1,720,961 research outputs found
Application of Shape Memory Alloys in Historical Constructions
No full textA device prototype, based on the superelastic properties of Shape Memory Alloys (SMAs), is proposed to enhance the thermal and seismic behavior of steel tie-rods. First, the thermal behavior of steel tie-rods with and without SMAs is presented based on the results of extensive experimental tests in thermal room. Next, the seismic performances of the proposed SMA system are discussed based on the results of a series of shaking table tests on a 1:4-scale timber roof truss model. In this article, the functioning principles of the proposed SMA-based device prototype are illustrated and the main aspects related to its implementation in practice are discussed in detail. Finally, a recent example of application of the proposed technology to a historic single-aisle church, realized in the 13th century in Brindisi (southern Italy), and equipped with inadequate and deteriorated steel tied rods, is shown
Experimental thermographic investigation for dry finish turning of SAF 2507 steel
No full textThe Oil&Gas Industry widely uses Super-Duplex Stainless Steels (S-DSS) since their combination of high mechanical characteristics and corrosion resistance. Among them, the SAF 2507 is one of the renowned. The challenges associated with the machining of these steels are directly related to the high temperature that influences the tool-life and the quality of the finished products. This phenomenon is induced by the low thermal conductivity which leads to a high concentration of heat. In order to properly understand their thermal behavior, the distribution of the temperature varying the cutting parameters should be investigated. During dry finish turning, the evolution of the temperature can be captured through a thermographic test campaign, for instance following a L18 - 2 · 37-5 fractional factorial design with no replications. The data acquired can be deeply studied with a statistical methodology framework, the relationship between the response of the experiment and the machining parameters can be established, and a surrogate model for predicting the temperature can be built and validated. The results show that, for the SAF 2507 steel, the cutting temperature for dry finishing turning is mostly influenced by the deep of cut, the feed rate and slightly by the cutting speed
SMA-Based Composites for Active Confinement of Masonry Columns
No full textAlthough masonry is an extremely popular material in the building industry, it’s very weak in tension, as compared to its strength in compression. Smart pre-stressing of masonry with shape memory alloy is a promising solution to this limitation. The shape memory effect of SMA (Shape Memory Alloy) materials seems to be an innovative suitable solution for active strengthening of masonry structures.
Strengthening masonry element with SMA wires and FRP (Fiber Reinforced Polymers) is possible in order to obtain permanent confining effect on the structural element even after the SMA activation. If pre-strained SMA wires are heated under constraint, actually, tensile stresses are produced in the wires, causing stress state on the surface of masonry element. Unconfined and passive confined masonry cylinders were tested for compressive strength and the results were compared to those of cylinders confined by SMA and FRP active confinement technique. This solution can improve the compressive strength and ductility of the columns due to the permanent confining effect of the SMA. Differently from others works, in the proposed concepts, the activation of SMA and the cross-linking of the matrix takes place simultaneously in order to achieve a final and durable effect. This work showed the potential of the proposed method to retrofit unreinforced masonry columns using SMA wires and FRP to protect them from earthquakes
Experimental studies by combined NDT of capillary rise monitoring in masonry specimens
No full textIn the case of Cultural Heritage a destructive or partly destructive investigation approach is rightly hindered by high protection measures. Nevertheless, for preservation purposes it is fundamental to deepen
the knowledge about the various types of historic structures and their health state of conservation as well as on evolution of material decay due to environmental factors. The role of non destructive techniques (NDT) for assessment purposes becomes fundamental in these cases but their use is still not sufficiently widespread nor the technique’s limits or possibilities are completely explored.
Radar and infrared thermography are nondestructive investigation techniques becoming more frequently employed in diagnostics. This paper describes an integrated experimental approach based on infrared thermography and radar for the assessment of masonry structures. At a laboratory scale, the focus was placed onto their evaluation capacity to detect construction details and the beginning of material changes/deterioration and evolution with particular regard to moisture and brine capillary transport
Developing Solutions Based on Shape Memory Alloys for Historical Constructions
No full textThe superelastic properties of Shape Memory Alloys (SMAs) can be used to improve the thermal and seismic behavior of steel tie-rods, which are often used in historical constructions. In this paper, a device prototype based on SMAs is presented, whose performances have been assessed through extensive experimental tests in thermal chamber and shaking table tests on reduced-scale testing models. The functioning principles of the device and the main steps for its implementation are first illustrated. The experimental behavior of the device is then examined. Finally, a recent example of application of the proposed technology to a historic single-aisle church, realized in the 13th century in Brindisi (southern Italy), and equipped with inadequate and deteriorated steel tied rods, is shown
Masonry circular columns confined with glass and basalt fibers
No full textThe mechanical behaviour of masonry columns having a circular cross section, confined with glass and basalt FRP systems was studied in this paper. An extended experimental investigation is presented in order to show the results of axial compression tests on circular masonry columns built with natural calcareous blocks that may be commonly found in Italy and all over Europe in historical buildings. Totally twenty masonry columns were built, instrumented and tested. Different fibres were used including glass and basalt (sheets and grids), different strengthening schemes were applied for confinement of the columns, including complete jacketing and discontinuous FRP strips, different bonding agents were employed including epoxy resin and polymer/cement-based mortar. In four GFRP-confined columns the strengthening action was activated by the presence of Shape Memory Alloys (SMA) filaments immersed in the FRP system. This novel technique is also presented in the paper
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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