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Mercadal, Borja, Ricardo Salvador, Maria Chiara Biagi, Fabrice Bartolomei, Fabrice Wendling, and Giulio Ruffini. "Modeling implanted metals in electrical stimulation applications." Journal of Neural Engineering 19, no. 2 (March 8, 2022): 026003. http://dx.doi.org/10.1088/1741-2552/ac55ae.
Повний текст джерелаАнотація:
Abstract Objective. Metal implants impact the dosimetry assessment in electrical stimulation techniques. Therefore, they need to be included in numerical models. While currents in the body are ionic, metals only allow electron transport. In fact, charge transfer between tissues and metals requires electric fields to drive electrochemical reactions at the interface. Thus, metal implants may act as insulators or as conductors depending on the scenario. The aim of this paper is to provide a theoretical argument that guides the choice of the correct representation of metal implants in electrical models while considering the electrochemical nature of the problem Approach. We built a simple model of a metal implant exposed to a homogeneous electric field of various magnitudes. The same geometry was solved using two different models: a purely electric one (with different conductivities for the implant), and an electrochemical one. As an example of application, we also modeled a transcranial electrical stimulation (tES) treatment in a realistic head model with a skull plate using a high and low conductivity value for the plate. Main results. Metal implants generally act as electric insulators when exposed to electric fields up to around 100 V m−1 and they only resemble a perfect conductor for fields in the order of 1000 V m−1 and above. The results are independent of the implant’s metal, but they depend on its geometry. tES modeling with implants incorrectly treated as conductors can lead to errors of 50% or more in the estimation of the induced fields Significance. Metal implants can be accurately represented by a simple electrical model of constant conductivity, but an incorrect model choice can lead to large errors in the dosimetry assessment. Our results can be used to guide the selection of the most appropriate model in each scenario.
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Akinsanmi, Olaitan, B. A. Adegboye, G. A. Olarinoye, and M. B. Soroyewun. "Neuro-Fuzzy Based Modeling of Electrostatic Fields for Harmattan Season in Zaria." International Journal of Engineering Research in Africa 4 (May 2011): 75–85. http://dx.doi.org/10.4028/www.scientific.net/jera.4.75.
Повний текст джерелаАнотація:
This paper presents a Neuro-Fuzzy based modeling of electrostatic fields for harmattan season in Zaria, Nigeria based on online based data capturing mechanism, which involved the use of a data acquisition system interfaced with a digital electrostatic field strength meter (model 257D) and a computer system. The acquired electric field data were captured by the computer using the Microsoft Office Excel Program for twenty-four months (February 2007 – February 2009). The focus of the analysis is determining the effect of environmental factors such as temperature, pressure and relative humidity on the static electric field during the harmattan season. The plots of the electrostatic field against the variation of the environmental factors were used as the qualitative analytical tools and yielded a non-linear relationship. The data was analyzed using Neuro-Fuzzy technique, which is a hybrid intelligent system combining the benefits of computational techniques of Fuzzy Logic and Artificial Neural Networks. The result of the analyses yielded good neural statistical values of Root Mean Square (RMS) of 0.32, Average Absolute Error of 0.18, and Pearson R value of 0.96 for the harmattan scenario, which are reflections of a good model. The result was further buttressed by the 3D plot of the Neuro-Fuzzy based modeling of the experimental parameters. With the insignificant values of the RMS and Average Absolute value, the empirical model gave a fairly good prediction which could be relied upon to predict the electrostatic fields during harmattan in Zaria, Nigeria.
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Tang, Zi Rong, M. Rizwan Malik, Tie Lin Shi, J. Gong, L. Nie, and Guang Lan Liao. "Modelling and Fabrication of 3-D Carbon-MEMS for Dielectrophoretic Manipulation of Micro/Nanoparticles in Fluids." Materials Science Forum 628-629 (August 2009): 435–40. http://dx.doi.org/10.4028/www.scientific.net/msf.628-629.435.
Повний текст джерелаАнотація:
Carbon-MEMS (C-MEMS) have emerged as a new category of devices for micro/nano technology with many potential applications. Dielectrophoretic manipulation of micro/nanoparticles with C-MEMS is studied in this paper. Through electric field distribution modeling in carbon electrode array, we analyze the strongest simulation effect results of electric field in three dimensional (3-D) surface plots depicting the magnitude of electric field in various cross sections at different heights above the channel floor for 2, 10, 30 and 50 μm high carbon electrodes. It is represented here that maximum intensity of electric field generates with the equality between the height above the channel floor and the height of the electrodes. Simulation parameters involved are for dielectrophoretic manipulation of micro/nano particles based on 3-D C-MEMS. The advantages of using 3-D C-MEMS electrodes over other techniques of creating high-throughput systems for dielectrophoretic manipulation environment surrounded by micro/nano horizons are: (i) complex microscale 3-D electrodes with high-aspect ratios can easily be shaped and patterned using conventional lithography (ii) carbon has a high window of stability thus allowing application of higher voltages (iii) there is no need for bulk micromachining or patterning electrodes on multiple planes (iv) the distance between electrodes can precisely be controlled through the lithography process. FEMLAB 3.4 Multiphysics Modeling software (COMSOL, Stockholm, Sweden) is used for the modeling of electric fields and one-layer C-MEMS microelectrode array was fabricated with SU-8 photoresist.
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Jörgens, Christoph, and Markus Clemens. "A Review about the Modeling and Simulation of Electro-Quasistatic Fields in HVDC Cable Systems." Energies 13, no. 19 (October 5, 2020): 5189. http://dx.doi.org/10.3390/en13195189.
Повний текст джерелаАнотація:
In comparison to high-voltage alternating current (HVAC) cable systems, high-voltage direct current (HVDC) systems have several advantages, e.g., the transmitted power or long-distance transmission. The insulating materials feature a non-linear dependency on the electric field and the temperature. Applying a constant voltage, space charges accumulate in the insulation and yield a slowly time-varying electric field. As a complement to measurements, numerical simulations are used to obtain the electric field distribution inside the insulation. The simulation results can be used to design HVDC cable components such that possible failure can be avoided. This work is a review about the simulation of the time-varying electric field in HVDC cable components, using conductivity-based cable models. The effective mechanisms and descriptions of charge movement result in different conductivity models. The corresponding simulation results of the models are compared against measurements and analytic approximations. Different numerical techniques show variations of the accuracy and the computation time that are compared. Coupled electro-thermal field simulations are applied to consider the environment and its effect on the resulting electric field distribution. A special case of an electro-quasistatic field describes the drying process of soil, resulting from the temperature and electric field. The effect of electro-osmosis at HVDC ground electrodes is considered within this model.
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Wijewardena Gamalath, K. A. I. L., and A. M. Samarakoon. "Modeling of Planar Plasma Diode." International Letters of Chemistry, Physics and Astronomy 13 (September 2013): 220–42. http://dx.doi.org/10.18052/www.scipress.com/ilcpa.13.220.
Повний текст джерелаАнотація:
To investigate the dynamics of a planar plasma diode system (PDS), a model based on the current density equilibrium at the interface was developed. The current densities and plasma boundary variations with the potential fields were obtained by simulating a single square pulse. The variation of an observed overshoot current density with the applied voltage is presented. Planar plasma diode system was also simulated for periodic, sine, square, triangular and saw tooth voltage patterns by varying the amplitude and frequencies. A method to find the lower bound of the electron density of plasma for a specified PDS is presented. Particle-In-Cell simulation technique was used to investigate the plasma particles and electric field distributions over the anode cathode gap for different intensities of external electric fields. The system became stable after few time steps and this time depends upon the intensity and polarization of the external field.
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Gavin, H. P., R. D. Hanson, and F. E. Filisko. "Electrorheological Dampers, Part II: Testing and Modeling." Journal of Applied Mechanics 63, no. 3 (September 1, 1996): 676–82. http://dx.doi.org/10.1115/1.2823349.
Повний текст джерелаАнотація:
Electrorheological (ER) materials develop yield stresses on the order of 5–10 kPa in the presence of strong electric fields. Viscoelastic and yielding material properties can be modulated within milli-seconds. An analysis of flowing ER materials in the limiting case of fully developed steady flow results in simple approximations for use in design. Small-scale experiments show that these design equations can be applied to designing devices in which the flow is unsteady. More exact models of ER device behavior can be determined using curve-fitting techniques in multiple dimensions. A previously known curve-fitting technique is extended to deal with variable electric fields. Experiments are described which illustrate the potential for ER devices in large-scale damping applications and the accuracy of the modeling technique.
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Kurbanismailov, Z. M., A. T. Tarlanov, and E. M. Akimov. "The technique of point visualization of the electric field in space and time." Russian Technological Journal 9, no. 3 (June 28, 2021): 58–65. http://dx.doi.org/10.32362/2500-316x-2021-9-3-58-65.
Повний текст джерелаАнотація:
Testing of electronic devices is an integral part of the technological process of any manufacturer of such equipment. In this case, an electronic device is understood as an energy-intensive unit such as a mobile phone, data center or spacecraft. One of the key stages of testing is to identify the effect of electric fields on various electronic components of the device. This stage often requires making a mock-up of some part of an unfinished device in order to fix interference with special equipment. This requires time, financial and human resource costs. In order to reduce these costs in the modern world, the use of mathematical modeling tools for testing noise immunity and electromagnetic compatibility is becoming popular. In this paper, it is proposed to use an algorithm for visualizing electric fields in three-dimensional space and time. The algorithm is easily embedded into applications as a component of a mathematical modeling system. The work considered three ways of visualizing the electric field strength: starting from a simple setting of points in space, on the basis of which the electric field will be built, around the source of electric field radiation, to the use of algorithms that make it possible to arrange points equidistantly based on a given number of points in space for the formation of an electric field. The performance and visual implications of these methods were analyzed. The proposed methodology will be useful to the developer community as an embedded solution for point visualization of the electric field in any project in any algorithmic language with the ability to animate in time.
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Brown, Thomas S., Tonatiuh Sánchez-Vizuet, and Francisco-Javier Sayas. "Evolution of a semidiscrete system modeling the scattering of acoustic waves by a piezoelectric solid." ESAIM: Mathematical Modelling and Numerical Analysis 52, no. 2 (March 2018): 423–55. http://dx.doi.org/10.1051/m2an/2017045.
Повний текст джерелаАнотація:
We consider a model problem of the scattering of linear acoustic waves in free homogeneous space by an elastic solid. The stress tensor in the solid combines the effect of a linear dependence of strains with the influence of an existing electric field. The system is closed using Gauss’s law for the associated electric displacement. Well-posedness of the system is studied by its reformulation as a first order in space and time differential system with help of an elliptic lifting operator. We then proceed to studying a semidiscrete formulation, corresponding to an abstract Finite Element discretization in the electric and elastic fields, combined with an abstract Boundary Element approximation of a retarded potential representation of the acoustic field. The results obtained with this approach improve estimates obtained with Laplace domain techniques. While numerical experiments illustrating convergence of a fully discrete version of this problem had already been published, we demonstrate some properties of the full model with some simulations for the two dimensional case.
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Poikonen, Ari, and Ilkka Suppala. "On modeling airborne very low‐frequency measurements." GEOPHYSICS 54, no. 12 (December 1989): 1596–606. http://dx.doi.org/10.1190/1.1442627.
Повний текст джерелаАнотація:
Numerical models employed in ground VLF modeling use a normally incident (homogeneous) plane wave as a primary field. We show that these models are not directly applicable to modeling the impedance and wavetilt in the air, quantities needed in the interpretation of airborne VLF resistivity measurements. Instead, the primary field must be replaced by an inhomogeneous plane wave incident on the ground at an angle close to 90 degrees in order to provide the correct behavior of the apparent resistivities in the air. VLF magnetic polarization parameters, however, can be modeled in the air using the normally incident plane wave as a primary field. We also show that the plane‐wave analysis provides the same attenuation characteristics for the wavetilt in the air that is predicted by the Norton’s surface wave obtained by using the vertical electric dipole as a source. Use of the inhomogeneous plane wave introduces the vertical component of the electric field in the model. A 2‐D modeling technique based on the network solution is used to demonstrate the effects of the vertical electric field in the H‐polarization case. The vertical electric field generates charge distributions on the horizontal boundaries of conductors. In the case of a vertical sheet‐like conductor, these charges cause a slight asymmetry in apparent‐resistivity anomalies. Attenuation characteristics of various VLF anomalies with altitude are also presented. The H‐polarization anomalies attenuate much more rapidly in the air than those for E‐polarization due to the difference in the dominating source of EM fields in each polarization.
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Shi, Yun Fei, and Jun Liu. "Multi-Physics Modeling and Simulation of Electro-Optical Sensing." Advanced Materials Research 1092-1093 (March 2015): 292–95. http://dx.doi.org/10.4028/www.scientific.net/amr.1092-1093.292.
Повний текст джерелаАнотація:
With the rapid development of UHV technology, Electric field measurement technique has attracted lots of people's attention.Electro-optical sensors for measuring the electric field to become the main method due to the crystal optical fiber preparation and mature technology. This article describes the basic principles that Mach - Zehnder of lithium niobate optical modulator for electric field measurements.Designing the Mach - Zehnder electro-optic sensors in the Comsol Multiphysics oftware, the calculation model for the simulation results of bending radius that the optical waveguide transmission power loss minimum, a 3dB directional coupler to determine the length of the arm and finally adding a signal voltage, the applied voltage is obtained a linear relationship between the output power.
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Amanatiadis, Stamatios, Theodoros Zygiridis, and Nikolaos Kantartzis. "Accurate Time-Domain Modeling of Arbitrarily Shaped Graphene Layers Utilizing Unstructured Triangular Grids." Axioms 11, no. 2 (January 22, 2022): 44. http://dx.doi.org/10.3390/axioms11020044.
Повний текст джерелаАнотація:
The accurate modeling of curved graphene layers for time-domain electromagnetic simulations is discussed in the present work. Initially, the advanced properties of graphene are presented, focusing on the propagation of strongly confined surface plasmon polariton waves at the far-infrared regime. Then, the implementation of an unstructured triangular grid was examined, based on the Delaunay triangulation method. The electric-field components were placed at the edges of the triangles, while two different techniques were proposed for the sampling of the magnetic ones. Specifically, the first one suggests that the magnetic component is placed at the triangle’s circumcenter providing more accurate results, although instability may occur for nonacute triangles. On the other hand, the magnetic field was sampled at the triangle’s centroid, considering the second technique, ensuring the algorithm’s stability, but further approximations were required, leading to a slight accuracy reduction. Moreover, the updating equations in the time-domain were extracted via an appropriate approximation of Maxwell equations in their integral form. Finally, graphene was introduced in the computational domain as an equivalent surface current density, whose location matches the corresponding electric components. The validity of our methodology was successfully performed via the comparison of graphene surface wave propagation properties to their theoretical values, whereas the global error determination indicates the minimal triangle dimensions. Additionally, an instructive setup comprising a circular graphene scatterer was analyzed thoroughly, to reveal our technique’s advantages compared to the conventional staircase discretization.
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Roberts, Roger L., and Jeffrey J. Daniels. "Modeling near‐field GPR in three dimensions using the FDTD method." GEOPHYSICS 62, no. 4 (July 1997): 1114–26. http://dx.doi.org/10.1190/1.1444212.
Повний текст джерелаАнотація:
Complexities associated with the theoretical solution of the near‐field interaction between the fields radiated from dipole antennas placed near a dielectric half‐space and electrical inhomogeneities within the dielectric can be overcome by using numerical techniques. The finite‐difference time‐domain (FDTD) technique implements finite‐difference approximations of Maxwell's equations in a discretized volume that permit accurate computation of the radiated field from a transmitting antenna, propagation through the air‐earth interface, scattering by subsurface targets and reception of the scattered fields by a receiving antenna. In this paper, we demonstrate the implementation of the FDTD technique for accurately modeling near‐field time‐domain ground‐penetrating radar (GPR). This is accomplished by incorporating many of the important GPR parameters directly into the FDTD model. These variables include: the shape of the GPR antenna, feed cables with a fixed characteristic impedance attached to the terminals of the antenna, the height of the antenna above the ground, the electrical properties of the ground, and the electrical properties and geometry of targets buried in the subsurface. FDTD data generated from a 3-D model are compared to experimental antenna impedance data, field pattern data, and measurements of scattering from buried pipes to verify the accuracy of the method.
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Ruihan, Xu, Bao Weijie, Wang Zhihai, and Wang Yaohong. "Start-up stage with improved resolution for an electric field-assisted fused deposition." RSC Advances 11, no. 13 (2021): 7397–404. http://dx.doi.org/10.1039/d0ra07795j.
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Classen, C., E. Gjonaj, U. Römer, R. Schuhmann, and T. Weiland. "Modeling of field singularities at dielectric edges using grid based methods." Advances in Radio Science 9 (July 29, 2011): 39–44. http://dx.doi.org/10.5194/ars-9-39-2011.
Повний текст джерелаАнотація:
Abstract. Electric field singularities at sharp metallic edges or at a dielectric contact line can be described analytically by asymptotic expressions. The a priori known form of the field distribution in the vicinity of these edges can be used to construct numerical methods with improved accuracy. This contribution focuses on a modified Finite Integration Technique and on a Discontinuous Galerkin Method with singular approximation functions. Both methods are able to handle field singularities at perfectly electric conducting as well as at dielectric edges. The numerical accuracy of these methods is investigated in a number of simulation examples including static and dynamic field problems.
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Remley, K. A., A. Weisshaar, V. K. Tripathi, and S. M. Goodnick. "Modeling of Radiation Fields in a Sub-Picosecond Photo-Conducting System." VLSI Design 8, no. 1-4 (January 1, 1998): 407–12. http://dx.doi.org/10.1155/1998/10832.
Повний текст джерелаАнотація:
FDTD and Monte Carlo methods are combined to simulate the terahertz radiation from a coplanar photoconducting structure. The simulation tool under consideration allows calculation of potentials, particle distributions, current densities, and the near field electromagnetic fields anywhere in the computational domain. To model the far field radiation, it is not efficient nor, in many cases, physically possible at present to use the FDTD technique directly because of the excessive computational burden. Techniques are discussed for modeling both the near field and the far field radiation. Computational results showing the far field radiation are in qualitative agreement with published experimental results.
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Ren, Zhengyong, Thomas Kalscheuer, Stewart Greenhalgh, and Hansruedi Maurer. "A finite-element-based domain-decomposition approach for plane wave 3D electromagnetic modeling." GEOPHYSICS 79, no. 6 (November 1, 2014): E255—E268. http://dx.doi.org/10.1190/geo2013-0376.1.
Повний текст джерелаАнотація:
We developed a novel parallel domain-decomposition approach for 3D large-scale electromagnetic induction modeling in the earth. We used the edge-based finite-element method and unstructured meshes. Unstructured meshes were divided into sets of nonoverlapping subdomains. We used the curl-curl electric field equation to carry out the analysis. In each subdomain, the electric field was discretized by first-order vector shape functions along the edges of tetrahedral elements. The tangential components of the magnetic field on the interfaces of the subdomains were defined as a set of Lagrange multipliers. The unknown Lagrange multipliers were solved from an interface problem defined on the interfaces of the subdomains. With the availability of the Lagrange multipliers, the electric field values in each subdomain were solved independently. Three synthetic examples were evaluated to verify our code. Excellent agreement with previously published solutions was obtained. Synthetic examples revealed that our domain decomposition technique is scalable with respect to the number of subdomains and robust with regard to frequency and the heterogeneous distribution of material parameters, i.e., electric conductivity, electric permittivity, and magnetic permeability.
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Lee, K. H., and H. F. Morrison. "A solution for TM‐mode plane waves incident on a two‐dimensional inhomogeneity." GEOPHYSICS 50, no. 7 (July 1985): 1163–65. http://dx.doi.org/10.1190/1.1441989.
Повний текст джерелаАнотація:
Quantitative interpretation of magnetotelluric (MT) surveys depends at present on the availability of an efficient forward modeling algorithm. To date, two major numerical techniques have been used to obtain the scattered fields from buried inhomogeneities in plane‐wave fields: methods solving the governing differential equation which generally uses a finite‐element or finite‐difference approach, and methods which solve an integral‐equation formulation of the problem. For two‐dimensional (2-D) inhomogeneities a solution for incident fields with the electric field parallel to the strike of the inhomogeneity (TE mode solution) was developed by Hohmann (1971) using the integral‐equation approach. For a perfect conductor an integral formulation, for surface scattering currents, for the TM mode (magnetic field parallel to the strike of the inhomogeneity) was developed by Parry (1969). General 2-D solutions in the presence of an arbitrary mode plane wave (mixed TE-TM) were obtained by Ryu (1970), Swift (1971), and Rijo (1977) using either a finite‐element or finite‐difference technique.
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Gallinato, Olivier, Baudouin Denis de Senneville, Olivier Seror, and Clair Poignard. "Numerical modelling challenges for clinical electroporation ablation technique of liver tumors." Mathematical Modelling of Natural Phenomena 15 (2020): 11. http://dx.doi.org/10.1051/mmnp/2019037.
Повний текст джерелаАнотація:
Electroporation ablation is a promising non surgical and minimally invasive technique of tumor ablation, for which no monitoring is currently available. In this paper, we present the recent advances and challenges on the numerical modeling of clinical electroporation ablation of liver tumors. In particular, we show that a nonlinear static electrical model of tissue combined with clinical imaging can give crucial information of the electric field distribution in the clinical configuration. We conclude the paper by presenting some important questions that have to be addressed for an effective impact of computational modeling in clinical practice of electroporation ablation.
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Fellner, Andreas, Amirreza Heshmat, Paul Werginz, and Frank Rattay. "A finite element method framework to model extracellular neural stimulation." Journal of Neural Engineering 19, no. 2 (April 1, 2022): 022001. http://dx.doi.org/10.1088/1741-2552/ac6060.
Повний текст джерелаАнотація:
Abstract Objective. Increasing complexity in extracellular stimulation experiments and neural implant design also requires realistic computer simulations capable of modeling the neural activity of nerve cells under the influence of an electrical stimulus. Classical model approaches are often based on simplifications, are not able to correctly calculate the electric field generated by complex electrode designs, and do not consider electrical effects of the cell on its surrounding. A more accurate approach is the finite element method (FEM), which provides necessary techniques to solve the Poisson equation for complex geometries under consideration of electrical tissue properties. Especially in situations where neurons experience large and non-symmetric extracellular potential gradients, a FEM solution that implements the cell membrane model can improve the computer simulation results. To investigate the response of neurons in an electric field generated by complex electrode designs, a FEM framework for extracellular stimulation was developed in COMSOL. Approach. Methods to implement morphologically- and biophysically-detailed neurons including active Hodgkin-Huxley (HH) cell membrane dynamics as well as the stimulation setup are described in detail. Covered methods are (a) development of cell and electrode geometries including meshing strategies, (b) assignment of physics for the conducting spaces and the realization of active electrodes, (c) implementation of the HH model, and (d) coupling of the physics to get a fully described model. Main results. Several implementation examples are briefly presented: (a) a full FEM implementation of a HH model cell stimulated with a honeycomb electrode, (b) the electric field of a cochlear electrode placed inside the cochlea, and (c) a proof of concept implementation of a detailed double-cable cell membrane model for myelinated nerve fibers. Significance. The presented concepts and methods provide basic and advanced techniques to realize a full FEM framework for innovative studies of neural excitation in response to extracellular stimulation.
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Tandberg, Erik, Peter J. Schultz, Geof C. Aers, and T. E. Jackman. "Defect profiling of semiconductor epilayers using positron beams." Canadian Journal of Physics 67, no. 4 (April 1, 1989): 275–82. http://dx.doi.org/10.1139/p89-048.
Повний текст джерелаАнотація:
Over the last 10 years, positrons have been used as a tool to study and profile dilute concentrations of defects in solids. The two basic techniques involve the measurement of the positron lifetime and the Doppler broadening of the annihilation γ-rays. Only recently have positrons been used to profile defects in multilayered structures. We review the theory of positron–defect interactions and positron transport in silicon, and introduce a model used to profile defects and electric-field effects using the steady-state diffusion equation. An example is discussed that involves the modelling of defects and electric fields in homoepitaxial layers of silicon grown by molecular-beam epitaxy on Si(100) substrates. Finally we discuss the limitations of the modelling technique and future prospects.
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Nicolls, M. J., M. C. Kelley, M. N. Vlasov, Y. Sahai, J. L. Chau, D. L. Hysell, P. R. Fagundes, F. Becker-Guedes, and W. L. C. Lima. "Observations and modeling of post-midnight uplifts near the magnetic equator." Annales Geophysicae 24, no. 5 (July 3, 2006): 1317–31. http://dx.doi.org/10.5194/angeo-24-1317-2006.
Повний текст джерелаАнотація:
Abstract. We report here on post-midnight uplifts near the magnetic equator. We present observational evidence from digital ionosondes in Brazil, a digisonde in Peru, and other measurements at the Jicamarca Radio Observatory that show that these uplifts occur fairly regularly in the post-midnight period, raising the ionosphere by tens of kilometers in the most mild events and by over a hundred kilometers in the most severe events. We show that in general the uplifts are not the result of a zonal electric field reversal, and demonstrate instead that the uplifts occur as the ionospheric response to a decreasing westward electric field in conjunction with sufficient recombination and plasma flux. The decreasing westward electric field may be caused by a change in the wind system related to the midnight pressure bulge, which is associated with the midnight temperature maximum. In order to agree with observations from Jicamarca and Palmas, Brazil, it is shown that there must exist sufficient horizontal plasma flux associated with the pressure bulge. In addition, we show that the uplifts may be correlated with a secondary maximum in the spread-F occurrence rate in the post-midnight period. The uplifts are strongly seasonally dependent, presumably according to the seasonal dependence of the midnight pressure bulge, which leads to the necessary small westward field in the post-midnight period during certain seasons. We also discuss the enhancement of the uplifts associated with increased geomagnetic activity, which may be related to disturbance dynamo winds. Finally, we show that it is possible using simple numerical techniques to estimate the horizontal plasma flux and the vertical drift velocity from electron density measurements in the post-midnight period.
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Abd Karim, Kasrul, N. Abdullah, M. Nazri Othman, Auzani Jidin, and RN Firdaus. "Modeling of 6 to 4 Switched Reluctance Motor using Coefficient Method and Analytical Method." Indonesian Journal of Electrical Engineering and Computer Science 7, no. 2 (August 1, 2017): 373. http://dx.doi.org/10.11591/ijeecs.v7.i2.pp373-380.
Повний текст джерелаАнотація:
Electric kick scooter field has become famous this lately, and become another solution for electric vehicle. Switched Reluctance Motor has been choosen as the propulsion system in this application due to the advantages of this motor. Meanwhile, the issue of lack experience in electrical motor design is one of the hollow subjects in machine design field. Through design aspects, the Switched Reluctance motor is developed using a simple technique which is coefficients method. This method is to provide the easiest ways for other non-academic designer for those who has lack experience in motor design. A set of a coefficient to determine motor dimension is being set. Then, this technique will be refered to the existing analytical method to provide a design guideline and to validate this coefficient as the quick references to design the SRM. The aim is not to make a comparison between the methods but intend to provide another easiest solution to design the SRM motor. The modelling has been test using RMxprt tools The expectation from this method is the outcomes will be compatible with existing design.
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Streich, Rita. "3D finite-difference frequency-domain modeling of controlled-source electromagnetic data: Direct solution and optimization for high accuracy." GEOPHYSICS 74, no. 5 (September 2009): F95—F105. http://dx.doi.org/10.1190/1.3196241.
Повний текст джерелаАнотація:
Three-dimensional modeling of marine controlled-source electromagnetic (CSEM) data is vital to improve the understanding of electromagnetic (EM) responses collected in increasingly complex geologic settings. A modeling tool for simulating 3D marine CSEM surveys, based on a finite-difference discretization of the Helmholtz equation for the electric fields, has been developed. Optimizations for CSEM simulations include the use of a frequency-domain technique, a staggering scheme that reduces inaccuracies especially for horizontal electric-dipole sources located near the seafloor, and a new interpolation technique that provides highly accurate EM field values for receivers located in the immediate vicinity of the seafloor. Source singularities are eliminated through a secondary-field approach, in which the primary fields are computed analytically for a homogeneous or a 1D layered background; the secondary fields are computed using the finite-difference technique. Exploiting recent advances in computer technology and algorithmic developments, the system of finite-difference equations is solved using the MUMPS direct-matrix solver. In combination with the other optimizations, this allows accurate EM field computations for moderately sized models on small computer clusters. The explicit availability of matrix factorizations is advantageous for multisource modeling and makes the algorithm well suited for future use within an inversion scheme. Comparisons of simulated data for (1) 1D models to data generated using a 1D reflectivity technique and (2) 3D models to published 3D data demonstrate the accuracy and benefits of the approach.
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Naumova, Olga V., and Elza G. Zaytseva. "Analysis of Electric Field Distribution for SOI-FET Sensors with Dielectrophoretic Control." Sensors 22, no. 7 (March 23, 2022): 2460. http://dx.doi.org/10.3390/s22072460.
Повний текст джерелаАнотація:
Silicon-on-insulator (SOI) nanowire or nanoribbon field-effect transistor (FET) biosensors are versatile platforms of electronic detectors for the real-time, label-free, and highly sensitive detection of a wide range of bioparticles. At a low analyte concentration in samples, the target particle diffusion transport to sensor elements is one of the main limitations in their detection. The dielectrophoretic (DEP) manipulation of bioparticles is one of the most successful techniques to overcome this limitation. In this study, TCAD modeling was used to analyze the distribution of the gradient of the electric fields E for the SOI-FET sensors with embedded DEP electrodes to optimize the conditions of the dielectrophoretic delivery of the analyte. Cases with asymmetrical and symmetrical rectangular electrodes with different heights, widths, and distances to the sensor, and with different sensor operation modes were considered. The results showed that the grad E2 factor, which determines the DEP force and affects the bioparticle movement, strongly depended on the position of the DEP electrodes and the sensor operation point. The sensor operation point allows one to change the bioparticle movement direction and, as a result, change the efficiency of the delivery of the target particles to the sensor.
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Kundu, T., D. Placko, E. K. Rahani, T. Yanagita, and Cac Minh Dao. "Ultrasonic field modeling: a comparison of analytical, semi-analytical, and numerical techniques." IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control 57, no. 12 (December 2010): 2795–807. http://dx.doi.org/10.1109/tuffc.2010.1753.
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Savic, Marija, and Marija Radmilovic-Radjenovic. "Gas discharges modeling by Monte Carlo technique." Chemical Industry 64, no. 3 (2010): 171–75. http://dx.doi.org/10.2298/hemind091221022s.
Повний текст джерелаАнотація:
The basic assumption of the Townsend theory - that ions produce secondary electrons - is valid only in a very narrow range of the reduced electric field E/N. In accordance with the revised Townsend theory that was suggested by Phelps and Petrovic, secondary electrons are produced in collisions of ions, fast neutrals, metastable atoms or photons with the cathode, or in gas phase ionizations by fast neutrals. In this paper we tried to build up a Monte Carlo code that can be used to calculate secondary electron yields for different types of particles. The obtained results are in good agreement with the analytical results of Phelps and. Petrovic [Plasma Sourc. Sci. Technol. 8 (1999) R1].
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Shahinpoor, Mohsen. "Ionic Polymeric Conductor Nano Composites (IPCNCs) as Distributed Nanosensors and Nanoactuators." Advances in Science and Technology 54 (September 2008): 70–81. http://dx.doi.org/10.4028/www.scientific.net/ast.54.70.
Повний текст джерелаАнотація:
This article covers advances made in connection with Ionic Polymeric-Conductor Nano Composites (IPCNCs) as distributed biomimetic nanosensors, nanoactuators, nanorobots and artificial muscles. A review of the fundamental properties and characteristics of IPCNCs will first be presented. This summary will include descriptions of the basic materials' molecular structure and subsequent procedure to manufacture the basic material for chemical plating and electroactivation. Further described are chemical molecular plating technologies to make IPCNCs, nanotechnologies of manufacturing and trapping of nanoparticles, SEM, TEM, SPM and AFM characterization of IPMNCs, biomimetic sensing and actuation characterization techniques, electrical characterization and equivalent circuit modeling of IPCNCs as electronic materials. A phenomenological model of the underlying sensing and actuation mechanisms is also presented based on linear irreversible thermodynamics with two driving forces, an electric field and a solvent pressure gradient and two fluxes, electric current density and the ionic+solvent flux. The presentation concludes with a number of videos and some live demos.
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Freno, Brian A., Neil R. Matula, Justin I. Owen, and William A. Johnson. "Code-verification techniques for the method-of-moments implementation of the electric-field integral equation." Journal of Computational Physics 451 (February 2022): 110891. http://dx.doi.org/10.1016/j.jcp.2021.110891.
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Mitsuhata, Yuji, та Toshihiro Uchida. "3D magnetotelluric modeling using the T‐Ω finite‐element method". GEOPHYSICS 69, № 1 (січень 2004): 108–19. http://dx.doi.org/10.1190/1.1649380.
Повний текст джерелаАнотація:
We present a finite‐element algorithm for computing MT responses for 3D conductivity structures. The governing differential equations in the finite‐element method are derived from the T–Ω Helmholtz decomposition of the magnetic field H in Maxwell's equations, in which T is the electric vector potential and Ω is the magnetic scalar potential. The Coulomb gauge condition on T necessary to obtain a unique solution for T is incorporated into the magnetic flux density conservation equation. This decomposition has two important benefits. First, the only unknown variable in the air is the scalar value of Ω. Second, the curl–curl equation describing T is only defined in the earth. By comparison, the system of curl–curl equations for H and the electric field E are singular in the air, where the conductivity σ is zero. Although the use of a small but nonzero value of σ in the air and application of a divergence correction are usually necessary in the E or H formulation, the T–Ω method avoids this necessity. In the finite‐element approximation, T and Ω are represented by the edge‐element and nodal‐element interpolation functions within each brick element, respectively. The validity of this modeling approach is investigated and confirmed by comparing modeling results with those of other numerical techniques for two 3D models.
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Ji, Haifeng, Qian Zhang, and Bin Zhang. "A Cartesian Grid Method for Modeling Charge Distribution on Interfaces via Augmented Technique." Mathematical Problems in Engineering 2018 (2018): 1–7. http://dx.doi.org/10.1155/2018/7521273.
Повний текст джерелаАнотація:
In the electrostatic field computations, second-order elliptic interface problems with nonhomogeneous interface jump conditions need to be solved. In realistic applications, often the total electric quantity on the interface is given. However, the charge distribution on the interface corresponding to the nonhomogeneous interface jump condition is unknown. This paper proposes a Cartesian grid method for solving the interface problem with the given total electric quantity on the interface. The proposed method employs both the immersed finite element with the nonhomogeneous interface jump condition and the augmented technique. Numerical experiments are presented to show the accuracy and efficiency of the proposed method.
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Nazir, Muhammad Tariq, Faizan Tahir Butt, Bao Toan Phung, Guan Heng Yeoh, Ghulam Yasin, Shakeel Akram, Muhammad Shoaib Bhutta, Shahid Hussain, and Tuan Anh Nguyen. "Simulation and Experimental Investigation on Carbonized Tracking Failure of EPDM/BN-Based Electrical Insulation." Polymers 12, no. 3 (March 5, 2020): 582. http://dx.doi.org/10.3390/polym12030582.
Повний текст джерелаАнотація:
Ethylene propylene diene monomer (EPDM) is broadly employed as an insulating material for high voltage applications. Surface discharge-induced thermal depolymerization and carbon tracking adversely affect its performance. This work reports the electrical field modeling, carbon tracking lifetime, infrared thermal distribution, and leakage current development on EPDM-based insulation with the addition of nano-BN (boron nitride) contents. Melt mixing and compression molding techniques were used for the fabrication of nanocomposites. An electrical tracking resistance test was carried out as per IEC-60587. Simulation results show that contamination significantly distorted the electrical field distribution and induced dry band arcing. Experimental results indicate that electric field stress was noticed significantly higher at the intersection of insulation and edges of the area of contamination. Moreover, the field substantially intensified with the increasing voltage levels. Experimental results show improved carbonized tracking lifetime with the addition of nano-BN contents. Furthermore, surface temperature was reduced in the critical contamination flow path. The third harmonic component in the leakage current declined with the increase of the nano-BN contents. It is concluded that addition of nano-BN imparts a better tracking failure time, and this is attributed to better thermal conductivity and thermal stability, as well as an improved shielding effect to electrical discharges on the surface of nanocomposite insulators.
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Buyakova, Natal'ya, Vasiliy Zakaryukin, Andrey Kryukov, and Van Le. "MODELLING OF THE ELECTROMAGNETIC FIELDS CREATED BY COMPACT MULTI SEGMENT POWER LINES." Scientific Papers Collection of the Angarsk State Technical University 2018, no. 1 (March 4, 2020): 152–61. http://dx.doi.org/10.36629/2686-7788-2020-152-161.
Повний текст джерелаАнотація:
In the article analysis technique of electromagnetic safety conditions on routes of
compact power lines (CPL) is offered. As the tool the program complex Fazonord was applied to modeling of CPL modes and electromagnetic fields.
Results of modeling show that the average levels of CPL electric field strengths exceed a similar indicator for the standard power line by 25…145 %, distinctions of maximums lie within 7… 150 %.
Especially considerable strength excesses take place at three-segment CPL. By criterion of magnetic
field strength the return picture is observed: levels of CPL magnetic field strength on 70 … 90 % below
than in traditional power line, and the best picture of electromagnetic safety possesses the foursegment power line.
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Meriouma, Takieddine, Sid Ahmed Bessedik, and Rabah Djekidel. "Modelling of Electric and Magnetic Field Induction under Overhead Power Line Using Improved Simulation Techniques." European Journal of Electrical Engineering 23, no. 4 (August 31, 2021): 289–300. http://dx.doi.org/10.18280/ejee.230402.
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Trichtchenko, L., and D. H. Boteler. "Modelling of geomagnetic induction in pipelines." Annales Geophysicae 20, no. 7 (July 31, 2002): 1063–72. http://dx.doi.org/10.5194/angeo-20-1063-2002.
Повний текст джерелаАнотація:
Abstract. Geomagnetic field variations induce telluric currents in pipelines, which modify the electrochemical conditions at the pipe/soil interface, possibly contributing to corrosion of the pipeline steel. Modelling of geomagnetic induction in pipelines can be accomplished by combining several techniques. Starting with geomagnetic field data, the geoelectric fields in the absence of the pipeline were calculated using the surface impedance derived from a layered-Earth conductivity model. The influence of the pipeline on the electric fields was then examined using an infinitely long cylinder (ILC) model. Pipe-to-soil potentials produced by the electric field induced in the pipeline were calculated using a distributed source transmission line (DSTL) model. The geomagnetic induction process is frequency dependent; therefore, the calculations are best performed in the frequency domain, using a Fourier transform to go from the original time domain magnetic data, and an inverse Fourier transform at the end of the process, to obtain the pipe-to-soil potential variation in the time domain. Examples of the model calculations are presented and compared to observations made on a long pipeline in the auroral zone.Key words. Geomagnetism and paleomagnetism (geo-magnetic induction)
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Boayue, Nya Mehnwolo, Gábor Csifcsák, Oula Puonti, Axel Thielscher, and Matthias Mittner. "Head models of healthy and depressed adults for simulating the electric fields of non-invasive electric brain stimulation." F1000Research 7 (November 15, 2018): 704. http://dx.doi.org/10.12688/f1000research.15125.2.
Повний текст джерелаАнотація:
During the past decade, it became clear that the electric field elicited by non-invasive brain stimulation (NIBS) techniques such as transcranial direct current stimulation (tDCS) and transcranial magnetic stimulation (TMS) are substantially influenced by variations in individual head and brain anatomy. In addition to structural variations in the healthy, several psychiatric disorders are characterized by anatomical alterations that are likely to further constrain the intracerebral effects of NIBS. Here, we present high-resolution realistic head models derived from structural magnetic resonance imaging data of 19 healthy adults and 19 patients diagnosed with major depressive disorder (MDD). By using a freely available software package for modelling the electric fields induced by different NIBS protocols, we show that our head models are well-suited for assessing inter-individual and between-group variability in the magnitude and focality of tDCS-induced electric fields for two protocols targeting the left dorsolateral prefrontal cortex.
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Nadimi, M., and A. Sadr. "Computer Modeling of MWIR Homojunction Photodetector Based on Indium Antimonide." Advanced Materials Research 383-390 (November 2011): 6806–10. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.6806.
Повний текст джерелаАнотація:
High operating temperatures infrared photodetectors are needed for improving the performance of existing military and civilian infrared systems. To obtain high device performance at higher temperatures, the thermally generated noise required to be reduced. Minority-carrier extraction and exclusion techniques are the approaches for decreasing the thermal noise of infrared systems. In the present work, an InSb extraction diode was studied and simulated for operation in the MWIR region. The simulation was performed using ATLAS device simulator from SILVACO®. The energy band diagram, doping profile, electric field profile, dark current and spectral response were calculated as a function of device thickness, applied reverse voltage and operating wavelength. The simulated photodetector exhibited a zero bias resistance-area product, R0A = 1.6×〖10〗^(-3) Ω〖.cm〗^2 at 240K.
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Yin, Changchun. "MMT forward modeling for a layered earth with arbitrary anisotropy." GEOPHYSICS 71, no. 3 (May 2006): G115—G128. http://dx.doi.org/10.1190/1.2197492.
Повний текст джерелаАнотація:
The standard model of a layered isotropic earth is a good approximation to geophysical reality in geoelectromagnetic mapping. In regions with distinct dipping stratification, however, it is difficult to model these fine structures because of large storage and time requirements. In this case, we may approximately replace the isotropic conductors with a preferential electrical direction by macro-scale anisotropy. The marine-magnetotelluric (MMT) forward problem is formulated for a layered earth with arbitrary anisotropy. For a given layer beneath the ocean, the two horizontal components of the electric field are projected onto the principal anisotropic directions and continued from layer to layer using continuity conditions. The formulation is used to derive the impedance tensor and apparent resistivities for a uniform anisotropic half-space, which clearly distinguish the effect of electrical anisotropy on MMT responses. The principal anisotropic orientations are clearly identified in the polar plots, which show the azimuthal variation of the apparent resistivity. The resolvability analysis of a resistive intermediate layer indicates that the depth of exploration for the MMT method depends strongly on the anomaly threshold associated with system sensitivity and environmental noise level but less on the resistivity contrast between the target and surrounding media. For an anisotropic target, to obtain a larger depth of exploration the electric field should be measured in the direction of higher target-host resistivity contrast. The simulation of reservoir characterization using marine MT shows that the current MMT technique cannot be an effective tool yet for direct offshore reservoir characterization, but it can be a good complementary tool for controlled-source electromagnetic (EM) technologies emerging for offshore hydrocarbon exploration.
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Et.al, R. Jeyarohini. "A performance Analysis of DM-DG and TM-DG TFETs Analytical Models for Low Power Applications." Turkish Journal of Computer and Mathematics Education (TURCOMAT) 12, no. 3 (April 10, 2021): 4642–51. http://dx.doi.org/10.17762/turcomat.v12i3.1874.
Повний текст джерелаАнотація:
Device Modeling is utilized to engendering incipient device models for the demeanor of the electrical devices predicated on fundamental physics. Modeling of the device may also include the creation of Compact models. An emerging device type of transistor is the Tunnel Field-Effect transistor that achieves compactness and speed during device modeling. This article presents an analytical comparative study of duel material DG TFETs and triple Material DG TFETs with gate oxide structure . Here the implementation of device modeling is done by solving Poisson’s equation with Parabolic Approximation Technique(PAT).The process of formulation of drain current(Id) model is based on integrating the BTBT generation. A Transconductance model of the device is additionally developed utilizing this drain current model of TFET. Surface potential is calculated by utilizing the channel potential model. The electrical properties like Surface potential〖(Ψ〗_(s,i)), Drain current (Id ), and Electric field(Ei) have been compared for both Duel material DG-TFET and Triple material DG-TFET. The comparison statement of DMDG-TFETs and TMDG-TFETs provide improved performance. The analytical model of the device results are compared with simulated results for DMDG TFET and TMDG TFET and good acquiescent is examined.
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Luo, Bing, Tingting Wang, Fuzeng Zhang, Yibin Lin, Chaozhi Zheng, and She Chen. "Interdigital Capacitive Sensor for Cable Insulation Defect Detection: Three-Dimensional Modeling, Design, and Experimental Test." Journal of Sensors 2021 (March 31, 2021): 1–10. http://dx.doi.org/10.1155/2021/8859742.
Повний текст джерелаАнотація:
Due to excellent electrical and mechanical properties, cross-linked polyethylene (XLPE) cables are widely used in power systems. Poor manufacturing techniques in the production and installation of cable joints will cause insulation defects. The interdigital capacitive (IDC) sensor has advantages of simple structure and non-contact with the center conductor and shows great potential for online monitoring on XLPE cables. This paper focuses on the 3D modeling of a fully covered IDC sensor for cable insulation detection. Firstly, a 3D finite element model of the sensor is built, and the electric field distributions are compared with those of the partially covered sensor. For the sensor with more electrode pairs, the sensitivity increases with the sensor length and tends to saturate at the length of 5 cm, while the sensitivity remains constant for the sensor with fewer electrode pairs. Then, the differences between 3D and 2D results are discussed and the sensor parameters are optimized to reduce the influence of the fringe capacitance. The simulation results indicate that air gaps between the sensor and XLPE cable are the main reason of the difference between simulation and experiment. When the electrode width is equal to the gap width, the effects of both the fringing electric field and air gaps are relatively small. Finally, several types of sensors are made and used to detect the cable joint with and without the stress cone dislocation under different excitation voltage frequency. The results show that the measured capacitance decreases with frequency and the capacitance of the cable joint with the defects is smaller than that of the normal cable joint.
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FJELDLY, TOR A., and MICHAEL S. SHUR. "SIMULATION AND MODELING OF COMPOUND SEMICONDUCTOR DEVICES." International Journal of High Speed Electronics and Systems 06, no. 01 (March 1995): 237–84. http://dx.doi.org/10.1142/s0129156495000079.
Повний текст джерелаАнотація:
We review the simulation and modeling techniques used for popular compound semiconductor devices such as the Heterostructure Field Effect Transistor (HFET), the Metal Semiconductor Field Effect Transistor (MESFET), and the Heterostructure Bipolar Transistor (HBT). Starting with the basic transport theory and the numerical simulation techniques based on this theory, we proceed to give examples of Monte Carlo simulations and of 2D balance equation simulations for investigating fundamental device properties and for exploring new design concepts. Next, we present analytical HFET and MESFET models suitable for circuit simulations. These models are based on the so-called universal FET modeling concept, and accurately reproduce FET I-V and C-V characteristics. Finally, we review basic simulation and modeling issues for HBTs.
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Aris, Muhammad Naeim Mohd, Hanita Daud, Sarat Chandra Dass, and Khairul Arifin Mohd Noh. "Gaussian Processes for Hydrocarbon Depth Estimation in Forward Modeling of Seabed Logging." Journal of Environmental and Engineering Geophysics 24, no. 3 (September 2019): 399–408. http://dx.doi.org/10.2113/jeeg24.3.399.
Повний текст джерелаАнотація:
Seabed logging (SBL) is an application of the marine controlled-source electromagnetic (CSEM) technique to discover offshore hydrocarbon reservoirs underneath the seabed. This application is based on electrical resistivity contrast between hydrocarbon and its surroundings. In this paper, simulation and forward modeling were performed to estimate the hydrocarbon depths in one-dimensional (1-D) SBL data. 1-D data, consisted offset distance (input) and magnitude of electric field (output), were acquired from SBL models developed using computer simulation technology (CST) software. The computer simulated outputs were observed at various depths of hydrocarbon reservoir (250 m–2,750 m with an increment of 250 m) with frequency of 0.125 Hz. Gaussian processes (GP) was employed in the forward modeling by utilizing prior information which is electric field (E-field) at all observed inputs to provide E-field profile at unobserved/untried inputs with uncertainty quantification in terms of variance. The concept was extended for two-dimensional (2-D) model. All observations of E-field were then investigated with the 2-D forward GP model. Root mean square error (RMSE) and coefficient of variation (CV) were utilized to compare the acquired and modeled data at random untried hydrocarbon depths at 400 m, 950 m, 1,450 m, 2,100 m and 2,600 m. Small RMSE and CV values have indicated that developed model can fit well the SBL data at untried hydrocarbon depths. The measured variances of the untried inputs revealed that the data points (true values) were very close to the estimated values, which was 0.003 (in average). RMSEs obtained were very small as an average of 0.049, and CVs found as very reliable percentages, an average of 0.914%, which implied well fitting of the GP model. Hence, the 2-D forward GP model is believed to be capable of predicting unobserved hydrocarbon depths.
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Chatterjee, Aveek, and Kevin Matocha. "Atomistic Scale Modeling and Analysis of Sodium Enhanced Oxidation of Silicon Carbide." Materials Science Forum 615-617 (March 2009): 493–96. http://dx.doi.org/10.4028/www.scientific.net/msf.615-617.493.
Повний текст джерелаАнотація:
We explain the phenomenon of sodium enhanced oxidation (SEO) using computational techniques, and analyze a set of probable hypotheses, which can elucidate the observation of high inversion channel mobility achieved with SEO. The ability of the Na to screen the interface traps, reduce carbon cluster type of defect formation, and enhance the oxidation rate can be explained using these calculations. We observe an increased availability of electrons near the interface in the presence of Na. The sodium atom also helps in breaking the intramolecular oxygen bond. The electronic and atomic structure of the interface cluster, and electric field computations showed that the carbon cluster formed at the oxide side of the interface could be screened by the Na ion.
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Bessette, D. "Modeling Techniques for Correcting Measured Data on the ITER Toroidal Field Insert Coil." IEEE Transactions on Appiled Superconductivity 14, no. 2 (June 2004): 1418–22. http://dx.doi.org/10.1109/tasc.2004.830631.
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Vilchevskaya, Elena N., and Wolfgang H. Müller. "Modeling of orientational polarization within the framework of extended micropolar theory." Continuum Mechanics and Thermodynamics 33, no. 4 (January 28, 2021): 1263–79. http://dx.doi.org/10.1007/s00161-021-00972-x.
Повний текст джерелаАнотація:
AbstractIn this paper the process of polarization of transversally polarizable matter is investigated based on concepts from micropolar theory. The process is modeled as a structural change of a dielectric material. On the microscale it is assumed that it consists of rigid dipoles subjected to an external electric field, which leads to a certain degree of ordering. The ordering is limited, because it is counteracted by thermal motion, which favors stochastic orientation of the dipoles. An extended balance equation for the microinertia tensor is used to model these effects. This balance contains a production term. The constitutive equations for this term are split into two parts, one , which accounts for the orienting effect of the applied external electric field, and another one, which is used to represent chaotic thermal motion. Two relaxation times are used to characterize the impact of each term on the temporal development. In addition homogenization techniques are applied in order to determine the final state of polarization. The traditional homogenization is based on calculating the average effective length of polarized dipoles. In a non-traditional approach the inertia tensor of the rigid rods is homogenized. Both methods lead to similar results. The final states of polarization are then compared with the transient simulation. By doing so it becomes possible to link the relaxation times to the finally observed state of order, which in terms of the finally obtained polarization is a measurable quantity.
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Liu, Hai-Tao, Wen-Juan Wu, and Jian-Guo Wu. "Dynamic non-local stress analysis of two collinear semi-permeable mode-I cracks in a piezoelectric medium." Journal of Intelligent Material Systems and Structures 30, no. 20 (September 20, 2019): 3100–3112. http://dx.doi.org/10.1177/1045389x19873425.
Повний текст джерелаАнотація:
This article investigates the dynamic non-local stress analysis of two collinear semi-permeable mode-I cracks in a piezoelectric medium under the harmonic waves by using the generalized Almansi theorem and the Schmidt method. Based on the Fourier transform technique, this problem is formulated into coupled dual integral equations. The dynamic stress and the dynamic electric displacement fields at the crack tips are obtained by solving the derived dual integral equations. Numerical examples are provided to show the effects of the crack length, the distance between the two collinear cracks, the lattice parameter, the electric permittivity of the air inside the crack, and the characteristics of the harmonic wave on the dynamic stress field and the dynamic electric displacement field near the crack tips. The dynamic stress and electric displacement decrease with increasing the distance between two collinear cracks and lattice parameter in a piezoelectric medium. Meanwhile, the dynamic field will impede or enhance crack propagation in piezoelectric medium depending on the circular frequency of the incident wave. Different from the classical solutions, the present solutions exhibit no stress and electric displacement singularities at the crack tips. This work is expected to be helpful for theoretical modeling of piezoelectric medium at nanoscale.
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Li, Jintai, Jianxin Liu, Jianqiang Xue, Rongwen Guo, Hang Chen, and Rong Liu. "A Feasibility Study of CSEM in Geological Advance Forecast with Horizontal Casing Well." Minerals 12, no. 5 (May 18, 2022): 638. http://dx.doi.org/10.3390/min12050638.
Повний текст джерелаАнотація:
With the rapid exploitation of deep mines by digging new tunnels, the advance forecast of water inrush has become increasingly important. The land-based controlled source electromagnetic method (CSEM) is commonly used to detect water-bearing structures. To increase its sensitivity, we propose a new measuring configuration for CSEM by placing EM sensors in an underground steel-cased well. The numerical modeling is conducted by COMSOL to overcome the difficulties of investigating the feasibility of the measuring configuration. The current distribution and electromagnetic field along an in-seam horizontal casing are investigated based on a synthesis three-layered model. The results illustrate that the casing can be treated as antennas that enhance the electric fields at large depths. The water-bearing structures can be observed by a magnetic field (with a perpendicularly horizontal electric dipole (HED) source) rather than an electric field (with a parallelly HED source). Numerical simulations demonstrate that the proposed method is a feasible and effective technique for the detection of water-bearing structures during deep mineral exploration.
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Kanyou Nana, R., S. Korte, S. Dickmann, H. Garbe, and F. Sabath. "Estimation of the threat of IEMI to complex electronic systems." Advances in Radio Science 7 (May 19, 2009): 249–53. http://dx.doi.org/10.5194/ars-7-249-2009.
Повний текст джерелаАнотація:
Abstract. The threat of ultra wideband (UWB) sources is interesting for military issues. This paper summarizes information concerning the voltages generated from some commercially available UWB generator systems and their produced electromagnetic fields. The paper focuses on the coupling of UWB fields into electronic equipment and discusses possible modeling and measurement techniques to estimate such a threat for modern ships. An evaluation procedure for the determination of the induced voltage at the input of an electronic component is presented. This method is based on the computation of the internal electric field and the measurements on a test network, which is similar to the structure of the steering control cabling. It allows the estimation of the potential threat for the ship's electronic equipment due to the exposal to UWB emitting sources.
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Fiocchi, Serena, Michela Longhi, Paolo Ravazzani, Yiftach Roth, Abraham Zangen, and Marta Parazzini. "Modelling of the Electric Field Distribution in Deep Transcranial Magnetic Stimulation in the Adolescence, in the Adulthood, and in the Old Age." Computational and Mathematical Methods in Medicine 2016 (2016): 1–9. http://dx.doi.org/10.1155/2016/9039613.
Повний текст джерелаАнотація:
In the last few years, deep transcranial magnetic stimulation (dTMS) has been used for the treatment of depressive disorders, which affect a broad category of people, from adolescents to aging people. To facilitate its clinical application, particular shapes of coils, including the so-called Hesed coils, were designed. Given their increasing demand and the lack of studies which accurately characterize their use, this paper aims to provide a picture of the distribution of the induced electric field in four realistic human models of different ages and gender. In detail, the electric field distributions were calculated by using numerical techniques in the brain structures potentially involved in the progression of the disease and were quantified in terms of both amplitude levels and focusing power of the distribution. The results highlight how the chosen Hesed coil (H7 coil) is able to induce the maxima levels ofEmainly in the prefrontal cortex, particularly for the younger model. Moreover, growing levels of induced electric fields with age were found by going in deep in the brain, as well as a major capability to penetrate in the deepest brain structures with an electric field higher than 50%, 70%, and 90% of the peak found in the cortex.
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BLINOV, L. M., V. V. LAZAREV, S. P. PALTO, G. CIPPARRONE, A. MAZZULLA, and P. PAGLIUSI. "ELECTRIC FIELD TUNING A SPECTRUM OF NEMATIC LIQUID CRYSTAL LASING WITH THE USE OF A PERIODIC SHADOW MASK." Journal of Nonlinear Optical Physics & Materials 16, no. 01 (March 2007): 75–90. http://dx.doi.org/10.1142/s0218863507003561.
Повний текст джерелаАнотація:
Lasing has been observed in the dye-doped isotropic and nematic phases of liquid crystals in a plane layer placed between one substrate with a uniform transparent electrode and another substrate with a system of parallel chromium (nontransparent) electrodes. The latter has a periodicity of 15 μm and plays a double role: (i) in both the phases it operates as a shadow mask providing a spatial modulation of the pump beam and consequently, a gain of the material and (ii) in the nematic phase it additionally creates a Bragg resonator structure with spatial modulation of the refraction index when an electric voltage is applied across the transparent and non-transparent electrodes. The resonator operates at high order Bragg resonance modes of numbers m = 71–79 for three lasing dyes studied. With that simple cell, a voltage induced tuning of the spectral positions of lasing lines over 25 nm has been demonstrated without using holographic or other complicated techniques. The mechanism of the observed phenomenon is discussed using modeling of the liquid crystal reorientation and optical properties in the spatially periodic electric field.
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Amara-Ouali, Yvenn, Yannig Goude, Pascal Massart, Jean-Michel Poggi, and Hui Yan. "A Review of Electric Vehicle Load Open Data and Models." Energies 14, no. 8 (April 16, 2021): 2233. http://dx.doi.org/10.3390/en14082233.
Повний текст джерелаАнотація:
The field of electric vehicle charging load modelling has been growing rapidly in the last decade. In light of the Paris Agreement, it is crucial to keep encouraging better modelling techniques for successful electric vehicle adoption. Additionally, numerous papers highlight the lack of charging station data available in order to build models that are consistent with reality. In this context, the purpose of this article is threefold. First, to provide the reader with an overview of the open datasets available and ready to be used in order to foster reproducible research in the field. Second, to review electric vehicle charging load models with their strengths and weaknesses. Third, to provide suggestions on matching the models reviewed to six datasets found in this research that have not previously been explored in the literature. The open data search covered more than 860 repositories and yielded around 60 datasets that are relevant for modelling electric vehicle charging load. These datasets include information on charging point locations, historical and real-time charging sessions, traffic counts, travel surveys and registered vehicles. The models reviewed range from statistical characterization to stochastic processes and machine learning and the context of their application is assessed.