Characteristic frequency functions and characteristic gain functions

1977 ◽  
Vol 26 (2) ◽  
pp. 265-278 ◽  
Author(s):  
A. G. J. MAcFARLANE ◽  
I. POSTLETHWAITE
Keyword(s):  
Characteristic Frequency ◽  
Frequency Functions

SURFACE IRREGULARITIES AS A COMPLEX SIGNAL OF TOOL REPRESENTATION TOGETHER WITH UNEVEN DISPLACEMENT IN RESPECT TO THE WORKPIECE

2014 ◽  
Vol 21 (1) ◽  
pp. 133-144 ◽  
Author(s):  
Adam Boryczko ◽  
Wojciech Rytlewski
Keyword(s):  
Machining Process ◽  
Surface Irregularity ◽  
Complex Signal ◽  
Complex Phenomenon ◽  
Tool Profile ◽  
Surface Irregularities ◽  
The Individual ◽  
Frequency Functions

Abstract In a dynamic machining process, distortion in surface irregularity is a very complex phenomenon. Surface irregularities form a periodic representation of the tool profile with various kinds of disturbance in a broad range of changes in the height and length of the profile. To discern these irregularity disturbances, interactions of the tool in the form of changes perpendicular and parallel relative to the workpiece were analyzed and simulated. The individual kinds of displacement of the tool relative to the workpiece introduce distortions in the changes of height and length. These changes are weakly represented in standard height and length irregularity parameters and their discernment has been found through amplitude-frequency functions.

scholarly journals Complexity and characteristic frequency studies in ECG signals of mice based on multiple scale factors

2011 ◽  
Vol 54 (6) ◽  
pp. 544-552
Author(s):  
XiaoDong Yang ◽  
AiJun He ◽  
Peng Liu ◽  
TongFeng Sun ◽  
XinBao Ning
Keyword(s):  
Characteristic Frequency ◽  
Multiple Scale ◽  
Ecg Signals ◽  
Scale Factors

Recognition of Bearing Faults of the Same Kind

1991 ◽  
Author(s):  
Ming Bao ◽  
Chun-sheng Zhao
Keyword(s):  
Condition Monitoring ◽  
Characteristic Frequency ◽  
Correct Equation ◽  
Bearing Faults ◽  
Single Fault ◽  
Equipment Utilization ◽  
Bearing Part ◽  
Fault Characteristic

Abstract Condition monitoring has gained much acceptance because of the reduction of maintenance expenses and the increase of rate of equipment utilization. It is very important that the serious degrees of machinery faults is correctly predicted. Two faults in a bearing part is, of course, more serious than the single fault is. If the features of bearing faults of the same kind are not recognized, faults of the same kind are, then, mistaken for a single fault, the serious consequences may be caused. The features of bearing faults of the same kind are presented and the illustrations are given in the paper. Meanwhile, the correct equation of roller’ s fault characteristic frequency is expounded conveniently.

Effects of material texture and packing density on the interfacial polarization of granular soils

Geophysics ◽  
2021 ◽  
pp. 1-58
Author(s):  
Hang Chen ◽  
Qifei Niu
Keyword(s):  
Electrical Conductivity ◽  
Packing Density ◽  
Characteristic Frequency ◽  
Effective Permittivity ◽  
Scale Up ◽  
Interfacial Polarization ◽  
Granular Soils ◽  
Geologic Materials ◽  
Effective Electrical Conductivity ◽  
Material Texture

Many electrical and electromagnetic (EM) methods operate at MHz frequencies, at which the interfacial polarization occurring at the solid-liquid interface in geologic materials may dominate the electrical signals. To correctly interpret electrical/EM measurements, it is therefore critical to understand how the interfacial polarization influences the effective electrical conductivity and permittivity spectra of geologic materials. We have used pore-scale simulation to study the role of material texture and packing in interfacial polarization in water-saturated granular soils. Synthetic samples with varying material textures and packing densities are prepared with the discrete element method. The effective electrical conductivity and permittivity spectra of these samples are determined by numerically solving the Laplace equation in a representative elementary volume of the samples. The numerical results indicate that the effective permittivity of granular soils increases as the frequency decreases due to the polarizability enhancement from the interfacial polarization. The induced permittivity increment is mainly influenced by the packing state of the samples, increasing with the packing density. Material textures such as the grain shape and size distribution may also affect the permittivity increment, but their effects are less significant. The frequency characterizing the interfacial polarization (i.e., the characteristic frequency) is mainly related to the electrical contrast of the solid and water phases. The model based on the traditional differential effective medium (DEM) theory significantly underestimates the permittivity increment by a factor of more than two and overestimates the characteristic frequency by approximately 1 MHz. These inaccurate predictions are due to the fact that the electrical interactions between neighboring grains are not considered in the DEM theory. A simple empirical equation is suggested to scale up the theoretical depolarization factor of grains entering the DEM theory to account for the interaction of neighboring grains in granular soils.

A Characterization of the Polya Frequency Functions of Order 3

1983 ◽  
Vol 15 (1-4) ◽  
pp. 53-69
Author(s):  
H. F. Weinberger
Keyword(s):  
Frequency Functions
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