Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 27 for “"Sunspots"”.
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Analysis of the penumbra formation in sunspots
The formation of the penumbra in sunspots is a physical process which involve the coupling between the plasma and the magnetic field in different layers of the solar atmosphere. Its study requires long time series of observations carried out with high temporal, spatial, and spectral resolution. …
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Analysis of high resolution observations of sunspots fine structures
In questo lavoro di tesi ho trattato lo studio dell'interazione tra il plasma e i campi magnetici presenti sul Sole. Osservazioni effettuate durante due campagne osservative, una presso lo Swedish 1-m Solar Telescope e l'altra presso il Richard B. Dunn Solar Telescope, hanno fornito dati ad alta …
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The 3-D topology of magnetic fields in and around sunspots
… on the surface of the solar disc are the sunspots, which have been studied since their detection in the 17th century. Despite this years and centuries of scientific investigations, surprisingly many facets of sunspots are not well understood. In this thesis, the properties of a sunspots' …
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Development of digital imaging technologies for the segmentation of solar features and the extraction of filling factors from SODISM images
… to improve the monitoring of features, such as sunspots and the prediction and diagnosis of solar activity. In proportion to the available raw material, the little-published analysis of SODISM data has provided the impetus for this study, specifically a novel method of contributing to the …
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The Impact of Sunspot Rotation on Solar Flares
… images of the Sun to determine the rotation of sunspots. This tool is used throughout the thesis, first on the active region 11158, in an in-depth case study of the rotation and flaring properties of the region as it traverses the solar disc. The case study develops analysis techniques, such as …
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High resolution studies of complex solar active regions
… regions. The most violent events are produced in sunspots with a complex magnetic field topology. Studying their morphology and dynamics is helpful in understanding the energy accumulation and release mechanisms for flares and CMEs, which are intriguing problems in solar physics. The study of …
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Em busca de um novo indicador Espectroscópico do período de rotação das Estrelas do tipo solar
The study of sunspots consistently contributed to a better understanding of magnetic phenomena of the Sun, as its activity. It was found with the dynamics of sunspots that the Sun has a rotation period of twenty-seven days around your axis. With the help of Project Sun-As-A-Star that solar spectra …
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Small and large-scale magnetic fields involved with solar flares
… white-light and magnetogram observations of 6 sunspots reveal the rapid penumbral decay and central umbral/penumbral darkening associated with flares and suggest that the flaring magnetic fields change from a highly inclined to a more vertical configuration. Moreover, these changes are …
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Image enhancement techniques applied to solar feature detection
… to detection of solar flares, plages and sunspots.
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Modeling and prediction of sunspot cycles
Solar activity, as indexed by sunspots, has a cycle of length varying from about 9 to 13 years. Statisticians have fitted several models to predict sunspot numbers one year ahead. We instead focus on predicting the magnitudes of the next cycle maximum, the next cycle minimum, the time from the …
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Automated Prediction of Solar Flares Using SDO Data. The Development of An Automated Computer System for Predicting Solar Flares Based on SDO Satellite Data Using HMI Images Analysis, Visualisation, and Deep Learning Technologies
… stored in twisted magnetic fields, usually near sunspots, is suddenly released. Yet, their occurrence is not fully understood. These flares can affect the Earth by the release of massive quantities of charged particles and electromagnetic radiation. Investigating the associations between solar …
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Automated Prediction of Solar Flares Using SDO Data. The Development of An Automated Computer System for Predicting Solar Flares Based on SDO Satellite Data Using HMI Images Analysis, Visualisation, and Deep Learning Technologies
… stored in twisted magnetic fields, usually near sunspots, is suddenly released. Yet, their occurrence is not fully understood. These flares can affect the Earth by the release of massive quantities of charged particles and electromagnetic radiation. Investigating the associations between solar …
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PROPERTIES AND CORRELATION OF FLARES AND CORONAL MASS EJECTIONS AND THEIR POSSIBLE RELEVANCE ON THE SOUTHERN NIGHT SKY BACKGROUND : A STATISTICAL STUDY
… their existence to localized magnetic fields: sunspots, faculae, filaments, active regions, bright points, coronal holes, etc. The occurrence of these phenomena is variable, depending on the so-called activity cycle, characterized by a period of 11 years. Moreover, in some situations, the …
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A comprehensive study of evolution of photospheric magnetic field and flows associated with solar eruptions
… the flow field vorticity of selected sunspots away from flare kernels in the AR 11158 is calculated using the Differential Affine Velocity Estimator. It is found that some spots exhibit a sharp acceleration of rotation co-temporal with the rapid rising of the soft X-ray flux, and that …
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Extrinsic uncertainty, ergodic chaos and monetary policy in two intertemporal economic models
… existence of extrinsic uncertainty also known as sunspots is analysed within the framework of a single commodity two-period pure exchange over lapping generations model. Transversality techniques are utilised to show that extrinsically uncertain equilibria are locally generic in the space of …
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Engineering System Design for Automated Space Weather Forecast. Designing Automatic Software Systems for the Large-Scale Analysis of Solar Data, Knowledge Extraction and the Prediction of Solar Activities Using Machine Learning Techniques
… created by investigating the associations among sunspots, filaments, flares, and CMEs. Evolution patterns of sunspot areas and McIntosh classifications are analysed using a statistical machine learning method, namely the Hidden Markov Model (HMM).
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Engineering System Design for Automated Space Weather Forecast. Designing Automatic Software Systems for the Large-Scale Analysis of Solar Data, Knowledge Extraction and the Prediction of Solar Activities Using Machine Learning Techniques.
… created by investigating the associations among sunspots, filaments, flares, and CMEs. Evolution patterns of sunspot areas and McIntosh classifications are analysed using a statistical machine learning method, namely the Hidden Markov Model (HMM).
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Automatic solar feature detection using image processing and pattern recognition techniques
… input features is used to differentiate between sunspots and filaments. Once a filament is identified, morphological thinning, pruning, and adaptive edge linking methods are applied to determine filament properties. Furthermore, a filament matching method is proposed to detect filament …
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Avalanches in stars and at finite temperature
… scaling even in the Sun's data, likely caused by sunspots or combinations of such spots. We also look at Tabby's star, where the anomalous dimming has not been explained, and show that there is also avalanche scaling seen in this extraordinary star. We then look at avalanches at finite but low …
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Spot evolution on the red giant star XX Triangulum
… surfaces are thought to be stellar analogues of sunspots. Thus, starspots are direct manifestations of strong magnetic fields. Their decay rate is directly related to the magnetic diffusivity, which itself is a key quantity for the deduction of an activity cycle length. So far, no single starspot …
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