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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.
11

Automates cellulaires, fonctions booléennes et dessins combinatoires / Cellular automata, boolean functions and combinatorial designs

Mariot, Luca 09 March 2018 (has links)
Le but de cette thèse est l'étude des Automates Cellulaires (AC) dans la perspective des fonctions booléennes et des dessins combinatoires. Au-delà de son intérêt théorique, cette recherche est motivée par ses applications à la cryptographie, puisque les fonctions booléennes et les dessins combinatoires sont utilisés pour construire des générateurs de nombres pseudo aléatoires (Pseudorandom Number Generators, PRNG) et des schémas de partage de secret (Secret Sharing Schemes, SSS). Les résultats présentés dans la thèse ont été développés sur trois lignes de recherche, organisées comme suit. La première ligne porte sur l'utilisation des algorithmes d'optimisation heuristique pour chercher des fonctions booléennes ayant des bonnes propriétés cryptographiques, à utiliser comme des règles locales dans des PRNG basés sur les AC. La motivation principale est l'amélioration du générateur de Wolfram basé sur la règle 30, qui a été montré être vulnérable vis à vis de deux attaques cryptanalytiques. La deuxième ligne s'occupe des fonctions booléennes vectorielles engendrées par les règles globales des AC. La première contribution considère la période des pré-images des configurations spatialement périodiques dans les AC surjectifs, et l'analyse des propriétés cryptographiques des règles globales des AC. La troisième ligne se concentre sur les dessins combinatoires engendrés par les AC, en considérant les Carrés Latins Orthogonaux (Orthogonal Latin Squares, OLS), qui sont équivalents aux SSS. En particulier, on donne une caractérisation algébrique des OLS engendrés par les AC linéaires, et on utilise des algorithmes heuristiques pour construire des OLS basés sur des AC non linéaires. / The goal of this thesis is the investigation of Cellular Automata (CA) from the perspective of Boolean functions and combinatorial designs. Beside its theoretical interest, this research finds its motivation in cryptography, since Boolean functions and combinatorial designs are used to construct Pseudorandom Number Generators (PRNG) and Secret Sharing Schemes (SSS). The results presented in the thesis are developed along three research lines, organized as follows. The first line considers the use of heuristic optimization algorithms to search for Boolean functions with good cryptographic properties, to be used as local rules in CA-based PRNG. The main motivation is to improve Wolfram's generator based on rule 30, which has been shown to be vulnerable against two cryptanalytic attacks. The second line deals with vectorial Boolean functions induced by CA global rules. The first contribution considers the period of preimages of spatially periodic configurations in surjective CA, and analyze the cryptographic properties of CA global rules. The third line focuses on the combinatorial designs generated by CA, specifically considering Orthogonal Latin Squares (OLS), which are equivalent to SSS. In particular, an algebraic characterization of OLS generated by linear CA is given, and heuristic algorithms are used to build OLS based on nonlinear CA.
12

A Configurable B-spline Parameterization Method for Structural Optimization of Wing Boxes

Yu, Alan Tao 28 September 2009 (has links)
This dissertation presents a synthesis of methods for structural optimization of aircraft wing boxes. The optimization problem considered herein is the minimization of structural weight with respect to component sizes, subject to stress constraints. Different aspects of structural optimization methods representing the current state-of-the-art are discussed, including sequential quadratic programming, sensitivity analysis, parameterization of design variables, constraint handling, and multiple load treatment. Shortcomings of the current techniques are identified and a B-spline parameterization representing the structural sizes is proposed to address them. A new configurable B-spline parameterization method for structural optimization of wing boxes is developed that makes it possible to flexibly explore design spaces. An automatic scheme using different levels of B-spline parameterization configurations is also proposed, along with a constraint aggregation method in order to reduce the computational effort. Numerical results are compared to evaluate the effectiveness of the B-spline approach and the constraint aggregation method. To evaluate the new formulations and explore design spaces, the wing box of an airliner is optimized for the minimum weight subject to stress constraints under multiple load conditions. The new approaches are shown to significantly reduce the computational time required to perform structural optimization and to yield designs that are more realistic than existing methods.
13

Aztec Stone Boxes: Myth, Metaphor, and History

Hulshoff, Amy Catherine, Hulshoff, Amy Catherine January 2016 (has links)
This essay is study of Aztec stone boxes from the pre-conquest Aztec empire. My study focuses on the interpretation of carvings on the surfaces, as well as the interiors and lids when applicable. The study includes not only traditionally functional boxes, but also altars (blocks or basins) and offering chambers, as comparative examples. The thesis focuses on three specific stone boxes located in museums in Mexico, Germany, and Great Britain: the Islas y Bustamante Box (Museo Nacional de Anthropologi­a, Mexico), the Hackmack Box (Museum fur Volkerkunde, Hamburg), and the Ahuitzotl Box (British Museum, London, and Museum fur Volkerkunde, Berlin). I am studying the iconographic programs, with a focus on themes of auto-sacrifice and creation, carved on the art objects themselves and their function as story-telling devices, with or without the contents that the box may have contained. In their forms, the objects themselves are metaphors for space, time, Aztec history, and Aztec creation myths. The Hackmack Box depicts the creation god, Quetzalcoatl (feathered serpent), and refers to the creation myth of mankind saved from the underworld and resurrected from the ashes of bones, using Quetzalcoatl's own blood. The box bears Montezuma's name glyph and is likely a tribute to his birth, his ascension and success as a ruler, and his piety. The Islas y Bustamante Box depicts the god of caves, Tepeyolotl, and refers to the myth that man ascended from caves, as all of life originated from the mouth of a cave that was also a natural spring. The box itself is a metaphor for this type of cave. The Ahuitzotl Box depicts the god of water Tlaloc, and refers to the myth of the tlaloques (helpers) discovery of "food-mountain", in other words, the discovery of maize that nourished the Aztec people. It has been linked to the dedication of the aqueduct built under the Aztec ruler Ahuitzotl, and serves as a tribute to this historical event. The cosmic arrangement of the motifs on these boxes reveal the object as a metaphor for space and time itself as they comply with the Aztec's earthly orientation of the heavens, the earth, an the underworld.
14

Datové schránky jako způsob doručování v občanském soudním řízení / Data boxes as a method of delivery in civil proceedings

Traxlerová, Alena January 2012 (has links)
The title of the thesis is "The data-boxes as a delivery method in civil proceedings". The thesis describes the significance of data-boxes in civil proceedings and deals with electronization of the legal institute of delivery. Delivery constitutes one of the basic legal institutes of civil proceedings which has undergone many changes in recent years. The key source of law for the given topic is law No. 99/1963 Coll., the Civil Procedure Code, as amended, especially by the amending law No. 7/2009 Coll., which has introduced obligatory use of the data-box-system in civil proceedings, and law No. 300/2008 Coll., on the Electronic Acts and Authorized Document Conversion, as amended, which has incorporated data-boxes into our legal system. The aim of the thesis is the analysis and subsequent comparison of the advantages of delivery via data-boxes. The thesis compares and evaluates various methods of delivery - delivery by means of a delivering body and by means of the public data network, i.e. particularly by means of an e-mail with electronic signature and by means of a data-box. The thesis is divided into seven chapters. The introductory chapter explains the term delivery within the framework of civil proceedings. The following chapters describe the development of delivery in civil proceedings since...
15

This is not my funny Valentine. This is the science of sleep.

Roethlisberger, Crystal Lyn 01 May 2010 (has links)
This paper revolves around the idea of the infra-thin, a concept coined by Duchamp, which describes paradoxes and/or phenomena that are not easily defined with words but instead sensed. The infra-thin is illustrated throughout the paper by discussions revolving around scars, bruises, birthmarks, dust, fog, lint, and other similar "things" that are, in some definition of the term, objects. The afore listed entities are used as examples: 1. To initiate a dialogue that starts with Minimalism, bounces back to Duchamp and explains how he influenced the Minimalists, places Warhol in context, describes how Minimalism moved forward from the show at the Jewish Museum, and puts the rest of us working post-1966 in perspective. 2. To begin a conversation about readymades. A readymade being an anonymous, neutral object that we take for face value as "work of art" simply because of an artist's deeming it art. Because it exists as a neutral object, it is seen out of the corner of the viewer's eye, recognized as this anonymous thing that equals art object, and is then forgotten about and only recollected by memory as a readymade as opposed to the object that it resembles. 3. To introduce the idea of attempting to explain through language paradoxes that are sensed and/or attached directly to memory. I start with readymade but then there are other things. Bruises, scars, birthmarks are a few examples. Others include fog, dust, fuzz. Still others are shadows and stains. A few more are vapor and evanescence. Also, things inherently human, like emotion.
16

Boxing for biodiversity: a long-term follow up of an artificial dead wood environment

Carlsson, Staffan January 2015 (has links)
Today many saproxylic species are threatened because of habitat decline in Europe. Hollow trees represent a great part of the habitats that saproxylic species use. Since hollows takes a long time to develop, management actions are needed to prevent the extinction of saproxylic species. The aim of this study was to investigate the succession of saproxylic beetle species in artificial habitats in the form of wooden boxes. Wooden boxes were filled with a potential substrate and placed at different distances (0-1800 m) from oak hollow hot spots. In addition to the start mixture, four different additional substrates were added. In total, 4510 specimens of 114 saproxylic beetle species were sampled in 43 boxes over ten years. The specimens of tree-hollow species, wood rot species and nest species increased with 38% from the fourth to the final year but species richness decline from 47 to 29, respectively. A dead hen had a tendency for attracting more species but the small effect of different added substrates diminished over the years and had no significant effect on species richness after ten years. There was a higher similarity in species richness after ten years between the boxes and real hollow oaks. In conclusion, the artificial habitat developed into a more hollow like environment, with fewer but more abundant wood mould specialists, during ten years. This study clearly shows that the wooden boxes are used as habitats for saproxylic species as the boxes seems to develop into a more hollow-like habitat with time.
17

Nelly, monsteragenten & Kalles nya klänning. : En studie om hur genusperspektivet används i böcker för åldrarna 6-9 i boklådor från stadsbiblioteket i Karlstad kommun. / Nelly the monster agent & Kalle’s new dress. : A study on the gender perspective in books for children in the ages 6-9 in library book boxes from the town library in Karlstad municipality.

Mattsson, Chaterine January 2013 (has links)
This work addresses how the book boxes that are shipped to different schools, that don’t havelibraries themselves, from the city library are composed in Karlstad municipality and whatbooks they may contain. A case study is made to find out which books can be included in theboxes. An interview with staff from Karlstad City Library is made and two different kinds ofbook boxes are analyzed. There is one book box with children books that have a genderperspective and one with fiction children books.The books are analyzed and the conclusion of this work is that it is important to know whatthe children are reading and how books can influence them. Included in this work are alsoideas and suggestions for further research.
18

A Configurable B-spline Parameterization Method for Structural Optimization of Wing Boxes

Yu, Alan Tao 28 September 2009 (has links)
This dissertation presents a synthesis of methods for structural optimization of aircraft wing boxes. The optimization problem considered herein is the minimization of structural weight with respect to component sizes, subject to stress constraints. Different aspects of structural optimization methods representing the current state-of-the-art are discussed, including sequential quadratic programming, sensitivity analysis, parameterization of design variables, constraint handling, and multiple load treatment. Shortcomings of the current techniques are identified and a B-spline parameterization representing the structural sizes is proposed to address them. A new configurable B-spline parameterization method for structural optimization of wing boxes is developed that makes it possible to flexibly explore design spaces. An automatic scheme using different levels of B-spline parameterization configurations is also proposed, along with a constraint aggregation method in order to reduce the computational effort. Numerical results are compared to evaluate the effectiveness of the B-spline approach and the constraint aggregation method. To evaluate the new formulations and explore design spaces, the wing box of an airliner is optimized for the minimum weight subject to stress constraints under multiple load conditions. The new approaches are shown to significantly reduce the computational time required to perform structural optimization and to yield designs that are more realistic than existing methods.
19

Evaluation of the impact of non-uniform neutron radiation fields on the dose received by glove box radiation workers

Crawford, Arthur Bryan, Biegalski, Steven, January 2004 (has links) (PDF)
Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: Steven Biegalski. Vita. Includes bibliographical references. Also available from UMI.
20

Piercingové skrýše - konvolut užitných dóz (zásobnic) / Piercing hideouts

FLAMOVÁ, Barbora January 2013 (has links)
This diploma thesis addresses the practical and theoretical aspects of piercing jewellery and related accoutrements. The practical part describes the design and construction of a series of ceramic jewellery boxes for piercing jewellery. These three boxes are functional and unique jewellery in their own right. The theoretical part of this thesis examines body piercing art, piercing techniques and piercing jewellery. A visual section displays the piercing jewellery and documents the making of the jewellery boxes and their final design.

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