Search results for "1105"
showing 10 items of 459 documents
Enriching standards-based digital thread by fusing as-designed and as-inspected data using knowledge graphs
2020
Abstract Realizing the digital thread is essential for linking and orchestrating data across the product lifecycle in smart manufacturing. Linking heterogeneous lifecycle data is critical to maintain associativity and traceability in a digital thread. Recently, researchers have successfully leveraged ontology models with knowledge graphs in engineering domains for threading different lifecycle data. One of the most successful of such efforts is OntoSTEP which enables the formal capture of information embedded in the STandard for Exchange of Product model data (STEP) data representation, or ISO 10303. Meanwhile, an emerging inspection standard, called the Quality Information Framework (QIF),…
Transformation of Construction Cement to a Self-Healing Hybrid Binder
2019
A new biomimetic strategy to im prove the self-healing properties of Portland cement is presented that is based on the application of the biogenic inorganic polymer polyphosphate (polyP), which is used as a cement admixture. The data show that synthetic linear polyp, with an average chain length of 40, as well as natural long-chain polyP isolated from soil bacteria, has the ability to support self-healing of this construction material. Furthermore, polyP, used as a water-soluble Na-salt, is subject to Na+/Ca2+ exchange by the Ca2+ from the cement, resulting in the formation of a water-rich coacervate when added to the cement surface, especially to the surface of bacteria-containing cement/c…
Unexplored alternative use of calcareous sludge from the paper-pulp industry in green geopolymer construction materials
2020
Abstract Calcareous sludge is an alkaline waste produced by the paper pulp industry that is commonly disposed of in land-fill. However, recent studies and the European regulations discourage such practice. This work investigates an alternative and innovative way to recycle and reuse this waste, as filler, in the production of green geopolymeric mortars intended for applications in construction. This is the first time that this calcareous sludge is used to produce novel waste-based materials, in both construction and geopolymer technology. The novel alkali-activated mortar also uses biomass fly ash – another slightly investigated waste stream – to substitute the metakaolin (70 wt% substituti…
Onset of cohesion in cement paste
2004
It is generally agreed that the cohesion of cement paste occurs through the formation of a network of nanoparticles of a calcium-silicate-hydrate ("C-S-H"). However, the mechanism by which these particles develop this cohesion has not been established. Here we propose a dielectric continuum model which includes all ionic interactions within a dispersion of C-S-H particles. It takes into account all co-ions and counterions explicitly (with pure Coulomb interactions between ions and between ions and the surfaces) and makes no further assumptions concerning their hydration or their interactions with the surface sites. At high surface charge densities, the model shows that the surface charge of…
A numerical model for pre-monitoring design of historical colonnade courtyards: The case study of chiaramonte palace in palermo
2016
This paper proposes a numerical model that can be used for theoretical and experimental dynamic characterization of historical colonnade courtyards. Such an architectural element appears often in buildings of historical heritage and, especially under seismic excitation, it represents the most vulnerable structural part. Therefore, it is very important to have reliable as well as simple models available for vulnerability analysis, to evaluate different reinforcing systems if needed, or to plan dynamic characterization tests or monitoring campaigns, as in the present case. Chiaramonte Palace, a wonderful example of the historical heritage of Palermo, is investigated as case study. Firstly, a …
Practical Calculation Models for Column Footing and Comparison with Experimental Data
2017
In this paper, a simplified calculation model for the prediction of the load-carrying capacity of an RC column footing with a square cross section is presented. A detailed background of available experimental data and existing models for the prediction of the load-carrying capacity of slender and deep footings is presented. Cases of flexural failure and punching shear failures for slender footing and concrete strut crushing and tie yielding in deep members are analyzed. The aim of the paper is to propose a simple design formula for slender and deep footing verified by available experimental data and in agreement with other existing expressions. Expressions of the maximum mechanical ratio of…
Challenges influencing the safety of migrant workers in the construction industry: A qualitative study in Italy, Spain, and the UK
2021
Abstract The construction industry is notoriously high risk for accidents, injuries, and deaths, particularly for non-national or migrant workers, who comprise a significant proportion of the workforce. This paper presents an international, qualitative study focused on exploring the challenges which influence the safety of migrant construction workers in Italy, Spain, and the UK. Based on a comprehensive review of the literature, we formulated two research questions about the challenges relating to safety that migrant workers face and the challenges to safety training effectively improving migrant workers’ safety behaviours. We present our template analysis of semi-structured interviews and…
Procedure for a Temperature-Traffic Model on Rubberized Asphalt Layers for Roads and Railways
2017
The impact of temperature on the mechanical properties and thermal susceptibility of the railway bituminous sub-ballast layer, has served as motivation to develop the advanced measurement of thermal cycles in this layer and, an evaluation of the average seasonal temperatures interpolated by sinusoidal functions, of which characteristic parameters are determined. According to weather situation, Barber’s temperature model was used to prove the effectiveness for the railway superstructure. It is included the assessment of improved modified asphalt mixes performed with coarse rubber from scrap tires, having 1.5 to 3 percent of crumb rubber (particle size 0.2-4 mm) by weight of the total mix, as…
Diagramas ¿Ilustraciones eficaces en la instrucción en ciencias?
2018
<span>Los diagramas científicos constituyen un tipo particular de ilustración que pretende mostrar relaciones entre conceptos antes que identificar entidades particulares, esto es, su objetivo no es reproducir fielmente la realidad (Lowe, 1986). Estos diagramas se caracterizan por contener información codificada de manera altamente económica</span>
Dificultades conceptuales y epistemológicas en el aprendizaje de los procesos químicos
2018
<span>La línea de investigación sobre las concepciones alternativas de los estudiantes en temas de Ciencia ha sido, desde hace más de 20 años, el eje medular del cuerpo teórico de conocimientos que hoy llamamos Didáctica de las Ciencias. Se dispone de mucha información sobre las ideas, preconcepciones o concepciones alternativas como puede apreciarse en la literatura didáctica. Y aunque, como indica Duit (1993), el dominio en el que más se ha investigado es en el de la Física, también hay un 18% de los más de 3,000 artículos referenciados por aquellos autores a los que podemos acudir en el campo de la enseñanza-aprendizaje de la Química (Furió, 1996).</span>