Global shutter pixels are indispensable for applications wherein the minimisation of motion artefacts is of critical importance. However, these pixels are more complex than the common rolling shutter type pixels and require some form of per-pixel storage. They are almost invariably reliant upon metal light shielding in order to protect their in-pixel memory nodes and this prevents them from taking advantage of some of the latest developments in CMOS image sensor technology. Backside-illumination is the most prominent example of such a technology. The greater sensitivity afforded by the reduced optical stack height is indispensable for many applications, particularly in the mobile market where form factor and power consumption are constrained. The design challenge is to exploit these advantages offered by backside-illumination without making use of metal shielding of the per-pixel memory. The research in this thesis covers the design, implementation and characterisation of a back-illuminated voltage-domain global shutter pixel. The pixel architecture is a novel 10 transistor-per-pixel architecture with dual independent in-pixel storage nodes. Beginning with the pixel architecture, the design is developed through TCAD-driven photodiode and pixel layout co-optimisation. The behaviour of pixels with differential parasitic light sensitivity (PLS) behaviour is analysed in greater detail than previously reported and a prediction model is developed based upon this. The 10T pixel is characterised and found to have excellent PLS of -73:5 dB native and -82:5 dB differential PLS at 940 nm. The dual in-pixel storage enables the pixel to operate either in a low noise correlated double sampling mode with differential PLS, or in an exposure-bracketed high dynamic range imaging (HDR) mode. This HDR mode is successfully demonstrated and yields substantial enhancement of the pixel dynamic range.

Orientador: Marco Antônio Rodrigues Fernandes / Resumo: O uso de fontes de radiações ionizantes tem sido cada vez mais presente nas diversas atividades técnico-científicas. Os cuidados e os benefícios da prática já são bastante conhecidos e difundidos na área da medicina de humanos, tanto no campo do diagnóstico quanto da terapia. Na área da medicina veterinária, a radioterapia vem ganhando espaço, no entanto, o uso de feixes de radiações ionizantes exige o conhecimento de legislações específicas sobre proteção radiológica e a atuação de profissionais altamente especializados. O uso seguro das práticas de radioterapia requer o dimensionamento de blindagens para a correta proteção dos profissionais, dos pacientes e do meio ambiente. Neste trabalho foram realizados cálculos de blindagem para dimensionamento das espessuras das barreiras de proteção à radiação para uma sala de radioterapia adequada para o uso de um equipamento de teleterapia de ortovoltagem, destinado para procedimentos de radioterapia em medicina veterinária. Foram também realizados estudos para o dimensionamento das mesmas barreiras e condições de trabalho para o uso em braquiterapia de alta e de baixa taxa de dose (BATD e BBTD), para diferentes fontes radioativas. Foram ainda desenvolvidos os cálculos para dimensionamento das paredes de um espaço localizado no interior do canil situado no prédio da Faculdade de Medicina Veterinária e Zootecnia da Unesp de Botucatu (FMVZ), visando sua adequação para a realização de procedimentos de braquiterapia de baixa de dose. Os... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The use of ionizing radiation surces has increased in various technical-scientific activities. The care and benefits of the practice are already well known and widespread in human medicine, both in the field of diagnosis and therapy. In the area of veterinary medicine, radiotherapy has been gaining space, however, the use of ionizing radiation beams requires the knowledge of specific legislation on radiolprotection and specialized professionals. The safe use of radiotherapy practices requires the design of shielding for the correct protection of professionals, patients and the environment. The present study calculated the dimension and thickness of the radiation protection barriers to a radiotherapy room suitable for the use of orthovoltage teletherapy equipment, destined for radiotherapy procedures in veterinary medicine. Studies were also carried out for the design of the same barriers and working conditions for use in high and low dose rate brachytherapy (HDR and LDR) for different radioactive sources. The calculations for dimensioning the walls of a dog kennel located in the school of Veterinary Medicine and Animal Science, Unesp Botucatu (FMVZ), were also developed, aiming at their adequacy for the accomplishment of dose rate brachytherapy procedures. The results showed that the thicknesses calculated for the walls of the orthovoltage radiotherapy room are sufficient for the shielding of the radiations from the sources of high and low dose rate brachytherapy. / Mestre

Shadow shielding is a novel and practical concept for waste heat rejection from lunar surface spacecraft systems. A shadow shield is a light shield that shades the radiator from parasitic thermal radiation emanating from the sun or lunar surface. Radiator size and mass can reduce if the radiator is not required to account for parasitic heat loads in addition to system energy rejection requirements. The lunar thermal environment can be very harsh towards radiative heat rejection. Parasitic heat loads force the radiator to expand in size and mass to compensate. On the Moon, there are three types: surface infrared, solar insulation, and albedo. This thesis tests shadow shielding geometry and its effect on the radiator and nuclear reactor in a reactor-powered Carnot heat engine. Due to the nature of cooling by radiative heat transfer, the maximum shaft work a Carnot system can produce and the minimal required radiator area occurs when the Carnot efficiency is 25%. First, a case for shadow shielding is made using an isothermal, control radiator model in Thermal Desktop. Six radiator temperatures and three latitudes are considered in the tests. Test variables in this section include radiator shapes and shade geometry. The simulations found that shadow shielding is best suited for a low-temperature radiator at the lunar equator. Optimized parabolic shade geometry includes a focus right above or at the top of the radiator and full to three-quarters shade height. The most useful rectangular radiator shape for shadow shielding is that which has a low height and long width. All simulations were conducted using a shade with a 10 kg/m2 area mass. A sensitivity study was conducted for different shade area masses using high and low values found in the literature. The shade is the most useful when the shade's area mass is less than or equal to that of the radiator. If the shade mass is below this threshold, the shade would be applicable to all radiator temperatures tested. Optimized shade and radiator geometry results were then factored into a second model where the radiator is comprised of heat pipes which is similar to radiators from actual system designs. Further simulations were conducted implementing the SAFE-4001 fast fission nuclear reactor design. The study found that shadow shielding allowed the system to use a low-temperature radiator where other configurations were not viable because shadow shielding drastically improves radiative heat transfer from the radiator, but at the consequence of raising radiator mass.

No description available.

Neben der konventionellen Digitalen Subtraktions-Angiografie (DSA) werden insbesondere seit Einführung der Angiografiesysteme mit Flachdetektor-Technologie zunehmend auch Rotationsangiografien und DYNA-CTs durchgeführt. Ziel der Studie ist die Bestimmung der Strahlenexposition für den Untersucher bei DSA-Serien im Vergleich zu Rotationsangiografien an einem biplanen Angiografiesystem unter Berücksichtigung gerätetechnischer Strahlenschutzvorrichtungen. Die Untersuchung erfolgte an einem biplanen Angiographiesystem mit Flachdetektor-Technologie (AxiomArtis dBA, Siemens). Die Strahlenexposition wurde als Ortsdosis in Höhe der Augen, Schilddrüse und Gonaden eines stehenden Untersuchers mit dem Dosimeter UMO LB 123 (Berthold) bestimmt. Alle Messungen wurden sowohl mit als auch ohne deckengeführtes Strahlenschutzschild und Unterkörperschutz mit Aufsatz durchgeführt. Die Messorte wurden in unterschiedlichen Abständen und Winkeln zum Isozentrum gewählt. Der Patient wurde durch ein Alderson-Phantom simuliert. Die Messergebnisse ergaben eine 90%ige Reduzierung der Strahlenexposition des Untersuchers durch die Strahlenschutzvorrichtung am Tisch. Für einen wirksamen Gonadenschutz ist der Aufsatz zum Unterkörperschutz unverzichtbar. Die optimale Schutzwirkung ist nur an der Position des Untersuchers nachweisbar; Personal direkt neben dem Untersucher ist einer bis zu 10mal größeren Strahlenexposition ausgesetzt. Die Strahlenexposition des Untersuchers ist bei der Durchführung einer Rotationsangiografie (8s DS H) auch unter Berücksichtigung aller gerätetechnischen Strahlenschutzvorrichtungen 9 bis 10fach höher, verglichen zu einer DSA-Serie in Standardprojektionen (6s, 3 Bilder/s). Die Strahlenexposition des Untersuchers an einem biplanen Angiografiesystem kann durch gerätetechnische Strahlenschutzvorrichtungen erheblich reduziert werden. Hochdosisprotokolle für Rotationsangiografien sollten auf ihre Notwendigkeit überprüft werden.

This thesis is concerned with applications of modern solid-state NMR spectroscopy. Investigations of three quite different types are undertaken, each of which attempt to advance knowledge in the fields of chemistry and NMR. The goal of each project is to obtain insight into the effects of chemical environment, in particular bonding, on the NMR observables. Carbon-13 and nitrogen-15 solid-state nuclear magnetic resonance has been used to study solid samples containing the dicyanoaurate(I) anion, [Au(CN)2]-, with n-butylammonium, potassium, and thallium counterions. Differences in Au-Tl metallophilic bonding are shown to cause a difference in the isotropic cyanide carbon-13 chemical shift of up to 15.7 ppm, while differences in Au-Au aurophilic bonding are found to be responsible for a change of up to 5.9 ppm. Disordered polymeric gold(I) monocyanide was also investigated, and a range of 7+-2% to 25+-5% of the AuCN chains are found to be "slipped" instead of aligned with the neighbouring chains at the metal position. An investigation of the chemical shift tensors of the 13C-labelled carbons in solid samples of Ph13C≡13CPh and (η2-Ph13C≡13CPh)Pt(PPh3)2·(C6H6) has also been carried out. Coordination of diphenylacetylene to platinum causes a change in the 13C chemical shift tensor orientation and a net increase in the isotropic chemical shift. The carbon chemical shift tensors in the platinum complex bear a striking similarity to those of the alkenyl-carbons in trans-Ph(H)C=C(H)Ph, and a theoretical discussion of these observations is presented. Each of the fundamental NMR interaction tensors (σ, J, D and V) may be decomposed into isotropic, symmetric, and antisymmetric components. Observations of all theoretically allowed components other than the antisymmetric portion of J (Janti) have previously been published. Andrew and Farnell's theory (Mol. Phys. 15, 157 (1968)) for the effects of Janti on NMR spectra has been extended to powdered samples, and methods for analyzing the resultant line shapes have been determined. Finally, the first reported experimental attempts to measure Janti are presented, and experimental proof that no elements of Janti(119Sn,119Sn) in hexa(p-tolyl)ditin are larger than 2900 Hz is given.

Thesis (MScEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: This work discusses the design of a 3-axis Geomagnetometer SQUID System (GSS), in which HTS SQUIDs are used unshielded. The initial GSS installed at SANSA was fully operable, however the LN2 evaporation rate and SQUID orientation required improving. Magnetic shields were also developed in case the SQUIDs would not operate unshielded and to test the system noise with geomagnetic variations removed. To enable removing the double layer shield from the probes while the SQUIDs remain submerged in LN2, the shield was designed to disassemble. The shields proved to be effective, however due to icing the shields could not be removed without removing the SQUIDs from the LN2. / AFRIKAANSE OPSOMMING: Hierdie werk bespreek die ontwerp van 'n 3-as Geomagnetometer SQUID Sisteem (GSS), waarin HTS SQUIDs sonder magnetiese skilde aangedryf word. Die aanvanklike GSS geïnstalleer by SANSA was ten volle binnewerking, maar die LN2 verdamping en SQUID oriëntasie benodig verbetering. Magnetiese skilde was ook ontwikkel vir die geval dat die SQUIDs nie sonder skilde wou werk nie en om die ruis te toets na geomagnetiese variasies verwyder is. Die dubbele laag skild was ontwerp om uitmekaar gehaal te word terwyl die SQUIDs binne die LN2 bly. Die skild was doeltreffend, maar ys het verhoed dat die skild verwyder kon word vanaf die LN2 sonder om die SQUIDs ook te verwyder.

Made available in DSpace on 2014-10-09T12:33:20Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:06:27Z (GMT). No. of bitstreams: 0 / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:43:49Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:10:01Z (GMT). No. of bitstreams: 1 06779.pdf: 6662459 bytes, checksum: 5a5ae589785a8bad523a922f578319f8 (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

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