scholarly journals High‐frequency measurement of dielectric permittivity and antimicrobial properties of polyaniline and graphite oxide nanocomposites

2021 ◽  
Author(s):  
Shubha L.N. ◽  
ChandraBabu Putta
Keyword(s):  
Dielectric Permittivity ◽  
Graphite Oxide ◽  
High Frequency ◽  
Antimicrobial Properties ◽  
Frequency Measurement

scholarly journals Sintering, Microstructure, and Dielectric Properties of Copper Borates for High Frequency LTCC Applications

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4017
Author(s):  
Dorota Szwagierczak ◽  
Beata Synkiewicz-Musialska ◽  
Jan Kulawik ◽  
Norbert Pałka
Keyword(s):  
Dielectric Properties ◽  
Dielectric Permittivity ◽  
High Frequency ◽  
Ceramic Materials ◽  
Sintering Behavior ◽  
Terahertz Time Domain Spectroscopy ◽  
Very High Frequency ◽  
X Ray ◽  
Low Dielectric ◽  
Very High

New ceramic materials based on two copper borates, CuB2O4 and Cu3B2O6, were prepared via solid state synthesis and sintering, and characterized as promising candidates for low dielectric permittivity substrates for very high frequency circuits. The sintering behavior, composition, microstructure, and dielectric properties of the ceramics were investigated using a heating microscope, X-ray diffractometry, scanning electron microscopy, energy dispersive spectroscopy, and terahertz time domain spectroscopy. The studies revealed a low dielectric permittivity of 5.1–6.7 and low dielectric loss in the frequency range 0.14–0.7 THz. The copper borate-based materials, owing to a low sintering temperature of 900–960 °C, are suitable for LTCC (low temperature cofired ceramics) applications.

scholarly journals Gaining Insights in Loading Events for Wind Turbine Drivetrain Prognostics

2020 ◽  
Author(s):  
Pieter-Jan Daems ◽  
Y. Guo ◽  
S. Sheng ◽  
C. Peeters ◽  
P. Guillaume ◽  
...  
Keyword(s):  
High Frequency ◽  
Failure Modes ◽  
Measurement Data ◽  
Wind Farms ◽  
Frequency Measurement ◽  
Operating Conditions ◽  
Failure Data ◽  
The World ◽  
Operations And Maintenance ◽  
History Of

Abstract Wind energy is one of the largest sources of renewable energy in the world. To further reduce the operations and maintenance (O&M) costs of wind farms, it is essential to be able to accurately pinpoint the root causes of different failure modes of interest. An example of such a failure mode that is not yet fully understood is white etching cracks (WEC). This can cause the bearing lifetime to be reduced to 5–10% of its design value. Multiple hypotheses are available in literature concerning its cause. To be able to validate or disprove these hypotheses, it is essential to have historic high-frequency measurement data (e.g., load and vibration levels) available. In time, this will allow linking to the history of the turbine operating data with failure data. This paper discusses the dynamic loading on the turbine during certain events (e.g., emergency stops, run-ups, and during normal operating conditions). By combining the number of specific events that each turbine has seen with the severity of each event, it becomes possible to assess which turbines are most likely to show signs of damage.

Shallow subsurface mapping by electromagnetic sounding in the 300 kHz to 30 MHz range: Model studies and prototype system assessment

Geophysics ◽  
1994 ◽  
Vol 59 (8) ◽  
pp. 1201-1210 ◽  
Author(s):  
Duff C. Stewart ◽  
Walter L. Anderson ◽  
Thomas P. Grover ◽  
Victor F. Labson
Keyword(s):  
Dielectric Permittivity ◽  
High Frequency ◽  
Low Frequency ◽  
Computer Programs ◽  
Thin Layers ◽  
Depth Range ◽  
Frequency Range ◽  
Model Studies ◽  
New Instrument ◽  
Displacement Currents

A new instrument designed for frequency‐domain sounding in the depth range 0–10 m uses short coil spacings of 5 m or less and a frequency range of 300 kHz to 30 MHz. In this frequency range, both conduction currents (controlled by electrical conductivity) and displacement currents (controlled by dielectric permittivity) are important. Several surface electromagnetic survey systems commonly used (generally with frequencies less than 60 kHz) are unsuitable for detailed investigation of the upper 5 m of the earth or, as with ground‐penetrating radar, are most effective in relatively resistive environments. Most computer programs written for interpretation of data acquired with the low‐frequency systems neglect displacement currents, and are thus unsuited for accurate high‐frequency modeling and interpretation. New forward and inverse computer programs are described that include displacement currents in layered‐earth models. The computer programs and this new instrument are used to evaluate the effectiveness of shallow high‐frequency soundings based on measurement of the tilt angle and the ellipticity of magnetic fields. Forward model studies indicate that the influence of dielectric permittivity provides the ability to resolve thin layers, especially if the instrument frequency range can be extended to 50 MHz. Field tests of the instrument and the inversion program demonstrate the potential for detailed shallow mapping wherein both the resistivity and the dielectric permittivity of layers are determined. Although data collection and inversion are much slower than for low‐frequency methods, additional information is obtained inasmuch as there usually is a permittivity contrast as well as a resistivity contrast at boundaries between different materials. Determination of dielectric permittivity is particularly important for hazardous waste site characterization because the presence of some contaminants may have little effect on observed resistivity but a large effect on observed permittivity.

scholarly journals High-Frequency Measurement of Ultrasound Using Flexural Ultrasonic Transducers

2018 ◽  
Vol 18 (13) ◽  
pp. 5238-5244 ◽  
Author(s):  
Andrew Feeney ◽  
Lei Kang ◽  
Steve Dixon
Keyword(s):  
High Frequency ◽  
Frequency Measurement ◽  
Ultrasonic Transducers

scholarly journals What do we know about Indonesian tropical lakes? Insights from high frequency measurement

2018 ◽  
Vol 118 ◽  
pp. 012024
Author(s):  
Arianto Budi Santoso ◽  
Endra Triwisesa ◽  
Muh. Fakhrudin ◽  
Eko Harsono ◽  
Hadiid Agita Rustini
Keyword(s):  
High Frequency ◽  
Frequency Measurement ◽  
Tropical Lakes

High-frequency measurement techniques for magnetic cores

1990 ◽  
Vol 5 (1) ◽  
pp. 41-53 ◽  
Author(s):  
V.J. Thottuvelil ◽  
T.G. Wilson ◽  
H.A. Owen
Keyword(s):  
High Frequency ◽  
Measurement Techniques ◽  
Frequency Measurement ◽  
Magnetic Cores

High-frequency dielectric permittivity of water and its components

2011 ◽  
Vol 85 (7) ◽  
pp. 1113-1118 ◽  
Author(s):  
N. M. Putintsev ◽  
D. N. Putintsev
Keyword(s):  
Dielectric Permittivity ◽  
High Frequency
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