A car engine is also known as an internal combustion engine, and is designed to use small, controlled explosions to create the power necessary to move the vehicle. This type of engine is used in lawnmowers, motorcycles and other motorized devices. All car engines are designed to use a four stroke combustion cycle. The four strokes are the intake, compression, combustion and exhaust. These strokes are repeated in quick succession to generate power. All parts of the combustion cycle take place within an enclosed car engine.
A small, controlled explosion forces the piston, or "arms," of the engine to move. When the energy from the explosion is almost worn out, another explosion occurs, forcing the pistons to move again. This recurring cycle generates the power needed.
The piston is a metal rod that is connected by a crankshaft to the connecting rod. During the intake cycle, the intake valve opens and the piston moves down, to start the cycle. This motion brings a cylinder full of air and a small amount of gas into the engine.
In the compression cycle, the piston moves up and reduces the space of the air and fuel. The smaller the space, the more powerful the explosion will be. The seal on this space must be airtight, so that no energy is lost.
The speed of the cycle determines the speed of the vehicle. When the driver increases the amount of gas going to the engine, the engine pistons increase their movement. This faster pace results in an increase in the speed of the combustion cycle.
Nanotechnology is a branch of science that deals with particles 1-100 nanometers in size. Experts believe possible dangers of nanotechnology lie in how these tiny particles might interact with the environment, and more importantly, with the human body. Complicating the dangers of nanotechnology, size and shape of nanoparticles affect the level of toxicity, preempting the ease of uniform categories even when considering a single element. In general, experts report smaller particles are more bioactive and toxic. Their ability to interact with other living systems increases because they can easily cross the skin, lung, and in some cases the blood/brain barriers. Once inside the body, there may be further biochemical reactions like the creation of free radicals that damage cells.
Nanotechnology should not be confused with molecular nanotechnology (MNT) a still theoretical science dedicated to manufacturing products from the atom up through use of nanoscale machines.
Thunder is caused by lightning, which is essentially a stream of electrons flowing between or within clouds, or between a cloud and the ground. The air surrounding the electron stream is heated to as hot as 50,000 degrees Farhenheit, which is three times hotter than the surface of the sun. As the superheated air cools it produces a resonating tube of partial vacuum surrounding the lightning's path. The nearby air rapidly expands and contracts. This causes the column to vibrate like a tubular drum head and produces a tremendous crack. As the vibrations gradually die out, the sound echoes and reverberates, generating the rumbling we call thunder.The speed of sound is even more insignificant when compared to the speed of light. The light from the flash reaches us in a fraction of a second, whereas the sound lags along like a snail following an interplanetary rocket.
The audiovisual spectacle of thunder and lightning is a combination of the dynamics of the vibration of air molecules and their disturbance by electrical forces. It is an awesome show--and one that reminds all of us of the powers of nature and our own insignificance in relation to them.
A typical water-softening system removes calcium and magnesium ions from hard water and replaces them with sodium ions. Calcium and magnesium ions interfere with the action of household soaps and detergents, but sodium does not. The water-softening process thus helps detergents to more effectively remove dirt and oils from clothing and dishes. It also helps soaps to give a "slippery" feel to your skin when you wash. Most manufacturers of water softeners recommend that you reduce the amount of soap and detergents you use after installing a water softener.
The water softener unit is located in your household plumbing near the place where water enters the house so that it softens the water used for drinking and washing but not for irrigation. The unit contains several cubic feet of porous plastic resin covered with molecules that attract and bind to positive ions dissolved in the water. Normally, sodium positive ions coat the resin, but as water flows over the resin on its way to your sink or washer, the naturally occurring calcium and magnesium positive ions that exist in hard water stick to the resin. This releases sodium ions into the water in order to maintain a balance of electrical charge on the resin. Gradually, most of the sodium ions are released into the household water, and the resin becomes saturated with calcium and magnesium ions. Every few days, the unit must renew the resin by rinsing it with a concentrated solution of saltwater (sodium chloride), usually in the middle of the night. The high concentration of sodium ions in the salty water displaces the calcium and magnesium ions the resin, and the resin becomes once again covered with sodium ions. The salty rinse water, calcium and magnesium ions are flushed down the drain, and the system resumes normal operation. (Every so often it is necessary to add a bag of sodium chloride salt to the softener unit to prepare this salty rinse water
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Jets leave white trails, or contrails, in their wakes for the same reason you can sometimes see your breath. The hot, humid exhaust from jet engines mixes with the atmosphere, which at high altitude is of much lower vapor pressure and temperature than the exhaust gas. The water vapor contained in the jet exhaust condenses and may freeze, and this mixing process forms a cloud very similar to the one your hot breath makes on a cold day.
Jet engine exhaust contains carbon dioxide, oxides of sulfur and nitrogen, unburned fuel, soot and metal particles, as well as water vapor. The soot provides condensation sites for the water vapor. Any particles present in the air provide additional sites
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A volcano is essentially an opening or a vent through which this magma and the dissolved gases it contains are discharged. Although there are several factors triggering a volcanic eruption, three predominate: the buoyancy of the magma, the pressure from the exsolved gases in the magma and the injection of a new batch of magma into an already filled magma chamber.
Magmas of so-called andesitic and rhyolitic compositions also contain dissolved volatiles such as water, sulfur dioxide and carbon dioxide. Experiments have shown that the amount of a dissolved gas in magma (its solubility) at atmospheric pressure is zero, but rises with increasing pressure
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The term jet propulsion refers to the action produced by a reactor to the ejection of matter. Jet propulsion revolutionized the science of flight by dramatically increasing possible speeds and altitudes, hence enabling space exploration. When the matter in a typical rocket (like gunpowder in fireworks) is ignited, the resulting chemical reaction produces heat and gases, which escape from the rocket and cause it to move forward. The oxygen necessary for combustion is carried (in tanks or in a combined form) in the rocket itself so that the rocket thrust is independent of the atmosphere. Other jet propulsion devices depend on the air inducted into the engine to supply the necessary oxygen. After heat is released by the combustion, the hot gases are accelerated through the engine so that the exit velocity is greater than the airstream velocity at the entrance.
Fuels contain a large quantity of potential energy, which is rapidly released during combustion. A portion of this heat energy is converted into useful work, moving the vehicle through the atmosphere or into space. Another portion, however, in the form of the jet's kinetic energy, is lost and dissipates into the atmosphere. The very fuel-efficient turbofan engines used in modern commercial aircraft engines attempt to minimize the latter portion.
Various types of jet engines have been developed to deliver the required thrust and engine performance for a wide range of flight speeds and altitudes. Air-breathing turbojet, turbofan and ramjet engines operate according to similar principles in the sense that they raise the inducted air pressure before combustion and expand the high-energy gases before they leave, in a nozzle or exhaust system. In turbojet engines, the inducted air goes through a compressor to increase its pressure before entering the combustor, then through a turbine before accelerating in the exhaust nozzle. The ramjet engine, though, has no moving parts; it produces a ram pressure rise from decelerating the high-speed inducted air in the inlet diffuser. The ramjet engine can only operate at high supersonic velocities and therefore requires another launching device, such as a rocket or turbojet engine, to accelerate it to the required speed.
Computer telephony integration (CTI) means coordinating a computer with a telephone system, and using the computer (perhaps even a desktop machine) to perform the call control functions usually associated with a PBX or Key System. Computer telephony integration (CTI) is technology that allows interactions on a telephone and a computer to be integrated or co-ordinated. As contact channels have expanded from voice to include email, web, and fax, the definition of CTI has expanded to include the integration of all customer contact channels (voice, email, web, fax, etc.) with computer systems. So the computer can answer calls, play recorded messages, re-route calls, recognize incoming callers (using caller ID or similar services) and bring up screens showing callers' accounts, order status or any other information in the database. Then the operator (customer service representative, order taker) can converse with the customer and have all pertinent details at his or her fingertips. Telephone control from the desktop PC includes answering calls or hanging up, transferring, forwarding, conferencing, or placing calls on hold. Integrated telephone and PC features will insure that users always know who is calling, even when they are already on the phone, because all calls show up on their PC screen. Conference calls will be a simple matter of dragging the icons representing different callers on a PC screen onto an existing call icon.
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Atoms are comprised of a nucleus consisting of protons and neutrons. The number of orbiting electrons is the same as the number of protons and is termed the "atomic number" of the element. Helium has two protons and two electrons; its atomic number is two. Basically, it contains a nucleus, holding some number (call it N) of positively charged protons, which is surrounded by a cloud (N) of negatively charged electrons. The force that holds the electrons and protons together is the electromagnetic force. The number N tells you what element you have: for hydrogen N equals 1, for helium, 2, and so on.
The same electromagnetic force that draws opposite charged electrons and protons together tries to push the protons (which all have the same charge) away from each other. To avoid this separation, another particle comes into play in the nucleus: the neutron. Much like a proton in mass but without electric charge, the neutron is essential for holding the nucleus together. At short distances (i.e. within the nucleus), a very strong force, more powerful than electromagnetism, takes over and attracts the protons and neutrons. If you hit protons and neutrons hard enough, you find that they in turn are made of even smaller pieces, called quarks. Quarks are held together by the same strong force that holds the nucleus together
A Josephson junction is made by sandwiching a thin layer of a nonsuperconducting material between two layers of superconducting material. The pairs of superconducting electrons could "tunnel" right through the nonsuperconducting barrier from one superconductor to another. In a Josephson junction, the nonsuperconducting barrier separating the two superconductors must be very thin. If the barrier is an insulator, it has to be on the order of 30 angstroms thick or less. If the barrier is another metal (nonsuperconducting), it can be as much as several microns thick. Until a critical current is reached, a supercurrent can flow across the barrier; electron pairs can tunnel across the barrier without any resistance. But when the critical current is exceeded, another voltage will develop across the junction. That voltage will depend on time--that is, it is an AC voltage. This in turn causes a lowering of the junction's critical current, causing even more normal current to flow--and a larger AC voltage. The frequency of this AC voltage is nearly 500 gigahertz (GHz) per millivolt across the junction. So, as long as the current through the junction is less than the critical current, the voltage is zero. As soon as the current exceeds the critical current, the voltage is not zero but oscillates in time. Detecting and measuring the change from one state to the other is at the heart of the many applications for Josephson junctions.
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