AcharyaChanakya/simple-wikipedia huggingface dataset:
Compressors are similar to pumps: both increase the pressure on a fluid and both can transport the fluid through a pipe. As gases are compressible, the compressor also reduces the volume of a gas. Liquids are relatively incompressible, so the main action of a pump is to transport liquids.
There are many different types of gas compressors. The two primary categories are:
The more important types in each of the four sub-categories are discussed below.
Centrifugal compressors use a vaned rotating disk or impeller in a shaped housing to force the gas to the rim of the impeller, increasing the velocity of the gas. A diffuser (divergent duct) section converts the velocity energy to pressure energy. They are primarily used for continuous, stationary service in industries such as oil refineries, chemical and petrochemical plants and natural gas processing plants. Their application can be from 100 hp (75 kW) to thousands of horsepower. With multiple staging, they can achieve extremely high output pressures greater than 10,000 psi (69 MPa).
Many large snow-making operations (like a ski resort) use this type of compressor. They are also used in internal combustion engines as superchargers and turbochargers. Centrifugal compressors are used in small gas turbine engines or as the final compression stage of medium-sized gas turbines.
Diagonal or mixed-flow compressors are similar to centrifugal compressors, but have a radial and axial velocity component at the exit from the rotor. The diffuser is often used to turn diagonal flow to the axial direction. The diagonal compressor has a lower diameter diffuser than the equivalent centrifugal compressor.
Axial-flow compressors use a series of fan-like rotating rotor blades to progressively compress the gasflow. Stationary stator vanes, located downstream of each rotor, redirect the flow onto the next set of rotor blades. The area of the gas passage diminishes through the compressor to maintain a roughly constant axial Mach number. Axial-flow compressors are normally used in high flow applications, such as medium to large gas turbine engines. They are almost always multi-staged. Beyond about 4:1 design pressure ratio, variable geometry is often used to improve operation.
Reciprocating compressors use pistons driven by a crankshaft. They can be either stationary or portable, can be single or multi-staged, and can be driven by electric motors or internal combustion engines. Small reciprocating compressors from 5 to 30 horsepower (hp) are commonly seen in automotive applications and are typically for intermittent duty. Larger reciprocating compressors up to 1000 hp are still commonly found in large industrial applications, but their numbers are declining as they are replaced by various other types of compressors. Discharge pressures can range from low pressure to very high pressure (>5000 psi or 35 MPa). In certain applications, such as air compression, multi-stage double-acting compressors are said to be the most efficient compressors available, and are typically larger, noisier, and more costly than comparable rotary units.
Rotary screw compressors use two meshed rotating positive-displacement helical screws to force the gas into a smaller space. These are usually used for continuous operation in commercial and industrial applications and may be either stationary or portable. Their application can be from 3 hp (2.24 kW) to over 500 hp (375 kW) and from low pressure to very high pressure (>1200 psi or 8.3 MPa). They are commonly seen with roadside repair crews powering air-tools. This type is also used for many automobile engine superchargers because it is easily matched to the induction capacity of a piston engine.
A scroll compressor, also known as scroll pump and scroll vacuum pump, uses two interleaved spiral-like vanes to pump or compress fluids such as liquids and gases. The vane geometry may be involute, archimedean spiral, or hybrid curves. They operate more smoothly, quietly, and reliably than other types of compressors.
Often, one of the scrolls is fixed, while the other orbits eccentrically without rotating, thereby trapping and pumping or compressing pockets of fluid between the scrolls.
A diaphragm compressor (also known as a membrane compressor) is a variant of the conventional reciprocating compressor. The compression of gas occurs by the movement of a flexible membrane, instead of an intake element. The back and forth movement of the membrane is driven by a rod and a crankshaft mechanism. Only the membrane and the compressor box come in touch with the gas being compressed.
Diaphragm compressors are used for hydrogen and compressed natural gas (CNG) as well as in a number of other applications.
Air compressors sold to and used by the general public are often attached on top of a tank for holding the pressurized air. Oil-lubricated and oil-free compressors are available. Oil-free compressors are desirable because without a properly designed separator, oil can make its way into the air stream. For some purposes, for example as a diving air compressor, even a little oil in the air stream may be unacceptable.
Charles's law says "when a gas is compressed, temperature is raised". There are three possible relationships between temperature and pressure in a volume of gas undergoing compression:
Since compression generates heat, the compressed gas is to be cooled between stages making the compression less adiabatic and more isothermal. The inter-stage coolers cause condensation meaning water separators with drain valves are present. The compressor flywheel may drive a cooling fan.
For instance in a typical diving compressor, the air is compressed in three stages. If each stage has a compression ratio of 7 to 1, the compressor can output 343 times atmospheric pressure (7 x 7 x 7 = 343 Atmospheres).
Gas compressors are used in various applications where either higher pressures or lower volumes of gas are needed:
In bookkeeping and finance, "cash" can also refer to checks, money orders, cashier's checks, bank drafts, or traveler's checks. In all these forms, the term indicates the most liquid form of assets, which have a fixed value and can be easily converted to currency: "ready money". For example, wages or salaries paid as "cash" (as opposed to, e.g., stock options) would in most countries normally be paid with checks or direct bank deposits, which are trivially convertible to currency.
Hemer
Heating is making something warm. It could mean:
HVACR "R" stand for Refrigeration
Heating devices, or systems:
Heat engine
In engineering and thermodynamics, a heat engine converts heat energy to mechanical work by using the temperature difference between a hot "source" and a cold "sink". Heat is transferred from the source, through the "working body" of the engine, to the "sink", and in this process some of the heat changes into work by using the qualities of the gas or liquid inside the engine.
There are many kinds of heat engines. Each has a thermodynamic cycle. Heat engines are often named after the thermodynamic cycle they use, like the Carnot cycle. They often pick up everyday names, such as gasoline/petrol, turbine, or steam engines.
Internal combustion engines generate heat inside the engine itself. Other heat engines may absorb heat from an external source. Heat engines can be open to the air or sealed and closed off to the outside (This is called an Open or Closed cycle).
When scientists study heat engines they come up with ideas for engines that cannot actually be built . These are called ideal engines or cycles. Real heat engines are often confused with the ideal engines or cycles they attempt to mimic.
Typically when describing the physical device the term 'engine' is used. When describing the ideal the term 'cycle' is used.
One could say that the thermodynamic cycle is an ideal case of the mechanical engine. One could equally say that the model does not quite perfectly match the mechanical engine. However, much benefit is gained from the simplified models, and ideal cases they may represent.
In general terms, the larger the difference in temperature between the hot source and the cold sink, the more efficient the cycle or engine. On Earth, the cold side of any heat engine is limited to the air temperature of the place where the engine is.
Most efforts to improve the efficiency of heat engines goes into increasing the temperature of the heat source, but at very high temperatures the metal of the engine begins to go soft.
The efficiency of various heat engines proposed or used today ranges from 3 percent (97 percent waste heat) for the OTEC ocean power proposal through 25 percent for most automotive engines, to 45 percent for a supercritical coal plant, to about 60 percent for a steam-cooled combined cycle gas turbine. All of these processes gain their efficiency (or lack thereof) due to the temperature drop across them.
The least efficient, OTEC, uses the temperature difference of ocean water on the surface and ocean water from the depths, a small difference of perhaps 25 degrees Celsius, and so the efficiency must be low.
The most efficient, the combined cycle gas turbine burns natural-gas to heat air to nearly 1530 degrees Celsius, a large temperature difference of 1500 degrees Celsius, and so the efficiency can be very large when the steam-cooling cycle is added.
People mostly use heat engines where the heat comes from a fire that expands a working fluid (usually either water or air) and the heat sink is either a body of water or the atmosphere as in a cooling tower.
Familiar ones that use the expansion of heated gases include: the steam engine, the diesel engine, and the gasoline (petrol) engine in an automobile.
The Stirling engine is much rarer but is found in small models which can run off the heat of a hand.
One kind of toy heat engine is the drinking bird.
A bimetallic strip is a device that converts temperature into mechanical movement and is used in thermostats to control temperature. It is a heat engine that does not use a liquid or gas.
Thermodynamic cycle
A thermodynamic cycle is a series of thermodynamic processes which returns a system to its initial state. Properties depend only on the thermodynamic state and thus do not change over a cycle. Variables such as heat and work are not zero over a cycle, but rather depend on the process. The first law of thermodynamics dictates that the net heat input is equal to the net work output over any cycle. The repeating nature of the process path allows for continuous operation, making the cycle an important concept in thermodynamics.
If the cyclic process moves clockwise around the loop, then it represents a heat engine, and W will be positive. If it moves counterclockwise then it represents a heat pump, and W will be negative.
Two primary classes of thermodynamic cycles are power cycles and heat pump cycles. Power cycles are cycles which convert some heat input into a mechanical work output, while heat pump cycles transfer heat from low to high temperatures using mechanical work input.
Thermodynamic power cycles are the basis for the operation of heat engines, which supply most of the world's electric power and run almost all motor vehicles. Power cycles can be divided according to the type of heat engine they seek to model. The most common cycles that model internal combustion engines are the Otto cycle, which models gasoline engines and the Diesel cycle, which models diesel engines. Cycles that model external combustion engines include the Brayton cycle, which models gas turbines, and the Rankine cycle, which models steam turbines.
Educational software links:
Christoph Metzelder
Christoph Metzelder (born 5 November 1980 in Haltern, Germany) is a German football player. He plays for Real Madrid In the Germany national team he has played in 47 matches and scored no goal.
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Thermodynamic system
In thermodynamics, a thermodynamic system, originally called a "working substance", is defined as that part of the universe that is under consideration. A real or imaginary boundary separates the system from the rest of the universe, which is referred to as the environment or surroundings (sometimes called a reservoir.) A useful classification of thermodynamic systems is based on the nature of the boundary and the quantities flowing through it, such as matter, energy, work, heat, and entropy. A system can be anything, for example a cylinder, a solution in a test tube, a living organism, or a planet, etc.
Treat could mean:
In general, a piston is a lubricated sliding shaft that fits tightly inside the opening of a cylinder. Its purpose is to change the volume enclosed by the cylinder, to exert a force on a fluid inside the cylinder, to cover and uncover ports, or some combination of these. A rubber seal is sometimes used to keep the lubricate within the shaft. Due to the constant motion of the machine this seal wears quickly and should be replaced with every servicing. If the seal should break during usage there can be disastrous long lasting consequences for the machine.
There are two ways that a piston engine can transform combustion into motive power. These are two-stroke and four-stroke.
A single cylinder two-stroke engine produces power every crankshaft revolution, while a single cylinder four-stroke engine produces power once every two revolutions. Older designs of small two-stroke engines produced more pollution than four stroke engines. However, modern two-stroke designs, like the Vespa ET2 Injection use fuel-injection and are as clean as four-strokes. Large diesel two-stroke engines, as used in ships and locomotives, have always used fuel injection and produce low emissions. One of the biggest internal combustion engines in the world, the Wärtsilä-Sulzer RTA96-C is a two-stroke; it is bigger than most two-story houses, has pistons nearly 1 metre in diameter and is one of the most efficient mobile engines in existence. In theory, a four stroke engine has to be larger than a two stroke engine to produce an equivalent amount of power. Two stroke engines are becoming less common in developed countries these days, mainly due to manufacturer reluctance to invest in reducing two-stroke emissions. Traditionally, two stroke engines were reputed to need more maintenance. Even though the simplest two stroke engines have fewer moving parts, they could wear out faster than four stroke engines. However fuel-injected two-strokes achieve better engine lubrication, and cooling and reliability should improve considerably.
A steam engine is another type of piston engine. In most steam engines, the pistons are "double acting": steam is alternately admitted to either end of the cylinder, so that every piston stroke produces power.
Pinyin is the Mandarin word for "spelling", writing letters showing the sound of a word in place of a Chinese character. Today, it almost always has the sense of Hanyu Pinyin, the way of writing Mandarin sounds which has been used by the People's Republic of China from the 1950s. Other countries like the United States and Taiwan used other ways of spelling Chinese (such as the Wade-Giles way) for a long time, but in the late 20th century started to use Hanyu Pinyin as well. It is the standard of China as well as the United Nations. It is the most common romanization system for Chinese.
Pinyin uses Roman letters in a special way for certain Chinese sounds. For example, the pinyin letter C is pronounced as /ts/ as in the English word "cats" or the Japanese word "tsunami", and does not sound at all like /k/ or /s/ by itself. Pinyin uses special marks to show the four Chinese tones, which are very important to using Mandarin clearly.
b p m f w
d t n l
g k ng h
j q x y
z c s
a e i o u ü
ai ei ao ou
an en ang eng ong
There are five kinds of tone in Pinyin:
ā, á, ǎ, à, a
"Geyin fuhao" is used after the syllables starting with vowels "a, o, e", for example: pi'ao.
We should divide Pinyin text by words and write syllables connectedly, such as "I am a foreigner" should be written as "Wo shi waiguoren" in Pinyin.
Susianna Kentikian
Banknote
A banknote (more commonly known as a bill in the United States and Canada) is a paper by which a bank promises to pay to the bearer on demand. Together with coins, banknotes make up the cash forms of all modern money.
Coins are generally used for lower valued monetary units, and banknotes for higher values.
Originally, the value of money was determined by the value of the material the money was made of, such as silver or gold. However, carrying around a lot of precious metal was cumbersome and often dangerous. As an alternative, banknotes would be issued. In financial terms, a note is a promise to pay someone money. Banknotes were originally a promise to give an amount of precious metal to anyone who presented the paper. People could pay for things by giving the banknote, and thus the stored value (usually in gold or silver coins kept in the bank's vault) that the banknote promised.
In Europe the first paper money consisted of paper 'coins' issued in Protestant Leyden (today, Leiden) in the Netherlands during the Spanish siege of 1574. Over 5000 of the estimated 14,000 residents of Leyden died, mostly due to starvation. Even leather (often used to create emergency currency) was boiled and used to feed the people. So to create currency, the residents took covers and paper from hymnals and church missives and created paper planchets, which were struck using the same dies that were previously used to mint coins.
The first proper European banknotes were issued by Stockholms Banco, a predecessor of the Bank of Sweden, in 1660, although the bank ran out of coins to redeem its notes in 1664 and ceased operating in that year.
Emergency paper money hand-written on playing cards was used in French Canada from 1685.
In the early 1690s, the Massachusetts Bay Colony was the first of the colonies to issue the permanently circulating banknotes. The use of fixed denominations and printed banknotes came into use in the 18th century.
In the United States, public acceptance of banknotes in replacement of precious metals was hastened in part by Executive Order 6102. This order carried the threat of a maximum $10,000 fine and a maximum of ten years in prison for anyone who kept more than $100 of gold in preference to bank notes. Similar measures were taken worldwide, with similar results.
Common cold
The common cold is caused by viruses. It spreads easily, so it is very infectious. The symptoms are mostly in the upper respiratory system. Its damage is mostly felt in the nose and throat. The symptoms include coughs, painful throat, runny nose and fever. These symptoms usually last seven to ten days, but sometimes up to three weeks. "Over two hundred different viruses can cause the common cold": that is why the details vary so much. Rhinoviruses are the most common cause.
The common cold mostly hurts the nose, pharynx, throat, and the sinuses (sinusitis). The symptoms come from the immune system's response to the infection, not from direct destruction by the viruses themselves. Hand washing is good, but the viruses also spread through moist air. Close contact with infected people is common in many cities. Wearing face masks might help, especially on any mass transit system (railways, underground, buses...).
There is no cure for the common cold, but the symptoms can be treated. It is the most frequent infectious disease in humans. The average person gets two to three colds every year. The average child gets between 6 and 12 colds every year. These colds have been with humans for as long as we have a history.
The most common symptoms of a cold are a cough, runny nose, a stuffy nose, and a sore throat. Other issues are sore muscles, feeling tired, headache, and not wanting to eat. Around 40% of people with colds have a sore throat, while around 50% have a cough. Muscle ache happens in about half of the cases. A fever is an uncommon symptom in adults, but it is common in infants and young children. The cough caused by a cold is usually mild compared to a cough caused by influenza (the flu). A cough and a fever indicate a higher likelihood of the flu in adults. A number of the viruses that cause the common cold may also result in no symptoms. The color of the mucus that is coughed up from the lungs (sputum) may vary in color from clear to yellow to green. This color does not indicate if an infection is caused by viruses or bacteria.
A cold usually begins with feeling tired, a feeling of being chilled, sneezing, and a headache. Additional symptoms such as runny nose and cough follow within two or more days. Symptoms typically reach their worst two to three days after the infection begins. Symptoms usually end after seven to ten days, but can last up to three weeks. The cough lasts for more than ten days in 35% to 40% of cases involving children. It lasts for more than 25 days in 10% of cases involving children.
The common cold is an easily spread infection of the upper respiratory tract. Rhinoviruses cause 30% to 80% of all cases. A rhinovirus is an RNA-containing virus. There are 99 known types of this kind of virus.
Other viruses can also cause the common cold. "Coronavirus" causes 10% to 15% of cases. The flu causes 5% to 15% of cases. Often, more than one virus is present and causing the infection. In total, over two hundred different viruses are associated with colds.
The common cold virus is usually spread in one of two main ways. By breathing or swallowing droplets in the air containing the virus; or by contacting infected nasal mucus or contaminated objects. The most common method of transmitting the cold virus has not been determined. The viruses may survive for a long time in the environment. Viruses may then be transmitted from the hands to the eyes or nose where infection occurs. People sitting close together appear at greater risk of becoming infected. Transmission is common in day cares and at schools, due to the closeness of many children with little immunity and frequently poor hygiene. These infections are then brought home to other members of the family. There is no evidence that the air on commercial flights transmits cold viruses. Rhinoviruses are most infectious in the first three days of cold symptoms. They are much less infectious afterwards.
The traditional theory was that the disease spread to someone staying too long in cold weather, rain, or winter conditions. This is how the disease got its name. The role of body cooling as a risk factor for the common cold is controversial. Some common cold viruses are seasonal, found more often in cold or wet weather. This is believed to mostly be due to more time spent indoors, close to each other; specifically children returning to school. Still, changes in the respiratory system may result in easier infections. Dry air may increase transmission rates by allowing small easily spread droplets to spread farther and stay in the air longer.
Herd immunity, immunity that occurs when an entire group of people become immune to a particular infection, occurs from previous exposure to cold viruses. Thus younger populations have greater rates of respiratory infections and older populations have lower rates of respiratory infections. Poor immune function is also a risk factor for disease. Lack of sleep and poor nutrition have also been associated with a greater risk of developing infection following rhinovirus exposure. This is believed to be due to their effects on immune function.
The symptoms of the common cold are believed to be mostly related to the immune response to the virus. The mechanism of this immune response is virus-specific. For example, the rhinovirus is typically acquired by direct contact. It binds to human ICAM-1 receptors through unknown methods to trigger the release of inflammatory mediators. These inflammatory mediators then produce the symptoms. It does not generally cause damage to the nasal epithelium.
In contrast, the respiratory syncytial virus (RSV) is contacted by both direct contact and airborne droplets. It then replicates in the nose and throat before frequently spreading to the lower respiratory tract. RSV does cause epithelium damage.
Human parainfluenza virus typically results in inflammation of the nose, throat, and airways. In young children, when it affects the trachea it may produce croup, a hoarse cough and difficulty breathing. This is due to the small size of the airway in children.
The distinction between different upper respiratory tract infections (URTIs) is loosely based on the location of the symptoms. The common cold primarily affects the nose, pharyngitis primarily affects the throat, and bronchitis primarily affects the lungs. The common cold is frequently defined as inflammation of the nose and may include varying amounts of throat inflammation. Self-diagnosis is common. Isolation of the actual viral agent involved is rarely performed. It is generally not possible to identify the specific virus through symptoms.
The only effective way to prevent the common cold is by physically preventing the spread of the viruses. This primarily includes hand washing and wearing face masks. In the health care environment, gowns and disposable gloves are also worn. Isolating infected individuals is not possible because the disease is so widespread and symptoms are not specific. Vaccination has proved difficult because there are so many viruses involved and the viruses undergo rapid change. Developing a broadly effective vaccine is very unlikely.
Regular hand washing reduces the spread of cold viruses. It is most effective and is especially recommended for use in children, due to a lack of evidence supporting the effectiveness of over-the-counter cold medicines for children, and due to the risk for harm from those medicines. In 2009, Canada restricted the use of over-the-counter cough and cold medication in children six years old and younger due to concerns regarding risks and unproven benefits. The misuse of dextromethorphan (an over-the-counter cough medicine) has led to its ban in a number of countries.
In adults, the symptoms of a runny nose can be reduced by first-generation antihistamines. However, first-generation antihistamines are associated with adverse side effects such as drowsiness. Other decongestants such as pseudoephedrine are also effective in adults. Ipratropium nasal spray may reduce the symptoms of a runny nose, but there is little effect on stuffiness. Second-generation antihistamines do not appear to be effective.
Due to the lack of studies, it is not known whether drinking more fluids improves symptoms or shortens respiratory illness. A similar lack of data exists for the use of heated humidified air. One study found chest vapor rub to be effective in providing some symptomatic relief of night-time cough, congestion, and sleep difficulty.
Antibiotics have no effect against viral infections and thus have no effect against the common cold. Antibiotics are often prescribed even though antibiotic side effects cause overall harm. Antibiotics are commonly prescribed because people expect doctors to prescribe them, and doctors want to help people. Prescribing antibiotics also happens because it is difficult to exclude causes of infection that may be managed by antibiotics. There are no effective antiviral drugs for the common cold, even though some preliminary research has shown benefit.
While there are many alternative treatments used for the common cold, there is not enough scientific evidence to support the use of most treatments. As of 2010, there is not enough evidence to recommend for or against either honey or nasal irrigation. Zinc supplements may reduce the severity and duration of symptoms when taken within 24 hours of their onset. The effect of vitamin C on the common cold, while extensively researched, is disappointing. Evidence about the usefulness of echinacea is inconsistent. Different types of echinacea supplements may vary in their effectiveness.
The common cold is generally mild and goes away on its own with most symptoms improving in one week. Severe complications, if they occur, are usually in the very old, the very young, or those who are immunosuppressed (have a weakened immune system). Secondary bacterial infections may occur resulting in sinusitis, pharyngitis, or an ear infection. It is estimated that sinusitis occurs in 8% of cases. Ear infections occur in 30% of cases.
The common cold is the most common human disease and people are affected all around the world. Adults typically have two to five infections per year. Children may have six to ten colds per year (and up to twelve colds per year for school children). Rates of symptomatic infections increase in the elderly due to a weakening immune system.
While the cause of the common cold has been known since only the 1950s, the disease has been with humanity since ancient times. Its symptoms and treatment are described in the Egyptian Ebers papyrus, the oldest existing medical text, written before the 16th century BC. The name "common cold" came into use in the 16th century, due to the similarity between its symptoms and those of exposure to cold weather.
In the United Kingdom, the Common Cold Unit (CCU) was set up by the Medical Research Council in 1946, and it was here that the rhinovirus was discovered in 1956. In the 1970s, the CCU demonstrated that treatment with interferon during the incubation phase of rhinovirus infection provided some protection against the disease. No practical treatment could be developed. The unit was closed in 1989, two years after it completed research of zinc gluconate lozenges in the prevention and treatment of rhinovirus colds. Zinc was the only successful treatment developed in the history of the CCU.
The economic impact of the common cold is poorly understood in much of the world. In the United States, the common cold leads to 75 million to 100 million physician visits annually, costing at least $7.7 billion per year (by conservative cost estimates). Americans spend $2.9 billion on over-the-counter (OTC) drugs. Americans spend an additional $400 million on prescription medicines for symptomatic relief. More than one-third of people who saw a doctor received an antibiotic prescription. The use of antibiotic prescriptions has implications for antibiotic resistance. An estimated 22 million to 189 million school days are missed each year due to a cold. As a result, parents missed 126 million workdays to stay home to care for their children. When added to the 150 million workdays missed by employees suffering from a cold, the total economic impact of cold-related work loss exceeds $20 billion per year. This accounts for 40% of time lost from work in the United States.
A number of antivirals have been tested for effectiveness in the common cold. As of 2009, none have been both found effective and licensed for use. There are ongoing trials of the antiviral drug pleconaril. It shows promise against picornaviruses. There are also ongoing trials of BTA-798. The oral form of pleconaril had safety issues and an aerosol form is being studied.
Researchers from the University of Maryland, College Park and the University of Wisconsin–Madison have mapped the genome for all known virus strains that cause the common cold.
Qajar dynasty
The Qajar dynasty (, - or دودمان قاجار - "Qâjâr") was a ruling Turkic dynasty of Iran from 1781 to 1925.
Soltan Ahmad Shah Qajar (1909-1925) was the last ruling Shah. Among many other members of the Qajar family are
Zenwalk Linux
Zenwalk (formerly Minislack), or Zenwalk Linux, is a Linux distribution started by Jean-Philippe Guillemin. It was at first based on Slackware. Since its creation, the distribution has become very different from Slackware while still still being able to use its binary packages. Zenwalk aims to be a Linux distribution with many uses by focusing on Internet applications, multimedia and programming tools.
The Zenwalk Project aims to create a Linux operating system that can be used on old and slow computers through the use of the latest software available for a stable release, optimization for a specific processor architecture to increase execution speed, and introduces a very powerful package management system with dependency resolution.
There are four main versions of Zenwalk:
Zenwalk (full version ~ 420 MB iso download) is a distribution aimed at mainstream desktop use. Designed to be a stand-alone operating system, it installs to the hard drive by way of a ncurses-based installer. It includes all of the officially released software packages that are deemed most useful for their tasks. This collection may change with every release.
Zenwalk Core (~ 230 MB iso download) is a Zenwalk system built with customization in mind. Released with no X Window System binaries, its aim is to allow a skilled user to build a system fit for his or her needs. The project's lead developer is Emmanuel Bailleul.
ZenLive (~ 476 MB iso download) is a Zenwalk system built on a Live CD design. ZenLive follows the progress made by the full Zenwalk system closely, thus mirroring the version number, and attempts to stay true to the original distribution's goals. In addition, it includes all of the necessary libraries and applications to develop and compile software, a particularly rare feature in Live CD distributions. Project members include Pierrick Le Brun, creator, Mauricio Tricoli, project lead, and Michael Verret, artwork.
Zenserver (~ 263 MB iso download) is a Zenwalk Core-derived system specifically designed for servers. The main goals are to create a secure, reliable, easy to use, easy to configure, expandable and dependable server operating system, in the best Zenwalk tradition. The distribution development team is led by Teran McKinney.
There are currently four Zenwalk-based distributions:
Thermodynamic equilibrium
Thermodynamic potential
In thermodynamics, thermodynamic potentials are parameters associated with a thermodynamic system and have the dimensions of energy. They are called "potentials" because in a sense, they describe the amount of potential energy in a thermodynamic system when it is subjected to certain constraints. The different potentials correspond to different constraints to which the system may be subjected. The four most common thermodynamic potentials are:
where "T" = temperature, "S" = entropy, "p" = pressure, "V" = volume. The Helmholtz free energy is often denoted by the symbol "F", but the use of "A" is preferred by IUPAC (See Alberty, 2001). formula_1 is the number of particles of type "i" in the system. For the sake of completeness, the set of all formula_1 are also included as natural variables, although they are sometimes ignored.
Thermodynamic potentials are very useful when calculating the equilibrium results of a chemical reaction, or when measuring the properties of materials in a chemical reaction. The chemical reactions usually take place under some simple constraints such as constant pressure and temperature, or constant entropy and volume, and when this is true, there is a corresponding thermodynamic potential which comes into play. Just as in mechanics, the system will tend towards lower values of potential and at equilibrium, under these constraints, the potential will take on an unchanging minimum value. The thermodynamic potentials can also be used to estimate the total amount of energy available from a thermodynamic system under the appropriate constraint.
Thermal efficiency
The thermal efficiency (formula_1) is a dimensionless performance measure of a thermal device such as an internal combustion engine, a boiler, or a furnace, for example.
The input, formula_2, to the device is heat, or the heat-content of a fuel that is consumed. The desired output is mechanical work, formula_3, or heat, formula_4, or possibly both. Because the input heat normally has a real financial cost, a memorable, generic definition of thermal efficiency is
From the first and second law of thermodynamics, the output can not exceed what is input, so
When expressed as a percentage, the thermal efficiency must be between 0% and 100%. Due to inefficiencies such as friction, heat loss, and other factors, thermal efficiencies are typically much less than 100%. For example, a typical gasoline automobile engine operates at around 25% thermal efficiency, and a large coal-fueled electrical generating plant peaks at about 36%. In a combined cycle plant thermal efficiencies are approaching 60%.
When transforming thermal energy into mechanical energy, the thermal efficiency of a heat engine is the percentage of energy that is transformed into work. Thermal efficiency is defined as
or via the first law of thermodynamics to substitute waste heat rejection for the work produced,
For example, when 1000 joules of thermal energy is transformed into 300 joules of mechanical energy (with the remaining 700 joules dissipated as waste heat), the thermal efficiency is 30%.
For an energy conversion device like a boiler or furnace, the thermal efficiency is
So, for a boiler that produces 210 kW (or 700,000 BTU/h) output for each 300 kW (or 1,000,000 BTU/h) heat-equivalent input, its thermal efficiency is 210/300 = 0.70, or 70%. This means that the 30% of the energy is lost to the environment.
An electric resistance heater has a thermal efficiency of at or very near 100%, so, for example, 1500W of heat are produced for 1500W of electrical input. When comparing heating units, such as a 100% efficient electric resistance heater to an 80% efficient natural gas-fueled furnace, energy prices must be compared to find the lower cost.
Heat pumps, refrigerators, and air conditioners, for example, move heat, rather than convert it, so other measures are needed to describe their thermal performance. The common measures are the coefficient-of-performance (COP), energy-efficiency ratio (EER), and seasonal-energy-efficiency ratio (SEER).
The Efficiency of a Heat pump (HP) and Refrigerators (R)*:
If temperatures at both ends of the Heat Pump or Refrigerator are constant and their processes reversible:
The 'thermal efficiency' is sometimes called the energy efficiency. In the United States, in everyday usage the SEER is the more common measure of energy efficiency for cooling devices, as well as for heat pumps when in their heating mode. For energy-conversion heating devices their peak steady-state thermal efficiency is often stated, e.g., 'this furnace is 90% efficient', but a more detailed measure of seasonal energy effectiveness is the Annual Fuel Utilization Efficiency (AFUE).
Thermodynamic state
A thermodynamic state is the macroscopic condition of a thermodynamic system as described by its particular thermodynamic parameters. The state of any thermodynamic system can be described by a set of thermodynamic parameters, such as temperature, pressure, density, composition, independently of its surroundings or history.
The parameters required to specify the state depend on the characteristics of the system. There is an optimal ensemble of parameters that uniquely specify the state, and all other parameters can be derived from these. The "state postulate" says that the state of a simple compressible system is completely specified by two independent, intensive properties.
Thermal physics
Thermal physics is the combined study of thermodynamics, statistical mechanics, and kinetic theory. This umbrella-subject is typically designed for physics students and functions to provide a general introduction to each of three core heat-related subjects. Other authors, however, define thermal physics loosely as a summation of only thermodynamics and statistical mechanics.
Thermal physics, generally speaking, is the study of the statistical nature of physical systems from an energetic perspective. Starting with the basics of heat and temperature, thermal physics analyzes the first law of thermodynamics and second law of thermodynamics from the statistical perspective, in terms of the number of microstates corresponding to a given macrostate. In addition, the concept of entropy is studied via quantum theory.
A central topic in thermal physics is the canonical probability distribution. The electromagnetic nature of photons and phonons are studied which show that the oscillations of electromagnetic fields and of crystal lattices have much in common. Waves form a basis for both, provided one incorporates quantum theory.
Other topics studied in thermal physics include: chemical potential, the quantum nature of an ideal gas, i.e. in terms of fermions and bosons, Bose-Einstein condensation, Gibbs free energy, Helmholtz free energy, chemical equilibrium, phase equilibrium, the equipartition theorem, entropy at absolute zero, and transport processes as mean free path, viscosity, and conduction.
There are two types of thermodynamic instruments, the meter and the reservoir. A thermodynamic meter is any device which measures any parameter of a thermodynamic system. In some cases, the thermodynamic parameter is actually defined in terms of an idealized measuring instrument. For example, the zeroth law states that if two bodies are in thermodynamic equilibrium with a third body, they are also in thermodynamic equilibrium with each other. This principle, as noted by James Maxwell in 1872, asserts that it is possible to measure temperature. An idealized thermometer is a sample of an ideal gas at constant pressure.
A thermodynamic reservoir is a system which is so large that it does not appreciably alter its state parameters when brought into contact with the test system.
It is important that these two types of instruments are distinct. A meter does not perform its task accurately if it behaves like a reservoir of the state variable it is trying to measure. If, for example, a thermometer, were to act as a temperature reservoir it would alter the temperature of the system being measured, and the reading would be incorrect. Ideal meters have no effect on the state variables of the system they are measuring.
Statistical mechanics is the application of probability theory, which includes mathematical tools for dealing with large populations, to the field of mechanics, which is concerned with the motion of particles or objects when subjected to a force.
It provides a framework for relating the microscopic properties of individual atoms and molecules to the macroscopic or bulk properties of materials that can be observed in everyday life, therefore explaining thermodynamics as a natural result of statistics and mechanics (classical and quantum) at the microscopic level. In particular, it can be used to calculate the thermodynamic properties of bulk materials from the spectroscopic data of individual molecules.
This ability to make macroscopic predictions based on microscopic properties is the main asset of statistical mechanics over thermodynamics. Both theories are governed by the second law of thermodynamics through the medium of entropy. However, entropy in thermodynamics can only be known empirically, whereas in statistical mechanics, it is a function of the distribution of the system on its micro-states.
Kinetic theory
Kinetic theory or "kinetic theory of gases" attempts to explain overall properties of gases, such as pressure, temperature, or volume, by considering their molecular composition and motion. The theory basically states that pressure is not caused by molecules pushing each other away, like earlier scientists thought. Instead, pressure is caused by the molecules colliding with each other and their container. Kinetic theory is also known as "kinetic-molecular theory" or "collision theory".
There are three main components to kinetic theory:
The main postulate of this theory are--
1.The particles attract each other with a force. This force is called cohesive force if the particles are of same kind and adhesive force when particles are of different kinds.
2. All matter is composed of small particles called molecules. (Atoms or ions as the situation demands).
3. The particles are in a state of unending motion (continuous motion) and as such have kinetic energy.
4. with the supply of heat energy (thermal energy) to matter, the kinetic energy of a particle increase, i.e., they start moving more vigorously. Reverse happens if the matter is cooled.i.e., heat energy is taken out of it.
5. The force of attraction between the particles decreases, if the distance between them increases and vice versa.
Last updated Sat,16 May 2020
9:00 pm
By Rachit Vishwakarma
Frik
Mongolian might mean:
Yeghishe Charents
Yeghishe Charents (born Yeghishe Soghomonian, ) (13 March 1897, Kars - 29 November 1937, Yerevan) was an Armenian poet killed in Stalin's purges.
From 1904 to 1912 Yeghishe Soghomonian he was at school in Kars. Amid the upheavals of the First World War and the Armenian Genocide in the Ottoman Empire, he volunteered in 1915 for the Caucasian Front. In 1917-1918 he was in Karin Erzurum during the bitter fighting. Some of his experiences would later appear in his poetry.
Yeghishe Charents (Soghomonian), one of the nation's favourite poets - a famous philanderer who apparently sought the USSR Kremlin's favours - produced a now famous poem called "The Message". Its praise of Uncle Joe might grind the average set of teeth down to the gum; it included the following: "A new light shone on the world... It is only this sunlight/Which for centuries will stay alive." And more of the same.
Undiscovered by the USSR Kremlin's censors for many months, however, Charents (1897 - 1937) had used the first letter of each line to frame a quite different "message", which read: "O Armenian people, your only salvation is in the power of your unity." Whoops! Like the distant Mount Ararat, it was a brave, hopeless symbol, as doomed as it was impressive. Yeghishe Charents was "disappeared" by the NKVD (KGB) in 1937 after being denounced by the architect Alexsandr Tamanyan - now hard at work building Yerevan's new Stalinist opera house - the moment Yeghishe Charents' schoolboy prank was spotted. Then Alexsandr Tamanyan fell from the roof of his still unfinished opera house, and even today Armenians - with their Arab-like desire to believe in "заговор" the plot - ask the obvious questions.
"Three songs to the sad and pale girl", poems (1914)
"Blue-eyed Homeland", poem (1915)
"Soma", poem (1918) Yerevan
"Charents-Name", poem (1922)
"Uncle Lenin", poem (1924)
"Country of Nayiri" (Yerkir Nayiri) (1926)
"Epical Sunrise", poems (1930)
"Book of the Way", poems (1934)
Kars
Kars (, ) is a city in northeast Turkey and is the capital of the Kars Province, before at the head of a sanjak in the Turkish vilayet of Erzurum. Population: 8,672 (1878); 20,891 (1897); 54,000 (1970); 142,145 (1990); 130,361 (2000).
The early history of Kars is little known, beyond that it had its own dynasty of Armenian rulers and was the capital of a region known as Vanand. At some point in the 9th century (at least by 888) it became part of the territory of the Armenian Bagratids. For a short time (from 928 to 961) Kars became the capital of their kingdom. It was during this period that the Cathedral, later known as the Church of the Apostles, was built.
Kars Province
Kars is a province of Turkey. It is in the northeastern part of the country. It shares part of its border with the Republic of Armenia.
From 1878 until 1917 most of the present-day Turkish province of Kars was part of the Russian oblast of Kars.
In 1919 and 1920 the province came under the control of the Democratic Republic of Armenia as the Vanand province (with the city of Kars as its capital). Its territory was ceded to Turkey by the Soviet Union in the Treaty of Kars.
Kars province is divided into 8 districts ("ilçe"), each named after the administrative center of the district:
There are 383 villages in Kars.
Manny Gamburyan
Manvel Gamburyan (was born in 1981) is a mixed martial artist with a history in judo. Manvel was chosen as a participant on the reality show "The Ultimate Fighter 5". He fights on Jens Pulver's team. Manny defeated Noah Thomas in the preliminary round.
In May, 1991, Manvel's family relocated from Armenia to United States. Shortly after his arrival, Manvel began training in judo at Gokor Chivichyan's Hayastan MMA Academy and quickly became one of the top judokas in the country, winning junior nationals less than two years later. He went on to win junior nationals eight times, the junior Olympics once, and was a member of the 2000 judo junior world team.
The Mickey Mouse Club
The Mickey Mouse Club was an American variety television series that began in 1955, ran intermittently, and left the air in 1996. It was directed by Walt Disney Productions.