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  • Electronic Resource  (6)
  • Book
  • 1975-1979  (6)
  • Fourier analysis
  • Verständlichkeit
  • 1
    Electronic Resource
    Electronic Resource
    Frequency and amplitude analysis of the EMG during exercise on the bicycle ergometer (1979)
    Springer
    European journal of applied physiology 41 (1979), S. 1-15 
    Details
    ISSN: 1439-6327
    Keywords: Dynamic exercise ; Static exercise ; EMG ; Fourier analysis ; Fatigue ; Temperature regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The surface EMG was recorded from above the quadriceps muscle in 3 male subjects during bicycle ergometry at work loads between 20 and 100% of the VO2 max to measure the EMG amplitude (RMS) and frequency (assessed from the center frequency of the power spectra) during this type of work. During brief (3 min) bouts of work the RMS amplitude of the EMG was linearly related to the work load; the center frequency of the EMG power spectra was the same at all work loads examined. In contrast, during sustained bouts of work maintained for 80 min at 20 and 40% of the VO2 max, the RMS amplitude of the EMG remained constant while the center frequency initially increased for the first 20 min of work and then progressively decreased as the work continued. When work loads of 60, 80, and 100% of the VO2 max were sustained to fatigue, the RMS amplitude continually increased while the EMG frequency decreased from the beginning to the end of the work periods. The results of this study showed that the EMG is a complex waveform, being influenced not only by fatigue, but to even a larger extent in many cases, the temperature of the exercising muscles. Therefore, although musclar fatigue caused an increase in the RMS amplitude and decrease in the center frequency, the increase in muscle temperature associated with the work opposed these changes by causing a reduction in the RMS amplitude and an increase in the center frequency.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00424464
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Optical processing of structural contour maps (1977)
    Springer
    Mathematical geology 9 (1977), S. 3-38 
    Details
    ISSN: 1573-8868
    Keywords: optical processing ; Fourier analysis ; structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract Optical processing is a fast, easy, economical, and reliable method of quantifying map patterns. A reduced transparency of a zebra-like pattern, obtained by blackening in alternate contour bands of a map, is used as input to an optical system of a laser source and objective lens to produce Fourier transforms. By sampling the intensity distribution across the transform, information about the spatial frequency (periodicity) and orientation in the original map can be inferred. Parameters used for comparing the map images are the values of intensity distribution in the transform. These intensities are normalized and subjected to comparison using various similarity methods. Cross-multiplication of the intensities is suggested as a measure of vectorial comparison of the orientations. By plotting the directional intensities into a polar coordinate system, rose diagrams are prepared for visual comparison. Optically derived parameters are independent of scale and other restrictive and limiting requirements as demanded in techniques of map analyses based on numerically derived parameters. The technique can be used in analyzing other pictorial data including aerial photographs, rock-fabric diagrams, and thin sections.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02312493
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Numerical strain analysis using polar coordinate transformations (1976)
    Springer
    Mathematical geology 8 (1976), S. 183-202 
    Details
    ISSN: 1573-8868
    Keywords: Fourier analysis ; paleontology ; structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract A system of strain analysis based on the application of a homogeneous strain transformation in plane polar coordinates to match deformed shapes of the same initial form is described. Two types of transformation are derived. A simple transformation between the deformed and the undeformed states, used to compare deformed shapes with a predetermined initial configuration, is recorded in the form of a plane polar coordinate Fourier series. This method allows reliable strain estimates to be made from single specimens of a fossil in an area where sufficient consistency of original shape has been established. A transformation describing the difference in relative strain between local polar coordinate systems in the same overall homogeneous deformation field, is used to compare the members of a group of deformed shapes with one another. This transformation allows the determination of the optimum initial ‘mean shape’of a group of fossils in a deformed rock as well as giving a strain measurement. The use of parabolic integration enhances the determination of the Fourier descriptions, and allows the use of irregularly spaced data. Inherent mathematical features of the method provide controls on the accuracy of the determination. The relatively mechanical nature of the input and the general form of the solution make the method readily applicable in semiautomated systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01079034
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Fourier analysis of bivalve outlines: Implications on evolution and autecology (1976)
    Springer
    Mathematical geology 8 (1976), S. 151-163 
    Details
    ISSN: 1573-8868
    Keywords: Fourier analysis ; power-spectrum analysis ; paleoecology ; paleontology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract Fourier analysis of shape provides a unique means of studying morphologic variation of bivalves, especially in terms of their evolution and autecology. Amplitude spectra resulting from analysis may be refined, summarized, and further evaluated by a series of statistical measures designed to extract the maximum amount of information from outline features. Root mean square error comparison of harmonics, combined with a modified analysis of variance design and Snedecor's F-test, permits identification of significant amplitudes. Intra- and interspecific variation may be expressed as variance about mean power estimates derived from significant amplitudes for each species. Variance estimates of 14 species of heterodont bivalves indicate that venerid bivalves show considerably more intraspecific shape variability than do tellinid species. In both groups, however, species characterized by more elongate shells show less intraspecific variability. Evolutionary and environmental implications of interspecific shape variance in bivalves suggest that future comprehensive examination of specimens, collected in situ, may be fruitful.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01079032
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    B-splines for smoothing and differentiating data sequences (1976)
    Springer
    Mathematical geology 8 (1976), S. 243-266 
    Details
    ISSN: 1573-8868
    Keywords: data processing ; Fourier analysis ; mathematics ; numerical analysis ; time series ; well logging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract Sequence convolution formulae, based on the B-splines of I. J. Schoenberg provide simple and effective methods for smoothing and differentiating data sequences. Their time and frequency domain properties allow calculation of the degree of smoothing and noise rejection, and their z-transforms lead to the rapid calculation of formulae from a simple sequence of polynomials. As an example of their use, numerical differentiation is used to produce smooth velocity—depth profiles and to delineate major velocity discontinuities from time—depth data logged at a well.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01029272
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Dynamic models of geomorphological patterns (1975)
    Springer
    Mathematical geology 7 (1975), S. 267-278 
    Details
    ISSN: 1573-8868
    Keywords: Fourier analysis ; pattern analysis ; geomorphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract A deformation mechanism is described and analyzed. It is intended for height patterns exposed to erosion and tectonic activity. A simulation experiment is carried out for this model. Closedform expressions are derived for the covariance field, the properties of spectral estimates, and for the optimal retrospective reconstruction of earlier, unknown height patterns. For obvious reasons the author is in no position to make claims about the verisimilitude of the model. It is offered as an example of a potential application to geology of the theory of patterns developed by the author and his coworkers in recent years. It is hoped that those more qualified than the author in the subject matter area can extend and modify the analysis to make it closer to geological reality.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02312724
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    Paper (German National Licenses)
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