This concept of calculating, optimizing, and utilizing a trajectory known as a ``Free Return Trajectory" to facilitate spacecraft rendezvous with Near-Earth Asteroids is presented in this dissertation. A Free Return Trajectory may be defined as a trajectory that begins and ends near the same point, relative to some central body, without performing any deterministic velocity maneuvers (i.e., no maneuvers are planned in a theoretical sense for the nominal mission to proceed). Free Return Trajectories have been utilized previously for other purposes in astrodynamics, but they have not been previously applied to the problem of Near-Earth Asteroid rendezvous. Presented here is a series of descriptions, algorithms, and results related to trajectory initial guess calculation and optimal trajectory convergence. First, Earth-centered Free Return Trajectories are described in a general manner, and these trajectories are classified into several families based on common characteristics. Next, these trajectories are used to automatically generate initial conditions in the three-body problem for the purpose of Near-Earth Asteroid rendezvous. For several bodies of interest, example initial conditions are automatically generated, and are subsequently converged, resulting in feasible, locally-optimal, round-trip trajectories to Near-Earth Asteroids utilizing Free Return Trajectories. Subsequently, a study is performed on using an unpowered flyby of the Moon to lower the overall DV cost for a nominal round-trip voyage to a Near-Earth Asteroid. Using the Moon is shown to appreciably decrease the overall mission cost. In creating the formulation and algorithms for the Lunar flyby problem, an initial guess routine for generic planetary and lunar flyby tours was developed. This continuation algorithm is presented next, and details a novel process by which ballistic trajectories in a simplistic two-body force model may be iteratively converged in progressively more realistic dynamical models until a final converged ballistic trajectory is found in a full-ephemeris, full-dynamics model. This procedure is useful for constructing interplanetary transfers and moon tours in a realistic dynamical framework; an interplanetary and an inter-moon example are both shown. To summarize, the material in this dissertation consists of: novel algorithms to compute Free Return Trajectories, and application of the concept to Near-Earth Asteroid rendezvous; demonstration of cost-savings by using a Lunar flyby; and a novel routine to transfer trajectories from a simplistic model to a more realistic dynamical representation. / text

<p>Numerical trajectory optimization is helpful not only for mission planning but also design</p> <p>space exploration and quantifying vehicle performance. Direct methods for solving the opti-</p> <p>mal control problems, which first discretize the problem before applying necessary conditions</p> <p>of optimality, dominate the field of trajectory optimization because they are easier for the</p> <p>user to set up and are less reliant on a forming a good initial guess. On the other hand,</p> <p>many consider indirect methods, which apply the necessary conditions of optimality prior to</p> <p>discretization, too difficult to use for practical applications. Indirect methods though provide</p> <p>very high quality solutions, easily accessible sensitivity information, and faster convergence</p> <p>given a sufficiently good guess. Those strengths make indirect methods especially well-suited</p> <p>for generating large data sets for system analysis and worth revisiting.</p> <p>Recent advancements in the application of indirect methods have already mitigated many</p> <p>of the often cited issues. Automatic derivation of the necessary conditions with computer</p> <p>algebra systems have eliminated the manual step which was time-intensive and error-prone.</p> <p>Furthermore, regularization techniques have reduced problems which traditionally needed</p> <p>many phases and complex staging, like those with inequality path constraints, to a signifi-</p> <p>cantly easier to handle single arc. Finally, continuation methods can circumvent the small</p> <p>radius of convergence of indirect methods by gradually changing the problem and use previ-</p> <p>ously found solutions for guesses.</p> <p>The new optimal control problem solver Giuseppe incorporates and builds upon these</p> <p>advancements to make indirect methods more accessible and easily used. It seeks to enable</p> <p>greater research and creative approaches to problem solving by being more flexible and</p> <p>extensible than previous solvers. The solver accomplishes this by implementing a modular</p> <p>design with well-defined internal interfaces. Moreover, it allows the user easy access to and</p> <p>manipulation of component objects and functions to be use in the way best suited to solve</p> <p>a problem.</p> <p>A new technique simplifies and automates what was the predominate roadblock to using</p> <p>continuation, the generation of an initial guess for the seed solution. Reliable generation of</p> <p>a guess sufficient for convergence still usually required advanced knowledge optimal contrtheory or sometimes incorporation of an entirely separate optimization method. With the</p> <p>new method, a user only needs to supply initial states, a control profile, and a time-span</p> <p>over which to integrate. The guess generator then produces a guess for the “primal” problem</p> <p>through propagation of the initial value problem. It then estimates the “dual” (adjoint)</p> <p>variables by the Gauss-Newton method for solving the nonlinear least-squares problem. The</p> <p>decoupled approach prevents poorly guessed dual variables from altering the relatively easily</p> <p>guess primal variables. As a result, this method is simpler to use, faster to iterate, and much</p> <p>more reliable than previous guess generation techniques.</p> <p>Leveraging the continuation process also allows for greater insight into the solution space</p> <p>as there is only a small marginal cost to producing an additional nearby solutions. As a</p> <p>result, a user can quickly generate large families of solutions by sweeping parameters and</p> <p>modifying constraints. These families provide much greater insight in the general problem</p> <p>and underlying system than is obtainable with singular point solutions. One can extend</p> <p>these analyses to high-dimensional spaces through construction of compound continuation</p> <p>strategies expressible by directed trees.</p> <p>Lastly, a study into common convergence explicates their causes and recommends mitiga-</p> <p>tion strategies. In this area, the continuation process also serves an important role. Adaptive</p> <p>step-size routines usually suffice to handle common sensitivity issues and scaling constraints</p> <p>is simpler and out-performs scaling parameters directly. Issues arise when a cost functional</p> <p>becomes insensitive to the control, which a small control cost mitigates. The best perfor-</p> <p>mance of the solver requires proper sizing of the smoothing parameters used in regularization</p> <p>methods. An asymptotic increase in the magnitude of adjoint variables indicate approaching</p> <p>a feasibility boundary of the solution space.</p> <p>These techniques for indirect methods greatly facilitate their use and enable the gen-</p> <p>eration of large libraries of high-quality optimal trajectories for complex problems. In the</p> <p>future, these libraries can give a detailed account of vehicle performance throughout its flight</p> <p>envelope, feed higher-level system analyses, or inform real-time control applications.</p>

Syftet med denna masteruppsats var att undersöka skillnaden i Game User Experience Satisfaction (GUESS) vid användning av SimProv, både i VR (Oculus Rift) och på skärm. SimProv är en spelliknande klassrumssimulation. Studien avsåg även finna potentiella problem som användaren kunde stöta på under testsessionen. För att kunna undersöka och utvärdera detta behövde SimProv vidareutvecklas. Vidareutvecklingen utfördes genom att använda spelmotorn Unity med PlayMaker, som är ett visual scripting språk, tillsammans med att följa rekommendationer som finns för UI- och User experience-design för VR-spel. Inomgruppsdesign med 30 deltagare användes som testmetod. Hälften av deltagarna fick antingen börja med att spela på skärm eller i VR med Oculus Rift. Efter varje spelsession fick deltagarna fylla i den nya psykometrisk validerade skalan Game User Experience Satisfaction Scale (GUESS), som består av nio subskalor. Avslutningsvis kunde deltagarna fylla i två fritextfrågor genom ett digitalt formulär, om de potentiella problem de stött på vid respektive spelsession. Då GUESS är en ny skala har få studier av denna typ utförts. De få studier som har utförts pekar åt olika håll i frågan om spel bör utvecklas i VR eller inte. Resultaten från denna studie, som utfördes med tvåsidig hypotesprövning med t-test, visade inga signifikanta skillnader mellan VR och skärm. Endast en subskala, Play Engrossment, visade signifikant skillnad för VR. De textbaserade resultaten som analyserades med tematisk analys visade att majoriteten av deltagarna föredrog VR, men att alternativen i spelet upplevdes som begränsande. / The aim of this Master’s Thesis was to find out the difference in Game User Experience Satisfaction (GUESS) when using SimProv, both in VR (Oculus Rift) and on monitor. SimProv is a game-like classroom simulation. The purpose of this thesis was also to find potential problems that users may encounter during the test sessions. To assess and evaluate this, SimProv had to be furthered developed. This development was done using the game engine Unity and the visual scripting language PlayMaker in combination with following UI and UX design recommendations for VR games. A within subjects design with 30 participants was conducted. The users played either the monitor version or the VR version first, with no particular order. After each play session participants were asked to fill in the GUESS-scale, which is a newly developed and psychometrically validated scale that consists of 9 subscales. At the end of the play sessions participants could choose to answer two questions, through a digital form, about potential problems they may have encountered in both modalities. Since GUESS is a new scale few studies of evaluating VR versus monitor, using GUESS, have been conducted. The few studies that have been conducted showed no consensus in whether games should or should not be developed for VR. The inferential analysis with two-tailed paired samples t-tests in this study showed no significant difference between VR and monitor. The subscale Play Engrossment showed significant differences for VR. The text-based questions, that were analyzed with a thematic analysis, showed that the majority of the participants preferred VR. However, many participants felt that the answer options in the game where restricted.

Made available in DSpace on 2016-04-27T17:27:25Z (GMT). No. of bitstreams: 1 Luis Manuel Malta de Alves Louceiro.pdf: 1818082 bytes, checksum: 8786aaf4801d1196495dedbefe6aea8d (MD5) Previous issue date: 2008-11-11 / The main objective of this Master s Dissertation is to know in an unprecedented work to what extent the mystic of Nature, orador, poet, essayist and Transcendentalist philosopher Ralph Waldo Emerson (1803-82) may have influenced Pragmaticist and Semiotician Charles Sanders Peirce (1839-1914) through his poem, The Sphynx (1841; translated for the first time into Portuguese in Annex 1), which stimulated the latter to offer an answer to the Emersonian enigma in the essay, A Guess at the Riddle (1887-88; translated for the first time into Portuguese in Annex 2), something that, later, according to Nathan Houser & Christian Kloesel, led to the construction of his admirable Architectonic (The Essential Peirce - Volume 1, 245), about which Peirce himself wrote: this book, if ever written, as it soon will be if I am in a situation to do it, will be one of the births of time (Ibid, ibidem). Therefore, in Part I we will analyze Emerson s poem and will highlight his Main Ideas, those present in his own books, essays and poems - before and after the making of the poem (1841) -, so we can know his intellectual development, in his rich dialog with the Western, Middle-Eastern and Eastern philosophies (that influenced him tremendously) -, once the key-idea behind this Master s Dissertation is grounded on Peirce s other comment on The Sphynx - symbols grow in the essay What Is A Sign? (1894) until we get to Emerson s Epistemology of Moods, his Existential Ethics of Sel-Improvement and his Metaphysics of Process, according to Stanley Cavell, who is responsible for the renaissance of Emerson s philosophical studies in the US in the last three decades. In Part II we will make a structural analysis (Martial Guéroult) of the answer Peirce gave to the Emersonian enigma in his essay, A Guess at the Riddle (1887-88) / O principal objetivo desta Dissertação de Mestrado é saber em trabalho inédito - em que medida o místico da Natureza, orador, poeta, ensaísta, e filósofo transcendentalista norteamericano Ralph Waldo Emerson (1803-82) pode ter influenciado o pragmaticista e semioticista norte-americano Charles Sanders Peirce (1839-1914) através de seu poema The Sphynx (1841; A Esfinge ; com tradução inédita no Anexo 1), que teria motivado este a oferecer uma resposta ao enigma emersoniano no ensaio A Guess at the Riddle (1887-88; Uma Conjectura ao Enigma ; tradução inédita no Anexo 2), algo que levou Peirce, mais tarde, nas palavras de Nathan Houser & Christian Kloesel, à construção de sua admirável arquitetônica (The Essential Peirce - Volume 1, 245) e sobre o qual o próprio Peirce escreveu: este livro, se alguma vez for escrito, como será se eu estiver na condição de fazê-lo, será um dos acontecimentos da época (The Essential Peirce - Volume 1, p. 245). Assim, na Parte I faremos uma análise do poema emersoniano em que exporemos suas Principais Idéias, aquelas presentes em seus próprios livros, ensaios e poemas - antes e depois da feitura do poema (1841) -, para que possamos conhecer seu desenvolvimento intelectual, no rico diálogo com as tradições filosóficas Ocidental. Médio-Oriental e Oriental (que muito o influenciaram) -, uma vez que a idéia-chave por detrás desta Dissertação está fundada no outro comentário de Peirce ao enigma d A Esfinge - os símbolos crescem no ensaio What Is A Sign? (1894; O Que É Um Signo? ) até chegar à sua Epistemologia de Estados de Espírito, sua Ética Existencial de Auto- Melhoramento e sua Metafísica do Processo, de acordo com Stanley Cavell, que é responsável pelo renascimento dos estudos filosóficos emersonianos nos EUA nas últimas três décadas. Na Parte II faremos uma análise estrutural (Martial Guéroult) da resposta que Peirce forneceu ao enigma emersoniano com seu ensaio, Uma Conjectura ao Enigma (1887-88)

Conducting musical analyses over three case studies, Electric, Eclectic, Canadian: Issues of Genre and Identity in the Music of the Guess Who considers issues of genre, culture, and identity in the music of Canadian rock band the Guess Who. The first case study discusses soft rock transformations in the songs “These Eyes” (1968), “Laughing” (1969), and “Undun” (1969). The second case study examines changes in audience identification with the song “American Woman” (1970), performing comparative analyses of the Guess Who original release to Lenny Kravitz’s version (1999). The final case study discusses ideas of authenticity in the folk rock-inspired protest songs “Hand Me Down World” (1970), “Share the Land” (1970), and “Guns, Guns, Guns” (1972), comparing them to the iconic songs “For What It’s Worth” (Buffalo Springfield, 1967), “Big Yellow Taxi” (1970), “Ohio” (Neil Young, 1970 and “Southern Man” (Young, 1970). The conclusions summarise various musical and socio-political aspects of the Guess Who’s output and places it in relation to questions of national identity.

Работа посвящена вопросу применения сервисов Web2.0 в процессе обучения лексической стороне иноязычном речи в старшей школе. Объектом данного исследования является процесс обучения лексической стороне иноязычной речи в старшей школе, предметом - применение социальных сетевых сервисов Веб 2.0 в обучении лексической стороне речи учащихся старшей школы. Цель настоящей магистерской диссертации состоит в определении возможностей социальных сетевых сервисов Web2.0 в обучении иностранным языкам учащихся старших классов, а также разработке методических рекомендаций по формированию лексического навыка на базе интернет-технологий. В практической части работы был разработан электронный комплекс упражнений по теме “Travelling”, который впоследствии был апробирован в опытно-экспериментальном обучении. Благодаря пробному обучению экспериментальная группа улучшила свой результат и даже превзошла результат контрольной группы, что может говорить об эффективности применения интерактивных упражнений, созданных с помощью сервисов Web2.0. Использование ресурсов Web2.0 позволило не только повысить качество формируемого навыка, но и спроектировать уроки английского языка так, чтобы они были увлекательными, интерактивными и результативными. Также были созданы методические рекомендации по формированию лексического навыка учащихся старшей школы с использованием сервисов Web2.0, которые могут быть использованы как учителями английского языка среднеобразовательных учреждений, так и студентами педагогических и лингвистических высших учебных заведений. / The dissertation is devoted to the use of Web2.0 services in the process of teaching the lexical side of foreign language speech in high school. The object of the study is the process of teaching the lexical side of foreign language speech in high school, the subject of the study is the use of Web 2.0 social networking services in teaching the lexical side of speech to high school students. The purpose of the study is to determine the capabilities of Web2.0 social networking services in teaching foreign languages to high school students, as well as to develop methodological recommendations for the formation of lexical skills based on Internet technologies. In the practical part of the work, an electronic set of exercises on the topic “Traveling” was developed, which was subsequently tested in experiential learning. Thanks to the experiential learning, the experimental group improved its result and even surpassed the result of the control group, which can indicate the effectiveness of the use of interactive exercises created with the help of Web2.0 services. The use of Web2.0 resources made it possible not only to improve the quality of the formed skill, but also to design English lessons so that they were exciting, interactive and effective. Guidelines were also created for the formation of lexical skills of high school students using Web2.0 services, which can be used by both teachers of English at secondary educational institutions and students of pedagogical and linguistic higher educational institutions.

<p>The present study investigates lexical similarity perceptions by students of Swedish as a foreign language (L3) with a good yet non-native proficiency in English (L2). The general theoretical framework is provided by studies in transfer of learning and its specific instance, transfer in language acquisition.</p><p>It is accepted as true that all previous linguistic knowledge is facilitative in developing proficiency in a new language. However, a frequently reported phenomenon is that students see similarities between two systems in a different way than linguists and theoreticians of education do. As a consequence, the full facilitative potential of transfer remains unused.</p><p>The present research seeks to shed light on the similarity perceptions with the focus on the comprehension of a written text. In order to elucidate students’ views, a form involving similarity judgements and multiple choice questions for formally similar items has been designed, drawing on real language use as provided by corpora. 123 forms have been distributed in 6 groups of international students, 4 of them studying Swedish at Level I and 2 studying at Level II. </p><p>The test items in the form vary in the degree of formal, semantic and functional similarity from very close cognates, to similar words belonging to different word classes, to items exhibiting category membership and/or being in subordinate/superordinate relation to each other, to deceptive cognates. The author proposes expected similarity ratings and compares them to the results obtained. The objective measure of formal similarity is provided by a string matching algorithm, Levenshtein distance.</p><p>The similarity judgements point at the fact that intermediate similarity values can be considered problematic. Similarity ratings between somewhat similar items are usually lower than could be expected. Besides, difference in grammatical meaning lowers similarity values significantly even if lexical meaning nearly coincides. Thus, the obtained results indicate that in order to utilize similarities to facilitate language learning, more attention should be paid to underlying similarities.</p>

The present study investigates lexical similarity perceptions by students of Swedish as a foreign language (L3) with a good yet non-native proficiency in English (L2). The general theoretical framework is provided by studies in transfer of learning and its specific instance, transfer in language acquisition. It is accepted as true that all previous linguistic knowledge is facilitative in developing proficiency in a new language. However, a frequently reported phenomenon is that students see similarities between two systems in a different way than linguists and theoreticians of education do. As a consequence, the full facilitative potential of transfer remains unused. The present research seeks to shed light on the similarity perceptions with the focus on the comprehension of a written text. In order to elucidate students’ views, a form involving similarity judgements and multiple choice questions for formally similar items has been designed, drawing on real language use as provided by corpora. 123 forms have been distributed in 6 groups of international students, 4 of them studying Swedish at Level I and 2 studying at Level II.  The test items in the form vary in the degree of formal, semantic and functional similarity from very close cognates, to similar words belonging to different word classes, to items exhibiting category membership and/or being in subordinate/superordinate relation to each other, to deceptive cognates. The author proposes expected similarity ratings and compares them to the results obtained. The objective measure of formal similarity is provided by a string matching algorithm, Levenshtein distance. The similarity judgements point at the fact that intermediate similarity values can be considered problematic. Similarity ratings between somewhat similar items are usually lower than could be expected. Besides, difference in grammatical meaning lowers similarity values significantly even if lexical meaning nearly coincides. Thus, the obtained results indicate that in order to utilize similarities to facilitate language learning, more attention should be paid to underlying similarities.