3,923 research outputs found
The role of asymptotic functions in network optimization and feasibility studies
Solutions to network optimization problems have greatly benefited from
developments in nonlinear analysis, and, in particular, from developments in
convex optimization. A key concept that has made convex and nonconvex analysis
an important tool in science and engineering is the notion of asymptotic
function, which is often hidden in many influential studies on nonlinear
analysis and related fields. Therefore, we can also expect that asymptotic
functions are deeply connected to many results in the wireless domain, even
though they are rarely mentioned in the wireless literature. In this study, we
show connections of this type. By doing so, we explain many properties of
centralized and distributed solutions to wireless resource allocation problems
within a unified framework, and we also generalize and unify existing
approaches to feasibility analysis of network designs. In particular, we show
sufficient and necessary conditions for mappings widely used in wireless
communication problems (more precisely, the class of standard interference
mappings) to have a fixed point. Furthermore, we derive fundamental bounds on
the utility and the energy efficiency that can be achieved by solving a large
family of max-min utility optimization problems in wireless networks.Comment: GlobalSIP 2017 (to appear
Bifurcations and Averages in the Homoclinic Chaos of a Laser with a Saturable Absorber
The dynamical bifurcations of a laser with a saturable absorber were
calculated, with the 3-2 level model, as function of the gain parameter. The
average power of the laser is shown to have specific behavior at bifurcations.
The succession of periodic-chaotic windows, known to occur in the homoclinic
chaos, was studied numerically. A critical exponent of 1/2 is found on the
tangent bifurcations from chaotic into periodic pulsations.Comment: 6 or 7 pages, 3 figures, publishe
Subwavelength position sensing using nonlinear feedback and wave chaos
We demonstrate a position-sensing technique that relies on the inherent
sensitivity of chaos, where we illuminate a subwavelength object with a complex
structured radio-frequency field generated using wave chaos and a nonlinear
feedback loop. We operate the system in a quasi-periodic state and analyze
changes in the frequency content of the scalar voltage signal in the feedback
loop. This allows us to extract the object's position with a one-dimensional
resolution of ~\lambda/10,000 and a two-dimensional resolution of ~\lambda/300,
where \lambda\ is the shortest wavelength of the illuminating source.Comment: 4 pages, 4 figure
Instruções práticas para o cultivo do milho nas várzeas do Amapá.
Preparo do solo; Semeadura; Cultivar; Tratos culturais; Pragas de importância economica; Controle de pragas; Controle de doenças; Rotação de culturas; Colheita; Secagem; Beneficiamento; Armazenamento; Comercialização; Coeficientes tecnicos.bitstream/item/96059/1/CPAF-AP-1990-Cultivo-Milho.pd
Incidência de doenças em linhagens de arroz de terras altas.
Vários fatores podem afetar a lavoura de arroz, entre eles, as doenças sĂŁo motivo de grande preocupação para os produtores, pois diminuem a produtividade e afetam a qualidade de grĂŁos. O clima quente e Ăşmido favorece o aumento da severidade da maioria das enfermidades. Atualmente, as doenças do arroz, estĂŁo sendo manejadas atravĂ©s da associação do controle quĂmico ao uso de cultivares resistentes. A prevalĂŞncia e a severidade das doenças dependem da presença de patĂłgeno virulento, de ambiente favorável Ă incidĂŞncia e da suscetibilidade da cultivar.bitstream/item/97081/1/CPAF-AP-2002-Doencas-arroz.pd
Teste de cultivares de mandioca no Amapá.
A mandioca é uma das principais culturas de subsitência da Amazônia brasileira. É cultivada por pequenos agricultores, constituindo-se em alimento básico da maioria da população, especialmente a de baixa renda...bitstream/item/96766/1/CPAF-AP-2002-Teste-mandioca.pd
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