Saturday, January 9, 2010

THE LION ROCK SIGIRIYA SRI LANKA


Sigiriya (Lion's rock) is an ancient rock fortress and palace ruin situated in the central Matale District of Sri Lanka, surrounded by the remains of an extensive network of gardens, reservoirs, and other
structures. A popular tourist destination, Sigiriya is also renowned for its ancient paintings (frescos),[1] which are reminiscent of the Ajanta Caves of India. The Sigiriya was built during the reign of King Kassapa I (AD 477 – 495), and it is one of the seven World Heritage Sites of Sri Lanka.[2][3]


Sigiriya may have been inhabited through prehistoric times. It was used as a rock-shelter mountain monastery from about the 5th century BC, with caves prepared and donated by devotees to the Buddhist Sangha. The garden and palace were built by King Kasyapa. Following King Kasyapa's death, it was again a monastery complex up to about the 14th century, after which it was abandoned. . The Sigiri inscriptions were deciphered by the archaeologist Senarath Paranavithana in his renowned two-volume work, published by Oxford, Sigiri Graffiti. He also wrote the popular book "Story of Sigiriya".[4]

The Mahavamsa, the ancient historical record of Sri Lanka, describes King Kasyapa as the son of King Dhatusena. Kasyapa murdered his father by walling him alive and then usurping the throne which rightfully belonged to his brother Mogallana, Dhatusena's son by the true queen. Mogallana fled to India to escape being assassinated by Kasyapa but vowed revenge. In India he raised an army with the intention of returning and retaking the throne of Sri Lanka which he considered was rightfully his. Knowing the inevitable return of Mogallana, Kasyapa is said to have built his palace on the summit of Sigiriya as a fortress and pleasure palace. Mogallana finally arrived and declared war. During the battle Kasyapa's armies abandoned him and he committed suicide by falling on his sword. Chronicles and lore say that the battle-elephant on which Kasyapa was mounted changed course to take a strategic advantage, but the army misinterpreted the movement as the King having opted to retreat, prompting the army to abandon the king altogether. Moggallana returned the capital to Anuradapura, converting Sigiriya into a monastery complex.

Alternative stories have the primary builder of Sigiriya as King Dhatusena, with Kasyapa finishing the work in honour of his father. Still other stories have Kasyapa as a playboy king, with Sigiriya a pleasure palace. Even Kasyapa's eventual fate is mutable. In some versions he is assassinated by poison administered by a concubine. In others he cuts his own throat when isolated in his final battle.

VIDEO

WATCH CAR SENSOR VIDEO

Wednesday, October 21, 2009

CAR SENSOR





Every new car, and most cars produced after 1980, have an oxygen sensor. The sensor is part of the emissions control system and feeds data to the­ engine management computer. The goal of the sensor is to help the engine run as efficiently as possible and also to produce as few emissions as possible.


gasoline engine burns gasoline in the presence of oxygen (see How Car Engines Work for complete details). It turns out that there is a particular ratio of air and gasoline that is "perfect," and that ratio is 14.7:1 (different fuels have different perfect ratios -- the ratio depends on the amount of hydrogen and carbon found in a given amount of fuel). If there is less air than this perfect ratio, then there will be fuel left over after combustion. This is called a rich mixture. Rich mixtures are bad because the unburned fuel creates pollution. If there is more air than this perfect ratio, then there is excess oxygen. This is called a lean mixture. A lean mixture tends to produce more nitrogen-oxide pollutants, and, in some cases, it can cause poor performance and even engine damage.


­Th­e oxygen sensor is positioned in the exhaust pipe and can detect rich and lean mixtures. The mechanism in most sensors involves a chemical reaction that generates a voltage (see the patents below for details). The engine's computer looks at the voltage to determine if the mixture is rich or lean, and adjusts the amount of fuel entering the engine accordingly.
The reason why the engine needs the oxygen sensor is because the amount of oxygen that the engine can pull in depends on all sorts of things, such as the altitude, the temperature of the air, the temperature of the engine, the barometric pressure, the load on the engine, etc.
When the oxygen sensor fails, the computer can no longer sense the air/fuel ratio, so it ends up guessing. Your car performs poorly and uses more fuel than it needs to.