Modeling and Analysis of Effective Electromagnetic Parameters of Capillary System of Agricultural Soils Electric Conductivity. Low-Frequency Resonances in Empty Cylinders of Circular Section with Ideal Surface Conductivity Along Helices

2018 ◽  
Vol 50 (10) ◽  
pp. 77-83
Author(s):  
Alexander A. Brovarets ◽  
Yuriy V. Chovnyuk
Keyword(s):  
Electric Conductivity ◽  
Agricultural Soils ◽  
Low Frequency ◽  
Surface Conductivity ◽  
Electromagnetic Parameters ◽  
Circular Section ◽  
Modeling And Analysis ◽  
Capillary System

Effects of variable thermal conductivity and electrical conductivity on flow of williamson nanofluid between two parallel disks

2021 ◽  
Author(s):  
Mazmul Hussain ◽  
Nargis Khan
Keyword(s):  
Thermal Conductivity ◽  
Differential Equations ◽  
Electric Conductivity ◽  
Variable Temperature ◽  
Lewis Number ◽  
Variable Thermal Conductivity ◽  
Industrial Applications ◽  
Weissenberg Number ◽  
Modeling And Analysis ◽  
Variable Nature

The variable nature of the thermal conductivity of nanofluid with respect to temperature plays an important role in many engineering and industrial applications including solar collectors and thermoelectricity. Thus, the foremost motivation of this article is to investigate the effects of thermal conductivity and electric conductivity due to variable temperature on the flow of Williamson nanofluid. The flow is considered between two stretchable rotating disks. The mathematical modeling and analysis have been made in the presence of magnetohydrodynamic and thermal radiation. The governing differential equations of the problem are transformed into non-dimensional differential equations by using similarity transformations. The transformed differential equations are thus solved by a finite difference method. The behaviors of velocity, temperature and concentration profiles due to various parameters are discussed. For magnetic parameter, the radial and tangential velocities have showed decreasing behavior, while converse behavior is observed for axial velocity. The temperature profile shows increasing behavior due to an increase in the Weissenberg number, heat generation parameter and Eckert number, while it declines by increasing electric conductivity parameter. The nanoparticle concentration profile declines due to an increase in the Lewis number and Reynolds number.

Modeling and Design of an Inertial Vibration Reflector

1997 ◽  
Vol 119 (1) ◽  
pp. 20-27
Author(s):  
R. G. Longoria ◽  
V. A. Narayanan
Keyword(s):  
Vibration Suppression ◽  
Active Vibration Control ◽  
Low Frequency ◽  
Dominant Frequency ◽  
Prototype System ◽  
Primary System ◽  
Transient Vibration ◽  
Modeling And Analysis ◽  
Reflector System ◽  
Oriented Parallel

This paper presents the modeling and analysis of a novel vibration suppression device. This reflector system exerts inertial forces, induced by tuned pendular motion, to control translational vibration of a primary system. Tuning of the reflector critically depends on the parameters of the pendula and on the rotational speed at which they are spun about an axis oriented parallel to the undesired motion. Consequently, one of its most appealing attributes is this devices’s ability to be tuned to, and thus actively track, the dominant frequency of disturbance forces. The paper describes how governing equations from an integrated physical model are developed using a bond graph approach and then used to derive relations applicable in design of an inertial reflector system. It is shown how the model supports component selection and tradeoff studies as well as simulation. Experimental results from testing of a laboratory realization of a prototype system are used to verify the design and to compare with simulation of a mathematical model. The results from the laboratory demonstrate the ability of the inertial reflector to control steady and transient vibration, and the favorable results suggest extended investigation for active vibration control situations. In particular, applications in low frequency vibration mitigation are promising.

Characterization and Design of Honeycomb Absorbing Materials

2019 ◽  
Vol 294 ◽  
pp. 51-56
Author(s):  
Hui Min Sun ◽  
Le Chen ◽  
Zhao Zhan Gu
Keyword(s):  
Double Layer ◽  
Low Frequency ◽  
Single Layer ◽  
Electromagnetic Parameters ◽  
Honeycomb Sandwich ◽  
Absorbing Materials ◽  
Absorbing Material ◽  
The Difference ◽  
Free Space Method ◽  
Honeycomb Sandwich Structure

Honeycomb absorbing materials are anisotropic structural materials. Depending on the size of honeycomb lattices, the absorbent content of the impregnated layer is different, the thickness of the impregnated layer is different, and the absorbing function of the impregnated honeycomb absorbing materials is also different. For the characterization of electromagnetic parameters of honeycomb absorbing materials, this paper adopts free space method for testing, uses CST software for modeling, and inverts the electromagnetic parameters of honeycomb absorbing structures. The absorbing performance of single-layer and double-layer honeycomb sandwich structures was simulated by RAM Optimizer software. The research shows that the height of the single-layer honeycomb absorbing material is 22mm. When the absorber content is 65%, 75% and 85% respectively, the harmonic peak moves slightly to the low frequency electromagnetic wave with the increase of the absorber content, but the absorbing strength decreases with the increase of the absorber content. For the double-layer honeycomb sandwich structure, the difference of absorber content in the upper and lower honeycomb absorbing materials is smaller, and the absorbing performance is stronger. When the thickness of the wave-transparent panel is thinner, the harmonic peak of the absorbing curve moves slightly to the high frequency.

Low-frequency electrical conductivity of aqueous kaolinite suspensions: surface conductance, electrokinetic potentials and counterion mobility

Clay Minerals ◽  
2017 ◽  
Vol 52 (3) ◽  
pp. 299-313 ◽  
Author(s):  
Christian Weber ◽  
Helge Stanjek
Keyword(s):  
Charge Density ◽  
Surface Charge Density ◽  
Volume Fraction ◽  
Low Frequency ◽  
Surface Conductivity ◽  
Evaluation Procedure ◽  
Surface Conductance ◽  
Consistency Check ◽  
Data Set ◽  
First Time

AbstractThe low-frequency conductivity of aqueous kaolinite suspensions has been measured as a function of volume fraction and concentration of KCl, K2SO4and BaCl2, respectively. These measurements were interpreted with a theoretical model accounting for surface conductivity and particle shape. For the first time, an internally consistent data set was established by measuring all parameters necessary to solve the relevant equations. The simultaneous availability of surface conductivity, surface charge density and diffuse layer charge density permitted the estimation of counterion mobilities in the stagnant layer and a consistency check for the evaluation procedure of the conductivity experiments. In agreement with current literature results, monovalent counterions were found to have a Stern layer mobility similar to their bulk mobility, whereas the mobility of divalent counterions in this layer is reduced by a factor of ∼2.

scholarly journals Electromechanical coupling dynamic modeling and analysis of vertical electrodynamic shaker considering low frequency lateral vibration

2020 ◽  
Vol 12 (10) ◽  
pp. 168781402096385
Author(s):  
Shuguang Zuo ◽  
Zhaoyang Feng ◽  
Jian Pan ◽  
Xudong Wu
Keyword(s):  
Dynamic Model ◽  
Electromechanical Coupling ◽  
Low Frequency ◽  
Coupling Model ◽  
Vertical Position ◽  
Force Model ◽  
Lateral Vibration ◽  
Modeling And Analysis ◽  
Electrodynamic Shaker ◽  
Coupling Dynamic

For the problem of relatively severe lateral vibration found in the vertical electrodynamic shaker experiment, an electromechanical coupling dynamic model of the electrodynamic shaker considering low-frequency lateral vibration is proposed. The reason and mechanism of the lateral vibration is explained and analyzed through this model. To establish this model, an electromagnetic force model of overall conditions is firstly built by fitting force samples with neural network method. The force samples are obtained by orthogonal test of finite element simulation, in which five factors of the moving coil including current, vertical position, flipping eccentricity angle, radial translational eccentric direction and distance are considered. Secondly, a 7-dof dynamic model of the electrodynamic shaker is developed with the consideration of the lateral vibration of the moving system. To obtain the transfer function accurately, the stiffness and damping parameters are identified. Finally, an electromechanical dynamic model is established by coupling the force model and the 7-dof dynamic model, and it is verified by experiments. The coupling model proposed can be further used for the control and optimization of the electrodynamic shaker.

Modeling and Analysis of Ultra-Low Frequency Dynamics of Drag-Free Satellites

2019 ◽  
Vol 31 (2) ◽  
pp. 151-160 ◽  
Author(s):  
Jiaxing Zhou ◽  
Lei Liu ◽  
Zhigang Wang
Keyword(s):  
Low Frequency ◽  
Modeling And Analysis

The Influence of Salt Concentration in Injected Water on Low-Frequency Electrical-Heating-Assisted Bitumen Recovery

SPE Journal ◽  
2011 ◽  
Vol 16 (03) ◽  
pp. 548-558 ◽  
Author(s):  
I.I.. I. Bogdanov ◽  
J.A.. A. Torres ◽  
H.A.. A. Akhlaghi ◽  
A.M.. M. Kamp
Keyword(s):  
Electric Conductivity ◽  
Oil Recovery ◽  
Salt Concentration ◽  
Salt Water ◽  
Low Frequency ◽  
Water Circulation ◽  
Electrical Heating ◽  
Simple Problem ◽  
Field Scale ◽  
Bitumen Recovery

Summary Steam injection is often not a good alternative for oil recovery from shallow bitumen reservoirs. For instance, the thin caprock creates the danger of steam breakthrough. For deeper reservoirs, the heat losses from injection wells may be prohibitive. A technology that may be better suited is oil recovery aided by low-frequency electrical heating of the reservoir. This technology, well known for environmental remedial applications, has been field tried recently, yielding promising results. The process uses electric conductivity of connate water to propagate an alternating current between electrodes, inducing the Joule heating of the reservoir. An associated problem is the appearance of hot spots around the electrodes that may be relieved by water circulation. However, the water circulation may have a significant effect on the heating process because the electric conductivity of the circulated water depends on its salt content. To find out the influence of salt concentration on process efficiency, we have studied the process of salt-water recirculation around an electrode using numerical simulation. The physical properties and operational data for Athabasca bitumen have been collected from the literature. The model built with Computer Modelling Group's STARS simulator and tested first with available analytical solutions has been validated, and the proper choice of the underlying grid and numerical tuning parameters has been verified. The process was also simulated at field scale for a common pattern of electrodes and production wells. The salt penetrated into the reservoir, far beyond the major water-circulation zone around the electrodes. This process increases the electric conductivity in a large region between electrodes, which improves the heating of the reservoir. The single-electrode simulation studies using different tools yielded similar results for a simple problem. More-complex (and more-realistic) field-scale simulations show that adding salt enhances the oil production. In practice, an upper concentration limit may be given by corrosion problems at the electrodes. The reservoir simulation of bitumen recovery assisted by low-frequency heating is a challenging multiphysics problem. The understanding of the influence of salt concentration on the circulated water provided by this work is an important key in process-design considerations.

Detection and imaging of electric conductivity and permittivity at low frequency

1991 ◽  
Vol 38 (11) ◽  
pp. 1106-1110 ◽  
Author(s):  
L.F. Fuks ◽  
M. Cheney ◽  
D. Isaacson ◽  
D.G. Gisser ◽  
J.C. Newell
Keyword(s):  
Electric Conductivity ◽  
Low Frequency
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