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🔗 United States/U.S. Government 🔗 United States 🔗 Appalachia 🔗 National Archives 🔗 Tennessee 🔗 Energy 🔗 Alabama

The Tennessee Valley Authority (TVA) is a federally owned electric utility corporation in the United States. TVA's service area covers all of Tennessee, portions of Alabama, Mississippi, and Kentucky, and small areas of Georgia, North Carolina, and Virginia. While owned by the federal government, TVA receives no taxpayer funding and operates similarly to a private for-profit company. It is headquartered in Knoxville, Tennessee, and is the sixth-largest power supplier and largest public utility in the country.

The TVA was created by Congress in 1933 as part of President Franklin D. Roosevelt's New Deal. Its initial purpose was to provide navigation, flood control, electricity generation, fertilizer manufacturing, regional planning, and economic development to the Tennessee Valley, a region that had suffered from lack of infrastructure and even more extensive poverty during the Great Depression than other regions of the nation. TVA was envisioned both as a power supplier and a regional economic development agency that would work to help modernize the region's economy and society. It later evolved primarily into an electric utility. It was the first large regional planning agency of the U.S. federal government, and remains the largest.

Under the leadership of David E. Lilienthal, the TVA also became the global model for the United States' later efforts to help modernize agrarian societies in the developing world. The TVA historically has been documented as a success in its efforts to modernize the Tennessee Valley and helping to recruit new employment opportunities to the region. Historians have criticized its use of eminent domain and the displacement of over 125,000 Tennessee Valley residents to build the agency's infrastructure projects.

🔗 Technology

Deep borehole disposal (DBD) is the concept of disposing high-level radioactive waste from nuclear reactors in extremely deep boreholes instead of in more traditional deep geological repositories that are excavated like mines. Deep borehole disposal seeks to place the waste as much as five kilometres (3.1 mi) beneath the surface of the Earth and relies primarily on the thickness of the natural geological barrier to safely isolate the waste from the biosphere for a very long period of time so that it should not pose a threat to humans and the environment. The concept was originally developed in the 1970s, but in 2014 a proposal for a first experimental borehole was proposed by a consortium headed by Sandia National Laboratories.

The waste would be put into the lower mile of such a hole, within crystalline rock to isolate it from the environment. The upper two miles of the borehole would be filled with protective layers including asphalt, bentonite, concrete and crushed rock that are expected to protect the environment during geologic time, and the hole would be lined with steel casing.

A pair of proposed test boreholes in the United States were cancelled due to public opposition and lack of funding in 2016 and 2017.

🔗 Technology 🔗 Physics 🔗 Telecommunications 🔗 Radio 🔗 Electronics 🔗 Engineering

In antenna theory, a phased array usually means an electronically scanned array, a computer-controlled array of antennas which creates a beam of radio waves that can be electronically steered to point in different directions without moving the antennas. The general theory of an electromagnetic phased array also finds applications in ultrasonic and medical imaging application (phased array ultrasonics) and in optics optical phased array.

In a simple array antenna, the radio frequency current from the transmitter is fed to multiple individual antenna elements with the proper phase relationship so that the radio waves from the separate elements combine (superpose) to form beams, to increase power radiated in desired directions and suppress radiation in undesired directions. In a phased array, the power from the transmitter is fed to the radiating elements through devices called phase shifters, controlled by a computer system, which can alter the phase or signal delay electronically, thus steering the beam of radio waves to a different direction. Since the size of an antenna array must extend many wavelengths to achieve the high gain needed for narrow beamwidth, phased arrays are mainly practical at the high frequency end of the radio spectrum, in the UHF and microwave bands, in which the operating wavelengths are conveniently small.

Phased arrays were originally conceived for use in military radar systems, to steer a beam of radio waves quickly across the sky to detect planes and missiles. These systems are now widely used and have spread to civilian applications such as 5G MIMO for cell phones. The phased array principle is also used in acoustics, and phased arrays of acoustic transducers are used in medical ultrasound imaging scanners (phased array ultrasonics), oil and gas prospecting (reflection seismology), and military sonar systems.

The term "phased array" is also used to a lesser extent for unsteered array antennas in which the phase of the feed power and thus the radiation pattern of the antenna array is fixed. For example, AM broadcast radio antennas consisting of multiple mast radiators fed so as to create a specific radiation pattern are also called "phased arrays".

🔗 Computer science 🔗 Mathematics 🔗 Systems 🔗 Cryptography 🔗 Cryptography/Computer science 🔗 Systems/Operations research

The knapsack problem is a problem in combinatorial optimization: Given a set of items, each with a weight and a value, determine the number of each item to include in a collection so that the total weight is less than or equal to a given limit and the total value is as large as possible. It derives its name from the problem faced by someone who is constrained by a fixed-size knapsack and must fill it with the most valuable items. The problem often arises in resource allocation where the decision makers have to choose from a set of non-divisible projects or tasks under a fixed budget or time constraint, respectively.

The knapsack problem has been studied for more than a century, with early works dating as far back as 1897. The name "knapsack problem" dates back to the early works of mathematician Tobias Dantzig (1884–1956), and refers to the commonplace problem of packing the most valuable or useful items without overloading the luggage.

🔗 Linguistics 🔗 Linguistics/Etymology

OK (spelling variations include okay, O.K., and ok) is an English word (originally American English) denoting approval, acceptance, agreement, assent, acknowledgment, or a sign of indifference. OK is frequently used as a loanword in other languages. It has been described as the most frequently spoken or written word on the planet. The origins of the word are disputed.

As an adjective, OK principally means "adequate" or "acceptable" as a contrast to "bad" ("The boss approved this, so it is OK to send out"); it can also mean "mediocre" when used in contrast with "good" ("The french fries were great, but the burger was just OK"). It fulfills a similar role as an adverb ("Wow, you did OK for your first time skiing!"). As an interjection, it can denote compliance ("OK, I will do that"), or agreement ("OK, that is fine"). It can mean "assent" when it is used as a noun ("the boss gave her the OK to the purchase") or, more colloquially, as a verb ("the boss OKed the purchase"). OK, as an adjective, can express acknowledgement without approval. As a versatile discourse marker or back-channeling item, it can also be used with appropriate intonation to show doubt or to seek confirmation ("OK?", "Is that OK?").

🔗 Transhumanism 🔗 Alternative Views 🔗 Futures studies

American author, inventor and futurist Raymond Kurzweil has become well known for his predictions about artificial intelligence and the human species, mainly concerning the technological singularity. He predicts that Artificial Intelligence would outsmart the human brain in computational capabilities by mid-21st century. His first book, The Age of Intelligent Machines, published in 1990, put forth his theories on the results of the increasing use of technology and predicted the explosive growth in the internet, among other predictions. Later works, 1999's The Age of Spiritual Machines and 2005's The Singularity is Near outlined other theories including the rise of clouds of nano-robots (nanobots) called foglets and the development of Human Body 2.0 and 3.0, whereby nanotechnology is incorporated into many internal organs.

🔗 Robotics

Micromouse is an event where small robot mice solve a 16×16 maze. It began in the late 1970s. Events are held worldwide, and are most popular in the UK, U.S., Japan, Singapore, India, South Korea and becoming popular in subcontinent countries such as Sri Lanka.

The maze is made up of a 16×16 grid of cells, each 180 mm square with walls 50 mm high. The mice are completely autonomous robots that must find their way from a predetermined starting position to the central area of the maze unaided. The mouse needs to keep track of where it is, discover walls as it explores, map out the maze and detect when it has reached the goal. Having reached the goal, the mouse will typically perform additional searches of the maze until it has found an optimal route from the start to the finish. Once the optimal route has been found, the mouse will run that route in the shortest possible time.

Competitions and conferences are still run regularly.

🔗 Science Fiction 🔗 Business 🔗 Psychology 🔗 Anthropology 🔗 Hitchhiker's Guide to the Galaxy

"Somebody else's problem" (also "someone else's problem") is a phrase used to describe an issue which is dismissed by a person on the grounds that they consider somebody else to be responsible for it. The term is also used to refer to a factor that is "out of scope" in a particular context.

🔗 Linguistics 🔗 Linguistics/Theoretical Linguistics

An agglutinative language is a type of synthetic language with morphology that primarily uses agglutination. Words may contain different morphemes to determine their meanings, but all of these morphemes (including stems and affixes) remain, in every aspect, unchanged after their unions. This results in generally more easily deducible word meanings if compared to fusional languages, which allow modifications in either or both the phonetics or spelling of one or more morphemes within a word. This usually results in a shortening of the word, or it provides easier pronunciation.

Agglutinative languages have generally one grammatical category per affix while fusional languages have multiple. The term was introduced by Wilhelm von Humboldt to classify languages from a morphological point of view. It is derived from the Latin verb agglutinare, which means "to glue together".

Non-agglutinative synthetic languages are fusional languages; morphologically, they combine affixes by "squeezing" them together, drastically changing them in the process, and joining several meanings in a single affix (for example, in the Spanish word comí "I ate", the suffix -í carries the meanings of first person, singular number, past tense, perfective aspect, indicative mood, active voice.) The term agglutinative is sometimes incorrectly used as a synonym for synthetic. Used in this way, the term embraces both fusional languages and inflected languages. The agglutinative and fusional languages are two ends of a continuum, with various languages falling more toward one or the other end. For example, Japanese is generally agglutinative, but displays fusion in otōto (弟, younger brother), from oto+hito (originally woto+pito), and in its non-affixing verb conjugations. A synthetic language may use morphological agglutination combined with partial usage of fusional features, for example in its case system (e.g., German, Dutch, and Persian).

Agglutinative languages tend to have a high rate of affixes or morphemes per word, and to be very regular, in particular with very few irregular verbs. For example, Japanese has very few irregular verbs – only two are significantly irregular, and there are only about a dozen others with only minor irregularity; Ganda has only one (or two, depending on how "irregular" is defined); while in the Quechua languages, all the ordinary verbs are regular. Korean has only ten irregular forms of conjugation except for the passive and causative conjugations. Georgian is an exception; it is highly agglutinative (with up to eight morphemes per word), but it has a significant number of irregular verbs with varying degrees of irregularity.

An auto-antonym or autantonym, also called a contronym, contranym or Janus word, is a word with multiple meanings (senses) of which one is the reverse of another. For example, the word cleave can mean "to cut apart" or "to bind together". This phenomenon is called enantiosemy, enantionymy (enantio- means "opposite"), antilogy or autantonymy. An enantiosemic term is necessarily polysemic.