Composite cure assessment using spectral analysis (via an embedded optical fibre sensor).

Available from British Library Document Supply Centre-DSC:DXN051258 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo

Study of the Effect of Siliceous Species in the Formation of a Geopolymer Binder: Understanding the Reaction Mechanisms among the Binder, Wood, and Earth Brick.

International audienceIn building construction, geopolymer binder or mortar can interact with the structural materials and thus modify the binder formation mechanisms. In a geopolymer binder, the availability and amount of siliceous species is a preponderant parameter influencing the nature of networks formed after consolidation. In this study, the interactions between the binder and structural materials (wood and earth bricks) were investigated by 29Si magic angle spinning nuclear magnetic resonance (MAS NMR) and Fourier transform infrared spectroscopy (FTIR) during and after the consolidation. Then, the effect of the amount and nature of the siliceous species available in the reaction medium were analyzed. According to the siliceous species available, it is possible to form different types of materials (hardening or sedimented materials). By corroborating these results with MAS NMR and FTIR analyses, a formation scheme of the binder in contact with the materials was proposed

Variabilité du module d'Young : influence sur le comportement des voûtes en maçonnerie

International audience Le module d'Young des pierres naturelles, même issues du même massif, peut varier considérablement dans un ratio de 1 à 2 (Binda et al. 2003). Il pourrait être nécessaire d'en tenir compte dans les calculs. L'objectif de ce papier est de présenter une méthodologie permettant d'évaluer la capacité portante et de prédire le mécanisme de ruine des voûtes maçonnées avec la prise en compte de cette variabilité naturelle de la pierre de construction. En utilisant une approche probabiliste, l'étude d'une voûte composée de 16 voussoirs est présentée. Le module d'Young des voussoirs est considéré comme étant une variable aléatoire. L'approche probabiliste nécessite souvent d'effectuer un grand nombre de calculs de la réponse mécanique, un compromis a été trouvé donc entre le temps de calcul et la précision. La méthode de calcul consiste à assimiler la voûte à une ossature plane 1D formée d'éléments poutres à deux nœuds chargées en flexion et en compression. La formation de rotules est conditionnée par le théorème du tiers central. La formation de quatre rotules successives est synonyme de mécanisme de ruine. Le calcul est implémenté dans un logiciel développé à cet effet (ArcProg-Z).  Le principe consiste à affecter aux voussoirs des valeurs du module d'Young de façon tout-à-fait aléatoire. Le programme développé calcule ensuite la valeur de la charge critique ainsi que sa position et détermine le mécanisme de ruine correspondant à chaque combinaison de valeurs affectée. Le calcul est répété pour 10000 combinaisons soient 160000 valeurs du module d'Young tirées aléatoirement suivant une loi normale définie par sa valeur moyenne et son coefficient de variation. Ce même calcul est effectué en considérant 3 valeurs différentes du coefficient de variation : 5%, 10% et 20%.  Les résultats obtenus sont exploités de trois angles différents. Le premier concerne la variation de la capacité portante de la voûte en fonction des combinaisons de valeurs du module affectées aux voussoirs. Le second observe les positions des différentes rotules formées et le troisième angle étudie l'importance de la prise en compte de cette variabilité du module dans les calculs. Une relation qui relie la capacité portante de la voûte à la variation des modules des différents voussoirs est proposée. Cette relation a permis d'identifier les voussoirs dont la chute du module contribuera le plus à la chute de la capacité portante i.e. les voussoirs sur lesquels aucun défaut n'est toléré.  Les mécanismes de ruine sont identifiés dans les différents cas (déterministe, CV=5%, 10% et 20%) ainsi que leur probabilité d'occurrence. Les résultats montrent que le mécanisme observé dans le cas déterministe (modules tous égaux à la valeur moyenne de la loi) est celui qui a la plus forte probabilité. Les calculs ont montré que le nombre de ces mécanismes ainsi que leurs probabilités d'occurrence augmentent en fonction du coefficient de variation du module d'Young. Cela signifie que si une variation importante du module d'Young des voussoirs est avérée, sa prise en compte dans les calculs est impérative, que ce soit pour la détermination de la capacité portante de la voûte ou pour prédire son mécanisme de ruine.</p

Regimes of droplet train impact on a moving surface in an additive manufacturing process

In jetting-based additive manufacturing, one or more droplet trains are deposited on a moving surface to fabricate layers in an additive approach. The impact behaviour of the droplets onto the surface defines the final fabricated layer properties in terms of geometry and surface finish. This paper reports on such behaviour when depositing a solution of a bio-degradable resin towards an ultimate goal of fabricating bone implants in an additive manufacturing process. The solution was jetted via a fixed single nozzle continuous piezoelectric printhead on a moving surface. The effect of two main process parameters, jetting frequency and substrate linear velocity, on the impact behaviour was investigated. Quantitative analysis was undertaken to investigate the droplet formation characteristics and droplet/surface interactions. The phenomena associated with the interaction at the front of the advancing liquid layer were correlated with the process conditions. The result was a classification of the droplet train/moving surface interactions into three main regimes depending on the droplet impingement characteristics and the surface motion

Design methodology for integrating multipath systems (building services)

Purpose – The purpose of this paper is to report on a geometrical integration methodology that can be used to organise some types of these systems. Most multipath delivery systems, such as Building Services (BSs), are arbitrarily distributed with no known solution to reduce the complexity in the way channels are arranged. Design/methodology/approach – Integration for optimal functionality through reduction of geometrical complexity is achieved by understanding the elements of complexity within current practices; identifying commonalities between the various components which can be used for integration; performing an axiomatic design to resolve design complications; adopting theory of inventive problem-solving for methodology and process development towards optimal functionality; and generating a mathematical solution to inform digital modelling of optimal design. The study takes into account thermophysical and electromagnetic interactions between utilities and uses novel mathematical manipulations based on designing a manifold of spherical and cylindrical geometries joined using Bezier surfaces. Findings – Once a solution was reached, computer-aided design (CAD) iterations were undertaken for channelling six BSs into a single unit. The outcome was concentric cylindrical–spherical shells superimposed with spacings of typically few millimetres to deliver/distribute the utilities. It is applied to bring together BSs into a single trunking system at minimal, yet appropriate, proximal distances, and it allows distribution of any number of services in any direction. Physical prototypes were produced and initial testing of their performance (reported elsewhere) has been encouraging. Originality/value – A design methodology for integrating arbitrary distributed paths/conduits. The approach could be incorporated into CAD tools as a design feature to facilitate integration of multipath delivery systems

Design approach for the integration of services in buildings

This paper describes a novel methodology to group building services (BSs) into a single trunking system at minimal proximal distances between them. The study focused on solving the geometrical complexity encountered in conventional arrangements of BSs, while taking into account thermophysical and electromagnetic interactions between services together with building regulations. The potential solution for delivery and distribution of BSs in any number of directions is an ‟onion layers„ type of design, using novel mathematical manipulations based on manifolds of spherical and cylindrical geometries joined using Bezier surfaces. Computer Aided Design iterations were undertaken for channelling six BSs into a single unit including water, air, electricity and data. It consists of concentric cylindrical-spherical shells superimposed at few millimetres gaps (channels) for which physical prototypes were produced

Monitoring the polymerization of a diglycidyl ether bisphenol-A/2,2'-dimethyl-4,4'-methylenebis (cyclohexylamine) matrix with a Fourier transform infrared optical fibre sensor

An optical fibre sensor (OFS) for the online monitoring of the polymerization reaction is described in this paper. The sensor, based on Fourier transform infrared (FT-IR) and differential scanning calorimetry (DSC) analysis, was used to study the reaction between diglycidyl ether bisphenol-A (DGEBA) and 2,20-dimethyl-4,40-methylenebis(cyclohexylamine) (DMMB-CHA). Changes in concentrations of reactants and products were monitored over the curing period at different temperatures by the FT-IR technique, and from DSC runs the variation in the enthalpy of reaction over time for different curing temperatures was determined. Plots of fractional conversions versus time from the two methods were produced and compared. An attempt to deduce glass transition temperatures from the fractional conversion curves produced by FT-IR is also described. This involved the use of the fitting polynomial calculated from the DSC results. As a result, a sensor designed for embedding into a system curing at elevated temperature was constructed and tested

BIM enabled building energy modelling: development and verification of a GBXML to IDF conversion method

As part of the Design4Energy retrofit scenario a methodology is developed that uses Building Information Modelling (BIM) of existing domestic buildings to assess their energy performance using a Building Energy Modelling (BEM) technique. The focus is on the conversion process from gbXML BIM export file to an idf file for EnergyPlusTM. The conversion process is broken down into six steps of progressive addition of idf objects to enable verification. The measured operational data are used to assess the adequacy of the defaults being used

Developing suitable thermal models for domestic buildings with Smart Home equipment

Smart Home controls are part of a Smart Home system and allow remote and automated control of heating systems. The key research question is: with the rapid advancement of new wireless and networked control products, which thermal modelling techniques are able to best make use of the real-time performance data arising from in-home sensors and predict the impact of using advanced controls to reduce energy demand and maximise comfort? As part of identifying suitable modelling approaches for Smart Homes, a lumped parameter model which builds on the work done by Bacher and Madsen (2011) using a data-driven “Grey box” model has been developed. The potential for using the measured data and the impacts of advanced controls for this modelling technique are discussed

Decision support to enable energy efficient building design for optimised retrofit and maintenance

Optimising energy consumption of new buildings (through design) and reducing energy consumption of existing buildings (using optimised retrofitting or maintenance) are important to achieving the global targets of energy saving and cutting CO2 emissions of buildings. Many decision support tools have been developed for architects and building designers to choose the best building design options with retrofit and maintenance in mind. However, there is a lack of understanding of the required data structures and databases that would support design and enable Facility Management (FM) in making best decisions during retrofit and maintenance for improved energy efficiency (EE). To address these limitations a decision support tool based on Multiple Criteria Decision Making (MCDM) for architects, energy designers and for FM is being developed within an ongoing EU research project “Design4Energy”, to enable design for EE maintenance and retrofit and support the FM in the operation stage. In this paper three aspects are presented: (1) analysis of existing decision support tools; (2) detailing the database requirements in terms of information technology (IT), components and systems, materials and the stakeholders on the basis of a literature search and a survey conducted with of stakeholders from the building sector; (3) a first prototype of a decision support tool for maintenance and retrofit being developed