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Journal articles on the topic 'Electromagnetic field emitter'
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1
Sydorchuk, O. L., S. O. Sobolenko, V. V. Kovalchuk, and L. M. Maryshchuk. "Solving an Equation by the Saddle Point Method for the Electromagnetic Field Scattered by the Opening Horn Emitter." Visnyk NTUU KPI Seriia - Radiotekhnika Radioaparatobuduvannia, no. 91 (March 30, 2023): 28–36. https://doi.org/10.20535/radap.2023.91.28-36.
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Horn emitters are widely used as part of antenna systems in modern radio-electronic equipment, radars, television, etc. The simplicity of their design and high-level technical characteristics are major advantages of the emitters. However, there are certain disadvantages. In order to assess and possibly eliminate them, we usually do electrodynamics calculations of the electromagnetic field scattered from the horn emitter when designing new antenna systems and take into account all the factors, which cause scattering in order to reduce it. The well-known calculation methods result in the appearance of algorithms in open form, which usually do not have any exact solutions. In the few cases where their strict solutions are known, the algorithms look rather complex and, even with the help of modern software packages of computing tools, do not allow us to understand physics or causes of such a process. In such cases, approximate asymptotic methods shall be widely applied.It has been established that it is appropriate to use the saddle point method to solve boundary value problems in determining the electromagnetic field scattered from a horn emitter. We carried out a detailed analysis of the saddle point method by solving an equation for the electromagnetic field scattered by an opening horn emitter, which was a causes of diffraction on the horn in order to reduce the diffraction.The publication involves two tasks: a detailed analysis of the saddle point method for solving the integral electromagnetic field equation and determination of the field scattered by the opening horn emitter with application of the saddle point method.The problem statement includes one of the cases of a plane wave free incidence, namely, when the wave is polarized normally to the plane of incidence (S-polarization), that is, the plane of wave polarization and the incidence plane are mutually perpendicular.We have obtained an expression for the field scattered by the opening horn emitter with normal polarization of the incident wave to the plane of its incidence after taking integrals by the saddle point method. Unlike complex modern software products, this solution will allow us to analyze physical processes that occur when the electromagnetic field is reflected by the opening horn emitter. For example, we have analysed the scattered field in two planes. These simple expressions may be used to easily make scattered field diagrams in Mathcad.Further studies will take into account beyond cutoff reflection coefficients and the horn emitter load.
2
Kosulina, Natalia, Maksym Sorokin, Yuri Handola, Stanislav Kosulin, and Kostiantyn Korshunov. "Forming an elliptical directional diagram of the sectoral horn antenna for flow irradiation of sugar beet seeds by electromagnetic field." Eastern-European Journal of Enterprise Technologies 1, no. 5 (121) (2023): 26–37. http://dx.doi.org/10.15587/1729-4061.2023.273972.
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The object of research is the process that forms an elliptical directional diagram of the H-sector horn antenna for flow irradiation of seeds with the electromagnetic field. The emitter of electromagnetic energy is presented as one of the main elements of installations for irradiating seeds with an electromagnetic field before sowing. This parameter was investigated by taking into account the values of the biotropic parameters of the low-energy electromagnetic field under the conditions of flow processing. This paper reports a study into the parameters of the H-sector horn emitter for irradiation of sugar beet seeds with a low-energy electromagnetic field at a frequency of 73...75 GHz in continuous flow. Thus, one should use the H-sectoral horn emitter with the following parameters: aperture width aa=20 mm; horn length RH=35 mm; b=1.8 mm. It is determined that in order to irradiate sugar beet seeds on the conveyor plane with a power flow density of P=100 μW/cm2, it is necessary to place two horns 1200 mm above the conveyor at a distance of 2540 mm from each other. It was checked that the treatment of sugar beet seeds with electromagnetic radiation in a continuous flow with a capacity of 300 kg/h is possible with a power of up to 2 W supplied to two horn antennas; the speed of the conveyor is 15 cm/s. The parameters of the sectoral horn for an elliptical directional diagram were studied by dividing the main task into internal and external. According to the results of the research, it is possible to build a base of geometric presets for adjusting installations for different types of seeds, the desired performance, the structural features of installations, as well as existing emitters
3
Jakubiuk, Kazimierz, Daniel Kowalak, and Mikołaj Nowak. "The forming and emission of high power electromagnetic pulses." ITM Web of Conferences 19 (2018): 01001. http://dx.doi.org/10.1051/itmconf/20181901001.
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An impulse energy source, a power conditioning system and an electromagnetic field emitter are essential to generate an electromagnetic field pulse (EMFP) with a specific frequency bandwidth. Selected simulation results for a power conditioning system consisting of a fuse opening switch and a paraboloidal electromagnetic emitter have been presented in this article. The synthetic system examined in the simulation is powered by an impulse capacitor instead of a flux compression generator (FCG) used in practice. The obtained results confirm that pulse generation and emission of high-power EMFP is possible.
4
Natalia, Kosulina, Sorokin Maksym, Handola Yuri, Kosulin Stanislav, and Korshunov Kostiantyn. "Forming an elliptical directional diagram of the sectoral horn antenna for flow irradiation of sugar beet seeds by electromagnetic field." Eastern-European Journal of Enterprise Technologies 1, no. 5(121) (2023): 26–37. https://doi.org/10.15587/1729-4061.2023.273972.
Full textAbstract:
The object of research is the process that forms an elliptical directional diagram of the H-sector horn antenna for flow irradiation of seeds with the electromagnetic field. The emitter of electromagnetic energy is presented as one of the main elements of installations for irradiating seeds with an electromagnetic field before sowing. This parameter was investigated by taking into account the values of the biotropic parameters of the low-energy electromagnetic field under the conditions of flow processing. This paper reports a study into the parameters of the H-sector horn emitter for irradiation of sugar beet seeds with a low-energy electromagnetic field at a frequency of 73...75 GHz in continuous flow. Thus, one should use the H-sectoral horn emitter with the following parameters: aperture width a<sub>a</sub>=20 mm; horn length R<sub>H</sub>=35 mm; b=1.8 mm. It is determined that in order to irradiate sugar beet seeds on the conveyor plane with a power flow density of P=100 μW/cm<sup>2</sup>, it is necessary to place two horns 1200 mm above the conveyor at a distance of 2540 mm from each other. It was checked that the treatment of sugar beet seeds with electromagnetic radiation in a continuous flow with a capacity of 300 kg/h is possible with a power of up to 2 W supplied to two horn antennas; the speed of the conveyor is 15 cm/s. The parameters of the sectoral horn for an elliptical directional diagram were studied by dividing the main task into internal and external. According to the results of the research, it is possible to build a base of geometric presets for adjusting installations for different types of seeds, the desired performance, the structural features of installations, as well as existing emitters
5
Alexeyeva, Lyudmila, and Aziz Gulfariza. "TRANSPORT SOLUTIONS O MAXWELL EQUATIONS AT SUB-LIGHT SPEEDS IN BIQUATERNION REPRESENTATION." JOURNAL OF THE OPEN SYSTEMS EVOLUTION PROBLEMS 26, no. 1 (2024): 64–73. http://dx.doi.org/10.26577/jpeos.2024.v26.i1-i6.
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The most common movable radiation sources of electromagnetic waves among the operating ones located on the platforms of various vehicles. It is obvious that the speed of movement affects the processes of wave propagation in an environment with such electrical conductivity and magnetic permeability, as does the shape of the source itself and the nature of its operation. In this work are constructed and studied transport solutions of the biquaternion wave equation, which is a biquaternion generalization of Maxwell's equations. These equations describe the electromagnetic fields of emitters of electromagnetic (EM) waves and electro-gravimagnetic waves (EGM), moving in a fixed direction with a constant speed, which is less than the speed of propagation of waves in an electromagnetic medium (the speed of light). Fundamental and generalized transport solutions have constructed that describe the EM fields of moving objects in the entire range of speeds, from light to superluminal.The electromagnetic field generated by a moving point emitter on the Z-axis described by the biquaternion Green's function (bifunction) in a moving coordinate system constructed using the Fourier transform of generalized functions. The energy density and Poynting vector of this field were determined. Influence of movement speed researched on field characteristics
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Sokolovsky, A. I., and S. F. Lyagushyn. "Dicke model investigations in the framework of reduced description method." Journal of Physics and Electronics 32, no. 1-2 (2024): 3–21. https://doi.org/10.15421/332401.
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The reduced description method proceeds from Bogolyubov’s idea that at large times the non-equilibrium system evolution can be described with the limited number of parameters and principle of correlation weakening. The way to the right choice of such parameters and constructing the time evolution equations for them was opened by the works of Kharkiv school in statistical physics. A quarter of a century ago at Dnipropetrovsk National University the developed method was first applied to the Dicke system of two-level emitters interacting via electromagnetic field. The paper presents a short review of the results obtained. They include the analysis of Dicke Hamiltonian structure, the choice of reduced description parameters satisfying the Peletminskii – Yatsenko scheme conditions, the realization of this scheme for concentrated and prolonged Dicke systems resulting in the temporal equation for emitter subsystemstatistical operator. The reduced description method possibilities are illustrated with using the effective Hamiltonian concept, in particular taking into account emitter motion and higher correlations. Reformulating the theory in terms of electromagnetic field allowed to construct the electrodynamics of medium formed by two-level emitters with considering binary correlations of field variables and to put forward the problem of correlation development picture. A new method of investigating correlations in quasispin subsystem with using ferromagnetism theory approach was also proposed.
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Herschmann, R., and O. Büchel. "Radiation characteristics of a coaxial waveguide with eccentric inner conductor for application in hyperthermia and microwave reflex therapy." Advances in Radio Science 5 (June 13, 2007): 189–95. http://dx.doi.org/10.5194/ars-5-189-2007.
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Abstract. This paper examines the radiation characteristics of a contact emitter conceived for application in hyperthermia and microwave reflex therapy. It is important to analyse the distribution of power density in the near field area, as the radiator's therapeutic sphere of activity is localized here. The contact emitter is a coaxial radiator with an eccentric course of the inner conductor. According to Huygens principle, a theoretical view of the near field radiation characteristics is made by determining the equivalent current densities in the emitter aperture. It is shown that by an eccentric shift of the inner conductor, an almost isotropic near field radiation pattern and power density can be achieved. For this, the electromagnetic field in the emitter aperture is determined by using a Bipolar coordinate system. This calculation considers only the fundamental TEM mode of the contact emitter. Besides the theoretical results near and far fields are simulated using the programme system Ansoft HFSS.
8
Gupta, Preeti, Pooja Jain, and O. G. Kakde. "Deep Learning Techniques in Radar Emitter Identification." Defence Science Journal 73, no. 5 (2023): 551–63. http://dx.doi.org/10.14429/dsj.73.18319.
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In the field of electronic warfare (EW), one of the crucial roles of electronic intelligence is the identification of radar signals. In an operational environment, it is very essential to identify radar emitters whether friend or foe so that appropriate radar countermeasures can be taken against them. With the electromagnetic environment becoming increasingly complex and the diversity of signal features, radar emitter identification with high recognition accuracy has become a significantly challenging task. Traditional radar identification methods have shown some limitations in this complex electromagnetic scenario. Several radar classification and identification methods based on artificial neural networks have emerged with the emergence of artificial neural networks, notably deep learning approaches. Machine learning and deep learning algorithms are now frequently utilized to extract various types of information from radar signals more accurately and robustly. This paper illustrates the use of Deep Neural Networks (DNN) in radar applications for emitter classification and identification. Since deep learning approaches are capable of accurately classifying complicated patterns in radar signals, they have demonstrated significant promise for identifying radar emitters. By offering a thorough literature analysis of deep learning-based methodologies, the study intends to assist researchers and practitioners in better understanding the application of deep learning techniques to challenges related to the classification and identification of radar emitters. The study demonstrates that DNN can be used successfully in applications for radar classification and identification.
 
9
Sekachev, A. F., V. V. Shalai, Yu D. Zemenkov, A. F. Fitzner, and A. E. Yakovlev. "Experimental study of the transmission of energy of a microwave electromagnetic field into the oil environment employing a submersible emitter." Oil and Gas Studies, no. 3 (July 15, 2021): 120–29. http://dx.doi.org/10.31660/0445-0108-2021-3-120-129.
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The supply of heat to oil media pumped by pipeline transport systems is one of the main problems in the oil industry. The article describes a method for supplying heat to oil-containing media using the energy of an electromagnetic field. The possibility of releasing surfaces in contact with oil sludge under the influence of electromagnetic fields has been shown by experiment. We describe the design and parameters of a biconical horn radiator of a microwave electromagnetic field operating at a frequency of 2 450 MHz. A method for generating energy and transmitting it to the emitter by means of a coaxial cable is shown. Testing the emitter in oil placed in an optically transparent and radio-tight double-walled tank is presented. The design of the stand allows us to safely examine the thermal process using a thermal imager. The installation made it possible to heat 7 liters of oil at 15 °C in 12 minutes.
10
Komarov, V. A. "MAGNETOELASTIC ELECTROMAGNETIC ACOUSTIC TRANSFORMATION. PART 7." Kontrol'. Diagnostika, no. 268 (October 2020): 30–39. http://dx.doi.org/10.14489/td.2020.10.pp.030-039.
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A double EMAT has been considered analytically and experimentally for the perpendicular arrangement of the electromagnetic field of the emitter and the polarizing field in ferromagnets. At relatively low conductivities of the samples the transformation leads to the significant discrepancy between the maxima position of the shear waves elastic displacements and the EMF maxima position of the double EMAT along the interface due to the Wiedemann effect. The discrepancy decreases with the approaching to the center of symmetry of the emitter. It has been shown that the transformation efficiency at the Wiedemann effect is determined by the ratio of linear magnetostriction along the direction of the polarizing field to the magnetization along this field. Experimental measurements showed that the Wiedemann effect is characterized by the stretched curve of the EMAT efficiency dependence on the induction or amplitude of the polarizing field with the increase in these values up to the magnetic saturation of the ferromagnet. When the magnetization of the material is normal relative to the interface, the dependence on the conversion efficiency is determined only by the Wiedemann effect for ferrite and by the Wiedemann effect and the electrodynamic effect for a well conducting sample material.
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Komarov, V. A. "MAGNETOELASTIC ELECTROMAGNETIC ACOUSTIC TRANSFORMATION. PART 7." Kontrol'. Diagnostika, no. 268 (October 2020): 30–39. http://dx.doi.org/10.14489/td.2020.10.pp.030-039.
Full textAbstract:
A double EMAT has been considered analytically and experimentally for the perpendicular arrangement of the electromagnetic field of the emitter and the polarizing field in ferromagnets. At relatively low conductivities of the samples the transformation leads to the significant discrepancy between the maxima position of the shear waves elastic displacements and the EMF maxima position of the double EMAT along the interface due to the Wiedemann effect. The discrepancy decreases with the approaching to the center of symmetry of the emitter. It has been shown that the transformation efficiency at the Wiedemann effect is determined by the ratio of linear magnetostriction along the direction of the polarizing field to the magnetization along this field. Experimental measurements showed that the Wiedemann effect is characterized by the stretched curve of the EMAT efficiency dependence on the induction or amplitude of the polarizing field with the increase in these values up to the magnetic saturation of the ferromagnet. When the magnetization of the material is normal relative to the interface, the dependence on the conversion efficiency is determined only by the Wiedemann effect for ferrite and by the Wiedemann effect and the electrodynamic effect for a well conducting sample material.
12
Svendsen, Mathias B. M., and Beatriz Olmos. "Modified dipole-dipole interactions in the presence of a nanophotonic waveguide." Quantum 7 (August 22, 2023): 1091. http://dx.doi.org/10.22331/q-2023-08-22-1091.
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When an emitter ensemble interacts with the electromagnetic field, dipole-dipole interactions are induced between the emitters. The magnitude and shape of these interactions are fully determined by the specific form of the electromagnetic field modes. If the emitters are placed in the vicinity of a nanophotonic waveguide, such as a cylindrical nanofiber, the complex functional form of these modes makes the analytical evaluation of the dipole-dipole interaction cumbersome and numerically costly. In this work, we provide a full detailed description of how to successfully calculate these interactions, outlining a method that can be easily extended to other environments and boundary conditions. Such exact evaluation is of importance as, due to the collective character of the interactions and dissipation in this kind of systems, any small modification of the interactions may lead to dramatic changes in experimental observables, particularly as the number of emitters increases. We illustrate this by calculating the transmission signal of the light guided by a cylindrical nanofiber in the presence of a nearby chain of emitters.
13
El-Bayeh, Claude Ziad. "Claude Ziad El-A Proposed Algorithm for Detecting Invisible Celestial Objects by Generalizing the Planck’s Blackbody Radiation Law." Energy, Environment and Storage 2, no. 2 (2022): 14–23. http://dx.doi.org/10.52924/giah1715.
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Blackbody radiation was proposed by Planck to measure the temperature of a body by observing its electromagnetic waves spectrum. However, when it comes to massive objects such as stars, other factors can affect the emitted wavelength of the light from the body, such as gravitational field and doppler effect, which are caused not only by the star but also by the observer (i.e., Earth). Hence, predicting the surface temperature of a star by using only its radiation might not be accurate especially for massive stars. To solve the problem, and to give more accuracy to the measurement, this paper proposes an algorithm and a modification of the Plank’s blackbody radiation theory by considering the impact of relativistic Doppler effect and the gravitational field of both, the emitter (i.e., star), and the receiver (i.e., Earth). For validation purposes, the proposed modification theory is compared to the original one proposed by Planck using four different case studies, (a) sun is considered as an emitter and the earth as the receiver; (b) a massive star is considered as an emitter and the earth as a receiver; (c) the earth is considered as an emitter and a massive star as a receiver; finally (d) two identical stars are considered as emitter and receiver, respectively. Results show that our proposed method works perfectly and gives more accurate results compared to the traditional Plank’s theory since the impact of gravitational field and Doppler effect on the spectrum are considered.
14
Sydorchuk, O., V. Zalevskiy, and V. Kovalchuk. "SIMULATION OF REFLECTION FROM HORN EMITTERS OF PHASED ANTENNA ARRAYS TO DETERMINE THE COEFFICIENTS." Проблеми створення, випробування, застосування та експлуатації складних інформаційних систем, no. 25 (I) (December 25, 2023): 76–89. http://dx.doi.org/10.46972/2076-1546.2023.25.07.
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The article is devoted to the problem of researching reflection coefficients from horn emitters that are part of a phased antenna array. It was found that the advantage of using horn antennas is the high directivity of their radiation, a significant efficiency and a fairly high amplification factor. However, their main drawback is the back radiation (scattering) of electromagnetic waves by the elements of the antenna design. This affects the radar visibility of samples of weapons and military equipment and their electromagnetic compatibility. To eliminate these shortcomings, the article analyzes the differential characteristics of the backscatter diagrams of aperture antennas in order to improve the mathematical model of the reradiated field study, taking into account the reflection coefficients from horn emitters. In the course of the study, the causes and regularities of such a phenomenon as the reflection of electromagnetic waves from internal inhomogeneities of horn antennas were clarified, in order to reduce it. The given graphs of the dependence of the amplitudes of the reflected electromagnetic field on the observation angles show that the improvement of the alignment in the antenna path will cause an increase in the maximum signal amplitude in the transmission mode. According to the principle of inversion of antennas, such an arrangement will improve the absorption of waves of higher types directed to the openings of a single emitter or an equidistant antenna array. This will reduce the voltage standing wave factor and the level of side lobes. Therefore, the sounding radar station will receive a reduced level of the reflected signal, which will improve the defense of weapons samples that include a horn as a separate antenna or as part of equidistant linear phased antenna arrays. Keywords: phased antenna array; pyramidal horn emitter; reduction of the effective scattering surface; reflection coefficient.
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Yada, Kyohei, Takashi Shimojo, Hideyuki Okada, and Atsushi Sakurai. "Theoretical and Numerical Analysis of Active Switching for Narrow-Band Thermal Emission with Graphene Ribbon Metasurface." Sensors 21, no. 20 (2021): 6738. http://dx.doi.org/10.3390/s21206738.
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Components smaller than the wavelength of electromagnetic waves are called meta-atoms. Thermal emission can be controlled by an artificial structure in which these meta-atoms are arranged on the surface. This artificial structure is called a metasurface, and its optical properties are determined by the materials and shapes of the meta-atoms. However, optical devices may require active control of thermal emission. In the present study, we theoretically and numerically analyze a wavelength-selective emitter using a graphene ribbon metasurface. The graphene ribbon metasurface consists of a graphene ribbon array, potassium bromide thin film, and silver substrate. The geometric parameters of the graphene metasurface are determined based on an equivalent circuit model that agrees well with the results of the electromagnetic field analysis (rigorous coupled-wave analysis). The proposed emitter causes impedance matching depending on the conductivity of the graphene ribbon in a very narrow wavelength range. The conductivity of graphene can be actively controlled by the gate voltage. Therefore, the proposed emitters may realize near-perfect emission with a high quality factor and active controllable switching for various wavelengths. In addition, the quality factor can be changed by adjusting the electron mobility of graphene. The proposed emitter can be used for optical devices such as thermophotovoltaic systems and biosensing.
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Robins, E. S., M. J. G. Lee, and P. Langlois. "Effect of optical diffraction on laser heating of a field emitter." Canadian Journal of Physics 64, no. 1 (1986): 111–17. http://dx.doi.org/10.1139/p86-016.
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The wavelength of the illuminating radiation used in studies of photofield emission is comparable to the diameter of the shank of the field emitter. Under these conditions, diffraction is expected to play an important role in determining the absorption of energy from the electromagnetic field. The complicated geometry of the field emitter has so far prevented an exact calculation of this effect. By considering the diffraction of a plane wave by an idealized model of a field emitter, we have calculated the absorption of energy from an incident focussed laser beam. Calculations based on the present results yield accurate predictions of the magnitude of the temperature rise and its dependence on the position of the focal spot and on the direction of polarization of the incident beam.
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Ren, Feifei, Jinxin Gu, Hang Wei, et al. "Effect of Unit Cell Shape on Switchable Infrared Metamaterial VO2 Absorbers/Emitters." Research 2021 (April 22, 2021): 1–8. http://dx.doi.org/10.34133/2021/9804183.
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Metamaterial absorber/emitter is an important aspect of infrared radiation manipulation. In this paper, we proposed four simple switchable infrared metamaterial absorbers/emitters with Ag/VO2 disks on the Ag plane employing triangle, square, hexagon, and circle unit cells. The spectral absorption peaks whose intensities are above 0.99 occur at ~4 μm after structure optimization when VO2 is in insulating state and disappear when VO2 becomes metallic state. The simulated electromagnetic field reveals that the spectral absorption peaks are attributed to the excitation of magnetic polariton within the insulating VO2 spacer layer, whose values exceed 1.59 orders of magnitude higher than the incident magnetic field. Longer resonant wavelength would be excited in square arrays because its configuration is a better carrier of charges at the same spans. For absorption stability, the absorbers/emitters with square and circular structures do not have any change with the polarization angles changing from 0° to 90°, due to the high rotational symmetric structure. And four absorbers/emitters reveal similar shifts and attenuations under different incident angles. We believed that the switchable absorber/emitter demonstrates promising applications in the sensing technology and adaptive infrared system.
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Wang, Junyi, Youlin Wang, Xiaohang Chen, Jincan Chen, and Shanhe Su. "Hot carrier-based near-field thermophotovoltaics with energy selective contacts." Applied Physics Letters 122, no. 12 (2023): 122203. http://dx.doi.org/10.1063/5.0143300.
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A model of the thermophotovoltaic device combining a near-field thermal emitter and a hot-carrier solar cell is established. The fluctuating electromagnetic near-field theory for the radiative thermal transport and Landauer's formula for the carrier extraction are introduced. Expressions for the efficiency and the power output of the device are derived. How the voltage and the extraction energy of the energy selective contacts affect the performance of the device is revealed. The results show that the efficiency of the proposed device can be greatly enhanced by exploiting the radiation between the emitter and the cell and extracting carriers through electron tunneling effects.
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Li, Gen, Tao Shu, Hanchao Zheng, Chenjie Lin, Pengxiang Zhang, and Yingying Wang. "Research on Material Selection and Electromagnetic Characteristics of Composite Electromagnetic launcher." Journal of Physics: Conference Series 2450, no. 1 (2023): 012007. http://dx.doi.org/10.1088/1742-6596/2450/1/012007.
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Abstract The armature and rail thermal ablation caused by the current concentration phenomenon will affect the service life of the guideway during the operation of the compound four-rail electromagnetic emitter. With different rail materials simulated and analyzed using the finite element analysis method and the ANSYS software, the composite four-rail electromagnetic launcher’s current density distribution and electromagnetic field distribution were designed to optimize and improve the thermal ablation of the armature and rail of the composite electromagnetic launcher. The results show that the copper steel composite electromagnetic launcher can improve the current concentration and electromagnetic shielding ability.
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Dumansky, O. V., and L. M. Mikhailova. "A GROUND IS AS EMITTER FOR TREATMENT OF ENDOMETRITU OF ZOONS." Podilian Bulletin: Agriculture, Engineering, Economics, no. 32 (May 29, 2020): 108–12. http://dx.doi.org/10.37406/2706-9052-2020-1-13.
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The article proposes to experimentally investigate the corrugated conical emitter in order to confirm the theoretical calculations of the reflection coefficient of the electromagnetic field from the opening of the investigated corrugated conical emitter. Research is based on the influence of electromagnetic fields on the physicochemical processes in biological objects. Theoretical studies have shown that for industrial use requires a radiator with a frequency range of 30-31 GHz and a diameter of not more than 30 mm, which should provide a width of the radiation pattern within 24-30 mm. For practical purposes, it is necessary to estimate the reflection coefficient of the calculated corrugated emitter. For the study we use a conical corrugated irradiator, the length of which from the opening to the phase center is 21 mm. The diameter of the radiating aperture is 25 mm. The basic geometrical parameters of the corrugation: h = 2.5 mm, c = 1.25 mm, b = 1.25 mm. To feed the transmitter under consideration, a transition from a rectangular waveguide with a cross section of 7.2 × 3.4 mm to a circular diameter of 7 mm is used. Measurements were made at 30 GHz. Since the modulus of the reflection coefficient of the emitter must be close to zero, the method of reflectometer must be used for accurate measurements
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Bayramdurdiyev, Davut Ya, Ramil F. Malikov, Igor V. Ryzhov, and Victor A. Malyshev. "Nonlinear optical dynamics of two-dimensional super-lattices of quantum V-emitters." Journal of Physics: Conference Series 2103, no. 1 (2021): 012225. http://dx.doi.org/10.1088/1742-6596/2103/1/012225.
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Abstract We study theoretically the nonlinear optical response of a super-lattice of regularly arranged three-level identical quantum emitters with a doublet in the excited state to the action of a monochromatic electromagnetic field quasi-resonant to optical transitions in the emitter, using into account the dephasing of the system. The total retarded dipole-dipole interaction of the emitters is accounted for in the mean-field approximation. This interaction plays the role of positive feedback, which (in combination with the immanent nonlinearity of emitters themselves) leads to multistability of the super-lattice response. The stability of different response branches is analyzed using the Lyapunov exponents’ method. Another important property of the super-lattice is its high reflectance in a certain frequency range; i.e., within this range, the super-lattice operates as a perfect nanometer mirror; moreover, reflection can be switched to transmission changing slightly the incident field amplitude (bistability). The possibility of the application of the above-mentioned super-lattice optical properties in nanophotonics is discussed.
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Vasilyev, Alexey A., Alexey N. Vasilyev, and Dmitry Budnikov. "Using Modeling to Select the Type of Microwave Field Emitter for Dense-Layer Grain Dryers." Applied Sciences 13, no. 16 (2023): 9070. http://dx.doi.org/10.3390/app13169070.
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The microwave field is used for drying and disinfecting grains during the pre-sowing seed treatment. The use of a microwave field in these installations leads to an increase in their productivity and a decrease in the energy consumed by them. In grain dryers, where the grain moves in a dense layer without being loosened, one of the challenges in using microwave fields is ensuring sufficient uniformity of the field distribution. In this article, waveguide design options that introduce microwave radiation into the grain layer are discussed. The objective of this study was to use application software to find the optimum type of transmitter from the three options presented. A mathematical simulation of the electromagnetic field distribution was performed with the use of CST Microwave Studio software 2019 in order to evaluate and compare horn-type, rectangular, and semicircular waveguides. The data on the standing wave ratio and radiation efficiency of these types of waveguides have been reported. The specific features of the microwave electromagnetic field distribution and radiation power in the output of these waveguides have been described. The results of mathematical simulations revealed that semicircular waveguides with slot-type radiators are preferable for processing dense grain layers.
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Alaeddine, Ali, Moncef Kadi, Kaouther Daoud, Hichame Maanane, and Philippe Eudeline. "Study of electromagnetic field stress impact on SiGe heterojunction bipolar transistor performance." International Journal of Microwave and Wireless Technologies 1, no. 6 (2009): 475–82. http://dx.doi.org/10.1017/s1759078709990572.
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This paper deals with the various aspects of electromagnetic field impact modeling on the SiGe heterojunction bipolar transistor (HBT) device for microwave applications. This study differs from conventional HBT device reliability research associated with other stresses. The originality of this study comes from the generation of a localized electromagnetic field using the near-field bench. A coupling phenomenon between the electromagnetic field and the micro-strip lines connecting the transistor are evaluated by electromagnetic and electrical simulations. After stress, the input and the transmission scattering parameters are affected. This is primarily due to the deviation of the input impedance and the reduction of the transconductance, respectively. The stress effects have been related to a base current degradation. This degradation is due to a hot carrier introducing generation/recombination trap centers at the Si/SiO2 interface of the emitter–base spacer oxide, which leads to an excess recombination base current.
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Komarov, V. A. "MAGNETOELASTIC ELECTROMAGNETIC ACOUSTIC TRANSFORMATION. PART VI." Kontrol'. Diagnostika, no. 262 (April 2020): 14–21. http://dx.doi.org/10.14489/td.2020.04.pp.014-021.
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In the case of EMAT using overhead transducers, a high-frequency alternating and strong polarizing magnetic fields jointly act on the magnetoelastic medium. These fields can be positioned at different directions to each other. The article analyzes the situation when the polarizing field, located along the interface of the media and the normal component of the emitter variable field are orthogonally related. That is, the classic Wiedemann effect is implemented in EMAT. It has been shown that the Wiedemann effect in EMAT contributes primarily to the generation of shear waves. The generation of longitudinal waves is secondary and less efficient. About an order of magnitude less In fact, the Wiedemann effect can only be observed (compared to the Joule effect) for the materials with low conductivity and for the ferrodielectrics. Increasing the efficiency of the method is possible by increasing the frequency of the current in the transducer. When the conductivity and frequency properly seltcted, the efficiency of the method can compete with EMAT performed by means of the Joule effect.
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Komarov, V. A. "MAGNETOELASTIC ELECTROMAGNETIC ACOUSTIC TRANSFORMATION. PART VI." Kontrol'. Diagnostika, no. 262 (April 2020): 14–21. http://dx.doi.org/10.14489/td.2020.04.pp.014-021.
Full textAbstract:
In the case of EMAT using overhead transducers, a high-frequency alternating and strong polarizing magnetic fields jointly act on the magnetoelastic medium. These fields can be positioned at different directions to each other. The article analyzes the situation when the polarizing field, located along the interface of the media and the normal component of the emitter variable field are orthogonally related. That is, the classic Wiedemann effect is implemented in EMAT. It has been shown that the Wiedemann effect in EMAT contributes primarily to the generation of shear waves. The generation of longitudinal waves is secondary and less efficient. About an order of magnitude less In fact, the Wiedemann effect can only be observed (compared to the Joule effect) for the materials with low conductivity and for the ferrodielectrics. Increasing the efficiency of the method is possible by increasing the frequency of the current in the transducer. When the conductivity and frequency properly seltcted, the efficiency of the method can compete with EMAT performed by means of the Joule effect.
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Bogolyubov, N. N., and A. V. Soldatov. "Low-frequency fluorescence spectrum of a laser driven polar quantum emitter damped by squeezed vacuum with finite bandwidth." Journal of Physics: Conference Series 2056, no. 1 (2021): 012001. http://dx.doi.org/10.1088/1742-6596/2056/1/012001.
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Abstract A two-level quantum emitter with broken inversion symmetry driven by external semiclassical monochromatic high-frequency electromagnetic (e.g., laser) field and damped by squeezed vacuum reservoir with finite bandwidth is presented. The squeezed vacuum source is assumed to be either degenerate parametric oscillator (DPO) or a non-degenerate parametric oscillator (NDPO). It is shown that the shape of low-frequency fluorescence spectrum of the emitter can be effectively alternated by controlling the degree of the squeezed vacuum source degeneration and phase of the squeezing.
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Feist, Johannes, Antonio I. Fernández-Domínguez, and Francisco J. García-Vidal. "Macroscopic QED for quantum nanophotonics: emitter-centered modes as a minimal basis for multiemitter problems." Nanophotonics 10, no. 1 (2020): 477–89. http://dx.doi.org/10.1515/nanoph-2020-0451.
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AbstractWe present an overview of the framework of macroscopic quantum electrodynamics from a quantum nanophotonics perspective. Particularly, we focus our attention on three aspects of the theory that are crucial for the description of quantum optical phenomena in nanophotonic structures. First, we review the light–matter interaction Hamiltonian itself, with special emphasis on its gauge independence and the minimal and multipolar coupling schemes. Second, we discuss the treatment of the external pumping of quantum optical systems by classical electromagnetic fields. Third, we introduce an exact, complete, and minimal basis for the field quantization in multiemitter configurations, which is based on the so-called emitter-centered modes. Finally, we illustrate this quantization approach in a particular hybrid metallodielectric geometry: two quantum emitters placed in the vicinity of a dimer of Ag nanospheres embedded in a SiN microdisk.
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Wei, Wei, Qi Liu, Xia Zhang, and Xin Yan. "Single-Photon Emission by the Plasmon-Induced Transparency Effect in Coupled Plasmonic Resonators." Photonics 8, no. 6 (2021): 188. http://dx.doi.org/10.3390/photonics8060188.
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The plasmon-induced transparency (PIT) effect with unique spectrum transmission characteristics is a significant property of plasmonic structures. A resonant nanocavity with nanoscale dimensions around a single-photon emitter dramatically enhances the emission rate of the emitter. Thus, we propose detuned resonant nanocavities to manipulate the emission rate of the emitter inside, of which either cell consists of a rectangular resonator surrounded by a U-like resonator. An InGaAs quantum dot in a GaAs nanowire placed in the center of the detuned resonant nanocavity was employed as a single-photon emitter. The finite-difference time domain simulation revealed that the distribution of the electromagnetic field can be affected by changing the coupling intensity between the bright and dark states of the PIT. Consequently, the emission rate of the single-photon emitter was dramatically enhanced by more than 2000 times due to the Purcell effect induced by the PIT in the resonant cavity. With the achievement of an ultrafast single-photon emission rate, the proposed single-photon emitter could have diverse applications in quantum information and quantum communications.
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Xu, Junran, Chung Leung, Xin Zhuang, et al. "A Low Frequency Mechanical Transmitter Based on Magnetoelectric Heterostructures Operated at Their Resonance Frequency." Sensors 19, no. 4 (2019): 853. http://dx.doi.org/10.3390/s19040853.
Full textAbstract:
Magneto-elasto-electric (ME) coupling heterostructures, consisting of piezoelectric layers bonded to magnetostrictive ones, provide for a new class of electromagnetic emitter materials on which a portable (area ~ 16 cm2) very low frequency (VLF) transmitter technology could be developed. The proposed ME transmitter functions as follows: (a) a piezoelectric layer is first driven by alternating current AC electric voltage at its electromechanical resonance (EMR) frequency, (b) subsequently, this EMR excites the magnetostrictive layers, giving rise to magnetization change, (c) in turn, the magnetization oscillations result in oscillating magnetic fields. By Maxwell’s equations, a corresponding electric field, is also generated, leading to electromagnetic field propagation. Our hybrid piezoelectric-magnetostrictive transformer can take an input electric voltage that may include modulation-signal over a carrier frequency and transmit via oscillating magnetic field or flux change. The prototype measurements reveal a magnetic dipole like near field, demonstrating its transmission capabilities. Furthermore, the developed prototype showed a 104 times higher efficiency over a small-circular loop of the same area, exhibiting its superiority over the class of traditional small antennas.
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Maslovski, Stanislav I., and Constantin R. Simovski. "Purcell factor and local intensity enhancement in surface-enhanced Raman scattering." Nanophotonics 8, no. 3 (2019): 429–34. http://dx.doi.org/10.1515/nanoph-2018-0190.
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AbstractWe prove that, at any point of any reciprocal structure, the local field intensity enhancement, which is averaged over the incident wave polarizations and the incidence directions, exactly coincides with the radiative part of the Purcell factor, which is averaged over the orientations of the emitter. This result is important for gaining a better understanding of the electromagnetic Raman gain in the surface-enhanced Raman scattering and for the further development of this technique.
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Kumar, Sandeep, and Sunil Kumar. "Ultrafast light-induced THz switching in exchange-biased Fe/Pt spintronic heterostructure." Applied Physics Letters 120, no. 20 (2022): 202403. http://dx.doi.org/10.1063/5.0091934.
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The ultrafast optical control of magnetization in spintronic structures enables one to access to the high-speed information processing, approaching the realm of terahertz (THz). Femtosecond visible/near-infrared laser-driven ferromagnetic/nonmagnetic metallic spintronic heterostructures-based THz emitters combine the aspects from the ultrafast photo-induced dynamics and spin-charge inter-conversion mechanisms through the generation of THz electromagnetic pulses. In this Letter, we demonstrate photoexcitation density-dependent induced exchange-bias tunability and THz switching in an annealed Fe/Pt thin-film heterostructure, which otherwise is a widely used conventional spintronic THz emitter. By combining the exchange-bias effect along with THz emission, the photo-induced THz switching is observed without any applied magnetic field. These results pave the way for an all-optical ultrafast mechanism to exchange-bias tuning in spintronic devices for high-density storage, read/write magnetic memory applications.
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Wu, Bin, Shibo Yuan, Peng Li, Zehuan Jing, Shao Huang, and Yaodong Zhao. "Radar Emitter Signal Recognition Based on One-Dimensional Convolutional Neural Network with Attention Mechanism." Sensors 20, no. 21 (2020): 6350. http://dx.doi.org/10.3390/s20216350.
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As the real electromagnetic environment grows complex and the quantity of radar signals turns massive, traditional methods, which require a large amount of prior knowledge, are time-consuming and ineffective for radar emitter signal recognition. In recent years, convolutional neural network (CNN) has shown its superiority in recognition so that experts have applied it in radar signal recognition. However, in the field of radar emitter signal recognition, the data are usually one-dimensional (1-D), which takes more time and storage space than by using the original two-dimensional CNN model directly. Moreover, the features extracted from convolutional layers are redundant so that the recognition accuracy is low. In order to solve these problems, this paper proposes a novel one-dimensional convolutional neural network with an attention mechanism (CNN-1D-AM) to extract more discriminative features and recognize the radar emitter signals. In this method, features of the given 1-D signal sequences are extracted directly by the 1-D convolutional layers and are weighted in accordance with their importance to recognition by the attention unit. The experiments based on seven different radar emitter signals indicate that the proposed CNN-1D-AM has the advantages of high accuracy and superior performance in radar emitter signal recognition.
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Pilipenko, Vyacheslav, Eugeny Fedorov, Nikolay Mazur, and Stanislav Klimov. "Electromagnetic pollution of near-Earth space by power line emission." Solar-Terrestrial Physics 7, no. 3 (2021): 105–13. http://dx.doi.org/10.12737/stp-73202107.
Full textAbstract:
We present an overview, based on satellite observations at low Earth orbits, on electromagnetic radiation from ground power transmission lines at an industrial frequency 50–60 Hz. Particular attention has been given to Chibis-M and DEMETER satellite observations. The electric 40-cm antenna of the micro-satellite often recorded 50–60 Hz radiation (known as Power Line Emission (PLE)) when it flew over industrialized areas of the planet. The PLE spectral amplitude varied from 1.2 to 18 (μV/m)/Hz0.5, which corresponds to the electric field amplitude E~1 μV/m. We report results of numerical calculations of the electromagnetic response of the atmosphere and ionosphere to a large-scale surface emitter at a frequency of 50 Hz. According to simulation results, PLE with an intensity of ~1 μV/m observed on satellites in the nightside ionosphere at midlatitudes can be excited by an unbalanced current 8–10 A in a power transmission line above the earth's crust with conductivity of 10–3 S/m. At middle and low latitudes with an inclined geomagnetic field, the maximum response in the upper ionosphere to the transmission line radiation should be seen shifted equatorward, although this shift is less than that upon guidance by the geomagnetic field. The maximum amplitude of the electromagnetic response of the ionosphere to the power transmission line emission decreases for an inclined geomagnetic field, but insignificantly. To date, the PLE intensity in near-Earth space has turned out to be higher than the intensity of natural radiation in this range (Schumann resonances and ion whistlers), and continues to grow with the technological development of mankind.
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Gong, Chengxuan, and Gaige Zheng. "Selective Properties of Mid-Infrared Tamm Phonon-Polaritons Emitter with Silicon Carbide-Based Structures." Micromachines 13, no. 6 (2022): 920. http://dx.doi.org/10.3390/mi13060920.
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Electromagnetic (EM) absorbers and emitters have attracted much interest because of their versatile applications. A photonic heterostructure composed of silicon carbide (SiC) layer/germanium (Ge) cavity/distributed Bragg reflector (DBR) has been proposed. Selective emission properties have been investigated through rigorous coupled wave analysis (RCWA) method. The results illustrate that Tamm phonon-polaritons can be excited, and the magnetic field is partially centralized at the junction of Ge cavity and SiC film, aimed to improve the interactions of photon–phonon. The absorptivity/emissivity of the structure can be better optimized by controlling the coupling of surface modes with the incident wave. Near-unity absorption can be achieved through optimizing the SiC grating/Ge cavity/distributed Bragg reflector (DBR) multilayer structure with geometrical parameters of ds = 0.75 μm, dg = 0.7 μm, d1 = 1.25 μm and d2 = 0.75 μm, respectively. Physical mechanism of selective emission characteristics is deliberated. In addition, the simulation results demonstrate that the emitter desensitizes to the incidence angle and polarization state in the mid-infrared (MIR) range. This research ameliorates the function of the selective emitters, which provides more efficient design for SiC-based systems.
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Godarev-Lozovsky, M. G. "THE ONTOLOGICAL TRIANGLE OF THE RELATIONAL PARADIGM." Metaphysics, no. 2 (December 15, 2021): 24–38. http://dx.doi.org/10.22363/2224-7580-2021-2-24-38.
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The philosophical analysis of three main paradigms in the basis of physical knowledge is carried out. It is permissible to conclude that in the case of electromagnetic interaction between the emitter and the absorber: 1) the process of interaction of the photon with the medium in space and time can occur; 2) in the case when the photon “teleports” - there is only a relation outside of space and time. The following classification of fundamental concepts, with which the relational paradigm deals, is revealed. The ideal: space and time, field, information, a set of movements of quantum particles. The material: interactions, environment. Nothing more than countable: time, electromagnetic interactions. Uncountable: space, environment, interactions with the environment, a set of movements of quantum particles. Substantial: environment, interactions, information, a set of movements of quantum particles. Relational: space, time, field - as a means of description.
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Maksuwan, Atirat. "Propagation of Massless Spin-1 Particle between Two Media." Key Engineering Materials 675-676 (January 2016): 687–90. http://dx.doi.org/10.4028/www.scientific.net/kem.675-676.687.
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In general explanation for propagation of electromagnetic wave at a plane between two media of different dielectric properties. The description of this phenomenon be based on the actual physical process of the well know interpretation of the classical rays with the polarization vectors. In this research, we investigate this situation by using the knowledge of the amplitude of emission and absorption of massless spin-1 particle (photon) excitation by the emitter and detector, respectively. By using time evolution process based on vacuum-to-vacuum transition amplitude in quantum (field) theory QED formalism. This process shows that the propagation of photon excitation by the external sources is given with an explanation of the amplitude of propagation between different spacetime points from an emitter to a detector, which exclude with the Feynman propagator. The purpose of this research is developing a formalism based on the actual physical process of photons propagate from an emitter to a detector. It shows the consistency to the actual physical process of interpretation of the polarization vectors in the classical rays.
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Tokman, Mikhail, Maria Erukhimova, Yongrui Wang, Qianfan Chen, and Alexey Belyanin. "Generation and dynamics of entangled fermion–photon–phonon states in nanocavities." Nanophotonics 10, no. 1 (2020): 491–511. http://dx.doi.org/10.1515/nanoph-2020-0353.
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AbstractWe develop the analytic theory describing the formation and evolution of entangled quantum states for a fermionic quantum emitter coupled simultaneously to a quantized electromagnetic field in a nanocavity and quantized phonon or mechanical vibrational modes. The theory is applicable to a broad range of cavity quantum optomechanics problems and emerging research on plasmonic nanocavities coupled to single molecules and other quantum emitters. The optimal conditions for a tripartite entanglement are realized near the parametric resonances in a coupled system. The model includes dissipation and decoherence effects due to coupling of the fermion, photon, and phonon subsystems to their dissipative reservoirs within the stochastic evolution approach, which is derived from the Heisenberg–Langevin formalism. Our theory provides analytic expressions for the time evolution of the quantum state and observables and the emission spectra. The limit of a classical acoustic pumping and the interplay between parametric and standard one-photon resonances are analyzed.
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Kosionis, Spyridon G., Vassilios Yannopapas, Ioannis Thanopulos, and Emmanuel Paspalakis. "Controlling Resonance Fluorescence Spectra and Photon Statistics in a Driven V-Type Quantum Emitter—Metal Nanoparticle Coupled Structure." Photonics 9, no. 9 (2022): 629. http://dx.doi.org/10.3390/photonics9090629.
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We study the resonant fluorescence emission spectrum and the intensity-intensity correlations of the emitted fluorescent field by a V-type quantum emitter (QE) which is located near a metal nanosphere. For the description of the studied phenomena, we use the density matrix equations methodology combined with electromagnetic calculations and obtain results for the profile of the resonant fluorescence spectrum and the second-order correlation functions associated with the fluorescent photons. The decay rates and the coupling term exhibit a strong dependence on the distance that separates the QE from the metal nanoparticle. This distance also influences the resonance fluorescence of the V-type QE. We find that, in the general case, the resonant fluorescence spectrum is composed of five Lorentzian-type peaks, for high interparticle distances, while, when the QE is located very close to the surface of the nanosphere, the central resonance becomes dominant, and a single-peaked spectral profile appears. The two-time correlation functions of the fluorescent photons evolve in an oscillatory manner around unity, for non-zero time delay, with a period that decreases with the increase of the field intensity. In the strong driving field regime, the antibunching to bunching crossing time does not depend on the interparticle distance, contrary to the results found in the weak driving field regime. We also find that, for a weak laser field and under specific conditions, the second-order correlation functions constantly remain in the antibunching region.
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Zlobina, Irina, and Guzel Muldasheva. "Microwave technology for modification of large-scale structures made of cured polymer composite materials." EPJ Web of Conferences 321 (2025): 02004. https://doi.org/10.1051/epjconf/202532102004.
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An analysis of the results of strengthening modification of cured polymer composite materials in a microwave electromagnetic field has been conducted. It has been demonstrated that the essential factor for achieving the desired effect is a combination of energy flux density and exposure time, ensuring the material is heated to a temperature of 60-80°C. The drawbacks of implementing microwave modification in beam-type chambers with sequentially arranged emitters have been noted. It has been proposed to perform strengthening microwave modification of large-sized products made of polymer composite materials by discretely moving (scanning) a horn emitter across the product surface with a delay at each scanning step. Experimental studies of the temperature field distribution on the irradiated surface have been carried out for various scanning schemes. A rational overlap value of the directional pattern areas with maximum energy flux density at each scanning step has been established at 25%, ensuring uniform heating of the product surface with a spread of no more than ±5°C, which consequently allows for the realization of a uniform distribution of physical and mechanical properties of the modified structure.
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Hoijer, Magnus. "Polarization of the Electromagnetic Field Radiated From a Random Emitter and Its Coupling to a General Antenna." IEEE Transactions on Electromagnetic Compatibility 55, no. 6 (2013): 1335–37. http://dx.doi.org/10.1109/temc.2013.2265321.
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Mu, Haiwei, Yu Wang, Jingwei Lv, et al. "Electric field enhancement by a hybrid dielectric-metal nanoantenna with a toroidal dipole contribution." Applied Optics 61, no. 24 (2022): 7125. http://dx.doi.org/10.1364/ao.466124.
Full textAbstract:
Plasmonic nanocavities enable extreme light–matter interactions by pushing light down to the nanoscale. The numerical simulation is carried out systematically on the slotted Φ -shaped Si disk system with the super-dipole mode based on the analysis of the scattering strength of electric and toroidal dipoles. New blocks are introduced to the zero-field strength region of a slotted Si disk system as a function of the field enhancement factors. The far-field scattering characteristics and near-field electromagnetic field distributions are investigated by a multipole decomposition analysis to elucidate the intrinsic causes of the field enhancement. In the hybrid metal-dielectric nanoantenna, the Φ -shaped Si structure is prepared by superimposing Au nanoantennas for further field enhancement. In addition, the effects of the placement of an electric dipole emitter on the Purcell factor are derived. The geometric volume of the system is increased, and the electric field strength is improved, leading to an electric field increase of ∼ 30 . Coupling between the super-dipole mode of the dielectric nanostructure and plasmonic modes of the metallic nanoantenna produces an enhancement as large as 16 times. Our results reveal a greatly enhanced super-dipole mode by electromagnetic coupling in composite structures, which will play a significant role in enhanced nonlinear photonics, near-field enhancement spectroscopy, and strong photon–exciton coupling.
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Huang, Jing, Xiao Li, Bin Wu, Xinyu Wu, and Peng Li. "Few-Shot Radar Emitter Signal Recognition Based on Attention-Balanced Prototypical Network." Remote Sensing 14, no. 23 (2022): 6101. http://dx.doi.org/10.3390/rs14236101.
Full textAbstract:
In recent years, radar emitter signal identification has been greatly developed via the utilization of deep learning and has achieved significant improvements in identification accuracy. However, with the continuous emergence of complex regime radars and the increasing complexity of the electromagnetic environment, some new kinds of radar emitter signals collected are not in sufficient quantities to satisfy the demand of deep learning. As a result, in this paper, we adopted the prototypical network (PN) belonging to metric-based meta-learning to realize few-shot radar emitter signal recognition with the aim of meeting the needs of modern electronic warfare. Additionally, considering the problems that may arise in the field of few-shot radar emitter signal recognition, such as discriminative location bias caused by a small number of base classes or the large difference between base classes and novel classes, we proposed an attention-balanced strategy to improve meta-learning. Specifically, each channel in the feature map is forced to make the same contribution in the distinguishment of different classes. In addition, for PN, taking into account that the feature vectors of each support sample in the class are different, we set a network to exploit the relation between each support sample in the same classes, and weighted each feature vector of the support samples according to the relation. Large quantities of experiments indicate that our algorithm possesses more advantages than other algorithms.
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Xue, Jian, Lan Tang, Xinggan Zhang, Lin Jin, Ming Hao, and Youlin Gui. "Feature Evaluation and Comparison in Radar Emitter Recognition Based on SAHP." Electronics 10, no. 11 (2021): 1274. http://dx.doi.org/10.3390/electronics10111274.
Full textAbstract:
In the field of radar emitter recognition, with the wide application of modern radar, the traditional recognition method based on typical five feature parameters cannot achieve satisfactory recognition results in a complex electromagnetic environment. Currently, many new feature extraction methods are presented, but few approaches have been applied for feature evaluation or performance comparison. To deal with this problem, a feature evaluation and selection method was proposed based on set pair analysis (SPA) theory and analytic hierarchy process (AHP). The main idea of this method is to use SPA theory to solve problems regarding the construction of the decision matrix based on AHP, as it relies heavily on expert’s subjective experience. The aim was to improve the objectivity of the evaluation. To check the effectiveness of the proposed method, six feature parameters were selected for a comprehensive performance evaluation. Then, the convolutional neural network (CNN) was introduced to validate the recognition capability based on the evaluation results. Simulation results demonstrated that the proposed method could achieve the feature analysis and evaluation more reasonably and objectively.
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Lyagushyn, S., and A. Sokolovsky. "Superradiance and solids: Reduced description method." Low Temperature Physics 50, no. 1 (2024): 103–9. http://dx.doi.org/10.1063/10.0023899.
Full textAbstract:
Spontaneous ordering in a system of excited emitters with a powerful short radiation pulse predicted by Dicke attracted the great attention of scientists for decades as a bright example of the nontrivial behavior of a nonequilibrium system. The Bogolyubov reduced description method has some advantages and provides new possibilities in the theoretical investigation of the Dicke process. The paper presents the authors’ results of modeling such processes concerning both optical ones in the presence of crystal lattice influence and acoustic superradiance, which is possible in solids. The right choice of reduced description parameters allows the account of atom motions (phonons), cavity influence, and excitations in the emitter system (excitons) in the electromagnetic radiation process. The mathematical analogy between the Dicke system and a spin system in a magnetic field opens the way to applying the reduced description technique to acoustic phenomena previously investigated with the boson variable elimination method. Such a new approach to superradiance in crystals with paramagnetic impurities and with competing mechanisms of relaxation (Wagner model) is outlined. Acoustic superradiance is discussed in connection with the problem of structural phase transitions.
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Pilipenko, Vyacheslav, Eugeny Fedorov, Nikolay Mazur, and Stanislav Klimov. "Electromagnetic pollution of near-Earth space by power line emission." Solnechno-Zemnaya Fizika 7, no. 3 (2021): 111–19. http://dx.doi.org/10.12737/szf-73202107.
Full textAbstract:
We present an overview, based on satellite observations at low Earth orbits, on electromagnetic radiation from ground power transmission lines at an industrial frequency 50–60 Hz. Particular attention has been given to Chibis-M and DEMETER satellite observations. The electric 40-cm antenna of the micro-satellite often recorded 50–60 Hz radiation (known as Power Line Emission (PLE)) when it flew over industrialized areas of the planet. The PLE spectral amplitude varied from 1.2 to 18 (μV/m)/Hz0.5, which corresponds to the electric field amplitude E~1 μV/m. We report results of numerical calculations of the electromagnetic response of the atmosphere and ionosphere to a large-scale surface emitter at a frequency of 50 Hz. According to simulation results, PLE with an intensity of ~1 μV/m observed on satellites in the nightside ionosphere at midlatitudes can be excited by an unbalanced current 8–10 A in a power transmission line above the earth's crust with conductivity of 10–3 S/m. At middle and low latitudes with an inclined geomagnetic field, the maximum response in the upper ionosphere to the transmission line radiation should be seen shifted equatorward, although this shift is less than that upon guidance by the geomagnetic field. The maximum amplitude of the electromagnetic response of the ionosphere to the power transmission line emission decreases for an inclined geomagnetic field, but insignificantly. To date, the PLE intensity in near-Earth space has turned out to be higher than the intensity of natural radiation in this range (Schumann resonances and ion whistlers), and continues to grow with the technological development of mankind.
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Reznikov, A. E., A. I. Sukhorukov, D. E. Edemskii, et al. "Investigations of the lower ionosphere over Antarctica via ELF-VLF radiowaves." Antarctic Science 5, no. 1 (1993): 107–13. http://dx.doi.org/10.1017/s0954102093000148.
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The paper discusses ELF-VLF investigations of the low Antarctic ionosphere. Two new methods of lower ionospheric diagnostics are based on an investigation of the VLF electromagnetic field structure in the Earth-ionosphere cavity. One method deals with the analysis of local transverse cavity resonances in the near field of an emitter (a horizontal antenna) with a frequency (~1.5-8 kHz) in the range of the first few resonances. The other method, based on tweek investigations, is applicable under night conditions and enables the characteristics of the low ionosphere to be determined over a signal propagation path. The use of the ELF-VLF transmitter at Siple Station provides a unique opportunity to implement these methods, as does the ELF multipoint recording in the Schumann resonance band of atmospherics excited by powerful lightning discharges.
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Belavskaya, Svetlana V., Dmitriy N. Kuleshov, Liliya I. Lisitsyna, et al. "Analysis of the healing time of in vivo biological tissue incisions made with surgical scissors and an electromagnetic emitter." Analysis and data processing systems, no. 1 (March 27, 2025): 141–54. https://doi.org/10.17212/2782-2001-2025-1-141-154.
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In modern surgery, the search for and development of methods that ensure effective and safe dissection of biological tissues are priority areas of research. Minimising damage to surrounding tissues, reducing the risk of complications and accelerating the healing process are the key factors determining the effectiveness of surgical intervention. Traditionally, surgical scissors or scalpels have been used for tissue dissection, however, they carry the risk of bleeding and tissue trauma, which can delay the healing process and promote inflammatory reactions. An alternative method showing promising results is the use of high-frequency electromagnetic radiation for tissue dissection and coagulation. This paper presents the results of an in vivo experimental study devoted to a comparative analysis of the dynamics of healing biological tissue incisions, in particular, skin incisions, in laboratory animals performed using two different methods: traditional surgical scissors and a high-frequency electromagnetic radiator operating at a frequency of 27.12 MHz. The aim of this study is to objectively evaluate the effect of different methods of tissue dissection on the healing process and to identify the features of regeneration when electromagnetic radiation is used. During the experimental study, one of the parameters characterising the healing process, such as Wound Closure Time was evaluated: The duration required for a complete closure of the skin defect was measured. The obtained data allow a comparative assessment of the dynamics of healing incisions made with a high-frequency electromagnetic radiator as an alternative device for dissecting biological tissues during surgical interventions compared to incisions made with a traditional instrument – surgical scissors. The results of the study provide important information on the influence of different dissection methods on healing dynamics. An important aspect is the study of the inflammation phase as an initial and key stage in wound healing. The study aims at determining the effect of coagulation on the intensity and duration of the inflammatory response. The analysis of the obtained results has shown that the use of high-frequency electromagnetic radiator for tissue dissection has a significant effect on the healing process. In particular, it is demonstrated that the electromagnetic coagulation method leads to a reduction in the intensity and duration of the inflammatory phase, compared to the use of surgical scissors. This effect is probably due to the fact that high-frequency radiation simultaneously provides tissue dissection and coagulation preventing bleeding and reducing the traumatic nature of the incision. The results of the study indicate the potential advantages of high-frequency electromagnetic radiation as an alternative method of tissue dissection in surgical practice. The identified features of wound healing performed by different methods can be used to optimise surgical protocols and reduce the risk of postoperative complications. The data obtained in the course of work are of practical importance for the development of new methods and technologies aimed at improving the quality of surgical interventions and accelerating the recovery of patients. In the future, it is planned to deepen the research in the field of the influence of various parameters of electromagnetic radiation on the healing process, as well as to conduct additional studies of key parameters characterising the healing process, such as: the intensity of the inflammatory response, morphological features of the formed scar tissue, including its density, structure and elasticity, and the process of formation of new epithelial cover over the wound surface.
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Salomon, Adi, and Martin Oheim. "Near-interface sensing, imaging and nanometrology using smart surfaces." EPJ Web of Conferences 309 (2024): 02003. http://dx.doi.org/10.1051/epjconf/202430902003.
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We present two distinct types of ‘smart’ surfaces designed for facilitating the quantitative exploration of dynamic processes occurring at sub-wavelength distances from interfaces, using far-field optical techniques. Based on evanescent waves in excitation and/or emission, we achieve an axial localization precision of about 10 nm. The first type of substrate incorporates nanocavities in a thin metallic film, enhancing and confining the electromagnetic field to a tiny volume. The second sample consists of a thin fluorescent film sandwiched between transparent spacer and capping layers deposited on a glass coverslip. The emission pattern from this film codes detailed information about the local fluorophore environment, namely, the refractive index, defects, reciprocal lattice, and the axial distance of the molecular emitter from the surface. An application to axial metrology in total internal reflection fluorescence and axial super-localisation microscopes is presented.
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Zenchenko, N. V., D. V. Lavrukhin, I. A. Glinskiy, and D. S. Ponomarev. "Improving the efficiency of an optical-to-terahertz converter using sapphire fibers." Russian Technological Journal 11, no. 2 (2023): 50–57. http://dx.doi.org/10.32362/2500-316x-2023-11-2-50-57.
Full textAbstract:
Objectives. The study aims to improve the efficiency of a large-area photoconductive terahertz (THz) emitter based on an optical-to-terahertz converter (OTC) having a radiating area of 0.3 × 0.3 mm2 for generating high-power THz radiation by using an array of close-packed profiled sapphire fibers having a diameter in the range of 100–300 μm as focusing optics.Methods. As a photoconductive substrate, we used a semi-infinite LT-GaAs layer (low-temperature grown GaAs; GaAs layer grown by molecular beam epitaxy at a low growth temperature). Additional Si3N4 and Al2O3 layers are intended for reducing leakage currents in the OTC and reducing the reflection of the laser pump pulse from the air/semiconductor interface (Fresnel losses), respectively, at a gap width of 10 μm. For forming the antenna electrodes and feed strips, the Ti/Au metal system was used. The simulation was carried out by the finite element method in the COMSOL Multiphysics environment.Results. The use of a profiled sapphire fiber whose diameter has been optimized with respect to the gap parameters to significantly increase the concentration of charge carriers in the immediate vicinity of the electrodes of an OTC is demonstrated. The integrated efficiency of a large-area photoconductive THz emitter was determined taking into account the microstrip topology of the array with a characteristic size of feed strips proportional to the gap width in the OTC and with the upper (masking) metal layer. The maximum localization of the electromagnetic field in close proximity to the edges of electrodes at the “fiber–semiconductor” interface is achieved with a profiled sapphire fiber diameter of 220 μm.Conclusions. By optimizing the diameter of the sapphire fiber, the possibility of improving the localization of incident electromagnetic waves in close proximity to the edges of the OTC electrodes by ~40 times compared to the case without fiber, as well as increasing the overall efficiency of a large-area emitter by up to ~7–10 times, was demonstrated.
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Domenikou, Natalia, Ioannis Thanopulos, Vassilios Yannopapas, and Emmanuel Paspalakis. "Stimulated Raman Adiabatic Passage in a Quantum Emitter Near to a Gold Nanoparticle." Materials Proceedings 4, no. 1 (2020): 7. http://dx.doi.org/10.3390/iocn2020-07867.
Full textAbstract:
In the last three decades, stimulated Raman adiabatic passage (STIRAP) has been proven a robust and high-efficient technique for population transfer in a three-level quantum system and beyond that. As coupled quantum-plasmonic nanostructures are widely used in recent nanophotonics for the superior properties that the coupled structures have over their constituents, a series of studies have analyzed the influence of a spherical metallic nanoparticle, which is a basic plasmonic nanosystem, on coherent population transfer methods in nearby quantum systems. For several recent proposals, it is important to understand the behavior of STIRAP near metallic nanoparticles. Therefore, in this work we present numerical results on the influence of a spherical metallic nanoparticle to the population transfer in a Λ-type quantum system under conditions of STIRAP. For the study of the system’s dynamics, we use the density matrix approach for the quantum system, where the parameters for the electric field amplitudes and the spontaneous decay rates have been calculated using ab initio electromagnetic calculations for the plasmonic nanoparticle. We then present results for the evolution of the populations of the different levels of the quantum system as a function of different parameters, in the presence and the absence of the plasmonic nanoparticle. We find that the presence of the plasmonic nanoparticle and the polarization of the pump and Stokes fields with respect to the surface of the nanoparticle, affect the efficiency of the population transfer inside the three-level quantum system. For the right combination of the values of the free space spontaneous decay rates and the fields intensities, high efficiency population transfer is obtained in the quantum system near a plasmonic nanoparticle using the STIRAP process.