Search | Encyclopedia MDPI

You're using an outdated browser. Please upgrade to a modern browser for the best experience.

Subject:

Sort by:

Most Viewed Latest Alphabetical (A-Z) Alphabetical (Z-A)

Filter:

All Topic Review Biography Peer Reviewed Entry Video Entry

Topic Review

Negawatt power is a theoretical unit of power representing an amount of electrical power (measured in watts) saved. The energy saved is a direct result of energy conservation or increased energy efficiency. The term was coined by the chief scientist of the Rocky Mountain Institute and environmentalist Amory Lovins in 1985, within the article, "Saving Gigabucks with Negawatts," where he argued that utility customers don’t want kilowatt-hours of electricity; they want energy services such as hot showers, cold beer, lit rooms, and spinning shafts, which can come more cheaply if electricity is used more efficiently. Lovins felt an international behavioral change was necessary in order to decrease countries' dependence on excessive amounts of energy. The concept of a negawatt could influence a behavioral change in consumers by encouraging them to think about the energy that they spend. A negawatt market can be thought of as a secondary market, in which electricity is allocated from one consumer to another consumer within the energy market. In this market, negawatts could be treated as a commodity. Commodities have the ability to be traded across time and space, which would allow negawatts to be incorporated in the international trading system. Roughly 10% of all U.S. electrical generating capacity is in place to meet the last 1% of demand and there is where the immediate efficiency opportunity exists. On March 15, 2011, the Federal Energy Regulatory Commission (FERC), the agency that regulates the U.S. electrical grid, approved a rule establishing the approach to compensation for demand response resources intended to benefit customers and help improve the operation and competitiveness of organized wholesale energy markets. This means that negawatts produced by reducing electrical use can demand the same market prices as real megawatts of generated electricity. The incentives for a negawatt market include receiving money, reduction of national energy dependency, and the local electricity deregulation within certain nations or states. As for the cost incentive, those who produce negawatts or simply conserve energy can earn money by selling the saved energy. The negawatt market could help nations or states obtain a deregulated electricity system by creating another market to purchase electricity from. The negawatt market also has two main drawbacks. Currently, there is no way to precisely measure the amount of energy saved in negawatts, and electricity providers may not want customers to use less energy due to the loss of profit.

11.4K
22 Nov 2022

Topic Review

Technological Dualism

Technological dualism was proposed by Benjamin Higgins. He was the Ritchie Professor of Economics at the University of Melbourne in the late 1940s. His theory explains the causes of unemployment in the underdeveloped economies. Developing countries of today are often characterized by dualistic economies. One is the modern (or formal) sector while the other is the traditional (informal) sector. Their relation has been explained by Higgins in his theory explained below.

11.4K
23 Nov 2022

Topic Review

Stage theories are based on the idea that elements in systems move through a pattern of distinct stages over time and that these stages can be described based on their distinguishing characteristics. Specifically, stages in cognitive development have a constant order of succession, later stages integrate the achievements of earlier stages, and each is characterized by a particular type of structure of mental processes which is specific to it. The time of appearance may vary to a certain extent depending upon environmental conditions. "Stage theory" can also be applied beyond psychology to describe phenomena more generally where multiple phases lead to an outcome. The term "stage theory" can thus be applied to various scientific, sociological and business disciplines. In these contexts, stages may not be as rigidly defined, and it is possible for individuals within the multi-stage process to revert to earlier stages or skip some stages entirely.

11.4K
02 Nov 2022

Topic Review

Black ginseng is a processed ginseng which prepared by steaming and drying of white or red ginseng for several times (usually 9). This process resulting in extensive changes in types and amounts of several secondary metabolites. Thus, primary ginsenosides (the main active inredients in ginseng) were transformed into less polar derivatives by steaming. In addition, apparent changes happened to other secondary metabolites such as the increasing of phenolic compounds, reducing sugars and acidic polysaccharides as well as the decrease in concentrations of free amino acids and total polysaccharides. Furthermore, the presence of some Maillard reaction products like maltol was also engaged. These obvious chemical changes were associated with a noticeable superiority for black ginseng over white and red ginseng in most of the comparative biological studies including anticarcinogenic, immunomodulatory, anti-Inflammatory, antidiabetic, hepatoprotective, antioxidant and tonic effects.

11.3K
30 Oct 2020

Topic Review

Power Electronic Converters in Electric Vehicle Applications

In the electric vehicle (EV) powertrain, all the electric input sources are connected to a HV–DC bus by an individual DC–DC converter, and the output three-phase electric motor (EM), i.e., the main load of the EV, is powered from this HV–DC bus through a three-phase inverter which drives the EM. Here, the voltage level of this HV–DC bus of the EV is around 400–750 V. Moreover, moving the EV via an EM from electric batteries, a DC–DC voltage is required because the batteries’ output voltage is much lower than the required voltage of EM. A traction inverter is needed to drive the EM by converting the DC batteries into variable-frequency AC. However, a disagreement could be made for stepping up the output AC voltage level of the inverter by utilizing a high-voltage transformer instead of a DC–DC converter. This is due to its having several essential advantages, such as reliability, cost-effectiveness, compact size, and lightweight DC–DC converters appear to be excellent candidates for EVs and HEVs powertrains.

11.3K
10 Jan 2023

Topic Review

Gaming Computer

A gaming computer, also known as a gaming PC, is a specialized personal computer designed for playing video games. Gaming PCs typically differ from mainstream personal computers by using high-performance video cards and high core-count central processing units with raw performance. Gaming PCs are also used for other demanding tasks such as video editing. Many gamers and computer enthusiasts choose to overclock their CPU(s) and GPU(s) in order to gain extra performance. The added power draw needed to overclock either processing unit often requires additional cooling, using upgraded air cooling or water cooling.

11.3K
01 Nov 2022

Topic Review

Insulin Signaling

The insulin signaling pathway begins with the binding of the peptide hormone insulin to its corresponding receptor, the insulin receptor. The insulin receptor is a receptor tyrosine kinase (RTK) that conformationally consists of two alpha and two beta subunit tetramers. The insulin receptor exhibiting kinase activity is responsible for its autophosphorylation at the tyrosine residue site upon insulin binding.

11.3K
28 Sep 2021

Topic Review

Application of Standardized Regression Coefficient in Meta-Analysis

The β coefficient is the estimate resulting from an analysis carried out on variables that have been standardized so that their standard deviations (and variances) are equal to one. Therefore, the standardized coefficient refers to how many standard deviations the response or outcome variable will change per a standard deviation increase in the explanatory or predictor variable. Thus, the standardized coefficient β can be regarded as an attempt to make regression coefficients more comparable, and can be used as an effect-size estimate when the exposure levels in original studies are measured in different units of measurement.

11.3K
14 Sep 2022

Topic Review

Direct Amidations of Carboxylic Acids with Amines

The prevalence of amides in biological systems and chemical fields such as polymers, materials and natural products drives continuous research on novel procedures to obtain these ubiquitous functional groups. Efforts to this purpose are mainly focused around the discovery of direct and catalytic methods that are more atom economic, safe and practical for diversified applications (e.g., organic, medicinal and peptide chemistries, material and polymer purposes, etc.), in accordance with green chemistry principles.

11.3K
22 Feb 2023

Topic Review

A year is the orbital period of a planetary body, for example, the Earth, moving in its orbit around the Sun. Due to the Earth's axial tilt, the course of a year sees the passing of the seasons, marked by change in weather, the hours of daylight, and, consequently, vegetation and soil fertility. In temperate and subpolar regions around the planet, four seasons are generally recognized: spring, summer, autumn and winter. In tropical and subtropical regions, several geographical sectors do not present defined seasons; but in the seasonal tropics, the annual wet and dry seasons are recognized and tracked. A calendar year is an approximation of the number of days of the Earth's orbital period, as counted in a given calendar. The Gregorian calendar, or modern calendar, presents its calendar year to be either a common year of 365 days or a leap year of 366 days, as do the Julian calendars; see below. For the Gregorian calendar, the average length of the calendar year (the mean year) across the complete leap cycle of 400 years is 365.2425 days. The ISO standard ISO 80000-3, Annex C, supports the symbol a (for Latin annus) to represent a year of either 365 or 366 days. In English, the abbreviations y and yr are commonly used. In astronomy, the Julian year is a unit of time; it is defined as 365.25 days of exactly 86,400 seconds (SI base unit), totalling exactly 31,557,600 seconds in the Julian astronomical year. The word year is also used for periods loosely associated with, but not identical to, the calendar or astronomical year, such as the seasonal year, the fiscal year, the academic year, etc. Similarly, year can mean the orbital period of any planet; for example, a Martian year and a Venusian year are examples of the time a planet takes to transit one complete orbit. The term can also be used in reference to any long period or cycle, such as the Great Year.

11.3K
14 Nov 2022

Topic Review

German Student Movement

The German student movement (also called 68er-Bewegung, movement of 1968, or soixante-huitards) was a protest movement that took place during the late 1960s in West Germany. It was largely a reaction against the perceived authoritarianism and hypocrisy of the West German government and other Western governments, and the poor living conditions of students. A wave of protests—some violent—swept West Germany, fueled by violent over-reaction by the police and encouraged by contemporary protest movements across the world. Following more than a century of conservatism among German students, the German student movement also marked a significant major shift to the left and radicalization of student activism.

11.3K
03 Nov 2022

Topic Review

Clouding of Consciousness

Clouding of consciousness (also known as brain fog or mental fog) is when a person is slightly less wakeful or aware than normal. They are not as aware of time or their surroundings and find it difficult to pay attention. People describe this subjective sensation as their mind being "foggy".

11.2K
21 Nov 2022

Topic Review

In biology, a kingdom (Latin: regnum, plural regna) is the second highest taxonomic rank, just below domain. Kingdoms are divided into smaller groups called phyla. Traditionally, some textbooks from the United States and Canada used a system of six kingdoms (Animalia, Plantae, Fungi, Protista, Archaea/Archaebacteria, and Bacteria/Eubacteria) while textbooks in Great Britain, India, Greece, Brazil and other countries use five kingdoms only (Animalia, Plantae, Fungi, Protista and Monera). Some recent classifications based on modern cladistics have explicitly abandoned the term kingdom, noting that some traditional kingdoms are not monophyletic, meaning that they do not consist of all the descendants of a common ancestor. The terms flora (for plants), fauna (for animals), and, in the 21st century, funga (for fungi) are also used for life present in a particular region or time.

11.2K
27 Nov 2022

Topic Review

Lignosulfonates

Lignosulfonates are biobased surfactants and specialty chemicals, which are usually produced as a byproduct during sulfite pulping of wood. They are the technical lignin that is, by far, the most commercially traded and are hence vital for replacing non‑renewable and fossil‑based chemicals. Due to their prominent use as plasticizers, dispersants, and stabilizers, the physicochemical properties of lignosulfonates play a key role in determining their end‑use and performance. Their chemical composition and structure are inherently linked to the characteristic behavior of lignosulfonates. This entry hence outlines the fundamental chemistry of lignosulfonates, while discussing the following physicochemical properties: · Solubility in different solvents · Conformation and shape in aqueous solution · Self-association and agglomeration in aqueous solution · Precipitation · Adsorption at surfaces and interfaces

11.2K
05 Jan 2021

Topic Review

Triply Periodic Minimal Surfaces Thermal Hydraulic Effects

Triply Periodic Minimal Surfaces (TPMS) are a kind of periodic implicit surface with zero mean curvature, that is, the surfaces that locally minimize surface area for a given boundary. The TPMS is composed of infinite, non-self-intersecting, periodic surfaces in three principal directions. The TPMS networks as repeated lattice structures have attracted much research interest because they have shown better mechanical performance, mass transfer, and thermal conductivity than conventional and strut-based structures, which have been employed in different disciplines. With excellent performances in the TPMS architectures, current works have investigated the TPMS structures to utilize in a wide range of applications.

11.2K
29 Dec 2022

Topic Review

A frog is any member of a diverse and largely carnivorous group of short-bodied, tailless amphibians composing the order Anura (ανοὐρά, literally without tail in Ancient Greek). The oldest fossil "proto-frog" Triadobatrachus is known from the Early Triassic of Madagascar , but molecular clock dating suggests their split from other amphibians may extend further back to the Permian, 265 million years ago. Frogs are widely distributed, ranging from the tropics to subarctic regions, but the greatest concentration of species diversity is in tropical rainforest. Frogs account for around 88% of extant amphibian species. They are also one of the five most diverse vertebrate orders. Warty frog species tend to be called toads, but the distinction between frogs and toads is informal, not from taxonomy or evolutionary history. An adult frog has a stout body, protruding eyes, anteriorly-attached tongue, limbs folded underneath, and no tail (the tail of tailed frogs is an extension of the male cloaca). Frogs have glandular skin, with secretions ranging from distasteful to toxic. Their skin varies in colour from well-camouflaged dappled brown, grey and green to vivid patterns of bright red or yellow and black to show toxicity and ward off predators. Adult frogs live in fresh water and on dry land; some species are adapted for living underground or in trees. Frogs typically lay their eggs in water. The eggs hatch into aquatic larvae called tadpoles that have tails and internal gills. They have highly specialized rasping mouth parts suitable for herbivorous, omnivorous or planktivorous diets. The life cycle is completed when they metamorphose into adults. A few species deposit eggs on land or bypass the tadpole stage. Adult frogs generally have a carnivorous diet consisting of small invertebrates, but omnivorous species exist and a few feed on plant matter. Frog skin has a rich microbiome which is important to their health. Frogs are extremely efficient at converting what they eat into body mass. They are an important food source for predators and part of the food web dynamics of many of the world's ecosystems. The skin is semi-permeable, making them susceptible to dehydration, so they either live in moist places or have special adaptations to deal with dry habitats. Frogs produce a wide range of vocalizations, particularly in their breeding season, and exhibit many different kinds of complex behaviors to attract mates, to fend off predators and to generally survive. Frogs are valued as food by humans and also have many cultural roles in literature, symbolism and religion. They are also seen as environmental bellwethers, with declines in frog populations often viewed as early warning signs of environmental damage. Frog populations have declined significantly since the 1950s. More than one third of species are considered to be threatened with extinction and over 120 are believed to have become extinct since the 1980s. The number of malformations among frogs is on the rise and an emerging fungal disease, chytridiomycosis, has spread around the world. Conservation biologists are working to understand the causes of these problems and to resolve them.

11.2K
19 Oct 2022

Topic Review

News International Phone Hacking Scandal

The News International phone hacking scandal was a controversy involving the now-defunct News of the World and other British newspapers owned by Rupert Murdoch. Employees of the newspaper were accused of engaging in phone hacking, police bribery, and exercising improper influence in the pursuit of stories. Whilst investigations conducted from 2005 to 2007 appeared to show that the paper's phone hacking activities were limited to celebrities, politicians, and members of the British royal family, in July 2011 it was revealed that the phones of murdered schoolgirl Milly Dowler, relatives of deceased British soldiers, and victims of the 7 July 2005 London bombings had also been hacked. The resulting public outcry against News Corporation and its owner Rupert Murdoch led to several high-profile resignations, including that of Murdoch as News Corporation director, Murdoch's son James as executive chairman, Dow Jones chief executive Les Hinton, News International legal manager Tom Crone, and chief executive Rebekah Brooks. The commissioner of London's Metropolitan Police Service (MPS), Sir Paul Stephenson, also resigned. Advertiser boycotts led to the closure of the News of the World on 10 July 2011, after 168 years of publication. Public pressure forced News Corporation to cancel its proposed takeover of the British satellite broadcaster BSkyB. The prime minister David Cameron announced on 6 July 2011 that a public inquiry, known as the Leveson Inquiry, would look into phone hacking and police bribery by the News of the World, consider the wider culture and ethics of the British newspaper industry and that the Press Complaints Commission would be replaced "entirely". A number of arrests and convictions followed, most notably of the former News of the World managing editor Andy Coulson. Murdoch and his son, James, were summoned to give evidence at the Leveson Inquiry. Over the course of his testimony, Rupert Murdoch admitted that a cover-up had taken place within the News of the World to hide the scope of the phone hacking. On 1 May 2012, a parliamentary select committee report concluded that Murdoch "exhibited wilful blindness to what was going on in his companies and publications" and stated that he was "not a fit person to exercise the stewardship of a major international company". On 3 July 2013, Channel 4 News broadcast a secret tape in which Murdoch dismissively claims that investigators were "totally incompetent" and acted over "next to nothing" and excuses his papers' actions as "part of the culture of Fleet Street".

11.2K
11 Oct 2022

Topic Review

Library Catalog

A library catalog or library catalogue is a register of all bibliographic items found in a library or group of libraries, such as a network of libraries at several locations. A bibliographic item can be any information entity (e.g., books, computer files, graphics, realia, cartographic materials, etc.) that is considered library material (e.g., a single novel in an anthology), or a group of library materials (e.g., a trilogy), or linked from the catalog (e.g., a webpage) as far as it is relevant to the catalog and to the users (patrons) of the library. The card catalog was a familiar sight to library users for generations, but it has been effectively replaced by the online public access catalog (OPAC). Some still refer to the online catalog as a "card catalog". Some libraries with OPAC access still have card catalogs on site, but these are now strictly a secondary resource and are seldom updated. Many libraries that retain their physical card catalog will post a sign advising the last year that the card catalog was updated. Some libraries have eliminated their card catalog in favour of the OPAC for the purpose of saving space for other use, such as additional shelving. The largest library catalog in the world is the WorldCat.org union catalog managed by the non-profit library cooperative OCLC, based in Dublin, Ohio. In January 2016, WorldCat.org had over 360,000,000 catalog records and over 2 billion library holdings.

11.2K
21 Oct 2022

Topic Review

Sustainable Business Models

Over the years, researchers have presented different concepts regarding business models. There is no unanimity, but there is a general agreement that a business model is the representation of how a company conducts its business. Subsequently, interest in the topic has increased and has come to be considered by companies that, driven to incorporate a positive contribution to sustainability into their values, began to face economic development that considers social and environmental aspects instead of worrying only about profit for the shareholders.

11.2K
19 Apr 2022

Topic Review Peer Reviewed

Prefabricated Building Systems—Design and Construction

Modern Methods of Construction with Offsite Manufacturing is an advancement from prefabricated technologies that existed for decades in the construction industry, and is a platform to integrate various disciplines into providing a more holistic solution. Due to the rapid speed of construction, reduced requirement of labour and minimised work on site, offsite manufacturing and prefabricated building systems are becoming more popular, and perhaps a necessity for the future of the global construction industry. The approach to the design and construction of prefab building systems demands a thorough understanding of their unique characteristics.

11.2K
13 Apr 2022

Page
of
2713

Featured Entry Collections

>>

Featured Books

>>

Encyclopedia of COVID-19

Encyclopedia of Engineering

Encyclopedia of Social Sciences

Encyclopedia of Social Sciences
Chief Editor: Kum Fai Yuen

Encyclopedia of Digital Society, Industry 5.0 and Smart City

Encyclopedia of Digital Society, Industry 5.0 and Smart City
Chief Editor: Sandro Serpa

Academic Video Service

Feedback

Top