Tag Archives: Amplitude

Harmonic Equations Deducible From the Hydrodynamic Motion of a Floating Object (Published)

Elementary analysis of hydrostatics gives an important result usually called Archimedes principle. Further investigation of this principle in hydrodynamic terms reveal some important properties common to an oscillatory system. The major aim of this paper is to give a brief derivation of a differential equation that best describes the harmonic nature of the motion of an object that is partially submerged in a liquid. The fundamental physical law for a floating object is called Archimedes principle stated as “An object that is partially or wholly submerged in a liquid is acted on by an upward force which equals the weight of the liquid displaced”. However, additional general description of this principle concerning the motion of the object will be established here in an effort to see if the results will be of any particular significance as a problem of hydrodynamics.

Keywords: Amplitude, cylinder, damping, floating object, harmonic motion, hydrodynamic

Field Measurements of GPR Antenna Pattern for Ava Data Correction (Published)

Amplitude versus incidence angle (AVA) analysis is a multi – offset attribute analysis technique which involves relating amplitude variations with increasing angle of incidence (or practically, offsets), in order to characterize interfaces and layers. The GPR AVA technique has its origin from seismic reflection processing and assumes isotropic source radiation (and reception) for GPR and also, far – field conditions. GPR antennae radiate EM energy as waves travelling in a hemispherical wave front into the ground and, typically show a strong directionality in radiation and reception with respect to amplitude and/ or frequency of the signal when used for surface surveys. The antennae patterns depend on the properties of the media in which the GPR signal is radiated into and must, therefore be accounted for in AVA analysis. This paper reports the results of numerical simulations and field measurement of antennae patterns. The field site is Threshfield quarry, Yorkshire, United Kingdom, extracting the Carboniferous Limestone. A series of transillumination surveys, across limestone boulders of different thicknesses were done to enable in – situ determination of the antennae patterns. In addition to these and for comparison purposes, numerical simulations using GprMax software were also done. Both numerical and field data were processed using Reflex-Win Version 3.5.1 software (Sandmeier, 1997-2004). Processing comprises: de-wow (for field data), band – pass Butterworth filtering (250-750MHz), geometric spreading and envelope, or Hilbert transform. The resulting antennae patterns measured in the field agree broadly with numerically derived patterns, in that the basic shape is the same.

Keywords: AVA, Amplitude, Antennae Patterns, GPR

Field Measurements of GPR Antenna Pattern for Ava Data Correction (Published)

Amplitude versus incidence angle (AVA) analysis is a multi – offset attribute analysis technique which involves relating amplitude variations with increasing angle of incidence (or practically, offsets), in order to characterize interfaces and layers. The GPR AVA technique has its origin from seismic reflection processing and assumes isotropic source radiation (and reception) for GPR and also, far – field conditions. GPR antennae radiate EM energy as waves travelling in a hemispherical wave front into the ground and, typically show a strong directionality in radiation and reception with respect to amplitude and/ or frequency of the signal when used for surface surveys. The antennae patterns depend on the properties of the media in which the GPR signal is radiated into and must, therefore be accounted for in AVA analysis. This paper reports the results of numerical simulations and field measurement of antennae patterns. The field site is Threshfield quarry, Yorkshire, United Kingdom, extracting the Carboniferous Limestone. A series of transillumination surveys, across limestone boulders of different thicknesses were done to enable in – situ determination of the antennae patterns. In addition to these and for comparison purposes, numerical simulations using GprMax software were also done. Both numerical and field data were processed using Reflex-Win Version 3.5.1 software (Sandmeier, 1997-2004). Processing comprises: de-wow (for field data), band – pass Butterworth filtering (250-750MHz), geometric spreading and envelope, or Hilbert transform. The resulting antennae patterns measured in the field agree broadly with numerically derived patterns, in that the basic shape is the same.

Keywords: AVA, Amplitude, Antennae Patterns, GPR