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Novos métodos de estimação de ruído de fundo de céu aplicados à missão CoRoT. / New methods for estimating sky background noise applied to the CoRoT mission.Luciana Guidon Coelho 11 April 2012 (has links)
O satélite franco-europeu com participação brasileira, CoRoT (Convention, Rotation and planetary Transits), faz parte de uma missão espacial dedicada à sismologia estelar e à busca por exoplanetas. Para a descoberta de exoplanetas, o objetivo é detectar a ocultação temporária da estrela ao redor da qual orbita o planeta em questão, ou seja, detectar um trânsito planetário que pode ser traduzido por uma diminuição tênue do fluxo de fótons estelar coletado pelos CCDs do fotômetro. Existem alguns ruídos e diversas fontes de luz que atingem os CCDs e que não são provenientes das estrelas em estudo. Tais ruídos e fontes de luz geram uma iluminação chamada de fundo de céu nos CCDs que é não homogênea e que precisa ser corrigida antes do início da exploração científica dos dados obtidos nas observações do satélite. A correção de fundo de céu é um procedimento padrão na redução de dados fotométricos, e consiste na subtração do nível médio de fundo de céu das medições fotométricas de uma estrela. Para a determinação do fundo de céu o CoRoT utiliza um conjunto de janelas de fundo de céu. Este trabalho propõem métodos alternativos para a alocação destas janelas de fundo de céu e estimação do ruído de fundo de céu para o canal de exoplanetas do satélite CoRoT. São apresentados dois novos métodos de alocação de janelas e são testados diversos métodos de estimação de ruído de fundo de céu. Os testes realizados neste trabalho sugerem fortemente a utilização do método chamado k-min para a alocação de janelas e do método mediana e 5 vizinhos para a estimação de ruído de fundo de céu. O método k-min procura alocar as janelas de maneira homogênea e em locais de mínimo de uma imagem do céu observado pelo satélite e o método mediana e 5 vizinhos estima o ruído de fundo de céu a partir da mediana de todas as janelas de fundo de céu com nível DC corrigido pela mediana das cinco janelas vizinhas mais próximas. / The French-European satellite with Brazilian participation, CoRoT (Convention, Rotation and planetary Transits), is part of a space mission dedicated to stellar seismology and exoplanets search. Both scientific programs are based on a high-precision photometry and require long-term uninterrupted observations. The satellite uses stellar photometry from images captured on CCD (charged coupled devices), known as photometry by mask. For the discovery of exoplanets, the goal is to detect the temporary hiding of the star which around orbits the planet in question, that is, to detect a planetary transit, which can be translated by a slight decrease in the stellar photon flux collected by the CCDs of the photometer. There are some noise and various sources of light that reaches the CCD and are not from the stars under study. Such noise and light sources produce a light called \"sky background\" in CCDs that is not homogeneous and that must be corrected before the scientific exploration of the data obtained from satellite observations. The sky background correction is a standard procedure in the reduction of photometric data. It consists in subtracting the average level of sky background of photometric measurements of a star. To determine the sky background noise, CoRoT uses a set of sky background windows and this work proposes alternative methods for allocating these windows and for estimating the sky background noise to the CoRoT exoplanet channel. Here are present two new methods of windows allocation and are tested several methods of estimating the sky background noise. Tests conducted in this study strongly suggest the use of the method called k-min for windows allocation and the method \"median and 5 neighbors\" to the estimation of sky background noise. The k-min method tries to allocate windows homogeneously and in minimum locals of image of the sky observed by the satellite, and the method \"median and 5 neighbors estimates the sky background noise by the median of all background windows with DC level corrected by the median of the five nearest neighbors.
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Organic Fluids and Passive Cooling in a Supercritical Rankine Cycle for Power Generation from Low Grade Heat SourcesVidhi, Rachana 08 July 2014 (has links)
Low grade heat sources have a large amount of thermal energy content. Due to low temperature, the conventional power generation technologies result in lower efficiency and hence cannot be used. In order to efficiently generate power, alternate methods need to be used. In this study, a supercritical organic Rankine cycle was used for heat source temperatures varying from 125°C to 200°C. Organic refrigerants with zero ozone depletion potential and their mixtures were selected as working fluid for this study while the cooling water temperature was changed from 10-25°C. Operating pressure of the cycle has been optimized for each fluid at every heat source temperature to obtain the highest thermal efficiency. Energy and exergy efficiencies of the thermodynamic cycle have been obtained as a function of heat source temperature.
Efficiency of a thermodynamic cycle depends significantly on the sink temperature. At areas where water cooling is not available and ambient air temperature is high, efficient power generation from low grade heat sources may be a challenge. Use of passive cooling systems coupled with the condenser was studied, so that lower sink temperatures could be obtained. Underground tunnels, buried at a depth of few meters, were used as earth-air-heat-exchanger (EAHE) through which hot ambient air was passed. It was observed that the air temperature could be lowered by 5-10°C in the EAHE. Vertical pipes were used to lower the temperature of water by 5°C by passing it underground. Nocturnal cooling of stored water has been studied that can be used to cool the working fluid in the thermodynamic cycle. It was observed that the water temperature can be lowered by 10-20°C during the night when it is allowed to cool. The amount of water lost was calculated and was found to be approximately 0.1% over 10 days.
The different passive cooling systems were studied separately and their effects on the efficiency of the thermodynamic cycle were investigated. They were then combined into a novel condenser design that uses passive cooling technology to cool the working fluid that was selected in the first part of the study. It was observed that the efficiency of the cycle improved by 2-2.5% when passive cooling system was used.
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Analysis on Operation Readiness Strategy -Case Study on Airline Industry & Rail IndustryP. Lin, Samuel 27 July 2007 (has links)
Following the Globalization trend, the policy of Deregulation, Open Sky and BOT had been implemented into the transportation industry in Taiwan. This new policy created the dynamics for transformation both in the Airlines Industry and Railway Industry.
The new transportation policy lead to the establishment of E-Airways and T-Rail. This research concentrated on the case study of Operations Readiness Strategy implemented by E-Airways and T-Rail respectively based on the academic theory of SWOT and Five Force Model.
E-Airways Case Study covers the strategic items on the establishment of Operations Core Competence, Flight Networks, Innovation of Economy-Deluxe class, Marketing Channel and Airline Strategic Alliance. T-Rail Case Study refers to the Operations Readiness Strategy implemented to import the core competence of High Speed Rail.
This research reached the conclusions:
1.To confirm academic theory to be applicable for the successful model of both E-Airways and T-Rail case study;
2.To confirm same strategy model to be applied for different industry;
3.To confirm the strategic competence to be created;
4.That Cross verification of SWOT and Five Force Model will lead to solid strategy.
5.The successful model of E-Airways case study with analysis on the operation readiness strategy is available as reference for any potential airline operator after merge & acquisition of existing airlines.
6.The successful model of T-Rail case study is available as reference model for any ¡§next one¡¨ national HSR (High Speed Rail) Project.
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Conservation Genetics of Black Bears in Arizona and Northern MexicoVaras-Nelson, Angela Cora January 2010 (has links)
Because American black bears (Ursus americanus) are an important game species in Arizona and are endangered in México, an understanding of the population structure, gene flow, and connectivity are important for effective management. Black bears inhabit coniferous and broadleaf deciduous woodlands in southern Arizona and northern México, usually in sky islands (sky islands are mountains that rise from the desert and are isolated from each other). Because a single sky island is too small to support a viable bear population, black bears move through desert lowlands to reach other sky islands. My objective was to assess genetic structure, connectivity, and conservation implications for sky island black bears in southern Arizona and northern México. I addresses 4 components of bear ecology and genetics: a literature review of genetic information available for black bears in North America; the use of 2 mitochondrial DNA genes (Control Region and ATP synthase protein 8) to study the phylogenetic relationship of black bears from the sky islands of southern Arizona and northern México relative to all North America; the use of 10 microsatellite loci to detect the current genetic structure of black bears in the sky islands in Arizona and northern México; and the use of noninvasive samples collected from the field to determine bear density and population size for black bear in Sierra San Luis, Sonora, México. These studies provide information that can be used by biologists, land managers, and others to assist in the conservation of black bears and their habitat.
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Developing a method for regional food system planning in the Sea to Sky Region, British ColumbiaRaimondi, Laura Joanne 08 May 2012 (has links)
This study set out to test the potential of an environmental management planning
method to be adapted into a food system planning framework, referred to as a Regional
Food System Management Plan (RFSMP). The RFSMP approach is a valuable and useful
tool for regional food systems planning as it promotes community and environmental
sustainability through enhanced food self-reliance. The RFSMP framework was
developed and tested in the context of the Sea to Sky Region of British Columbia. The
main components of the RFSMP framework included delineation of regional boundaries,
stakeholder values identification and calculation of food self-reliance. Implementation of
the RFSMP framework focused on the planning stage and the crop production
components of the food system. This study recommends future work to address
agricultural data gaps, complete the RFSMP framework beyond the planning phase and
production component of the food system, and test the planning framework in other
regions.
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Definitions of Clear-sky Fluxes and ImplicationsVerma, Abhishek 2011 December 1900 (has links)
Clear-sky top-of-atmosphere (TOA) fluxes are important in estimating the impact of clouds on our climate. In this study, we quantitatively compare the clear-sky fluxes measurements of the Clouds and the Earths Radiant Energy System (CERES) instrument to clear-sky fluxes from two reanalysis, NASA's Modern Era Retrospective-analysis for Research and Application (MERRA), and the European Center for Medium Range Weather Forecast Interim reanalysis (ERA-Interim). In the first comparison, we compare observed fluxes from individual cloud-free field-of-
views to the reanalyses. In the second comparison, we compare monthly averaged observed clear-sky fluxes to those from the reanalyses. Monthly clear-sky fluxes are
calculated by averaging fluxes from cloud-free regions.
In both comparisons, the fluxes generally agree within +/- 10 W/m^2. Finally, we show that, while the differences between the fluxes of observations and the reanalyses are several W/m2, the inter-annual anomalies agree much better, with zonal and global average inter-annual anomalies typically agreeing within 1 W/m^2. The longwave clear-sky anomalies show excellent agreement even when comparing individual grid points, whereas the shortwave clear-sky anomalies are generally smaller at individual grid points.
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A New Set of Spectroscopic Metallicity Calibrations for RR Lyrae Variable StarsSpalding, Eckhart 01 January 2014 (has links)
RR Lyrae stars are old, iron-poor, Helium-burning variable stars. RR Lyraes are extremely useful for tracing phase-space structures and metallicities within the galaxy because they are easy to identify, have consistent luminosities, and are found in large numbers in the galactic disk, bulge, and halo. Here we present a new set of spectroscopic metallicity calibrations that use the equivalent widths of the Ca II K, Hγ, and Hδ lines to calculate metallicity values. Applied to spectroscopic survey data, these calibrations will help shed light on the evolution of the Milky Way and other galaxies.
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Reading the Sky : From Starspots to Spotting StarsEriksson, Urban January 2014 (has links)
This thesis encompasses two research fields in astronomy: astrometry and astronomy education and they are discussed in two parts. These parts represent two sides of a coin; astrometry, which is about constructing 3D representations of the Universe, and AER, where for this thesis, the goal is to investigate university students’ and lecturers’ disciplinary discernment vis-à-vis the structure of the Universe and extrapolating three-dimensionality. Part I presents an investigation of stellar surface structures influence on ultra-high-precision astrometry. The expected effects in different regions of the HR-diagram were quantified. I also investigated the astrometric effect of exoplanets, since astrometric detection will become possible with projects such as Gaia. Stellar surface structures produce small brightness variations, influencing integrated properties such as the total flux, radial velocity and photocenter position. These properties were modelled and statistical relations between the variations of the different properties were derived. From the models it is clear that for most stellar types the astrometric jitter due to stellar surface structures is expected to be of order 10 μAU or greater. This is more than the astrometric displacement typically caused by an Earth-sized exoplanet in the habitable zone, which is about 1–4 μAU, making astrometric detection difficult. Part II presents an investigation of disciplinary discernment at the university level. Astronomy education is a particularly challenging experience for students because discernment of the ‘real’ Universe is problematic, making interpretation of the many disciplinary-specific representations used an important educational issue. The ability to ‘fluently’ discern the disciplinary affordances of these representations becomes crucial for the effective learning of astronomy. To understand the Universe I conclude that specific experiences are called. Simulations could offer these experiences, where parallax motion is a crucial component. In a qualitative study, I have analysed students’ and lecturers’ discernment while watching a simulation video, and found hierarchies that characterize the discernment in terms of three-dimensionality extrapolation and an Anatomy of Disciplinary Discernment. I combined these to define a new construct: Reading the Sky. I conclude that this is a vital competency needed for learning astronomy and suggest strategies for how to implement this in astronomy education.
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Reading the sky : from starspots to spotting starsEriksson, Urban January 2014 (has links)
This thesis encompasses two research fields in astronomy: astrometry and astronomy education and they are discussed in two parts. These parts represent two sides of a coin; astrometry, which is about constructing 3D representations of the Universe, and AER, where for this thesis, the goal is to investigate university students’ and lecturers’ disciplinary discernment vis-à-vis the structure of the Universe and extrapolating three-dimensionality. Part I presents an investigation of stellar surface structures influence on ultra-high-precision astrometry. The expected effects in different regions of the HR-diagram were quantified. I also investigated the astrometric effect of exoplanets, since astrometric detection will become possible with projects such as Gaia. Stellar surface structures produce small brightness variations, influencing integrated properties such as the total flux, radial velocity and photocenter position. These properties were modelled and statistical relations between the variations of the different properties were derived. From the models it is clear that for most stellar types the astrometric jitter due to stellar surface structures is expected to be of order 10 μAU or greater. This is more than the astrometric displacement typically caused by an Earth-sized exoplanet in the habitable zone, which is about 1–4 μAU, making astrometric detection difficult. Part II presents an investigation of disciplinary discernment at the university level. Astronomy education is a particularly challenging experience for students because discernment of the ‘real’ Universe is problematic, making interpretation of the many disciplinary-specific representations used an important educational issue. The ability to ‘fluently’ discern the disciplinary affordances of these representations becomes crucial for the effective learning of astronomy. To understand the Universe I conclude that specific experiences are called. Simulations could offer these experiences, where parallax motion is a crucial component. In a qualitative study, I have analysed students’ and lecturers’ discernment while watching a simulation video, and found hierarchies that characterize the discernment in terms of three-dimensionality extrapolation and an Anatomy of Disciplinary Discernment. I combined these to define a new construct: Reading the Sky. I conclude that this is a vital competency needed for learning astronomy and suggest strategies for how to implement this in astronomy education.
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Transgressing boundaries and cultural haunting in Chinese American and Chinese Canadian 'talk stories' /Morfetas, Elpida, January 1900 (has links)
Thesis (M.A.)--Carleton University, 2002. / Includes bibliographical references (p. 158-165). Also available in electronic format on the Internet.
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