Nuclear power is the controlled use of nuclear energy.' like uranium that can be released by nuclear reactions in a machine called a nuclear reactor. This energy is made into electricity, which then can be used to power machines and heat homes. In 2007, 14% of the world's electricity came from nuclear power. Nuclear power plants also make radioactive waste that could be harmful if it is not stored properly.
People have also been studying since the middle 20th century to use fusion power which produces much more energy and doesn't produce radioactive waste. Nuclear fusion reactors don't exist yet and are still being developed.
Enrico Fermi made the first nuclear reactor in 1941. Many reactors were built in the U.S. during World War II during the Manhattan Project. In 1954 the first nuclear power plant started in Obninsk near Moscow. Most nuclear power plants in the U.S. were built during the 1960s and 1970s. Nuclear reactors also power some large military ships and submarines.
Nuclear reactors use a process called nuclear fission, which uses atoms like uranium or plutonium (In particular the isotope Uranium 235) and splits them apart with particles called neutrons. This converts some of the mass into energy, according to Einstein's equation E=mc2. The fissionable elements are placed into rods called 'fuel rods'. The fuel rods are submerged in water, and the energy released in the fission reaction heats up the water which turns into steam.
The steam then turns a turbine, which generates electricity. The steam is then condensed in huge cooling towers, and it turns back into water and is sent into the reactor again.
The reaction can be controlled by putting 'control rods' in between the fuel rods. The control rods are generally made of boron, which absorbs neutrons and stops the reaction.
A nuclear meltdown can happen when the reaction is not controlled, and starts to generate dangerous radioactive gases (like Krypton). Contrary to popular belief, nuclear reactors can't explode like a nuclear bomb, but it is a danger when radioactive materials escape.
Some serious nuclear accidents have occurred. A scale was made to measure how dangerous accidents are. It is called the International Nuclear Event Scale. The scale has 8 levels (0-7), and 7 is the worst.
Nuclear-powered submarine mishaps include the Soviet submarine K-19 reactor accident (1961), the Soviet submarine K-27 reactor accident (1968), and the Soviet submarine K-431 reactor accident (1985).
The economics of nuclear power is challenging, and following the 2011 Fukushima nuclear disaster, costs are likely to go up for currently operating and new nuclear power plants, due to increased requirements for on-site spent fuel management and elevated design basis threats.
There is a debate about the use of nuclear power. Supporters, such as the World Nuclear Association and IAEA, argue that nuclear power is a sustainable energy source that reduces carbon emissions. Additionally, it does not contribute to smog or acid rain. Anti-nuclear opponents, such as Greenpeace International and the Nuclear Information and Resource Service, believe that nuclear power poses threats to people and the environment.
In 2007, nuclear power plants made some 2600 TWh of electricity and provided 14 percent of the electricity used in the world, which represented a fall of 2 per cent compared with 2006. As of May 9, 2010, there were 438 (372 GW) nuclear reactors operating globally. A peak was reached in 2002 when there were 444 nuclear reactors operating.
The nuclear emergencies at Japan's Fukushima Daiichi Nuclear Power Plant and other nuclear facilities raised questions about the future of nuclear power. Platts has said that "the crisis at Japan's Fukushima nuclear plants has prompted leading energy-consuming countries to review the safety of their existing reactors and cast doubt on the speed and scale of planned expansions around the world". Following the Fukushima nuclear disaster, the International Energy Agency halved its estimate of additional nuclear generating capacity to be built by 2035.
Software versioning
Software versioning is a way to name different versions of computer software. A computer software has different states in its life-cycle process from Development through deployment into Production and Sustainment. Each state in the process is given a unique version and version number. Versions are most often a sequence of one to four numbers (for example, 12.2.3) to represent Major.Minor.Maintenance actions, but can also use names, dates, or other sequencing mechanisms. In some practices, the numbers are used with variations like the 3rd digit being replaced by a letter (for example, 4.1a). The changes are all revisions in that something is being changed and the version number tells people how complex the change is to the software.
Many times, after a program has been made, things called "patches" can be downloaded from the program's website. The patches usually make small updates or fixes to the main program, such as fixing bugs or updating information or program functions. When a patch is used, the program is advanced to the next version, advancing the version number by the appropriate level.
Sympathy
Sympathy exists when the feelings or emotions of one person lead to similar feelings in another person so that they share feeling. Mostly sympathy means the sharing of unhappiness or suffering, but it can also mean sharing other (positive) emotions. In a broader sense, it can refer to the sharing of political or ideological sentiments, such as in the phrase "a communist sympathiser".
The psychological state of sympathy is closely linked with that of empathy, but is not identical to it. Empathy is understanding and feeling another person's emotions as they feel them, but makes no statement as to how they are viewed.
Sympathy, by contrast, implies a degree of equal feeling, that is, the sympathiser views the matter similarly to how the person themselves does. It thus implies concern, or care or a wish to reduce negative feelings others are experiencing.
Puddle
A puddle is a small mass of liquid, usually water, uncontained on a surface. It can form either in depressions in the surface, or directly upon the flat surface, held together by surface tension. A puddle is generally considered to be small enough to step over or shallow enough to walk through, and too small to traverse with a boat.
Puddles commonly form during rainstorms, and can cause problems for transport, especially when combined with cold conditions to form patches of ice, which are highly slippery and difficult to see.
Beam (structure)
A beam is a structural element that carries structural load.
Beams generally carry vertical forces, but can also be used to carry horizontal loads (Those loads can result from wind or an earthquake). The loads that a beam carries are led to columns or walls, which lead the force to the next element.
Beams are characterized by their profile (their shape), their length, and their material. In constructions of today beams are mostly made of steel, reinforced concrete, or wood.
Load
Load may mean:
Organ (music)
In music, organ is a word that can mean several kinds of musical instruments. The word comes from the Greek ὄργανον "organon", which means "organ", "instrument", or "tool".
Most organs are played using keyboards, one or more of which may be played using the feet. They are found and used in churches, concert halls, and even in theatres, especially older movie theatres or cinemas. A person who plays the organ is called an organist.
Here are some different types of organs:
Pipe organs are the most common kind of organ, and many people mean this kind of organ when they use the word "organ". They sound different notes when air flows through pipes of different lengths and types. They take up a lot of room, and the noise they make are meant to fill large spaces.