Limitations of visual gamma corrections in LCD displays

A method for estimating the non-linear gamma transfer function of liquid-crystal displays (LCDs) without the need of a photometric measurement device was described by Xiao et al. (2011) [1]. It relies on observer's judgments of visual luminance by presenting eight half-tone patterns with luminances from 1/9 to 8/9 of the maximum value of each colour channel. These half-tone patterns were distributed over the screen both over the vertical and horizontal viewing axes. We conducted a series of photometric and psychophysical measurements (consisting in the simultaneous presentation of half-tone patterns in each trial) to evaluate whether the angular dependency of the light generated by three different LCD technologies would bias the results of these gamma transfer function estimations. Our results show that there are significant differences between the gamma transfer functions measured and produced by observers at different viewing angles. We suggest appropriate modifications to the Xiao et al. paradigm to counterbalance these artefacts which also have the advantage of shortening the amount of time spent in collecting the psychophysical measurements

Influencia de los defectos geométricos en la superficie de contacto de un disipador de calor, orientado a la asignación de sus tolerancias de fabricación

Comunicación presentada en el XXI Congreso Nacional de Ingeniería Mecánica, celebrado en Elche en Noviembre de 2016.Las desviaciones de la geometría real en los componentes fabricados respecto de la geometría ideal tratada durante el diseño provocan la aparición de anomalías durante el funcionamiento de componentes ensamblados, siendo necesario limitar estas desviaciones mediante una apropiada síntesis de tolerancias (su especificación y la asignación de sus valores) de modo que se garantice la funcionalidad. Esta síntesis de tolerancias se deberá llevar a cabo efectuando un estudio detallado de cómo las desviaciones de fabricación afectan a la función, y asignando valores de las tolerancias atendiendo a criterios de capacidad y de costes de fabricación. Sin embargo, las relaciones entre el valor de las tolerancias y la calidad de funcionamiento no están siempre claras, por lo que las tolerancias se especifican asignando valores "habituales" o recomendados. Este proceder es frecuente y lleva a que se establezcan, con gran frecuencia, esquemas inconsistentes de tolerancias, que conducen a asignar valores para las tolerancias excesivamente estrechos. Como consecuencia de todo ello las piezas resultan caras y el propio funcionamiento del conjunto puede incluso no quedar garantizado. En este trabajo se analiza un sistema compuesto por un circuito integrado (CI) y un disipador de calor sobre él montado, estudiando cómo influyen los errores de fabricación presentes en la superficie del disipador en la capacidad de transmisión de calor en la zona de contacto entre CI y disipador, siendo el requisito funcional la transmisión de una cantidad de calor Q definida bajo unas condiciones de contorno ambientales. Como resultado se obtendrán las ecuaciones funcionales que ligan el RF con la tipología y magnitud de los errores, particularizado para el caso concreto de los defectos de rugosidad superficial en la superficie del CI

Estudio de los factores de transmisión de la variabilidad dimensional en la fabricación de baldosas cerámicas

Comunicación presentada en el XXI Congreso Nacional de Ingeniería Mecánica, celebrado en Elche en Noviembre de 2016.Uno de los principales problemas en la fabricación de pavimento en la industria cerámica es la variabilidad dimensional tras la cocción del producto cerámico que ocasiona la clasificación del producto en diferentes calibres o calidades dimensionales. A pesar del conocimiento extenso del proceso de fabricación de las baldosas cerámicas, pocos son los trabajos que buscan analizar las interacciones entre las diferentes etapas del proceso para estimar la variación dimensional final del producto. Un análisis global del proceso permitiría realizar modificaciones de puntos de operación en ciertas etapas para minimizar la variabilidad, o estudiar en detalle las etapas críticas del proceso sobre las que implementar acciones de mejora. Este trabajo muestra un estudio del proceso global de fabricación de las baldosas cerámicas y la aplicación de la metodología Stream-of-Variation para el modelado de la propagación de errores entre las diferentes etapas del proceso.Este trabajo ha sido financiado por la Generalitat Valenciana en su programa de ayudas a proyectos de I+D para grupos emergentes convocatoria 2015, proyecto GV/2015/091

Chemical variations in Quercus pollen as a tool for taxonomic identification: Implications for long-term ecological and biogeographical research

Aim Fossil pollen is an important tool for understanding biogeographical patterns in the past, but the taxonomic resolution of the fossil‐pollen record may be limited to genus or even family level. Chemical analysis of pollen grains has the potential to increase the taxonomic resolution of pollen analysis, but present‐day chemical variability is poorly understood. This study aims to investigate whether a phylogenetic signal is present in the chemical variations of Quercus L. pollen and to assess the prospects of chemical techniques for identification in biogeographical research. Location Portugal. Taxon Six taxa (five species, one subspecies) of Quercus L., Q. faginea, Q. robur, Q. robur ssp. estremadurensis, Q. coccifera, Q. rotundifolia and Q. suber belonging to three sections: Cerris, Ilex and Quercus (Denk, Grimm, Manos, Deng, & Hipp, 2017). Methods We collected pollen samples from 297 individual Quercus trees across a 4° (~450 km) latitudinal gradient and determined chemical differences using Fourier‐transform infrared spectroscopy (FTIR). We used canonical powered partial least squares regression (CPPLS) and discriminant analysis to describe within‐ and between‐species chemical variability. Results We find clear differences in the FTIR spectra from Quercus pollen at the section level (Cerris: ~98%; Ilex: ~100%; Quercus: ~97%). Successful discrimination is based on spectral signals related to lipids and sporopollenins. However, discrimination of species within individual Quercus sections is more challenging: overall, species recall is ~76% and species misidentifications within sections lie between 18% and 31% of the test set. Main Conclusions Our results demonstrate that subgenus level differentiation of Quercus pollen is possible using FTIR methods, with successful classification at the section level. This indicates that operator‐independent FTIR approaches can surpass traditional morphological techniques using light microscopy. Our results have implications both for providing new insights into past colonization pathways of Quercus, and likewise for forecasting future responses to climate change. However, before FTIR techniques can be applied more broadly across palaeoecology and biogeography, our results also highlight a number of research challenges that still need to be addressed, including developing sporopollenin‐specific taxonomic discriminators and determining a more complete understanding of the effects of environmental variation on pollen‐chemical signatures in Quercus.publishedVersio

Organocatalytic enantioselective functionalization of indoles in the carbocyclic ring with cyclic imines

An organocatalytic enantioselective functionalization in the carbocyclic ring of indoles with benzoxathiazine 2,2-dioxides is described using a quinine-derived bifunctional organocatalyst. This aza-Friedel-Crafts reaction provides 4-indolyl, 5-indolyl and 7-indolyl sulfamidate derivatives in good yields (up to 99%) and with moderate to high enantioselectivities (up to 86% ee)

Regio- and Stereoselective Synthesis of 3-Pyrazolylidene-2-oxindole Compounds by Nucleophilic Vinylic Substitution of (E)-3-(Nitromethylene)indolin-2-one

A highly regio- and stereoselective synthesis of 3-alkylidene-2-oxindoles has been described through a nucleophilic vinylic substitution (SNV) of (E)-3-(nitromethylene)indolin-2-one using pyrazol-3-ones as nucleophiles and Et3N as a base. The reaction affords selectively the Z-isomer when pyrazol-3-ones without substituents at the 4 position are used. While the reaction is E-selective with 4-substituted pyrazolones. The stereoselectivity (up to >20:1) and the yields (up to 98%) are very high under mild reaction conditions

Catalytic enantioselective aza-Reformatsky reaction with seven-membered cyclic imines dibenzo[b,f][1,4]oxazepines

A catalytic enantioselective aza-Reformatsky reaction is reported with cyclic dibenzo[b,f][1,4]oxazepines and ethyl iodoacetate leading to the synthesis of chiral ethyl 2-(10,11-dihydrodibenzo[b,f][1,4]oxazepin-11-yl)acetate derivatives with excellent yields and high enantioselectivities (up to 98% yield and 97 : 3 er) using a readily available diaryl prolinol L4 as the chiral ligand and Me2Zn as the zinc source under an air atmosphere. Furthermore, different transformations were carried out with the corresponding chiral β-amino esters, preserving in all cases the optical purity

Organocatalytic Enantioselective Synthesis of α-Hydroxyketones through a Friedel−Crafts Reaction of Naphthols and Activated Phenols with Aryl- and Alkylglyoxal Hydrates

An efficient organocatalytic asymmetric synthesis of α-hydroxyketones has been developed. Quinine-derived thiourea catalyzed the enantioselective Friedel−Crafts alkylation of naphthols and activated phenols with aryl- and alkylglyoxal hydrates, providing the corresponding chiral α-hydroxyketones with high yields (up to 97%) and excellent enantioselectivities (up to 99% ee)

Enantioselective alkynylation of benzo[e][1,2,3]-oxathiazine 2,2-dioxides catalysed by (R)-VAPOL-Zn complexes: synthesis of chiral propargylic cyclic sulfamidates

(R)-VAPOL-Zn(II) complexes catalysed the enantioselective addition of terminal alkynes to cyclic benzoxathiazine 2,2-dioxides, providing the corresponding chiral propargylic sulfamidates with high yields (up to 93%) and good enantiomeric excesses (up to 87%)