There was a large radar campaign during 2007 and 2008, the International Polar Year (IPY),and at that time the EISCAT Svalbard Radar was operated and measured the ionosphere continuouslyat most times. This report presents statistical results from an electron enhancementpoint of view. Until now there has been some research into the field and results based on theions in the ionosphere, and the enhancements we refer to as Naturally enhanced ion acousticlines (NEIALs). Plasma line data from May 2007 to February 2008 has been analysed inorder to find and classify enhancements as NEIALs have been classified but with respect tothe electron distribution instead of the ion distribution. A method of detection was developedin order to differentiate the enhancements from the background with a relation between theminimum and maximum power of each measured dump. Results show that there is a largedifference between the downshifted plasma lines and the upshifted plasma lines, both has arange distribution peak at 180 km and the upshifted plasma line has another peak at 230 kmwhich the downshifted plasma line does not. The occurrence rate of the enhancements was1.64 % for the downshifted plasma line and 4.69 % for the upshifted plasma line. Threedifferent types of enhancements are classified using the variance distribution for the peakfrequency of that detected dump, Single, Profile, and Diffuse. The Single enhancements havea bit different spectral, range, and time of day distributions than of the Profile and Diffusedistributions. The Diffuse classifications are mostly wrong classifications and aliasing and itis very similar to Profile enhancements as seen by its distribution.

The structure of the plasma in Jupiter’s vast magnetosphereis complicated and not fully understood. One way to study the plasma is to look at auroral emissions from the moonIo as it moves through different regions of the plasma torus that surrounds Jupiter. In this paper, the correlation between aurorabrightness on Io and the plasma density at the position of the moon is investigated. If a correlation exists, auroral emissonson Io could be used as a diagnostic for the current state ofJupiter’s plasma environment. For this purpose, a model of the Io plasma torus is developed, combining ideas from different existing models. The model is compared with observations of aurorae on Io made by the Hubble Space Telescope. Io’s position at the time of the observations is obtained with SPICE, a software developed by NASA. A moderate correlation is found when using the whole data set of observations. However, a strong correlation is found for observations on the dusk side of Jupiter. Strong correlations are also found when studying individual years and epochs. / Strukturen på plasman i Jupiters vidsträckta magnetosfär är komplicerad och inte fullständigt känd. Ett sätt att studera plasman är att undersöka ljuset från polarsken på månen Io då den passerar genom olika regioner av det torusformade plasmamolnet som omsluter Jupiter. I denna artikel undersöks korrelationen mellan polarskenets ljusstyrka och plasmans densitiet kring månens position. Om ett sådant samband finns skulle ljusstyrkan hos månens polarsken kunna användas som diagnostik för plasmans aktuella tillstånd. För detta ändamål utvecklas en modell av plasmatorusen genom att kombinera ide´er från flera tidigare modeller. Modellen jämförs sedan med observationer av polarskenet på Io genomförda med rymdteleskopet Hubble. Månens position vid de olika tidpunkterna bestäms med hjälp av SPICE, en mjukvara utvecklad av NASA. En måttligt stark korrelation uppnås när hela datamängden används. När däremot endast data från Jupiters gryningssida används uppnås en korrelation. Det hittas även starka samband när enskilda år studeras. / Kandidatexjobb i elektroteknik 2022, KTH, Stockholm

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Over the past few years, speech recognition technology performance on tasks ranging from isolated digit recognition to conversational speech has dramatically improved. Performance on limited recognition tasks in noiseree environments is comparable to that achieved by human transcribers. This advancement in automatic speech recognition technology along with an increase in the compute power of mobile devices, standardization of communication protocols, and the explosion in the popularity of the mobile devices, has created an interest in flexible voice interfaces for mobile devices. However, speech recognition performance degrades dramatically in mobile environments which are inherently noisy. In the recent past, a great amount of effort has been spent on the development of front ends based on advanced noise robust approaches. The primary objective of this thesis was to analyze the performance of two advanced front ends, referred to as the QIO and MFA front ends, on a speech recognition task based on the Wall Street Journal database. Though the advanced front ends are shown to achieve a significant improvement over an industry-standard baseline front end, this improvement is not operationally significant. Further, we show that the results of this evaluation were not significantly impacted by suboptimal recognition system parameter settings. Without any front end-specific tuning, the MFA front end outperforms the QIO front end by 9.6% relative. With tuning, the relative performance gap increases to 15.8%. Finally, we also show that mismatched microphone and additive noise evaluation conditions resulted in a significant degradation in performance for both front ends.

No description available.

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

This dissertation examines the body of literature that formed around anomalous light apparitions (comets, new stars, the aurora borealis, and rainbows) as it explores questions about the representation and response to celestial and meteorological phenomena during the seventeenth and eighteenth centuries in colonial America. I further consider the ways that these texts’ meanings are informed by rational scientific thought and by other non-scientific or non-rational, emotive, or aesthetic modes of thinking. I consider how these phenomena elicit a set of empirical yet emotionally-charged observational practices that complicate how we understand the roles of the rational and the non-rational in the scientific literature of this period. I argue that non-rational passionate investments are evident within or as part of the period’s rational scientific literature; they act as the impetus for scientific inquiry therefore forming an integral part of the scientific endeavor. This dissertation further explores how the practice of writing about these phenomena generates and facilitates the formation of communities of amateur scientific observers in colonial America. I further investigate how practices of data collection contribute to knowledge about the regular and irregular behaviors of celestial bodies, and how this knowledge impacts everyday practices essential for survival such as farming and travelling. What science writing from this period demonstrates is the ability for multiple ways of thinking to be in play simultaneously; these texts show how several worldviews (i.e. science, Puritanism, popular religion) are intrinsic to each other. Because of their liminality, these texts function outside of traditional categories such science, religion, and natural philosophy. Furthermore, they destabilize traditional conceptions of genre with their blend of rational and non-rational modes of thought and their incorporation of fact and fiction. While I treat these literary texts within their historical contexts, I am also interested in the ways in which these texts reach modern audiences, particularly in academia at a time when the humanities and sciences are positioned against one another. / English

Too often, space or void, has been considered an a priori condition. Rather than using it and it's relationship to solids to create a harmony and balance of form, void has been unconsciously disregarded as a virtual nonelement in design. This thesis attempts to bring a tangible character to the void; to design the void as if it were a solid form. In doing so, the limiting properties of solid are broken down. Defining characteristics of solid and void are shared and boundaries are blurred. What was once known becomes unknown. / Master of Architecture

A dual satellite system in a Low Earth Orbit, LEO, would be beneficial to study the electromagnetic occurrences in the magnetosphere and their contributions to the development of the aurora events in the Earth's lower atmosphere. An orbit configuration is sought that would increase the total time that both satellites are inside the auroral oval. Some additional objectives include minimizing the total fuel cost and the average angle between the satellites' radius vectors. This orbit configuration is developed using a series of instantaneous burns applied at each satellite's perigee. An analysis of the optimal solutions generated by a Particle Swarm Optimization method is completed using a cost function with different weights for the time, fuel, and angle terms. Three different scenarios are presented: a single burn case, a double burn case, and a four burn case. The results are calculated using two different orbital mechanics models: an unperturbed two-body simulation and a two-body simulation with added Earth's equatorial bulge effects. It is shown that the added perturbation reduces the total event time in the optimal solutions generated. Specific weights for the cost function are recommended for further studies. / Master of Science

In recent years, multi-core processors and multi-processor networks have grown in popularity as a solution to the limits on increasing clock speed, rising power consumption, and the nanometer manufacturing processes. Multi-core processors and multi-processor networks are seen as the next step in the advancement of computational capabilities by way of concurrent processing. However, parallel software design is difficult due to the immaturity of scalable architectures and software development environments for multi-core hardware. How should processors effectively and quickly pass information, with as little overhead as possible? What kind of communication architecture is best suited for parallelism? How can large-scale architectures be quickly produced, verified and properly utilized by software? Using commercially available FPGA development boards, Xilinx tools and components, this thesis offers a light-weight solution to these questions for effective, low-overhead, low-latency multi-core communication and fast prototyping of multi-processor networks for scalable processor arrays. / Master of Science