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Topic Review
AI Mk. VIII Radar
Radar, Airborne Interception, Mark VIII, or AI Mk. VIII for short, was the first operational microwave-frequency air-to-air radar. It was used by Royal Air Force night fighters from late 1941 until the end of World War II. The basic concept, using a moving parabolic antenna to search for targets and track them accurately, remained in use by most airborne radars well into the 1980s. Low-level development began in 1939 but was greatly sped after the introduction of the cavity magnetron in early 1940. This operated at 9.1 cm wavelength (3 GHz), much shorter than the 1.5 m wavelength of the earlier AI Mk. IV. Shorter wavelengths allowed it to use smaller and much more directional antennas. Mk. IV was blinded by the reflections off the ground from its wide broadcast pattern, which made it impossible to see targets flying at low altitudes. Mk. VIII could avoid this by keeping the antenna pointed upward, allowing it to see any aircraft at or above the horizon. The design was just beginning to mature in late 1941 when the Luftwaffe began low-level attacks. A prototype version, the Mk. VII, entered service on the Bristol Beaufighter in November 1941. A small number of these were sent to units across the UK to provide coverage at low altitudes while Mk. IV equipped aircraft operated at higher altitudes. After a small run of the improved Mk. VIIIA, the definitive Mk. VIII arrived in early 1942, offering higher power as well as a host of electronic and packaging upgrades. It arrived just as production rates of the De Havilland Mosquito began to improve, quickly displacing the Beaufighter units in RAF squadrons. Mk. VIII equipped Mosquitoes would be the premier night fighter from 1943 through the rest of the war. The Mk. VIII spawned a number of variants, notably the AI Mk. IX which included a lock-on feature to ease interceptions. A series of events, including a deadly friendly fire incident, so greatly delayed the Mk. IX that it never entered service. During the late-war period, many UK aircraft adopted the US SCR-720 under the name AI Mk. X. This worked on the same general principles as the Mk. VIII, but used a different display system that offered several advantages. Development of the basic system continued, and the Mk. IX would eventually briefly re-appear in greatly advanced form as the AI.17 during the 1950s.
  • 1.2K
  • 16 Nov 2022
Topic Review
CeO2-based transition metal catalysts
The rational design and fabrication of highly-active and cost-efficient catalytic materials constitutes the main research pillar in catalysis field. In this context, the fine-tuning of size and shape at nanometer scale can exert an intense impact not only on the inherent reactivity of catalyst’s counterparts but also on their interfacial interactions, opening up new horizons for the development of highly active and robust materials. The main implications of ceria nanoparticles’ shape engineering (rods, cubes, polyhedra) in catalysis are revealed, on the ground of some of the most pertinent heterogeneous reactions, such as CO2 hydrogenation, CO oxidation, and N2O decomposition. It is clearly revealed that shape functionalization can remarkably affect the intrinsic features and in turn the reactivity of ceria nanoparticles. More importantly, by combining ceria nanoparticles (CeO2 NPs) of specific architecture with various transition metals (e.g., Cu, Fe, Co, Ni) remarkably active multifunctional composites can be obtained due mainly to the synergistic metal-ceria interactions, providing the design principles of earth-abundant metal oxide catalysts for various real-life environmental and energy applications.
  • 1.2K
  • 22 Apr 2021
Topic Review
Industry 4.0 Manufacturing Systems
Manufacturing systems are generally “physical” systems in a physical world. The internet is a cyber-world. The internet has allowed for global connectedness. At the same time, infused with this connectedness, is a “dark web.” The dark web constitutes malware, viruses, “ransomware-as-a-service,” and other divisive instruments. Industry 4.0 brings together in the form of “cyber-physical” systems a new range of opportunities for additive manufacturing. While the opportunity of connectedness maps, at the same time, the challenges of the “dark web” also maps into this world of manufacturing. On a growing basis, measures to improve cybersecurity continue to develop. These measures include the lever of machine and deep learning. In this entry, the authors use engineering control systems and other relevant theories, including augmented artificial intelligence, as a way of making more secure cyber-physical systems and thereby making practical the considerations for Industry 4.0.
  • 1.2K
  • 14 Apr 2021
Topic Review
Cellulose Triacetate Hollow-Fiber Membranes
Cellulose triacetate (CTA)-based hollow fiber (HF) membrane is one of the commercially successful semipermeable membranes that has had a long progress since the time the excellent semi-permeable feature of cellulose-based polymers was found in 1957. Because of the reliable and excellent performances, especially for drinking water production from seawater, CTA-HFs have been widely used as reverse osmosis (RO) membranes, especially in arid regions. 
  • 1.2K
  • 29 Mar 2021
Topic Review
Temperature Sensors for Thermoregulation in Personal Protective Equipment
The exposure to extreme temperatures in workplaces involves physical hazards for workers. A poorly acclimated worker may have lower performance and vigilance and therefore may be more exposed to accidents and injuries. Due to the incompatibility of the existing standards implemented in some workplaces and the lack of thermoregulation in many types of protective equipment, thermal stress remains one of the most frequent physical hazards in many work sectors. In order to provide a better protection of individuals against thermal aggressors, the scientific community has been interested in the development of the textile-based or flexible temperature sensors that can be integrated into personal protective equipment. These sensors can measure the skin temperature and monitor the microclimate temperature between the body and the clothing or the outside temperature during exposure to thermal aggressors. 
  • 1.2K
  • 29 Jan 2022
Topic Review
Atrial Fibrillation Arrhythmia Detection Methods
Atrial fibrillation (AF) is still a major cause of disease morbidity and mortality, making its early diagnosis desirable and urging researchers to develop efficient methods devoted to automatic AF detection. Till now, the analysis of electrocardiography (Holter-ECG) recordings remains the gold-standard technique to screen AF. This is usually achieved by studying either RR interval time series analysis, P-wave detection or combinations of both morphological characteristics. After extraction and selection of meaningful features, each of the AF detection methods might be conducted through univariate and multivariate data analysis. Many of these automatic techniques have been proposed over the last years. 
  • 1.2K
  • 12 Jul 2022
Topic Review
Structural Health Monitoring Systems
Structural health monitoring (SHM) is a rapidly evolving field, and there is a vast literature covering several topics that are related to this field. This entry is focused on the analysis of the state of the art of sensors for guided ultrasonic waves for the detection and localization of impacts for structural health monitoring (SHM).
  • 1.2K
  • 06 May 2021
Topic Review
Functional and Cellular Layouts of Product Variants
Due to market competition, manufacturers typically produce their products with different customized features, leading to the production of product variants (or a product family). Since the market trend can change swiftly, the demands of individual product variants can be difficult to predict. Two flexible manufacturing layouts are commonly considered: functional and cellular layouts. While the functional layout is more resilient to demand changes due to better resource pooling, the cellular layout can be more productive on some occasions due to better routing efficiency.
  • 1.2K
  • 14 Nov 2023
Topic Review
Cuff-Less Blood Pressure Monitoring Technology
Initial calibration is a great challenge for cuff-less blood pressure (BP) measurement. The traditional one point-to-point (oPTP) calibration procedure had a strong sensitivity in the selection of initial value because of only using one sample/point to obtain unknown parameters of specific model in a calm state. In this study, a mean point-to-point (mPTP) paring calibration method through averaging and balancing calm or peaceful state was proposed for the first time. Thus, based on mPTP, a factor point-to-point (fPTP) paring calibration method through introducing the penalty factor was further proposed to improve and optimize the performance of BP estimation.
  • 1.2K
  • 29 Oct 2020
Topic Review
Zellige
Zellige (Arabic: [zˈliʑ]; Arabic: الزليج; also zelige or zellij) is mosaic tilework made from individually chiseled geometric tiles set into a plaster base. This form of Islamic art is one of the main characteristics of Moroccan architecture. It consists of geometrically patterned mosaics, used to ornament walls, ceilings, fountains, floors, pools and tables.
  • 1.2K
  • 06 Oct 2022
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