<div>For centuries, fluid flows (hydrodynamics) and electromagnetic phenomena have interested scientists and laypeople alike. The earliest recording of the intersection of these two ideas, electro-hydrodynamics, was reported four centuries ago by William Gilbert who observed that static electricity generated from rubbed amber could ``attract" water. Today electrohydrodynamic phenomena are the underlying mechanisms driving the production of nano-fibers through electro-spinning, printing circuitry, and electrospraying, which John Fenn used in his Nobel prize winning work on electrospray ionization mass spectrometry. In all of these applications, a strong electric field is used to deform a liquid-gas interface (free surface) into a sharp conical tip. Unable to sustain these large interfacial stresses, a thin jet of fluid emerges from the tip of the cone and may subsequently break into a stream of smaller droplets. This tip-streaming phenomenon demands fundamental understanding of three canonical problems in fluid mechanics: electrified cones (Taylor cones), jets, and droplets. </div><div>In this thesis, the electrohydrodynamics of free surface flows are examined through both analytical and numerical treatment of the Cauchy momentum equations augmented with Maxwell's equations. Linear oscillations and stability of (inviscid) conducting charged droplets are examined in the presence of a solid ring shaped constraint. Here the constraint gives rise to an additional mode of oscillation---absent in the analysis of a free (unconstrained) droplet. Interestingly, the amount of charge necessary for instability, the Rayleigh charge limit, is unaltered by the constraint, but the mode of oscillation associated with instability changes. While all of the aforementioned applications involve electrified liquid-gas interfaces, recent experiments reveal a previously unknown type of streaming can occur for droplets suspended in another fluid. In these experiments, the suspending fluid is more conductive and an external electric field drives the intially spherical drop to adopt an oblate shape. Based on the viscosity ratio between the drop and suspending fluid, two different types of instability were observed: (i) if the drop is more viscous, then the drop forms a dimple at its poles and ruptures though its center, a phenomenon that is now referred to as dimpling, and (ii) if the suspending fluid is more viscous, then the drop adopts a lens-like shape and emits a sheet from its equator that subsequently breaks into a stream of rings and then tiny droplets, a phenomenon that is now called equatorial streaming. The physics of these two instabilities are far beyond the applicability of linear theory, requiring careful numerical analysis. Here steady-state governing equations are solved using the Galerkin finite element method (GFEM) to reveal the exact nature of these two instabilities and their dependence on the viscosity ratio. The fate of these drops once they succumb to instability is then analyzed by fully transient simulations.</div><div> Lastly, in a growing number of applications, the working fluid is non-Newtonian, and may even contain suspended solid particles. When non-Newtonian rheology is attributable to the presence of polymer, the dynamics is analyzed by means of a DEVSS-TG/SUPGFEM algorithm that is developed for simulating viscoelastic free surface </div><div>flows. When complex fluid rheology is due to the presence of suspended solid spherical particles, both early-time (linear) and asymptotic dynamics are uncovered by coupling the motion of the particles and Newtonian fluid implicitly in a GFEM fluid-structure interaction (FSI) algorithm. These novel algorithms are used to analyze the pinch-off dynamics of liquid jets and drops.</div>

Våld i nära relation är ett globalt problem och kränker våldsutsatta kvinnors handlingsfrihet, livsutrymmet och mänskliga rättigheter. Kvinnor är överrepresenterade offer för våld i nära relation och forskningen kring våldsutsatta kvinnors uppbrottsprocesser är begränsad. Syftet med vår studie var att undersöka hur tidigare forskning uppmärksammat uppbrottsprocesser som våldsutsatta kvinnor genomgår när de lämnar våldsutövande män. Vi har undersökt främjande och hindrande faktorer i kvinnornas uppbrottsprocesser. Utifrån en integrativ litteraturstudie har 12 vetenskapliga artiklar valts ut där resultatet tematiserats varpå en analys har genomförts utifrån ett intersektionellt perspektiv och generella motståndsresurser. Resultatet visar att uppbrottsprocesser är komplexa och att okunskap i omgivande nätverk och hos professionella som arbetar med våldsutsatta kvinnor finns. I analysen framkommer det att uppbrottsprocessen inte kan ses utifrån ett perspektiv utan att faktorer innan, under och efter uppbrottet måste beaktas för att ge våldsutsatta kvinnor det stöd de behöver. / Domestic violence is a global issue and violates abused women's latitude, living space and human rights. Women are overrepresented victims of domestic violence and research about abused women’s breakup processes is limited. The purpose of this study was to examine how former research describes abused women’s breakup processes when they leave violent men. We have investigated facilitating and obstructing factors in women’s breakup processes. With an integrative literature study 12 science articles have been chosen where the results have been thematized whereupon an analysis have been implemented from an intersectional perspective and general resistance resources. The result indicates that breakup processes are complex and that ignorance in surrounding networks and among professionals who work with abused women exists. The analysis shows that the breakup process can’t be seen from only one perspective but that factors before, during and after the breakup must be accounted for to be able to give the support that abused women need.

Pressure swirl atomizers are commonly used in IC, aero-engines, and liquid propellant rocket combustion. Understanding the atomization process is important in order to enhance vaporization, mitigate soot formation, design of combustion chambers, and improve overall combustion efficiency. This work utilizes non-invasive techniques such as ultra -speed imaging, and Phase Doppler Particle Anemometry (PDPA) in order to investigate the cascade atomization process of pressure-swirl atomizers by examining swirling liquid film dynamics and the localized droplet characteristics of the resulting hollow cone spray. Specifically, experiments were conducted to examine these effects for three different nozzles with orifice diameters .3mm, .5mm, and .97mm. The ultra-speed imaging allowed for both visualization and interface tracking of the swirling conical film which emanated from each nozzle. Moreover, this allowed for the measurement of the radial fluctuations, film length, cone angle and maximum wavelength. Radial fluctuations are found to be maximum near the breakup or rupture of a swirling film. Film length decreases as Reynolds number increases. Cone angle increases until a critical Reynolds number is reached, beyond which it remains constant. A new approach to analyze the temporally unstable waves was developed and compared with the measured maximum wavelengths. The new approach incorporates the attenuation of a film thickness, as the radius of a conical film expands, with the classical dispersion relationship for an inviscid moving liquid film. This approach produces a new long wave solution which accurately matches the measured maximum wavelength swirling conical films generated from nozzles with the smallest orifice diameter. For the nozzle with the largest orifice diameter, the new long wave solution provides the upper bound limit, while the long wave solution for a constant film thickness provides the lower bound limit. These results indicate that temporal instability is the dominating mechanism which generates long Kelvin Helmholtz waves on the surface of a swirling liquid film. The PDPA was used to measure droplet size and velocity in both the near field and far field of the spray. For a constant Reynolds number, an increase in orifice diameter is shown to increase the overall diameter distribution of the spray. In addition, it was found that the probability of breakup, near the axis, decreases for the largest orifice diameter. This is in agreement with the cascading nature of atomization.

A few years ago Covid-19 locked people down at their homes, effectively limiting their social connections and pushing the communicative outlet of the online realm in the forefront. If one wanted to socialize or seek entertainment, there was almost no other choice but to do so via turning to popular or social media. However, with the newly increased frequency of exposure came the question of whether there was also a change in the formation of parasocial relationships formed in isolation and this thesis explores the meaningfulness and longevity of such connections, tracing them before, during and after the pandemic. It also makes note of phenomena such as loneliness, parasocial romance and parasocial breakup, additionally examining the degree of attachment formed to media figures during isolation, as well as their relevance to the public. To achieve that, the empirical portion of this study consists of a survey in which 114 participants had to answer questions relating to isolation and parasocial behaviour. Additionally, for the purposes of the thesis two social media creators were contacted for interviews and were asked to share their views on parasocial interactions and attachments as they observed them in isolation from the other side of the connection. On the basis of previously existing separate research in parasocial relations and isolation six hypotheses were formed in this thesis relating to people’s online activity, perceived loneliness and financial generosity, as well as the degree of relatability and attachment they felt towards media personae.

No description available.

Design of atomizers for gas-turbine purposes are an important ordeal. The per-formance of the atomizer directly impacts the efficiency of the gas-turbine, andconsequently, the energy extracted from the turbine. Furthermore, the design ofthe atomizer can have an impact on reducing toxic emissions. On a global scale,gas-turbines can be considered crucial for the transition to renewable energy. Forengineers, designing of atomizers are however challenging. Turbulent flow, multi-phase interaction and chemical reactions are some of the complex physics involvedwhich has to be taken into consideration when designing the atomizer. Engineerstraditionally uses experimental testing for investigation of designs, and it is still verymuch a useful methodology. However, numerical simulations and CFD have recentlygained popularity due to being a more cost-effective methodology. In this work, theprocedure for designing a prefilm atomizer involving CFD (single phase model andmulti phase model) and experimental testing is documented. The details of the twonumerical models (a single phase model and a multi phase model) has been doc-umented as well as the experimental setup. The single phase model is used for aparametric study and experimental testing is used for evaluation of designs. Themulti phase model is aimed to replicate the experimental results. The validity ofthe numerical models and the experimental setup are discussed, and possible mod-ifications of the methodology for future studies are suggested. Finally, suggestionsfor how the prefilmer should be designed is suggested.

No description available.

Mid-Late Triassic-age alkali-basalt dikes were emplaced along the coast of New England between 240-200 Ma. Known as the Coastal New England (CNE) magmatic province, this dike swarm is the immediate magmatic predecessor to the formation of the Central Atlantic Magmatic Province large igneous province at 201 Ma and the breakup of Pangea. The intent of this study is to determine the melt source and mechanisms for melting which produced the Triassic coastal dikes. To achieve this goal, major and trace element compositions were analyzed for 53 CNE dikes from Maine and Nova Scotia. Radiogenic Nd-Sr-Pb-Hf ratios, representing some of the first 176Hf/177Hf data for CNE, are reported for 12 of the dikes. Taken together, the compositional data implicate melting of a deep mantle source that is relatively enriched in incompatible elements, such as a mantle-plume similar to those hypothesized as the source of melting in modern ocean-island basalts (i.e. Hawaii). Dike compositions are inconsistent with melts generated at typical spreading-center ridges (i.e. MORB). Modeling suggests that CNE melts ascended through thick continental crust, consistent with the incipient stages of rifting of Pangea, as evidenced by a heterogeneous mix of melting and crystallization depths, between 0-70km, with no clear geographic pattern. Radiogenic isotope data are relatively consistent and represent a mixture between HIMU, EMI and DMM mantle reservoirs, implying component consisting of relict subducted oceanic crust (or other similarly evolved material). CNE magmatism may have contributed to the breakup of Pangea by destabilizing the lower crust in the limited local area where it erupted, but its true relationship with the breakup of Pangea and later CAMP event requires more study. / Master of Science / Approximately 200-250 million years ago, hundreds of sheets of lava, called dikes, erupted along what is today the coast of New England. As these volcanic dikes rose up from the Earth’s mantle, they traveled along cracks and weak areas of the Earth’s crust. Today, these dikes are found along the New England coast as far south as Rhode Island and as far north as Nova Scotia, Canada. Based on the similarity of their geochemistry and petrology, as well as their geologic age and geography of their eruption, geologists group these dikes and similar volcanics together as a single, related magmatic event. This magmatic event produced the Coastal New England (CNE) magmatic province. 250 million years ago, the coast of New England was actually an interior part of the supercontinent known as Pangea. Around 250 m.yr. ago, Pangea slowly began rifting apart, which is when CNE volcanism began. By 200 m.yr. ago, Pangea had broken up, and CNE volcanism had ended. Further complicating the story, a large-igneous province (LIP) also erupted 200 m.yr. ago. Known as the Central Atlantic Magmatic Province (CAMP), this volcanism consisted of enormous volumes of lava that flooded over the entire east coast of the United States. The intent of this study is to determine what geological conditions led to the CNE volcanism. By learning which part of the Earth melted and why, CNE volcanism’s role in the breakup of Pangea, and the much larger CAMP eruptions that coincided with it, will become clearer. For instance, did the geologic events that resulted in CNE volcanism contribute to the breakup of Pangea, or did the breakup of Pangea cause CNE volcanism followed by CAMP volcanism? To achieve this goal, the geochemical compositions of 53 CNE dikes from Maine and Nova Scotia were analyzed. Radiogenic Nd-Sr-Pb-Hf ratios for a subset of the dikes (12) were also analyzed. This study presents some of the first radiogenic hafnium data for rocks from CNE. The data indicate that the melting which produced the CNE dikes began in the deep mantle, similar to the melting of mantle plumes beneath modern ocean-islands such as Hawaii. In contrast, shallow mantle melting, like the melting at mid-ocean ridges where oceanic crust is produced, is not consistent with the geochemical evidence presented for CNE in this study. Modeling suggests that CNE magmas rose through thick continental crust, which caused them to begin forming crystals at relatively high depths. Radiogenic isotope data suggests that part of the mantle that melted was old, recycled oceanic crust or similar mantle material. CNE magmatism may have contributed to the breakup of Pangea by destabilizing the lower crust in the limited local area where it erupted, but its true relationship with the breakup of Pangea and later CAMP event requires more study.

The increasing reliance on space infrastructure and its rapid expansion necessitate the development and enhancement of tools for space debris and fragmentation research. Accurate prediction of the risks associated with satellite fragmentation requires comprehensive understanding of the dynamics involved. To address this need, the widely used NASA Standard Breakup Model (SBM) is employed in this thesis to predict fragment characteristics resulting from breakup events. Additionally, a novel method is introduced to determine the direction of these fragments, something not directly covered by the SBM. Furthermore, the principle of kinetic gas theory is applied to calculate the overall, long-term collision risk between debris and a predetermined satellite population. The results from this reveal the limitations of the SBM in accurately simulating fragmentations for certain satellite types. However, the newly implemented fragment directionality method aligns well with observed data, suggesting its potential for further research. Similarly, the risk model exhibits strong correspondence with ESA's MASTER, a model used for assessing collision risks with debris, with the deviations likely due to different impact velocity models used. Finally, the validated fragmentation and risk models are combined, and the combined model is used to analyse a real-world fragmentation event. / Det ökande beroendet av rymdinfrastruktur, samt dess snabba expansion kräver utveckling och förbättring av verktyg för forskning och analys kring rymdskräp och fragmentering. För att förstå risken förknippad med satellitfragmentationer så krävs förståelse för den involverade dynamiken. För att tillgodose detta används NASA:s Standard Breakup Model (SBM) i denna avhandling för att bestämma fragmentegenskaper som bildas från olika sorters fragmentationshändelser. Dessutom introduceras en ny metod för att bestämma riktningen för dessa fragment, något som inte direkt täcks av SBM. Dessutom tillämpas principen för kinetisk gasteori för att beräkna den totala, långsiktiga kollisionsrisken mellan rymdskrot och en förutbestämd satellitpopulation. Resultaten från detta avslöjar SBM:s begränsningar när det gäller att simulera fragmenten för vissa satellittyper. Hursomhelst så kan man se att den nyligen implementerade fragmentriktningsmetoden stämmer väl överens med den observerade datan, vilket tyder på dess potential för ytterligare forskning. På samma sätt uppvisar riskmodellen överensstämmelse med ESA:s MASTER, en modell som används för att bedöma kollisionsrisker med rymdskrot, där avvikelser sannolikt beror på att olika kollisionshastighetmodeller används. Slutligen kombineras de validerade fragmenterings- och riskmodellerna, som sedan används för att bidra med analyser till en riktig fragmentationshändelse.

Prieš rengiant kelių investicinius projektus surenkami ir detaliai analizuojami esami kelių eksploatacinių rodiklių duomenys ir jų reglamentuotų norminių reikšmių atitiktis. Baigiamajame darbe išanalizuoti automobilių kelių asfaltbetonio dangos būklės, patikimumo bei šių rodiklių gavimo ir apdorojimo metodai. Pateikiamas automobilių kelių asfaltbetonio dangos reikiamų eksploatacinių rodiklių teorinis pagrindimas, reglamentuotos norminės reikšmės bei eksploatacinių rodiklių gerinimo svarba. Naudojantis tyrimų, atliktų Lietuvos svarbiausiuose magistraliniuose keliuose A1 Vilnius – Kaunas - Klaipėda ir A5 Kaunas – Marijampolė - Suvalkai, duomenimis, atlikta pagrindinių eksploatacinių rodiklių - dangos lygumo, rato su danga sukibimo koeficiento, dangos suirimo masto rodiklio, konstrukcijos deformacijos modulio bei provėžų gylio analizė ir šių rodiklių kitimas laiko atžvilgiu. Nustatyta dangos būklę apibūdinančių rodiklių sietis. Analizės pagrindu pateikti rekomenduojami leistinieji dangos lygumo rodikliai. Pateiktos išvados ir rekomendacijos. Baigiamojo darbo aprašomojo skyriaus apimtis – 89 psl., 17 lentelių, 90 paveikslų, 44 bibliografiniai šaltiniai. / Before the preparation of highway investment projects, the available data of highway maintenance indices are collected and analysed and their conformity with the standard values is established. The thesis deals with the analysis of reliability of the condition of highway asphalt concrete pavement and the indices collection and procession methods. The thesis includes the theoretical grounding of the necessary maintenance indices of the highway asphalt concrete pavement, standard values and the importance of improvement of the maintenance indices. Using the data of the testing performed in the main Lithuanian highways A1 Vilnius – Kaunas - Klaipėda and A5 Kaunas – Marijampolė - Suvalkai, the analysis of the basic maintenance indices, i.e. pavement smoothness, wheel adherence coefficient, pavement breakup degree index, construction deformation module and furrow depth, and the change of such indices in the terms of time has been carried out. The link between the indices characterising the condition of the pavement has been determined. Basing on the analysis, the recommended permitted pavement smoothness indices are presented. The conclusions and recommendations of the thesis are introduced. Theses consist of: 89 p. text without appendixes, 90 pictures, 17 tables, 44 bibliographical entries.