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Flicker (light)
In visual perception, flicker is a human-visible change in luminance of an illuminated surface or light source which can be due to fluctuations of the light source itself, or due to external causes such as due to rapid fluctuations in the voltage of the power supply (power-line flicker) or incompatibility with an external dimmer. Twinkling, also called scintillation, is a generic term for variations in apparent brightness, colour, or position of a distant luminous object viewed through a medium. Flicker exists for other organisms having different perceptual thresholds. Light meters and image sensors can potentially detect flicker at much higher frequency bands than human vision. Shutter speeds used in motion photography can interact with high frequency flicker to produce visual artifacts in the captured imagery that betray flicker that would not otherwise be noted. The spectral sensitivity of the human eye to flicker depends upon the mode of visual perception. Due to the flicker ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Visual Perception
Visual perception is the ability to detect light and use it to form an image of the surrounding Biophysical environment, environment. Photodetection without image formation is classified as ''light sensing''. In most vertebrates, visual perception can be enabled by photopic vision (daytime vision) or scotopic vision (night vision), with most vertebrates having both. Visual perception detects light (photons) in the visible spectrum reflected by objects in the environment or emitted by light sources. The light, visible range of light is defined by what is readily perceptible to humans, though the visual perception of non-humans often extends beyond the visual spectrum. The resulting perception is also known as vision, sight, or eyesight (adjectives ''visual'', ''optical'', and ''ocular'', respectively). The various physiological components involved in vision are referred to collectively as the visual system, and are the focus of much research in linguistics, psychology, cognitive s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phantom Array
The flicker fusion threshold, also known as critical flicker frequency or flicker fusion rate, is the frequency at which a flickering light appears steady to the average human observer. It is a concept studied in vision science, more specifically in the psychophysics of visual perception. A traditional term for "flicker fusion" is "persistence of vision", but this has also been used to describe positive afterimages or motion blur. Although flicker can be detected for many waveforms representing time-variant fluctuations of intensity, it is conventionally, and most easily, studied in terms of sinusoidal modulation of intensity. There are seven parameters that determine the ability to detect the flicker: # the frequency of the modulation; # the amplitude or depth of the modulation (i.e., what is the maximum percent decrease in the illumination intensity from its peak value); # the average (or maximum—these can be inter-converted if modulation depth is known) illumination intens ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Persistence Of Vision
Persistence of vision is the optical illusion that occurs when the visual perception of an object does not cease for some time after the Light ray, rays of light proceeding from it have ceased to enter the eye. The illusion has also been described as "retinal persistence", "persistence of impressions", simply "persistence" and other variations. A very commonly given example of the phenomenon is the apparent fiery trail of a glowing coal or burning stick while it is whirled around in the dark. In recent theories about iconic memory, visual sensory memory, higher-level (cortical) informational persistence is considered a more relevant component of normal vision than the lower-level aspect of visible persistence. Many explanations of the illusion actually seem to describe Afterimage#Positive afterimages, positive afterimages and the neurological effect can be compared to the technological effect of motion blur in photography (or in film and video). "Persistence of vision" can a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MATLAB
MATLAB (an abbreviation of "MATrix LABoratory") is a proprietary multi-paradigm programming language and numeric computing environment developed by MathWorks. MATLAB allows matrix manipulations, plotting of functions and data, implementation of algorithms, creation of user interfaces, and interfacing with programs written in other languages. Although MATLAB is intended primarily for numeric computing, an optional toolbox uses the MuPAD symbolic engine allowing access to symbolic computing abilities. An additional package, Simulink, adds graphical multi-domain simulation and model-based design for dynamic and embedded systems. , MATLAB has more than four million users worldwide. They come from various backgrounds of engineering, science, and economics. , more than 5000 global colleges and universities use MATLAB to support instruction and research. History Origins MATLAB was invented by mathematician and computer programmer Cleve Moler. The idea for MATLAB was base ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Power Quality
Electric power quality is the degree to which the voltage, frequency, and waveform of a power supply system conform to established specifications. Good power quality can be defined as a steady supply voltage that stays within the prescribed range, steady AC frequency close to the rated value, and smooth voltage curve waveform (which resembles a sine wave). In general, it is useful to consider power quality as the compatibility between what comes out of an electric outlet and the load that is plugged into it. The term is used to describe electric power that drives an electrical load and the load's ability to function properly. Without the proper power, an electrical device (or load) may malfunction, fail prematurely or not operate at all. There are many ways in which electric power can be of poor quality, and many more causes of such poor quality power. The electric power industry comprises electricity generation (AC power), electric power transmission and ultimately electric power ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Electrotechnical Commission
The International Electrotechnical Commission (IEC; ) is an international standards organization that prepares and publishes international standards for all electrical, electronics, electronic and related technologies. IEC standards cover a vast range of technologies from power generation, transmission and distribution to home appliances and office equipment, semiconductors, fibre optics, batteries, solar energy, nanotechnology, and marine energy, as well as many others. The IEC also manages four global conformity assessment systems that certify whether equipment, system or components conform to its international standards. All electrotechnologies are covered by IEC Standards, including energy production and distribution, electronics, magnetics and electromagnetics, electroacoustics, multimedia, telecommunications and medical technology, as well as associated general disciplines such as terminology and symbols, electromagnetic compatibility, measurement and performance, dependa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Queensway Tunnel
The Queensway Tunnel ( signposted as the Birkenhead Tunnel or B'head Tunnel) is a road tunnel under the River Mersey, in the north west of England, between Liverpool and Birkenhead. Locally, it is often referred to as the "old tunnel", to distinguish it from the newer Kingsway Tunnel (1971), which serves Wallasey and the M53 motorway traffic. At in length, it is the longest road tunnel in the UK. History Planning and construction The first tunnel under the River Mersey was for the Mersey Railway in 1886. The first tunnel crossing was proposed in 1825, and again in 1827. A report in 1830 rejected the road tunnel due to concerns about building damage. During the 1920s there were concerns about the long queues of cars and lorries at the Mersey Ferry terminal, so once royal assent to a parliamentary bill was received, construction of the first Mersey road tunnel started in 1925, to a design by consulting engineer Sir Basil Mott. Mott supervised the construction in association wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluorescent Lamp
A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor, to produce ultraviolet and make a phosphor coating in the lamp glow. Fluorescent lamps convert electrical energy into visible light much more efficiently than Incandescent light bulb, incandescent lamps, but are less efficient than most LED lamps. The typical luminous efficacy of fluorescent lamps is 50–100 lumens per watt, several times the efficacy of incandescent bulbs with comparable light output (e.g. the luminous efficacy of an incandescent lamp may only be 16 lm/W). Fluorescent lamp fixtures are more costly than incandescent lamps because, among other things, they require a electrical ballast, ballast to regulate Electric current, current through the lamp, but the initial cost is offset by a much lower running cost. Compact fluorescent lamps (CFL) made in the same sizes a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stage Lighting
Stage lighting is the craft of lighting as it applies to the production of theater, dance, opera, and other performance arts. Stage Lighting Design Principle and Process Several different types of stage lighting instruments are used in this discipline. theatrecrafts' Types of Lanterns. In addition to basic lighting, modern stage lighting can also include special effects, such as Laser lighting display, lasers and fog machines. People who work on stage lighting are commonly referred to as lighting technicians or lighting designers. The equipment used for stage lighting (e.g. cabling, Salt water dimmer, dimmers, lighting instruments, contro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Traffic-light Signalling And Operation
In traffic engineering, there are regional and national variations in traffic light operation. This may be in the standard traffic light sequence (such as the inclusion of a red–amber phase) or by the use of special signals (such as flashing amber or public transport signals). Flashing signals Flashing red In the United States and Canada, a flashing red light is the equivalent of a stop sign. In New Zealand, Hong Kong, and the United Kingdom, paired red/red traffic lights are often installed outside fire and ambulance stations on major roads, which, when activated by the station, flash alternately (so that at any time one red light is showing), the purpose being to cause traffic to stop for a set amount of time to allow emergency vehicles to exit their station safely. The UK also uses an amber light which precedes the flashing red lights, and these signals are also used at level crossings, airfields and lifting bridges. Flashing amber/yellow In the US, Canada, Braz ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
