A multidisciplinary approach to calibrating advanced numerical simulations of masonry arch bridges

This paper proposes a robust multidisciplinary method that combines geomatic procedures (terrestrial laser scanning and reverse engineering), geophysical methods (ground-penetrating radar and multichannel analysis of surface waves), sonic and impact echo tests, and ambient vibration approaches to generate accurate numerical simulations of masonry arch bridges. These methods are complemented by a robust finite element model updating method based on metamodeling global sensitivity analysis and a robust calibration strategy. The results obtained corroborate the feasibility of the proposed methodology with an average relative error in frequencies of 1.21% and an average modal assurance criterion of 0.93

On the use minor and non-destructive methods for the safety evaluation of an historic RC bridge: the Bôco Bridge

The authors would like to express their gratitude to Tezin Nyandak and Gonçalo Escusa for their help during the experimental campaign. The work was also financed by FEDER funds through the Competitiveness Factors Operational Programme - COMPETE and by national funds through FCT – Foundation for Science and Technology within the scope of the project POCI-01-0145-FEDER-007633.Currently in use, the Bôco Reinforced Concrete (RC) Bridge, built in the early of 20th century, is one of the oldest RC bridges in Portugal. Its initial structural system, erected following the Hennebique system, was retrofitted in the 1960s to support heavy traffic, increasing the section of its structural components. However, the low quality of implemented retrofitting solution has promoted the presence of pathological processes, mainly concrete spalling and steel corrosion. In this context, the present paper shows the first results obtained during the second experimental campaign carried out on the bridge. This campaign comprised the use of several minor and non-destructive methods (laser scanning, operational modal analysis, and laboratory material characterization and mechanical tests), with the aim of improving the knowledge of the bridge and create an accurate numerical simulation (by means of Finite Element Model) to evaluate the safety level of this bridge. Results derived from this campaign, show a bridge with high load capacity, verifying the Ultimate Limit State.FCT -Fundação para a Ciência e a Tecnologia(POCI-01-0145-FEDER-007633)info:eu-repo/semantics/publishedVersio

Non-destructive means and methods for structural diagnosis of masonry arch bridges

Within the precepts defended by the International Charter of Kraków, this paper aims at presenting a fully non-destructive multidisciplinary approach able to characterize masonry bridges at three different levels: i) geometrical level; ii) material level and; iii) structural level. To this end, this approach integrates the terrestrial laser scanner, the sonic and impact-echo methods, the ground penetrating radar and the multichannel analysis of surface waves. All these data are combined with reverse engineering procedures, allowing the creation of suitable as-built CAD models for advanced numerical simulations. Then, these numerical models are contrasted and updated through the data provided by the ambient vibration tests. To validate the methodology proposed in this paper, the Roman bridge of Avila was used as study case. This bridge shows a complex mixture of constructive techniques (masonry, cohesive material, Opus Caementicium and reinforced concrete). Thus, the numerical model was considered for performing predictive structural analysis.Junta of Castilla y León | Ref. SA075P1

Relativistic confinement of neutral fermions with a trigonometric tangent potential

The problem of neutral fermions subject to a pseudoscalar potential is investigated. Apart from the solutions for $E=\pm mc^{2}$, the problem is mapped into the Sturm-Liouville equation. The case of a singular trigonometric tangent potential ($\sim \mathrm{tan} \gamma x$) is exactly solved and the complete set of solutions is discussed in some detail. It is revealed that this intrinsically relativistic and true confining potential is able to localize fermions into a region of space arbitrarily small without the menace of particle-antiparticle production.Comment: 12 page

Cardiovascular responses to passive static flexibility exercises are influenced by the stretched muscle mass and the Valsalva maneuver

BACKGROUND: The respiratory pattern is often modified or even blocked during flexibility exercises, but little is known about the cardiovascular response to concomitant stretching and the Valsalva maneuver (VM) in healthy subjects. OBJECTIVES: This study evaluated the heart rate (HR), systolic blood pressure (SBP), and rate-pressure product (RPP) during and after large and small muscle group flexibility exercises performed simultaneously with the VM. METHODS: Asymptomatic volunteers (N = 22) with the following characteristics were recruited: age, 22 ± 3 years; weight, 73 ± 6 kg; height, 175 ± 5 cm; HR at rest, 66 ± 9 BPM; and SBP at rest, 113 ± 10 mmHg. They performed two exercises: four sets of passive static stretching for 30 s of the dorsi-flexion (DF) of the gastrocnemius and the hip flexion (HF) of the ischio-tibialis. The exercises were performed with (V+) or without (V-) the VM in a counterbalanced order. The SBP and HR were measured, and the RPP was calculated before the exercise session, at the end of each set, and during a 30-min post-exercise recovery period. RESULTS: The within-group comparisons showed that only the SBP and RPP increased throughout the sets (p<0.05), but no post-exercise hypotension was detected. The between-group comparisons showed that greater SBP increases were related to the VM and to a larger stretched muscle mass. Differences for a given set were identified for the HR (the HFV+ and HFV- values were higher than the DFV+ and DFV- values by approximately 12 BPM), SBP (the HFV+ value was higher than the DFV+ and DFV- values by approximately 12 to 15 mmHg), and RPP (the HFV+ value was higher than the HFV- value by approximately 2000 mmHGxBPM, and the HFV+ value was higher than the DFV+ and DFV- values by approximately 4000 mmHGxBPM). CONCLUSION: Both the stretched muscle mass and the VM influence acute cardiovascular responses to multiple-set passive stretching exercise sessions

Resolución de inecuaciones variacionales y aplicaciones

En esta comunicación se pretende dar una breve introducción a las inecuaciones variacionales, y exponer las líneas de trabajo que sobre este tema se desarrollan en el Departamento de Ecuaciones Funcionales de la Universidad de Santiago.Asimismo se resumen algunas contribu ciones publicadas o en curso de realización

What makes a task a problem in early childhood education?

This article begins with a theoretical discussion of the characteristics that a task should feature to be regarded as a mathematics problem suitable for pre-primary students. Those considerations are followed by a report of a classroom experience in which three problems involving quotative or partitive division were posed to pre-primary school pupils to determine the presence of otherwise of the respective characteristics. The findings show that the characteristics of pre-primary education problems depend on two factors: mathematical activity that engages pupils and a structure that favours both their understanding of the problem and the application and verification of the solutions

Recensiones [Revista de Historia Económica Año VII Invierno 1989 n. 1 pp. 219-253]

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