no / Hot spots are high thermal gradients on the disc surface during brake events which can cause the undesired phenomena of thermal judder and drone. The origin of hot spotting has been presented by various theories such as Thermo elastic instability (TEI) and progressive waviness distortions (PWD). However, majority of the numerical models based on these theories mainly concentrated on solid disc rather than ventilated disc which is the most commonly used nowadays. According to the experimental work done by the authors, disc geometry factors such as vents and pins also have correlations with hot spot distribution; these phenomena are difficult to be predicted analytically. Thus a convenient 2D asymmetric finite element simulation has been performed in order to obtain the correlations observed in experiments. Further parameter studies investigated factors such as uneven initial temperature, vents, pins and pad length. The results have been correlated with the experimental data and demonstrate the contribution of geometric factors in the generation of hot spots and hot judder.

No description available.

Laser beam welding has gained a significant interest during the last two decades. The suitability of the process for high volume production has the possibility to give a strong advantage compared to several other welding methods. However, it is important to have the process in full control since various quality issues may otherwise occur. During laser welding of boron steels quality issues such as imperfections, changes in local and global geometry as well as strength reduction can occur. The aspects that need to be considered are strongly depending on alloy content, process parameters etc. These problems that can occur could be fatal for the construction and the lowest level of occurrence is wanted, independent of industry. The focus of this study has been to investigate the properties of laser welded boron steel. The study includes laser welding of boron alloyed steels with strengths of 1500 MPa and a recently introduced 1900 MPa grade. Focus has been to investigate weldability and the occurrence of cracks, porosity and strength reducing microstructure that can occur during laser welding, as well as distortion studies for tolerances in geometry. The results show that both conventional and 1900 MPa boron alloyed steel are suitable for laser welding. Due to the martensitic structure of welds the material tends to behave brittle. Cracking and porosity do not seem to be an issue limiting the use of these steels. For tolerances in geometry for larger structures tests has been done simulating laser welding of A-pillars and B-pillars. Measurements have been done with Vernier caliper as well as a more advanced optical method capturing the movements during the welding sequence. Results from the tests done on Ushaped beams indicates that depending on the geometry of the structure and heat input distortions can be controlled to give distortions from 1 to 8 mm, at a welding length of 700 mm. This means that important geometry points can be distorted several millimeters if the laser welding process not is controlled.

The research presented in this thesis is a collection of many different, yet connected, parts that stemmed from the development of a new alternative material intended to be utilised as anode material in solid oxide fuel cells. The main part is the research conducted in the development and characterisation of the novel A-site deficient La₀.2₂Sr₀.₇₋ₓCaₓTiO₃. Calcium introduction resulted in reducing this perovskite unit cell volume which, at the beginning, enhanced its electrical conductivity in reducing conditions. However, the ideal cubic symmetry coud not be maintained, as in the starting material LA₀.₂Sr₀.₇TiO₃, as a result of the increased A-site ionic radius mismatch and two lower symmetries were observed at room temperature. These were the tetragonal I4/mcm for 0.1 ≤ x ≤ 0.35 and orthorhombic Pbnm for 0.4 ≤ x ≤ 0.7. Higher temperature NPD data showed that the orthorhombic samples transformed into higher symmetries with Pbnm → I4/mcm → Pm3-m phase transitions. Detailed crystallographic analysis is discussed; where the different unit cells showed changes to the tilts of the BO₆ octahedra, along with distortions to these octahedra. DC conductivity measurements showed a high electrical conductivity of 27.5 S/cm for a pre-reduced composition La₀.₂Sr₀.₂₅Ca₀.₄₅TiO₃ at 900°C and pO₂ = 10⁻¹⁹ atm. This material showed very encouraging features; which makes it a very promising anode material for SOFCs. A study was also done which explores the best renewable energy options for the United Arab Emirates given its local climate and other aspects. The reliance on seawater desalination is argued to by unsustainable for different reasons. Thus, water security should be a main element in the planning process for adopting renewable energy technologies. A system that combines different technologies; with a focus on fuel cells technology; is outlined which is thought of to be a very promising basis for a broader system that will secure power and water in a very environment friendly way. Different compositions of the system La₀.₂Sr₀.₇₋ₓCaₓTiO₃ were also studied using AC impedance spectroscopy in order to establish whether or not this system can show a ferroelectric behaviour. Results showed a variation in the dielectric constant of different samples with temperature; however, no Curie point was observed. Nonetheless, the results did show that the different compositions were very homogeneous when fully oxygenated and there were some indications of possible symmetry changes at sub-ambient temperatures. The final part of this thesis outlined the work done towards the development of a new analytical instrument. An existing TGA instrument was altered in order to provide a simultaneous thermogravimetric analysis and DC conductivity measurement for solid solutions at controlled temperature and oxygen partial pressure. Results were obtained for different samples of the system La₀.₂Sr₀.₇₋ₓCaₓTiO₃ which showed a great dependence of the electrical conductivity on the oxygen stoichiometry in these oxides. Also, a direct method is possible with this instrument to estimate the oxygen chemical diffusion coefficient using the electrical conductivity relaxation method. This new setup will be very useful for different electrochemical and thermal studies which can broaden the understanding of the different mechanisms that affect the performance of different solid state materials.

La présence de distorsions cognitives chez les délinquants sexuels est considérée comme étant intimement liée à l’étiologie et au maintient des comportements sexuels déviants. Selon Ward et Keenan (1999), les distorsions cognitives émergent des théories implicites. Les théories implicites peuvent être définies comme étant un réseau de croyances interreliées que les délinquants ont à propos d’eux et du monde qui les entoure. Polaschek et Ward (2002) ainsi que Polaschek et Gannon (2004) ont postulé qu’il existe 5 théories implicites chez les violeurs : Les femmes sont des objets sexuels; L’excitation sexuelle de l’homme est incontrôlable; Le droit de faire ce que nous voulons; Le monde est dangereux; et Les femmes sont dangereuses. La présente recherche avait pour but d’examiner si les théories implicites chez les violeurs étaient pleinement représentées par les travaux de Polaschek et collègues. Les distorsions cognitives de 21 agresseurs sexuels de femmes adultes ont été analysées à partir de l’analyse de leurs discours. Les analyses indiquent que quatre des cinq théories implicites sont présentes dans notre échantillon. De plus, la théorie implicite Les femmes sont des objets sexuels serait mieux conceptualisée en tant que Les femmes sont des objets. Finalement, et en complément aux résultats des études de Polaschek, notre échantillon présente des cognitions qui normalisent la criminalité, la délinquance, la violence et la sexualité pour atteindre leurs buts; nous conduisant à la création d’une nouvelle théorie implicite : Normalisation du crime. Nos résultats indiquent qu’il y aurait peut-être d’autre / The presence of cognitive distortions among sex offenders are considered to be highly influential in the etiology and maintenance of deviant sexual behavior. According to Ward and Keenan (1999), cognitive distortions emerge from implicit theories. Implicit theories can be defined as a network of interrelated beliefs that sex offenders hold about them, the others and the world. Polaschek and Ward (2002) and Polaschek and Gannon (2004) postulates that there is five implicit theories amongst rapists: Women are Sexual objects; Male Sex Drive is Uncontrollable; Entitlement; Dangerous World; and Women are Dangerous. The current research examined whether the cognitive distortions of rapists are fully represent by the implicit theories proposed by Polaschek and colleagues. Semi-structured interviews were conducted with 21 convicted rapists and their cognitive distortions were analyzed using the grounded theory method. Our analysis indicates the presence of four of the five Polaschek’s implicit theories among our sample. In addition, the implicit theory Women are Sex object would better be conceptualise as Women are Object. Finally, and in contrast to Polaschek’s research, our sample of rapists demonstrated cognitions that normalize the use of criminality, delinquency, violence and sexuality to achieve their goals. These findings lead us to the creation of a new implicit theory : Normalisation of Crime. Our findings indicate that there may be implicit theories among rapists that have not yet been fully explored.

The three-dimensional x-ray structure of 2,2'-bipyridylglycinatochloro copper(II) dihydrate has been fully refined to a final R factor of 0.081. The bipyridyl and glycine ligands are arranged about the central copper atom in a square planar configuration while the chlorine atom is 2.635 angstroms above this plane directly over the copper atom. This unusually long distance is explained by the positioning of a glycine group on the opposite side of the square plane, resulting in a distorted octahedral arrangement. Also, the chlorine atom is linked to three oxygen atoms via hydrogen bonding, thus stabilizing the distorted octahedral complex.

>Magister Scientiae - MSc / The growth rate of large-scale structure is a key probe of gravity in the accelerating Universe. Standard models of Dark Energy within General Relativity predict essentially the same growth rate, whereas Modified Gravity theories without Dark Energy predict a different growth rate. Redshift-space distortions lead to anisotropy in the power spectrum, and extracting the monopole and quadrupole allows us to determine the growth rate and thus test theories of gravity. We investigate redshift-space distortions in the intensity maps of the 21cm emission line of neutral hydrogen (HI) in galaxies after the Epoch of Reionization: HI intensity mapping delivers very accurate redshifts. We first use the standard approach based on the Fourier power spectrum. Then we explored an alternative approach, based on the spherical-harmonic angular power spectrum. Fisher forecasting was used to make predictions of the accuracy with which MeerKAT will measure the growth rate parameter, via the proposed MeerKAT Large Area Synoptic Survey (MeerKLASS). Then we extend the forecasts to consider the planned HI intensity mapping survey in Phase 1 of the Square Kilometre Array. These forecasts enable us to predict at what level of accuracy General relativity and various alternative theories could be ruled out.

O objetivo geral desta tese foi investigar as associações entre as variáveis autoeficácia, locus de controle, distorções cognitivas, catastrofização da dor, depressão, ansiedade, nível de incapacidade gerado pela cefaleia e qualidade de vida em pacientes com migrânea. Para isso, 147 indivíduos foram selecionados dentre os pacientes cadastrados nos ambulatórios de cefaleia de três hospitais de referência da região Sul do Brasil. A tese foi composta por quatro estudos. Os dois primeiros tiveram por objetivo adaptar e validar para o contexto brasileiro a Headache Management Self-Efficacy Scale e a Headache-Specific Locus of Control Scale, respectivamente. O terceiro estudo teve por objetivo construir e validar um instrumento de avaliação de distorções cognitivas, aplicado ao contexto do tratamento da migrânea. Por fim, o quarto estudo buscou investigar as associações entre a frequência e a severidade da cefaleia, as principais comorbidades psiquiátricas e as medidas validadas nos três estudos anteriores. Os resultados indicaram que a versão brasileira reduzida da Headache Management Self-Efficacy Scale (HMSE-10), a versão brasileira da Headache-Specific Locus of Control Scale e o Inventário de Distorções Cognitivas relacionadas à Cefaleia (INDICCE) representam medidas válidas e confiáveis de crenças de autoeficácia, locus de controle e distorções cognitivas na migrânea, respectivamente. Ademais, as respostas cognitivas e emocionais dos pacientes estiveram associadas aos níveis de incapacidade e cronicidade da cefaleia. Espera-se que os resultados obtidos nos quatro estudos da tese contribuam para o desenvolvimento de futuros protocolos de intervenções psicológicas para a migrânea. / The aim of this thesis was to investigate the relationships between self-efficacy, locus of control, cognitive distortions, pain catastrophizing, depression, anxiety, headache-related disability and quality of life in patients with migraine. 147 individuals were selected among patients enrolled in the headache outpatient clinics of three reference hospitals in the southern region of Brazil. The thesis is composed of four studies. The first two studies had the objective of adapting and validating the Headache Management Self-Efficacy Scale and the Headache-Specific Locus of Control Scale, respectively. The third study aimed to construct and validate an instrument to evaluate cognitive distortions applied to the context of migraine treatment. Finally, the fourth study sought to investigate the associations between frequency and severity of headache, main psychiatric comorbidities and the measures validated in the three previous studies. The results indicate that the Brazilian short version of the Headache Management Self-Efficacy Scale (HMSE-10), the Brazilian version of the Headache-Specific Locus of Control Scale and the Inventory of Cognitive Distortions related to Headache (INDICCE) are valid and reliable measures of self-efficacy beliefs, locus of control and cognitive distortions in migraine, respectively. In addition, cognitive and emotional responses of patients were associated with headache-related disability and chronicity. We hope that the results obtained in the four studies in this thesis will contribute to the development of future protocols for psychological interventions for migraine.

Although the overall levels of harmonics in modern power supply systems are in most of the practical cases still below the prescribed tolerance limits and thresholds (e.g. these stipulated in [IEC 61000-3-2 and 61000-3-12]), the sources of harmonics are constantly increasing in numbers and are expected to increase even more in the future. Some of the examples of modern non-linear power electronic (PE) devices that are expected to be employed on a much wider scale in LV networks in the future include: light-emitting diode (LED) lamps, switched-mode power supplies (SMPS'), electric vehicle battery chargers (EVBCs) and photovoltaic inverters (PVIs), which are all analysed in this thesis. The thesis first reviews the conventional harmonic analysis methods, investigating their applicability to modern PE devices. After that, the two most widely used forms of harmonic models, i.e. component-based models (CBMs) and frequency-domain models (FDMs), are applied for modelling of the four abovementioned types of modern PE devices and their models are fully validated by measurements. The thesis next investigates the impact of supply voltage conditions and operating modes (e.g. low vs high operating powers) on the device characteristics and performance, using both measurements and developed CBMs and FDMs. The obtained results confirm that both supply conditions and operating modes have an impact on the characteristics of most of the considered PE devices, which is taken into account in the developed models and demonstrated on a number of case studies. As the next contribution, the thesis proposes new indices for the evaluation of current waveform distortions, allowing for a separate analysis of contributions of low and high frequency harmonics and interharmonics to the total waveform distortion of PE devices. As the modern PE devices are normally based on high-frequency switching converters or inverters, the impact of circuit topologies and control algorithms on their harmonic emission characteristics and performance is also investigated. Special attention is given to the operation of PE devices at low powers, when there is a significant increase of current waveform distortion, a substantial decrease of efficiency and power factors and when input ac current might lose its periodicity with the supply voltage frequency. This is analysed in detail for SMPS', resulting in the proposal of a new methodology ("operating cycle based method") for evaluating overall performance of PE devices across the entire range of operating powers. Finally, a novel and simple hybrid harmonic modelling technique, allowing for the use of both time-domain and frequency-domain models in the same simulation environment, is proposed and illustrated on the selected case studies. This is accompanied with a frequency-domain aggregation approach, which is applied in the thesis to investigate the impact of increasing numbers of different types of modern PE devices on the LV network. The implementation of the developed hybrid harmonic modelling approach and frequency-domain aggregation technique is demonstrated on the example of a typical (UK) urban generic LV distribution network and used for the analysis of different deployment levels of EVs and PVIs. The presented harmonic modelling framework for individual PE devices and, particularly, for their aggregate models, fills the gap in the existing literature on harmonic modelling and characterisation of modern PE devices, which is important for the correct evaluation of their harmonic interactions and analysis of the impact of their large-scale deployment on the overall network performance.

Thin films and multilayers are widely used in many applications, ranging from X-ray optics to microelectronic devices. In service, the X-ray optics elements are exposed to the X-ray beam, which heats up the structure resulting in the thermal deformations, and consequently in distortions of the reflective surface. In addition, the excessive heating may activate interdiffusion in the multilayers coatings and result in degradation of their reflective performance and even film cracking. Therefore, analysis of the thermally-induced deformations and stresses in the X-ray optical elements is important. The presented work is organized in two major parts. The first part examines formation of the peculiar periodic crack patterns observed in the thermally loaded Mo/Si multilayers. Film stress evolution during thermal cycling of the multilayers on Si substrate is analyzed. Results of the high-speed microscopic observations of crack propagation in the annealed Mo/Si multilayers are presented. The observations provide experimental evidence of the mechanism underlying formation of the periodic crack patterns. In the second part, thermal deformations and the resulting surface curvature changes in the X-ray optics elements are analyzed. Finite element modeling is used to assess the potential to thermally control curvature in the X-ray mirrors consisting of the Mo/Si multilayers on a Si substrate. Influence of heating due to the X-ray beam irradiation on thermal deformations in the X-ray mirror bonded to a thick substrate is analyzed in-depth. The detailed consideration includes analysis of the thermal and structural mechanics simulations. Based on simulations of different model configurations, influence of structural composition on thermal distortions of the optics elements is addressed. Results of this analysis can be used to mitigate distortions of the X-ray optics caused by the X-ray beam and provide basis for further studies of thermally controlling surface curvature in the optical elements.