Topic: Electrical engineering

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πŸ”— Nvidia’s CEO Is the Uncle of AMD’s CEO

πŸ”— Biography πŸ”— Computing πŸ”— Computing/Computer hardware πŸ”— Business πŸ”— Women scientists πŸ”— Biography/science and academia πŸ”— Electrical engineering πŸ”— Taiwan πŸ”— Women in Business

Lisa Su (Chinese: θ˜‡ε§ΏδΈ°; Pe̍h-ōe-jΔ«: So͘ Chu-hong; born 7 November 1969) is a Taiwanese-born American business executive and electrical engineer, who is the president, chief executive officer and chair of AMD. Early in her career, Su worked at Texas Instruments, IBM, and Freescale Semiconductor in engineering and management positions. She is known for her work developing silicon-on-insulator semiconductor manufacturing technologies and more efficient semiconductor chips during her time as vice president of IBM's Semiconductor Research and Development Center.

Su was appointed president and CEO of AMD in October 2014, after joining the company in 2012 and holding roles such as senior vice president of AMD's global business units and chief operating officer. She currently serves on the boards of Cisco Systems, Global Semiconductor Alliance and the U.S. Semiconductor Industry Association, and is a fellow of the Institute of Electrical and Electronics Engineers (IEEE). Recognized with a number of awards and accolades, she was named Executive of the Year by EE Times in 2014 and one of the World's Greatest Leaders in 2017 by Fortune. She became the first woman to receive the IEEE Robert Noyce Medal in 2021.

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πŸ”— Asynchronous (Clockless) CPU

πŸ”— Computing πŸ”— Electronics πŸ”— Electrical engineering

An asynchronous circuit, or self-timed circuit, is a sequential digital logic circuit which is not governed by a clock circuit or global clock signal. Instead it often uses signals that indicate completion of instructions and operations, specified by simple data transfer protocols. This type of circuit is contrasted with synchronous circuits, in which changes to the signal values in the circuit are triggered by repetitive pulses called a clock signal. Most digital devices today use synchronous circuits. However asynchronous circuits have the potential to be faster, and may also have advantages in lower power consumption, lower electromagnetic interference, and better modularity in large systems. Asynchronous circuits are an active area of research in digital logic design.

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πŸ”— LK-99

πŸ”— Korea πŸ”— Physics πŸ”— Chemicals πŸ”— Electrical engineering πŸ”— Materials

LK-99 is a proposed ambient pressure and room-temperature superconductor with a grayβ€’black appearance.:β€Š8β€Š LK-99 has a hexagonal structure slightly modified from leadβ€’apatite and is claimed to function as a superconductor below 400Β K (127Β Β°C; 260Β Β°F).:β€Š1β€Š The material was investigated by a team of Sukbae Lee et al. from the Korea Institute of Science and Technology (KIST).:β€Š1β€Š As of 26Β JulyΒ 2023 the discovery of LK-99 has not been peer reviewed or independently replicated.

The chemical composition of LK-99 is approximately Pb9Cu(PO4)6O such thatβ€”compared to pure lead-apatite (Pb10(PO4)6O):β€Š5β€Šβ€”approximately one quarter of Pb(2) ions are replaced by Cu(II) ions.:β€Š9β€Š This partial replacement of Pb2+ ions (measuring 133 picometre) with Cu2+ ions (measuring 87 picometre) is said to cause a 0.48% reduction in volume, creating internal stress inside the material.:β€Š8β€Š

The internal stress is claimed to cause a heterojunction quantum well between the Pb(1) and oxygen within the phosphate ([PO4]3βˆ’) generating a superconducting quantum well (SQW).:β€Š10β€Š Lee et al claim to show LK-99 exhibits a response to a magnetic field (Meissner effect) when chemical vapor deposition is used to apply LK-99 to a non-magnetic copper sample.:β€Š4β€Š Pure lead-apatite is an insulator, but Lee et al claim copper-doped lead-apatite forming LK-99 is a superconductor, or at higher temperatures, a metal.:β€Š5β€Š

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  • "LK-99" | 2023-07-27 | 101 Upvotes 58 Comments

πŸ”— Oliver Heaviside

πŸ”— Biography πŸ”— Mathematics πŸ”— Physics πŸ”— Telecommunications πŸ”— Biography/science and academia πŸ”— Energy πŸ”— Electrical engineering πŸ”— Physics/Biographies πŸ”— Devon

Oliver Heaviside FRS (; 18 May 1850 – 3 February 1925) was an English self-taught electrical engineer, mathematician, and physicist who adapted complex numbers to the study of electrical circuits, invented mathematical techniques for the solution of differential equations (equivalent to Laplace transforms), reformulated Maxwell's field equations in terms of electric and magnetic forces and energy flux, and independently co-formulated vector analysis. Although at odds with the scientific establishment for most of his life, Heaviside changed the face of telecommunications, mathematics, and science.

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πŸ”— Charlieplexing

πŸ”— Computing πŸ”— Electronics πŸ”— Electrical engineering

Charlieplexing (also known as tristate multiplexing, reduced pin-count LED multiplexing, complementary LED drive and crossplexing) is a technique for accessing a large number of LEDs, switches, micro-capacitors or other I/O entities, using very few tri-state logic wires from a microcontroller, these entities being wired as discrete components, x/y arrays, or woven in a diagonally intersecting pattern to form diagonal arrays.

The method uses the tri-state logic capabilities of microcontrollers in order to gain efficiency over traditional multiplexing, each I/O pin being capable, when required, of rapidly changing between the three states, logical 1, logical 0, and high impedance.

This enables these I/O entities (LEDs, switches etc.) to be connected between any two microcontroller I/Os - e.g. with 4 I/Os, each I/O can pair with 3 other I/Os, resulting in 6 unique pairings (1/2, 1/3, 1/4, 2/3, 2/4, 3/4). Only 4 pairings are possible with standard x/y multiplexing (1/3, 1/4, 2/3, 2/4). Also, due to the microcontroller's ability to reverse the polarity of the 6 I/O pairs, the number of LEDS (or diodes) that are uniquely addressable, can be doubled to 12 - adding LEDS 2/1, 3/1, 4/1, 3/2, 4/2 and 4/3.

Although it is more efficient in its use of I/O, a small amount of address manipulation is required when trying to fit Charlieplexing into a standard x/y array.

Other issues that affect standard multiplexing but are exacerbated by Charlieplexing are:

  • consideration of current requirements and the forward voltages of the LEDs.
  • a requirement to cycle through the in-use LEDs rapidly so that the persistence of the human eye perceives the display to be lit as a whole. Multiplexing can generally be seen by a strobing effect and skewing if the eye's focal point is moved past the display rapidly.

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πŸ”— Ferrite Bead

πŸ”— Technology πŸ”— Electronics πŸ”— Electrical engineering

A ferrite bead (also known as a ferrite block, ferrite core, ferrite ring, EMI filter, or ferrite choke) is a type of choke that suppresses high-frequency electronic noise in electronic circuits.

Ferrite beads employ high-frequency current dissipation in a ferrite ceramic to build high-frequency noise suppression devices.

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πŸ”— Trancitor

πŸ”— Electronics πŸ”— Electrical engineering

The trancitor as the combined word of a "transfer-capacitor" is to be considered as another active-device category besides the transistor as a "transfer-resistor". As observed in the table shown, four kinds of active devices are theoretically deduced. Among them, trancitors are missing to be the third and fourth kinds, whereas transistors, such as bipolar junction transistor (BJT) and field-effect transistor (FET), were already invented as the first and second kinds, respectively. Unlike the transistor switching the current at its output (i.e., current source), the trancitor transfers its input to the voltage output (i.e., voltage source), so an inverse relationship with each other.

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πŸ”— Wikipedia: Cost of Electricity by Source

πŸ”— Climate change πŸ”— Economics πŸ”— Electrical engineering

Different methods of electricity generation can incur significantly different costs, and these costs can occur at significantly different times relative to when the power is used. The costs include the initial capital, and the costs of continuous operation, fuel, and maintenance as well as the costs of de-commissioning and remediating any environmental damage. Calculations of these costs can be made at the point of connection to a load or to the electricity grid, so that they may or may not include the transmission costs.

For comparing different methods, it is useful to compare costs per unit of energy which is typically given per kilowatt-hour or megawatt-hour. This type of calculation assists policymakers, researchers and others to guide discussions and decision making but is usually complicated by the need to take account of differences in timing by means of a discount rate. The consensus of recent major global studies of generation costs is that wind and solar power are the lowest-cost sources of electricity available today.

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πŸ”— Photon Sieve

πŸ”— Physics πŸ”— Telecommunications πŸ”— Astronomy πŸ”— Electrical engineering πŸ”— Glass

A photon sieve is a device for focusing light using diffraction and interference. It consists of a flat sheet of material full of pinholes that are arranged in a pattern which is similar to the rings in a Fresnel zone plate, but a sieve brings light to much sharper focus than a zone plate. The sieve concept, first developed in 2001, is versatile because the characteristics of the focusing behaviour can be altered to suit the application by manufacturing a sieve containing holes of several different sizes and different arrangement of the pattern of holes.

Photon sieves have applications to photolithography. and are an alternative to lenses or mirrors in telescopes and terahertz lenses and antennas.

When the size of sieves is smaller than one wavelength of operating light, the traditional method mentioned above to describe the diffraction patterns is not valid. The vectorial theory must be used to approximate the diffraction of light from nanosieves. In this theory, the combination of coupled-mode theory and multiple expansion method is used to give an analytical model, which can facilitate the demonstration of traditional devices such as lenses and holograms.

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