Cookies
O website necessita de alguns cookies e outros recursos semelhantes para funcionar. Caso o permita, o INESC TEC irá utilizar cookies para recolher dados sobre as suas visitas, contribuindo, assim, para estatísticas agregadas que permitem melhorar o nosso serviço. Ver mais
Aceitar Rejeitar
  • Menu
Publicações

2013

Differentiation between the effect of temperature and pressure on radon within the subsurface geological media

Autores
Zafrir, H; Barbosa, SM; Malik, U;

Publicação
RADIATION MEASUREMENTS

Abstract
Long-term continuous in-situ radon field monitoring was carried out in the southern region of Israel, at the Amram Mountain research tunnel in Elat and in shallow boreholes in the Gevanim valley in Makhtesh Ramon. This work shows that long-term radon monitoring based on simultaneous alpha and gamma measurement enables to differentiate between the impact of ambient temperature and pressure on radon transportation within porous media both in sites isolated from outer meteorological influence as in the Amram tunnel and in sites open to the influence of environmental conditions as in the Gevanim boreholes array. It was found that if the monitoring site is a closed measuring space with undisturbed environmental conditions, the radon in the air space will reach equilibrium with the radon in the rock. Then the radon time series as measured by both gamma and alpha detectors exhibit the same temporal variations. The results in this case indicate that the diurnal, intra-seasonal and seasonal variations in the radon concentration are clearly associated with the ambient temperature gradient outside the rock air interface, 100 m above the tunnel. In shallow, open boreholes, no equilibrium between the radon within the porous media and the radon in the open borehole air is necessarily established and the results of radon monitoring are different. Gamma detectors that measure the changes in radon concentrations in the porous rock indicated a clear correlation between radon concentrations and the daily variations of external surface temperature, from about 1 m up to 85 m. Yet the alpha detectors that measure the changes in radon concentrations in very shallow borehole air (about 1 m) reveal a clear anti-correlation with atmospheric pressure waves at semi-daily, daily, and intra-seasonal time scales. At depths of several tens of meters, outer pressure waves induce anti-correlated radon variations lasting the same time, but destroy the ordered radon daily periodicity in the measuring air space, although almost not disturbing the daily radon variation within the surrounding porous media.

2013

Strategic outsourcing: a lean tool of healthcare supply chain management

Autores
Machado Guimarães, C; Crespo de Carvalho, J;

Publicação
Strategic Outsourcing: An International Journal

Abstract
Considering lean thinking inside and beyond the organisation's boundaries, in the extended supply chain, this paper aims to fill a literature gap clearly stating some outsourcing practices as lean practices and establishing a deployment evolution parallel between both practices. A literature review was carried out collecting cases of lean deployment in healthcare, from both scientific and grey literature. Cases were classified according to lean deployment taxonomy in healthcare settings, showing some differences in lean journey stages in 15 countries. There is an alignment between SCM thinking in healthcare and lean thinking that places a SCM decision as outsourcing as a lean practice serving not only strategic intent but solving operational efficiency. There is a match between different outsourcing drivers (transactional, strategic and transformational) and lean maturity levels. The main constraint to deployment of both lean and outsourcing practices are cultural differences. Understanding lean and outsourcing different deployment maturity levels under the national cultural umbrella can open new perspectives to study lean sustainability factors and better outsourcing relationships in healthcare organisations. This paper presents a merger between the state?of?the art of both lean and outsourcing practices in healthcare settings and suggests an outsourcing and lean evolving pathway. © 2013, Emerald Group Publishing Limited

2013

Investigation of Underwater Acoustic Networking Enabling the Cooperative Operation of Multiple Heterogeneous Vehicles

Autores
Cruz, NA; Ferreira, BM; Kebkal, O; Matos, AC; Petrioli, C; Petroccia, R; Spaccini, D;

Publicação
MARINE TECHNOLOGY SOCIETY JOURNAL

Abstract
In this paper, we investigate the creation of an underwater acoustic network to support marine operations based on static and mobile nodes. Each underwater device combines communication, networking, and sensing capabilities and cooperates with the other devices in coordinated missions. The proposed system is built upon the SUNSET framework, providing acoustic communications and networking capabilities to autonomous underwater vehicles, autonomous surface vessels, and moored systems, using underwater acoustic modems. Specific solutions have been developed and tested to control the underwater nodes acoustically and to instruct the vehicles on keeping a given formation using acoustic links. One of the novelties of our approach has been the development and utilization of a realistic simulation infrastructure to provide a very accurate representation of all the dynamic systems involved in the network, modeling the vehicle dynamics, the acoustic channel, and the communication messages. This infrastructure has been extensively used to investigate and validate the proposed solutions under different environmental conditions before the actual deployment of devices. Several experiments were then conducted in the laboratory and in the field. The experimental results have confirmed the effectiveness of the proposed solutions and the reliability of the proposed simulation framework in estimating system performance.

2013

New theoretical and experimental methods for the design of fiber optic tweezers

Autores
Ribeiro, RSR; Guerreiro, A; Ecoffet, C; Soppera, O; Jorge, PAS;

Publicação
FIFTH EUROPEAN WORKSHOP ON OPTICAL FIBRE SENSORS

Abstract
This paper presents a study of optical forces acting on dielectric particles in media of distinct refractive index. The radiation pressure forces produced by optical tweezers are calculated using the finite difference time domain method as well as the Lorentz force on electric dipoles. The model considers a 2-dimension structure composed of a waveguide and a dielectric microparticle. Furthermore, the paper presents preliminary experimental results concerning the implementation of fiber optical tweezers system based on polymeric lensed fibers.

2013

Differential Evolutionary Particle Swarm Optimization (DEEPSO): a successful hybrid

Autores
Miranda, V; Alves, R;

Publicação
2013 1ST BRICS COUNTRIES CONGRESS ON COMPUTATIONAL INTELLIGENCE AND 11TH BRAZILIAN CONGRESS ON COMPUTATIONAL INTELLIGENCE (BRICS-CCI & CBIC)

Abstract
This paper explores, with numerical case studies, the performance of an optimization algorithm that is a variant of EPSO, the Evolutionary Particle Swarm Optimization method. EPSO is already a hybrid approach that may be seen as a PSO with self-adaptive weights or an Evolutionary Programming approach with a self-adaptive recombination operator. The new hybrid DEEPSO retains the self-adaptive properties of EPSO but borrows the concept of rough gradient from Differential Evolution algorithms. The performance of DEEPSO is compared to a well-performing EPSO algorithm in the optimization of problems of the fixed cost type, showing consistently better results in the cases presented.

2013

Optical inclinometer based on phase-shifted Bragg grating in a taper configuration

Autores
Moura, JPP; Silva, SO; Becker, M; Rothardt, M; Bartelt, H; Frazao, O;

Publicação
FIFTH EUROPEAN WORKSHOP ON OPTICAL FIBRE SENSORS

Abstract
A simple optical inclinometer based on phase-shifted Bragg grating in a taper configuration is proposed. The phase-shifted FBG was fabricated using a DUV femtosecond laser technique in the taper region. The sensing head was characterized for different angle curvatures and also to strain. The angle and strain sensitivities of the inclinometer are 13.15 pm/degree and 8.96 pm/mu epsilon.

  • 3310
  • 4545