Law Of Electromagnetic Induction Research Articles

Micromagnetic stimulation (µMS) dose-response of the rat sciatic nerve

Objective. The objective of this study was to investigate the effects of micromagnetic stimuli strength and frequency from the Magnetic Pen (MagPen) on the rat right sciatic nerve. The nerve’s response was measured by recording muscle activity and movement of the right hind limb. Approach. The MagPen was custom-built to be stably held over the sciatic nerve. Rat leg muscle twitches were captured on video, and movements were extracted using image processing algorithms. EMG recordings were also used to measure muscle activity. Main results. The MagPen prototype, when driven by an alternating current, generates a time-varying magnetic field, which, according to Faraday’s law of electromagnetic induction, induces an electric field for neuromodulation. The orientation-dependent spatial contour maps of the induced electric field from the MagPen prototype have been numerically simulated. Furthermore, in this in vivo work on µMS, a dose-response relationship has been reported by experimentally studying how varying the amplitude (Range: 25 mV p-p through 6 V p-p) and frequency (range: 100 Hz through 5 kHz) of the MagPen stimuli alters hind limb movement. The primary highlight of this dose-response relationship (repeated over n rats, where n = 7) is that for a µMS stimuli of higher frequency, significantly smaller amplitudes can trigger hind limb muscle twitch. This frequency-dependent activation can be justified by Faraday’s Law, which states that the magnitude of the induced electric field is directly proportional to the frequency. Significance. This work reports that µMS can successfully activate the sciatic nerve in a dose-dependent manner. The impact of this dose-response curve addresses the controversy in this research community about whether the stimulation from these μcoils arise from a thermal effect or micromagnetic stimulation. MagPen probes do not have a direct electrochemical interface with tissue and therefore do not experience electrode degradation, biofouling, and irreversible redox reactions like traditional direct contact electrodes. Magnetic fields from the μcoils create more precise activation than electrodes because they apply more focused and localized stimulation. Finally, unique features of µMS, such as the orientation dependence, directionality, and spatial specificity, have been discussed.

The influences of external magnetic field on the reflection and transmission waves at the interface of two dipolar gradient elastic solids

The elastic wave propagation and the reflection and transmission at interface with consideration of the microstructure effects and the Lorentz force simultaneously are investigated in the present work. The microstructure effects are modelled by the dipolar gradient elasticity and the Lorentz force due to the external magnetic field is derived by the electromagnetic induction law and Maxwell equation. The numerical results are provided for incident P wave, incident SV wave and incident SH wave, respectively. It is found that the microstructure effects induce the dispersive feature of elastic waves but the external magnetic field do not contribute to the dispersion with only influence on the amplitude of speed. The surface waves are more sensitive to the external magnetic field and the microstructure effects compared with the bulk waves.

Design and modeling of a novel triple-magnet magnetic dynamic vibration absorber

A novel Triple-magnet Magnetic Dynamic Vibration Absorber (TMDVA) with Eddy Current Damping (ECD) and Coulomb damping is proposed in this paper. A multi-storey structure is selected as the vibration reduction object. First, the equivalent dynamics model of the TMDVA multi-storey structure vibration reduction system is established. Then the nonlinear magnetic force model is built according to the magnetizing current theory. Next, an ECD accurate calculation model is developed and derived based on Faraday’s law of electromagnetic induction. Because of the model, the ECD coefficient can be designed and adjusted arbitrarily. The full text indicates that adjusting the ECD coefficient properly can not only improve the vibration reduction effect of the TMDVA, but also reduce the sensitivity of the vibration reduction effect to the excitation amplitude as well as enhance the broadband vibration reduction performance and the robustness of the TMDVA. With its simple structure, the TMDVA is easy to be implemented and miniaturized. And the low frequency vibration reduction effect of the TMDVA is better than other existing magnetic dynamic vibration absorbers. Taken together, the TMDVA has potential application value in passive vibration reduction of engineering structures.

Electromagnetic induction: How the “flux rule” has superseded Maxwell's general law

As documented by textbooks, the teaching of electromagnetic induction in university and high school courses is primarily based on what Feynman labeled as the “flux rule,” downgrading it from the status of physical law. However, Maxwell derived a “general law of electromagnetic induction” in which the vector potential plays a fundamental role. A modern reformulation of Maxwell's law can be easily obtained by defining the induced electromotive force as ∮l(E→+v→c×B→)·dl→, where v→c is the velocity of the positive charges which, by convention, are the current carriers. Maxwell did not possess a model for the electric current. Therefore, in his law, he took v→c to be the velocity of the circuit element containing the charges. This paper aims to show that the modern reformulation of Maxwell's law governs electromagnetic induction, and the “flux rule” is not a physical law but only a calculation shortcut that does not always yield the correct predictions. This paper also tries to understand why Maxwell's law has been ignored, and how the “flux rule” has taken root. Finally, a section is dedicated to teaching this modern reformulation of Maxwell's law in high schools and elementary physics courses.

Electricity Generation by Wind Using Resonance and Piezoelectric Effect

Faraday's law of Electromagnetic Induction is the working principle behind A.C.-D.C. generators, which contributes a major part of the generated electricity utilized today. However, the Photoelectric Effect used in Solar cells is also a useful source of renewable energy produced from the sun. In this research work, we have tried to generate electricity from the concept of Resonance and Piezoelectric Effect. To achieve the goal, we have used a thin strip of stretch-resistant material which naturally has the property of resisting the applied stretching force. The length of this stretch-resistant material will be set up so that the incoming airflow will make the thin strip vibrate at its resonant frequency. This will create high-amplitude mechanical vibrations on the thin strip. Now, these vibrations will be passed to the piezoelectric material. Piezoelectric materials have the property to exhibit the piezoelectric effect, which will convert the high amplitude mechanical vibrations passed by thin strips to the piezoelectric material into electrical discharge and hence, we generated electricity from wind using Piezoelectric Effect & Resonance. Due to less moving parts in our setup, it is theoretically more efficient in high wind conditions where a windmill usually fails to work. The only moving part is the thin strip which moves in a flapping motion hence, the generator is named a flapping generator. Even though the generated electricity is in a lesser amount, we can create an array of some such setups to increase the output electricity (as we do in solar energy generation) as per our requirement.

Research on Characteristics of Magnetohydrodynamic Micro-Angle Vibration Sensor in AC Magnetic Field

Magneto-hydrodynamic micro angle vibration sensor (MHD sensor) is based on the law of electromagnetic induction. The AC magnetic field might be coupled to the working magnetic circuit, thus affects the sensor output. In order to suppress the influence of AC magnetic on the sensor, a model quantifying the interference between the sensors’ output and AC magnetic field is established. The electrical loop within the MHD sensor is optimized, and magnetic shielding measures are adopted to reduce the external magnetic influence on the sensor. ANSYS Maxwell software is used to simulate and analyze the MHD sensor in AC magnetic field. Finally, experiments are conducted to verify the proposed model and optimization measures. Electromagnetic coils are used to generate the AC magnetic field needed for the experiments. Simulation and experimental results show that the AC magnetic influences on the static and dynamic characteristics of MHD sensor are different. Specifically, the optimized & shielded MHD sensor is proved to be more insensitive to the AC magnetic, which is followed by the optimized one and shielded one, and the original sensor is the worst. The results demonstrate that the MHD sensor can be improved to be insensitive to the AC magnetic field through electrical loop optimization and the implementation of magnetic shielding measures.

New insights into Maxwell’s equations based on new experimental discoveries

No theory is absolute as scientific exploration is the product of human ingenuity, which will continue to evolve with the development of new discoveries and technology.It has been established that the electric field is produced by friction, and the changing electric field can be then generated by constant friction. After the friction stops, this electrostatic field will exist for a designated period of time or even longer. Accordingly, a series of experiments were designed to test the proposed Collision Electro–Magnetic Theory (CEMT) that the electromagnetic energy can be generated by the collision. The 1-W bulb can be lighted by collecting the changing electric field energy when a polymethyl methacrylate (PMMA) board was rubbed with polytetrafluoroethylene (PTFE) film by hand. When a closed coil was placed in the changing electric field, an induced current and an induced electromotive force were generated in the coil, which also magnetized the scissors in the coil. The 1-W bulb can produce a current by the generated changing electric field, when one end of the plastic rods was rubbed by fur.In addition, we discovered that shaking the plastic rod with an electrostatic field generated by the friction can also generate a changing electric field, which not only wirelessly lighted the 28-W fluorescent tube lamp, but also produced an induced current and an induced electromotive force in the closed coil nearby the lamp.Based on the above experiments, we have the following speculation: just as the unified theory of electromagnetism suggests, the changing electric field produces a magnetic field, and the varying magnetic field produces an electric field. Stated plainly, the electric field is in fact a magnetic field and the magnetic field is also an electric field, so they can be both be regarded as energy fields in essence. The coil and conductor can be regarded as the energy collector that can collect energy from the energy field, as long as there is a constantly changing energy field in the collector. The conduction current is transmitted in the collector, while part of the energy field that is not collected in free space, which corresponds to the displacement current calculated in the fourth equation of Maxwell's equations.The essence of Maxwell's equations and related laws are two different phenomena resulting from an energy field in the closed-loop self-circulating state or open-loop acyclic state. The first equation describes an open-loop static energy field, and the second equation describes a closed-loop static energy field. The third equation describes how the induced conduction current can be generated in the closed-loop energy field, and the fourth equation describes how the induced conduction current can be generated in the open-loop energy field.Based on the new experimental discoveries, this work interprets Faraday's law of electromagnetic induction, Maxwell's displacement current and Maxwell's equations from a new perspective, which is important to understand the nature of Maxwell's equations systematically.

From Faraday’s law to the expanded Maxwell’s equations for a mechano-driven media system that moves with acceleration

<p indent="0mm">In classical electrodynamics, by motion for either the observer or the media, it always naturally assumed that the relative moving velocity is a constant along a straight line (e.g., in an inertia reference frame), so that the electromagnetic behavior of charged particles in vacuum space can be easily described using special relativity. However, for engineering applications, the media have shapes and sizes and may move with acceleration, and recent experimental signs of progress in triboelectric nanogenerators have revealed pieces of evidence for expanding Maxwell’s equations to include media motion that could be time and even space dependent. Therefore, we have developed the expanded Maxwell’s equations for a mechano-driven media system (MEs-f-MDMS) by neglecting relativistic effect. This article first presents the updated progresses made in the field. Secondly, we extensively investigated Faraday’s law of electromagnetic induction for a media system that moves with an acceleration. We found that, the “anti-flux rule” examples outlined by Feynman in his book are just caused by the accelerated motion of the media, which were not included in Maxwell’s equations, but disregarded. This is a typical example that Maxwell’s equations have to be expanded for moving media. Therefore, the charged moving media are confirmed to be the sources of generating electromagnetic radiation (a motion-generated electromagnetic field); and the generated electromagnetic wave within the medium can be described using the expanded Maxwell’s equations. Most importantly, in comparison to the existing classical electrodynamics, the newly developed MEs-f-MDMS marks four unique advances, which have been summarized and the near field electrodynamics vs. the far field electrodynamics are proposed.

Faraday's equation and law of electromagnetic induction - theory and practice

Faraday's equation and law of electromagnetic induction - theory and practice

The expanded Maxwell’s equations for a mechano-driven media system that moves with acceleration

In classical electrodynamics, by motion for either the observer or the media, it is always naturally assumed that the relative moving velocity is a constant along a straight line (e.g., in inertia reference frame), so that the electromagnetic behavior of charged particles in vacuum space can be easily described using special relativity. However, for engineering applications, the media have shapes and sizes and may move with acceleration, and recent experimental progresses in triboelectric nanogenerators have revealed evidences for expanding Maxwell’s equations to include media motion that could be time and even space dependent. Therefore, we have developed the expanded Maxwell’s equations for a mechano-driven media system (MEs-f-MDMS) by neglecting relativistic effect. This paper first presents the updated progresses made in the field. Second, we extensively investigated Faraday’s law of electromagnetic induction for a media system that moves with an acceleration. We concluded that the newly developed MEs-f-MDMS are required for describing the electrodynamics inside a media that has a finite size and volume and move with and even without acceleration. The classical Maxwell’s equations are to describe the electrodynamics in vacuum space when the media in the nearby move.

Magnetostrictive Vibration Harvester with a Multistage Amplifier and Its Application in Human Walking Energy Harvesting

In this paper, as a theoretical basis, a foot vibration harvester with a finite support mechanism is proposed based on the Villari effect of magnetostrictive materials and Faraday’s law of electromagnetic induction, where a rod-shaped Terfenol-D is used as a core element for energy conversion, and a multi-stage force amplification mechanism is used as a core mechanical structure. The purpose of the amplification mechanism is to amplify the input force provided to the Terfenol-D rod and increase the output electric power. Moreover, the amplification mechanism is designed based on the bridge amplification structure, microlever amplification structure, and wedge amplification mechanism. A mathematical model of the amplification mechanism was developed using the force analysis and unit stiffness matrix methods, and the size and structure were designed and optimized. The performed simulations yielded an output force amplification ratio of 18.04. Based on the optimization results, a prototype was fabricated, and experiments were conducted. Specifically, experiments on the effect of the bias magnetic field on the harvester’s harvesting capability were performed, and the operating characteristics were tested for one complete cycle. Moreover, the effects of the amplification mechanism and vibration harvester were tested for practical applications. The peak output voltage of the harvester was 397.5[Formula: see text]mV under 100 N excitation, and the output electrical power on a resistive load could reach 3.33[Formula: see text]mW. In the application of the human walking process, the voltage could reach a maximum value of 387.3[Formula: see text]mV. The results of the study initially prove that the designed vibration harvester can stably collect human walking vibration.

Real-Time Inspection in Detection Magnetic Flux Leakage by Deep Learning Integrated with Concentrating Non-Destructive Principle and Electromagnetic Induction

One of the most common techniques of pipeline inspection is magnetic flux leakage (MFL). It is a non-destructive testing (NDT) method that employs magnetic sensitive sensors to detect MFL of faults on pipelines' internal and external surfaces. This research proposed a novel technique in real-time detection of MFL with pattern recognition in non-destructive principle using deep learning architectures. Here, the MFL signal has been collected as a large data sequence which has to be trained and validated using neural networks. Initially, the MFL has been detected using Faraday's law of electromagnetic induction (EMI) which is induced with Z-filter in electromagnetic (EM) decomposition. The collected signal of MFL has been classified using convolutional neural network (CNN), and this classified signal has been recognized by the patterns based on their threshold of the signal. By extracting and analyzing magnetic properties of MFL for a signal, the quantitative MFL has exceeded their threshold value from detected signals. Damage indices based on the link between enveloped MFL signal and the threshold value, as well as a generic damage index for MFL technique, were used to strengthen the quantitative analysis.

PO186 / #872 SHORT TERM REDUCTION OF CHRONIC NEUROPATHIC PAIN AFTER HIGH-FREQUENCY REPETITIVE TRANSCRANIAL MAGNETIC STIMULATION (RTMS): E-POSTER VIEWING

Chronic neuropathic pain (CNP) is a debilitating condition that may affect up to 70% of the population, and severely impacts their quality of life. The effects of available treatments are very limited and most available options are considered ineffective with multiple side effects. There is a critical need to develop a new generation of therapies. Transcranial magnetic stimulation (TMS) is a non-invasive and painless brain stimulation technique that allows us to change brain excitability based on Faraday’s Law of Electromagnetic induction.

Recognition and Processing of Visual Information after Neuronavigated Transcranial Magnetic Stimulation Session

Background: Transcranial magnetic stimulation (TMS) is a method of noninvasive and painless stimulation of the nervous system, which is based on Faraday’s law of electromagnetic induction. Over the past twenty years, the TMS technique has been deployed as a tool for the diagnosis and therapy of neurodegenerative diseases, as well as in the treatment of mental disorders (e.g., depression). Methods: We tested the inhibitory effects of repetitive TMS (rTMS) on reaction times to militarily relevant visual stimuli amidst distractors and on accompanying blood oxygenation level dependent (BOLD) signal functional magnetic resonance imaging (fMRI) in 20 healthy people. rTMS was applied over the visual cortices, V1, on both hemispheres with the inhibitory theta burst paradigm with the intensity of 70% of the active motor threshold fMRI in 20 healthy people. Results: Analysis of the reaction time to visual stimuli after using TMS to the V1 visual cortex revealed an increase in the number of incorrect recognitions, and the reaction time was from 843 to 910 ms. In the subgroup of participants (n = 15), after the stimulation, there were significant reductions of BOLD signal in blood flow within V1 cortices. Conclusions: The studies of reaction times after the rTMS revealed the inhibitory effect of rTMS on the reaction times and recognition performance of significant (military) objects in the visual field.

Design of a V-Twin with Crank-Slider Mechanism Wind Energy Harvester Using Faraday’s Law of Electromagnetic Induction for Powering Small Scale Electronic Devices

The maintenance of wireless sensor networks involves challenges such as the periodic replacement of batteries or energy sources in remote locations that are often inaccessible. Therefore, onboard energy harvesting solutions can provide a viable alternative. Experimental energy harvesting from fluid flow, specifically from air flow, is typically restricted to a rotor and stator design or a model that strikes a piezoelectric. On the other hand, energy harvesting from mechanical vibrations routinely uses the linear motion of a magnet passing through a coil or vibrating piezoelectric elements. In this paper, we propose a novel V-twin harvester design that converts wind energy from a rotational input into the linear motion of a magnet inside a coil via a crank-slider mechanism. This design allows for high performance with a smoother voltage output when compared to a reference rotor/stator harvester design or piezoelectric method. At 0.5 Hz, a single crank-slider generated a voltage of 0.176 Vpp with an output power of 0.147 mW, whereas the reference harvester generated 0.14 mW at 1.0 Hz with a 0.432 Vpp. A single crank-slider operating at regulated frequencies of 0.5, 1, 2, and 3 Hz, with a stroke length of 50 mm and a generated continuous power of 0.147, 0.452, 2.00, and 4.48 mW, respectively. We found that under ambient wind speeds of 3.4 and 4.1 m/s the V-twin formation with the optimized configuration, in which the coils and loads were both connected in series, generated 27.0 and 42.2 mW, respectively.

Precise Positioning of Redundant Robot Motion Energy-Saving Control Based on Sensing Technology

In order to provide intelligent drinking water service for human beings, an intelligent indoor positioning water delivery system is proposed. The system can realize the functions of automatic filling water and so on. Based on the UP Squared processor, the system extends the UWB positioning Zigbee wireless transmission gyroscope manipulator and other functional modules. Based on the UP Squared processor, the system extends the UWB positioning Zigbee wireless transmission gyroscope manipulator and other functional modules. MPU6050 module was used to sense the rotation angle, and PID algorithm was used to control the rotation of redundant robot. The position of water cup is sensed based on current magnetic effect and electromagnetic induction law. Ultrasonic module is used to detect the rising height of the outlet and the water level in the cup. Several parameters of the system, such as orientation, distance adjustment, and power consumption, and the whole process of water delivery are tested through experiments. The experimental results show that the designed robot has a measurement accuracy of 1 cm, a total of static power of 5.35 W, and a total of dynamic power of 13.6 W. Conclusion. The system has the characteristics of accurate positioning, fast and smooth steering, and low power consumption, which can meet the technical requirements of practical application in indoor intelligent positioning water delivery.

Study on the effect of changing stator structure on wind permanent magnet eddy current heating device

With the development of new energy, the proportion of wind power in the global power production structure is increasing year by year, and it has broad development prospects. This article discusses a new type of wind-powered permanent magnet eddy current heating device, which converts excess wind energy into heat energy and stores it in a heat storage medium, so as to achieve the function of storing heat energy. Thermal energy can be directly supplied to users and can also be used for thermal power generation when the power supply is insufficient, which is of practical significance to alleviating the problems of energy shortage and large amount of wind curtailment. Based on the law of electromagnetic induction and eddy current phenomenon, this paper establishes a model of permanent magnet eddy current heating device, and then simulates and analyzes the permanent magnet eddy current heating device to improve the heating power and material utilization of the device. The focus is on the influence of stator groove type, the number of stator slots and the thickness of the stator on the heating power. Finally, the simulation analysis of the permanent magnet eddy current heating device before and after the optimization is carried out in MATLAB. The simulation results prove the effectiveness of the optimization.

Estimation of the effect of magnetic field on a memristive neuron

A cell's action potential can be induced by rapid pumping and changes in intracellular and extracellular ions, and a magnetic field is generated to regulate neural activity effectively. Stochastic propagation and diffusion of ions across the cell membrane can break the balance of ion concentration. An appropriate external stimulus can speed up the exchange of ions and then different firing modes in the neuron can be induced for energy release. An improved neuron model is proposed and suggested to explore the effect of the magnetic field from the physical aspect, which a memristive channel with locally active feature is added to the known Hodgkin-Huxley (HH) neuron model by connecting a memristor in parallel with the HH neural circuit. That is, the memristive channel current is equivalent to the induction current, and an additive magnetic flux variable is introduced into the HH model, and its evolution is guided by the law of electromagnetic induction and energy conversion. The induction current can modulate the excitability and the threshold for inducing distinct action potentials. The transition from different-type firing patterns is induced by modulating the inductive current. In addition, an external magnetic field from two sources is applied to estimate the mode transition and firing patterns by regulating the magnetic flux, which induces further changes in the neural activity of the neuron. The neuron keeps quiescent when two identical magnetic field sources are emitted at high frequency. While the neuron can be activated to generate continuous firing patterns when the two applied magnetic field sources show certain diversity in the frequency. The potential mechanism is that the frequency synthesized by the two stimuli is close to the intrinsic frequency of the neuron, and then bursting can be induced effectively.

Far distance measurement of electric current through infrared radiation

Ohm’s law and Electromagnetic Induction law are two fundamental laws used for the current measurement. However, these two methods require putting resistance into the circuit or magnetic sensor close to the line, which is dangerous when the wireline has high voltages. To improve the safety, this paper proposes a non-contact far distance current measurement method, which is in conjunction with a fuse-like radiant sensor made of metal foil and an infrared radiation (IR) camera, without any additional conjunction line. Nature behind that is a mathematical model based on another law, Joule Heating. The mathematical model unifies the alternating current (AC) and heat conduction equation in the dynamic process, quantitatively determines the relationship between the sinuous temperature variation and current amplitude along the wireline. Experiments verify that the proposed method can measure current with the relative error within ± 3.66 % in the range of 1.05–3.45Arms at power frequency (50 Hz) from 1 m away. Therefore, the proposed method has a bright future for electric current measurement of tour inspection, especially in high voltage transmission systems.

Enhanced variable reluctance energy harvesting for self-powered monitoring

With the rapid development of microelectronic technology, wireless sensor nodes have been widely used in rotational equipment for health condition monitoring. However, for many low-frequency applications, there still remains an open issue of harvesting sufficient electrical energy to provide long-term service. Therefore, in this paper an enhanced variable reluctance energy harvester (EVREH) is proposed for self-powered health monitoring under low-frequency rotation conditions. A periodic arrangement of magnets and teeth is employed to achieve frequency up-conversion for performance enhancement under a specific space constraint. In addition, the permeance of the air gap is calculated by the combined magnetic field division and substituting angle method, and the output model of the EVREH is derived for parametric analysis based on the law of electromagnetic induction. Simulations and experimental evaluations under a range of structural parameters are then carried out to verify the effectiveness of the proposed model and investigate the output performance of the proposed harvester. The experimental results indicate that the proposed energy harvester could produce a voltage of 8.7 V and a power of 726 mW for a rotational speed of 200 rpm, with a power density of 0.545 mW/(cm3∙Hz2). Moreover, a self-powered wireless sensing system based on the proposed energy harvester is demonstrated, obtaining a vibration spectrum of the rotating motor and stator which can determine the health state of the system during low rotational speeds. Therefore, this autonomous self-sensing experiment verifies the potential of the EVREH for self-powered monitoring in low-frequency rotation applications.