Generation Of Electromagnetic Fields Research Articles

Detection and Identification of Pesticides in Fruits Coupling to an Au-Au Nanorod Array SERS Substrate and RF-1D-CNN Model Analysis.

In this research, a method was developed for fabricating Au-Au nanorod array substrates through the deposition of large-area Au nanostructures on an Au nanorod array using a galvanic cell reaction. The incorporation of a granular structure enhanced both the number and intensity of surface-enhanced Raman scattering (SERS) hot spots on the substrate, thereby elevating the SERS performance beyond that of substrates composed solely of an Au nanorod. Calculations using the finite difference time domain method confirmed the generation of a strong electromagnetic field around the nanoparticles. Motivated by the electromotive force, Au ions in the chloroauric acid solution were reduced to form nanostructures on the nanorod array. The size and distribution density of these granular nanostructures could be modulated by varying the reaction time and the concentration of chloroauric acid. The resulting Au-Au nanorod array substrate exhibited an active, uniform, and reproducible SERS effect. With 1,2-bis(4-pyridyl)ethylene as the probe molecule, the detection sensitivity of the Au-Au nanorod array substrate was enhanced to 10-11 M, improving by five orders of magnitude over the substrate consisting only of an Au nanorod array. For a practical application, this substrate was utilized for the detection of pesticides, including thiram, thiabendazole, carbendazim, and phosmet, within the concentration range of 10-4 to 5 × 10-7 M. An analytical model combining a random forest and a one-dimensional convolutional neural network, referring to the important variable-one-dimensional convolutional neural network model, was developed for the precise identification of thiram. This approach demonstrated significant potential for biochemical sensing and rapid on-site identification.

Magnetic Microrobot Spin Motility Characterization Using a Model Prediction Adaptive Control-Enhanced Electromagnetic Coil System

Magnetic microrobots (MMs) have been receiving tremendous attention due to their advantages of untethered controllability and bio-compatibility, and they have been shown to be promising tools for targeted therapy. Ahead of implementations, one of the most vital motion properties of the MMs, i.e. the fundamental spin motility, should be characterized for better utilization. To fulfill the precise characterization of MMs, it is of great value to develop an electromagnetic field generator with high accuracy. One electromagnetic field generator usually equips its coils with iron cores to enhance the generated magnetic field (MF) strength, which may also bring in unwanted nonlinear and temperature-dependent dynamic properties. The complex properties usually make the coils hard to control to maintain consistent good performances. To generate a desirable MF under varying temperature conditions, this study develops a model prediction adaptive control (MPAC) approach to regulate the coil system adaptively. Validation tests show that, compared with the prevalent MPC method, the MPAC approach can generate a more accurate MF at different ambient temperatures. As an application, the MPAC-controlled MF generator is utilized to characterize the MM's spin motility, and a nonlinear dynamic model is established, which can properly describe the MM's spin behavior under various excitation conditions.

The influence of the da Vinci surgical robot on electromagnetic tracking in a clinical environment

Robot-assisted surgery is increasingly used in surgery for cancer. Reduced overview and loss of anatomical orientation are challenges that might be solved with image-guided surgical navigation using electromagnetic tracking (EMT). However, the robot’s presence may distort the electromagnetic field, affecting EMT accuracy. The aim of this study was to evaluate the robot’s influence on EMT accuracy. For this purpose, two different electromagnetic field generators were used inside a clinical surgical environment: a table top field generator (TTFG) and a planar field generator (PFG). The position and orientation of sensors within the electromagnetic field were measured using an accurate in-house developed 3D board. Baseline accuracy was measured without the robot, followed by stepwise introduction of potential distortion sources (robot and robotic instruments). The absolute accuracy was determined within the entire 3D board and in the clinical working volume. For the baseline setup, median errors in the entire tracking volume within the 3D board were 0.9 mm and 0.3° (TTFG), and 1.1 mm and 0.4° (PFG). Adding the robot and instruments did not affect the TTFG’s position accuracy (p = 0.60), while the PFG’s accuracies decreased to 1.5 mm and 0.7° (p < 0.001). For both field generators, when adding robot and instruments, accuracies inside the clinical working volume were higher compared to the entire tracking 3D board volume, 0.7 mm and 0.3° (TTFG), and 1.1 mm and 0.7° (PFG). Introduction of a surgical robot and robotic instruments shows limited distortion of the EMT field, allowing sufficient accuracy for surgical navigation in robotic procedures.

Generic Vectorial Hologram Based on Simultaneous and Independent Amplitude and Phase Modulation of Orthogonal Polarization States via Single Completely Spin‐Decoupled Meta‐Particles

AbstractMetasurfaces composed of subwavelength structure arrays provide a diverse and powerful platform for generation of complicated electromagnetic (EM) fields and wavefronts manipulation and have triggered an unprecedented research upsurge in electromagnetism with the development of computer‐generated holography (CGH). Different from conventional scalar holograms only containing amplitude and phase properties, a vectorial hologram that benefits from the maneuverability of polarization of EM fields exhibits more immeasurable application potential and is simultaneously regarded as an urgent requirement. In this work, assisted by single completely spin‐decoupled meta‐particles, which perfectly combine the functions of simultaneous and independent amplitude and phase modulation of orthogonal polarization states containing left‐ and right‐handed circularly polarized (LCP&amp;RCP) components, a vectorial hologram induced through eigenstates degeneracy with the ability of encoding arbitrary polarization is proposed in the microwave region. As the proof of concept, eight distinct holograms with specified polarizations and six‐channel polarization‐multiplexed hologram display are fabricated and characterized, further showcaing the versatility of the approach for the customization of arbitraty polarization and integration of reconstructed patterns. With the advantages of multi‐controllability and ultra‐compactness, the constructed monolayer completely spin‐decoupled paradigm for vectorial regulation may find prospective application aspects in spin detection, target perception, multi‐channel data encryption, and many other related fields.

Evolutions of hydrodynamic and electromagnetic wakes induced by underwater vehicles

The electromagnetic wake induced by the movement of stratified conductive seawater in the presence of the geomagnetic ambiance contains vital information for non-acoustic detection. However, the intricate mechanism among hydrodynamics, ions transports, and vortex evolution has not been systematically explored, which synergistically generate the electromagnetic wake. In this context, an interdisciplinary model involving continuity, momentum, heat and mass transfer, and Maxwell's equations is constructed by the ANSYS Fluent software to address the evolution of wake characteristics behind a full-scale submarine-propeller vehicle. The instantaneous visualizations including velocity distributions, vortex interactions, electromagnetic signatures, and vortex dynamics during downstream evolution are reproduced by the high-fidelity numerical simulations. Tip vortex pairing in the circumferential direction and secondary vortex system originating from the local distortions in the helical morphology due to the wake of the sails are observed and described. Flow fields and electromagnetic features at different axial and radial positions in the wake are also discussed. The results manifest that the pronounced intensity of the induced magnetic field can attain 0.5 nT, which can be detected by precise magnetometers. Moreover, velocity components and induced magnetic fields are thoroughly examined to reveal the mechanism of induced electromagnetic field generation, which is closely linked to the flow velocity and background geomagnetic field. Subsequently, dynamic analyses by power spectral densities are executed to further inspect the frequency characteristics. These scientific findings provide beneficial insights for the research on hydrodynamic and electromagnetic wake, especially considering the potential application of submersible non-acoustic detection.

INCLUDING THE OWN FIELDS OF QUANTUM EMITTERS IN DESCRIBING GENERATION REGIMES

The paper discusses three different modes of electromagnetic field generation by an ensemble of quantum emitters placed at the radiation wavelength in the one-dimensional case. The excitation of the resonator field is considered, which, as a rule, is determined by the geometry of the system, with and without taking into account the eigenfields of the emitters. The superradiance mode of the same ensemble of emitters is also analyzed. Since the main indicator of generation is the level of energy output from the system, the position of the maximum of this indicator determines the operating point of the device. Taking into account the intrinsic field of the emitters enhances the generation intensity and significantly changes the position of the operating point.

Ultrafast and terahertz spintronics: Guest editorial

Spin-based electronics (spintronics) aims at extending electronic functionalities, which rely on the electron charge as information carrier, by the spin of the electron. To make spintronics competitive and compatible with other information carriers like photons and electrons, their speed needs to be pushed to femtosecond time scales and, thus, terahertz frequencies. In ultrafast and terahertz spintronics, femtosecond optical and terahertz electromagnetic pulses are used to induce spin torque and spin transport and to monitor the subsequent time evolution. The two approaches, sometimes referred to as femto-magnetism and terahertz magnetism, have provided new, surprising, and relevant insight as well as applications for spintronics. Examples include the ultrafast optical switching of magnetic order and the generation of broadband terahertz electromagnetic fields. This APL Special Topic Collection is dedicated to provide a platform for the newest developments and future trends in the very active, dynamic, and exciting research field of ultrafast and terahertz spintronics.

On Accounting for Own Fields of Emitters when Describing Generation Modes

The paper discusses three different modes of electromagnetic field generation by an ensemble of oscillators placed at the radiation wavelength in the one-dimensional case. The excitation of the resonator field is considered, which, as a rule, is determined by the geometry of the system, with and without taking into account the eigenfields of the emitters. The superradiance regime of the same ensemble of oscillators is also analyzed. In fact, superradiance is formed due to the emitters' own fields even in the absence of a resonator. It is noted that the maximum achievable amplitudes of induced fields both in the superradiance regime and in the regime of excitation of the resonator field are comparable. This makes us think about the role of the self-fields of emitters in electronic devices. It is shown that in describing the resonator excitation mode, in addition to the resonator field, it is also necessary to take into account the sum of the natural fields of the emitters in the active zone. Synchronization of emitters leads not only to an increase in the resonator field, but also, as in the superradiance regime, it significantly increases the amplitude of the sum of the oscillator fields. It is shown that in the practically interesting case of open systems (dissipative generation modes), taking into account the eigenfields of the emitters significantly reduces the characteristic time for the development of the generation process and increases the maximum achievable oscillation amplitude. This account also changes the conditions for achieving the maximum energy flow from the system. This can change the operating point of the generation process, which is determined by the requirement for the maximum rate of energy output from the system.

Stopped Flow of Glycerol Induces the Enhancement of Adsorption and Aggregation of HRP on Mica.

Glycerol is a usable component of heat-transfer fluids, and is thus suitable for the use in microchannel-based heat exchangers in biosensors and microelectronic devices. The flow of a fluid can lead to the generation of electromagnetic fields, which can affect enzymes. Herein, by means of atomic force microscopy (AFM) and spectrophotometry, a long-term effect of stopped flow of glycerol through a coiled heat exchanger on horseradish peroxidase (HRP) has been revealed. Samples of buffered HRP solution were incubated near either the inlet or the outlet sections of the heat exchanger after stopping the flow. It has been found that both the enzyme aggregation state and the number of mica-adsorbed HRP particles increase after such an incubation for 40 min. Moreover, the enzymatic activity of the enzyme incubated near the inlet section has been found to increase in comparison with that of the control sample, while the activity of the enzyme incubated near the outlet section remained unaffected. Our results can find application in the development of biosensors and bioreactors, in which flow-based heat exchangers are employed.

Advances in Marine Intelligent Electromagnetic Detection System, Technology, and Applications: A Review

This paper introduces the current state of the art in marine intelligent electromagnetic detection sensors, systems and platforms for the detection and health monitoring of offshore structures, especially for subsea cables and pipelines. The presented survey is by no means exhaustive, but introduce some notable results and relevant techniques in the detection and inspection of marine structure electromagnetic monitoring fields. Particularly, this paper presents a review of the main research works focusing on electromagnetic detection techniques and intelligent marine vehicles for subsea cables. The marine electromagnetic exploration techniques are elaborated as active and passive detections based on different electromagnetic field generation and sensing principles. The pulse induction-based detection method for subsea ferromagnetic lines detection, transient and controlled-source electromagnetic systems in marine geological fields under the category of active detection approach, are reviewed. According to the classical applications on subsea cable-like target inspection, the passive detection approach is detailed classified as crisscrossing detection and along-tracking detection, which are characterised by different trajectories of detection vehicles. Finally, the paper discusses the marine electromagnetic detection techniques in general and highlights challenges that need to be addressed in developing detection vehicles with lower electromagnetic noises and advanced autonomy on carrying out detection missions.

A tool-free neuronavigation method based on single-view hand tracking

ABSTRACT This work presents a novel tool-free neuronavigation method that can be used with a single RGB commodity camera. Compared with freehand craniotomy placement methods, the proposed system is more intuitive and less error prone. The proposed method also has several advantages over standard neuronavigation platforms. First, it has a much lower cost, since it does not require the use of an optical tracking camera or electromagnetic field generator, which are typically the most expensive parts of a neuronavigation system, making it much more accessible. Second, it requires minimal setup, meaning that it can be performed at the bedside and in circumstances where using a standard neuronavigation system is impractical. Our system relies on machine-learning-based hand pose estimation that acts as a proxy for optical tool tracking, enabling a 3D-3D pre-operative to intra-operative registration. Qualitative assessment from clinical users showed that the concept is clinically relevant. Quantitative assessment showed that on average a target registration error (TRE) of 1.3 cm can be achieved. Furthermore, the system is framework-agnostic, meaning that future improvements to hand-tracking frameworks would directly translate to a higher accuracy.

Controlled Electromagnetic Field Based Safety System for Handheld Circular Saw.

This paper presents the design of a safety system based on controlled electromagnetic field (CEMF) sensing technology to prevent accidents caused by power tools, especially related to handheld circular saws. The safety system creates an invisible protection bubble of electromagnetic field around the cutting edge. The system can provide early warning or critical warning when a person penetrates the safety bubble. This paper covers how the CEMF technology has been adapted to add value within this application where it needs to coexist with a difficult environment of metallic parts turning thousands of times per minute, strong vibrations, and different ranges of materials to be processed. The proposed contactless solution successfully detects the user, providing enough time for the power tool to totally stop its movement before touching and harming the user. This key property has required a careful optimization of the electromagnetic field generation, the design of a shield circuitry capable of operating properly in a large metal device, and the development of a multi-frame algorithm to address the stringent requirements related to the ability of the system to react to both very fast and very slow events. The feasibility of the system has been validated by a virtual testbench.

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.

Biocomunicação Instrumental, um novo recurso de terapia na prática clínica

Quantum physics considers that the human body is an electromagnetic field generator, which is influenced by the environment and other living beings (biocommunication)_ Therefore, our body acts as a gauge and generator of&#x0D; bioinformation. Studies in this area have Increased considerably in recent years, mainly with the use of equipment (instrumental biocommunication) which aim to rebalance the patient's electromagnetic field by sending information. The possibility of these devices recognizing the body's quantum physicochemical properties and intervening in them has presented promising results for this new type of therapy. The theory proposes to&#x0D; intervene on the disease by transmitting specific electronic vibrations to take the atom back to normal vibration and eliminate the disease, that is, to bring the atom to a level of stability so that it can get back to work properly. This review aims to review the available information on one of the equipment that proposes to this therapy, Quantec_

Generation of electromagnetic resonators and strong electrostatic fields at the plasma boundary by a beam of powerful radiation

The interaction of an electromagnetic beam with a sharp boundary of a dense cold semi-limited plasma is considered in the case of the normal wave propagation to the plasma surface for different intensity values with respect to thermal energy of electrons. At relatively small radiation energies, when the deformation of the boundary is insignificant, the possibility of the appearance of an electrostatic field outside the plasma has been revealed, the intensity of which decreases according to the power law with a distance from the plasma and the center of the beam, is close in magnitude to the amplitude of the electric field strength of the wave and which does not have an oscillatory space-time structure. If the intensity of the beam is comparable to the thermal energy of electrons at the boundary, it is possible to form cavities with a reduced electron density being each electromagnetic resonator of a spherical, ellipsoidal or cylindrical shape, which move deep into the dense plasma and at certain ratios of plasma and beam parameters to exist in a stable state for a long time.

Novel electromagnetic induction heat curing process of fly ash geopolymer using waste iron powder as a conductive material

Geopolymer (GP) was invented to replace concrete, but its heat curing requirement hinders extensive use in real-world construction. Past studies have tested several methods of heat curing. However, the conventional heat curing process (using an oven) is still required for GP to develop good strength on the laboratory scale. This study introduces a new heat curing method for GP based on an electromagnetic field (EMF)generator and a ferromagnetic material. Waste iron powder (WIP) was used as the ferromagnetic material mixed with the fly ash-based GP to generate heat through induction. The sample was cured at 1.18 kW with 150–200 kHz of EMF generator for 15 min. The results showed that 5% of the WIP mixed sample gained compressive and flexural strength at 28 days more than the control (oven-cured). Compressive and flexural strengths of 76.8 MPa and 11.3 MPa were obtained, respectively. In addition, heat induction enhanced the densification and geopolymerization in the GP matrix following SEM and XRD results. This alternative method of heat curing accelerated the formation of the GP matrix, reduced curing time, and increased strength. Moreover, this EMF curing method can save 99.70% of the energy consumed compared to the conventional heat curing method.

Features of the Generation of Extreme Electromagnetic Fields in a Mesoscale Dielectric Sphere with Regard to the Environment

Features of the Generation of Extreme Electromagnetic Fields in a Mesoscale Dielectric Sphere with Regard to the Environment

Peculiarities of Generation of Extreme Electromagnetic Fields in a Dielectric Mesoscale Sphere with the presence of the Environment

The results of numerical simulation based on the Mie theory of the effect of superresonance (high-order Fano resonance) for a mesoscale dielectric sphere immersed in air are presented, since the environment in the form of a vacuum is an idealization that is almost never realized in nature. Using the example of a particle with a refractive index of 1.5 and a size parameter q~ 26 and q~ 38, it was demonstrated for the first time that a change in the refractive index of the environment by 2.4· 10-4 leads to a decrease in the field intensity in the region of the shadow pole of the sphere by an order of magnitude and a shift of the resonant value of the size parameter q to the short-wavelength region. In this case, the relative intensities of the resonant peaks for both the magnetic and electric fields in the vicinity of the poles of the sphere in the optical range can reach values characteristic of a particle in vacuum (of the order of 106-107), with an appropriate adjustment of the resonant size parameter. Keywords: high-order Fano resonance, superresonance, mesotronics, field intensity, extreme magnetic field.

Design and Development of a New Rotating Electromagnetic Field Generation System for Driving Microrobots

This article presents the design, optimization, and testing of a new rotating electromagnetic field generation system for actuating magnetic microrobots. Its unique feature lies in that the proposed six-coil electromagnetic actuation system produces a uniform rotating magnetic field with a large 3-D workspace, which is enabled by conducting an architectural optimization of the system in consideration of both electric issues and geometry constraints. To maintain a low working temperature, each coil is fabricated with silicone grease for filling the gap among the copper wires and integrated with a water cooling fan for reducing the effect of coil heating. An analytical model is established to determine the dominant structural parameters, which are optimally tuned by resorting to genetic algorithm (GA) to achieve the best actuation performance. A prototype magnetic field generation system is developed for experimental testing. Experimental studies are carried out by driving various magnetic microrobots, including helical microswimmers and microparticles. Results indicate that the developed system can effectively actuate the microrobots with precision motion tracking, validating the effectiveness of the developed rotating magnetic field generation system.

Transverse and longitudinal coupling of LSPPs in isolated triangular Al–SiO2–Al hybrid nanoplates for generation of local electromagnetic fields with enhanced intensity and increased decay time

Achieving a large enhancement of local electromagnetic fields in the ultraviolet waveband is desirable for some applications such as surface-enhanced Raman scattering and surface-enhanced fluorescence. In addition, it is more significant for some applications such as plasmon-enhanced harmonic generation to enhance the intensity of local electromagnetic fields and increase their decay time at the same time. In this paper, using the finite-difference time-domain method, we numerically demonstrate that using the linearly polarized light with a wavelength of 325 nm as the illumination light, an isolated triangular Al–SiO2–Al hybrid nanoplate with optimized geometric parameters can produce a local electric field enhanced by a factor of about 108 at one of its top apexes, and produce two local electric fields enhanced by a factor of about 150 at two transverse dielectric/metal interfaces of one of its longitudinal side edges. Moreover, we also numerically demonstrate that the decay time of enhanced local electric fields produced by the isolated triangular Al–SiO2–Al hybrid nanoplate is about 1.6 times as large as that of enhanced local electric fields produced by an isolated triangular Al nanoplate. These unique properties of the isolated triangular Al–SiO2–Al hybrid nanoplate arise because of both the transverse coupling and the longitudinal coupling of localized surface plasmon polaritons in this structure. Our findings make triangular Al–SiO2–Al hybrid nanoplates very promising for application in many fields such as surface-enhanced Raman scattering and plasmon-enhanced harmonic generation.