Ray tracing has for a long time been used to create photo realistic images, but due to complex calculations done per pixel and slow hardware, the time to render a frame has been counted in hours or even days and this can be drawback if a change of a scene cannot be seen instantly. When ray tracing a frame takes less than a second to render we call it “real time ray tracing” or “interactive ray tracing” and many solutions have been developed and some involves distributing the computation to different computers interconnected in a very fast network (100 Mbit or higher). There are some drawbacks with this approach because most people do not have more than one computer and if they have, the computers are most likely not connected to each other. Since the hardware of today is fast enough to render a pretty complex image within minutes it should be possible to achieve real time ray tracing by combining many different methods that has been developed and reduce the render time. This work will examine what has to be sacrificed in image quality and complexity of static scenes, in order to achieve real time frame rate with ray tracing on a single computer. Some of the methods that will be covered in this work are frame optimizations, secondary rays optimization, hierarchies, culling, shadow caching, and sub sampling.

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The 2013 meeting of the Intergovernmental Panel on Climate Change concluded that the coupling of clouds to the Earth's climate is one of the biggest uncertainties faced in predicting climate change today. Cirrus clouds are of particular interest because the extensive variability in particle size, shape and complexity poses a number of challenges in the accurate modelling of optical properties. The dependence of the single-scattering properties on particle shape demand accurate representation of the crystal geometries in scattering models, geometries which can vary from simple hexagonal prisms to complex multi-branched aggregates. This work, presented as a series of papers, uses laboratory studies to investigate the single scattering properties of ice crystals. Of particular focus here are columns with internal cavities. The first paper investigates the phase function, P11 and asymmetry parameter, g of varying crystal habits, whilst the second paper focuses on polarised scattering. One of the main findings is the difference in internal structure between hollow columns grown at warmer temperatures (-7 degrees C) and those grown at colder temperatures (-30 degrees C). Measurements were used to create new particle geometries for use in scattering models. The third paper makes use of findings from papers 1 & 2 to create an optical parametrization for cirrus, utilizing the new particle geometry.

The thesis delves into the area of troubleshooting procedures, an interesting areafor industry. Many products in industry tend to be complex, which in turn makestroubleshooting procedures trickier. A fast and efficient repair process is oftendesired, since customers want the product to be repaired as fast as possible. The purpose of a troubleshooting procedure is to find a fault in a broken product,and to choose proper repair actions in a workshop. Such a procedure can besimplified by diagnosis tools, for example software programs that make faultconclusions based on fault codes. These tools can make such conclusions withthe help of algorithms, i.e. fault tracing algorithms. Before a product release, it is hard to specify all faults and connections in the system.New unknown fault cases are likely to arise after release, and somehow thisneed to be taken into account in the troubleshooting scenario. The troubleshootingprocedure can be made more robust, if new data could be easily incorporatedin the current structure. This work seek to answer how new data can be incorporatedin trouble shooting procedures. A good and reliable fault tracing algorithm is essential in the process of findingfaults and repair actions, which is the reason behind the focus of this thesis. Thepresented problem asks how a fault can be identified from fault codes and symptoms,in order to recommend suitable repair actions. Therefore, the problem isdivided into two parts, finding the fault and recommending repair actions. Inthe first part, three candidate algorithms for finding the faults are investigated,namely Bayesian networks, neural networks, and a method called matrix correlationinspired from latent semantic indexing. The investigation is done by trainingeach algorithm with data, and evaluating the results. The second part consists ofone method proposal for repair action recommendations and one example. Thetheoretical investigation is based on the Servo unit steering (SUS), which residein the IPS system of Volvo Penta. The primary contribution of the thesis is the evaluation of three different algorithmsand a proposal of one strategy to recommend suitable repair actions.In this study Bayesian networks are found to conform well with the desired attributes,which in turn lead to the conclusion that Bayesian networks is well suited for this problem.

Context. Reaching photo realistic results when rendering 3D graphics in real-time is a hard computational task. Ray-tracing gives results close to this but is too expensive to be run at real-time frame rates. On the other hand rasterized methods such as deferred rendering are able to keep the tight time constraints with the support of modern hardware. Objectives. The basic objective is to merge deferred rendering and ray-tracing into one rasterized pipeline for dynamic scenes. In the thesis the proposed method is explained and compared to the methods it merges. Image quality, execution time and VRAM usage impact are investigated. Methods. The proposed method uses deferred rendering to render the result of the primary rays. Some pixels are marked, based on material properties for further rendering with ray-tracing. Only reflections are presented in the thesis but it has been proven that other global illumination effects can be implemented in the ray-tracing framework used. Results and Conclusions. The hybrid method is proved through experiments to be between 2.49 to 4.19 times faster than pure ray-tracing in the proposed pipeline. For smaller scenes it can be run at frame rates close to real-time, but, for larger scenes such as the Crytek Sponza scene the real-time feeling is lost. However, interactivity is never lost. It is also proved that a simple adjustment to the original framework can save almost 2/3 of the memory spent on A-buffers. Image comparisons prove that the technique can compete with offline ray tracers in terms of image quality.

The testing technique with high dynamic range is required to meet the measurement of refractive wavefront with large distortion from test refractive surface. A general deflectometric method based on reverse Hartmann test is proposed to test refractive surfaces. Ray tracing of the modeled testing system is performed to reconstruct the refractive wavefront from test surface, in which computer-aided optimization of system geometry is performed to calibrate the geometrical error. For the refractive wavefront error with RMS 255 mu m, the testing precision better than 0.5 mu m is achieved.

The heart arises from two sources of mesoderm progenitors, the first (FHF) and the second heart field (SHF) progenitors. Mesp1 has been proposed to mark the most primitive multipotent cardiac progenitors (MCPs) common for both heart fields. However, it remains unclear whether at the single cell level, Mesp1 progenitors represent a common progenitor for the FHF and SHF. Using mosaic tracing and inducible clonal analysis with a multicolor reporter strategy, we investigated the contribution of Mesp1 cardiovascular progenitors in a temporally controlled manner during the early gastrulation. Our data indicated that the myocardium derives from ~250 Mesp1 expressing cardiac progenitors born during gastrulation. Temporal analysis of clonally labeled Mesp1 cells revealed the existence of temporally distinct populations of Mesp1 progenitors that are restricted to either the FHF or the SHF. FHF progenitors were unipotent, while SHF progenitors, were either uni- or bipotent. Microarray and single cell RT-PCR analysis of Mesp1 progenitors revealed the existence of molecularly distinct populations of Mesp1 progenitors, consistent with their lineage and regional contribution. Moreover biophysical analysis of clonal data revealed that, despite arising at different time points and contributing to different heart regions, the temporally distinct cardiac progenitors present very similar clonal dynamics. Altogether, these results provide insights into the number of cardiac progenitors and their mode of growth. Moreover they provide evidence that heart development arises from distinct populations of unipotent and bipotent cardiac progenitors expressing Mesp1 independently at different time points during gastrulation. Our data reveal that the regional segregation and lineage restriction of cardiac progenitors occurs very early during embryonic development. / Doctorat en Sciences biomédicales et pharmaceutiques (Médecine) / info:eu-repo/semantics/nonPublished

This thesis explores Voxel Cone Tracing as a possible Global Illumination solutionon mobile devices.The rapid increase of performance on low-power graphics processors hasmade a big impact. More advanced computer graphics algorithms are now possi-ble on a new range of devices. One category of such algorithms is Global Illumi-nation, which calculates realistic lighting in rendered scenes. The combinationof advanced graphics and portability is of special interest to implement in newtechnologies like Virtual Reality.The result of this thesis shows that while possible to implement a state of theart Global Illumination algorithm, the performance of mobile Graphics Process-ing Units is still not enough to make it usable in real-time.

Magister Public Health - MPH / Background: STIs are of major public health concern in developing countries, not least because they facilitate transmission of HIV, but also because they are important causes of mortality and morbidity among African populations, resulting in, among other things, adverse birth outcomes, neonatal and infant infections, ectopic pregnancy, anogenital cancer,infertility, pelvic inflammatory disease, and death. Thus, effective treatment needs to be prompt and accurate to control the spread, and morbidity and mortality of STIs. Even though syndromic approach to the management of STIs is effective, most evaluations have focused on syndromic STI management within STI clinics as opposed to research studies. Partner notification is an integral component of the syndromic approach and is aimed at preventing onward transmission of infection as well as re-infection. It includes informing sexual partners of infected people of their exposure, administering presumptive treatment, and providing advice about the prevention of future infection.Methods: This is a cross sectional descriptive study based on a retrospective review of STI data of study participants in KICoS aged 18 to 34 years. A non probability convenience sampling method was used to recruit study participants. A total of 1,277 participants were prescreened into KICoS of whom 847 were enrolled into this study. Data was collected using CAPI and ACASI questionnaires as well as Teleforms which was analysed in SAS for windows 9.1. Results: Syndromic prevalence of STIs was 5.7% while the aetiological prevalence was 32.8%.Risk factors to STI acquisition included, being female, having multiple sexual partners,having lower than tertiary education, using recreational drugs and being HIV. Agreement between the interviewing methods as well between the syndromic and laboratory diagnosis ranged from fair to substantial. This was also true for the agreement between laboratory and CAPI as well as between the laboratory and ACASI. Sensitivity was generally low while specificity was high. Uptake of contact tracing cards was high though with very low uptake of contact treatment with only 2.1% and 0.4% partners of the syndromically and aetiologically diagnosed participants coming for treatment.Conclusions: STI is a problem in this community and thus there should be more emphasis on risk reduction messages in patient education to mitigate the spread of STIs. The performance of syndromic management was very poor against the aetiological diagnosis thus there needs to further review the use of syndromic diagnosis of STIs in research settings. Partner tracing needs to be intensified since there was very poor partner treatment even with high uptake of contact cards.Acknowledgements: This study would have not been what it was without the immense support I received from many individuals all of whom cannot be mentioned here. I would however want to thank the Dr Wairimu Chege (Principal Investigator, KICoS) for her inspiration and encouragement. I would also like to thank my supervisor, Ernie Kunneke for going through this study with me repeated times including on a ride to the airport. On the same note I would also like to thank my lecturers and student administrators at the SOPH. My gratitude also goes to my colleagues Richard Ndivo, Sherri Pals and Eleanor McLellan-Lemal for all the support they accorded me throughout this research.I would also want to give my heartfelt gratitude to my family. My daughter Akinyi who used to type with me at night, her mother Auma for understanding my late nights up and finally to my Parents Mr and Mrs Gideon and Monica Otieno for understanding the importance of education and taking me to school through all the difficulties. Last but not least I would like to express my gratitude to the almighty God for having seen me through this process.

Master's Thesis is focused on urban public transport, specifically on tram network in Prague. The first part introduces the transport, with focus on personal transport, its transport routes and means of transport. Next part describes Prague tram network, its history from the very beginning of the first tram lines till present and that is broken up into the detail on particular tram lines which are now operated. Further the transportation survey of Prague integrated transport from the year 2016 is introduced. The information from this survey are consequently used for two different drafts on solution of tram network. The first draft suggests tracing the lines with the biggest possible amount of lines while the second one suggests tracing with as many direct offers as possible. The last part of the thesis compares and valuates both suggested drafts.