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Repositório IC-Online

Institution's Scientific Repository

 

IC-Online, the Institutional Repository of Scientific Information of the Polytechnic of Leiria (IPLeiria), is part of the RCAAP Project (Open Access Scientific Repositories of Portugal). Its main objectives are to organise, preserve and disseminate the scientific production of the Polytechnic of Leiria (IPLeiria), helping to increase the visibility and impact of the institution's scientific publications.

The IC-Online Repository includes various types of digital documents, such as articles from national and international scientific journals, papers from congresses and conferences, master's dissertations and doctoral theses, among others.

Email repositorio@ipleiria.pt

Recent Submissions

Experimental measurement of H3+/H5 + and D3+/D5+ mobilities in their parent gases
Publication . Neves, P.N.B.; Escada, J.; Borges, F.I.G.M.; Távora, L. M. N.; Conde, C.A.N.
The experimental study of the reduced mobility K0 of the molecular ions H3+/H5+ in H 2 and D3+/D5+ in D 2 was carried out using a recently developed technique, that uses a Xe VUV flash lamp and a Gaseous Electron Multiplier (GEM) microstructure with a CsI deposit to produce the molecular ions by electron avalanche ionization. For both gases, the K0 values were obtained at room temperature (295 K) and at pressures from 5 to 50 Torr for uniform reduced electric fields E/N from 4 to 40 Td. The reduced mobility derived from the measurements is an average of the K0 value of the two molecular ions, and for the H 3+ and H5+ ions is 11.1 cm 2V-1s-1 while for D3+ and D5+ it ranges from 8.5 to 7.8 cm2V -1s-1, for pressure from 5 to 50 Torr. A discussion of the obtained results is presented.
2011-10Conference paper Open access Show more
Direct Load Control in the Perspective of an Electricity Retailer – A Multi-Objective Evolutionary Approach
Publication . Gomes, Álvaro; Antunes, Carlos Henggeler; Oliveira, Eunice
The judicious use of end-use electric loads in the framework of demand-side management programs as valuable resources to increase the global efficiency of power systems as far as economical, technical and quality of service aspects are concerned, is a relevant issue in face of the changes underway in the power systems industry. This paper presents the results of a multi-objective optimization model, in the perspective of an electricity retailer, which is aimed at designing load control actions to be applied to groups of electric loads. An evolutionary algorithm is used to compute solutions to this problem.
2011Book part Restricted access Show more
Optimization of a Wood Plastic Composite for Architectural Applications
Publication . Martins, G.; Antunes, F.; Mateus, A.; Malça, C.
The actual demand for sustainable construction has fostered the research of alternative products made of new materials, such as composites based on renewable resources obtained directly from nature or, most importantly in this context, from the wastes of industries thus encouraging the implementation of recycling processes. This study reports the optimization of wood plastic composites (WPC) made of industrial residues of pine sawdust, high density polyethylene (HDPE) and maleic anhydride-grafted-polyethylene (PE-g-MA) as coupling agent. These composites were specifically designed for the production of an innovative shading system to apply in the forefront of buildings, thus requiring an adequate combination of material properties concerning resistance to weather conditions, with mechanical and functional performance of the final products. The composites were optimized to enable their production and the fabrication of the shutter units through sequential extrusion processing. The optimization of the composites started with a thorough characterization of the raw materials and the mixtures were prepared after analysing the effect of the concentration of pine sawdust in the polymeric matrix, with variable amounts of the coupling agent. Torque rheometry was used to determine the most adequate viscosities for extrusion processing. The composites with optimized contents of pine sawdust and additives were characterized using SEM, FTIR, DSC-TGA, tensile testing, measurements of water contact angle and water absorption capacity. This allowed determining the respective microstructure, chemical interactions, thermal stability, mechanical properties, surface wettability and swelling capacity.
2017Journal article Open access Show more
The Effect 0f Warm-up on Tethered Front Crawl Swimming Forces
Publication . Neiva, Henrique; Morouço, Pedro; Silva, António; Marques, Mário; Marinho, Daniel; Morouço, Pedro
This study was conducted to determine the effect of warm-up on high-intensity front crawl tethered swimming and thus to better understand possible variations in the force exerted by the swimmers. Ten male national level swimmers (mean ± SD; age 15.3 ± 0.95 years old, height: 1.73 ± 5.2 m, body mass: 64.3 ± 7.8 kg, Fat mass 8.31 ± 3.1 kg) participated in this study. After a typical competition warm-up, the subjects performed a 30 s tethered swimming all-out effort in front crawl swimming technique. The same test was repeated in the day after but performed without warming up. Capillary blood lactate concentration was assessed before and after the swimming test and the Borg ratings of perceived exertion scale was used. Without a previous warm-up, the mean ± SD values of maximum and mean forces were 299.62 ± 77.56 N and 91.65 ± 14.70 N, respectively. These values were different (p<0.05) from the values obtained with warm-up (351.33 ± 81.85 N and 103.97 ± 19.11 N). Differences were also observed when regarding to the forces relative to body mass. However, the values of lactate net concentrations after the test performed with and without warm-up were not different (6.27 ± 2.36 mmol·l(-1) and 6.18 ± 2.353 mmol·l (-1)) and the same occurs with the values of ratings of perceived exertion (15.90 ± 2.42 and 15.60 ± 2.27). These results suggest an improvement of the maximum and mean force of the swimmer on the tethered swimming due to previous warm-up.
2011-09-01Journal article Open access Show more
Quasistatic and fatigue behavior of an AISI H13 steel obtained by additive manufacturing and conventional method
Publication . Garcias, José F.; Martins, Rui F.; Branco, Ricardo; Marciniak, Zbigniew; Macek, Wojciech; Pereira, Cândida; Santos, Cyril
This work aims to compare the mechanical behavior of an AISI H13 steel obtained by additive manufacturing with that obtained by conventional manufacturing methods. The average values of the ultimate tensile strength (UTS) and ductility obtained for the specimens produced by the conventional method were equal to 658 MPa and 18%, respectively, which compares with 503 MPa and 0.75% registered for the selective laser melting (SLM) specimens. Inversely, the average hardness value determined for the SLM specimens was higher, 450 HV, than the observed for the conventional, 200 HV. In addition, the maximum applied stress corresponding to a fatigue limit's endurance of 2 × 106 cycles was equal to 340 and 85 MPa for conventional and SLM specimens, respectively. Therefore, from a fatigue design point of view, it was possible to infer that σmax/UTS = 0.17 for the SLM specimens tested. Porosity and lack of fusion influenced the static and the fatigue strength negatively in the SLM specimens.
2021-08-19Journal article Open access Show more