Instrument for measuring phase and amplitude of harmonics in the ultralow-frequency range

1976 ◽  
Vol 19 (11) ◽  
pp. 1650-1654
Author(s):  
V. D. Stashuk ◽  
V. A. Panchul
Keyword(s):  
Frequency Range ◽  
Ultralow Frequency

scholarly journals Problems of the Pc1 magnetospheric wave theory. A review

2019 ◽  
Vol 5 (3) ◽  
pp. 102-109
Author(s):  
Анатолий Гульельми ◽  
Anatol Guglielmi ◽  
Александр Потапов ◽  
Alexander Potapov
Keyword(s):  
Standard Model ◽  
Electromagnetic Waves ◽  
Wave Theory ◽  
Space Physics ◽  
Frequency Range ◽  
Open Problems ◽  
Ultralow Frequency ◽  
Near Earth Space ◽  
The Standard Model ◽  
New Ideas

The Pc1 ultralow-frequency electromagnetic waves (frequency range 0.2–5 Hz), also known as pearl necklace, are a unique phenomenon in near-Earth space physics. Many properties of pearls remain a mystery, despite the research of prominent cosmophysicists for more than half a century. In the proposed review, we briefly outline the main points of the so-called standard model, which is widely used to interpret Pc1. Next, we focus on the criticism of the standard model and on the identification of open problems in the Pc1 theory. The general conclusion is that it is necessary to develop new ideas outside the framework of the standard model in order to understand the processes of excitation and propagation of Pc1 waves in Earth’s magnetosphere.

Frequency up-converted piezoelectric energy harvester for ultralow-frequency and ultrawide-frequency-range operation

2018 ◽  
Vol 112 (16) ◽  
pp. 163902 ◽  
Author(s):  
Xiyang Zhang ◽  
Shiqiao Gao ◽  
Dongguang Li ◽  
Lei Jin ◽  
Qinghe Wu ◽  
...  
Keyword(s):  
Energy Harvester ◽  
Frequency Range ◽  
Ultralow Frequency ◽  
Piezoelectric Energy

scholarly journals Problems of the Pc1 magnetospheric wave theory. A review

2019 ◽  
Vol 5 (3) ◽  
pp. 87-92 ◽  
Author(s):  
Анатолий Гульельми ◽  
Anatol Guglielmi ◽  
Александр Потапов ◽  
Alexander Potapov
Keyword(s):  
Standard Model ◽  
Electromagnetic Waves ◽  
Wave Theory ◽  
Space Physics ◽  
Frequency Range ◽  
Open Problems ◽  
Ultralow Frequency ◽  
Near Earth Space ◽  
The Standard Model ◽  
New Ideas

The Pc1 ultralow-frequency electromagnetic waves (frequency range 0.2–5 Hz), also known as pearl necklace, are a unique phenomenon in near-Earth space physics. Many properties of pearls remain a mystery, despite the research of prominent cosmophysicists for more than half a century. In the proposed review, we briefly outline the main points of the so-called standard model, which is widely used to interpret Pc1. Next, we focus on the criticism of the standard model and on the identification of open problems in the Pc1 theory. The general conclusion is that it is necessary to develop new ideas outside the framework of the standard model in order to understand the processes of excitation and propagation of Pc1 waves in Earth’s magnetosphere.

scholarly journals Ultralow frequency dielectric dispersion in PZT + PFS ferroelectric ceramic

2014 ◽  
Vol 04 (03) ◽  
pp. 1450021 ◽  
Author(s):  
Andrzej Osak
Keyword(s):  
Time Domain ◽  
Room Temperature ◽  
Fractional Power ◽  
Ferroelectric Ceramic ◽  
Dielectric Dispersion ◽  
Frequency Range ◽  
Depolarization Current ◽  
Ultralow Frequency ◽  
Temperature Range ◽  
The Time Domain

The depolarization decaying currents were measured for the PZT compound with morphotropic composition modified by the Fe 1/3 Sb 2/3 cations, i.e., Pb [( Fe 1/3 Sb 2/3)x Ti y Zr z] O 3 with x + y + z = 1, x = 0.1, y = 0.44 (morphotropic boundary) and y = 0.47. The measurements were performed at room temperature and a few temperatures above (up to 473 K), as well as at a few lower temperatures (down to 77 K). The samples were poling at fields 0.02 kV/cm and 0.2 kV/cm at higher and lower temperatures, respectively. In the high temperature range, the time dependence depolarization current follows the fractional power law with two different exponents (n < 1 and m > 1), while in the low temperature range with a single exponent (n). The appropriate procedure has been used to transform the results obtained in the time domain into the frequency domain in order to calculate real and imaginary parts of the dielectric permittivity in the frequency range 5 × 10-5-0.1 Hz. The possible dielectric relaxation mechanisms have been discussed.

Density-based discrimination of protein and RNA in the ribosome

1992 ◽  
Vol 50 (1) ◽  
pp. 464-465
Author(s):  
Joachim Frank
Keyword(s):  
Transfer Function ◽  
Spatial Frequency ◽  
Three Dimensional ◽  
Wiener Filter ◽  
Dark Field Image ◽  
Dark Field ◽  
Frequency Range ◽  
Bright Field ◽  
Contrast Transfer Function ◽  
Pass Filter

Cryo-electron microscopy combined with single-particle reconstruction techniques has allowed us to form a three-dimensional image of the Escherichia coli ribosome.In the interior, we observe strong density variations which may be attributed to the difference in scattering density between ribosomal RNA (rRNA) and protein. This identification can only be tentative, and lacks quantitation at this stage, because of the nature of image formation by bright field phase contrast. Apart from limiting the resolution, the contrast transfer function acts as a high-pass filter which produces edge enhancement effects that can explain at least part of the observed variations. As a step toward a more quantitative analysis, it is necessary to correct the transfer function in the low-spatial-frequency range. Unfortunately, it is in that range where Fourier components unrelated to elastic bright-field imaging are found, and a Wiener-filter type restoration would lead to incorrect results. Depending upon the thickness of the ice layer, a varying contribution to the Fourier components in the low-spatial-frequency range originates from an “inelastic dark field” image. The only prospect to obtain quantitatively interpretable images (i.e., which would allow discrimination between rRNA and protein by application of a density threshold set to the average RNA scattering density may therefore lie in the use of energy-filtering microscopes.

Evaluation of Special Hearing Aids for Deaf Children

1971 ◽  
Vol 36 (4) ◽  
pp. 527-537 ◽  
Author(s):  
Norman P. Erber
Keyword(s):  
Hearing Aids ◽  
High Frequency ◽  
Hearing Aid ◽  
Low Frequency ◽  
Acoustic Stimulation ◽  
Deaf Children ◽  
Frequency Range ◽  
Frequency Limit ◽  
Unpublished Studies ◽  
Published Research

Two types of special hearing aid have been developed recently to improve the reception of speech by profoundly deaf children. In a different way, each special system provides greater low-frequency acoustic stimulation to deaf ears than does a conventional hearing aid. One of the devices extends the low-frequency limit of amplification; the other shifts high-frequency energy to a lower frequency range. In general, previous evaluations of these special hearing aids have obtained inconsistent or inconclusive results. This paper reviews most of the published research on the use of special hearing aids by deaf children, summarizes several unpublished studies, and suggests a set of guidelines for future evaluations of special and conventional amplification systems.

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