Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Physica B+C 86-88 (1977), S. 803-804 
    ISSN: 0378-4363
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Magnetic power losses have been experimentally investigated and theoretically predicted over a range of frequencies (direct current—1.5 kHz) and peak inductions (0.5–1.5 T) in 1-mm-thick FeSi 2 wt. % laminations. The direct current hysteresis properties of the system are described by the Preisach model, with the Preisach distribution function reconstructed from the measurement of the recoil magnetization curve (Bp=1.7 T). On this basis, the time behavior of the magnetic induction vs frequency at different lamination depths is calculated by a finite element method numerical solution of Maxwell equations, which takes explicitly into account the Preisach model hysteretic B(H) relationship. The computed loop shapes are, in general, in good agreement with the measured ones. The power loss dependence on frequency is predicted and experimentally found to change from a ∼f3/2 to a ∼f2 law with increasing peak induction. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 6615-6617 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Rotational and alternating hysteresis losses have been investigated in theory and experiment in nonoriented soft magnetic laminations. Attention has been focused on the dependence of energy loss on peak magnetization Ip. The experiments, performed in a wide induction range (∼2×10−4 T≤Ip≤∼1.6 T), show that the ratio between rotational and alternating energy losses Whr/Wha is a monotonically decreasing function of Ip. A quantitative theoretical investigation is carried out through modeling of the magnetization process under rotating field and its relation to processes under alternating field. Three basic mechanisms of magnetization rotation are considered: linear combination of unidirectional hysteresis loops at low inductions (Rayleigh region), cyclic rearrangement of magnetic domains between different easy directions at intermediate inductions, and coherent spin rotation toward the approach to magnetic saturation. The ensuing predicted behavior of Whr/Wha is found to be in good agreement with the experiments performed in nonoriented low carbon steel and 3% FeSi laminations.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 5371-5379 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A new model is presented which quantitatively describes the reversible magnetization process and its contribution to the magnetization curve in soft amorphous ribbons. It takes into account the role of the coherent moment rotations, through analysis of the orientation distribution of the magnetization vector Is in the sample cross section and its evolution with the applied field. Such analysis relies on the assumption, dictated by magnetic domains observations, of a spatial distribution of local anisotropies, whose intensity and direction are mainly determined by the long-range random stresses quenched in during the process of rapid solidification. The reversible I(H) curve is obtained by integrating the local magnetization contributions with respect to their angular distribution, according to a minimum energy condition involving the Zeeman, the local anisotropy, and the macroscopic anisotropy terms. It is shown that a relatively simple analytical expression for I(H) can be worked out. The model is applied to experimental I(H) recoil curves, which have been determined as a function of the stress-induced anisotropy in positive magnetostriction (Fe81B14Si3C2) and negative magnetostriction (Co80B10Si10) amorphous ribbons. It is shown that the shape of I(H) and its evolution with the applied tensile/compressive stress are correctly predicted by the theory.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A newly developed digital feedback wattmeter, allowing power loss measurements in soft laminations under generic induction waveform is presented. The system is intrinsically free of auto-oscillations, typical drawback of analog feedback circuits, and can therefore be operated in a wide frequency range (0.5 Hz–100 kHz). Loss measurements performed by this setup under sinusoidal and distorted induction waveforms on Co based amorphous ribbons are reported. It is shown that the classical approximation to the prediction of power losses under distorted induction largely fails to account for the experimental results. A novel theoretical approach, based on the statistical theory of losses, is discussed and successfully applied to the experiments. In particular, it is shown that knowledge of the loss components under sinusoidal induction at a given magnetizing frequency permits one to make an accurate prediction of the effect of distortion at that frequency as well as other ones. Illustrative applications at 1 kHz and 100 kHz are reported.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 4045-4047 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The hysteresis loop and loss properties of near-zero-magnetostrictive amorphous ribbons have been investigated as a function of the induced macroscopic magnetic anisotropy Ku from dc to 10 kHz. It is found that, following the evolution of Ku, imposed by means of sequential field annealings along the longitudinal (LD) and transverse (TD) directions, the hysteresis loop shape and area and the frequency dependence of energy losses suffer dramatic changes, dictated by the value of Ku and the local distributed anisotropies K. On passing from longitudinal to transverse macroscopic easy axis, coherent spin rotations come into play and, in association with the domain wall displacements, eventually provide a net magnetization reversal along both LD and TD. The hysteresis loss component Wh correspondingly increases and the energy loss at high frequencies decreases. It is concluded that: (1) optimal quasi-static magnetic behavior requires relatively high and positive Ku values (〉50–100 J/m3), with longitudinal plane rigid walls and (2) the best high frequency properties are attained for Ku∼0, where flexible walls and complex domain patterns are created. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Dynamic hysteresis loop shapes and magnetic power losses are studied in nonoriented Fe-Si laminations exhibiting significant excess losses. Measurements are carried out under controlled sinusoidal induction in the frequency range from 1 Hz to 1.6 kHz, at various peak inductions from 0.25 to 1.5 T. Excess losses are found to obey a f3/2 law up to frequencies of 200–400 Hz, depending on peak induction. Beyond this limit, definite deviations are observed, due to eddy current shielding. Detailed information on the flux and field distribution in this high frequency regime is obtained by finite element solutions of Maxwell equations employing the dynamic Preisach model to describe quasi-static hysteresis and dynamic wall processes. The agreement between theoretical predictions and measurements is discussed. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 5020-5022 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The role of stress-induced anisotropy on magnetic power losses has been investigated in FeBSiC amorphous ribbons, in the "as-quenched'' state and after annealing. Loss separation has been accomplished up to 400 Hz, under a wide range of applied tensile stresses (3.5 MPa≤σ≤300 MPa). It is found that, by increasing σ, the hysteresis loss component Wh is initially decreased and passes through a minimum around a critical stress σ0. Correspondingly, rearrangement of the maze domain structure associated with the unstressed state occurs and a longitudinally oriented pattern sets in. The dynamic loss exhibits a somewhat opposite trend, as it tends to monotonically increase with σ, thus attenuating the overall benefits of tensile stressing. Insight on the physical mechanisms responsible for these phenomena is obtained by measuring, at different stress levels, Wh versus temperature (20 °C≤T≤280 °C). Topological rearrangements of the domain structure and interaction of the Bloch walls with localized stress fluctuations are envisaged, in association with roughness of the ribbon surface, as the main sources of coercivity and losses. As to the relaxation aftereffect, this is shown to produce additional loss under fairly restricted conditions of temperature and magnetization rate.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 5930-5932 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The magnetization process has been investigated in nonoriented SiFe alloys over a wide induction range, from about 10−4 T to technical saturation. Special attention has been devoted to the role of grain size 〈s〉. The low-field behavior of the initial magnetization curve is characterized by a number of remarkable features: (1) the permeability μr tends, in the limit of vanishing applied field H, to a constant value, independent of 〈s〉; (2) the increase of μr with H exhibits a nonlinear behavior, in contrast with the Rayleigh law; and (3) the larger the grain size, the steeper the rise of μr with H. This effect is attributed to an increased ease of propagation of locally induced magnetization reversals at larger 〈s〉 values. Experiments put in evidence a correlation between μr and the length of propagation λ, which is found to vary as μ1/2r. However, at high inductions (above about 1 T), larger grains imply a reduction of permeability, due to the growth of unfavorable crystallographic textures. Grain size also affects power losses to a large extent. Measurements performed at 1 and 1.5 T show that the hysteresis component Ph and the excess eddy component Pe, respectively, vary as 1/(square root of)〈s〉 and (square root of)〈s〉 in the investigated range 45 μm≤〈s〉≤360 μm.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 5574-5576 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We investigate the role of grain size in the magnetization process of nonoriented 1.7% Al 1.9% Si Fe steels by measuring the power spectrum and the amplitude probability distribution of the Barkhausen noise. Experiments refer to single strips of variable grain size (0.03 mm〈s〈0.27 mm) and are made under controlled values of magnetization rate and permeability. We also study the propagation along the specimen of individual Barkhausen reversals at very low magnetization rates (3×10−4 T s−1). The data are interpreted in the frame of a theory recently proposed by the authors, which connects the Barkhausen effect to the statistical properties of the random local coercive field experienced by a moving domain wall.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...