Subject:
All Disciplines Arts & Humanities Biology & Life Sciences Business & Economics Chemistry & Materials Science Computer Science & Mathematics Engineering Environmental & Earth Sciences Medicine & Pharmacology Physical Sciences Public Health & Healthcare Social Sciences
Sort:
Hottest Latest Alphabetical (A-Z) Alphabetical (Z-A)
Type:
All Topic Review Biography
Topic Review
Constituent State
A constituent state is a state entity that constitutes a part of a sovereign state. A constituent state holds regional jurisdiction over a defined administrative territory, within a sovereign state. Government of a constituent state is a form of regional government. Throughout history, and also in modern political practice, most constituent states are part of complex states, like federations or confederations. Constituent states can have republican or monarchical forms of government. Those of republican form are usually called states or autonomous states, republics or autonomous republics, or cantons. Those that have a monarchical form of government are often defined by traditional hierarchical rank of their ruler (usually a principality, or an emirate).
  • 3.4K
  • 31 Oct 2022
Topic Review Peer Reviewed
Entropy
The concept of entropy constitutes, together with energy, a cornerstone of contemporary physics and related areas. It was originally introduced by Clausius in 1865 along abstract lines focusing on thermodynamical irreversibility of macroscopic physical processes. In the next decade, Boltzmann made the genius connection—further developed by Gibbs—of the entropy with the microscopic world, which led to the formulation of a new and impressively successful physical theory, thereafter named statistical mechanics. The extension to quantum mechanical systems was formalized by von Neumann in 1927, and the connections with the theory of communications and, more widely, with the theory of information were respectively introduced by Shannon in 1948 and Jaynes in 1957. Since then, over fifty new entropic functionals emerged in the scientific and technological literature. The most popular among them are the additive Renyi one introduced in 1961, and the nonadditive one introduced in 1988 as a basis for the generalization of the Boltzmann–Gibbs and related equilibrium and nonequilibrium theories, focusing on natural, artificial and social complex systems. Along such lines, theoretical, experimental, observational and computational efforts, and their connections to nonlinear dynamical systems and the theory of probabilities, are currently under progress. Illustrative applications, in physics and elsewhere, of these recent developments are briefly described in the present synopsis.
  • 3.4K
  • 07 May 2022
Topic Review
Manufacturing Processes for Ceramic Matrix Composites
Materials such as ceramic matrix composites (CMCs) have been the focus of research and being tested in different conditions for several decades now. They are known as a subgroup of composite materials and ceramics. Ceramic composites were developed to control and address problems that occurred with other commonly used ceramics, such as silicon carbide, alumina, silicon nitride, aluminum nitride, and zirconia. Such ceramics fractured with ease, revealing scratches and cracks while mechanical and thermo-mechanical loads were applied to them. CMCs exhibit mechanical and thermal properties comparable with, and in some cases, even better than, the conventional superalloys used in aero-engines. However, their adoption relies on other variables as well, such as the cost of development, industrialization, manufacturing, and the availability of manufacturing technologies and systems.
  • 3.4K
  • 27 Apr 2023
Topic Review
Physical Body
In physics, a physical body or physical object (or simply a body or object) is an identifiable collection of matter, which may be constrained by an identifiable boundary, and may move as a unit by translation or rotation, in 3-dimensional space. In common usage, an object is a collection of matter within a defined contiguous boundary in 3-dimensional space. The boundary must be defined and identified by the properties of the material. The boundary may change over time. The boundary is usually the visible or tangible surface of the object. The matter in the object is constrained (to a greater or lesser degree) to move as one object. The boundary may move in space relative to other objects that it is not attached to (through translation and rotation). An object's boundary may also deform and change over time in other ways. Also in common usage, an object is not constrained to consist of the same collection of matter. Atoms or parts of an object may change over time. An object is defined by the simplest representation of the boundary consistent with the observations. However the laws of Physics only apply directly to objects that consist of the same collection of matter. Each object has a unique identity, independent of any other properties. Two objects may be identical, in all properties except position, but still remain distinguishable. In most cases the boundaries of two objects may not overlap at any point in time. The property of identity allows objects to be counted. Examples of models of physical bodies include, but are not limited to a particle, several interacting smaller bodies (particles or other), and continuous media. The common conception of physical objects includes that they have extension in the physical world, although there do exist theories of quantum physics and cosmology which may challenge this. In modern physics, "extension" is understood in terms of the spacetime: roughly speaking, it means that for a given moment of time the body has some location in the space, although not necessarily a point. A physical body as a whole is assumed to have such quantitative properties as mass, momentum, electric charge, other conserving quantities, and possibly other quantities. A body with known composition and described in an adequate physical theory is an example of physical system.
  • 3.4K
  • 12 Dec 2022
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.
  • 3.4K
  • 29 Oct 2020
Topic Review
Communication
Communication (from Latin communicare, meaning "to share"or "to be in relation with") is "an apparent answer to the painful divisions between self and other, private and public, and inner thought and outer word." As this definition indicates, communication is difficult to define in a consistent manner, because it is commonly used to refer to a wide range of different behaviors (broadly: "the transfer of information"), or to limit what can be included in the category of communication (for example, requiring a "conscious intent" to persuade). John Peters argues the difficulty of defining communication emerges from the fact that communication is both a universal phenomena (because everyone communicates), and a specific discipline of institutional academic study. One possible definition of communication is the act of developing meaning among entities or groups through the use of sufficiently mutually understood signs, symbols, and semiotic conventions. In Claude Shannon's and Warren Weaver's influential model, human communication was imagined to function like a telephone or telegraph. Accordingly, they conceptualized communication as involving discrete steps: These elements are now understood to be substantially overlapping and recursive activities rather than steps in a sequence. For example, communicative actions can commence before a communicator formulates a conscious attempt to do so, as in the case of phatics; likewise, communicators modify their intentions and formulations of a message in response to real-time feedback (e.g., a change in facial expression). Practices of decoding and interpretation are culturally enacted, not just by individuals (genre conventions, for instance, trigger anticipatory expectations for how a message is to be received), and receivers of any message operationalize their own frames of reference in interpretation. The scientific study of communication can be divided into: The channel of communication can be visual, auditory, tactile/haptic (e.g. Braille or other physical means), olfactory, electromagnetic, or biochemical. Human communication is unique for its extensive use of abstract language. Development of civilization has been closely linked with progress in telecommunication.
  • 3.4K
  • 02 Nov 2022
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. 
  • 3.4K
  • 20 Oct 2022
Topic Review
Methods for Determination of Lipophilicity
Lipophilicity is one of many parameters involved in the biological activity of drugs, as it affects their pharmacokinetic and pharmacodynamic behavior. Generally, lipophilicity is assessed by the partition coefficient of a compound between a nonpolar phase (n-octanol) and an aqueous phase (water), expressed as P (partition coefficient) or as its decimal logarithm (Log P). The gold standard method for the experimental determination of Log P is the shake-flask method.
  • 3.4K
  • 25 Aug 2022
Topic Review
Visual Appearance of Oil
The visual appearance of oil spills at sea is often used as an indicator of spilled oil properties, state and slick thickness. These appearances and the oil properties that are associated with them are reviewed in this entry. The appearance of oil spills is an estimator of thickness of thin oil slicks, thinner than a rainbow sheen (<3 µm). Rainbow sheens have a strong physical explanation. Thicker oil slicks (e.g., >3 µm) are not correlated with a given oil appearance. At one time, the appearance of surface discharges from ships was thought to be correlated with discharge rate and vessel speed; however, this approach is now known to be incorrect. Oil on the sea can sometimes form water-in-oil emulsions, dependent on the properties of the oil, and these are often reddish in color. These can be detected visually, providing useful information on the state of the oil. Oil-in-water emulsions can be seen as a coffee-colored cloud below the water surface. Other information gleaned from the oil appearance includes coverage and distribution on the surface.
  • 3.4K
  • 27 Jan 2021
Topic Review
The Link between Ethics and Organizational Performance
Ethics in corporate governance, HR management ethics, and ethics in sales and marketing have a notably positive effect on business ethics, leading to a substantial and affirmative impact on organizational performance.
  • 3.4K
  • 30 Jun 2023
  • Page
  • of
  • 5358
Featured Entry Collections
>>

Featured Books

>>
Encyclopedia of Social Sciences
Encyclopedia of COVID-19
Encyclopedia of Fungi
Encyclopedia of Digital Society, Industry 5.0 and Smart City
ScholarVision Creations
Feedback