A solar cell, or photovoltaic cell, is an electrical device that converts the energy of light directly into electricity by the photovoltaic effect, a physical and chemical phenomenon. It is a form of photoelectric cell, defined as a device whose electrical characteristics, such as current, voltage, or resistance, vary when exposed to light. Individual solar cell devices can be combined to form modules, otherwise known as solar panels. In basic terms a single junction silicon solar cell can produce a maximum open-circuit voltage of 0.5 to 0.6 volts. Solar cells are described as being photovoltaic, irrespective of whether the source is sunlight or an artificial light, they are used as a photodetector, detecting light or other electromagnetic radiation near the visible range, or measuring light intensity. The operation of a photovoltaic cell requires three basic attributes: The absorption of light, generating either electron-hole pairs or excitons; the separation of charge carriers of opposite types.
The separate extraction of those carriers to an external circuit. In contrast, a solar thermal collector supplies heat by absorbing sunlight, for the purpose of either direct heating or indirect electrical power generation from heat. A "photoelectrolytic cell", on the other hand, refers either to a type of photovoltaic cell, or to a device that splits water directly into hydrogen and oxygen using only solar illumination. Assemblies of solar cells are used to make solar modules that generate electrical power from sunlight, as distinguished from a "solar thermal module" or "solar hot water panel". A solar array generates solar power using solar energy. Multiple solar cells in an integrated group, all oriented in one plane, constitute a solar photovoltaic panel or module. Photovoltaic modules have a sheet of glass on the sun-facing side, allowing light to pass while protecting the semiconductor wafers. Solar cells are connected in series and parallel circuits or series in modules, creating an additive voltage.
Connecting cells in parallel yields a higher current. Strings of series cells are handled independently and not connected in parallel, though as of 2014, individual power boxes are supplied for each module, are connected in parallel. Although modules can be interconnected to create an array with the desired peak DC voltage and loading current capacity, using independent MPPTs is preferable. Otherwise, shunt diodes can reduce shadowing power loss in arrays with series/parallel connected cells; the photovoltaic effect was experimentally demonstrated first by French physicist Edmond Becquerel. In 1839, at age 19, he built the world's first photovoltaic cell in his father's laboratory. Willoughby Smith first described the "Effect of Light on Selenium during the passage of an Electric Current" in a 20 February 1873 issue of Nature. In 1883 Charles Fritts built the first solid state photovoltaic cell by coating the semiconductor selenium with a thin layer of gold to form the junctions. Other milestones include: 1888 – Russian physicist Aleksandr Stoletov built the first cell based on the outer photoelectric effect discovered by Heinrich Hertz in 1887.
1905 – Albert Einstein proposed a new quantum theory of light and explained the photoelectric effect in a landmark paper, for which he received the Nobel Prize in Physics in 1921. 1941 – Vadim Lashkaryov discovered p-n-junctions in Cu2O and Ag2S protocells. 1946 – Russell Ohl patented the modern junction semiconductor solar cell, while working on the series of advances that would lead to the transistor. 1954 – the first practical photovoltaic cell was publicly demonstrated at Bell Laboratories. The inventors were Daryl Chapin and Gerald Pearson. 1958 – solar cells gained prominence with their incorporation onto the Vanguard I satellite. Solar cells were first used in a prominent application when they were proposed and flown on the Vanguard satellite in 1958, as an alternative power source to the primary battery power source. By adding cells to the outside of the body, the mission time could be extended with no major changes to the spacecraft or its power systems. In 1959 the United States launched Explorer 6, featuring large wing-shaped solar arrays, which became a common feature in satellites.
These arrays consisted of 9600 Hoffman solar cells. By the 1960s, solar cells were the main power source for most Earth orbiting satellites and a number of probes into the solar system, since they offered the best power-to-weight ratio. However, this success was possible because in the space application, power system costs could be high, because space users had few other power options, were willing to pay for the best possible cells; the space power market drove the development of higher efficiencies in solar cells up until the National Science Foundation "Research Applied to National Needs" program began to push development of solar cells for terrestrial applications. In the early 1990s the technology used for space solar cells diverged from the silicon technology used for terrestrial panels, with the spacecraft application shifting to gallium arsenide-based III-V semiconductor materials, which evolved into the modern III-V multijunction photovoltaic cell used on spacecraft. Improvements were gradual over the 1960s.
This was the reason that costs remained high, becau
Cell is an apocalyptic horror novel by American author Stephen King, published in 2006. The story follows a New England artist struggling to reunite with his young son after a mysterious signal broadcast over the global cell phone network turns the majority of his fellow humans into mindless vicious animals. Clayton Riddell, a struggling artist from Maine, has just landed a graphic novel deal in Boston when "The Pulse", a signal sent out over the global cell phone network turns every cell phone user into a mindless zombie-like killer. Clay is standing in Boston Common. Civilization crumbles as the "phoners" attack each other and any unaltered people, including animals, in view. Amidst the chaos, Clay is thrown together with middle-aged Tom teenager Alice Maxwell; the next day, they learn the "phoners" have begun banding together. Clay is still determined to reunite with his young son, Johnny. Having no better alternatives and Alice come with him, they trek north by night across a devastated New England, having fleeting encounters with other survivors and catching disturbing hints about the activities of the phoners, who still attack non-phoners on sight.
Crossing into New Hampshire, they arrive at the Gaiten Academy, a prep school with one remaining teacher, Charles Ardai, one surviving pupil, Jordan. The pair show the newcomers where the local phoner flock goes at night: they pack themselves into the Academy's soccer field and "switch off" until morning, it is clear the phoners are developing psychic abilities. The five survivors decide they must destroy the flock and, using two propane tankers, they succeed in doing so. Clay tries to get everyone to flee the scene; that night, all of the survivors share the same horrific dream: each dreamer sees himself in a stadium, surrounded by phoners, as a disheveled man wearing a Harvard University hooded sweatshirt approaches, bringing their death. Waking, the heroes share their frightening dream experiences and dub him "the Raggedy Man". A new flock surrounds their residence, the "normies" face the flock's metaphorical spokesman: the man in the Harvard hoodie; the flock kills other normals in reprisal and orders the protagonists to head north to a spot in Maine called "Kashwak".
To stop their main objection, the flock psychically compels Ardai to commit suicide. Clay and the others travel north, as Clay is still determined to go home. En route, they learn that as "flock-killers" they have been psychically marked as untouchables, to be shunned by other normies. Following a petty squabble on the road, Alice is killed by a loutish pair of normies; the group buries her and arrives in Clay's hometown of Kent Pond, where they discover notes from Johnny which tell them Clay's estranged wife Sharon was turned into a phoner, but their son survived for several days, before he and the other normies were prompted by the phoners to head to the cell phone-free Kashwak. Clay has another nightmare which reveals that once there, the normie refugees were all exposed to the Pulse, he remains intent on finding his son, but after meeting another group of flock-killers and Jordan decide to avoid the ceremonial executions the phoners have planned. Before separating, the group discovers that Alice's murderers were psychically compelled into a gruesome suicide act for touching an untouchable.
Clay sets off alone. One of the flock-killers, construction worker Ray Huizenga, surreptitiously gives Clay a cell phone and a phone number, telling him to use them when the time is right; the group arrives at Kashwak, the site of a half-assembled county fair, where increasing numbers of phoners are beginning to behave erratically and break out of the flock. Jordan theorizes that a computer program caused the Pulse and that, while it is still broadcasting into the battery-powered cell phone network, it has become corrupted with a computer worm that has infected the newer phoners with a mutated Pulse. An entire army of phoners is waiting for them and Clay notices Sharon is among them; the phoners lock the group in the fair's exhibition hall for the night. As Clay awaits their morning execution, he sees Ray's unspoken plan: Ray had filled the rear of the bus with explosives, wired a phone-triggered detonator to them and killed himself to prevent the phoners from telepathically discovering the explosives.
The group breaks a window for Jordan to squeeze through and he drives the vehicle into the midst of the inert phoners. Thanks to a jury-rigged cell phone patch set up by the pre-Pulse fair workers, Clay is able to detonate the bomb and wipe out the Raggedy Man's flock; the majority of the group heads into Canada, to let the approaching winter wipe out the region's unprotected and leaderless phoners. Clay heads south, he finds Johnny. However, Johnny is an erratic shadow of his former self and so, following another theory of Jordan's, Clay decides to give Johnny another blast from the Pulse, hoping the corrupted signal will cancel itself out and reset his son's brain; the book ends with Clay's dialing and placing the cell phone to Joh
A storm cell is an air mass that contains up and down drafts in convective loops and that moves and reacts as a single entity, functioning as the smallest unit of a storm-producing system. Pulse storm Supercell Thunderstorm "A Comprehensive Glossary of Weather Terms For Storm Spotters". NOAA Technical Memorandum NWS SR-145. NOAA. Retrieved 2016-07-09
A prison cell known as a jail cell, is a small room in a prison or police station where a prisoner is held. Cells vary by their furnishings, hygienic services and cleanliness, both across countries and based on the level of punishment to which the prisoner has been sentenced; the International Committee of the Red Cross recommends. Prison cells vary in size internationally from 2 m2 in Guinea to 12 m2 in Switzerland. In the United States, prison cells are about 6 by 8 feet in dimension, with steel or brick walls and one solid or barred door that locks from the outside. Many modern prison cells are pre-cast. Solid doors may have a window. Furnishings and fixtures inside the cell are constructed so that they cannot be broken, are anchored to the walls or floor. Stainless steel lavatories and commodes are used; this prevents the making of weapons. There are a number of prison and prison cell configurations, from simple police-station holding cells to massive cell blocks in larger correctional facilities.
The practice of assigning only one inmate to each cell in a prison is called single-celling. In many countries, the cells are dirty and have few facilities. Other countries may house many offenders in prisons. In the United Kingdom, cells in a police station are the responsibility of the Custody Sergeant, who logs each detainee and allocates him or her an available cell. Custody Sergeants ensure cells are clean and as germ-free as possible, in accordance with the Human Rights Act of 1998. In the United States, the standard cell is equipped with either a ledge or a steel bedstead that holds a mattress. A one-piece sink/toilet constructed of welded, putatively stainless steel is provided. Bars typify older jails, while newer ones have doors that feature a small safety glass window and a metal flap that can be opened to serve meals. A limited number of United States prisons offer upgrades. Costing around $100 a night, these cells are considered cleaner and quieter, some of them offer extra facilities.
Different standards for cells exist in a single country and in a single jail. Some of those cells are reserved for "isolation", where a convict is kept alone in a cell as punishment method; some isolation cells contain no services at all. Celebrity Justice: Prison Lifestyles of the Rich and Famous, Matt Clarke 91111 Now
An electrochemical cell is a device capable of either generating electrical energy from chemical reactions or using electrical energy to cause chemical reactions. The electrochemical cells which generate an electric current are called voltaic cells or galvanic cells and those that generate chemical reactions, via electrolysis for example, are called electrolytic cells. A common example of a galvanic cell is a standard 1.5 volt cell meant for consumer use. A battery consists of one or more cells, connected either in parallel, series or series-and-parallel pattern. An electrolytic cell is an electrochemical cell that drives a non-spontaneous redox reaction through the application of electrical energy, they are used to decompose chemical compounds, in a process called electrolysis—the Greek word lysis means to break up. Important examples of electrolysis are the decomposition of water into hydrogen and oxygen, bauxite into aluminium and other chemicals. Electroplating is done using an electrolytic cell.
Electrolysis is a technique. An electrolytic cell has three component parts: two electrodes; the electrolyte is a solution of water or other solvents in which ions are dissolved. Molten salts such as sodium chloride are electrolytes; when driven by an external voltage applied to the electrodes, the ions in the electrolyte are attracted to an electrode with the opposite charge, where charge-transferring reactions can take place. Only with an external electrical potential of correct polarity and sufficient magnitude can an electrolytic cell decompose a stable, or inert chemical compound in the solution; the electrical energy provided can produce a chemical reaction which would not occur spontaneously otherwise. A galvanic cell, or voltaic cell, named after Luigi Galvani, or Alessandro Volta is an electrochemical cell that derives electrical energy from spontaneous redox reactions taking place within the cell, it consists of two different metals connected by a salt bridge, or individual half-cells separated by a porous membrane.
Volta was the inventor of the first electrical battery. In common usage, the word "battery" has come to include a single galvanic cell, but a battery properly consists of multiple cells. A primary cell is a Galvanic battery, designed to be used once and discarded, not recharged with electricity and reused like a secondary cell. In general, the electrochemical reaction occurring in the cell is not reversible, rendering the cell unrechargeable; as a primary cell is used, chemical reactions in the battery use up the chemicals that generate the power. In contrast, in a secondary cell, the reaction can be reversed by running a current into the cell with a battery charger to recharge it, regenerating the chemical reactants. Primary cells are made in a range of standard sizes to power small household appliances such as flashlights and portable radios. Primary batteries make up about 90% of the $50 billion battery market, but secondary batteries have been gaining market share. About 15 billion primary batteries are thrown away worldwide every year all ending up in landfills.
Due to the toxic heavy metals and strong acids or alkalis they contain, batteries are hazardous waste. Most municipalities require separate disposal; the energy needed to manufacture a battery is about 50 times greater than the energy. Due to their high pollutant content compared to their small energy content, the primary battery is considered a wasteful, environmentally unfriendly technology. Due to increasing sales of wireless devices and cordless tools which cannot be economically powered by primary batteries and come with integral rechargeable batteries, the secondary battery industry has high growth and has been replacing the primary battery in high end products. A secondary cell referred to as a rechargeable battery is an electrochemical cell that can be run as both a galvanic cell or as an electrolytic cell; this is used as a convenient way to store electricity, when current flows one way the levels of one or more chemicals build up, while it is discharging they reduce and the resulting electromotive force can do work.
A fuel cell is an electrochemical cell that converts the chemical energy from a fuel into electricity through an electrochemical reaction of hydrogen fuel with oxygen or another oxidizing agent. Fuel cells are different from batteries in requiring a continuous source of fuel and oxygen to sustain the chemical reaction, whereas in a battery the chemical energy comes from chemicals present in the battery. Fuel cells can produce electricity continuously for as long as oxygen are supplied; the first fuel cells were invented in 1838. The first commercial use of fuel cells came more than a century in NASA space programmes to generate power for satellites and space capsules. Since fuel cells have been used in many other applications. Fuel cells are used for primary and backup power for commercial and residential buildings and in remote or inaccessible areas, they are used to power fuel cell vehicles, including forklifts, buses, boats and submarines. There are many types of fuel cells, but they all consist of an anode, a cathode, an electrolyte that allows positively charged hydrogen ions to move between the two sides of the fuel cell.
At the anode a catalyst causes the fuel to undergo oxidation reactions that generate protons (positivel
Abstract cell complex
In mathematics, an abstract cell complex is an abstract set with Alexandrov topology in which a non-negative integer number called dimension is assigned to each point. The complex is called “abstract” since its points, which are called “cells”, are not subsets of a Hausdorff space as it is the case in Euclidean and CW complex. Abstract cell complexes play an important role in image computer graphics; the idea of abstract cell complexes relates to J. Listing und E. Steinitz. A. W Tucker, K. Reidemeister, P. S. Aleksandrov as well as R. Klette und A. Rosenfeld have described abstract cell complexes. E. Steinitz has defined an abstract cell complex as C = where E is an abstract set, B is an asymmetric and transitive binary relation called the bounding relation among the elements of E and dim is a function assigning a non-negative integer to each element of E in such a way that if B d i m < d i m. V. Kovalevsky described abstract cell complexes for 3D and higher dimensions, he suggested numerous applications to image analysis.
In his book he has suggested an axiomatic theory of locally finite topological spaces which are generalization of abstract cell complexes. The book contains among others new definitions of topological balls and spheres independent of metric, a new definition of combinatorial manifolds and many algorithms useful for image analysis; the topology of abstract cell complexes is based on a partial order in the set of its points or cells. The notion of the abstract cell complex defined by E. Steinitz is related to the notion of an abstract simplicial complex and it differs from a simplicial complex by the property that its elements are no simplices: An n-dimensional element of an abstract complexes must not have n+1 zero-dimensional sides, not each subset of the set of zero-dimensional sides of a cell is a cell; this is important since the notion of an abstract cell complexes can be applied to the two- and three-dimensional grids used in image processing, not true for simplicial complexes. A non-simplicial complex is a generalization which makes the introduction of cell coordinates possible: There are non-simplicial complexes which are Cartesian products of such "linear" one-dimensional complexes where each zero-dimensional cell, besides two of them, bounds two one-dimensional cells.
Only such Cartesian complexes make it possible to introduce such coordinates that each cell has a set of coordinates and any two different cells have different coordinate sets. The coordinate set can serve as a name of each cell of the complex, important for processing complexes. Abstract complexes allow the introduction of classical topology in grids being the basis of digital image processing; this possibility defines the great advantage of abstract cell complexes: It becomes possible to define the notions of connectivity and of the boundary of subsets. The definition of dimension of cells and of complexes is in the general case different from that of simplicial complexes; the notion of an abstract cell complex differs from that of a CW-complex because an abstract cell complex is no Hausdorff space. This is important from the point of view of computer science since it is impossible to explicitly represent a non-discrete Hausdorff space in a computer.. The book by V. Kovalevsky contains the description of the theory of locally finite spaces which are a generalization of abstract cell complexes.
A locally finite space S is a set of points where a subset of S is defined for each point P of S. This subset containing a limited number of points is called the smallest neighborhood of P. A binary neighborhood relation is defined in the set of points of the locally finite space S: The element b is in the neighborhood relation with the element a if b belongs to the smallest neighborhood of the element a. New axioms of a locally finite space have been formulated, it was proven that the space S is in accordance with the axioms only if the neighborhood relation is anti-symmetric and transitive; the neighborhood relation is the reflexive hull of the inverse bounding relation. It was shown. Therefore, a locally finite space satisfying the new axioms is a particular case of a classical topological space, its topology is a poset topology or Alexandrov topology. An abstract cell complex is a particular case of a locally finite space in which the dimension is defined for each point, it was demonstrated that the dimension of a cell c of an abstract cell complex is equal to the length of the maximum bounding path leading from any cell of the complex to the cell c.
The bounding path is a sequence of cells. The book contains the theory of digital straight segments in 2D complexes, numerous algorithms for tracing boundaries in 2D and 3D, for economically encoding the boundaries and for reconstructing a subset from the code of its boundary. A digital image may be represented by a 2D Abstract Cell Complex by decomposing the image into its ACC dimensional constituents: points, cracks/edges, pixels/faces; this decomposition together