouping. This benefit provides more flexibility for laminate tailoring and thickness tapering; where the mechanical coupling behaviour and immunity to thermal warping distortions is maintained throughout, it also opens up the possibility of changing the coupling behaviour through a novel ply termination strategy. Where standard ply angle orientations are a design constraint, seven unique classes of mechanically coupled laminates exist with interactions between Extension, Shearing, Bending, and Twisting. Alternative woven cloth architecture are also considered. For instance, 5-Harness Satin (5HS) weave material, possesses straighter load-carrying fibres and low crimp angle, gives rise to improve mechanical performance in comparison to Plain weave material, in which maximum fibre kinking potentially exists. However, due to the unsymmetric nature of the 5HS weave architecture, a single layer of this material is shown to be thermally unstable, therefore a method is presented to predict the thermal warping curvature and eliminate their effect by applying suitable lamination strategies.

Molecules adsorbed on surfaces can show fascinating characteristics and properties. In particular the assembly of molecules into ordered arrays on surfaces is of great interest, whether one considers possible commercial applications or fundamental physical interactions. Specifically, the mediation of ordered molecular arrangements via hydrogen bonding yields many interesting structures. This thesis focusses primarily on the importance of hydrogen bonding between molecules on surfaces in ultra high vacuum (UHV), and how these interactions govern ordered phase formation. Scanning tunnelling microscopy is used to investigate the planar perylene derivative PTCDA on the hexagonal Ag-Si(111) (sqrt 3) * (sqrt 3)R30^o surface alone, with C_{60}, and with melamine. Interesting molecular architectures are observed including a square PTCDA arrangement, and a PTCDA-melamine hexagonal network which contains both stabilising hydrogen bonds and potentially repulsive interactions. Hydrogen bonding systems of pyridinecarboxylic acids on rutile TiO_2 have been studied using photoemission spectroscopy. Ordered films of isonicotinic acid were investigated using valence band photoemission, and an angular dependence is observed in valence band spectra as the angle between the sample and the incoming light is changed. Biisonicotinic acid was also studied on TiO_2 and on gold using core level photoemission to determine how it bonds to these surfaces; it is thought to chemisorb to both TiO_2 and gold through its carboxylic acid groups in an upright orientation. Some large or fragile molecules cannot be sublimed in vacuum for deposition as they fragment. Another research focus has been the development of a technique for depositing non-volatile molecules in vacuum directly from solution. Concepts of electrospray ionisation have been used in the development of a vacuum electrospray deposition system. The molecule is dissolved or suspended in solution and electrosprayed directly into a vacuum environment, with the result that molecules of interest are deposited on a sample without fragmentation or corruption. The samples may then be investigated with vacuum based techniques such as scanning tunnelling microscopy and photoemission spectroscopy.

Multi-storey precast concrete skeletal structures are assembled from individual prefabricated components which are erected on-site using various types of connections. In the current design of these structures, beam-to-column connections are assumed to be pin jointed. This current research work focuses on the flexural behaviour of the beam-to-column connections and their effect on the behaviour of the global precast concrete frame. The experimental work has involved the determination of moment-rotation relationships for semi-rigid precast concrete connections both in full scale connection tests and smaller isolated joint tests. This has been done using the so called "component method" in which the deformation of various parts of the connection and their interfaces are summated, and compared with results from full scale sub-frame connection tests. The effects of stress redistribution, shear interaction etc. are taken of by linear transformation in the results from the full scale tests, enabling parametric equations to be formulated empirically in order to describe the semi-rigid behaviour. Eight full scale column-beam-slab assemblages were tested to determine the (hogging) moment-rotation behaviour of double (balanced loading) and single sided in-plane connections. Two of the most common types of connection were used, the welded plate and the billet type. Proprietary hollow core slabs were tied to the beams by tensile reinforcing bars, which also provide the in-plane continuity across the joint. The strength of the connections in the double sided tests was at least 0.84 times the predicted moment of resistance of the composite beam and slab. The strength of the single sided connections was limited by the strength of the connection itself, and was approximately half of that for the double sided connection, even though the connection was identical. The secant stiffness of the connections ranged from 0.7 to 3.9 times the flexural stiffness of the attached beam. When the connections were tested without the floor slabs and tie steel, the reduced strength and stiffness were approximately a third and half respectively. This remarkable contribution of the floor strength and stiffness to the flexural capacity of the joint is currently neglected in the design process for precast concrete frames. Measurements of the extent of damaged zones near to the connection in full scale tests showed that, unlike steel connections, semi-rigid behaviour in precast concrete does not occur at a single nodal position. In general the double sided connections were found to be more suited to a semi-rigid design approach than the single sided ones. Analytical studies were carried out to determine empirical design equations for column effective length factors β in unbraced and partially braced precast concrete frames. The main variables were the relative flexural stiffness α of the frame members, and the relative linear rotational stiffness Ks of the connection to that of an encastre beam. The variation of β factors with Ks and α are presented graphically and in the form of design equations similar to those currently used in BS 8 110. The change in the response of a structure is greatest when 0< Ks <1.5 where β is found to be more sensitive to changes in Ks than α. When Ks >2 the changes in the behaviour are so small that they may be ignored within the usual levels of accuracy associated with stability analysis. This is an important finding because the experiments have found Ks to be generally less than 2 for typical sizes of beam. The results enable designers to determine β factors for situations currently not catered for in design codes of practice, in particular the upper storey of a partially braced frame. A design method is proposed to extend the concrete column design approach in BS 8110 and EC2, whereby the strength and semi-rigid stiffness of the connection enables column bending moments to be distributed to the connected beams. However, the suitability of each type of connection towards a semi-rigid design approach must be related to the stiffness and strength of the frame for which it is a part.

It is necessary at the design stage to predict the creep behaviour of components and structures operating at high temperature. The direct calculation of the creep behaviour requires extensive material data for the long service lives of the components and engineering methods are needed to minimise the amount of data needed. This can be achieved in some cases by use of the so called Reference stress method and the objective of this work was the experimental prediction of the creep deformation of some components using developments of this idea. It has been achieved by the determination of Reference stresses from accelerated room temperature creep tests of lead alloy models. Reference stresses, which characterise the creep response of components in relation to uniaxial tests, have previously been determined by calculation. Reference stresses determined by the new experimental methods have been compared with analytical predictions for beams in pure bending, cantilevers, thin cylinders and thin spheres under internal pressure. Acceptable agreement was found for the Reference stresses and consequent predictions of creep deformations. The method has also been used successfully to predict creep strains in a cylindrical pressure vessel with a hemispherical end. The methods of chill-casting models from a lead-antimony-arsenic alloy have been improved and the material has been calibrated by constant and stepped load, uniaxial and biaxial (combined pressure and torsion of thin cylinders) tests. The creep strains cannot be characterised by separate. stress and time functions; a strain hardening law best describes its stepped load response; the von-Mises criterion gives accurate predictions of creep strains in the tension-compression quadrant but underestimates the creep strains in the tension-tension quadrant.