The project considers the class of deterministic continuous-time optimal control problems (OCPs) with piecewise-affine (PWA) vector fields and polynomial data. The OCP is relaxed as an infinite-dimensional linear program (LP) over space of occupation measures. The LP is then written as a particular instance of the generalized moment problem which is then approached by an asymptotically converging hierarchy of linear matrix inequality (LMI) relaxations. The relaxed dual of the original LP gives a polynomial approximation of the value function along optimal trajectories. Based on this polynomial approximation, a novel suboptimal policy is developed to construct a state feedback in a sample-and-hold manner. The results show that the suboptimal policy succeeds in providing a stabilizing suboptimal state feedback law that drives the system relatively close to the optimal trajectories and respects the given constraints.

Dynamic behavior of flexural-torsional coupled vibration of rotating beams using the Rayleigh-Ritz method with orthogonal polynomials as basis functions is studied. The present work starts from a review of the development and analysis of four basic types of beam theories: the Euler-Bernoulli, Rayleigh, Shear and Timoshenko and goes over to a study of flexural-torsional coupled vibration analysis using basic beam theories. In obtaining natural frequencies, orthogonal polynomials used in the Rayleigh-Ritz method are studied as an efficient way of getting results. The study is also performed for both non-rotating and rotating beams. Orthogonal polynomials and functions studied in the present work are : Legendre, Chebyshev, integrated Legendre, modified Duncan polynomials, the eigenfunctions of a pinned-free uniform beam, and the special trigonometric functions used in conjunction with Hermite cubics. Studied cases are non-rotating and rotating Timoshenko beams, bending-torsion coupled beam with free-free boundary conditions, a cantilever beam, and a rotating cantilever beam. The obtained natural frequencies and mode shapes are compared to those available in various references and results for coupled flexural-torsional vibrations are compared to both previously available references and with those obtained using NASTRAN finite element package. / Master of Science

Soft robotics are robots, manipulators, and technologies using soft/compliant materials as the key elements of the robotic bodies instead of traditional rigid materials like metals. However, they face problems in the following areas: 1. Low energy density. In many cases of soft robots, the large blocks of elastomer are barely stiff enough for self-supporting and working as end-effectors, let alone high-speed motion or high-force manipulation. 2. Inconvenient actuation methods. The most widely used actuation method of soft robots is fluidic pumping to the elastomeric bodies, which is called pneumatic networks (Pneu-Nets). However, the tube and pipe system dissipate too much energy via viscous friction, leading to a low energy efficiency, especially when the actuation frequency is high. 3. Difficulty in estimating robotic morphology or motion trajectory. The elastic body of a soft robot is usually made of an infinite number of tiny elastic cubes that deform continuously. Each of the cubes has six degrees of freedom (DOF), and they all together form an integrated constitutive equation that has a number of six times DOF coefficients, even if we only consider statics or pseudo-statics. During dynamic analysis, the comparable magnitudes of elastic energy, kinetic energy, and gravitational energy make the calculations even harder. With the inspiration from the prestressing assembly and the snapping of a steel hair clip, this work proposes that we use a prestressed bistable self-interacting kinked ribbon, which we term hair clip mechanism (HCM), made from paper, plastic, metal, carbon-fiber-reinforced plastic (CFRP) plates, etc., as the force amplifier to increase the functionalities of soft/compliant robots and manipulators. The efforts and contributions in this research include all three aspects of theory, simulation, and applications: 1. New mathematical model and solutions (theory). The assembly and actuation of HCMs include the processes of lateral-torsional buckling, post-buckling morphing, and snap-through bucking, which are highly non-linear. To calculate and estimate the deformation of such mechanisms, a mathematical model based on elastic instability and Euler-Bernoulli beam theory is derived and used for analyses and applications. Corresponding design algorithms for HCM robots are derived based on the theory. 2. Finite-element (FE) simulation and verification. To ensure the accuracy of the theoretical solutions and the correctness of the experiments, FE software is used to replicate the processes of lateral-torsional buckling, post-buckling morphing, snap-through buckling, specific robotic applications, etc. 3. Robotic applications of HCMs. The energy-storing-and-releasing properties of HCMs make them very suitable for increasing the controllability and controllability of soft robots/manipulators. Different from both rigid materials and elastomeric soft materials, HCMs and their major materials were termed “compliant mechanisms/materials.” These materials have moduli comparable to rigid materials but are compliant and deformable thanks to their small out-of-plane bending stiffness. Because of the small deformation assumption used, the mathematical model and solutions built and derived in this work are only a first approximation with qualitative-level correctness. However, they offer an estimation error within 5% compared to the experiments and FE simulation data in the specific problem of the assembly of HCMs involving lateral-torsional buckling and post-buckling responses. To calculate the snap-through buckling, they give an error of ~10% because of the additional assumption of the snapping trajectory used. As for applications, the bistable HCMs are mounted on a soft gripper, a terrestrial galloping runner, and three different soft robotic fish. The motor-driven snapping soft gripper exploits the elastic instability of HCMs to achieve rapid closing within 46ms and reversible operation over a span of 86mm, 2.7 times and 10.9 times better than the reference gripper, respectively. The single-actuated untethered terrestrial soft crawler is capable of jumping off and can gallop at a speed of 313 mm/s or 1.56 body length per second (BL/s), faster than most previous soft crawlers in mm/s and BL/s. The pneumatic HCM fish swim at 26.54 cm/s or 1.40BL/s in a lab-condition aquarium tank, about twice as fast as its reference group. The motor-driven HCM fish has a speed of 2.03 BL/s or 42.6 cm/s, 2-3 times faster than previous untethered soft robotic fish. The newest HCM fish robot uses CFRP as its material, herein referred to as “CarbonFish.” Preliminary evaluations of CarbonFish have evidenced an undulation frequency approaching 10~13 Hz and an operating time of about 40 min, suggesting its potential to outperform other biologically inspired aquatic entities and real fish.

付記する学位プログラム名: 京都大学卓越大学院プログラム「先端光・電子デバイス創成学」 / 京都大学 / 新制・課程博士 / 博士(工学) / 甲第25292号 / 工博第5251号 / 新制||工||1999(附属図書館) / 京都大学大学院工学研究科電気工学専攻 / (主査)教授 松尾 哲司, 教授 萩原 朋道, 教授 阪本 卓也 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

In this paper, we develop a scheme to recover a single erasure when using a Cartesian code,in the context of a distributed storage system. Particularly, we develop a scheme withconsiderations to minimize the associated bandwidth and maximize the associateddimension. The problem of recovering a missing node's data exactly in a distributedstorage system is known as theexact repair problem. Previous research has studied theexact repair problem for Reed-Solomon codes. We focus on Cartesian codes, and show wecan enact the recovery using a linear exact repair scheme framework, similar to the oneoutlined by Guruswami and Wooters in 2017. / Master of Science / Distributed storage systems are systems which store a single data file over multiple storage nodes. Each storage node has a certain storage efficiency, the "space" required to store the information on that node. The value of these systems, is their ability to safely store data for extended periods of time. We want to design distributed storage systems such that if one storage node fails, we can recover it from the data in the remaining nodes. Recovering a node from the data stored in the other nodes requires the nodes to communicate data with each other. Ideally, these systems are designed to minimize the bandwidth, the inter-nodal communication required to recover a lost node, as well as maximize the storage efficiency of each node. A great mathematical framework to build these distributed storage systems on is erasure codes. In this paper, we will specifically develop distributed storage systems that use Cartesian codes. We will show that in the right setting, these systems can have a very similar bandwidth to systems build from Reed-Solomon codes, without much loss in storage efficiency.

Yes / Metamodelling or surrogate modelling techniques are frequently used across the engineering disciplines in conjunction with expensive simulation models or physical experiments. With the proliferation of metamodeling techniques developed to provide enhanced performance for specific problems, and the wide availability of a diverse choice of tools in engineering software packages, the engineering task of selecting a robust metamodeling technique for practical problems is still a challenge. This research introduces a framework for describing the typology of engineering problems, in terms of dimensionality and complexity, and the modelling conditions, reflecting the noisiness of the signals and the affordability of sample sizes, and on this basis presents a systematic evaluation of the performance of frequently used metamodeling techniques. A set of metamodeling techniques, selected based on their reported use for engineering problems (i.e. Polynomial, Radial Basis Function, and Kriging), were systematically evaluated in terms of accuracy and robustness against a carefully assembled set of 18 test functions covering different types of problems, sampling conditions and noise conditions. A set of four real-world engineering case studies covering both computer simulation and physical experiments were also analysed as validation tests for the proposed guidelines. The main conclusions drawn from the study are that Kriging model with Matérn 5/2 correlation function performs consistently well across different problem types with smooth (i.e. not noisy) data, while Kriging model with Matérn 3/2 correlation function provides robust performance under noisy conditions, except for the very high noise conditions, where the Kriging model with nugget appears to provide better models. These results provide engineering practitioners with a guide for the choice of a metamodeling technique for problem types and modelling conditions represented in the study, whereas the evaluation framework and benchmarking problems set will be useful for researchers conducting similar studies.

Cette thèse a pour contexte la combinatoire énumérative et décrit la construction de plusieurs bijections entre modèles combinatoires connus ou nouveaux de suites d'entiers et polynômes, plus particulièrement celle des nombres de Genocchi (et de leurs extensions, les polynômes de Gandhi) qui interviennent dans diverses branches des mathématiques et dont les propriétés combinatoires sont de ce fait activement étudiées, et celles de polynômes q-eulériens associés aux quatre statistiques fondamentales de MacMahon sur les permutations ainsi qu'à des statistiques analogues. On commence par définir les permutations de Dumont normalisées, un modèle combinatoire des nombres de Genocchi médians normalisés q-étendus, notés ¯cn(q) et définis par Han et Zeng, puis l'on construit une première bijection entre ce modèle et l'ensemble des configurations de Dellac, autre interprétation combinatoire de ¯cn(q) mise en évidence par Feigin dans le contexte de la géométrie des grassmanniennes de carquois. En s'appuyant sur la théorie des fractions continues de Flajolet, on en construit finalement un troisième modèle combinatoire à travers les histoires de Dellac, que l'on relie aux premiers modèles sus-cités au moyen d'une seconde bijection. On s'intéresse ensuite à la classe combinatoire des k-formes irréductibles définies par Hivert et Mallet dans l'étude des k-fonctions de Schur, et qui faisaient l'objet d'une conjecture supposant que les polynômes de Gandhi sont générés par les k-formes irréductibles selon la statistique des k-sites libres. On construit une bijection entre les k-formes irréductibles et les pistolets surjectifs de hauteur k − 1 (connus pour générer les polynômes de Gandhi selon la statistique des points fixes) envoyant les k-sites libres des premières sur les points fixes des seconds, démontrant de ce fait la conjecture. Enfin, on établit une nouvelle identité combinatoire entre deux polynômes q-eulériens définis par des statistiques eulériennes et mahoniennes sur l'ensemble des permutations d'un ensemble fini, au moyen d'une dernière bijection sur les permutations, qui envoie une suite finie de statistiques sur une autre / This work is set in the context of enumerative combinatorics and constructs several statistic-preserving bijections between known or new combinatorial models of sequences of integers or polynomials, espacially the sequence of Genocchi numbers (and their extensions, the Gandhi polynomials) which appear in numerous mathematical theories and whose combinatorial properties are consequently intensively studied, and two sequences of q-Eulerian polynomials associated with the four fundamental statistics on permutations studied by MacMahon, and with analog statistics. First of all, we define normalized Dumont permutations, a combinatorial model of the q-extended normalized median Genocchi numbers ¯cn(q) introduced by Han and Zeng, and we build a bijection between the latter model and the set of Dellac configurations, which have been proved by Feigin to generate ¯cn(q) by using the geometry of quiver Grassmannians. Then, in order to answer a question raised by the theory of continued fractions of Flajolet, we define a new combinatorial model of ¯cn(q), the set of Dellac histories, and we relate them with the previous combinatorial models through a second statistic-preserving bijection. Afterwards, we study the set of irreducible k-shapes defined by Hivert and Mallet in the topic of k-Schur functions, which have been conjectured to generate the Gandhi polynomials with respect to the statistic of free ksites. We construct a statistic-preserving bijection between the irreducible k-shapes and the surjective pistols of height k−1 (well-known combinatorial interpretation of the Gandhi polynomials with respect to the fixed points statistic) mapping the free k-sites to the fixed points, thence proving the conjecture. Finally, we prove a new combinatorial identity between two eulerian polynomials defined on the set of permutations thanks to Eulerian and Mahonian statistics, by constructing a bijection on the permutations, which maps a finite sequence of statistics on another

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-08-06T14:53:31Z No. of bitstreams: 1 ALEX RAMOS BORGES - DISSERTAÇÃO PPGMAT 2012..pdf: 550720 bytes, checksum: cd1d40089c6d522f3d44501f683dc900 (MD5) / Made available in DSpace on 2018-08-06T14:53:31Z (GMT). No. of bitstreams: 1 ALEX RAMOS BORGES - DISSERTAÇÃO PPGMAT 2012..pdf: 550720 bytes, checksum: cd1d40089c6d522f3d44501f683dc900 (MD5) Previous issue date: 2012-12 / Neste trabalho serão estudadas as graduações e identidades polinomiais graduadas da álgebra Un(K) das matrizes triangulares superiores n×n sobre um corpo K, o qual será sempre in nito. Primeiramente, será estudado o caso n = 2, para o qual será mostrado que existe apenas uma graduação não trivial e serão descritos as identidades, as codimensões e os cocaracteres graduados. Para o caso n qualquer, serão estudadas as identidades e codimensões graduadas, considerando-se a Zn-graduação natural de Un(K). Finalmente, será apresentada uma classi cação das graduações de Un(K) por um grupo qualquer. / In this work we study the gradings and the graded polynomial identities of the upper n × n triangular matrices algebra Un(K) over a eld K, which is always in nity. The case n = 2 will be rstly studied, for which will be shown that there is only one nontrivial grading and we shall describe the graded identities, codimensions and cocharacters. For the general n case, we shall study graded identities and codimensions, considering the natural Zn-grading of Un(K). Finally, we will present a classi cation of the gradings of Un(K) by any group.

Submitted by Alison Vanceto (alison-vanceto@hotmail.com) on 2016-10-05T14:14:54Z No. of bitstreams: 1 TeseRSV.pdf: 1391601 bytes, checksum: fb3e58d9db6c377161785dede432eeee (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2016-10-05T19:33:46Z (GMT) No. of bitstreams: 1 TeseRSV.pdf: 1391601 bytes, checksum: fb3e58d9db6c377161785dede432eeee (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2016-10-05T19:34:21Z (GMT) No. of bitstreams: 1 TeseRSV.pdf: 1391601 bytes, checksum: fb3e58d9db6c377161785dede432eeee (MD5) / Made available in DSpace on 2016-10-07T18:13:48Z (GMT). No. of bitstreams: 1 TeseRSV.pdf: 1391601 bytes, checksum: fb3e58d9db6c377161785dede432eeee (MD5) Previous issue date: 2015-05-15 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / In this dissertation we made an analytic study of the Bethe Ansatz equations for the XXZ six vertex model with periodic boundary conditions. We had show that the Bethe Ansatz equations deduced from the algebraic and coordinate Bethe Ansatze are related by a conformal map. This allowed us to reduce the Bethe Ansatz equations to a system of polynomial equations. For the one, two and three magnon sectors, we succeeded in decouple these equations, so that the solutions could be expressed in terms of the roots of some self-inversive polynomials, Pa (z). Through new theorems deduced here about the distribution of the roots of self-inversive polynomials in the complex plane, we did a thorough analysis of the distribution of the Bethe roots for the two-magnon sector. This analysis allowed us to show that the Bethe Ansatz is indeed complete for this sector, except at some critical values of the anisotropy parameter A, in which the polynomials Pa (z) may have multiple roots. Finally, an unexpected connection between the Bethe Ansatz equations and the Salem polynomials was found and a new algorithm for search small Salem numbers was elaborated. / Nesta tese fizemos um estudo analítico das equações de Bethe para o modelo de seis vértices XXZ com condições de contorno periódicas. Mostramos que as equações de Bethe deduzidas pelo Ansatz algébrico estão relacionadas com as equações de Bethe do Ansatz de coordenadas por uma transformação conforme. Isso nos permitiu reduzir as equações de Bethe a um sistema de equações polinomiais. Para os setores de um, dois e três mágnons, mostramos que essas equações podem ser desacopladas, de modo que as suas soluções podem ser expressas em termos das raízes de certos polinómios auto-inversivos, Pa(z). Deduzimos aqui novos teoremas acerca da distribuição das raízes dos polinómios auto-inversivos no plano complexo, o que nos permitiu fazer uma análise minuciosa da distribuição das raízes de Bethe para o setor de dois mágnons. Esta análise nos permitiu mostrar que o Ansatz de Bethe é de fato completo para este setor, exceto para alguns valores críticos do parâmetro de anisotropia A, no qual os polinómios Pa(z) podem apresentar raízes múltiplas. Por fim, uma inesperada conexão entre as equações de Bethe e os polinómios de Salem foi encontrada e um novo algoritmo para se procurar por números de Salem pequenos foi elaborado.

The present paper is a study of modied Hermite polynomials of two variables Hn(x; y; a) which for a = e reduces to Hermite polynomials of two variables Hn(x; y) due to M.A. Khan and G.S. Abukhammash. / El presente artculo se estudian polinomios modicados de Hermite de dos variables Hn(x; y; a) que para a = e se reducen a los polinomios de Hermite de dos variables Hn(x; y) introducidos por M.A. Khan y G.S.Abukhammash.