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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
711

Algorithmic transformation of multi-loop Feynman integrals to a canonical basis

Meyer, Christoph 30 January 2018 (has links)
Die Auswertung von Mehrschleifen-Feynman-Integralen ist eine der größten Herausforderungen bei der Berechnung präziser theoretischer Vorhersagen für die am LHC gemessenen Wirkungsquerschnitte. In den vergangenen Jahren hat sich die Nutzung von Differentialgleichungen bei der Berechnung von Feynman-Integralen als sehr erfolgreich erwiesen. Es wurde dabei beobachtet, dass die von den Feynman-Integralen erfüllte Differentialgleichung oftmals in eine sogenannte kanonische Form transformiert werden kann, welche die Integration der Differentialgleichung mittels iterierter Integrale wesentlich vereinfacht. Das zentrale Ergebnis der vorliegenden Arbeit ist ein Algorithmus zur Berechnung rationaler Transformationen von Differentialgleichungen von Feynman-Integralen in eine kanonische Form. Neben der Existenz einer solchen rationalen Transformation stellt der Algorithmus keinerlei weitere Bedingungen an die Differentialgleichung. Insbesondere ist der Algorithmus auf Mehrskalenprobleme anwendbar und erlaubt eine rationale Abhängigkeit der Differentialgleichung vom dimensionalen Regulator. Bei der Anwendung des Algorithmus wird zunächst das Transformationsgesetz im dimensionalen Regulator entwickelt, um Differentialgleichungen für die Koeffizienten in der Entwicklung der Transformation herzuleiten. Diese Differentialgleichungen werden dann mit einem rationalen Ansatz für die gesuchte Transformation gelöst. Es wird zudem eine Implementation des Algorithmus in dem Mathematica Paket CANONICA vorgestellt, welches das erste veröffentlichte Programm dieser Art ist, das auf Mehrskalenprobleme anwendbar ist. CANONICAs Potential für moderne Mehrschleifenrechnungen wird anhand mehrerer nicht trivialer Mehrschleifen-Integraltopologien demonstriert. Die gezeigten Topologien hängen von bis zu drei Variablen ab und umfassen auch vormals ungelöste Topologien, die zu Korrekturen höherer Ordnung zum Wirkungsquerschnitt der Produktion einzelner Top-Quarks am LHC beitragen. / The evaluation of multi-loop Feynman integrals is one of the main challenges in the computation of precise theoretical predictions for the cross sections measured at the LHC. In recent years, the method of differential equations has proven to be a powerful tool for the computation of Feynman integrals. It has been observed that the differential equation of Feynman integrals can in many instances be transformed into a so-called canonical form, which significantly simplifies its integration in terms of iterated integrals. The main result of this thesis is an algorithm to compute rational transformations of differential equations of Feynman integrals into a canonical form. Apart from requiring the existence of such a rational transformation, the algorithm needs no further assumptions about the differential equation. In particular, it is applicable to problems depending on multiple kinematic variables and also allows for a rational dependence on the dimensional regulator. First, the transformation law is expanded in the dimensional regulator to derive differential equations for the coefficients of the transformation. Using an ansatz in terms of rational functions, these differential equations are then solved to determine the transformation. This thesis also presents an implementation of the algorithm in the Mathematica package CANONICA, which is the first publicly available program to compute transformations to a canonical form for differential equations depending on multiple variables. The main functionality and its usage are illustrated with some simple examples. Furthermore, the package is applied to state-of-the-art integral topologies appearing in recent multi-loop calculations. These topologies depend on up to three variables and include previously unknown topologies contributing to higher-order corrections to the cross section of single top-quark production at the LHC.
712

Form und Zeit

Höfler, Carolin 19 September 2011 (has links)
Seitdem der Computer in den 1990er Jahren zur omnipräsenten Infrastruktur der zeitgenössischen Architekturproduktion wurde, fand die technologische Seite der digitalen Formgenerierung große Aufmerksamkeit, wohingegen die Interpretation von Raum als kontinuierliche Oberfläche eher unterbelichtet blieb. Die relativ einfache und schnelle Erzeugung von Freiformflächen durch entsprechende 3D-Software, die Geschwindigkeit, mit der Computer ständig variable Morphologien und Familien von nicht euklidischen Formen berechnen können, hat zu der Annahme verleitet, die weichen Flächen und räumlichen Konfigurationen seien wissenschaftlich unausweichlich und technologisch prädestiniert. Die Wahl dieser Formen beruht aber weder allein auf einer technologischen Vorgabe noch auf einem rein stilistischen Konzept. Mithilfe neuer Technologien werden zeitbasierte Raummodelle erprobt, die sich vom traditionellen Konzept des kartesischen Raumes als Koordinatensystem abheben. Die Untersuchung und Interpretation dieser Raumvorstellungen und ihrer Semantik bilden den Kernpunkt der vorliegenden Arbeit. Dem rhetorisch formulierten Anspruch nach waren die computergenerierten Formen das Produkt einer Nullsetzung. So stark dieser Anspruch bis heute aufrechterhalten wird, so wenig lässt sich verbergen, dass diese scheinbar neue generierte Bildwelt auf zahlreichen Vorbildern aufbaut. Es sind vor allem die Programme und Projekte gegen eine als monoton und dogmatisch empfundene Architekturmoderne, die auf die Gestalter digitaler Raummodelle eingewirkt haben. Zur Rekonstruktion der Rezeptionslinien werden drei Raumbegriffe bestimmt, die ihre Prägung in der experimentellen Architektur der Nachkriegsmoderne fanden: der endlose Raum, die vernetzte Struktur und die schräge Fläche. Mit diesen Begriffen werden Kontinuitäten und Diskontinuitäten in der Entwicklung der experimentellen Architektur herausgestellt, und die computerbasierten Raumkonzepte einer kritischen Betrachtung unterzogen. / Since the computer became omnipresent infrastructure of contemporary architectural production in the 1990s, a great deal of attention has been given to the technological side of the digital form generation, whereas the interpretation of space as a continuous surface has tended to remain underexposed. The relatively easy and fast generation of free-form surfaces using appropriate 3D software, the speed with which computers are able to calculate constantly variable morphologies and families of non-Euclidean shapes, has led to the assumption that soft surfaces and spatial configurations are scientifically inevitable and technologically predestined. However, the choice of these shapes is neither based on a technological specification nor on a purely stylistic concept. With the help of new technologies, time-based space models are tested, which contrast with the traditional concept of Cartesian space as a coordinate system. The investigation and interpretation of these spatial ideas and their semantics form the core of this work. If the rhetorically worded claim were to be believed, the computer-generated shapes are the product of muting. However strongly this claim has been maintained until now, it is nonetheless hardly possible to conceal that this apparently new generated graphic world is in fact built upon numerous examples. Above all, it is the programs and projects against a modern architecture found to be monotonous and dogmatic, which have influenced the designers of digital spatial models. To reconstruct the reception lines, three spatial terms are defined, which found their style in the experimental architecture of the post-war modern age: the endless space, networked structure and inclined surface. With the help of these terms, continuities and discontinuities are brought out in the development of experimental architecture, and the computer-based spatial concepts are subjected to critical examination.
713

Números complexos para professores de matemática da educação básica que atuam no ensino médio / Complex number for high school mathematics teachers

Cruz Filho, Robinson Antão da 13 April 2018 (has links)
Um texto sobre o corpo dos números complexos abordando-os de uma forma integrada e direcionada para professores de educação básica que atuam no ensino médio. Apresenta de forma bem fundamentada vários aspectos dos números complexos: par ordenado, vetor do plano, forma algébrica, forma trigonométrica e matricial. Todos os resultados essenciais foram demonstrados. Há um capítulo com alguns problemas resolvidos. / A text on the field of complex numbers in an integrated way and directed to teachers of basic education who work in high school. It presents in a well-founded form several aspects of the complex numbers: ordered pair, plane vector, algebraic form, trigonometric and matrix form. For every essential result, there is a proof. There is a chapter with some solved problems.
714

Här och nu : en undersökning om närvaro och motivation / Here and now : about presence and motivation

Jarl, Agnes January 2019 (has links)
Att elever inte alltid kommer i tid till en lektion är nog ett problem som de flestagymnasieskolor i Sverige har. Utifrån sen ankomst som bakgrund och diskussion med eleverom skolans riktlinjer kring sen ankomst, utvecklades intresset för att utforska eleversmotivation för skolnärvaro. Jag har bett elever i årskurs två på gymnasiet att kommunicerasina erfarenheter om motivation, närvaro och sen ankomst. Genom a/r/tography somförhållningssätt har syftet varit att undersöka min egen ämnesdidaktik för att kunna skapaförutsättningar kring elevers motivation och närvaro i bildämnet och i klassrummet. Detövergripande syftet med undersökningen är att undersöka gymnasieelevers motivation ibildämnet samt att medvetandegöra eleven genom skapande, om sin egen plats och närvarorent fysiskt och psykiskt. Studien utgår från frågeställningen, Hur formulerar och gestaltargymnasieeleverna sin upplevelse kring motivation och närvaro. Vad synliggörs när jagundersöker skolfrånvaro genom den bildpedagogiska praktiken tillsammans med eleverna?I undersökningen består en del av empirin av kakelplattor i lera skapat av eleverna därde kommunicerar erfarenheter och tankar kring motivation och närvaro. Resultatet visar hurelevernas motivation för skolarbetet ofta ligger utanför den specifika pedagogiska praktiken.Många anger CSN som motivation, då deras studiestöd vid frånvaro riskerar att dras in. Andratänker mer långsiktigt på närvaron som nödvändig för goda skolresultat och framtidaarbete. Även skolan som en plats att träffa vänner är motiverande för skolnärvaro. Genomeget skapande undersöker även jag dessa frågor parallellt med eleverna i denna undersökningoch som en medskapare av bilder. Elevernas kakel har satts samman till en vägg likaså harmina kakelplattor bildat en vägg. Utöver att dessa kakelplattor analyseras enskilt iuppsatsen, så visas också den praktiska och konstnärliga undersökningens resultat påKonstfacks vårutställning.Mitt arbete och mina slutsatser pekar mot att eleverna också motiveras av att arbetatillsammans, med en utställning som mål. I analysen har jag kommit fram till och förståttderas tidigare erfarenheter om skolan som en plats där motivation att komma till skolan i rätttid präglas av förväntningar av omgivning lika mycket som motivationen av att vilja ha enljus framtid och en utbildning för sin egen skull.
715

Urban Intensification in Metropolitan Khartoum : Influential Factors, Benefits and Applicability

Elghazali, Burhan January 2006 (has links)
This dissertation explores the theoretical and methodological implications involved in the policy framework needed to intensify urban residential areas in a developing country. Metropolitan Khartoum, Sudan, has been chosen as a case study. The aim of the study is to further our understanding of the implications of transforming a sprawling city form to an intensified form. The objectives are: to identify the factors that have shaped Sudanese urban form in general and Metropolitan Khartoum in specific; to identify the policies that can intensify the urban residential neighborhoods in Metropolitan Khartoum; and, to influence both the demand and requisite housing needs for this intensified form. This research is qualitative in its nature: the complexity of the study problematic required the adoption of a constructivist paradigm as the fundamental set of beliefs. Inductive arguments are used in conjunction with a wide range of methods, including detailed descriptions of Sudan and metropolitan Khartoum, with special emphasis on how local environment, urban challenges, policy, legislation and practices affect the study problematic. The theoretical premises of intensification are reviewed along with development issues, urban infrastructure challenges and opportunities in developing countries and local acceptability of intensification. The different forces that can shape urban forms have been described and the suitability of metropolitan Khartoum, with different general urban intensification policies and practices and of urban management tools in large African cities has been investigated. The outcome of the study provides detail for a discussion of results that work to explain some of the cause and effect of urban sprawl in Metropolitan Khartoum. It also suggests possible change in both policy and regulation to induce successful city reform towards intensification. / QC 20110121
716

Urban Intensification in Metropolitan Khartoum : Influential Factors, Benefits and Applicability

Elghazali, Burhan January 2006 (has links)
<p>This dissertation explores the theoretical and methodological implications involved in the policy framework needed to intensify urban residential areas in a developing country. Metropolitan Khartoum, Sudan, has been chosen as a case study. The aim of the study is to further our understanding of the implications of transforming a sprawling city form to an intensified form. The objectives are: to identify the factors that have shaped Sudanese urban form in general and Metropolitan Khartoum in specific; to identify the policies that can intensify the urban residential neighborhoods in Metropolitan Khartoum; and, to influence both the demand and requisite housing needs for this intensified form. This research is qualitative in its nature: the complexity of the study problematic required the adoption of a constructivist paradigm as the fundamental set of beliefs. Inductive arguments are used in conjunction with a wide range of methods, including detailed descriptions of Sudan and metropolitan Khartoum, with special emphasis on how local environment, urban challenges, policy, legislation and practices affect the study problematic. The theoretical premises of intensification are reviewed along with development issues, urban infrastructure challenges and opportunities in developing countries and local acceptability of intensification. The different forces that can shape urban forms have been described and the suitability of metropolitan Khartoum, with different general urban intensification policies and practices and of urban management tools in large African cities has been investigated. The outcome of the study provides detail for a discussion of results that work to explain some of the cause and effect of urban sprawl in Metropolitan Khartoum. It also suggests possible change in both policy and regulation to induce successful city reform towards intensification.</p>
717

On the Structure of the Domain of a Symmetric Jump-type Dirichlet Form

Schilling, René L., Uemura, Toshihiro 16 June 2014 (has links) (PDF)
We characterize the structure of the domain of a pure jump-type Dirichlet form which is given by a Beurling–Deny formula. In particular, we obtain su cient conditions in terms of the jumping kernel guaranteeing that the test functions are a core for the Dirichlet form and that the form is a Silverstein extension. As an application we show that for recurrent Dirichlet forms the extended Dirichlet space can be interpreted in a natural way as a homogeneous Dirichlet space. For reflected Dirichlet spaces this leads to a simple purely analytic proof that the active reflected Dirichlet space (in the sense of Chen, Fukushima and Kuwae) coincides with the extended active reflected Dirichlet space. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
718

Form und In-formation zur Logik selbstreferentieller Strukturgenese

Weiss, Christina January 2006 (has links)
Zugl.: Witten, Herdecke, Univ., Diss.
719

Der elektronisch geschlossene Vertrag mit Schiedsabrede : Zulässigkeit und anwendbares Recht in nationalen und internationalen Schiedsverfahren /

Baldus, Bianca Natalie, January 2004 (has links)
Thesis (doctoral)--Universiẗat, Saarbrücken, 2003. / Includes bibliographical references (p. 285-305).
720

Wh-constructions and the division of labour between syntax and the interfaces

Βλάχος, Χρήστος 01 February 2013 (has links)
The minimalist approach to natural human language argues that the syntax of a language L maps a certain structure to a certain form at PF and to a certain meaning at LF. With the above in mind, the ideal perhaps scenario, in terms of transparency, would be that the mapping between form and meaning would be one to one. In other words, there is as much form as there is meaning. This would further imply that the mapping between form and meaning is symmetric. The present thesis studies some aspects of the form and meaning of two kinds of wh-constructions in Modern Greek, i.e., questions and sluicing, and shows that the relevant mapping may not necessarily be one to one. With respect to questions, it is argued that the same form may correspond to more than one meaning. As regards sluicing, it is proposed that there is less form than meaning. On the face of the previous, the argument will be as follows. Syntax generates form, and restricts part of meaning, while additional aspects of meaning are facilitated by PF, regarding wh-questions, and LF, concerning sluicing. Finally, since PF contributes to meaning, LF sees PF, and vice versa. / Το μινιμαλιστικό πλαίσο προσέγγισης της φυσικής ανθρώπινης γλώσσας υποστηρίζει ότι η σύνταξη μιας γλώσσας Γ αντιστοιχεί μια ορισμένη μορφή με μια ορισμένη δομή στην ΦΔ, και με μία ορισμένη σημασία στην ΛΔ. Με αυτό ως δεδομένο, το ιδεατό ίσως σενάριο, όσον αφορά στην διαφάνεια, θα ήταν ότι η αντιστοίχιση μεταξή μορφής και σημασίας είναι ένα προς ένα. Με άλλα λόγια, υπάρχει τόση μορφή όση και σημασία. Κάτι τέτοιο θα υπονοούσε επίσης ότι η αντιστοίχιση μορφής-σημασίας είναι συμμετρική. Η παρούσα διατριβή μελετά ορισμένες πτυχές δομών ερώτησης μερικής αγνοίας, και δομών εκκένωσης, στα Νέα Ελληνικά, και δείχνει ότι η εν λόγω αντιστοίχιση δεν είναι απαραίτητα ένα προς ένα. Όσον αφορά στις δομές ερώτησης μερικής αγνοίας, υποστηρίζεται ότι η ίδια μορφή μπορεί να σχετίζεται με περισσότερες από μια σημασίες. Σχετικά με τις δομές εκκένωσης, προτείνεται ότι φέρουν λιγότερη μορφή απο σημασία. Με βάση τα παραπάνω, το επιχείρημα θα έχει ως εξής. Η σύνταξη παράγει μορφή, και περιορίζει μέρος της σημασίας, ενώ ένα άλλο μέρος της σημασίας εισάγεται από την ΦΔ, όσον αφορά στις ερωτήσεις μερικής αγνοίας, και την ΛΔ, σχετικά με τις δομές εκκένωσης. Τέλος, αφού η ΦΔ συνεισφέρει στην σημασία, τότε η ΛΔ δομή βλέπει την ΦΔ, και αντιστρόφως.

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