Results 1 to 10 of about 1,310,237 (159)
The occurrence mechanism and damping method of ultra‐low‐frequency oscillations
IET Renewable Power Generation, 2021 The ultra‐low‐frequency oscillation (ULFO) problem has reappeared in China recently. Although the hydraulic generator is supposed to have a strong connection to this problem, the conditions for ULFO appearance and detailed reasons are not clear yet.
Peng Wang +6 more
doaj +2 more sources
IEEE Transactions on Sustainable Energy, 2022 This paper presents a dynamic analysis for ultra-low frequency oscillations (ultra-LFOs) observed in the wind-hydropower hybrid systems. In such systems, DFIG wind turbines (WTs) are required to be frequency-responsive with providing the inertia and ...
Li Sun, Xiaowei Zhao, Li Sun
exaly +2 more sources
Differential ultra low noise amplifier for low frequency noise measurements
AIP Advances, 2011 Almost all low noise voltage preamplifier suitable for application in the field of Low Frequency Noise Measurements (either commercially available or proposed in the literature) are single ended input amplifiers.
Graziella Scandurra +2 more
doaj +3 more sources
An ultra-low-frequency sound absorber and its application in noise reduction in ducts
APL MaterialsWe demonstrate, both numerically and experimentally, an ultra-low-frequency sound absorber and its application in silenced ducts. The absorber comprises an array of resonant dual-spiral channel units (with a thickness of λ/47) backed by a wall, achieving
Yi-jun Guan +6 more
doaj +2 more sources
Progress in the realisation of ultra- low frequency vibration calibrations
Measurement: Sensors, 2021 The demand from industry to produce high credibility measurement data down to ever lower frequencies with ever lower noise is increasing. Recently also a demand to support the operation of global networks for environmental monitoring and research in ...
Jacob Holm Winther
doaj +1 more source
Study on stability margin of ultra-low frequency oscillation in hydropower system
Energy Reports, 2023 In recent years, the ultra-low frequency oscillation of power system caused by hydropower units has occurred frequently. It is very important to study the ultra-low frequency oscillation characteristics of hydropower stations for the stable operation of ...
Fan Tang +8 more
doaj +1 more source
Ultra Low Frequency Wave Produced by Underwater Oscillating Sphere and Its Measurement
Journal of Marine Science and Engineering, 2021 When an underwater target moves in viscous fluid, it may cause the periodic movement of the surrounding fluid and generate ultra-low-frequency (ULF) gravity waves.
Huan Wang +4 more
doaj +1 more source
AC amplifiers with ultra‐low corner frequency by using bootstrapping
Electronics Letters, 2021 A novel architecture for an AC (i.e. high‐pass) amplifier is proposed allowing a drastic reduction of the cutoff frequency to the sub‐Hertz range. It builds upon the classic AC configuration with a high gain amplifier and a parallel RC circuit in the ...
Maite Martincorena‐Arraiza +3 more
doaj +1 more source
A family of AC amplifiers for ultra‐low frequency operation [PDF]
International Journal of Circuit Theory and Applications, 2021 AbstractA family of capacitively coupled alternating current (AC) amplifiers featuring ultra‐low (below 1 Hz) corner frequency is presented. This is achieved by using high‐gain devices which actively boost feedback resistance and thus reduce corner frequency.
Maite Martincorena-Arraiza +4 more
openaire +1 more source
Design of a Clinical Ultra-Low Frequency Ballistocardiograph [PDF]
Circulation, 1959 The potential advantages of an ultra-low frequency ballistocardiograph are presented.
R R, DONALDSON +3 more
openaire +2 more sources