Results 271 to 280 of about 7,200,285 (346)

Meshing frequency modulation assisted empirical wavelet transform for fault diagnosis of wind turbine planetary ring gear

Renewable Energy, 2019
Condition monitoring and fault diagnosis for wind turbine gearbox is significant to save operation and maintenance costs. However, strong interferences from high-speed parallel gears and background noises make fault detection of wind turbine planetary ...
Yun Kong, Tianyang Wang, F. Chu
semanticscholar   +1 more source

An Advanced Nonlinear Frequency Modulation Waveform for Radar Imaging With Low Sidelobe

IEEE Transactions on Geoscience and Remote Sensing, 2019
With the development of high-resolution radar satellite for global comprehensive environmental monitoring, day-and-night and all-weather surveillance has become an active and growing research field. However, in all cases, these applications require radar
Guodong Jin, Yunkai Deng, Robert Wang, Wei Wang, Pei Wang, Yajun Long, Zhi Zhang, Yongwei Zhang   +7 more
semanticscholar   +1 more source

Nonlinear Frequency Modulation Signal Generator in LT-1

IEEE Geoscience and Remote Sensing Letters, 2019
Generally, synthetic aperture radar (SAR) system transmits linear frequency modulation (LFM) signal to obtain the high-resolution image and weighted windowing is usually employed to suppress sidelobes.
Guodong Jin, Kaiyu Liu, Yunkai Deng, Y. Sha, Robert Wang, Dacheng Liu, Wen Wang, Yajun Long, Yongwei Zhang   +8 more
semanticscholar   +1 more source

Experimental study on the intrawave frequency modulation characteristic of rotor rub and crack fault

Mechanical systems and signal processing, 2019
Rub and crack are two important rotor faults. In this paper, the rub, crack and rub-crack coupled fault experiments are performed on a rotor test rig and the instantaneous frequency signatures of the faults are analyzed using Hilbert–Huang transform. The
Aijun Hu, Ling Xiang, Yue Zhang
semanticscholar   +1 more source

Study on intra-wave frequency modulation phenomenon in detection of rub-impact fault

Mechanical systems and signal processing, 2019
The rub-impact fault occurring in the rotating machinery can cause the periodically frequency modulation (FM) in its vibration response. Such kind of modulation mode has been named as intra-wave FM effect, which carries the intrinsic fault information of
P. Zhou, M. Du, Shiqian Chen, Qingbo He, Zhike Peng, Wenming Zhang   +5 more
semanticscholar   +1 more source

A Novel Dual Switching Frequency Modulation for Z-Source and Quasi-Z-Source Inverters

IEEE transactions on industrial electronics (1982. Print), 2018
Impedance network inverters are the best alternatives for voltage-source and current-source inverters. The boosting capability and the shoot-through solution of such converters make them excellent solutions for various applications.
M. Mohammadi, J. Moghani, J. Milimonfared   +2 more
semanticscholar   +1 more source

Automatic determination of digital modulation types with different noises using Convolutional Neural Network based on time-frequency information

Applied Soft Computing, 2020
In this study, a novel digital modulation classification model has been proposed for automatically recognizing six different modulation types including amplitude shift keying (ASK), frequency shift keying (FSK), phase-shift keying (PSK), quadrate ...
N. Daldal, Zafer Cömert, K. Polat
semanticscholar   +1 more source

Doppler modulation and Zeeman modulation: laser frequency stabilization without direct frequency modulation

Applied Optics, 1988
We discuss two methods (Zeeman modulation and Doppler modulation) for locking the frequency of a singlemode cw laser to an atomic absorption line. These methods do not require the laser frequency to be modulated directly. In the first scheme the absorption frequency of the atom is modulated via the Zeeman effect; in the second scheme the laser ...
A, Weis, S, Derler
openaire   +2 more sources

Frequency-modulated Nd:YAG laser

Optics Letters, 1991
A frequency-modulated, single-mode Nd:YAG laser has been constructed that tunes up to 12 GHz. The laser incorporates a LiTaO(3) electro-optic phase modulator with acoustic damping to provide a tuning sensitivity of 12 MHz/V and linear voltage-to-frequency conversion. A frequency excursion of 1.2 GHz has been generated with a rise time of 0.6 ns.
P A, Schulz, S R, Henion
openaire   +2 more sources

Frequency-modulation-polarization spectroscopy

Optics Letters, 1983
We have combined frequency-modulation and polarization spectroscopy to detect anisotropic spectral features with high sensitivity. The many line shapes possible with this technique and the potential for laser noise suppression were demonstrated by using saturation holes in iodine vapor.
M, Romagnoli, M D, Levenson, G C, Bjorklund   +2 more
openaire   +2 more sources