Transient electromagnetic calculations using the Gaver‐Stehfest inverse Laplace transform method

Knight, J. H.; Raiche, Art

doi:10.1190/1.1441280

Cited by 145 publications

(96 citation statements)

References 2 publications

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“…Combined, the two effects reduce the 2 maximum temperature rise by about 0.15 K and delay the arrival time of the maximum 3 temperature rise by approximately 5 s. In contrast, for water, the two effects combine to increase 4 the maximum temperature rise by about 0.09 K, and they cause the maximum temperature rise to 5 appear approximately 4 s earlier. 6 The results presented in Fig. 5 clearly indicate that the DPHP method will yield biased 7 estimates of thermal properties if the line-source solution is used for thermal property estimation.…”

Section: Finite Radius 21mentioning

confidence: 92%

Semianalytical Solution for Dual‐Probe Heat‐Pulse Applications that Accounts for Probe Radius and Heat Capacity

Knight

Kluitenberg

Kamai

et al. 2012

Vadose Zone Journal

139

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The dual‐probe heat‐pulse (DPHP) method is useful for measuring soil thermal properties. Measurements are made with a sensor that has two parallel cylindrical probes: one for introducing a pulse of heat into the soil (heater probe) and one for measuring change in temperature (temperature probe). We present a semianalytical solution that accounts for the finite radius and finite heat capacity of the heater and temperature probes. A closed‐form expression for the Laplace transform of the solution is obtained by considering the probes to be cylindrical perfect conductors. The Laplace‐domain solution is inverted numerically. For the case where both probes have the same radius and heat capacity, we show that their finite properties have equal influence on the heat‐pulse signal received by the temperature probe. The finite radius of the probes causes the heat‐pulse signal to arrive earlier in time. This time shift increases in magnitude as the probe radius increases. The effect of the finite heat capacity of the probes depends on the ratio of the heat capacity of the probes (C0) and the heat capacity of the soil (C). Compared with the case where C0/C = 1, the magnitude of the heat‐pulse signal decreases (i.e., smaller change in temperature) and the maximum temperature rise occurs later when C0/C > 1. When C0/C < 1, the magnitude of the signal increases and the maximum temperature rise occurs earlier. The semianalytical solution is appropriate for use in DPHP applications where the ratio of probe radius (a0) and probe spacing (L) satisfies the condition that a0/L ≤ 0.11.

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Section: Finite Radius 21mentioning

confidence: 92%

Semianalytical Solution for Dual‐Probe Heat‐Pulse Applications that Accounts for Probe Radius and Heat Capacity

Knight

Kluitenberg

Kamai

et al. 2012

Vadose Zone Journal

139

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“…The magnetic field H d (t) can be obtained by converting Eq. (3) into the time domain [12]. However, for motion measurement, the motion of the sensor will cause a slight change of the effective area for the inhomogeneous static magnetic field around the borehole, resulting in MBN that will strongly influence the performance of the proposed system.…”

Section: Borehole Emi System For Casing Inspectionmentioning

confidence: 99%

Borehole electromagnetic induction system with noise cancelation for casing inspection

Dang

Yang

Dang

et al. 2016

IEICE Electron. Express

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A borehole electromagnetic induction (EMI) system with noise cancelation for casing inspection is presented. Based on the analysis of the model for received signal in multi-cylindrical borehole structures, we choose to utilize a receive-only channel as the reference to cancel the effect of the background noise, where a registration matrix is used to compensate for the correlation of the non-isolated reference channel. Moreover, the performance of noise cancelation is verified by applying it to an oil borehole EMI system for the inspection of oil-well casings. Field experiments are conducted and the results demonstrate the effectiveness of the proposed method.

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“…The Hankel transforms in equations 1 and 2 may be calculated using conventional digital filter techniques (Anderson, 1979), while the Laplace transform may be computed using numerical methods such as the Gaver-Stehfest algorithm (Stehfest, 1970;Knight and Raiche, 1982). Alternatively, the Hankel transforms and the inverse Laplace transform may also be evaluated by using appropriate digital filters as described by Johansen and S(llrensen (1979), Weidelt (1984), and Christensen (1990).…”

Section: Fundamental Theorymentioning

confidence: 99%

On mapping seafloor mineral deposits with central loop transient electromagnetics

2012

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Electromagnetic methods are commonly employed in exploration for land-based mineral deposits. A suite of airborne, land, and borehole electromagnetic techniques consisting of different coil and dipole configurations have been developed over the last few decades for this purpose. In contrast, although the commercial value of marine mineral deposits has been recognized for decades, the development of suitable marine electromagnetic methods for mineral exploration at sea is still in its infancy. One particularly interesting electromagnetic method, which could be used to image a mineral deposit on the ocean floor, is the central loop configuration. Central loop systems consist of concentric transmitting and receiving loops of wire. While these types of systems are frequently used in land-based or airborne surveys, to our knowledge neither system has been used for marine mineral exploration. The advantages of using

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Transient electromagnetic calculations using the Gaver‐Stehfest inverse Laplace transform method

Cited by 145 publications

References 2 publications

Semianalytical Solution for Dual‐Probe Heat‐Pulse Applications that Accounts for Probe Radius and Heat Capacity

Semianalytical Solution for Dual‐Probe Heat‐Pulse Applications that Accounts for Probe Radius and Heat Capacity

Borehole electromagnetic induction system with noise cancelation for casing inspection

On mapping seafloor mineral deposits with central loop transient electromagnetics

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