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The aim of this study was to assess the applicability of indirect techniques for streamflow and suspended sediment concentration estimation and their use in the calculation of suspended sediment transport rate in the small mountain watersheds of Madeira Island, Portugal. Emphasis was given to the application of salt dilution gauging to the indirect determination of the flow rate and the use of water turbidity data to estimate the concentration of suspended sediments. The field and laboratory work carried out are briefly described, and the main experimental results and the field data from the short measurement campaign performed in the Ribeira Seca stream in Faial, on the north side of the island, are presented and discussed. Whilst the measurement campaign carried out was temporally and spatially limited, it was pioneering for Madeira and allowed to verify the applicability of the indirect hydrometric and sedimentometric techniques used in this exploratory study.

There are many simultaneous iterative methods for approximating complex polynomial zeros, from more traditional numerical algorithms, such as the well-known third order Ehrlich–Aberth method, to the more recent ones. In this paper, we present a new family of combined iterative methods for the simultaneous determination of simple complex zeros of a polynomial, which uses the Ehrlich iteration and a correction based on King's family of iterative methods for nonlinear equations. The use of King's correction allows increasing the convergence order of the basic method from three to six. Some numerical examples are given to illustrate the convergence behaviour and effectiveness of the proposed sixth order Ehrlich-like family of combined iterative methods for the simultaneous approximation of simple complex polynomial zeros.

The purpose of this paper is to present and briefly describe a web-based tool for processing and visualizing in a suitable way the available data from satellite laser altimetry missions, in particular data from ICESat and ICESat-2. This new tool, called ICEComb, allows to access all data contained within each data granule of the datasets of both missions, visualize the data interactively on a geographic map, store data locally, and process and explore data in an efficient, detailed and meaningful way, thus providing an easy-to-use environment for satellite laser altimetry data analysis and interpretation.

Processing, handling and visualising the large data volume produced by satellite altimetry missions is a challenging task. A reference tool for the visualisation of satellite laser altimetry data is the OpenAltimetry platform, a tool that provides altimetry-specific data from the Ice, Cloud, and land Elevation Satellite (ICESat) and ICESat-2 satellite missions through a web-based interactive interface. However, by focusing only on altimetry data, that tool leaves out access to many other equally important information existing in the data products from both missions.The main objective of the work reported here was the development of a new web-based tool, called ICEComb, that offers end users the ability to access all the available data from both satellite missions, visualise and interact with them on a geographic map, store the data records locally, and process and explore data in an efficient, detailed and meaningful way, thus providing an easy-to-use software environment for satellite laser altimetry data analysis and interpretation.The proposed tool is intended to be mainly used by researchers and scientists to aid their work using ICESat and ICESat-2 data, offering users a ready-to-use system to rapidly access the raw collected data in a visually engaging way, without the need to have prior understanding of the format, structure and parameters of the data products. In addition, the architecture of the ICEComb tool was developed with possible future expansion in mind, for which well-documented and standard languages were used in its implementation. This allows, e.g., to extend its applicability to data from other satellite laser altimetry missions and integrate models that can be coupled with ICESat and ICESat-2 data, thus expanding and enriching the context of studies carried out with such data.The use of the ICEComb tool is illustrated and demonstrated by its application to ICESat/GLAS measurements over Lake Mai-Ndombe, a large and shallow freshwater lake located within the Ngiri-Tumba-Maindombe area, one of the largest Ramsar wetlands of international importance, situated in the Cuvette Centrale region of the Congo Basin.Keywords: Laser altimetry, ICESat/GLAS, software tool design, data visualization, Congo Basin.Acknowledgement. This work was partially supported by the Portuguese Foundation for Science and Technology (FCT) through LARSyS − FCT Pluriannual funding 2020−2023.

Nowadays, students learn from the world through a variety of physical and virtual spaces. As one of the priorities of the 21st century is to develop capacities associated with computational thinking and digital literacy, the use of robots in the teaching of programming is becoming more and more usual, since it promotes the development of problem solving, communication and teamwork skills. The purpose of this paper is to analyse and discuss the concept of participation in a virtual community created for the learning of programming with robots. Based on the situated learning theory and the underlying concepts of communities of practice, as well as the effects of technology thereon, we seek a better understanding of learning in these virtual spaces.

Submitted by António Freitas (amsf@uma.pt) on 2021-10-21T07:56:02Z No. of bitstreams: 1 Envisat radar altimetry measurements of water level in a semi-arid river with complex morphology.pdf: 1495508 bytes, checksum: 9f5def8b189dadef8ffec3be918b424e (MD5) Made available in DSpace on 2021-10-21T07:56:02Z (GMT). No. of bitstreams: 1 Envisat radar altimetry measurements of water level in a semi-arid river with complex morphology.pdf: 1495508 bytes, checksum: 9f5def8b189dadef8ffec3be918b424e (MD5) Previous issue date: 2020 info:eu-repo/semantics/publishedVersion

The dependence between variables plays a central role in multivariate extremes. In this paper, spatial dependence of Madeira Island's rainfall data is addressed within an extreme value copula approach through an analysis of maximum annual data. The impact of altitude, slope orientation, distance between rain gauge stations and distance from the stations to the sea are investigated for two different periods of time. The results obtained highlight the influence of the island's complex topography on the spatial distribution of extreme rainfall in Madeira Island. The authors wish to thank the Portuguese Foundation for Science and Technology (FCT) for the financial support through the PhD grant SFRH/BD/39226/2007, financed by national funds of MCTES. They are also grateful to the Center of Statistics and Applications of the University of Lisbon (CEAUL) for the bibliographical and financial support through the FCT under the projects PEst- OE/MAT/UI0006/2011 and PEst-OE/MAT/UI0006/2014, and to the University of Madeira for the logistic support. The authors wish also to thank the Portuguese Institute for Sea and Atmosphere and namely to Dr. Victor Prior, and the Department of Hydraulics and Energy Technologies of the Madeira Regional Laboratory of Civil Engineering and namely to Dr. Carlos Magro, for providing the rainfall data used in this study. The second author also thanks the Brazilian agency CAPES for the partial financial support during his sabbatical leave info:eu-repo/semantics/publishedVersion

In the past and nowadays, hydrology is one of the most natural fields of application for the theory of extremes. This work presents an application of univariate extreme value theory to the study of precipitation in Madeira Island. The method for testing extreme value conditions investigated by Dietrich et al. (Extremes 5:71–85, 2002) was applied to the monthly 1-day maxima precipitation data for the rainy season from seven pluviometric stations maintained by the Portuguese Meteorological Institute. The statistical procedures for the problem of statistical choice of extreme domains of attraction analysed by Neves and Fraga Alves (TEST 16:297–313, 2007) were also applied to each station data set. The results of this analysis indicate the possible k upper extremes to be used for each local sample and the sign of each extreme value index γ.