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🔗 Aviation 🔗 Military history 🔗 Military history/Military aviation 🔗 Military history/Military science, technology, and theory 🔗 Aviation/aircraft

In aerobatics the Cobra maneuver, also known as just the Cobra, is a dramatic and demanding maneuver in which an airplane flying at a moderate speed suddenly raises the nose momentarily to the vertical position and slightly beyond, before dropping it back to normal, effectively making the plane a full body air brake.

The maneuver relies on the ability of the plane to be able to quickly change alpha which momentarily stalls the plane without overloading the airframe and powerful engine thrust to maintain approximately constant altitude through the entire move. It is an impressive maneuver to demonstrate an aircraft's pitch control authority, high alpha stability and engine-versus-inlet compatibility, as well as the pilot's skill.

Although the maneuver is mainly performed at air shows it has use in close range air combat as a last ditch maneuver to make a pursuing plane overshoot. There is currently no widely spread or readily available evidence of the Cobra being used in real combat, although, there are records of it being used during mockup-dogfights and during border protection.

🔗 Robotics

Q-learning is a model-free reinforcement learning algorithm to learn a policy telling an agent what action to take under what circumstances. It does not require a model (hence the connotation "model-free") of the environment, and it can handle problems with stochastic transitions and rewards, without requiring adaptations.

For any finite Markov decision process (FMDP), Q-learning finds an optimal policy in the sense maximizing the expected value of the total reward over any and all successive steps, starting from the current state. Q-learning can identify an optimal action-selection policy for any given FMDP, given infinite exploration time and a partly-random policy. "Q" names the function that returns the reward used to provide the reinforcement and can be said to stand for the "quality" of an action taken in a given state.

Alternative Title: Just because you have some money, that doesn't mean that you have to spend it.

In biology, the hallmarks of an aggressive cancer include limitless multiplication of ordinarily beneficial cells, even when the body signals that further multiplication is no longer needed. The Wikipedia page on the wheat and chessboard problem explains that nothing can keep growing forever. In biology, the unwanted growth usually terminates with the death of the host. Ever-increasing spending can often lead to the same undesirable result in organizations.

Clicking on the first link in the main text of a Wikipedia article, and then repeating the process for subsequent articles, would usually lead to the Philosophy article. As of February 2016, 97% of all articles in Wikipedia eventually led to the article Philosophy. The remaining articles lead to an article without any outgoing wikilinks, to pages that do not exist, or get stuck in loops. This has gone up from 94.52% in 2011.

There have been some theories on this phenomenon, with the most prevalent being the tendency for Wikipedia pages to move up a "classification chain." According to this theory, the Wikipedia Manual of Style guidelines on how to write the lead section of an article recommend that the article should start by defining the topic of the article, so that the first link of each page will naturally take the reader into a broader subject, eventually ending in wide-reaching pages such as Mathematics, Science, Language, and of course, Philosophy, nicknamed "the mother of all sciences".

🔗 History 🔗 Visual arts

The Hockney–Falco thesis is a theory of art history, advanced by artist David Hockney and physicist Charles M. Falco. Both claimed that advances in realism and accuracy in the history of Western art since the Renaissance were primarily the result of optical instruments such as the camera obscura, camera lucida, and curved mirrors, rather than solely due to the development of artistic technique and skill. Nineteenth-century artists' use of photography had been well documented. In a 2001 book, Secret Knowledge: Rediscovering the Lost Techniques of the Old Masters, Hockney analyzed the work of the Old Masters and argued that the level of accuracy represented in their work is impossible to create by "eyeballing it". Since then, Hockney and Falco have produced a number of publications on positive evidence of the use of optical aids, and the historical plausibility of such methods. The hypothesis led to a variety of conferences and heated discussions.

Arthropod enthusiast, mainly focus on Panarthropod head problem, phylogeny across arthropod subphyla and stem lineage, basal chelicerates, dinocaridids and lobopodians. Sometime drawing stuff, not so well in english, mainly active at Japanese Wikipedia.

Japanese: 利用者:Junnn11

Commons: User:Junnn11

Twitter: ni075

🔗 Computing 🔗 Computing/Computer hardware

The transputer is a series of pioneering microprocessors from the 1980s, featuring integrated memory and serial communication links, intended for parallel computing. They were designed and produced by Inmos, a semiconductor company based in Bristol, United Kingdom.

For some time in the late 1980s, many considered the transputer to be the next great design for the future of computing. While Inmos and the transputer did not achieve this expectation, the transputer architecture was highly influential in provoking new ideas in computer architecture, several of which have re-emerged in different forms in modern systems.

The Stigler diet is an optimization problem named for George Stigler, a 1982 Nobel Laureate in economics, who posed the following problem:

For a moderately active man weighing 154 pounds, how much of each of 77 foods should be eaten on a daily basis so that the man’s intake of nine nutrients will be at least equal to the recommended dietary allowances (RDAs) suggested by the National Research Council in 1943, with the cost of the diet being minimal?

The nutrient RDAs required to be met in Stigler’s experiment were calories, protein, calcium, iron, as well as vitamins A, B₁, B₂, B₃, and C. The result was an annual budget allocated to foods such as evaporated milk, cabbage, dried navy beans, and beef liver at a cost of approximately $0.11 a day in 1939 U.S. dollars.

While the name “Stigler Diet” was applied after the experiment by outsiders, according to Stigler, “No one recommends these diets for anyone, let alone everyone.” The Stigler diet has been much ridiculed for its lack of variety and palatability; however, his methodology has received praise and is considered to be some of the earliest work in linear programming.

🔗 Computing 🔗 Computer science

Esterel is a synchronous programming language for the development of complex reactive systems. The imperative programming style of Esterel allows the simple expression of parallelism and preemption. As a consequence, it is well suited for control-dominated model designs.

The development of the language started in the early 1980s, and was mainly carried out by a team of Ecole des Mines de Paris and INRIA led by Gérard Berry in France. Current compilers take Esterel programs and generate C code or hardware (RTL) implementations (VHDL or Verilog).

The language is still under development, with several compilers out. The commercial version of Esterel is the development environment Esterel Studio. The company that commercialize it (Synfora) initiated a normalization process with the IEEE in April 2007 however the working group (P1778) dissolved March 2011. The Esterel v7 Reference Manual Version v7 30 – initial IEEE standardization proposal is publicly available.

🔗 Agriculture 🔗 Food and drink 🔗 Politics of the United Kingdom 🔗 Poultry

The salmonella-in-eggs controversy was a political controversy in the United Kingdom caused by the Parliamentary Under-Secretary of State for Health, Edwina Currie's claims that "most of the egg production in this country, sadly, is now affected with salmonella" in 1988. These claims led to a 60 percent decline in egg sales over the next few weeks, and angered both politicians and those in the egg production industry. Currie's statement also resulted in the destruction of around 400 million eggs and the slaughter of around 4 million hens. The controversy dominated Currie's tenure as Parliamentary Under-Secretary of State for Health and resulted in her resignation two weeks later.