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Publications

2013

The Role of the TRS in Precision Agriculture: DGPS with EGNOS and RTK Positioning Using Data from NTRIP Streams

Authors
Osorio, I; Cunha, M;

Publication
REFERENCE FRAMES FOR APPLICATIONS IN GEOSCIENCES

Abstract
For Precise Agriculture purposes, several steps of a maize crop-system were recorded by the use of a GPS receiver with EGNOS and RTK capabilities. The field is about 35 km far from two GNSS CORS, one from RENEP, operated by IGS, and the other from SERVIR, operated by IGEoE. Both networks disseminate real-time GNSS data streams over the Internet using the NTRIP protocol. The GNSS data streams from RENEP reference stations (including validated station coordinates) provide the user with a real-time access to the ETRS89 and, those same streams from IGEoE, a military institution, are in ITRS, allowing large scale scientific applications. The validation of the EGNOS and the RTK solutions, obtained in the two TRS systems, was achieved by the results from post-processed measurements. RTK solutions, when compared to the post-processed values in the same TRS, show sub-decimeter accuracy what is enough for many of the Precision Agriculture studies. However, the two RTK solutions have a translation with a magnitude of the order of 0.5 m that can be explained by the independence of the ETRS89 on the continental drift. Indeed, at the zone where the field is located, while the ETRFyy Cartesian coordinates have velocities less than 1 mm/year, the ITRFyy Cartesian coordinates have velocities greater than 1 cm/year, what give rise to a point position variation with a magnitude of 2.5 cm/year. In order to correlate the tractor velocity, during a pre-emergence herbicide application, to the terrain slope, the field orthometric heights were obtained by the use of GRS80 ondulations, on a 1.5' x 1.5'grid, in the local Portuguese geoid model GeodPT08. The global precision of this model is estimated in 4 cm, which is within the error for the real time solutions obtained.

2013

Power management architecture for smart hip prostheses comprising multiple energy harvesting systems

Authors
Silva, NM; Santos, PM; Ferreira, JAF; Soares dos Santos, MPS; Ramos, A; Simoes, JAO; Reis, MJCS; Morais, R;

Publication
SENSORS AND ACTUATORS A-PHYSICAL

Abstract
Energy harvesting solutions such as instrumented orthopaedic implants are under development to power a wide variety of electronic systems including biomedical implants. Three micro-power generators have already been developed as part of a smart hip prosthesis structure. This paper outlines a power management architecture for efficient harvesting of energy to supply power to modules other than those powered by current instrumented implants. Considering that it is impossible to predict the amount of energy harvested by each particular person, the proposed system also comprises an activation circuit and its ultracapacitor energy reservoir as a fourth type of energy to be used when a continuous energy source is needed. The hip prosthesis prototype has now the capability to energize more power demanding loads, intermittently or continuously, such as radio-frequency modules. The proposed architecture enables operation of a Bluetooth low energy (V4.0) embedded device (BLE112 from Bluegiga), part of a wireless body sensor network, up to 50 s, and a MSP430/eZ430-RF2500 (Texas Instruments), which uses the SimpliciTl communication protocol, up to 110 s, solely using the energy produced by one of the generators.

2013

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

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

Publication
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

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

Publication
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

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

Publication
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

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

Publication
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.

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