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Topic Review
Power Grid
One of the most critical infrastructures in the world is electrical power grids (EPGs). New threats affecting EPGs, and their different consequences, are analyzed in this survey along with different approaches that can be taken to prevent or minimize those consequences, thus improving EPG resilience. The necessity for electrical power systems to become resilient to such events is becoming compelling; indeed, it is important to understand the origins and consequences of faults. This survey provides an analysis of different types of faults and their respective causes, showing which ones are more reported in the literature. As a result of the analysis performed, it was possible to identify four clusters concerning mitigation approaches, as well as to correlate them with the four different states of the electrical power system resilience curve.
  • 3.2K
  • 23 Oct 2020
Topic Review
Solar PV-Hydrogen-PEM Fuel Cell System
The results obtained from the design and analysis of a photovoltaic-hydrogen-PEM fuel cell (PVHPEMFC) hybrid system for Najaf City in Iraq has been presented. The hybrid system consists of photovoltaic arrays coupled with an electrolyzer to produce hydrogen, a PEM fuel cell that converts chemical energy (H2) to electricity, hydrogen storage, a battery storage system, and the load. In this kind of system, all components can be connected electrically in parallel. The voltage of the PV arrays and fuel cell must be high enough to charge the battery, and the voltage of the electrolyzer must be low enough for the battery to power it during periods of low insolation. The designed system model is based on the electrical component models and variable solar radiation data depending on the location.
  • 3.2K
  • 29 Oct 2020
Topic Review
Seismometer
A seismometer is an instrument that responds to ground motions, such as caused by earthquakes, volcanic eruptions, and explosions. Seismometers are usually combined with a timing device and a recording device to form a seismograph. The output of such a device—formerly recorded on paper (see picture) or film, now recorded and processed digitally—is a seismogram. Such data is used to locate and characterize earthquakes, and to study the Earth's internal structure.
  • 3.2K
  • 01 Dec 2022
Topic Review
Sami Drum
A Sami drum is a shamanic ceremonial drum in the culture of the Sami people of Northern Europe. Sami ceremonial drums have two types: a bowl drum in which the drumhead is strapped over a burl, and a frame drum in which the drumhead stretches over a thin ring of bentwood. Both variations are oval-shaped. The drumhead is fashioned from reindeer hide. In Sami shamanism, the noaidi – the Sami shaman – used the drum to get into a trance, or to obtain information from the future or about other places. The drum was held in one hand, and operated with the other hand. While the noaidi was in trance, his free spirit left his body to visit the spiritual world or other places. When used for divination purposes, the drum was used together with a drum hammer and an vuorbi (index or pointer) made of brass or horn. Answers could be interpreted from where the vuorbi stopped on the membrane, and at which symbols. The patterns on the drum membrane reflect the world view of the owner and his family, both in religious and worldly matters, such as reindeer herding, hunting, householding and relations to their neighbours and to the non-Sami community. Many drums were taken out of their use and Sami ownership during the 18th century. A large number of drums were confiscated by Sami missionaries and other officials as a part of an intensified Christian mission towards the Sami. Other drums were bought by collectors. Between 70 and 80 drums are preserved; the largest collection of drums is at the Nordic Museum, Stockholm.
  • 3.2K
  • 27 Oct 2022
Topic Review
Anti Urination Devices in Norwich
Anti urination devices were a form of hostile architecture installed in Norwich and the surrounding area in the late 19th century to discourage public urination. The overcrowded and narrow streets of the city centre and a lack of public toilets led to men urinating against the side of buildings, but the installation of new public urinals to address the issue was delayed by disputes over where they were to be sited. Anti urination devices were built in places which suffered particular problems with public urination, and were intended to discourage men from urinating at that spot. Most were built of sloped or curved stone, flint or concrete, and were shaped such that anyone attempting to urinate against the wall would need to stand well away from the wall in public view, hopefully discouraging them from doing so. The slope of the structure meant that should anyone still attempt to urinate against it, the stream of urine would be deflected back onto their feet and legs. A few instead consisted of a spiked metal bar positioned across a corner at the height of a typical man's groin, and were intended to dissuade men from approaching the corner with their genitals exposed. Following improved public toilet provision from the 1890s onwards, the problems caused by the lack of urinals became less of an issue, and anti urination devices ceased to be installed. Although most metal examples were removed during the Second World War, and many others have been demolished in subsequent years, around 30 remain in place in central Norwich with further surviving examples in other parts of East Anglia.
  • 3.2K
  • 07 Oct 2022
Topic Review
Carbon-Based Quantum Dots for Supercapacitors
Carbon-based Quantum dots (C-QDs) are carbon-based materials that experience the quantum confinement effect, which results in superior optoelectronic properties. In recent years, C-QDs have attracted attention significantly and have shown great application potential as a high-performance supercapacitor device. C-QDs (either as a bare electrode or composite) give a new way to boost supercapacitor performances in higher specific capacitance, high energy density, and good durability. This review comprehensively summarizes the up-to-date progress in C-QD applications either in a bare condition or as a composite with other materials for supercapacitors. The current state of the three distinct C-QD families used for supercapacitors including carbon quantum dots, carbon dots, and graphene quantum dots is highlighted. 
  • 3.2K
  • 28 Sep 2021
Topic Review
Types of Aluminium Matrix Composites
Al alloy has very attractive properties required in the production of aerospace, automotive, electrical and electronic, sports and recreational components/equipment. Its low strength and low wear resistance have challenged its applications in some other critical industrial utilities. Nonetheless, the invention of metal composites has removed such barriers. The addition of one or more reinforcements to Al has helped in the creation of aluminium matrix composites (AMCs), which has not only increased the global utilization of Al alloy, but has been a major source of global revenue and job. 
  • 3.2K
  • 20 Oct 2022
Topic Review
Groundwater Withdrawal-Induced Land Subsidence
Land subsidence is probably one of the most evident environmental effects of groundwater pumping. Globally, freshwater demand is the leading cause of this phenomenon. Land subsidence induced by aquifer system drainage can reach total values of up to 14.5 m. The spatial extension of this phenomenon is usually extensive and is often difficult to define clearly. Aquifer compaction contributes to many socio-economic effects and high infrastructure-related damage costs. Currently, many methods are used to analyze aquifer compaction. These include the fundamental relationship between groundwater head and groundwater flow direction, water pressure and aquifer matrix compressibility. Such solutions enable satisfactory modelling results. However, further research is needed to allow more efficient modelling of aquifer compaction. Recently, satellite radar interferometry (InSAR) has contributed to significant progress in monitoring and determining the spatio-temporal land subsidence distributions worldwide. Therefore, implementation of this approach can pave the way to the development of more efficient aquifer compaction models. This entry presents a comprehensive review of models used to predict land surface displacements caused by rock mass drainage, as well as (2) recent advances and (3) a summary of InSAR implementation over recent years to support the aquifer compaction modelling process. Therefore, the study presented would be of benefit to readers who are interested in the topic of interaction between the human population and the hydrogeological system in different regions. The research presented allows readers to better understand the factors, developments and effects of groundwater drainage and thus facilitate large - scale risk assessment and preventive planning.
  • 3.1K
  • 27 Oct 2020
Topic Review
Kerb Construction
Concrete kerbs can be prepared by precast and cast in situ methods. The precast concrete kerbs can be manufactured by conventional (using a vibrator), dry-pressed and wet-pressed methods and can be installed in almost all weather conditions. Possible rainfall, temperatures and sunlight hours are considered in casting in situ kerbs, and they are more labour-intensive compared to the precast variations. However, cast in situ kerb can better handle sudden changes of direction. There is no study found comparing different aspects of in situ casting and precast kerb. Both types of concrete kerb are suggested for construction by all authorities, such as the Austroads and AASHTO. The precast kerbs require manual placement and have been a major source of workplace injury in the United Kingdom. Past studies have suggested that the use of special lifting equipment (such as vacuum lifters, lifting clamps or stone magnets), reduction in kerb section length, reduction in kerb foundation depth, use of a lightweight or hollow concrete section or other lightweight materials, such as polymer, can reduce the likelihood of such workplace injuries and may also lead to quicker construction as well as better construction quality.
  • 3.1K
  • 28 Mar 2022
Topic Review
CubeSat Missions and Their Antenna Designs
CubeSats are a class of miniaturized satellites that have become increasingly popular in academia and among hobbyists due to their short development time and low fabrication cost. Their compact size, lightweight characteristics, and ability to form a swarm enables them to communicate directly with one another to inspire new ideas on space exploration, space-based measurements, and implementation of the latest technology. CubeSat missions require specific antenna designs in order to achieve optimal performance and ensure mission success. Over the past, a plethora of antenna designs have been proposed and implemented on CubeSat missions. Several challenges arise when designing CubeSat antennas such as gain, polarization, frequency selection, pointing accuracy, coverage, and deployment mechanisms.
  • 3.1K
  • 18 Jul 2022
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