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π Intel iAPX 432
The iAPX 432 (Intel Advanced Performance Architecture) is a discontinued computer architecture introduced in 1981. It was Intel's first 32-bit processor design. The main processor of the architecture, the general data processor, is implemented as a set of two separate integrated circuits, due to technical limitations at the time. Although some early 8086, 80186 and 80286-based systems and manuals also used the iAPX prefix for marketing reasons, the iAPX 432 and the 8086 processor lines are completely separate designs with completely different instruction sets.
The project started in 1975 as the 8800 (after the 8008 and the 8080) and was intended to be Intel's major design for the 1980s. Unlike the 8086, which was designed the following year as a successor to the 8080, the iAPX 432 was a radical departure from Intel's previous designs meant for a different market niche, and completely unrelated to the 8080 or x86 product lines.
The iAPX 432 project is considered a commercial failure for Intel, and was discontinued in 1986.
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- "Intel iAPX 432" | 2022-08-10 | 52 Upvotes 34 Comments
π Theory of Constraints
The theory of constraints (TOC) is a management paradigm that views any manageable system as being limited in achieving more of its goals by a very small number of constraints. There is always at least one constraint, and TOC uses a focusing process to identify the constraint and restructure the rest of the organization around it. TOC adopts the common idiom "a chain is no stronger than its weakest link". That means that organizations and processes are vulnerable because the weakest person or part can always damage or break them, or at least adversely affect the outcome.
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- "Theory of Constraints" | 2024-05-01 | 122 Upvotes 64 Comments
π Pessimism Porn
Pessimism porn is a neologism coined in 2009 during the 2007β2012 global financial crisis to describe the alleged eschatological and survivalist thrill some people derive from predicting, reading and fantasizing about the collapse of civil society through the destruction of the world's economic system.
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- "Pessimism Porn" | 2016-09-05 | 13 Upvotes 1 Comments
π Hagia Triada Sarcophagus
The Hagia Triada Sarcophagus is a late Minoan 137Β cm (54Β in)-long limestone sarcophagus, dated to about 1400 BC or some decades later, excavated from a chamber tomb at Hagia Triada, Crete in 1903, and now on display in the Heraklion Archaeological Museum ("AMH") in Crete.
Uniquely for such a piece from this date on Crete, it is coated in plaster and painted in fresco on all faces. Otherwise the Minoans (unlike the ancient Egyptians) only used frescoes to decorate palaces and houses for the enjoyment of the living and not in funerary practice. It is the only limestone sarcophagus of its era discovered to date; there are a number of smaller terracotta "ash-chests" (larnax), painted far more crudely, usually in a single colour. It is the only object with a series of narrative scenes of Minoan funerary ritual (later sarcophagi found in the Aegean were decorated with abstract designs and patterns). It was probably originally used for the burial of a prince.
It provides probably the most comprehensive iconography of a pre-Homeric thysiastikis ceremony and one of the best pieces of information on noble burial customs when Crete was under Mycenaean rule, combining features of Minoan and Mycenaean style and subject matter, as well as probable influence from Ancient Egyptian religion.
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- "Hagia Triada Sarcophagus" | 2022-02-10 | 42 Upvotes 1 Comments
π Digital Radio Frequency Memory (DRFM)
Digital Radio Frequency Memory (DRFM) is an electronic method for digitally capturing and retransmitting RF signals. DRFM systems are typically used in radar jamming, although applications in cellular communications are becoming more common.
π Oriental Carpets in Renaissance Painting
Carpets of Middle-Eastern origin, either from Anatolia, Persia, Armenia, Azerbaijan, the Levant, the Mamluk state of Egypt or Northern Africa, were used as decorative features in Western European paintings from the 14th century onwards. More depictions of Oriental carpets in Renaissance painting survive than actual carpets contemporary with these paintings. Few Middle-Eastern carpets produced before the 17th century remain, though the number of these known has increased in recent decades. Therefore, comparative art-historical research has from its onset in the late 19th century relied on carpets represented in datable European paintings.
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- "Oriental Carpets in Renaissance Painting" | 2020-09-12 | 36 Upvotes 14 Comments
π Carrington Event
The Carrington Event was the most intense geomagnetic storm in recorded history, peaking from 1β2 September 1859 during solar cycle 10. It created strong auroral displays that were reported globally and caused sparking and even fires in multiple telegraph stations. The geomagnetic storm was most likely the result of a coronal mass ejection (CME) from the Sun colliding with Earth's magnetosphere.
The geomagnetic storm was associated with a very bright solar flare on 1 September 1859. It was observed and recorded independently by British astronomers Richard Christopher Carrington and Richard Hodgsonβthe first records of a solar flare.
A geomagnetic storm of this magnitude occurring today would cause widespread electrical disruptions, blackouts, and damage due to extended outages of the electrical power grid.
Discussed on
- "Carrington Event" | 2024-05-12 | 43 Upvotes 16 Comments
π Gravity Probe B
Gravity Probe B (GP-B) was a satellite-based experiment to test two unverified predictions of general relativity: the geodetic effect and frame-dragging. This was to be accomplished by measuring, very precisely, tiny changes in the direction of spin of four gyroscopes contained in an Earth-orbiting satellite at 650Β km (400Β mi) altitude, crossing directly over the poles.
The satellite was launched on 20 April 2004 on a Delta II rocket. The spaceflight phase lasted until ; Its aim was to measure spacetime curvature near Earth, and thereby the stressβenergy tensor (which is related to the distribution and the motion of matter in space) in and near Earth. This provided a test of general relativity, gravitomagnetism and related models. The principal investigator was Francis Everitt.
Initial results confirmed the expected geodetic effect to an accuracy of about 1%. The expected frame-dragging effect was similar in magnitude to the current noise level (the noise being dominated by initially unmodeled effects due to nonuniform coatings on the gyroscopes). Work continued to model and account for these sources of error, thus permitting extraction of the frame-dragging signal. By , the frame-dragging effect had been confirmed to within 15% of the expected result, and the NASA report indicated that the geodetic effect was confirmed to be better than 0.5%.
In an article published in the journal Physical Review Letters in , the authors reported analysis of the data from all four gyroscopes results in a geodetic drift rate of β6601.8Β±18.3Β mas/yr and a frame-dragging drift rate of β37.2Β±7.2Β mas/yr, in good agreement with the general relativity predictions of β6606.1Β±0.28%Β mas/yr and β39.2Β±0.19%Β mas/yr, respectively.
Discussed on
- "Gravity Probe B" | 2022-08-14 | 70 Upvotes 15 Comments
π Bessel Beam
A Bessel beam is a wave whose amplitude is described by a Bessel function of the first kind. Electromagnetic, acoustic, gravitational, and matter waves can all be in the form of Bessel beams. A true Bessel beam is non-diffractive. This means that as it propagates, it does not diffract and spread out; this is in contrast to the usual behavior of light (or sound), which spreads out after being focused down to a small spot. Bessel beams are also self-healing, meaning that the beam can be partially obstructed at one point, but will re-form at a point further down the beam axis.
As with a plane wave, a true Bessel beam cannot be created, as it is unbounded and would require an infinite amount of energy. Reasonably good approximations can be made, however, and these are important in many optical applications because they exhibit little or no diffraction over a limited distance. Approximations to Bessel beams are made in practice either by focusing a Gaussian beam with an axicon lens to generate a BesselβGauss beam, by using axisymmetric diffraction gratings, or by placing a narrow annular aperture in the far field. High order Bessel beams can be generated by spiral diffraction gratings.
Discussed on
- "Bessel Beam" | 2018-08-27 | 34 Upvotes 10 Comments
π Microformats
Microformats (ΞΌF) are predefined HTML markup (like HTML classes) created to serve as descriptive and consistent metadata about elements, designating them as representing a certain type of data (such as contact information, geographic coordinates, events, products, recipes, etc.). They allow software to process the information reliably by having set classes refer to a specific type of data rather than being arbitrary.
Microformats emerged around 2005 and were predominantly designed for use by search engines, web syndication and aggregators such as RSS. Google confirmed in 2020 that it still parses microformats for use in content indexing. Microformats are referenced in several W3C social web specifications, including IndieAuth and Webmention.
Although the content of web pages has been capable of some "automated processing" since the inception of the web, such processing is difficult because the markup elements used to display information on the web do not describe what the information means. Microformats can bridge this gap by attaching semantics, and thereby obviating other, more complicated, methods of automated processing, such as natural language processing or screen scraping. The use, adoption and processing of microformats enables data items to be indexed, searched for, saved or cross-referenced, so that information can be reused or combined.
As of 2013, microformats allow the encoding and extraction of event details, contact information, social relationships and similar information.
Microformats2, abbreviated as mf2, is the updated version of microformats. Mf2 provides an easier way of interpreting HTML structured syntax and vocabularies than the earlier ways that made use of RDFa and microdata.