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Journal articles on the topic 'Approach law for magnetic saturation'

Author: Grafiati

Published: 4 June 2021

Last updated: 1 February 2022

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1

Yamkane, Z., R. Fersi, F. Z. Rachid, R. Moubah, H. Lassri, N. Mliki, S. Alleg, M. Sajieddine, and L. Bessais. "Law of Approach to Magnetic Saturation in Nanocrystalline Pr2Co7Cx(x≤1): Effects of Carbonation." SPIN 10, no. 03 (August 14, 2020): 2050016. http://dx.doi.org/10.1142/s2010324720500162.

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We report on the effect of Carbon insertion on the microstructure and magnetic properties of nanocrystalline Pr2Co7Cx([Formula: see text]). The Pr2Co7Cx were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and physical property measurement system (PPMS9) Quantum Design. Mean field theory was utilized to depict the temperature dependence of magnetization and deduce the exchange interactions. The approach to saturation magnetization was as well used. The results were interpreted in the framework of random magnetic anisotropy model. From such analysis, some fundamental parameters were extracted.

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2

Devi, Elangbam Chitra, and Ibetombi Soibam. "Law of Approach to Saturation in Mn–Zn Ferrite Nanoparticles." Journal of Superconductivity and Novel Magnetism 32, no. 5 (August 3, 2018): 1293–98. http://dx.doi.org/10.1007/s10948-018-4823-4.

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3

Devi, Elangbam Chitra, and Ibetombi Soibam. "Magnetic properties and law of approach to saturation in Mn-Ni mixed nanoferrites." Journal of Alloys and Compounds 772 (January 2019): 920–24. http://dx.doi.org/10.1016/j.jallcom.2018.09.160.

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4

UTSUNOMIYA, Tomoaki, Hidekazu NISHIZAWA, Kiyoshi KANETA, and Hideaki KONDO. "A magnetic method for measuring stress based on law of approach to saturation magnetization." Journal of Advanced Science 1, no. 1 (1989): 79–81. http://dx.doi.org/10.2978/jsas.1.79.

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5

Zhang, Zhan Xin, Hui Li Li, Tao Liu, and Feng Ming Wang. "The Measurement for the Effective Anisotropy Constant of the Nanocomposite Permanent Magnetic Material Nd₂Fe₁₄B/α-Fe." Advanced Materials Research 189-193 (February 2011): 292–95. http://dx.doi.org/10.4028/www.scientific.net/amr.189-193.292.

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The effective anisotropy constant and the saturation magnetization in nano composite Nd2Fe14B/α-Fe have been calculated by the law of approach to saturation (LATS) method. The applicability of the method has been analyzed. The calculated result shows that the LATS method is suitable for the calculation of the effective anisotropy constant and the saturation magnetization in nano composite permanent magnetic materials.

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6

Hua, Bing, Nan Zhang, and Mohong Zheng. "Satellite magnetic/momentum wheel attitude control technology based on PIO cascade-saturation algorithm." World Journal of Engineering 18, no. 4 (March 26, 2021): 645–50. http://dx.doi.org/10.1108/wje-10-2020-0536.

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Purpose Taking into account the factors of torque saturation and angular velocity limitation during the actual attitude maneuver of the satellite, as well as the difficulty of parameter selection in the design of attitude control algorithm, the purpose of this paper is to propose a satellite magnetic/momentum wheel attitude control technology based on pigeon-inspired optimization (PIO) cascade-saturation control law optimization. Design/methodology/approach The optimal parameters are calculated through the PIO algorithm and then the parameters are used in the cascade-saturation control law to control the actuator findings-mathematical simulation results show that the cascade-saturation control law optimization algorithm based on PIO can shorten the adjustment time and reduce the steady-state error. Findings Compared with traditional attitude maneuver control with given parameters, the PIO algorithm can accurately calculate the optimal parameters needed to achieve the control objective and this method has better stability and higher accuracy. Originality/value The innovative PIO algorithm is used to calculate the optimal parameters, and the cascade saturation control law is used to control the actuator. Compared with the traditional algorithm, the regulation time is shortened and the steady-state error is reduced.

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7

Komogortsev, S. V., and R. S. Iskhakov. "Law of approach to magnetic saturation in nanocrystalline and amorphous ferromagnets with improved transition behavior between power-law regimes." Journal of Magnetism and Magnetic Materials 440 (October 2017): 213–16. http://dx.doi.org/10.1016/j.jmmm.2016.12.145.

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8

Utsunomiya, T., H. Nishizawa, and K. Kaneta. "Biaxial stress measurement using a magnetic probe based on the law of approach to saturation magnetization." NDT & E International 24, no. 2 (April 1991): 91–94. http://dx.doi.org/10.1016/0963-8695(91)90823-l.

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9

KUNO, Tomoko, Shunji SUZUKI, Kimiko URUSHIBATA, Kurima KOBAYASHI, Noritsugu SAKUMA, Kazuya YOKOTA, Masao YANO, Akira KATO, and Akira MANABE. "Effects of the Applied Magnetic Field for Measurements in the Law of Approach to Ferromagnetic Saturation (LAFS)." Journal of the Japan Society of Powder and Powder Metallurgy 63, no. 13 (2016): 1053–59. http://dx.doi.org/10.2497/jjspm.63.1053.

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10

Kronmüller, H., V. A. Ignatchenko, and A. Forkl. "Law of approach to magnetic saturation in inhomogeneous ferri- and antiferromagnets and in amorphous iron-rich Fe-Zr alloys." Journal of Magnetism and Magnetic Materials 134, no. 1 (May 1994): 68–74. http://dx.doi.org/10.1016/0304-8853(94)90074-4.

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11

Man’kov, Yu I. "Effect of conduction electrons on the law of approach to saturation of a metallic ferromagnet with surface pinning of the magnetic moment." Physics of the Solid State 41, no. 4 (April 1999): 582–88. http://dx.doi.org/10.1134/1.1130829.

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12

Denisova, Elena, Lidia Chekanova, Rauf Iskhakov, Sergey Komogortsev, Ivan Nemtsev, Dmitry Velikanov, and Svetlana Mel’nikova. "Magnetic Anisotropy of Co-Nanostructures Embedded in Matrices with Different Pores Size and Morphology." Solid State Phenomena 233-234 (July 2015): 583–86. http://dx.doi.org/10.4028/www.scientific.net/ssp.233-234.583.

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Composite materials with Co (P) particles embedded into pores of silica and track etched polycarbonate membranes were fabricated by an electroless reduction. The magnetic and structural properties of the composite materials are characterized by scanning electron microscopy, X-ray diffraction, and vibrating sample magnetometer. The macroscopic and local magnetic anisotropy of the Co (P) particles electroless deposited in the pores of the polycarbonate membrane and silica is studied. The composite materials with linear pores exhibit uniaxial magnetic anisotropy. The easy axis lies along the Co (P) rods, the shape anisotropy dominates over the intrinsic crystalline anisotropy. Information on local anisotropy field and the grain size was obtained from investigation of approach to saturation magnetization law. The local anisotropy field for all the samples depends on P content. For Co (P) rods the local anisotropy value is also determined by nominal pore sizes. It was found that the investigated Co (P) rods is nanocrystalline. The effects of different pores morphology on the FMR-spectra characteristics are studied.

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13

Aphesteguy, Juan C., Silvia E. Jacobo, Ricardo López Antón, and G. V. Kurlyandskaya. "Structural and Magnetic Characterization of Polyaniline Composite Films." Materials Science Forum 570 (February 2008): 138–43. http://dx.doi.org/10.4028/www.scientific.net/msf.570.138.

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In this work a novel approach for the preparation of Fe3O4/PANI (polyaniline) thin film composite containing magnetic nanoparticles is presented. Magnetite (Fe3O4) nanoparticles have been coated by PANI and the PANI chains have been doped by 10-camphorsulfonic acid (CSA). The doped composite is soluble in common organic solvents. Thin films of composites of polyaniline (PANI) were casted from m-cresol. Several characterization techniques were employed in order to determine composition, structure and magnetic properties of the nanocomposite film (Xray diffraction, transmission electron microscopy, TEM, Scanning electron microscopy, SEM, and optical microscopy). The magnetization data were obtained from M(H) hysteresis loops and zero field cooling – field cooling, ZFC-FC. Magnetic measurements evidence a ferromagnetic behaviour of the obtained composite, at room temperature with saturation magnetization of about 3.4 emu/g and coercivity of 42 Oe. The temperature dependences of the conductivity of the films follows the         = − 1 / 2 ( ) exp T T To o σ σ law, which has been explained within the framework of the onedimensional variable-range-hoping (1D-VRH) model. Application of 1T magnetic field increases the resistivity of the film and the temperature slope dependence.

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14

Das, Soumen, Subhendu K. Panda, Prithiwish Nandi, Subhadra Chaudhuri, Abhishek Pandey, and R. Ranganathan. "Silica Encapsulated Ni Nanoparticles: Variation of Optical and Magnetic Properties with Particle Size." Journal of Nanoscience and Nanotechnology 7, no. 12 (December 1, 2007): 4447–55. http://dx.doi.org/10.1166/jnn.2007.877.

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Ni nanoparticles embedded in SiO2 matrix were prepared by sol–gel process. The molar percentages of Ni were varied from 2 to 20% of total SiO2 present in the matrix. Transmission electron microscope (TEM) images revealed that particle sizes varied from 8.0–15.7 nm at an annealing temperature of 773 K with variation of concentration. The optical absorption spectra revealed that the surface plasmon resonance (SPR) peak in the UV region of the spectrum shifted with the particle diameter (D) from that at 247.3 nm for D = 8.0 nm to 250.7 nm for D = 15.7 nm. In hysteresis loop measurements the magnetizations (M) of the nanocomposites also increased with higher Ni content in the matrix and did not saturate in the measuring limit of the magnetic filed (H) of 4 KOe. The anhysteric curves for different samples were analyzed with the law of approach to saturation (LAS). The zero field cooled (ZFC) and field cooled (FC) magnetization measurements at 50 Oe showed increasing broadening of the ZFC curve with the higher Ni content. To calculate the average blocking temperature (<TB>) a distribution of the blocking temperatures (TB) was assumed to initiate theoretical fittings and it was found to be increasing with the Ni concentration in the matrix.

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15

Zezyulina, Polina A., Dmitry A. Petrov, Konstantin N. Rozanov, Denis A. Vinnik, Sergey S. Maklakov, Vladimir E. Zhivulin, Andrey Yu Starikov, Daria P. Sherstyuk, and Santiranjan Shannigrahi. "Study of the Static and Microwave Magnetic Properties of Nanostructured BaFe12−xTixO19." Coatings 10, no. 8 (August 14, 2020): 789. http://dx.doi.org/10.3390/coatings10080789.

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The effect of Ti substitution on the microwave and magnetostatic properties of nanostructured hexagonal BaFe12−xTixO19 ferrite composites is studied. The microwave permeability is measured in the frequency range of 0.1–22 GHz by a coaxial technique. An analysis of the magnetostatic data is made by the law of approach to saturation. The ferrimagnetic resonance frequencies calculated from the magnetostatic data are consistent with those obtained from the microwave measurements. The natural ferrimagnetic resonance frequencies are located in the frequency range of 15 to 22 GHz, depending on the substitution level x. An increase in the amount of substitution elements results in a low-frequency shift of the ferrimagnetic resonance frequency for samples with x < 1. With x rising from 1 to 2.5, the resonance frequency increases. The results of the study demonstrate that the tailored optimization of the nano-structure of a functional material is a robust tool to fine-tune its microwave magnetic properties. The ferrites under study are promising materials to be applied as functional coatings intended to control electromagnetic interference in microwave devices.

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16

Palka, Ryszard, and Rafal Piotuch. "Usage of FEM for synthesis of dead-beat current controller for permanent magnet synchronous motor." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 38, no. 5 (September 2, 2019): 1386–400. http://dx.doi.org/10.1108/compel-12-2018-0534.

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Purpose Predictive controllers and permanent magnet synchronous motors (PMSMs) got more attention over the past decades thanks to their applicable features. This paper aims to propose and verify a method to design a predictive current controller with consideration of motor characteristics obtained from finite element analysis (FEA). Design/methodology/approach Permanent magnet motor parameters and its maps can be calculated by means of FEA. The model takes into account magnetic saturation and thermal electro-magnetic properties. For each dq current vector and each position, self and mutual inductances are calculated. Based on co-energy method and fundamentals of coordinate transformation dynamic and static, dq inductances are obtained. These are used in classical and modified dead-beat current controller equations. Findings To sustain good features of a controller over higher current regions, it is necessary to adapt control law of a dead-beat controller. After its modification, control quality can be superior over classical solution in high saturation regions. The transient simulations of controller and motor give accurate results. Originality/value Common predictive current controllers use nominal motor parameters in their equations. The authors proposed a modified dead-beat current controller to improve the control quality. There is no need to apply self-tuning algorithms, and implementation of the controller is not much more complicated than that of the classical controller. Designer of a control system can obtain required data from motor designer; in design process of modern machines such data are often already available. The proposed methodology increases control quality of the presented dead-beat controller.

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17

Zubelewicz, A., Q. Guo, E. C. Cutiongco, M. E. Fine, and L. M. Keer. "Micromechanical Method to Predict Fatigue Life of Solder." Journal of Electronic Packaging 112, no. 2 (June 1, 1990): 179–82. http://dx.doi.org/10.1115/1.2904360.

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Fatigue lifetimes of low-tin high-lead and tin-lead eutectic solders under total strain controlled tension-tension tests were studied in this paper. Based on the stress and strain micro-macro correlations, a modified Coffin-Manson law is obtained. The modified lifetime prediction formulas which had been used to predict the fatigue lifetime for low-tin high-lead solder, exhibiting cyclic hardening and then saturation, was found to apply to the eutectic solder, where substantial cyclic softening has been observed. This micromechanically based approach allows one to model the known physical phenomena in solders by modifying the appropriate parameters in the predictive micromechanically based constitutive equations.

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18

Łaszcz, Amadeusz, Mariusz Hasiak, and Jerzy Kaleta. "Temperature Dependence of Anisotropy in Ti and Gd Doped NiMnGa-Based Multifunctional Ferromagnetic Shape Memory Alloys." Materials 13, no. 13 (June 28, 2020): 2906. http://dx.doi.org/10.3390/ma13132906.

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The temperature dependence of magnetocrystalline anisotropy was investigated in detail for the polycrystalline Ni50Mn25Ga25, Ni50Mn25Ga20Ti5 and Ni50Mn25Ga20Gd5 ferromagnetic shape memory alloys in the temperature range of 50–400 K. The effective anisotropy constant was estimated from a series of high field magnetization curves based on the fitting procedure according to the law of approach to magnetic saturation. The low temperature martensitic phase was found to have a significantly higher anisotropy energy in comparison to a high temperature austenitic phase, which was observed through a sudden, distinct drop of anisotropy energy. The calculated values of the effective anisotropy constant were comparable to the results published by other authors. Moreover, the strong influence of chemical composition on the first-order phase transition and the second-order ferromagnetic to the paramagnetic transition was revealed. Finally, the strong coupling between the temperature dependence of the coercive field and the temperature dependence of magnetocrystalline anisotropy was also shown and discussed in the present study.

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19

Nakai, Ikuo, Makio Kurisu, and Shunji Ishio. "Approach to Magnetic Saturation of Amorphous Gd80Si12B8." Journal of the Magnetics Society of Japan 23, no. 1_2 (1999): 561–63. http://dx.doi.org/10.3379/jmsjmag.23.561.

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20

Brodale, G. E., R. A. Fisher, N. E. Philips, and K. Matho. "Approach to magnetic saturation in Mn and Mn." Journal of Magnetism and Magnetic Materials 54-57 (February 1986): 194–96. http://dx.doi.org/10.1016/0304-8853(86)90547-0.

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21

Rollett, A. D., M. L. Storch, E. J. Hilinski, and S. R. Goodman. "Approach to saturation in textured soft magnetic materials." Metallurgical and Materials Transactions A 32, no. 10 (October 2001): 2595–603. http://dx.doi.org/10.1007/s11661-001-0049-2.

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22

Vazquez, M., W. Fernengel, and H. Kronmüller. "Approach to magnetic saturation in rapidly quenched amorphous alloys." Physica Status Solidi (a) 115, no. 2 (October 16, 1989): 547–53. http://dx.doi.org/10.1002/pssa.2211150223.

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23

Carmona, F., V. Madurga, and M. Vázquez. "Approach to magnetic saturation in (Co0.95Fe0.05)75Si15B10 amorphous alloy." Journal of Magnetism and Magnetic Materials 62, no. 1 (November 1986): 68–70. http://dx.doi.org/10.1016/0304-8853(86)90735-3.

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24

Neuweiler, A., B. Hofmann, and H. Kronmüller. "Approach to magnetic saturation in manocrystalline and amorphous Fe73.5Cu1Nb3Si13.5B9." Journal of Magnetism and Magnetic Materials 153, no. 1-2 (February 1996): 28–34. http://dx.doi.org/10.1016/0304-8853(95)00533-1.

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25

Lin, Yue-qiang, Jian Li, Xiao-dong Liu, Ting-zhen Zhang, Bang-cai Wen, Qing-mei Zhang, and Hua Miao. "Saturation Magnetization and Law of Approach to Saturation for Self-formed Ionic Ferrofluids Based on MnFe2O4Nanoparticles." Chinese Journal of Chemical Physics 23, no. 3 (June 2010): 325–30. http://dx.doi.org/10.1088/1674-0068/23/03/325-330.

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26

Herbst, J. F., and F. E. Pinkerton. "Law of approach to saturation for polycrystalline ferromagnets: Remanent initial state." Physical Review B 57, no. 17 (May 1, 1998): 10733–39. http://dx.doi.org/10.1103/physrevb.57.10733.

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27

Hirscher, M., R. Reisser, R. Würschum, H. E. Schaefer, and H. Kronmüller. "Magnetic after-effect and approach to ferromagnetic saturation in nanocrystalline iron." Journal of Magnetism and Magnetic Materials 146, no. 1-2 (April 1995): 117–22. http://dx.doi.org/10.1016/0304-8853(94)01643-7.

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28

Wajnert, Dawid, and Bronislaw Tomczuk. "Nonlinear magnetic equivalent circuit of the hybrid magnetic bearing." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 38, no. 4 (July 1, 2019): 1190–203. http://dx.doi.org/10.1108/compel-10-2018-0423.

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Purpose The purpose of this paper is to create a reliable nonlinear magnetic equivalent circuit (NMEC) of the hybrid magnetic bearing (HMB). Commonly used magnetic equivalent circuits of HMB omit a saturation effect of the magnetic material as well as the leakage and fringing flux. It results in imprecise modelling of the magnetic field distribution. On the other hand, only 3D finite element analysis (FEA) can be used to precisely simulate the magnetic field in this type of the magnetic bearing. The proposed NMEC incorporates the saturation effect of the magnetic material, as well as the leakage and fringing flux. Design/methodology/approach The magnetic equivalent circuit of presented HMB is proposed to obtain a reliable model that ensures short calculation time. Developed NMEC incorporates the phenomena as the saturation effect, as well as the leakage and fringing flux. The reluctance of the air gap that includes the fringing flux was calculated using 3D FEA. Kirchhoffs’ laws were used to create a set of nonlinear equations that were iteratively solved by Broyden’s method. Findings Incorporating into NMEC of the HMB a saturation effect of the magnetic material, as well as the leakage and fringing flux, resulted in the accurate model that was in good agreement with 3 D finite element model and the real object. The developed NMEC offers the calculation time in the range of miliseconds, therefore can be successfully used in the engineering design instead of the FEM. Originality/value Presented NMEC can be considered as a fundamental model that can be successfully used for accurate and fast simulation of the HMB. Proposed NMEC includes considerable factors that decide about the model accuracy such as the saturation effect of the ferromagnetic material and the leakage and fringing flux. The developed NMEC can be used in the optimization procedures and for simulations of dynamic responses.

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29

Vinnik, Denis, Santhoshkumar Mahadevan, and Puneet Sharma. "Magnetic Study on Divalent Ion Substituted Barium Hexaferrites." Defect and Diffusion Forum 410 (August 17, 2021): 714–19. http://dx.doi.org/10.4028/www.scientific.net/ddf.410.714.

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Magnetic properties of Co, Ni and Zn substituted barium hexaferrite (BaM) samples prepared by solid state ceramic method were studied. Saturation magnetisation were found higher for Zn-substituted BaM, whereas, coercivity is higher for Co2+ and Ni2+ ion substituted samples. Anisotropy field for all substituted samples was calculated by the law of approaching saturation. Remanence, squareness and thermomagnetic plot suggest Zn2+ ions restricts the magnetic interaction of various sites in BaM.

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Nakai, Ikuo. "Approach to magnetic saturation in amorphous Gd2T (T = Co, Ni and Cu)." Journal of Magnetism and Magnetic Materials 177-181 (January 1998): 117–18. http://dx.doi.org/10.1016/s0304-8853(97)00487-3.

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31

Christen, Thomas, Pierre Bouzat, Nicolas Pannetier, Nicolas Coquery, Anaïck Moisan, Benjamin Lemasson, Sébastien Thomas, et al. "Tissue Oxygen Saturation Mapping with Magnetic Resonance Imaging." Journal of Cerebral Blood Flow & Metabolism 34, no. 9 (July 9, 2014): 1550–57. http://dx.doi.org/10.1038/jcbfm.2014.116.

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A quantitative estimate of cerebral blood oxygen saturation is of critical importance in the investigation of cerebrovascular disease. While positron emission tomography can map in vivo the oxygen level in blood, it has limited availability and requires ionizing radiation. Magnetic resonance imaging (MRI) offers an alternative through the blood oxygen level-dependent contrast. Here, we describe an in vivo and non-invasive approach to map brain tissue oxygen saturation ( StO2) with high spatial resolution. StO2 obtained with MRI correlated well with results from blood gas analyses for various oxygen and hematocrit challenges. In a stroke model, the hypoxic areas delineated in vivo by MRI spatially matched those observed ex vivo by pimonidazole staining. In a model of diffuse traumatic brain injury, MRI was able to detect even a reduction in StO2 that was too small to be detected by histology. In a F98 glioma model, MRI was able to map oxygenation heterogeneity. Thus, the MRI technique may improve our understanding of the pathophysiology of several brain diseases involving impaired oxygenation.

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Zhang, Hui, Dechang Zeng, and Zhongwu Liu. "The law of approach to saturation in ferromagnets originating from the magnetocrystalline anisotropy." Journal of Magnetism and Magnetic Materials 322, no. 16 (August 2010): 2375–80. http://dx.doi.org/10.1016/j.jmmm.2010.02.040.

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33

Xiong, X. Y., T. R. Finlayson, and B. C. Muddle. "The approach to saturation magnetization of nanocrystalline Fe90Zr7B3alloy." Journal of Physics D: Applied Physics 34, no. 18 (September 5, 2001): 2845–53. http://dx.doi.org/10.1088/0022-3727/34/18/319.

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34

Hernando, A., C. Gómez-Polo, M. El Ghannami, and A. Garcia Escorial. "Approach to saturation and magnetic properties of melt-spun FeCu granular systems." Journal of Magnetism and Magnetic Materials 173, no. 3 (September 1997): 275–86. http://dx.doi.org/10.1016/s0304-8853(97)00184-4.

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35

Aranda, G. R., J. González, and K. Kulakowski. "Approach to the magnetic saturation in nanocrystalline ferromagnets in the random anisotropy model." Journal of Applied Physics 83, no. 11 (June 1998): 6341–43. http://dx.doi.org/10.1063/1.367643.

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36

Utsunomiya, T., H. Nishizawa, and K. Kaneta. "Effect of stress on the law of approach to saturation magnetization in carbon steels." IEEE Transactions on Magnetics 27, no. 3 (May 1991): 3420–25. http://dx.doi.org/10.1109/20.79084.

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37

An, Hongyu, and Weili Lin. "Quantitative Measurements of Cerebral Blood Oxygen Saturation Using Magnetic Resonance Imaging." Journal of Cerebral Blood Flow & Metabolism 20, no. 8 (August 2000): 1225–36. http://dx.doi.org/10.1097/00004647-200008000-00008.

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A quantitative estimate of cerebral blood oxygen saturation is of critical importance in the investigation of cerebrovascular disease because of the fact that it could potentially provide information on tissue viability in vivo. In the current study, a multi-echo gradient and spin echo magnetic resonance imaging sequence was used to acquire images from eight normal volunteer subjects. All images were acquired on a Siemens 1.5T Symphony whole-body scanner (Siemens, Erlangen, Germany). A theoretical signal model, which describes the signal dephasing phenomena in the presence of deoxyhemoglobin, was used for postprocessing of the acquired images and obtaining a quantitative measurement of cerebral blood oxygen saturation in vivo. With a region-of-interest analysis, a mean cerebral blood oxygen saturation of 58.4% ± 1.8% was obtained in the brain parenchyma from all volunteers. It is in excellent agreement with the known cerebral blood oxygen saturation under normal physiologic conditions in humans. Although further studies are needed to overcome some of the confounding factors affecting the estimates of cerebral blood oxygen saturation, these preliminary results are encouraging and should open a new avenue for the noninvasive investigation of cerebral oxygen metabolism under different pathophysiologic conditions using a magnetic resonance imaging approach.

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38

Zhang, Guo Liang, Ting Lei, Fan Yang, and Zhuang Cai. "Neural Network Adaptive Control of Free Floating Space Robot with Actuator Saturation." Applied Mechanics and Materials 590 (June 2014): 380–85. http://dx.doi.org/10.4028/www.scientific.net/amm.590.380.

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This paper proposes an adaptive neural network law for trajectory tracking of a class of free-floating space robot with actuator saturation. Using neural network with global approximation, the control strategy design an on-line real time adaptive learning law to approach the uncertain model and the actuator saturation nonlinearity. The neural network approach errors and outside disturbance can be eliminated by a robust controller.The control strategy need not depend on the model, and can be used under actuator saturation.The control strategy can guarantee the stability of system and the asymptotic convergence of tracking errors based on the Lyapunov’s theory. The simulation results indicate that the proposed strategy can effectively work with actuator saturation.

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39

LACIS, S., E. ZAVICKIS, and G. BOSSIS. "MAGNETIC INTERACTIONS OF CHAINS FORMED BY FERROMAGNETIC SPHERES." International Journal of Modern Physics B 16, no. 17n18 (July 20, 2002): 2307–13. http://dx.doi.org/10.1142/s0217979202012281.

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General properties of sphere-chain and chain-chain structures are analysed for homogeneously magnetized spheres. For field aligned structures the local maximum of the magnetic force is observed at H0/MS ≈ 0.5. The magnetic saturation effects are accounted by the Frölich-Kennelly law. Outlines of the approximate methodology of multi-chain interaction are given together with the test results.

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40

Wright, Nicholas J. "Stellar Magnetic Dynamos and Activity Cycles." Proceedings of the International Astronomical Union 9, S302 (August 2013): 190–93. http://dx.doi.org/10.1017/s1743921314002038.

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AbstractUsing a new uniform sample of 824 solar and late-type stars with measured X-ray luminosities and rotation periods we have studied the relationship between rotation and stellar activity that is believed to be a probe of the underlying stellar dynamo. Using an unbiased subset of the sample we calculate the power law slope of the unsaturated regime of the activity – rotation relationship as LX / Lbol ∝ Roβ, where β = − 2.70 ± 0.13. This is inconsistent with the canonical β = − 2 slope to a confidence of 5σ and argues for an interface-type dynamo. We map out three regimes of coronal emission as a function of stellar mass and age, using the empirical saturation threshold and theoretical super-saturation thresholds. We find that the empirical saturation timescale is well correlated with the time at which stars transition from the rapidly rotating convective sequence to the slowly rotating interface sequence in stellar spin-down models. This may be hinting at fundamental changes in the underlying stellar dynamo or internal structure. We also present the first discovery of an X-ray unsaturated, fully convective M star, which may be hinting at an underlying rotation - activity relationship in fully convective stars hitherto not observed. Finally we present early results from a blind search for stellar X-ray cycles that can place valuable constraints on the underlying ubiquity of solar-like activity cycles.

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Gerami, Adeleh Mokhles, and Mehdi Vaez-Zadeh. "The numerical investigation of magnetic properties of single domain MnP:GaP nanoparticles." Modern Physics Letters B 30, no. 06 (March 7, 2016): 1650065. http://dx.doi.org/10.1142/s0217984916500652.

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The magnetic properties of MnP:GaP nanoparticles are calculated using a statistical mechanical approach and effect of various factors on magnetization of nanoparticles is studied. The calculation is based on solution of localized partition function and evolution of magnetic moment affected by thermal fluctuation and external field is included by solving master equation. Instead of constant magnetic saturation approximation, a temperature dependent magnetic moment saturation is included to improve calculation efficiency for larger nanoparticles. In the present work, the field-cooled and zero-field-cooled (FC/ZFC) magnetization of randomly oriented anisotropy and log-normal volume distributed nanoparticles are calculated.

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Bloch, Katarzyna, and Mateusz Talar. "The Structure and Magnetic Properties of Bulk Amorphous FeCoYB Alloys." Revista de Chimie 70, no. 1 (February 15, 2019): 245–47. http://dx.doi.org/10.37358/rc.19.1.6892.

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In this paper the results of the structure and magnetic studies for bulk amorphous Fe62Co10Y8B20 and Fe64Co10Y6B20 alloys were presented. For the structural investigation was performed by X-ray diffractometry. It was found that investigated samples were amorphous in the as-cast state. Using a vibrating sample magnetometer (VSM) the magnetisation within magnetic fields ranging from 0 to 2T was measured. On the basis of these investigations the saturation magnetization value and the coercive field were determined. Basing on initial magnetization curve analysis in the area of so-called approach to ferromagnetic saturation, the type of structural defects having influence on magnetization in high magnetic fields were determined.

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Chen, Dongyan, Shanqiang Li, and Yujing Shi. "The Practical Stabilization for a Class of Networked Systems with Actuator Saturation and Input Additive Disturbances." Mathematical Problems in Engineering 2012 (2012): 1–19. http://dx.doi.org/10.1155/2012/326876.

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The practical stabilization problem is investigated for a class of linear systems with actuator saturation and input additive disturbances. Firstly, the case of the input additive disturbance being a bounded constant and a variety of different situations of system matrices are studied for the three-dimensional linear system with actuator saturation, respectively. By applying the Riccati equation approach and designing the linear state feedback control law, sufficient conditions are established to guarantee the semiglobal practical stabilization or oscillation for the addressed system. Secondly, for the case of the input additive disturbances being time-varying functions, a more general class of systems with actuator saturation is investigated. By employing the Riccati equation approach, a low-and-high-gain linear state feedback control law is designed to guarantee the global or semiglobal practical stabilization for the closed-loop systems.

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Khlifi, Mohamed Arbi, and Habib Rehaoulia. "General modeling of saturated AC machines for industrial drives." COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering 35, no. 1 (January 4, 2016): 44–63. http://dx.doi.org/10.1108/compel-12-2014-0346.

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Purpose – When magnetic saturation in ac machines is evolved, the theory of main flux saturation in d-q axes remains the best. Because of its simplicity, it is the most used in either motoring or generating mode for synchronous or asynchronous machines. Although, it is considered as a global way of introducing the iron saturation, compared to other methods, today, its fidelity has no contest in predicting complex ac machine operations. For this purpose, the aims of this paper consists of modeling these machines whatever the state-space variables values are taking into account the magnetic saturation. Two unified procedures are proposed. The first one deals with a common approach to establishing a complete and detailed model synthesis in d-q axes. The second also presents a unified approach to introducing magnetic saturation of the iron core in the characteristic equations. The analysis takes the salient pole synchronous machine as a general case of study. Then the approaches are extended to undamped and smooth air gap synchronous machines as well as induction machines. The paper aims to discuss these issues. Design/methodology/approach – The present paper, which is a first part of a work under study dealing with a unified method to derive multiple models of saturated ac machines, is intended to the description of an alternative method and its application for induction and synchronous machines. It mainly consists of the following parts: first, after writing the stator and rotor space vector d-q equations, the number of possible models is immediately discussed. By considering the currents and fluxes as state-space variables, 14 models are obtained for AC induction machine (IM and SM). They are classified into three families, current (three), flux (three) and mixed models (eight). Second, in order to easily introduce the magnetic saturation in the 14 developed models, a method is presented. It consists of just elaborating the model with the winding currents as state variables, then deriving all the other models from it. Third, to emphasize the influence of the presence of magnetic saturation, in each model, each inductance along the d and q axes is written with a fundamental expression which exists with or without saturation and an additional one due purely to saturation. Hence the additional terms can be studied and quantified in an easy way or simply removed when linear case is assumed. Fourth, adopting such strategy to write the different coefficients of the models had led to the definition of common saturation factors. In turn, the definition of common saturation factors had allowed the definition of different groups of models within each family. Fifth, an alternative to evaluate the static and dynamic saturation coefficients is also proposed. It is shown that by proper fitting of the experimental magnetizing curve, all saturation coefficients can be written only in terms of which is simply the magnitudes ratio of the magnetizing flux and current. Sixth, although the theory of the main flux saturation is now admitted, an investigation was carried out on a self-excited induction generator and the build-up of voltage and current phases of a standalone alternator, to prove the equivalence between the all developed models. Findings – The number of models based on the state-space variables choice, of a saturated ac machine, is reviewed. A simple method consisting of elaborating just the winding currents model, with magnetic saturation and deriving all the other models from it, is presented. In this study special interest was particularly focussed on either novel models or existing models cited in the literature but cannot be obtained by other approaches. In all cases, if the differential equations of the machine are formulated in terms of a set of variables other than the winding currents, a noticeable reduction in the size of equations may be obtained and consequently less time computing. The approach seems to be able to derive any possible model whatever the state-space variables and the type of the ac machine and hence can be classified as a general approach. Practical implications – The experiments of synchronous and induction machine transients prove the validity of the method. Originality/value – By suitable choice of state-space characteristic vectors among the fluxes and the currents, a synthesis of AC machine models in d-q axes is established. To introduce magnetic saturation in each model, an approach-based uniquely on the elaboration of the winding currents model is exposed and applied. In addition, the analysis gives a detailed classification of all found models taking into account the state variables nature as well as the cross-coupling coefficient considered as a saturation factor. The study is completed with a simple alternative to evaluate all saturation factors by just calculating the static magnetizing inductance.

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Hernández-Guzmán, Victor M., Jorge Orrante-Sakanassi, and Fortino Mendoza-Mondragón. "Velocity Regulation in Switched Reluctance Motors under Magnetic Flux Saturation Conditions." Mathematical Problems in Engineering 2018 (2018): 1–13. http://dx.doi.org/10.1155/2018/3280468.

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We propose a controller for velocity regulation in switched reluctance motors under magnetic flux saturation conditions. Both hysteresis and proportional control are employed in the internal electric current loops. A classical PI velocity controller is employed in the external loop. Our control law is the simplest one proposed in the literature but provided with a formal stability proof. We prove that the state is bounded having an ultimate bound which can be rendered arbitrarily small by a suitable selection of controller gains. Furthermore, this result stands when starting from any initial condition within a radius which can be arbitrarily enlarged using suitable controller gains. We present a simulation study where even convergence to zero of velocity error is observed as well as a good performance when regulating velocity in the presence of unknown step changes in external torque disturbances.

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46

Zhang, J., M. Fujikura, and T. Sato. "Effects of Surface Etching on the Approach to Magnetic Saturation in Amorphous Fe80.5Si6.5B12C1 Alloy Ribbons." Journal of the Magnetics Society of Japan 20, no. 2 (1996): 413–16. http://dx.doi.org/10.3379/jmsjmag.20.413.

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47

Keshoju, K., X. Gu, A. T. Kumar, and L. Sun. "Magnetic Nanostructures Fabricated by Electrochemical Synthesis." Solid State Phenomena 121-123 (March 2007): 839–42. http://dx.doi.org/10.4028/www.scientific.net/ssp.121-123.839.

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Electrochemical processing is a cost effective and low-temperature approach suitable for the fabrication of certain unique nanostructures that are difficult to obtain by other methods. Here we report on the synthesis of nanowires and nanoporous structures with the intention to control the magnetic properties of conventional materials. Nanowires with variable sizes (diameter 15 nm - microns, and length up to 100 microns) have been fabricated by template assisted electrodeposition. Utilizing a combined alloy electrodeposition and electrochemical dealloying approach, porous nanostructures with controlled pore size and porosity have also been synthesized. Magnetization, Curie temperature, coercivity, saturation field, and remnant magnetization of these magnetic nanostructures exhibit much wider tunibility compared to bulk and thin film samples.

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48

Pang, Xianhai, Haijun Zhang, Shuhong Wang, and Hao Jing. "Flux density calculation of air gap for switched reluctance motor considering magnetic saturation based on sub-domain method." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 37, no. 6 (November 5, 2018): 2081–92. http://dx.doi.org/10.1108/compel-06-2017-0226.

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Purpose The purpose of this paper is to study the saturation and nonlinear performance of magnetic field in the air gap of switched reluctance motor (SRM). Design/methodology/approach The analytical method of sub-domain combined with the saturation compensation method is used to determine the nonlinear distribution of air gap magnetic field in SRM. Also, the resolutions of the two-dimensional (2D) Laplace’s equation and Poisson’s equation in polar coordinates are used to obtain the simplified expression of magnetic flux density. Findings For verifying the effectiveness of analytical model, the results are compared with those obtained from the 2D finite element method (FEM). The influence of magnetic saturation is taken into account by associating the sub-domain analysis result with the nonlinear B-H properties of stator and rotor iron. The magnetic flux density in radial and tangential direction considering the saturation effect may be calculated accurately. It can be seen that one can easily determine the linear analytical results accurately, whereas it is difficult to determine the magnetic flux density with saturation influence; especially at some local positions, there is a larger difference between analytical and FE model due to the complex boundary conditions. Practical implications This paper presents the development and optimization design of high-performance SRM. Originality/value The magnetic saturation may be taken into account for the SRM and analytical models support to simulated system performance.

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Pati, Avadh, and Richa Negi. "Design of backstepping control with CNN-based compensator for active magnetic bearing system subjected to input voltage saturation." World Journal of Engineering 15, no. 6 (December 3, 2018): 678–87. http://dx.doi.org/10.1108/wje-03-2017-0068.

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Purpose The stability and input voltage saturation is a common problem associated with an active magnetic bearing (AMB) system. The purpose of this paper is to design a control scheme that stabilizes the single degree of freedom AMB system and also tackle the problem of input voltage saturation in the AMB system. Design/methodology/approach The proposed control technique is a combination of two separate control schemes. First, the Backstepping control scheme is designed to stabilize and control the AMB system and then Chebyshev neural network (CNN)-based compensator is designed to tackle the input voltage saturation when the system control action is saturated. Findings The mathematical and simulation results are presented to validate the effectiveness of proposed methodology for single-degree freedom AMB system. Originality/value This paper introduces a CNN-based compensator with Backstepping control strategy to stabilize and tackle the problem of input voltage saturation in the 1-DOF AMB systems.

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50

Polak, Ch, Roland Grössinger, T. Holubar, Marcelo Knobel, Reiko Sato Turtelli, and H. Sassik. "Determination of the Quenched-In State of Amorphous Ribbons Applying the Law of Approach to Saturation." Key Engineering Materials 81-83 (January 1993): 239–44. http://dx.doi.org/10.4028/www.scientific.net/kem.81-83.239.

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