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🔗 Biography 🔗 Biography/science and academia 🔗 Ireland

Percy Edwin Ludgate (2 August 1883 – 16 October 1922) was an Irish amateur scientist who designed the second analytical engine (general-purpose Turing-complete computer) in history.

A rotary woofer is a subwoofer-style loudspeaker which reproduces very low frequency content by using a conventional speaker voice coil's motion to change the pitch (angle) of the blades of an impeller rotating at a constant speed. The pitch of the fan blades is controlled by the audio signal presented to the voice coil, and is able to swing both positive and negative, with respect to a zero pitch spinning blade position. Since the audio amplifier only changes the pitch of the blades, it takes much less power, per dB of generated acoustic sound level, to drive a rotary woofer than to power a conventional subwoofer, which uses a moving electromagnet (voice coil) placed within the field of a stationary permanent magnet to drive a cone which then displaces air. Rotary woofers excel at producing sounds below 20 Hz, below the normal hearing range; when installed in the wall of a sealed room, they can produce audio frequencies down to 0 Hz, a static pressure differential, by simply compressing the air in the sealed room.

🔗 Aviation 🔗 Military history 🔗 Military history/Military aviation 🔗 Engineering 🔗 Industrial design

Speed tape is an aluminium pressure-sensitive tape used to perform minor repairs on aircraft and racing cars. It is used as a temporary repair material until a more permanent repair can be carried out. It has an appearance similar to duct tape, for which it is sometimes mistaken, but its adhesive is capable of sticking on an airplane fuselage or wing at high speeds, hence the name.

🔗 Animation

Rubber hose animation was the first animation style that became standardized in the American animation field. The defining feature is the curving motion most things possess, resembling that of a rubber hose. While the style fell out of fashion during the 1930s, there has been a minor revitalization of it in recent years with works such as the video games Cuphead and Bendy and the Ink Machine, and the film Steven Universe: The Movie.

🔗 Disaster management 🔗 Africa 🔗 Greece 🔗 Turkey 🔗 Bulgaria 🔗 Africa/Libya 🔗 Weather 🔗 Weather/Non-tropical storms 🔗 Weather/Floods 🔗 Weather/Weather 🔗 Africa/Egypt 🔗 Weather/Tropical cyclones

Storm Daniel, also known as Cyclone Daniel, was the deadliest Mediterranean tropical-like cyclone ever recorded as well as the deadliest weather event during 2023. It caused catastrophic damage in Libya and also affected parts of southeastern Europe. Forming as a low-pressure system around 4 September 2023, the storm affected Greece, Bulgaria and also Turkey with extensive flooding. The storm then organized as a Mediterranean Low and was designated as Storm Daniel, in which it soon acquired quasi-tropical characteristics (TLC) and moved toward the coast of Libya, where it caused catastrophic flooding before degenerating into a remnant low. The storm was the result of an Omega block, as a high-pressure zone became sandwiched between two zones of low pressure, the isobars shaping a Greek letter Ω.

🔗 Lists 🔗 Photography 🔗 Photography/History of photography

This is a list of photographs considered the most important in surveys where authoritative sources review the history of the medium not limited by time period, region, genre, topic, or other specific criteria. These images may be referred to as the most important, most iconic, or most influential—but they are all considered key images in the history of photography.

🔗 Computing 🔗 Computer science

In computational complexity and optimization the no free lunch theorem is a result that states that for certain types of mathematical problems, the computational cost of finding a solution, averaged over all problems in the class, is the same for any solution method. The name alludes to the saying "no such thing as a free lunch", that is, no method offers a "short cut". This is under the assumption that the search space is a probability density function. It does not apply to the case where the search space has underlying structure (e.g., is a differentiable function) that can be exploited more efficiently (e.g., Newton's method in optimization) than random search or even has closed-form solutions (e.g., the extrema of a quadratic polynomial) that can be determined without search at all. For such probabilistic assumptions, the outputs of all procedures solving a particular type of problem are statistically identical. A colourful way of describing such a circumstance, introduced by David Wolpert and William G. Macready in connection with the problems of search and optimization, is to say that there is no free lunch. Wolpert had previously derived no free lunch theorems for machine learning (statistical inference). Before Wolpert's article was published, Cullen Schaffer independently proved a restricted version of one of Wolpert's theorems and used it to critique the current state of machine learning research on the problem of induction.

In the "no free lunch" metaphor, each "restaurant" (problem-solving procedure) has a "menu" associating each "lunch plate" (problem) with a "price" (the performance of the procedure in solving the problem). The menus of restaurants are identical except in one regard – the prices are shuffled from one restaurant to the next. For an omnivore who is as likely to order each plate as any other, the average cost of lunch does not depend on the choice of restaurant. But a vegan who goes to lunch regularly with a carnivore who seeks economy might pay a high average cost for lunch. To methodically reduce the average cost, one must use advance knowledge of a) what one will order and b) what the order will cost at various restaurants. That is, improvement of performance in problem-solving hinges on using prior information to match procedures to problems.

In formal terms, there is no free lunch when the probability distribution on problem instances is such that all problem solvers have identically distributed results. In the case of search, a problem instance in this context is a particular objective function, and a result is a sequence of values obtained in evaluation of candidate solutions in the domain of the function. For typical interpretations of results, search is an optimization process. There is no free lunch in search if and only if the distribution on objective functions is invariant under permutation of the space of candidate solutions. This condition does not hold precisely in practice, but an "(almost) no free lunch" theorem suggests that it holds approximately.

🔗 United States 🔗 Comedy 🔗 Journalism

The Order of the Occult Hand is a secret society of American journalists who slip the meaningless and telltale phrase "It was as if an occult hand had…" in print as an inside joke.

🔗 Africa 🔗 Highways 🔗 Highways/Road transport 🔗 Highways/African Highways

The Trans-African Highway network comprises transcontinental road projects in Africa being developed by the United Nations Economic Commission for Africa (UNECA), the African Development Bank (ADB), and the African Union in conjunction with regional international communities. They aim to promote trade and alleviate poverty in Africa through highway infrastructure development and the management of road-based trade corridors. The total length of the nine highways in the network is 56,683 km (35,221 mi).

In some documents the highways are referred to as "Trans-African Corridors" or "Road Corridors" rather than highways. The name Trans-African Highway and its variants are not in wide common usage outside of planning and development circles, and as of 2014 one does not see them signposted as such or labelled on maps, except in Kenya and Uganda where the Mombasa–Nairobi–Kampala–Fort Portal section (or the Kampala–Kigali feeder road) of Trans-African Highway 8 is sometimes referred to as the "Trans-Africa Highway".

🔗 United States 🔗 California 🔗 India 🔗 Pakistan 🔗 Ethnic groups 🔗 United States/Asian Americans 🔗 California/Southern California 🔗 United States/Mexican-Americans

The Punjabi Mexican American community, the majority of which is localized to Yuba City, California, is a distinctive ethnicity holding its roots in a migration pattern that occurred almost a century ago. The first meeting of these cultures occurred in the Imperial and Central Valleys in 1907, near the largest irrigation system in the Western Hemisphere.