Search results
Results from the WOW.Com Content Network
Cosmic ray visual phenomena, or light flashes (LF), also known as Astronaut's Eye, are spontaneous flashes of light visually perceived by some astronauts outside the magnetosphere of the Earth, such as during the Apollo program.
Another possibility is a composite group, in which successive groups in the period have different numbers of flashes, e.g. "Fl. (2+1)" indicates a group of two flashes, followed by one flash. A specific case sometimes used [2] is when the flashes are longer than two seconds. Such a light is sometimes denoted "long flashing" with the ...
Photopsia is the presence of perceived flashes of light in the field of vision. It is most commonly associated with: [4] posterior vitreous detachment; migraine aura (ocular migraine / retinal migraine) migraine aura without headache; scintillating scotoma; retinal break or detachment; occipital lobe infarction (similar to occipital stroke)
The electronic flash system eventually superseded bulb guns as prices came down. Already in the early 1970s, amateur electronic flashes were available for less than $100. Two professional xenon tube flashes. A typical electronic flash unit has electronic circuitry to charge a high-capacitance capacitor to several hundred volts.
The shape properties of the light waveform (e.g. sinusoidal, rectangular pulse and its duty cycle); see Figure 1; The average light level of the light source and its contrast with the background light level within the environment; The viewing angle and changes in direction of view by the observer; Physiological factors such as age and fatigue.
Chamberlain, LiftMaster, and Craftsman have interchangeable parts, primarily the gear and circuit boards. The greatest difference between the brands is that Chamberlain and Craftsman operate on a square shaped split-rail system, while LiftMaster consists of one single solid piece of inverted t-shaped rail.
The senders had to determine if there was a need to rotate the falling blocks, but without the ability to rotate them – only the receiver was able to perform this operation. At the edges of each screen, were two icons with two flashing lights in two different frequencies, (one at 15 Hz and the other at 17 Hz).
**Military airport beacons flash alternately white and green, but are differentiated from civil beacons by two quick white flashes between the green flashes. In Class B, C, D, and E surface areas, operation of the airport beacon between sunrise and sunset often indicates that the ground visibility is less than 3 miles and/or the ceiling is less ...