Cookies Policy
The website need some cookies and similar means to function. If you permit us, we will use those means to collect data on your visits for aggregated statistics to improve our service. Find out More
Accept Reject
  • Menu
Publications

Publications by CRAS

2018

A note on Nash equilibrium with wave dynamics and boundary control: controllability, observability and stabilizability considerations

Authors
Azevedo Perdicoúlis, TP; Jank, G; dos Santos, PL;

Publication
Int. J. Control

Abstract

2018

The secrets of segway revealed to students: Revisiting the inverted pendulum

Authors
Perdicoúlis, TPA; Dos Santos, PL;

Publication
13th APCA International Conference on Control and Soft Computing, CONTROLO 2018 - Proceedings

Abstract
This article revisits the inverted pendulum-in particular, analyses a simplified model of a Segway, with a view to exploring its capabilities in Control Systems Engineering education. The integration between the theoretic and practical side is achieved through simulation, and in particular by using MathWorks software. We also present a structure for the work to be done in the Laboratory class and propose a solution for the problem. © 2018 IEEE.

2018

Preface

Authors
Silva, MF; Virk, GS; Tokhi, MO; Malheiro, B; Ferreira, P; Guedes, P;

Publication
Human-Centric Robotics- Proceedings of the 20th International Conference on Climbing and Walking Robots and the Support Technologies for Mobile Machines, CLAWAR 2017

Abstract

2018

Developing a Geologically Based VS30 Site-Condition Model for Portugal: Methodology and Assessment of the Performance of Proxies

Authors
Vilanova, SP; Narciso, J; Carvalho, JP; Lopes, I; Quinta Ferreira, M; Pinto, CC; Moura, R; Borges, J; Nemser, ES;

Publication
BULLETIN OF THE SEISMOLOGICAL SOCIETY OF AMERICA

Abstract
The inclusion of site-specific conditions is essential to adequately represent the seismic hazard and the seismic risk for a region. We acquired, gathered, and organized a near-surface shear-wave velocity database for Portugal and applied a three-step methodological approach for developing a V-S30 site-condition map using extrapolation based on surface geology. The methodology includes (1) defining a preliminary set of geologically defined units, (2) calculating the probability distribution of log V-S30 for each unit, and (3) merging the units according to the results of statistical tests. The final model comprises three geologically defined units characterized by log V-S30 distributions that are statistically significantly different from each other: F1, igneous, metamorphic, and old sedimentary rocks; F2, Neogene and Pleistocene formations; and F3, Holocene formations. The site conditions for the F3 unit may be further refined using correlations with topographic slope based on the Shuttle Radar Topography Mission at 3 arcsec resolution (SRTM3) dataset. We analyzed the performance site-condition models based on correlations with exogenous data (topographic slope and surface-geology analogs). The results show that the residual distributions between log V-S30 values measured and estimated from those proxies are strongly biased for some geological units, emphasizing the need for acquiring regional V-S data.

2018

Variação espacial da resistividade elétrica em terraços agrícolas: correlação estatística entre TRE e algoritmos de direção de fluxos = Electrical resistivity spatial variation in agriculture terraces : statistical correlation with ERT and flow direction algorithms

Authors
Fernandes, Joana; Bateira, Carlos; Costa, António; Fonseca, Bruno; Moura, Rui; Goncalves, Jose A;

Publication

Abstract
The construction of terraces, in the Douro Region, with earthen embankments rises aset of problems related to the hydrological processes. The main objective of this study is the evaluation of the electrical resistivity spatial variation in agriculture terraces atDouro valley (Portugal).To achieve this objective two variables are analysed, the soil electrical resistivity andthe flow direction algorithms. In field survey, 13 electrical resistivity profiles wererecorded. The contributing area calculated with the algorithms D (DeterminiscInfinity Flow) and MFD (Multiple Flow Direction), are the base of the internal runoffmodelling, both supported by the digital elevation model with a special resolution of1m2.Was stablished a correlation between the spatial variation of the soil electrical resistivityrepresented by standard deviation electrical resistivity of each profile and the averagevalue of contributing area coincident with each profile.The electrical resistivity standard deviation seems to be moderately good correlated forthe D algorithm at about 1m of depth and has a good correlaon at 1,5m to 2m ofdepth with the MFD algorithm. The results analysis shows a significant positivestatistical correlation between electrical resistivity standard deviation and thecontributing areas (MFD and D) depending on the soil depths.

2018

Energy Harvesting to Increase the Autonomy of Moored Oceanographic Monitoring Stations

Authors
Faria, CL; Goncalves, LM; Martins, MS; Lima, R;

Publication
2018 OCEANS - MTS/IEEE KOBE TECHNO-OCEANS (OTO)

Abstract
device to increase energy autonomy of moored oceanographic monitoring stations. Oscillations and currents through the sea or river are used to produce energy when the whole system is submerged to a depth between 3 to 10 meters. In order to have an inexpensive system, a buoy containing a Linear Electromagnetic Generator (LEG), is fabricated in a 3D printer, using PLA (polylactic acid) filament. Inside of the buoy, one cylinder shaped LEG (98mm length and 25mm of diameter) produces a maximum output power of 20 mW with a 4 Hz movement. To increase power output in larger systems, more LEGs can be added.

  • 76
  • 181