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🔗 Biefeld–Brown effect
The Biefeld–Brown effect is an electrical phenomenon that produces an ionic wind that transfers its momentum to surrounding neutral particles. It describes a force observed on an asymmetric capacitor when high voltage is applied to the capacitor's electrodes. Once suitably charged up to high DC potentials, a thrust at the negative terminal, pushing it away from the positive terminal, is generated. The effect was named by inventor Thomas Townsend Brown who claimed that he did a series of experiments with professor of astronomy Paul Alfred Biefeld, a former teacher of Brown whom Brown claimed was his mentor and co-experimenter at Denison University in Ohio.
The use of an asymmetric capacitor, with the negative electrode being larger than the positive electrode, allowed for more thrust to be produced in the direction from the low-flux to the high-flux region compared to a conventional capacitor. These asymmetric capacitors became known as Asymmetrical Capacitor Thrusters (ACT). The Biefeld–Brown effect can be observed in ionocrafts and lifters, which utilize the effect to produce thrust in the air without requiring any combustion or moving parts.
In his 1960 patent titled "Electrokinetic Apparatus," Brown refers to electrokinesis to describe the Biefeld–Brown effect, linking the phenomenon to the field of electrohydrodynamics (EHD). Brown also believed the Biefeld–Brown effect could produce an anti-gravity force, referred to as "electrogravitics" based on it being an electricity/gravity phenomenon. However, there is little evidence that supports Brown's claim on the effect's anti-gravity properties.
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- "Biefeld–Brown effect" | 2014-10-26 | 27 Upvotes 3 Comments
🔗 Khalid El-Masri
Khaled El-Masri (also Khalid El-Masri and Khaled Masri, Levantine Arabic pronunciation: [ˈxaːlɪd elˈmɑsˤɾi, -ˈmɑsˤɾe], Arabic: خالد المصري) (born 29 June 1963) is a German and Lebanese citizen who was mistakenly abducted by the Macedonian police in 2003, and handed over to the U.S. Central Intelligence Agency (CIA). While in CIA custody, he was flown to Afghanistan, where he was held at a black site and routinely interrogated, beaten, strip-searched, sodomized, and subjected to other cruel forms of inhumane and degrading treatment and torture. After El-Masri held hunger strikes, and was detained for four months in the "Salt Pit", the CIA finally admitted his arrest and torture were a mistake and released him. He is believed to be among an estimated 3,000 detainees whom the CIA abducted from 2001–2005.
In May 2004, the U.S. Ambassador to Germany, Daniel R. Coats, convinced the German interior minister, Otto Schily, not to press charges or to reveal the program. El-Masri filed suit against the CIA for his arrest, extraordinary rendition and torture. In 2006, his suit El Masri v. Tenet, in which he was represented by the American Civil Liberties Union (ACLU), was dismissed by the United States District Court for the Eastern District of Virginia, based on the U.S. government's claiming the state secrets privilege. The ACLU said the Bush administration attempted to shield its abuses by invoking this privilege. The case was also dismissed by the Appeals Court for the Fourth Circuit, and in December 2007, the United States Supreme Court declined to hear the case.
On 13 December 2012, El-Masri won an Article 34 case at the European Court of Human Rights in Strasbourg. The court determined he had been tortured while held by CIA agents and ruled that Macedonia was responsible for abusing him while in the country, and knowingly transferring him to the CIA when torture was a possibility. It awarded him compensation. This marked the first time that CIA activities against detainees was legally declared as torture. The European Court condemned nations for collaborating with the United States in these secret programs.
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- "Khalid El-Masri" | 2014-03-11 | 19 Upvotes 3 Comments
🔗 Project Orion (nuclear propulsion)
Project Orion was a study of a spacecraft intended to be directly propelled by a series of explosions of atomic bombs behind the craft (nuclear pulse propulsion). Early versions of this vehicle were proposed to take off from the ground (with significant associated nuclear fallout); later versions were presented for use only in space. Six non-nuclear tests were conducted using models. The project was eventually abandoned for multiple reasons such as the Partial Test Ban Treaty which banned nuclear explosions in space as well as concerns over nuclear fallout.
The idea of rocket propulsion by combustion of explosive substance was first proposed by Russian explosives expert Nikolai Kibalchich in 1881, and in 1891 similar ideas were developed independently by German engineer Hermann Ganswindt. Robert A. Heinlein mentions powering spaceships with nuclear bombs in his 1940 short story "Blowups Happen." Real life proposals of nuclear propulsion were first made by Stanislaw Ulam in 1946, and preliminary calculations were made by F. Reines and Ulam in a Los Alamos memorandum dated 1947. The actual project, initiated in 1958, was led by Ted Taylor at General Atomics and physicist Freeman Dyson, who at Taylor's request took a year away from the Institute for Advanced Study in Princeton to work on the project.
The Orion concept offered high thrust and high specific impulse, or propellant efficiency, at the same time. The unprecedented extreme power requirements for doing so would be met by nuclear explosions, of such power relative to the vehicle's mass as to be survived only by using external detonations without attempting to contain them in internal structures. As a qualitative comparison, traditional chemical rockets—such as the Saturn V that took the Apollo program to the Moon—produce high thrust with low specific impulse, whereas electric ion engines produce a small amount of thrust very efficiently. Orion would have offered performance greater than the most advanced conventional or nuclear rocket engines then under consideration. Supporters of Project Orion felt that it had potential for cheap interplanetary travel, but it lost political approval over concerns with fallout from its propulsion.
The Partial Test Ban Treaty of 1963 is generally acknowledged to have ended the project. However, from Project Longshot to Project Daedalus, Mini-Mag Orion, and other proposals which reach engineering analysis at the level of considering thermal power dissipation, the principle of external nuclear pulse propulsion to maximize survivable power has remained common among serious concepts for interstellar flight without external power beaming and for very high-performance interplanetary flight. Such later proposals have tended to modify the basic principle by envisioning equipment driving detonation of much smaller fission or fusion pellets, in contrast to Project Orion's larger nuclear pulse units (full nuclear bombs) based on less speculative technology.
To Mars by A-Bomb: The Secret History of Project Orion was a 2003 BBC documentary film about the project.
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- "Project Orion" | 2023-03-16 | 126 Upvotes 69 Comments
- "Project Orion (nuclear propulsion)" | 2015-02-10 | 32 Upvotes 11 Comments
🔗 Lipogram
A lipogram (from Ancient Greek: λειπογράμματος, leipográmmatos, "leaving out a letter") is a kind of constrained writing or word game consisting of writing paragraphs or longer works in which a particular letter or group of letters is avoided. Extended Ancient Greek texts avoiding the letter sigma are the earliest examples of lipograms.
Writing a lipogram may be a trivial task when avoiding uncommon letters like Z, J, Q, or X, but it is much more challenging to avoid common letters like E, T, or A in the English language, as the author must omit many ordinary words. Grammatically meaningful and smooth-flowing lipograms can be difficult to compose. Identifying lipograms can also be problematic, as there is always the possibility that a given piece of writing in any language may be unintentionally lipogrammatic. For example, Poe's poem The Raven contains no Z, but there is no evidence that this was intentional.
A pangrammatic lipogram is a text that uses every letter of the alphabet except one. For example, "The quick brown fox jumped over the lazy dog" omits the letter S, which the usual pangram includes by using the word jumps.
Discussed on
- "Lipogram" | 2021-04-24 | 35 Upvotes 14 Comments
🔗 Ostrich Algorithm
In computer science, the ostrich algorithm is a strategy of ignoring potential problems on the basis that they may be exceedingly rare. It is named for the ostrich effect which is defined as "to stick one's head in the sand and pretend there is no problem". It is used when it is more cost-effective to allow the problem to occur than to attempt its prevention.
🔗 Anti-Café
An anti-café (sometimes called a pay-per-minute café or a time club) is a venue that offers working space, food and drink, where customers pay only for the time they spend there. Anti-cafés became popular around 2011 in Russia and some CIS countries, with further independent anti-cafés opening across the world. Anti-cafés include the Ziferblat chain, founded by Russian writer Ivan Mitin in December 2010 in Moscow, the "Slow Time" café in Wiesbaden opened in 2013, and "Dialogues" in Bangalore.
Anti-cafés mostly target entrepreneurs, digital nomads, students, and creatives who need a cheap and convenient place to get their work done and meet other professionals. They can also be used by companies as a place give presentations and press conferences at low cost.
Discussed on
- "Anti-Café" | 2021-10-14 | 60 Upvotes 70 Comments
🔗 FILE_ID.DIZ
FILE_ID.DIZ is a plain text file containing a brief content description of the archive in which it is included. It was originally used in archives distributed through bulletin board systems (BBS), and still in the warez scene.
Bulletin boards commonly accept uploaded files from their users. The BBS software would prompt the user to supply a description for the uploaded file, but these descriptions were often less than useful. BBS system operators spent many hours going over the upload descriptions correcting and editing the descriptions. The FILE_ID.DIZ inclusion in archives was designed to address this problem.
FILE_ID stands for "file identification". DIZ stands for Description In Zipfile.
Clark Development and the Association of Shareware Professionals supported the idea of this becoming a standard for file descriptions. Clark rewrote the PCBDescribe program and included it with their PCBoard BBS software. The ASP urged their members to use this description file format in their distributions. Michael Leavitt, an employee of Clark Development, released the file specification and his PCBDescribe program source code to the public domain and urged other BBS software companies to support the DIZ file.
SysOps could add a common third-party script written in PPL, called "DIZ/2-PCB" that would process, rewrite, verify, and format DIZ files from archives as they were uploaded to a BBS. The software would extract the archive, examine the contents, compile a report, import the DIZ description file and then format it according to your liking. During this time, it was usual practice to add additional lines to the description, such as ads exclaiming the source of the uploaded BBS.
Traditionally, a FILE_ID.DIZ should be "up to 10 lines of text, each line being no more than 45 characters long." according to the specification v1.9.
The concept of DIZ files was to allow a concise description of uploaded files to be automatically applied. Advertisements and "high ASCII" artwork were specifically prohibited.
Even since the decline of the dial-up bulletin board system, FILE_ID.DIZ files are still utilized by the warez scene in their releases of unlicensed software. They are commonly bundled as part of the complete packaging by self-described pirate groups, and indicate the number of disks, and other basic information. Along with the NFO file, it is essential to the release. Especially in terms of unlicensed software ("warez"), it was common for each file in a sequential compressed archive (an archive intentionally split into multiple parts at creation so the parts can then be individually downloaded by slower connections like dial-up. Example: .rar, .r00, .r01, .r02, etc.), to contain this file. This probably contributed to its extended popularity after the decline of the bulletin board system in the late 1990s and early 2000s until now, since even casual consumers of unlicensed software would have stumbled upon it due to its abundance.
Discussed on
- "FILE_ID.DIZ" | 2015-06-27 | 10 Upvotes 3 Comments
🔗 Tamil Bell
The Tamil Bell is a broken bronze bell discovered in approximately 1836 by missionary William Colenso. It was being used as a pot to boil potatoes by Māori women near Whangarei in the Northland Region of New Zealand.
The bell is 13 cm long and 9 cm deep, and has an inscription. The inscription running around the rim of the bell has been identified as old Tamil. Translated, it says "Mohoyiden Buks ship’s bell". Some of the characters in the inscription are of an archaic form no longer seen in modern Tamil script, thus suggesting that the bell could be about 500 years old, possibly from the Later Pandya period. It is thus what is sometimes called an out-of-place artefact.
Indologist V. R. Ramachandra Dikshitar states in his The Origin and Spread of the Tamils that ancient Tamil sea-farers might have had a knowledge of Australia and Polynesia. The discovery of the bell has led to speculation about a possible Tamil presence in New Zealand, but the bell is not in itself proof of early Tamil contact with New Zealand'. Seafarers from Trincomalee may have reached New Zealand during the period of increased trade between the Vanni country and South East Asia. The bell might have been dropped off the shore by a Portuguese ship, whose sailors had been in touch with the Indians. Also, a number of Indian vessels had been captured by the Europeans during the period; thus, another possibility is that the bell might have belonged to such a wrecked vessel, cast away on the New Zealand shores.
The bell was bequeathed by William Colenso to the Dominion Museum – now the Museum of New Zealand Te Papa Tongarewa.
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- "Tamil Bell" | 2017-03-24 | 374 Upvotes 123 Comments
🔗 Piyama-Radu
Piyamaradu (also spelled Piyama-Radu, Piyama Radu, Piyamaradus, Piyamaraduš) was a warlike personage whose name figures prominently in the Hittite archives of the middle and late 13th century BC in western Anatolia. His history is of particular interest because it appears to intertwine with that of the Trojan War. Some scholars assume that his name is cognate to that of King Priam of Troy.
🔗 Pencil Hardness Grading
A pencil ( ) is a writing or drawing implement with a solid pigment core in a protective casing that reduces the risk of core breakage, and keeps it from marking the user's hand.
Pencils create marks by physical abrasion, leaving a trail of solid core material that adheres to a sheet of paper or other surface. They are distinct from pens, which dispense liquid or gel ink onto the marked surface.
Most pencil cores are made of graphite powder mixed with a clay binder. Graphite pencils (traditionally known as "lead pencils") produce grey or black marks that are easily erased, but otherwise resistant to moisture, most chemicals, ultraviolet radiation and natural aging. Other types of pencil cores, such as those of charcoal, are mainly used for drawing and sketching. Coloured pencils are sometimes used by teachers or editors to correct submitted texts, but are typically regarded as art supplies, especially those with cores made from wax-based binders that tend to smear when erasers are applied to them. Grease pencils have a softer, oily core that can leave marks on smooth surfaces such as glass or porcelain.
The most common pencil casing is thin wood, usually hexagonal in section but sometimes cylindrical or triangular, permanently bonded to the core. Casings may be of other materials, such as plastic or paper. To use the pencil, the casing must be carved or peeled off to expose the working end of the core as a sharp point. Mechanical pencils have more elaborate casings which are not bonded to the core; instead, they support separate, mobile pigment cores that can be extended or retracted (usually through the casing's tip) as needed. These casings can be reloaded with new cores (usually graphite) as the previous ones are exhausted.
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- "Pencil Hardness Grading" | 2023-11-08 | 19 Upvotes 7 Comments