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๐ Citicorp Center Engineering Crisis
The Citicorp Center engineering crisis was the discovery, in 1978, of a significant structural flaw in Citicorp Center, then a recently completed skyscraper in New York City, and the subsequent effort to quietly make repairs over the next few months. The building, now known as Citigroup Center, occupied an entire block and was to be the headquarters of Citibank. Its structure, designed by William LeMessurier, had several unusual design features, including a raised base supported by four offset stilts, and diagonal bracing which absorbed wind loads from upper stories.
In the original design, potential wind loads for the building were calculated incorrectly. The flaw was discovered by Diane Hartley, an undergraduate student at Princeton University who was writing a thesis on the building, and was communicated to the firm responsible for the structural design. LeMessurier was subsequently lauded for acknowledging his error and orchestrating a successful repair effort. Estimates at the time suggested that the building could be toppled by a 70-mile-per-hour (110ย km/h) wind, with possibly many people killed as a result. The crisis was kept secret until 1995 and Hartley had no knowledge of the significance of her work until after that time.
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- "Citicorp Center Engineering Crisis" | 2022-05-21 | 18 Upvotes 1 Comments
๐ CorsiโRosenthal Box
The CorsiโRosenthal Box, also called a CorsiโRosenthal Cube or a Comparetto Cube, is a design for a do-it-yourself air purifier that can be built comparatively inexpensively. It was designed during the COVID-19 pandemic with the goal of reducing the levels of airborne viral particles in indoor settings.
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- "CorsiโRosenthal Box" | 2022-05-19 | 81 Upvotes 21 Comments
๐ QB64
QB64 (originally QB32) is a self-hosting BASIC compiler for Microsoft Windows, Linux and Mac OS X, designed to be compatible with Microsoft QBasic and QuickBASIC. QB64 is a C++ emitter, which is integrated with a C++ compiler to provide compilation via C++ code and GCC optimization.
QB64 implements most QBasic statements, and can run many QBasic programs, including Microsoft's QBasic Gorillas and Nibbles games. Furthermore, QB64 has been designed to contain an IDE resembling the QBASIC IDE. QB64 also extends the QBASIC programming language to include 64-bit data types, as well as better sound and graphics support. It can also emulate some DOS/x86 specific features such as INT 33h mouse access, and multiple timers.
Since version 2.0, QB64 now offers debugging abilities, with the new $DEBUG metacommand.
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- "QB64" | 2022-05-17 | 14 Upvotes 1 Comments
๐ Unsolved Problems in Economics
This is a list of some of the major unsolved problems, puzzles, or questions in economics. Some of these are theoretical in origin and some of them concern the inability of orthodox economic theory to explain an empirical observation.
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- "Unsolved Problems in Economics" | 2022-05-17 | 157 Upvotes 237 Comments
๐ List of territory purchased by a sovereign nation from another sovereign nation
This is a list of purchases of territory by a sovereign nation from another sovereign nation.
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- "List of territory purchased by a sovereign nation from another sovereign nation" | 2022-05-16 | 10 Upvotes 1 Comments
๐ Soundies
Soundies are three-minute American musical films, produced between 1940 and 1947, each displaying a song, dance, and/or band or orchestral number. Produced professionally on 35 mm black-and-white film, like theatrical motion pictures, they were printed on the more portable and economical 16 mm film.
The films were shown in a coin-operated "movie jukebox" named the Panoram, manufactured by the Mills Novelty Company of Chicago. Each Panoram housed a 16 mm RCA film projector, with eight Soundies films threaded in an endless-loop arrangement. A system of mirrors flashed the image from the lower half of the cabinet onto a front-facing screen in the top half. Each film cost 10 cents to play, with no choice of song; the patron saw whatever film was next in the queue. Panorams could be found in public amusement centers, nightclubs, taverns, restaurants, and factory lounges, and the films were changed weekly. The completed Soundies were generally made available within a few weeks of their filming, by the Soundies Distributing Corporation of America.
Several production companies filmed the Soundies shorts in New York City, Hollywood, and Chicago: James Roosevelt's Globe Productions (1940โ41), Cinemasters (1940โ41), Minoco Productions (owned by Mills Novelty, 1941โ43), RCM Productions (1941โ46), LOL Productions (1943), Glamourettes (1943), Filmcraft Productions (1943โ46), and Alexander Productions (1946) led by William D. Alexander). The performers recorded the music in advance, and mimed to the soundtrack during filming.
The movie-jukebox idea developed several imitations and variations of the technical design; the most successful of these imitators were the Techniprocess company (managed by Rudy Vallee) and the Featurettes company, which used original novelty songs and usually unknown talent (17-year-old Gwen Verdon appears in a couple of the Featurettes as "Gwen Verdun"). As Soundies quickly gained most of the market for jukebox films, the other companies disbanded, and some sold their films to the Soundies concern.
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- "Soundies" | 2022-05-12 | 40 Upvotes 12 Comments
๐ The Nature of the Firm (1937)
"The Nature of the Firm" (1937) is an article by Ronald Coase. It offered an economic explanation of why individuals choose to form partnerships, companies and other business entities rather than trading bilaterally through contracts on a market. The author was awarded the Nobel Memorial Prize in Economic Sciences in 1991 in part due to this paper. Despite the honor, the paper was written when Coase was an undergraduate and he described it later in life as "little more than an undergraduate essay."
The article argues that firms emerge because they are better equipped to deal with the transaction costs inherent in production and exchange than individuals are. Economists such as Oliver Williamson, Douglass North, Oliver Hart, Bengt Holmstrรถm, Arman Alchian and Harold Demsetz expanded on Coase's work on firms, transaction costs and contracts. Economists and political scientists have used insights from Coase's work to explain the functioning of organizations in general, not just firms. Coase's work strongly influenced the New Economics of Organization (New Institutional Economics).
Coase's article distinguished between markets as a coordination mechanism and firms as a coordination mechanism.
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- "The Nature of the Firm (1937)" | 2022-05-13 | 132 Upvotes 56 Comments
๐ Volume of an n-ball tends to a limiting value of 0 as n goes to infinity
In geometry, a ball is a region in a space comprising all points within a fixed distance, called the radius, from a given point; that is, it is the region enclosed by a sphere or hypersphere. An n-ball is a ball in an n-dimensional Euclidean space. The volume of a n-ball is the Lebesgue measure of this ball, which generalizes to any dimension the usual volume of a ball in 3-dimensional space. The volume of a n-ball of radius R is where is the volume of the unit n-ball, the n-ball of radius 1.
The real number can be expressed by a expression involving the gamma function. It can be computed with several recurrence relations. It can be expressed in terms of the area of the unit n-sphere.
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- "Volume of an n-ball tends to a limiting value of 0 as n goes to infinity" | 2022-05-12 | 90 Upvotes 50 Comments
๐ Project Denver
Project Denver is the codename of a microarchitecture designed by Nvidia that implements the ARMv8-A 64/32-bit instruction sets using a combination of simple hardware decoder and software-based binary translation (dynamic recompilation) where "Denver's binary translation layer runs in software, at a lower level than the operating system, and stores commonly accessed, already optimized code sequences in a 128ย MB cache stored in main memory". Denver is a very wide in-order superscalar pipeline. Its design makes it suitable for integration with other SIPs cores (e.g. GPU, display controller, DSP, image processor, etc.) into one die constituting a system on a chip (SoC).
Project Denver is targeted at mobile computers, personal computers, servers, as well as supercomputers. Respective cores have found integration in the Tegra SoC series from Nvidia. Initially Denver cores was designed for the 28nm process node (Tegra model T132 aka "Tegra K1"). Denver 2 was an improved design that built for the smaller, more efficient 16nm node. (Tegra model T186 aka "Tegra X2").
In 2018, Nvidia released an improved design (codename: "Carmel", based on ARMv8 (64-bit; variant: ARM-v8.2 with 10-way superscalar, functional safety, dual execution, parity & ECC) got integrated into the Tegra Xavier SoC offering a total of 8 cores (or 4 dual-core pairs). The Carmel CPU core supports full Advanced SIMD (ARM NEON), VFP (Vector Floating Point), and ARMv8.2-FP16. First published testings of Carmel cores integrated in the Jetson AGX development kit by third party experts took place in September 2018 and indicated a noticeably increased performance as should expected for this real world physical manifestation compared to predecessors systems, despite all doubts the used quickness of such a test setup in general an in particular implies. The Carmel design can be found in the Tegra model T194 ("Tegra Xavier") that is designed with a 12 nm structure size.
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- "Project Denver" | 2022-05-08 | 23 Upvotes 8 Comments
๐ Mono No Aware
Mono no aware (็ฉใฎๅใ), literally "the pathos of things", and also translated as "an empathy toward things", or "a sensitivity to ephemera", is a Japanese idiom for the awareness of impermanence (็กๅธธ, mujล), or transience of things, and both a transient gentle sadness (or wistfulness) at their passing as well as a longer, deeper gentle sadness about this state being the reality of life.
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- "Mono No Aware" | 2022-05-05 | 27 Upvotes 4 Comments