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Topic Review
Application of Analog-to-Digital Converter in Ultrasonic Imaging System
The ADC, a bridge between the analog world and the digital world, converts the analog signals to digital so that the analog signal in the baseband can be processed by the back-end computer or microprocessor.
  • 3.0K
  • 17 Jan 2022
Topic Review
Crash Boats of World War 2
Crash boats, at the time known as "aircraft rescue boat" or "air-sea rescue boat" were wooden speedboats built to rescue the crew of downed United States and other Allies aircraft during World War II. US boats came from observation of British experience with High-speed launches during the Battle of Britain. By the end of World War II America had produced 300,000 planes, creating a need to have crash rescue boats stationed around the globe. These boats were fast boats used to rescue pilots, crew and passengers from downed aircraft in search and rescue, air-sea rescue missions. The boats would race out to a crash site and rescue wounded aircrew. Some speed boats built before the war were acquired and converted to be crash boats and many new boats were built. Standard crash boats were built in four lengths for World War II. The smallest standard size boat was 42 feet long. The larger boats were 63 or 85 or 104 feet long. They were built for the Army Air Forces, US Navy and some were transferred to Allies. The design was similar to patrol boats built for the war, but with less or no armament and first aid equipped. The boats were designed to be light and fast to be able to get to the downed aircrew as fast as possible. Most were used in the Pacific war across the vast South Pacific, in the Island hopping campaign. Some were station on the West Coast of the United States to support the vast training centers. Many were designated Air Rescue Boats or ARB or AVR or P or C or R Hull classification symbol. After the war most were abandoned or destroyed, a few served in the Korean war (with United States Air Force ), some sold to private and some donated to Sea Scouts.
  • 3.0K
  • 23 Nov 2022
Topic Review
Solar Reflectance Measurement
The relative amount of solar radiation reflected by a surface is specified as solar reflectance, or albedo. The latter term sometimes refers only to visible sunlight (Vis), while the former generally refers to the entire spectrum of solar radiation, including near-infrared (NIR) and ultraviolet (UV) radiation. However, the scientific and technical communities consider albedo and solar reflectance synonymous, with both referring to the entire solar spectrum. Solar reflectance is usually expressed as a value between zero, for a surface absorbing all incoming radiation, and one, for a perfect reflector—or as a percentage between 0 and 100%. For an opaque surface, solar reflectance is complementary to solar absorptance—that is, the ratio of absorbed to total incident solar energy. Several instruments are available for its measurement, in the laboratory on in situ, according to several standard test methods.
  • 3.0K
  • 23 Nov 2021
Topic Review
Cylinder Block
The cylinder block is an integrated structure comprising the cylinder(s) of a reciprocating engine and often some or all of their associated surrounding structures (coolant passages, intake and exhaust passages and ports, and crankcase). The term engine block is often used synonymously with "cylinder block" (although technically distinctions can be made between en bloc cylinders as a discrete unit versus engine block designs with yet more integration that comprise the crankcase as well). In the basic terms of machine elements, the various main parts of an engine (such as cylinder(s), cylinder head(s), coolant passages, intake and exhaust passages, and crankcase) are conceptually distinct, and these items can all be made as discrete pieces that are bolted together. Such construction was very widespread in the early decades of the commercialization of internal combustion engines (1880s to 1920s), and it is still sometimes used in certain applications where it remains advantageous (especially very large engines, but also some small engines). However, it is no longer the normal way of building most petrol engines and diesel engines, because for any given engine configuration, there are more efficient ways of designing for manufacture (and also for maintenance and repair). These generally involve integrating multiple machine elements into one discrete part, and doing the making (such as casting, stamping, and machining) for multiple elements in one setup with one machine coordinate system (of a machine tool or other piece of manufacturing machinery). This yields lower unit cost of production (and/or maintenance and repair). Today most engines for cars, trucks, buses, tractors, and so on are built with fairly highly integrated design, so the words "monobloc" and "en bloc" are seldom used in describing them; such construction is often implicit. Thus "engine block", "cylinder block", or simply "block" are the terms likely to be heard in the garage or on the street.
  • 3.0K
  • 28 Sep 2022
Topic Review
Satellite Sandwich Structures
Sandwich panels are widely used in the design of unmanned satellites and, in addition to having a structural function, can often serve as shielding, protecting the satellites’ equipment from hypervelocity impacts (HVI) of orbital debris and micrometeoroids.
  • 3.0K
  • 12 May 2021
Topic Review
Reclaimed Water
Reclaimed or recycled water (also called wastewater reuse or water reclamation) is the process of converting wastewater into water that can be reused for other purposes. Reuse may include irrigation of gardens and agricultural fields or replenishing surface water and groundwater (i.e., groundwater recharge). Reused water may also be directed toward fulfilling certain needs in residences (e.g. toilet flushing), businesses, and industry, and could even be treated to reach drinking water standards. This last option is called either "direct potable reuse" or "indirect potable" reuse, depending on the approach used. Reclaiming water for reuse applications instead of using freshwater supplies can be a water-saving measure. When used water is eventually discharged back into natural water sources, it can still have benefits to ecosystems, improving streamflow, nourishing plant life and recharging aquifers, as part of the natural water cycle. Wastewater reuse is a long-established practice used for irrigation, especially in arid countries. Reusing wastewater as part of sustainable water management allows water to remain as an alternative water source for human activities. This can reduce scarcity and alleviate pressures on groundwater and other natural water bodies.
  • 3.0K
  • 24 Oct 2022
Topic Review Peer Reviewed
High-Speed Railway
Union Internationale des Chemins (UIC) defines the high-speed railway (HSR) as a high-speed railway system that contains the infrastructure and the rolling stock. The infrastructure can be newly built dedicated lines enabled for trains to travel with speed above 250 km/h or upgraded conventional lines with a speed up to 200 or even 220 km/h. HSR requires specially built trains with increased power to weight ratio and must have an in-cab signalling system as traditional signalling systems are incapable of above 200 km/h.
  • 2.9K
  • 18 Apr 2022
Topic Review
Lattice Materials
Lattice material is a cellular material consisting of a periodic network of structural elements such as rods or beams. This network of lattices exists over a wide spectrum of scale from the nanoscale to macroscale and has been applied in a wide area of applications. In the nanoscale spectrum, most of the CNT (Carbon Nano Tube) based sensors are made using lattice materials. Micro-lattices material is being developed intensively as it offers high energy absorption capability. On a macroscale, due to its high stiffness and lightweight properties, lattice materials are widely used in aerospace applications.
  • 3.0K
  • 28 Mar 2022
Topic Review
Flocculation Harvesting Techniques for Microalgae
Microalgae have been considered as one of the most promising biomass feedstocks for various industrial applications such as biofuels, animal/aquaculture feeds, food supplements, nutraceuticals, and pharmaceuticals. Several biotechnological challenges associated with algae cultivation, including the small size and negative surface charge of algal cells as well as the dilution of its cultures, need to be circumvented, which increases the cost and labor. Therefore, efficient biomass recovery or harvesting of diverse algal species represents a critical bottleneck for large-scale algal biorefinery process. Among different algae harvesting techniques (e.g., centrifugation, gravity sedimentation, screening, filtration, and air flotation), the flocculation-based processes have acquired much attention due to their promising efficiency and scalability. 
  • 3.0K
  • 13 Sep 2020
Topic Review
Solid Waste Management in Middle East Arab Countries
Solid waste production, specifically construction waste, in Middle Eastern Arab countries has dramatically increased. This is characterized by several factors, including rapid urbanization, common food wasting habits, diverse culture, lack of proper planning of solid waste processes, insufficient equipment, as well as lack of proper funding. The exponential growth in solid waste generation rates has led to hazards to health and the environment, causing issues related to air and water pollution under the already increasing pressure of climate change.
  • 2.9K
  • 17 Nov 2022
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