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Publications

2019

Optimal bidding strategy for an aggregator of prosumers in energy and secondary reserve markets

Authors
Iria, J; Soares, F; Matos, M;

Publication
APPLIED ENERGY

Abstract
This paper proposes a two-stage stochastic optimization model to support an aggregator of prosumers in the definition of bids for the day-ahead energy and secondary reserve markets. The aggregator optimizes the prosumers' flexibility with the objective of minimizing the net cost of buying and selling energy and secondary reserve in both day-ahead and real-time market stages. The uncertainties of the renewable generation, consumption, outdoor temperature, prosumers' preferences, and house occupancy are modeled through a set of scenarios. For a case study of 1000 prosumers, the results show that the proposed bidding strategy reduces the costs of both aggregator and prosumers by 40% compared to a bidding strategy typically used by retailers.

2019

Low-Cost Interrogation System for Long-Period Fiber Gratings Applied to Remote Sensing

Authors
dos Santos, PSS; Jorge, PAS; de Almeida, JMMM; Coelho, L;

Publication
SENSORS

Abstract
We present a portable and low-cost system for interrogation of long-period fiber gratings (LPFGs) costing around a 30th of the price of a typical setup using an optical spectrum analyzer and a broadband light source. The unit is capable of performing real-time monitoring or as a stand-alone data-logger. The proposed technique uses three thermally modulated fiber-coupled laser diodes, sweeping a few nanometers around their central wavelength. The light signal is then modulated by the LPFG and its intensity is acquired by a single photo-detector. Through curve-fitting algorithms the sensor transmission spectrum is reconstructed. Testing and validation were accomplished by inducing variations in the spectral features of an LPFG through changes either in external air temperature from 22 to 425 degrees C or in refractive index (RI) of the surrounding medium from 1.3000 to 1.4240. A dynamic resolution between 3.5 and 1.9 degrees C was achieved, in temperatures from 125 to 325 degrees C. In RI measurements, maximum wavelength and optical power deviations of 2.75 nm and 2.86 dB, respectively, were obtained in the range from 1530 to 1570 nm. The worse RI resolution obtained was 3.47x10(-3). The interrogation platform was then applied in the detection of iron corrosion, expressing wavelength peak values within 1.12 nm from the real value in the region between 1530 and 1570 nm.

2019

SEGMENTATION OF SENTINEL-2 IMAGES ON SNAP - AN EVALUATION WITH SITEF

Authors
Marcal, ARS;

Publication
2019 IEEE INTERNATIONAL GEOSCIENCE AND REMOTE SENSING SYMPOSIUM (IGARSS 2019)

Abstract
Image segmentation is widely used in image processing, particularly when there is one or few objects of interest. The segmentation of multi-spectral remote sensing images is more challenging due to the large number and diversity of the objects of interest, and the difficulty in having ground truth to tune the segmentation algorithm parameters and to evaluate the results produced. The Synthetic Image TEsting Framework (SITEF) is a tool to address these issues. As the shape and location of the objects in a synthetic image are known, it provides references to be used for quantitative evaluation of the segmentation results. This paper presents SITEF with an experiment to evaluate the segmentation of a SENTINEL-2 image using the software SNAP.

2019

A Pan-cancer Transcriptome Analysis Reveals Pervasive Regulation through Alternative Promoters

Authors
Demircioglu, D; Cukuroglu, E; Kindermans, M; Nandi, T; Calabrese, C; Fonseca, NA; Kahles, A; Kjong Van Lehmann,; Stegle, O; Brazma, A; Brooks, AN; Ratsch, G; Tan, P; Goke, J;

Publication
CELL

Abstract
Most human protein-coding genes are regulated by multiple, distinct promoters, suggesting that the choice of promoter is as important as its level of transcriptional activity. However, while a global change in transcription is recognized as a defining feature of cancer, the contribution of alternative promoters still remains largely unexplored. Here, we infer active promoters using RNA-seq data from 18,468 cancer and normal samples, demonstrating that alternative promoters are a major contributor to context-specific regulation of transcription. We find that promoters are deregulated across tissues, cancer types, and patients, affecting known cancer genes and novel candidates. For genes with independently regulated promoters, we demonstrate that promoter activity provides a more accurate predictor of patient survival than gene expression. Our study suggests that a dynamic landscape of active promoters shapes the cancer transcriptome, opening new diagnostic avenues and opportunities to further explore the interplay of regulatory mechanisms with transcriptional aberrations in cancer.

2019

An Adequate While-Language for Hybrid Computation

Authors
Goncharov, S; Neves, R;

Publication
PROCEEDINGS OF THE 21ST INTERNATIONAL SYMPOSIUM ON PRINCIPLES AND PRACTICE OF DECLARATIVE PROGRAMMING (PPDP 2019)

Abstract
Hybrid computation harbours discrete and continuous dynamics in the form of an entangled mixture, inherently present in various natural phenomena and in applications ranging from control theory to microbiology. The emergent behaviours bear signs of both computational and physical processes, and thus present difficulties not only in their analysis, but also in describing them adequately in a structural, well-founded way. In order to tackle these issues and, more generally, to investigate hybridness as a dedicated computational phenomenon, we introduce a while-language for hybrid computation inspired by the fine-grain call-by-value paradigm. We equip it with operational and computationally adequate denotational semantics. The latter crucially relies on a hybrid monad supporting an (Elgot) iteration operator that we developed elsewhere. As an intermediate step, we introduce a more lightweight duration semantics furnished with analogous results and based on a new duration monad that we introduce as a lightweight counterpart to the hybrid monad.

2019

Decision Support for Small Players Negotiations Under a Transactive Energy Framework

Authors
Pinto, T; Faia, R; Ghazvini, MAF; Soares, J; Corchado, JM; Vale, Z;

Publication
IEEE TRANSACTIONS ON POWER SYSTEMS

Abstract
This paper proposes a decision support model to optimize small players' negotiations in multiple alternative/complementary market opportunities. The proposed model endows players with the ability to maximize their gains in electricity market negotiations. The proposed approach is integrated in a multi-agent simulation platform, which enables experimenting different market configurations, thus facilitating the assessment of the impact of negotiation outcomes in distinct electricity markets. The proposed model is directed to supporting the actions of small players in a transactive energy environment. Therefore, the experimental findings include negotiations in local markets, negotiations through bilateral contracts, and the participation in wholesale markets (through aggregators). The validation is performed using real data from the Iberian market, and results show that by planning market actions considering the expected prices in different market opportunities, small players are able to improve their benefits from market negotiations.

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