2021
Autores
Martinez, SD; Campos, FA; Villar, J; Rivier, M;
Publicação
INTERNATIONAL JOURNAL OF ELECTRICAL POWER & ENERGY SYSTEMS
Abstract
This paper presents a conjectured-price-response equilibrium approach for modeling both centralized generation (CG) and behind-the-meter distributed generation (BMDG). A Nash game is set up with two constraints linking the CG and BMDG decisions to satisfy both the electricity demand in an energy market and the firm capacity in a capacity market. CG agents maximize their market profits while BMDG customers minimize their net supply costs, making decisions on their annual capacity investments and hourly productions decisions. Customers' costs account for 1) the energy bought from the grid minus the BMDG energy surpluses sold; 2) the payment of the grid access tariff (power and energy-based terms) and 3) the BMDG capacity investments' costs. The equilibrium conditions enable to represent different degrees of oligopoly using conjectural variations in both the energy and capacity markets. This work proves that such an equilibrium problem can be solved through an equivalent, yet simpler-to-solve, quadratic minimization problem. Some case examples compare the results of the proposed joint energy and capacity equilibrium with those from an energy-only equilibrium. Among other conclusions, these cases show that the proposed equilibrium sends adequate economic signals to the consumers to taper off the total system peak demand, whenever the weight of the power-based term of the access tariff is not extremely high.
2021
Autores
Cossa, OF; Sousa, N; Goncalves, R; Martins, J; Branco, F;
Publicação
PROCEEDINGS OF 2021 16TH IBERIAN CONFERENCE ON INFORMATION SYSTEMS AND TECHNOLOGIES (CISTI'2021)
Abstract
In recent years there has been a marked increase in bank fraud by SMS (Short Messaging System) and voice. One of the factors contributing to increase in cases of SMS fraud is the low cost of acquiring large volumes of messages, the reliability (the message will reach the recipient) and the fact that it does not need the Internet to reach the victim. In relation to financial fraud by voice, these can be used to persuade victims to make bank transfers to fraudulent accounts, with the promise of receiving large sums in prizes. The prevention of these types of fraud is not a trivial task, as it requires the application of appropriate techniques and methods depending on their nature. This article presents a Systematic Literature Review (SLR) from 2015 to 2020, with the aim of analyzing the state of the art on bank frauds committed by SMS or voice. The SLR allowed the identification of the most common types of bank fraud by SMS or voice, and the respective detection techniques.
2021
Autores
Pereira, I; Madureira, A; Silva, ECE; Abraham, A;
Publicação
APPLIED SCIENCES-BASEL
Abstract
In real manufacturing environments, scheduling can be defined as the problem of effectively and efficiently assigning tasks to specific resources. Metaheuristics are often used to obtain near-optimal solutions in an efficient way. The parameter tuning of metaheuristics allows flexibility and leads to robust results, but requires careful specifications. The a priori definition of parameter values is complex, depending on the problem instances and resources. This paper implements a novel approach to the automatic specification of metaheuristic parameters, for solving the scheduling problem. This novel approach incorporates two learning techniques, namely, racing and case-based reasoning (CBR), to provide the system with the ability to learn from previous cases. In order to evaluate the contributions of the proposed approach, a computational study was performed, focusing on comparing our results previous published results. All results were validated by analyzing the statistical significance, allowing us to conclude the statistically significant advantage of the use of the novel proposed approach.
2021
Autores
Klimentova, X; Viana, A; Pedroso, JP; Santos, N;
Publicação
OMEGA-INTERNATIONAL JOURNAL OF MANAGEMENT SCIENCE
Abstract
Nowadays there are several countries running independent kidney exchange programmes (KEPs). These programmes allow a patient with kidney failure, having a willing healthy but incompatible donor, to receive a transplant from a similar pair where the donor is compatible with him. Since in general larger patient-donor pools allow for more patients to be matched, this prompts independent programmes (agents) to merge their pools and collaborate in order to increase the overall number of transplants. Such collaboration does however raise a problem: how to assign transplants to agents so that there is a balance between the contribution each agent brings to the merged pool and the benefit it gets from the collaboration. In this paper we propose a new Integer Programming model for multi-agent kidney exchange programmes (mKEPs). It considers the possible existence of multiple optimal solutions in each matching period of a KEP and, in consecutive matching periods, selects the optimal solution among the set of alternative ones in such a way that in the long-term the benefit each agent gets from participating in the mKEP is balanced accordingly to a given criterion. This is done by use of a memory mechanism. Extensive computational tests show the benefit of mKEPs, when compared to independent KEPs, in terms of potential increase in the number of transplants. Furthermore, they show that, under different policies, the number of additional transplants each agent receives can vary significantly. More importantly, results show that the proposed methodology consistently obtains more stable results than methodologies that do not use memory.
2021
Autores
Monteiro, MM; Silva, JDE; Haustein, S; de Sousa, JP;
Publicação
JOURNAL OF TRANSPORT GEOGRAPHY
Abstract
Temporary transnational relocation is a growing type of migration. However, travel behavior adaptation of highly skilled temporary residents and its urban impacts have largely been ignored. This study extends the knowledge of mobility biographies, mobility cultures, and mobility of millennials by examining how temporary residents adapt their intra-urban travel behavior in response to a transnational relocation. The data used here comes from semi-structured interviews with students and researchers of nine different nationalities, aged between 19 and 31 years, temporarily living in Portugal (Lisbon or Porto). We found supporting evidence for the occurrence of residential self-selection, although prior information on study/workplace combined with low knowledge on neighborhood-level make it somewhat specific. Given their shortterm perspective, temporary residents are more prone to rely on public transport and non-motorized modes, having a low likelihood of purchasing vehicles. Thus, measures aimed at improving and facilitating the use of active modes can have an immediate effect on this group's travel behavior and contribute to reaching critical mass for these sustainable alternatives. Temporary residents are also a potentially interesting market segment for public transportation operators for increases in revenues, as they tend to display a relatively higher travel intensity and a wider diversity of activities and destinations. Finally, technology usage was found to reduce the stress-related to traveling to unfamiliar places by increasing the perceived spatial orientation, having the downside of generating a feeling of confidence that decreases the internalization of information. Providing timely and persuasive information at the very beginning of temporary residents' stay can help induce their travel behavior decisions.
2021
Autores
Ruiz Armenteros, AM; Marchamalo Sacrsitan, M; Bakon, M; Lamas Fernandez, F; Delgado, JM; Sanchez Ballesteros, V; Papco, J; Gonzalez Rodrigo, B; Lazecky, M; Perissin, D; Sousa, JJ;
Publicação
INTERNATIONAL CONFERENCE ON ENTERPRISE INFORMATION SYSTEMS / INTERNATIONAL CONFERENCE ON PROJECT MANAGEMENT / INTERNATIONAL CONFERENCE ON HEALTH AND SOCIAL CARE INFORMATION SYSTEMS AND TECHNOLOGIES 2020 (CENTERIS/PROJMAN/HCIST 2020)
Abstract
Deformation monitoring is a common practice in most of dams to ensure their structural health and safety status. Systematic monitoring is frequently carried out by means of geotechnical sensors and geodetic techniques that, although very precise an accurate, can be time-consuming and economically costly. Remote sensing techniques are proved to be very effective in assessing deformation. Changes in the structure, shell or associated infrastructures of dams, including adjacent slopes, can be efficiently recorded by using satellite Synthetic Aperture Radar Inteferometry (InSAR) techniques, in particular, Muti-Temporal InSAR time-series analyses. This is a mature technology nowadays but not very common as a routine procedure for dam monitoring. Today, thanks to the availability of spaceborne satellites with high spatial resolution SAR images and short revisit times, this technology is a powerful cost-effective way to monitor millimeter-level displacements of the dam structure and its surroundings. What is more, the potential of the technique is increased since the Copernicus C-band SAR Sentinel-1 satellites are in orbit, due to the high revisit time of 6 days and the free data availability. ReMoDams is a Spanish research project devoted to provide the deformation monitoring of several embankments dams using advances time-series InSAR techniques. One of these dams is The Arenoso dam, located in the province of Cordova (southern Spain). This dam has been monitored using Sentinel-1 SAR data since the beginning of the mission in 2014. In this paper, we show the processing of 382 SLC SAR images both in ascending and descending tracks until March 2019. The results indicate that the main displacement of the dam in this period is in the vertical direction with a rate in the order of -1 cm/year in the central part of the dam body. (C) 2020 The Authors. Published by Elsevier B.V.
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