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Publications

Publications by CRAS

2010

INTRODUCING NUMERICAL ANALYSIS TOOLS IN ENGINEERING. A SCILAB USER CASE IN ELECTRONICS COURSE

Authors
Campos, D; Dias, N; Dias, A; Ferreira, H;

Publication
3RD INTERNATIONAL CONFERENCE OF EDUCATION, RESEARCH AND INNOVATION (ICERI2010)

Abstract
Software tools in education became popular since the widespread of personal computers. Engineering courses lead the way in this development and these tools became almost a standard. Engineering graduates are familiar with numerical analysis tools but also with simulators (e. g. electronic circuits), computer assisted design tools and others, depending on the degree. One of the main problems with these tools is when and how to start use them so that they can be beneficial to students and not mere substitutes for potentially difficult calculations or design. In this paper a software tool to be used by first year students in electronics/electricity courses is presented. The growing acknowledgement and acceptance of open source software lead to the choice of an open source software tool - Scilab, which is a numerical analysis tool - to develop a toolbox. The toolbox was developed to be used as standalone or integrated in an e-learning platform. The e-learning platform used was Moodle. The first approach was to assess the mathematical skills necessary to solve all the problems related to electronics and electricity courses. Analysing the existing circuit simulators software tools, it is clear that even though they are very helpful by showing the end result they are not so effective in the process of the students studying and self learning since they show results but not intermediate steps which are crucial in problems that involve derivatives or integrals. Also, they are not very effective in obtaining graphical results that could be used to elaborate reports and for an overall better comprehension of the results. The developed tool was based on the numerical analysis software Scilab and is a toolbox that gives their users the opportunity to obtain the end results of a circuit analysis but also the expressions obtained when derivative and integrals calculations, plot signals, obtain vector diagrams, etc. The toolbox runs entirely in the Moodle web platform and provides the same results as the standalone application. The students can use the toolbox through the web platform (in computers where they don't have installation privileges) or in their personal computers by installing both the Scilab software and the toolbox. This approach was designed for first year students from all engineering degrees that have electronics/electricity courses in their curricula.

2010

A Learning Environment for Robotic Production Line Simulation

Authors
Dias, A; Dias, N; Campos, D; Ferreira, H;

Publication
PROCEEDINGS OF THE 9TH EUROPEAN CONFERENCE ON E-LEARNING, VOL 1

Abstract
This paper presents a framework for a robotic production line simulation learning environment using Autonomous Ground Vehicles (AGV). An eLearning platform is used as interface with the simulator. The objective is to introduce students to the production robotics area using a familiar tool, an eLearning platform, and a framework that simulates a production line using AGVs. This framework allows students to learn about robotics but also about several areas of industrial management engineering without requiring an extensive prior knowledge on the robotics area. The robotic production line simulation learning environment simulates a production environment using AGVs to transport materials to and from the production line. The simulator allows students to validate the AGV dynamics and provides information about the whole materials supplying system which includes: supply times, route optimization and inventory management. The students are required to address several topics such as: sensors, actuators, controllers and an high level management and optimization software. This simulator was developed with a known open source tool from robotics community: Player/Stage. This tool was extended with several add-ons so that students can be able to interact with a complex simulation environment. These add-ons include an abstraction communication layer that performs events provided by the database server which is programmed by the students. An eLearning platform is used as interface between the students and the simulator. The students can visualize the effects of their instructions/programming in the simulator that they can access via the eLearning platform. The proposed framework aims to allow students from different backgrounds to fully experience robotics in practice by suppressing the huge gap between theory and practice that exists in robotics. Using an eLearning platform eliminates installation problems that can occur from different computers software distribution and makes the simulator accessible by all students at school and at home.

2010

Clustering Time Series of Sea Levels: Extreme Value Approach

Authors
Scotto, MG; Alonso, AM; Barbosa, SM;

Publication
JOURNAL OF WATERWAY PORT COASTAL AND OCEAN ENGINEERING-ASCE

Abstract
In this paper, long (>40 years) hourly tide gauge records from the North Atlantic are analyzed. A new time series clustering approach which combines Bayesian methodology, extreme value theory, and classification techniques is adopted for the analysis of the regional variability of sea-level extremes. The tide gauge records are clustered on the basis of their corresponding predictive distributions for 25-, 50-, and 100-year return values. The results of the cluster analysis show a clear distinction between the higher latitude stations for which the return values are largest and the remaining locations. This distinction reflects in the U.S. east coast the transition between the Scottian shelf and Gulf of Maine area and the mid-Atlantic Bight area. For the stations at lower latitudes the results show a grouping based on return levels that is not a function of geographical proximity but reflects local effects in extreme sea levels associated with the specific location of each tide gauge.

2010

Multiyear to daily radon variability from continuous monitoring at the Amram tunnel, southern Israel

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

Publication
GEOPHYSICAL JOURNAL INTERNATIONAL

Abstract
Radon is a naturally occurring radioactive noble gas generated within mineral grains of uranium bearing rocks by alpha decay from radium. The Amram tunnel (A. Bloch Geophysical Observatory) is a particularly suitable location for the investigation of radon variability. Located in the arid environment of the Arava desert, near Elat, the 170 m tunnel that constitutes the observatory enables radon monitoring in a desert environment and under fairly stable environmental conditions. The analysis of the temporal variability of continuous measurements of radon and environmental parameters at the Amram tunnel over a period of several years shows a complex temporal pattern characterized by non-stationary and multiscale features. Radon concentrations exhibit multiyear variability in the form of a increasing trend of similar to 1000 Bq m(-3) yr(-1) in the mean and much larger trends up to similar to 2500 Bq m(-3) yr(-1) in the maximum radon levels. Radon concentrations also display strong seasonal patterns, with maxima in summer and minima in winter, ranging from 2.5 kBq m(-3) in winter to 35 kBq m(-3) in summer. Intraseasonal variability is characterized by very large radon anomalies, with sharp increases of more than 20 kBq m(-3) relative to the base level, that occur in spring and summer and last for several days. Daily periodic variability with maxima around midnight appears also in spring and summer, being absent in the cold months. Radon variability at seasonal, intraseasonal and daily timescales is associated with the air temperature outside the tunnel, specifically the temperature gradient between the external environment and the more stable environment inside the tunnel where the measurements are performed.

2010

Recognition of potential areas for the extraction of armourstone in maritime works (NW Portugal): Coupling GIS mapping, geomaterial and geotechnics aspects

Authors
Pires, A; Chaminé, HI; Rocha, F;

Publication
ISRM International Symposium - 6th Asian Rock Mechanics Symposium, ARMS 2010

Abstract
This work introduces the coastal geo-engineering issues for a suitable selection and geomaterial characterisation of quarries. The development of the research had two main phases: (i) the field survey, applied cartography and inspection of maritime structures and (ii) the geological and geotechnical quarry assessment. This study reports results from the second phase which comprises the evaluation of quarries and the identification of potential areas for the extraction of armourstone with quality and availability to supply maritime structures. It was proposed a zoning of the NW Portugal region and taken into account some features like the land use, urban and settlement plans, geological setting, geotechnical and geomechanical description/typification of the rock masses. 459 quarries were identified, georeferenced and distributed in a total area of 14.010km2. More than 200 sites were selected, characterised and included in the GIS database project with interactive support (e.g. hyperlinks for the datasheets, photos or essential information). A total area of 4,1% was calculated, including relevant geological conditions and comprising existent quarries (active/inactive) or new places (suitable or predictable areas). A multidisciplinary perspective must be adopted providing a cost-effective method useful to the incorporation of important concepts (durability and integrity) in geo-monitoring coastal plans and highlighting GIS coastal projects.

2010

Environmental issues in urban groundwater systems: a multidisciplinary study of the Paranhos and Salgueiros spring waters, Porto (NW Portugal)

Authors
Afonso, MJ; Chamine, HI; Marques, JM; Carreira, PM; Guimaraes, L; Guilhermino, L; Gomes, A; Fonseca, PE; Pires, A; Rocha, F;

Publication
ENVIRONMENTAL EARTH SCIENCES

Abstract
This study presents the results of a multidisciplinary approach, using hydrogeochemical, isotopic and ecotoxicological analyses, performed to assess the nature and suitability for use of Paranhos and Salgueiros spring waters (Porto city, NW Portugal). Based on the surface activities located along the course of the springs, 23 water samples were collected. All the samples were analysed for major element concentrations. The isotopic techniques employed included delta(2)H, delta(18)O and (3)H. Standard acute bioassays with Daphnia magna were also performed. The hydrogeochemical analyses showed a nitrate and sulphate-enriched composition for these groundwaters, resulting mainly from urban drainage and sewer leakage. In the ecotoxicological analyses, no significant mortality was observed in any of the tests performed. The results obtained in this study suggest that Porto urban groundwater could be suitable for irrigation uses.

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