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π Forest kindergarten
Forest kindergarten is a type of preschool education for children between the ages of three and six that is held almost exclusively outdoors. Whatever the weather, children are encouraged to play, explore and learn in a forest environment. The adult supervision is meant to assist rather than lead. It is also known as Waldkindergarten (in German), outdoor nursery, or nature kindergarten.
Discussed on
- "Forest kindergarten" | 2019-07-06 | 114 Upvotes 44 Comments
π Agent 355
Agent 355 (died after 1780) was the code name of a female spy during the American Revolution, part of the Culper Ring. Agent 355 was one of the first spies for the United States, but her real identity is unknown. The number, 355, could be de-crypted from the system the Culper Ring used to mean "lady."
Discussed on
- "Agent 355" | 2019-07-04 | 115 Upvotes 10 Comments
π Wheatstone System
The Wheatstone system was an automated telegraph system that replaced a human operator with machines capable of sending and recording Morse code at a consistent fast rate. The system included a perforator, which prepared punched paper tape called a Wheatstone slip, a transmitter that read the tape and converted the symbols into dots and dashes encoded as mark and space electric currents on the telegraph line, and a receiver at the other end of the telegraph line that printed the Morse symbols. The system was invented by Charles Wheatstone. Enhancements could be made so that it was a duplex system, able to send and receive on the same line simultaneously.
The Wheatstone slip was a paper tape that contained holes in a pattern to control the mark and space signals on the telegraph line. The paper tape was from 0.46 to 0.48 inches in width, (but the standard width is from 0.472 to 0.475 inches) and a standard thickness of 0.004 to 0.0045 inches. Olive oil coating lubricated the punch process. There were three rows of holes. The middle row forms a rack so that a star wheel can move the paper forward. Every used position on the tape has a middle hole punched. The top hole indicates when to turn on the mark signal on the line, and the bottom hole says to turn off the mark signal. Each vertical column represents a time interval in the Morse code, including the spacing between the holes. The holes are spaced 0.1 inches apart. A column of three holes turns on the mark at the beginning of the interval, and turns it off at the end making a dot. If there is a top hole without a bottom, and then the next column has a bottom without a top hole, mark is on for three intervals, and a dash is represented. If there is only a centre hole, then nothing changes, and this would normally be used to put in space between letters and words.
The Wheatstone perforator was a manually operated hole punch machine to produce Wheatstone slips. It had three buttons (or keys) labelled "A", "A1" and "A2". "A" punched the pattern for dot, "A1" punched the pattern for space, and "A2" punched the dash pattern in two columns. The keys were so difficult to press that fist-held rubber-tipped mallets were used to depress them and operate the punches. Using this, invalid combinations of holes could not be produced. The blank paper tape was fed in from the right over a roller and came out the left side. It was oriented in a vertical plane. The paper punches were labelled with numbers: 1 for the top hole of the dot, 2 for the sprocket hole for dot, and 3 for the bottom hole for dot. When a dash was punched, extra hole punches to the right punched a centre hole with number 4 and a bottom hole with number 5. The perforator was introduced in 1867. It enabled transmission speeds on a telegraph line to increase to 70 words per minute. The very first message ever punched onto a tape was "SOS EIOS". The manual perforator was subsequently replaced by keyboard perforators like the Gell keyboard perforator or Kleinschmidt keyboard perforator.
Each of the keys had a spring to restore its position after pressing. Each key moved a corresponding lever underneath the instrument. The other end of the levers protruded up into the back of the mechanism. Each punch rod also had a spring to put it back in place after punching a hole. For space and dot keying (A or A1) the star wheel was only allowed to turn one position by a pawl, and the paper tape only moved forward one position. However, when key A2 was hit, the corresponding lever B2 raised a bar (h) which allowed another lever attached to the pawl to move further back when the star wheel rotated, and the wheel could turn two positions, for a dash. The distance the paper tape moved for each position was determined by how far lever k moved, and its range of movement had to be set by adjusting screws i and t. A flat spring g stored energy from the punch to move the paper. The force of the spring was determined by adjusting screws n and n'. A guide roller (r) with a groove was pressed by an adjustable spring to press the pawl against the star wheel. The star wheel was on a frame with a piece sticking out the left hand side as a lever. When the operator wanted to insert paper tape, this lever was pulled, and the star wheel retracted from the paper.
The Wheatstone transmitter read a paper tape (Wheatstone slip) and converted the dot pattern into mark and space symbols on the telegraph line. It worked by two rods alternately rising up to sample the holes in the tape. First of all the top hole was probed, and if the rod could go through, it moved a compound lever that connected the mark signal to the line. With no hole the lever remained unmoved. Next the top hole rod dropped and the bottom hole rod checked whether there was a bottom hole in the tape. If there was, the compound lever was moved back to connect the space signal on the line. If there was no hole, the compound lever was left alone as it was. An extra switch enabled the transmitter to be bypassed so that a Morse key could be used instead.
The Wheatstone receiver converted the signal on the telegraph line to an inked pattern on a paper strip. An electromagnet electrically connected to the telegraph line moved an inking wheel to press against the paper. A clockwork mechanism advanced the paper tape, and turned the inking wheel, and an ink supply wheel. The paper advance speed could be adjusted between 7 and 60 feet per minute. Power to the clockwork had three sources: it could be a coiled spring, a weight, or an electric motor. Paper spools were stored in drawers beneath the reader to allow quick change when one was exhausted. The ink supply wheel turned in an inkwell. The machine was started and stopped by use of a lever. In electrical characteristics, the electromagnet had two windings, each of 100 ohms resistance. These could be connected in parallel or series to achieve a 50 or 200 ohm resistance, to better match the telegraph line. Other maintenance that might have been required was cleaning of the marker and supply wheels, adjusting the armature-coil spacing to avoid a marking or spacing bias, and cleaning the sounding tongue and contact points.
The Wheatstone telegram consisted of strips of paper tape with the Morse code printed on it, pasted on a form. The telegram would later be retyped to make a final presentable message for the recipient.
Discussed on
- "Wheatstone System" | 2019-11-25 | 44 Upvotes 11 Comments
π SkySails
SkySails GmbH & Co. KG is a Hamburg-based company that sells kite rigs to propel cargo ships, large yachts and fishing vessels by wind energy. Ships are pulled by an automatically-controlled foil kite of some hundreds of square meters. For multiple reasons, they give many times the thrust per unit area of conventional mast-mounted sails.
The systems save fuel, and reduce carbon emissions and shipping costs, but have not been widely adopted.
Discussed on
- "SkySails" | 2019-07-04 | 126 Upvotes 42 Comments
π Possible explanations for the slow progress of AI research
Artificial general intelligence (AGI) is the hypothetical intelligence of a machine that has the capacity to understand or learn any intellectual task that a human being can. It is a primary goal of some artificial intelligence research and a common topic in science fiction and futures studies. AGI can also be referred to as strong AI, full AI, or general intelligent action. (Some academic sources reserve the term "strong AI" for machines that can experience consciousness.)
Some authorities emphasize a distinction between strong AI and applied AI (also called narrow AI or weak AI): the use of software to study or accomplish specific problem solving or reasoning tasks. Weak AI, in contrast to strong AI, does not attempt to perform the full range of human cognitive abilities.
As of 2017, over forty organizations were doing research on AGI.
Discussed on
- "Possible explanations for the slow progress of AI research" | 2019-11-25 | 19 Upvotes 15 Comments
π Daimler Reitwagen
The Daimler Petroleum Reitwagen ("riding car") or Einspur ("single track") was a motor vehicle made by Gottlieb Daimler and Wilhelm Maybach in 1885. It is widely recognized as the first motorcycle. Daimler is often called "the father of the motorcycle" for this invention. Even when the three steam powered two wheelers that preceded the Reitwagen, the Michaux-Perreaux and Roper of 1867β1869, and the 1884 Copeland, are considered motorcycles, it remains nonetheless the first petrol internal combustion motorcycle, and the forerunner of all vehicles, land, sea and air, that use its overwhelmingly popular engine type.
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- "Daimler Reitwagen" | 2019-11-25 | 31 Upvotes 2 Comments
π AI Winter
In the history of artificial intelligence, an AI winter is a period of reduced funding and interest in artificial intelligence research. The term was coined by analogy to the idea of a nuclear winter. The field has experienced several hype cycles, followed by disappointment and criticism, followed by funding cuts, followed by renewed interest years or decades later.
The term first appeared in 1984 as the topic of a public debate at the annual meeting of AAAI (then called the "American Association of Artificial Intelligence"). It is a chain reaction that begins with pessimism in the AI community, followed by pessimism in the press, followed by a severe cutback in funding, followed by the end of serious research. At the meeting, Roger Schank and Marvin Minskyβtwo leading AI researchers who had survived the "winter" of the 1970sβwarned the business community that enthusiasm for AI had spiraled out of control in the 1980s and that disappointment would certainly follow. Three years later, the billion-dollar AI industry began to collapse.
Hype is common in many emerging technologies, such as the railway mania or the dot-com bubble. The AI winter was a result of such hype, due to over-inflated promises by developers, unnaturally high expectations from end-users, and extensive promotion in the media . Despite the rise and fall of AI's reputation, it has continued to develop new and successful technologies. AI researcher Rodney Brooks would complain in 2002 that "there's this stupid myth out there that AI has failed, but AI is around you every second of the day." In 2005, Ray Kurzweil agreed: "Many observers still think that the AI winter was the end of the story and that nothing since has come of the AI field. Yet today many thousands of AI applications are deeply embedded in the infrastructure of every industry."
Enthusiasm and optimism about AI has increased since its low point in the early 1990s. Beginning about 2012, interest in artificial intelligence (and especially the sub-field of machine learning) from the research and corporate communities led to a dramatic increase in funding and investment.
Discussed on
- "AI Winter" | 2024-10-08 | 11 Upvotes 2 Comments
- "AI Winter" | 2019-11-25 | 55 Upvotes 41 Comments
- "AI winter" | 2007-10-25 | 16 Upvotes 1 Comments
π Battle Chess
Battle Chess is a computer game version of chess in which the chess pieces come to life and battle one another when capturing. It was originally developed and released by Interplay Entertainment for the Amiga in 1988 and subsequently on many other systems, including 3DO Interactive Multiplayer, Acorn Archimedes, Amiga CD32, Amiga CDTV, Apple IIGS, Apple IIe, Atari ST, Commodore 64, MS-DOS, FM Towns, NES, Mac OS, NEC PC-9801, X68000 and Microsoft Windows. In 1991, Battle Chess Enhanced was released by Interplay for the PC, featuring improved VGA graphics and a symphonic musical score that played from the CD-ROM.
Battle Chess was critically acclaimed and commercially successful, resulting in two official follow-ups as well as several inspired games. Its remake, Battle Chess: Game of Kings, was released on Steam on December 11, 2015.
Discussed on
- "Battle Chess" | 2019-11-24 | 132 Upvotes 90 Comments
π National Eagle Repository
The National Eagle Repository is operated and managed under the Office of Law Enforcement of the United States Fish and Wildlife Service located at the Rocky Mountain Arsenal National Wildlife Refuge outside of Denver, Colorado. It serves as a central location for the receipt, storage, and distribution of bald and golden eagles that have been found dead. Eagles and eagle parts are available only to Native Americans enrolled in federally recognized tribes for use in religious and cultural ceremonies.
Discussed on
- "National Eagle Repository" | 2019-07-03 | 38 Upvotes 5 Comments
π .DS_Store
In the Apple macOS operating system, .DS_Store is a file that stores custom attributes of its containing folder, such as the position of icons or the choice of a background image. The name is an abbreviation of Desktop Services Store, reflecting its purpose. It is created and maintained by the Finder application in every folder, and has functions similar to the file desktop.ini in Microsoft Windows. Starting with a full stop (period) character, it is hidden in Finder and many Unix utilities. Its internal structure is proprietary, but has since been reverse-engineered.
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- ".DS_Store" | 2021-03-12 | 50 Upvotes 30 Comments
- ".DS_Store" | 2019-07-02 | 71 Upvotes 21 Comments