Background. Digital simulations of physical scenarios are becoming increasingly feasible and driverless vehicles are playing an ever growing part in contemporary mining operations and have the potential to increase productivity and worker safety. Such vehicles require sensors to detect their environments, two of the most common types being LiDAR and RADAR sensors. LiDAR sensors are sensitive to atmospheric sensory pollutants whereas RADAR sensors typically are not, but more susceptible to echoes. As such, digital simulations of such sensors seem a viable alternative to reduce costs and risks in testing new hardware. Objectives. This thesis aims to adapt existing models for CPU simulated LiDAR and RADAR sensors to the GPU as well as to further develop their functionality. These models will then be evaluated against one another according to their performance and scalability. Methods. The stated goals are achieved through the method of literary research, implementation, experimentation, and gathering of data. This data will then be structured, analyzed, and discussed to reach conclusions about the developed software models. Results. The results show that GPU accelerated sensor models have a high overhead cost compared to CPU implementation which hampers performance for low intensity simulations. GPU implementations do however scale more efficiently in many scenarios and achieved speedups of up to 650 times when executed on DXR shaders with heavy workloads than equivalent tests on the CPU. Likewise, low workloads appear unfit for GPU accelerations as the overhead cost of streaming data and instructions between the CPU and GPU can take over twice as long as merely executing the same instructions on the CPU. Conclusions. In conclusion, GPU accelerated ray tracing sensor simulations can be highly efficient compared to CPU implementations when tracing large numbers of rays or simulating many concurrent sensors, but may result in increased execution time if the workload is not high enough to justify the additional overhead cost of CPU-to-GPU communication. / Bakgrund. Digitala simuleringar av fysikaliska fenomen blir mer och mer görbara och självgående fordon spelar en allt större roll i dagens gruvoperationer. Dessa fordon har möjligheten att öka produktiviteten för företaget och säkerheten för arbetarna. Sådana fordon behöver sensorer för att finna sig i sin omgivning och LiDAR- och RADAR-sensorer är två av de vanligaste alternativen. LiDAR-sensorer är känsliga för luftburna störningsmoment medan RADAR-sensorer är jämförelsevis opåverkade men känsliga mot ekon. Med detta i åtanke verkar digitala simuleringar av sådana sensorer vara ett lovande alternativ för att sänka kostnader och risker med att testa ny hårdvara. Syfte. Syftet med arbetet är att översätta befintliga CPU modeller för att simulera LiDAR- och RADAR-sensorer till GPU-programvara såväl som att vidareutveckla deras funktionalitet. Dessa modeller kommer sedan att bli utvärderade gentemot varandra vad gäller deras prestanda och skalbarhet. Metod. De givna målen kommer att uppfyllas via litterära studier, implementation, experimentering och datainsamling. Denna data kommer sedan att bli omstrukturerad, analyserad, diskuteras, och få slutsatser dragna kring sig gällande den mjukvara som utvecklats och framförts. Resultat. Resultaten visar att GPU-accelererade sensormodeller har en hög overheadkostnad jämfört med CPU implementationerna, vilket sänker deras relativa prestanda i lågintensitetssimuleringar. GPU-implementationerna har dock högre skalbarhet i många situationer och kan uppnå resultat upp till 650 gånger snabbare än originalkoden när de istället utförs via DXR-shaders med hög arbetsbörda. Likaså är framstår låg arbetsbörda som opassande scenarion för GPU accelererad mjukvara då exekveringstiden på CPUn kan komma att bli snabbare än overheadkostnaden av att strömma datan och instruktionerna till GPUn. Slutsatser. GPU accelererad raytracing med stora antal strålar eller sensorer som exekveras samtidigt ger upphov till mycket tidseffektiva simuleringar men kan leda till ökad total exekveringstid om arbetsbördan inte blir tillräckligt hög för att rättfärdiga overheadkostnaden av GPU-till-CPU kommunikation.

De nos jours, la problématique du bruit généré par les avions est devenue un point de développement important dans le domaine de l'aéronautique. C'est ainsi que de nombreuses études sont faites dans le domaine et une première approche consiste à modéliser de façon numérique ce bruit de manière à réduire de façon conséquente les coûts lors de la conception. C'est dans ce contexte qu'un motoriste a demandé à l'université de Sherbrooke, et plus particulièrement au groupe d'acoustique de l'Université de Sherbrooke (GAUS), de développer un outil de calcul de la propagation des ondes acoustiques dans les nacelles mais aussi pour l'étude des effets d'installation. Cet outil de prédiction leur permet de réaliser des études afin d'optimiser les traitements acoustiques (« liners »), la géométrie de ces nacelles pour des études portant sur l'intérieur de la nacelle et des études de positionnement des moteurs et de design pour les effets d'installation. L'objectif de ce projet de maîtrise était donc de poursuivre le travail réalisé par [gousset, 2011] sur l'utilisation d'une méthode de lancer de rayons pour l'étude des effets d'installation des moteurs d'avion. L'amélioration du code, sa rapidité, sa fiabilité et sa généralité étaient les objectifs principaux. Le code peut être utilisé avec des traitements acoustiques de surfaces («liners») et peut prendre en compte le phénomène de la diffraction par les arêtes et enfin peut être utilisé pour réaliser des études dans des environnements complexes tels que les nacelles d'avion. Le code développé fonctionne en 3D et procéde en 3 étapes : (1) Calcul des faisceaux initiaux (division d'une sphère, demi-sphère, maillage des surfaces de la géométrie) (2) Propagation des faisceaux dans l'environnement d'étude : calcul de toutes les caractéristiques des rayons convergents (amplitude, phase, nombre de réflexions, ...) (3) Reconstruction du champ de pression en un ou plusieurs points de l'espace à partir de rayons convergents (sommation des contributions de chaque rayon) : sommation cohérente. Le code (GA3DP) permet de prendre en compte les traitements de surface des parois, la directivité de la source, l'atténuation atmosphérique et la diffraction d'ordre 1. Le code a été validé en utilisant différentes méthodes telles que la méthode des sources-images, la méthode d'analyse modale ou encore la méthode des éléments finis de frontière. Un module Matlab a été créé spécialement pour l'étude des effets d'installation et intégré au code existant chez Pratt & Whitney Canada.

Internet-based and mobile technologies enable new ways of learning. They offer us new possibilities to access an enormous amount of knowledge at any time and everywhere. Among many advantages, the adaptations require a rethinking of our previous learning behaviour patterns and processes. The challenge for students is no longer to get access to information and knowledge, but to select the right one and to deal with the information and knowledge overflow. The aim of this research is to define, design and validate an advanced concept to support the contemporary learning processes. Therefore, the requirements for a new approach have been assessed, the available solutions from the related area of (personal) Knowledge Management have been investigated, and the weaknesses in the context of learning identified. The identified issues have been substantiated by university students via a quantitative survey. Besides several smaller aspects, knowledge fragmentation and the nescience of the knowledge formation process have been classified as the most critical ones. To overcome these problems, a methodological concept has been developed, and a corresponding technological design created. The chosen approach is an intelligent, independent intermediate layer, which traces the different steps our knowledge entities are going through. Based on personal and individual configurations, the system provides a comprehensive and overall observation of nearly all our knowledge work activities. It supports the building and accessing of the knowledge formation paths for every important knowledge unit, later path combination and the access to automatically generated versions of our work. Moreover, it helps the users not only to remember what they did, but also gives them some strong indications why they did it. This is achieved by combining different knowledge actions and looking at the influences they have on each other. The suggested concept has been critically proved and confirmed via a qualitative expert analysis and backed up by a quantitative survey among university students.

International Telemetering Conference Proceedings / October 21, 2002 / Town & Country Hotel and Conference Center, San Diego, California / The objective of the project is to continuously track a handheld device in an office, with centimeter accuracy in the three dimensions. A 3-D ray-tracing algorithm has been developed to simulate the impulse response of the indoor channel. The algorithm can evaluate the impulse response at multiple receiver locations. Non-linear optimization has been used to eliminate the need for multiple runs of simulation. The optimization program also significantly reduces the number of rays launched. The algorithm incorporates bandwidth effects on multipath resolution of the system.

Hyporheic water is thought to infiltrate at the head of a riffle which in turn is complemented by upwelling back to the stream at the tail of the riffle in a pool-riffle-pool (PRP) sequence. Heat tracing is a potentially useful method to characterize these hyporheic flow paths and quantify associated fluxes. Temperature was monitored within a PRP sequence for several days. Temperature in the hyporheic zone reflected the diel temperature change in the river but not uniformly. The observed thermal pattern exhibited deeper penetration of thermal oscillations below the head pool and shallower penetration below the tail pool. This pattern is consistent with the conceptual model of hyporheic exchange over a PRP sequence. One-dimensional analytical heat transport models were used at different points below the PRP sequence to estimate distributed vertical fluid fluxes. The calculated fluxes exhibit a trend that follows the expected distribution for a PRP sequence but modified for a losing stream. Deviation of both magnitude and distribution of fluxes from the conceptual ‘downwelling-to-upwelling’ model is partly due to the dominantly losing conditions at the study site but the trends are consistent with a losing stream undergoing hyporheic exchange. Violation of the assumptions in the analytical models most likely adds error to flux estimates. For this study, flux estimation methods using a temperature time series amplitude analysis more closely matched field measurements than phase methods. / text

It is important to track how a requirement changes throughout the software lifecycle. Each requirement should be validated during and at the end of each phase of the software lifecycle. It is common to build traceability matrices to demonstrate that requirements are satisfied by the design. Traceability matrices are needed in various tasks in the software development process. Unfortunately, developers and designers do not always build traceability matrices or maintain traceability matrices to the proper level of detail. Therefore, traceability matrices are often built after-the-fact. The generation of traceability matrices is a time consuming, error prone, and mundane process. Most of the times, the traceability matrices are built manually. Consider the case where an analyst is tasked to trace a high level requirement document to a lower level requirement specification. The analyst may have to look through M x N elements, where M and N are the number of high and low level requirements, respectively. There are not many tools available to assist the analysts in tracing unstructured textual artifacts and the very few tools that are available require enormous pre-processing. The prime objective of this work was to dynamically generate traceability links for unstructured textual artifacts using information retrieval (IR) methods. Given a user query and a document collection, IR methods identify all the documents that match the query. A closer observation of the requirements tracing process reveals the fact that it can be stated as a recursive IR problem. The main goals of this work were to solve the requirements traceability problem using IR methods and to improve the accuracy of the traceability links generated while best utilizing the analysts time. This work looked into adopting different IR methods and using user feedback to improve the traceability links generated. It also applied wrinkles such as filtering to the original IR methods. It also analyzed using a voting mechanism to select the traceability links identified by different IR methods. Finally, the IR methods were evaluated using six datasets. The results showed that automating requirements tracing process using IR methods helped save analysts time and generate good quality traceability matrices.

Ghost images are caused by the inter-reflections of light from optical surfaces that have transmittances less than unity. Ghosts can reduce contrast, provide misleading information, and if severe can veil parts of the nominal image. This dissertation develops several methodologies to simulate ghost effects arising from an even number of light reflections between the surfaces of multi-element lens systems. We present an algorithm to generate the ghost layout that is generated by two, four and up to N (even) reflections. For each possible ghost layout, paraxial ray tracing is performed to calculate the locations of the Gaussian cardinal points, the locations and diameters of the ghost entrance and exit pupils, the locations and diameters of the ghost entrance and exit windows, and the ghost chief and marginal ray heights and angles at each surface in the ghost layout. The paraxial ray trace data is used to estimate the fourth order ghost aberration coefficients. Petzval, tangential, and sagittal ghost image surfaces are introduced. Potential ghosts are formed at the intersection points between the ghost image surfaces and the Gaussian nominal image plane. Paraxial radiometric methodology is developed to estimate the ghost irradiance point spread function at the nominal image plane. Contrast reduction by ghosts can cause a reduction in the depth of field, and a simulation model and experimental technique that can be used to measure the depth of field is presented. Finally, ghost simulation examples are provided and discussed.

An investigation is presented into methods of characterising cirrus ice crystals from in-situ light scattering data. A database of scattering patterns from modelled crystals was created using the Ray Tracing with Diffraction on Facets (RTDF) model from the University of Hertfordshire, to which experimental and modelled data was fitted. Experimental data was gathered in the form of scattering patterns from ice analogue crystals with similar optical properties and hexagonal symmetry to ice, yet stable at room temperature. A laboratory rig is described which images scattering patterns from single particles while allowing precise control over the orientation of the particle with respect to the incident beam. Images of scattering patterns were captured and compared to patterns from modelled crystals with similar geometry. Methods for introducing particles en-masse and individually to the Small Ice Detector (SID) instruments are discussed, with particular emphasis on the calibration of the gain of the SID-2 instrument. The variation in gain between detector elements is found to be significant, variable over the life of the detector, and different for different detectors. Fitting was performed by comparison of test scattering patterns (either modelled or experimental) to the reference database. Representation of the two dimensional scattering patterns by asymmetry factor, moment invariants, azimuthal intensity patterns (AIP) and the Fourier transform of the AIP are compared for fitting accuracy. Direct comparison of the AIP is found to be the most accurate method. Increased resolution of the AIP is shown to improve the fitting substantially. Case studies are presented for the fitting of two ice analogue crystals to the modelled database. Fitting accuracy is found to be negatively influenced by small amounts of surface roughness and detail not currently considered by the RTDF model. Fitting of in-situ data gathered by the SID-3 instrument during the HALO 02 campaign at the AIDA cloud chamber in Germany is presented and discussed. Saturation of detector pixels is shown to affect pattern fitting. In-flight operation of the instrument involves the variation of gain of the whole detector (as opposed to individual elements) in order to obtain unsaturated images of both large and small particles.

The central tenet of tracing theory is that in certain circumstances it is possible to show that one asset stands in the place of another, such that any claims in relation to the original asset can be transmitted to its substitute. Since at least 2001 academic and judicial orthodoxy has been that this is done by following the path of value from one asset to the other, and can be aided in more complex cases by the application of evidential rules or presumptions. These ideas are at the heart of existing accounts of proprietary claims against trustees who deal with trust assets without authority, and personal and proprietary claims against strangers to the trust. They are also at the heart of calls to 'unify' the rules of tracing at law and in equity, removing existing distinctions drawn between claimants who are owed fiduciary duties and those who are not. In this thesis it is argued that there are no independent processes of following and identifying value, and that the language of 'tracing value' has lent the appearance of neutrality and conceptual unity to disparate heads of fiduciary and non-fiduciary liability. Most importantly, it has led to the assumption that in any case in which a claimant can demonstrate that a series of transactions links some right in the defendant’s hands with a right previously held by or for the claimant, the claimant can claim that right. In this thesis it is argued that far from creating an arbitrary practical obstacle for claimants seeking to trace and locate value, the fiduciary relationship is at the heart of the justification for any claim that exists to a new right in the hands of someone else.

The aim of this paper is to investigate the link between internal and external conflict of states in the field of International Relations. More specifically, it is a critique of the Diversionary War theory, which argues that political leaders can instigate foreign conflict to divert the attention from domestic issues in order to secure their political positions. This paper will test an alternative approach to the Diversionary War theory called the Diversionary Peace theory, which inverts the logic of the original theory. It argues that leaders facing domestic strife have incentives to cooperate with other states in order to deal with the internal problems in a more cost effective way. Using process tracing methodology, the Diversionary Peace theory is applied to Turkey from 1984-1999, to understand how the Kurdish issue as a source of domestic conflict in Turkey affected the Turkish-Syrian relations. The Diversionary Peace Theory would assume that as the Kurdish conflict escalates at the domestic level, Turkey would be inclined to give concessions to Syria to deescalate conflict at the international level. This paper proves otherwise: as the domestic conflict escalates, relations actually deteriorate and cooperation becomes less likely. Therefore, it is both a critique of the Diversionary War theory and the Diversionary Peace theory. The main interpretation of the findings is that the theory is not applicable to those cases where the boundaries between domestic and international realms are too porous as in the case of the Kurdish politics. When the domestic conflict and international dispute is interlinked, as in this case, I argue that cooperation might not be possible. Future reseachers in the area are advised to pay attention to whether the domestic factor and the international factor are interlinked, how the level of domestic conflict affects foreign relations and the impact of domestic audience costs.