278 research outputs found

    In-situ early age hydration of cement-based materials by synchrotron X-ray powder diffraction

    Get PDF
    Cement based binders are building materials of worldwide importance. Since these samples are very complex, the knowledge/control of their mineralogical composition are essential to design and predict materials with specific/improved performance. Rietveld quantitative phase analysis (RQPA) allows the quantification of crystalline phases and, when combined with specific methodologies, as the addition of an internal standard or the external standard approach (G-factor), amorphous and non-crystalline phases can also be quantified. However, to carry out a proper RQPA in hydrated cementitious-materials, a good powder diffraction pattern is necessary. In this work, synchrotron X-ray powder diffraction (SXRPD) has been used, allowing in-situ measurements during the early-age hydration process. This work deals with the early hydration study of cement-based materials. The studied samples were: a laboratory-prepared belite calcium sulphoaluminate (BCSAF) clinker (non-active) mixed with 10wt% gypsum, labelled G10B0; two active laboratory-prepared BCSAF clinkers (activated with 2wt% borax), one mixed with 10wt% gypsum and the other one with 10wt% monoclinic-bassanite, hereafter named G10B2 and B10B2, respectively; and an environmentally-friendly cement sample from Henkel, composed of bassanite mixed with 15wt% Portland cement and 10wt% Metakaolin, labelled H1. Anhydrous G10B0 contains beta-belite and orthorhombic-ye'elimite as main phases, while alpha'H-belite and pseudo-cubic-ye'elimite are stabilized in G10B2 and B10B2, with the corresponding sulphate source. Anhydrous H1 contains monoclinic and hexagonal bassanite and alite as main phases. Ye'elimite, in the non-active BCSAF cement pastes, dissolves at a higher pace than in the active one (degree of reaction is α~25% and α~10% at 1 h, respectively) (both prepared with gypsum), with the corresponding differences in ettringite crystallisation (degree of precipitation is α~30% and α~5%, respectively). Moreover, the type of sulphate source has important consequences on the hydration of the active BCSAF cement pastes. Bassanite is quickly dissolved and it precipitates as gypsum within the first hour of hydration (in B10B2). At that time, ettringite starts to crystallize, and after 12 hours is almost fully crystallized, similar to G10B2. In H1, bassanite transforms into gypsum within the first hour, being the principal hydration product; ettringite starts to be formed just after few hydration minutes. These results are crucial in the understanding and development of improved cement materials.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    Reference Ontologies to Support the Development of New Product-Service Lifecycle Systems

    Full text link
    In competitive and time sensitive market places, organisations are tasked with providing Product Lifecycle Management (PLM) approaches to achieve and maintain competitive advantage, react to change and understand the balance of possible options when making decisions on complex multi-faceted problems, Global Production Networks (GPN) in one such domain in which this applies. When designing and configuring GPN to develop, manufacture and deliver product-service provision, information requirements that affect decision making become more complex. The application of reference ontologies to a domain and its related information requirements can enhance and accelerate the development of new product-service lifecycle systems with a view towards the seamless interchange of information or interoperability between systems and domains. This paper present preliminary results for the capture and modelling of end-user information and an initial higher level reference core ontology for the development of reference ontologies to ameliorate product-service lifecycle management for GPNPalmer, C.; Urwin, E.; Pinazo-Sanchez, J.; Sánchez Cid, F.; Pajkovska-Goceva, S.; Young, R. (2014). Reference Ontologies to Support the Development of New Product-Service Lifecycle Systems. En Advances in Production Management Systems: Innovative and Knowledge-Based. Springer Verlag. 642-649. doi:10.1007/978-3-662-44736-9_78S642649Vandermerwe, S., Rada, J.: Servitization of business: adding value by adding services. European Management Journal 6(4), 314–324 (1988)Coe, N.M., Dicken, P., Hess, M.: Global production networks: realizing the potential. Economic Geography Research Group, Working Paper Series No. 05.07 (2007)Young, R.I.M., Gunendran, A.G., Chungoora, N., Harding, J.A., Case, K.: Enabling interoperable manufacturing knowledge sharing in PLM. In: Proceedings of the Sixth Interna-tional Conference on Product Life Cycle Management PLM 2009, University of Bath, Bath, UK, July 6-8, pp. 130–138. Inderscience Enterprises Ltd., Switzerland (2009)Chungoora, N., Young, R.I.M.: The configuration of design and manufacture know-ledge models from a heavyweight ontological foundation. International Journal of Production Research 49(15), 4701–4725 (2011)Chungoora, N., Cutting-Decelle, A.-F., Young, R.I.M., Gunendran, G., Usman, Z., Harding, J.A., Case, K.: Towards the ontology-based consolidation of production-centric standards. International Journal of Production Research 51(2), 327–345 (2013a)Hastilow, N.: An Ontological Approach to Manufacturing Systems Interoperability in Dynamic Change Environments. PhD Thesis. School of Mechanical and Manufacturing Engineering, Loughborough University, UK (2013)Highfleet Ontology Library Reference. Highfleet Inc., Baltimore (2014)International Standards Society, ISO/IEC 15288:2008 Systems and Software Engineering – System lifecycle processes. ISO, Genève (2008)Banathy, B.H.: A systems view of education: Concepts and principles for effective practice. Educational Technology (1992)OMG, 2012 OMG unified modeling language (OMG UML), superstructure and infrastructure version 2.4.1 (2012), http://www.omg.org/spec/UML/2.4.1/ (accessed May 9, 2014)Mizoguchi, R., Kozaki, K., Kitamura, Y.: Ontological analyses of roles. In: 2012 Federated Conference on Computer Science and Information Systems (FedCSIS), pp. 489–496. IEEE (September 2012)FIPS PUBs: Integration definition for function modelling (IDEF0). Federal information processing standards publication, 183 (1993)POP* Revised framework Work package – A1.8, Athena European integrated project no. 507849 public deliverable (2006

    Specific leaf area variations in Pinus elliottii var. elliottii Engelm. X Pinus caribaea var hondurensis Morelet. and upscaling to proyected leaf area estimations

    Get PDF
    El área foliar especifica es un parámetro que permite realizar estimaciones del área foliar de las plantas y caracteriza a las especies y su performance en la productividad de los ecosistemas. Se realizaron determinaciones del AFE en diferentes secciones o tercios de la copa de 18 individuos del Pinus elliotti var. elliottii x Pinus caribaea var hondurensis en tres rodales de 7-10-15 años de edad. Las diferencias del AFE resultaron significativas para los tercios y edades con una clara tendencia de aumento desde la sección superior hacia la inferior. El área foliar proyectada (AFP) del tercio medio, calculada a partir del AFE, resulto significativamente diferente respecto al tercio superior e inferior. Las variaciones de AFE responderían a adaptaciones al ambiente y a cambios ontogénicos en los individuos. La mayor AFP del tercio medio podría responder a una estrategia de compensación de tasas de fotosíntesis entre los tercios, particularmente entre los tercios superiores.The specific leaf area is a parameter that allows estimates of leaf area of plant species and characterize its performance in the productivity of ecosystems. SLA determinations were performed in different sections or crown-thirds of 18 individuals of Pinus elliottii var. elliottii x Pinus caribaea var hondurensis in three stands of 7-10-15 years old. SLA differences were significant for third and ages with a clear tendency of increase from the upper to the lower section. Projected leaf area (PLA) from the middle third, calculated from the SLA, was significantly different with respect to upper and lower third. The SLA variations may be due to respond to changes in environment and adaptations to ontogenetic changes in individuals. Most of the middle third PLA could respond to a compensation strategy of photosynthetic rates between the crown-thirds, particularly among upper thirds.Facultad de Ciencias Agrarias y Forestale

    Aspectos ecológicos y ambientales de los bosques nativos y plantaciones forestales de la Argentina : una visión panorámica y conceptual

    Get PDF
    Fil: Frangi, Jorge Luis. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Laboratorio de Investigaciones de Sistemas Ecológicos y Ambientales; ArgentinaFil: Pérez, Carolina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Laboratorio de Investigaciones de Sistemas Ecológicos y Ambientales; ArgentinaFil: Martiarena, Rodolfo Andres. INTA EEA. Misiones; ArgentinaFil: Pinazo, Martín. INTA EEA. Misiones; ArgentinaFil: Martínez Pastur, Guillermo. Centro Austral de Investigaciones Científicas. Tierra del Fuego; ArgentinaFil: Brown, Alejandro. Fundación ProYungas; TucumánFil: Peri, Pablo L.. Universidad Nacional de la Patagonia Austral. INTA EEA. Río Gallegos; ArgentinaFil: Ceballos, Darío S.. INTA EEA. Campana; Argentin

    Management of trypanosomiasis and leishmaniasis

    Get PDF
    <p>Background: The current treatments for human African trypanosomiasis (HAT), Chagas disease and leishmaniasis (collectively referred to as the kinetoplastid diseases) are far from ideal but, for some, there has been significant recent progress. For HAT the only advances in treatment over the past two decades have been the introduction of an eflornithine/nifurtimox co-administration and a shorter regime of the old standard melarsoprol.</p> <p>Sources of data: PubMed.</p> <p>Areas of Agreement: There is a need for new safe, oral drugs for cost-effective treatment of patients and use in control programmes for all the trypanosomatid diseases.</p> <p>Areas of controversy: Cutaneous leishmaniasis is not on the agenda and treatments are lagging behind.</p> <p>Growing points: There are three compounds in development for the treatment of the CNS stage of HAT: fexinidazole, currently due to entry into phase II clinical studies, a benzoxaborole (SCYX-7158) in phase I trials and a diamidine derivative (CPD-0802), in advanced pre-clinical development. For Chagas disease, two anti-fungal triazoles are now in clinical trial. In addition, clinical studies with benznidazole, a drug previously recommended only for acute stage treatment, are close to completion to determine the effectiveness in the treatment of early chronic and indeterminate Chagas disease. For visceral leishmaniasis new formulations, therapeutic switching, in particular AmBisome, and the potential for combinations of established drugs have significantly improved the opportunities for the treatment in the Indian subcontinent, but not in East Africa.</p> <p>Areas timely for developing research: Improved diagnostic tools are needed to support treatment, for test of cure in clinical trials and for monitoring/surveillance of populations in control programmes.</p&gt

    Influence of fly ash blending on hydration and physical behavior of Belite-Alite-Ye'elimite cements

    Get PDF
    A cement powder, composed of belite, alite and ye’elimite, was blended with 0, 15 and 30 wt% of fly ash and the resulting lended cements were further characterized. During hydration, the presence of fly ash caused the partial inhibition of both AFt degradation and belite reactivity, even after 180 days. The compressive strength of the corresponding mortars increased by increasing the fly ash content (68, 73 and 82 MPa for mortars with 0, 15 and 30 wt% of fly ash, respectively, at 180 curing days), mainly due to the diminishing porosity and pore size values. Although pozzolanic reaction has not been directly proved there are indirect evidences.This work is part of the Ph.D. of D. Londono-Zuluaga funded by Beca Colciencias 646—Doctorado en el exterior and Enlaza Mundos 2013 program grant. Cement and Building materials group (CEMATCO) from National University of Colombia is acknowledged for providing the calorimetric measurements. Funding from Spanish MINECO BIA2017-82391-R and I3 (IEDI-2016-0079) grants, co-funded by FEDER, are acknowledged

    Reference ontologies to support the development of global production network systems

    Get PDF
    In competitive and time sensitive market places, organisations are tasked with providing product lifecycle management (PLM) approaches to achieve and maintain competitive advantage, react to change and understand the balance of possible options when making decisions on complex multi-faceted problems, global production networks (GPN) is one such domain in which this applies. When designing and configuring GPN to develop, manufacture and deliver product–service provision, information requirements that affect decision making become more complex. The application of reference ontologies to a domain and its related information requirements can enhance and accelerate the development of new product-service systems with a view towards the seamless interchange of information or interoperability between systems and domains. This paper presents (i) preliminary results for the capture and modelling of end-user information, (ii) an initial higher level reference core ontology for the development of reference ontologies and (iii) the formal logical modelling of Level 1 of the FLEXINET reference ontology using a Common Logic based approach

    An ontology for global production network design and reconfiguration

    Get PDF
    Organisations constantly seek to improve and fully exploit global production networks. This can be to provide more competitive solutions to customer requests, to exploit potential new technologies or to consider new business models based on the servitisation of products. To support such decisions requires the interchange and evaluation of information from a wide range of different and varied sources. This paper puts forward a reference ontology aimed at supporting businesses who seek to design, configure and reconfigure global production networks. The aim of this is to support interoperability between information systems within multi-domain contexts

    An ontology for global production network design and reconfiguration

    Get PDF
    Organisations constantly seek to improve and fully exploit global production networks. This can be to provide more competitive solutions to customer requests, to exploit potential new technologies or to consider new business models based on the servitisation of products. To support such decisions requires the interchange and evaluation of information from a wide range of different and varied sources. This paper puts forward a reference ontology aimed at supporting businesses who seek to design, configure and reconfigure global production networks. The aim of this is to support interoperability between information systems within multi-domain contexts

    Standardised semantic models to support the configuration of global production networks

    Get PDF
    The configuration and deployment of global production networks, raises questions about the interchange of data and information between varied and different organisations, domains and systems. Standards should be an instrumental part of forming a basis to enable seamless interoperability, yet there is no clear support for global production networks. This paper sets out a reference ontology for global production networks being developed as a basis for interoperability between systems, with the potential for it to be developed as a standard
    corecore