Electromagnetic Waveforms Research Articles

A ray of black on cells: A short review on radiation biology

Atom is the fundamental unit of elements. The nature of radiation is the transmission of energy through space & matter. The interaction between radiation & matter occurs at 10-13seconds after exposure & may persists for seconds, hours, decades & possibly even generations. X-Ray are forms of electromagnetic waves, which are useful in various imaging modalities for diagnosis & treatment planning of diseases. This review “ A ray of black on cells: a short review on radiation biology” intends to focus on effects of radiation on living systems. Keywords: Molecules.

Switching transient analysis of the cascade STATCOM by the equivalent model with redundant H-bridge submodules

Cascade Static Synchronous Compensator (STATCOM) is a multilevel power electronic device, and its safety, reliability, and operation life are directly affected by switching transient processes. The work presented a switching transient analysis of the redundancy fault-tolerant control for the Cascaded STATCOM by the proposed contactor equivalent model. It was more accurate, ignoring fast dynamic changes and replacing the instantaneous speed with the average speed. Redundancy fault-tolerant control of submodules was crucial to the reliability of Cascade STATCOM. The closing and opening process of the AC contactor generally lasted for several milliseconds. When failure occurred in H-bridge, many factors such as the change of excitation circuit, the resistance, and the capacitance affected the electromagnetic transient process during the closing of the AC contactor. Arc discharge occurred when the H-bridge submodule was re-entered, and the AC contactor was turned off. Based on this, an equivalent model of ac contactor suitable for h-bridge was proposed, considering the influences of excitation circuit, arc discharge, and distribution parameters on switching transient. Simulation and experiments were used to analyze the electromagnetic transient waveform of a single H-bridge sub-module in the contactor closure and disconnection process, and the electromagnetic transient waveform of cascade STATCOM in the redundant sub-module contactor closure and disconnection process. The results showed that the transient change of the proposed model during sub module’s bypass and re-entry process was closer to the physical process. The equivalent model obtained in the work provides the theoretical and numerical basis for the design and operation of high-power power electronic equipment.

3D Time-domain electromagnetic full waveform inversion in Debye dispersive medium accelerated by multi-GPU paralleling

Electromagnetic full waveform inversion in Debye dispersive medium (EFWI-D) is a promising technique to reconstruct the inner structure and electrical properties of the medium such as soil, rock and biological tissues. Same as conventional full waveform inversion, EFWI-D requires high computational cost, especially in the 3D case. To reduce the long computation time, we design and implement the EFWI-D algorithm in time domain using multiple GPU cards. The inversion method is based on the L-BFGS optimization algorithm, which can increase the convergence of the misfit function, while the auxiliary differential equation (ADE) method is employed for modeling the Debye dispersive medium by using exponential time differencing (ETD) finite-difference time-domain (FDTD) approach. Moreover, a multi-stream strategy is performed in the workflow to improve the computation performance. Numerical results illustrate the improvement of the computational performance and the preliminarily feasibility of the proposed inversion algorithm. Program summaryProgram title: 3D Electromagnetic Full Waveform Inversion in Debye Dispersive Medium Based on Multi-GPU ParallelingCPC Library link to program files:https://doi.org/10.17632/mjd9pp5dcm.1Licensing provisions: LGPLProgramming language: C/C++, CUDANature of problem: Electromagnetic FWI derives high-resolution distribution of electrical parameters by using additional information provided by the amplitude and phase of the received signals. It goes beyond ray-tracing tomography techniques, which use only the travel time kinematics of the signals. Mathematically, electromagnetic FWI is a kind of conditional extremum problem which is to minimize the difference between observed and modeled waveform of received signals under the condition of Maxwell's equation.Solution method: The basis of inversion is the solution of the forward problem. In this program, the forward simulation is based on Auxiliary Differential Equation (ADE) method. Since the inverse problem is nonlinear, it is solved by using iterative solution which is an optimization method. As it is well known that 3D FWI requires tremendous computation, multi-GPU paralleling is used in this program to accelerate the computing process.Additional comments including Restrictions and Unusual features: The program is mainly designed to solve the inverse problem in Debye dispersive medium, but it also can be used for solving the forward and inverse problem in nondispersive medium by setting the input parameter: poles_of_debye_dispersive_medium(non_dispersive=0,dispersive=1-5)=0.

Fundamental characteristics and application of radiation

Radiation is the emission or transmission of energy as waves or particles through space or through a material medium which is able to penetrate various materials and is often categorized as either ionizing or non-ionizing depending on the energy of the radiated particles. Radiation processing can be defined as exposure of materials with high energy radiation to change their physical, chemical, or biological characteristics, to increase their usefulness, and safety purpose, or to reduce their harmful impact on the environment. Ionizing radiation is produced by radioactive decay, nuclear fission, and fusion, by extremely hot objects, and by particle accelerators. The radiation coming from the sun is due to the nuclear fusion; therefore, we are living in a natural radioactive world. Radioactive substances are common sources of ionized radiation that emit α, β, or γ radiation, consisting of helium nuclei, electrons or positrons, and photons, respectively. Alpha rays are the weakest form of radiation and can be stopped by paper. Beta rays are able to pass through paper but not through aluminum. Gamma rays are the strongest radiation. They are able to pass through paper and aluminum, but not through a thick block of lead or concrete. Alpha and beta radiation are the high energy subatomic particles where gamma radiation is a form of high energy electromagnetic waves. This review presents the fundamental introduction of radiation, the three types of radiation, and their applications.

Listening to NFC at higher harmonic frequencies

The widespread use of the NFC technology (Near Field Communication) arouses interest to various security aspects. There are known examples of information exchange with card at a distance greater than standard 5-10 cm. It is also interesting to use signals of higher harmonics, which potentially may be radiated in the form of electromagnetic waves, rather than exists as a magnetic field of scattering. In this work, the radiation of third harmonic by card of standard ISO 14443-3А with the fundamental frequency 13.56 MHZ for various excitation modes using the RFID-RC522 reader, smartphone Sony Xperia Z5 Premium, and continuous 10% amplitude modulated 13.56 MHz signal from generator with the subcarrier of imitated smart card response 847.5 kHz was investigated. The card response at third harmonic was simulated in circuit analysis software. Both simulation and experiment proved, that the third harmonic with its side frequencies 40,68 ± 0,8475 MHz have the highest level after the fundamental. To receive the third harmonic signal, the resonant loop antenna in the form of ring vibrator loaded on capacitor was used. This allows the sizes of the received system to be reduced, but the problem of complex field structure in the near-field zone remains. Due to narrow bandwidth of the receiver antenna, the registration of card response signal was complicated. The experiments with three methods of signal generation proved, that third-harmonic signal is registered at the distance more than 1.5m, which may pose a threat for contactless smart-cards transactions security. At the same time, the influence of high level of noise at such a distance may cause difficulties to decode the short-duration signals, which requires further study.

Analytical Modeling and Calculation of Electromagnetic Torque of Interior Permanent Magnet Synchronous Motor Considering Ripple Characteristics

<div class="section abstract"><div class="htmlview paragraph">Based on the classical <i>dq</i> theory, this paper proposes a new electromagnetic torque analytical model (AM) for interior permanent magnet synchronous motor (IPMSM) considering ripple characteristics, including permanent magnet (PM) torque ripple and reluctance torque ripple. The analytical expression of PM torque considering the effect of PM flux linkage harmonics is first derived according to <i>dq</i> transformation and energy method. Then, an improved inductance calculation method considering the non-sinusoidal magnetic field distribution and cross-coupling effect is proposed, and the reluctance torque model is established by taking the influence of inductance harmonics into consideration. Subsequently, the total electromagnetic torque can be obtained by the superposition of PM torque and reluctance torque. Finally, the proposed AM was verified by finite-element method (FEM). The results show that the proposed AM is accurate enough to predict the instantaneous electromagnetic torque waveforms and the average electromagnetic torque. In addition, according to the proposed AM, the sources and order features of torque ripples can be directly determined, and the intrinsic relationship between key electromagnetic parameters and torque harmonics can be revealed.</div></div>

Approaches of Chaotic Image Encryption models in Enlightening Image Storage and Security systems

The present life scenario has become completely digital and intelligent in all aspects, including the way of communication, production methodologies, medical sciences and other entertainment domains. Out of all domains, communication plays a vital role in every human life and the same is valid for corporates who handle bulk amount of data to be transmitted. This may include a multimedia data transfer between defense authorities of various countries or between a commercial information sharing centers. Under these circumstances, such information is to be transmitted in a secured channel. Unfortunately, secured fiber optic or any other wired communication is highly expensive and not affordable for infinite number of users. Hence, most of the communications among people are only through wireless channels. Due to the tremendous developments in communication standards up to 5G, people prefer wireless communications to cover the whole part of the world. As the information is freely available to anyone in the form of electromagnetic waves, it is impossible to share privately through a common wireless network due to week encryption methodologies. Simultaneously key space is not abundant. This has been highly inspired to pursue research in a different direction to a greater degree and to develop the measurements of current cryptography protocols and procedures. Choosing a chaotic encryption domain has several compelling explanations as described here.

Modeling the distribution line form of surface electromagnetic wave and calculating the transmission coefficient of a symmetric strip line

The work is devoted to the analysis of the dependence of the dielectric properties of highly conducting anisotropic materials from the magnitude and the direction of the magnetic field. A nonlinear model of propagation of a surface electromagnetic wave in a planar bismuth waveguide located in a quantizing magnetic field is considered. As a result of the simulation of the shape of the magneto-optical experiment line, a software package in the JavaScript language for calculating the dielectric constant and the bismuth conductivity tensor for each direction (binary, bisector and trigonal) is presented.

Waveform sampling on an atomic scale

A method to quantitatively map transient electromagnetic waveforms with atomic-spatial resolution is now possible using lightwave-driven scanning tunnelling microscopy featuring a single-molecule switch.

The role of scientific research on nuclear radiation waste management and preserving environment

On the level of this article, we deal with nuclear radiation (and their residues), which is defined as a physical phenomenon and strong atomic activity that occurs in unstable atoms of elements. We are interested in studying radiation as the emission or diffusion of energy into space in the form of electromagnetic waves or particles. The scientist Fermi (1934 AD) is among the first to present scientific research in this field. Radioisotopes are considered one of the most prominent discoveries of modern science and based on the importance of the topic, scientists and researchers searched for methods and techniques to facilitate the implementation of practical applications for radiation measurement, and among those methods a specialized program was used to simulate radiation dose (digital simulation in a computer through the use of an imaginary model of the radiometric process with technology Monte Carlo using code (Geant 4). We have also highlighted the views of researchers and specialists in the area of disposal of radioactive waste, relying on a field study and a comparison of some of the currently adopted techniques to get rid of the negative consequences that each unreasonable (reckless) management and measure of this radioactive waste may have Among the most prominent results we have reached is highlighting the weakness of dealing with this topic and not giving it the right to research and scientific achievements carried out by researchers, which increases the complexity of the situation and from which it is difficult to control the problem in the future.

Classical sub-subleading soft photon and soft graviton theorems in four spacetime dimensions

Classical soft photon and soft graviton theorems determine long wavelength electromagnetic and gravitational waveforms for a general classical scattering process in terms of the electric charges and asymptotic momenta of the ingoing and outgoing macroscopic objects. Performing Fourier transformation of the electromagnetic and gravitational waveforms in the frequency variable one finds electromagnetic and gravitational waveforms at late and early retarded time. Here extending the formalism developed in [1], we derive sub-subleading electromagnetic and gravitational waveforms which behave like u−2(ln u) at early and late retarded time u in four spacetime dimensions. We also have derived the sub-subleading soft photon theorem analyzing two loop amplitudes in scalar QED. Finally, we conjectured the structure of leading non-analytic contribution to (sub)n-leading classical soft photon and graviton theorems which behave like u−n(ln u)n−1 for early and late retarded time u.

Quantitative sampling of atomic-scale electromagnetic waveforms

Tailored nanostructures can confine electromagnetic waveforms in extremely sub-wavelength volumes, opening new avenues in lightwave sensing and control down to sub-molecular resolution. Atomic light–matter interaction depends critically on the absolute strength and the precise time evolution of the near field, which may be strongly influenced by quantum-mechanical effects. However, measuring atom-scale field transients has remained out of reach. Here we introduce quantitative atomic-scale waveform sampling in lightwave scanning tunnelling microscopy to resolve a tip-confined near-field transient. Our parameter-free calibration employs a single-molecule switch as an atomic-scale voltage standard. Although salient features of the far-to-near-field transfer follow classical electrodynamics, we develop a comprehensive understanding of the atomic-scale waveforms with time-dependent density functional theory. The simulations validate our calibration and confirm that single-electron tunnelling ensures minimal back-action of the measurement process on the electromagnetic fields. Our observations access an uncharted domain of nano-opto-electronics where local quantum dynamics determine femtosecond atomic near fields. Ultrafast lightwave sampling based on scanning tunnelling microscopy is developed to resolve near fields with sub-picosecond time resolution and sub-nanometre spatial resolution. Parameter-free quantitative measurement is achieved by using a single-molecule switch.

Soft factors from classical scattering on the Reissner-Nordström spacetime

We consider perturbations of the $4$ dimensional Reissner-Nordstr\"om spacetime induced by the probe scattering of a point particle with charge and mass moving on an unbound trajectory with an asymptotically large velocity. The resulting classical radiative solutions are the gravitational and electromagnetic bremmstrahlung. We use these classical solutions to derive the universal photon and graviton soft factor contributions at the tree level, which have the same form as noted in the literature. The soft factor expressions enable us to investigate the tail contribution to the memory effect in late time gravitational and electromagnetic waveforms. We find that generically, the contribution from the charge dominates that from the mass in the late time radiation.

Single-Cycle Optical Control of Beam Electrons.

We report the single-cycle optical control of a freely propagating electron beam with an isolated cycle of midinfrared light. In particular, we produce and characterize a modulated electron current with peak-cycle-specific subfemtosecond structure in time. The direct effects of the carrier-envelope phase, amplitude, and dispersion of the optical waveform on the temporal composition, pulse durations, and chirp of the free-space electron wave function demonstrate the subcycle nature of our control. These results and concept may create novel opportunities in free-electron lasers, laser-driven particle accelerators, ultrafast electron microscopy, and wherever else high-energy electrons are needed with the temporal structure of single-cycle light.

Instantaneous Electromagnetic Torque Waveform Calculations for Switched Reluctance Machines Exploiting Vector Analysis

Switched reluctance (SR) machines are magnetically non-linear electromechanical devices and their full and accurate performance prediction-especially of the instantaneous electromagnetic torque waveforms-is not amenable to closed-form analytical solutions. Consequently, the analysis of such machines is usually performed with the aid of computer-based numerical simulations that-even if providing good accuracy-do not offer physical insight into the electromagnetic energy conversion processes taking place inside the machine. For this reason, the SR machine design and analysis are not simple exercises as they require substantial computational resources and extensive prior design expertise. In this article, a methodology for a reasonably accurate prediction of the instantaneous electromagnetic torque waveforms of the SR machines is proposed using a closed-form analytical solution. The suggested approach relies on a simple vector analysis of the flux-linkage map of a non-linear SR machine and as such avoids integration, non-linear curve fitting, or geometrical series summation. The proposed vector-analysis-based methodology offers intuitive physical insight into the electromagnetic energy conversion processes taking place inside the SR machine related to the instantaneous torque generation.

The Seismic Electromagnetic Emissions During the 2010 Mw 7.8 Northern Sumatra Earthquake Revealed by DEMETER Satellite

The abnormal electromagnetic emissions recorded by the DEMETER satellite associated with the April 6, 2010 Mw 7.8 northern Sumatra earthquake are examined in this study. The variations of wave intensities recorded by revisiting orbits from August 2009 to May 2010 indicate that some abnormal enhancements at ELF (Extremely Low Frequency) range of 300 - 800 Hz occurred from 10 to 3 days before the main shock, while they remained a relatively smooth trend during quiet seismic activity times. The perturbation amplitudes relative to the background map which were built by using the same-time seasonal window (February 1 to April 30) data from 2008 to 2010 further suggested strong enhancements of wave intensities during the period prior to the earthquake. We computed the wave propagation parameters for the electromagnetic field waveform data by using the Singular Value Decomposition method, and results show that there are certain portions of the ELF emissions obliquely propagating upward from the Earth towards outer space direction at 10 and 6 days before the main shock. The potential energy variation of acoustic-gravity wave (AGW) suggests the possible existence of AGW stability with wavelengths roughly varying from 5.45 to 9.49 km in atmosphere at the time of the main shock. In this study, we comprehensively investigate the link between the electromagnetic emissions and the earthquake activity through a convincing observational analysis, and preliminarily explore the seismic-ionospheric disturbance coupling mechanism, which is still not fully understood at present by the scientific community.

Analytical Calculation of Performance of Line-Start Permanent-Magnet Synchronous Motors Based on Multidamping-Circuit Model

This article presents a new analytical method for calculating performance of line-start permanent-magnet synchronous motor (LSPMSM) based on multidamping-circuit model (MDCM) to take spatial harmonic components of LSPMSM into account. First, MDCM of damping bar in the rotor is established according to Kirchhoff's current law. Second, an eleven-order system of LSPMSM is deduced from a group of differential equations according to the equations of flux linkage, voltage, torque, and motion. Then, starting process of LSPMSM is simulated with the proposed analytical method, including speed, current, and electromagnetic torque waveforms versus time, respectively. The starting performance and synchronization capability are analyzed and compared under different effective value of input phase voltage, moment of inertia, and load torque. The simulation time with finite element method is about 1235 times longer than the simulation time with the proposed analytical method to calculate the starting process of LSPMSM with the same computer. Finally, the validation of the developed analytical method based on MDCM is verified by comparing simulating results with experimental results and direct axis and quadrature axis (DQ) model. The results based on this new method are reliable. It is conducive to calculate, analyze, and design LSPMSM with less time.

Active Huygens’ Box: Arbitrary Electromagnetic Wave Generation With an Electronically Controlled Metasurface

This work investigates the generation of arbitrary electromagnetic waveforms inside a geometrical area enclosed by an active metasurface. We introduce the Huygens' box, where a region of space is enclosed by an active Huygens' metasurface. We show that, upon generating the necessary electric and magnetic currents, we can create any desired electromagnetic field inside Huygens' box. Using this method, we demonstrate, through simulation and experiment, the generation of traveling plane waves, a standing plane wave, and a Bessel wave inside a metallic cavity. These waves are generated using the same (reconfigurable) metasurface by aptly controlling the electronic excitations. By linear superposition of these unconventional traveling-wave “modes,” we experimentally demonstrate, for the first time, a subwavelength superoscillation focal spot formed without involving evanescent EM waves and without an accompanying region of exorbitantly high waveform energy. The Huygens' box brings controlled waveform generation to an unprecedented level, with far-reaching implications to imaging, wireless communication, and medical therapy.

ELECTROMAGNETIC SWITCHING TRANSIENTS IN TRANSMISSION LINE COOPERATING WITH THE LOCAL SUBSYSTEM

The article investigates the overvoltage occurring during switching states in the line cooperating with the local subsystem. It discusses the possibilities of determining extreme values of overvoltage of all kinds by means of simulation tests. In particular, special attention was paid to the need to faithfully representation of components in power system i.e. transmission line, voltage transformer and surge arrester for correct reproduce electromagnetic waveforms on the primary as well as secondary side of voltage transformers. Overvoltages appearing in the line connected to the local subsystem during switching operations are forced by the change of network operating conditions. Electromagnetic transients in the unloaded line were tested after its sudden disconnection from the power supply. In the research, particular attention was paid to the conditions of switching off the line (moment and disconnection unity), the influence of surge protection devices, the type of the voltage transformer and the short-circuit power of the power subsystems. Simulation tests have shown that under certain conditions overvoltages with dangerously high values (e.g. 2.25x400 kV) may occur.

Analysis of Torque Ripples of an Induction Motor Taking into Account a Inter-Turn Short-Circuit in a Stator Winding

Despite the increasing popularity of permanent magnet synchronous machines, induction motors (IM) are still the most frequently used electrical machines in commercial applications. Ensuring a failure-free operation of IM motivates research aimed at the development of effective methods of monitoring and diagnostic of electrical machines. The presented paper deals with diagnostics of an IM with failure of an inter-turn short-circuit in a stator winding. As this type of failure commonly does not lead immediately to exclusion of a drive system, an early stage diagnosis of inter-turn short-circuit enables preventive maintenance and reduce the costs of a whole drive system failure. In the proposed approach, the early diagnostics of IM with the inter-turn short-circuit is based on the analysis of an electromagnetic torque waveform. The research is based on an elaborated numerical field–circuit model of IM. In the presented model, the inter-turn short-circuit in the selected winding has been accounted for. As the short-circuit between the turns can occur in different locations in coils of winding, computations were carried out for various quantity of shorted turns in the winding. The performed analysis of impact of inter-turn short-circuit on torque waveforms allowed to find the correlation between the quantity of shorted turns and torque ripple level. This correlation can be used as input into the first layer of an artificial neural network in early and noninvasive diagnostics of drive systems.