Have a deep view into what people are curious about.

🔗 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".

🔗 Computing 🔗 Computing/Early computers

The IBM 7030, also known as Stretch, was IBM's first transistorized supercomputer. It was the fastest computer in the world from 1961 until the first CDC 6600 became operational in 1964.

Originally designed to meet a requirement formulated by Edward Teller at Lawrence Livermore National Laboratory, the first example was delivered to Los Alamos National Laboratory in 1961, and a second customized version, the IBM 7950 Harvest, to the National Security Agency in 1962. The Stretch at the Atomic Weapons Research Establishment at Aldermaston, England was heavily used by researchers there and at AERE Harwell, but only after the development of the S2 Fortran Compiler which was the first to add dynamic arrays, and which was later ported to the Ferranti Atlas of Atlas Computer Laboratory at Chilton.

Since the 7030 was much slower than expected and failed to meet its aggressive performance estimates, IBM was forced to drop its price from $13.5 million to only $7.78 million and withdrew the 7030 from sales to customers beyond those having already negotiated contracts. PC World magazine named Stretch one of the biggest project management failures in IT history.

Within IBM, being eclipsed by the smaller Control Data Corporation seemed hard to accept. The project lead, Stephen W. Dunwell, was initially blackballed for his role in the "failure", but as the success of the IBM System/360 became obvious, he was given an official apology and, in 1966 was made an IBM Fellow.

In spite of Stretch's failure to meet its own performance goals, it served as the basis for many of the design features of the successful IBM System/360, which shipped in 1964.

🔗 Computing 🔗 Computing/Computer hardware 🔗 Computing/Software

In computing, a Parallel Sysplex is a cluster of IBM mainframes acting together as a single system image with z/OS. Used for disaster recovery, Parallel Sysplex combines data sharing and parallel computing to allow a cluster of up to 32 systems to share a workload for high performance and high availability.

🔗 Mathematics 🔗 Greece

Greek numerals, also known as Ionic, Ionian, Milesian, or Alexandrian numerals, are a system of writing numbers using the letters of the Greek alphabet. In modern Greece, they are still used for ordinal numbers and in contexts similar to those in which Roman numerals are still used elsewhere in the West. For ordinary cardinal numbers, however, Greece uses Arabic numerals.

🔗 Biology

The thermal grill illusion is a sensory illusion originally demonstrated in 1896 by the Swedish physician Torsten Thunberg. The illusion is created by an interlaced grill of warm (e.g., 40°C/104°F) and cool (20°C/68°F) bars. When someone presses a hand against the grill, they experience the illusion of burning heat. But if the person presses against only a cool bar, only coolness is experienced; if the person presses against only a warm bar, only warmth is experienced.

Researchers have used the illusion to demonstrate that burning pain sensation is in fact a mixture of both cold and heat pain and that it is only the inhibition of the cold pain "channel" that reveals the heat component.

The illusion is demonstrated by positioning the middle finger in cold water and the ring and index fingers in warm water. Due to shortcomings in the body map - multisensory representation of the body - and this particular sensory input configuration, the brain is tricked into thinking the middle finger is in the warm water and the index and ring fingers in cold water.

In an fMRI experiment of the illusion, researchers recently observed an activation of the thalamus not seen for control stimuli. Also, activity in a portion of the right mid/anterior insula correlated with the perceived unpleasantness of the illusion.

🔗 Biography 🔗 Computing 🔗 Business 🔗 Biography/science and academia 🔗 New York (state) 🔗 Criminal Biography 🔗 Computing/Computer Security 🔗 New Jersey 🔗 New York (state)/Cornell University 🔗 Computing/Networking

Robert Tappan Morris (born November 8, 1965) is an American computer scientist and entrepreneur. He is best known for creating the Morris worm in 1988, considered the first computer worm on the Internet.

Morris was prosecuted for releasing the worm, and became the first person convicted under the then-new Computer Fraud and Abuse Act. He went on to co-found the online store Viaweb, one of the first web-based applications, and later the funding firm Y Combinator—both with Paul Graham.

He later joined the faculty in the department of Electrical Engineering and Computer Science at the Massachusetts Institute of Technology, where he received tenure in 2006. He was elected to the National Academy of Engineering in 2019.

🔗 Sociology 🔗 Organizations 🔗 Media 🔗 Culture 🔗 Sociology/social movements 🔗 Toys

The Barbie Liberation Organization or BLO, sponsored by RTMark, were a group of artists and activists involved in culture jamming. They gained notoriety in 1993 after switching voice boxes in talking G.I. Joes and Barbie dolls. The BLO performed "surgery" on a reported 300–500 dolls from retail and returned them to shelves, an action they refer to as shopgiving. Thus, Teen Talk Barbie dolls would say phrases such as "Vengeance is mine", while G.I. Joe dolls would say phrases such as "The beach is the place for summer!"

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

netcat (often abbreviated to nc) is a computer networking utility for reading from and writing to network connections using TCP or UDP. The command is designed to be a dependable back-end that can be used directly or easily driven by other programs and scripts. At the same time, it is a feature-rich network debugging and investigation tool, since it can produce almost any kind of connection its user could need and has a number of built-in capabilities.

Its list of features includes port scanning, transferring files, and port listening, and it can be used as a backdoor.

🔗 Numbers 🔗 Law

An illegal number is a number that represents information which is illegal to possess, utter, propagate, or otherwise transmit in some legal jurisdiction. Any piece of digital information is representable as a number; consequently, if communicating a specific set of information is illegal in some way, then the number may be illegal as well.