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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.
451

Estimación de la zona crítica de diseño en naves industriales con diferentes alturas libres que soporten puentes grúas de diferentes capacidades de carga / Estimation of the critical design zone in industrial Buildings with different free heights that support crane bridges with different load capacities

Cuadros Torres, David Edgardo, Jiménez Vargas, Gef Sinder 08 May 2021 (has links)
El presente estudio tiene como finalidad encontrar la zona crítica de diseño en naves industriales que combinen la premisa de diferentes alturas libres con la ubicación de distintas capacidades de carga de un puente grúa. Se propuso un total de nueve modelos simétricos en planta con una disposición de pórticos a dos aguas. El sistema estructural contempla pórticos a momento y pórticos arriostrados. El recorrido del puente grúa de manera longitudinal y transversal determinó entre 10 a 90 ubicaciones donde la carga del puente grúa está concentrada para el análisis. Las cargas contempladas para el análisis y diseño fueron las producidas por carga muerta, carga viva, viento y sismo. Para el diseño de los elementos de las naves industriales se ha considerado la Norma E.090 del Reglamento Nacional de Edificaciones y como complemento se ha utilizado las normas: ASCE y AISC. El diseño de los elementos estructurales se basó en el método LRFD. El resultado de la investigación encontró una zona crítica de diseño en los márgenes izquierdo y derecho de cada modelo. Los valores de ambos márgenes correspondientes a la capacidad de carga del puente grúa son iguales en cada una de sus posiciones simétricas. Se comprobó que en la zona crítica existe una única ubicación que genera los máximos desempeños en los elementos de las naves industriales. Se determinó los ratios de costo de los perfiles de las naves industriales; los cuales, varían entre 51 y 190 dólares por metro cuadrado. / The purpose of this study is to find the critical design area in industrial buildings that combine the premise of different free heights with the location of different load capacities of an overhead crane. A total of nine symmetrical models were proposed in plan with a gabled portico arrangement. The structural system includes frames at the moment and braced frames. The span of the overhead crane longitudinally and transversely determined between 10 to 90 locations where the overhead crane load is concentrated for the analysis. The loads considered for the analysis and design were those produced by dead load, live load, wind and earthquake. For the design of the elements of the industrial buildings, Standard E.090 of the National Building Regulations has been considered and as a complement the following standards have been used: ASCE and AISC. The design of the structural elements was based on the LRFD method. The result of the investigation found a critical design zone on the left and right margins of each model. The values ​​of both margins corresponding to the load capacity of the overhead crane are equal in each of their symmetrical positions. It was found that in the critical zone there is a single location that generates the maximum performances in the elements of the industrial buildings. The cost ratios of the profiles of the industrial buildings were determined; which, vary between 51 and 190 dollars per square meter. / Tesis
452

LIMITING DISTRIBUTIONS AND DEVIATION ESTIMATES OF RANDOM WALKS IN DYNAMIC RANDOM ENVIRONMENTS

Yongjia Xie (12450573) 25 April 2022 (has links)
<p>This dissertation includes my research works during Ph.D. career about three different kinds of random walks in (dynamical) random environments. It includes my two published papers “Functional weak limit of random walks in cooling random environments” which has been published in electronic communications in probability in 2020, and “Variable speed symmetric random walk driven by the simple symmetric exclusion process” which is the joint work with Peterson and Menezes and has been published in electronic journals of probability in 2021. This dissertation also includes my two other projects, one is the joint work with Janjigian and Emrah about moderate deviation and exit time estimates in integrable directed polymer models. The other one is the joint work with Peterson and Conrado that extends the weak limit of random walks in cooling randon environments with underlying environment is in the transient case.</p>
453

Mathématiques discrètes appliquées à la cryptographie symétrique / Mathématiques discrètes appliquées à la cryptographie symétrique

Rotella, Yann 19 September 2018 (has links)
Dans cette thèse, nous étudions la sécurité de primitives cryptographiques. Ces systèmes sont fondés sur des transformations utilisant des objets mathématiques représentés de multiples manières. Nous utilisons alors certaines structures inhérentes à leurs composantes, et jusqu'alors non prises en compte, pour mettre en évidence de nouvelles vulnérabilités. Par l'exploitation de diverses représentations, nous avons ainsi cryptanalysé des chiffrements authentifiés de la compétition CAESAR, des chiffrements à flot spécifiques et des constructions génériques. Nous avons donné des critères de conception en vue de la standardisation par le NIST de chiffrements à bas coût. Dans le cas des chiffrements à flot, nous avons défini de nouveaux critères cryptographiques plus pertinents que les critères usuels. Plus précisément, nous analysons la sécurité des chiffrements par bloc légers au regard des récentes attaques par invariant, et nous montrons comment les éviter par un choix approprié de la couche linéaire de diffusion et des constantes de tour. Nous proposons une nouvelle cryptanalyse des registres filtrés, grâce à la décomposition des éléments dans les sous-groupes multiplicatifs du corps fini à 2^n éléments. L'analyse du chiffrement FLIP, mais aussi du générateur pseudo-aléatoire de Goldreich a mis en évidence des faiblesses exploitables dans des attaques de type ``supposer et déterminer'', qui nécessitent la prise en compte de nouveaux critères sur les fonctions booléennes utilisées dans ce contexte. Enfin, nous cryptanalysons une version simplifiée du chiffrement authentifié Ketje en utilisant plusieurs techniques, permettant ainsi d'affiner l'évaluation de sa sécurité. / In this thesis, we study the security of symmetric cryptographic primitives. These systems are based on transformations relying on mathematical objects that can be represented in multiple ways. We then exploit different induced structures to highlight new vulnerabilities. By exploiting various representations, we cryptanalyzed some schemes submitted to the CAESAR competition, and also some dedicated and generic stream ciphers. We exhibited design criteria for lightweight block ciphers in view of the NIST standardization process and in the case of stream ciphers we defined new cryptographic criteria more relevant than the usual ones. More precisely, we study the security of lightweight block ciphers with respect to the recent invariant attacks, and we show how to avoid them with an appropriate choice of the linear layer and the round constants. We propose a new cryptanalysis of the filtered registers, by decomposing elements in the multiplicative subgroups of the finite field with 2^n elements. The analysis of the FLIP cipher, but also of the Goldreich pseudo-random generator, revealed weaknesses that are exploitable in ``guess and determine'' attacks. This leads to new criteria on the Boolean functions used in this context. Finally, we cryptanalyze a weaker version of the authenticated encryption scheme Ketje using several techniques, in order to refine the security evaluation of this cipher.
454

Facets of a Balanced Minimum Evolution Network Polytope

Durell, Cassandra M. 27 June 2019 (has links)
No description available.
455

WNT7A and EGF Alter Myogenic Differentiation in hiPSCs Derived from Duchenne Muscular Dystrophy Patients

Madana, Maria 22 June 2023 (has links)
Duchenne Muscular Dystrophy (DMD) is a disorder caused by loss-of-function mutations in dystrophin, a critical protein that maintains muscle fiber integrity. Our lab discovered that dystrophin-deficient skeletal muscle stem cells, also known as satellite cells, cannot generate enough myogenic progenitors for proper muscle regeneration. Previously, we demonstrated that WNT7A, a protein expressed during muscle regeneration, stimulates symmetric division of satellite cells, and gives rise to two daughter satellite cells. Conversely, epidermal growth factor (EGF) induces asymmetric division, which generates one daughter satellite cell and one committed precursor cell. We aimed to investigate these satellite cell division mechanisms following WNT7A or EGF treatment in a human model using healthy and DMD-patient derived hiPSCs differentiated into the myogenic lineage. The presence of satellite-like cells was confirmed in both lines by their characteristic expression of PAX7 and other myogenic markers. Intriguingly, DMD-patient hiPSCs precociously differentiated compared to healthy control human induced pluripotent stem cells (hiPSCs). More notably, WNT7A treatment had a potent effect on the DMD differentiated cells. High content analysis revealed an expansion of the satellite-like cell pool as observed by a higher number of PAX7+ cells within the total population and gene expression analysis demonstrated a significant increase in global PAX7 expression. In contrast, EGF treatment reduced the number of PAX7+ cells and increased the proportion of MYOG+ cells within the myogenic population, indicating an increase in myogenic progenitors. Taken together, WNT7A and EGF can alter the myogenic differentiation program of healthy and DMD-patient derived hiPSCs by modulating the satellite-like cell division dynamics.
456

Разработка методики проектирования модели многопроводной системы передачи данных : магистерская диссертация / Development of method of modeling multiconductor data transmission system

Шестаков, А. П., Shestakov, A. P. January 2015 (has links)
Диплом посвящен описанию методики моделирования системы передачи данных на симметричных линии передач. Приведена методика построения моделей систем в программной среде NI AWR Design Environment. Производится разбор этапов построения модели. / Diploma is dedicated to the describe method of modeling of transmission system build upon symmetric transmission lines. Method of modeling in NI AWR Design Environment been presented. An extensive explanation of modeling process is given.
457

Design and Analysis of Non-symmetric Satellite Constellations / Design och analys av icke-symmetriska satellitkonstellationer

Costales, Jomuel Danilo January 2023 (has links)
Satellite constellation design has been a well-studied problem since the beginning of the space age. In recent years new concepts and approaches tried to solve it with fewer satellites whilst guaranteeing coverage to the areas of interest, whether globally or regionally. This thesis introduces a novel approach based on the repeating ground track concept. It then links and converts the constellation design problem to a Set Cover problem. Although it is NP-hard, the Greedy Algorithm is capable to approximate the solution in a polynomial time with a logarithm ratio. An application of the non-symmetric strategy is illustrated with in 36 different scenarios, where altitude, sensor swath and time requirement are varied. In addition to that, a comparison with the Walker constellation on 6 scenarios is analyzed and discussed. In most cases the non-symmetric strategy produces constellations with significantly less satellites required. / Satellitkonstellationsdesign har varit ett väl studerat problem sedan början av rymdåldern. Under de senaste åren har nya koncept och tillvägagångssätt försökt lösa det med färre satelliter samtidigt som de garanterar täckning till intresseområdena, globalt eller regionalt. Detta examensarbete introducerar ett nytt tillvägagångssätt baserat på konceptet med återkommande markspår. Den länkar sedan och konverterar konstellationsdesignproblemet till ett Set Cover-problem. Även om problemet är NP-hårt, är den giriga algoritmen kapabel att approximera lösningen under polynomtid med ett logaritmförhållande. En tillämpning av den icke-symmetriska strategin illustreras med i 36 olika scenarier, där höjd, sensorsvep och tidsbehov varieras. Utöver det analyseras och diskuteras en jämförelse med Walker-konstellationen på 6 scenarier. I de allra flesta fall producerar den icke-symmetriska strategin konstellationer med betydligt färre satelliter.
458

Signings of graphs and sign-symmetric signed graphs

Asiri, Ahmad 08 August 2023 (has links) (PDF)
In this dissertation, we investigate various aspects of signed graphs, with a particular focus on signings and sign-symmetric signed graphs. We begin by examining the complete graph on six vertices with one edge deleted ($K_6$\textbackslash e) and explore the different ways of signing this graph up to switching isomorphism. We determine the frustration index (number) of these signings and investigate the existence of sign-symmetric signed graphs. We then extend our study to the $K_6$\textbackslash 2e graph and the McGee graph with exactly two negative edges. We investigate the distinct ways of signing these graphs up to switching isomorphism and demonstrate the absence of sign-symmetric signed graphs in some cases. We then introduce and study the signed graph class $\mathcal{S}$, which includes all sign-symmetric signed graphs, we prove several theorems and lemmas as well as discuss the class of tangled sign-symmetric signed graphs. Also, we study the graph class $\mathcal{G}$, consisting of graphs with at least one sign-symmetric signed graph, prove additional theorems and lemmas, and determine certain families within $\mathcal{G}$. Our results have practical applications in various fields such as social psychology and computer science.
459

Numerical Methods for the Solution of Linear Ill-posed Problems

Alqahtani, Abdulaziz Mohammed M 28 November 2022 (has links)
No description available.
460

Intraglottal Glottal Pressure Distributions for Three Oblique Glottal Angles

Li, Jun 18 August 2010 (has links)
No description available.

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