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🔗 Spaceflight 🔗 Maps 🔗 Japan

The Quasi-Zenith Satellite System (QZSS) (Japanese: 準天頂衛星システム, Hepburn: juntenchō eisei shisutemu), also known as Michibiki (みちびき, "guidance"), is a regional navigation satellite system (RNSS) and a satellite-based augmentation system (SBAS) developed by the Japanese government to enhance the United States-operated Global Positioning System (GPS) in the Asia-Oceania regions, with a focus on Japan. The goal of QZSS is to provide highly precise and stable positioning services in the Asia-Oceania region, compatible with GPS. Four-satellite QZSS services were available on a trial basis as of 12 January 2018, and officially started on 1 November 2018. A satellite navigation system independent of GPS is planned for 2023 with seven satellites. In May 2023 it was announced that the system would expand to eleven satellites.

🔗 Technology 🔗 Disability

The optophone is a device, used by people who are blind, that scans text and generates time-varying chords of tones to identify letters. It is one of the earliest known applications of sonification. Dr. Edmund Fournier d'Albe of Birmingham University invented the optophone in 1913, which used selenium photosensors to detect black print and convert it into an audible output which could be interpreted by a blind person. The Glasgow company, Barr and Stroud, participated in improving the resolution and usability of the instrument.

Only a few units were built and reading was initially exceedingly slow; a demonstration at the 1918 Exhibition involved Mary Jameson reading at one word per minute. Later models of the Optophone allowed speeds of up to 60 words per minute, though only some subjects are able to achieve this rate.

🔗 Internet 🔗 Websites 🔗 Websites/Computing 🔗 Digital Preservation

The English Wikipedia has decided to stop using archive.today and its related websites. This decision was taken after a request for comment with more than 200 participants and is due to multiple concerns, including the site using editors' and readers' computers to run a denial-of-service attack and evidence that the website has tampered with some archived pages.

The addition of links to these websites is already being blocked by the edit filter, and it will likely be added to the spam blacklist in the future. Before that happens, we need everyone's help to replace or remove links to these websites. As of February 28, 2026, the citation templates in popular use on Wikipedia (WP:CS1 and WP:CS2) will not render Archive.today and affiliated archive URLs.

Note: Archive.org, or web.archive.org, run by the Internet Archive and the most-used web archive on Wikipedia, is uninvolved with and entirely separate from archive.today. Please keep using archive.org.

🔗 Ships

The Voith Schneider propeller (VSP), also known as a cycloidal drive is a specialized marine propulsion system (MPS). It is highly maneuverable, being able to change the direction of its thrust almost instantaneously. It is widely used on tugs and ferries.

🔗 Computer science

The inner-platform effect is the tendency of software architects to create a system so customizable as to become a replica, and often a poor replica, of the software development platform they are using. This is generally inefficient and such systems are often considered to be examples of an anti-pattern.

🔗 Aviation 🔗 Military history 🔗 Military history/Military aviation 🔗 Military history/Military science, technology, and theory 🔗 Military history/World War II 🔗 Military history/German military history 🔗 Military history/European military history 🔗 Military history/British military history

The Battle of the Beams was a period early in the Second World War when bombers of the German Air Force (Luftwaffe) used a number of increasingly accurate systems of radio navigation for night bombing in the United Kingdom. British scientific intelligence at the Air Ministry fought back with a variety of their own increasingly effective means, involving jamming and distortion of the radio waves. The period ended when the Wehrmacht moved their forces to the East in May 1941, in preparation for the attack on the Soviet Union.

🔗 Psychology 🔗 Linguistics 🔗 History of Science 🔗 Linguistics/Applied Linguistics 🔗 Portugal 🔗 Galicia

Saudade (European Portuguese: [sɐwˈðaðɨ] ; Brazilian Portuguese: [sawˈdadʒi] ; Galician: [sawˈðaðɪ]; Northeast Brazil: [sawˈdadi]). (English: ; plural saudades) in Portuguese and Galician is an emotional state of melancholic or profoundly nostalgic longing for a beloved yet absent someone or something. It derives from the Latin word for solitude. It is often associated with a repressed understanding that one might never encounter the object of longing ever again. It is a recollection of feelings, experiences, places, or events, often elusive, that cause a sense of separation from the exciting, pleasant, or joyous sensations they once caused. Duarte Nunes Leão defines saudade as, "Memory of something with a desire for it". In Brazil, the day of saudade is officially celebrated on 30 January. It is not a widely acknowledged day in Portugal.

🔗 Mathematics

Connes' embedding problem, formulated by Alain Connes in the 1970s, is a major problem in von Neumann algebra theory. During that time, the problem was reformulated in several different areas of mathematics. Dan Voiculescu developing his free entropy theory found that Connes' embedding problem is related to the existence of microstates. Some results of von Neumann algebra theory can be obtained assuming positive solution to the problem. The problem is connected to some basic questions in quantum theory, which led to the realization that it also has important implications in computer science.

The problem admits a number of equivalent formulations. Notably, it is equivalent to the following long standing problems:

• Kirchberg's QWEP conjecture in C*-algebra theory
• Tsirelson's problem in quantum information theory
• The predual of any (separable) von Neumann algebra is finitely representable in the trace class.

In January 2020, Ji, Natarajan, Vidick, Wright, and Yuen announced a result in quantum complexity theory that implies a negative answer to Connes' embedding problem. However, an error was discovered in September 2020 in an earlier result they used; a new proof avoiding the earlier result was published as a preprint in September. A broad outline was published in Communications of the ACM in November 2021, and an article explaining the connection between MIP*=RE and the Connes Embedding Problem appeared in October 2022.

🔗 Computing 🔗 Computing/Software 🔗 Computing/Free and open-source software 🔗 Linux

vi (pronounced as two letters, ) is a screen-oriented text editor originally created for the Unix operating system. The portable subset of the behavior of vi and programs based on it, and the ex editor language supported within these programs, is standardized by the Single Unix Specification and POSIX.

vi is actually a mode of the earlier ex editor. Originally, ex lacked a full-screen editing capability, but in 1976, Bill Joy enhanced it to support a visual mode. The program was updated to start in visual mode when launched with the command vi instead of the legacy mode when launched via the ex command. In this way, ex and vi are the same program, not two programs. Joy's ex 1.1 was released as part of the first Berkeley Software Distribution (BSD) Unix release in March 1978. It was not until version 2.0 of ex, released as part of Second BSD in May 1979 that the editor was installed under the name "vi" which took a user straight into ex's visual mode.

Some implementations of vi trace their source code ancestry to Bill Joy's work. Others are completely new, largely compatible clones.

The name "vi" comes from the shortest unambiguous abbreviation of the ex command visual, which switches the ex line editor into full-screen mode.

In addition to various non–free software variants of vi distributed with proprietary implementations of Unix, vi was opensourced with OpenSolaris, and several free and open source software vi clones exist. A 2009 survey of Linux Journal readers found that vi was the most widely used text editor among respondents, beating gedit, the second most widely used editor, by nearly a factor of two (36% to 19%).

🔗 Technology 🔗 Software 🔗 Software/Computing 🔗 Apps

Bitchat is a peer-to-peer encrypted messaging app developed by Jack Dorsey, co‑founder of Twitter (now X) and Block, Inc. Announced in July 2025, Bitchat enables users to send messages via Bluetooth Low Energy (BLE) mesh networks without requiring internet connections, cellular service, user accounts, or central servers. Bitchat also uses the internet-based Nostr protocol for global reach.