Encontrados 14 documentos, a visualizar página 1 de 2
Simulation of a Chromatic Dispersion Monitoring Scheme Using an Optical Delay-a...
Vítor Ribeiro; Mário Lima; António Teixeira; Rogério Nogueira; Diana FidalgoA new postdetection method of dispersion is proposed, based on a scheme previously implemented, and that additionally uses a Bit Error Rate (BER) analyser, which allows the extending of the monitoring window. The monitoring method was tested with transmission rates of up to 40 Gbit/s. It showed monitoring windows of at least ± 300 ps / nm, as well as the ability to adapt to different modulation formats, ...
Chromatic dispersion monitoring technique using optical asynchronous sampling a...
Vítor Ribeiro; António Teixeira; Mário LimaWe present the equations that led to the novel nal equation, which relates chromatic dispersion with the power amplitude, measured in a time window. ; We present the equations that led to the novel nal equation, which relates chromatic dispersion with the power amplitude, measured in a time window.
Polarization Mode Dispersion Measurements using Low-Coherence Interferometry
Luís M. N. Amaral; O. Frazão; M. B. Marques; Mário Lima; António TeixeiraAn interferometric setup for measuring Polarization Mode Dispersion (PMD), was tested. It uses a low-coherence technique in a Michelson interferometer to determine the PMD values in two reels, measuring the Differential Group Delay (DGD). The low-coherence source bounds the minimum value of DGD detected to 0,13 ps, leading to a minimum value detected around 0,14 ps. The measured PMD mean value for one reel, in ...
Degradação de fibras ópticas devido à propagação de sinais de elevada intensidade
Ana Maria Rocha; Fátima Domingues; Margarida Facão; António Teixeira; Mário Lima; Rogério Nogueira; Marta Ferreira; Paulo AndréThe propagation of high power signals in optical fibers can lead to the fibre degradation and destruction. In this work we study three forms of degradation resulting from the high optical power propagation: i) increasing of the fiber coating temperature for bending situation; ii) degaradation of optical connectors; and iii) ignition and propagation of the fuse effect that can lead to the destruction of the opti...
Distribution of OFDM radio signals over optical fiber
Paulo Andrade; Mário Lima; António TeixeiraIn this paper, we will study, via simulation, several transmission schemes of OFDM radio signals over optical fiber, in order to evaluate their main advantages and limitations. We will start by studying the transmission of 2 OFDM channels at 8GHz and 60 GHz, considering several types of optical modulation: Double Sideband (DSB), Vestigial Sideband (VSB) and Double Sideband-Carrier Suppressed (DSB-CS). Then, we ...
Coherent Fiber Communications Analyzer
Ricardo M. Ferreira; Ali Shahpari; Mário Lima; António L. TeixeiraThis paper addresses an coherent fiber communication analyzer with digital signal processing (DSP). First we make an overview of the investigations that are being conducted at Instituto de Telecomunicações (IT) in the coherent communications area and then introduce the coherent receiver used in the IT laboratory. We also present an interface developed in GUI of Matlab to analyze coherent signals. ...
PON Upstream traffic coexistence in a Stacked-PON environment
Tiago Mendes; Mário Lima; António TeixeiraA stacked-PON scenario using todays most deployed standards over the same fiber span was proposed and a coexistence upstream traffic scenario was simulated an experimentally evaluated. ; A stacked-PON scenario using todays most deployed standards over the same fiber span was proposed and a coexistence upstream traffic scenario was simulated an experimentally evaluated.
Fabricação de microcanais utilizando o método de xurografia: visualização da ca...
Pinto, Elmano; Pinho, Diana; Bento, David; Correia, Teresa Montenegro; Garcia, Valdemar; Dias, Ricardo P.; Miranda, João Mário; Lima, R.No presente estudo, pretendeu-se desenvolver/melhorar uma metodologia de microfabricação de baixo custo, conhecida por xurografia e efectuar a visualização e quantificação da camada livre de células (CLC) junto às paredes para diferentes escoamentos sanguíneos em microcanais.
Porous titanium scaffolds produced by powder metallurgy for biomedical applicat...
Vasconcellos,Luana Marotta Reis de; Oliveira,Marize Varella de; Graça,Mário Lima de Alencastro; Vasconcellos,Luis Gustavo Oliveira dePorous titanium scaffolds are promising materials for biomedical applications such as prosthetic anchors, fillers and bone reconstruction. This study evaluated the bone/titanium interface of scaffolds with interconnected pores prepared by powder metallurgy, using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Porous scaffolds and dense samples were implanted in the tibia of rabbits...
Metátese de olefinas no Brasil: "Brazil is romping it!"
Matos,José Milton E.; Batista,Nouga C.; Carvalho,Rogério M.; Santana,Sirlane A. A.; Puzzi,Paula N.; Sanches,Mário; Lima-Neto,Benedito S.Some aspects of the olefin metathesis reactions are summarized here (types of reactions, mechanism and catalysts). In particular, the research groups that have been working on this chemistry in Brazil are presented. The main goal of this paper is to make this type of reaction more widely known in the Brazilian chemical community.
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