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Design, síntese e caracterização de ligas multicomponentes contendo Mg para armazenagem de hidrogênio
(Universidade Federal de São Carlos, 2022-02-14) Ferraz, Mariana de Brito; Zepon, Guilherme; https://lattes.cnpq.br/7924187202036614; https://lattes.cnpq.br/5414167939699652
The use of hydrogen as an alternative fuel has been investigated due to its great potential to be used as an energy vector. One of the challenges for its wide application is to store it safely and efficiently. Therefore, metallic hydrides have been studied as a promising alternative for hydrogen storage in solid state. Moreover, multicomponent (MC) alloys are currently gaining attention because they can increase the possibility of obtaining materials for this application, due to their large compositional field. Recently, it was reported in the literature that some alloys with body centered cubic (BCC) structure present high storage capacity. There are many works dedicated to the study of MCs alloys composed only by transition metals, which ends up limiting the gravimetric capacity, due to the density. Therefore, the use of the element Mg in the composition of these alloys is proposed, since it has low density and good affinity with hydrogen. The present work made use of the parameters ∅, Ω, 𝛿�� (%) and VEC, as a method of composition selection, which resulted in the alloy Mg35Al15Ti25V10Zn15. This alloy was synthesized by mechanical alloy (MA) and reactive milling (RM), structurally characterized and its hydrogen storage properties were analyzed. The alloy produced by MA was composed of a BCC phase, with an amount of unmixed Mg, absorbing about 2.5 %p. of H2 at 375°C and 4 MPa. The alloy produced by RM was composed of a mixture of a face centered cubic (FCC) hydride and MgH2, having a desorption capacity of 2.75 %p. H2. Furthermore, the desorption behavior was analyzed, and it was observed that MgH2 is the first to desorb and the desorption sequence is complete after the decomposition of the FCC and body centered tetragonal (BCT) phases, leading to the formation of the BCC phase.
Categoria de Lusternik-Schnirelmann e aplicações
(Universidade Federal de São Carlos, 2022-02-14) Ferreira, Junio Cesar; Töben, Dirk; https://lattes.cnpq.br/0022267686144981; https://lattes.cnpq.br/6854004362377096
The Lusternik-Schnirelmann category associates a positive integer to each topological space. This number is an important invariant in algebraic topology, critical point theory and symplectic geometry. In this dissertation we present the theory of Lusternik-Schnirelmann category, compute the category of several topological spaces and provide some reformulations of the category. In addition, we show two applications of Lusternik-Schnirelmann category to other areas of mathematics. The first one is a geometric application proving that a convex body in Euclidean space of dimension n admits at least n binormal chords. The second application relates the category to topological complexity in the motion planning problem.
Slice Elasticity Architecture (SEA): definition, implementation and integration
(Universidade Federal de São Carlos, 2022-02-14) Rocha, André Luiz Beltrami; Verdi, Fábio Luciano; https://lattes.cnpq.br/9143186843657940; https://lattes.cnpq.br/6413433791281709
Network slicing initiatives (e.g., Cloud Network Slicing, 5G Network Slicing) are being widely studied by academia and industry as enablers for future networks like 5G and 6G, as well as verticals such as V2X, critical communications, augmented reality, and others. Several challenges arise with this emerging concept, which needs to be solved to further groundbreaking technologies. A significant challenge is slice elasticity, defined as the capacity to grow or shrink slice resources (e.g., computing, networking, or storage). One alternative to solve this challenge is providing a closed control loop (CCL) involving slice monitoring, management, and orchestration. In addition, this CCL may be easily adapted and coupled with most of the slicing initiatives of standardization bodies. In that sense, this thesis proposes, implements, and integrates the Slice Elasticity Architecture (SEA), an architecture to support a new business model called Slicing Elasticity as a Service (SlEaaS). This new business model enables slice resource orchestration across a heterogeneous end- to-end infrastructure that spans multiple administrative and technological domains in a facilitated and automated way for tenants and slice providers. The SEA monitors slice resources periodically, offers the policies/SLAs administration, and performs slice elasticity operations autonomously when the predefined policy is violated to ensure the QoS of the instantiated service. The SEA design is scalable and generic enough to support several technologies transparently. The results demonstrate the SEA functionalities based on scenarios of slice elasticity operations for computing and networking resources.