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Publicações

2019

Multimethod 3D geophysical survey of a monument - The bell tower of Batalha Abbey

Autores
Senos Matias, MJ; Almeida, F; Moura, R; Barraca, N;

Publicação
25th European Meeting of Environmental and Engineering Geophysics, Held at Near Surface Geoscience Conference and Exhibition 2019, NSG 2019

Abstract
Batalha Abbey is a 14th century UNESCO world heritage site that shows signs of decay. During the last years, high resolution geophysical methods have been used to contribute to the knowledge of its construction characteristics and to an informed maintenance and rehabilitation project. Here in it is presented a multimethod high-resolution geophysical investigation of its main tower. A 3D resistivity survey was carried out on the surface around the tower to investigate the ground beneath it. A GPR survey was used on the tower walls surface to investigate its interior. Three frequencies, 250MHz, 500MHz and 800MHz, were used. Finally, a seismic tomography study was done around the tower with both geophones and sources on the tower walls to provide a 3D velocity image of the tower interior. 3D resistivity results give a clear image of the walls foundations and of the ground beneath the tower. GPR 250MHz data provide a complete GPR image across the tower, although of low resolution. Higher resolution GPR results provided clearer information on the constructive elements of the tower. Finally, the seismic tomography results gave, for the first time, a complete image of the tower interior and proved it a compact construction with no voids.

2019

Stochastic Security Constrained Unit Commitment with High Penetration of Wind Farms

Autores
Kia, M; Hosseini, SH; Heidari, A; Lotfi, M; Catalao, JPS; Shafie khah, M; Osorio, G; Santos, SF;

Publicação
2019 IEEE INTERNATIONAL CONFERENCE ON ENVIRONMENT AND ELECTRICAL ENGINEERING AND 2019 IEEE INDUSTRIAL AND COMMERCIAL POWER SYSTEMS EUROPE (EEEIC / I&CPS EUROPE)

Abstract
Secure and reliable operation is one of the main challenges in restructured power systems. Wind energy has been gaining increasing global attention as a clean and economic energy source, despite the operational challenges its intermittency brings. In this study, we present a formulation for electricity and reserve market clearance in the presence of wind farms. Uncertainties associated with generation and line outages are modeled as different system scenarios. The formulation incorporates the cost of different scenarios in a two-stage short-term (24-hours) clearing process, also considering different types of reserve. The model is then linearized in order to be compatible with standard mixed-integer linear programming solvers, aiming at solving the security constrained unit-commitment problem using as few variables and optimization constraints as possible. As shown, this will expedite the solution of the optimization problem. The model is validated by testing it on a case study based on the IEEE RTS1, for which results are presented and discussed.

2019

Steganography for Indoor Location

Autores
Moutinho, J; Freitas, D; Araujo, RE;

Publicação
2019 AES INTERNATIONAL CONFERENCE ON AUDIO FORENSICS

Abstract
This paper presents steganography techniques that were employed to avoid human perception of the added audio signals in an acoustic environment for indoor location purposes. In the context of audio forensics, indoor location can be used in connection with the detection of a crime. The validation of using the acoustic channel for data transmission over an almost imperceptible audio signal enables the possibility of a receiving processing mobile device (such as a smartphone) to localize itself absolutely by receiving and processing such signals from the infrastructure. Some possible applications will be presented demonstrating the utility of this technology. This paper will present the use of almost imperceptible audio signals to successfully transmit hidden information using a spread spectrum data-hiding technique or a music/speech cover signal and the echo hiding technique.

2019

Using a mobile application to support tourist's information and services needs: The case of Cabo Verde Islands

Autores
Adrião, Z; Morais, EP; Cunha, CR;

Publicação
Proceedings of the 33rd International Business Information Management Association Conference, IBIMA 2019: Education Excellence and Innovation Management through Vision 2020

Abstract
Mobile applications are proliferating in all business domains. In the tourism sector, that is information intensive, and a global phenomenon, the development of efficient solutions for deliver information and services for “information-starvingâ€� tourists is a challenge, and opportunity but mostly a necessity of modern competitive touristic destinations. This paper briefly discusses the role that mobile devices applications have in the support of information and services of Cabo Verde visiting tourists and presents the design and development of a prototype application Android-based that enable important information and services for all Cabo Verde tourists that need to know more about Cabo Verde islands and their important information and services, manly related with their culture, gastronomy, events and hospitality services. © 2019 International Business Information Management Association (IBIMA).

2019

Groundwater resources in a Mediterranean mountainous region: environmental impact of road de-icing

Autores
Marques, JE; Marques, JM; Carvalho, A; Carreira, PM; Moura, R; Mansilha, C;

Publicação
SUSTAINABLE WATER RESOURCES MANAGEMENT

Abstract
Water from mountainous regions is a strategic natural resource. In Mediterranean mountainous regions, which, in many cases, correspond to protected areas, high-altitude roads are often the main threat to the sustainability of water resources. In these regions, the regular socioeconomic functioning requires frequent road de-icing operations which normally consist of spreading NaC1 and other chemicals, such as CaCl2, in pavements. The main purpose of this research is to assess the environmental impact of road de-icing on groundwater resources in a Mediterranean mountainous region and to describe it by means of a hydrogeological conceptual model. The research focused in a cross-sectional sector located in Serra da Estrela (Central Portugal), where a hydrogeological inventory was carried out, followed by hydrogeochemical and hydrogeophysical studies. The results clearly identify different hydrogeo-chemical signatures in polluted (Cl-Na facies and higher EC) and unpolluted (HCO3-Na, Cl-Na, and very low EC). The relation of hydrogeochemistry and altitude is complex and depends on both natural processes (namely, water-rock interaction) and anthropic processes (de-icing operations). The hydrogeophysical survey systematically identified the presence of a pollution plume migrating downstream from roads.

2019

3D Surface velocity retrieval of mountain glacier using an offset tracking technique applied to ascending and descending SAR constellation data: a case study of the Yiga Glacier

Autores
Wang, Q; Fan, JH; Zhou, W; Tong, LQ; Guo, ZC; Liu, G; Yuan, WL; Sousa, JJ; Perski, Z;

Publicação
INTERNATIONAL JOURNAL OF DIGITAL EARTH

Abstract
COSMO-SkyMed is a constellation of four X-band high-resolution radar satellites with a minimum revisit period of 12 hours. These satellites can obtain ascending and descending synthetic aperture radar (SAR) images with very similar periods for use in the three-dimensional (3D) inversion of glacier velocities. In this paper, based on ascending and descending COSMO-SkyMed data acquired at nearly the same time, the surface velocity of the Yiga Glacier, located in the Jiali County, Tibet, China, is estimated in four directions using an offset tracking technique during the periods of 16 January to 3 February 2017 and 1 February to 19 February 2017. Through the geometrical relationships between the measurements and the SAR images, the least square method is used to retrieve the 3D components of the glacier surface velocity in the eastward, northward and upward directions. The results show that applying the offset tracking technique to COSMO-SkyMed images can be used to derive the true 3D velocity of a glacier's surface. During the two periods, the Yiga Glacier had a stable velocity, and the maximum surface velocity, 2.4 m/d, was observed in the middle portion of the glacier, which corresponds to the location of the steepest slope.

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