Time-Reversal Symmetry Breaking and Decoherence in Chaotic Dirac Billiards

In this work, we perform a statistical study on Dirac Billiards in the extreme quantum limit (a single open channel on the leads). Our numerical analysis uses a large ensemble of random matrices and demonstrates the preponderant role of dephasing mechanisms in such chaotic billiards. Physical implementations of these billiards range from quantum dots of graphene to topological insulators structures. We show, in particular, that the role of finite crossover fields between the universal symmetries quickly leaves the conductance to the asymptotic limit of unitary ensembles. Furthermore, we show that the dephasing mechanisms strikingly lead Dirac billiards from the extreme quantum regime to the semiclassical Gaussian regime

Characterization of small Brushless motors for unmanned aerial vehicles/ Caracterização de motores Brushless de pequeno porte para veículos aéreos não tripulados

Brushless motors are increasingly present in our lives and to get the best out of them it is important to know their performance. The objective of this work is to create a methodology of experimental characterization of this type of motor. As a methodology, research was done on similar works, it was built a test bench and an acquisition system to obtain the data. The variables measured were: rotation, torque, temperature, current and voltage. In addition to possessing a servo motor that acts like brake prony type to vary the load applied to the system. The results obtained allowed the analysis of the motor performance. It was also possible to design a mathematical model that represents the system, using the information obtained and the equations present in the literature. It was possible to conclude that the bench and the methodology used were valid, and that the ESC (electronic speed controller) is a great efficiency limiter of the motors

Parede celular de levedura em rações para alevinos de Tilápia do Nilo.

Este estudo avaliou a suplementação de diferentes níveis de parede celular de levedura spray dried (0,0%; 0,1%; 0,2% e 0,4%), em rações para alevinos de tilápia do Nilo. Foram utilizados 120 alevinos revertidos sexualmente para macho, com peso médio inicial de 2,48 ± 0,07 g, distribuídos aleatoriamente em 20 aquários circulares com volume de 60 L (seis peixes por aquário), dotados de sistema de recirculação de água com biofiltro e aquecimento controlado. O delineamento experimental foi inteiramente casualizado, com quatro tratamentos e cinco repetições. Não houve diferença significativa para conversão alimentar, taxa de crescimento específico e taxa de eficiência protéica. Para o ganho de peso houve efeito quadrático (p<0,05), com nível ótimo estimado em 0,22% de parede celular. Pode-se concluir que a inclusão de 0,22% de parede celular de levedura proporciona melhores resultados de desempenho produtivo para alevinos de tilápia do Nilo. Termos para indexação: Saccharomyces sp., glucano, manano,bitstream/item/38744/1/BP200847.pdfDocumento on-line

Desempenho produtivo de tilápias-do-nilo alimentadas com rações contendo parte aérea de mandioca.

bitstream/item/53729/1/BP201159.pd

Classification of areas using pixel-by-pixel and sample classifiers

There are no author-identified significant results in this report

The two-echelon capacitated vehicle routing problem: models and math-based heuristics

Multiechelon distribution systems are quite common in supply-chain and logistics. They are used by public administrations in their transportation and traffic planning strategies, as well as by companies, to model own distribution systems. In the literature, most of the studies address issues relating to the movement of flows throughout the system from their origins to their final destinations. Another recent trend is to focus on the management of the vehicle fleets required to provide transportation among different echelons. The aim of this paper is twofold. First, it introduces the family of two-echelon vehicle routing problems (VRPs), a term that broadly covers such settings, where the delivery from one or more depots to customers is managed by routing and consolidating freight through intermediate depots. Second, it considers in detail the basic version of two-echelon VRPs, the two-echelon capacitated VRP, which is an extension of the classical VRP in which the delivery is compulsorily delivered through intermediate depots, named satellites. A mathematical model for two-echelon capacitated VRP, some valid inequalities, and two math-heuristics based on the model are presented. Computational results of up to 50 customers and four satellites show the effectiveness of the methods developed

Group Theory analysis of phonons in two-dimensional Transition Metal Dichalcogenides

Transition metal dichalcogenides (TMDCs) have emerged as a new two dimensional materials field since the monolayer and few-layer limits show different properties when compared to each other and to their respective bulk materials. For example, in some cases when the bulk material is exfoliated down to a monolayer, an indirect-to-direct band gap in the visible range is observed. The number of layers $N$ ($N$ even or odd) drives changes in space group symmetry that are reflected in the optical properties. The understanding of the space group symmetry as a function of the number of layers is therefore important for the correct interpretation of the experimental data. Here we present a thorough group theory study of the symmetry aspects relevant to optical and spectroscopic analysis, for the most common polytypes of TMDCs, i.e. $2Ha$, $2Hc$ and $1T$, as a function of the number of layers. Real space symmetries, the group of the wave vectors, the relevance of inversion symmetry, irreducible representations of the vibrational modes, optical selection rules and Raman tensors are discussed.Comment: 32 pages, 4 figure