Time domain frequency stability calculated from the frequency domain description :

1991 ◽  
Author(s):  
F L Walls ◽  
John Gary ◽  
Abbie O'Gallagher ◽  
Roland Sweet ◽  
Linda Sweet
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Frequency Stability ◽  
Domain Description

scholarly journals Time domain frequency stability calculated from the frequency domain description :

1989 ◽  
Author(s):  
F L Walls ◽  
John Gary ◽  
Abbie O'Gallagher ◽  
Roland Sweet ◽  
Linda Sweet
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Frequency Stability ◽  
Domain Description

Estimation of Eccentric Distance for Four-Tooth End Mills Based on Amplitude Spectrum

2013 ◽  
Vol 278-280 ◽  
pp. 207-211
Author(s):  
Can Liu ◽  
Jing Quan Wu ◽  
Guang Hui Li ◽  
Guang Yu Tan
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Mathematical Reasoning ◽  
Spectral Characteristics ◽  
Amplitude Spectrum ◽  
Frequency Component ◽  
Milling Force ◽  
End Mills ◽  
Domain Description ◽  
Eccentric Distance

Time-domain expressions of nominal component and eccentric component that composing horizontal peripheral milling force are derived from geometry of down milling, they are periodic functions with fundamental frequencies same as tooth-frequency and spindle-frequency respectively. By expanding these two time-domain expressions with Taylor series, the frequency-domain description of periheral milling force is obtained. Further mathematical reasoning is exerted on this frequency-domain description, and it proved that as for four-tooth end mills, even-order harmonics of eccentric milling force do not exist, and the amplitude of spindle-frequency component be linear with eccentric distance, but irrelevant with eccentric angle. Above research results imply that the tooth-frequency component of four-tooth end mills is irrelevant with eccentricity, and that eccentric distance can be estimated with amplitudes of tooth-frequency and spindle-frequency components. Results of milling experiment imply that this eccentric-distance estimating method be effective. Spectral characteristics of eccentric milling force for four-tooth end mills are revealed with theory deduction, and the estimation algorithm for eccentric distance with simple calculation is present. Study conclusions can be used in eccentric-geometry estimating and in milling-force modeling.

scholarly journals Polarization-Sensitive Electro-Optic Sampling of Elliptically-Polarized Terahertz Pulses: Theoretical Description and Experimental Demonstration

Particles ◽  
2019 ◽  
Vol 2 (1) ◽  
pp. 70-89 ◽  
Author(s):  
Kenichi Oguchi ◽  
Makoto Okano ◽  
Shinichi Watanabe
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Probe Pulse ◽  
Polarization State ◽  
Frequency Component ◽  
Phase Mismatch ◽  
Pockels Effect ◽  
Electro Optic ◽  
Domain Description ◽  
Elliptically Polarized

We review our recent works on polarization-sensitive electro-optic (PS-EO) sampling, which is a method that allows us to measure elliptically-polarized terahertz time-domain waveforms without using wire-grid polarizers. Because of the phase mismatch between the employed probe pulse and the elliptically-polarized terahertz pulse that is to be analyzed, the probe pulse senses different terahertz electric-field (E-field) vectors during the propagation inside the EO crystal. To interpret the complex condition inside the EO crystal, we expressed the expected EO signal by “frequency-domain description” instead of relying on the conventional Pockels effect description. Using this approach, we derived two important conclusions: (i) the polarization state of each frequency component can be accurately measured, irrespective of the choice of the EO crystal because the relative amplitude and phase of the E-field of two mutually orthogonal directions are not affected by the phase mismatch; and, (ii) the time-domain waveform of the elliptically-polarized E-field vector can be retrieved by considering the phase mismatch, absorption, and the effect of the probe pulse width. We experimentally confirm the above two conclusions by using different EO crystals that are used for detection. This clarifies the validity of our theoretical analysis based on the frequency-domain description and the usefulness of PS-EO sampling.

JOINT INTERPRETATION OF AIRBORNE ELECTROMAGNETIC DATA IN THE TIME DOMAIN AND FREQUENCY DOMAIN

2018 ◽  
Vol 12 (7-8) ◽  
pp. 76-83
Author(s):  
E. V. KARSHAKOV ◽  
J. MOILANEN
Keyword(s):  
Fourier Transform ◽  
Frequency Domain ◽  
Time Domain ◽  
Frequency Interval ◽  
Single Spectrum ◽  
Simultaneous Inversion ◽  
Homogeneous Half Space ◽  
Time Domain Data ◽  
The Time Domain

Тhe advantage of combine processing of frequency domain and time domain data provided by the EQUATOR system is discussed. The heliborne complex has a towed transmitter, and, raised above it on the same cable a towed receiver. The excitation signal contains both pulsed and harmonic components. In fact, there are two independent transmitters operate in the system: one of them is a normal pulsed domain transmitter, with a half-sinusoidal pulse and a small "cut" on the falling edge, and the other one is a classical frequency domain transmitter at several specially selected frequencies. The received signal is first processed to a direct Fourier transform with high Q-factor detection at all significant frequencies. After that, in the spectral region, operations of converting the spectra of two sounding signals to a single spectrum of an ideal transmitter are performed. Than we do an inverse Fourier transform and return to the time domain. The detection of spectral components is done at a frequency band of several Hz, the receiver has the ability to perfectly suppress all sorts of extra-band noise. The detection bandwidth is several dozen times less the frequency interval between the harmonics, it turns out thatto achieve the same measurement quality of ground response without using out-of-band suppression you need several dozen times higher moment of airborne transmitting system. The data obtained from the model of a homogeneous half-space, a two-layered model, and a model of a horizontally layered medium is considered. A time-domain data makes it easier to detect a conductor in a relative insulator at greater depths. The data in the frequency domain gives more detailed information about subsurface. These conclusions are illustrated by the example of processing the survey data of the Republic of Rwanda in 2017. The simultaneous inversion of data in frequency domain and time domain can significantly improve the quality of interpretation.

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