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Magnetic Properties
Published in Yip-Wah Chung, Monica Kapoor, Introduction to Materials Science and Engineering, 2022
Coercivity of magnetic materials depends not only on chemical composition but also on the microstructure. Imperfections such as dislocations, grain boundaries, and precipitates impede domain wall motion and thus increase coercivity. Another factor controlling coercivity is the shape of the magnetic material. Whenever something is magnetized, there is an internal demagnetizing field that aids domain reversal. By convention, the magnetic field points from the north pole to the south pole of the magnet. Therefore, inside the magnet, the north pole of each magnetic domain is being pushed towards the south pole of the magnet, thus acting to demagnetize the magnet. The strength of this demagnetizing field depends on the shape of the material. It is stronger for a thin-disk magnet and weaker for a long bar magnet.
Petroleum Geophysical Survey
Published in Muhammad Abdul Quddus, Petroleum Science and Technology, 2021
Magnetic induction is a process in which a magnetic material is magnetized through an externally applied magnetic field. Induction is a magnetism acquired by the material. An external applied field (H) introduces magnetic properties in magnetic permeable material, say an iron bar. Iron itself does not have a magnetic field, because the atoms are randomly arranged. In an external field, the atoms of the bar align themselves in a north–south direction, producing magnetic dipoles. The bar acquires an induced magnetism till a ‘saturation’ point is reached. The magnetized material produces its own induced magnetic field and the material as a whole behaves like a dipole magnet. The induced magnetic field (H*) is directly proportional to the applied magnetic field strength (H).
Field Applications
Published in Ahmad Shahid Khan, Saurabh Kumar Mukerji, Electromagnetic Fields, 2020
Ahmad Shahid Khan, Saurabh Kumar Mukerji
In the modern era, electricity has now become the backbone of the global economy. The generation, transportation, conversion, and many other aspects of electric power are closely related to electromagnetics. The devices, methods, and systems involving electrical energy require electromagnetic theory for a better understanding of their design and operation. In this era of information technology, the transmission of information with or without wires, a sound knowledge of electromagnetic field is essential. In electromagnetics, both electric and magnetic fields are defined in terms of the forces they produce. Thus, a strong grasp of field theory is essential for proper use of these fields to create forces, motion, and effects to do useful work, and to transmit noise free signals loaded with information.
Static and thermal instability analysis of embedded functionally graded carbon nanotube-reinforced composite plates based on HSDT via GDQM and validated modeling by neural network
Published in Mechanics Based Design of Structures and Machines, 2022
Ali Forooghi, Nasim Fallahi, Akbar Alibeigloo, Hosein Forooghi, Saber Rezaey
The magnetic field is obtained from the moving electric charges. To define how this complex environment is generated by electric charges and currents, the classic Maxwell’s equations are determined in the differential form according to the following relations (Karami et al. 2018): in which where represents the displacement vector. is the two-dimensional (2D) magnetic field vector that is applied to the considered system with the angle θ as follows (Ghorbanpour Arani et al. 2013):
Detection and evaluation of thermal aging brittleness of heat-resistant steel using magneto-acoustic compound techniques
Published in Nondestructive Testing and Evaluation, 2023
Yanhong Guo, Zenghua Liu, Xin Zhao, Cunfu He, Bin Wu
Electromagnetic induction involves two phenomena: induced induction and dynamic induction. Induced induction refers to the induction of an electromotive force in a stationary conductor loop when the magnetic field in the surrounding area of the stationary conductor loop changes. Dynamic induction refers to the movement of the conductor loop in a constant magnetic field, which causes the instantaneous change in the magnetic flux passing through the closed loop to produce a dynamic induced electromotive force.
A hybrid-electric propulsion system for an unmanned aerial vehicle based on proton exchange membrane fuel cell, battery, and electric motor
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2022
Amir Hamzeh Farajollahi, Mohsen Rostami, Mohammad Marefati
An electric motor generates mechanical energy through the interaction of magnetic fields and current-carrying conductors. According to the equivalent circuit provided by Drela (Drela 2007) for a direct current electric motor the shaft power is the torque time rotational speed (Hu et al. 2021):