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🔗 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.

🔗 Technology 🔗 Medicine

The Corsi–Rosenthal Box, also called a Corsi–Rosenthal 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.

🔗 Technology 🔗 Physics 🔗 Ancient Near East 🔗 Ancient Egypt 🔗 Archaeology 🔗 Spectroscopy 🔗 Blades

Tutankhamun's meteoric iron dagger, also known as Tutankhamun's iron dagger and King Tut's dagger, is an iron-bladed dagger from the tomb of the ancient Egyptian Pharaoh Tutankhamun (reigned c. 1334–1325 BC). As the blade composition and homogeneity closely correlate with meteorite composition and homogeneity, the material for the blade is determined to have originated by way of a meteoritic landing. The dagger is currently displayed at the Egyptian Museum in Cairo.

🔗 Technology 🔗 Physics 🔗 Energy

The Crookes radiometer (also known as a light mill) consists of an airtight glass bulb containing a partial vacuum, with a set of vanes which are mounted on a spindle inside. The vanes rotate when exposed to light, with faster rotation for more intense light, providing a quantitative measurement of electromagnetic radiation intensity.

The reason for the rotation was a cause of much scientific debate in the ten years following the invention of the device, but in 1879 the currently accepted explanation for the rotation was published. Today the device is mainly used in physics education as a demonstration of a heat engine run by light energy.

It was invented in 1873 by the chemist Sir William Crookes as the by-product of some chemical research. In the course of very accurate quantitative chemical work, he was weighing samples in a partially evacuated chamber to reduce the effect of air currents, and noticed the weighings were disturbed when sunlight shone on the balance. Investigating this effect, he created the device named after him.

It is still manufactured and sold as an educational aid or for curiosity.

🔗 Technology 🔗 Physics 🔗 Telecommunications 🔗 Radio 🔗 Electronics 🔗 Engineering

In antenna theory, a phased array usually means an electronically scanned array, a computer-controlled array of antennas which creates a beam of radio waves that can be electronically steered to point in different directions without moving the antennas. The general theory of an electromagnetic phased array also finds applications in ultrasonic and medical imaging application (phased array ultrasonics) and in optics optical phased array.

In a simple array antenna, the radio frequency current from the transmitter is fed to multiple individual antenna elements with the proper phase relationship so that the radio waves from the separate elements combine (superpose) to form beams, to increase power radiated in desired directions and suppress radiation in undesired directions. In a phased array, the power from the transmitter is fed to the radiating elements through devices called phase shifters, controlled by a computer system, which can alter the phase or signal delay electronically, thus steering the beam of radio waves to a different direction. Since the size of an antenna array must extend many wavelengths to achieve the high gain needed for narrow beamwidth, phased arrays are mainly practical at the high frequency end of the radio spectrum, in the UHF and microwave bands, in which the operating wavelengths are conveniently small.

Phased arrays were originally conceived for use in military radar systems, to steer a beam of radio waves quickly across the sky to detect planes and missiles. These systems are now widely used and have spread to civilian applications such as 5G MIMO for cell phones. The phased array principle is also used in acoustics, and phased arrays of acoustic transducers are used in medical ultrasound imaging scanners (phased array ultrasonics), oil and gas prospecting (reflection seismology), and military sonar systems.

The term "phased array" is also used to a lesser extent for unsteered array antennas in which the phase of the feed power and thus the radiation pattern of the antenna array is fixed. For example, AM broadcast radio antennas consisting of multiple mast radiators fed so as to create a specific radiation pattern are also called "phased arrays".

🔗 Technology 🔗 Energy

A solar pond is a pool of saltwater which collects and stores solar thermal energy. The saltwater naturally forms a vertical salinity gradient also known as a "halocline", in which low-salinity water floats on top of high-salinity water. The layers of salt solutions increase in concentration (and therefore density) with depth. Below a certain depth, the solution has a uniformly high salt concentration.

🔗 Technology 🔗 Computing 🔗 Electronics

A supercomputer is a computer with a high level of performance as compared to a general-purpose computer. The performance of a supercomputer is commonly measured in floating-point operations per second (FLOPS) instead of million instructions per second (MIPS). Since 2017, there are supercomputers which can perform over a hundred quadrillion FLOPS (petaFLOPS). Since November 2017, all of the world's fastest 500 supercomputers run Linux-based operating systems. Additional research is being conducted in China, the United States, the European Union, Taiwan and Japan to build faster, more powerful and technologically superior exascale supercomputers.

Supercomputers play an important role in the field of computational science, and are used for a wide range of computationally intensive tasks in various fields, including quantum mechanics, weather forecasting, climate research, oil and gas exploration, molecular modeling (computing the structures and properties of chemical compounds, biological macromolecules, polymers, and crystals), and physical simulations (such as simulations of the early moments of the universe, airplane and spacecraft aerodynamics, the detonation of nuclear weapons, and nuclear fusion). They have been essential in the field of cryptanalysis.

Supercomputers were introduced in the 1960s, and for several decades the fastest were made by Seymour Cray at Control Data Corporation (CDC), Cray Research and subsequent companies bearing his name or monogram. The first such machines were highly tuned conventional designs that ran faster than their more general-purpose contemporaries. Through the decade, increasing amounts of parallelism were added, with one to four processors being typical. From the 1970s, vector processors operating on large arrays of data came to dominate. A notable example is the highly successful Cray-1 of 1976. Vector computers remained the dominant design into the 1990s. From then until today, massively parallel supercomputers with tens of thousands of off-the-shelf processors became the norm.

The US has long been the leader in the supercomputer field, first through Cray's almost uninterrupted dominance of the field, and later through a variety of technology companies. Japan made major strides in the field in the 1980s and 90s, with China becoming increasingly active in the field. As of November 2018, the fastest supercomputer on the TOP500 supercomputer list is the Summit, in the United States, with a LINPACK benchmark score of 143.5 PFLOPS, followed by, Sierra, by around 48.860 PFLOPS. The US has five of the top 10 and China has two. In June 2018, all supercomputers on the list combined broke the 1 exaFLOPS mark.

🔗 Technology

Tensegrity, tensional integrity or floating compression is a structural principle based on a system of isolated components under compression inside a network of continuous tension, and arranged in such a way that the compressed members (usually bars or struts) do not touch each other while the prestressed tensioned members (usually cables or tendons) delineate the system spatially.

The term was coined by Buckminster Fuller in the 1960s as a portmanteau of "tensional integrity". The other denomination of tensegrity, floating compression, was used mainly by the constructivist artist Kenneth Snelson.

🔗 United States 🔗 Technology 🔗 Aviation 🔗 Military history 🔗 Military history/Military aviation 🔗 Military history/North American military history 🔗 Military history/United States military history 🔗 Military history/Military science, technology, and theory 🔗 Canada 🔗 Aviation/aircraft 🔗 Engineering 🔗 Cold War 🔗 Military history/Military land vehicles 🔗 Military history/Canadian military history

The Avro Canada VZ-9 Avrocar was a VTOL aircraft developed by Avro Canada as part of a secret U.S. military project carried out in the early years of the Cold War. The Avrocar intended to exploit the Coandă effect to provide lift and thrust from a single "turborotor" blowing exhaust out the rim of the disk-shaped aircraft. In the air, it would have resembled a flying saucer.

Originally designed as a fighter-like aircraft capable of very high speeds and altitudes, the project was repeatedly scaled back over time and the U.S. Air Force eventually abandoned it. Development was then taken up by the U.S. Army for a tactical combat aircraft requirement, a sort of high-performance helicopter. In flight testing, the Avrocar proved to have unresolved thrust and stability problems that limited it to a degraded, low-performance flight envelope; subsequently, the project was cancelled in September 1961.

Through the history of the program, the project was referred to by a number of different names. Avro referred to the efforts as Project Y, with individual vehicles known as Spade and Omega. Project Y-2 was later funded by the U.S. Air Force, who referred to it as WS-606A, Project 1794 and Project Silver Bug. When the U.S. Army joined the efforts it took on its final name "Avrocar", and the designation "VZ-9", part of the U.S. Army's VTOL projects in the VZ series.

🔗 California 🔗 Companies 🔗 Technology 🔗 Private Equity 🔗 California/San Francisco Bay Area

Y Combinator is an American seed accelerator launched in March 2005 and has been used to launch over 2,000 companies including Stripe, Airbnb, Cruise Automation, DoorDash, Coinbase, Instacart, and Dropbox. The combined valuation of the top YC companies was over $155 billion as of October, 2019.