Cookies Policy
The website need some cookies and similar means to function. If you permit us, we will use those means to collect data on your visits for aggregated statistics to improve our service. Find out More
Accept Reject
  • Menu
Publications

2019

Catalytic Cyclization of Propargyl Bromoethers via Electrogenerated Nickel(I) Tetramethylcyclam in Ionic Liquids: Water Effects

Authors
Mendes, JP; Dunach, E; Esperanca, JMSS; Medeiros, MJ; Ribeiro, JF; Silva, MM; Olivero, S;

Publication
JOURNAL OF THE ELECTROCHEMICAL SOCIETY

Abstract
Cyclic voltammetry and controlled-potential electrolysis have been employed to investigate the reductive intramolecular cyclization of propargyl bromoethers derivatives, catalyzed by electrogenerated (1,4,8,11-tetramethyl-1,4,8,11-tetraaza-cyclotetradecane) nickel(I), [Ni(tmc)](+), as the catalyst, in N,N,N-trimethyl-N-(2-hydroxyethyl) ammonium bis(trifluoromethylsulfonyl) imide, [N-1 1 1 2(OH)][NTf2] and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide, [C(2)mim][NTf2] in the absence and in the presence of water. The results show that the reaction leads to the formation of the expected heterocyclic compounds, in moderate to good yields. These compounds are important intermediates in the synthesis of natural products with possible biological activities. (C) 2019 The Electrochemical Society.

2019

Shoreline and Coastal Terrain Mapping

Authors
Pérez-Alberti A.; Pires A.; Chaminé H.I.;

Publication
Encyclopedia of Earth Sciences Series

Abstract

2019

De-Internationalization of SMEs

Authors
Moreira, AC; Freitas da Silva, PM; Mota, J; Gadim, HO;

Publication
Handbook of Research on Corporate Restructuring and Globalization - Advances in Business Strategy and Competitive Advantage

Abstract
Existing literature has devoted high attention to the topic of internationalization. A common assumption is that companies progressively commit to international operations; however, with the increase of competition in international markets, there may be a backwards perspective towards international operations. In this chapter, the topic of de-internationalization is examined, and a case study of a Portuguese SME that de-internationalized conducted. The featured case highlights the drivers and the main challenges of internationalization, as well as the factors and the difficulties in a de-internationalization process. The chapter findings highlight the need to expand the existing research on the topics of de-internationalization and re-internationalization.

2019

Optimal Distribution Network Reconfiguration with Distributed Generation using a Genetic Algorithm

Authors
Peñaloza, J; Yumbla, J; López, J; Padilha-Feltrin, A;

Publication
2019 IEEE PES Innovative Smart Grid Technologies Conference - Latin America (ISGT Latin America)

Abstract

2019

Experimental NFT hydroponics system with lower energy consumption

Authors
Ramos, C; Nobrega, L; Baras, K; Gomes, L;

Publication
Proceedings of the 2019 5th Experiment at International Conference, exp.at 2019

Abstract
Precision agriculture nowadays has great importance as it brings together the knowledge acquired through traditional cultivation techniques with precision and technological automation. One of the inherent techniques of precision agriculture is hydroponics, with plants growing using aqueous solutions and without soil availability. Although NFT (Nutrient Film Technique) systems are already well-developed systems, there is a big difference between home projects and highly automated processes, which in turn require high investment values. Among other things, in this work, the aim was to study and developed algorithms that allow the efficient recirculation of water, allowing electricity savings to be around 40% compared to more traditional systems. © 2019 IEEE.

2019

Harmonics and flicker in an iron and steel industry with AC arc furnaces

Authors
Pérez Donsión, M; Jar Pereira, S; Oliveira, FT;

Publication
Renewable Energy and Power Quality Journal

Abstract
An AC arc furnace is an unbalanced, non-linear and time-varying load, which can cause many power quality problems to the electric network inside the plant and in its electrical vicinity. Although different studies addressing harmonics and flicker analyses on arc furnaces can be found in the bibliography, it is very difficult obtain an exact model that considers all the parameters that influence the process, and therefore it is necessary to obtain actual measurements under different conditions. This paper presents measurement results for harmonic distortion, flicker and unbalance obtained over three different measurement campaigns on an iron and steel industry (SNL), as well as the pertinent conclusions. Measurement campaigns were performed on an AC arc furnace of 83 MW (170 TM) with a 120 MVA transformer connected by a ‘dirty’ 220 kV line (55 km) to the Substation of Carregado, where other feeders supply industrial and domestic consumers. Finally, the dynamic behaviour of an SVC will be analysed and compared to that of a STATCOM by means of simulation studies.

  • 1868
  • 4503