History of the volt

In 1800, as the result of a professional disagreement over the galvanic response advocated by Luigi Galvani, Alessandro Volta developed the so-called Voltaic pile, a forerunner of the battery, which produced a steady electric current. Volta had determined that the most effective pair of dissimilar metals to produce electricity was zinc and silver. In the 1880s, the International Electrical Congress, now the International Electrotechnical Commission (IEC), approved the volt as the unit for electromotive force. At that time, the volt was defined as the potential difference [i.e., what is nowadays called the "voltage (difference)"] across a conductor when a current of one ampere dissipates one watt of power.


The international volt was defined in 1893 as 1/1.434 of the emf of a Clark cell. This definition was abandoned in 1908 in favor of a definition based on the international ohm and international ampere until the entire set of "reproducible units" was abandoned in 1948.

Prior to the development of the Josephson junction voltage standard, the volt was maintained in national laboratories using specially constructed batteries called standard cells. The United States used a design called the Weston cell from 1905 to 1972.

This SI unit is named after Alessandro Volta. As with every SI unit whose name is derived from the proper name of a person, the first letter of its symbol is uppercase (V). When an SI unit is spelled out in English, it should always begin with a lowercase letter (volt), except where any word would be capitalized, such as at the beginning of a sentence or in capitalized material such as a title. Note that "degree Celsius" conforms to this rule because the "d" is lowercase.

—Based on The International System of Units,

Sony Alpha DSLR- A850 Full Frame Digital SLR Camera

Sony Alpha DSLR- A850 Full Frame Digital SLR Camera

• Full Frame Image Sensor (24 x 36mm)
• High Resolution (24.6 Megapixels)
• High Sensitivity (ISO 6400)
• Dual Noise Reduction Processing
• SteadyShot INSIDE Image Stabilization
• 3.0" Xtra Fine LCD
• 9-Point Auto Focusing
• 40-Segment Multi-Pattern Metering
• CF and Memory Stick Duo Card Slots
• 13 Creative Style Modes
• 13 Creative Style Modes

9W Power Amplifier

The TDA1010 is a monolithic integrated class-B audio amplifier circuit in a 9-lead single in-line (SIL) plastic package. The device is primarily developed as a 6 W car radio amplifier for use with 4 Wand 2 Wload impedances. The wide supply voltage range and the flexibility of the IC make it an attractive proposition for record players and tape recorders with output powers up to 10 W.

50W Power Amplifier

Here is Power Amplifier 50W Circuit,Use IC STK1050. OCL Class AB Amp.

Voltage supply +35V , -35V 2-3A / Ch

bending movment

On the Design of Damaged Steel Columns


• Emeritus Professor Nick Trahair

• Kourosh Kayvani (Connell Wagner)

This project explores a number of situations where columns with out-of-tolerance crookedness or which have been damaged may still be designed, despite the implications of many codes that they must be replaced, and has suggested rules for their design. The case of a column whose crookedness is out-of-tolerance is first examined, and two design methods are suggested. In the first method, the column is treated in a similar way to that used for the basis of the BS5950 column design method by allowing for the excess crookednesses. In the second method, the column is designed as a straight beam-column with design moments equal to those resulting from the first-order analysis of an imperfect structure whose geometry includes the excess crookednesses.



Following this, the case is considered of a column damaged by unexpected bending which leaves an out-of-tolerance permanent set. It is concluded that the residual stresses caused by the damaging bending moments can be ignored, and the damaged column can be designed for its increased crookedness by using either of the methods proposed for columns with out-of-tolerance crookedness. The straightening of the damaged column was also considered. It was found that the residual stresses which follow relaxation after straightening can also be ignored and the column designed in the usual way.



Finally, the case is analysed of a force-fitted column which has excessive crookedness locked in during its connection to other members of a structure. It is found that the force-fitting deflection can be regarded as an initial crookedness, so that the column can be designed as an out-of-tolerance column.



Trahair, NS and Kayvani, K 'Capacities of Steel Columns with Excessive Crookedness', The Structural Engineer, 84 (4), 2006, pp 37 - 41, and School of Civil Engineering Research Report R 846.

dambulla history

Dambulla is situated exactly 160Km from Colombo. It is situated at the very end of north western province and the right beginning of the north central province. Dambulla is one of the places of historical importance in Sri Lanka.

Dambulla is a historical city. Tourists who come to Sri Lanka never fail to visit Dambulla. There main attractions are Dambulla historical temple and Sigiriya fortress. Sigiriya is situated about 10Km away from Dambulla, other attractive places are Kandalama tank, Namal uyana and Kaludiya Pokuna.
This city belongs to the dry zone.

The largest market of Sri Lanka is situated in Dambulla. It is called “The Economic Center”. The city becomes very busy during the evening until late in the night since it is the center of distribution of vegetable to the entire country. Almost all the vegetables grown in Sri Lanka can be seen in Dambulla.
You can see a lot of indigenous and migrant birds at Kandalama. Dambulla has a hot and humid climate throughout the year. Wild elephants too can be seen at habarana, a village situated few miles away from Dambulla. The ebony and the satin wood are the valuable trees grow in his area.There are an international level cricket stadium too in Dambulla. Nearly twenty hotels in and around Dambulla provides all the modern facility for tourist.

segiry history

"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. Sigiriya is world famous for its frescoes.

A popular tourist destination, Sigiriya is also renowned for its ancient paintings which are reminiscent of the Ajanta Caves ofI ndia. 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.

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".