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Cherly, Jorgen. "Sommes d'exponentielles cubiques dans l'anneau des polynômes en une variable sur le corps à deux éléments et application au problème de Waring." Bordeaux 1, 1989. http://www.theses.fr/1989BOR10618.
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En termes generaux, dont sont exclus les symboles mathematiques, on peut decrire la these comme une contribution a l'etude du probleme de waring dans le cas de l'anneau des polynomes en une variable sur le corps fini a deux elements, que nous notons f(2,x). Le resultat principal est qu'il existe une constante absolue k telle que tout element de f(2,x) qui est une somme de cubes est somme d'au plus k cubes, avec les restrictions optimales sur les degres des termes. Le degre 3 etant superieur a la caracteristique 2, il n'est pas possible d'appliquer dans ce cas les methodes classiques. L'idee de vaughan de prolonger les arcs majeurs est introduite dans ce contexte d'application de la methode du cercle, et des techniques ad hoc sont developpees pour pallier le manque de methode de phase stationnaire
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Pecatte, Timothée. "Bornes inférieures et algorithmes de reconstruction pour des sommes de puissances affines." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEN029/document.
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Le cadre général de cette thèse est l'étude des polynômes comme objets de modèles de calcul. Cette approche permet de définir de manière précise la complexité d'évaluation d'un polynôme, puis de classifier des familles de polynômes en fonction de leur difficulté dans ce modèle. Dans cette thèse, nous nous intéressons en particulier au modèle AffPow des sommes de puissance de forme linéaire, i.e. les polynômes qui s'écrivent $f = \sum_{i = 1}^s \alpha_i \ell_i^{e_i}$, avec $\deg \ell_i = 1$. Ce modèle semble assez naturel car il étend à la fois le modèle de Waring $f = \sum \alpha_i \ell_i^d$ et le modèle du décalage creux $f = \sum \alpha_i \ell^{e_i}$, mais peu de résultats sont connus pour cette généralisation.Nous avons pu prouver des résultats structurels pour la version univarié de ce modèle, qui nous ont ensuite permis d'obtenir des bornes inférieures et des algorithmes de reconstruction, qui répondent au problème suivant : étant donné $f = \sum \alpha_i (x-a_i)^{e_i}$ par la liste de ses coefficients, retrouver les $\alpha_i, a_i, e_i$ qui apparaissent dans la décomposition optimale de $f$.Nous avons aussi étudié plus en détails la version multivarié du modèle, qui avait été laissé ouverte par nos précédents algorithmes de reconstruction, et avons obtenu plusieurs résultats lorsque le nombre de termes dans une expression optimale est relativement petit devant le nombre de variables ou devant le degré du polynômeThe general framework of this thesis is the study of polynomials as objects of models of computation. This approach allows to define precisely the evaluation complexity of a polynomial, and then to classify families of polynomials depending on their complexity. In this thesis, we focus on the study of the model of sums of affine powers, that is polynomials that can be written as $f = \sum_{i = 1}^s \alpha_i \ell_i^{e_i}$, with $\deg \ell_i = 1$.This model is quite natural, as it extends both the Waring model $f = \sum \alpha_i \ell_i^d$ , and the sparsest shift model $f = \sum \alpha_i \ell^{e_i}$, but it is still not well known.In this work, we obtained structural results for the univariate variant of this model, which allow us to obtain lower bounds and reconstruction algorithms, that solve the following problem : given $f = \sum \alpha_i (x-a_i)^{e_i}$ as a list of its coefficient, find the values of the $\alpha_i$’s, $e_i$’s and $a_i$’s in the optimal decomposition of $f$.We also studied the multivariate case and obtained several reconstruction algorithms that work whenever the number of terms in the optimal expression is small in terms of the number of variable or the degree of the polynomial
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Lambert, Victor. "Quelques problèmes additifs : bases, pseudo-puissances et ensembles k-libres." Palaiseau, Ecole polytechnique, 2015. https://theses.hal.science/tel-01174654/document.
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Habituellement étudié dans N ou Z, on s'intéresse aux bases additives dans les groupes abéliens infinis. On obtient des résultats sur les fonctions E, X et S, qui caractérisent le comportement d'une base lorsqu'on lui enlève un élément. On étudie également l'ensemble A des pseudo-puissances s-ièmes. Celles-ci forment presque sûrement une base additive d'ordre s+1. On cherche à affiner ce résultat en déterminant des compléments additifs de sA de taille minimale, c'est-à-dire des ensembles B tels que sA+B contient presque sûrement tout entier suffisamment grand. Enfin, nous montrons quelle est la taille maximale d'un ensemble k-libre dans Z/nZ. La contrainte modulaire joue ici un rôle prépondérant. Les méthodes employées sont très différentes, selon la relation arithmétique entre k et n. En particulier, nous démontrons un résultat sur des arbres combinatoires, dans l'étude du cas généralWidely studied in N or Z, we are interested in additive bases in infinite abelian groups. We get some results about the functions E, X and S, which caracterize the behaviour of a basis when we remove an element. We also study the set A of pseudo s-th powers, which is an additive basis of order s+1. We wonder what is the minimal size of an additive complement of sA, that is a set B such that sA+B contains all large enough integers. With respect to this problem, we prove quite precise theorems which are tantamount to asserting that a threshold phenomenon occurs. Finally, we establish the maximal size of a k-free set in Z/nZ. The study of this quantity strongly depends on the arithmetical relative properties of n and k. That is why we use different methods depending on cases. In particular, we show a result on combinatorial trees for the general case
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Messias, Daniel Correia Lemos de. "Multiplicidade de anéis 1-dimensionais e uma aplicação ao problema de Waring." Universidade Federal da Paraíba, 2015. http://tede.biblioteca.ufpb.br:8080/handle/tede/9271.
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Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq
Let k be an algebraically closed eld of characteristic zero and consider the polynomial ring S = k[x1, . . . , xn] endowed with the standard grading. The Waring's problem for a form F ∈ S of degree d asks about the least integer s ≥ 1 for which there exist linear forms L1, . . . , Ls ∈ S satisfying F = Σs i=1 Ldi. Such integer is called Waring rank of F. In this dissertation, we present a solution to this problem { due to Carlini-Catalisano-Geramita { in the case of monomials, as an interesting application of a theorem (due to the same authors) that establishes a lower bound for the multiplicity of (standard) graded, nitely generated, reduced, 1-dimensional k-algebras.
Seja k um corpo algebricamente fechado de caracter stica zero e considere o anel de polin^omios S = k[x1, . . . , xn] munido da gradua c~ao padr~ao. O Problema de Waring para uma forma F ∈ S de grau d questiona a respeito do menor inteiro s ≥ 1 para o qual existem formas lineares L1, . . . , Ls ∈ S satisfazendo F = Σs i=1 Ldi. Tal inteiro e denominado posto de Waring de F. Nesta disserta c~ao, apresentamos uma solu c~ao deste problema { devida a Carlini-Catalisano-Geramita { no caso de mon^omios, como uma interessante aplica c~ao de um teorema (dos mesmos autores) que estabelece uma cota inferior para a multiplicidade de k- algebras graduadas (padr~ao) nitamente geradas, reduzidas e 1-dimensionais.
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Cascioli, Chiara. "Varietà algebriche e Problema di Waring." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/17406/.
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L'elaborato inizia con una trattazione sulle varietà algebriche nello spazio proiettivo, mettendo in luce somiglianze e differenze con il caso affine. Vengono dimostrati alcuni teoremi a riguardo, e vengono introdotti i morfismi proiettivi. Viene poi posta l'attenzione su un particolare esempio di morfismo proiettivo, l'embedding di Veronese. Infine viene introdotto il Problema di Waring e viene enunciato il Teorema di Alexander - Hirschowitz tramite il quale si ha una soluzione del problema suddetto.
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Zhao, Lilu, and 赵立璐. "Some results on Waring-Goldbach type problems." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B4832954X.
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This thesis consists of three topics. The first one is on quadratic Waring-Goldbach problems. The second topic is about some additive problems involving fourth powers. The last topic is to consider an average result for the divisor problem in arithmetic progressions.
Chapter 1 is an introduction. In Chapter 2 the Lagrange equation with almost prime variables is studied, based on a method of Heath-Brown and Tolev. The techniques involve the circle method and the sieve method in analytic number theory. It is established that every sufficiently large integer, congruent to 4 modulo 24, can be represented as the sum of four squares of integers, each of which has at most four prime factors. In order to derive the desired result, it is important to study the asymptotic formula for a smooth counting function involving the sum of one square of a prime number and three squares of integers in arithmetic progressions. For this purpose, the square sieve of Heath-Brown and the Kloosterman refinement are employed. This is the main task of Chapter 3.
Chapter 4 is devoted to the investigation on the sum of four squares of primes and K powers of two. Inspired by the work of Wooley, this problem is dealt with by applying the linear sieve instead of the four dimensional vector sieve.
The theme of Chapter 5 is the three squares theorem with almost prime variables, firstly investigated by Blomer and Br?udern. A sharper result is obtained, in this chapter, by developing the three dimensional weighted sieve.
In Chapter 6, the main concern is the exceptional set for the sum of fourth powers. By developing Vaughan's p-adic iteration method, some new estimations are established. The new estimations improve upon the earlier result obtained by Kawada and Wooley. As a consequence of the new estimates, it is established that every sufficiently large integer under a natural congruence condition can be expressed as a sum of six fourth powers of primes and six fourth powers of integers. Moreover, a pair of diagonal quartic forms is considered. In Chapter 7, it is shown that a pair of diagonal quartic equations with 23 variables has nonzero integral solutions under certain reasonable conditions.
The purpose of Chapter 8 is to consider a Waring-Goldbach type problem involving twelve fourth powers of primes and one fourth power of a positive integer. The idea of proof is to combine Chen's switching principle and Iwaniec's linear sieve. A new result is obtained, which refines that of Ren and Tsang on this topic.
In the last chapter, a distribution problem for the divisor function on arithmetic progressions is investigated. Denote by ?q,b(X) the error term in the divisor problem in the arithmetic progression b(mod q). New asymptotic formulae for the variance A(q, X) =?qb=1|?q,b(x)|2 for X1=4+E ?· q?·X1=2-E and X1=2+E ? q ·?X1-E are derived. The distinct behaviors of A(q, X) in these two ranges are unveiled.published_or_final_version
Mathematics
Doctoral
Doctor of Philosophy
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Oneto, Alessandro. "Power ideals, Fröberg conjecture and Waring problems." Licentiate thesis, Stockholms universitet, Matematiska institutionen, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-103504.
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This thesis is divided into two chapters. First, we want to study particularclasses of power ideals, with particular attention to their relation with the Fröberg conjecture on the Hilbert series of generic ideals. In the second part,we study a generalization (introduced by Fröberg, Ottaviani, and Shapiro in 2012)of the classical Waring problem for polynomials about writing homogeneouspolynomials as sums of powers. We see also how the theories of fat points andsecant varieties of Veronese varieties play a crucial role in the relation betweenthose chapters and in providing tools to nd an answer to our questions. The main results are the computation of the Hilbert series of particularclasses of power ideals, which in particular give us a proof of the Fröberg conjecturefor generic ideals generated by eight homogeneous polynomials of thesame degree in four variables, and the solution of the generalized Waring problemin the case of sums of squares in three and four variables. We also beginthe study of the generalized Waring problem for monomials.
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Oneto, Alessandro. "Waring-type problems for polynomials : Algebra meets Geometry." Doctoral thesis, Stockholms universitet, Matematiska institutionen, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-129019.
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In the present thesis we analyze different types of additive decompositions of homogeneous polynomials. These problems are usually called Waring-type problems and their story go back to the mid-19th century and, recently, they received the attention of a large community of mathematicians and engineers due to several applications. At the same time, they are related to branches of Commutative Algebra and Algebraic Geometry. The classical Waring problem investigates decompositions of homogeneous polynomials as sums of powers of linear forms. Via Apolarity Theory, the study of these decompositions for a given polynomial F is related to the study of configuration of points apolar to F, namely, configurations of points whose defining ideal is contained in the ``perp'' ideal associated to F. In particular, we analyze which kind of minimal set of points can be apolar to some given polynomial in cases with small degrees and small number of variables. This let us introduce the concept of Waring loci of homogeneous polynomials. From a geometric point of view, questions about additive decompositions of polynomials can be described in terms of secant varieties of projective varieties. In particular, we are interested in the dimensions of such varieties. By using an old result due to Terracini, we can compute these dimensions by looking at the Hilbert series of homogeneous ideal. Hilbert series are very important algebraic invariants associated to homogeneous ideals. In the case of classical Waring problem, we have to look at power ideals, i.e., ideals generated by powers of linear forms. Via Apolarity Theory, their Hilbert series are related to Hilbert series of ideals of fat points, i.e., ideals of configurations of points with some multiplicity. In this thesis, we consider some special configuration of fat points. In general, Hilbert series of ideals of fat points is a very active field of research. We explain how it is related to the famous Fröberg's conjecture about Hilbert series of generic ideals. Moreover, we use Fröberg's conjecture to deduce the dimensions of several secant varieties of particular projective varieties and, then, to deduce results regarding some particular Waring-type problems for polynomials. In this thesis, we mostly work over the complex numbers. However, we also analyze the case of classical Waring decompositions for monomials over the real numbers. In particular, we classify for which monomials the minimal length of a decomposition in sum of powers of linear forms is independent from choosing the ground field as the field of complex or real numbers.
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Cardoso, Júnior Abílio Lemos. "O anel dos vetores de Witt e o problema de Waring." reponame:Repositório Institucional da UnB, 2011. http://repositorio.unb.br/handle/10482/6725.
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Dissertação (mestrado)-Universidade de Brasília, Instituto de Ciências Exatas, Departamento de Matemática, 2006.Texto parcialmente liberado pelo autor.
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Neste trabalho, fazemos um estudo geral do anel de valorização discreta completo. Construímos o anel dos vetores deWitt, denotado por W(A), com coeficientes em um anel comutativo com unidade A. Definimos W(k), onde k é um corpo perfeito de característica p, e mostramos que W(k) é um anel de valorização discreta completo não ramificado. Em seguida tomamos k algébrico sobre Fp e concluímos que W(k) é, a menos de isomorfismo, a única extensão completa não ramificada de Zp. Por fim, aplicamos o problema de Waring para W(k). _________________________________________________________________________________ ABSTRACT
In this work we study complete discrete valuation rings. We construct the ring of Witt vectors, denoted by W(A), with components in a commutative ring with unity A. We define W(k), where k is a perfect field of characteristc p, and prove that W(k), defined in this way, is a complete discrete unramified valuation ring. Afterwards, we take k algebraic over Fp and we conclude that W(k) is, up to isomorphism, the unique complete unramified extension of Zp. Finally, we apply the Waring’s problem to W(k).
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Hoffman, John W. "Some Problems in Additive Number Theory." Kent State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=kent1408298984.
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Alnaser, Ala' Jamil. "Waring's problem in algebraic number fields." Diss., Manhattan, Kan. : Kansas State University, 2009. http://hdl.handle.net/2097/2207.
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Cipra, James Arthur. "Waring’s number in finite fields." Diss., Kansas State University, 2010. http://hdl.handle.net/2097/4152.
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Doctor of PhilosophyDepartment of Mathematics
Todd E. Cochrane
This thesis establishes bounds (primarily upper bounds) on Waring's number in finite fields. Let $p$ be a prime, $q=p^n$, $\mathbb F_q$ be the finite field in $q$ elements, $k$ be a positive integer with $k|(q-1)$ and $t= (q-1)/k$. Let $A_k$ denote the set of $k$-th powers in $\mathbb F_q$ and $A_k' = A_k \cap \mathbb F_p$. Waring's number $\gamma(k,q)$ is the smallest positive integer $s$ such that every element of $\mathbb F_q$ can be expressed as a sum of $s$ $k$-th powers. For prime fields $\mathbb F_p$ we prove that for any positive integer $r$ there is a constant $C(r)$ such that $\gamma(k,p) \le C(r) k^{1/r}$ provided that $\phi(t) \ge r$. We also obtain the lower bound $\gamma(k,p) \ge \frac {(t-1)}ek^{1/(t-1)}-t+1$ for $t$ prime. For general finite fields we establish the following upper bounds whenever $\gamma(k,q)$ exists: $$ \gamma(k,q)\le 7.3n\left\lceil\frac{(2k)^{1/n}}{|A_k^\prime|-1}\right\rceil\log(k), $$ $$ \gamma(k,q)\le8n \left\lceil{\frac{(k+1)^{1/n}-1}{|A^\prime_k|-1}}\right\rceil, $$ and $$ \gamma(k,q)\ll n(k+1)^{\frac{\log(4)}{n\log|\kp|}}\log\log(k). $$ We also establish the following versions of the Heilbronn conjectures for general finite fields. For any $\ve>0$ there is a constant, $c(\ve)$, such that if $|A^\prime_k|\ge4^{\frac{2}{\ve n}}$, then $\gamma(k,q)\le c(\varepsilon) k^{\varepsilon}$. Next, if $n\ge3$ and $\gamma(k,q)$ exists, then $\gamma(k,q)\le 10\sqrt{k+1}$. For $n=2$, we have $\gamma(k,p^2)\le16\sqrt{k+1}$.
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Wooley, Trevor Dion. "On simultaneous additive equations and Waring's problem." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/46614.
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Kimmel, Randall K. "Can Statistics Based Early Warning Systems Detect Problem Banks Before Markets?" Kent State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=kent1309322520.
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Chen, Kejie [Verfasser], and Michael H. [Akademischer Betreuer] Weber. "Real-time GNSS for fast seismic source inversion and tsunami early warning / Kejie Chen ; Betreuer: Michael H. Weber." Potsdam : Universität Potsdam, 2016. http://d-nb.info/1218400633/34.
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Chen, Kejie [Verfasser], and Michael [Akademischer Betreuer] Weber. "Real-time GNSS for fast seismic source inversion and tsunami early warning / Kejie Chen ; Betreuer: Michael H. Weber." Potsdam : Universität Potsdam, 2016. http://d-nb.info/1218400633/34.
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Dureab, Fekri [Verfasser], and Albrecht [Akademischer Betreuer] Jahn. "The usefulness of the electronic Disease Early Warning System (eDEWS) in the humanitarian crisis of Yemen / Fekri Dureab ; Betreuer: Albrecht Jahn." Heidelberg : Universitätsbibliothek Heidelberg, 2020. http://d-nb.info/1211989712/34.
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Helland, Per Kristian. "A Survey of Combining Association Rules for Pre-warning of Oil Production Problems." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for datateknikk og informasjonsvitenskap, 2007. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-16746.
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Periods of sub-optimal production rates, or complete shut-downs, add negative numbers to the revenuegraph for oil companies. Oil and gas are produced from several reservoirs and through many wells withvarying gas/oil proportion, making it a complex process that is difficult to control. As a part of a threestepprocess for utilizing data in the oil production domain, this thesis derive methods for combiningevent patterns, called restricted association rules, in time series in order to warn about future anomalies inoil production processes. Two problems have been considered: Network learning and network reasoning.The suggested solution consists of building an Association Rules Network (ARN) from the rule set givenas input. After transforming the hypergraph-based ARN to a directed acyclic graph, correlations betweennodes are found by applying the shortest-path principle. Motivated by the shortcomings of this simplesolution, it is shown how a method for learning Bayesian networks with support for representation oftemporal dependencies can be derived from the initial ARN. The concept, named Temporal BayesianNetwork of Events (TBNE), is a powerful, but yet complex solution that enjoys the properties of Bayesiannetwork reasoning while at the same time representing temporal information. This thesis has shown thatit is theoretically feasible to combine restricted association rules in order to create a network structurefor reasoning. It is concluded that the final choice of solution must be based on a carefully considerationof the trade-off between complexity and expressiveness, and that a natural continuation is testing thesuggested concepts with real data.
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Sättele, Martina [Verfasser], Daniel [Akademischer Betreuer] Straub, and Michael [Akademischer Betreuer] Krautblatter. "Quantifying the Reliability and effectiveness of Early Warning Systems for Natural Hazards / Martina Sättele. Gutachter: Michael Krautblatter ; Daniel Straub. Betreuer: Daniel Straub." München : Universitätsbibliothek der TU München, 2015. http://d-nb.info/1072500825/34.
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Setiadi, Neysa Jacqueline [Verfasser]. "Assessing people´s early warning response capability to inform urban planning interventions to reduce vulnerability to tsunamis : case study of Padang City, Indonesia / Neysa Jacqueline Setiadi." Bonn : Universitäts- und Landesbibliothek Bonn, 2020. http://d-nb.info/1206336773/34.
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Setiadi, Neysa [Verfasser]. "Assessing people´s early warning response capability to inform urban planning interventions to reduce vulnerability to tsunamis : case study of Padang City, Indonesia / Neysa Jacqueline Setiadi." Bonn : Universitäts- und Landesbibliothek Bonn, 2020. http://nbn-resolving.de/urn:nbn:de:101:1-2020031201583794741001.
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Setiadi, Neysa [Verfasser]. "Assessing People´s Early Warning Response Capability to Inform Urban Planning Interventions to Reduce Vulnerability to Tsunamis : Case Study of Padang City, Indonesia [[Elektronische Ressource]] / Neysa Setiadi." Bonn : Universitäts- und Landesbibliothek Bonn, 2014. http://d-nb.info/1048677052/34.
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Kovner, Nimrod Z. "Migration in a warming world : on the responsibility and obligations of states towards climate change immigrants." Thesis, London School of Economics and Political Science (University of London), 2017. http://etheses.lse.ac.uk/3582/.
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People across the globe are on the move due to environmental disruption and degradation, causing them to travel and find their future in new locations. Climate change will increase the number of people seeking to escape environmental pressures. What should be the appropriate response to this increase of migrating people, driven away from their homes as a result of climate change effects? From the perspective of normative political philosophy, it is more precise to ask two interrelated questions: what are the obligations in the context of climate change migration and to who should assign them. Previous research in normative political philosophy has focused on the high-profile case of small island states that can be submerged by the rising levels of the oceans, overlooking the wider ways in which human mobility will be induced by climate change effects. The thesis, then, fills this gap in the literature and provides a nuanced account that combines insights from political philosophy and writing on climate change and immigration. My dissertation answers the two above-mentioned questions, dedicating the first part to the ‘who’ question and taking up the ‘what’ question in the second part. The overall argument shows that states creating hazardous climate change incur obligations towards those adversely affected by it, including those relocating across international borders. And these states ought to amend or supplement their immigration policy in a way that advances the capacity of vulnerable individuals to cope with climate change. In the first part of the thesis, I establish state responsibility for the adverse effects of climate change, primarily focusing on its relation with duties towards climate change adaptation. I work with a backward-looking principle of responsibility, responsibility for causing bad outcomes, and explore its application to the case of climate change in the face of some conceptual and empirical challenges. I further develop a notion of responsibility for creating risk that can capture the collective adverse outcome states bring about by emitting greenhouse gases. I explicate the moral significance of imposing risks on others and the obligations that it gives rise to. Building on this theoretical groundwork, the second part of the thesis dives into the complex nexus of climate change and human mobility. I focus on a particular pattern of immigrationinternational movement due to gradual environmental changes associated with climate change that significantly restrict people’s life prospects. I defend a view that perceives such migratory scenarios as a way to cope with climate change, a form of adaptation. I argue that the obligations of states include providing admission to climate immigrants. However, they are part of a wider set of actions and policies to advance the adaptation capacity of all individuals vulnerable to climate change hazards: immigrants themselves, but also the immobile. This part of thesis shows that the adaptation duty of states is a complex balancing act between providing admission and supporting local adaptation. The last chapter elaborates on this challenge. Drawing on the research on climate immigration, I highlight the aspects of this movement that must be considered in a morally informed immigration policy. In addition, I put forward the possibility that states can allocate among themselves their obligations so some will do more in terms of admitting immigrants and some will do more in terms of supporting local adaptation.
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Battini, Jean-Marc. "Co-rotational beam elements in instability problems." Doctoral thesis, KTH, Byggkonstruktion, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3284.
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The purpose of the work presented in this thesis is to implement co-rotational beam elements and branch-switching procedures in order to analyse elastic and elastoplasticinstability problems. For the 2D beam elements, the co-rotational framework is taken from Crisfield [23]. The main objective is to compare three different local elasto-plastic elements. The 3D co-rotational formulation is based on the work of Pacoste and Eriksson [73],with new items concerning the parameterisation of the finite rotations, the definitionof the local frame, the inclusion of warping effects through the introduction of aseventh nodal degree of freedom and the consideration of rigid links. Differenttypes of local formulations are considered, including or not warping effects. It isshown that at least some degree of non-linearity must be introduced in the localstrain definition in order to obtain correct results for certain classes of problems. Within the present approach any cross-section can be modelled, and particularly, the centroid and shear center are not necessarily coincident.Plasticity is introduced via a von Mises material with isotropic hardening. Numericalintegration over the cross-section is performed. At each integration point, theconstitutive equations are solved by including interaction between the normal andshear stresses. Concerning instabilities, a new numerical method for the direct computation of elasticcritical points is proposed. This is based on a minimal augmentation procedure asdeveloped by Eriksson [32–34]. In elasto-plasticity, a literature survey, mainly concernedwith theoretical aspects is first presented. The objective is to get a completecomprehension of the phenomena and to give a basis for the two branch-switchingprocedures presented in this thesis.A large number of examples are used in order to assess the performances of the elements and the path-following procedures.QC 20100512
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Mendoza, Malia Leonor [Verfasser], Matthias [Akademischer Betreuer] Becker, Davila Jose [Akademischer Betreuer] Martin, and Üwe [Akademischer Betreuer] Sörgel. "Near Real-Time High-Rate GPS Data Analysis for Earthquake and Tsunami Early Warning / Leonor Mendoza Malia. Betreuer: Matthias Becker ; Jose Martin Davila ; Üwe Sörgel." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2015. http://d-nb.info/1111910251/34.
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Baumert, Niklas [Verfasser], Heiko [Akademischer Betreuer] Faust, and Jörn [Akademischer Betreuer] Birkmann. "Advancing Risk and Vulnerability Assessment for Decision-Making and Research : Case Study from the German-Indonesian Tsunami Early Warning System (GITEWS) Project / Niklas Baumert. Betreuer: Heiko Faust. Gutachter: Heiko Faust ; Jörn Birkmann." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2016. http://d-nb.info/1095884069/34.
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Rohloff, Amanda. "Climate change, moral panic, and civilization : on the development of global warming as a social problem." Thesis, Brunel University, 2012. http://bura.brunel.ac.uk/handle/2438/6973.
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This study combines moral panic with the figurational sociology of Norbert Elias to explore how climate change has developed as a social problem. The central argument is that,through combining the short-term focus of moral panic with the long-term focus of Elias, we can examine the interplay between planned and unplanned developments in both the perception and reality of climate change. The first part of the research consisted of discourse analysis of a variety of different texts from 1800 to the present. These were used to explore the long-term development of climatechange as emerging from an ecological civilizing process. The second stage of the research related these developments to moral panics, arguing that the emergence of climate change can only be understood by exploring the interplay between long-term processes and short-term campaigns. The third part of the research explored these historical developments at the individual level, examining the notion of individual ecological civilizing processes. 15 semi-structured interviews were undertaken with climate change ‘activists’ and ‘non-activists’, comparing how their biographical developments related to ecological civilizing processes and moral panics. The final part of the research compared climate change with five other empirical examples of moral panics, to explore the civilizing and decivilizing processes and civilizing offensives that occur before, during, and after the panics. The central aim was to demonstrate the complexity of moral panics, and to aid in the reformulation of the concepts of moral panic and decivilization. Through a synthesis of Elias and moral panic, as applied to the example of climate change, this study aimed to: critically assess the development of climate change; to reassess the concept of decivilization and the relation between civilizing processes and offensives; and to reformulate the concept of moral panic, including suggesting how moral panic research ought to be undertaken.
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Zhou, Feng. "Spatial, Temporal and Spatio-Temporal Correspondence for Computer Vision Problems." Research Showcase @ CMU, 2014. http://repository.cmu.edu/dissertations/410.
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Many computer vision problems, such as object classification, motion estimation or shape registration rely on solving the correspondence problem. Existing algorithms to solve spatial or temporal correspondence problems are usually NP-hard, difficult to approximate, lack flexible models and mechanism for feature weighting. This proposal addresses the correspondence problem in computer vision, and proposes two new spatio-temporal correspondence problems and three algorithms to solve spatial, temporal and spatio-temporal matching between video and other sources. The main contributions of the thesis are: (1) Factorial graph matching (FGM). FGM extends existing work on graph matching (GM) by finding an exact factorization of the affinity matrix. Four are the benefits that follow from this factorization: (a) There is no need to compute the costly (in space and time) pairwise affinity matrix; (b) It provides a unified framework that reveals commonalities and differences between GM methods. Moreover, the factorization provides a clean connection with other matching algorithms such as iterative closest point; (c) The factorization allows the use of a path-following optimization algorithm, that leads to improved optimization strategies and matching performance; (d) Given the factorization, it becomes straight-forward to incorporate geometric transformations (rigid and non-rigid) to the GM problem. (2) Canonical time warping (CTW). CTW is a technique to temporally align multiple multi-dimensional and multi-modal time series. CTW extends DTW by incorporating a feature weighting layer to adapt different modalities, allowing a more flexible warping as combination of monotonic functions, and has linear complexity (unlike DTW that has quadratic). We applied CTW to align human motion captured with different sensors (e.g., audio, video, accelerometers). (3) Spatio-temporal matching (STM). Given a video and a 3D motion capture model, STM finds the correspondence between subsets of video trajectories and the motion capture model. STM is efficiently and robustly solved using linear programming. We illustrate the performance of STM on the problem of human detection in video, and show how STM achieves state-of-the-art performance.
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Lian, Duan. "Bayesian methods for inverse problems." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:b4000e98-7d56-4274-8210-a22b04be436c.
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This thesis describes two novel Bayesian methods: the Iterative Ensemble Square Filter (IEnSRF) and the Warp Ensemble Square Root Filter (WEnSRF) for solving the barcode detection problem, the deconvolution problem in well testing and the history matching problem of facies patterns. For the barcode detection problem, at the expanse of overestimating the posterior uncertainty, the IEnSRF efficiently achieves successful detections with very challenging real barcode images which the other considered methods and commercial software fail to detect. It also performs reliable detection on low-resolution images under poor ambient light conditions. For the deconvolution problem in well testing, the IEnSRF is capable of quantifying estimation uncertainty, incorporating the cumulative production data and estimating the initial pressure, which were thought to be unachievable in the existing well testing literature. The estimation results for the considered real benchmark data using the IEnSRF significantly outperform the existing methods in the commercial software. The WEnSRF is utilised for solving the history matching problem of facies patterns. Through the warping transformation, the WEnSRF performs adjustment on the reservoir features directly and is thus superior in estimating the large-scale complicated facies patterns. It is able to provide accurate estimates of the reservoir properties robustly and efficiently with reasonably reliable prior reservoir structural information.
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Christiansen, Joacim Lunewski. "A Framework for discovering Interesting Rules from Event Sequences with the purpose of pre-warning Oil Production Problems." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for datateknikk og informasjonsvitenskap, 2007. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-16748.
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Periods of sub-optimal production rates, or complete shut-downs, add negative numbers to the revenue graph for oil companies. Oil and gas are produced from several reservoirs and through many wells with varying gas/oil proportion, making it a complex process that is difficult to control. As a part of a three step process for utilizing data in the oil production domain, this thesis derive methods for discovering event patterns, called restricted association rules, from time series in order to pre-warn about future problems in oil production processes. A restricted rule syntax and semantics is derived to explicitly target rules suited for prediction. Based on the defined rule syntax, a two step process is derived where restricted rule mining based on the concept of minimal occurrences is used to discover restricted association rules from a sequence of events. Next, redundant rules are removed based on the concept of minimum improvement and chaining of rules, during a rule selection phase. Information theory is applied in order to identify the most interesting rules, which can be submitted to an expert for validation. Both a simple solution for easy implementation in ConocoPhillips and a more advanced solution appropriate for general prediction cases are derived. This thesis concludes that it is feasible to discover dependencies between events from actual process data. It is also concluded that a large number of rules can be pruned, in order to get a manageable set of rules which is believed to have good predictive performance.
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Silva, Henrique Furia. "Formulação do problema da torção uniforme em barras de seção transversal maciça." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/3/3144/tde-20022006-150915/.
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O escopo do trabalho é estudar o problema da torção uniforme em barras de seção maciça e resolvê-lo analiticamente para obter o momento de inércia à torção da seção transversal e os deslocamentos ao longo de toda a barra. Este trabalho foi desenvolvido no contexto da Teoria da Elasticidade, utilizando o método semi-inverso para determinar as equações de Saint-Venant para a torção uniforme. As seções em forma de elipse e triângulo eqüilátero foram resolvidas utilizando a função de tensão de Prandtl, a função empenamento e a sua conjugada harmônica. A seção retangular foi resolvida utilizando as funções empenamento e de Prandtl desenvolvidas em séries infinitas. Foi desenvolvida uma formulação matricial utilizando o Método de Galerkin para resolver problemas que não possuem solução fechada.The main purpose of this essay is to present the issue of the uniform torsion in solid section bars and to solve it analytically to achieve the moment of inertia to the torsion of the transversal section and the displacements throughout the whole bar. This essay was developed in the Elasticity Theory context, using the semi-inverse method to determine the Saint-Venant equations to the uniform torsion. The sections in ellipse and equilateral triangle were solved using the Prandtl stress function, the warping function and its harmonic conjugate. The rectangular section was solved using the warping and the Prandtl functions developed in infinite series. A formulation based on matrixes was developed using the Galerkin method to solve problems that do not have closed solution.
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Bikic, Sabina, and Alexander Sheibani. "Att bedöma eller inte bedöma problem med fortsatt drift, det är frågan : En kvantitativ studie om revisorns bedömning av fortsatt drift." Thesis, Linköpings universitet, Företagsekonomi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-141952.
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Introduktion: Bedömning av fortsatt drift är ett område som vållar många revisorer bekymmer. Samtidigt är det en fundamental förutsättning för att utföra revision av hög kvalitet. Tidigare studier inom området har studerat fenomenet utifrån sekundärdata. Denna studie ämnar att använda sig av primärdata utifrån alternativ forskningsmetod för att komplettera tidigare studier ur en svensk kontext. Syfte: Syftet med denna studie är att förklara skillnaderna i revisorns bedömning av fortsatt drift. Metod: Studien utgår från en kvantitativ forskningsmetod och en deduktiv ansats. En tvärsnittsdesign har använts och empirin har samlats in från auktoriserade revisorer genom en enkätundersökning. Detta har kompletterats med kvalitativ data som har samlats in genom uppföljningsintervjuer. Slutsats: Studiens resultat indikerar att revisorer är en homogen grupp och att det finns ett antal bakomliggande faktorer som är avgörande vid bedömning av fortsatt drift, såsom dialog med klienten och tillgång till klientens framtidsorienterade lönsamhetsinformation.Introduction: Going concern assessment is a subject that causes many auditors anxiety. At the same time it is a fundamental prerequisite for performing audit of high quality. Previous studies in the field have studied the phenomenon based on secondary data. This study aims at using primary data based on alternative research methods to supplement earlier studies through a Swedish context. Purpose: The purpose of this study is to explain the differences in the auditor’s going concern assessment. Method: The study is based on a quantitative research method with a deductive approach. A cross-sectional design has been used and research data has been collected through auditor’s participation through a survey. This study has been supplemented with qualitative data collected through follow- up interviews Conclusion: The result of the study indicate that auditors are a homogeneous group and that there are a number of underlying factors that are crucial in assessing going concern, such as ongoing dialogue with client and access to the clients future oriented profitability information.
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Tong, Daoqin. "Continuous space facility location for covering spatial demand objects." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1186686117.
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Ghidelli, Luca. "On Gaps Between Sums of Powers and Other Topics in Number Theory and Combinatorics." Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/40014.
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One main goal of this thesis is to show that for every K it is possible to find K consecutive natural numbers that cannot be written as sums of three nonnegative cubes. Since it is believed that approximately 10% of all natural numbers can be written in this way, this result indicates that the sums of three cubes distribute unevenly on the real line. These sums have been studied for almost a century, in relation with Waring's problem, but the existence of ``arbitrarily long gaps'' between them was not known. We will provide two proofs for this theorem. The first is relatively elementary and is based on the observation that the sums of three cubes have a positive bias towards being cubic residues modulo primes of the form p=1+3k.
Thus, our first method to find consecutive non-sums of three cubes consists in searching them among the natural numbers that are non-cubic residues modulo ``many'' primes congruent to 1 modulo 3. Our second proof is more technical: it involves the computation of the Sato-Tate distribution of the underlying cubic Fermat variety {x^3+y^3+z^3=0}, via Jacobi sums of cubic characters and equidistribution theorems for Hecke L-functions of the Eisenstein quadratic number field Q(\sqrt{-3}). The advantage of the second approach is that it provides a nearly optimal quantitative estimate for the size of gaps: if N is large, there are >>\sqrt{log N}/(log log N)^4 consecutive non-sums of three cubes that are less than N. According to probabilistic models, an optimal estimate would be of the order of log N / log log N.
In this thesis we also study other gap problems, e.g. between sums of four fourth powers, and we give an application to the arithmetic of cubic and biquadratic theta series. We also provide the following additional contributions to Number Theory and Combinatorics: a derivation of cubic identities from a parameterization of the pseudo-automorphisms of binary quadratic forms; a multiplicity estimate for multiprojective Chow forms, with applications to Transcendental Number Theory; a complete solution of a problem on planar graphs with everywhere positive combinatorial curvature.
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Chvatík, Štěpán. "Asynchronní motor s vnějším rotorem." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018. http://www.nusl.cz/ntk/nusl-377075.
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潘國隆. "ON POLYNOMIAL WARING--GOLDBACH PROBLEM." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/05491016704353515036.
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Chang, Seng Denis [Verfasser]. "Disaster risk preparedness : the role of risk governance, multi-institutional arrangements and polycentric frameworks for a resilient tsunami early warning system in Indonesia / vorgelegt von Denis Chang Seng." 2010. http://d-nb.info/1007679425/34.
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Liao, Min-wen, and 廖敏雯. "The Study on The Identification of Problem Bank and The Establishment of Early Warning System in Taiwan." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/92280094766862417734.
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碩士義守大學
財務金融學系碩士班
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Owing to the rapid change of financial and banking operational environment and the opening of financial and banking industry ,the operational environment has serious competition and had become the situation of over banking ,for the banking industry ,it must have good operation strategies and marketing methods and financial structure ,otherwise ,it will meet the bank crisis and failure . To avoid the occurrence of problem bank, firstly, what is the identification of problem bank, how to set up management standard and execution procedure, and how to choose a good method to proceed the assessment indicator and operational procedure, at last, according to the generation reasons of problem bank to construct an effective financial early warning system. It has practical value for the study of problem bank. This research will choose the open financial statement of bank as the assessment base ,at first ,selecting the affected variable by the literature review to get the important variable of banking crisis and obtaining seven topics and thirteen components by the factor analysis ,and then, mail to the second questionnaire which has designed on the key affected variable of problem bank to get the weight of the affected variable by the fuzzy analytical hierarchy process （FAHP）,and then, to set up an assessment model of problem bank .Finally, proceeding the practical test with the sample supported by the bank which is Public Offering to understand the comprehensive and practicable situation of assessment indicator and method, and as the application base for the construction early warning system, and the referred base and executing the check of bank for the financial supervisory commission, Executive Yuan. Verify some in the model, utilize six items of assessment indexes , such as Jenson α, Sharpe index , Treynor index , after tax net profit rate of increase , opening in the interests rate of increase , camp to accept rate of increase ,etc., find after analysing via Fama-MacBeth, this research institute finance early warning system Sharpe index and camp in next season constructed to build charge rate of increase it has to be quite apparent prediction ability, the relevant degree with apparent margin appears too in Jenson α, in Treynor index, after tax net profit rate of increase, open although interests rate of increase appear apparent, but positive correlation appears.
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Trunečková, Daniela. "Reprezentace problému klimatických změn v tištěných médiích." Master's thesis, 2015. http://www.nusl.cz/ntk/nusl-336478.
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This diploma thesis on Representation of the problem of climate change in the print media is a content analysis of Czech quality daily newspapers, namely Hospodářské noviny, Lidové noviny, Mladá fronta DNES and Právo. It deals with the way the selected daily newspapers presented debate on global climate change in 2013-2014. The theoretical part informs readers about the basic concepts and definitions and introduces them to the problem. The empirical part answers the question of whether the media coverage of global climate change in Czech quality daily newspapers is consistent with scientific findings of the international climate discourse represented by Intergovernmental Panel on Climate Change (IPCC) or whether it relies equally on opinions of the small group of so called climate skeptics who question the general consensus of the scientific comunity regarding the causes and consequences of climate change or the need of adequate measures. The results of research indicated that most of analyzed articles informed about climate change the same way as the main climatological research. The largest number of skeptical articles appeared in Lidové noviny. A considerable number of articles didn't comment on the causes of climate change, their seriousness or decisions regarding action.
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Ray, Cody W. "Modeling, control, and estimation of flexible, aerodynamic structures." Thesis, 2012. http://hdl.handle.net/1957/29477.
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Engineers have long been inspired by nature's flyers. Such animals navigate complex environments gracefully and efficiently by using a variety of evolutionary adaptations for high-performance flight. Biologists have discovered a variety of sensory adaptations that provide flow state feedback and allow flying animals to feel their way through flight. A specialized skeletal wing structure and plethora of robust, adaptable sensory systems together allow nature's flyers to adapt to myriad flight conditions and regimes. In this work, motivated by biology and the successes of bio-inspired, engineered aerial vehicles, linear quadratic control of a flexible, morphing wing design is investigated, helping to pave the way for truly autonomous, mission-adaptive craft. The proposed control algorithm is demonstrated to morph a wing into desired positions. Furthermore, motivated specifically by the sensory adaptations organisms possess, this work transitions to an investigation of aircraft wing load identification using structural response as measured by distributed sensors. A novel, recursive estimation algorithm is utilized to recursively solve the inverse problem of load identification, providing both wing structural and aerodynamic states for use in a feedback control, mission-adaptive framework. The recursive load identification algorithm is demonstrated to provide accurate load estimate in both simulation and experiment.Graduation date: 2012