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Ni-based superalloys have been extensively used in high-value-added industries due to their excellent performance in extremely harsh environment, i.e. high strength at elevated temperature over the service life. However, their physical material properties also cause this class of materials difficult to be machined and yield to low surface integrity. Thus, the surface integrity related machinability evaluation of such kinds of superalloy is essential for safety critical components manufacturers (e.g. aerospace, nuclear, and marine) to increase their service life. However, the traditional evaluation methods are either time or money consuming as varieties of cutting experiments are needed to collect enough information. In addition, these methods could only assess a specific set of cutting parameters at a time. Therefore, with the varying combinations of cutting parameters, the test becomes complicated due to the fact that multiple factors need to be considered to establish the threshold of cutting parameters which ensure the compliance with required workpiece surface integrity. In particular, surface integrity related machinability is usually studied by conducting cutting tests on conventional machine tools by varying the cutting parameters and followed by part sectioning to analyse superficial layer damages, which is obviously time consuming and resourceful. The research project in this thesis is related to Rolls Royce plc. and SECO Tools AB, aiming to develop a novel method that is able to evaluate the surface integrity related machinability of materials quickly with a limited volume of workpiece. A Pendulum-Based Cutting Test (PBCT) methodology is proposed which allows quick cutting tests for surface integrity evaluation along with providing cutting energies associated with particular levels of workpiece surface damage; this is supported by an unified cutting energy model that links level of machined surface with energy partition in the cutting areas. This method could rapidly define the energy consumed during the cutting process that result in particular magnitudes of surface damage without using conventional machine tools, while with the ability to monitor the cutting process in detail with only limited amount of materials required. The test results show that the level of surface damage could be related by the input energy, while given different cutting parameters that yield the same input energy, then result in the same level of surface damage. This gives the possibility to define energy thresholds for ensuring that particular levels of surface damage are not exceeded; hence, there is no need to test various cutting parameters. Therefore, this approach introduces an advantage for optimization and selection of cutting parameters for specific surface integrity by studying the input energy levels of the cutting process rather than performing extensive machining trails with various cutting parameter combinations blindly. Moreover, this research proposes an innovative concept which is able to generate machined surface that covers a wide range of cutting speeds continuously on a very limited geometry sample through a single test, thus to allow to continuously study the cutting performance transition of materials (e.g. Ni-based superalloy) at different cutting conditions. An obvious chip morphology variation, i.e. serrated chips at the start areas and smooth chips at the end of the chip, can be achieved, due to the decrease of cutting speed during cutting process. Coupled with energy-based surface integrity evaluation method, the consumed energy in different cutting areas (shear, friction and ploughing) at different cutting speeds could be evaluated and correlated with the continuous cutting mechanism transition along with various cutting conditions. To quantitatively study the plastic deformation of acquired machined surface, Electron Back Scattering Diffraction (EBSD) techniques has been employed. The experimental results showed that this research introduces an efficient way to carry out the surface integrity investigation of materials. To conclude, a quick and simple method to evaluate the surface related machinability of materials in limited volume is of great interest for both academic and industrial areas. Therefore, as described above, the motivation of this thesis is to develop a new method to accomplish the anticipated ability. The innovative PBCT method supported by built energy evaluation model has been proposed to carry out the surface integrity related machinability evaluation tests for materials, while a quantitative method for surface damage level on machined components has been introduced to accurately identify the surface integrity. All of the demonstrations for the proposed concept and method are presented with Inconel 718 as examples, while detailed validation tests are discussed in this thesis.

This thesis comprises studies of deformation of thin wires in torsion. Generally, experiments in small-scale plasticity usually focus on small-sized samples. However, studying thin wires with lengths up to a meter in torsion has the advantage of giving extremely high strain resolution and reversal of the loading direction. These experiments allow the transition from elastic to plastic deformation to be studied in forward and reversed loading and subsequently to high strains. In this way the work explored the very early stages of plastic deformation. This is important since structural failure is usually a consequence of exceeding the elastic limit. Micro-strain plastic deformation, dislocation creep, Bauschinger effects and the thermal activated recovery were easily observed. The onset of irreversible deformation was also observed and associated with a few dislocations in the largest grains throughout the wire. Easy plastic deformation on reversal of the loading direction was observed following this initial plastic deformation but not before. Strain hardening behaviour was also studied. Comparing to the traditional torque-torsion method, much higher sensitivity was achieved. Data was fitted with the Ramsberg-Osgood equation to reveal the facts underlying strain hardening and flow stress. Size dependence of the plastic deformation was studied in wires with different diameters and grain sizes. The onset of plastic deformation and subsequent hardening could be related to the combined length-scale of the wire diameter and grain size. The results in this thesis are important to understanding plasticity in confined volumes and at very low strains. The control of strength by the length-scale of the materials provides a new technique for controlling strength and fatigue resistance in metallic materials.

The data presented shows that IL-1beta has a biphasic effect on PTC TGF-beta signalling, with early NF-kappaB-mediated inhibition and delayed sensitization via an autocrine IL-6 loop, and possibly also via an autocrine IL-6 loop, and possibly also via a switch from NF Kappa B p52/p50 heterodimer to p50/p50 homodimer formation. Secondly, the data indicates that BMP-7 prevents TGF-beta1-mediated loss of the transcriptional repressor SnoN and hence specifically limits Smad3 DNA binding, altering the balance of transcriptional responses to TGF-beta1 in PTC.

This dissertation covers several issues related to the ac-dc bus-interface bi-directional converters in renewable energy systems. The dissertation explores a dc-electronic distribution system for residential and commercial applications with a focus on the design of an ac-dc bi-directional converter for such application. This converter is named as the "Energy Control Center" due to its unique role in the system. First, the impact of the unbalanced power from the ac grid, especially the single-phase grid, on the dc system operation is analyzed. Then, a simple ac-dc two-stage topology and an advanced digital control system is proposed with a detailed design procedure. The proposed converter system significantly reduces the dc-link capacitor volume and achieves a dynamics-decoupling operation between the interfaced systems. The total volume of the two-stage topology can be reduced by upto three times compared with the typical design of a full-bridge converter. In addition, film capacitors can be used instead of electrolytic capacitors in the system, and thus the whole system reliability is improved. A set of ac passive plus active filter solutions is proposed for the ac-dc bus-interface converter which significantly reduces the total power filter volume but still eliminate the total leakage current and the common-mode conducted EMI noises by more than 90%. The dc-side low-frequency CM voltage ripple generated by the unbalanced ac voltages can be eliminated as well. The proposed solution features a high reliability and fits three types of the prevalent low-voltage ac distribution systems. Grid synchronization, a critical interface control in ac-dc bus-interface converters, is discussed in detail. First, a novel single-phase grid synchronization solution is proposed to achieve the rejection of multiple noises as well as the capability to track the ac voltage amplitude. Then, a comprehensive modeling methodology of the grid synchronization for three-phase system is proposed to explain the output frequency behaviors of grid-interface power converters at the weak grid, at the islanded condition, and at the multi-converter condition. The proposed models provide a strong tool to predict the grid synchronization instabilities raised from industries under many operating conditions, which is critical in future more-distributed-generation power systems. Islanding detection issues in ac-dc bus-interface converters are discussed in detail. More than five frequency-based islanding detection algorithms are proposed. These solutions achieve different performances and are suitable for different applications, which are advantageous over existing solutions. More importantly, the detailed modeling, trade-off analysis, and design procedures are given to help completely understand the principles. In the end, the effectiveness of the proposed solutions in a multiple-converter system are analyzed. The results drawn from the discussion can help engineers to evaluate other existing solutions as well.

This dissertation research examines, theoretically and empirically, the forms and contents of journalistic practices in contemporary China. By following Pierre Bourdieu, I define journalism as a "sub-field" of the three major fields of social activity¯the state, market, and society, all of which are related to, nested under, and affected by the field of power. Therefore journalistic practice is interpreted as competing for legitimacy, a form of power that struggles over symbolic capital. By focusing on media construction of four major public health crises from early 1980s to 2010, I present detailed descriptions and analyses of the complexity and dynamics surrounding news production of public health issues.

This thesis proposes a complete modeling and control design methodology for a multifunctional single-phase bidirectional PWM converter in renewable energy systems. There is a generic current loop for different modes of operation to ease the transition between different modes, including stand-alone inverter mode, grid-tied inverter mode, grid-tied rectifier mode and grid-tied charger/discharger mode. Under stand-alone mode operation, ac voltage regulation is of importance because of the sensitive loads. In this thesis, different multi-loop-based control schemes are investigated and compared, especially between the load current feedback control, PR control and capacitor current loop control. It shows that PR controller reduces the steady-state error, while load current feedback controller improves the transient response. However, the load current feedback controller and capacitor current loop controller presents unstable outputs under some filter load condition. Single-phase d-q frame control is also studied. In order to ease the implementation effort, an unbalanced d-q frame control is proposed to achieve zero steady-state error voltage regulation without generating β-axis component. Based on the same principle, a d-q frame-based single-phase PLL is also proposed to achieve the fast dynamic response with the zero steady-state error phase tracking. The entire control system is verified on a modified 7 kW single-phase PWM converter prototype with a simple DSP-based digital implementation. The load step response test is presented under different modes of operation. The controllers for stand-alone mode are also done under no load, 1 kW resistive load, 1kVar capacitive load, and non-linear load conditions verifying that the single-phase d-q achieves 70% steady-state error improvement if taking the normal PID controller as the baseline design. In the end, the proposed PLL is compared with the standard PLL by experiments showing that the steady-state error can be reduced by 80%.