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A High-Speed Continuous Wave GPR
Subsurface Sensing Technologies and Applications, 2005In this work an innovative high speed continuous wave stepped frequency GPR has been designed and implemented with the aim of overcoming the low speed issue of wide bandwidth CW-SF GPRs. It is based on a structure combining a Digital Direct Synthesizer (DDS), a Phase Lock Loop (PLL) and a quadrature modulator (I/Q Modulator).
PARRINI, FILIPPO +2 more
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EPL (Europhysics Letters), 2011
We revisit the problem of heat conductance and diffusion, two remarkable transport processes characterized by instantaneous actions. We show that the assumption of local thermal equilibrium sets a limit to the speed of change in the distribution function of a statistical system .
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We revisit the problem of heat conductance and diffusion, two remarkable transport processes characterized by instantaneous actions. We show that the assumption of local thermal equilibrium sets a limit to the speed of change in the distribution function of a statistical system .
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Wave Speed in Noncircular Collapsible Ducts
Journal of Biomechanical Engineering, 1981The wave speed in initially elliptical collapsible tubes was studied. The celerity c of pressure waves of small amplitude was calculated from the numerically defined area-pressure law of the buckled cross section. In addition to the fact that the wave speed variation with transmural pressure was strongly dependent upon the initial eccentricity of the ...
M, Bonis, C, Ribreau
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Stationary waves in tubes and the speed of sound
The Physics Teacher, 2015The opportunity to plot oscillograms and frequency spectra with smartphones creates many options for experiments in acoustics, including several that have been described in this column.1–3 The activities presented in this paper are intended to complement these applications, and include an approach to determine sound velocity in air by using standard ...
Lutz Kasper +2 more
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Measurements of wave speed and reflected waves in elastic tubes and bifurcations
Journal of Biomechanics, 2002Wave intensity analysis is a time domain method for studying waves in elastic tubes. Testing the ability of the method to extract information from complex pressure and velocity waveforms such as those generated by a wave passing through a mismatched elastic bifurcation is the primary aim of this research.
Ashraf W. Khir, K H Parker
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The Journal of the Acoustical Society of America, 1990
The low-frequency tube wave speed is given explicitly for a variety of borehole environments. The presence of a logging tool, the effects of casing, and bore eccentricity are considered. The results are all relatively simple and indicate that the speed decreases in the presence of a tool or borehole eccentricity.
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The low-frequency tube wave speed is given explicitly for a variety of borehole environments. The presence of a logging tool, the effects of casing, and bore eccentricity are considered. The results are all relatively simple and indicate that the speed decreases in the presence of a tool or borehole eccentricity.
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Speed of stress wave propagation in lung
Journal of Applied Physiology, 1986The speed of stress waves in the lung parenchyma was investigated to understand why, among all internal organs, the lung is the most easily injured when an animal is subjected to an impact loading. The speed of the sound is much less in the lung than that in other organs.
R T, Yen +4 more
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Speed of Straight Waves in a Ripple Tank
American Journal of Physics, 1959The appropriate hydrodynamic relations are developed in a manner that utilizes mathematics which is no more complicated than the expression for the total derivative of a function of more than one variable. Expressions for the speed of propagation are obtained in two cases; first the surface tension is neglected, then it is taken into account.
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On the conservation of fast calcium wave speeds
Cell Calcium, 2002Calcium waves were first seen about 25 years ago as the giant, 10 micro m/s wave or tsunami which crosses the cytoplasm of an activating medaka fish egg [J Cell Biol 76 (1978) 448]. By 1991, reports of such waves with approximately 10 micro m/s velocities through diverse, activating eggs and with approximately 30 micro m/s velocities through diverse ...
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Elementary Derivation of Equations for Wave Speeds
American Journal of Physics, 1954The equations for the speed of waves in the following cases are derived in an elementary way: transverse waves along a stretched wire and through an elastic solid; longitudinal waves through a fluid in a uniform tube, through a uniform rod, and along a stretched spring; long gravity waves through a shallow canal.
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