In this report a radar model is modeled and implemented in a simulation framework called Flames. The focus is to investigate how and if electromagnetic waves emitted from the radar antenna can be simulated by different methods and how these methods can be implemented to work in real-time simulations. The radar model developed in this report is based on ray tracing and ray propagation techniques developed by the author. The model considers varying refractive indices that describes both standard atmospheres and atmospheres where ducting occur. Preparatory studies are also made to model ground reflection by ray tracing techniques. Other simulation techniques, such as the Finite-Difference Time-Domain method and the Split-Step Parabolic Equation method, are furthermore considered for radar simulation applications. The results show that ray tracing in conjunction with geometrical optics is a valid method for simulating electromagnetic waves in simple atmosphere models.

X-ray and neutron computed tomography (CT) have been used successfully for the non-destructive imaging of artifact in art conservation. These applications range from object investigations to the use of micro-focus CT for experimental studies. While there is precedent for the use of CT in art conservation, the method is still limited in application partially due to restricted access to facilities and the high cost of producing publishable results. The purpose of this study was to identify alternative CT methods including the use of different radiation sources and industrial imaging system. Both investigations of the use of low-flux neutron CT at the Royal Military College in Kingston compared to high-flux neutron CT at the Advanced Neutron Tomography And Radiography Experimental System (ANTARES) at FRM-II in Garching, Munich and the use of megavoltage gamma ray computed tomography at Kingston General Hospital in Kingston successfully imaged the corroded metal artifacts. The artifacts investigated were from the Diniacopoulos Collection at Queen’s University and were underwater concretions of L’Anse aux Bouleaux provided by Parks Canada. This study also evaluated the Xradia XCT-400 for comparison to similar systems used in conservation. This evaluation also provided successful images of corroded metal coins from the Diniacopoulos Collection for use in identification. To address the issue of cost prohibitive image analysis programs, a workflow using the open-source software programs ImageVis3D, 3DSlicer and ImageJ was developed. This workflow would enable researchers and conservators to produce publishable images and analyze the information in the CT data sets. Additionally, this workflow addresses some common research questions that might arise during investigations that would guide conservators in optimizing their imaging parameters and image analysis. The combination of the alternative radiation sources and the open-source workflow allows for greater accessibility of CT for conservators and researchers. While the preliminary success of the study is promising, more research is needed to optimize the scanning parameters and image analysis through the use of phantoms and comparisons to traditional investigative methods in conservation. / Thesis (Master, Art Conservation) -- Queen's University, 2011-09-09 14:25:25.219

No description available.

Thesis (Ph.D)--University of Adelaide, 1955. / Typewritten copy.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Astrophysical events that evolve on short timescales (from milliseconds to years) are widely referred as transient events. In many cases, transient events are explosions or mergers of astrophysical objects that emit particles of all energies. This thesis focuses on very-high-energy (VHE; 100 GeV to 100 TeV) gamma rays, observed by the VERITAS telescope, to understand two types of transients, superluminous supernovae (SLSNe) and classical novae. In the first part, the background physics and technical approach of an imaging atmospheric Cherenkov technique deployed by VERITAS is reviewed in depth, including the analysis pipeline of VERITAS data, from camera data reduction to high level analysis output. In addition to supporting the ongoing work at VERITAS, the second part of this thesis describes the extensive effort to develop, commission and align the optical system of the prototype Schwarzschild-Couder telescope, also located at the VERITAS observatory. This new telescope provides an wider field of view and higher angular resolution compared with the conventional IACT design of current telescopes, and will join the next generation of VHE telescopes in the Cherenkov Telescope Array (CTA) project currently in development. The observation and analysis of two SLSNe is performed, on SN 2015bn and SN 2017egm, with both VERITAS and Fermi-LAT telescopes. The upper limit is reported on both events and is compared to a simple and a self-consistent model for parameter estimation. In addition, a population of sources were analyzed to estimate the future detection potential of new SLSNe with several gamma-ray observatories. Finally, the observation and analysis of several novae were performed. These sources were observed with VERITAS and Fermi-LAT. The observation of Nova Herculis 2021 is noteworthy in that the overlap of both observations may constrain the cutoff energy of the nova spectral model, providing a estimate for the maximum energy of the accelerated particles in the nova’s shock region.

Advances in hardware acceleration has resulted in development of a variety of hardware accelerated ray tracing libraries. The purpose of this bachelor thesis is to investigate if a simple ray tracer, based on a hardware accelerated ray tracing library, can achieve acceptable frame rates in rendering simple 3D game-related environments. Games are often associated with fast rasterization-based rendering techniques, but rasterization is limited where instead ray tracing holds many advantages. Background research was done to gain knowledge about related work, state-of-the-art in ray tracing and available hardware accelerated libraries. By using a method similar to Kanban and Scrum [36], the implementation was split up into different tasks, prioritizing the tasks of implementing basic functionalities of a ray tracer. A simple ray tracer was implemented based on the chosen library Embree, a framework developed at Intel Corporation. Results show that the scenes rendered in lower resolutions (800 x 600) are good candidates for having a stable frame rate of 30 FPS, which is not enough in order to render a real game. The standard of games today require high resolution (full HD 1920 x 1080) and complex scenes. Earlier studies show that Embree has potential of higher performance and looking back the performance of real-time ray tracing has improved, but is still limited to low resolutions and simple lighting and shading models. / Framsteg inom hårdvaruacceleration har resulterat i att en rad olika hårdvaruaccelererade bibliotek för strålföljning utvecklats. Syftet med denna kandidat-uppsats är att undersöka om en enkel strålföljare, baserad på ett hårdvaruaccelererat bibliotek för strålföljning, kan uppnå acceptabla bildfrekvenser vid rendering av enkla spel-relaterade miljöer i 3D. Datorspel förknippas ofta med snabba renderingstekniker. Rasteriseringsalgoritmen är dock begränsad där istället strålföljning har många fördelar. En litteraturstudie gjordes för att få kunskap om relaterade arbeten, state-of-the-art i strålföljning och tillgängliga hårdvaruaccelererade bibliotek. Genom att använda en metod som kan liknas vid Kanban och Scrum [36], blev implementationen uppdelad i olika uppgifter (eng. tasks), där implementationen av grundläggande funktioner av en strålföljare hade högsta prioritet. En enkel strålföljare implementerades med det valda biblioteket Embree, ett ramverk som utvecklas hos Intel Corporation. Resultaten visar att scenerna som renderas med lägre upplösningar (800 x 600) är goda kandidater för att uppnå en stabil bildfrekvens med 30 bilder per sekund (eng. frames per second), vilket inte är tillräckligt för att rendera ett riktigt spel. Standarden hos spel idag kräver hög upplösning (full HD 1920 x 1080) och komplexa scener. Tidigare studier visar att Embree har potential för högre prestanda och tidigare resultat visar att prestandan av interaktiv strålföljning har förbättrats, men att den fortfarande är begränsad till låga upplösningar och enklare belysningsmodeller.

The ROSAT spacecraft is due for launch in June 1990. On board will be an X-Ray Telescope (XRT) and an XUV Wide Field Camera (WFC). The XRT will perform the first ever imaging all sky survey in the 0.1 keV- 2.0 keV wave-band. This will be complemented by the first all sky survey in the 0.062 keV - 0.21 keV wave-band using the WFC. A scientific simulator has been developed to assist the WFC mission in the following areas: 1. Production of representative telemetry to develop and test the ROSAT WFC ground system software. 2. Determination of optimum parameters for several WFC firmware and hardware features. 3. Evaluation of background radiation effects on operational and astrophysical aspects of the WFC mission. The modelling and simulation of the performance aspects of the WFC telescope and its interaction with the predicted environment is described here. The complete model has been implemented as a user orientated software package and can be run to produce scientific telemetry and other simulated output that interface with the ROSAT WFC ground system software. The results of the simulator provide essential foresight into the following: The efficacy of image analysis software. The efficiency of in-orbit WFC low energy (50 keV) electron rejection. Prediction of all sky exposure coverage, the background environment, and minimum source sensitivity.

X-Ray emission techniques have been developed for the analysis of unusual and difficult samples that cannot be analyzed by conventional analytical techniques. Three X-ray techniques have been investigated, including radioisotope-induced X-ray fluorescence (RXRF), proton-induced X-ray emission (PIXE) and high resolution PIXE. Low flux radioisotope X-ray sources have been used to non-destructively characterize the elements present in photographic papers and emulsions. The information obtained has proven valuable for cataloging and preserving photographic prints of historical significance. Radioisotope X-ray sources have also been used in the development of low-cost, portable instrumentation useful for quantitating a variety of toxicological samples, including urine and feces samples to determine the elimination rates of X-ray contrast media containing dysprosium. The PIXE technique has been applied to the analysis of forensic samples, including bullet lead, tissue fragments and thin metal coatings, and has been compared with other non-destructive methods of analysis. Sample preparation techniques and analytical procedures have been developed for general, thin target, quantitative PIXE analysis. These procedures were applied to the analysis of five NBS standard reference materials, and to the analysis of deep-sea ferromanganese nodules. A high resolution (2 eV) PIXE system has been developed to aid in the deconvolution of overlapping X-ray peaks encountered in conventional PIXE spectra. This system has been applied to the measurement of chemical shifts in the X-ray emisson spectra of transition metal compounds.

No description available.