Monday, September 17, 2007

Solar wind

The solar wind is a stream of charged particles which are expelled from the upper atmosphere of the sun. It consists mostly of high-energy electrons and protons that are able to get away the sun's gravity in part because of the high temperature of the corona and the high kinetic energy particles gain through a process that is not well understood at this time.

They are directly related to the solar wind, together with geomagnetic storms that can knock out power grids on Earth, auroras and the plasma tail of a comet always pointing away from the sun. While early models of the solar wind used primarily thermal energy to accelerate the material, by the 1960s it was clear that thermal hurrying alone cannot account for the high speed solar wind. Some additional acceleration mechanism is required, but is not presently known, but most likely relates to magnetic fields in the solar atmosphere. The solar wind is answerable for the overall shape of Earth's magnetosphere, and fluctuations in its speed, density, direction, and entrained magnetic field powerfully affect Earth's local space environment.

Monday, September 03, 2007

LCD

A liquid crystal display (LCD) is a thin, flat display appliance made up of any number of color or monochrome pixels arrayed in front of a light source or reflector. It is prized by engineers because it uses very little amounts of electric power, and is therefore suitable for use in battery-powered electronic devices. In color LCDs each individual pixel is separated into three cells, or subpixels, which are coloured red, green, and blue, respectively, by additional filters. Each subpixel can be controlled independently to defer thousands or millions of possible colors for each pixel. Older CRT monitors employ a similar sub pixel structures via the use of phosphors, although the analog electron beam employed in CRTs do not hit correct subpixels.
Color components may be arrayed in a range of pixel geometries, depending on the monitor's usage. If software knows which type of geometry is being used in a given LCD, this can be used to increase the evident resolution of the monitor through subpixel rendering.