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Publications

2018

Meteorological Meteorological and soil surface effects in gamma radiation time series - Implications for assessment of earthquake precursors

Authors
Barbosa, S; Huisman, JA; Azevedo, EB;

Publication
JOURNAL OF ENVIRONMENTAL RADIOACTIVITY

Abstract
Monitoring of environmental radioactivity for the purpose of earthquake prediction requires the discrimination of anomalies of non-tectonic origin from seismically-induced anomalies. This is a challenging task as time series of environmental radioactivity display a complex temporal pattern reflecting a wide range of different physical processes, including meteorological and surface effects. The present study is based on the detailed time series of gamma radiation from the Eastern North Atlantic (ENA) site in the Azores, and on very high resolution precipitation intensity and soil moisture time series. The results show that an abrupt shift in the average level of the gamma radiation time series previously reported as a potential earthquake precursor can also be explained by a corresponding abrupt change in soil moisture. It was concluded that the reduction of false positive earthquake precursors requires the detailed assessment of both precipitation and soil moisture conditions at high temporal resolution.

2018

EVA a hybrid ROV/AUV for underwater mining operations support

Authors
Martins, A; Almeida, J; Almeida, C; Matias, B; Kapusniak, S; Silva, E;

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

Abstract
This paper presents EVA, a new concept for an hybrid ROV/AUV designed to support the underwater operation of an underwater mining machine, developed in the context of the European H2020 R&D VAMOS Project. This project is briefly presented, introducing the main components and concepts, providing the reader with clear picture of the operational scenario and allowing to understand better the functionality requirements of the support robotic vehicle developed. The design of EVA is detailed presented, addressing the mechanical design, hardware architecture, sensor system and navigation and control. The results of EVA both in water test tank, in the ! VAMOS! Field trials in Lee Moor, UK, and in an harbor scenario are presented and discussed

2018

2nd Workshop on Learning with Imbalanced Domains: Preface

Authors
Torgo, L; Matwin, S; Japkowicz, N; Krawczyk, B; Moniz, N; Branco, P;

Publication
Second International Workshop on Learning with Imbalanced Domains: Theory and Applications, LIDTA@ECML/PKDD 2018, Dublin, Ireland, September 10, 2018

Abstract

2018

Day-ahead stochastic scheduling model considering market transactions in smart grids

Authors
Soares, J; Lezama, F; Canizes, B; Ghazvini, MAF; Vale, Z; Pinto, T;

Publication
20th Power Systems Computation Conference, PSCC 2018

Abstract
The integration of renewable generation and electric vehicles (EVs) into smart grids poses an additional challenge to the stochastic energy resource management problem due to the uncertainty related to weather forecast and EVs user-behavior. Moreover, when electricity markets are considered, market price variations cannot be disregarded. In this paper, a two-stage stochastic programming approach to schedule the day-ahead operation of energy resources in smart grids under uncertainty is presented. A realistic case study is performed using a large-scale scenario with nearly 4 million variables with the goal to minimize expected operation cost of energy aggregators. Three scenarios are analyzed to understand the effect of market transactions and external suppliers on the aggregator model. The results suggest that the market transactions can reduce expected cost, while the external supplier offers risk-free price. In addition, the performance metric shows the superiority of the stochastic approach over an equivalent deterministic model. © 2018 Power Systems Computation Conference.

2018

Table Space Designs For Implicit and Explicit Concurrent Tabled Evaluation

Authors
Areias, M; Rocha, R;

Publication
CoRR

Abstract

2018

Aspect-Driven Mixed-Precision Tuning Targeting GPUs

Authors
Nobre, R; Reis, L; Bispo, J; Carvalho, T; Cardoso, JMP; Cherubin, S; Agosta, G;

Publication
PARMA-DITAM 2018: 9TH WORKSHOP ON PARALLEL PROGRAMMING AND RUNTIME MANAGEMENT TECHNIQUES FOR MANY-CORE ARCHITECTURES AND 7TH WORKSHOP ON DESIGN TOOLS AND ARCHITECTURES FOR MULTICORE EMBEDDED COMPUTING PLATFORMS

Abstract
Writing mixed-precision kernels allows to achieve higher throughput together with outputs whose precision remain within given limits. The recent introduction of native half-precision arithmetic capabilities in several GPUs, such as NVIDIA P100 and AMD Vega 10, contributes to make precision-tuning even more relevant as of late. However, it is not trivial to manually find which variables are to be represented as half-precision instead of single- or double-precision. Although the use of half-precision arithmetic can speed up kernel execution considerably, it can also result in providing non-usable kernel outputs, whenever the wrong variables are declared using the half-precision data-type. In this paper we present an automatic approach for precision tuning. Given an OpenCL kernel with a set of inputs declared by a user (i.e., the person responsible for programming and/or tuning the kernel), our approach is capable of deriving the mixed-precision versions of the kernel that are better improve upon the original with respect to a given metric (e.g., time-to-solution, energy-to-solution). We allow the user to declare and/or select a metric to measure and to filter solutions based on the quality of the output. We implement a proof-of-concept of our approach using an aspect-oriented programming language called LARA. It is capable of generating mixed-precision kernels that result in considerably higher performance when compared with the original single-precision floating-point versions, while generating outputs that can be acceptable in some scenarios.

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