Volume low-frequency dispersion in a semi-insulating system

1988 ◽  
Vol 23 (2) ◽  
pp. 209-213 ◽  
Author(s):  
A.K. Jonscher ◽  
L. Levesque
Keyword(s):  
Low Frequency ◽  
Frequency Dispersion

Magnetic Permeability and Relaxation Frequency in High Frequency Magnetic Materials.

2001 ◽  
Vol 674 ◽  
Author(s):  
M.I. Rosales ◽  
H. Montiel ◽  
R. Valenzuela
Keyword(s):  
High Frequency ◽  
Domain Walls ◽  
Magnetocrystalline Anisotropy ◽  
Low Frequency ◽  
Frequency Dispersion ◽  
Anisotropy Constant ◽  
Relaxation Frequency ◽  
Resonance Relaxation ◽  
Frequency Behavior

ABSTRACTAn investigation of the frequency behavior of polycrystalline ferrites is presented. It is shown that the low frequency dispersion (f < 10 MHz) of permeability is associated with the bulging of pinned domain walls, and has a mixed resonance-relaxation character, closer to the latter. It is also shown that there is a linear relationship between the magnetocrystalline anisotropy constant, K1, and the relaxation frequency. The slope of this correlation depends on the grain size. Such a relationship could allow the determination of this basic parameter from polycrystalline samples.

Theory of the ferroelectric Mott-Hubbard phase in organic conductors

2002 ◽  
Vol 12 (9) ◽  
pp. 149-152
Author(s):  
S. Brazovskii
Keyword(s):  
Activation Energy ◽  
Phase Transitions ◽  
Low Frequency ◽  
Frequency Dispersion ◽  
Organic Conductors ◽  
The State ◽  
Charge Disproportionation ◽  
Subsequent Phase

Recently the ferroelectric FE anomaly (Nad, Monceau, et al.) followed by the charge disproportionation CD (Brown, et al) have been discovered in ($TMTTF)_2X$ compounds. A theory of the combined Mott-Hubbard state describes both effects by interference of the build-in nonequivalence of bonds and the spontaneous one of sites. The state gives rise to three types of solitons: $\pi -$ solitons (holons) are observed via the activation energy A in conductivity G; noninteger $\alpha -$ solitons provide the frequency dispersion of the FE response; combined spin-charge solitons determine $G(T)$ below subsequent phase transitions. The optical edge lies well below the conductivity gap 2A; the critical FE mode coexists with a combined electron-phonon resonance and a phonon antiresonance. The CD and the FE can exists hiddenly even in the Se subfamily giving rise to the unexplained yet low frequency optical peak, the enhanced pseudogap and traces of phonons activation.

scholarly journals Bioimpedance Analysis of L929 and HaCaT Cells in Low Frequency Range

2018 ◽  
Vol 4 (1) ◽  
pp. 115-118 ◽  
Author(s):  
Viviane S. Teixeira ◽  
Jan-Patrick Kalckhoff ◽  
Wolfgang Krautschneider ◽  
Dietmar Schroeder
Keyword(s):  
Low Frequency ◽  
Steel Corrosion ◽  
Frequency Dispersion ◽  
Human Keratinocytes ◽  
Cell Types ◽  
Hacat Cells ◽  
Frequency Range ◽  
Corrosion Resistant ◽  
L929 Mouse

AbstractIn this work, Bioimpedance Spectroscopy (BIS) is used to study fluids and cell solutions. A n ew fourelectrode- terminal (4T) chamber using 3D printing and stainless steel corrosion resistant V4A was designed to measure the impedance of live cell solutions at the frequency range 0.1Hz- 1MHz. At f < 1kHz the double layer (DL) that builds at electrode’s surface raises the impedance substantially preventing the observation of the real impedance of the cells. The new 4T design circumvents the DL, is more robust and cheap, and allows for the repeatability of the results. Experiments were performed in vitro with two cell lines, L929 (mouse fibroblasts) and HaCaT (human keratinocytes). Results show that it is possible to distinguish between the two cell types by means of its BIS measurements in the new setup. Also, a low-frequency dispersion (α-dispersion) was observed in HaCaT cells solution, but not in L929. Furthermore, a potentiostat circuit model was developed in LTSpice to simulate the hardware setup and two different circuit models were used to fit cell’s data.

Low-frequency dispersion characteristics of GaN HFETs

1995 ◽  
Vol 31 (22) ◽  
pp. 1951-1952 ◽  
Author(s):  
W. Kruppa ◽  
K. Doverspike ◽  
S.C. Binari
Keyword(s):  
Low Frequency ◽  
Frequency Dispersion ◽  
Dispersion Characteristics

scholarly journals Dispersive changes in magnetic background noise polarization at 0.1 to 6Hz during sunset and sunrise at L=1.3

2004 ◽  
Vol 22 (6) ◽  
pp. 1989-2000 ◽  
Author(s):  
T. Bösinger ◽  
S. L. Shalimov
Keyword(s):  
Background Noise ◽  
Azimuthal Angle ◽  
Low Frequency ◽  
Frequency Dispersion ◽  
Major Axis ◽  
Resonance Structure ◽  
Frequency Range ◽  
Ionosphere Model ◽  
F Region ◽  
E Region

Abstract. Polarization properties of the magnetic background noise (MBN) and the spectral resonance structure (SRS) of the ionospheric Alfvén resonator (IAR) below the first Schumann resonance but above 0.1 Hz are measured by a sensitive pulsation magnetometer at the island of Crete (L=1.3) and analyzed using the existing SRS theory by Belyaev et al. (1989b). The focus of the paper is on the systematic changes in the MBN and SRS properties associated with the transition from a sunlit to a dark ionosphere (sunset) and vice versa (sunrise). We are able to pinpoint in observations an E-region and F-region terminator effect and to simulate it by means of a simple ionosphere model, implying the formalism given by Belyaev et al. (1989b). The E-region terminator effect is associated with an apparent control for the SRS presence or absence with no clear frequency dispersion in polarization properties, whereas the F-region terminator effect exhibits strong frequency dispersion, especially in the low frequency range. This yields a change in the ellipticity of MBN, starting as early as 2 to 3h ahead of the "zero-line" of the terminator. In a 24h presentation of the ellipticity versus frequency and time, the sunrise/sunset effect produces a sharp, dispersive boundary between night and day (day and night). Only inside this boundary, during the night hours, is SRS observed, at times accompanied by a large quasi-periodic long period modulation in the azimuthal angle of the major axis of the polarization ellipse. Attention is also paid to peculiarities in the low frequency range (~0.1Hz), where especially large changes in the polarization properties occur in association with the passage of the terminator. The F-region effect is very distinct and well reproduced by our simple model. Changes in the azimuth associated with the E-region terminator effect are of the order of 20&amp;deg.

OUTPUT IMPEDANCE FREQUENCY DISPERSION AND LOW FREQUENCY NOISE IN GaAs MESFETs

1988 ◽  
Vol 49 (C4) ◽  
pp. C4-201-C4-204 ◽  
Author(s):  
D. GITLIN ◽  
C. R. VISWANATHAN ◽  
A. A. ABIDI
Keyword(s):  
Low Frequency ◽  
Frequency Dispersion ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Output Impedance

scholarly journals The Dispersion of Strong Field Dielectric Permittivity in (1-x)PMN-(x)PT Ceramics

2011 ◽  
Vol 56 (4) ◽  
pp. 1199-1203 ◽  
Author(s):  
P. Wawrzała ◽  
R. Skulski
Keyword(s):  
Dielectric Permittivity ◽  
Hysteresis Loop ◽  
Electric Fields ◽  
Strong Field ◽  
Low Frequency ◽  
Frequency Dispersion ◽  
Strong Electric Fields

The Dispersion of Strong Field Dielectric Permittivity in (1-x)PMN-(x)PT CeramicsWe propose the method of analysis of the dielectric permittivity measured in very strong electric fields. The method is based on the numeric calculations of derivative fromP - Ehysteresis loop. Such investigations have been performed for PMN-PT ceramics at various temperatures and frequencies. As a result we analyze the low frequency dispersion of the strong field dielectric permittivity.

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