abstract: Dynamic loading is the term used for one way of optimally loading a transformer. Dynamic loading means the utility takes into account the thermal time constant of the transformer along with the cooling mode transitions, loading profile and ambient temperature when determining the time-varying loading capability of a transformer. Knowing the maximum dynamic loading rating can increase utilization of the transformer while not reducing life-expectancy, delaying the replacement of the transformer. This document presents the progress on the transformer dynamic loading project sponsored by Salt River Project (SRP). A software application which performs dynamic loading for substation distribution transformers with appropriate transformer thermal models is developed in this project. Two kinds of thermal hottest-spot temperature (HST) and top-oil temperature (TOT) models that will be used in the application--the ASU HST/TOT models and the ANSI models--are presented. Brief validations of the ASU models are presented, showing that the ASU models are accurate in simulating the thermal processes of the transformers. For this production grade application, both the ANSI and the ASU models are built and tested to select the most appropriate models to be used in the dynamic loading calculations. An existing application to build and select the TOT model was used as a starting point for the enhancements developed in this work. These enhancements include:  Adding the ability to develop HST models to the existing application,  Adding metrics to evaluate the models accuracy and selecting which model will be used in dynamic loading calculation  Adding the capability to perform dynamic loading calculations,  Production of a maximum dynamic load profile that the transformer can tolerate without acceleration of the insulation aging,  Provide suitable output (plots and text) for the results of the dynamic loading calculation. Other challenges discussed include: modification to the input data format, data-quality control, cooling mode estimation. Efforts to overcome these challenges are discussed in this work. / Dissertation/Thesis / M.S. Electrical Engineering 2011

In Chapter 2 of this thesis I present my database of molecular absorption cross sections. These were developed using public molecular transition line-lists (from the ExoMol group). I use them to find limitations in the modelling of exoplanet atmospheres due to pressure broadening. Pressure broadening, where collisions between molecules in atmospheres cause a Lorentzian broadening of molecular transitional lines, is little understood in the field. In this chapter I consider its effects on real exoplanet atmosphere observations, both with current and future instruments. I show that pressure broadening may affect future observations of exoplanets in the JWST era. Pressure broadening primarily affects cooler, small exoplanets such as Earth analogues. In Chapter 3 I present the pipeline I have developed to reduce HST WFC3 spectra of exoplanet hosts during transits to create transmission spectra. This code corrects several instrumental systematics, from varying dark signal in the detector to subpixel shifts in the target position over time. By creating a pipeline to process all targets, regardless of observing strategy, systematics are dealt with uniformly and different planets’ spectra can be meaningfully compared. I show that the height of the water feature in 30 unique exoplanets’ transmission spectra is strongly correlated with the most simplistic absorption model. I use this to predict a list of the best future targets for observations with HST WFC3 to find water. In Chapter 4 I discuss my work with the stellar spectra from WFC3, which utilise the sub-pixel shifts in target position to oversample the spectra and increase the resolution. I have compared these exoplanet host stellar spectra with stellar models to investigate how well stellar atmosphere models describe the near IR. I find a small discrepancy in temperature when WFC3 alone is used to assess the stellar temperature, particularly with cooler stars. I attribute this firstly to an error in the WFC3 sensitivity curve and secondly to an inaccuracy in models of cool, small stars due to molecular absorption. In Chapter 5 I present my work on K2 light curve data using machine learning to find young stellar objects that display unusual, transit-like behaviour. These objects are known as dipper stars due to their distinctive occultations with depths of 10-50% in flux and very fast orbital periods of a few hours to a few days. Such large occultations are difficult to explain and are currently attributed to material at the inner edge of the protoplanetary disk. This behaviour is often variable and aperiodic, suggesting that the occulting material is changing in morphology on the time scale of a single orbit. Using python’s scikit-learn I have developed a code that utilises a Random Forest algorithm to classify stars in K2 Campaign Field 2 and distinguish these objects from other types of variables, such as eclipsing binaries and pulsating stars. This method has proved very successful and has allowed me to nearly quadruple the number of known dipper candidates in the Upper Scorpius and Rho Ophiuchus regions.

The objective of this research is the statistical study of space weather e ects on im- age detectors in Low Earth Orbit. The Hubble Space Telescope is used as a resource for acquiring proton a ected images for statistical analysis. For the purpose of the present work, the space weather environment will consist of cosmic as well as solar proton particles. The proton occurrences evident in images from the Hubble Charge Coupled Device (CCD) have been used to calculate the probability of proton events, which is related to the local space weather particle ux. The proton particles transfer energy to the CCD silicon, which ultimately results in measured signal that is not originating from photon illumination. The signal due to the proton interactions is rst separated from the noise contribution and subsequently used in the determi- nation of a pulse height probability distribution. Separation of the noise from the proton events also leads to the measurement of proton streak lengths and orientations along with the associated probability distributions. The directionality of the space weather environment in Low Earth Orbit is examined using the distribution of proton streak angles. Statistics found from the Hubble are also used as a starting point for simulations that create synthetic proton signal images. The distributions resulting from the Hubble CCD analysis give the probability of the: number of proton events, which is related to the ux of the space weather protons; energy of proton events, which allows estimates of damaging proton interactions; length of proton streaks on the CCD, which shows the relative probability of a long traversing proton event; angle of proton event, which indicates the directionality of the space weather environment.

abstract: Recent trends in the electric power industry have led to more attention to optimal operation of power transformers. In a deregulated environment, optimal operation means minimizing the maintenance and extending the life of this critical and costly equipment for the purpose of maximizing profits. Optimal utilization of a transformer can be achieved through the use of dynamic loading. A benefit of dynamic loading is that it allows better utilization of the transformer capacity, thus increasing the flexibility and reliability of the power system. This document presents the progress on a software application which can estimate the maximum time-varying loading capability of transformers. This information can be used to load devices closer to their limits without exceeding the manufacturer specified operating limits. The maximally efficient dynamic loading of transformers requires a model that can accurately predict both top-oil temperatures (TOTs) and hottest-spot temperatures (HSTs). In the previous work, two kinds of thermal TOT and HST models have been studied and used in the application: the IEEE TOT/HST models and the ASU TOT/HST models. And, several metrics have been applied to evaluate the model acceptability and determine the most appropriate models for using in the dynamic loading calculations. In this work, an investigation to improve the existing transformer thermal models performance is presented. Some factors that may affect the model performance such as improper fan status and the error caused by the poor performance of IEEE models are discussed. Additional methods to determine the reliability of transformer thermal models using metrics such as time constant and the model parameters are also provided. A new production grade application for real-time dynamic loading operating purpose is introduced. This application is developed by using an existing planning application, TTeMP, as a start point, which is designed for the dispatchers and load specialists. To overcome the limitations of TTeMP, the new application can perform dynamic loading under emergency conditions, such as loss-of transformer loading. It also has the capability to determine the emergency rating of the transformers for a real-time estimation. / Dissertation/Thesis / M.S. Electrical Engineering 2013

We study the variability of intensity of Io’s aurora asa function of Jupiter’s rotation measured in system III longitude.The far-ultraviolet intensity of Io’s aurora was measured by theHubble Space Telescope (HST) using the FUV-MAMA photondetector of the STIS. The data was processed using Matlab tofilter background and reflection, and account for the detector’soptical systems. Target regions of the detector were isolated forthe measurement of the OI(1356 ̊A) and SI(1479 ̊A) emissionsrespectively. By sampling photon detections within each emissionregion, we compute intensity reconstructions that we map tosystem III longitude. Curves were then fitted to the reconstruc-tions using a sinus fit. The results show two intensity peaks atsystem III longitudes (140±5)◦and (284±2)◦for both OIandSI. The difference in amplitude between the peaks are (38±6)%and (28±6)% for OIand SIrespectively. The asymmetriespeak intensities is possibly caused by the probability of excitingsulphur being higher than the probability of exciting sulphur.For a full explanation measurement of the oxygen to sulphurproportion in Ios atmosphere would be needed. We compare theresults to peaks of Io’s footprint on Jupiter measured by JUNOand other HST data sets. We find it likely that we confirm furthervariance in peak angle than reported in other research. This isespecially clear in the first intensity peak as it has a significantlylarger angle. Variability in Jupiter’s magnetic field and densityof the Jovian plasma torus is likely to explain peak angle andintensity variability, but further research is necessary to explainthe mechanisms in detail. / Vi studerar hur intensiteten av Ios aurora varierar i relation till Jupiters rotation mätt i system III longitud. Ios aurora mättes inom UVC området av Hubble Space Telescope (HST) med FUV-MAMA fotondetektorn. Matlab användes för att filtrera bort oönskade signaler som reflektion och bakgrund samt ta hänsyn till sensorns optiska system. Observationsområderna på sensorn konstruerades för mätningen av syre OI (1356Å ) och svavel SI (1479Å ) emissionerna. Genom att sampla fo- tondetektioner inom varje observationsområde så rekonstruerar vi en intensitetskurva som vi mappar till system III longitud. En kurva var sedan anpassad till rekonstruktionen med hjälp av en sinusanpassning. Resultaten visar två intensitetstoppar vid system III longituderna (140 ± 5)◦ och (284 ± 2)◦ för både OI och SI . Kvoten mellan topparna var (38 ± 6)% för OI och (28 ± 6)% för SI . Skillnaden i topparna kan förklaras av att sannolikheten att excitera svavel är större än att excitera syre. För fullständig beskrivning av skillnaden i topparna skulle mätningar av syre till svavel proportionen i Ios atmosfär behövas. Vi jämför våra reslutat med mätningar av Ios avtryck på Jupiter från JUNO och andra HST mätningar. Vi finner det sannolikt att vi bekräftar ytterligare varians i topparnas vinkel, främst för den första toppen vars vinkel är signifikant större. Variationer i Jupiters magnetfält och plasmadensitet av Jupiters plasmatorid kan sannolikt förklara positionen av topparna och intensitetsvariationerna. Vidare forskning behövs för att utförligt förklara dessa mekanismer. / Kandidatexjobb i elektroteknik 2020, KTH, Stockholm

En damm används i huvudsak för att magasinera vatten i energiutvinningssyfte. Dammen rör sig fram och tillbaka i ett säsongsmönster mestadels beroende på skillnader i utomhustemperatur och vattentemperaturen i magasinet. Det nordiska klimatet innebär risk för isläggning i magasinet, för vilken lasten är relativt outforskad. Denna rapport syftar till ett med multipla linjära regressionsmodeller samt dynamiska regressionsmodeller avgöra vilka variabler som förklarar en specifik svensk dammkonstruktions rörelse. Dammens rörelse mäts genom att mäta dammens förflyttning kontra berggrunden med data från dammens inverterade pendlar. Av särskilt intresse är att avgöra islastens påverkan på rörelsen. Resultaten visar att multipla linjära regressions-modeller inte fullständigt lyckas modellera dammens rörelse, då de har problem med autokorrelerade residualer. Detta hanteras med hjälp av autoregressiva regressionsmodeller där de initiala förklarande variablerna inkluderas, kallat dynamisk regression. Denna rapports resultat visar att de autoregressiva parametrarna fungerar mycket väl för att förklara pendlarna, men att även tid, temperatur, det hydrostatiska trycket samt istjocklek är användbara förklarande variabler. Istjockleken visar signifikant påverkan på 5 % signifikansnivå på två av de undersökta pendlarna, vilket är ett noterbart resultat. Författarna menar att rapportens resultat indikerar att det finns anledning att fortsätta forska kring islastens påverkan på dammkonstruktioner. / A dam is a structure mainly used for storing water and generating electricity. The structure of a dam moves in a season-based pattern, mainly because of the difference in temperature between the air on outside of the dam and the water on the inside. Due to the Nordic climate, occurrences of icing on the water in the basin is fairly frequent. The effects of ice on the structural load of the dam are relatively unexplored and are the subject to this bachelor’s thesis. The goal of this project is to evaluate which predictors are significant to the movement of the dam with multiple linear regression models and dynamic regressions. The movement is measured by inverted pendulums that register the dam’s movement compared to the foundation. It is of particular interest to determine if the ice load influences the movement of the dam. The multiple regression models used to explain the dam’s movement were all discarded due to autocorrelation in the residuals. This falsifies the models, since autocorrelation means that they don’t meet the needed assumptions. To counteract the autocorrelation, dynamic models with autoregressive terms were fitted. These models showed no problem with autocorrelation. The result from the dynamic models were successful and managed to significantly explain the movement of the dam. The autoregressive terms proved to be efficient explanatory variables. The dynamic regression models also show that the time, temperature, hydrostatic pressure and ice thickness variables are also useful explanatory variables. The ice thickness shows a significant effect at the 5 % significance level on two of the investigated pendulums. The report's results indicate that there is reason to continue research on the ice load impact on dam constructions.

International Telemetering Conference Proceedings / October 25-28, 1993 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The Hubble Space Telescope (HST) Observatory Management System (HSTOMS), located at the Goddard Space Flight Center (GSFC), provides telemetry, command, analysis and mission planning functions in support of the HST spacecraft. The Telemetry and Command System (TAC) is an aging system that performs National Aeronautics and Space Administration (NASA) Communications (Nascom) block and telemetry processing functions. Future maintainability is of concern because of the criticality of this system element. HSTOMS has embarked on replacing the TAC by using functional elements developed by the Microelectronics Systems Branch of the GSFC. This project, known as the Transportable TAC (TTAC) because of its inherent flexibility, is addressing challenges that have resulted from applying recent technological advances into an existing operational environment. Besides presenting a brief overview of the original TAC and the new TTAC, this paper also describes the challenges faced and the approach to overcoming them.

Abstract In this report I present a study of possible age gradients in the Green Pea galaxy J145735.13+223201.8 to be able to conclude if there is an extended star forming history in such a galaxy. Data are coming from two different sources, highly resolved images in four different wavelengths of stars in the galaxy, and of nebular gas in a narrow band Ha Balmer line filter, from the Hubble Space Telescope (HST), as well as spectral line information from the Sloan Digital Sky Survey (SDSS). I compare the observations with stellar population models from two different libraries, Yggdrasil and Starburst99. Due to the highly resolved images from HST this is one of the first studies of spatially resolved stellar populations in a Green Pea galaxy. With the help from these spatially resolved images it was possible to study star clumps independently from each other. This would not be possible when using only data from SDSS. In this way it was possible to conclude an age difference between the centre of the galaxy and its outskirts. I found that the galaxy has an age gradient at a confidence level greater than 95%.

High-speed corridor is the future of travellibg. Many Eauropian states have begun with building it a few years ago and it works well. The Czech Republic still does not have this form of transport, but due to the location it will be necessary to build high quality railways even here for the future connection across Europe. This thesis deals with the construction of high-speed train stop (the HST) nearby the airport Brno Turany. The service follows the previous semestral work - Brno main railway station. The HST station building is drafted as a bridge over the rail and the platforms, it works not only as a check-in and waiting area but also like a pedestrian crossing over the corridor. The solid responds to the airport nearby and used bridge construction to smartly takes roof up. Public parts are at ground level, technical background and maintenance are located along the platforms below the ground level.

A body exposed to hypersonic flow is subjected to extremely high wall heating rates, owing to the conversion of the kinetic energy of the oncoming flow into heat through the formation of shock waves and viscous dissipation in the boundary layer and this is one of the main concerns in the design of any hypersonic vehicle. The conventional way of tackling this problem is to use a blunt fore-body, but it also results in an increase in wave drag and puts the penalty of excessive load on the propulsion system. An alternative approach is to alter the flow field using external means without changing the shape of the body; and several such methods are reported in the literature. The superiority of such methods lie in the fact that the effective shape of the body can be altered to meet the requirements of low wave drag, without having to pay the penalty of an increased wall heat transfer rate. Among these techniques, the use of local energy addition in the freestream to alter the flow field is particularly promising due to the flexibility it offers. By the suitable placement of the energy source relative to the body, this method can be effectively used to reduce the wave drag, to generate control forces and to optimise the performance of inlets. Although substantial number of numerical investigations on this topic is reported in the literature, there is no experimental evidence available, especially under hypersonic flow conditions, to support the feasibility of this concept. The purpose of this thesis is to experimentally investigate the effect of energy deposition on the flow-field of a 120� apex angle blunt cone in a hypersonic shock tunnel. Energy deposition is done using an electric arc discharge generated between two electrodes placed in the free stream and various parameters influencing the effectiveness of this technique are studied. The effect of energy deposition on aerodynamic parameters such as the drag force acting on the model and the wall heat flux has been investigated. In addition, the unsteady flow field is visualised using a standard Z-type schlieren flow visualisation setup. The experimental studies have shown a maximum reduction in drag of 50% and a reduction in stagnation point heating rate of 84% with the deposition of 0.3 kW of energy. The investigations also show that the location of energy deposition has a vital role in determining the flow structure; with no noticeable effects being produced in the flow field when the discharge source is located close to the body (0.416 times body diameter). In addition, the type of the test gas used is also found to have a major influence on the effectiveness of energy deposition, suggesting that thermal effects of energy deposition govern the flow field alteration mechanism. The freestream mass flux is also identified as an important parameter. These findings were also confirmed by surface pressure measurements. The experimental evidence also indicates that relaxation of the internal degrees of freedom play a major role in the determination of the flow structure. For the present experimental conditions, it has been observed that the flow field alteration is a result of the interaction of the heated region behind the energy spot with the blunt body shock wave. In addition to the experimental studies, numerical simulations of the flow field with energy deposition are also carried out and the experimentally measured aerodynamic drag with energy deposition is found to match reasonably well with the computed values.