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Topic Review
Drilling Fluids for Extended-Reach Wells
In the planning phase of extended-reach well (ERW), special attention should be paid to the choice of drilling fluid. Selected drilling fluids for extended-reach wells should satisfy the same basic functions that are common to all drilling fluids, and they have to provide excellent reservoir protection. When drilling extended-reach wells, the following critical factors should be considered: hole cleaning, torque and drag, borehole stability, equivalent circulating density (ECD) and lost circulation. So far, oil-based mud (OBM) and water-based mud (WBM) have also been used in practice, but the emphasis is on the application of environmentally friendly additives.
  • 1.4K
  • 06 Apr 2023
Topic Review
Loss-of-Coolant Accident
A loss-of-coolant accident (LOCA) is a mode of failure for a nuclear reactor; if not managed effectively, the results of a LOCA could result in reactor core damage. Each nuclear plant's emergency core cooling system (ECCS) exists specifically to deal with a LOCA. Nuclear reactors generate heat internally; to remove this heat and convert it into useful electrical power, a coolant system is used. If this coolant flow is reduced, or lost altogether, the nuclear reactor's emergency shutdown system is designed to stop the fission chain reaction. However, due to radioactive decay, the nuclear fuel will continue to generate a significant amount of heat. The decay heat produced by a reactor shutdown from full power is initially equivalent to about 5 to 6% of the thermal rating of the reactor. If all of the independent cooling trains of the ECCS fail to operate as designed, this heat can increase the fuel temperature to the point of damaging the reactor. Under operating conditions, a reactor may passively (that is, in the absence of any control systems) increase or decrease its power output in the event of a LOCA or of voids appearing in its coolant system (by water boiling, for example). This is measured by the coolant void coefficient. Most modern nuclear power plants have a negative void coefficient, indicating that as water turns to steam, power instantly decreases. Two exceptions are the Soviet RBMK and the Canadian CANDU. Boiling water reactors, on the other hand, are designed to have steam voids inside the reactor vessel. Modern reactors are designed to prevent and withstand loss of coolant, regardless of their void coefficient, using various techniques. Some, such as the pebble bed reactor, passively slow down the chain reaction when coolant is lost; others have extensive safety systems to rapidly shut down the chain reaction, and may have extensive passive safety systems (such as a large thermal heat sink around the reactor core, passively-activated backup cooling/condensing systems, or a passively cooled containment structure) that mitigate the risk of further damage.
  • 1.4K
  • 09 Oct 2022
Topic Review
Coracle
A coracle is a small, rounded, lightweight boat of the sort traditionally used in Wales, and also in parts of the West Country and in Ireland, particularly the River Boyne, and in Scotland, particularly the River Spey. The word is also used of similar boats found in India , Vietnam, Iraq and Tibet. The word "coracle" is an English spelling of the original Welsh cwrwgl, cognate with Irish and Scottish Gaelic currach, and is recorded in English text as early as the sixteenth century. Other historical English spellings include corougle, corracle, curricle and coricle.
  • 1.3K
  • 05 Nov 2022
Topic Review
List of Intel Celeron Microprocessors
The Celeron is a family of microprocessors from Intel targeted at the low-end consumer market. CPUs in the Celeron brand have used designs from sixth- to eighth-generation CPU microarchitectures.
  • 1.3K
  • 06 Dec 2022
Topic Review
Fault Tolerance Structures in Wireless Sensor Networks (WSNs)
The Industrial Revolution 4.0 (IR 4.0) has drastically impacted how the world operates. The Internet of Things (IoT), encompassed significantly by the Wireless Sensor Networks (WSNs), is an important subsection component of the IR 4.0. WSNs are a good demonstration of an ambient intelligence vision, in which the environment becomes intelligent and aware of its surroundings. WSN has unique features which create its own distinct network attributes and is deployed widely for critical real-time applications that require stringent prerequisites when dealing with faults to ensure the avoidance and tolerance management of catastrophic outcomes. Thus, the respective underlying Fault Tolerance (FT) structure is a critical requirement that needs to be considered when designing any algorithm in WSNs. Moreover, with the exponential evolution of IoT systems, substantial enhancements of current FT mechanisms will ensure that the system constantly provides high network reliability and integrity. 
  • 1.4K
  • 26 Aug 2022
Topic Review
Duplex Steels
Welded structures made of duplex steels are used in building applications due to their resistance to local corrosion attack initiated by chlorides. In this entry, the material and technological factors determining the corrosion resistance of such steels are discussed in detail. 
  • 1.4K
  • 28 Mar 2022
Topic Review
Optical Accelerometers
Optical accelerometers are high-precision inertial sensors that use optical measurement technology to achieve high-precision and electromagnetic interference-resistant acceleration measurements. With the intensive research and development of optical accelerometers in recent years, their applications in inertial navigation, structural health monitoring, precision vibration isolation systems, wind turbine fault monitoring, earthquake monitoring, and other low-frequency vibration detection have flourished. Optical accelerometers have various schemes; however, their characteristics vary considerably due to different optical modulation schemes. This study aims to address the lack of systematic evaluation of currently available low-frequency optical accelerometers. Optical accelerometers can be classified into four categories in accordance with their optical modulation schemes: optical path-, optical intensity-, optical phase-, and optical wave-length-modulated accelerometers. 
  • 1.4K
  • 16 Jun 2022
Topic Review
Failure Modes of the Electric Motors
The reliability assessment of electric machines plays a very critical role in today’s engineering world. The reliability assessment requires a good understanding of electric motors and their root causes. Electric machines mostly fail due to mechanical problems and bearing damage is the main source of this. The bearings can be damaged by mechanical, electrical, and thermal stresses. Among all stresses, the researcher should give special attention to the electrical one, which is bearing current and shaft voltage.
  • 1.4K
  • 21 Jun 2023
Topic Review
Solid Waste Management
Disposal of municipal solid waste (MSW) is one of the significant global issues that is more evident in developing nations. One of the key methods for disposing of the MSW is locating, assessing, and planning for landfill sites.  Due to rapidly expanding global urbanization, associated lack of resources, and inadequate urban waste management, MSW issues and management concerns are on the rise. Over a third of total municipal waste out of two billion tons generated remains uncollected worldwide. MSW is collected and disposed of at certain locations or burnt down in most developing nations. Landfill sites for solid waste must be inspected in terms of all requirements to reduce economic and environmental expenses.
  • 1.4K
  • 17 Jun 2022
Topic Review
Indefinite Lifespan
Indefinite lifespan (also known as indefinite life extension or bio-indefinite) is a term used in the life extension movement and transhumanism to refer to the hypothetical longevity of humans (and other life-forms) under conditions in which ageing is effectively and completely prevented and treated. Their lifespans would be "indefinite" (that is, they would not be "immortal"), because protection from the effects of aging on health does not guarantee survival. Such individuals would still be susceptible to death by disease, starvation, accidents, or deliberate killing, but not death from aging. Semantically, "indefinite lifespan" is more accurate than "immortality" which, especially in religious contexts, implies an inability to die.
  • 1.3K
  • 26 Oct 2022
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