Lyapunov Exponents without Rescaling and Reorthogonalization

We present a new method for the computation of Lyapunov exponents utilizing representations of orthogonal matrices applied to decompositions of M or MM_trans where M is the tangent map. This method uses a minimal set of variables, does not require renormalization or reorthogonalization, can be used to efficiently compute partial Lyapunov spectra, and does not break down when the Lyapunov spectrum is degenerate.Comment: 4 pages, no figures, uses RevTeX plus macro (included). Phys. Rev. Lett. (in press

Classification of the phases of 1D spin chains with commuting Hamiltonians

We consider the class of spin Hamiltonians on a 1D chain with periodic boundary conditions that are (i) translational invariant, (ii) commuting and (iii) scale invariant, where by the latter we mean that the ground state degeneracy is independent of the system size. We correspond a directed graph to a Hamiltonian of this form and show that the structure of its ground space can be read from the cycles of the graph. We show that the ground state degeneracy is the only parameter that distinguishes the phases of these Hamiltonians. Our main tool in this paper is the idea of Bravyi and Vyalyi (2005) in using the representation theory of finite dimensional C^*-algebras to study commuting Hamiltonians.Comment: 8 pages, improved readability, added exampl

Energy Harvesting Wireless Sensor Networks: Delay Analysis Considering Energy Costs of Sensing and Transmission

Energy harvesting (EH) provides a means of greatly enhancing the lifetime of wireless sensor nodes. However, the randomness inherent in the EH process may cause significant delay for performing sensing operation and transmitting the sensed information to the sink. Unlike most existing studies on the delay performance of EH sensor networks, where only the energy consumption of transmission is considered, we consider the energy costs of both sensing and transmission. Specifically, we consider an EH sensor that monitors some status environmental property and adopts a harvest-then-use protocol to perform sensing and transmission. To comprehensively study the delay performance, we consider two complementary metrics and analytically derive their statistics: (i) update age - measuring the time taken from when information is obtained by the sensor to when the sensed information is successfully transmitted to the sink, i.e., how timely the updated information at the sink is, and (ii) update cycle - measuring the time duration between two consecutive successful transmissions, i.e., how frequently the information at the sink is updated. Our results show that the consideration of sensing energy cost leads to an important tradeoff between the two metrics: more frequent updates result in less timely information available at the sink.Comment: submitted for possible journal publicatio

Profissão: Zootecnista.

bitstream/CPAF-RO-2010/14385/1/profissao-zootecnista.pdfDisponível em: . Acesso em: 13 jan. 2009. Artigo também publicado em outros canais: Portal do Agronegócio; Página Rural; Agroredenotícias

Utilização da amiréia na alimentação de ruminantes.

Realizou-se um trabalho de revisão de literatura com o intuito de levantar os motivos pelos quais pode ser vantajoso a produção e utilização da amiréia na alimentação de ruminantes.bitstream/CPAF-RO-2010/13294/1/doc126-amireia-.pd

Conceitos básicos de genética de populações.

Conceitos de genética básica; Moléculas de DNA; Conceitos de genética de populações; População genética ou mendeliana; Freqüência genotípica; Freqüência gênica ou alélica; Teorema de Hardy-Weinberg (1908).bitstream/CPAF-RO-2010/12193/1/doc118-geneticadepopulacoes.pd

Método do quadrado para estimar a capacidade de suporte de pastagens.

Este folder informa sobre como montar o método do quadrado, o qual consiste no corte da forragem presente dentro de uma área conhecida delimitada por moldura de madeira ou metálica (quadro), lançada ao acaso em diferentes pontos da área a ser avaliada.bitstream/CPAF-RO-2010/14332/1/folder-metododoquadrado-pastagens.pdf1 Folder