On: “Interpretation of Gravity Anomalies Due to Finite Inclined Dikes Using Fourier Transformation” by V. L. S. Bhimasankaram, R. Nagendra, and S. V. Seshagiri Rao (GEOPHYSICS, February 1977, p. 51–59)

Geophysics ◽  
1978 ◽  
Vol 43 (4) ◽  
pp. 823-824
Keyword(s):  
Fourier Transformation ◽  
Gravity Anomalies ◽  
Frequency Range ◽  
Straight Line ◽  
Elegant Solution

We feel that some of the results and conclusions in this paper need some comments. 1) The authors claim on p. 59 that their method clearly stands out as the first direct and elegant solution to the problem of the finite dipping dike in gravity prospecting. This is, in fact, not true, since Sharma et al (1970) arrived at exactly the same formulas. In our opinion their method of interpretation seems more realistic in many ways than the authors. For instance they find the depth to the dike from the slope of a straight line fitted to a spectral quantity, where the authors make use of selected points of the spectrum. The latter method seems to be more sensitive to noise than the former, where the straight line is fitted to the spectral quantity over some frequency range, thus some kind of averaging process is performed.

INTERPRETATION OF GRAVITY ANOMALIES DUE TO FINITE INCLINED DIKES USING FOURIER TRANSFORMATION

Geophysics ◽  
1977 ◽  
Vol 42 (1) ◽  
pp. 51-59 ◽  
Author(s):  
V. L. S. Bhimasankaram ◽  
R. Nagendra ◽  
S. V. Seshagiri Rao
Keyword(s):  
Fourier Transform ◽  
High Frequency ◽  
Fourier Transformation ◽  
Synthetic Data ◽  
Gravity Anomalies ◽  
Frequency Range ◽  
Unknown Parameters ◽  
Estimated Parameters ◽  
The Fourier Transform ◽  
Theoretical Considerations

The Fourier transform of the gravity field due to a finite dipping dike is derived and its real and imaginary components are separated. Analysis of these two functions in a certain high‐frequency range yields simple relations that can be used to estimate the unknown parameters of the dike. The theoretical considerations are tested on synthetic data after performing the discrete Fourier transform (DFT), and the validity of the method of interpretation is established from a comparison of the actual and estimated parameters.

Psychophysical Assessment of Whole-Body Vibration

1971 ◽  
Vol 13 (1) ◽  
pp. 41-50 ◽  
Author(s):  
Richard W. Shoenberger ◽  
C. Stanley Harris
Keyword(s):  
Magnitude Estimation ◽  
Whole Body Vibration ◽  
Whole Body ◽  
Subjective Response ◽  
Frequency Range ◽  
General Shape ◽  
Subjective Intensity ◽  
Straight Line ◽  
Matching Procedure ◽  
Body Response

Using the methods of magnitude estimation and intensity matching, curves of equal subjective vibration intensity were constructed over the frequency range from 3.5 to 20 Hz. Twenty subjects made magnitude estimations of the intensity of vibration at 0.08, 0.16, 0.24, 0.40, 0.48, and 0.56 gz with vibration at 0.32 gz serving as a standard. These intensities were judged at each of the frequencies of 3.5, 5, 7, 9, 11, 15, and 20 Hz. For each frequency, the results were plotted as straight-line functions on log-log graphs of subjective intensity against physical intensity. The slopes of the lines varied as a function of frequency, the steepest slope occurring at 5 Hz. (the frequency of greatest body response due to resonance in this axis). Additional experiments were conducted in which ten subjects matched the intensity of 9-Hz. vibration at 0.16, 0.36, and 0.56 gz with vibration at each of the other six frequencies listed above, and ten different subjects made similar equality judgments against 9-Hz. vibration at 0.08, 0.26, and 0.46 gz. Equal intensity curves derived from the magnitude estimation data show the same general shape and comparable levels as corresponding curves determined experimentally using the intensity matching procedure. These methods provide more systematic and quantitative characterizations of subjective response to vibration than previous approaches which have relied heavily on qualitative descriptions.

Interpretation of gravity anomalies of dike-like bodies by Fourier transformation

1970 ◽  
Vol 7 (2) ◽  
pp. 512-516 ◽  
Author(s):  
Bijon Sharma ◽  
L. P. Geldart ◽  
D. E. Gill
Keyword(s):  
Fourier Transform ◽  
Detailed Analysis ◽  
Gravity Anomaly ◽  
Fourier Transformation ◽  
Amplitude Spectrum ◽  
Gravity Anomalies ◽  
Objective Method ◽  
The Fourier Transform

An objective method is presented for interpreting the gravity anomalies of a dike using the Fourier transform of the observed gravity anomaly function. The amplitude spectrum of the transformed function contains information about the depth, inclination, and the thickness of the dike. The usefulness of the Fourier transform technique is illustrated by a detailed analysis of the gravity anomaly of a dike.

A Straight-Line 160-Gb/s DPSK Transmission Over 1000 km With Time-Domain Optical Fourier Transformation

2008 ◽  
Vol 20 (13) ◽  
pp. 1094-1096 ◽  
Author(s):  
Toshihiko Hirooka ◽  
Masatada Okazaki ◽  
Masataka Nakazawa
Keyword(s):  
Time Domain ◽  
Fourier Transformation ◽  
Straight Line

Development of a Hand-Arm Model to Emulate Tremor Handwriting Behavior

2014 ◽  
Vol 660 ◽  
pp. 911-915
Author(s):  
Zulkifli Mohd Yusop ◽  
Mohd Zarhamdy Md Zain ◽  
Mohamed Hussein ◽  
Maziah Mohamad
Keyword(s):  
Spectral Density ◽  
Hand Movement ◽  
Screw Thread ◽  
Frequency Range ◽  
Hand Tremor ◽  
Power Spectral ◽  
Straight Line ◽  
Acceleration Data ◽  
Model Setup ◽  
Handwriting Behavior

Patients with hand tremor may find difficulties in performing their routine task especially writing. The worse when the tremor becomes severe. In this paper, a hand-arm model has been developed to study the behavior of tremor while performing handwriting. Regarding the study, the hand of patient oscillates in a perpendicular direction to the forearm rather than other directions due to hand support while the handwriting is performed. A miniature accelerometer patched to the writing device and acceleration data recorded have then been examined by power spectral density (PSD). For hand-arm model setup, the DC motor was used to emulate the hand movement to draw a straight line by connecting the linear screw thread to the writing mechanism. For writing mechanism, there are two parts, holder to hold the pen and Linear Voice Coil Actuator (LVCA) to resemble hand tremor conditions. By injecting tremor data to the LVCA the acceleration is measured once again by attaching a miniature accelerometer to the writer device. The findings show that the model can emulates hand tremor by considering its acceleration and frequency range from PSD based on record actual tremor data as references. The hand-arm model furthers can be a research conduct to design a writing device that can be cancelled or at least suppress the tremor.

scholarly journals Improved Evaluation of Planar Calibration Standards Using the TDR Preselection Method

10.14311/988 ◽  
2007 ◽  
Vol 47 (4-5) ◽  
Author(s):  
J. Vancl
Keyword(s):  
Measurement Error ◽  
Time Domain ◽  
Fourier Transformation ◽  
Constant Error ◽  
Error Model ◽  
Error Minimization ◽  
Network Analyzer ◽  
Frequency Range ◽  
Calibration Standards ◽  
Planar Calibration

Calibration and correction methods for the Vector Network Analyzer (VNA) are based on the fundamental assumption of the constant error model, which is independent of connected calibration standards and/or devices under test (DUT). Unfortunately, this assumption is not satisfied well for planar calibration standards fabricated by etching technology on soft substrates. An evaluation of the error model is affected especially by variations in the manufacturing process and also by the reproducibility of an assembly. In this paper, we propose error minimization by selecting the best combination of available calibration standards based on time domain reflection (TDR) measurement, which can also be obtained by the fourier transformation from the measured S-parameters. The proposed method was verified experimentally using short, open, load and thru (SOLT) standards fabricated on an FR4 laminate substrate which achieves the essential reduction of the measurement error in the frequency range up to 15 GHz. 

Vibration Isolation on Lightweight Floor Structures

2002 ◽  
Vol 9 (4) ◽  
pp. 257-269 ◽  
Author(s):  
P Hammer ◽  
J Brunskog
Keyword(s):  
High Frequency ◽  
Vibration Isolation ◽  
Low Frequency ◽  
High Mobility ◽  
Frequency Range ◽  
Two Stage ◽  
One Stage ◽  
Straight Line ◽  
Floor Structure

A theoretical and experimental study of vibration isolation for a source on a lightweight floor structure is presented. The effectiveness of one-stage and two-stage isolator systems is studied. Approximate formulae are presented for both low and high frequency for the receiver, the floor structure. For the mobility, a comparison between approximate formulae, numerical exact results and experimental results are presented. The low frequency asymptote for the approximate mobility is valid up to l/λp ≈ 1/4. The high frequency asymptote is valid from l/λp ≈ 1/2. A straight line can be drawn between these two points for the intermediate range 1/4 < l/λp < 1/2. Finally, a case study is presented. A fan is mounted on a wooden joist floor. The effect of both one and two stage isolation is demonstrated. It is clearly seen that the high mobility situation for the receiver is increased by adding a rigid body to the mount. Hence, in the frequency range of interest, the ‘receiver’ acts more or less as a blocked termination. A two-stage isolator almost completely eliminates the structure borne sound and compared to a one-stage isolator it reduces the sound by 20 dB at the rpm for the fan.

Microdensitometer—computer correlation analysis of ultrastructural periodicity

1978 ◽  
Vol 36 (2) ◽  
pp. 32-33
Author(s):  
D.R. Ensor ◽  
C.G. Jensen ◽  
J.A. Fillery ◽  
R.J.K. Baker
Keyword(s):  
Correlation Analysis ◽  
Background Noise ◽  
Computer Control ◽  
Optical Diffraction ◽  
Screw Thread ◽  
Straight Line ◽  
Computer Storage ◽  
Correlation Process ◽  
Electron Microscope Image ◽  
Fixed Beam

Because periodicity is a major indicator of structural organisation numerous methods have been devised to demonstrate periodicity masked by background “noise” in the electron microscope image (e.g. photographic image reinforcement, Markham et al, 1964; optical diffraction techniques, Horne, 1977; McIntosh,1974). Computer correlation analysis of a densitometer tracing provides another means of minimising "noise". The correlation process uncovers periodic information by cancelling random elements. The technique is easily executed, the results are readily interpreted and the computer removes tedium, lends accuracy and assists in impartiality.A scanning densitometer was adapted to allow computer control of the scan and to give direct computer storage of the data. A photographic transparency of the image to be scanned is mounted on a stage coupled directly to an accurate screw thread driven by a stepping motor. The stage is moved so that the fixed beam of the densitometer (which is directed normal to the transparency) traces a straight line along the structure of interest in the image.

Freeze fracture imaging and computer simulation of liposome structure: Membrane geometry and defects

1983 ◽  
Vol 41 ◽  
pp. 646-647
Author(s):  
Joseph A. Zasadzinski
Keyword(s):  
Liquid Crystalline ◽  
Freeze Fracture ◽  
Continuum Theory ◽  
Closed Surfaces ◽  
Straight Line ◽  
Low Weight ◽  
Concentric Spheres ◽  
Membrane Geometry ◽  
Dupin Cyclides ◽  
Limiting Case

At low weight fractions, many surfactant and biological amphiphiles form dispersions of lamellar liquid crystalline liposomes in water. Amphiphile molecules tend to align themselves in parallel bilayers which are free to bend. Bilayers must form closed surfaces to separate hydrophobic and hydrophilic domains completely. Continuum theory of liquid crystals requires that the constant spacing of bilayer surfaces be maintained except at singularities of no more than line extent. Maxwell demonstrated that only two types of closed surfaces can satisfy this constraint: concentric spheres and Dupin cyclides. Dupin cyclides (Figure 1) are parallel closed surfaces which have a conjugate ellipse (r1) and hyperbola (r2) as singularities in the bilayer spacing. Any straight line drawn from a point on the ellipse to a point on the hyperbola is normal to every surface it intersects (broken lines in Figure 1). A simple example, and limiting case, is a family of concentric tori (Figure 1b).To distinguish between the allowable arrangements, freeze fracture TEM micrographs of representative biological (L-α phosphotidylcholine: L-α PC) and surfactant (sodium heptylnonyl benzenesulfonate: SHBS)liposomes are compared to mathematically derived sections of Dupin cyclides and concentric spheres.

Human Enamel Replication

1976 ◽  
Vol 34 ◽  
pp. 180-181
Author(s):  
Norman L. Dockum ◽  
John G. Dockum
Keyword(s):  
Organic Matrix ◽  
Human Teeth ◽  
Human Enamel ◽  
Straight Line ◽  
Ultrastructural Characteristics

Ultrastructural characteristics of fractured human enamel and acid-etched enamel were compared using acetate replicas shadowed with platinum and palladium. Shadowed replications of acid-etched surfaces were also obtained by the same method.Enamel from human teeth has a rod structure within which there are crystals of hydroxyapatite contained within a structureless organic matrix composed of keratin. The rods which run at right angles from the dentino-enamel junction are considered to run in a straight line perpendicular to the perimeter of the enamel, however, in many areas these enamel rods overlap, interlacing and intertwining with one another.

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