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Spacecraft Actuators
Published in Yaguang Yang, Spacecraft Modeling, Attitude Determination, and Control Quaternion-based Approach, 2019
Magnetic torque rods have been used in most low orbit earth satellites. Magnetic torque rods are generally planar coils of uniform wire rigidly placed along the spacecraft body axes. When electricity passes through the coils, a magnetic dipole is created. The strength of the dipole depends on several factors, such as amount of electricity and total area enclosed by the coils, etc. This dipole interacts with Earth’s magnetic field, causing the coils to attempt to align their own magnetic field in the direction opposite to that of Earth’s.
Electric and magnetic fields
Published in James R. Nagel, Cynthia M. Furse, Douglas A. Christensen, Carl H. Durney, Basic Introduction to Bioelectromagnetics, 2018
James R. Nagel, Cynthia M. Furse, Douglas A. Christensen, Carl H. Durney
Similar to how E causes partial alignment of permanent electric dipoles in materials, B causes partial alignment of permanent magnetic dipoles in materials (but there is no effect of B analogous to the separation of electric charge by an applied E field). The alignment of magnetic dipoles becomes very important during magnetic resonance imaging (MRI) applications, as described in Section 6.4.
Magnetic Resonance Imaging
Published in Kwan Hoong Ng, Jeannie Hsiu Ding Wong, Geoffrey D. Clarke, Problems and Solutions in Medical Physics, 2018
Kwan Hoong Ng, Jeannie Hsiu Ding Wong, Geoffrey D. Clarke
Classically, the magnetic dipole moment is a measure of the magnetic strength of a magnet or current-carrying coil, described in terms of the torque that the magnet experiences when placed in an external magnetic field (see Figure 9.1). As the electrons travel around the coil, the north pole of the magnet is attracted to the south pole of the external magnetic field, causing a net rotation of the current loop. The magnetic moment has a close connection with angular momentum through a phenomenon called the ‘gyromagnetic effect’. The ‘gyromagnetic effect’ manifests when a magnetic moment is subject to a torque in a magnetic field that tends to align it with the applied magnetic field. The moment ‘precesses’, i.e. it rotates about the axis of the applied field. This is the same motion that a gyroscope makes as it is spinning and rotating within a gravitational field.
Magnetic dipole dynamics on Reiner–Philippoff boundary layer flow
Published in Numerical Heat Transfer, Part A: Applications, 2023
Yusuf O. Tijani, Adeshina T. Adeosun, Hammed A. Ogunseye, Hari Niranjan
A magnetic dipole is a fundamental concept in electromagnetism that refers to a system of two magnetic charges of opposite sign and equal strength separated by a small distance. It is analogous to an electric dipole, which consists of two electric charges of opposite sign and equal magnitude separated by a small distance. There has been a spotlight of research attention on magnetic dipole in other fields of science due to its immersive application. Several applications in heat transfer benefit from the use of the magnetic dipole phenomenon, ranging from magnetic resonance imaging to electronic devices. This physical constitutive relation led to an additional term in the equation of motion for fluid flow and energy balance, see Ref. [19]. Studies relating to investigating the magnetic dipole effect on fluid flow are quite recent in the scientific community. A quick Scopus search with keywords: “Magnetic Dipole” + “Fluid Flow” + “Heat Transfer” revealed 156 documents as at the time of this research. Zeeshan et al. [20] explore the numerical solution for magnetic dipole influence over an expanding sheet with thermal radiation. Anderson et al. [19] examine the rate of heat transfer for ferrofluid considering a magnetic dipole over an expanding surface. Waqas et al. [21] scrutinize magnetic dipole and activation energy in a flowing Eyring–Powell nanofluid over an expanding sheet. Prasannakumara [22] modeled -Maxwell nanofluid by considering magnetic dipole impact. Other notable studies where information and research notes on fluid flow with magnetic dipole attribute can be found include Misbah and Muhammad [23], Tabassam et al. [24] and Muhammad et al. [25]. To the best of our knowledge, all of the above mentioned studies (with the expception on Na [1] and Tijani et al. [7]) in the literature have considered flow over a region and applied magnetic field as a body force to the Reiner–Philippoff fluid flow. To this end, no study has considered the choice of magnetic dipole effect using a generalized main-stream velocity, at least, not to the author’s knowledge. This study brings to light the impact of magnetic dipole and generalized main-stream velocity on the Reiner–Philippoff fluid. The practical intuition of the generalized main-stream velocity is the ability to see the behavior of boundary layer flow with different main-stream velocity without having to simulate the velocities in separate models.