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Publications

2019

Paint Your Programs Green: On the Energy Efficiency of Data Structures

Authors
Pereira, R; Couto, M; Cunha, J; Melfe, G; Saraiva, J; Fernandes, JP;

Publication
Composability, Comprehensibility and Correctness of Working Software - 8th Summer School, CEFP 2019, Budapest, Hungary, June 17-21, 2019, Revised Selected Papers

Abstract

2019

THE USE OF SYSTEM DYNAMICS TO EVALUATE PRINT OUTSOURCING SCENARIOS IN A PUBLIC EDUCATIONAL INSTITUTION

Authors
Negrini, F; Simo netto, ED; Rodrigues, GO; de Castro, HCGA;

Publication
SISTEMAS & GESTAO

Abstract
Information and Communication Technologies (ICT) emerge as a strategic tool, indispensable for the survival of any organization. However, excessive use of ICT can lead to drawbacks such as equipment dependency, rapid obsolescence, and rising maintenance costs. Inefficient use of ICT can result in higher costs for organizations, which may cause them to lose important competitive advantages. In this context, outsourcing printing may be an alternative for institutions to reduce their costs and become more competitive. The aim of this paper is to evaluate scenarios about the financial viability of printing outsourcing in a Federal Higher Education Institution (Instituicoo Federal de Ensino Superior - IFES). To this end, an exploratory research was conducted, with a quantitative approach, using computational modeling, and using the System Dynamics methodology, with simulation and evaluation of three different scenarios: current scenario, likely scenario, unlikely scenario. The results obtained indicate that the unlikely scenario (100% of leased printers) resulted in lower printing costs over the period of the experiment, totaling R$ 637,828.00; the probable scenario (50% of leased printers) totaled R$ 1,000,480.00; while the current scenario (20% of leased printers) resulted in costs of R$ 1,603,060. With the simulations, it was found that printer leasing (outsourcing printing) is the best financial alternative for IFES, which served as a reference for the study, resulting in lower printing costs compared to printer acquisition. The use of systems modeling to evaluate scenarios has been used to support managers in the decision making involving ICT; however, there were no studies in the literature focused on the financial viability simulation of printer outsourcing. Thus, this work sought to bridge this gap by developing and validating a simulation model that can be applied in different scenarios and types of organizations, and work as a reference for future studies.

2019

NU Ori: a hierarchical triple system with a strongly magnetic B-type star

Authors
Shultz, M; Le Bouquin, JB; Rivinius, T; Wade, GA; Kochukhov, O; Alecian, E; Petit, V; Pfuhl, O; Karl, M; Gao, F; Grellmann, R; Lin, CC; Garcia, P; Lacour, S;

Publication
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

Abstract
NU Ori is a massive spectroscopic and visual binary in the Orion Nebula Cluster, with four components: Aa, Ab, B, and C. The B0.5 primary (Aa) is one of the most massive B-type stars reported to host a magnetic field. We report the detection of a spectroscopic contribution from the C component in high-resolution ESPaDOnS spectra, which is also detected in a Very Large Telescope Interferometer data set. Radial velocity (RV) measurements of the inner binary (designated Aab) yield an orbital period of 14.3027(7) d. The orbit of the third component (designated C) was constrained using both RVs and interferometry. We find C to be on a mildly eccentric 476(1) d orbit. Thanks to spectral disentangling of mean line profiles obtained via least-squares deconvolution, we show that the Zeeman Stokes V signature is clearly associated with C, rather than Aa as previously assumed. The physical parameters of the stars were constrained using both orbital and evolutionary models, yielding M-Aa = 14.9 +/- 0.5 M-circle dot, M-Ab = 3.9 +/- 0.7 M-circle dot, and M-C = 7.8 +/- 0.7 M-circle dot. The rotational period obtained from longitudinal magnetic field (B-z) measurements is P-rot = 1.09468(7)d, consistent with previous results. Modelling of (B-z) indicates a surface dipole magnetic field strength of similar to 8 kG. NU Ori C has a magnetic field strength, rotational velocity, and luminosity similar to many other stars exhibiting magnetospheric Ha emission, and we find marginal evidence of emission at the expected level (similar to 1 per cent of the continuum).

2019

Guest Editorial: Demand Side Management and Market Design for Renewable Energy Support and Integration

Authors
Catalao, JPS; Siano, P; Contreras, J; Chicco, G; Erdinc, O; Masoum, M; Aghaei, J; Wang, F; Li, FX; Bakirtzis, A; Parvania, M;

Publication
IET RENEWABLE POWER GENERATION

Abstract

2019

Performance Analysis and Optimization Techniques for Oracle Relational Databases

Authors
Almeida, F; Silva, P; Araujo, F;

Publication
CYBERNETICS AND INFORMATION TECHNOLOGIES

Abstract
Databases provide an efficient way to store, retrieve and analyze data. Oracle relational database is one of the most popular database management systems that is widely used in a different variety of industries and businesses. Therefore, it is important to guarantee that the database access and data manipulation is optimized for reducing database system response time. This paper intends to analyze the performance and the main optimization techniques (Forall, Returning, and Bulk Collect) that can be adopted for Oracle Relational Databases. The results have shown that the adoption of Forall and Bulk Collect approaches bring significant benefits in terms of execution time. Furthermore, the growth rate of the average execution time is lower for Bulk Collect than Forall. However, adoption of Returning approach doesn't bring significant statistical benefits.

2019

State-of-the-art of transmission expansion planning: A survey from restructuring to renewable and distributed electricity markets

Authors
Gomes, PV; Saraiva, JT;

Publication
INTERNATIONAL JOURNAL OF ELECTRICAL POWER & ENERGY SYSTEMS

Abstract
Transmission Expansion Planning (TEP) problem aims at identifying when and where new equipment as transmission lines, cables and transformers should be inserted on the grid. The transmission upgrade capacity is motivated by several factors as meeting the increasing electricity demand, increasing the reliability of the system and providing non-discriminatory access to cheap generation for consumers. However, TEP problems have been changing over the years as the electrical system evolves. In this way, this paper provides a detailed historical analysis of the evolution of the TEP over the years and the prospects for this challenging task. Furthermore, this study presents an outline review of more than 140 recent articles about TEP problems, literature insights and identified gaps as a critical thinking in how new tools and approaches on TEP can contribute for the new era of renewable and distributed electricity markets.

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