Monday, April 30, 2007


A door is a makeup in a wall that allows easy transformation between an opening and a closed wall. It is establish in many houses and other buildings: internal ones, doors giving access to the street/external world, and doors to private outdoor areas such as a garden or balcony. In an apartment building, an midway kind is the outer door of an apartment, inside the building.
The first records are those represented in the paintings of the Egyptian tombs, in which they are shown as single or double doors, each in a single piece of wood. In Egypt, where the climate is intensely dry, there would be no fear of their warping, but in other countries it would be necessary to frame them, which according to Vitruvius was done with stiles and rails: the spaces enclosed being filled with panels let into grooves made in the stiles and rails. The stiles were the vertical boards, one of which, tenoned or hinged, is known as the hanging stile, the other as the middle or meeting stile. The horizontal cross pieces are the top rail, bottom rail, and middle or intermediate rails. The most ancient doors were in timber, those made for King Solomon's temple being in olive wood, which were fixed and overlaid with gold. The doors dwelt upon in Homer would appear to have been cased in silver or brass. Besides Olive wood, elm, cedar, oak and cypress were used.

All ancient doors were hung by pivots at the top and bottom of the hanging stile which worked in sockets in the lintel and cill, the final being always in some hard stone such as basalt or granite. Those found at Nippur by Dr. Hilprecht, dating from 2000 B.C. were in dolorite. The tenons of the gates at Balawat were covered with bronze. These doors or gates were hung in two leaves, each about 8 ft.4 in. wide and 27 ft. high; they were enclosed with bronze bands or strips, 10 in. high, covered with repouss embellishment of figures, etc. The wood doors would seem to have been about 3 in. thick, but the hanging stile was over 14 inches diameter. Other sheathings of various sizes in bust have been found, which proves this to have been the universal method adopted to protect the wood pivots. In the Hauran in Syria, where timber is scarce the doors were made in stone, and one measuring 5 ft. 4 in. by 2 ft. 7 in. is in the British Museum; the band on the meeting stile shows that it was one of the leaves of a double door. At Kuffeir near Bostra in Syria, Burckhardt found stone doors, 9 to 10 ft. high, being the entrance doors of the town. In Etruria many stone doors are referred to by Dennis.

Tuesday, April 24, 2007

Northern Mockingbird

The Northern Mockingbird, Mimus polyglottos, is the mockingbird commonly originate in North America.Adults are grey on the head and upperparts with pale yellow eyes and a slim black bill with a slight downward curve; the underparts are light. They have a long dark tail by means of white edges and long dark legs. They have white wing bars and show white wing patches in flight.Their breeding habitat is areas with a mix of open areas and dense shrubs from southern Canada to Mexico, but is most common in the southern United States. They build a twig nest in a dense shrub or tree. This bird forcefully defends its nest against other birds and animals, including humans. When a predator is persistent mockingbirds from adjacent territories, summoned by a distinct call, may join the attack. Other birds may gather to watch as the mockingbirds harass the intruder.
They are usually permanent residents; northern birds may move south during harsh weather. However, this species has occurred in Europe as an extreme rarity.These birds forage on the ground or in vegetation; they also fly down from a perch to capture food. They mainly eat insects and berries. While foraging they will regularly spread their wings in a peculiar two-step motion to display the white patches underneath. The purpose of this behavior is disputed. Some ornithologists claim this is merely a territorial display, while others say that flashing the white patches startles hiding insects and forces them into the open. Both theories seem to have some merit.
This bird imitates the calls of other birds, animal sounds and yet machine noises. It is often found in urban areas. They often call through the night and may continue year-round apart from for the summer moulting season. Mockingbirds usually sing the loudest in the twilight of the early morning when the sun is on the horizon. While singing on a high perch they will often bolt more than a few feet into the air in a looping motion, with wings outstretched to display their white underside, then land back on the perch without breaking a note. That serves as a territorial display.Mockingbirds have a strong preference for certain trees, such as maple, sweet gum (green 5-pointed leaves and prickly porous balls), and sycamore. They normally avoid pine trees. In urban areas, mockingbirds rarely come down to the ground, unlike most birds. Also, they have a particular preference for high places, such as the topmost branches of trees and the tops of telephone poles.

Wednesday, April 18, 2007

Radio clock

A radio clock is a clock that is synchronized by a time code bit stream transmitted by a radio transmitter associated to a time standard such as an atomic clock. The picture shows a type of radio controlled digital clock. With special mechanism, radio controlled analog clocks are also available.
A radio controlled clock consists of an antenna for intercepting the RF time code signal, a receiving circuit to exchange the time code RF signal into digital time code, and a controller circuit to decode the time code bit streams and to drive an output circuit which can be LCD in case of digital clocks or stepping motors in case of analog clocks.

Tuesday, April 10, 2007

Satellite phone

A satellite telephone, satellite phone, or satphone is a mobile phone that communicates directly with orbiting communications satellites. Depending on the architecture of a particular system, coverage may comprise the entire Earth, or only specific regions.
Satellite phone (Inmarsat)The mobile equipment, also known as a terminal or earth station, varies generally. A satellite phone handset has a size and weight comparable to that of a late 1980s or early 1990s cell phone, but with a large retractable antenna. These are popular on expeditions into remote areas where terrestrial cellular service is unavailable.
A fixed installation, such as used shipboard, may include large, rugged, rack-mounted electronics, and a steerable microwave antenna on the mast that mechanically tracks the overhead satellites.

Friday, April 06, 2007


A smartphone is any electronic handheld device that integrates the functionality of a mobile phone, personal digital assistant or other information appliance. This is frequently achieved by adding telephone functions to an existing PDA or putting "smart" capabilities, such as PDA functions, into a mobile phone. A key characteristic of a smartphone is that additional applications can be installed on the device. The applications can be developed by the manufacturer of the handheld device, by the operator or by any other third-party software developer.
It is increasingly difficult to define exactly what qualifies as a smartphone. Almost all new mobile phones have some rudimentary PDA functionality such as phonebooks, calendars, and task lists. Furthermore, BREW and Java ME devices allow for the installation of additional applications but are still not considered smartphones. There are many BREW devices with PDA functionality, the ability to run third-party applications in native code and sporting displays as large as 240x320 pixels; yet they are not considered smartphones. The elusive definition seems loosely tied to the particular operating systems listed below.

Monday, April 02, 2007


The Sun is the star at the centre of our Solar system. It is infrequently referred to as Sol to distinguish it from other "suns". Planet Earth orbits the Sun, as do many other bodies, with other planets, asteroids, meteoroids, comets and dust. Its heat and light support almost all life on Earth.
The Sun has a mass of about 2×1030kg, which is fairly higher than that of an average star. About 74% of its mass is hydrogen, with 25% helium and the rest made up of trace quantities of heavier elements. It is consideration that the Sun is about 5 billion years old, and is about half way through its main sequence evolution, throughout which nuclear fusion reactions in its core fuse hydrogen into helium. In about 5 billion years time the Sun will become a planetary nebula.
Although it is the nearest star to Earth and has been intensively studied by scientists, many questions about the Sun remain unanswered, such as why its outer atmosphere has a temperature of over 106 K when its visible surface has a temperature of just 6,000 K.