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Topic Review
Acrylic Bone Cements
Acrylic bone cements (ABC) are widely used in orthopedics for joint fixation, antibiotic release, and bone defect filling, among others. Most of the commercial ABCs available today consist of two components, one solid, based mainly on poly(methyl methacrylate) (PMMA), and one liquid, based on methyl methacrylate (MMA), which are mixed and, through the polymerization reaction of the monomer, transformed into a hardened cement paste. 
  • 2.4K
  • 22 Dec 2020
Topic Review
Centrifugal Fan
A centrifugal fan is a mechanical device for moving air or other gases in a direction at an angle to the incoming fluid. Centrifugal fans often contain a ducted housing to direct outgoing air in a specific direction or across a heat sink; such a fan is also called a blower, blower fan, biscuit blower, or squirrel-cage fan (because it looks like a hamster wheel). These fans increase the speed and volume of an air stream with the rotating impellers. Centrifugal fans use the kinetic energy of the impellers to increase the volume of the air stream, which in turn moves against the resistance caused by ducts, dampers and other components. Centrifugal fans displace air radially, changing the direction (typically by 90°) of the airflow. They are sturdy, quiet, reliable, and capable of operating over a wide range of conditions. Centrifugal fans are constant-displacement or constant-volume devices, meaning that, at a constant fan speed, a centrifugal fan moves a relatively constant volume of air rather than a constant mass. This means that the air velocity in a system is fixed even though the mass flow rate through the fan is not. Centrifugal fans are not positive-displacement devices and centrifugal fans have certain advantages and disadvantages when contrasted with positive-displacement blowers: centrifugal fans are more efficient, whereas positive-displacement blowers may have a lower capital cost. The centrifugal fan has a drum shape composed of a number of fan blades mounted around a hub. As shown in the animated figure, the hub turns on a driveshaft mounted in bearings in the fan housing. The gas enters from the side of the fan wheel, turns 90 degrees and accelerates due to centrifugal force as it flows over the fan blades and exits the fan housing.
  • 2.4K
  • 23 Oct 2022
Topic Review
Pot-in-pot Refrigerator
A pot-in-pot refrigerator, clay pot cooler or zeer (Arabic: زير) is an evaporative cooling refrigeration device which does not use electricity. It uses a porous outer earthenware pot (lined with wet sand) containing an inner pot (which can be glazed to prevent penetration by the liquid) within which the food is placed. The evaporation of the outer liquid draws heat from the inner pot. The device can cool any substance, and requires only a flow of relatively dry air and a source of water.
  • 2.4K
  • 09 Oct 2022
Topic Review
Pollution of Polyethylene Terephthalate Water Bottles
According to studies on global plastic manufacturing and the resulting pollution, plastic wastes have been identified as a serious environmental concern. The impact of plastic garbage on marine species, humans, and the environment is a source of public concern, necessitating the need to save ecosystems and the lives that depend on them. Polyethylene terephthalate (PET) water bottles have a significant carbon footprint and represent tremendous waste. In the United Arab Emirates (UAE), PET water bottles are widely utilized, with yearly consumption reaching 450 water bottles per person. 
  • 2.4K
  • 27 Apr 2022
Topic Review
Battery Equalizer Circuits
In this entry, several battery equalizer circuits are reviewed and simulated. In addition, a table is presented where the main characteristics of the equalizers are summarized. These characteristics are used to assign a score to each circuit with respect to how many characteristics are similar to the ideal equalizer. Finally, a methodology is presented to compare these equalizers, taking into account the results obtained from the table.
  • 2.4K
  • 25 Nov 2020
Topic Review
Battery Energy Storage and Management in Electric Vehicles
Electric vehicle (EV) technology has received massive attention worldwide due to its improved performance efficiency and significant contributions to addressing carbon emission problems. In line with that, EVs could play a vital role in achieving sustainable development goals (SDGs). EVs have a substantial influence on various goals of sustainable development, such as affordable and clean energy, sustainable cities and communities, industry, economic growth, and climate actions.
  • 2.4K
  • 08 Oct 2022
Topic Review Peer Reviewed
Geometric Design of Suburban Roundabouts
A modern roundabout is an intersection with a circulatory roadway at which the vehicle speed is low, and the traffic is continuous and circulating in one direction around the central island towards the exits at the approach legs. Modern roundabout design is an iterative process that is composed of the following steps: (1) the identification of the roundabout as the optimal traffic solution; (2) the definition of the number of lanes at the intersection based on the required capacity and the level of service; (3) the initial design of the roundabout geometry; (4) design vehicle swept path, the fastest path analysis, and visibility performance checks; and (5) detailed roundabout design if the results of the performance checks are in line with the design recommendations. Initial roundabout geometry design elements are not independent of each other; therefore, care must be taken to provide compatibility between them. An overview and a comparative analysis of the initial geometric design elements for suburban single-lane roundabouts defined in roundabout design guidelines and norms used in Croatia, Austria, France, the Netherlands, Germany, Serbia, and Switzerland is given in this entry.
  • 2.3K
  • 13 Apr 2022
Topic Review
E-Fuels
Power-to-X (PtX) are fuel production pathways in which electricity is converted into various gaseous or liquid fuels, such as e-hydrogen, e-methanol, e-methane, dimethyl ether (E-DME), e-ammonia, or e-diesel. These fuels are also named electrofuels (e-fuel) or power-to-liquid (PtL) and are mentioned in the Annexes of the RED II amendments as alternative options for the decarbonisation of the transport sector. Some of these molecules still contain carbon atoms, thus producing CO2 when used for energy production. The carbon source for the synthesis of e-fuels has to be carefully analysed to define them really carbon neutral.
  • 2.4K
  • 27 Feb 2023
Topic Review
Internet of Everything (IoE) Taxonomies
The paradigm of the Internet of everything (IoE) is advancing toward enriching people’s lives by adding value to the Internet of things (IoT), with connections among people, processes, data, and things. This paper provides a survey of the literature on IoE research, highlighting concerns in terms of intelligence services and knowledge creation. The significant contributions of this study are as follows: (1) a systematic literature review of IoE taxonomies (including IoT); (2) development of a taxonomy to guide the identification of critical knowledge in IoE applications, an in-depth classification of IoE enablers (sensors and actuators); (3) validation of the defined taxonomy with 50 IoE applications; and (4) identification of issues and challenges in existing IoE applications (using the defined taxonomy) with regard to insights about knowledge processes.
  • 2.4K
  • 27 Jan 2021
Topic Review
Neuromorphic Computing
Neuromorphic computing systems aims at processing information in a way similar to the human brain. Instead of a conventional von Neumann computer, a neuromorphic system generally relies on a neural network, where the memory and the processing elements are intimately co-located within the same hardware. Neuromorphic computing takes advantage of computational memories, which can both store and process data via physical laws within the device and/or the circuit. This entry summarizes the history and main concepts of neuromorphic computing, including both deep neural networks (DNNs) which are adopted for extensive artificial intelligence tasks, such as driverless cars, and spiking neural networks (SNNs), which aim at a more realistic brain-inspired computation. 
  • 2.4K
  • 22 Jan 2021
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