Reflejos en termografía infrarroja. Nuevo método para la estimación de la emisividad de superficies con acabado especular

Existe mucha confusión sobre el concepto de reflectividad. Es normal suponer que las superficies con reflejo especular tienen una reflectividad alta, y por tanto las que no se comportan como espejo, baja. El objetivo de este trabajo es mostrar de forma práctica que es muy común la existencia de superficies con baja reflectividad pero con reflejo especular, y compararlo con el comportamiento de superficies especulares de alta reflectividad. Por otra parte, se demuestra que es posible medir temperaturas sobre superficies especulares, incluso aunque aparezcan “falsos puntos calientes”. Finalmente se propone un método para determinar la emisividad de superficies especulares con baja emisividad, hasta valores incluso inferiores a 0.1

Experimental resuts and simulation with TRNSYS of a 7.2 kWp grid-connected photovoltaic system

This paper presents a dynamic model and experimental results of a 7.2. kWp photovoltaic (PV) installation located at the Polytechnic University of Valencia (Spain). The modelling of the monocrystalline cells has been realised in TRNSYS and has been validated during an extensive experimental campaign from January 2001 to March 2003, using the data of a fully monitored PV field. The simulation results with TRNSYS provide an accurate prediction of the long-term performance. In addition to the dynamic models, algebraic methods such as the constant fill factor have also been applied.In the design of PV systems, there are several important uncertainties which have to be taken into account, such as the reduction of power with respect to the nominal power under Standard Test Conditions (STC), the choice of the meteorological database, and the models for the calculation of the radiation on tilted surface and of the cell temperature. These aspects are analyzed thoroughly in this paper, as well as the problems inherent to the PV power injection into the grid.Quesada, BR.; Sánchez, C.; Cañada, J.; Royo Pastor, R.; J. Payá (2011). Experimental resuts and simulation with TRNSYS of a 7.2 kWp grid-connected photovoltaic system. Applied Energy. 88:1772-1783. doi:10.1016/j.apenergy.2010.12.011S177217838

Thermographic study of the preheating plugs in diesel engines

The use of direct injection diesel engines has been widely applied during the past ten years. In such engines, the preheating plugs are a key element which has a significant contribution in the pollutant emissions. In this paper, two different plug designs from Renault are analyzed. The new plug reduces substantially the required electrical consumption. Nevertheless, the pollutant emissions are higher (fundamentally CO and HCs) and hereby a thorough analysis is required to understand the possible reasons. Firstly, an infrared thermography analysis of the plugs has been carried out. The new plug tip presents 100e200 C higher temperatures than with the former design. Secondly, a thermal model has been developed and validated with temperature measurements. The latter model has helped to obtain the energy flow diagram. Finally, a thermography analysis of the head of the cylinders has been carried out. The results show that the higher exhaust emissions are related with an incomplete combustion process due to a thin air gap which surrounds the tip of the plug.The authors gratefully acknowledge RENAULT SPAIN and RENAULT FRANCE for the funding of research projects during the past 20 years.Royo Pastor, R.; Albertos Arranz, M.; Cárcel Cubas, JA.; Payá Herrero, J. (2012). Thermographic study of the preheating plugs in diesel engines. Applied Thermal Engineering. 37:412-419. doi:10.1016/j.applthermaleng.2011.11.059S4124193

Charge Transport in Trap-Sensitized Infrared PbS Quantum-Dot-Based Photoconductors: Pros and Cons

Control of quantum-dot (QD) surface chemistry offers a direct approach for the tuning of charge-carrier dynamics in photoconductors based on strongly coupled QD solids. We investigate the effects of altering the surface chemistry of PbS QDs in such QD solids via ligand exchange using 3-mercaptopropionic acid (MPA) and tetrabutylammonium iodide (TBAI). The roll-to-roll compatible doctor-blade technique was used for the fabrication of the QD solid films as the photoactive component in photoconductors and field-effect phototransistors. The ligand exchange of the QD solid film with MPA yields superior device performance with higher photosensitivity and detectivity, which is due to less dark current and lower noise level as compared to ligand exchange with TBAI. In both cases, the mechanism responsible for photoconductivity is related to trap sensitization of the QD solid, in which traps are responsible of high photoconductive gain values, but slow response times under very low incident optical power (100 pW), where traps are filled, both MPA- and TBAI-treated photodevices exhibit similar behavior, characterized by lower responsivity and faster response time, as limited by the mobility in the QD solid

Tin perovskite solar cells with >1,300 h of operational stability in N2 through a synergistic chemical engineering approach

Despite the promising properties of tin-based halide perovskites, one clear limitation is the fast Sn+2 oxidation. Consequently, the preparation of long-lasting devices remains challenging. Here, we report a chemical engineering approach, based on adding Dipropylammonium iodide (DipI) together with a well-known reducing agent, sodium borohydride (NaBH4), aimed at preventing the premature degradation of Sn-HPs. This strategy allows for obtaining efficiencies (PCE) above 10% with enhanced stability. The initial PCE remained unchanged upon 5 h in air (60% RH) at maximum-power-point (MPP). Remarkably, 96% of the initial PCE was kept after 1,300 h at MPP in N2. To the best of our knowledge, these are the highest reported values for Sn-based solar cells. Our findings demonstrate a beneficial synergistic effect when additives are incorporated, highlight the important role of iodide in the performance upon light soaking, and, ultimately, unveil the relevance of controlling the halide chemistry for future improvement of Sn-based perovskite devices

Energy performance of a ventilated façade by simulation with experimental validation

A model for a building with ventilated façade was created using the software tool TRNSYS, version 17, and airflow parameters were simulated using TRNFlow. The results obtained with the model are compared and validated with experimental data. The temperature distribution along the air cavity was analysed and a chimney effect was observed, which produced the highest temperature gradient on the first floor. The heat flux of the external wall was analysed, and greater temperatures were observed on the external layer and inside the cavity. The model allows to calculate the energy demand of the building façade proposing and evaluating passive strategies. The corresponding office building for computer laboratories located in Valencia (Spain), was monitored for a year. The thermal behaviour of the floating external sheet was analysed using an electronic panel designed for the reading and storage of data. A feasibility study of the recovery of hot air inside the façade into the building was performed. The results obtained showed a lower heating demand when hot air is introduced inside the building, increasing the efficiency of heat recovery equipment.The English revision of this paper was funded by the Universitat Politecnica de Valencia, Spain.Aparicio Fernandez, CS.; Vivancos, J.; Ferrer Gisbert, P.; Royo Pastor, R. (2014). Energy performance of a ventilated façade by simulation with experimental validation. Applied Thermal Engineering. 66(1-2):563-570. doi:10.1016/j.applthermaleng.2014.02.041S563570661-

New insights into the genetic etiology of Alzheimer's disease and related dementias

Characterization of the genetic landscape of Alzheimer's disease (AD) and related dementias (ADD) provides a unique opportunity for a better understanding of the associated pathophysiological processes. We performed a two-stage genome-wide association study totaling 111,326 clinically diagnosed/'proxy' AD cases and 677,663 controls. We found 75 risk loci, of which 42 were new at the time of analysis. Pathway enrichment analyses confirmed the involvement of amyloid/tau pathways and highlighted microglia implication. Gene prioritization in the new loci identified 31 genes that were suggestive of new genetically associated processes, including the tumor necrosis factor alpha pathway through the linear ubiquitin chain assembly complex. We also built a new genetic risk score associated with the risk of future AD/dementia or progression from mild cognitive impairment to AD/dementia. The improvement in prediction led to a 1.6- to 1.9-fold increase in AD risk from the lowest to the highest decile, in addition to effects of age and the APOE ε4 allele

Common variants in Alzheimer’s disease and risk stratification by polygenic risk scores

Funder: Funder: Fundación bancaria ‘La Caixa’ Number: LCF/PR/PR16/51110003 Funder: Grifols SA Number: LCF/PR/PR16/51110003 Funder: European Union/EFPIA Innovative Medicines Initiative Joint Number: 115975 Funder: JPco-fuND FP-829-029 Number: 733051061Genetic discoveries of Alzheimer's disease are the drivers of our understanding, and together with polygenetic risk stratification can contribute towards planning of feasible and efficient preventive and curative clinical trials. We first perform a large genetic association study by merging all available case-control datasets and by-proxy study results (discovery n = 409,435 and validation size n = 58,190). Here, we add six variants associated with Alzheimer's disease risk (near APP, CHRNE, PRKD3/NDUFAF7, PLCG2 and two exonic variants in the SHARPIN gene). Assessment of the polygenic risk score and stratifying by APOE reveal a 4 to 5.5 years difference in median age at onset of Alzheimer's disease patients in APOE ɛ4 carriers. Because of this study, the underlying mechanisms of APP can be studied to refine the amyloid cascade and the polygenic risk score provides a tool to select individuals at high risk of Alzheimer's disease

New insights into the genetic etiology of Alzheimer's disease and related dementias

Characterization of the genetic landscape of Alzheimer's disease (AD) and related dementias (ADD) provides a unique opportunity for a better understanding of the associated pathophysiological processes. We performed a two-stage genome-wide association study totaling 111,326 clinically diagnosed/'proxy' AD cases and 677,663 controls. We found 75 risk loci, of which 42 were new at the time of analysis. Pathway enrichment analyses confirmed the involvement of amyloid/tau pathways and highlighted microglia implication. Gene prioritization in the new loci identified 31 genes that were suggestive of new genetically associated processes, including the tumor necrosis factor alpha pathway through the linear ubiquitin chain assembly complex. We also built a new genetic risk score associated with the risk of future AD/dementia or progression from mild cognitive impairment to AD/dementia. The improvement in prediction led to a 1.6- to 1.9-fold increase in AD risk from the lowest to the highest decile, in addition to effects of age and the APOE ε4 allele

Common variants in Alzheimer's disease and risk stratification by polygenic risk scores.

Funder: Funder: Fundación bancaria ‘La Caixa’ Number: LCF/PR/PR16/51110003 Funder: Grifols SA Number: LCF/PR/PR16/51110003 Funder: European Union/EFPIA Innovative Medicines Initiative Joint Number: 115975 Funder: JPco-fuND FP-829-029 Number: 733051061Genetic discoveries of Alzheimer's disease are the drivers of our understanding, and together with polygenetic risk stratification can contribute towards planning of feasible and efficient preventive and curative clinical trials. We first perform a large genetic association study by merging all available case-control datasets and by-proxy study results (discovery n = 409,435 and validation size n = 58,190). Here, we add six variants associated with Alzheimer's disease risk (near APP, CHRNE, PRKD3/NDUFAF7, PLCG2 and two exonic variants in the SHARPIN gene). Assessment of the polygenic risk score and stratifying by APOE reveal a 4 to 5.5 years difference in median age at onset of Alzheimer's disease patients in APOE ɛ4 carriers. Because of this study, the underlying mechanisms of APP can be studied to refine the amyloid cascade and the polygenic risk score provides a tool to select individuals at high risk of Alzheimer's disease