LED degradation: From component to system

Human civilization revolves around artificial light. Since its earliest incarnation as firelight to its most recent as electric light, artificial light is at the core of our existence. It has freed us from the temporal and spatial constraints of daylight by allowing us to function equally well night and day, indoors and outdoors. It evolved from...

Spatial conductivity mapping of unprotected and capped black phosphorus using microwave microscopy

Thin layers of black phosphorus present an ideal combination of a 2Dmaterial with a tunable direct bandgap and high carrier mobility. However the material suffers from degradation in ambient conditions due to an oxidation reaction which involves water, oxygen and light. Wehave measured the spatial profile of the conductivity on flakes of...

Influence of the alkali-silica reaction on the mechanical degradation of concrete

The alkali-silica reaction (ASR) is an important problem that has yet to be completely understood. Owing to the complexity of this<br/>phenomenon, a number of studies have been conducted to characterize its kinetics, its impact on the material, and its structural consequences.<br/>This paper focuses on the deteriorating impact of ASR on concrete...

Deep convolutional neural networks for detection of rail surface defects

In this paper, we propose a deep convolutional neural network solution to the analysis of image data for the detection of rail surface defects. The images are obtained from many hours of automated video recordings. This huge amount of data makes it impossible to manually inspect the images and detect rail surface defects. Therefore, automated...

Lumen maintenance predictions for LED packages

Commercial claims for LED-based products in terms of lumen maintenance are fully based on TM-21 extrapolations using LM-80 data. This paper indicates that there may be a risk in doing this as TM-21 only relies on the behavior of the average LED degradation, instead of taking into account the degradation of all individual LEDs. Therefore, we...