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Letteratura scientifica selezionata sul tema "Electromagnetic losses"

Autore: Grafiati

Pubblicato: 25 gennaio 2025

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Articoli di riviste sul tema "Electromagnetic losses"

Gurova, Elena G. "Eddy Current Impact Estimation in Designing Vibroisolator with 3D Electromagnetic Stiffness Compensator". Applied Mechanics and Materials 792 (settembre 2015): 519–23. http://dx.doi.org/10.4028/www.scientific.net/amm.792.519.

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In this research the method of the calculation of the power losses in DC electromagnet through eddy currents, which are analog of the viscous friction, is presented. The influence of these currents on the operation of the vibroisolator with the electromagnetic stiffness compensator is estimated. The losses of the power on eddy currents are less than 1 per cent of the electromagnet power itself and the compensator totally. The example of the calculation of the losses for eddy currents in steel conductor is also shown.

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Matzui, Ludmila, Ludmila Vovchenko, Yuriy Prylutskyy, Igor Korotash, Volodymyr Matzui, Peter Eklund, Uwe Ritter e Peter Scharff. "Electromagnetic losses in carbon–epoxy composites". Materials Science and Engineering: C 27, n. 5-8 (settembre 2007): 1007–9. http://dx.doi.org/10.1016/j.msec.2006.06.017.

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Tsukerman, Igor. "Computational Electromagnetics: A Miscellany". J 4, n. 4 (15 dicembre 2021): 881–96. http://dx.doi.org/10.3390/j4040060.

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The paper presents a miscellany of unorthodox and, in some cases, paradoxical or controversial items related to computational and applied electromagnetics. The topics include a definition of the magnetic source field via a line integral, losses in electric power transmission vs. losses in photonics, homogenization of periodic electromagnetic structures, spurious modes, models of plasmonic media, and more. It is hoped that this assortment of subjects will be of interest to a broad audience of scientists and engineers.

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Deng, Xiong Fang, Ji Bo Hou, Lian Cheng e Ru Na Tian. "Research on Mechanism of Overland Flow Losses of Direct-Current Conduction Electromagnetic Pump for Casting". Applied Mechanics and Materials 401-403 (settembre 2013): 250–53. http://dx.doi.org/10.4028/www.scientific.net/amm.401-403.250.

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Compared with other factors, overland flow losses have stronger influence on the efficiency of direct-current conduction electromagnetic pump for casting. Mercury-media simulation of direct-current conduction electromagnetic pump is used. The mechanism of overland flow losses by changing the structure of liquid inlet was studied and got effective method of inhibiting overland flow losses. It can provide theoretical support for improving the efficiency of direct-current conduction electromagnetic pump.

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MATSUSHITA, Teruo. "Electromagnetic phenomena and hysteresis losses in superconductors." TEION KOGAKU (Journal of Cryogenics and Superconductivity Society of Japan) 24, n. 2 (1989): 83–92. http://dx.doi.org/10.2221/jcsj.24.83.

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Dupré, L., M. De Wulf, D. Makaveev, V. Permiakov, A. Pulnikov e J. Melkebeek. "Modelling of electromagnetic losses in asynchronous machines". COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 22, n. 4 (dicembre 2003): 1051–65. http://dx.doi.org/10.1108/03321640310482995.

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Matsushita, T. "Electromagnetic phenomena and hysteresis losses in superconductors". Cryogenics 30, n. 4 (aprile 1990): 314–23. http://dx.doi.org/10.1016/0011-2275(90)90309-z.

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Hong, Kyung-Pyo, e Ju Lee. "Design of 200 kW Cryogenic Induction Motor for Liquefied Natural Gas Emergency Pump". Energies 17, n. 8 (16 aprile 2024): 1898. http://dx.doi.org/10.3390/en17081898.

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This paper presents a design study focusing on the thermal safety of an induction motor integrated with a pump unit, which operates submerged in liquefied natural gas (LNG) in the LNG tanks of LNG carrier ships ranging from 150 K to 200 K cubic meters (CBM). In this study, we carried out the electromagnetic design of the induction motor and verified the thermal safety against a temperature increase due to losses during the motor operation through thermal fluid analysis, taking into account the discharge flow of the emergency pump and the air gap of the motor. In the electromagnetic design, the resistivity of the stator winding copper conductors and the rotor aluminum bars, which act as important design constants for the rated operating and starting characteristics of the induction motor in cryogenic temperature environments, reflects the characteristic of linearly changing with the temperature. In cryogenic environments, the reduction in the resistance of the rotor bars of the induction motor leads to a decrease in the starting torque characteristics. Therefore, the shape optimization design of the rotor bar was performed to improve the starting torque characteristics, and 2D electromagnetic analysis was performed on the magnetic flux density distribution and magnetic saturation using Ansys Electromagnetics 16.0. After the electromagnetic design, a 3D thermal flow analysis was conducted using Ansys Fluent 17.0, considering the stator iron losses, rotor bar losses, stator and rotor iron losses, and stray load losses as heat sources. The flow analysis aimed to analytically verify the thermal safety concerning the vaporization of the LNG flowing through the emergency pump’s discharge flow path and the motor’s internal air gap. The motor was manufactured, and the rated and starting operating characteristics of the motor were measured under LN2 submerged conditions according to the IEEE 112 F1 method, to validate whether the performance characteristics met the specifications’ requirements. Subsequently, the thermal safety of the motor was finally verified through a temperature increase test under LNG submerged conditions after assembling it with the emergency pump.

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Nikitenko, Anatolii, Mykola Kostin, Tetiana Mishchenko e Oksana Hoholyuk. "Electrodynamics of Power Losses in the Devices of Inter-Substation Zones of AC Electric Traction Systems". Energies 15, n. 13 (22 giugno 2022): 4552. http://dx.doi.org/10.3390/en15134552.

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This article presents a new method for the estimation of active power losses based on a “field” approach, i.e., on the theory of the electromagnetic field and the theory of propagation of electromagnetic waves in a dielectric medium. Electromagnetic waves are assumed to transmit energy from the traction substation to electric rolling stock through the airspace of the inter-substation zone (i.e., not through the wires of the traction network) and meet electrically conductive surfaces on their way. The waves are partially reflected from the surfaces and partially penetrate them, thus creating thermal losses, the determination of which is the main task of this article. The analytical expressions for specific losses of active power are obtained by solving the system of Maxwell’s equations. Calculations of specific power losses in the catenary, rails, roofs, and bottoms of carriages and electric locomotives are performed. Power losses in carriages and electric locomotives are found to be at least 7%. A comparative assessment of the magnitude of total power losses of different types obtained by the “field” and “circuit” approaches is provided, which has established that “conditional” losses correspond to losses in rails, train carriages, and electric locomotives.

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Ren, X., R. Corcolle e L. Daniel. "Losses Approximation for Soft Magnetic Composites Based on a Homogenized Equivalent Conductivity". Advanced Electromagnetics 5, n. 2 (28 settembre 2016): 59. http://dx.doi.org/10.7716/aem.v5i2.391.

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Soft magnetic composites (SMC) are a promising alternative to laminated steel in many Electrical Engineering applications. This is largely owing to their low level of eddy current losses. The electromagnetic behavior of SMC in electromagnetic devices cannot be easily predicted using standard numerical techniques such as the finite element method, mostly due to the computational cost required to model the material microstructure. Another difficulty lies in the high property contrast between the matrix and the inclusions. In this paper we propose a homogenization strategy to define the equivalent electromagnetic properties of SMC. For components made of SMC, the equivalent conductivity and permeability can be determined. These equivalent properties can be used to calculate eddy current losses or introduced into structural analysis tools to design electromagnetic devices.

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Più fonti

Tesi sul tema "Electromagnetic losses"

Ramprecht, Jörgen. "Electromagnetic Waves in Media with Ferromagnetic Losses". Doctoral thesis, KTH, Elektroteknisk teori och konstruktion, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4776.

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The operation of a wide variety of applications in today's modern society are heavily dependent on the magnetic properties of ferromagnetic materials and their interaction with electromagnetic fields. The understanding of these interactions and the associated loss mechanisms is therefore crucial for the improvement and future development of such applications. This thesis is concerned with electromagnetic waves in media with ferromagnetic losses. We model the dynamics of the magnetization of a ferromagnetic material with the nonlinear Landau-Lifshitz-Gilbert (LLG) equation and study stability conditions on static solutions. Furthermore, with the aid of a small signal analysis this equation is linearized around a stable static solution. From this analysis we obtain a small signal permeability, which shows that ferromagnetic material in general are gyrotropic with a resonant frequency behavior similar to that of a Lorentz material. In difference to dielectric Lorentz material, this resonance frequency can be shifted with the aid of a bias field. For a specific bias field we obtain a frequency behavior that mimics that of a material with electric conductivity losses. In terms of losses per unit volume it is then possible to define a magnetic conductivity which is independent of frequency. We treat composite materials built from ferromagnetic inclusions in a nonmagnetic and nonconductinig background material. The composite material inherits the gyrotropic structure and resonant behavior of the single particle. The resonance frequency of the composite material is found to be independent of the volume fraction, unlike dielectric composite materials. For small enough particles, typically around 100 nm, it becomes energetically favorable to form a single domain in the particle, where disturbances in the magnetization can propagate in the form of spin waves. We study the possibility of exciting spin waves and derive a susceptibility that takes spin waves into account. It is found that spin wave resonances are excited in the gigahertz range and this could offer a way to increase the losses in a composite material. We also discuss some concerns regarding stability and causality of effective material parameters for biased ferromagnetic materials. Finally, we discuss the possibility of using magnetic materials in absorbing applications. We analyze the scattering of electromagnetic waves from a metal surface covered with a thin magnetic lossy sheet. It is found that very thin magnetic layers can provide substantial specular absorption over a wide frequency band. However, magnetic specular absorbers, where the waves propagates just a fraction of the wavelength in the material, seem to require a certain amount of ferromagnetic material which make them quite heavy and thereby limit its practical use. On the other hand, for nonspecular absorbers where the waves propagates several wavelengths in the material, the amount of magnetic material required for efficient absorption seems to be substantially less than for specular absorbers. Thus, as nonspecular absorbers, magnetic lossy materials could offer very thin and light designs.
QC 20100906

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Ramprecht, Jörgen. "Electromagnetic waves in media with ferromagnetic losses /". Stockholm : Electromagnetic Engineering, Elektroteknisk teori & konstruktion, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4776.

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Ng, Kong. "Electromagnetic losses in brushless permanent magnet machines". Thesis, University of Sheffield, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.579745.

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Chen, Yu Ju. "A comprehensive electromagnetic analysis of AC losses in large superconducting cables". Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/41418.

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Irenji, Neamat Taghizadeh. "Calculation of electromagnetic rotor losses in high-speed permanent magnet machines". Thesis, University of Southampton, 1998. https://eprints.soton.ac.uk/47948/.

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High-speed permanent magnet machines are currently being developed for a number of applications including gas-turbine generator sets and machine tools. Due to the high peripheral speed of the rotor and the relatively high conductivity of the magnets used, rotor eddy current loss can be substantial. Quite low levels of loss may present a serious problem if rotor cooling is poor. The accurate calculation of these losses, and appreciation of their dependence on machine parameters, are therefore of great importance for reasons of both efficiency and temperature rise. In this, thesis, a method has been developed to evaluate the asynchronously rotating harmonics with respect to the rotor and to calculate rotor power loss caused by these harmonics. The harmonics are determined by double Fourier analysis of the normal flux density data over the rotor surface. The data is obtained from finite element magnetostatic analysis of the machine at different rotor positions, with all possible harmonic sources present, except rotor induced eddy currents whose effect on harmonics was found to be negligible. Rotor power loss is calculated for each harmonic using a 2D rectilinear current sheet model of the machine. The magnitude of the current sheet, which is placed on the inner surface of a toothless stator, is adjusted to produce the same magnetostatic normal flux density over the rotor surface as that of the corresponding harmonic. The 2D current sheet model does not allow for 3D end effects and magnet segmentation. The accuracy of the analytical rectilinear current sheet model was verified by comparison with a cylindrical FE current sheet model, and by solving a benchmark eddy current problem that can be also solved using FE steady-state AC analysis. The current sheet model was used to calculate rotor loss in a number of generic machines, with two basic types of rotor construction: 1) non-salient rotor with arc shaped surface magnets and 2) salient rotor with chord shaped surface magnets. The results show that rotor loss depends strongly on the ratio of slot opening to slot pitch (s/X.) and on the ratio of total airgap to slot pitch (g/X). For the same fundamental airgap flux density, rotor loss reduces dramatically by increasing airgap length and reducing slot opening. Increasing the number of slots also reduces the loss. The results also show that rotor loss in a generator increases as the power factor moves from lagging to leading due to the armature reaction effect. Using a conducting sleeve, instead of a non-conducting one, with conductivity in the range of practical values, increases rotor losses dramatically. Reducing magnet conductivity reduces rotor loss. Rotor power loss in machines with non-conducting sleeve is concentrated on the surface of the magnet and a small part on the surface of the hub. In machines with chord shaped magnets, the power loss density can be very high in the parts of the steel hub near the intersection of two poles where local total airgap is small. The harmonics caused by inverter switching in a motor or rectifier switching in an alternator can cause a very significant increase in rotor loss, compared to a machine with a sinusoidal mmf. The results also show that the loss depends strongly on the switching strategy, e.g., switching harmonics in 6 step mmf waveform produce 3 times more loss than a 12 step mmf waveform. Although the developed method for calculation of rotor power loss does not take the effect of magnet peripheral discontinuity or segmentation into account, it is clear that segmentation reduces power loss by interrupting the eddy current return path, specially for harmonics with long wavelengths. The effect of segmentation requires further study.

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Whitman, Daniel Joseph. "Electromagnetic Fields, Power Losses, and Resistance of High-Frequency Magnetic Devices". Wright State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=wright1268951694.

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Mousavi, Seyedali. "Electromagnetic Modelling of Power Transformers for Study and Mitigation of Effects of GICs". Doctoral thesis, KTH, Elektroteknisk teori och konstruktion, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-159747.

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Geomagnetic disturbances that result from solar activities can affect technological systems such as power networks. They may cause DC currents in power networks and saturation of the core in power transformers that leads to destruction in the transformer performance. This phenomena result in unwanted influences on power transformers and the power system. Very asymmetric magnetization current, increasing losses and creation of hot spots in the core, in the windings, and the metallic structural parts are adverse effects that occur in transformers. Also, increasing demand of reactive power and malfunction of protective relays menaces the power network stability. Damages in large power transformers and blackouts in networks have occurred due to this phenomenon. Hence, studies regarding this subject have taken the attention of researchers during the last decades. However, a gap of a comprehensive analysis still remains. Thus, the main aim of this project is to reach to a deep understanding of the phenomena and to come up with a solution for a decrease of the undesired effects of GIC. Achieving this goal requires an improvement of the electromagnetic models of transformers which include a hysteresis model, numerical techniques, and transient analysis. In this project, a new algorithm for digital measurement of the magnetic materials is developed and implemented. It enhances the abilities of accurate measurements and an improved hysteresis model has been worked out. Also, a novel differential scalar hysteresis model is suggested that easily can be implemented in numerical methods. Two and three dimensional finite element models of various core types of power transformers are created to study the effect of DC magnetization on transformers. In order to enhance the numerical tools for analysis of low frequency transients related to power transformers and the network, a novel topological based time step transformer model has been outlined. The model can employ a detailed magnetic circuit and consider nonlinearity, hysteresis and eddy current effects of power transformers. Furthermore, the proposed model can be used in the design process of transformers and even extend other application such as analysis of electrical machines. The numerical and experimental studies in this project lead to understanding the mechanism that a geomantic disturbance affects power transformers and networks. The revealed results conclude with proposals for mitigation strategies against these phenomena.

QC 20150210

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Shahabi, Ghahfarokhi Neda. "Minimising capacitive couplings and distributing copper losses in planar magnetic elements". Thesis, Queensland University of Technology, 2010. https://eprints.qut.edu.au/43466/1/Neda_Shahabi_Ghahfarokhi_Thesis.pdf.

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Planar magnetic elements are becoming a replacement for their conventional rivals. Among the reasons supporting their application, is their smaller size. Taking less bulk in the electronic package is a critical advantage from the manufacturing point of view. The planar structure consists of the PCB copper tracks to generate the desired windings .The windings on each PCB layer could be connected in various ways to other winding layers to produce a series or parallel connection. These windings could be applied coreless or with a core depending on the application in Switched Mode Power Supplies (SMPS). Planar shapes of the tracks increase the effective conduction area in the windings, brings about more inductance compared to the conventional windings with the similar copper loss case. The problem arising from the planar structure of magnetic inductors is the leakage current between the layers generated by a pulse width modulated voltage across the inductor. This current value relies on the capacitive coupling between the layers, which in its turn depends on the physical parameters of the planar scheme. In order to reduce this electrical power dissipation due to the leakage current and Electromagnetic Interference (EMI), reconsideration in the planar structure might be effective. The aim of this research is to address problem of these capacitive coupling in planar layers and to find out a better structure for the planar inductance which offers less total capacitive coupling and thus less thermal dissipation from the leakage currents. Through Finite Element methods (FEM) several simulations have been carried out for various planar structures. The labs prototypes of these structures are built with the similar specification of the simulation cases. The capacitive couplings of the samples are determined with Spectrum Analyser whereby the test analysis verified the simulation results.

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Prasai, Anish. "Methodologies for Design-Oriented Electromagnetic Modeling of Planar Passive Power Processors". Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/34164.

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The advent and proliferation of planar technologies for power converters are driven in part by the overall trends in analog and digital electronics. These trends coupled with the demands for increasingly higher power quality and tighter regulations raise various design challenges. Because inductors and transformers constitute a rather large part of the overall converter volume, size and performance improvement of these structures can subsequently enhance the capability of power converters to meet these application-driven demands. Increasing the switching frequency has been the traditional approach in reducing converter size and improving performance. However, the increase in switching frequency leads to increased power loss density in windings and core, with subsequent increase in device temperature, parasitics and electromagnetic radiation. An accurate set of reduced-order modeling methodologies is presented in this work in order to predict the high-frequency behavior of inductors and transformers. Analytical frequency-dependent expressions to predict losses in planar, foil windings and cores are given. The losses in the core and windings raise the temperature of the structure. In order to ensure temperature limitation of the structure is not exceeded, 1-D thermal modeling is undertaken. Based on the losses and temperature limitation, a methodology to optimize performance of magnetics is outlined. Both numerical and analytical means are employed in the extraction of transformer parasitics and cross-coupling. The results are compared against experimental measurements and are found to be in good accord. A simple near-field electromagnetic shield design is presented in order to mitigate the amount of radiation. Due to inadequacy of existing winding technology in forming suitable planar windings for PCB application, an alternate winding scheme is proposed which relies on depositing windings directly onto the core.
Master of Science

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Mohammad, Mostak. "Optimization of Inductive Wireless Charging Systems for Electric Vehicles: Minimizing Magnetic Losses and Limiting Electromagnetic Field Emissions". University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1564756659521461.

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Libri sul tema "Electromagnetic losses"

United States. National Aeronautics and Space Administration., a cura di. A model for the scattering of high-frequency electromagnetic fields from dielectrics exhibiting thermally-activated electrical losses. [Washington, DC]: National Aeronautics and Space Administration, 1991.

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Genenko, Yuri, e Hermann Rauh. Electromagnetics of Superconductor/Paramagnet Heterostructures. Oxford University PressOxford, 2025. https://doi.org/10.1093/9780191782855.001.0001.

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Abstract Redistribution of the transport current in a superconductor affected by paramagnetic shields provides a possibility of strongly overcritical states and a drastic reduction of AC losses in thin superconductor films and tubes. Such superconductors subject to para- or diamagnetic shielding are studied by means of the potential theory and the critical state model when carrying a transport current or exposed to an external magnetic field. Analytical results are obtained for a number of shielding geometries and confirmed by numerical solutions. It is shown that using magnetostatic-electrostatic analogies allows consideration of paramagnetic shielding configurations of arbitrary shapes and magnetic permeabilities by means of common finite-element solvers to enhance the dissipation-free transport currents in superconductors and reduce AC losses in them. Furthermore, using the generalized London theory, the penetration of magnetic flux into magnetically shielded bulk superconductors is studied and the enhancement of the Bean-Livingston barrier is established.

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Mashhoon, Bahram. Acceleration Kernel. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198803805.003.0003.

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The phenomenon of spin-rotation coupling provides the key to the determination of the kernel. Imagine an observer rotating in the positive sense about the direction of propagation of an incident plane monochromatic electromagnetic wave of positive helicity. Using the locality postulate, the field as measured by the rotating observer can be determined. If the observer rotates with the same frequency as the wave, the measured radiation field loses its temporal dependence. By a mere rotation, observers could in principle stay at rest with respect to an incident positive-helicity wave. To avoid this possibility, we assume that a basic radiation field cannot stand completely still with respect to an accelerated observer. This basic principle eventually leads to the determination of the kernel and a nonlocal theory of accelerated systems that is in better agreement with quantum mechanics than the standard theory based on the hypothesis of locality.

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Horing, Norman J. Morgenstern. Random Phase Approximation Plasma Phenomenology, Semiclassical and Hydrodynamic Models; Electrodynamics. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198791942.003.0010.

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Chapter 10 reviews both homogeneous and inhomogeneous quantum plasma dielectric response phenomenology starting with the RPA polarizability ring diagram in terms of thermal Green’s functions, also energy eigenfunctions. The homogeneous dynamic, non-local inverse dielectric screening functions (K) are exhibited for 3D, 2D, and 1D, encompassing the non-local plasmon spectra and static shielding (e.g. Friedel oscillations and Debye-Thomas-Fermi shielding). The role of a quantizing magnetic field in K is reviewed. Analytically simpler models are described: the semiclassical and classical limits and the hydrodynamic model, including surface plasmons. Exchange and correlation energies are discussed. The van der Waals interaction of two neutral polarizable systems (e.g. physisorption) is described by their individual two-particle Green’s functions: It devolves upon the role of the dynamic, non-local plasma image potential due to screening. The inverse dielectric screening function K also plays a central role in energy loss spectroscopy. Chapter 10 introduces electromagnetic dyadic Green’s functions and the inverse dielectric tensor; also the RPA dynamic, non-local conductivity tensor with application to a planar quantum well. Kramers–Krönig relations are discussed. Determination of electromagnetic response of a compound nanostructure system having several nanostructured parts is discussed, with applications to a quantum well in bulk plasma and also to a superlattice, resulting in coupled plasmon spectra and polaritons.

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Boudreau, Joseph F., e Eric S. Swanson. Simulation. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198708636.003.0015.

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This chapter is devoted to Monte Carlo simulation of stochastic processes, both fundamental processes and those involving radiation transport through macroscopic material. The computation of fundamental processes builds on the treatment of rotations and Lorentz transformations from the previous chapter and expands it with a discussion of computational techniques for the evaluation of Feynman diagrams. The simulation of radiation transport covers electromagnetic processes such as ionization energy loss, bremsstrahlung, and pair production. A discussion of real-life challenges in the simulation of radiation transport is included, as well as a brief discussion of simulation toolkits that are available for solving industrial-strength problems. The discussion is intended to give an overview of some of the principal computational and numerical techniques enabling these toolkits.

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Konijnenberg, Sander, Aurele J. L. Adam e H. Paul Urbach. BSc Optics. TU Delft Open, 2021. http://dx.doi.org/10.5074/t.2021.003.

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This book treats optics at the level of students in the later stage of their bachelor or the beginning of their master. It is assumed that the student is familiar with Maxwell’s equations. Although the book takes account of the fact that optics is part of electromagnetism, special emphasis is put on the usefulness of approximate models of optics, their hierarchy and limits of validity. Approximate models such as geometrical optics and paraxial geometrical optics are treated extensively and applied to image formation by the human eye, the microscope and the telescope. Polarisation states and how to manipulate them are studied using Jones vectors and Jones matrices. In the context of interference, the coherence of light is explained thoroughly. To understand fundamental limits of resolution which cannot be explained by geometrical optics, diffraction theory is applied to imaging. The angular spectrum method and evanescent waves are used to understand the inherent loss of information about subwavelength features during the propagation of light. The book ends with a study of the working principle of the laser.

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Capitoli di libri sul tema "Electromagnetic losses"

Janowski, Tadeusz, e Ryszard Goleman. "Additional Losses in Frequency Tripler Windings". In Electromagnetic Fields in Electrical Engineering, 107–12. Boston, MA: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4613-0721-1_21.

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Béland, Bernard, e Daniel Gamache. "Impedance and Losses in Magnetic Cylindrical Conductors". In Electromagnetic Fields in Electrical Engineering, 39–43. Boston, MA: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4613-0721-1_8.

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Kerényi, D. "Stray-Load Losses in Yoke-Beams of Transformers". In Electromagnetic Fields in Electrical Engineering, 113–18. Boston, MA: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4613-0721-1_22.

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Anuszczyk, Jan. "Power Losses in Electrotechnical Sheet Steel under Rotational Magnetization". In Electromagnetic Fields in Electrical Engineering, 3–7. Boston, MA: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4613-0721-1_2.

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Babare, A., A. Di Napoli, E. Santini e G. Scendrate. "A Method for Losses Evaluation in Large Power Transformer Tanks". In Electromagnetic Fields in Electrical Engineering, 95–100. Boston, MA: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4613-0721-1_19.

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Ferreira, J. A. "Skin and Proximity Effect Losses in Transformer and Inductor Windings". In Electromagnetic Modelling of Power Electronic Converters, 83–96. Boston, MA: Springer US, 1989. http://dx.doi.org/10.1007/978-1-4757-2014-3_6.

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Ferreira, J. A. "Experimental Measurement of Eddy Current Losses in Transformer Windings and Inductor Coils". In Electromagnetic Modelling of Power Electronic Converters, 107–24. Boston, MA: Springer US, 1989. http://dx.doi.org/10.1007/978-1-4757-2014-3_8.

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Wu, Ke. "Electromagnetic Analysis of Multiconductor Losses and Dispersion in High-Speed Interconnects". In Modeling and Simulation of High Speed VLSI Interconnects, 47–56. Boston, MA: Springer US, 1994. http://dx.doi.org/10.1007/978-1-4615-2718-3_5.

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Kajikawa, Kazuhiro, Hideaki Shiraishi, Atsushi Takenaka, Masataka Iwakuma e Kazuo Funaki. "Effects of Winding Pitch on Transverse-Field Losses Measured by a Simple Electromagnetic Method". In Advances in Superconductivity XI, 967–70. Tokyo: Springer Japan, 1999. http://dx.doi.org/10.1007/978-4-431-66874-9_226.

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Huang, Na, Jie Yang, Wenbin Yu e Guanghui Du. "Analysis of Electromagnetic and Losses Characteristics for 12 MW Permanent Magnet Synchronous Wind Generator". In Lecture Notes in Electrical Engineering, 768–75. Singapore: Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-97-1447-6_78.

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Atti di convegni sul tema "Electromagnetic losses"

Dikmarova, Liudmyla, Petro Dub, Vitalij Nichoga e Liubomyr Sopilnyk. "Electromagnetic Connection Parameters of Coaxial Lines in Medium with Losses". In EMC_2002_Wroclaw, 257–60. IEEE, 2002. https://doi.org/10.23919/emc.2002.10842590.

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Dikmarova, Liudmyla, Petro Dub, Vitalij Nichoga e Liubomyr Sopilnyk. "Electromagnetic Connection Parameters of Coaxial Lines in Medium with Losses". In EMC_2002_Wroclaw, 1–4. IEEE, 2002. https://doi.org/10.23919/emc.2002.10842305.

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Araneo, Rodolfo, e Stefano Lauria. "Corona and Ground Losses Influence on Surge Propagation in Multiconductor Power Lines". In 1992 International Symposium on Electromagnetic Compatibility, 1091–96. IEEE, 1992. https://doi.org/10.1109/isemc.2002.10792206.

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Li, Zhaokai, Bin Liu, Peter Fransson e Luca Peretti. "Equivalent Resistance Model of the Permanent-Magnet Motor for Predicting Electromagnetic Losses". In 2024 International Conference on Electrical Machines (ICEM), 1–6. IEEE, 2024. http://dx.doi.org/10.1109/icem60801.2024.10700397.

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Maio, I., e F. G. Canavero. "Modelling of Line Losses and Dispersion Effects for Signal Integrity Simulation". In 11th International Zurich Symposium and Technical Exhibition on Electromagnetic Compatibility, 197–202. IEEE, 1995. https://doi.org/10.23919/emc.1995.10784264.

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Wang, Shuwen, e Aiming Zhao. "References Maxwell-based Permanent Magnet Synchronous Motor Short Circuit Faults and Electromagnetic Losses". In 2024 3rd International Conference on Energy, Power and Electrical Technology (ICEPET), 1367–72. IEEE, 2024. http://dx.doi.org/10.1109/icepet61938.2024.10626737.

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Wong, Bert, Antonio Cantoni, Kevin Fynn e Joe Trinkle. "Effect of Modelling Fringing and Losses for a Microstrip on the Radiated Emission Characteristics". In 16th International Zurich Symposium and Technical Exposition on Electromagnetic Compatibility, 557–62. IEEE, 2005. https://doi.org/10.23919/emc.2005.10806328.

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Bohl, Lennart P. P. B., Guido A. Rasek, Thomas Stöhr, Cheng Yang e Christian Schuster. "Calculation and Distribution of Losses in EMC Filters in the High-Voltage Power Train for an Electric Vehicle". In 2024 International Symposium on Electromagnetic Compatibility – EMC Europe, 985–90. IEEE, 2024. http://dx.doi.org/10.1109/emceurope59828.2024.10722334.

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Zvezdina, Marina Yu, Yulia A. Shokova, Anna M. Shaposhnikova e Larisa V. Cherckesova. "Climate Factors Impact on Millimetre Antenna Losses". In 2021 Radiation and Scattering of Electromagnetic Waves (RSEMW). IEEE, 2021. http://dx.doi.org/10.1109/rsemw52378.2021.9494012.

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Wrobel, R., A. Mlot e P. H. Mellor. "Investigation of end-winding proximity losses in electromagnetic devices". In 2010 XIX International Conference on Electrical Machines (ICEM). IEEE, 2010. http://dx.doi.org/10.1109/icelmach.2010.5608236.

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Rapporti di organizzazioni sul tema "Electromagnetic losses"

Corones, Jim. Transient Electromagnetic Scattering from Heterogeneous Lossy Spheres. Fort Belvoir, VA: Defense Technical Information Center, gennaio 1987. http://dx.doi.org/10.21236/ada186669.

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Mei, Kenneth K. Time Domain Scattering of Focused Electromagnetic Beam by Lossy Targets. Fort Belvoir, VA: Defense Technical Information Center, settembre 1989. http://dx.doi.org/10.21236/ada227741.

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Shore, Robert A., e Arthur D. Yaghjian. Traveling Electromagnetic Waves on Linear Periodic Arrays of Small Lossless Penetrable Spheres. Fort Belvoir, VA: Defense Technical Information Center, giugno 2004. http://dx.doi.org/10.21236/ada429387.

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Riley, D. J., e C. D. Turner. The inclusion of wall loss in electromagnetic finite-difference time-domain thin-slot algorithms. Office of Scientific and Technical Information (OSTI), settembre 1990. http://dx.doi.org/10.2172/6448589.

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Zhao, George, Grang Mei, Bulent Ayhan, Chiman Kwan e Venu Varma. DTRS57-04-C-10053 Wave Electromagnetic Acoustic Transducer for ILI of Pipelines. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), marzo 2005. http://dx.doi.org/10.55274/r0012049.

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In this project, Intelligent Automation, Incorporated (IAI) and Oak Ridge National Lab (ORNL) propose a novel and integrated approach to inspect the mechanical dents and metal loss in pipelines. It combines the state-of-the-art SH wave Electromagnetic Acoustic Transducer (EMAT) technique, through detailed numerical modeling, data collection instrumentation, and advanced signal processing and pattern classifications, to detect and characterize mechanical defects in the underground pipeline transportation infrastructures. The technique has four components: (1) thorough guided wave modal analysis, (2) recently developed three-dimensional (3-D) Boundary Element Method (BEM) for best operational condition selection and defect feature extraction, (3) ultrasonic Shear Horizontal (SH) waves EMAT sensor design and data collection, and (4) advanced signal processing algorithm like a nonlinear split-spectrum filter, Principal Component Analysis (PCA) and Discriminant Analysis (DA) for signal-to-noise-ratio enhancement, crack signature extraction, and pattern classification. This technology not only can effectively address the problems with the existing methods, i.e., to detect the mechanical dents and metal loss in the pipelines consistently and reliably but also it is able to determine the defect shape and size to a certain extent.

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Maydykovskiy, Igor, e Petras Užpelkis. The Physical Essence of Time. Intellectual Archive, dicembre 2020. http://dx.doi.org/10.32370/iaj.2450.

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The article considers the model of the space-frequency-time continuum, according to which the physical essence of Time is manifested as a fraction of electromagnetic energy spent on updating a material object in a cyclic process of copying-incarnation. For all structural levels of physical reality, the value of this fraction is a fundamental constant, which can be represented as the tangent of the loss angle, or expressed in radians, as the angle of inclination of the evolutionary spiral, which characterizes the rate of change of states or the duration of events and processes. The value of this constant can be calculated, and its value turns out to be identically equals to the square of the fine structure Constant (α2). The description of the method for identifying a new constant allows us to present the formula of Scientific Discovery as the Physical Essence of Time.

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Lee, Wall e Burch. L52333 NDE and Inspection Techniques Applied to Composite Wrap Repairs. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), giugno 2012. http://dx.doi.org/10.55274/r0010468.

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The objective includes: Assess commercially available inspection methods to validate integrity of composite repair systems. Identify applicability to inspect composite overwrap and parent metal for both onshore and sub-sea pipelines (where information is available). Identify sources of data to include other users of composite materials(aerospace/aircraft, naval/ship repairs). Identify procedures and technologies to assess inspection effectiveness and provide a gap analysis. Interface with other PRCI projects on long-term testing of composite repairs and other joint industry projects on composite repairs to improve our understanding of long term durability of repairs. Identify global experience with composite repairs; not just North America. For general wall loss, radiography or electromagnetic techniques appear to be the best candidates. Standard radiography techniques can detect changes in wall thickness over a large area. Saturated low frequency systems, e.g. SLOFEC are good for a quick rapid scan of the area of interest. Pulsed eddy current, e.g. PEC, is also available for a general survey of the underlying substrate. For pinhole leaks, the electromagnetic techniques do not have sufficient resolution to detect defects of order 20 mm (0.8 in.) diameter and less. Standard radiography techniques can detect pinhole leaks down to diameters of 3 mm (0.12 in.) or less. Tangential radiography techniques are generally good for defect sizing but there are practical limitations with chord length (i.e. beam path through the pipe wall). Ultrasonic techniques could offer a potential solution but is currently limited due to the high attenuation of the composite repair material where through the repair inspection could only detect large diameter defects greater than 25 mm (1 in.) diameter on thin repairs less than 5 mm (0.2 in.). Detecting pin hole defects by applying the ultrasound along the axial direction of the substrate, effectively skipping the ultrasound under the repair, showed more promise. For delamination or debonding of the interface between the composite laminate and the steel substrate, laser shearography and microwave inspection appear to offer the best solution. Currently there is no single inspection technique that can be applied with confidence to the inspection of interfacial delaminations. Further developments are on-going to provide a solution to this challenging inspection problem. Acoustic emission is able to give an overall picture of the damage within the composite under live loads. It can be used as a QA tool to test the integrity of the repair. However, it is difficult to interpret the signals to gain any quantitative information about a particular defect.

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Nestleroth e Alers. L51946 Enhanced Implementation of MFL Using EMAT Sensors to Detect External Coating Disbondment. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), dicembre 2002. http://dx.doi.org/10.55274/r0010676.

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External coatings are used routinely to protect transmission pipelines from conditions that promote corrosion. However, over time coatings may disbond, allowing corrosion to occur. To detect metal loss due to corrosion defects, transmission pipeline operators often use magnetic flux leakage (MFL) in-line inspection tools. These tools do not detect the cause of an actual problem, i.e., failure of a coating and the presence of a corrosive environment; rather, they detect only the result, i.e., a defect that may permanently alter the pressure capacity of the pipeline. Metal loss is the most common defect that occurs at a disbond; however, it is not the only defect that can occur. Stress corrosion cracking (SCC) almost always occurs at disbonds. Information about disbonded and missing coatings, soil models, cathodic protection assessment, and related data could be used to assess a pipeline for the potential of cracking. Direct inspection of the coating could indicate potential problems that could lead to pipeline degradation that affects serviceability. SCC can be detected using in-line inspection technology, but such tools have a limited availability and limited success in natural gas pipelines, and the cost of inspection is high compared to MFL inspection. A novel method for the in-line evaluation of a protective coating on a pipeline was shown to be feasible. The method involves the merging of two technologies, magnetic flux leakage (MFL) and electromagnetic acoustic transducers (EMATs). The results of the testing performed at the Pipeline Simulation Facility showed three technical accomplishments. First, EMATs could be designed to work with the magnetic fields produced by an MFL tool, although fields 2 to 3 times greater are usually optimal for EMAT sensors. Second, the EMAT transmitter and receiver could be mounted on an MFL inspection tool without interfering with the corrosion detection sensors. Finally, the EMAT sensors as implemented on the MFL pig could detect missing coating and disbonds on wrapped tar coating. While technical issues remain that would broaden the applicability, the immediate implementation of this technology for specific coating problems is possible.

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Nestleroth. L52298 Augmenting MFL Tools With Sensors that Assess Coating Condition. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), marzo 2009. http://dx.doi.org/10.55274/r0010396.

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Abstract (sommario):

External coatings are routinely used to protect transmission pipelines from corrosion; however, coatings may degrade or disbond over time enabling corrosion to occur. Transmission pipeline operators often use magnetic flux leakage (MFL) in-line inspection tools to detect metal loss corrosion defects. Rather than finding the cause of a problem, failure of the coating within a corrosive environment, MFL corrosion surveys only find the result of the problem, corrosion defects that may permanently alter the pressure carrying capacity of the pipeline. Stress corrosion cracking (SCC) can be detected using in-line inspection (ILI) technology, but the availability of tools is limited and the cost of inspection is high compared to MFL inspection. SCC almost always occurs at coating faults; direct coating assessment could indicate future problems that could degrade the serviceability of the pipeline. In this project, a new sensor was developed to assess external coating that could work with currently available ILI tools for minimal additional cost to perform the inspection. The sensors, electromagnetic acoustic transducers (EMATs), generate ultrasonic waves that are guided by the pipe material around the circumference of the pipe. The coating material and adherence can influence the propagation of the ultrasonic waves; changes in ultrasonic signal features were attributed to coating faults. This development used modeling and experiments to establish a more optimal configuration for coating assessment. A multiple feature approach was used. A commonly used feature, signal amplitude, provided good sensitivity to coating condition but was influenced by inspection variables. One unique feature identified in this development is arrival time of the ultrasonic wave. For the wave type and frequency selected, the wave velocity was different for bare and coated pipe. Therefore, disbonded or missing coating can be detected by monitoring arrival time of the ultrasonic wave, a feature that is amplitude independent. Another feature for assessing coating, absorption of selective frequencies, was also demonstrated. Coating assessment capability was experimentally demonstrated using a prototype EMAT ILI tool. All three detection features were shown to perform well in an ILI environment as demonstrated at Battelle"s Pipeline Simulation Facility and BJ Inspection Services pull rigs. Improvement to the prototype occurred between each test; the most significant improvement was the design and construction of a novel set of thick-trace transmitting and receiving Printed Circuit Board (PCB) EMAT coils. Implementation variables such as moisture and soil loading were shown to have a minimal influence on results.

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Drive modelling and performance estimation of IPM motor using SVPWM and Six-step Control Strategy. SAE International, aprile 2021. http://dx.doi.org/10.4271/2021-01-0775.

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This paper presents a comprehensive evaluation of the performance of an interior permanent magnet (IPM) traction motor drive, and analyses the impact of different modulation techniques. The most widely used modulation methods in traction motor drives are Space vector modulation (SVPWM), over-modulation, and six-step modulation have been implemented. A two-dimensional electromagnetic finite element model of the motor is co-simulated with a dynamic model of a field-oriented control (FOC) circuit. For accurate tuning of the current controllers, extended complex vector synchronous frame current regulators are employed. The DC-link voltage utilization, harmonics in the output waveforms, torque ripple, iron losses, and AC copper losses are calculated and compared with sinusoidal excitation. Overall, it is concluded that the selection of modulation technique is related to the operating condition and motor speed, and a smooth transition between different modulation techniques is essential to achieve a better performance.

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