13,451 research outputs found
Lobby index as a network centrality measure
We study the lobby index (l-index for short) as a local node centrality
measure for complex networks. The l-inde is compared with degree (a local
measure), betweenness and Eigenvector centralities (two global measures) in the
case of biological network (Yeast interaction protein-protein network) and a
linguistic network (Moby Thesaurus II). In both networks, the l-index has poor
correlation with betweenness but correlates with degree and Eigenvector. Being
a local measure, one can take advantage by using the l-index because it carries
more information about its neighbors when compared with degree centrality,
indeed it requires less time to compute when compared with Eigenvector
centrality. Results suggests that l-index produces better results than degree
and Eigenvector measures for ranking purposes, becoming suitable as a tool to
perform this task.Comment: 11 pages, 4 figures. arXiv admin note: substantial text overlap with
arXiv:1005.480
FUNCTIONS, FUNCTIONING AND OPTIMIZED POSITIONING OF PRESSURE CONTROL VALVES IN OIL-HYDRAULIC CIRCUITS
The pressure control valves can perform different functions in the hydraulic systems, such as: establish maximum pressure, reduce pressure in some circuit lines, and establish sequence movements, among other functions. The main operation of these valves consists of providing a balance between pressure and the force load on a spring. Most of these valves can be positioned in many different levels, between totally open and totally closed, depending on the flow and on the pressure differential. The pressure control valves are usually named according to their primary functions, e.g., lock wire valve, sequence valve, safety valve, etc. and, their basic function is limit or to determine the pressure of the hydraulic system for the attainment of a certain function of the equipment in motion. They are also classified by the type of connections, by the size and by the selected pressure band. Instead of relief and security, discharge, counterbalance, sequence, reducing and shock suppressor valves represent the pressure control devices. In this paper, oil-hydraulic circuits are suggested for practical lessons of Hydraulic and Pneumatic Commands where they regulate valves of pressure, by acting in the following situations: limiting the maximum pressure of the system, determining a level of pressure, determining two different levels of pressure, determining at the same time two distinct levels of pressure, unloading the pump. The functions of these devices will be discussed and analyzed as an attempt to improve their position in the circuit
Finite size analysis of a two-dimensional Ising model within a nonextensive approach
In this work we present a thorough analysis of the phase transitions that
occur in a ferromagnetic 2D Ising model, with only nearest-neighbors
interactions, in the framework of the Tsallis nonextensive statistics. We
performed Monte Carlo simulations on square lattices with linear sizes L
ranging from 32 up to 512. The statistical weight of the Metropolis algorithm
was changed according to the nonextensive statistics. Discontinuities in the
m(T) curve are observed for . However, we have verified only one
peak on the energy histograms at the critical temperatures, indicating the
occurrence of continuous phase transitions. For the regime, we
have found continuous phase transitions between the ordered and the disordered
phases, and determined the critical exponents via finite-size scaling. We
verified that the critical exponents , and depend
on the entropic index in the range in the form , and . On the other hand, the critical exponent does not
depend on . This suggests a violation of the scaling relations and and a nonuniversality of the
critical exponents along the ferro-paramagnetic frontier.Comment: accepted for publication in Phys. Rev.
Análise de Envoltória de Dados para alocação de recursos: uma proposta de algoritmo sequencial.
Este trabalho apresenta um modelo sequencial de atribuição de recursos em modelos DEA, inspirado no modelo de votação de Hondt, considerando-se que o excesso de recursos a ser distribuído tem soma constante. Caso fosse de interesse realocal os recursos já existentes, mantendo-se constante o total dos recursos (soma dos recursos constante) poderia ser usado o modelo DEA com Ganhos de Soma Zero - GSZ-DEA, orientado a inputs. O algoritmo sequencial de alocação de recursos em DEA proposto neste artigo é aplicado à distribuição de vagas docentes aos departamentos de ensino do Centro Tecnológico da UFF. O modelo considera o número de professores de cada departamento, o envolvimento com atividades de ensino e pesquisa e a existência de projetos de expansão aprovados
Magnetic fabric of Red Beds from the Conraria Formation, Central Portugal
Poster apresentado ao VIII Congresso Nacional de Geologia, em Braga (9-16 de Julho 2010)O objectivo principal deste estudo consistiu em quantificar o fabric magnético em amostras da
subunidade superior da Formação de Conraria, Grupo de Silves, na região de Coimbra. Foram efectuadas
determinações de anisotropia da susceptibilidade magnética (ASM) em 50 amostras, obtidas em 11 sites,
de forma a caracterizar o seu fabric magnético. O paralelismo geral entre um fabric achatado e a
estratificação poderá indicar uma conjugação entre o arranjo sedimentar primário e outro com origem na
diagénese ou mesmo em componentes de origem tectónica precoce.The main goal of this study was to quantify the magnetic fabric on rock samples of the upper subunit of the
Conraria Formation, Silves Group, in the region of Coimbra. Studies of Anisotropy of Magnetic Susceptibility
(AMS) were carried out on 50 samples from 11 sites in order to characterise the magnetic fabric. The general
parallelism between an oblate fabric and stratification may indicate a combination between the primary
sedimentary arrangement and another one with origin in the diagenesis or even in components of earlier tectonic
origin
Effects of long-term exposure to antimicrobial colistin sulfate (polymyxin E) over mixed cultures of nitrifiers and methanogens.
Processo de reavaliação dos ensaios da Embrapa Agroindústria de Alimentos pelo Inmetro segundo a norma NBR ISO/IEC 17025.
Partida e operação de um reator aeróbio de nitritação parcial para o tratamento de dejetos de suínos com remoção simultânea de COT.
Projeto: 02.07.06.007
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