1,721,071 research outputs found
Proposal of a phase change material-graphene modified composite with enhanced thermal properties for application in energy storage concrete
No full textPhase change materials (PCMs) are among the most promising candidates for thermal energy storage (TES) applications. However, their low thermal conductivity and slow phase change phenomena are major restricting factors for efficient TES applications. This work investigates a novel thermal energy storage aggregate (TSA) composite based on butyl stearate (BS), a low-cost, commercially available, supported by graphene nanoparticles (GN) as high conductive agents stabilized in the porous media of expanded clay (EC) aggregates. Based on GN's high thermal conductivity, adding 2% GN in the composite shows enhanced heat transfer, while the composite TSA containing 2% GN, compared to plain EC, decreases the maximum temperature peaks up to 5 °C in heating cycles. Furthermore, the leakage test demonstrates that the developed TSA exhibits excellent thermal stability, indicating the potential to maintain its thermal performance even after multiple thermal cycles. Finally, the thermal performance of a TES concrete (TSC) containing TSA with 3.5% PCM-2GN by weight of TSC decreased the peak ambient temperature fluctuations up to 3.5 0C for a test in complete insulation condition. This reduction on TSC surface was between 9 0C to 10.8 0C in 1D heat transfer condition with 0% and 50% humidity, respectively. The novel-designed TSA composites pave the way for a practical and effective solution to enhance internal building comfort and energy efficiency
Effect of Supplementary Reinforcement on the Pull-out of Cast-in-Place Anchors
No full textThe most recent design codes and guidelines for anchors are based on the rather conservative hypothesis that the load-bearing capacity be the greater between the resistance corresponding to concrete-cone breakout and that corresponding to supplementary reinforcement failure, because of either steel yielding or bond collapse. Among the few studies available in the literature on the behavior of anchors placed inside locally-reinforced concrete, a new analytical model was proposed by Sharma, who demonstrated that the local reinforcement contributes to anchor resistance. Within such a framework, some results are presented and commented from an experimental campaign on cast-in place anchors embedded inside concrete blocks heavily reinforced with closed stirrups to prevent concrete-cone breakout: Predictive models are recalled as well
Experimental Investigation on a Beam-Column Joint with Slab and Transverse Beam under Cyclic Loading
No full textThe presence of in-situ cast slabs and transverse beams in reinforced-concrete (RC) beamcolumn joints is usually neglected in RC design practice concerning frames subjected to seismic actions for at least two reasons: (i) the need of simplification in the design process and (ii) the limited experimental studies which are mainly focused on two-dimensional subassemblies. As a part of a research project addressing innovative retrofit solutions based on post-installed fasteners, an external beam-column joint subassembly including a two-way floor slab and a transverse beam is tested (prior to be retrofitted) under a quasi-static cyclic load yielding a 6% drift. The specimen was designed for gravity loads, with limited transverse reinforcement and poor detailing in the joint zone. As expected, the slab and the transverse beam increase the stiffness and the load-carrying capacity of the sub-assembly when the beam flange acts in tension until the joint fails in shear. The effective width of the slab bars, evaluated using strain gauges measurement, is compared with codes’ provisions, showing a good agreement. Compared with preliminary analytical predictions mostly based on two-dimensional models, the load-bearing capacity in shear of the 3D joint assembly is higher. The crack pattern suggests that the increased loadbearing capacity may be primarily attributed to the transverse beam, which increases the joint width and exerts a passive confinement on the joint
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
Lattice Discrete Particle Modeling of MSFRC material
No full textFiber Reinforced Concrete (FRC) is an innovative composite material whose important capabilities are currently investigated both experimentally and numerically. The development of a reliable predictive numerical model requires the careful consideration of concrete heterogeneity and random or oriented arrangement of fibres reinforcement. Among the most validated theories, the Lattice Particle Discrete Model (LDPM) effectively simulates the concrete composite behaviour derived from the interaction of aggregates: the meso-structure of the quasi-brittle material is designed with polyhedral particles reflecting the actual coarse aggregate distribution. The LDPM theory was previously extended to account for the fibers crack-bridging effect, typical of FRCs. In this first step of a larger study, the short-term capabilities of the model are studied before investigating the sustained load response. Experimental results from FRC with 8 kg/m3 of polypropylene (PP) macrofibres are used to calibrate the numerical model, presenting many considerations preliminary the model validation
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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