An Approximate Inversion Scheme for Surface-Borehole EM in the Presence of Steel Casing. 1D Implementation

Geophysics ◽  
2020 ◽  
pp. 1-51
Author(s):  
Nestor H. Cuevas
Keyword(s):  
Electrical Properties ◽  
Numerical Simulations ◽  
Field Distribution ◽  
Scaling Factor ◽  
Synthetic Dataset ◽  
Inversion Method ◽  
Computational Burden ◽  
Layered Earth ◽  
Exciting Source ◽  
Surface Borehole

An approximate inversion scheme for Surface-Borehole EM data is proposed. The method aims at reducing the computational burden arising by the fine discretization required to accurately solve for the field distribution in the full complexity of the borehole system together with the reservoir medium. I first analyze numerical simulations of the surface-borehole response performed for a 1D layered earth, incorporating also realistic complexity of the borehole system. The analysis brings useful insight on the requirement of incorporating fluid and mud/cement electrical properties when implementing an inversion by numerically simulating the full complexity of the system. Subsequently, the synthetic dataset was used to test an inversion method which uses the data dominated by the casing effect to approximately describe the casing secondary fields. A scaling factor is then introduced to account for the the current induced in the well as the exciting source is placed further below the casing shoe. The method is found to recover fairly well the known 1D resistivity strata, still some bias is expected for the resistivity close below the casing shoe, where the data is anticipated to be most distorted by the casing effect.

An Improved MMSE Pre-Coding Method for the Downlink Multi-User MIMO System

2012 ◽  
Vol 457-458 ◽  
pp. 600-606
Author(s):  
Xian Kun Gao ◽  
Yan Cui ◽  
Ji Lai Ying ◽  
Yong Chang Yu
Keyword(s):  
Numerical Simulations ◽  
Mimo System ◽  
Multiple Antennas ◽  
Poor Performance ◽  
Inversion Method ◽  
Block Diagonalization ◽  
Coding Method ◽  
Diagonalization Method ◽  
Noise Ratio ◽  
Theoretical Analyses

Recently many practical downlink multi-user MIMO linear pre-coding methods have been proposed, such as the channel inversion method and the block diagonalization method (BD). Considering the channel inversion method based on MMSE criterion (MMSE-CI) which is confined to a single receives antenna case, the BD has more advantages in multiple antennas cases, however, it has poor performance at the low and medium SNR regime on account of no consideration on the noise. In this paper, an improved MMSE pre-coding method is proposed with multi receive antennas of each user. Based on MMSE-CI, the cooperation of multiple antennas is adopted to further suppress the residual interference during designing the pre-coding matrix, which could increase the signal-to- interference-plus-noise ratio (SINR) at each user’s receiver. The proposed method obtains a better performance than the MMSE-CI and the BD algorithms, and its effectiveness is validated by both theoretical analyses and numerical simulations.

THE INFLUENCE OF SELECTED PARAMETERS ON MAGNETIC FLUID SEAL TIGHTNESS AND MOTION RESISTANCE

Tribologia ◽  
2017 ◽  
pp. 71-76 ◽  
Author(s):  
Marcin SZCZĘCH ◽  
Wojciech HORAK ◽  
Józef SALWIŃSKI
Keyword(s):  
Magnetic Field ◽  
Numerical Simulations ◽  
Field Distribution ◽  
Magnetic Fluid ◽  
High Speed ◽  
Critical Pressure ◽  
Motion Resistance ◽  
Seal Tightness ◽  
Vacuum Systems ◽  
The Magnetic Field

Magnetic fluid seals belong to the class of non-contact seals. They are used as protective seals for vacuum systems, high speed shafts, precision mechanics, and electromechanical devices. The proper functioning of the magnetic fluid seal is related to creating and maintaining the continuity of the fluid ring on the sealing stage. This is achieved by appropriately shaped magnetic field distribution in the region of the sealing stage. Consequently, one of the main issues with the construction of such seals is to determine the distribution of the magnetic field in this region. This paper presents the results of analytical calculations and numerical simulations, based on which the influence of selected geometric parameters on the critical pressure and motion resistance was determined.

Analysis of conductivity of random media using dc, MT, and TEM

Geophysics ◽  
2003 ◽  
Vol 68 (2) ◽  
pp. 506-515 ◽  
Author(s):  
Jürgen Bigalke
Keyword(s):  
Electrical Properties ◽  
Finite Difference ◽  
Numerical Simulations ◽  
Random Media ◽  
Normalization Procedure ◽  
Transient Electromagnetic ◽  
Random Lattices ◽  
Two Component ◽  
Isotropic Random

In geophysics, the geoelectric (dc), magnetotelluric (MT), and transient electromagnetic (TEM) measuring procedures are commonly used to investigate electrical properties of the ground. Finite difference codes are available for all these methods and, in this paper, the data obtained from numerical simulations are compared with regard to two‐component cubic random lattices. Provided the usage of a convenient normalization procedure, it was expected that in case of statistically homogeneous and isotropic random lattices dc, MT, and TEM would yield the same results. Surprisingly, this is not true for the MT data; the lowest MT conductivities are only one‐fifth of the corresponding TEM values.

Inversion Method for Determining Effective Thermal Conductivities of Porous Materials

1987 ◽  
Vol 109 (4) ◽  
pp. 831-834 ◽  
Author(s):  
K. Kamiuto ◽  
M. Iwamoto
Keyword(s):  
Numerical Simulations ◽  
Porous Materials ◽  
Glass Beads ◽  
Inversion Method ◽  
Temperature Profiles ◽  
Thermal Conductivities

An inversion method for determining the effective thermal conductivies of porous materials from observed mean effective thermal conductivities is presented. Its validity is confirmed by numerical simulations. The effective thermal conductivities of glass beads are determined by the proposed method successfully used to predict the temperature profiles within the glass beads.

scholarly journals Investigation of Electrical Properties of TiO2 Nanocomposite Based Polymer

2021 ◽  
Vol 2120 (1) ◽  
pp. 012031
Author(s):  
Anis Akilah Binti Ameer Ali ◽  
Hafisoh Ahmad ◽  
Hoon Yap ◽  
Hafizul Azizi Bin Ismail
Keyword(s):  
Titanium Dioxide ◽  
Electrical Properties ◽  
Electric Field ◽  
Field Distribution ◽  
Electric Field Distribution ◽  
Promising Result ◽  
Low Cost ◽  
Past Research ◽  
Host Matrix ◽  
Ethylene Propylene

Abstract Past research has reported the challenges regarding on degradation and aging due to high localization of electric field at triple point areas of polymeric insulator. The different materials and designs of polymeric insulator have initiated the partial discharge and arching activities which eventually lead to the insulation failures. The compounding of nanomaterials in the polymer shows a promising result to overcome this problem by redistributing the uniformity of electrical field lines on the insulator. In the present work, ethylene-propylene-diene rubber (EPDM) and titanium dioxide (TiO2) is introduced as nano composites that been embedded into insulator’s housing made of 1) silicone rubber (SiR) and 2) Ethylene Propylene Diene Monomer (EPDM) Rubber. Titanium dioxide (TiO2) is a semiconductor material that can be formed in different sizes either micron or nano-sized filler and has high relative permittivity that be able to reduce the high electrical stresses on high voltage equipment. Meanwhile EPDM shows good mechanical profile, excellent resistance properties and low cost. Therefore, it brings to the new opportunity to fabricate the nanocomposite based on both materials which exhibits an improved electrical properties and good distribution of electric field on polymeric outdoor insulators. In depth investigation was carried out to analyze the effect of different nano-filler loading in the compound and behavior of nanocomposites at different polymer base. An 11kV polymeric insulator is modelled to be simulated by using COMSOL Multiphysics software under dry-clean surface conditions to investigate the electric field distribution at terminal ends and along the insulator creepage path. The Electrostatics interface from the AC/DC Module is used in the evaluation of electric field distribution of insulator model correspondingly with the variations in filler percentage in the host matrix.

scholarly journals Fabrication of High-Performance CNT Reinforced Polymer Composite for Additive Manufacturing by Phase Inversion Technique

Polymers ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 4007
Author(s):  
Pooyan Parnian ◽  
Alberto D’Amore
Keyword(s):  
Additive Manufacturing ◽  
Electrical Properties ◽  
Phase Inversion ◽  
High Performance ◽  
Inversion Method ◽  
Fused Filament Fabrication ◽  
Phase Inversion Technique ◽  
Key Factor ◽  
3D Printed ◽  
Thermal And Electrical Properties

Additive Manufacturing (AM) of polymer composites has enabled the fabrication of highly customized parts with notably mechanical properties, thermal and electrical conductivity compared to un-reinforced polymers. Employing the reinforcements was a key factor in improving the properties of polymers after being 3D printed. However, almost all the existing 3D printing methods could make the most of disparate fiber reinforcement techniques, the fused filament fabrication (FFF) method is reviewed in this study to better understand its flexibility to employ for the proposed novel method. Carbon nanotubes (CNTs) as a desirable reinforcement have a great potential to improve the mechanical, thermal, and electrical properties of 3D printed polymers. Several functionalization approaches for the preparation of CNT reinforced composites are discussed in this study. However, due to the non-uniform distribution and direction of reinforcements, the properties of the resulted specimen do not change as theoretically expected. Based on the phase inversion method, this paper proposes a novel technique to produce CNT-reinforced filaments to simultaneously increase the mechanical, thermal, and electrical properties. A homogeneous CNT dispersion in a dilute polymer solution is first obtained by sonication techniques. Then, the CNT/polymer filaments with the desired CNT content can be obtained by extracting the polymer’s solvent. Furthermore, optimizing the filament draw ratio can result in a reasonable CNT orientation along the filament stretching direction.

scholarly journals Projective Synchronization of a 3D Chaotic System with Quadratic and Quartic Nonlinearities

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Babatunde Idowu ◽  
Kehinde Oyeleke ◽  
Cornelius Ogabi ◽  
Olasunkanmi Olusola
Keyword(s):  
Stability Analysis ◽  
Numerical Simulations ◽  
Chaotic System ◽  
Numerical Solutions ◽  
Initial Conditions ◽  
Three Dimensional ◽  
Scaling Factor ◽  
Projective Synchronization ◽  
Adaptive Synchronization ◽  
Dimensional System

Introduction: In this work, the projective synchronization of two identical three dimensional chaotic system with quadratic and quartic non linearities was considered as well as the equilibrium and stability analysis of the system. The projective synchronization with same and different scaling factor was carried out for this category of system to show its feasibility in order to establish that no matter the type and number of nonlinearities, projective synchronization can be achieved. Numerical simulations was done to verify the above. In all kinds of chaos synchronization, projective synchronization (PS), characterized by a scaling factor that two systems synchronize proportionally, is one of the most interesting problems. It was first reported by Mainieri et al [1] , where it was stated that the two identical systems (master and slave) could be synchronized up to a scaling factor, . They further stated that the scaling factor was dependent on the chaotic evolution and initial conditions so that the ultimate state of projective synchronization was unpredictable. Aims: Is to achieve projective synchronization of two identical three Dimensional chaotic system with quadratic and quartic nonlinearities synchronizing to a scaling factor and also present the equilibrium and stability analysis of the system. This is to establish that projective synchronization can be achieved for varied systems with varied nonlinearities. Materials and Methods: We employed the adaptive synchronization technique to achieve projective synchronization of the system (master and slave) with different scaling factors, and the fourth order RungeKutta algorithm is used for numerical solutions. Results: In this work, the projective synchronization of two identical three dimensional systems with quadratic and quartic nonlinearities was achieved with the same and different scaling factor, . The equilibrium and stability analysis of the system was also presented. Numerical simulations was done to verify the above. Conclusion: The investigated projective synchronization behaviour of two identical three-dimensional system with two nonlinearities (quadratic and quartic) was achieved for cases where the scaling factor is the same and when different. This shows that projective synchronization can be achieved for systems with varying nonlinearities even when the scaling factor is different and this suggests its use in communication using chaotic wave forms as carriers, perhaps with a view to securing communication.

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