Petrol Engine

A petrol engine (known as a gasoline engine) is an internal combustion engine with spark-ignition, designed to run on petrol (gasoline) and similar volatile fuels.

It differs from a diesel engine in the method of mixing the fuel and air, and in using spark plugs to initiate the combustion process. In a diesel engine, only air is compressed (and therefore heated), and the fuel is injected into the then very hot air at the end of the compression stroke, and self-ignites. In a petrol engine, the fuel and air are usually pre-mixed before compression (although some modern petrol engines now use cylinder-direct petrol injection).

The pre-mixing was formerly done in a carburetor, but now (except in the smallest engines) it is done by electronically controlled fuel injection. Petrol engines run at higher speeds than diesels, partially due to their lighter pistons, con rods and crankshaft (as a result of lower compression ratios) and due to petrol burning faster than diesel. However the lower compression ratios of a petrol engine give a lower efficiency than a diesel engine.


Uses of Petrol Engine

Motor cars
Motorcycles
Aircraft
Motorboats
Small machines, such as lawn mowers, chainsaws and portable engine-generators


Petrol engines may run on the four-stroke cycle or the two-stroke cycle.

Read More

Devadasi - Servant of God

In Hinduism, the devadasi tradition (देवदासी / ದೇವದಾಸಿ; "servant of god") is a religious tradition in which girls are "married" and dedicated to a deity (deva or devi) or to a temple and includes performance aspects such as those that take place in the temple as well as in the courtly and mujuvani [telegu] or home context. Originally, in addition to this and taking care of the temple and performing rituals, these women learned and practiced Sadir, Odissi and other classical Indian artistic traditions and enjoyed a high social status.

During British rule, kings who were the patrons of temples and temple arts became powerless. As a result, devadasis were left without their traditional means of support and patronage. Colonial views on devadasis are hotly disputed by several groups and organizations in India and by western academics.

Recently the devadasi system has started to disappear, having been outlawed in all of India in 1988. However, devadasis still exist in India today, as shown in a 2004 report by the National Human Rights Commission of the Government of India. According to this report, "after initiation as devadasis, women migrate either to nearby towns or other far-off cities to practice prostitution" (p200). A study from 1990 recorded that 45.9% of devadasis in one particular district were prostitutes, while most of the others relied on manual labour and agriculture for their income. The practice of dedicating devadasis was declared illegal by the government of the Indian state Karnataka in 1982 and by the government of Andhra Pradesh in 1988. However as of 2006 the practice was still prevalent in around 10 districts of northern Karnataka and 14 districts in Andhra Pradesh.

Devadasis are also known by various other local terms, such as jogini. Furthermore, the devadasi practice of religious prostitution is known as basivi in Karnataka and matangi in Maharastra. It is also known as venkatasani, nailis, muralis and theradiyan. Devadasi are sometimes referred to as a caste; however, some question the accuracy of this usage. "According to the devadasis themselves there exists a devadasi 'way of life' or 'professional ethic' (vritti, murai) but not a devadasi jāti (sub-caste). Later, the office of devadasi became hereditary but it did not confer the right to work without adequate qualification" (Amrit Srinivasan, 1985). In Europe the term Bayadere (from French: bayadère, ascending to Portuguese: Balliadera, literally dancer) was occasionally used.

The Chola empire encouraged the devadasi system. Men and women were dedicated to temple service. They developed the system of music and dance employed during temple festivals.
Inscriptions reveal that the 400 dancers, their gurus and orchestras, were maintained by the Brihadeesvarar temple, Thanjavur, with munificent grants, including the daily disbursement of oil, turmeric, betel leaves and nuts.

Traditionally the young devadasi underwent a ceremony of dedication to the deity of the local temple which resembled in its ritual structure the upper caste Tamil marriage ceremony. Following this ceremony, she was set apart from her non-dedicated sisters in that she was not permitted to marry and her celibate or unmarried status was legal in customary terms. Significantly, however she was not prevented from leading a normal life involving sex with individuals of her choice and childbearing. The very rituals which marked and confirmed her incorporation into temple service also committed her to the rigorous emotional and physical training in the classical dance, her hereditary profession. In addition, they served to advertise in a perfectly open and public manner her availability for sexual liaisons with a proper patron and protector. Very often in fact, the costs of temple dedication were met by a man who wished thus to anticipate a particular devadasi's favours after she had attained puberty. It was crucially a women's 'dedicated' status which made it a symbol of social prestige and privilege to maintain her. The devadasi's sexual partner was always chosen by 'arrangement' with her mother and grandmother acting as prime movers in the veto system. Alliance with a Muslim, a Christian, or a lower caste was forbidden while a Brahmin or member of the royal elite was preferred for the good breeding and/or wealth he would bring into the family. The non-domestic nature of the contract was an understood part of the agreement with the devadasi owing the man neither any householding services nor her offspring. The children in turn could not hope to make any legal claim on the ancestral property of their father whom they met largely in their mother's home when he came to visit.

Nattuvanars were the male accompanists of the devadasi during her performance. They conducted the music orchestra while the devadasi performed her service. Inscriptions reveal that nattuvanars were used to teach the Chola princess Kuntavai a thousand years ago.
Reformists and Abolitionists conceived of the devadasi practice as a social evil and considered many Devadasi to be prostitutes. The first anti-Nautch and anti-dedication movement was launched in 1882. "Their main aim was to do away with this system. Reform lobbyists were drawn mainly from missionaries, doctors, journalists and social workers. They urged the abolition of all ceremonies and procedures by which young girls dedicated themselves as Devadasis of Hindu shrines. They organized seminars and conferences to create a public opinion against the Devadasi system. In the later part of 1892 an appeal was made to the Viceroy and Governor General of India and to the Governor of Madras. This appeal also defines the position of the anti-nautch movement".

Some journals and newspapers like The Indian Social Reformer and Lahore Purity Servant supported the Reformist or Abolitionist movement. The movement initially concentrated on building public opinion and enlisting members to refuse to attend Nautch parties as well as to refuse to invite devadasis to festivities at their homes. Around 1899, the anti-Nautch and puritan movement turned its attention to stopping dedications. The anti-Nautch movement paved the way for anti-dedication movement.

Read More

Sati - The Burning Bride

Sati is described as a Hindu custom in India in which the widow was burnt to ashes on her dead husband's pyre. Basically the custom of Sati was believed to be a voluntary Hindu act in which the woman voluntary decides to end her life with her husband after his death. But there were many incidences in which the women were forced to commit Sati, sometimes even dragged against her wish to the lighted pyre.

Though Sati is considered a Hindu custom, the women, known as Sati in Hindu religious literature, did not commit suicide on their dead husband's pyre. The first woman known as Sati was the consort of Lord Shiva. She burnt herself in fire as protest against her father who did not give her consort Shiva the respect she thought he deserved, while burning herself she prayed to reborn again as the new consort of Shiva, which she became and her name in the new incarnation was Parvati.

Other famous woman in Hindu literature titled Sati was Savitri. When Savitri's husband Satyavan died, the Lord of death, Yama arrived to take his soul. Savitri begged Yama to restore Satyavan and take her life instead, which he could not do. So Savitri followed Lord Yama a long way. After a long way in which Yama noticed that Savitri was losing strength but was still following him and her dead husband, Yama offered Savitri a boon, anything other than her husband's life. Savitri asked to have children from Satyavan. In order to give Savitri her boon, Lord Yama had no choice but to restore Satyavan to life and so Savitri gained her husband back.

These two women along with other women in Hindu mythology who were exceptionally devoted to their husbands symbolized the truthful Indian wife who would do everything for their husband and they were named Sati. The meaning of the word sati is righteous. But as written earlier the women named Sati, in Hindu religious literature, did not commit suicide on their dead husband's pyre. Therefore the custom of burning the widow on her dead husband's pyre probably did not evolve from religious background but from social background.

There are different theories about the origins of Sati. One theory says that Sati was introduced to prevent wives from poisoning their wealthy husbands and marry their real lovers. Other theory says that Sati began with a jealous queen who heard that dead kings were welcomed in heaven by hundreds of beautiful women, called Apsaras. And therefore when her husband died, she demanded to be burnt on her dead husband's pyre and so to arrive with him to heaven and this way to prevent the Apsaras from consorting with her husband. There are also other theories about the origins of Sati.

Even though Sati is considered an Indian custom or a Hindu custom it was not practiced all over India by all Hindus but only among certain communities of India. On the other hand, sacrificing the widow in her dead husband's funeral or pyre was not unique only to India. In many ancient communities it was an acceptable feature. This custom was prevalent among Egyptians, Greek, Goths, Scythians and others. Among these communities it was a custom to bury the dead king with his mistresses or wives, servants and other things so that they could continue to serve him in the next world.

Another theory claims that Sati was probably brought to India by the Scythians invaders of India. When these Scythians arrived in India, they adopted the Indian system of funeral, which was cremating the dead. And so instead of burying their kings and his servers they started cremating their dead with his surviving lovers. The Scythians were warrior tribes and they were given a status of warrior castes in Hindu religious hierarchy. Many of the Rajput clans are believed to originate from the Scythians. Later on other castes who claimed warrior status or higher also adopted this custom.

This custom was more dominant among the warrior communities in north India, especially in Rajasthan and also among the higher castes in Bengal in east India. Among the Rajputs of Rajasthan, who gave lot of importance to valor and self sacrifice, wives and concubines of the nobles even committed suicide, when they came to know that their beloved died in battlefield. In other parts of India it was comparatively low. And among the majority of Indian communities it did not exist at all.

A few rulers of India tried to ban this custom. The Mughals tried to ban it. The British, due to the efforts of Hindu reformers like Raja Ram Mohan Roy outlawed this custom in 1829.

There aren't exact figures about the number of Sati incidences. In general, before this custom was outlawed in 1829, there were a few hundred officially recorded incidences each year. Even after the custom was outlawed, this custom did not vanish completely. It took few decades before this custom almost vanished. But still there are rare incidences in which the widow demands to voluntary commit Sati. In 1987 an eighteen years old widow committed Sati in a village of Rajasthan with the blessing of her family members. In this incidence the villagers took part in the ceremony, praising and supporting the widow for her act. In October 1999 a woman hysterically jumped on her husband's pyre surprising everyone. But this incidence was declared suicide and not Sati, because this woman was not compelled, forced or praised to commit this act.

In different communities of India, Sati was performed for different reasons and different manners. In communities where the man was married to one wife, the wife put an end to her life on the pyre. But even in these communities not all widows committed Sati. Those women who committed Sati were highly honored and their families were given lot of respect. It was believed that the woman who committed Sati blessed her family for seven generations after her. Temples or other religious shrines were built to honor the Sati.

In communities were the ruler was married to more than one wife; in some cases only one wife was allowed to commit Sati. This wife was normally the preferred wife of the husband. This was some kind of honor for the chosen wife and some kind of disgrace for the other wives. In other communities some or all of the wives and mistresses were immolated with the husband. And in some cases even male servants were immolated with the kings. This kind of Sati in which the wives and servants were treated as the ruler's property intensifies the theory that Sati was introduced to India by the Scythian invaders of India.

In some very rare incidences mothers committed Sati on their son's pyre and in even more rare cases husbands committed Sati on their wives pyres.

Read More

Know More

What is a Mexican stand-off?

A Mexican stand-off is a confrontation between two or more opponents in which nobody wins. It is considered to be a more dangerous situation than a stalemate. A classical Mexican stand-off occurs when 3 men stand pointing guns at each other.
The man who shoots first will be shot by the others. Nobody wants to shoot for fear of being shot at in return but nobody wants to give up his weapon for fear of being shot. The term is though to have originated in the late 19th century.

Read More

Printing

Printing is a process for reproducing text and image, typically with ink on paper using a printing press. It is often carried out as a large-scale industrial process, and is an essential part of publishing and transaction printing.

The development of printing was preceded by the use of cylinder seals in Mesopotamia developed in 3500 BC, and other related stamp seals. The earliest form of printing was woodblock printing, with existing examples from China dating to before 220 AD and Egypt to the 4th century. Later developments in printing include the movable type, first developed by Bi Sheng in China, and the printing press, a more efficient printing process developed by Johannes Gutenberg in the 15th century.

Read More

Titanic

RMS Titanic was a passenger liner that struck an iceberg on her maiden voyage from Southampton, England, to New York City, and sank on 15 April 1912. She hit the iceberg four days into the crossing, at 11:40 pm on 14 April 1912, and sank at 2:20 am the following morning, resulting in the deaths of 1,517 people in one of the deadliest peacetime maritime disasters in history.

The largest passenger steamship in the world, the Olympic-class RMS Titanic was owned by the White Star Line and constructed at the Harland and Wolff shipyard in Belfast, Ireland. She set sail for New York City on 10 April 1912 with 2,223 people on board. The high casualty rate resulting from the sinking was due in part to the fact that, although complying with the regulations of the time, the ship carried lifeboats for only 1,178 people. A disproportionate number of men died due to the "women and children first" protocol that was enforced by the ship's crew.

Titanic was designed by experienced engineers, using some of the most advanced technologies and extensive safety features of the time. Adding to the ironic nature of the tragedy is the fact that the liner sank on her maiden voyage. The high loss of life, the media frenzy over Titanic's famous victims, the legends about the sinking, the resulting changes in maritime law, and the discovery of the wreck have all contributed to the enduring interest in Titanic.

Titanic's hull was launched at 12:13 on 31 May 1911, and her outfitting was completed by 31 March the following year. Her length overall was 882 feet 9 inches (269.1 m), the moulded breadth 92 feet 0 inches (28.0 m), the tonnage 46,328 GRT, and the height, from the water line to the boat deck, 59 feet (18 m). She was equipped with two reciprocating four-cylinder, triple-expansion steam engines and one low-pressure Parsons turbine, each driving a propeller. There were 29 boilers fired by 159 coal burning furnaces that made possible a top speed of 23 knots (43 km/h; 26 mph). Only three of the four 62 foot (19 m) funnels were functional: the fourth, which only provided ventilation, was added to make the ship look more impressive. The ship could carry a total of 3,547 passengers and crew.

Of the two steam-powered steering engines installed, one was kept in use and one kept in reserve; the engines could be slid away and disengaged when not required. A quarter-circle rack-and-pinion drive was connected to the short tiller through stiff springs, to isolate the engines from any shocks in heavy seas or during fast changes of direction. As a last resort, the tiller could be moved by ropes connected to two steam capstans.

The Titanic's design and construction featured luxury and opulence. The First-class section had a swimming pool, a gymnasium, squash court, Turkish bath, Electric bath and a Verandah Cafe. First-class common rooms were adorned with ornate wood panelling, expensive furniture and other decorations. In addition, the Café Parisien offered cuisine for the first-class passengers, with a sunlit veranda fitted with trellis decorations. There were libraries and barber shops in both the first and second-class, while the third class general room had pine panelling and sturdy teak furniture. The ship incorporated technologically advanced features for the period, including three electric elevators in first class and one in second class. She also had an extensive electrical system powered by steam-driven generators and ship-wide wiring for electric lights and two Marconi radios. One 5,000-watt set was manned by two operators working in shifts sending and receiving passenger messages, keeping the ship in constant contact with the outside world. First-class passengers paid a hefty fee for such amenities; the most expensive one-way trans-Atlantic passage was £875(equivalent to £64,204 as of 2011), or $4,375 ($99,237 as of 2011).

Read More

DNA

Deoxyribonucleic acid or DNA, is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms. The main role of DNA molecules is the long-term storage of information. DNA is often compared to a set of blueprints, like a recipe or a code, since it contains the instructions needed to construct other components of cells, such as proteins and RNA molecules. The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in regulating the use of this genetic information.

DNA consists of two long polymers of simple units called nucleotides, with backbones made of sugars and phosphate groups joined by ester bonds. These two strands run in opposite directions to each other and are therefore anti-parallel. Attached to each sugar is one of four types of molecules called bases. It is the sequence of these four bases along the backbone that encodes information. This information is read using the genetic code, which specifies the sequence of the amino acids within proteins. The code is read by copying stretches of DNA into the related nucleic acid RNA, in a process called transcription.

Within cells, DNA is organized into long structures called chromosomes. These chromosomes are duplicated before cells divide, in a process called DNA replication. Eukaryotic organisms (animals, plants, fungi, and protists) store most of their DNA inside the cell nucleus and some of their DNA in organelles, such as mitochondria or chloroplasts.

DNA was first isolated by the Swiss physician Friedrich Miescher who, in 1869, discovered a microscopic substance in the pus of discarded surgical bandages. As it resided in the nuclei of cells, he called it "nuclein". In 1919, Phoebus Levene identified the base, sugar and phosphate nucleotide unit. Levene suggested that DNA consisted of a string of nucleotide units linked together through the phosphate groups. However, Levene thought the chain was short and the bases repeated in a fixed order. In 1937 William Astbury produced the first X-ray diffraction patterns that showed that DNA had a regular structure.

Read More

Aum - The Symbol

Om or Aum, written in Devanāgari as ॐ and as ओम्, in Sanskrit known as pranava प्रणव, is a sacred/mystical syllable in the Dharma or Indian religions, i.e. Hinduism, Jainism, and Buddhism.

Aum is most commonly pronounced as a long or over-long nasalized close-mid back rounded vowel, though there are other enunciations adhered to in received traditions. It is placed at the beginning of most Hindu texts as a sacred incantation to be intoned at the beginning and end of a reading of the Vedas or prior to any prayer or mantra. The Māndukya Upanishad is entirely devoted to the explanation of the syllable. The syllable consists of three phonemes, a Vaishvanara, u Hiranyagarbha and m Iswara, which symbolize the beginning, duration, and dissolution of the universe and the associated gods Brahma, Vishnu, and Shiva, respectively. Aum is pronounced in three sounds - A (aaa) , U (ooooo) and M (mmmmm) and signifies Right (A) and Left (U) Sympathetic Nervous Systems (SNS) and (M) Parasympathetic Nervous System. Right SNS (controlled by Left part of brain) looks after the actional aspect where as the left SNS looks after the emotional aspect of human beings.

The name Omkara is taken as a name of God in the Hindu revivalist Arya Samaj.

The syllable aum is first described as all-encompassing mystical entity in the Upanishads. Today, in all Hindu art and all over India and Nepal, 'aum' can be seen virtually everywhere, a common sign for Hinduism and its philosophy and theology. Hindus believe that as creation began, the divine, all-encompassing consciousness took the form of the first and original vibration manifesting as sound "AUM". Before creation began it was "Shunyākāsha", the emptiness or the void. Shunyākāsha, meaning literally "no sky", is more than nothingness, because everything then existed in a latent state of potentiality.

The vibration of "AUM" symbolizes the manifestation of God in form ("sāguna brahman"). "AUM" is the reflection of the absolute reality, it is said to be "Adi Anadi", without beginning or the end and embracing all that exists. The mantra "AUM" is the name of God, the vibration of the Supreme. When taken letter by letter, A-U-M represents the divine energy (Shakti) united in its three elementary aspects: Bhrahma Shakti (creation), Vishnu Shakti (preservation) and Shiva Shakti (liberation, and/or destruction).

In Jainism, Aum is regarded to be a condensed form of reference to the five parameshthis, by their initials A+A+A+U+M

In Buddhism, Aum is placed at the beginning of their Vidya-Sadaksari or mystical formulary in six syllables as well as most other mantras and dhāranis. As a seed syllable (bija mantra), it is also considered holy in Esoteric Buddhism.

Read More

KITES

A kite is a tethered aircraft. The necessary lift that makes the kite wing fly is generated when air (or in some cases water) flows over and under the kite's wing, producing low pressure above the wing and high pressure below it.

This deflection also generates horizontal drag along the direction of the wind. The resultant force vector from the lift and drag force components is opposed by the tension of the one or more lines or tethers. The anchor point of the kite line may be static or moving (e.g., the towing of a kite by a running person, boat or vehicle).

Kites are usually heavier-than-air, but there is a second category of lighter-than-air kite called a kytoon which may be filled with hydrogen, hot air, methane, or helium; these stay aloft with or without wind; at calm they float; at wind they receive lift from buoyancy and aerodynamic lift. Kytoons have been made in toy-scale as well as military large scale.

Kites may be flown for recreation, art or other practical uses. Sport kites can be flown in aerial ballet, sometimes as part of a competition. Power kites are multi-line steerable kites designed to generate large forces which can be used to power activities such as kite surfing, kite landboarding, kite buggying and a new trend snow kiting. Kites towed behind boats can lift passengers which has had useful military applications in the past.

Kites were used approximately 2,800 years ago in China, where materials ideal for kite building were readily available: silk fabric for sail material; fine, high-tensile-strength silk for flying line; and resilient bamboo for a strong, lightweight framework. Alternatively, the kite authors Clive Hart and Tal Streeter hold that leaf kites existed far before that time in what is now Indonesia, based on their interpretation of cave paintings on Muna Island off Sulawesi. The kite was said to be the invention of the famous 5th century BC Chinese philosophers Mozi and Lu Ban. By at least 549 AD paper kites were being flown, as it was recorded in that year a paper kite was used as a message for a rescue mission. Ancient and medieval Chinese sources list other uses of kites for measuring distances, testing the wind, lifting men, signalling, and communication for military operations. The earliest known Chinese kites were flat (not bowed) and often rectangular. Later, tailless kites incorporated a stabilizing bowline. Kites were decorated with mythological motifs and legendary figures; some were fitted with strings and whistles to make musical sounds while flying.

Stories of kites were brought to Europe by Marco Polo towards the end of the 13th century, and kites were brought back by sailors from Japan and Malaysia in the 16th and 17th centuries.
The period from 1860 to about 1910 became the "golden age of kiting". Kites started to be used for scientific purposes, especially in meteorology, aeronautics, wireless communications and photography; reliable manned kites were developed as well as power kites. Invention of powered airplane diminished interest in kites.World War II saw a limited use of kites for military purposes. Since then they are used mainly for recreation due to a vast improvement in technology.

Read More