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Publications

2011

300 km-ultralong Raman fiber lasers using a distributed mirror for sensing applications

Authors
Martins, H; Marques, MB; Frazao, O;

Publication
OPTICS EXPRESS

Abstract
Several configurations of ultralong Raman fiber lasers (URFL) based on a distributed mirror combined with Bragg gratings or fiber loop mirrors are studied. Two continuous-wave URFL configurations, with single and cascaded cavities using fiber Bragg gratings as mirrors are explored for a 300 km long fiber. For optical sensing, the cavity length was optimized for 250 km using one of the gratings an intensity sensor. Another URFL configuration based in a fiber loop mirror is also reported. For optical sensing using a 300 km long fiber it is shown that the best choice is a hybrid configuration. The sensitivity of the FBG laser sensor range was from (76 +/- 2) x 10(-6) mu epsilon(-1) (for lower strain) to (9.0 +/- 0.4) x 10 -6 mu epsilon(-1) (for higher strain). (C) 2011 Optical Society of America

2011

Synthesis of orthorhombic rare-earth manganite thin films by a novel chemical solution route

Authors
Romaguera Barcelay, Y; Moreira, JA; Gonzalez Aguilar, G; Almeida, A; Araujo, JP; de la Cruz, JP;

Publication
JOURNAL OF ELECTROCERAMICS

Abstract
A novel and general chemical solution route for processing high-quality transition metal and rare-earth orthorhombic manganite thin films on Pt(111)/Ti/SiO2/Si substrates was reported. The precursor solutions decomposition process of the manganites was studied by TG and DTA techniques, showing the formation of the phase above 650A degrees C in LaMnO3 and 750A degrees C in both EuMnO3 and DyMnO3 thin films. X-ray diffraction and Raman spectroscopic analysis reveal the formation of a pure orthorhombic structure, with a space group Pbnm, in LaMnO3, EuMnO3 and DyMnO3 thin films annealed at temperatures above the TG phase formation temperature observed. Microstructure and grain morphology of the films were analyzed by SEM and AFM techniques, showing a progressive improvement of the films structures with the increase of the annealing temperature. The temperature dependence of the magnetic response of the LaMnO3, EuMnO3 and DyMnO3 thin films show typical transition temperatures, compared with those reported for lanthanum, europium and dysprosium manganite single crystals and ceramics.

2011

Anosov and Circle Diffeomorphisms

Authors
Almeida, JP; Fisher, AM; Pinto, AA; Rand, DA;

Publication
DYNAMICS, GAMES AND SCIENCE I

Abstract
We present an infinite dimensional space of C1+ smooth conjugacy classes of circle diffeomorphisms that are C1+ fixed points of renormalization. We exhibit a one-to-one correspondence between these C1+ fixed points of renormalization and C1+ conjugacy classes of Anosov diffeomorphisms.

2011

A Tourist's Choice Model

Authors
Brida, J; Defesa, MJ; Faias, M; Pinto, AA;

Publication
DYNAMICS, GAMES AND SCIENCE I

Abstract
We present a tourism model where the choice of a resort by a tourist depends not only on the product offered in the resort, but also on the characteristics of the other tourists staying in the resort. In order to explore the effect of the types of the tourists in the allocation of tourists across resorts, we introduce a game theoretical model and describe the relevant Nash equilibria.

2011

Comparison of Brillouin-Raman Comb Fiber Laser in Two Different Configurations

Authors
Martins, H; Marques, MB; Frazao, O;

Publication
LASER PHYSICS

Abstract
The properties of a Brillouin-Raman comb fiber laser are compared for two different configurations: co-propagating and counter-propagating Raman pump. The optical spectrum is compared for changing the Raman pump power and the power or the wavelength of seed laser. A Brillouin-Raman comb with 400 linewidth lasers in a flat-amplitude bandwidth of 32 nm between 1538 and 1570 nm, with an average optical power 20 dB above the nearby frequencies was generated. The lasers in the comb had an OSNR of 20 dB and a wavelength spacing of 0.08 nm. The results for the counter-propagating configuration were observed to have better quality.

2011

Behaviour and integration of service-oriented automation and production devices at the shop-floor

Authors
Mendes, JM; Restivo, F; Colombo, AW; Leitao, P;

Publication
International Journal of Computer Aided Engineering and Technology

Abstract
Automation and manufacturing systems are changing in the direction of cooperative ecosystems with heterogeneous entities. An important feature that should be considered is the vertical integration from the business needs down to the shop-floor where the real action takes place. This paper analyses the integration of shop-floor devices into the IT-enterprise but maintaining also a certain degree of independence in terms of behaviour. Service-oriented paradigm is used as the main backbone due its proven merits in the business levels and recently also in automation and production systems. In the provided example, high-level Petri nets (HLPN) demonstrate a set of useful features, namely the partial behaviour description and analysis and some parameters in the integration. The resulting application leads to an easy integration of autonomous devices in the IT-enterprise, taking especially in account the requirements of the shop-floor level. © 2011 Inderscience Enterprises Ltd.

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