Experimental validation of the exact analytical solution to the steady periodic heat transfer problem in a PCM layer

Phase change materials (PCM) are used in many industrial and residential applications for their advantageous characteristic of high capacity of latent thermal storage by means of an isothermal process. In this context, it is very useful to have predictive mathematical models for the analysis of the thermal performance and for the thermal design of these layers. In this work, an experimental validation of an analytical model that resolves the steady periodic heat transfer problem in a finite layer of PCM is presented. The experimental investigation was conducted employing a PCM with thermophysical and thermochemical behavior very close to those hypothesized in the formulation of the analytical model. For the evaluation of the thermophysical properties of the PCM sample used, an experimental procedure created by the authors was employed. In all tests realized in a sinusoidal and non-sinusoidal periodic regime, the comparison between the measured and calculated trends of the temperature at different sample heights and of the surface heat fluxes show an excellent agreement. Moreover, also having verified the analytical total stored energy, the analytical model constitutes a valid instrument for the evaluation of the latent and sensible contribution and the trend in time of the position of the bi-phase interface.The work was partially funded by the Spanish government (ENE2015-64117-C5-1-R (MINECO/FEDER), ENE2015-64117-C5-3-R (MINECO/FEDER), and ULLE10-4E-1305). GREA is certified agent TECNIO in the category of technology developers from the Government of Catalonia. The authors would like to thank the Catalan Government for the quality accreditation given to their research group (2014 SGR 123). This project has received funding from the European Commission Seventh Framework Programme (FP/2007-2013) under Grant agreement Nº PIRSES-GA-2013-610692 (INNOSTORAGE) and from European Union's Horizon 2020 research and innovation programme under grant agreement Nº 657466 (INPATH-TES). Alvaro de Gracia would like to thank Ministerio de Economia y Competitividad de España for Grant Juan de la Cierva, FJCI-2014-19940. Julià Coma would like to thank the Departament d'Universitats, Recerca i Societat de la Informació de la Generalitat de Catalunya for his research fellowship (2016FI_B2 00147). Aran Solé would like to thank Ministerio de Economía y Competitividad de España for Grant Juan de la Cierva, FJCI-2015-25741

The balance between GMD and OFUT1 regulates notch signaling pathway activity by modulating notch stability

The Notch signaling pathway plays an important role in development and physiology. In Drosophila, Notch is activated by its Delta or Serrate ligands, depending in part on the sugar modifications present in its extracellular domain. O-fucosyltransferase-1 (OFUT1) performs the first glycosylation step in this process, O-fucosylating various EGF repeats at the Notch extracellular domain. Besides its O-fucosyltransferase activity, OFUT1 also behaves as a chaperone during Notch synthesis and is able to down regulate Notch by enhancing its endocytosis and degradation. We have reevaluated the roles that O-fucosylation and the synthesis of GDP-fucose play in the regulation of Notch protein stability. Using mutants and the UAS/Gal4 system, we modified in developing tissues the amount of GDP-mannosedeshydratase (GMD), the first enzyme in the synthesis of GDP-fucose. Our results show that GMD activity, and likely the levels of GDPfucose and O-fucosylation, are essential to stabilize the Notch protein. Notch degradation observed under low GMD expression is absolutely dependent on OFUT1 and this is also observed in Notch Abruptex mutants, which have mutations in some potential O-fucosylated EGF domains. We propose that the GDP-fucose/OFUT1 balance determines the ability of OFUT1 to endocytose and degrade Notch in a manner that is independent of the residues affected by Abruptex mutations in Notch EGF domains.This work was funded by ICM P06-039F grant to A.G. and by a BFU2009-09403 grant of the M.E.C. to J.F.dC. An institutional grant from the Ramón Areces Foundation to the CBMSO is also acknowledged.Peer Reviewe

Performance implications of three-mirror Fabry-Perot demultiplexers for 10-Gb/s WDM dispersion-supported transmission with 0.5-nm channel spacing

This letter assesses the performance of dispersion-supported transmission (DST) for three 10-Gb/s WDM channels separated 0.5 nm, using a three-mirror Fabry-Perot demultiplexer. It is shown that the use of three-mirror demultiplexers reduces the crosstalk penalty to less than 1 dB in the region of small linear increase of dispersion penalty of the DST method, while double-cavity Fabry-Perot demultiplexers are less suitable to operate at this channel spacing. Compared with published performance studies for WDM-DST systems with 1 nm of channel spacing, these results indicate the channel spacing may be cut in a half, if a three-mirror filter is used as demultiplexe

On the use minor and non-destructive methods for the safety evaluation of an historic RC bridge: the Bôco Bridge

The authors would like to express their gratitude to Tezin Nyandak and Gonçalo Escusa for their help during the experimental campaign. The work was also financed by FEDER funds through the Competitiveness Factors Operational Programme - COMPETE and by national funds through FCT – Foundation for Science and Technology within the scope of the project POCI-01-0145-FEDER-007633.Currently in use, the Bôco Reinforced Concrete (RC) Bridge, built in the early of 20th century, is one of the oldest RC bridges in Portugal. Its initial structural system, erected following the Hennebique system, was retrofitted in the 1960s to support heavy traffic, increasing the section of its structural components. However, the low quality of implemented retrofitting solution has promoted the presence of pathological processes, mainly concrete spalling and steel corrosion. In this context, the present paper shows the first results obtained during the second experimental campaign carried out on the bridge. This campaign comprised the use of several minor and non-destructive methods (laser scanning, operational modal analysis, and laboratory material characterization and mechanical tests), with the aim of improving the knowledge of the bridge and create an accurate numerical simulation (by means of Finite Element Model) to evaluate the safety level of this bridge. Results derived from this campaign, show a bridge with high load capacity, verifying the Ultimate Limit State.FCT -Fundação para a Ciência e a Tecnologia(POCI-01-0145-FEDER-007633)info:eu-repo/semantics/publishedVersio

Study of the thermal properties and the fire performance of flame retardant-organic PCM in bulk form

The implementation of organic phase change materials (PCMs) in several applications such as heating and cooling or building comfort is an important target in thermal energy storage (TES). However, one of the major drawbacks of organic PCMs implementation is flammability. The addition of flame retardants to PCMs or shape-stabilized PCMs is one of the approaches to address this problem and improve their final deployment in the building material sector. In this study, the most common organic PCM, Paraffin RT-21, and fatty acids mixtures of capric acid (CA), myristic acid (MA), and palmitic acid (PA) in bulk, were tested to improve their fire reaction. Several flame retardants, such as ammonium phosphate, melamine phosphate, hydromagnesite, magnesium hydroxide, and aluminum hydroxide, were tested. The properties of the improved PCM with flame retardants were characterized by thermogravimetric analyses (TGA), the dripping test, and differential scanning calorimetry (DSC). The results for the dripping test show that fire retardancy was considerably enhanced by the addition of hydromagnesite (50 wt %) and magnesium hydroxide (50 wt %) in fatty acids mixtures. This will help the final implementation of these enhanced PCMs in building sector. The influence of the addition of flame retardants on the melting enthalpy and temperatures of PCMs has been evaluated

New formulation and characterization of enhanced bulk-organic phase change materials

The main drawbacks faced by researchers to successfully implement organic-PCM as materials to improve the thermal performance of building systems are their low thermal conductivity, their high flammability, and their low thermal cycling stability. T In the present work, authors present a new enhanced PCM formulations aimed to solve the stated disadvantages in organic bulk-PCM. The new enhanced PCM were prepared by adding high thermal conductivity particles and two kinds of flame retardants into organic PCM (paraffin and fatty acid eutectic mixtures). In the first stage, the effective thermal conductivity of organic-PCM was increased by using two different methods: directly dispersion of powder graphite (PG) bulk-PCM and vacuum impregnation of PCM into expanded graphite (EG). In the second stage, the fire reaction behaviour of the thermal conductivity enhanced PCM formulations was improved by adding two kind of flame retardant: magnesium hydroxide and ammonium phosphate (APP).. Their fire reaction behaviour, thermal conductivity and thermophysical properties were measured by adapting the dripping test (UNE 23727-90), the hot-wire method and Differential Scanning Calorimetry (DSC), respectively. The enhanced PCM composites show a self-extinguished behaviour in terms of fire performance mechanism. The EG working with endothermic and phosphates flame retardants improve the fire performance of PCM by acting as a synergic system and the thermal conductivity is increased. However, their thermal storage capacity is significant decreased due to the large amount of flame retardant added (up to 40%). The thermal reliability was also tested, the enhanced PCM composites were stable up to 1000 thermal cycles

Solar absorption in a ventilated facade with PCM. Experimental results

1st International Conference on Solar Heating and Coolingfor Buildings and Industry (SHC 2012)The paper investigates experimentally the thermal performance of a ventilated double skin facade (DSF) with phase change material (PCM) in its air channel, during the heating season in the Mediterranean climate. Two identical house-like cubicles located in Puigverd de Lleida (Spain) were monitored during winter 2012, and in one of them, a ventilated facade with PCM was located in the south wall. The ventilated facade can operate under mechanical or natural ventilation mode and its thermal control depends on the weather conditions and the energetic demand of the building. The experimental results conclude that even though the use of the ventilated facade with PCM improves significantly the thermal behaviour of the whole building (working as a heat supplier in free floating tests, and reducing significantly the electrical consumption of the HVAC systems), these improvements might be increased if a thermal control is used.This work was supported by the “Corporación Tecnológica de Andalucía” by means of the project “MECLIDE-Soluciones estructurales con materiales especiales para la climatización diferida de edificios” with the colaboration of DETEA. The work was partially funded by the Spanish government (ENE2011-28269-C03-02) and the European Union (COST Action COST TU0802), and in collaboration with DETEA. The authors would like to thank the Catalan Government for the quality accreditation given to their research group (2009 SGR 534)

Non-destructive means and methods for structural diagnosis of masonry arch bridges

Within the precepts defended by the International Charter of Kraków, this paper aims at presenting a fully non-destructive multidisciplinary approach able to characterize masonry bridges at three different levels: i) geometrical level; ii) material level and; iii) structural level. To this end, this approach integrates the terrestrial laser scanner, the sonic and impact-echo methods, the ground penetrating radar and the multichannel analysis of surface waves. All these data are combined with reverse engineering procedures, allowing the creation of suitable as-built CAD models for advanced numerical simulations. Then, these numerical models are contrasted and updated through the data provided by the ambient vibration tests. To validate the methodology proposed in this paper, the Roman bridge of Avila was used as study case. This bridge shows a complex mixture of constructive techniques (masonry, cohesive material, Opus Caementicium and reinforced concrete). Thus, the numerical model was considered for performing predictive structural analysis.Junta of Castilla y León | Ref. SA075P1