Space Shuttle

Perşembe, Nisan 23, 2009 · Kategori: Teknoloji





NASA's Space Shuttle, officially called the Space Transportation System (STS), is the spacecraft currently used by the United States government for its human spaceflight missions and is scheduled to be retired from service in 2010. At launch, it consists of a rust-colored external tank (ET), two white, slender Solid Rocket Boosters (SRBs), and the orbiter, a winged spaceplane which is the space shuttle in the narrowest sense.

The orbiter carries astronauts and payload such as satellites or space station parts into low earth orbit, into the Earth's upper atmosphere or thermosphere.[1] Usually, five to seven crew members ride in the orbiter. The payload capacity is 22,700 kilograms (50,000 lb). When the orbiter's mission is complete it fires its Orbital Maneuvering System (OMS) thrusters to drop out of orbit and re-enters the lower atmosphere.[1] During the descent, the shuttle orbiter decelerates from hypersonic speed primarily by aerobraking and then for the landing phase it acts as a glider, making a completely unpowered ("deadstick") landing.

[edit] Technical data

Space Shuttle Atlantis transported by a Boeing 747 Shuttle Carrier Aircraft (SCA), 1998 (NASA).
Space Shuttle Endeavour being transported by a Boeing 747.
Space Shuttle Orbiter and Soyuz-TM (drawn to scale).
An overhead view of Atlantis as it sits atop the Mobile Launcher Platform (MLP) before STS-79. Two Tail Service Masts (TSMs) to either side of the orbiter's tail provide umbilical connections for propellant loading and electrical power.
Water is released onto the mobile launcher platform on Launch Pad 39A at the start of a rare sound suppression system test in 2004. During launch, 300,000 US gallons (1,100 m³) are poured onto the pad in only 41 seconds.

Orbiter specifications[13] (for Endeavour, OV-105)

  • Length: 122.17 ft (37.24 m)
  • Wingspan: 78.06 ft (23.79 m)
  • Height: 58.58 ft (17.86 m)
  • Empty weight: 172,000 lb (78,000 kg)[14]
  • Gross liftoff weight: 240,000 pounds (110,000 kg)
  • Maximum landing weight: 230,000 pounds (100,000 kg)
  • Main engines: Three Rocketdyne Block IIA SSMEs, each with a sea level thrust of 393,800 lbf (1.752 MN) at 104% power
  • Maximum payload: 55,250 lb (25,060 kg)
  • Payload bay dimensions: 15 ft (4.6 m) by 59 ft (18.0 m)
  • Operational altitude: 100 to 520 nmi (185 to 960 km)
  • Speed: 7,743 m/s (27,875 km/h, 25,404 ft/s, 17,321 mi/h)
  • Crossrange: 2,009 km (1,085 nmi)
  • Crew: Varies. The earliest shuttle flights had the minimum crew of two; many later missions a crew of five. Today, typically seven people fly (commander, pilot, several mission specialists, and rarely a flight engineer). On two occasions, eight astronauts have flown (STS-61-A, STS-71). Eleven people could be accommodated in an emergency mission (see STS-3xx).

External tank specifications (for SLWT)

  • Length: 46.9 metres (154 ft)
  • Diameter: 8.4 metres (28 ft)
  • Propellant volume: 2,025 cubic metres (535,000 US gal)
  • Empty weight: 26,535 kg (58,500 lb)
  • Gross liftoff weight: 756,000 kilograms (1,670,000 lb)

Solid Rocket Booster specifications

  • Length: 45.6 m (149.6 ft)
  • Diameter: 3.7 m (12.14 ft)
  • Empty weight (per booster): 63,272 kg (139,491 lb)
  • Gross liftoff weight (per booster): 590,000 kg (1.3 million lb)
  • Thrust (sea level, liftoff): 12.5 MN (2.8 million lbf)

System Stack specifications

  • Height: 56 m (183.7 ft)
  • Gross liftoff weight: 2 million kg (4.5 million lb)
  • Total liftoff thrust: 30.16 MN (6.781 million lbf)

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DDR-2 information

Perşembe, Nisan 23, 2009 · Kategori: Teknoloji

File:1GB DDR2 SO-DIMM.png

File:High Performance RAM.jpg

DDR2 SDRAM is a double data rate synchronous dynamic random access memory technology. It supersedes the original DDR SDRAM specification and the two are not compatible. The primary improvement that DDR2 brings over its predecessor is the operation of the external data bus at twice the clock rate. This is achieved by operating the memory cells at half the clock rate (one quarter of the data transfer rate), rather than at the clock rate as in the original DDR. Consequently, DDR2 memory operating at the same external data bus clock rate as DDR will provide the same bandwidth but with higher latency, resulting in inferior performance. Alternatively, DDR2 memory operating at twice the external data bus clock rate as DDR may provide twice the bandwidth with the same latency (in nanoseconds).

Standard nameMemory clockCycle timeI/O Bus clockData transfers per secondModule namePeak transfer rateTimings[2][3]
DDR2-400100 MHz10 ns200 MHz400 MillionPC2-32003200 MB/s3-3-3
4-4-4
DDR2-533133 MHz7.5 ns266 MHz533 MillionPC2-4200
PC2-43001		4266 MB/s3-3-3
4-4-4
DDR2-667166 MHz6 ns333 MHz667 MillionPC2-5300
PC2-54001		5333 MB/s4-4-4
5-5-5
DDR2-800200 MHz5 ns400 MHz800 MillionPC2-64006400 MB/s4-4-4
5-5-5
6-6-6
DDR2-1066266 MHz3.75 ns533 MHz1066 MillionPC2-8500
PC2-86001		8533 MB/s6-6-6
7-7-7

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Atatürk Airport

Salı, Nisan 21, 2009 · Kategori: Teknoloji

 








Istanbul's Atatürk International Airport (IST) at Yesilyurt, 23 km (14 miles) west of Sultanahmet Square, is the busiest of Turkey's major airports.

It's the place most visitors land first. (Here's visa info. Here's info on transport to/from the airport.)

The modern International Terminal Dis Hatlar Terminali) is spacious and efficient, with all the expected services including ATMs (cash machines) from which you can obtain Turkish Liras, currency exchange offices, restaurants, cafes and shops, Emanet (Baggage Check, Left Luggage) and an Airport Hotel.

Note that prices for food and drink at Turkish airports tend to be very high. My quick informal survey showed them to be 40% higher than at expensive Frankfurt Airport, and twice as high as at pricey Paris-Charles de Gaulle Airport.

Here's information on Atatürk Airport Lost and Found, if you've lost or forgotten something in the airport or on an airplane.

An underground passage (15-minute walk) connects the International Terminal with the older Domestic Terminal (Iç Hatlar Terminali) and also the Istanbul Metro, called the Hafif Metro ("Light rail system") on many airport terminal signs.

There are several ways to travel between Atatürk Airport and the city center. Here they are.

A half-dozen hotels are within a few km of the airport, and one is right within the International terminal itself. More...

Istanbul's other airport is Sabiha Gökçen International Airport (SAW) on the Asian side of the Bosphorus, about 55 km (34 miles) east of Atatürk International Airport (IST). Here's how to travel from Atatürk Airport to Sabiha Gökçen Airport.

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SULTAN AHMET MOSQUE (THE BLUE MOSQUE)

Salı, Nisan 21, 2009 · Kategori: Tarihce

        
 

 


One of the most famous monuments of Turkish and Islamic art, the mosque is visited by all who come to Istanbul and gains their admiration.

This imperial mosque is an example of classical Turkish architecture, and it is the only mosque that was originally built with six minarets.

It is surrounded by other important edifices of Istanbul, built at earlier ages. Istanbul is viewed best from the sea and the mosque is part of this magnificent scenery.

Although it is popularly known as the Blue Mosque, its real name is Sultan Ahmet Mosque. Befitting his original profession, its architect Mehmet Aga decorated the interior fastidiously like a jeweler. Built between 1609-1616, the mosque used to be part of a large complex, including a covered bazaar, Turkish baths, public kitchens, a hospital, schools, a caravanserai, and the mausoleum of Sultan Ahmet. Some of these social and cultural buildings have not survived to our day.

The architect was a student of Sinan, the greatest architect of classical Turkish architecture. He applied a plan used previously by his master, but on a larger scale.

The main entrance to Sultan Ahmet Mosque is on the Hippodrome side. There is an outer courtyard, and the inner courtyard and the edifice itself are elevated.

From the gate opening to the inner courtyard one can view the domes, rising above one another in perfect harmony, over the symbolic ablution fountain in the middle and the surrounding porticoes.

There are three entrances to the mosque interior. The wealthy and colorful vista inside created by the paintings, tiles and stained glass complements the exterior view. The interior has a centralized plan; the main and side domes rise on four large columns that support broad and pointed arches. The walls of the galleries surrounding the three sides of the interior chamber are decorated by over 20,000 exquisite Iznik tiles. The areas above the tiles and the inside of the domes are decorated with paintwork.

The blue of the paintwork, which gives the mosque its name, was not the color of the decorations originally; they were painted blue during later restorations. During the last renovation, completed in 1990, the darker blue color of the interior decorations painted as its original light colors.

The floor is covered by carpets, as in all mosques. Next to the mihrab (niche aligned towards Mecca) opposite the main entrance, there is a marble minber (pulpit) with exquisite marble work. On the other side is the sultan's loge (box) in the form of a balcony. The 260 windows flood with light the interior space, which is covered by a dome 23.5 m in diameter and 43 m high.

The small market building, repaired and reconstructed in recent years, is situated to the east of the mosque, and the single-domed mausoleum of Sultan Ahmet and the medrese (religious school) building are to the north, on the Hagia Sophia side.

In summer months light and sound shows are organized in the park here. Sultan Ahmet Mosque occupies a focal point in city tours, together with the numerous monumental buildings and museums in the vicinity.

The minarets of the mosque are classical examples of Turkish architecture. The balconies are reached by spiral stairs. It is from these balconies that five times a day the believers are called to prayer - in our day using loudspeakers.

The domes and the minarets are covered by lead, and at the top of the minarets there are standards made of gold-plated copper. Master craftsmen repair these coverings very skillfully when needed.

Islam requires all Muslims to pray five times a day. When the believers hear the call to prayer from the minarets, they perform their ablutions (washing) and then pray. The noon prayer on Fridays and the prayers on other important holidays are performed in the mosques collectively, but other prayers can be performed anywhere.

In the communal prayers performed in the mosque, the imam takes the lead and he chants verses from the Koran. The areas of prayer for men and women are separate. In the central area only men are allowed to pray, while women take their places either behind them or in the galleries.

It is a characteristic of classical Turkish mosques that even in the most crowded day, the majority of the congregation can easily see the mihrab.

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Eurofighter

Salı, Nisan 21, 2009 · Kategori: Teknoloji



             

The eurofighter typhoon provides the operators with a multi-role combat aircraft, capable of being deployed in the full spectrum of air operations, from air policing, to peace support, through to high intensity conflict.

This highly capable and extremely agile aircraft is powered by twin turbofans which power the higly capable aircraft up to Mach 2 and 65,000ft. The airframe is largely constructed of carbon fibre composites and light alloys to save weight while the aircraft is equipped with the advanced ECR90 radar, which can track multiple targets at long range. The pilot can carry out many functions by voice command while aircraft manoeuvre; weapon and defensive aid deployment is done through a combined stick and throttle. All of these innovations dramatically simplify operation of the aircraft in combat. Combined with an advanced cockpit that is fully compatible with night-vision goggles, the pilot is superbly equipped for air combat.

Initial production aircraft of the F2 standard will be deployed primarily as air-superiority fighters, but will quickly be equipped with a potent precision ground-attack capability. Armament will include the long-range Advanced Medium Range Air-to-Air Missile (AMRAAM), the UK-developed Advanced Short Range Air-to-Air Missile (ASRAAM) and various air-to-ground weapons.

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