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A Novel Specimen Produced by Additive Manufacturing for Pure Plane Strain Fatigue Crack Growth Studies
Publication . Jesus, Joel de; Borges, Micael; Antunes, Fernando; Ferreira, José; Reis, Luis; Capela, Carlos
Fatigue crack growth is usually studied using C(T) or M(T) specimens with through-thickness cracks. The objective of the present study is to propose a cylindrical specimen with central crack, produced by additive manufacturing. This geometry allows to have pure plane strain state along the whole crack front, avoiding the complexities associated with corner points, crack shape, and variation of crack closure along crack front. Additionally, this geometry may be used to develop studies in vacuum, avoiding expensive vacuum equipment, since the air is not in contact with the crack front. Cylindrical specimens of Ti6Al4V titanium alloy were produced by Selective Laser Melting and tested at a stress ratio R = 0. Marking with overloads was the solution adopted to measure the length of the internal cracks. The fracture surfaces presented circular crack fronts and the da/dN-DK curves showed a great influence of atmosphere on fatigue crack growth. An average difference of 50% was found between the results in air and vacuum. Therefore, this geometry with internal crack is an interesting alternative to through-thickness geometries.
Dental Age Assessment by I2M and I3M: Portuguese Legal Age Thresholds of 12 and 14 Year Olds
Publication . Augusto, Diana; Pereira, Cristiana Palmela; Rodrigues, Ana; Cameriere, Roberto; Salvado, Francisco; Santos, Rui
Objective: Better understanding of dental age assessment may help in cases of age estimation in Forensic Clinics. The first aim was to provide essential information on method reliability for upcoming studies using dental age assessment by second molar index (I2M), and third molar index (I3M) for age estimation on legal ages of 12 - 14 years. The second aim was to document forensic method outcomes of the Demirjian method which has already been used in forensic clinic. Material and methods: Two samples were used for this purpose: for I2M, 633 orthopantomographs (270 females / 363 males), the age range from 7 to 17 years and for I3M, 471 orthopantomographs (253 females / 218 males), the age range from 10 to 23 years, from the database population of Lisbon North University Hospital Center, approved by the Ethic Committee. Results: The I3M cut-off point (1.133) for 12- year-olds obtained better results than the cut-off point stated by the I2M (0.135). Besides, I2M cut-off point (0.001) for 14- year- olds showed better results when compared with the cut-off point (0.705) established by the I3M. Both methods are reliable for the legal age thresholds of 12 and 14 years. However, using I2M and I3M allows us to vary the cut-off value to privilege sensitivities or specificity, depending on which is more appropriate to the intended application. Conclusions: The accuracy (88.94%) of I3M obtained better results for the 12- year- old cut-off point (1.133) and the accuracy (90.21%) of the I2M performed better for the 14- year- old cut-off point (0.001).
Evolving a multi-classifier system with cartesian genetic programming for multi-pitch estimation of polyphonic piano music
Publication . Miragaia, Rolando; Vega, Francisco Fernandez de; Reis, Gustavo
This paper presents a new method for multi-pitch estimation on piano recordings. We propose a framework based on a set of classifiers to analyze the audio input and identify the piano notes present on the given audio signal. Our system's classifiers were evolved using Cartesian Genetic Programming: we take advantage of Cartesian Genetic Programming to evolve a set of mathematical functions that act as independent classifiers for piano notes. Our latest improvements are also presented, including test results using F-measure metrics. Our system architecture is also described to show the feasibility of its parallelization and implementation as a real time system. The proposed approach achieved competitive results, when compared to the state of the art.
Survey and Characterisation of Founder’s Chapel Pathologies of the Santa Maria da Vitoria Monastery, Batalha
Publication . Vazão, Flávio; Gaspar, Florindo; Rodrigues, Hugo
The Monastery of Santa Maria da Vitória, also known as the Monastery of Batalha, is
one of the most beautiful examples of Portuguese and European architecture and has been part of the UNESCO World Heritage list. The construction took over 150 years, across various phases, and composed by several styles namely: gothic, Manuelino and some renaissance details. A number of changes were made to the initial project, resulting in a vast monastic complex that today includes a church, two cloisters with annexed dependencies and two royal pantheons, the Founder’s Chapel and the Unfinished Chapels. The built heritage, under the ambient conditions, even with a proper maintenance can have pathologies and defects due to deterioration of materials, repeated loading lack and exceptional events. Within this process, inspection and diagnosis techniques, play a major role, providing information and allowing the definition of adequate remedial measures. To start this procedure in the Monastery of Santa Maria da Vitória the Founder’s Chapel was selected fora detailed survey and to be subjected to a non-destructive tests, using thermography and ultrasonic testing, preliminary diagnosis with pathology mapping and laser scanning.
Seismic performance of the infill masonry walls and ambient vibration tests after the Ghorka 2015, Nepal earthquake
Publication . Varum, Humberto; Furtado, André; Rodrigues, Hugo; Dias-Oliveira, João; Vila-Pouca, Nelson; Arêde, António
Recent earthquakes have demonstrated a significant contribution of the masonry
infill walls in the structural response of the reinforced concrete (RC) buildings. Field
observations after the 25th April’s earthquake in Nepal reinforce the conclusion regarding the influence of the infill walls increasing significantly the structural stiffness, which has a direct impact on the natural frequencies of the structure and of structural elements. Firstly the manuscript focuses on the performance of the infilled RC structures, describing common Nepalese architectural configurations and the major damages observed in infilled RC buildings. Secondly, it shows results from data collected on ambient vibration tests performed in seven infill panels with different characteristics, such as geometric dimensions, openings and levels of damage. These results are used to study the influence of each parameter in the out-of-plane frequency of the wall panels. The present studies along the manuscript are followed by a presentation of the study cases (buildings and the walls), test setups, main results and conclusions.