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Foundation of Electromagnetic Theory
Published in Bahman Zohuri, Patrick J. McDaniel, Electrical Brain Stimulation for the Treatment of Neurological Disorders, 2019
Bahman Zohuri, Patrick J. McDaniel
In the study of the fundamental science of physics, several kinds of quantities are, encountered; in particular, we need to distinguish vectors and scalars. For our purposes, it is sufficient to define a scalar as follows: Scalar: A scalar is a quantity that is completely characterized by its magnitude. Examples of scalars are mass, volume, etc. A simple extension of the idea of a scalar is a scalar field—a function of position that is completely specified by its magnitude at all points in space.Vector: A vector is a quantity that is completely characterized by its magnitude and direction. Examples of vectors are that we consider position from a fixed origin, velocity, acceleration, force, etc. The generalization to a vector field gives a function of position that is completely specified by its magnitude and direction at all points in space.
Magnetic properties of materials
Published in David Jiles, Introduction to the Electronic Properties of Materials, 2017
The band theory of ferromagnetism is a simple extension of Pauli’s band theory of paramagnetism to ferromagnets with the inclusion of an exchange interaction (internal effective magnetic field) to align the electrons in a cooperative manner in the absence of an external applied field. This causes a relative displacement of the spin-up and spin-down half-bands known as the exchange splitting. It is qualitatively similar to that encountered under the action of an applied magnetic field in Pauli paramagnetism, except that here the shift in energy is much larger and occurs in the absence of an applied magnetic field. The net spontaneous magnetization of a material is again determined by the difference in occupancy between the spin-up and spin-down states.
Remote optical sensing by laser
Published in John P. Dakin, Robert G. W. Brown, Handbook of Optoelectronics, 2017
Such a system provides a single line-of-sight wind-velocity component. However, simple extension of such equipment enables one to determine the wind field anywhere around the measuring station. The laser beam may be scanned in order to resolve various components of the wind and several different scan patterns have been developed to suit particular measurement tasks. One of the simplest is to use a conical scan about a vertical axis. In this case, if the half-angle of the cone is φ (i.e., the angle of the lidar beam from vertical) and θsc is the beam direction in the horizontal plane, the measured line-of-sight wind component VM is given by VM=VHcos(θM–θsc) sinΦ+VVcosφ
The Ten Differences Between Programs and Projects, and the Problems They Cause
Published in Engineering Management Journal, 2022
Julien Pollack, Ekaterina Anichenko
The same cannot yet be said for program management. Programs are still defined through reference to projects. For example, although Martinsuo and Hoverfält (2018) assert that over the last 25 years research has moved from viewing programs as a simple extension of projects to a rich field of research, they nonetheless devote a section of their paper to explaining the differences between programs and projects, as do other recent publications (e.g., Shao, 2018; Steinfort, 2017; Vuorinen & Martinsuo, 2018). When authors identify similarities between projects and programs, it is typically to argue for further clarification of the differences between them (e.g., Artto et al., 2009; Pellegrinelli, 2011). Programs are defined by their differences to projects, not their similarities. This is a deliberate act of category differentiation.
Extended MARTINI water model for heat transfer studies
Published in Molecular Physics, 2020
A simple extension of the original MARTINI model is developed by changing sigma and epsilon of LJ potential and adding a viscous force term to the force field. This has enabled to simulate surface tension, enthalpy of vaporisation and density related to water at temperatures near . The use of overly simplistic LJ potential limits the ability to match a larger number of parameters, say for example diffusion coefficient. This can be improvised using potential functions with more variables like Tersoff [42] or Brenner [43] potential, however, with an expense in computational cost. Though the current study doesn't focus on dielectric properties, dipole moments, radial distribution function [44], etc., it may be beneficial to match them for a more accurate version of the CGMD model.
A VSEPR-inspired force field for determining molecular properties of PF5
Published in Molecular Physics, 2019
Laura M. McCaslin, John F. Stanton
Clearly the ability to calculate molecular force fields has grown substantially since the early work by Bartell and his group on the POS model, and very high accuracy force constants can now be calculated quite efficiently for any of the compounds or molecular ‘types’ mentioned above. While models similar to the POS approach continue to see some use [17–19], this venerable mechanical model may now seem quaint. However, it is undeniable that the model worked better than one might have expected given its naivete, and the present authors wondered how an – again simple – extension of the POS model that includes effects of bond stretching would perform for the description of a full (bending and stretching) force field for an AX-type molecule.