Aurora Animation considering the force applied tocharged-particles in an electromagnetic field

コンピュータグラフィクス(CG)において,大気光学現象の可視化は映画やゲームなどエンターテインメント分野で需要があり,これまでに多くの研究が行われてきた.従来のオーロラのレンダリングは静止画が主体であり,オーロラのスプリッティングやカールといった動きまで含めたレンダリングは実現できていない.この問題を解決するため,本論文では荷電粒子群の電場シミュレーションを用いたオーロラのアニメーション手法を提案する.すなわち,荷電粒子群によって形成される電場を解析的に求め,荷電粒子が電場と地球磁場の双方から受ける力を考慮してオーロラの動きを表示するVisualizing atmospheric optical phenomena is required in the entertainment industry such as Cinemas and Games, and a lot of researches have been done so far in the field of Computer graphics (CG). In this research, we focus on dynamic scenes of aurora. Traditional rendering methods of aurora cannot generate the motion such as a splitting and a curl. To solve the problem, we take into account the motion of charged particles that generate aurora by simulating the electric field of the charged particles. That is, we analytically solve the electric field of the charged particles, and calculate the motion of the aurora considering the force from both the electric field and the earth's magnetic field

Ion Velocity Distributions in Inhomogeneous and Time-dependent Auroral Situations

Aurorae often break down into elongated filaments parallel to the geomagnetic field lines (B) with cylindrically symmetric structures. The object of this thesis is to study the ion distribution function and transport properties in response to the sudden introduction of a radial electric field (E) in such a cylindrical geometry. Both collision-free and collisional situations are considered. The thesis starts by solving a collision-free problem where the electric field is constant in time but increases linearly with radius, while the initial ion density is uniform in space. The attendant Boltzmann equation is solved by tracking the ions back in time, thereby using the temporal link between the initial position and velocity of an ion and its position and velocity at an arbitrary time and place. Complete analytical solutions show that the ion distribution function is a pulsating Maxwellian in time, and all transport parameters (e.g., bulk speed, temperature, etc.) oscillate in time but independent of radius. If the ion-neutral collisions are taken into account by employing a simple relaxation model, analytical solutions are also obtained. In this case, the ion distribution function can be driven to horseshoe shapes which are symmetric with respect to the ExB direction. The bulk parameters evolve in a transition period of the order of one collision time as they go from oscillating to the non-oscillating steady state. In more realistic electric field structures which are spatially inhomogeneous but still constant in time, a generalized semi-numerical code is developed under collision-free conditions. This code uses a backmapping approach to calculate the ion velocity distribution and bulk parameters. With arbitrarily selected electric field rofiles, calculations reveal various shapes of ion velocity distribution functions (e.g., tear-drop, core-halo, ear-donut, etc). The associated transport properties are also obtained and discussed. Under both collision-free and collisional conditions, the effect of the density inhomogeneities at the initial time is studied in an electric field which is proportional to radius and constant in time. With two profiles of the initial ion density for the collision-free case, and one profile for the collisional case, complete analytical solutions are obtained. The results reveal that the distribution function and the bulk properties are now strongly dependent on radial position. If the radial electric field is unable to stay constant with time but modulated by in-coming charged particles, a fluid formalism is used to study the excitation of several plasma waves under different kinds of initial conditions. These identified waves include the ion cyclotron oscillation, the ion and electron upper-hybrid oscillations, and the lower-hybrid oscillation. The results of this thesis are expected to be applicable to high-resolution observations. Future work should also include the mirror effect and the formation of conics in velocity space. Finally, the velocity distributions obtained in this thesis could trigger various plasma instabilities, and this topic should also be looked at in the future

Monte Carlo simulation of the Jovian plasma torus interaction with Io’s atmosphere and the resultant aurora during eclipse

textIo, the innermost Galilean satellite of Jupiter, exhibits a wide variety of complex phenomena such as interaction with Jupiter’s magnetosphere, volcanic activity, and a rarefied multi-species sublimating and condensing atmosphere with an ionosphere. Io’s orbital resonance with Jupiter and the other Galilean satellites produces intense tidal heating. This makes Io the most volcanically active body in the solar system with plumes that rise hundreds of kilometers above the surface. In the present work, the interaction of Io’s atmosphere with the Jovian plasma torus is simulated via the Direct Simulation Monte Carlo (DSMC) method and the aurora produced via electron-neutral excitation collisions is examined using electron transport Monte Carlo simulation. The electron-transport Monte Carlo simulation models the electron collisions with the neutral atmosphere and their transport along field lines as they sweep past Io, using a pre-computed steady atmosphere and magnetic field. As input to the Monte Carlo simulation, the neutral atmosphere was first modeled using prior 2D sunlit continuum simulations of Io’s atmosphere produced by others. In order to justify the use of a sunlit atmosphere for eclipse, 1D two-species (SO2 and a non-condensable) DSMC simulations of Io’s atmospheric dynamics during and immediately after eclipse were performed. It was found that the inclusion of a non-condensable species (SO or O2) leads to the formation of a diffusion layer which prevents rapid collapse. The degree to which the diffusion layer slowed the atmospheric collapse was found to be extremely sensitive to both the initial non-condensable mole fraction and the reaction (or sticking) probability on the surface of the “non-condensable”. Furthermore, upon egress, vertical stratification of the atmosphere occurred with the non-condensable species being lifted to higher altitudes by the rapid sublimation of SO2 as the surface warms. Simulated aurorae (specifically the [OI] 6300 Å and the S2, SO, and SO2 molecular band emission in the middle ultraviolet) show good agreement with observations of Io in eclipse and an attempt was made to use the simulations to constrain the upstream torus electron temperature and Io’s atmospheric composition, structure, and volcanic activity. It is found that the position of the bright [OI] 6300 Å wake spot relative to Io’s equator depends on the position of Io relative to the plasma torus’ equator and the asymmetric electron number flux that results. Using HST/STIS UV-Vis spectra, the upstream electron temperature is weakly constrained to be between 3 eV and 8 eV depending on the flux of a low energy (35 eV), non-thermal component of the plasma (more non-thermal flux requires lower thermal plasma temperatures to fit the spectrum). Furthermore, an upper limit of 5% of the thermal torus density (or 180 cm−3 based on the Galileo J0 plasma density at Io) is obtained for the low energy non-thermal component of the plasma. These limits are consistent with Galileo observations of the upstream torus temperature and estimates for the the non-thermal component. Finally, plume activity and S2 content during eclipse observations with HST/STIS were constrained by examining the emission intensity along the spatial axis of the aperture. During the August 1999 UV-Vis observations, the auroral simulations indicate that the large volcanoes Pele and Surt were inactive whereas Tvashtar was active and that Dazhbog and possibly Loki were also actively venting gas. The S2 content inferred for the large Pele-type plumes was between 5% (Tvashtar) and 30% (Loki, if active), consistent with prior observations (Spencer et al., 2000; Jessup et al., 2007). A 3D DSMC simulation of Io’s sublimation and sputtered atmosphere including photo- and plasma-chemistry was developed. In future work these atmospheric simulations will replace the continuum target atmosphere in the auroral model and thus enable a better match to the observed high altitude auroral emission. In the present work, the plasma interaction is modeled by a flux of ions and electrons which flow around and through Io’s atmosphere along pre-computed fields and interact with the neutral gas. A 3D DSMC simulation of Io’s atmosphere assuming a simple thermal model for the surface just prior to ingress into eclipse and uniform frost coverage has been performed in order to understand how Io’s general atmospheric dynamics are affected by the new plasma model with chemistry and sputtering. Sputtering was found to supply most of the nightside atmosphere (producing an SO2 column of ~5×1013 cm−2); however, the dense dayside sublimation atmosphere was found to block sputtering of the surface. The influence of the dynamic plasma pressure on the day-to-night circumplanetary flow was found to be quite substantial causing the day-to-night wind across the dawn terminator to flow slightly towards the equator. This results in a region of high density near the equator that extends far (~2000 km for the condensable species) onto the nightside across the dawn terminator. Thus, even without thermal lag due to rotation or variable surface frost, highly asymmetric equatorial column densities relative to the subsolar point are obtained. The non-condensable O2, which is a trace species on the dayside, is the dominant species on the nightside despite increased SO2 sputtering because the loss rate of O2 is slow. Finally, a very intriguing O2 flow feature was observed near the dusk terminator where the flow from the leading hemisphere (pushed by the plasma) meets the flow from the dayside trailing hemisphere. Since the O2 does not condense on the surface, it slowly convects towards the poles and then back onto the nightside, eventually to be dissociated or stripped away by the plasma.Aerospace Engineerin

アーティスト制御可能なオーロラシミュレーションに関する研究

筑波大学修士(情報学)学位論文・平成30年3月23日授与(39508号

Espalhamento elástico de elétrons por isômeros de C2H2CL2, C4H4N2 e C3H3NX (X=NH, O, S)

Orientador: Prof. Dr. Márcio Henrique Franco BettegaDissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências Exatas, Curso de Pós-Graduação em Física. Defesa: Curitiba, 27/02/2012Bibliografia: fls. 95-103Resumo: Neste trabalho apresentamos seções de choque de espalhamento elástico de elétrons pelos isômeros C2H2Cl2, C4H4N2 e C3H3NX (onde X=NH, O, S). Os cálculos de espalhamento foram efetuados na aproximação de núcleos fixos, com uso do método multicanal de Schwinger implementado com pseudopotenciais de Bachelet, Hamann e Schl¨uter, e nas aproximações estático-troca e estático-troca mais polarização. Para os três isômeros C2H2Cl2 apresentamos seções de choque integrais, de trasferência de momento e diferenciais. O procedimento Born-closure é empregado a fim de levar em conta o efeito do momento de dipolo. As ressonâncias encontradas tiveram suas posições comparadas aos valores experimentais. Discutimos ainda o efeito isômero, que consiste em diferenças apresentadas pelas seções de choque de cada molécula. Para os três isômeros C4H4N2 apresentamos seções de choque integrais. As ressonâncias são identificadas e caracterizadas. Suas posições são comparadas com os resultados encontrados na literatura. Cálculos de estrutura eletrôncia também são efetuados para ajudar na interpretação dos resultados. Os seis sistemas C3H3NX, onde X=NH, O, S tiveram suas seções de choque integrais apresentadas. As ressonâncias são identificadas e comparadas ao resultado experimental existente. Também discutimos as diferenças nas características das ressonâncias de cada molécula. Para todos os sistemas estudados, nossos resultados concordam bem com os reportados experimentalmente. Foi desenvolvido ainda um novo esquema para a construção do espaço de configurações.Abstract: In this work we present cross sections for elastic electron scattering from C2H2Cl2, C4H4N2 and C3H3NX (where X=NH, O, S) isomers. The scattering calculations were done in the fixed-nuclei approximation, with the Schwinger multichannel method implemented with pseudopotentials of Bachelet, Hamann and Schl¨uter, in the static-exchange and in the static-exchange plus polarization approximations. For the three C2H2Cl2 isomers, we present integral, momentum transfer and differential cross sections. The Born-closure procedure is employed in order to consider the dipole moment effect. The identified resonances had their positions compared to the experimental values. We also discuss the isomer effect, which consists in differences presented in the cross sections of each molecule. For the three C4H4N2 isomers, we present integral cross sections. The resonances are identified and characterized. Their positions are compared to the results found in the literature. Electronic structure calculations were done as well, in order to help in the interpretation of the results. The six systems C3H3NX, where X=NH, O, S had their integral cross sections presented. The resonances are identified and compared to the existing experimental result. We also discuss the differences in the characteristics of the resonances of each molecule. For all the studied systems, our results agree well with the ones reported experimentally. We also developed a new scheme for the construction of the configuration space. i

Espectro de ressonância de forma do monômero de ácido acrílico, suas equivalentes metiladas e seus dímeros

Orientador: Prof. Dr. Márcio Henrique Franco BettegaDissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências Exatas, Programa de Pós-Graduação em Física. Defesa : Curitiba, 31/08/2020Inclui referências: p. 131-141Resumo: Neste trabalho são apresentadas as seções de choque integrais e diferenciais de espalhamento elástico de elétrons de baixa energia pelos monômeros de ácido acrílico (C3H4O2), dímeros de ácido acrílico (C6H8O4) e pelas equivalentes metiladas do ácido acrílico (ácido crôtonico trans, ácido metacrílico, acrilato de metila - C4H6O2). Os dados obtidos para as posições das ressonâncias do ácido acrílico são comparados com dados experimentais de DEA. Infelizmente não foram encontrados dados teóricos ou experimentais relativos (diretamente ou indiretamente) ao espalhamento de elétrons para as outras moléculas. Foi feita uma análise sobre a interação entre o grupo vinil (C2H3) e o grupo carboxílico (COOH) nos monômeros de ácido acrílico como forma de investigar a origem de suas ressonâncias. Fez-se uma análise relativa aos efeitos da metilação nas posições e larguras das ressonâncias, e nos padrões oscilatórios das seções de choque diferenciais dos monômeros do ácido acrílico por meio de comparação com suas equivalentes metiladas. Também se investigou o impacto das ligações de hidrogênio nas seções de choque de complexos moleculares a partir da comparação entre os monômeros de ácido acrílico com seus dímeros. Os cálculos de seção de choque foram feitos a partir do método multicanal de Schwinger, com parte dos cálculos sendo feitos com a implementação de pseudopotenciais e a outra parte sendo do tipo all-electron. A razão para a realização de cálculos all-electron é a de testar a eficiência dos orbitais virtuais de valência (VVO's), que de momento não estão implementados com pseudopotenciais, para calcular as seções de choque de simetrias ressonantes. Palavras-chave: Espalhamento de elétrons, Método Multicanal de Schwinger, Ácido Acrílico, Efeitos da Metilação, Orbitais Virtuais de Valências.Abstract: In this work we present integral and differential low energy electron elastic scattering cross sections from acrylic acid monomers (C3H4O2), acrylic acid dimers (C6H8O4) and the methylated equivalents of acrylic acid (crotonic acid trans, methacrylic acid and methyl acrylate - C4H6O2). The results obtained for the positions of the resonances of acrylic acid are compared with experimetal DEA results. Unfortunately, no theoretical or experimental results (direct or indirect) were found for the electron scattering by the other molecules. An analysis about the interaction of the vinyl group (C2H3) with the carboxylic group (COOH) was done in the monomers of acrylic acid as a way to investigate the origins of its resonances. An analysis relatated to the methylation effects in the positions and widths of the resonances, and in the oscillatory patterns in the differential cross sections of the monomers of acrylic acid was done via comparison with its methylated equivalents. It was also investigated the impact of hydrogen bonds in the cross section of molecular complexes through comparison between the monomers of acrylic acid with its dimers. The cross section calculations were done through the Schwinger multichannel method, with part of the calculations being done with the pseudopotential implementation and the other part being an all-electron type. The reason for the all-electron calculations was to test the efficiency of the virtual valence orbitals (VVO's), which in the moment are not implemented with pseudopotentials, to calculate the cross sections of resonant symmetries. Keywords: Electron Scattering, Schwinger Multichannel Method, Acrylic Acid, Methylation Effects, Virtual Valence Orbitals

Theming Prehistory: Institutionalizing the Media of Deep Time in the Museum and Beyond

This dissertation project explores the convergence of museum and themed entertainment design through the lens of Deep Time—a concept that has important implications for connecting mass communication to scholarship on the Anthropocene. Based on case studies that represent a variety of exhibition contexts, I consider how paleontology, evolutionary theory, art history and archaeology function as public histories that structure and mobilize our understanding of the remote past. I examine several US-based sites: the George C. Page Museum at the La Brea Tar Pits in Los Angeles, the Evolving Planet exhibit at the Field Museum of Natural History in Chicago, and the Dinosaur attraction at Disneyʼs Animal Kingdom Theme Park in Orlando, Florida. In France, I conduct research on the replicated cave paintings of Lascaux IV and Caverne du Pont-d'Arc, at the International Centre for Parietal Art in Montignac and Grotte Chauvet 2 in Ardèche.These sites explore Deep Time as a theme that links media, temporality and ecology; I consider how this theme is implemented in designed spaces, and how these spaces go on to shape our shared scientific imagination. I conduct in-person research at each site; this entails formal analysis of attractions and their host institutions, ethnographic observation and consultation with attraction personnel. This in-person research is framed by spatial and temporal approaches to film and media theory, as well as key texts in museum and themed entertainment studies. The research sites represent distinct approaches to spatializing and temporalizing information, and each uses a unique combination of aesthetic and performative strategies in order to construct unique relationships between visiting publics, institutions and industries. These relationships imply a range of social, cultural and political contexts for exploring the intersection of media, temporality and environment, and each site proposes novel reconstructed environments and experiences as a basis for engaging the remote past and ultimately the Anthropocen

Between Noise and Song: The Contested Voice in Opera after Wagner

This project argues that changes to operatic vocal writing in the late nineteenth century prompted Austro-German operagoers to radically expand their understandings of vocal sound in the years around 1900. As post-Wagnerian composers granted greater melodic expression to the orchestra, and increasingly exploited non-melodic vocal effects such as groans and cries, fierce debates were launched about what and how opera’s voices ought to communicate. I track the fallout from these developments, drawing on an archive of journalistic music criticism, vocal treatises, and singer memoirs, as well as under-examined sources such as letters to newspapers, satire, poetry, and cartoons. Listeners looked far beyond the theater to interpret the shifting vocal terrain, enlisting operatic voices in such urgent fin-de-siècle projects as the fortification of human agency amidst industrial creep and the development of a middle-class resistance to elite aesthetics. By showing how they used operatic voices to comprehend and to construct the world around them—especially through emerging, abstract notions of “voice”—I not only provide new examples of the ways in which musical experiences can condition political thought, but reveal several new dimensions to the role of opera in sociopolitical change