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Journal articles on the topic 'Heterogeneous electromagnetic field'
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Zhukovskiy, Mikhail Evgenievich, and Varvara Alekseevna Egorova. "Modeling of the radiation induced electromagnetic field in finely-disperse media." Mathematica Montisnigri 52 (2021): 52–65. http://dx.doi.org/10.20948/mathmontis-2021-52-6.
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Algorithms for supercomputer modeling of the radiation electromagnetic field in heterogeneous materials of a complex finely-dispersed structure are constructed. A geometric model of a heterogeneous medium is created using Stilinger-Lubachevsky algorithms for multimodal structures. The model includes a system of detectors for statistical evaluation of functionals on the space of solutions of the photon-electron cascade transport equations. Algorithms for the three-dimensional approximation of the results of modeling the radiation transport in a fine-dispersed medium to an electrodynamic difference grid are developed. The approximation methods based on the technology of neural networks. The method of numerical solution of the complete system of Maxwell's equations for calculating the electromagnetic field in a fine-dispersed medium is worked out. The results of demonstration calculations of the electromagnetic field are presented. The results of the calculations show that the spatial distribution of the radiation electromagnetic field has a sharply inhomogeneous structure caused by the presence of boundaries of materials with different radiation properties.
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Grinchik, N. N., and Yu N. Grinchik. "Fundamental Problems of the Electrodynamics of Heterogeneous Media." Physics Research International 2012 (April 8, 2012): 1–28. http://dx.doi.org/10.1155/2012/185647.
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The consistent physic-mathematical model of propagation of an electromagnetic wave in a heterogeneous medium is constructed using the generalized wave equation and the Dirichlet theorem. Twelve conditions at the interfaces of adjacent media are obtained and justified without using a surface charge and surface current in explicit form. The conditions are fulfilled automatically in each section of counting schemes for calculations. A consistent physicomathematical model of interaction of nonstationaly electric and thermal fields in a layered medium with allowance or mass transfer is constructed. The model is based on the methods of thermodynamics and on the equations of an electromagnetic field and is formulated without explicit separation of the charge carriers and the charge of an electric double layer.
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Choroszucho, Agnieszka, Boguslaw Butrylo, Adam Steckiewicz, and Jacek Maciej Stankiewicz. "Determination of the Effective Electromagnetic Parameters of Complex Building Materials for Numerical Analysis of Wireless Transmission Networks." Electronics 9, no. 10 (September 25, 2020): 1569. http://dx.doi.org/10.3390/electronics9101569.
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In this paper, we present the method for determination of effective electromagnetic parameters of complex building materials. By application of the proposed algorithm, it is possible to analyze electromagnetic field distribution for large-scale problems with heterogeneous materials. The two-dimensional numerical model of building components (hollow brick) with periodic boundary conditions was solved using the finite-difference time-domain method (FDTD) and discussed. On this basis, the resultant transmission coefficient was found and then the equivalent relative permeability and electric conductivity of heterogeneous dielectric structures, in the developed homogenization algorithm, were identified. The homogenization of material properties was achieved by performing a multi-variant optimization scheme and finally, selecting optimal electric parameters. Despite the analysis of heterogeneous building materials, the presented algorithm is shown as a tool for the homogenization of complex structures when scattering of a high-frequency electromagnetic field is considered.
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List, Nanna Holmgaard, Hans Jørgen Aagaard Jensen, and Jacob Kongsted. "Local electric fields and molecular properties in heterogeneous environments through polarizable embedding." Physical Chemistry Chemical Physics 18, no. 15 (2016): 10070–80. http://dx.doi.org/10.1039/c6cp00669h.
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Effective external field effects in spectroscopies of molecules in heterogeneous environments, i.e., the implications of the additional environment polarization induced by the probing electromagnetic field, can be significant and depart remarkably from the simple Onsager picture.
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Bruzzone, S., M. Malvaldi, G. P. Arrighini, and C. Guidotti. "Electromagnetic Coupling in Near-Field Scattering by Small Homogeneous and Heterogeneous Nanoaggregates." Journal of Physical Chemistry B 109, no. 50 (December 2005): 23808–15. http://dx.doi.org/10.1021/jp0538518.
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Katyal, Jyoti. "Al-Au Heterogeneous Dimer-trimer Nanostructure for SERS." Nanoscience & Nanotechnology-Asia 10, no. 1 (January 23, 2020): 21–28. http://dx.doi.org/10.2174/2210681208666180821141727.
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: Tunability in resonance wavelength and the enhancement of the electromagnetic field intensities around the surface are two unique properties which make metal as a plasmonic material. A theoretical investigation on the LSPR and field enhancement for heterogeneous dimer–trimer metallic nanostructure by constituting Al and Au as two different plamsonic materials has been studied. Since electrons in Al exhibit free behavior for LSPR of Au, therefore, they influence the electric field magnitude generated by Au LSPR. Methods: The electromagnetic simulations reported in this paper were performed using the FDTD Solutions (version 7.5.1), a product of Lumerical Solutions Inc., Vancouver, Canada. We adopted a cubic Yee cell of 1 nm side and a time step Δt= 1.31•10-18 s, bounded by Courant condition. Results: The extinction spectrum shows LSPR peak over UV-visible region for isotropic nanostructure which shifts to NIR region for anisotropic shape nanostructure. The spherical shape hetero dimer nanostructure shows enhancement factor ~ 3.9 X 105 whereas it increases to ~ 6.2 X 106 for anisotropic shape at 610 nm. The field distribution corresponding to the trimer nanostructure reveals a large dipolar field distribution on each of the three nanoparticles, oscillating approximately in-phase. The spherical shape Al-Au-Al shows enhancement factor ~ 8.5 X 106 at 571 nm. The anisotropic shape increase the enhancement factor to ~ 2.4 X 107 at peak wavelength 700 nm i.e. tuning the plasmon wavelength towards NIR region. Conclusion: The tunability in plasmon wavelength and field enhancement factor has been evaluated for heterogeneous nanostructure over wider spectrum range i.e. DUV-Visible-NIR using Au-Al dimer and trimer nanostructure. The isotropic shape Au-Al hetero nanostructure shows larger enhancement in the UV-visible region, whereas the anisotropic shape nanostructure contributes towards the NIR region.
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Samluk, Jesse P., Cathleen A. Geiger, and Chester J. Weiss. "Full-physics 3-D heterogeneous simulations of electromagnetic induction fields on level and deformed sea ice." Annals of Glaciology 56, no. 69 (2015): 405–14. http://dx.doi.org/10.3189/2015aog69a737.
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AbstractIn this paper we explore simulated responses of electromagnetic (EM) signals relative to in situ field surveys and quantify the effects that different values of conductivity in sea ice have on the EM fields. We compute EM responses of ice types with a three-dimensional (3-D) finite-volume discretization of Maxwell’s equations and present 2-D sliced visualizations of their associated EM fields at discrete frequencies. Several interesting observations result: First, since the simulator computes the fields everywhere, each gridcell acts as a receiver within the model volume, and captures the complete, coupled interactions between air, snow, sea ice and sea water as a function of their conductivity; second, visualizations demonstrate how 1-D approximations near deformed ice features are violated. But the most important new finding is that changes in conductivity affect EM field response by modifying the magnitude and spatial patterns (i.e. footprint size and shape) of current density and magnetic fields. These effects are demonstrated through a visual feature we define as ‘null lines’. Null line shape is affected by changes in conductivity near material boundaries as well as transmitter location. Our results encourage the use of null lines as a planning tool for better ground-truth field measurements near deformed ice types.
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Carcione, José M. "A spectral numerical method for electromagnetic diffusion." GEOPHYSICS 71, no. 1 (January 2006): I1—I9. http://dx.doi.org/10.1190/1.2159050.
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I present a pseudospectral explicit scheme that can simulate low-frequency electromagnetic (EM) propagation in the earth. This scheme solves linear periodic parabolic equations, having accuracy within machine precision, both temporally and spatially. The method is based on a Chebyshev expansion of the evolution operator, with the spatial derivatives computed via a staggered Fourier pseudospectral technique. The results match analytical solutions of the initial-value problem and the Green's function. An example of the EM field produced by a set of magnetic sources in a heterogeneous model illustrates the algorithm's performance.
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Singer, B. Sh, and E. B. Fainberg. "Modelling of electromagnetic fields in thin heterogeneous layers with application to field generation by volcanoes-theory and example." Geophysical Journal International 138, no. 1 (July 1999): 125–45. http://dx.doi.org/10.1046/j.1365-246x.1999.00844.x.
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Han, Qiyu, and Zhijing (Zee) Wang. "Time‐domain simulation of SH-wave‐induced electromagnetic field in heterogeneous porous media: A fast finite‐element algorithm." GEOPHYSICS 66, no. 2 (March 2001): 448–61. http://dx.doi.org/10.1190/1.1444936.
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When a horizontally polarized rotational mechanical wave (SH-wave) travels through a porous rock, acceleration of the rock frame induces a streaming current in the SH particle motion plane. This streaming current is parallel to the particle displacement and has an associated electromagnetic (EM) field. This phenomenon is often described as the electroseismic (EOS) conversion. Numerically, the EOS phenomenon can be simulated in either the frequency or the time domain. Frequency‐domain numerical simulation has huge memory and computational requirements. Traditional time‐domain simulation, on the other hand, must restrict the time steps to be very small to satisfy stability conditions, resulting in large workload. In this paper, we present a fast finite‐element (FE) method simulating the EOS conversion in the time domain. In our method, we decompose the large 2-D FE matrix equations into a set of 1-D matrix equations and solve the problem using the approximate 1-D multistep process. We present numerical examples of 1-D and 2-D models to illustrate the coevolution of the seismic and electromagnetic fields. Our simulation results show that the diffusive electrical field is induced from the spatial variations of mechanical and electrical properties of the porous media due to the imbalance of the induced electric current. Besides the direct SH-wave itself, the transmitted waves, multiple waves, reflected waves, and diffracted waves also induce diffusive electrical fields. The EOS conversion is potentially useful for reservoir characterization, but the EOS data may be difficult to interpret due to the complexity of the superposed wave fields. The diffusive nature of the induced EM fields suggests that antennas should be positioned close to the target of interest in in‐situ measurements. As a result, borehole EOS surveys are likely to be more practical than surface surveys.
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Aksenchyk, A. V., and I. F. Kirynovich. "Simulation of High-Power Klystrons with Heterogeneous Focusing Magnetic Field." Doklady BGUIR 20, no. 2 (April 6, 2022): 94–98. http://dx.doi.org/10.35596/1729-7648-2022-20-2-94-98.
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The work shows a significant effect of the focusing magnetic field on the output characteristics of the klystron. When the calculations are done using nonlinear one-dimensional models, optimization of the parameters makes it possible to obtain versions of devices with the efficiency of 0.8 – 0.9 and higher. However, when testing these options using nonlinear two-dimensional models that take into account the radial motion of electrons, there is a significant discrepancy in the output characteristics obtained from the one-dimensional and two-dimensional models. This is due to the fact that during the motion of the electron beam, the radii of the leading centers of the large particles change the coefficients of interaction of the particle fields with the electromagnetic fields of the resonators change, which leads to a change in the output characteristics of the klystrons: efficiency, output power, and gain. On the other hand, it seemed that setting a large focusing magnetic field to exclude the radial motion of particles could eliminate this drawback, however, another problem arises here - the magnetic system for focusing becomes unacceptably large and it is technically difficult to obtain magnetic induction values of more than 2 T (the weight of the magnetic system can be several hundred kilograms). Therefore, one should choose the magnetic field induction for focusing the electron beam no more than 1T. In this paper, a twodimensional nonlinear mathematical model (2.5D) is proposed that takes into account the azimuthal component in the equations of motion. In the model, the induction of the focusing magnetic field is set in the form of tables. This makes it possible to set the inhomogeneity of the magnetic field at any place in the interaction space of the klystron. The calculation of a powerful relativistic klystron with an accelerating voltage of 1000 kV and the beam current of 250 A was carried out. The use of an inhomogeneous magnetic field makes it possible to reduce the deposition of electrons in the region of the gaps. Therefore, a decrease in the electron deposition leads to an increase in the durability of klystrons.
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Karpowicz, Jolanta, Patryk Zradziński, Jarosław Kieliszek, Krzysztof Gryz, Jaromir Sobiech, and Wiesław Leszko. "An In Situ and In Silico Evaluation of Biophysical Effects of 27 MHz Electromagnetic Whole Body Humans Exposure Expressed by the Limb Current." BioMed Research International 2017 (2017): 1–9. http://dx.doi.org/10.1155/2017/5785482.
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Objectives. The aim was to evaluate correlations between biophysical effects of 27 MHz electromagnetic field exposure in humans (limb induced current (LIC)) and (1) parameters of affecting heterogeneous electric field and (2) body anthropometric properties, in order to improve the evaluation of electromagnetic environmental hazards. Methods. Biophysical effects of exposure were studied in situ by measurements of LIC in 24 volunteers (at the ankle) standing near radio communication rod antenna and in silico in 4 numerical body phantoms exposed near a model of antenna. Results. Strong, positive, statistically significant correlations were found in all exposure scenarios between LIC and body volume index (body height multiplied by mass) (r>0.7; p<0.001). The most informative exposure parameters, with respect to the evaluation of electromagnetic hazards by measurements (i.e., the ones strongest correlated with LIC), were found to be the value of electric field (unperturbed field, in the absence of body) in front of the chest (50 cm from body axis) or the maximum value in space occupied by human. Such parameters were not analysed in previous studies. Conclusions. Exposed person’s body volume and electric field strength in front of the chest determine LIC in studied exposure scenarios, but their wider applicability needs further studies.
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Yoon, Sangwoo, Kye Sang Yoo, and Joohan Kim. "Effect of Pd Ions on the Generation of Ag and Au Heterogeneous Nanoparticles Using Laser Ablation in Liquid." Applied Sciences 11, no. 4 (February 4, 2021): 1394. http://dx.doi.org/10.3390/app11041394.
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Heterogeneous Ag/Au nanoparticles combined with Pd ions were generated by irradiating Ag/Au metal targets in a Pd solution with nanosecond and femtosecond lasers. AgPd and AuPd nanoparticles were generated by laser fragmentation and bonded. We numerically analyzed the hot spots with electromagnetic field enhancement of nanoparticles of different sizes separated by various distances. AgPd and AuPd nanoparticles differing in diameter were generated and showed different characteristics compared to typical core-shell heterogeneous nanoparticles. Pd ions played an important role in the generation of nanoparticles in liquid via laser ablation. The femtosecond laser produced both pure and heterogeneous nanoparticles of uniform size. The nanosecond laser produced pure nanoparticles with a relatively non-uniform size, which developed into spherical heterogeneous nanoparticles with a uniform (small) size in the presence of Pd ions. These nanoparticles could optimize applications such as photothermal therapy and catalysis.
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NABUTOVSKII, V. M., and V. R. BELOSLUDOV. "VAN DER WAALS CONTRIBUTION TO THE THERMODYNAMICAL PROPERTIES OF THE CURVILINEAR SURFACES." International Journal of Modern Physics B 03, no. 02 (February 1989): 171–210. http://dx.doi.org/10.1142/s0217979289000154.
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This article is a review of our papers devoted to the application of the Lifshitz, Dzjaloshinskii, Pitaevskii theory for the theoretical investigation of the thermodynamical properties of the plane, spherical and cylindrical interfaces and layers. In accordance with this theory the thermodynamical properties of the surface are determined by the fluctuating electromagnetic field. This field may be characterized by the averaged quadratic combinations of the electric and magnetic strength which are thermodynamical Green functions of this field. We have obtained these Green functions for the spherical and cylindrical interfaces and applied them for the calculations of the different thermodynamical quantities such as electromagnetic stress tensor, chemical potential, and density variation. We have shown that, in general, it is not valid to obtain size and form dependence of the thermodynamical quantities by using two-particle Van der Waals potential. We discuss the surface tension dependence of the particle (or hole) and homogeneous and heterogeneous nucleation.
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Castrignanò, A., R. Quarto, A. Venezia, and G. Buttafuoco. "A geostatistical approach for modelling and combining spatial data with different support." Advances in Animal Biosciences 8, no. 2 (June 1, 2017): 594–99. http://dx.doi.org/10.1017/s2040470017000048.
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The paper proposes a geostatistical framework to solve the issues of heterogeneous support for spatial estimation. Apparent soil electrical conductivity (ECa) was measured in a field cropped with San Marzano tomato using a multiple frequency electromagnetic profiler with 6 operating frequencies. Mixed support kriging was used to estimate ECa taking into account the change of support. The method includes punctual kriging with the error being the dispersion variance associated with each frequency. The individual ECa maps were weighted by the dispersion variance to obtain a map which was used for field partition in management zones.
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Khan, Zehra, Tarun Sharma, Naiyara Khan, and Adil Ahmad Magray. "Soil exploration using ground penetrating radar." IOP Conference Series: Earth and Environmental Science 889, no. 1 (November 1, 2021): 012009. http://dx.doi.org/10.1088/1755-1315/889/1/012009.
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Abstract Geophysical methods are extensively utilized in the field of geology and in geotechnical engineering such as seismic, gravitational, magnetic and electromagnetic fields. These methods are used to locate or to understand conditions below the ground surface, and the physical properties of subsurface. GPR also known as Radio Detecting and Ranging is based on the electromagnetic waves. It is a specially designed radar unit for transmitting electromagnetic pulses below the ground instead of air. In GPR the medium is soil which is heterogeneous and has higher attenuation rate than air. This method is used to measure the length, depth or to locate the soil layers and its deposits. GPR is one of the most versatile sensors; it provides high resolution profiles for shallow depth. GPR has been used in diverse fields such as archaeology, non-destructive testing, probing underground caves, detecting landmines, mapping pipes and conduits, investigating the reinforcement and conditions of roads, bridges and airport runways, to name a few. Use of this technique/method is being extensively adopted from recent years because of its properties and vast applications. The main applications of GPR in subsurface mapping are: mapping of subsurface utility structures, detection and mapping of unexploded ordnance and mines, extraction of hazardous waste containers or unexploded ammunitions, maintenance or repair of subsurface structures. This paper presents an understanding of the concept or the need of GPR dedicated to civil engineering applications in general and in the field of geotechnical engineering in particular.
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Arutyunov, S. Yu, I. N. Dorokhov, V. V. Kafarov, V. G. Korniichuk, and V. P. Solov'ev. "Application of methods of the mechanics of heterogeneous media to describe dispersion processes in an electromagnetic field." Journal of Applied Mechanics and Technical Physics 29, no. 4 (1989): 583–87. http://dx.doi.org/10.1007/bf00852501.
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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.
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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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Krylov, V. P. "Modelling of electromagnetic properties of multicomponent material." Industrial laboratory. Diagnostics of materials 84, no. 7 (August 8, 2018): 38–41. http://dx.doi.org/10.26896/1028-6861-2018-84-7-38-41.
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Current theories of heterogeneous media consider non-uniform materials as natural and artificially synthesizable structures. Nowadays, synthesis of the non-uniform multicomponent materials with given electrodynamic properties and characterized by magnetic and dielectric permeability, is gaining increasing development. When modeling a multicomponent structure as a uniform material with effective dielectric permeability (ignoring the magnetic properties) using the developed models for the components with known dielectric permeability, the errors arise in calculation of the transmission coefficient of a plane wave through the antenna dome wall. We present a heuristic model based on the laws of optics which is intended for simultaneous determination of the effective magnetic and dielectric permeability of multicomponent material in contrast to known models describing statistically non-uniform media only for one electrodynamic parameter. The electrodynamic model developed for description of the effective magnetic and dielectric permeability of non-uniform material suggests a possibility of characterizing a polarized material with the total dipole moment arising in alternating field and expressing the Brewster angle as a the sum of the polarization angles proportional to volume content the mixture components.
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Celaya-Echarri, Mikel, Leyre Azpilicueta, Fidel Alejandro Rodríguez-Corbo, Peio Lopez-Iturri, Victoria Ramos, Mohammad Alibakhshikenari, Raed M. Shubair, and Francisco Falcone. "Towards Environmental RF-EMF Assessment of mmWave High-Node Density Complex Heterogeneous Environments." Sensors 21, no. 24 (December 16, 2021): 8419. http://dx.doi.org/10.3390/s21248419.
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The densification of multiple wireless communication systems that coexist nowadays, as well as the 5G new generation cellular systems advent towards the millimeter wave (mmWave) frequency range, give rise to complex context-aware scenarios with high-node density heterogeneous networks. In this work, a radiofrequency electromagnetic field (RF-EMF) exposure assessment from an empirical and modeling approach for a large, complex indoor setting with high node density and traffic is presented. For that purpose, an intensive and comprehensive in-depth RF-EMF E-field characterization study is provided in a public library study case, considering dense personal mobile communications (5G FR2 @28 GHz) and wireless 802.11ay (@60 GHz) data access services on the mmWave frequency range. By means of an enhanced in-house deterministic 3D ray launching (3D-RL) simulation tool for RF-EMF exposure assessment, different complex heterogenous scenarios of high complexity are assessed in realistic operation conditions, considering different user distributions and densities. The use of directive antennas and MIMO beamforming techniques, as well as all the corresponding features in terms of radio wave propagation, such as the body shielding effect, dispersive material properties of obstacles, the impact of the distribution of scatterers and the associated electromagnetic propagation phenomena, are considered for simulation. Discussion regarding the contribution and impact of the coexistence of multiple heterogeneous networks and services is presented, verifying compliance with the current established international regulation limits with exposure levels far below the aforementioned limits. Finally, the proposed simulation technique is validated with a complete empirical campaign of measurements, showing good agreement. In consequence, the obtained datasets and simulation estimations, along with the proposed RF-EMF simulation tool, could be a reference approach for the design, deployment and exposure assessment of the current and future wireless communication technologies on the mmWave spectrum, where massive high-node density heterogeneous networks are expected.
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Yoon, Eui Pak, Jung Pyung Choi, Yu Sik Seo, and Tae Woon Nam. "The Continuous Elimination of Inclusions in Molten Aluminum by Direct and Alternate Electromagnetic Force." Materials Science Forum 539-543 (March 2007): 499–502. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.499.
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In the casting Al alloys, Inclusions are formed by various melt treatment and the some alloying elements have a bad effect on quality of products. Generally, inclusions deteriorate mechanical properties of casting products as well as provide heterogeneous nucleation sites of hydrogen porosity. But the difficulty of removing it is the fact that the inclusions are measured generally small about 20㎛ in the melt. So, in this study, Experiments were carried out on commercial die casting aluminum alloy A383 (JIS: ADC 12). The separation system including a D.C. electric field with steady D.C. magnetic field was adopted for reduction of inclusion in molten Al alloy. Also the quantitative and qualitative analysis of inclusion in Al alloy was taken by using the PoDFA (Porous Disc Filtration Apparatus) and EPMA.
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Slavich, PG. "Determining ECa-depth profiles from electromagnetic induction measurements." Soil Research 28, no. 3 (1990): 443. http://dx.doi.org/10.1071/sr9900443.
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The response of the EM-38 instrument to a wide range of simulated apparent electrical conductivity (ECa) profiles of different shape and mean ECa was modelled using depth response functions derived for uniform ECa profiles. Relationships between the calculated EM-38 readings and average profile ECa for depths to 1 m were determined using linear regression. These relationships were used to predict ECa profiles measured in the field using a 4-electrode probe. The mean profile ECa of the simulated profiles was strongly correlated with simple linear combinations of the calculated vertical (EM,) and horizontal (EMh) dipole measurements. The model calculations indicated that the depth to which the EM-38 measures may vary from 1.65 to 5 m, depending on the ECa of these layers and the instrument range setting. Apparent electrical conductivity profiles measured with a 4-electrode probe were more closely predicted from EM-38 measurements using this approach than the established coefficient approach of D. L. Corwin and J. D. Rhoades. The results indicate that the depth response functions, derived for homogeneous profiles, also apply to heterogeneous profiles.
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Anzulevich, Anton P., Leonid N. Butko, Dmitry A. Pavlov, Dmitry A. Kalganov, Valentin A. Tolkachev, Svetlana N. Anzulevich, Vasiliy D. Buchelnikov, Sergey G. Moiseev, and Zhiwei Peng. "Effective electrodynamical parameters and microwave heating of radially heterogeneous pellets containing EAF dust and biochar." Journal of Physics: Conference Series 2015, no. 1 (November 1, 2021): 012007. http://dx.doi.org/10.1088/1742-6596/2015/1/012007.
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Abstract In this work, we investigated the effect of microwave radiation with radially heterogeneous pellets consisting of electric arc furnace (EAF) dust and biochar. We reviewed the possible content of EAF dust in terms of permittivity and permeability of its components and calculated effective permittivity and permeability of EAF dust by an effective medium approach. Using obtained values we calculated dependencies of effective permittivity and permeability of EAF dust - biochar composite mixture on the volume fraction of EAF dust and conductivity of biochar. Taking into account these dependencies we simulated electromagnetic field and temperature distribution within pellet with a radial dependency of volume fraction of EAF dust and effective permittivity correspondingly.
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Xu, Min, Robert Geer, Pavel Kabos, and Thomas Wallis. "High Speed Signal Transmission using Through-Si Vias and Coplanar Waveguides in a 3D IC Test Structure." International Symposium on Microelectronics 2013, no. 1 (January 1, 2013): 000228–32. http://dx.doi.org/10.4071/isom-2013-tp13.
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High frequency signal transmission through silicon substrates is critical for 3D heterogeneous integration. This paper presented fabrication, testing, and simulation of high-frequency interconnects based on through-silicon vias (TSVs) and coplanar waveguides (CPWs) for stacked 3D integrated circuits (3D ICs). Our simulation results showed that adding ground TSVs can improve signal transmission by 6× at 50GHz. We further investigated signal/ground TSV (1SXG) configurations for high-bandwidth signal transmission links. Scattering parameter measurements of fabricated 1SXG TSV structures for frequencies from 100MHz to 50GHz show low insertion loss (S21 less than −1dB up to 50GHz) and return loss (S11 lower than −15dB). These results indicate that these vertical interconnects exhibit good performance for high speed signal transmission. To understand the RF signal transmission in 3D interconnects, we used full wave electromagnetic simulation to investigate the electromagnetic field distribution associated with the ground TSV placement. We observed that the ground TSVs induced substantial overall field confinement, consistent with the experimental observation of improved signal transmission. Simulations also provided design guidance with respect to the substrate conductivity's impact on EM confinement and signal transmission.
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Gómez‐Treviño, Enrique, Francisco J. Esparza, and Sóstenes Méndez‐Delgado. "New theoretical and practical aspects of electromagnetic soundings at low induction numbers." GEOPHYSICS 67, no. 5 (September 2002): 1441–51. http://dx.doi.org/10.1190/1.1512744.
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This paper presents a theoretical yet practical study of electromagnetic (EM) soundings at low induction numbers for vertical and horizontal magnetic dipoles. The physical model is a heterogeneous half‐space with arbitrary vertical conductivity variations. The study comprises a novel approach for solving forward problems, analytical formulas for inversion, and a practical algorithm for recovering conductivity variations from field measurements. The basis of the theoretical approach is a series representation of the EM field in terms of ascending powers of frequency. At low induction numbers only two terms are required. When substituted into Maxwell's equations, one term in the series can be obtained in terms of the other. Furthermore, if the electrical conductivity varies only with depth, the imaginary part of the field can be obtained from its real part through a differential equation. The real part, which corresponds to zero frequency, plays the role of a distributed source for the frequency‐dependent imaginary part. In the case of vertical magnetic dipoles, the approach applies directly to the real and imaginary components of the magnetic field, while for horizontal dipoles one must use the Hertz potential, but the procedure is exactly the same. In each case this leads to a statement of the forward problem as the solution of a real differential equation. The solutions are integral expressions valid for arbitrary conductivity profiles. Assuming that these expressions represent integral equations for conductivity, analytical inverse formulas are derived for both vertical and horizontal dipoles. These formulas ensure a unique recovery of the conductivity profile under ideal conditions. An algorithm based on linear programming offers a variety of practical advantages for the inversion of field data. Numerical experiments and applications to field data illustrate the performance of the algorithm.
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Neubauer, Georg, Patrick Preiner, Stefan Cecil, Niki Mitrevski, Johannes Gonter, and Heinrich Garn. "The relation between the specific absorption rate and electromagnetic field intensity for heterogeneous exposure conditions at mobile communications frequencies." Bioelectromagnetics 30, no. 8 (December 2009): 651–62. http://dx.doi.org/10.1002/bem.20519.
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Zlobina, I. V., and N. V. Bekrenev. "The Influence of Electromagnatic Field Microwave on Physical and Mechanical Characteristics of CFRP (Carbon Fiber Reinforced Polymer) Structural." Materials Science Forum 870 (September 2016): 101–6. http://dx.doi.org/10.4028/www.scientific.net/msf.870.101.
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Based on the analysis of the development trends of modern transport equipment the prospect of structural composite materials usage, for example CFRP structural, is shown. In this regard, the expediency of conducting research to improve the strength characteristics of these materials is established. It is shown that, despite the large amount of scientific publications on the application of electro-technological methods and microwave technologies for modification of composite materials, applied to heterogeneous materials, such as carbon fiber, in Russia and abroad there are still some unsolved theoretical and practical questions. The studies of the effect of microwave electromagnetic field power density on different physical and mechanical characteristics of laminated composite materials in order to establish the opportunities to improve their performance, in particular their strength, were made. The example of carbon is used to show that the microwave electromagnetic field power density of 17.5 W/cm3 at a frequency of 2450 MHz exposure time of 2 minutes causes an increase in the shear strength of 38 – 40 % and an increase in the duration of the construction operation of carbon under the action of the peak load of 1.5 up to 4.5 times, wherein the change in flexural strength and modulus of elasticity was 2.6 %.
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Kudryashova’, Tatiana, Sergey Polyakov, and Nikita Tarasov. "A novel parallel algorithm for 3D modelling electromagnetic purification of water." MATEC Web of Conferences 210 (2018): 04027. http://dx.doi.org/10.1051/matecconf/201821004027.
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The computational fluid dynamic research in this work has focused on the problem of full-scale three-dimensional modelling water purification processes by the electromagnetic method. Presently, this method of purification was used in the final stage of processing for the production of ultrapure water. In spite of many field experiments, detailed data on such processes can be obtained only by the mathematical modelling. This way allows us to take into account many aspects, for example: real three-dimensional geometry, physical structure of the purification system, heterogeneous composition of the impurities, etc. And also, the mathematical modelling helps to optimize many parameters in order to improve a design of the purification system. Within the framework of the modelling problem, one of the important aspects is the correct description of the three-dimensional flow inside a specific purification system. For this purpose, various mathematical models and numerical approaches are implemented. In this paper, the flow calculation was realized on basis of the Navier-Stokes equations.
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Aralkin, Mikhail V., Andrei N. Dement’ev, and Oleg V. Osipov. "Research of electromagnetic characteristics of planar chiral metastructures based on composite helices components taking into account the heterogeneous Bruggeman model." Physics of Wave Processes and Radio Systems 23, no. 3 (December 27, 2020): 44–55. http://dx.doi.org/10.18469/1810-3189.2020.23.3.44-55.
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In this work a mathematical model of a chiral metamaterial is constructed which based on composite fine-wire helices components, which takes into account the properties of chirality, heterogeneity and dispersion. When constructing the model the chiral metamaterial was considered as a heterogeneous system and described by the Bruggeman model. Inthis work, analytical relationships were obtained for calculating the resonance frequencies of composite helices components. Thedispersion properties of the metamaterial were described using the well-known Condon model. As an example of using the constructed mathematical model, we solved the problem of the reflection (transmission) of a plane electromagnetic wave of linear polarization from a planar layer of the chiral structure under study based on composite helices microelements. A system of linear algebraic equations was obtained to determine the reflection and transmission coefficients of the main and cross-polarized field components. As a result of the numerical simulation, the frequency-selective properties of the metastructure were discovered and the frequencies at which the electromagnetic wave is captured by the planar layer of the metastructure were revealed. A similar effect can be used to creation of frequency selective concentrators (hubs) of microwave energy.
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Kasatkina, N. Yu, I. V. Badretdinova, A. A. Litvinyuk, and V. V. Kasatkin. "Substantiation of technological parameters for the production of flax pulp by alkaline cooking in the microwave field." IOP Conference Series: Earth and Environmental Science 949, no. 1 (January 1, 2022): 012111. http://dx.doi.org/10.1088/1755-1315/949/1/012111.
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Abstract Flax fiber is the most valuable, rapidly renewable source of cellulose. To isolate cellulose from the fiber, it is necessary to get rid of its non-cellulose components: lignin, pectin substances, waxes and hemicellulose. These substances can be removed by cooking flax fiber in an alkaline solution. To intensify the process of destruction of the non-cellulose complex, it is proposed to use the energy of the electromagnetic field of ultrahigh frequencies. The article presents the results of theoretical and experimental studies aimed at establishing the dielectric characteristics of the system components, which make it possible to prove the effectiveness of the effect of the microwave field on the process of destruction of the non-cellulose complex and to deduce the permissible limits of technological parameters. For the effective management of the technological process of alkaline cooking, the dielectric characteristics of the system components are established on the basis of theoretical and experimental studies. To solve this problem, the system was divided into components: fiber, solution, heterogeneous system. Further, the characteristics of each component are determined separately. The established characteristics showed the following values: the dielectric constant of the fiber in the solution reached a value of 24.8, the dielectric constant of the solution-73, the dielectric constant of the heterogeneous system is 64.55. These values allow you to conduct the technological process of delignification with high efficiency indicators.
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Lin, Jiazhe, Rui Xu, and Xiaohong Tian. "Spatiotemporal Dynamics in Reaction–Diffusion Neural Networks Near a Turing–Hopf Bifurcation Point." International Journal of Bifurcation and Chaos 29, no. 11 (October 2019): 1950154. http://dx.doi.org/10.1142/s0218127419501542.
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Since the electromagnetic field of neural networks is heterogeneous, the diffusion phenomenon of electrons exists inevitably. In this paper, we investigate the existence of Turing–Hopf bifurcation in a reaction–diffusion neural network. By the normal form theory for partial differential equations, we calculate the normal form on the center manifold associated with codimension-two Turing–Hopf bifurcation, which helps us understand and classify the spatiotemporal dynamics close to the Turing–Hopf bifurcation point. Numerical simulations show that the spatiotemporal dynamics in the neighborhood of the bifurcation point can be divided into six cases and spatially inhomogeneous periodic solution appears in one of them.
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Yan, Shu Qing, Jing Pei Xie, Wen Yan Wang, and Ji Wen Li. "Microstructure and Tensile Property of Zn-Al Alloy Reinforced with Titanium Produced by Electrolysis." Advanced Materials Research 79-82 (August 2009): 1415–18. http://dx.doi.org/10.4028/www.scientific.net/amr.79-82.1415.
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In this study, some low-titanium aluminum alloys produced by electrolysis were prepared and the effect of various titanium contents on microstructure and tensile property of Zn-Al alloy was investigated. The test results showed that addition of titanium by electrolysis is an effective way to refine the grain size of Zn-Al alloy. As the titanium content is 0.04 wt%, the grain size becomes to be a minimum value and the tensile property of the alloy reaches to the maximum. Electrolysis showed that titanium atoms are to be some inherent particles in low-titanium aluminum alloy. These titanium atoms enter into the aluminum melt liquid and spread to the whole melt rapidly under stirring action of electromagnetic field of the electric current. The heterogeneous phase nuclei are high melting TiC and TiAl3 particles formed from in-situ precipitating trace C and Ti during cooling process. These in-situ precipitating heterogeneous nucleation sites with small dimension, high dispersity, cleaning interface and fine soakage with melt, have better capacity of heterogeneous nucleation than of exotic particles. It may inhibit grain growth faster and more effective in pinning dislocations, grain boundaries or sub-boundaries.
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Karamanos, K., A. Peratzakis, P. Kapiris, S. Nikolopoulos, J. Kopanas, and K. Eftaxias. "Extracting preseismic electromagnetic signatures in terms of symbolic dynamics." Nonlinear Processes in Geophysics 12, no. 6 (September 20, 2005): 835–48. http://dx.doi.org/10.5194/npg-12-835-2005.
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Abstract. When a heterogeneous material is strained, its evolution toward breaking is characterized by the nucleation and the coalescence of micro-cracks before the final break-up. Electromagnetic (EM) emission in a wide frequency spectrum ranging from very low frequencies (VLF) to very high frequencies (VHF) is produced by micro-cracks, which can be considered as the so-called precursors of general fracture. Herein we consider earthquakes (EQs) as large-scale fracture phenomena. We study the capability of nonlinear time series analysis to extract features from pre-seismic electromagnetic (EM) activity possibly indicating the nucleation of the impending EQ. In particular, we want to quantify and to visualize temporal changes of the complexity into consecutive time-windows of the time series. In this direction the original continuous time EM data is projected to a linguistic symbolic sequence and then we calculate the block entropies of the optimal partition. This analysis reveals a significant reduction of complexity of the underlying fracto-electromagnetic mechanism as the catastrophic events is approaching. We verify this result in terms of correlation dimension analysis. We point out that these findings are compatible with results from an independent linear method which uses a wavelet based approach for the estimation of fractal spectral characteristics. Field and laboratory experiments associate the epoch of low complexity in the tail of the precursory emission with the nucleation phase of the impending earthquake.
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Uvarova, Lyudmila A., Irina V. Krivenko, Marina A. Smirnova, and Alexey B. Nadykto. "Electromagnetic Radiation and Heat Transfer in Disperse Systems Consisting of Spherical and Cylindrical Particles." EPJ Web of Conferences 224 (2019): 02008. http://dx.doi.org/10.1051/epjconf/201922402008.
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The article deals with the electromagnetic radiation transfer in systems of spherical disperse particles with different optical characteristics. A model of the electromagnetic radiation transfer in cylindrical particles containing a small volume of different chemical substance is developed. The substance differs substantially from that of the particle in a radiation absorption coefficient for the wavelength under study in the long wave approximation. The finite element method is used to calculate the temperature field for the system of spherical particles in a two-dimensional approximation. The configurations of particle packing is chosen on a random basis, which significantly complicated the calculations, the longitudinal and transverse diameters of particle clusters, the distance between centers of two largest particles, and similar natural geometric properties have been considered as characteristic system dimensions.The possibility of controlling heat transfer in such systems is studied. It follows from our model calculations that both electromagnetic and thermal interaction of dispersed particles can be noticeable at large distances between their centers; that near the boundary of the dispersed particle there is a thermal surface layer of the particle, where the temperature distribution is essentially heterogeneous. It is concluded that the thermal mechanism of destruction of a weakly absorbing particle due to a strong increase in temperature because of electromagnetic resonance in a neighboring particle with a strong absorption. It is established that the effect of collective influences in polydisperse system can change temperature by more than 1,5 times.
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Grandis, Hendra, Michel Menvielle, and Michel Roussignol. "Thin-Sheet Inversion Modeling of Geomagnetic Deep Sounding Data Using MCMC Algorithm." International Journal of Geophysics 2013 (2013): 1–7. http://dx.doi.org/10.1155/2013/531473.
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The geomagnetic deep sounding (GDS) method is one of electromagnetic (EM) methods in geophysics that allows the estimation of the subsurface electrical conductivity distribution. This paper presents the inversion modeling of GDS data employing Markov Chain Monte Carlo (MCMC) algorithm to evaluate the marginal posterior probability of the model parameters. We used thin-sheet model to represent quasi-3D conductivity variations in the heterogeneous subsurface. The algorithm was applied to invert field GDS data from the zone covering an area that spans from eastern margin of the Bohemian Massif to the West Carpathians in Europe. Conductivity anomalies obtained from this study confirm the well-known large-scale tectonic setting of the area.
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Glinskikh, Viacheslav, Oleg Nechaev, Igor Mikhaylov, Kirill Danilovskiy, and Vladimir Olenchenko. "Pulsed Electromagnetic Cross-Well Exploration for Monitoring Permafrost and Examining the Processes of Its Geocryological Changes." Geosciences 11, no. 2 (January 29, 2021): 60. http://dx.doi.org/10.3390/geosciences11020060.
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This paper is dedicated to the topical problem of examining permafrost’s state and the processes of its geocryological changes by means of geophysical methods. To monitor the cryolithozone, we proposed and scientifically substantiated a new technique of pulsed electromagnetic cross-well sounding. Based on the vector finite-element method, we created a mathematical model of the cross-well sounding process with a pulsed source in a three-dimensional spatially heterogeneous medium. A high-performance parallel computing algorithm was developed and verified. Through realistic geoelectric models of permafrost with a talik under a highway, constructed following the results of electrotomography field data interpretation, we numerically simulated the pulsed sounding on the computing resources of the Siberian Supercomputer Center of SB RAS. The simulation results suggest the proposed system of pulsed electromagnetic cross-well monitoring to be characterized by a high sensitivity to the presence and dimensions of the talik. The devised approach can be oriented to addressing a wide range of issues related to monitoring permafrost rocks under civil and industrial facilities, buildings, and constructions.
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S.M, Daniliev, and Danilieva N.A. "Frequency components of radargrams in analyses of shallow soil cavities." International Journal of Engineering & Technology 7, no. 2.13 (April 15, 2018): 127. http://dx.doi.org/10.14419/ijet.v7i2.13.11625.
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The urgency of the issue being studied is determined by widespread large-scale implementation of ground penetrating radar (GPR) method within the study practice of technical state of various engineering-geological sites over a long operational period. Such buildings and structures as dams, architectural landmarks, residential and industrial buildings, temples and churches, roadways and takeoff runways may be referred to main engineering and geological sites which have been studied via ground penetrating radar method. Cracks of different length, orientation and opening, as well as cavities of various localization, being distinguished by filling material, are the main types of irregularities in the above-mentioned sites, which were being formed in the process of prolonged or improper operation. However, due to vastness of the irregularities being studied and the impossibility to include all the types of possible defects into this article, we have settled on the cavities which are the most commonly encountered in the course of practice only. This article considers the approach to analysis of the electromagnetic wave field frequency characteristics being applied during conducting ground penetrating radar studies of irregularities in the structure of engineering-geological sites on the basis of the results of electromagnetic wave fields mathematical simulation, and of the results obtained in experimental studies at real engineering-geological sites as well. There has been proposed a method based of inverse Fourier transformation for studying spectrum shift in georadargrams. The georadargram is a set of registered signals, which is obtained during even movement of the georadar along the survey line. Due to that, this article is aimed at attraction of analysis of wave electromagnetic field attributes in addition to standard methods of ground penetrating radar (GPR) data processing and interpretation, which allows to extend significantly prospect capabilities of GPR method by obtaining extra data on heterogeneous zones parameters at engineering and geological sites, and, thus, proceed from qualitative notions on technical condition of studied object to quantitative ones.
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Franci, Daniele, Stefano Coltellacci, Enrico Grillo, Settimio Pavoncello, Tommaso Aureli, Rossana Cintoli, and Marco Donald Migliore. "An Experimental Investigation on the Impact of Duplexing and Beamforming Techniques in Field Measurements of 5G Signals." Electronics 9, no. 2 (January 29, 2020): 223. http://dx.doi.org/10.3390/electronics9020223.
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The fifth generation mobile network introduces dramatic improvements with respect to the previous technologies. Features such as variable numerology, bandwidth parts, massive Multiple Input Multiple Output (MIMO) and Time Division Duplex (TDD) will extend the capabilities of the 5G wireless systems and, at the same time, will influence the measurement techniques used to assess the compliance with general public electromagnetic field exposure limits. In this study, a heterogeneous set of 5G signals is investigated with the aim of establishing an effective measurement technique suitable for the new technology. Following an experimental approach based on both modulation and zero span analysis, some important characteristics of the 5G system are highlighted and extensively discussed, and experimental procedures for estimating factors associated to TDD (F T D C factor) and beam sweeping (R factor), to be used in the extrapolation formulas, are presented. The results of this study represent a starting point for future investigations on effective methods to estimate both the instant maximum power and the total power transmitted during a 5G radio frame.
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DI, DI, PEITAO DONG, CHAOGUANG WANG, JIAN CHEN, JUNFENG WANG, HAOXU WANG, XUEZHONG WU, and SHENGYI LI. "HIGH-ORDERED AND ULTRA-SENSITIVE PARTICLE-IN-BOWL METALLIC ARRAYS FOR SURFACE ENHANCED RAMAN SPECTROSCOPY." Nano 09, no. 04 (June 2014): 1450050. http://dx.doi.org/10.1142/s1793292014500507.
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High-ordered particle-in-bowl (PIB) arrays are developed in this paper for surface enhanced Raman spectroscopy (SERS). A heterogeneous shadow mask, composing of the chrome (Cr) layer and colloid residues, is used to fabricate the silicon ( Si ) template from where the PIB arrays finally lift-off. The finite difference time domain (FDTD) method is employed to investigate the Raman enhancement mechanism of this PIB architecture. The electromagnetic (EM) field tends to concentrate in the gap between the bowl and the particle forming the "hot spots". The enhancement factor (EF) of the EM field is about 70 with an excitation wavelength of 785 nm. The Raman measurements validate the EM calculation of the PIB arrays. The EF is about 1.12 × 107 using Rodamine 6G (R6G) as probe molecule. The proposed PIB array is high-ordered in morphology and ultra-sensitive in Raman measurement, providing an ideal substrate for SERS-based bio-chemical sensing, disease diagnosis and analytical chemistry.
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Manzoli, Maela. "Boosting the Characterization of Heterogeneous Catalysts for H2O2 Direct Synthesis by Infrared Spectroscopy." Catalysts 9, no. 1 (January 2, 2019): 30. http://dx.doi.org/10.3390/catal9010030.
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Infrared (IR) spectroscopy is among the most powerful spectroscopic techniques available for the morphological and physico-chemical characterization of catalytic systems, since it provides information on (i) the surface sites at an atomic level, (ii) the nature and structure of the surface or adsorbed species, as well as (iii) the strength of the chemical bonds and (iv) the reaction mechanism. In this review, an overview of the main contributions that have been determined, starting from IR absorption spectroscopy studies of catalytic systems for H2O2 direct synthesis, is given. Which kind of information can be extracted from IR data? IR spectroscopy detects the vibrational transitions induced in a material by interaction with an electromagnetic field in the IR range. To be IR active, a change in the dipole moment of the species must occur, according to well-defined selection rules. The discussion will be focused on the advancing research in the use of probe molecules to identify (and possibly, quantify) specific catalytic sites. The experiments that will be presented and discussed have been carried out mainly in the mid-IR frequency range, between approximately 700 and 4000 cm−1, in which most of the molecular vibrations absorb light. Some challenging possibilities of utilizing IR spectroscopy for future characterization have also been envisaged.
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FAN, Peifeng, Hong QIN, and Jianyuan XIAO. "Discovering exact, gauge-invariant, local energy–momentum conservation laws for the electromagnetic gyrokinetic system by high-order field theory on heterogeneous manifolds." Plasma Science and Technology 23, no. 10 (August 27, 2021): 105103. http://dx.doi.org/10.1088/2058-6272/ac18ba.
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Shimelevitch, M. I., E. A. Obornev, I. S. Feldman, and V. A. Novikov. "Numerical simulation of the electromagnetic fields variations under the formation of the fault rupture before earthquake." Proceedings of higher educational establishments. Geology and Exploration, no. 6 (December 28, 2017): 42–48. http://dx.doi.org/10.32454/0016-7762-2017-6-42-48.
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A 2D geoelectric model of a heterogeneous geological medium has been developed taking into account the processes occurred in the geological subj ect of flexure type which transforms into an uplift-thrust structure as a result of deformations. The model is based on a hypothesis of the variation of electrical conductivity of geomaterials in the local area of the fault under subcritical stress-state conditions due to the geodynamical processes. In the shear stress maximum area, in the plane of fracture of the uplift-thrust type, a zone of increased fracturing is developed contributing to the essential decrease of electric resistance due to filling the fractures by fluid - so named «conductive split». A numerical simulation has demonstrated that when transiting from the quasi-stratllied model to a 2D model with the high-resistive shield a redistribution of the total current density in the medium is increased essentially due to the effect of the «conductive split», taking into account the assumed formation of the zone of fracturing. In this case, amplitude of the electromagnetic (EM) field for the longitudinal polarization increases far apart from the area of the «conductive split». The result obtained may be applied as a background for the development of the monitoring technique of the electromagnetic fields measured on a surface of the Earth far apart from the earthquake epicenter and directly over the fault for the controll ing of a level of the fault maturity for the occurrence of the seismic event.
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Frivaldsky, Michal, Miroslav Pavelek, Pavol Spanik, Dagmar Faktorova, and Gabriela Spanikova. "Approximation of complex organic tissue for investigation of the electromagnetic impact." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 38, no. 4 (July 1, 2019): 1334–46. http://dx.doi.org/10.1108/compel-10-2018-0395.
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Purpose The purpose of this paper is to study the performance of the approximated model of biological tissue for development of complex 3 D models. The comparison of results from the complex model of liver tissue and results from the approximated model is provided to validate the proposed approximation method. Design/methodology/approach The proposed model of hepatic tissue (respecting its heterogeneous character up to the microstructure of hepatic lobules) is used for analysis of current field distribution within this tissue. Initially, the complex model of tissue structure (respecting the heterogenous structure) is presented, considering its complicated structure. Consequently, the procedure for the approximation of a complex model is being described. The main motivation is the need for simple, fast and accurate simulation model, which can be consequently used within more complex modeling of human organs for investigation of negative impacts of electrosurgical equipment on heterogenic tissue structure. For these purposes, the complex and approximated model are mutually compared and evaluated. Findings The obtained results are exploitable for the analysis of the probability of injury formation in sensitive tissue structures, and the approximated model shall serve for optimization of complex and time-consuming analyses. Research limitations/implications Research limitations include development of precise and fast electro-magnetic simulation model of biological tissue. Practical implications Practical implications is focused on the optimization processes of the electro-surgical procedures. Originality/value The originality of the paper concerns the approximation method of organic tissue modeling.
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Yang, Y. P., and D. W. Emerson. "Electromagnetic conductivities of rock cores: Theory and analog results." GEOPHYSICS 62, no. 6 (November 1997): 1779–93. http://dx.doi.org/10.1190/1.1444278.
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Measurement theory developed for a laboratory investigation of electromagnetic characteristics of conductive and magnetic rocks agreed with experiments performed on synthetic conductive samples using a multifrequency coil‐bridge system in the 10 kHz to 4 MHz range. The theoretical analysis also provides a basic and useful method for the study of inductive [electromagnetic (EM)] conductivity and magnetic susceptibility spectra from conductive and/or magnetic samples. The skin effect, an important consequence of eddy current behavior, affects EM measurements and can be recognized by varying the energizing frequency. Investigations of the EM respses of 104 synthetic cores, of five types, revealed that textural effects, i.e., the structure, arrangement, and particle size of the conducting elements exerted a large influence on results. These analog cores contained a range of conductors, including copper wires, graphite powder, aluminum particles, and magnetite‐ilmenite grains, set in a matrix of insulating plaster or wax, representing models of layered, stringer, disseminated, network, massive, and magnetite‐rich mineralizations. For a heterogeneous sample, the laboratory‐measured EM conductivity depends strongly on the structure and orientation of the conducting materials and usually differs from the galvanic conductivity. For a sample with insulated conducting particles, the measured EM conductivity decreases with the increasing square of the sample diameter. This indicates that EM field methods may not respond well to disseminated targets with dispersed conducting minerals even at high concentrations. A mechanism attributed to magnetic loss produced unrealistically high apparent conductivities for magnetite‐bearing samples, especially at low frequencies (f < 100 kHz). For a conductive magnetite sample (σ >1 S/m), the effect of magnetic loss can be eliminated at high frequencies (f > 400 kHz ), and the ohmic conductivity of the magnetite sample can then be estimated.
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Babcock, S. E., and D. C. Larbalestier. "Observations and implications of grain boundary dislocation networks in high-angle YBa2Cu3O7−δ grain boundaries." Journal of Materials Research 5, no. 5 (May 1990): 919–28. http://dx.doi.org/10.1557/jmr.1990.0919.
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Regular networks of localized grain boundary dislocations (GBDs) have been imaged by means of transmission electron microscopy in three different types of high-angle grain boundaries in YBa2Cu3O7-δ, implying that these boundaries possess ordered structures upon which a significant periodic strain field is superimposed. The occurrence of these GBD networks is shown to be consistent with the GBD/Structural Unit and Coincidence Site Lattice (CSL)/Near CSL descriptions for grain boundary structure. Thus, these dislocations appear to be intrinsic features of the boundary structure. The spacing of the observed GBDs ranged from ∼10 nm to ∼100 nm. These GBDs make the grain boundaries heterogeneous on a scale that approaches the coherence length and may contribute to their weak-link character by producing the “superconducting micro-bridge” microstructure which has been suggested on the basis of detailed electromagnetic measurements on similar samples.
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Zhang, Ai Rong. "The Integration on Electrical Control Systems Based on Optimized Method." Advanced Materials Research 490-495 (March 2012): 2604–8. http://dx.doi.org/10.4028/www.scientific.net/amr.490-495.2604.
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Very large scale integration (VLSI) applications have improved control implementation performance. Indeed, an application specific integrated circuit (ASIC) solution can exploit efficiently specificities of the control algorithms that fixed hardware architecture cannot do. For example, parallel calculation cannot be included in a software solution based on sequential processing. In addition, ASIC can reduce wire and electromagnetic field interference by a fully system on a chip (SoC) integration. However, there are still two main drawbacks to an integrated circuit solution: design complexity and reuse difficulty. This is true even with programmable logic device (PLD) solutions. Conception aid developer (CAD) combined with hardware description languages (HDL) and VLSI design methodology have accelerated conception and reuse. Nevertheless, the main problem of integrated circuit design is to define the hardware architecture; this is particularly true for heterogeneous algorithm structures such as electrical controls.
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Contoyiannis, Y. F., S. M. Potirakis, and K. Eftaxias. "The Earth as a living planet: human-type diseases in the earthquake preparation process." Natural Hazards and Earth System Sciences 13, no. 1 (January 25, 2013): 125–39. http://dx.doi.org/10.5194/nhess-13-125-2013.
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Abstract. The new field of complex systems supports the view that a number of systems arising from disciplines as diverse as physics, biology, engineering, and economics may have certain quantitative features that are intriguingly similar. The Earth is a living planet where many complex systems run perfectly without stopping at all. The earthquake generation is a fundamental sign that the Earth is a living planet. Recently, analyses have shown that human-brain-type disease appears during the earthquake generation process. Herein, we show that human-heart-type disease appears during the earthquake preparation of the earthquake process. The investigation is mainly attempted by means of critical phenomena, which have been proposed as the likely paradigm to explain the origins of both heart electric fluctuations and fracture-induced electromagnetic fluctuations. We show that a time window of the damage evolution within the heterogeneous Earth's crust and the healthy heart's electrical action present the characteristic features of the critical point of a thermal second-order phase transition. A dramatic breakdown of critical characteristics appears in the tail of the fracture process of heterogeneous system and the injured heart's electrical action. Analyses by means of Hurst exponent and wavelet decomposition further support the hypothesis that a dynamical analogy exists between the geological and biological systems under study.
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Meju, Max A. "A simple geologic risk-tailored 3D controlled-source electromagnetic multiattribute analysis and quantitative interpretation approach." GEOPHYSICS 84, no. 3 (May 1, 2019): E155—E171. http://dx.doi.org/10.1190/geo2018-0063.1.
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Three-dimensional surveying is the method of choice in marine controlled-source electromagnetic (CSEM) exploration for hydrocarbons in frontier regions, but robust interpretation of the typically large-size field data faces significant challenges, including how to determine the correct resistivity, depth, and lateral limits of hydrocarbon-saturated reservoirs in the presence of heterogeneous host rocks or anisotropy and how to relate CSEM information to the key elements of geologic prospect evaluation (the presence of source rocks, migration and charge, reservoir rock, trap, and seal). We have developed a simple geologic risk-tailored approach for multiattribute analysis and first-pass interpretation of CSEM data in frontier exploration in which little prior information is available. First, geometric normalization of electric field amplitudes at each receiver location yields “phase-consistent” sounding curves that directly represent subsurface electrical structure (and can indicate reservoir rock presence). It enables accurate determination of seafloor resistivity (whose areal variation and direct correlation with seepage-induced geochemical and seismic shallow-gas anomalies can indicate the presence of a working petroleum system). Edge-detection attributes are then used to determine the geographical position and boundary shape of anomalous 3D resistive bodies (the trap presence and structural closure). Keeping these known parameters fixed, the most likely burial depth and resistivities of the sought 3D bodies are found using a simple line search technique involving rigorous 3D modeling and the results are validated and optimized post facto using seismic depth constraints to locally improve the prediction of the size and resistivities of hydrocarbon-charged or water-bearing sections crucial for prospect derisking, reserve estimation, and well placement.
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Neven, Alexis, Pradip Kumar Maurya, Anders Vest Christiansen, and Philippe Renard. "tTEM20AAR: a benchmark geophysical data set for unconsolidated fluvioglacial sediments." Earth System Science Data 13, no. 6 (June 15, 2021): 2743–52. http://dx.doi.org/10.5194/essd-13-2743-2021.
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Abstract. Quaternary deposits are complex and heterogeneous. They contain some of the most abundant and extensively used aquifers. In order to improve the knowledge of the spatial heterogeneity of such deposits, we acquired a large (1500 ha) and dense (20 m spacing) time domain electromagnetic (TDEM) data set in the upper Aare Valley, Switzerland (available at https://doi.org/10.5281/zenodo.4269887; Neven et al., 2020). TDEM is a fast and reliable method to measure the magnetic field directly related to the resistivity of the underground. In this paper, we present the inverted resistivity models derived from this acquisition. The depth of investigation ranges between 40 and 120 m, with an average data residual contained in the standard deviation of the data. These data can be used for many different purposes: from sedimentological interpretation of quaternary environments in alpine environments, geological and hydrogeological modeling, to benchmarking geophysical inversion techniques.
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Sakemi, Daisuke, Nick Serpone, and Satoshi Horikoshi. "Search for the Microwave Nonthermal Effect in Microwave Chemistry: Synthesis of the Heptyl Butanoate Ester with Microwave Selective Heating of a Sulfonated Activated Carbon Catalyst." Catalysts 11, no. 4 (April 2, 2021): 466. http://dx.doi.org/10.3390/catal11040466.
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The heptyl butanoate ester was synthesized from butanoic acid and heptanol in a heterogeneous medium in the presence of sulfonated activated carbon (AC-SO3H) catalyst particles subjected to microwave irradiation, which led to higher conversion yields (greater product yields) than conventional heating with an oil bath. The advantage of the microwaves appeared only when the moisture content in the butanoic acid batch(es) was high, suggesting that, unlike conventional heating, the reverse reaction caused by the moisture content and/or by the byproduct water was suppressed by the microwaves. This contrasted with the results that were found when carrying out the reaction in a homogeneous medium in the presence of the 2,4,6-trimethylpyridinium-p-toluene sulfonate (TMP-PTS) catalyst, as product yields were not improved by microwave heating relative to conventional heating. The removal of moisture/water content in the reaction solution was more pronounced when the reactor was cooled, as the reaction yields were enhanced via selective heating of the heterogeneous catalyst. A coupled electromagnetic field/heat transfer analysis gave credence to the selective heating of the AC-SO3H catalyst, which was further enhanced by cooling the reactor. It was deduced that unforeseen impurities and local high-temperature fields generated on the surface of small fine catalyst particles may have had an effect on the microwave chemistry such that the associated phenomena could be mistaken as originating from a nonthermal effect of the microwaves. Accordingly, it is highly recommended that impurities and selective heating be taken into consideration when examining and concluding the occurrence of a microwave nonthermal effect.