Search results for "Luminance"

Long-Living Light-Emitting Electrochemical Cells - Control through Supramolecular Interactions

2008

Light-emitting electrochemical cells with lifetimes surpassing 3000 hours at an average luminance of 200 cd m(-2) are obtained with an ionic iridium(III) complex conveniently designed to form a supramolecularly caged structure.

Photoluminescent Road Coatings for Open-Graded and Dense-Graded Asphalts: Theoretical and Experimental Investigation

2018

AbstractRoad safety builds on traffic and driver–infrastructure interaction: nighttime visibility represents a key-aspect of this complex interaction. Therefore, providing an adequate road lighting...

Low Current Density Driving Leads to Efficient, Bright and Stable Green Electroluminescence

2013

Electroluminescent devices have the potential to reshape lighting and display technologies by providing low-energy consuming solutions with great aesthetic features, such as flexibility and transparency. In particular, light-emitting electrochemical cells (LECs) are among the simplest electro-luminescent devices. The device operates with air-stable materials and the active layer can be resumed to an ionic phosphorescent emitter. As a consequence, LECs can be assembled using solution-process technologies, which could allow for low-cost and large-area lighting applications in the future. High efficiencies have been reported at rather low luminances (<50 cd m(-2)) and at very low current densi…

Improving the Turn-On Time of Light-Emitting Electrochemical Cells without Sacrificing their Stability

2010

The luminance, efficiency, and turn-on time of ionic iridium complex-based light-emitting electrochemical cells can be improved by inserting an ionic liquid with high intrinsic conductivity. This results in a device in which the decrease in turn-on time is achieved while maintaining the stability.

Controlling the dynamic behavior of light emitting electrochemical cells

2013

Abstract Light emitting electrochemical cells (LECs) present an attractive route towards cost efficient lighting applications. By utilizing ionic phosphorescent transition metal complexes, efficient electroluminescence can be realized from a single layer device using air stable electrodes. These devices achieve efficient charge carrier injection due to ion accumulation at the interface upon driving, resulting in a dynamic response upon device operation. Here we investigate the device operation by using fast current and luminance versus voltage sweeps during normal fixed bias operating. A universal set of JL–V curves can be identified in which different regimes are observable. The speed and …

Changes in the objective amplitude of accommodation with pupil size.

2014

PURPOSE We evaluate the effect of pupil size on objectively measured amplitude of accommodation (AA). METHODS Pupil diameter and wavefront aberrometry were obtained in 15 eyes when stimulus swept across the range of clear vision in steps of 0.5 diopters. Wavefront refraction techniques were used to compute objective AA as the maximum refractive change. Measurements were obtained monocularly under low and high ambient room lighting conditions with a fixed luminance of the fixation target. Amplitude of accommodation computations were performed taking into account just paraxial rays (paraxial AA) or including the effects of the change of spherical aberration during accommodation (minRMS AA). R…

Complete Measurement of the Λ Electromagnetic Form Factors.

2019

The exclusive process e+e−→ΛΛ¯, with Λ→pπ− and Λ¯→p¯π+, has been studied at s=2.396 GeV for measurement of the timelike Λ electric and magnetic form factors, GE and GM. A data sample, corresponding to an integrated luminosity of 66.9 pb−1, was collected with the BESIII detector for this purpose. A multidimensional analysis with a complete decomposition of the spin structure of the reaction enables a determination of the modulus of the ratio R=|GE/GM| and, for the first time for any baryon, the relative phase ΔΦ=ΦE−ΦM. The resulting values are R=0.96±0.14(stat)±0.02(syst) and ΔΦ=37°±12°(stat)±6°(syst), respectively. These are obtained using the recently established and most precise value of …

2018

Previous studies have reported that bright ceilings appear higher than dark ceilings, irrespective of the other colorimetric properties of the ceiling color (hue, saturation) and irrespective of the luminance of the remaining room surfaces (walls, floor). In the present study, we expand these findings to width and depth estimates. We presented stereoscopic full-scale room simulations on a head-mounted display and varied the luminance of the side walls, rear wall, and ceiling independently of each other. Participants judged the width and depth of the simulated rooms. Our results show that the perceived spatial layout of a given room is significantly influenced by the luminance of the direct …

2015

We examined the effects of spatial frequency similarity and dissimilarity on human contour integration under various conditions of uncertainty. Participants performed a temporal 2AFC contour detection task. Spatial frequency jitter up to 3.0 octaves was applied either to background elements, or to contour and background elements, or to none of both. Results converge on four major findings. (1) Contours defined by spatial frequency similarity alone are only scarcely visible, suggesting the absence of specialized cortical routines for shape detection based on spatial frequency similarity. (2) When orientation collinearity and spatial frequency similarity are combined along a contour, performa…

A Neural Network-Based Algorithm for 3D Multispectral Scanning Applied to Multimedia

2005

We describe a new stereoscopic system based on a multispectral camera and an LCD-Projector. The novel concept we want to show consists in the use of multispectral information for 3D-scenes reconstruction. Each 3D point is linked to a curve representing the spectral reflectance. This latter is a physical representation of the matter and presents the advantage over color information, which is perceptual, that it is independent from both illuminant and observer. We first present an easy methodology to geometrically and spectrally calibrate such a system. We then describe an algorithm for recovering 3D coordinates based on triangulation and an algorithm for reflectance curves reconstruction bas…