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π Kelvin's hydroelectric generator
The Kelvin water dropper, invented by Scottish scientist William Thomson (Lord Kelvin) in 1867, is a type of electrostatic generator. Kelvin referred to the device as his water-dropping condenser. The apparatus is variously called the Kelvin hydroelectric generator, the Kelvin electrostatic generator, or Lord Kelvin's thunderstorm. The device uses falling water to generate voltage differences by electrostatic induction occurring between interconnected, oppositely charged systems. This eventually leads to an electric arc discharging in the form of a spark. It is used in physics education to demonstrate the principles of electrostatics.
Discussed on
- "Kelvin's hydroelectric generator" | 2009-04-09 | 17 Upvotes 7 Comments
π How a Buffer Overflow Works
In information security and programming, a buffer overflow, or buffer overrun, is an anomaly where a program, while writing data to a buffer, overruns the buffer's boundary and overwrites adjacent memory locations.
Buffers are areas of memory set aside to hold data, often while moving it from one section of a program to another, or between programs. Buffer overflows can often be triggered by malformed inputs; if one assumes all inputs will be smaller than a certain size and the buffer is created to be that size, then an anomalous transaction that produces more data could cause it to write past the end of the buffer. If this overwrites adjacent data or executable code, this may result in erratic program behavior, including memory access errors, incorrect results, and crashes.
Exploiting the behavior of a buffer overflow is a well-known security exploit. On many systems, the memory layout of a program, or the system as a whole, is well defined. By sending in data designed to cause a buffer overflow, it is possible to write into areas known to hold executable code and replace it with malicious code, or to selectively overwrite data pertaining to the program's state, therefore causing behavior that was not intended by the original programmer. Buffers are widespread in operating system (OS) code, so it is possible to make attacks that perform privilege escalation and gain unlimited access to the computer's resources. The famed Morris worm in 1988 used this as one of its attack techniques.
Programming languages commonly associated with buffer overflows include C and C++, which provide no built-in protection against accessing or overwriting data in any part of memory and do not automatically check that data written to an array (the built-in buffer type) is within the boundaries of that array. Bounds checking can prevent buffer overflows, but requires additional code and processing time. Modern operating systems use a variety of techniques to combat malicious buffer overflows, notably by randomizing the layout of memory, or deliberately leaving space between buffers and looking for actions that write into those areas ("canaries").
Discussed on
- "How a Buffer Overflow Works" | 2009-04-01 | 17 Upvotes 6 Comments
π Gall's law
John Gall (September 18, 1925 β December 15, 2014) was an American author and retired pediatrician. Gall is known for his 1975 book General systemantics: an essay on how systems work, and especially how they fail..., a critique of systems theory. One of the statements from this book has become known as Gall's law.
Discussed on
- "Gall's Law" | 2009-04-01 | 40 Upvotes 6 Comments
- "Gall's law" | 2008-09-13 | 36 Upvotes 7 Comments
π All editions of Encarta are being discontinued (read about it on Wikipedia)
Microsoft Encarta was a digital multimedia encyclopedia published by Microsoft Corporation from 1993 to 2009. Originally sold on CD-ROM or DVD, it was also later available on the World Wide Web via an annual subscription β although later many articles could also be viewed free online with advertisements. By 2008, the complete English version, Encarta Premium, consisted of more than 62,000 articles, numerous photos and illustrations, music clips, videos, interactive content, timelines, maps, atlases and homework tools.
Microsoft published similar encyclopedias under the Encarta trademark in various languages, including German, French, Spanish, Dutch, Italian, Portuguese and Japanese. Localized versions contained contents licensed from national sources and more or less content than the full English version. For example, the Dutch version had content from the Dutch Winkler Prins encyclopedia.
In March 2009, Microsoft announced it was discontinuing both the Encarta disc and online versions. The MSN Encarta site was closed on October 31, 2009, in all countries except Japan, where it was closed on December 31, 2009. Microsoft continued to operate the Encarta online dictionary until 2011.
Discussed on
- "All editions of Encarta are being discontinued (read about it on Wikipedia)" | 2009-03-30 | 15 Upvotes 3 Comments
π Format wars this past century
A format war describes competition between mutually incompatible proprietary formats that compete for the same market, typically for data storage devices and recording formats for electronic media. It is often characterized by political and financial influence on content publishers by the developers of the technologies. Developing companies may be characterized as engaging in a format war if they actively oppose or avoid interoperable open-industry technical standards in favor of their own.
A format war emergence can be explained because each vendor is trying to exploit cross-side network effects in a two-sided market. There is also a social force to stop a format war: when one of them wins as de facto standard, it solves a coordination problem for the format users.
Discussed on
- "Format wars this past century" | 2009-03-21 | 14 Upvotes 5 Comments
π Wikiid: Can Wikipedia make a Wikipedia page notable enough to avoid deletion?
User:Diikiw/Wiikid, formerly Wikiid, is an article that was created on the web site Wikipedia in 2008. It is notable in its attempt to become the first Wikipedia page to gain notoriety solely for the fact that it was a page on Wikipedia; this was intended to spark a debate as to whether or not Wikipedia could be considered a source notable enough to allow a pageβs permanent entry on the site. It can be looked at both as metahumor and as a piece of postmodern art.
Discussed on
- "Wikiid: Can Wikipedia make a Wikipedia page notable enough to avoid deletion?" | 2009-03-16 | 40 Upvotes 27 Comments
π Erlang Shen
Erlang Shen (δΊιη₯), or Erlang is a Chinese God with a third truth-seeing eye in the middle of his forehead.
Er-lang Shen may be a deified version of several semi-mythical folk heroes who help regulate China's torrential floods dating variously from the Qin, Sui, and Jin dynasties. A later Buddhist source identifies him as the second son of the Northern Heavenly King Vaishravana.
In the Ming semi-mythical novels Creation of the Gods and Journey to the West, Erlang Shen is the nephew of the Jade Emperor. In the former, he assists the Zhou army in defeating the Shang. In the latter, he is the second son of a mortal and Jade emperor's sister. In the legend, he is known as the greatest warrior god of heaven.
Discussed on
- "Erlang Shen" | 2009-03-11 | 127 Upvotes 6 Comments
π The Erlang Distribution
The Erlang distribution is a two-parameter family of continuous probability distributions with support . The two parameters are:
- a positive integer the "shape", and
- a positive real number the "rate". The "scale", the reciprocal of the rate, is sometimes used instead.
The Erlang distribution with shape parameter simplifies to the exponential distribution. It is a special case of the gamma distribution. It is the distribution of a sum of independent exponential variables with mean each.
The Erlang distribution was developed by A. K. Erlang to examine the number of telephone calls which might be made at the same time to the operators of the switching stations. This work on telephone traffic engineering has been expanded to consider waiting times in queueing systems in general. The distribution is also used in the field of stochastic processes.
Discussed on
- "The Erlang Distribution" | 2009-03-11 | 142 Upvotes 3 Comments
π List Of Acquisitions By Google
Google is a computer software and a web search engine company that acquired, on average, more than one company per week in 2010 and 2011. The table below is an incomplete list of acquisitions, with each acquisition listed being for the respective company in its entirety, unless otherwise specified. The acquisition date listed is the date of the agreement between Google and the acquisition subject. As Google is headquartered in the United States, acquisition is listed in US dollars. If the price of an acquisition is unlisted, then it is undisclosed. If the Google service that is derived from the acquired company is known, then it is also listed here. Google itself was re-organized into a subsidiary of a larger holding company known as Alphabet Inc. in 2015.
As of DecemberΒ 2016, Alphabet has acquired over 200 companies, with its largest acquisition being the purchase of Motorola Mobility, a mobile device manufacturing company, for $12.5 billion. Most of the firms acquired by Google are based in the United States, and, in turn, most of these are based in or around the San Francisco Bay Area. To date, Alphabet has divested itself of four business units: Frommers, which was sold back to Arthur Frommer in April 2012; SketchUp, which was sold to Trimble in April 2012, Boston Dynamics in early 2016 and Google Radio Automation, which was sold to WideOrbit in 2009.
Many Google products originated as services provided by companies that Google has since acquired. For example, Google's first acquisition was the Usenet company Deja News, and its services became Google Groups. Similarly, Google acquired Dodgeball, a social networking service company, and eventually replaced it with Google Latitude. Other acquisitions include web application company JotSpot, which became Google Sites; Voice over IP company GrandCentral, which became Google Voice; and video hosting service company Next New Networks, which became YouTube Next Lab and Audience Development Group. CEO Larry Page has explained that potential acquisition candidates must pass a sort of "toothbrush test": Are their products potentially useful once or twice a day, and do they improve your life?
Following the acquisition of Israel-based startup Waze in June 2013, Google submitted a 10-Q filing with the Securities Exchange Commission (SEC) that revealed that the corporation spent $1.3 billion on acquisitions during the first half of 2013, with $966 million of that total going to Waze.
Discussed on
- "List Of Acquisitions By Google" | 2009-03-10 | 24 Upvotes 17 Comments
π Emacs + Vim + Haskell = Yi
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- "Emacs + Vim + Haskell = Yi" | 2009-02-28 | 40 Upvotes 8 Comments