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Topic Review
Shingled Magnetic Recording
Shingled magnetic recording (SMR) is a magnetic storage data recording technology used in hard disk drives (HDDs) to increase storage density and overall per-drive storage capacity. Conventional hard disk drives record data by writing non-overlapping magnetic tracks parallel to each other (perpendicular magnetic recording, PMR), while shingled recording writes new tracks that overlap part of the previously written magnetic track, leaving the previous track narrower and allowing for higher track density. Thus, the tracks partially overlap similar to roof shingles. This approach was selected because, if the writing head is made too narrow, it cannot provide the very high fields required in the recording layer of the disk.:7–9 The overlapping-tracks architecture complicates the writing process since writing to one track also overwrites an adjacent track. If adjacent tracks contain valid data, they must be rewritten as well. As a result, SMR drives are divided into many append-only (sequential) zones of overlapping tracks that need to be rewritten entirely when full, resembling flash blocks in solid state drives. Device-managed SMR devices hide this complexity by managing it in the firmware, presenting an interface like any other hard disk. Other SMR devices are host-managed and depend on the operating system to know how to handle the drive, and only write sequentially to certain regions of the drive. :11 ff. While SMR drives can use DRAM and flash memory caches to improve writing performance, continuous writing of large amount of data is noticeably slower than with PMR drives.
  • 1.9K
  • 01 Dec 2022
Topic Review
Herring–Nabarro Creep
Nabarro–Herring creep is a mode of deformation of crystalline materials (and amorphous materials) that occurs at low stresses and held at elevated temperatures in fine-grained materials. In Nabarro–Herring creep (NH creep), atoms diffuse through the crystals, and the creep rate varies inversely with the square of the grain size so fine-grained materials creep faster than coarser-grained ones. NH creep is solely controlled by diffusional mass transport. This type of creep results from the diffusion of vacancies from regions of high chemical potential at grain boundaries subjected to normal tensile stresses to regions of lower chemical potential where the average tensile stresses across the grain boundaries are zero. Self-diffusion within the grains of a polycrystalline solid can cause the solid to yield to an applied shearing stress, the yielding being caused by a diffusional flow of matter within each crystal grain away from boundaries where there is a normal pressure and toward those where there is a normal tension. Atoms migrating in the opposite direction account for the creep strain ([math]\displaystyle{ \epsilon_{NH} }[/math]). The creep strain rate is derived in the next section. NH creep is more important in ceramics than metals as dislocation motion is more difficult to effect in ceramics.
  • 1.9K
  • 08 Nov 2022
Topic Review
In-Situ Heavy Oil Aquathermolysis
The aquathermolysis process is widely considered to be one of the most promising approaches of in-situ upgrading of heavy oil. 
  • 1.9K
  • 28 Apr 2021
Biography
Clemens Herschel
Clemens Herschel (March 23, 1842 – March 1, 1930) was an American hydraulic engineer. His career extended from about 1860 to 1930, and he is best known for developing the Venturi meter, which was the first large-scale, accurate device for measuring water flow.[1][2] Clemens was born in Vienna in 1842. His family immigrated to Davenport, Iowa in 1850. He spent most of his life practicing his
  • 1.9K
  • 24 Nov 2022
Topic Review
List of Intel Pentium M Microprocessors
The Pentium M brand refers to single-core 32-bit mobile CPUs codenamed Banias and Dothan, and targeted at the consumer market of mobile computers.
  • 1.9K
  • 19 Oct 2022
Topic Review
Nosler Proprietary Cartridges
Nosler produces various high performance hollow point and soft point hunting bullets.
  • 1.9K
  • 02 Nov 2022
Topic Review
Transparent Wood Composites
Transparent wood composites are novel wood materials which have up to 90% transparency and some higher mechanical properties than wood itself, made for the first time in 1992. When these materials are made commercially available, a significant benefit is expected due to their inherent biodegradable properties; however, this has the axiomatic disadvantage of being problematic for long-term construction. These materials are significantly more biodegradable than glass and plastics. Transparent wood is also shatterproof. On the other hand, concerns may be relevant due to the use of non-biodegradable plastics for long-lasting purposes such as in buildings. File:Example of Transparent Wood and Light diffusion.webm
  • 1.9K
  • 11 Nov 2022
Topic Review
Ultrasonic Vibration-Assisted Ball-Burnishing Process
Burnishing processes are effective methods to increase the durability and surface texture of industrial parts, through plastic deformation of its micropeaks. Traditional burnishing can be strongly improved with the assistance of external energy sources. One of these sources is vibration assistance, which can be delivered into the systems through different means. In overall, vibration-assistance ball burnishing consists on overlapping to the static burnishing preload an oscillatory force that favours the acoustoplastic effect in the material, that is, an increase in dislocation mobility that facilitates plastic deformation, while eventually delivering residual hardening on the target surface.
  • 1.9K
  • 11 Jun 2021
Topic Review
Pipe Fitting
Pipe fitting or pipefitting is the occupation of installing or repairing piping or tubing systems that convey liquid, gas, and occasionally solid materials. This work involves selecting and preparing pipe or tubing, joining it together by various means, and the location and repair of leaks. Pipe fitting work is done in many different settings: HVAC, manufacturing, hydraulics, refineries, nuclear-powered supercarriers and fast-attack submarines, computer chip fabrication plants, power plant construction, and other steam systems. Pipe fitters (sometimes called simply "fitters") are represented in the US and Canada by the United Association of Journeymen and Apprentices of the Plumbing and Pipe Fitting Industry of the United States and Canada. Pipefitters work with a variety of pipe and tubing materials including several types of steel, copper, iron, aluminium, and plastic. Pipe fitting is not plumbing; the two are related but separate trades. Pipe fitters who specialize in fire prevention are called Sprinklerfitters, another related, but separate trade. Materials, techniques, and usages vary from country to country as different nations have different standards to install pipe.
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  • 24 Oct 2022
Topic Review
Rikhter R-23
The Rikhter R-23 is an aircraft autocannon developed for the Soviet Air Force starting in the late 1950s. It was designed to be as short as possible to avoid problems found on high-speed aircraft when the guns were pointed into the airstream. The R-23 was a gas operated revolver cannon that used gas bled from holes in the barrel to provide the motive force. Firing up to 2,600 rpm, the R-23 was the fastest firing single-barrel cannon ever introduced into service. The R-23 took some time to develop, and was not used operationally until 1964. It was used only in the tail turret of the Tu-22, and experimentally on the Salyut 3 space station. Its role was taken over by the twin-barrel Gryazev-Shipunov GSh-23. A modified version of the weapon was the only cannon to have been fired in space.
  • 1.9K
  • 08 Nov 2022
Topic Review
Sintering
Sintering or frittage is the process of compacting and forming a solid mass of material by heat or pressure without melting it to the point of liquefaction. Sintering happens naturally in mineral deposits or as part of a manufacturing process used with metals, ceramics, plastics, and other materials. The atoms in the materials diffuse across the boundaries of the particles, fusing the particles together and creating one solid piece. Because the sintering temperature does not have to reach the melting point of the material, sintering is often chosen as the shaping process for materials with extremely high melting points such as tungsten and molybdenum. The study of sintering in metallurgy powder-related processes is known as powder metallurgy. An example of sintering can be observed when ice cubes in a glass of water adhere to each other, which is driven by the temperature difference between the water and the ice. Examples of pressure-driven sintering are the compacting of snowfall to a glacier, or the forming of a hard snowball by pressing loose snow together. The word "sinter" comes from the Middle High German sinter, a cognate of English "cinder".
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  • 04 Nov 2022
Biography
Susan Kilrain
Susan Kilrain (born October 24, 1961) is an engineer, a former United States Navy officer, and a former NASA astronaut. Kilrain was born in Augusta, Georgia, as Susan Leigh Still to Dr. Joseph Still, M.D. and his wife, Jean Ann Batho; she has nine siblings. Her father was a prominent burn surgeon who founded and directed the Joseph M. Still Burn Center in Augusta, Georgia. Kilrain graduated f
  • 1.9K
  • 02 Dec 2022
Topic Review
Steam Reforming of Glycerol
In the last decades, environmental crises and increasing energy demand have motivated researchers to investigate the practical techniques for the production of clean fuels through renewable energy resources. It is essential to develop technologies to utilize glycerol as a byproduct derived from biodiesel. Glycerol is known as a sustainable and clean source of energy, which can be an alternative resource for the production of value-added chemicals and hydrogen. The hydrogen production via steam reforming (SR) of glycerol using Ni-based catalysts is one of the promising approaches for the entry of the hydrogen economy. The purpose of this review paper is to highlight the recent trends in hydrogen production over Ni-based catalysts using the SR of glycerol. The intrinsic ability of Ni to disperse easily over variable supports makes it a more viable active phase for the SR catalysts. The optimal reaction conditions have been indicated as 650–900 °C, 1 bar, and 15 wt% Ni in catalysts for high glycerol conversion. In this review paper, the effects of various supports, different promoters (K, Ca, Sr, Ce, La, Cr, Fe), and process conditions on the catalytic performance have been summarized and discussed to provide a better comparison for the future works. It was found that Ce, Mg, and La have a significant effect on catalytic performance as promoters. Moreover, SR of glycerol over hydrotalcite and perovskite-based catalysts have been reviewed as they suggest high catalytic performance in SR of glycerol with improved thermal stability and coke resistance. More specifically, the Ni/LaNi0.9Cu0.1O3 synthesized using perovskite-type supports has shown high glycerol conversion and sufficient hydrogen selectivity at low temperatures. On the other hand, hydrotalcite-like catalysts have shown higher catalytic stability due to high thermal stability and low coke formation. It is vital to notice that the primary concern is developing a high-performance catalyst to utilize crude glycerol efficiently.
  • 1.9K
  • 27 Oct 2020
Topic Review
Archaeoacoustics Around the World
Acoustics has been integrated with archaeology to better understand the social and cultural context of past cultures. Specifically, public events such as rituals or ceremonies, where an appreciation of sound propagation was required to hold an event. Various acoustic techniques have been used to study archaeological sites, providing information about the building characteristics and organizational structures of ancient civilizations. Archaeoacoustics is the application of acoustics in archaeological spaces.
  • 1.9K
  • 06 May 2023
Topic Review
Ionic Liquids in DSSCs
The dye-sensitized solar cells (DSSCs) which are considered as the third-generation solar cells have a huge potential to be commercialized due to their low cost, simplicity in fabrication, and promising photon-to-electrical energy conversion efficiency. Nevertheless, a high cell efficiency can only be achieved when an organic solvent is incorporated into the formulation of the electrolyte, which is prone to evaporation and leakage. As a result, DSSCs become unsuitable for long-run usage due to thermal instability in the electrolyte. The early intention of incorporating ionic liquids (ILs) into the electrolyte was to curb the abovementioned problem and to enable the DSSCs to function as a sustainable energy device. ILs have been incorporated into the electrolyte formulation and the extent of how the ILs can affect the cell efficiency in various electrolyte states is highlighted. This sheds light on the true purpose of introducing ILs into DSSC electrolyte, which is to enhance the ionicity of the electrolyte.
  • 1.9K
  • 26 Sep 2020
Topic Review
HP Series 80
The Hewlett-Packard series 80 of small scientific desktop computers was introduced in 1980, beginning with the popular HP-85 targeted at engineering and control applications. They provided the capability of the HP 9800 series desktop computers with an integrated monitor in a smaller package including storage and printer, at half the price.
  • 1.9K
  • 30 Nov 2022
Topic Review
Osa (Handgun)
The ПБ-4 «ОСА» (EN:PB-4 Osa, Russian for "wasp"), is a family of Russian non-lethal pistols that can be also used as flare gun, flashbang gun, or starting pistol. The system consists of the pistol (2-4 cartridges, laser target pointer, electronic ignition capsule), and various ammunition types. Osa was developed in the 1990s by engineer-constructor and weapon designer G.A. Bideev (Г.А. Бидеев). It was designed and is manufactured by the state-owned organizations Federal Center for Research and Manufacturing and The Institute for Science and Research in the Applied Chemistry. The pistol is available in the civilian market.
  • 1.9K
  • 14 Nov 2022
Topic Review
Manned Orbiting Laboratory
The Manned Orbiting Laboratory (MOL), originally referred to as the Manned Orbital Laboratory, was a never-flown part of the United States Air Force 's human spaceflight program, a successor to the canceled Boeing X-20 Dyna-Soar military reconnaissance space plane project. The project was developed from several early Air Force and NASA concepts of crewed space stations to be used for reconnaissance purposes. MOL evolved into a single-use laboratory, with which crews would be launched on 40-day missions and return to Earth using a Gemini B spacecraft, derived from NASA's Project Gemini. The MOL program was announced to the public on 10 December 1963 as an inhabited platform to prove the utility of putting people in space for military missions. Astronauts selected for the program were later told of the reconnaissance mission for the program. The contractor for the MOL was the Douglas Aircraft Company. The Gemini B was externally similar to NASA's Gemini spacecraft, although it underwent several modifications, including the addition of a circular hatch through the heat shield, which allowed passage between the spacecraft and the laboratory. MOL was canceled in 1969, during the height of the Apollo program, when it was shown that uncrewed reconnaissance satellites could achieve the same objectives much more cost-effectively. U.S. space station development was instead pursued with the civilian NASA Skylab (Apollo Applications Program) which flew in the mid-1970s. In the 1970s, the Soviet Union launched three Almaz military space stations, similar in intent to the MOL, but cancelled the program in 1977 for the same reasons. There is a MOL space suit on display at the Oklahoma City Science Museum, presumably never used.
  • 1.9K
  • 11 Oct 2022
Topic Review Peer Reviewed
Electronic Textiles
Electronic textiles belong to the broader range of smart (or “intelligent”) textiles. Their “smartness” is enabled by embedded or added electronics and allows the sensing of defined parameters of their environment as well as actuating according to these sensor data. For this purpose, different sensors (e.g., temperature, strain, light sensors) and actuators (e.g., LEDs or mechanical actuators) are embedded and connected with a power supply, a data processor, and internal/external communication. 
  • 1.9K
  • 13 Apr 2022
Topic Review
Unitized Regenerative Fuel Cells History
In Remote Area Power Supply (RAPS) systems that utilize solar and hydrogen power, which typically include photovoltaic modules, a proton exchange membrane (PEM) electrolyzer, hydrogen gas storage, and proton exchange membrane (PEM) fuel cells, the cost of these systems is currently higher compared to conventional RAPS systems that employ diesel generators or batteries. Unitized regenerative fuel cells (URFCs) offer a potential solution to reduce the expenses of solar hydrogen renewable energy systems in RAPS by combining the functionalities of the electrolyzer and fuel cell into a single unit, thereby eliminating the need to purchase separate and costly electrolyzer and fuel cell units. URFCs are particularly well-suited for RAPS applications because the electrolyzer and fuel cell do not need to operate simultaneously. In electrolyzer mode, URFCs function similarly to stand-alone electrolyzers. However, in fuel cell mode, the performance of URFCs is inferior to that of stand-alone fuel cells.
  • 1.9K
  • 10 Aug 2023
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