Compact Disk or CD

A compact disk (cd) is a popular form of digital storage media used for computer files, pictures, and music. The plastic platter is read and written to by a laser in a CD drive. It comes in several varieties including CD-ROM, CD-R, and CD-RW.

James Russell invented the compact disk in 1965. James Russell was granted a total of 22 patents for various elements of his compact disk system. However, the compact disk did not become popular until it was mass manufactured by Philips in 1980.

Calorific value of fuels

Calorific value of fuels
Heat energy is measured in units of joules or calories (1calorie = 4.18 joules). The heat generated by fuels when they burn in joules or calories measures quality of fuels. All fuels do not burn efficiently. Thus there are fuels that produce more heat than the others are. This can be distinguished in terms of number of joules or calories that they generate on burning.

The amount of energy generated when 1 unit mass of fuel is burnt completely is known as the calorific value of the fuel. The word calorific is used, not “joulific” because of the use of the word calorific has been in use for a very long time. When 1 gram of charcoal is burnt, it produces 33 kilo joules. Thus the calorific value of charcoal is 33kJ/g. Sometimes instead of calorific value, another term kilowatt per kilogram (KWh/kg) is used.

hydrogens calorific value is 150

India to host 4th Environment Friendly Vehicles Conference 2009

India will host the 4th Environmentally Friendly Vehicle (EFV) Conference in New Delhi from November 23-24th this year. This is for the first time that such a prestigious and international event on automobile sector is being organized in a developing country. The EFV conference aims at promotion of environmental friendly vehicles to ensure sustainable road transport. Reduction of greenhouse gases, improvement of air quality, reduction in traffic noise, protection of resources and prevention of the release of harmful substances are the main objectives of the Conference. It will also pave the way in achieving the ambitious targets on human health at a cost effective and sustainable manner. The Conference offers a platform for senior government officials, industry leaders, academicians and key decision makers, to discuss environment friendly mode of public transport and development. As a part of WP-29 initiative, Environmentally Friendly Vehicle (EFV) Conferences are being organized biennially. The first such Conference was held in Tokyo, Japan in 2003, second in Birmingham, UK in 2005 and the third conference in Dresden, Germany in 2007. The 2009 Delhi Conference will deal with issues such as – • Mobility and Environment - Role of EFVs • Future of EFVs & electric vehicles, • Gaseous Fuels Technology, Alternative fuels and Drives – Technology of Future • Regulatory and Legislative Framework for EFVs. The Conference is being jointly hosted by Ministry of Heavy Industries and Public Enterprises and other stakeholders viz. Ministry of Shipping, Road Transport and Highways, Ministry of Environment and Forest, Ministry of New and Renewable Energy, Ministry of Urban Development, Ministry of Petroleum and Natural Gas as well as Industry association i.e. Society of Indian Automobile Manufacturers (SIAM) and Auto Components Manufacturers Association (ACMA).

How Television Transmission Works?

TV Transmission Basics

1. Television transmissions are signals that come into your home to display an image on your TV. These signals can be sent over the air, through an antenna or satellite dish, or through a network of cables, as with cable television. These signals are converted to images before they are displayed on your screen.

Differences in Over the Air Transmissions

2. Over the air transmissions are usually radio signals. Antenna signals, such as UHF and VHF, and satellite signals are sent over different parts of the broadcasting spectrum, which is also used by cell phones, AM and FM frequencies and walkie-talkies. The difference between antenna and satellite signals is the frequency they transmit on, and the technology used to send them.

Antenna Signals

3. Antenna signals are sent from a radio broadcast tower, just like AM or FM signals. This is why many handheld radios can intercept antenna TV signals and play the sound. Antennas must be within range of the closest broadcast tower to receive a signal strong enough for display.

Satellite Signals

4. Satellite signals are transmitted from the broadcaster to the satellite, where they are blanket broadcast to any satellite dish capable of receiving them. Satellites are not limited by range, but by line sight, so a receiving dish must have a clear view of the satellite in the sky.

Cable Signals

5. Cable transmissions are converted to electrical impulses. The impulses can travel much further than antenna signals, but will lose integrity after long distances. They are over intercepted by stations that will strengthen the signal before retransmitting it to your home.

Conversion

6. Once the signal has reached your home, it is converted so you can view it on your screen. Satellite signals require special devices, known as receivers, to do this conversion. Analog cable signals sometimes need a special receiving unit, but nearly all modern TVs are considered "cable ready," meaning they have the receiving unit built in. Any analog antenna signal can be displayed without special equipment, and TVs that are not "digital ready" will require a digital to analog converter box to properly display.

Einstein

February 28th marks a grand click start of year long celebrations in India of 1905 – the magnificent year in which Einstein published three of his major works. 2005 has been designated as International year of Physics by United Nations. The grand toast has already been raised by international scientific community particularly physicists to honour a great personality of our times – Dr. Albert Einstein (born Ulm - Germany March 14, 1879 to April 18, 1955). Except Issac Newton, no other physicist changed our version and vision of Universe and its understanding as Dr. Einstein did. Much credit is given to his inventions and postulations because they came at a time when two world wars were fought and much of the socio-economic and scientific developments were blurred by exponsionist political dogmas. An average student at Zurich (Switzerland) who even failed to get admission to graduate school, Einstein was packed off to Federal Patent Office in Born (Switzerland) to serve as a patent clerk. Far removed from extraordinary gadgets and facilities of laboratory and library, Albert worked ferociously for long hours to publish five papers in one year each of which is a gem by itself. He was all of just 26 years in 1905 when he achieved this unsurpassed feat. The year 1905 has just one comparable year of science before 1665 to 1666. This is the time when in span of 18 months Sir Issac Newton invented calculus, constructed a theory of optics, explained how gravity works and discovered his laws of motion. It was such a sustained sprint of intellectual achievement that, at that time no one thought it could be equaled. Newton, hence stood as the tallest physicist. Einstein too gave the world new forms of mathematics to support his arguments in physics. He showed that atoms (the smallest divisible particles of matter) are real (it was a controversy at that time). His first paper which fetched him a Nobel Prize in 1921 proved existence of photons particles in light. In 1922 he had received a paper from unknown Indian physicist (then) Satyendra Nath Bose who worked on behaviour of these light particles – photons. In laboratory situation, Bose – Einstein condensate was proved to be correct only in 1995 nearly forty years after death of Einstein. His paper triggered a flurry of research by a whole generation of young physicists which has codified the universe now. Quantum mechanics took firm shape in 1920s and 1930s after that paper from him. As such, Albert Einstein was not considered to be an adroit mathematician. His power lay in that he could visualize physical consequences of experimental results. In the same year 1905, Einstein realized that nothing can travel faster than light. His first relativity paper later lead to general theory of relativity. The consequence of his observation E=mc2 where ‘E’ represents energy, ‘m’ is the mass of a body and ‘c’ denotes speed of light – lead to creation of a bomb which caused the holocaust in Hiroshima and Nagasaki in 1945. One particular paper which served as doctoral thesis (Princeton, N.J.,U.S.) was beautiful but brief. It explained how sugar dissolves in water! He explained motion was caused by molecules hitting the particles. Till then the question of “Brownian motion” remained unexplained as how suspended particle in a solution behaved. Einstein’s theory proved that molecules are real and they exist!! Einstein wrote profound things in simplistic terms. He himself admitted this in 1932, “the real goal of my research has always been simplification and unification of the system of theoretical physics”. He once remarked about Newton calling him lucky ——“there is only one Universe to discover and he did it”, Of course, Albert was referring to laws of gravity of Issac Newton. There are many legends about intellectual capabilities of Einstein. He is even held to be a demigod of physics. Between 1905 and 1925 – Einstein transformed human understanding of nature on every scale. From smallest particles (atom) to the biggest (cosmos as a whole). The problems that he left behind uncracked, continue to form cutting edge technology studies. When the scientific community around the world is relocating itself to use all their knowledge of, geology, remote sensing, space science, weather forecast to understand Tsunami, memories of a saint scientist, Dr. Albert Einstein stands tall in our memory. (PIB Features)

Nuclear force

The nuclear force (or nucleon-nucleon interaction or residual strong force) is the force between two or more nucleons.

It is responsible for binding of protons and neutrons into atomic nuclei. To a large extent, this force can be understood in terms of the exchange of virtual light mesons, such as the pions.

Sometimes the nuclear force is called the residual strong force, in contrast to the strong interactions which are now understood to arise from quantum chromodynamics (QCD).

This phrasing arose during the 1970s when QCD was being established. Before that time, the strong nuclear force referred to the inter-nucleon potential.

After the verification of the quark model, strong interaction has come to mean QCD.

Crankcase dilution

Crankcase dilution is a phenomenon in engines where accumulation of unburned gasoline in the crankcase, an excessively rich fuel mixture or poor combustion allows a certain amount of gasoline to pass down between the pistons and cylinder walls and dilute the engine oil.

RADAR

Radar is an object detection system that uses electromagnetic waves to identify the range, altitude, direction, or speed of both moving and fixed objects such as aircraft, ships, motor vehicles, weather formations, and terrain. The term RADAR was coined in 1941 as an acronym for RAdio Detection And Ranging. The term has since entered the English language as a standard word, radar, losing the capitalization. Radar was originally called RDF (Radio Direction Finder, now used as a totally different device) in the United Kingdom, in order to preserve the secrecy of its ranging capability

it was the British who were the first to fully exploit it as a defence against aircraft attack. This was spurred on by fears that the Germans were developing death rays. Following a study of the possibility of propagating electromagnetic energy and the likely effect, the British scientists asked by the Air Ministry to investigate concluded that a death ray was impractical but detection of aircraft appeared feasible. Robert Watson-Watt demonstrated to his superiors the capabilities of a working prototype and patented the device in 1935 (British Patent GB593017) It served as the basis for the Chain Home network of radars to defend Great Britain.

National Institute of Oceanography

The National Institute of Oceanography (NIO) is a constituent laboratory of CSIR - the Council of Scientific and Industrial Research, an autonomous research organization in India. The institute has its headquarters in the coastal state Goa, and regional centres in Kochi , Mumbai and Vizag. The Institute was established on 1 January 1966. At the end of over 40 years, this is grown today into a large oceanographic laboratory of international repute with main focus on the understanding of special oceanographic features of the Northern Indian Ocean. The institute headquarters was shifted to its present location on a panoramic view of Arabian Sea in the background soon after its establishment.

Projects

The first tide generated electricity project was established at
Vizhinjam, Kerala

Vizhinjam fishing harbour is the site of a unique demonstrations plant that converts sea wave energy to elecricity and is given to the local grid. This plant is based on the oscillating water column (OWC) principle. A caisson was constructed in December 1990 at Vizhinjam and two generations of power modules have been tested as of today. The plant was first commissioned in October 1991. The physical processes in the energy conversion are understood to a much greater extent, leading to a threefold increase in absolute power from the plant.

At present, more than 80% cost of the wave energy plant is due to civil construction (concrete caissons). Considerable cost savings can be obtained using the concept of multi-functional breakwaters wherein a power module forms an incremental addition to a caisson breakwater. It is proposed to demonstrate the utility of this concept with the design and construction of a breakwater with a number of power modules.

Applications and uses of chlorine

Applications and uses

Production of industrial and consumer products

Chlorine's principal applications are in the production of a wide range of industrial and consumer products.^[33][34] For example, it is used in making plastics, solvents for dry cleaning and metal degreasing, textiles, agrochemicals and pharmaceuticals, insecticides, dyestuffs, household cleaning products, etc.

Purification and disinfection

Chlorine is an important chemical for water purification (such as water treatment plants), in disinfectants, and in bleach. Chlorine in water is more than three times more effective as a disinfectant against Escherichia coli than an equivalent concentration of bromine, and is more than six times more effective than an equivalent concentration of iodine.^[35]

Chlorine is usually used (in the form of hypochlorous acid) to kill bacteria and other microbes in drinking water supplies and public swimming pools. In most private swimming pools chlorine itself is not used, but rathersodium hypochlorite, formed from chlorine and sodium hydroxide, or solid tablets of chlorinated isocyanurates. Even small water supplies are now routinely chlorinated.^[3] (See also chlorination)

It is often impractical to store and use poisonous chlorine gas for water treatment, so alternative methods of adding chlorine are used. These include hypochlorite solutions, which gradually release chlorine into the water, and compounds like sodium dichloro-s-triazinetrione (dihydrate or anhydrous), sometimes referred to as "dichlor", and trichloro-s-triazinetrione, sometimes referred to as "trichlor". These compounds are stable while solid and may be used in powdered, granular, or tablet form. When added in small amounts to pool water or industrial water systems, the chlorine atoms hydrolyze from the rest of the molecule forming hypochlorous acid (HOCl) which acts as a general biocide killing germs, micro-organisms, algae, and so on.

Chemistry

Elemental chlorine is an oxidizer. It undergoes halogen substitution reactions with lower halide salts. For example, chlorine gas bubbled through a solution of bromide or iodide anions oxidizes them to bromine and iodine respectively.

Like the other halogens, chlorine participates in free-radical substitution reactions with hydrogen-containing organic compounds. This reaction is often—but not invariably—non-regioselective, and hence, may result in a mixture of isomeric products. It is often difficult to control the degree of substitution as well, so multiple substitutions are common. If the different reaction products are easily separated, e.g. by distillation, substitutive free-radical chlorination (in some cases accompanied by concurrent thermal dehydrochlorination) may be a useful synthetic route. Industrial examples of this are the production of methyl chloride,methylene chloride, chloroform and carbon tetrachloride from methane, allyl chloride from propylene, and trichloroethylene and tetrachloroethylene from 1,2-dichloroethane.

Like the other halides, chlorine undergoes electrophilic additions reactions, most notably, the chlorination of alkenes and aromatic compounds with a Lewis acid catalyst. Organic chlorine compounds tend to be less reactive in nucleophilic substitution reactions than the corresponding bromine or iodine derivatives, but they tend to be cheaper. They may be activated for reaction by substituting with a tosylate group, or by the use of a catalytic amount of sodium iodide.

Chlorine is used extensively in organic and inorganic chemistry as an oxidizing agent and in substitution reactions because chlorine often imparts many desired properties to an organic compound, due to its electronegativity.

Chlorine compounds are used as intermediates in the production of a number of important commercial products that do not contain chlorine. Examples are: polycarbonates, polyurethanes, silicones,polytetrafluoroethylene, carboxymethyl cellulose and propylene oxide.

Use as a weapon

• World War I

Main article: Poison gas in World War I

Chlorine gas, also known as bertholite, was first used as a weapon in World War I by Germany on April 22, 1915 in the Second Battle of Ypres. As described by the soldiers it had a distinctive smell of a mixture between pepper and pineapple. It also tasted metallic and stung the back of the throat and chest. Chlorine can react with water in the mucosa of the lungs to form hydrochloric acid, an irritant which can be lethal. The damage done by chlorine gas can be prevented by a gas mask, or other filtration method, which makes the overall chance of death by chlorine gas much lower than those of other chemical weapons. It was pioneered by a German scientist later to be a Nobel laureate, Fritz Haber of the Kaiser Wilhelm Institute in Berlin, in collaboration with the German chemical conglomerate IG Farben, who developed methods for discharging chlorine gas against an entrenched enemy. It is alleged that Haber's role in the use of chlorine as a deadly weapon drove his wife, Clara Immerwahr, to suicide. After its first use, chlorine was utilized by both sides as a chemical weapon, but it was soon replaced by the more deadly gases phosgene and mustard gas.

• Iraq War

Main article: 2007 chlorine bombings in Iraq

Chlorine gas has also been used by insurgents against the local population and coalition forces in the Iraq War in the form of Chlorine bombs. On March 17, 2007, for example, three chlorine filled trucks were detonated in the Anbar province killing two and sickening over 350.^[37] Other chlorine bomb attacks resulted in higher death tolls, with more than 30 deaths on two separate occasions.^[38] Most of the deaths were caused by the force of the explosions rather than the effects of chlorine, since the toxic gas is readily dispersed and diluted in the atmosphere by the blast. The Iraqi authorities have tightened up security for chlorine, which is essential for providing safe drinking water for the population.

Chlorine cracking

Chlorine "attack" of an acetal resin plumbing joint.

The element is widely used for purifying water owing to its powerful oxidizing properties, especially potable water supplies and water used in swimming pools. Several catastrophic collapses of swimming pool ceilings have occurred owing to stress corrosion cracking of stainless steel rods used to suspend them.Some polymers are also sensitive to attack, including acetal resin and polybutene. Both materials were used in hot and cold water domestic supplies, and stress corrosion cracking caused widespread failures in the USA in the 1980s and '90s. One example shows an acetal joint in a water supply system, which when it fractured, caused substantial physical damage to computers in the labs below the supply. The cracks started at injection molding defects in the joint and grew slowly until finally triggered. The fracture surface shows iron and calcium salts which were deposited in the leaking joint from the water supply before failure.

[edit]Other uses

Chlorine is used in the manufacture of numerous organic chlorine compounds, the most significant of which in terms of production volume are 1,2-dichloroethane and vinyl chloride, intermediates in the production of PVC. Other particularly important organochlorines are methyl chloride, methylene chloride, chloroform, vinylidene chloride, trichloroethylene,perchloroethylene, allyl chloride, epichlorohydrin, chlorobenzene, dichlorobenzenes and trichlorobenzenes.

Chlorine is also used in the production of chlorates and in bromine extraction.

[edit]Health effects

NFPA 704
0 3 0 OX

Chlorine is a toxic gas that irritates the respiratory system. Because it is heavier than air, it tends to accumulate at the bottom of poorly ventilated spaces. Chlorine gas is a strong oxidizer, which may react with flammable materials.

Chlorine is detectable in concentrations of as low as 0.2 ppm. Coughing and vomiting may occur at 30 ppm and lung damage at 60 ppm. About 1000 ppm can be fatal after a few deep breaths of the gas.^[4] Breathing lower concentrations can aggravate the respiratory system, and exposure to the gas can irritate the eyes.

Chlorine's toxicity comes from its oxidizing power. When chlorine is inhaled at concentrations above 30ppm it begins to react with water and cells which change it into hydrochloric acid (HCl) andhypochlorous acid (HClO).

When used at specified levels for water disinfection, although chlorine reaction with water itself usually doesn't represent a major concern for human health, other materials present in the water can generate disinfection by-products that can damage human health.