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Complex plasmas: Interaction potentials and non-Hamiltonian dynamics
Get PDFThis thesis is a cumulative dissertation that consists of three papers.
The first paper addresses the issue of screening of a charged dust particle suspended in the plasma-wall transition layer of a plasma discharge. This problem is one of the fundamental issues in the physics of complex (dusty) plasmas, because the screening of charged dust particles determines the interaction forces between them and thus governs their dynamics. The kinetic model proposed in this paper considers a point charge embedded in a weakly-ionized plasma with ion drift. The latter is considered to be due to an external electric field and assumed to be mobility-limited. Here, "mobility-limited" means that the acceleration of ions in the external field is balanced by collisions of ions with neutrals and that this balance determines the drift velocity. The embedded point charge (i.e., a charged dust particle) perturbs the ion drift, and the resulting potential distribution around the dust particle is calculated. The results are proven to be in agreement with existing measurements performed in the plasma-wall transition layer of a rf plasma discharge. One of the important applications of this work is related to the possibility of tuning the pair interaction potential between dust particles by applying an external oscillating electric field. In particular, such a tuning allows studying electrorheological properties of strongly coupled systems on all relevant time scales. First experiments of this kind have already been performed onboard the International Space Station.
The second paper deals with the dust-lattice waves - oscillations of charged dust particles forming a crystalline structure in a plasma. The role of anisotropic screening of dust particles and variations of their charges is investigated. It is well known that the mentioned effects lead to non-Hamiltonian dynamics of dust particles and, as a result, can trigger an instability of the dust-lattice waves. This instability has been already observed in experiments. The new result is that the mutual influence of particles on their charges, not considered in the analysis of the dust-lattice waves before, is shown to be capable of making a significant contribution to this instability.
The third paper examines whether a similar instability can be observed in a cluster formed by two or three charged dust particles. It is found that an instability due to the non-Hamiltonian dynamics is only possible when the interparticle separation in the cluster is such that certain cluster eigenfrequencies are sufficiently close to each other.Настоящая диссертация является кумулятивной диссертацией и состоит из трех работ.
Первая работа посвящена экранированию заряженной пылевой частицы, левитируемой в приэлектродном слое плазменного разряда. Эта задача является одной из фундаментальных проблем физики пылевой плазмы, так как экранирование заряженных пылевых частиц определяет силы взаимодействия между ними и поэтому определяет их динамику. В статье предложена кинетическая модель, в которой рассматривается точечный заряд, помещенный в слабоионизированную плазму с ионным дрейфом. Предполагается, что ионный дрейф вызван внешним электрическим полем и соответствует мобильности ионов. Последнее означает, что подразумевается баланс между ускорением ионов во внешнем электрическом поле и столкновениями ионов с нейтралами, который и определяет скорость дрейфа. Внесенный точечный заряд (т.е., заряженная пылевая частица) возмущает дрейф ионов, и образующееся распределение потенциала вокруг пылевой частицы вычислено в настоящей работе. Результаты находятся в согласии с ранее опубликованными результатами измерений, выполненными в приэлектродном слое радиочастотного плазменного разряда. Одно из важных приложений этой работы связано с возможностью регулирования потенциала парного взаимодействия пылевых частиц посредством приложения внешнего осциллирующего электрического поля. В частности, такое регулирование позволяет изучать электрореологические свойства систем, в которых потенциальная энергия парного взаимодействия частиц превышает их кинетическую энергию. Первые эксперименты такого типа уже были проведены на борту Международной Космической Станции.
Предметом исследования второй работы являются так называемые пылекристаллические волны - колебания заряженных пылевых частиц, образующих кристаллическую структуру в плазме. Исследована роль как анизотропии экранирования пылевых частиц, так и вариаций их зарядов. Как известно, эти эффекты приводят к негамильтоновой динамике пылевых частиц и поэтому могут вызвать неустойчивость пылекристаллических волн, которая уже была обнаружена в экспериментах. Новый результат заключается в том, что взаимное влияние пылевых частиц на их заряды, которое ранее не учитывалось при анализе пылекристаллических волн, может обеспечить значительный вклад в эту неустойчивость.
В третьей работе исследовано, может ли подобная неустойчивость наблюдаться в кластере, состоящем из двух или трех пылевых частиц. Получено, что подобная неустойчивость из-за негамильтоновой динамики может возникнуть только тогда, когда расстояние между пылевыми частицами близко к резонансному значению, при котором определенные собственные частоты кластера совпадают.Diese Dissertation ist eine kumulative Dissertation und besteht aus drei Arbeiten.
Die erste Arbeit beschäftigt sich mit der Abschirmung des in einer Plasmarandschicht zur Schwebe gebrachten geladenen Staubteilchens. Dieses Problem ist von fundamentaler Bedeutung für die Physik der komplexen (staubigen) Plasmen, weil die Abschirmung die Form der Wechselwirkungen und somit die Dynamik der geladenen Staubteilchen bestimmt. In der Arbeit wird ein kinetisches Modell vorgeschlagen, in welchem ein Staubteilchen als eine Punktladung betrachtet wird, die sich in einem schwach ionisierten Plasma mit einer Ionendrift befindet. Es wird angenommen, dass die Ionendrift durch ein externes elektrisches Feld verursacht wird und dass diese Ionendrift der Mobilität der Ionen entspricht. Dies bedeutet, dass die Beschleunigung der Ionen im externen elektrischen Feld durch Ionen-Neutralteilchen-Stöße ausgeglichen wird und dass diese Kompensation die Geschwindigkeit der Ionendrift bestimmt. Die Punktladung (d.h. das Staubteilchen) stört diese Ionendrift, und in der vorliegenden Arbeit wird die resultierende Potentialverteilung des Staubteilchens im Plasma berechnet. Zudem wird festgestellt, dass die Resultate mit den früher in RF-Entladungen durchgeführten Experimenten konsistent sind. Die übergreifende Bedeutung dieser Untersuchung liegt in der Möglichkeit, damit durch ein externes elektrisches Wechselfeld das binäre Wechselwirkungspotential der Staubteilchen von außen zu steuern und somit z.B. elektrorheologische Eigenschaften von stark wechselwirkenden Systemen von Partikeln sichtbar zu machen und dynamisch auf allen relevanten Zeitskalen zu untersuchen. Erste Messungen dieser Art sind in Experimenten auf der Internationalen Raumstation bereits erfolgreich durchgeführt worden.
Die zweite Arbeit beschäftigt sich mit den sogenannten Staub-Gitter-Wellen (dust-lattice waves). Das sind Wellen, die durch Schwankungen der geladenen Staubteilchen, die eine Kristallstruktur im Plasma bilden, entstehen. In der vorliegenden Arbeit wird die Rolle sowohl der Anisotropie der Abschirmung der Staubteilchen als auch der Variation ihrer Ladungen untersucht. Wie bekannt führen diese Effekte zu nicht-Hamiltonischer Dynamik der Staubteilchen und können daher eine Instabilität der Staub-Gitter-Wellen auslösen. Solche Effekte sind in Experimenten bereits beobachtet worden. Das neue Ergebnis besteht darin, dass der gegenseitige Einfluss der Staubteilchen auf ihre Ladungen, ein Effekt, welcher bisher bei der Analyse der Staub-Gitter-Wellen noch nicht berücksichtigt wurde, einen wichtigen Beitrag zu dieser Instabilität leisten kann.
In der dritten Arbeit wird untersucht, ob eine ähnliche Instabilität in Partikelclustern, welche nur aus zwei oder drei Staubteilchen bestehen, beobachtet werden kann. Es wurde festgestellt, dass eine ähnliche Instabilität, die durch nicht-Hamiltonische Dynamik verursacht ist, nur dann möglich ist, wenn der Teilchenabstand so gewählt wird, dass bestimmte Eigenfrequenzen des Clusters gut miteinander übereinstimmen
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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