The objective of this project is the development of a mission analysis tool for the nanosatellite company GomSpace Sweden. Although there are many existing software, they can be quite complicated and time consuming to use. The goal of this work is to build a simple app to be used at the earliest stages of space missions in order to obtain key figures of merit quickly and easily. By comparing results, assessing the feasibility of customer needs, analysing how various parameters affect each other, it enables immediate deeper understanding of the implications of the main design decisions that are taken at the very beginning of a mission. The tool shall aid the system engineering process of determining orbit manoeuvre capability specifically for CubeSat electric propulsion systems taking into account the most relevant factors for perturbation in Low Earth Orbit (LEO), i.e. atmospheric drag and Earth’s oblateness effects. The manoeuvres investigated are: orbit raising from an insert orbit to an operating orbit, orbit maintenance, deorbiting within the space debris mitigation guidelines and collision avoidance within the 12 to 24 hours that the system has to react. The manoeuvres cost is assessed in terms of Delta v requirements, propellant mass and transfer times. The tool was developed with MATLAB and packaged as a standalone Linux application. / Målet med detta examensarbete var att utveckla ett verktyg för missionsanalys för nanosatellitföretaget GomSpace Sweden. Det finns många andra mjukvaror för att nå samma mål men de är ofta komplicerade och tidskrävande. Det specifika målet var således att skapa en enkel applikation som kan användas i de tidiga stegen av utformning av rymduppdrag för att snabbt och enkelt få fram viktiga parametrar. Genom att jämföra resultat, uppskatta genomförbarheten av kundbehov och analysera hur olika parametrar påverkar varandra kan omedelbar förståelse erhållas rörande påverkan av designbeslut som tas i början av rymduppdragen. Verktyget ska stödja systemingenjörsprocessen genom att uppskatta banförflyttningskapacitet för elektriska framdrivningssystem för CubeSats och ta i beaktande de mest relevanta faktorerna gällande störningar i låg jordbana (LEO), i.e. atmosfäriskt motstånd och effekterna av Jordens form. De undersökta manövrarna är: banhöjning från injektionsbana till operationell bana, banunderhåll, bansänkning som följer riktlinjerna för rymdskrot och kollisionsundvikande inom de 12 till 24 timmar som systemet har på sig att reagera. Kostnaden för manövrarna är uppskattade genom DeltaV-krav, massan av bränslet och förflyttningstider. Verktyget utvecklades med MATLAB och paketerades som en fristående applikation i Linux.

In nature, microscopic surface textures impact useful function, such as the drag reduction of shark skin (Dean & Bhushan, 2010) and superhydrophobicity of the lotus leaf(Pan, Kota, Mabry, & Tuteja, 2013). In this study, we explore these phenomena by re-creating microscopic surface textures via the method of interfacial flow instability in drying polyvinylidene fluoride (PVDF) acetone solutions. In general, PVDF films can be made using either spin coating or electrospray deposition with various weight concentrations in acetone. In order to study the morphology of the porous structure of PVDF films, wet deposition samples were fabricated by spin coating or near-field electrospray. Possible theories are discussed and examined to explain the formation of these porous structures resulting in development of a well-controlled method to create porous PVDF films with various pore sizes and pore densities. All samples are characterized and found to exhibit superhydrophobicity and drag reduction. To connect porous PVDF film morphology to the established field of dry particle fabrication, PVDF particle synthesis by far-field electrospray is also reviewed and discussed. An established method to generate polymer particles of different morphologies in other polymers (Almeria-Diez, 2012) by electrospray drying is confirmed using PVDF as well. Due to the ability of scalable and re-configurable electrospray, the microscopic surface textures can be applied to areas of any size to reduce drag or impart water-repelling properties.

Due to mass and volume constraints on planetary missions, the development of control techniques that do not require fuel are of big interest. For those planets that have a dense enough atmosphere, aerodynamic drag can play an important role. The use of atmospheric differential drag for formation keeping was first proposed by Carolina L. Leonard in 1986, and has been proven to work in Earth atmosphere by many missions. Moreover, atmospheric drag has been used in the Mars atmosphere as aerobraking technique to decelerate landing vehicles, and to circularize the orbit of the spacecraft. Still, no literature was available related to formation flying on Mars. To analyze the use of differential drag on the Mars atmosphere, the researcher accessed the two high resolution models available: NASA’s Mars-GRAM and ESA’s Mars Climate Database. These models allowed the simulation of conditions that a spacecraft would experience while in orbit around the planet. To explore the feasibility, the researcher first conducted a study where Mars atmosphere density was compared to Earth atmosphere, determining its applicability. Then, a simulation using MATLAB® was conducted, using a Keplerian two-body problem including the effects of Mars zonal harmonics (i.e. J2) and drag perturbations. Two 6U CubeSat were used in the simulation with deployable drag plates of different sizes, giving the possibility of having five differential drag scenarios as means of formation control. The conclusions showed that, although with some limitations, the use of differential drag as means of autonomous formation flying and proximity operations control is feasible using proven techniques previously validated in Low Earth Orbit. Lyapunov control was selected as the control strategy, where three different methods were evaluated and compared.

The bell-shaped lift distribution (BSLD) wing design methodology advanced by Ludwig Prandtl in 1932 was proposed as providing the minimum induced drag. This study used this method as the basis to analyze its characteristics in two wing formation flight. Of specific interest are the potential efficiency savings and the optimal positioning for formation flight. Additional comparison is made between BSLD wings and bird flight in formation. This study utilized Computational Flow Dynamics (CFD) simulations on a geometric modeling of a BSLD wing, the Prandtl-D glider. The results were validated by modified equations published by Prandtl, by CFD modeling published by others, and by Trefftz plane analysis. For verification, the results were compared to formation flight research literature on aircraft and birds, as well as published research on non-formation BSLD flight. The significance of this research is two part. One is that the BSLD method has the potential for significant efficiency in formation flight. The optimal position for a trailing wing was determined to be partially overlapping the leading wing vortex core. For a BSLD wing these vortices are located inboard from the wingtips resulting in wingtip overlap and have a wider impact downstream than the elliptical lift distribution (ELD) wingtip vortices. A second aspect is that avian research has traditionally been studied assuming the ELD model for bird flight, whereas this study proposes that bird flight would be better informed using the BSLD.

Se entiende a las drags queens como hombres caracterizados en base a la figura femenina para la realización de performances en un espacio y momento establecido. En Lima Metropolitana, existen apropiaciones simbólicas de elementos extranjeros y peruanos que las drags queens han utilizado para su dragqueenismo: vestimentas, expresiones, baile y vocabulario. Esto ha dado lugar a que algunos actores puedan ser reconocidos y visibilizados en medios de comunicación masivos; mientras que otros artistas, solo pueden ser reconocidos en espacios cerrados como museos, bares de “ambiente” y otros que impiden su visibilidad en el espacio público. Se reconoce que la performance de las drags queens se ha desplazado y es visibilizada por más público; sin embargo, aún se observan obstáculos en el desarrollo y entendimiento de arte que desafía la norma: censura y violencia. Ante este contexto, se desarrolla una intervención gráfica efímera de un espacio público llamado Glam que busca presentar el arte de las drags queens junto a dos aspectos fundamentales para entender el quid y la importancia de este medio artístico: símbolo de libertad de expresión y disciplina artística. Con ello, el proyecto busca divulgar, junto a una gráfica inspirada en la estética glamurosa de las drags queens, sobre el movimiento drag limeño y visibilizar la performance de los artistas locales. / Drag queens are defined as men who are characterized based on the Western woman figure to perform in an established space and time. In the Lima Metropolitan Area, dragqueenismo has been built with the appropriation of specific symbols of foreign and Peruvian elements that drag queens have used: clothing, expressions, dance, and vocabulary. This action has given rise to some actors being recognized and visible in the mass media and even by the conservative spheres of Lima; however, other artists can only be recognized in closed spaces such as museums, queer bars, and other places that prevent their visibility in the mass public spectrum. There is a displacement of the performance of drag queens from closed places to public ones; however, acts of censure or violence block the opportunity to understand this art. Given this context, the project Glam develops a brief graphic intervention of public space to present the art of drag queens that presents two fundamental aspects to understand the reason and the importance of this artistic medium: symbol of freedom of expression and artistic discipline. This project seeks to divulge and make visible the Lima drag movement along with a graphic inspired by the glamorous aesthetics of drag queens.

<p> Working within the framework of the linearized Boltzmann equation for the conduction electrons the existing theoretical treatments of ultrasonic attenuation in metals are extended to include realistic descriptions of the electronic structure and electron-lattice interaction. A variational solution of the Boltzmann equation which allows the inclusion of phonon drag effects is derived. An anisotropic scattering time solution is also presented. Both of these solutions are applied to calculation of the attenuation coefficient in pure metals and dilute alloys. </p> <p> The theory of the effects of electron-electron collisions on the ultrasonic attenuation in metals is also examined. </p> / Thesis / Doctor of Philosophy (PhD)

This paper presents a study on the translation of slang used by drag queens. The study aims to examine how the slang used by drag queens in RuPaul’s Drag Race season 12 is translated into Japanese. The translation strategies used are revealed and the faithfulness of the translation is discussed. Both the original and translated expressions, jargon and words used by drag queens in RuPaul’s Drag Race season 12 were gathered from the first three episodes. The data was then grouped based on the translation strategy and discussed further regarding the effectiveness of the translation strategy and faithfulness of the translation itself with the help of Nida’s theory of dynamic equivalence. The results show that translation by loan, excluding the omission, was the most used translation strategy, but its success hinges on the familiarity of the target audience. Together with substitution, they were the most successful strategies regarding the faithfulness of the translation and the preservation of the slang. Softening, employed to adapt informal and vulgar expressions, risked losing the original slang, and modulation also less successful in preserving it. Paraphrase and explicitation were less successful in retaining the slang nuances but aligned with Nida’s dynamic equivalence which emphasizes the meaning.

Editorial on the Research Topic. Physics and Geomorphology of Sand Ripples on Earth and in the Solar System.

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No description available.