Traditional PI controllers have been largely employed for the control of industrial variable speed drives due to the design ease and performance satisfaction they provide but, the problem is that these controllers do not always provide robust performance under variable loads. Existing solutions present themselves as complex control strategies that demand specialist expertise for their implementation. As a direct consequence, these factors have limited their adoption for the industrial control of drives. To counter this trend, the thesis proposes two techniques for robust control system design. The developed strategies employ particular Evolutionary Algorithms EA), which enable their simple and automated implementation. More specifically, the EA employed and tested are the Genetic Algorithms (GA), Bacterial Foraging (BF) and the novel Hybrid Bacterial Foraging, which combines specific desirable features of the GA and BF. The first technique, aptly termed Robust Experimental Control Design, employs the above mentioned EA in an automated trial-and-error approach that involves directly testing control parameters on the experimental drive system, while it operates under variable mechanical loads, evolving towards the best possible solutions to the control problem. The second strategy, Robust Identification-based Control Design, involves a GA system identification procedure employed in automatically defining an uncertainty model for the variable mechanical loads and, through the adoption of the Frequency Domain H-infinity Method in combination with the developed EA, robust controllers for drive systems are designed. The results that highlight the effectiveness of the robust control system design techniques are presented. Performance comparisons between the design techniques and amongst the employed EA are also shown. The developed techniques possess commercially viable qualities because they elude the need for skilled expertise in their implementation and are deployed in a simple and automated fashion.

In order to understand the behaviour of two-phase flow in inclined pipes, an extensive programme of work has been undertaken using the Inclinable Facility in the laboratories of the School of Chemical, Environmental and Mining Engineering at the University of Nottingham. The test pipe (6.5 m long) could be positioned at angles between -20° downwards and vertical upwards. Two pipe diameters were used; namely 38 mm and 67 mm. The fluids used were air and water. Superficial velocities for air ranged from 0.15 to 8.9 m/s and from 0.04 m/s to 0.7 m/s for water. Time series of liquid holdup (using capacitance probes) and pressure drop (differential pressure transducer) were measured. In addition, a high speed video system was used in order to obtain image sequence of the flow under different selected conditions. It was found that for upward inclined flow most of the experiments fall within the slug flow regime whereas for inclined downward flow the dominant flow pattern is stratified flow. For horizontal flow, the flow regime depends more on the gas and liquid superficial velocities. Data for liquid holdup, pressure drop, frequency and translational velocity of periodical structures are reported. Comparisons with literature correlations and data are performed as well. Frequency was found to be strongly affected by inclination angle and a correlation has been proposed. An effect of the pipe diameter is also found under certain flow conditions mainly on the liquid holdup, pressure drop and structure velocity. Increase of pipe diameter displaces the bubbly-slug transition to the right hand side on the flow pattern map for inclined flow, and for horizontal pipe the stratified-slug transition is moved up. In addition, a CFD code has been used to successfully model the hydrodynamics of In addition, a CFD code has been used to successfully model the hydrodynamics of the slug flow pattern, using the Volume of Fluid model based on the Euler-Euler approach. The modeling results are validated with the experiments and also provide more detailed information on the flow such as the velocity field.

Fixtures are used to fixate, position and support workpieces, and are critical elements in manufacturing processes. Machining is one of these manufacturing processes, and this is often done by computer numerical control (CNC) machines. A major trend observed in production industry is that manufacturing is increasingly done in small batches in combination with a quick changeover from one product to another, in combination with a surge in automation. Several novel fixture concepts have been developed that allow for a reconfiguration of the fixture layout, such that different types of workpieces can be fixtured using the same fixture components. However, the initial novel fixturing concepts lacked accuracy, and, in addition, required long set-up times. Recently, a new fixturing concept has been developed, the so-called intelligent fixturing system. Sensors and actuators are integrated in an intelligent fixturing system, which allows for an automatic and precise reconfiguration of the fixturing elements. Additionally, the actuated fixture elements can be used to exert optimal clamping forces to minimise the workpiece deflection during the machining process, this is called active fixturing. A literature survey has been carried out, in which it has been established that the main process variables to control in active fixturing, are the reaction forces at the contacts where the workpiece is fixated and supported by the fixture (the locating points), and/or the part or fixture displacements. Furthermore, four knowledge gaps were identified: (1) a lack of computationally efficient models of workpiece response during machining; (2) a lack of methodic structural analysis approach of part-fixture interaction; (3) a lack of model-based control design, which can potentially speed up the fixture design process; and (4) a lack of control design methodology for active fixturing systems. An active fixturing system can be divided into the following subsystems: the part, the part-fixture contact interface, passive fixture elements, the actuated clamp, sensors and the controller(s). In the thesis, a methodical research approach has been applied to address the knowledge gaps by analysing the active fixturing subsystems. In addition, a model-based control design methodology has been proposed. The research has aimed to establish mathematical models, or the necessary tools and methodology to build the subsystem models, and methods to connect the subsystem models into an overall model of the active fixturing system. On basis of the subsystem analyses, two simple, yet complete, active fixturing systems have been modelled. Parameter studies have been held to assess the performance of the control design. In addition, an industrial case study has been analysed, using the developed control design methodology. The study of the subsystems resulted in the comprehensive structural dynamic analysis of workpieces: a finite element model of the workpiece is built. Typically, finite element models contain too many degrees of freedom for real-time control applications. It was found that model reduction techniques can be used to reduce significantly the number of degrees of freedom. Methodologies for the selection of the degrees of freedom and for ensuring that the model reduction is accurate enough for practical use have been established. Mathematical models for hydraulically and electromechanically actuated clamps have been established. Compensators for closed-loop servo-control of the clamps have been investigated and control strategies to maintain workholding stability are found. Finally, a methodology to establish the overall model of an active fixturing system has been implemented. The control design methodology, and the mathematical tools established in the thesis have been verified against case studies of simple active fixturing systems. Furthermore, from the industrial case study it is concluded that the control design methodology can be successfully applied on complex fixturing systems. Additionally, a mathematical model for a piezoelectrically actuated clamp was derived, which also demonstrates the general applicability of the control design methodology derived here, as a new established actuator model is integrated in the control design. The overall conclusion, is hence that a good methodology for the model-based control design of active part-fixturing systems has been developed, which enables the engineer to speed up the design process of active fixturing systems.

The following work details an investigation into improving efficiency in pulverised-fuel- fired power stations. The particular area of focus is the splitter box; this is located in the pneumatic conveying pipeline within the power station. The conveying pipelines take the pulverised fuel from the mill to the burner face, at some point the air/fuel mixture has to be split to feed the individual burners. It is at these points that the splitter boxes occur, dividing the pipe into multiple legs. It is common for some of these splits to produce poor fuel balance between legs, leading to excess air being required for their combustion at the burner wall. The increased supply of air increases the chance of the formation of NOx gases as well as reducing the overall efficiency of the plant. The poor fuel balance is caused by a particle rope, a dense area of particle stratification that creates an area of high fuel density that is not easily divided by the splitter boxes. The objective of this work is to develop devices to improve the fuel balance at splitter boxes. The work involves an investigation into existing devices and station geometries to see why existing devices have not become commonplace in coal-fired power stations. It also involves conceptual design of devices and then their testing, both computationally and experimentally. Finally, the devices are assessed for their suitability for full-scale power station implementation. This thesis used both experimental and computational techniques to develop devices to overcome the problems at splitter boxes and successfully produced several devices that could be developed and deployed in full scale testing.

The main objective of the thesis is to establish a methodology to analyse the anisothermo-mechanical behaviour of a representative large industrial Superplastic Forming (SPF) tool made of XN40F material (40% Ni, 20% Cr, Balance Fe) to identify and evaluate different failure mechanisms to improve and predict the tool life. Sequentially coupled thermo-mechanical analyses under realistic loading conditions are developed within a general purpose non-linear Finite Element (FE) code, ABAQUS to predict and analyse the complex temperature-stress-strain cycles of the SPF tool. The temperature dependent cyclic plasticity and creep material data is established for the tool material performing the multi-strain range isothermal cyclic tests and the stress relaxation tests for a range of temperatures. Various strain controlled thermomechanical fatigue-creep and stress controlled ratchetting tests are designed and performed based on the preliminary FE analyses of the tool. The strain controlled and the stress controlled representative tests are carried out to capture the most damaging phase of the SPF thermo-mechanical cycle. In addition to above tests, heat transfer tests are also carried out on the rectangular block of tool material to validate the employed heat transfer methodology. Material constants are identified for different material behaviour models such as combined non-linear kinematic/isotropic hardening model for the cyclic plasticity, power law creep model for secondary creep and the two-layer viscoplastic model to address the combination of plasticity and creep. The identified constants are validated against the isothermal and thermo-mechanical fatigue tests. The FE modelling of the heat transfer tests using the calculated convective heat transfer coefficients and other thermal properties is carried out and the predicted thermal histories are compared with the experimental results. The validated heat transfer methodology is employed to simulate the realistic thermal cycles of the SPF tool. In addition to thermal loading, the tool gravity and the clamping pressure to counteract the forming gas pressure are employed in the thermo-mechanical analyses of the tool. The tool platen contact is also modelled where the platen is considered as analytically rigid surface. Various thermo-mechanical analyses are performed to investigate the effect of different thermal cycles, heating and cooling rates and the batch sizes, i.e. number of parts formed in a forming campaign, on the tool damage. Different strain and strain energy based thermo-mechanical fatigue life prediction methodologies are explored and evaluated using the isothermal and thermo-mechanical fatigue-creep lifing tests. The simple ductility exhaustion method is also developed to predict the ratchetting life of the specimen and the tool. The tool life predictions are performed employing the FE predicted stress-strain results into the identified stress-strain-life equations from the isothermal lifing tests. The predicted thermo-mechanical behaviour and tool lives are compared against the representative test and the industrial experience. From all thermo-mechanical fatigue-creep and ratchetting test results and thermo-mechanical analyses of the tool, the fatigue-creep interaction is found to be the most important factor in the tool failure.

The growing worldwide prevalence of cardiovascular diseases (CVD) such as chronic heart failure (CHF) highlights the need for an effective treatment method. Annually, there are an estimated 17.5 million deaths caused by cardiovascular diseases worldwide, representing 30% of all global deaths; of these deaths approximately 50% are due to CHF [1] and about 80% occur in low- and middle-income countries [2]. If current trends are allowed to continue, by 2015 an estimated 20 million people annually will die from CVD [3]. Each year, only about 3,000 people receive a heart transplant as the only current definitive long-term treatment for end-stage CHF. To compound the severity of the situation, organ donations are decreasing (4). Implantable blood pumps offer an effective treatment to CHF, either as a bridge to transplantation / recovery, or as destination therapy i.e. use of long term mechanical circulatory support in patients with end-stage heart failure without the intention of eventual heart transplantation. With the number of sufferers of CHF rising in both the developed and developing world it becomes pertinent to design a cost effective device. It is the objective of this work to investigate the proposal of a new cost-effective Centrifugal Rotary Blood Pump (CRBP), which employs previously unutilized design methodology. Through the replacement of those complex, custom components seen within existing CRBPs with standard off-the-shelf components, and the implementation of high-throughput manufacturing processes, such as injection moulding, a reduction in component parts allows for a reduced profit margin and hence a reduced total cost of device. It is proposed by the author that the current production cost of LVAD devices may be reduced by up to 95%. The work presented in this thesis identifies the principal difference between current pump designs; this is their bearing system. It is proposed here to form a new classification of bearing type that combines a passive magnetic bearing and a hydrodynamic bearing such that the relative potential merits of both systems may be exploited. Through the amalgamation of established design techniques with other more modern design practices a rigorous, adaptive design tool has been produced that CRBP designers may use to quickly obtain full impeller and volute geometry from few input parameters. The geometry output provides a platform from which a new conceptual Left Ventricular Assist Device (LVAD) has been envisaged. Through experimental and computational analysis of the magnetic coupling, this investigation has shown that it is possible to integrate the magnetic bearing and the drive system into one component of design; it is possible to design a magnetic coupling that not only acts as the drive system for a CRBP, but as a bearing system that offers both axial and radial bearing forces. A spiral groove bearing (5GB) has been implemented as the hydrodynamic bearing as part of the hybrid system. Experimental investigation has shown the spiral groove bearing to be anti traumatic, which may be attributed to the short residence time of blood in the bearing. However, a reduction in the anticipated load capacity shows that the bearings are operating on a reduced viscosity; this is an indication of cell exclusion within the 5GB. Comparisons to aqueous glycerol tests of known viscosities have shown that the blood bearing is operating on a viscosity close to that of plasma. It is suggested that a "shear front differential" is the mechanism behind cell exclusion, in which RBCs migrate away from areas of high shear stress into areas of relatively low shear stress. This investigation has demonstrated the suitability of the hybrid magnetic / hydrodynamic bearing for use in a new CRBP. It has been shown that the electromagnetic drive system intended for implementation in to this CRBP can be used as an effective passive magnetic bearing. It is intended that the axial and radial bearing forces produced by the drive system are balanced by a conical spiral groove thrust bearing. The incorporation of the hydrodynamic bearing into the magnetic bearing transforms the previously unstable passive magnetic bearing to a stable hybrid bearing. The stability of the system has been predicted through numerical analysis of the stiffness matrix and through satisfaction of the stability criteria. The natural frequencies of the system have been calculated; these are shown to be sufficiently different from any excitation frequencies identified that may cause the system to behave in an unstable fashion at the operational speed of the pump. The main point to be realized from the analysis of the hybrid bearing system, however, is that the proposed set-up of the hybrid bearing is not feasible due to the effect of cell exclusion, which causes the SGB to operate on a reduced viscosity. The reduction in viscosity reduces the load capacity of the SGB; the magnetic preload on the impeller cannot be balanced by the chosen SGB geometry. Recommendations have been made as to the design parameters that may be altered such that the design intent of the proposed system may be realised. Future work must concentrate on the realization of that design intent through the manufacture of a prototype, which can provide a proof-of-concept for the proposed system. The work presented here provides a feasibility study for the novel hybrid bearing / drive system and provides sound foundation upon which a prototype may be based.

The Gas-Liquid Cylindrical Cyclone (GLCC) separator is commonly used for the separation of oil and gas mixtures flowing from the well head. Similar to the design used by other separators, it has an inlet and two outlets for gas and liquid respectively. However, the inlet to the separator can either be single or dual type. The pipeline connection from the upstream preconditioning equipment (CFC) is inclined downwards and has a tangential inlet slot. The essence of having a downward inclination is to promote pre-separation of the fluid phases. On the other hand, a tangential inlet promotes circular fluid motion thereby inducing separation of the fluid phases by centrifugal forces. Due to the complex behaviour of the flow within the GLCC, liquid carry over (LCO) as drops into the gas phase pipeline and gas carry under (GCU) as bubbles into the liquid phase pipeline are inevitable. Both phenomena greatly reduce the purity of the fluid phases at the outlets. To overcome this challenge, it has been proposed from field experiments carried out by Chevron Energy Technology Company, to precondition the influent flow in an upstream vertical pipe before entrance to the GLCC. In order words, a suggested solution to overcoming liquid carry over (LCO) and gas carry under (GCU) is to precondition the oil/gas mixture by forcing small bubbles/drops of 3 - 5mm in diameter to coalesce in an upstream vertical pipe. The upstream vertical preconditioner is known as a Churn Flow Coalescer (CFC). This is because the churn flow regime is the most suitable for the coalescence of both liquid and gas phases. Therefore, it is in the scope of this research work to carry out detailed preconditioning experiments within an upstream vertical pipe that serves the purpose of a Churn Flow Coalescer (CFC). All experiments in this research work have been carried out in the Chemical and Environmental Engineering L3 laboratory at the University of Nottingham. Although, the churn flow regime is specifically the most suitable for the GLCC, the operational envelope for the initial set of experiments spans the bubble to churn regimes. This is because the experiments were performed with the aim of delineating the conditions for the inception of typical churn flow in a large diameter pipe. These set of experiments were conducted in a 121mm internal diameter, 5.3m in length vertical pipe using air and water as the operating fluids. In these experiments, slug flow characterised by a Taylor bubble and a liquid slug was not observed. The churn flow regime is made up of two sub-regimes namely: liquid bridging of the gas core and formation of huge waves. The former is a phenomenon that occurs when the liquid phase forms a bridge as a result of radial coalescence of the wave crests flowing about the pipe centreline and momentarily blocks the entire pipe cross-section. The huge waves occur when the liquid phase flows as waves on the inner walls of the pipe and about the pipe centreline having large amplitudes. Between bubble to churn flow regimes in these experiments, four regimes were observed namely, discrete bubbly flow and spherical cap bubbly flow which make up the bubbly flow regime, churn turbulent regime (transition region) and typical churn flow regime. These experiments paved way for detailed experiments to be carried within the churn flow regime. Detailed churn flow experiments were then carried out in a large scale closed loop facility having an internal diameter of 127mm and a longer vertical pipe of 11m. The rationale for performing the experiments in this facility is because the facility offered a wider range of conditions within the churn flow compared to the first experimental rig facility. Data was acquired at L/D = 2.4, 7.1, 30.7, 35.4 and 82.7 which represent different axial distances from the gas-liquid injection at the base of the test section. Air and water were also used as the operating fluids. The void fraction data acquired at different axial distance from the injection varies logarithmically with increase in axial distance. The flow can be considered to be developed at L/D = 82.7 based on the void fraction. In addition, the frequency of liquid bridging of the gas core decays with increasing distance from the injection (downstream) while the frequency of the huge waves and liquid structures entrained in the gas core increases downstream from the injection due to coalescence. Finally, the effect of viscosity in the churn flow regime was investigated using air-glycerol/ water as the fluid pairs in the same large scale loop facility. Two glycerol/water mixtures were used having viscosities of 12.2cP and 16.2cP respectively. The data was acquired at a suitable axial distance from the injection at L/D = 65.5. In this experimental campaign, the size and frequency of the liquid structures entrained in the gas core are larger compared to the liquid structures present when experiments were carried out using air-water as the operating fluids. As a result, this gives a bi-modal probability distribution for air-glycerol/ water compared to air-water. Similar to the air-water experiments, the liquid bridging operating condition gives a high degree of coalescence of both phases. The mechanism of entrained liquid structure formation has been proposed based on the comparative study to the air-water experiments. A model has also been developed that predicts the effective length of pipe for the Churn Flow Coalescer (CFC). Overall, the liquid bridging sub-regime of churn flow should be the prevailing condition in the CFC to enhance proper separation of gas and liquid phases in the downstream GLCC separator.

This work investigates the current situation of energy efficiency policies for commercial buildings in China and evaluates their effectiveness using theory-based policy evaluation methodology. The thesis covers three main research areas: a discussion of energy efficiency improvement measures suitable for commercial buildings in the Chinese national context; a technical support for the theory-based policy evaluation presented in a form of four detailed case studies following the Design Standard for Energy Efficiency of Public Buildings GB20189-2005 (the Standard); and a discussion of the effectiveness of this Standard that was evaluated using theory-based policy evaluation. Future improvements for the energy efficiency in commercial building in China are suggested. Four case studies in different climate zones are used to examine the technical and economical effectiveness of the Design Standard for Energy Efficiency of Public Buildings GB20 189-2005, and investigate the main problems of buildings as energy consumers. The results show that the case study buildings have poor thermal insulation qualities as well as low energy efficiencies of lighting and equipment. The implementation of the Standard allows for the achievement of its individual targets aimed at the thermal insulation quality improvements as well as being cost effective. For a further energy consumption reduction, installation of renewable energy technologies is simulated, however it is limited by economic constraints. The theory-based policy evaluation shows that the Standard is an important tool in energy efficiency encouragement for commercial buildings in China. However, its effectiveness is negatively affected by a lack of monitoring system and a lack of awareness among the involved parties. Improvement of building energy efficiency is the quickest and the most effective way of creating energy savings in buildings. In order to make a better use of the Standard, the Chinese government should stimulate more interest among construction companies and building owners by creating carrot and stick policies.

Spline couplings are a compact and efficient means for transferring torque between shafts in gas turbine aeroengines. With competition in the aerospace market and the need to reduce fuel burn from the flight carriers, there is an ever-present requirement for enhanced performance. Spline couplings are complex components that can fail from a variety of mechanisms, and are susceptible to fretting wear and fretting fatigue (FF). Due to the expensive nature of full-scale testing, this thesis investigates the use of the representative specimen (RS) concept for predicting fretting-induced damage between spline teeth. A combined experimental and computational RS methodology is developed, using a uniaxial representative specimen (URS) and a multiaxial representative specimen (MRS). The URS test rig simulates spline torque and axial loads from the overall flight cycle and associated damage. The MRS simulates the combination of the same major loads, with the addition of high-cycle bending loads from in-flight fluctuations. The URS was successfully employed for experimental characterisation of a range of spline material combinations, including inference of the coefficient-of-friction. The MRS successfully characterised the multiaxial FF behaviour of the current material of choice for triple-spool gas turbine couplings. A finite element-based total fatigue life (crack nucleation and propagation) capability was successfully validated for the MRS and URS. A global sub-modelling technique was employed, whereby a critical-plane Smith-Watson-Topper (SWT) fatigue parameter predicted crack nucleation, an El Haddad approach predicted short crack growth and a weighted function approach predicted long crack growth. A novel FF damage parameter, Dfret, was also implemented to incorporate the combined effects of relative slip and surface shear traction, in conjunction with the SWT parameter, for life prediction. The required material constants were obtained and captured the measured effect of relative slip on a titanium alloy and the measured effect of contact size on an aluminium alloy.

The thesis presented here comprises the work undertaken for research into novel NDE techniques in the power generation industry. This has been undertaken as part of the Engineering Doctorate Scheme run by the Research Centre for Non-Destructive Evaluation (RCNDE), which aims to bridge the technological gap between university research and industrial application. In this case, the scheme consisted of two projects completed in conjunction with RWE npower looking at current NDE problems in steam turbine and steam-raising plant. The first project was concerned with detecting microstructural transformation in steam turbine blades, which can act as a precursor to failure by environmentally assisted cracking. This project, and indeed, this entire thesis is principally based on electromagnetic testing methods. An eddy current technique for mapping the microstructural phases was produced and validated as far as was achievable; this offered a significant time-saving advantage over the previous method, by reducing inspection time from 5 man days to just 1.5. The technique has novelty in producing a 2-dimensional map of the blade surface which highlights areas where microstructural phases differ. The second project focuses on the detection of microstructural damage associated with material creep life expiry. This forms a review of the current state of technology and highlights potentially useful paths for future research in both established and emerging NDE technologies, including Magnetic Barkhausen Noise testing and laser-generated ultrasound. Both projects have provided tangible benefit to the sponsoring company and have pushed forward research in a number of technological applications.