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๐Ÿ”— Terfenol-D

๐Ÿ”— Military history ๐Ÿ”— Military history/Military science, technology, and theory ๐Ÿ”— Chemistry

Terfenol-D, an alloy of the formula TbxDy1โˆ’xFe2 (xย โ‰ˆย 0.3), is a magnetostrictive material. It was initially developed in the 1970s by the Naval Ordnance Laboratory in United States. The technology for manufacturing the material efficiently was developed in the 1980s at Ames Laboratory under a U.S. Navy-funded program. It is named after terbium, iron (Fe), Naval Ordnance Laboratory (NOL), and the D comes from dysprosium.

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๐Ÿ”— Pรณlya Urn Model

๐Ÿ”— Statistics

In statistics, a Pรณlya urn model (also known as a Pรณlya urn scheme or simply as Pรณlya's urn), named after George Pรณlya, is a type of statistical model used as an idealized mental exercise framework, unifying many treatments.

In an urn model, objects of real interest (such as atoms, people, cars, etc.) are represented as colored balls in an urn or other container. In the basic Pรณlya urn model, the urn contains x white and y black balls; one ball is drawn randomly from the urn and its color observed; it is then returned in the urn, and an additional ball of the same color is added to the urn, and the selection process is repeated. Questions of interest are the evolution of the urn population and the sequence of colors of the balls drawn out.

This endows the urn with a self-reinforcing property sometimes expressed as the rich get richer.

Note that in some sense, the Pรณlya urn model is the "opposite" of the model of sampling without replacement, where every time a particular value is observed, it is less likely to be observed again, whereas in a Pรณlya urn model, an observed value is more likely to be observed again. In both of these models, the act of measurement has an effect on the outcome of future measurements. (For comparison, when sampling with replacement, observation of a particular value has no effect on how likely it is to observe that value again.) In a Pรณlya urn model, successive acts of measurement over time have less and less effect on future measurements, whereas in sampling without replacement, the opposite is true: After a certain number of measurements of a particular value, that value will never be seen again.

One of the reasons for interest in this particular rather elaborate urn model (i.e. with duplication and then replacement of each ball drawn) is that it provides an example in which the count (initially x black and y white) of balls in the urn is not concealed, which is able to approximate the correct updating of subjective probabilities appropriate to a different case in which the original urn content is concealed while ordinary sampling with replacement is conducted (without the Pรณlya ball-duplication). Because of the simple "sampling with replacement" scheme in this second case, the urn content is now static, but this greater simplicity is compensated for by the assumption that the urn content is now unknown to an observer. A Bayesian analysis of the observer's uncertainty about the urn's initial content can be made, using a particular choice of (conjugate) prior distribution. Specifically, suppose that an observer knows that the urn contains only identical balls, each coloured either black or white, but he does not know the absolute number of balls present, nor the proportion that are of each colour. Suppose that he holds prior beliefs about these unknowns: for him the probability distribution of the urn content is well approximated by some prior distribution for the total number of balls in the urn, and a beta prior distribution with parameters (x,y) for the initial proportion of these which are black, this proportion being (for him) considered approximately independent of the total number. Then the process of outcomes of a succession of draws from the urn (with replacement but without the duplication) has approximately the same probability law as does the above Pรณlya scheme in which the actual urn content was not hidden from him. The approximation error here relates to the fact that an urn containing a known finite number m of balls of course cannot have an exactly beta-distributed unknown proportion of black balls, since the domain of possible values for that proportion are confined to being multiples of 1 / m {\displaystyle 1/m} , rather than having the full freedom to assume any value in the continuous unit interval, as would an exactly beta distributed proportion. This slightly informal account is provided for reason of motivation, and can be made more mathematically precise.

This basic Pรณlya urn model has been enriched and generalized in many ways.

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๐Ÿ”— Slopsquatting

๐Ÿ”— Computer Security ๐Ÿ”— Computer Security/Computing

Slopsquatting is a type of cybersquatting. It is the practice of registering a non-existent software package name that a large language model (LLM) may hallucinate in its output, whereby someone unknowingly may copy-paste and install the software package without realizing it is fake. Attempting to install a non-existent package should result in an error, but some have exploited this for their gain in the form of typosquatting.

The name is a portmanteau of "slop" and "typosquatting".

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๐Ÿ”— Bloom's Taxonomy

๐Ÿ”— Psychology ๐Ÿ”— Education

Bloom's taxonomy is a set of three hierarchical models used to classify educational learning objectives into levels of complexity and specificity. The three lists cover the learning objectives in cognitive, affective and sensory domains. The cognitive domain list has been the primary focus of most traditional education and is frequently used to structure curriculum learning objectives, assessments and activities.

The models were named after Benjamin Bloom, who chaired the committee of educators that devised the taxonomy. He also edited the first volume of the standard text, Taxonomy of Educational Objectives: The Classification of Educational Goals.

๐Ÿ”— Kensington Security Slot

๐Ÿ”— Computing ๐Ÿ”— Computing/Computer hardware ๐Ÿ”— Computing/Computer Security

A Kensington Security Slot (also called a K-Slot or Kensington lock) is part of an anti-theft system designed in the early 1990s and patented by Kryptonite in 1999โ€“2000, assigned to Schlage in 2002, and since 2005 owned and marketed by Kensington Computer Products Group, a division of ACCO Brands.

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๐Ÿ”— Mode 2

๐Ÿ”— History of Science

A knowledge production mode is a term from the sociology of science which refers to the way (scientific) knowledge is produced. So far, three modes have been conceptualized. Mode 1 production of knowledge is knowledge production motivated by scientific knowledge alone (basic research) which is not primarily concerned by the applicability of its findings. Mode 1 is founded on a conceptualization of science as separated into discrete disciplines (e.g., a biologist does not bother about chemistry). Mode 2 was coined in 1994 in juxtaposition to Mode 1 by Michael Gibbons, Camille Limoges, Helga Nowotny, Simon Schwartzman, Peter Scott and Martin Trow. In Mode 2, multidisciplinary teams are brought together for short periods of time to work on specific problems in the real world for knowledge production (applied research) in the knowledge society. Mode 2 can be explained by the way research funds are distributed among scientists and how scientists focus on obtaining these funds in terms of five basic features: 1) knowledge produced in the context of application; (2) transdisciplinarity; (3) heterogeneity and organizational diversity; (4) social accountability and reflexivity; (5) and quality control. Subsequently, Carayannis and Campbell described a Mode 3 knowledge in 2006.

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๐Ÿ”— Charlieplexing

๐Ÿ”— Computing ๐Ÿ”— Electronics ๐Ÿ”— Electrical engineering

Charlieplexing (also known as tristate multiplexing, reduced pin-count LED multiplexing, complementary LED drive and crossplexing) is a technique for accessing a large number of LEDs, switches, micro-capacitors or other I/O entities, using very few tri-state logic wires from a microcontroller, these entities being wired as discrete components, x/y arrays, or woven in a diagonally intersecting pattern to form diagonal arrays.

The method uses the tri-state logic capabilities of microcontrollers in order to gain efficiency over traditional multiplexing, each I/O pin being capable, when required, of rapidly changing between the three states, logical 1, logical 0, and high impedance.

This enables these I/O entities (LEDs, switches etc.) to be connected between any two microcontroller I/Os - e.g. with 4 I/Os, each I/O can pair with 3 other I/Os, resulting in 6 unique pairings (1/2, 1/3, 1/4, 2/3, 2/4, 3/4). Only 4 pairings are possible with standard x/y multiplexing (1/3, 1/4, 2/3, 2/4). Also, due to the microcontroller's ability to reverse the polarity of the 6 I/O pairs, the number of LEDS (or diodes) that are uniquely addressable, can be doubled to 12 - adding LEDS 2/1, 3/1, 4/1, 3/2, 4/2 and 4/3.

Although it is more efficient in its use of I/O, a small amount of address manipulation is required when trying to fit Charlieplexing into a standard x/y array.

Other issues that affect standard multiplexing but are exacerbated by Charlieplexing are:

  • consideration of current requirements and the forward voltages of the LEDs.
  • a requirement to cycle through the in-use LEDs rapidly so that the persistence of the human eye perceives the display to be lit as a whole. Multiplexing can generally be seen by a strobing effect and skewing if the eye's focal point is moved past the display rapidly.


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๐Ÿ”— Brabant Killers

๐Ÿ”— Crime ๐Ÿ”— Organized crime ๐Ÿ”— Belgium

The Brabant killers, also named the Nijvel Gang in Dutch-speaking media (Dutch: De Bende van Nijvel), and the mad killers of Brabant in French-speaking media (French: Les Tueurs fous du Brabant), are believed to be responsible for a series of violent attacks that mainly occurred in the Belgian province of Brabant between 1982 and 1985. A total of 28 people died and 22 were injured. The actions of the gang, believed to consist of a core of three men, made it Belgium's most notorious unsolved crime spree. The active participants were known as The Giant (a tall man who may have been the leader); the Killer (the main shooter) and the Old Man (a middle aged man who drove). The identities and whereabouts of the "Brabant killers" are unknown. Although significant resources are still dedicated to it, the most recent arrests in the case were of the now-retired original senior detectives. Failure to catch the gang resulted in a parliamentary inquiry. There have been many theories of ulterior motives behind the crimes.

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๐Ÿ”— Kibbutz

๐Ÿ”— Urban studies and planning ๐Ÿ”— Cooperatives ๐Ÿ”— Israel

A kibbutz (Hebrew: ืงึดื‘ึผื•ึผืฅโ€Ž / ืงื™ื‘ื•ืฅโ€Ž, lit. "gathering, clustering"; plural: kibbutzim ืงึดื‘ึผื•ึผืฆึดื™ืโ€Ž / ืงื™ื‘ื•ืฆื™ืโ€Ž) is a collective community in Israel that was traditionally based on agriculture. The first kibbutz, established in 1909, was Degania. Today, farming has been partly supplanted by other economic branches, including industrial plants and high-tech enterprises. Kibbutzim began as utopian communities, a combination of socialism and Zionism. In recent decades, some kibbutzim have been privatized and changes have been made in the communal lifestyle. A member of a kibbutz is called a kibbutznik (Hebrew: ืงึดื‘ึผื•ึผืฆึฐื ึดื™ืงโ€Ž / ืงื™ื‘ื•ืฆื ื™ืงโ€Ž; plural kibbutznikim or kibbutzniks).

In 2010, there were 270 kibbutzim in Israel. Their factories and farms account for 9% of Israel's industrial output, worth US$8 billion, and 40% of its agricultural output, worth over $1.7 billion. Some kibbutzim had also developed substantial high-tech and military industries. For example, in 2010, Kibbutz Sasa, containing some 200 members, generated $850 million in annual revenue from its military-plastics industry.

Currently the kibbutzim are organised in the secular Kibbutz Movement with some 230 kibbutzim, the Religious Kibbutz Movement with 16 kibbutzim and the much smaller religious Poalei Agudat Yisrael with two kibbutzim, all part of the wider communal settlement movement.

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