The Application of Ground-airborne TEM Systems for Underground Cavity Detection in China

2018 ◽  
Vol 23 (1) ◽  
pp. 103-113
Author(s):  
Guo-qiang Xue ◽  
Xiu Li ◽  
Sheng-bao Yu ◽  
Wei-ying Chen ◽  
Yan-ju Ji
Keyword(s):  
Three Dimensional ◽  
Field Measurements ◽  
Cavity Detection ◽  
Vector Finite Element Method ◽  
Military Applications ◽  
Vector Finite Element ◽  
Survey Results ◽  
Tem Method ◽  
Central Loop ◽  
Good Agreement

Ground-based, electrical-source, and UAV-borne receiver TEM configurations have previously been used to map mines in Jiangsu Province, China. In this study, the EM responses of air-filled mine tunnels were simulated by using a three-dimensional (3D) vector finite element method. A new apparent resistivity formula has been proposed for the ground-airborne TEM configuration. In the study area, field measurements were carried out along 36 profiles for the ground-airborne TEM and 16 profiles for ground TEM. The ground-airborne TEM results were determined to be in good agreement with the ground TEM survey results using a surface central loop, and were also consistent with the known geologic conditions. The experiment was successful and showed that a ground-ground-airborne TEM method could potentially become a novel alternative for both future civilian and military applications. [Figure: see text]

Numerical Modelling of Circulation in Lake Sperillen, Norway

2000 ◽  
Vol 31 (1) ◽  
pp. 57-72 ◽  
Author(s):  
N. R. B. Olsen ◽  
D. K. Lysne
Keyword(s):  
Numerical Model ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Field Measurements ◽  
Navier Stokes ◽  
Water Current ◽  
Simple Method ◽  
Vertical Temperature Profile ◽  
Navier Stokes Equations ◽  
Good Agreement

A three-dimensional numerical model was used to model water circulation and spatial variation of temperature in Lake Sperillen in Norway. A winter situation was simulated, with thermal stratification and ice cover. The numerical model solved the Navier-Stokes equations on a 3D unstructured non-orthogonal grid with hexahedral cells. The SIMPLE method was used for the pressure coupling and the k-ε model was used to model turbulence, with a modification for density stratification due to the vertical temperature profile. The results were compared with field measurements of the temperature in the lake, indicating the location of the water current. Reasonably good agreement was found.

The Buzz-Saw Noise Generated by a High Duty Transonic Compressor

1971 ◽  
Vol 93 (1) ◽  
pp. 63-68 ◽  
Author(s):  
M. G. Philpot
Keyword(s):  
Pressure Field ◽  
Near Field ◽  
Pressure Fluctuations ◽  
Three Dimensional ◽  
Field Measurements ◽  
Rotor Blades ◽  
Transonic Compressor ◽  
Harmonic Content ◽  
Circumferential Pressure ◽  
Good Agreement

The buzz-saw noise made by a two-stage transonic research compressor has been investigated experimentally over a range of tip relative Mach numbers up to 1.56. The results show that the phenomenon is due to the propagation at supersonic relative tip speeds of the steady rotating pressure field associated with the first-stage rotor blades. The flow entering the tip section of the rotor has been analyzed theoretically and the circumferential pressure fluctuations computed, with good agreement with near-field measurements. The analysis leads to a clearer understanding of the dependence of the noise on inlet Mach number and three-dimensional effects and indicates the types of rotor irregularity which will most influence the harmonic content.

Application of the Vector Finite Element Method to 3D Magnetohydrodynamics

2003 ◽  
Author(s):  
Masaaki Matsumoto ◽  
Takahiko Tanahashi
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Magnetic Flux ◽  
Flux Density ◽  
Three Dimensional ◽  
Magnetic Flux Density ◽  
Shape Functions ◽  
Vector Finite Element Method ◽  
Vector Finite Element ◽  
Element Method

It is well known that the vector finite element method is one of the powerful tools for solving electromagnetic problems. The vector shape functions that are consist of the facet and the edge vector shape functions have a lot of characteristics. One of them is automatic conservation of the magnetic flux density in analyzing the Induction equations without iterative correction. In the present paper the vector finite element method is applied to the problems of magnetohydrodynamics. Three-dimensional natural convection in a cavity under a constant magnetic field is analyzed numerically using the GSMAC finite element method for flow field and temperature field and the vector finite element method for the Induction equations. The computational results are good agreement with those obtained using B method that is one of the iterative methods to satisfy the solenoidal condition for the magnetic flux density of the Induction equations.

scholarly journals NUMERICAL SOLVING THREE-DIMENSIONAL DIRECT PROBLEM OF PULSED ELECTROMAGNETIC CROSS-WELL EXPLORATION FOR CRYOLITHOZONE MONITORING

2021 ◽  
Vol 2 (2) ◽  
pp. 181-185
Author(s):  
Oleg V. Nechaev ◽  
Kirill N. Danilovskiy
Keyword(s):  
Mathematical Model ◽  
Finite Element Method ◽  
Finite Element ◽  
Direct Problem ◽  
Geophysical Methods ◽  
Three Dimensional ◽  
Spatially Inhomogeneous ◽  
Vector Finite Element Method ◽  
Vector Finite Element ◽  
Pulsed Electromagnetic

The article is devoted to the problem of studying permafrost state and the processes of its geocryological changes using geophysical methods. To monitor the cryolithozone, a method of pulsed electromagnetic cross-well sounding is proposed. On the basis of the vector finite element method, a mathematical model of the cross-well sounding process by a pulsed source in a three-dimensional spatially inhomogeneous medium has been created.

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