RADIO INTERFEROMETRY DEPTH SOUNDING: PART I—THEORETICAL DISCUSSION

Geophysics ◽  
1973 ◽  
Vol 38 (3) ◽  
pp. 557-580 ◽  
Author(s):  
A. P. Annan
Keyword(s):  
Electrical Properties ◽  
Half Space ◽  
Interference Pattern ◽  
Saddle Point Method ◽  
Mode Analysis ◽  
Radio Interferometry ◽  
Wide Range ◽  
Depth Sounding ◽  
Transmitting Antenna ◽  
Surface Fields

Radio interferometry is a technique for measuring in‐situ electrical properties and for detecting subsurface changes in electrical properties of geologic regions with very low electrical conductivity. Ice‐covered terrestrial regions and the lunar surface are typical environments where this method can be applied. The field strengths about a transmitting antenna placed on the surface of such an environment exhibit interference maxima and minima which are characteristic of the subsurface electrical properties. This paper (Part I) examines the theoretical wave nature of the electromagnetic fields about various types of dipole sources placed on the surface of a low‐loss dielectric half‐space and two‐layer earth. Approximate expressions for the fields have been found using both normal mode analysis and the saddle‐point method of integration. The solutions yield a number of important results for the radio interferometry depth‐sounding method. The half‐space solutions show that the interface modifies the directionality of the antenna. In addition, a regular interference pattern is present in the surface fields about the source. The introduction of a subsurface boundary modifies the surface fields with the interference pattern showing a wide range of possible behaviors. These theoretical results provide a basis for interpreting the experimental results described in Part II.

scholarly journals Two-temperature dual-phase-lags theory in a thermoelastic solid half-space due to an inclined load

2016 ◽  
Vol 7 (2) ◽  
pp. 179-187
Author(s):  
Ashraf M. Zenkour ◽  
Ahmed E. Abouelregal ◽  
Khaled A. Alnefaie ◽  
Nidal H. Abu-Hamdeh ◽  
Abdulmalik A. Aljinaidi ◽  
...  
Keyword(s):  
Half Space ◽  
Mode Analysis ◽  
Dual Phase ◽  
Horizontal Distance ◽  
Inclined Load ◽  
Special Cases ◽  
Wide Range ◽  
Significant Difference ◽  
Phase Lags ◽  
Two Temperature

Abstract. This article addresses the thermoelastic interaction due to inclined load on a homogeneous isotropic half-space in context of two-temperature generalized theory of thermoelasticity with dual-phase-lags. It is assumed that the inclined load is a linear combination of both normal and tangential loads. The governing equations are solved by using the normal mode analysis. The variations of the displacement, stress, conductive temperature, and thermodynamic temperature distributions with the horizontal distance have been shown graphically. Results of some earlier workers have also been deduced from the present investigation as special cases. Some comparisons are graphically presented to estimate the effects of the two-temperature parameter, the dual-phase-lags parameters and the inclination angle. It is noticed that there is a significant difference in the values of the studied fields for different value of the angle of inclination. The method presented here maybe applicable to a wide range of problems in thermodynamics and thermoelasticity.

Linear electrical properties of striated muscle fibres observed with intracellular electrodes

1964 ◽  
Vol 160 (978) ◽  
pp. 69-123 ◽  
Keyword(s):  
Electrical Properties ◽  
Striated Muscle ◽  
Surface Membrane ◽  
Fibre Surface ◽  
Step Function ◽  
Muscle Fibres ◽  
Appreciable Effect ◽  
Current Application ◽  
Current Path ◽  
Wide Range

The linear electrical properties of muscle fibres have been examined using intracellular electrodes for a. c. measurements and analyzing observations on the basis of cable theory. The measurements have covered the frequency range 1 c/s to 10 kc/s. Comparison of the theory for the circular cylindrical fibre with that for the ideal, one-dimensional cable indicates that, under the conditions of the experiments, no serious error would be introduced in the analysis by the geometrical idealization. The impedance locus for frog sartorius and crayfish limb muscle fibres deviates over a wide range of frequencies from that expected for a simple model in which the current path between the inside and the outside of the fibre consists only of a resistance and a capacitance in parallel. A good fit of the experimental results on frog fibres is obtained if the inside-outside admittance is considered to contain, in addition to the parallel elements R m = 3100 Ωcm 2 and C m = 2.6 μF/cm 2 , another path composed of a resistance R e = 330 Ωcm 2 in series with a capacitance C e = 4.1 μF/cm 2 , all referred to unit area of fibre surface. The impedance behaviour of crayfish fibres can be described by a similar model, the corresponding values being R m = 680 Ωcm 2 , C m = 3.9 μF/cm 2 , R e = 35 Ωcm 2 , C e = 17 μF/cm 2 . The response of frog fibres to a step-function current (with the points of voltage recording and current application close together) has been analyzed in terms of the above two-time constant model, and it is shown that neglecting the series resistance would have an appreciable effect on the agreement between theory and experiment only at times less than the halftime of rise of the response. The elements R m and C m are presumed to represent properties of the surface membrane of the fibre. R e and C e are thought to arise not at the surface, but to be indicative of a separate current path from the myoplasm through an intracellular system of channels to the exterior. In the case of crayfish fibres, it is possible that R e (when referred to unit volume) would be a measure of the resistivity of the interior of the channels, and C e the capacitance across the walls of the channels. In the case of frog fibres, it is suggested that the elements R e , C e arise from the properties of adjacent membranes of the triads in the sarcoplasmic reticulum . The possibility is considered that the potential difference across the capacitance C e may control the initiation of contraction.

Influence of Nitrogen Implantation on Electrical Properties of Al/SiO2/4H-SiC MOS Structure

2013 ◽  
Vol 740-742 ◽  
pp. 733-736 ◽  
Author(s):  
Krystian Król ◽  
Mariusz Sochacki ◽  
Marcin Turek ◽  
Jerzy Żuk ◽  
Henryk M. Przewlocki ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Electrical Properties ◽  
Surface State ◽  
Material Properties ◽  
Implantation Dose ◽  
Nitrogen Implantation ◽  
Mos Structure ◽  
Implantation Damage ◽  
Wide Range ◽  
Implantation Dosage

In this article, an influence of nitrogen implantation dosage on SiC MOS structure is analyzed using wide range of nitrogen implantation dose (between ~1013 – 1016). Authors analyzed electrical and material properties of investigated samples using C-V, I-V measurements, Raman spectroscopy, and XPS profiling. It has been shown that surface state trap density is directly connected to implantation damage and thus implantation conditions. Using research results a trap origin at given energy can be concluded.

scholarly journals Prediction of Experimental Electromagnetic Coupling to a UAV Model Using Characteristic Mode Analysis

2021 ◽  
Author(s):  
Mohamed Hamdalla ◽  
Benjamin Bissen ◽  
James D. Hunter ◽  
Liu Yuanzhuo ◽  
Victor Khilkevich ◽  
...  
Keyword(s):  
Experimental Measurement ◽  
Experimental Approach ◽  
Electromagnetic Coupling ◽  
Mode Analysis ◽  
Angle Of Incidence ◽  
Characteristic Mode ◽  
System A ◽  
Wide Range ◽  
Aerial Vehicle ◽  
Excitation Conditions

<p>In this work, we study the current coupled to a simplified Unmanned Aerial Vehicle (UAV) model using a dual computational and experimental approach. The surrogate structure reduced the computational burden and facilitated the experimental measurement of the coupled currents. For a practical system, a wide range of simulations and measurements must be performed to analyze the induced current variations with respect to the incident excitation properties such as the frequency, angle of incidence, and polarization. To simplify this analysis, Characteristic Mode Analysis (CMA) was used to compute the eigen-currents of the UAV model and predict where and under which RF excitation conditions, the coupled current is maximized. We verified these predictions using direct experimental measurement of the coupled currents. The presented simulations and measurements show the usefulness of CMA for studying electromagnetic coupling to practical systems. </p>

scholarly journals Prediction of Experimental Electromagnetic Coupling to a UAV Model Using Characteristic Mode Analysis

2021 ◽  
Author(s):  
Mohamed Hamdalla ◽  
Benjamin Bissen ◽  
James D. Hunter ◽  
Liu Yuanzhuo ◽  
Victor Khilkevich ◽  
...  
Keyword(s):  
Experimental Measurement ◽  
Experimental Approach ◽  
Electromagnetic Coupling ◽  
Mode Analysis ◽  
Angle Of Incidence ◽  
Characteristic Mode ◽  
System A ◽  
Wide Range ◽  
Aerial Vehicle ◽  
Excitation Conditions

<p>In this work, we study the current coupled to a simplified Unmanned Aerial Vehicle (UAV) model using a dual computational and experimental approach. The surrogate structure reduced the computational burden and facilitated the experimental measurement of the coupled currents. For a practical system, a wide range of simulations and measurements must be performed to analyze the induced current variations with respect to the incident excitation properties such as the frequency, angle of incidence, and polarization. To simplify this analysis, Characteristic Mode Analysis (CMA) was used to compute the eigen-currents of the UAV model and predict where and under which RF excitation conditions, the coupled current is maximized. We verified these predictions using direct experimental measurement of the coupled currents. The presented simulations and measurements show the usefulness of CMA for studying electromagnetic coupling to practical systems. </p>

scholarly journals The first boundary value problem of the dynamics of an anisotropic elastic half-space under the action of subsonic transport loads

2020 ◽  
Vol 4 (78) ◽  
pp. 45-52
Author(s):  
G. K. ZAKIR’YANOVA ◽  
◽  
L. A. ALEXEYEVA ◽  
Keyword(s):  
Rock Mass ◽  
Boundary Value Problem ◽  
Half Space ◽  
Wide Class ◽  
Boundary Value ◽  
Operator Method ◽  
Elastic Half Space ◽  
Theory Of Elasticity ◽  
Wide Range ◽  
Anisotropic Elastic

The first boundary value problem of the theory of elasticity for an anisotropic elastic half-space is solved when a transport load moves along its surface. The subsonic Raleigh case is considered, when the velocity of motion is less than the velocity of propagation of bulk and surface elastic waves. The Green’s tensor of the transport boundary value problem is constructed and on its basis the solution of boundary value problems for a wide class of distributed traffic loads is given. To solve the problem, the methods of tensor and linear algebra, integral Fourier transform, and operator method for solving systems of differential equations were used. The obtained solution makes it possible to investigate the dynamics of the rock mass for a wide class of transport loads, in a wide range of velocities, both low velocities and high velocities, and to evaluate the strength properties of the rock mass under the influence of road transport. In particular, determine the permissible velocities of its movement and carrying capacity. In addition, a investigation on its basis of the movement of the day surface along the route will make it possible to establish criteria for the seismic resistance of ground structures and the permissible distances of their location from the route.

scholarly journals Система терагерцевой спектроскопии газовых смесей на основе твердотельных сверхпроводниковых источника и приемника терагерцевого диапазона

2021 ◽  
Vol 63 (9) ◽  
pp. 1204
Author(s):  
Н.В. Кинев ◽  
К.И. Рудаков ◽  
Л.В. Филиппенко ◽  
В.П. Кошелец
Keyword(s):  
Spectral Resolution ◽  
Open Space ◽  
Spectral Characteristics ◽  
Gas Mixture ◽  
Sis Receiver ◽  
Wide Range ◽  
A Cell ◽  
Transmitting Antenna ◽  
Josephson Oscillator ◽  
Better Than

In this paper, we demonstrate the application of a terahertz (THz) Josephson oscillator based on a tunnel superconductor-insulator-superconductor (SIS) long junction coupled to a transmitting antenna and emitting a signal to open space, for gas spectroscopy. The oscillator is utilized as an active source, the signal of which is absorbed by a gas mixture in a cell 60 cm long and then detected by a spectrometer based on a SIS receiver with a spectral resolution of better than 100 kHz. In the experiment, the absorption lines of ammonia and water in the THz range were recorded, and the dependence of the absorption spectral characteristics on the pressure of the gas mixture was shown in a wide range (from 0.005 to 10 mbar).

Optical and Electrical Properties of TiO2 Nanotubes Grown by Titanium Anodization

2009 ◽  
Vol 1178 ◽  
Author(s):  
Yahya Alivov ◽  
Vladimir Kuryatkov ◽  
Mahesh Pandikunta ◽  
Gautam Rajanna ◽  
Daniel Johnstone ◽  
...  
Keyword(s):  
Optical Properties ◽  
Electrical Properties ◽  
Tio2 Nanotubes ◽  
Anatase Phase ◽  
Rutile Phase ◽  
Electrochemical Anodization ◽  
Voltage Range ◽  
Wide Range ◽  
Transient Spectroscopy ◽  
Tio2 Nts

AbstractIn this work we investigated the structural, electrical, and optical properties of titanium dioxide (TiO2) nanotubes (NTs) formed by electrochemical anodization of Ti metal sheets in NH4F+glycerol electrolyte at different anodization voltages (Va) and acid concentrations. Our results revealed that TiO2 NTs can be grown in a wide range of anodization voltages from 10 V to 240 V. The maximum NH4F acid concentration, at which NTs can be formed, decreases with the anodization voltage, which is 0.7% for Va<60V, and decreases to 0.1% at Va =240 V. Glancing angle X-ray diffraction (GAXRD) experiments show that as-grown amorphous TiO2 transforms to anatase phase after annealing at 400 oC, and further transforms to rutile phase at annealing temperatures above 500 oC. Samples grown in 30-120 voltage range have higher crystal quality as seen from anatase (101) peak intensity and reduced linewidth. The electrical resistivity of the NTs varies with Va concentration and increases by eight orders of magnitude when Va increases from 10 V to 240 V. This is consistent with cathodoluminescense studies which showed improved optical properties for samples grown in this voltage range. Optical properties of samples were also studied by low temperature photoluminescence. Temperature dependent I-V and photo-induced current transient spectroscopy were employed to analyze electrical properties and defect structure on NT samples.

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