A laboratory experiment was conducted to investigate the performance characteristics of the currently available highpower LEDs under various drive conditions and ambient temperatures. Light output degradation and color shift properties as a function of time were measured for five types of commercial high-flux LEDs, namely, red, green, blue, and white from one manufacturer, and a different high-...

A system for measuring the absolute spectral responsivity of solar cells is described. The system uses higher-powered LED arrays that are coupled to an optical light guide that together provide large area illumination. Two different measurement methods were developed and tested using this measurement apparatus. The first method is an individual LED lock-in technique that can be performed over a...

Computers and laptops are increasingly used at work and at home. As a consequence, the exposure of short wavelength blue light, which is emitted by LED displays, increases too. By its action, light is well-known to enact damage on the neurosensory retina, especially on the underlying structures. In particular, this happens through photothermal, photomechanical, and photochemical mechanisms. Thi...

We present a pre-cortex model of olfactory system. The odor molecules are first received at the sensory layer, where receptor neurons spatio-temporaly encode them in terms of their spiking frequencies. Neurons expressing a specific receptor project to two or more topographically fixed glomeruli in the olfactory bulb (OB) and create a sensory map. Excitatory postsynaptic potentials are formed in...

A high efficiency LED (Light Emitting Diode) driver based on Buck converter, which could operate under a wide AC input voltage range (85 V 265 V) and drive a series of high power LEDs, is presented in this paper. The operation principles, power loss factors of the LED driver in this study are analyzed and discussed in detail and some effective ways to improve efficiency are proposed through sys...

The objective of the study is to assess the implementation of LED lighting into forest machine work in the dark. In addition, the paper includes a wide variety of important and relevant safety and health parameters. In modern, computerized work in the cab of forest machines, artificial illumination is a demanding task when performing duties, such as the visual inspections of wood and computer c...

This study investigates the distortion of visual colour harmony impression in case of different types of artificial changes among the perceptual attributes of test samples. A set of visual experiments were carried out to investigate the observer’s colour harmony impression as a function of artificial distortions. The visual colour harmony impression of a colour combination appearing harmonious ...

Abstract – Modeling of the cascode switching structure used in Flyback converter for achieving fast startup in the deeply dimmed phase-cut LED driver is presented in this paper. The cascode structure’s inherent instability and oscillation issue is modeled and analyzed quantitatively. Three solutions are proposed to stabilize the structure and suppress the unstable voltage oscillation. Solutions...

We present the 3D Wand, a low-cost 3D shape acquisition device consisting of a laser line projector and LEDs. A user projects a plane of light to the measured 3D scene by the handheld 3D Wand. The projected light and the LED lights are captured with a DV camera. By estimating the 3D pose of the 3D Wand from the visual information of the LED lights, the distance to the surface lit by the laser i...