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Crackling Noise
Crackling noise arises when a system is subject to an external force and it responds via events that appear very similar at many different scales. In a classical system there are usually two states, on and off. However, sometimes a state can exist in between. There are three main categories this noise can be sorted into: the first is ''popping'' where events at very similar magnitude occur continuously and randomly, e.g. popcorn; the second is ''snapping'' where there is little change in the system until a critical threshold is surpassed, at which point the whole system flips from one state to another, e.g. snapping a pencil; the third is ''crackling'' which is a combination of popping and snapping, where there are some small and some large events with a relation law predicting their occurrences, referred to as universality. Crackling can be observed in many natural phenomena, e.g. crumpling paper, fire, occurrences of earthquakes and the magnetisation of magnets. Some of these s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Campfire 4213
A campfire is a fire at a campsite that provides light and warmth, and heat for cooking. It can also serve as a beacon, and an insect and predator deterrent. Established campgrounds often provide a stone or steel fire ring for safety. Campfires are a popular feature of camping. At summer camps, the word campfire often refers to an event (ceremony, get together, etc.) at which there is a fire. Some camps refer to the fire itself as a campfire. History First campfire A new analysis of burned antelope bones from caves in Swartkrans, South Africa, confirms that ''Australopithecus robustus'' and/or '' Homo erectus'' built campfires roughly 1.6 million years ago. Nearby evidence within Wonderwerk Cave, at the edge of the Kalahari Desert, has been called the oldest known controlled fire. Microscopic analysis of plant ash and charred bone fragments suggests that materials in the cave were not heated above about . This is consistent with preliminary findings that the fires burned g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mercalli Intensity Scale
The Modified Mercalli intensity scale (MM, MMI, or MCS), developed from Giuseppe Mercalli's Mercalli intensity scale of 1902, is a seismic intensity scale used for measuring the intensity of shaking produced by an earthquake. It measures the effects of an earthquake at a given location, distinguished from the earthquake's inherent force or strength as measured by seismic magnitude scales (such as the "" magnitude usually reported for an earthquake). While shaking is caused by the seismic energy released by an earthquake, earthquakes differ in how much of their energy is radiated as seismic waves. Deeper earthquakes also have less interaction with the surface, and their energy is spread out across a larger volume. Shaking intensity is localized, generally diminishing with distance from the earthquake's epicenter, but can be amplified in sedimentary basins and certain kinds of unconsolidated soils. Intensity scales empirically categorize the intensity of shaking based on the ef ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supply And Demand
In microeconomics, supply and demand is an economic model of price determination in a Market (economics), market. It postulates that, Ceteris paribus, holding all else equal, in a perfect competition, competitive market, the unit price for a particular Good (economics), good, or other traded item such as Labour supply, labor or Market liquidity, liquid financial assets, will vary until it settles at a point where the quantity demanded (at the current price) will equal the quantity supplied (at the current price), resulting in an economic equilibrium for price and quantity transacted. The concept of supply and demand forms the theoretical basis of modern economics. In macroeconomics, as well, the AD–AS model, aggregate demand-aggregate supply model has been used to depict how the quantity of real GDP, total output and the aggregate price level may be determined in equilibrium. Graphical representations Supply schedule A supply schedule, depicted graphically as a supply cu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fat-tailed Distribution
A fat-tailed distribution is a probability distribution that exhibits a large skewness or kurtosis, relative to that of either a normal distribution or an exponential distribution. In common usage, the terms fat-tailed and heavy-tailed are sometimes synonymous; fat-tailed is sometimes also defined as a subset of heavy-tailed. Different research communities favor one or the other largely for historical reasons, and may have differences in the precise definition of either. Fat-tailed distributions have been empirically encountered in a variety of areas: physics, earth sciences, economics and political science. The class of fat-tailed distributions includes those whose tails decay like a power law, which is a common point of reference in their use in the scientific literature. However, fat-tailed distributions also include other slowly-decaying distributions, such as the log-normal. The extreme case: a power-law distribution The most extreme case of a fat tail is given by a distrib ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Return On Investment
Return on investment (ROI) or return on costs (ROC) is a ratio between net income (over a period) and investment (costs resulting from an investment of some resources at a point in time). A high ROI means the investment's gains compare favourably to its cost. As a performance measure, ROI is used to evaluate the efficiency of an investment or to compare the efficiencies of several different investments.Return On Investment – ROI , Investopedia as accessed 8 January 2013 In economic terms, it is one way of relating profits to invested. Purpos ...
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Upper Mantle (Earth)
The upper mantle of Earth is a very thick layer of rock inside the planet, which begins just beneath the crust (at about under the oceans and about under the continents) and ends at the top of the lower mantle at . Temperatures range from approximately at the upper boundary with the crust to approximately at the boundary with the lower mantle. Upper mantle material that has come up onto the surface comprises about 55% olivine, 35% pyroxene, and 5 to 10% of calcium oxide and aluminum oxide minerals such as plagioclase, spinel, or garnet, depending upon depth. Seismic structure The density profile through Earth is determined by the velocity of seismic waves. Density increases progressively in each layer, largely due to compression of the rock at increased depths. Abrupt changes in density occur where the material composition changes. The upper mantle begins just beneath the crust and ends at the top of the lower mantle. The upper mantle causes the tectonic plates to move. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tipping Point (climatology)
In climate science, a tipping point is a critical threshold that, when crossed, leads to large and often irreversible changes in the climate system. If tipping points are crossed, they are likely to have severe impacts on human society. Tipping behaviour is found across the climate system, in ecosystems, ice sheets, and the circulation of the ocean and atmosphere. Tipping points are often, but not necessarily, abrupt. For example, with average global warming somewhere between 0.8 and 3 °C, the Greenland ice sheet passes a tipping point and is doomed, but the melt would take place over millennia. Tipping points are possible at today's global warming of just over 1 °C above preindustrial times, and highly probable above 2 °C of global warming. The geological record shows many abrupt changes that suggest tipping points may have been crossed in ancient times. It is possible that some tipping points are close to being crossed or have already been crossed, like tho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cellular Automaton
A cellular automaton (pl. cellular automata, abbrev. CA) is a discrete model of computation studied in automata theory. Cellular automata are also called cellular spaces, tessellation automata, homogeneous structures, cellular structures, tessellation structures, and iterative arrays. Cellular automata have found application in various areas, including physics, theoretical biology and microstructure modeling. A cellular automaton consists of a regular grid of ''cells'', each in one of a finite number of '' states'', such as ''on'' and ''off'' (in contrast to a coupled map lattice). The grid can be in any finite number of dimensions. For each cell, a set of cells called its ''neighborhood'' is defined relative to the specified cell. An initial state (time ''t'' = 0) is selected by assigning a state for each cell. A new ''generation'' is created (advancing ''t'' by 1), according to some fixed ''rule'' (generally, a mathematical function) that determines the new state o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2D Cellular Automaton
D, or d, is the fourth letter in the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is English alphabet#Letter names, ''dee'' (pronounced ), plural ''dees''. History The Semitic languages, Semitic letter Daleth, Dāleth may have developed from the logogram for a fish or a door. There are many different Egyptian hieroglyphs that might have inspired this. In Semitic, Ancient Greek and Latin, the letter represented ; in the Etruscan alphabet the letter was archaic, but still retained (see letter B). The equivalent Greek letter is Delta, Delta (letter), Δ. Architecture The Lower case, minuscule (lower-case) form of 'd' consists of a lower-story left Typeface anatomy#Strokes, bowl and a Typeface anatomy#Strokes, stem ascender. It most likely developed by gradual variations on the upper case, majuscule (capital) form 'D', and today now composed as a stem with a full Typeface anat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gutenberg–Richter Law
In seismology, the Gutenberg–Richter law (GR law) expresses the relationship between the magnitude and total number of earthquakes in any given region and time period of ''at least'' that magnitude. : \!\,\log_ N = a - b M or : \!\,N = 10^ where * \!\, N is the number of events having a magnitude \!\, \ge M , * \!\, a and \!\, b are constants, i.e. they are the same for all values of ''N'' and ''M''. Since magnitude is logarithmic, this is an instance of the Pareto distribution. The Gutenberg–Richter law is also widely used for acoustic emission analysis due to a close resemblance of acoustic emission phenomenon to seismogenesis. Background The relationship between earthquake magnitude and frequency was first proposed by Charles Francis Richter and Beno Gutenberg in a 1944 paper studying earthquakes in California, and generalised in a worldwide study in 1949. This relationship between event magnitude and frequency of occurrence is remarkably common, although the v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Richter Magnitude Scale
The Richter scale —also called the Richter magnitude scale, Richter's magnitude scale, and the Gutenberg–Richter scale—is a measure of the strength of earthquakes, developed by Charles Francis Richter and presented in his landmark 1935 paper, where he called it the "magnitude scale". This was later revised and renamed the local magnitude scale, denoted as ML or . Because of various shortcomings of the original scale, most seismological authorities now use other similar scales such as the moment magnitude scale () to report earthquake magnitudes, but much of the news media still erroneously refers to these as "Richter" magnitudes. All magnitude scales retain the logarithmic character of the original and are scaled to have roughly comparable numeric values (typically in the middle of the scale). Due to the variance in earthquakes, it is essential to understand the Richter scale uses logarithms simply to make the measurements manageable (i.e., a magnitude 3 quake factors 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
