Additional Electromagnetic Fields Research Articles

Slowly rotating charges from Weyl double copy for Kerr black hole with Chern–Simons correction

The Weyl double copy builds the relation between gauge theory and gravity theory, in particular the correspondence between gauge solutions and gravity solutions. In this paper, we obtain the slowly rotating charge solutions from the Weyl double copy for the Kerr black hole with small Chern–Simons correction. Based on the Weyl double copy relation, for the Petrov type D solution in Chern–Simons modified gravity, we find the additional correction to the electromagnetic field strength tensor of the rotating charge. For the Petrov type I solution, we find that the additional electromagnetic field strength tensors have external sources, while the total sources vanish at the leading order.

Study of characteristics elementary atomic processes in the neon-like multicharged ions plasma within an energy approach

We present the theoretical foundations of an advanced relativistic approach to computing the main energy, spectral characteristics of radiative-collisional processes in the plasma (in particular, the Debye plasma) of atomic as the example, neon-like) ions with simultaneous, quantitatively consistent consideration of the complex relativistic, interelectron exchange-correlation and plasma environment effects. The approach is based on the combination of a relativistic energy approach (S-matrix Gell-Mann and Low formalism), the relativistic gauge-invariant many-body perturbation theory with optimized Dirac-Fock-Sturm and Debye-Hückel approximations with accounting for the plasma environment effects with possible generalization on the presence of an additional external electromagnetic field. The fundamental point of our approach is the selection of the optimized Dirac-Fock-Sturm zeroth approximation and application of the consistent procedure for constructing a one-quasiparticle representation (basis’s of relativistic wave functions) in compliance with the principle of gauge invariance, in particular, by minimizing a gauge-noninvariant contributions to the radiative widths of the atomic (ionic) levels due to the complex exchange-correlation effects. The electron-ion collision strength and the dioelect5ron capture rate etc are determined within the presented theory.

Hydrophilic-hydrophobic polymer strip with intrinsic signal and chemical-electromagnetic synergistic enhancement for non-metallic SERS-based identification of SARS-CoV-2 antigen

The formulation of substrates with reliable quantitative detection and robust molecular anchoring is crucial for surface-enhanced Raman scattering (SERS) technique. In this context, an appealing hydrophilic-hydrophobic polymer strip with Raman internal standard (IS) was generated by in-situ growing hydrophilic non-metallic black phosphorus/metal-organic frameworks (BP/ZIF-67) onto special regions of hydrophobic polydimethylsiloxane (PDMS) matrix, which dramatically promoted the concentration of target molecules. Furthermore, a specific detection of coronavirus disease 2019 (SARS-CoV-2) N-protein with a limit of 6.4 × 10−6 mg/mL was facilitated, benefiting from the selective capture rendered by the mesoporous surface of ZIF-67 and the ultra-high enhancement effect arose from BP/ZIF-67 hybrid structure-triggered charge transfer resonance process. Moreover, the extent of quantification in the SERS assay was significantly remedied due to the IS strategy. Especially, the slight local surface plasmon resonance (LSPR) capability of BP could readily provoke additional electromagnetic field to complement its powerful chemical enhancement, which was significantly superior to other non-metallic substrates. Such an upgraded platform may deliver another prospering technology for dependable virus monitoring.

Constraining an Einstein-Maxwell-dilaton-axion black hole at the Galactic Center with the orbit of the S2 star

We derive new constraints on the dilaton parameter appearing in the spherically-symmetric black hole solution of Einstein-Maxwell-dilaton-axion gravity, by studying the geodesic motion of the S2 star in the Galactic Center. Einstein-Maxwell-dilaton-axion black holes represent a compelling alternative to the standard black hole paradigm in General Relativity. This theory emerges from the low energy effective action of the heterotic string theory and has been proven to predict peculiar observational features from the direct imaging of black hole shadows. At a fundamental level, Einstein-Maxwell-dilaton-axion includes additional electromagnetic, dilatonic and axionic fields coupled to the space-time metric. When considering charged non-rotating black hole solutions, the additional fields endow the metric with one extra parameter b, called dilaton parameter, that is theoretically bound to 0 < b < M. Using publicly available astrometric data for S2 we derive an upper bound on b ≲ 12M at 95% confidence level and we demonstrate that only including the measurement of the relativistic orbital precession for S2 is sufficient to reduce this bound to b ≲ 1.4M at the same confidence level. Additionally, using a mock data mimicking future observations of S2 with the GRAVITY interferometer, we show that improved astrometric precision can help further narrow down the allowed dilaton parameter range to b ≲ 0.033M after monitoring the S2 orbit for one and a half period.

Dynamic and thermodynamic stability of charged perfect fluid stars

We perform a thorough analysis of the dynamic and thermodynamic stability for the charged perfect fluid star by applying the Wald formalism to the Lagrangian formulation of Einstein–Maxwell-charged fluid system. As a result, we find that neither the presence of the additional electromagnetic field nor the Lorentz force experienced by the charged fluid makes any obstruction to the key steps towards the previous results obtained for the neutral perfect fluid star. Therefore, the criterion for the dynamic stability of our charged star in dynamic equilibrium within the symplectic complement of the trivial perturbations with the Arnowitt-Deser-Misner (ADM) 3-momentum unchanged is given by the non-negativity of the canonical energy associated with the timelike Killing field, where it is further shown for both non-axisymmetric and axisymmetric perturbations that the dynamic stability against these restricted perturbations also implies the dynamic stability against more generic perturbations. On the other hand, the necessary condition for the thermodynamic stability of our charged star in thermodynamic equilibrium is given by the positivity of the canonical energy of all the linear on-shell perturbations with the ADM angular momentum unchanged in the comoving frame, which is equivalent to the positivity of the canonical energy associated with the timelike Killing field when restricted onto the axisymmetric perturbations. As a by-product, we further establish the equivalence of the dynamic and thermodynamic stability with respect to the spherically symmetric perturbations of the static, spherically symmetric isentropic charged star.

Improvement of the welded joints properties of P460NH steel with AC-assisted GTAW arc

Aiming at the problems of small grain size and difficult welding of P460 NH steel, an efficient and high-quality welding method of AC assisted arc welding is proposed. In this AC-assisted arc welding process, the alternating current was added to the filling wire to form an additional electromagnetic field. The alternating electromagnetic force generated by the interaction of the main arc and other electromagnetic fields can stir the molten pool during the welding process. The feasibility of improving the grain size and mechanical properties of microstructures with AC power in 0-30A was confirmed. The experiment proved that the arc oscillation caused by the alternating electromagnetic force can alleviate the root stay of the traditional GTAW process. When the AC strength doesn't exceed 20A, the average grain size decreases while the content of acicular ferrite and granular bainite increases. The average grain size is 3.258 μm refined to 2.960 μm. Moreover, the tensile strength and hardness of welded joints first increase with the addition of current and then decrease with the rise of current to 30A. Finally, the mechanism of AC on microstructure and solidification of molten pool was discussed.

Electromagnetic field excitation during the scattering of an acoustic wave on an inhomogeneity in a poroelastic medium

Elastic wave propagation in porous media containing a movable fluid is frequently accompanied by electromagnetic field generation. Such field can be produced, for instance, by piezoelectric effect or have electrokinetic origin. In the present work, we consider the case of electrolyte-filled pores; thus, the generated electromagnetic field is associated with the electrokinetic effects. In this case, the magnitude of the electric current generated by the elastic wave is proportional to the magnitude of the relative displacement in the fluid and the solid phases. The presence of inhomogeneities in a porous medium can result in appearance of additional fluid flow with respect to the solid phase; thus, an additional electric field is generated. In our work, the magnitude of the electromagnetic field generated during the scattering of an elastic wave on a spherical porous inclusion in a porous matrix is calculated. The inclusion can differ from the matrix by the properties of the fluid in the pores or the properties of the elastic skeleton, such as porosity or permeability. The solution of the dynamic equations of electrokinetics is obtained by using the hypothesis that the inclusion size is much larger than the characteristic size of the pores. We have obtained the dependencies of the amplitude of the generated electromagnetic field on the inclusion parameters and the incident wave frequency. It was shown that the analysis of the additional electromagnetic field generated during the scattering of the elastic wave can provide some useful information about the structure of porous media.

The Solar Wind at (16) Psyche: Predictions for a Metal World

Abstract NASA’s Psyche spacecraft will carry a magnetometer to main-belt asteroid (16) Psyche to search for remanent magnetic fields, and to attempt electromagnetic sounding of the interior. However, the Psyche spacecraft does not carry an instrument to measure solar wind plasmas. We thus combine data from five missions that have measured the solar wind at the orbit of asteroid (16) Psyche. We characterize these upstream conditions for future modeling and reference. We consider the implications of these ambient conditions for the interaction between (16) Psyche and the solar wind, outlining four possible resulting magnetospheres. Any magnetosphere would be dominated by ion-scale (Hall) physics and exotic electron-scale physics, requiring sophisticated physical modeling to describe. Under these different regimes, plasma generates additional electromagnetic fields, resulting in complex magnetism which may complicate the magnetic environment near asteroid (16) Psyche. Future missions to asteroids would benefit from combined magnetic field and plasma measurements.

Comparing induced polarization effect on semi-airborne and airborne transient electromagnetic data: A numerical study

In a transient electromagnetic (TEM) survey, when a chargeable body presents, its induced polarization (IP) will generate an additional electromagnetic field that further superposes on the TEM data. If the added fields are not considered properly when designing a TEM survey or inverting the TEM datasets, erroneous results may be obtained. Thus, we compare the IP effects on the airborne and semi-airborne TEM methods in this study. One big difference between the two methods is that the semi-airborne method mainly uses the ground-based galvanic source and the airborne method utilizes the air-based inductive source. To fully illustrate this difference, we calculated the IP-TEM coupled responses at a time range of 10−6 s to 10 s. Despite the commonly known reversal of signs in the transient, we found that in some cases of airborne TEM response, the sign will reverse twice. The relative errors caused by the IP effect are further demonstrated. A minimum peak at the early time that is closely related to the IP parameters is revealed, indicating that the IP fields will drop rapidly at the early time and then decay slowly. Finally, a misfit space analysis is performed, showing that both methods can well resolve the resistivity and the IP parameters of a conductive target, while it is difficult to recover the IP parameters of a resistivity target.

Rotating Kerr-Newman space-times in metric-affine gravity

We present new rotating vacuum configurations endowed with both dynamical torsion and nonmetricity fields in the framework of Metric-Affine gauge theory of gravity. For this task, we consider scalar-flat Weyl-Cartan geometries and obtain an axisymmetric Kerr-Newman solution in the decoupling limit between the orbital and the spin angular momentum. The corresponding Kerr-Newman-de Sitter solution is also compatible with a cosmological constant and additional electromagnetic fields.

Pengaruh medan elektromagnetik pada prestasi mesin motor bakar empat langkah dengan bahan bakar gas

The high level of fuel oil consumption in Indonesia caused by increases number of vehicles. Fuel oil consumption has switched into gas fuel as one of the secure alternative fuels and obtained more little gas emissions if compared with fuel oil. LPG (Liquified Petroleum Gas) is one of the alternative fuel was environmentally friendly. This research is purposed for compared performance of four-step engine with premium fuel and LPG fuel with a variety of additional electromagnetic field 600, 800, and 1000 total of copper wire windings. Using LPG fuel can increase torque generated by engine, but the result of engine power to be lower. Based on research data 800 copper wire windings can increase the number of torque and generated power compared to LPG fuel standard. LPG fuel can save fuel consumption compared to premium fuel. The most optimum decrease in fuel consumption is generated by using 1000 copper wire windings. Using LPG fuel can also reduce CO, CO2, and HC emissions levels. The best CO, CO2, and HC emissions levels are obtained from 1000 copper wire windings.Keywords: torque, power, fuel consumption, emissions, and LPG.

Dynamically assisted nuclear fusion

We consider the prototypical deuterium-tritium fusion reaction. At intermediate initial kinetic energies (in the keV regime), a major bottle-neck of this reaction is the Coulomb barrier between the nuclei, which is overcome by tunneling. Here, we study whether the tunneling probability can be enhanced by an additional electromagnetic field, such as an x-ray free electron laser (XFEL). We find that this dynamical assistance should be feasible with present-day or near future technology.

Assessment of the impact of forest plantations on the intensity of commercial frequency electromagnetic fields

Introduction. Influence of forest plantations on intensity of electromagnetic fields (EMF) of commercial frequency (50 Hz), generated by high voltage power transmission line (PTL), is considered. Materials and methods. The study was conducted near the village of Boltino in the Moscow Region. The EMF measurements were made on two profiles perpendicular to the 500 kV PTL (power transmission line) axis, one of which passes through the forest area, the other one does not cross it. Measurements of commercial frequency electromagnetic fields (CFEMF) were carried out using a measurement device and antennas, designed to measure the intensities of magnetic and electrical fields. Results. The comparative analysis of the character of change of electric and magnetic components of EMF with distance from the PTL axis allowed to establish the effect of EMF intensity decrease starting from the forest area boundary. Diagrams show that EMF reduction effect is more pronounced for the electrical component. Conclusions. The revealed effect to a certain extent shows the analogy of the forest area with the Faraday cage. However, such an analogy is not complete due to the fact that the forest area is not a perfectly conductive body, but has only a low conductivity. Additional EMF reduction occurs as a result of partial EMF energy absorption by the forest area

ПЕРСПЕКТИВИ ВИКОРИСТАННЯ ГІДРОЕНЕРГЕТИЧНОГО ПОТЕНЦІАЛУ НА РІЧКАХ БАСЕЙНУ ДНІПРА (НА ПРИКЛАДІ р. РОСЬ)

A new scientific and technological approach concerning the high level of ecological usage of hydropower potential of rivers in the Dnipro river basin is presented. The constructive and layout solutions for the declared small high-ecological hydroelectric power plants are presented. Examples of hydraulic calculation of pressure derivation are given and the power of a hydroelectric power plant is determined taking into account the effect of an additional electromagnetic field on its individual working bodies. The Ros is taken as the pilot river, which shows the locations of universal small high-ecological hydroelectric power stations and their main operating characteristics. In addition, recommendations are made regarding the rational allocation of hydroelectric power plants, taking into account the type of channel. The scientific novelty of the new technological approach is the use of an additional local electromagnetic field at the end of the pressure pipeline at a section length of at least 10 m, on the nozzle and on the turbine. The presence of an electromagnetic field around the turbine and generator enables the stations to operate at significant speeds (from 600 to 16 thousand revolutions per minute). In addition, in the background of the electromagnetic field, due to the absence of friction in the bearings, the life of turbines and generators increases. The universality of new hydroelectric power plants is explained by the fact that such stations can be used on any water facility (mountain or plain river, lake, reservoir or near the reservoir). The technical and economic efficiency of high-ecological hydroelectric power plants is assessed by the high level of environmental safety of the water object, the cost-effectiveness of construction and the achieved level of safety during flood passage, which is achieved by minimal interference and water use of the water object. In addition, the work of the station is effective at the minimum volume of water drain on any part of the river, almost without violating the hydroecological parameters of the water object. Comparative analysis of the estimated cost of a small hydroelectric power station near the village is presented.

Thermal transport of magnetohydrodynamic electroosmotic flow in circular cylindrical microchannels

Thermal transport phenomena of magnetohydrodynamic electroosmotic flow are investigated through a circular cylindrical microchannel. The fluid flow can be actuated by the interactions of imposed pressure-gradient, electroosmosis and additional electromagnetic field. Under the appropriate assumptions, the distributions of the non-dimensional flow velocity can be obtained. Based upon the achieved velocity field, heat transfer characteristics, explained by the non-dimensional temperature and Nusselt number, are discussed graphically by taking into account the effects of viscous dissipation and Joule heating under the constant wall heat flux circumstance. Concisely, the results show, in the absence of lateral electric field, the flow velocity decreases with the increasing magnitudes of Hartmann number resulting in the decrease of non-dimensional temperature, which ultimately culminates in increasing the Nusselt number. However, the profiles of non-dimensional flow velocity, non-dimensional temperature and Nusselt number are demarcated into two regions based on the value of critical Hartmann number and exhibit an adverse trend among different regions due to the existence of lateral electric field. The present endeavor can be utilized to design the exquisite and efficient electromagnetic devices, especially within a specific regime of thermal transport characteristics.

New torsion black hole solutions in Poincaré gauge theory

We derive a new exact static and spherically symmetric vacuum solution in the framework of the Poincaré gauge field theory with dynamical massless torsion. This theory is built in such a form that allows to recover General Relativity when the first Bianchi identity of the model is fulfilled by the total curvature. The solution shows a Reissner-Nordström type geometry with a Coulomb-like curvature provided by the torsion field. It is also shown the existence of a generalized Reissner-Nordström-de Sitter solution when additional electromagnetic fields and/or a cosmological constant are coupled to gravity.

Additional external electromagnetic fields for laser microprocessing of metals.

Ultra-short pulsed laser processing is a potent tool for microstructuring of a lot of materials. At certain laser parameters, particular periodical and/or quasi-periodical µm-size surface structures evolve apparently during processing. With extended plasmonics theory, it is possible to predict the structure formation, and a systematic technology can be derived to alter the surface for laser processing. In this work, we have demonstrated the modification of the laser processing with applying tailored dynamic surface electro-magnetic fields. Possible improvement in applications is seen in the fields of process efficiency of laser ablation and a superior control of the surface topography.

Real-space mapping of tailored sheet and edge plasmons in graphene nanoresonators

Researchers demonstrate graphene plasmon edge modes at infrared wavelengths. Such modes may offer additional electromagnetic field confinement compared with conventional sheet modes. Plasmons in graphene nanoresonators have many potential applications in photonics and optoelectronics, including room-temperature infrared and terahertz photodetectors, sensors, reflect arrays or modulators1,2,3,4,5,6,7. The development of efficient devices will critically depend on precise knowledge and control of the plasmonic modes. Here, we use near-field microscopy8,9,10,11 between λ0 = 10–12 μm to excite and image plasmons in tailored disk and rectangular graphene nanoresonators, and observe a rich variety of coexisting Fabry–Perot modes. Disentangling them by a theoretical analysis allows the identification of sheet and edge plasmons, the latter exhibiting mode volumes as small as 10−8λ03. By measuring the dispersion of the edge plasmons we corroborate their superior confinement compared with sheet plasmons, which among others could be applied for efficient 1D coupling of quantum emitters12. Our understanding of graphene plasmon images is a key to unprecedented in-depth analysis and verification of plasmonic functionalities in future flatland technologies.

Fabrication of highly active and cost effective SERS plasmonic substrates by electrophoretic deposition of gold nanoparticles on a DVD template

In this work we present a simple, rapid and cost effective method to fabricate highly active SERS substrates. This method consists in an electrophoretic deposition of gold nanoparticles on a metallic nanostructured template of a commercial digital versatile disk (DVD). The negatively charged gold nanoparticles self-assemble on the positively charged DVD metallic film connected to a positive terminal of a battery, due to the influence of the electric field. When gold nanoparticles self-assembled on DVD metallic film, a 10-fold additional enhancement of Raman signal was observed when compared with the case of GNPs self-assembled on a polycarbonate DVD substrate only. Finite-difference time-domain simulations demonstrated that the additional electromagnetic field arising in the hot-spots created between gold nanoparticles and DVD metallic film induces an additional enhancement of the Raman signal. SERS efficiency of the fabricated plasmonic substrate was successfully demonstrated through detection of para-aminothiophenol molecule with three different excitation laser lines (532, 633 and 785nm). The enhancement factor was calculated to be 106 and indicates that plasmonic substrates fabricated through this method could be a promising platform for future SERS based sensors.

Generalized Active EMF Cancel Methods for Wireless Electric Vehicles

In the inductive power transfer systems (IPTSs) of wireless electric vehicles (WEV), the electromagnetic field (EMF) should be lowered for the safety of pedestrians. In general, the EMF should be canceled for every space, time, and load condition of interest. Three generalized design methods for cancelling the EMF of WEV are proposed in this paper. By adding active EMF cancel coils to each primary main coil and secondary main coil, respectively, the EMF generated from each main coil can be independently cancelled by their corresponding cancel coils. Moreover, the EMF can be successfully mitigated if a dominant EMF source only is cancelled with 3-dB margin, which can be applied to any resonant type wireless power transfer systems. Furthermore, no significant power drop may occur if the cancel coils are placed aside from magnetic coupling path. Design examples are shown for U-type and W-type IPTS as well as a wireless stationary EV charger. Experimental verifications are shown for a recently developed I-type IPTS, which has a narrow rail width structure with alternating magnetic polarity along with a roadway. The proposed design methods have been demonstrated, without the loss of generality, to only the secondary coil where relatively large EMF is generated due to high ampere turns. An optimum spacing for cancel coils from main coils and an optimum number of turns are determined. Through experiments, additional EMF mitigation techniques such as the magnetic mirror method, separating pick-up rectifiers, and passive Al plate are provided. Thus, the EMF at 1 m distance from the center of a pick-up becomes under 44 mG even for the maximum power of 12 kW.