scholarly journals Planar waveguide hybrids for very high power RF

2003 ◽  
Author(s):  
C.D. Nantista ◽  
W.R. Fowkes ◽  
N.M. Kroll ◽  
S.G. Tantawi
Keyword(s):  
High Power ◽  
Planar Waveguide ◽  
Very High

scholarly journals I. On an aplanatic searcher, and its effects in improving high-power definition in the microscope

1870 ◽  
Vol 18 (114-122) ◽  
pp. 327-330
Keyword(s):  
High Power ◽  
Microscopic Object ◽  
Very High

The Aplanatic Searcher is intended to improve the penetration, amplify magnifying-power, intensify definition, and raise the objective somewhat further from its dangerous proximity to the delicate covering-glass indispensable to the observation of objects under very high powers. The inquiry into the practicability of improving the performance of microscopic object-glasses of the very finest known quality was suggesed by an accidental resolution in 1862 of the Podura markings into black beads. This led to a search for the cause of defective definition, it any existed. A variety of first-class objectives, from the 1/16 to the 1/4, failed to show the beading, although most carefully constructed by Messrs. Powell and Lealand.

scholarly journals Modeling Pulsed High-Power Spikes to Drive Piezoelectric Broadband Transducers Improving SNR in Ultrasonic Imaging & NDE

2021 ◽  
Author(s):  
Antonio Ramos ◽  
Abelardo Ruiz ◽  
Enrique Riera
Keyword(s):  
High Power ◽  
Dynamic Range ◽  
Ultrasonic Imaging ◽  
Average Power ◽  
Pulsed Power ◽  
Moderate Intensity ◽  
Signal To Noise ◽  
Discharge Generator ◽  
Piezoelectric Devices ◽  
Very High

Ultrasonic imaging & NDE applications can greatly improve their signal-to-noise ratios (SNR) by driving each transducer (composing piezoelectric arrays) with a spike giving pulsed power of k-Watts, repetitively at a PRF = 5000 spikes/s, by using a HV capacitive-discharge generator. However very-high levels, of pulsed intensities (3-10 A) and voltages (300-700 V) must be considered for a rigorous spike modeling. Even though the consumed "average" power will be small, the intensity through each transducer achieves several amperes, so the pulsed powers delivered by each HV generator can attain levels higher than in CW high-power ultrasonic applications: e.g., up to 5 kW / spike. This is concluded here from a transient modeling of the loaded generator. Then, unforeseen phenomena rise: intense brief pulses of driving power & emitted force in transducers, and non-linearities in driver semiconductors, because their characteristic curves only include linear ranges. But fortunately, piezoelectric devices working in this intense regime do not show serious heating problems, because the average power remains being moderate. Intensity, power and voltage, driving a broadband transducer from a HV capacitive pulser, are calculated to drastically improve (in ≅ 40 dB) the ultrasonic net dynamic range available, with emitted forces ≅ 250 Newtons pp and E/R received pulses of 70 V pp.

Very high power and superior rate capability LiFePO4 nanorods hydrothermally synthesized using tetraglycol as surfactant

RSC Advances ◽  
2015 ◽  
Vol 5 (3) ◽  
pp. 1859-1866 ◽  
Author(s):  
Ruiyuan Tian ◽  
Guangyao Liu ◽  
Haiqiang Liu ◽  
Lina Zhang ◽  
Xiaohua Gu ◽  
...  
Keyword(s):  
Ionic Conductivity ◽  
High Power ◽  
Lithium Iron Phosphate ◽  
Rate Capability ◽  
Iron Phosphate ◽  
Power Supplies ◽  
Large Current ◽  
Very High

Small polarizations, i.e. sufficiently good electronic and ionic conductivity is indispensible for high power lithium iron phosphate, especially for its applications to large current power supplies.

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