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What is superconductivity?
Superconductivity is a phenomenon observed in several metals and ceramic materials. When these materials are cooled to temperatures ranging from near absolute zero ( 0 degrees Kelvin. -273 degrees Celsius) to liquid nitrogen temperatures (77 K. -196 C). their electrical resistance drops with a jump down to zero. The cooling of the materials is achieved using liquid nitrogen or liquid helium for even lower temperatures. While superconductivity at low temperature is well understood, there is no clear explanation as yet of this phenomena at "high temperatures".
The critical temperature is known to be inversely proportional to the square root of the atomic mass. Electrical resistance in metals arises because electrons moving through the metal arc scattered due to deviations from translational symmetry. These are produced either by impurities, giving raise to a temperature independent contribution to the resistance, or by the vibrations of the lattice in the metal.
In a superconductor below its critical temperature, there is no resistance because these scattering mechanisms are unable to impede the motion of the current carriers. As a negatively-charged electron moves through the space between two rows of positivety-charged atoms, it pulls inward on the atoms of the lattice. This distortion attracts a second electron to move in behind ЎL An electron in the lattice can interact with another electron by exchanging an acoustic quanta called phonon. Phonons in acoustics are analogous to photons in electromagnetic The energy of a phonon is usually less than 0.1 eV (electron-volt) and thus is one or two orders of magnitude less than that of a photon.
Thus superconductivity is an electrical resistance of exactly zero which occurs in certain materials below a characteristic temperature. It was discovered by Heike Kamerlinch Onnes in 1911. Like ferromagnetism and atomic spectral lines, superconductivity is a quantum mechanical phenomenon. It is also characterized by a phenomenon called the Meissner effect the ejection of any sufficiently weak magnetic field from the interior of the superconductor as it transitions into the superconducting state. The occurrence of the Meissner effect indicates that superconductivity cannot be understood simply as the idealization of perfect conductivity in classical physics.
The electrical resistivity of a metallic conductor decreases gradually as the temperature is lowered. However, in ordinary conductors such as copper and silver, this decrease is limited by impurities and other defects. Even near absolute zero, a real sample of copper shows some resistance. Despite these imperfections, in a superconductor the resistance drops abruptly to zero when the material is cooled below its critical temperature. An electric current flowing in a loop of superconducting wire can persist indefinitely with no power source.
In 1986. it was discovered that some cuprate-perovskite ceramic materials have critical temperatures above 90 K (?I83 °С). These high-temperature superconductors renewed interest in the topic because of the prospects for improvement and potential room-temperature superconductivity. From a practical perspective, even 90 K is relatively easy to reach with readily available liquid nitrogen (which has a boiling point of 77 K). resulting in more experiments and applications.
There is not just one criterion to classify superconductors. The most common are: By their physical properties: they can be Type I (if their phase transition is of first order) or Type Ц (if their phase transition is of second order); By the theory to explain them: they can be conventional (if they are explained by the BCS theory or its derivatives) or unconventional (if not); By their critical temperature: they can be high temperature or low temperature (generally if they need other techniques to be cooled under their critical temperature); By material: they can be chemical elements (as mercury or lead), alloys, ceramics, or organic superconductors, which technically might be included among the chemical elements as they are made of carbon

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Драмарецька. Роздатки 14032012. Група 3.

[GorbachenkoVasyl]

Text: Cryogenics
In physics, cryogenics is the study of the production of very low temperature (below -ISO °C, -238 °F or 123 K) and the behavior of materials at those temperatures. A person who studies elements under extremely cold temperature is called a cryogeniсist Rather than the familiar temperature scales of Fahrenheit and Celsius, cryogenicists use the Kelvin scale (formerly also Rankine scale).
The word cryogenics stems from Greek and means "the production of freezing cold";
however the term is used today as a synonym for the low-temperature state. It is not well-defined at what point on the temperature scale refrigeration ends and cryogenics begins, but moat scientists assume it starts at or below -240 °F (about -150 °C or 123 fC). The National Institute of Standards and'Technology at Boulder, Colorado has chosen to consider the field of cryogenics as that involving temperatures below -180 °C (93.13 K) This is a logical dividing line, since the normal boiling points of the so-called permanent gases (such as helium, hydrogen, aeon, nitrogen, oxygen, and normal air) lie below -180 °C while the Freon refrigerants, hydrogen sulfide, and other common refrigerants have boiling points above -180 -c
Liquefied gases, such as liquid nitrogen and liquid helium, are used in many cryogenic applications. Liquid nitrogen is the most commonly used element in cryogenics and is legally purchasable around the world. Liquid helium is also commonly used and allows for the lowest attainable temperatures to be reached. These liquids are held in either special containers known as Dewar flasks, which are generally about six feet tall (1.8 m) and three feet (91.5cm) in diameter, or giant tanks in larger commercial operations. Dewar flasks are named after their inventor, James Dewar, the man who first liquefied hydrogen. Museums typically display smaller vacuum flasks fitted in a protective casing.
The field of cryogenics advanced during World War II when scientists found that metals frozen to low temperatures showed more resistance to wear. Based on this theory of cryogenic hardening, the commercial cryogenic processing industry was founded in 1966 by Ed Busch. With a background in the heat treating industry, Busch founded a company in Detroit called CryoTech in 1966. Though CryoTech later merged with 300 Below to create the largest and oldest commercial cryogenics company in the world, they originally experimented with the possibility of increasing the life of metal tools to anywhere between 200%-4O0% of the original life expectancy using cryogenic tempering instead of heat treating. Using liquid nitrogen, Cryo-Tech formulated the first early version of the cryogenic processor.
• Cryogens. tike liquid nitrogen, are further used for specialty- chilling and freezing applications. Special cryogenic chemical reactors are used to remove reaction hear and provide a low temperature environment. The freezing of foods and biotechnology products, like vaccines, requires nitrogen in blast freezing or immersion freezing systems. Certain soft or elastic materials become hard and brittle at very low temperatures, which makes cryogenic milling (cryomilling) an option for some materials that cannot easily be milled at higher temperatures.
Another use of cryogenics is cryogenic fuels- Cryogenic fuels, mainly liquid hydrogen, have -been used as rocket fuels. Liquid oxygen is used as an oxidizer of hydrogen, but oxygen is not, strictly speaking, a fuel. For example, NASA's workhorse space shuttle-uses cryogenic hydrogen fuel as its primary means of getting into orbit, as did all of the rockets built for the Soviet space program by Sergei Korolev. (This was a bone of contention between him and rival engine designer Valentin Glushko, who felt that cryogenic fuels were impractical for large-scale rockets such as the ill-fated N-1 rocket spacecraft.)
Russian aircraft manufacturer Tupolev developed a version of its popular design Tu-154 with a cryogenic fuel system, known as the Tu-155 The plane uses a fuel referred to as liquefied natural gas or LNQ, and made its first flight in 1989.
Some applications of cryogenics are Magnetic Resonance Imaging: MR! is used to scan internal organs of human body by generating very intense magnetic field. This magnetic field is generated by superconducting coils with the help of liquid helium.
Power Transmission in Big Cities: It is difficult to transmit power by over head cables in big cities. So underground cables ate used. But underground cables get heated and the resistance of the wire increases leading to wastage of power. This can be solved by cryogenics. Liquefied gases are sprayed on the cables to keep them cool and reduce their resistance.
Food Freezing: Cryogenic gases are used in transportation of large masses of frozen food When very large quantity of food must be transported to regions like war field, earthquake bit regions etc they must be stored for a long time. So cryogenic food freezing is used. Cryogenic food freezing is also helpful for large scale food processing industries. L
Blood Banking. Certain blood groups which are rare are stored at very low temperatures like -165 degree C.

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Драмарецька. Роздатки 21032012. Група 3.

[Obi-Van]

Титова, 1 група

Automation of Scientific Research

The advantages of automation in manufacturing and industry are well known. Since the introduction of division of labour in the 18th century mechanization of repetitive tasks has resulted in greater productivity and also reliability through the eradication of human error. The introduction of the electronic computer in the 20th century advanced automation yet further, with machines able to self- regulate through complex feedback loops. It is becoming increasingly desirable to translate this rend of automation to the process of scientific research to cope with the number of large, high- dimensional data problems now commonly found in most disciplines.
The extent of automation possible for a particular scientific investigation is usually constrained by he need for human intervention at the decision-making level, where different sources of information need to be drawn together and combined with expert knowledge to define a future strategy. This is the traditional role of the scientist. Artificial intelligence is the branch of computer science that aims to emulate these human learning and decision-making abilities.
Our brains do not work in terms of numbers, but use abstract and visual concepts; hence, communication between computer and man boomed when computers escaped the world of numbers to reach a visual interface. From this time on, computers have generated new knowledge and. more importantly for teaching, new ways to grasp concepts. Therefore, just as real experiments were the starting point for theory, virtual experiments can be used to understand theoretical concepts. But there are important differences. Some of them are fundamental: a virtual experiment may allow for die exploration of length and time scales together with a level of microscopic complexity not directly accessible to conventional experiments. Others are practical: numerical experiments are completely safe, unlike some dangerous but essential laboratory experiments, and are often less expensive. Finally, some numerical approaches are suited only to teaching, as the concept necessary far the physical problem, or its solution, lies beyond the scope of traditional methods. For all these reasons, computers open physics courses to novel concepts, bringing education and research closer.
Physics "deals with matter and energy and their interactions" (Webster) across a range of fields, including electricity, magnetism, and optics. These three fields correspond closely with the key ingredients in a modem computer: microelectronics, storage, and displays. Thus it is no surprise that physics plays a key role in IBM, spanning the entire range of computer technology. Some of our physics research is aimed at improving and further developing existing technologies. Other projects hope to overthrow existing technology and create new paradigms that will continue to drive the information revolution. Some research areas make use of the tremendous computational power now available to solve "grand challenge" problems such as protein folding, or they utilize deep, specialized knowledge developed at IBM to explain long standing riddles in areas such as 3stronomy. The interplay between physics and computers has benefited both sides - a situation that is not likely to change anytime soon.

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ДРАМАРЕЦЬКА. МЕЙЛ.
Automation of Scientific Research
CRYOGENICS
MEDICAL PHYSICS

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Група 3. Драмарецька. Розкдатки 28032012
http://radfiz.org.ua/files/k2/s4//E ... _28032012/

[Obi-Van]

Титова, 1 група

Cryogenics is a branch of phvsics (or engineering) that studies the production of very low temperatures (below -150 °C, -23S °F or 123 K) and the behavior of materials at those temperatures. The brandies of physics and engineering study very low temperatures, how to pioduce them, and how materials behave at those temperatures. Rather than the familiar temperature scales of Fahrenheit and Celsius, cryogenicists use the Kelvin and Rankine scales. The word cryogenics literally means "the production of icy cold"; however the term is used today as. a synonym for the low-temperature state. It is not well-defined at what point on the temperature scale refrigeration ends and cryogenics begins. The workers at the National Institute of Standards and Technology at Boulder. Colorado have chosen to consider the field of cryogenics as that involving temperatures below -180 (93.15 K). This is a logical dividing line, since the normal boiling points of the so- called permanent gases (such as helium, hydrogen. neon, nitrogen. oxygen. and normal air) lie below -180 °C while the Freon refrigerants, hydrogen sulfide, and other common refrigerants have ‘ boiling points above -180 °C. Recent research regarding superconductivity at low temperatures has been called cryoelectronics, and the utilization of these sciences is called crvotronics.
Liquefied gases: such as liquid nitrogen and liquid helium, are used in many cryogenic applications. Liquid nitrogen is the most commonly used element in cryogenics and is legally purchasable around the world. Liquid helium is also commonly used and allows lor the lowest attainable temperatures to be .reached. These gases are held in either special containers known as Dewar flasks, which are generally about six feet tall (1.8 m) and thiee feet (01.5 cm) in diameter, or giant tanks in larger commercial operations. Dewar flasks arc named after their inventor, James Dewar, the man who first liquified hydrogen. Museums typically display smaller vacuum flasks fitted in a protective casing. Cryogenic transfer pumps are the pumps used on LNG piers to transfer Liquefied Natural Gas from LNG Carriers to LNG storage tanks. Cryogens, like liquid nitrogen, are further used for specialty chilling and freezing applications. Some chemical reactions, like those used to produce the active ingredients for the popular statin drugs, must occur at low temperatures of approximately • 100 °C. Special cryogenic chemical reactors are used to remove reaction heat and provide a low temperature environment. The freezing of foods and biotechnology products, like vaccines, requires nitrogen in blast freezing or immersion freezing systems. Certain soft or elastic materials become hard and brittle at very low temperatures, which makes cryogenic milling (grinding) an option for some materials that cannot easily be milled at higher temperatures. The mechanical properties of materials can be modified through cryogenic process inti. The generation of high vacuum in various industrial processes is often achieved through the use of cryopumps which remove free floating molecules of gas from a volume by trapping them on cryogenically cooled surfaces.
Another use of cryogenic; is cryogenic JufilS- Cryogenic fuels, mainly oxygen and hydrogen, have been used as rocket fuels. For example, NASA’s workhorse space shuttle uses cryogenic oxygen and hydrogen fuels as its primary means of getting into orbit, as did all of the rockets built for the Soviet space program by Sergei Korolev (this was a bone of contention between him and rival engine designer Valentin Glushko, who felt that cryogenic fuels were impractical for large-scale rockets such as the ill-fated N-l- rocket spacecraft). India is actively developing cyrogenics for space research. An indigenous cryogenic stage developed by the Indian Space Research Organisation (ISRO) was successfully tested on the ground in August 2007 for a duration of eight minutes at the Liquid Propulsion Systems Centre (LPSC) at Mahendragiri. near Nagercoil in Tamil Nadu Russian aircraft manufacturer Turtolev is currently researching a version of its popular design Tu-154 with a: cryogenic fuel system, known as the Tu-155. The plane uses a fuel referred to as liquefied natura gas orLNG. and made its first flight in 1989.

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Роздатки. Драмарецька. 18042012
ТУТ

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Automation of scientific research
http://en.wikipedia.org/wiki/Automation
http://en.wikipedia.org/wiki/Laboratory_automation