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Topic Review
Void Coefficient
In nuclear engineering, the void coefficient (more properly called void coefficient of reactivity) is a number that can be used to estimate how much the reactivity of a nuclear reactor changes as voids (typically steam bubbles) form in the reactor moderator or coolant. Net reactivity in a reactor is the sum total of all these contributions, of which the void coefficient is but one. Reactors in which either the moderator or the coolant is a liquid typically will have a void coefficient value that is either negative (if the reactor is under-moderated) or positive (if the reactor is over-moderated). Reactors in which neither the moderator nor the coolant is a liquid (e.g., a graphite-moderated, gas-cooled reactor) will have a void coefficient value equal to zero. It is unclear how the definition of 'void' coefficient applies to reactors in which the moderator/coolant is neither liquid nor gas (supercritical water reactor).
  • 2.5K
  • 22 Nov 2022
Topic Review
Degradation of Antibiotics
Antibiotics are the therapeutic option for countless infections treatment; unfortunately, they are the second most common group of drugs in wastewaters worldwide due to failures in industrial waste treatments and their irrational use in humans and animals. Several techniques have been assayed for the degradation and mineralisation of antibiotics to reduce the environmental impact; strategies focused on physical, chemical, biological, and combined process design for degradation.
  • 2.5K
  • 25 Jul 2022
Topic Review
Inertial Confinement Fusion
Inertial confinement fusion (ICF) is a type of fusion energy research that attempts to initiate nuclear fusion reactions by heating and compressing a fuel target, typically in the form of a pellet that most often contains a mixture of deuterium and tritium. Typical fuel pellets are about the size of a pinhead and contain around 10 milligrams of fuel. To compress and heat the fuel, energy is delivered to the outer layer of the target using high-energy beams of laser light, electrons or ions, although for a variety of reasons, almost all ICF devices (As of 2015) have used lasers. The heated outer layer explodes outward, producing a reaction force against the remainder of the target, accelerating it inwards, compressing the target. This process is designed to create shock waves that travel inward through the target. A sufficiently powerful set of shock waves can compress and heat the fuel at the center so much that fusion reactions occur. ICF is one of two major branches of fusion energy research, the other being magnetic confinement fusion. When it was first proposed in the early 1970s, ICF appeared to be a practical approach to power production and the field flourished. Experiments during the 1970s and '80s demonstrated that the efficiency of these devices was much lower than expected, and reaching ignition would not be easy. Throughout the 1980s and '90s, many experiments were conducted in order to understand the complex interaction of high-intensity laser light and plasma. These led to the design of newer machines, much larger, that would finally reach ignition energies. The largest operational ICF experiment is the National Ignition Facility (NIF) in the US, designed using the decades-long experience of earlier experiments. Like those earlier experiments, however, NIF has failed to reach ignition and is, as of 2015, generating about ​1⁄3 of the required energy levels.
  • 2.5K
  • 29 Sep 2022
Topic Review
Resistance of PVD Coatings
Due to the increasing maintenance costs of hydraulic machines related to the damages caused by cavitation erosion and/or erosion of solid particles, as well as in tribological connections, surface protection of these components is very important. Up to now, numerous investigations of resistance of coatings, mainly nitride coatings, such as CrN, TiN, TiCN, (Ti,Cr)N coatings and multilayer TiN/Ti, ZrN/CrN and TN/(Ti,Al)N coatings, produced by physical vapor deposition (PVD) method using different techniques of deposition, such as magnetron sputtering, arc evaporation or ion plating, to cavitation erosion, solid particle erosion and wear have been made. The results of these investigations, degradation processes and main test devices used are presented in this paper. An effect of deposition of mono- and multi-layer PVD coatings on duration of incubation period, cumulative weight loss and erosion rate, as well as on wear rate and coefficient of friction in tribological tests is discussed. It is shown that PVD coating does not always provide extended incubation time and/or improved resistance to mentioned types of damage. The influence of structure, hardness, residence to plastic deformation and stresses in the coatings on erosion and wear resistance is discussed. In the case of cavitation erosion and solid particle erosion, a limit value of the ratio of hardness (H) to Young’s modulus (E) exists at which the best resistance is gained. In the case of tribological tests, the higher the H/E ratio and the lower the coefficient of friction, the lower the wear rate, but there are also many exceptions
  • 2.5K
  • 13 Oct 2020
Topic Review
Factors Affecting Success of Entrepreneurship in Agribusinesses
Entrepreneurship and innovation are the fuel of economic growth. Understanding the motivational factors that lead to the success of entrepreneurs in agribusiness can be useful in affecting the degree of successful investment that accelerates development and economic growth in the agriculture sector. Entrepreneurship experience, risk-taking behavior, interest rates, and initial capital have a significant impact on the probability of entrepreneurship success and entrepreneur’s profits. Policies that could improve the skills of entrepreneurs, provision of initial capital requirements, and financial market efficiency had an effective role in increasing entrepreneurship and innovation in the agribusiness sector. Entrepreneurs in the field of agriculture could consider these factors to have better choices while entering or continuing with their agribusinesses.
  • 2.5K
  • 30 Jun 2022
Topic Review
Bone Structure, Its Properties, and Bone Healing Mechanism
Bones are categorized into two major groups, namely cortical bones, and cancellous bones. Cortical bones are compact bones and are responsible for providing mechanical strength, structural rigidity, and movement. They account for 80% of the mass of the bones in the human body. Cancellous bones, also known as trabecular bones, are soft, spongy bones and are responsible for providing structural support to the cortical bones, flexibility, and reduction in weight. 
  • 2.5K
  • 21 Apr 2022
Topic Review
Herbalism
Herbalism (also herbal medicine) is the study of botany and use of plants intended for medicinal purposes. Plants have been the basis for medical treatments through much of human history, and such traditional medicine is still widely practiced today. Modern medicine makes use of many plant-derived compounds as the basis for evidence-based pharmaceutical drugs. Although phytotherapy may apply modern standards of effectiveness testing to herbs and medicines derived from natural sources, few high-quality clinical trials and standards for purity or dosage exist. The scope of herbal medicine is sometimes extended to include fungal and bee products, as well as minerals, shells and certain animal parts. The term, phytomedicine, may also refer to the science of pathology and damage to plants, the causes thereof, their manifestations, development, dissemination, methods for maintaining plant health, and measures used to control plant diseases and their causes. Herbal medicine is sometimes also used to refer to paraherbalism or phytotherapy, which is the alternative and pseudoscientific practice of using of extracts of plant or animal origin as supposed medicines or health-promoting agents. Phytotherapy differs from plant-derived medicines in standard pharmacology because it does not isolate and standardize the compounds from a given plant believed to be biologically active. It relies on the false belief that preserving the complexity of substances from a given plant with less processing is safer and potentially more effective. There is no evidence that either condition applies. Herbal dietary supplements most often fall under this category.
  • 2.5K
  • 11 Oct 2022
Topic Review
Grazing
Grazing is a method of feeding in which a herbivore feeds on plants such as grasses, or other multicellular organisms such as algae. In agriculture, grazing is one method used whereby domestic livestock are used to convert grass and other forage into meat, milk and other products. Many small selective herbivores follow larger grazers, who skim off the highest, tough growth of plants, exposing tender shoots. For terrestrial animals, grazing is normally distinguished from browsing in that grazing is eating grass or forbs, and browsing is eating woody twigs and leaves from trees and shrubs. Grazing differs from true predation because the organism being grazed upon is not generally killed. Grazing differs from parasitism as the two organisms live together in a constant state of physical externality (i.e. low intimacy). Water animals that feed for example on algae found on stones are called grazers-scrapers. Grazers-scrapers feed also on microorganisms and dead organic matter on various substrates.
  • 2.5K
  • 16 Nov 2022
Topic Review
Cardiff
Cardiff (/ˈkɑːrdɪf/ (listen); Welsh: Caerdydd [kairˈdiːð, kɑːɨrˈdɨːð] (listen)) is the capital of Wales, and its largest city. The eleventh-largest city in the United Kingdom , it is Wales's chief commercial centre, the base for most national cultural institutions and Welsh media, and the seat of the National Assembly for Wales. The unitary authority area's 2017 population was estimated to be 362,756. Cardiff is a significant tourist centre and the most popular visitor destination in Wales with 21.3 million visitors in 2017. In 2011, Cardiff was ranked sixth in the world in National Geographic's alternative tourist destinations. Cardiff is the county town of the historic county of Glamorgan (and later South Glamorgan). Cardiff is part of the Eurocities network of the largest European cities. A small town until the early 19th century, its prominence as a major port for the transport of coal following the arrival of industry in the region contributed to its rise as a major city. The Cardiff Built-up Area covers a slightly larger area outside the county boundary and includes the towns of Dinas Powys and Penarth. In 1905, Cardiff was made a city and proclaimed the capital of Wales in 1955. Since the 1980s, Cardiff has seen significant development. A new waterfront area at Cardiff Bay contains the Senedd building, home to the Welsh Assembly and the Wales Millennium Centre arts complex. Current developments include the continuation of the redevelopment of the Cardiff Bay and city centre areas with projects such as the Cardiff International Sports Village, a BBC drama village, and a new business district in the city centre. Sporting venues in the city include the Principality Stadium—the national stadium and the home of the Wales national rugby union team—Sophia Gardens (the home of Glamorgan County Cricket Club), Cardiff City Stadium (the home of Cardiff City football team and the Wales football team), Cardiff International Sports Stadium (the home of Cardiff Amateur Athletic Club), Cardiff Arms Park (the home of Cardiff Blues and Cardiff RFC rugby union teams) and Ice Arena Wales (the home of Cardiff Devils ice hockey team). The city hosted the 1958 British Empire and Commonwealth Games. The city was awarded the title of European City of Sport twice, due to its role in hosting major international sporting events: first in 2009 and again in 2014. The Principality Stadium hosted 11 football matches as part of the 2012 Summer Olympics, including the games' opening event and the men's bronze medal match.
  • 2.5K
  • 18 Oct 2022
Topic Review
Power Quality Measurement
The use of power networks can induce harmonic pollution, disturbances, and power quality events within a power grid, leading to abnormal operating conditions of equipment and materials. It is, therefore, mandatory to characterize power quality disturbances in order to enhance the power system’s efficiency and reliability.
  • 2.5K
  • 19 Nov 2021
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