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listelement.badge.dso-type Item , Síntese e caracterização estrutural de polímeros de coordenação de Sn(II) com ligantes carboxilatos(Universidade Federal de Minas Gerais, 2025-10-09) Amanda Pereira de SousaSn(II) coordination polymers (CPs) with carboxylate ligands represent a promising class of materials due to the unique combination of structural versatility and the stereochemical influence of the Sn(II) 5s² lone pair. This work aimed to synthesize and characterize new Sn(II) CPs, investigating how different carboxylic acids influence the dimensionality, geometry, and stability of the resulting networks. Hydrothermal routes were employed, using SnSO₄ and four distinct ligands: H₄MHNC, H₂IDC, H₂bpydc-5,5’, and H₂bpydc-6,6’. The materials were characterized by powder X-ray diffraction (PXRD), three-dimensional electron diffraction (3D-ED), Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric/differential scanning calorimetry (TGA/DSC). The results revealed the formation of diverse structures, including one-, two-, and three-dimensional polymers, as well as the occurrence of disphenoidal and unusual penta-coordinated geometries for Sn(II). In some cases, partial oxidation of tin to Sn(IV) was observed, highlighting the challenge of stabilizing this cation under hydrothermal conditions. Thermal analysis indicated significant compound stability up to intermediate temperatures. It can be concluded that the nature and geometry of the ligands were decisive for the formation of the observed topologies and for the stability of the obtained CPs. This work broadens the understanding of Sn(II) coordination chemistry, evidencing both its structural diversity and the synthetic challenges involved, while also pointing to potential applications in catalysis and the development of new functional materials.listelement.badge.dso-type Item , A few Willmore-type inequalities in noncompact spaces(Universidade Federal de Minas Gerais, 2024-05-13) Adam Petzet RudnikIn this work we obtain two Willmore-type inequalities for certain hypersurfaces in complete and noncompact Riemannian manifolds. The first is a sharp geometric inequality for closed hypersurfaces in Riemannian manifolds with asymptotically nonnegative Ricci curvature. The second concerns Riemannian manifolds with nonnegative Bakry-Émery Ricci curvature, whose sharpness is under current development. To accomplish this, we use standard comparison methods derived both from the Riccati and Jacobi equations, whose elements goes back to the work of E. Heintze and H. Karcher, specially in regards to volume growth of geodesic tubes around hypersurfaces. Moreover, these methods have been applied in a recent work by Wang to greatly simplify the proof of the Willmore-type inequality in complete noncompact Riemannian manifolds of nonnegative Ricci curvature, which was first proved by Agostiniani, Fagagnolo and Mazzieri.listelement.badge.dso-type Item , Generic cw-expansive diffeomorphisms and gluing-orbit(Universidade Federal de Minas Gerais, 2025-11-12) José Antonio Cueto UretaNa presente tese estudaremos alguns resultados de expansividade e colagem de órbitas "gluing orbit": um sobre a genericidade de difeomofismos cw-expansivos em superfícies, mostrando que a cw-expansividade genérica não implica Anosov (nem quase-Anosov); outro é a construção de difeomorfimos expansivos longe dos quase-Anosov em uma variedade de dimensão três, utilizando a isotopia dada por Franks e Robinson para encontrar um difeomorfismo quase-Anosov que não é Anosov; e com as técnicas de expansividade, cw-expansividade e sensivilidade mostramos que os conjuntos estáveis e instáveis locais de homeomorfimos com a propriedade gluing orbit contem subconjuntos perfeitos e a não transferência da propriedade gluing orbit a partir do espaço base para o hyperespaço.listelement.badge.dso-type Item , N-Deployment: a service-oriented and intelligent infrastructure deployment strategy for vehicular networks in complex urban environments(Universidade Federal de Minas Gerais, 2025-12-03) Leonardo Alvarenga Lopes SantosEmerging smart-city applications demand vehicular communication infrastructures that are cost-efficient, scalable, and adaptable to diverse service needs within complex urban traffic environments. This work presents N-Deployment, a flexible strategy for deploying fixed vehicular network infrastructure (RSUs) that meets heterogeneous service requirements. The proposed approach identifies minimal deployment configurations that maximize coverage efficiency and support multiple service types over a unified urban network. N-Deployment integrates insights from prior studies, including infrastructure minimization, geometric optimization, budget constraints, service continuity, unsupervised learning techniques such as clustering, and AI-driven mobility pattern analysis. We formulate a multiobjective optimization model to ensure that a specified fraction of the vehicle fleet connects to the infrastructure within a predefined time window, traversing at least N covered cells along their routes. Additionally, the model enables heterogeneous deployments, delivering differentiated services across distinct urban regions according to local demands. GRASP and NSGA-II metaheuristics are employed to address large-scale scenarios. Experimental results using real mobility traces from Cologne, Germany, show that N-Deployment outperforms traditional strategies by achieving higher vehicle coverage with fewer RSUs while supporting multiple service levels. To our knowledge, this is the first unified strategy to simultaneously address service heterogeneity, infrastructure cost, and real-time connectivity in vehicular network deployments.listelement.badge.dso-type Item , Sobre um sistema de fila com chegadas programadas sujeitas a perturbações do tipo Pareto(Universidade Federal de Minas Gerais, 2025-02-26) Javier Eduardo Beltran BautistaWe discuss the results and proofs presented in the article by Araman et al. (On a Single Server Queue Fed by a Scheduled Traffic with Pareto Perturbations), which studies queueing systems with scheduled arrivals affected by perturbations and deterministic service times. In this context, the n-th arrival is scheduled at time n but actually occurs at time n+ξn, where ξn are i.i.d. random variables. The behavior of the single-server system is analyzed under the assumption that the perturbations follow heavy-tailed distributions similar to the Pareto distribution, with finite mean. Despite the heavy tails of the perturbations, the system maintains unit intensity and exhibits light tails, indicating that individual perturbations do not dominate the global behavior of the system. The paper analyzes the queue behavior resulting from a sum of independent Bernoulli random variables. Assuming perturbations with finite mean, the use of these Bernoulli-type variables allows for a decomposition of the scheduled arrival process. This representation facilitates the mathematical characterization of the influence of perturbations and aids in obtaining an approximation for the stationary workload queue, both in the critically loaded case and in the heavy traffic scenario.