ejaasaari/simplewiki-2025-04-01 huggingface dataset:
Thrust is a force or a push. When a system pushes or accelerates mass in one direction, there is a thrust (force) just as large in the opposite direction. In math and physics, this is described by Isaac Newton’s second and third laws. Thrust is used to describe how strongly an engine pushes. It can be used for many kinds of vehicles and engines such as rockets, motorboats, propellers, and jet engines. Thrust compared to power. A very common question is how to compare the thrust number of an airplane engine with the mechanical power of a piston engine (the kind of engine in cars and in many airplanes with propellers). It is hard to compare these two. This is because they are not measuring the same exact thing. A piston engine does not move the plane. It just turns the propeller, which moves the plane. Because of this, piston engines are rated by how much power they give to the propeller. However, a jet engine has no propeller – it pushes the aircraft by moving hot air behind it. A useful way to measure the power of a jet engine is to how much power the jet engine gives to the aircraft through its thrust force. This is called the “propulsive power of the jet engine." Power is how much force it takes to move something over a distance, divided by the time it takes to move that distance: formula_1, Where P is power, F is force, d is distance, and t is time. For a rocket or jet engine, the force is the same as thrust produced by the engine. Distance divided by time is also called speed. So power is the same as thrust times speed formula_2, Where T is thrust and "v" is speed. This is the power being delivered by the engine at a certain thrust or velocity. The propulsive power of a jet engine increases with its speed. Thrust compared to weight. When the thrust of a rocket or an engine is compared to the weight, it is called the Thrust-to-weight ratio. The number that comes from this comparison does not have any units, because it is a ratio. A ratio in this case means that the thrust of the engine (in
Thrust is a reaction force described by Newton's Second and Third Law. For this meaning, see Thrust. This word has other uses:
Robert Anson Heinlein (July 7, 1907 – May 8, 1988) was an American writer. He mostly wrote science fiction books. He won the Hugo Award four times. Probably his best-known novels are Starship Troopers (1959, Hugo Award, was made into a film), and Stranger in a Strange Land (1961, Hugo Award). Two other Hugo awards were for Double Star (1956) and The Moon is a Harsh Mistress (1966). Together with Isaac Asimov and Arthur C. Clarke he is seen as one of the "Big Three of Science Fiction". Heinlein employed his concept of the "World as Myth" in various works, notably his science fiction novel "The Number of the Beast," which features a device which navigates through Block Time (aka Eternalism) in a plenum of innumerable alternate universes.
A video game genre is category of related games based on their gameplay (the rules and action of a game). Unlike genres of movies and novels, these genres are not based on a game's setting, main characters, or plot elements. However, horror games have been counted as a genre.
A fable is a type of story which shows something in life or has a meaning to a word. A fable teaches a lesson or suggests a moral from it. A fable starts in the middle of the story, that means, jumps into the main event without detailed introduction of characters. The characters of a fable may be animals, plants and legendary creatures. When animals are used in fables, they think and talk like people, even though they act like animals. For example, in a fable a clay pot might say that it is frightened of being broken. The stories told by fables are usually very simple. To understand a fable, the reader or listener does not need to know all about the characters, only one important thing. For this reason animals are often used in fables in a way that is easily understood because it is always the same. They keep the same "characteristics" from story to story. The most famous fables are those attributed to Aesop (6th century B.C.). Many fables are so well known that their morals have become English sayings. For example: So, if a person sees a beautiful thing that they want, but cannot have, sometimes they say "I don't want it, anyway! I'll bet it is really no good!" This way of thinking is called ""sour grapes"." "Crying wolf" is another well-known English saying. This comes from "The Boy Who Cried Wolf". This fable is about a boy who was sent to mind the sheep. The boy got lonely while minding the sheep, so he shouted "Wolf! Wolf!" The people came running. The next day, he did it again and they were very angry. On the third day the boy saw a wolf. He cried "Wolf! Wolf!" but no one came and the wolf ate him. So if a person always makes a great fuss to get attention, or if a person says something bad has happened when it has not, then it is called "crying wolf" and people will stop bothering to pay attention, even when things go really wrong.
Drainage is the natural or artificial removal of surface and sub-surface water from a given area. Many agricultural soils need drainage to improve production or to manage water supplies. Early history. The earliest archaeological record of an advanced system of drainage comes from the Indus Valley Civilization from around 3100 BC in what is now Pakistan and North India. The ancient Indus systems of sewerage and drainage that were developed and used in cities throughout the civilization were far more advanced than any found in contemporary urban sites in the Middle East and even more efficient than those in some areas of modern Pakistan and India today. All houses in the major cities of Harappa and Mohenjo-daro had access to water and drainage facilities. Waste water was directed to covered drains, which lined the major streets. Reasons for artificial drainage. Wetland soils may need drainage to be used for agriculture. In the northern USA and Europe, glaciation created numerous small lakes which gradually filled with humus to make marshes. Some of these were drained using open ditches and trenches. The largest project of this type in the world has been in process for centuries in the Netherlands. The area between Amsterdam, Haarlem and Leiden was, in prehistoric times swampland and small lakes. Turf cutting (Peat mining), subsidence and shoreline erosion gradually caused the formation of one large lake, the Haarlemmermeer, or lake of Haarlem. The invention of wind powered pumping engines in the 15th century permitted drainage of some of the marginal land, but the final drainage of the lake had to await the design of large, steam powered pumps and agreements between regional authorities. The elimination of the lake occurred between 1849 and 1852, creating thousands of km2 of new land.
Empoldering is a method of reclaiming land from the sea or from inland lakes, and a way to control floods. Empoldering involves the use of a polder, a piece of land in a low-lying area that has been reclaimed from a body of water by building dikes and drainage canals. Although empoldering is usually carried out in low-lying coastal areas, it can also be done in inland areas such as lakes and rivers. It is common in countries like the Netherlands, where much of the country is below sea level and subject to flooding. About one-fifth of the land in the Netherlands has been reclaimed from the sea. Their largest and most successful project is the Zuiderzee Works. Polders have two distinct features. Firstly, they are enclosed by dikes to keep the water out. The dikes also serve to protect the polder from erosion. Secondly, polders are continually maintained by systems of drainage canals and pumps which prevent them from becoming waterlogged and hence, suitable for cultivation. Process. Stage 1: Dike constructed around the area to be reclaimed to keep water from coming in. Stage 2: The area is drained using pumps and drainage canals. Stage 3: "Reeds" (a type of salt tolerant plant) are sown by aircraft to help the soil form. Stage 4: After 3 years, reeds are burnt and the ash is used as fertilizers for the soil. Stage 5: After a period of up to 15 years, the polder is ready for growing crops, building houses and constructing roads. Limits of land reclamation. 1. Cost of reclaiming from deeper waters  2. Availability of sand  3. Dispute over territorial boundaries
A resistor limits the electric current that flows through a circuit. Resistance is the restriction of current. In a resistor the energy of the electrons that pass through the resistor are changed to heat and/or light. For example, in a light bulb, the tungsten filament acts as a resistor that heats up because of the current going through it, causing it to glow. Series and parallel. Resistors can be linked in various combinations to help make a circuit: There are many different types of resistors. Resistors have different power ratings to tell engineers how much power they can handle before they break and how accurate their value is. Connecting two resistors in series results in a higher resistance, and connecting them in parallel makes a lower resistance.  Nowadays the electrical industry in many cases uses so called surface-mount technology based resistors which can be very small. Calculating resistance. Where R is the resistor's value  Ohm’s Law. The formula for Ohm’s law, V=I*R, states that the voltage drop across a component is equal to the product of the current flowing in the component multiplied by the resistance of the component. When using Ohm’s law, you are able to switch the formula around if needed to find a different outcome: I=V/R or R=V/I  Color code. Resistor's values are rated by the colors that are painted on the resistor. The colored bands that are used on the sides of a resistor are black, brown, red, orange, yellow, green, blue, purple, gray, and white. Each color represents a different number. The black band represents the number 0, brown band represents the number 1, red is 2 and so on all the way to white which is the number 9. These numbers are very important in the electronic field. A resistor has multiple bands of color on its side. The most common have four or five but they can range all the way up to 6 per resistor. On a four band resistor, the last band is usually gold or silver. The gold band represents a positive or negative 5% tolerance. The silver band on a resistor represents a positive or negative 10% tolerance. Hold this band on the right
The Death Star is a fictional moon-sized space station and superweapon. It was invented for the "Star Wars" movies. It was a huge spherical space station which fired a ray of energy which could destroy a planet. Origin and design. The details of the Death Star changed between different models during production of '. These changes include the position of the superlaser. The idea of the Death Star as a large, spherical space station was the same in all the models. The sound of the Death Star counting down until it fires comes from the "Flash Gordon" movies from the 1930's. Making a Death Star that was only partly built (but was still powerful) was a problem for Industrial Light &amp; Magic's modelmakers for '. Only the front side of the 137-centimeter model was finished. The image was flipped horizontally for the final movie. The Death Star is a Super Weapon used by the Galactic Empire in Star Wars. Both Death Stars were created in the movies by using a full models, models of sections of the space station and matte paintings. Depiction. Movies. The first Death Star was shown in its finished form in "". It was commanded by Grand Moff Tarkin (Peter Cushing). The Death Star was the Galactic Empire's "ultimate weapon". The movie begins with Leia Organa (Carrie Fisher) attempting to take the station's plans to the Rebel Alliance, wanting to help them destroy the Death Star. Onboard her vessel, she was captured by an imperial ship and taken captive to the Death Star. There, Tarkin tries to make Leia reveal the location of the rebel base by threatening the use of the Death Star to destroy Leia's home world, Alderaan. She tells them a location but not the real one, but Tarkin has her planet destroyed anyway. Later, Luke Skywalker (Mark Hamill) and his small crew are also captured and taken to the station, escaping with Leia shortly after. In the movie's main battle scene, the force ghost of Obi-wan Kenobi tells Luke to use the "Force" to help him direct proton torpedoes from his x-wing into the Death Star' reactor core and not with his ship's targeting system. Luke obe
The Doctor of Philosophy, (PhD, Ph.D., DPhil or D.Phil.) is a degree which a person gets from a university by finishing a doctorate program. In many areas of study, the PhD / DPhil is the highest degree that a person can earn. This is called the "terminal degree". There are PhD / DPhil degrees for many different fields. Examples of these include PhDs / DPhils in literature, philosophy, history, science, mathematics and engineering. Some PhD / DPhil degrees have existed for hundreds of years, such as a PhD / DPhil in Canon Law. Other PhD / DPhil degrees were developed in the 1970s and 1980s, such as the PhD / DPhil in computer science. Requirements for degree. To be admitted to a PhD / DPhil program, a person usually has to have completed their Bachelor's degree or master's degree that is related to the PhD / DPhil degree. For example, a person applying to be admitted to a PhD / DPhil degree in theater would normally have to have a master's degree such as a Master of Arts (MA) degree in theater, English literature or a related area. Elements of a PhD / DPhil degree. The PhD / DPhil degree usually takes between three and six years of full-time study to complete. They may or may not require a master's degree beforehand. Many PhD / DPhil degrees begin with a period of graduate courses. After the PhD / DPhil student has taken these courses, they take examinations to test what the student knows about their area of study. After the student passes the exams, they begin to do original research. The product is a long research report called a dissertation (or a "thesis"). Some PhD / DPhil degrees also require students to pass exams in languages (such as French, German or other languages). Many PhD / DPhil students teach undergraduate students or assist professors with research during their PhD / DPhil studies. As a requirement for university teaching. Requirements for university teaching vary in different subjects and in different countries. A PhD / DPhil is necessary or usual to become a university professor in many fields, especially in science. However, many famous professors
The Global 200 is the list of ecoregions identified by the World Wide Fund for Nature (WWF) as priorities for conservation. According to the WWF, an ecoregion is defined as a "relatively large unit of land or water containing a characteristic set of natural communities that share a large majority of their species, dynamics, and environmental conditions (Dinerstein et al. 1995, TNC 1997)." The WWF assigns a conservation status to each ecoregion in the Global 200: critical or endangered; vulnerable; and relatively stable or intact. Over half of the ecoregions in the Global 200 are rated endangered.
An ecoregion (ecological region), sometimes called a bioregion, is the next smallest ecologically and geographically defined area beneath "realm" or "ecozone". Ecoregions cover relatively large area of land or water, and contain characteristic, geographically distinct natural communities and species. When defined by the World Wide Fund for Nature (WWF), the boundaries of an ecoregion approximate the original extent of the natural communities prior to any major recent disruptions or changes. The WWF has identified 825 terrestrial ecoregions, and approximately 450 freshwater ecoregions across the Earth. World Wide Fund for Nature's full definition of an ecoregion, which is widely accepted and used, is the following: "A large area of land or water that contains a geographically distinct assemblage of natural communities that "(a) share a large majority of their species and ecological dynamics;" "(b) share similar environmental conditions, and;" "(c) interact ecologically in ways that are critical for their long-term persistence." --"World Wide Fund for Nature - Ecoregions" The "Global 200" is the list of ecoregions identified by the World Wide Fund for Nature (WWF) as priorities for conservation. Terrestrial. A terrestrial ecoregion is a certain area of land which is different from the area near it. It has a distinct climate, geology, type of soil, water availability, and distinct living species (the animals and plants that live in the ecoregion). For example, one ecoregion can be a desert. It would have sand, very little water, very hot temperatures during the day and very cold at night. The plants could be just bushes, small trees, cactii. The animals could be scorpions, little mammals, spiders. Or for example, an ecoregion could be a tropical forest It would have warm temperatures all day, a lot of rainfall all year, a huge river crossing, and a very organic soil. The plants could be huge trees or ferns. The animals could be insects, birds, fish and apes. Marine. Marine ecoregions
In physical geography, a wetland is an environment that combines the properties of land and water. Wetlands are a distinct kind of ecosystem. The combination of wet and dry areas means that many more different kinds of plants, animals and insects may live in a wetland than compared to other types of habitat. Because of this great biodiversity, several important wetlands are among the Global 200 ecoregions that the Worldwide Fund for Nature listed for conservation to try to get people to protect them. As well, Ramsar Convention is adopted in 1971 for protection of wetland.
In geography, a marsh is a type of wetland. It has grasses, rushes, reeds, typhas, sedges, and other herbaceous plants (possibly with low-growing woody plants) in a context of shallow water. A marsh is different from a swamp, which has a greater proportion of open water surface, which is generally deeper than a marsh. In the US, the term 'swamp' is used for wetland dominated by trees rather than grasses and low herbs. The water of a marsh can be fresh, brackish or saline. Coastal marshes may be associated with estuaries and along waterways between coastal barrier islands and the inner coast. Estuarine marshes often are based on soils consisting of sandy bottoms or bay muds. Marshes are critically important wildlife habitat, often serving as breeding grounds for a wide variety of animal life.
Ulan-Ude (Russian:Ула́н-Удэ́; Buryat: Улаан-Үдэ), formerly Verkhneudinsk (), the capital city of the Buryat Republic, Russia. The city is located about 100 km south-east of Lake Baikal. It sits at the foot of the Khamar-Daban and Khrebet Ulan-Burgasy mountain ranges, next to the confluence of the Selenga River and its tributary, the Uda. The city is divided into two parts by the Uda. Population 359,391 (2002 Census); 352,530 (1989 Census). It is the third largest city in East Siberia. It is served by Ulan-Ude Airport (Mukhino) as well as the smaller Ulan-Ude Vostochny Airport. Ulan-Ude was founded in 1666 by the Russian Cossacks. Due to its geographical position, the city grew rapidly and became a large trade centre which connected Russia with China and Mongolia. There are old merchants' mansions richly decorated with wood and stone carving in the historical center of Ulan-Ude, along the river banks. They represent beautiful examples of Russian classicism. There is also a large and highly unusual head of Lenin in the central square.
The pelagic zone is the open sea or ocean that is not near the coast. The name comes from the Greek πέλαγος ("pélagos"), which might be translated as "open sea". To make this clear, seas around continents have continental crust beneath them. They are shallow. Seas away from continents can be very deep, and do not have continental shelves beneath them.  Sub-zones. The pelagic (or open ocean) zone is divided into a number of sub-zones: The last three zones are similar in character, and some marine biologists count them as a single zone or consider the latter two to be the one zone. Some define the hadopelagic as waters below 6000 meters, whether in a trench or not.
Vitamin A is a vitamin, a group of organic chemicals including retinal and several carotenoids. The human body does not make these chemicals, and must take them from food. Egg yolks and liver are both rich in vitamin A. Many parts of the body need vitamin A. For example, vitamin A helps sight and is good for the immune system. It is also important for a growing embryo. β-carotene, a provitamin found in foods like carrots can be converted to vitamin A. The efficiency of the conversion depends on genetics and fat consumption. Too little vitamin A is dangerous to health. People who do not get enough of the vitamin may lose the ability to see in poor light and suffer from a weakened immune system. They may also have problems with memory, because vitamin A is important for the brain. People with malnutrition often have too little vitamin A. This is common in poor countries. Hypervitaminosis A. Too much vitamin A is also dangerous to one's health. It is a condition known as hypervitaminosis. Vitamin A is not soluble in water, and the human body can not get rid of the excess vitamin A easily by urination. Too much vitamin A can make someone very sick. People may get too much vitamin A from taking too many vitamin pills or from eating too much A-rich food like liver. What applies to humans applies to all mammals at least. Some large predators, such as the big cats, seem not to eat their preys' livers. On the other hand, polar bears apparently do so, and they store vitamin A in their liver cells. However, they have long, sometimes very long, periods between kills. In contrast, African big cats kill about every three or four days, and they do seem to avoid eating the preys' livers.
Vitamin D is a hormone. It is a steroid which is made in the body under the right conditions. To make it, the body needs sunlight, which acts on the lower layers of the skin.  However, if the body does not make enough, it can be found from food sources in tiny amounts. In fact, many countries add it automatically to certain foods like milk. Supplements can be easily found in most developed countries. Vitamin D is a fat-soluble nutrient. This means that any portion not used immediately is stored in fat tissue for future use. What it does. As a hormone, Vitamin D does many things in the body. It was first discovered as the substance which could prevent and cure rickets. It controls the levels of calcium ions and phosphates in the blood, as well as calcium and magnesium absorption in the intestines. It helps bones grow and form. It is also good for the immune system. Different kinds. In total, there are 5 different forms, D1 to D5. The most common ones are D2 and D3 (see images). D3 (also called cholecalciferol) is the kind produced by the body. It is also found naturally in marine oils and in lanolin (oil from sheep's wool), the most common source for supplements. D2 (also called ergocalciferol) is produced by fungi. It is similar to D3, but not exactly the same. Getting enough. D3 is made in the skin from cholesterol, and changed into a more active form by the liver. However, the skin will not make it unless enough ultraviolet light shines on it. As sunlight contains ultraviolet light, getting enough sun is one way of getting enough D3. Many things can keep the skin from making enough D3. Winter sunlight may be too weak. Melanin, which protects skin from damage, also keeps it from making D3, which is why people with darker skin are more prone to deficiency. Older people are also prone, because aging skin makes less D3, even with enough sunlight. Clothing, glass, sunscreens and sunblocks also shield the skin from getting enough ultraviolet light to make D3.