Electromagnetic Power Research Articles

A Compact Slot-Loaded Antipodal Vivaldi Antenna for a Microwave Imaging System to Monitor Liver Microwave Thermal Ablation

This study presents the design and the experimental validation of a slot-loaded antipodal Vivaldi antenna. The intended use is in an array configuration for monitoring liver microwave thermal ablation by way of microwave imaging (MWI). To optimize electromagnetic power transfer to the human abdomen, the antenna was designed to operate in a coupling medium. The final design has overall dimensions of 40mm×65mm, and the working bandwidth goes from 600 MHz up to 3 GHz, with the possibility to operate at higher frequencies, also. The antenna proposed in this study shows the most compact aperture dimension, as compared with other antennas designed for biomedical applications, working within the same bandwidth. To experimentally evaluate the antenna performances, the coupling medium was realized, proposing a recipe made by low cost, and easy to provide and use, materials. In particular, a mixture of water, oil, dishwashing detergent, and guar gum was used. The realized material showed dielectric properties close to the target ones, proved stability on a 1-week time, and reproducibility against different realizations. The antenna’s measured S-parameters well agreed with the simulation result. When locating two antennas in close proximity, as in the MWI array configuration, the results showed good performances towards mutual coupling.

Development and Characterization of a Micromagnetic Alternative to Cochlear Implant Electrode Arrays.

To stimulate the auditory nerve, cochlear implants directly inject electrical current into surrounding tissue via an implanted electrode array. While many cochlear implant users achieve strong speech perception scores, there remains significant variability. Since cochlear implant electrode arrays are surrounded by a conductive fluid, perilymph, a spread of excitation occurs. The functionality of the cochlea is spatially dependent, and a wider area of excitation negatively affects the hearing of the user. Importantly, magnetic fields are unaffected by the material properties of biological components. To utilize the electromagnetic properties of the human ear, a microcoil array was developed. The microcoils are 4-turn solenoids with a 250- [Formula: see text] turn radius and a 31.75- [Formula: see text] wire radius, coated with Parylene-C. The efficient design was implemented to accelerate testing. The obtained results describe stimulation capabilities. Functionality was validated using a frequency response analyzer to measure how the generated electromagnetic power radiates in space. 99.8% power loss was observed over a 100- [Formula: see text] separation between a pair of identical microcoils. Obtained through finite-element modeling, the microcoils can be driven by a 60 mA, 5 kHz, sinusoidal input for 10 minutes before predicted inflammation. Rattay's activating function was calculated to evaluate the magnetic stimulation effect of external fields on target neurons. Combined with the frequency response analysis, magnitude and spatial effects of the generated potential is established. As a result, each microcoil requires a 400- [Formula: see text]-wide area for each independent stimulation channel, which is 84% narrower than a commercial cochlear array channel, thereby suggesting greater spatial selectivity.

Microwave hyperthermia with X band flexible hyperthermia applicator for bone and joint cancer treatment

The microwave hyperthermia technique is proposed for bone and joint cancer with a flexible hyperthermia applicator operating in the X-band. The proposed approach consists of two steps. First, EM focus analysis is performed to optimize the phase value of antenna array elements’ excitation properties to concentrate the electromagnetic power at the tumor position while keeping the electromagnetic power level in healthy tissues at minimum values. Second, thermal analysis is performed by optimizing the amplitude value of the antenna elements’ excitation properties to achieve the required temperature at the tumor location. The proposed treatment technique is tested in a realistic simulation environment. The results obtained for different bone and joint models using the optimization technique for the excitation properties confirm the applicability of the proposed treatment method. In addition, the wideband frequency simulations show that frequencies around 10.4 GHz are the optimum values for treating bone and joint cancer.

Research on cam frequency-increasing hybrid piezoelectric electromagnetic energy harvester with center symmetric structure

This paper proposes a cam frequency-increasing hybrid piezoelectric electromagnetic energy harvester with center symmetric structure (C-HEH). The use of the cam structure allows the harvester to increase the efficiency of energy harvester per unit time, while the center symmetric structure of the entire harvester allows for maximum energy output in a limited size. This paper studies the influence of the number of cam protrusions and the length of the cylindrical permanent magnet on the output voltage signal at different rotation speeds. When the number of cam protrusions is 3 and the length of the cylindrical magnet is 10 mm, the maximum peak-to-peak voltages of the piezoelectric and the electromagnetic power generation unit are 53.74 V and 3.16 V, respectively. The effective value power of the hybrid energy harvester can be obtained as 1.49 mW. A series of application experiments were carried out to verify the performance of the C-HEH. The hybrid energy harvester can easily light up 86 light-emitting diodes (LEDs) lights and make the scientific calculators work stably after rectification. These results demonstrate the giant prospect of piezoelectric-electromagnetic energy harvesters for supplying wireless sensor networks and low-power electronic devices.

On the Optimal Selection of Flux Barrier Reconfiguration for a Five-Phase Permanent Magnet Assisted Synchronous Reluctance Machine for Low-Torque Ripple Application

This paper aims to investigate the reconfigurations of rotor flux barriers for a five-phase Permanent Magnet Assisted Synchronous Reluctance Machine (PMASynRM). To precisely study the performance of the proposed configurations, a conventional PMASynRM with double-layer flux barriers is included in the study. Since the novel rotor schemes consume the same amount of rare-earth magnets, steel sheet materials, and copper wire, resulting in no extra manufacturing costs, the optimal reconfiguration should be determined, providing developed electromagnetic characteristics. Thus, all the proposed models are designed and analyzed under the same condition. The Lumped Parameter Model (LPM) is exported to the Finite Element Method (FEM) for precise analysis to reach developed torque and lower values of torque ripple. Based on the FEM results the model presenting the lowest torque fluctuations is selected as the optimal model and dynamically investigated. According to the results, in comparison with the conventional model, the introduced rotor designs provide a much lower value of torque fluctuations with a desirable amount of electromagnetic torque and power. In addition, the optimal model presents high values of power factor and efficiency, making it a vital alternative for low-torque ripple high-speed operations with no extra cost to the implementation process.

Experimental investigation of flow and exergy transfer characteristics in the air-cooled randomly packed particle bed based on second law analysis

Randomly packed particle beds (RPPB) are widely used in industry, and their internal flow and heat transfer characteristics have a significant impact on the energy efficiency of the overall system. Based on the second law of thermodynamics theory, the correlation equation to predict the exergy transfer coefficient (ETC), exergy transfer Nusselt number (Nuex) within the RPPB is developed, which can reflect temperature and pressure exergy transfer. It effectively reveals the relationship between the role of heat transfer and pressure loss. The experiments are then carried out using stainless-steel particles packed bed with an electric induction heating system to provide a uniform internal heat source. The ambient air is used as the test fluid to cool the heated particles. The pressure drops and forced convection heat transfer characteristics of air-cooled high-temperature particles are investigated. The experiments are performed for flows with modified Reynolds number Redh in the range of 811–6810. The effects of cooling air inlet velocity (ua,in) and electromagnetic induction heating power (Qe) on the experimental results are investigated under different particle sizes (dp = 6 and 8 mm). The results show that when dp and Qe are constant, the overall Nuex decreases exponentially with increasing Redh, and even becomes negative. It means that the heat gain of the air through the RPPB is lower than the pressure loss. The critical Redh are 2650 and 5300 when dp = 6 and 8 mm, respectively. At fixed dp and ua,in, Nuex,T decrease linearly with the increase of Redh. In the case of low Qe, the exergy transfer between the particles and air is mainly based on pressure exergy transfer. As the Qe increases, the temperature exergy transfer gradually increases and dominates, and Nuex shifts from negative to positive. This study delves deeper into the forced convective heat transfer process in RPPB, comprehensively considering the effects of heat transfer and pressure loss.

Analysis of specific absorption rate and heat transfer in human head due to mobile phones

The human body absorbs a particular proportion of radiation when introduced to an electromagnetic field. The proportion of radio repeat energy burned-through in a unit mass of a human body when introduced to a radio frequency electromagnetic field is known as the Specific Absorption Rate and is alluded to as SAR. The position and bearing of the human body concerning the wellspring of the radiation impact the SAR regard. The sort of wellspring of the RF energy moreover impacts the SAR regard. This paper-based on how Mobile phones and there are arranged while simultaneously using them contribute and impact the value of SAR. Moreover, it is seen that SAR contributed by mobile phones is higher than other RF sources like Bluetooth and Wi-Fi Devices. This is a result of the way that the yield power transmitted by cells is higher than Bluetooth and Wi-Fi contraptions. As SAR is the proportion of electromagnetic power held over a specific volume of tissue, it is directly comparative with the strength of the electromagnetic field. Consequently, cells have higher Specific Absorption Rates when diverged from Bluetooth and Wi-Fi devices. SAR spatially shows up at the midpoint of over 1 g or 10 g of human tissue. Maxwell's field conditions in time–space are used to register the SAR movement in the human head. Charged particles gain energy and falter when electromagnetic radiation is the event on the issue. The energy gained could either be immediately reradiated and appear as scattered, reflected, or sent radiation or it may get into minuscule developments inside the matter, accomplishing warm concordance and setting out a decent establishment for itself as atomic power in the material. Temperature assessed over 1 g of tissue is higher when appeared differently in relation to 10 g volume of tissue. Muscle and blood have the temperature rise lower than the skin on account of skin significance. It is seen that when the significance of invasion grows SAR reduction and thusly temperature lessens.

Recovery of impact-damaged carbon fiber–reinforced composites using induction heating

Carbon fiber–reinforced composites (CFRCs) have been used extensively in structural applications within the aerospace and automotive manufacturing industries. However, several other applications have been recognized. These take advantage of the additional properties of CFRCs, which lead to providing better performance for structures. However, in their service environment, these CFRCs are inevitably susceptible to impact damage from multiple sources, and they must be able to recover from impacts to meet structural requirements. This study directs an experimental investigation of using induction heating (IH) for an impact-damaged CFRC. Here, IH process parameters, including the effects of electromagnetic frequency and generator power on the recovery of impact-damaged CFRC, have been analyzed. The anisotropic conductivity characteristics and the relationship between the drop-weight impact depth and conductivity of CFRC garnered much attention. This paper also offers the electromagnetic properties of CFRC for various applications. In this study, CFRC cured samples were obtained from Cetex® TC1200 PEEK, AS4 145 gsm, 16 unidirectional plies. Three variants of CFRC samples were tested: undamaged samples; samples with impact damage introduced in the center by a drop-weight impact test, according to the ASTM D7136/7136M standard; and samples with drop-weight impact damage recovered using the IH system. This work presents the results of the tensile strength of CFRC samples to assess the comparison of undamaged samples, samples damaged after the drop-weight impact test, and samples recovered after the drop-weight impact test. IH is appropriate for the recovery of impact-damaged CFRC samples, aiding in the conversion of electromagnetic energy to heat in order to generate mechanisms on components to recover the impact-damaged CFRC samples. Experimental results show that the impact-damaged area of the recovered CFRC samples is 37.0% less than that of damaged CFRC samples, and tensile strength results also improved after the impact-damaged CFRC samples were recovered. These results show that the IH method can effectively improve the impact damage performance of CFRC. The outcome of this study is promising for use in many applications, especially in the aerospace and automotive industries.

A Non-Invasive Millimetre-Wave Radar Sensor for Automated Behavioural Tracking in Precision Farming-Application to Sheep Husbandry.

The automated quantification of the behaviour of freely moving animals is increasingly needed in applied ethology. State-of-the-art approaches often require tags to identify animals, high computational power for data collection and processing, and are sensitive to environmental conditions, which limits their large-scale utilization, for instance in genetic selection programs of animal breeding. Here we introduce a new automated tracking system based on millimetre-wave radars for real time robust and high precision monitoring of untagged animals. In contrast to conventional video tracking systems, radar tracking requires low processing power, is independent on light variations and has more accurate estimations of animal positions due to a lower misdetection rate. To validate our approach, we monitored the movements of 58 sheep in a standard indoor behavioural test used for assessing social motivation. We derived new estimators from the radar data that can be used to improve the behavioural phenotyping of the sheep. We then showed how radars can be used for movement tracking at larger spatial scales, in the field, by adjusting operating frequency and radiated electromagnetic power. Millimetre-wave radars thus hold considerable promises precision farming through high-throughput recording of the behaviour of untagged animals in different types of environments.

Nonlinear Varying-Network Magnetic Circuit Analysis of Consequent-Pole Permanent-Magnet Motor for Electric Vehicles

To conserve rare earth resources, consequent-pole permanent-magnet (CPPM) machine has been studied, which employs iron-pole to replace half PM poles. Meanwhile, to increase flux-weakening ability, hybrid excitation CPPM machine with three-dimensional (3-D) flux flow has been proposed. Considering finite element method (FEM) is time-consuming, for the analysis of the CPPM machine, this paper presents a nonlinear varying-network magnetic circuit (NVNMC), which can analytically calculate the corresponding electromagnetic performances. The key is to separate the model of CPPM machine into different elements reasonably; thus, the reluctances and magnetomotive force (MMF) sources in each element can be deduced. While taking into account magnetic saturation in the iron region, the proposed NVNMC method can accurately predict the 3-D magnetic field distribution, hence determining the corresponding back-electromotive force and electromagnetic power. Apart from providing fast calculation, this analytical method can provide physical insight on how to optimize the design parameters of this CPPM machine. Finally, the accuracy of the proposed model is verified by comparing the analytical results with the results obtained by using FEM. As a result, with so many desired attributes, this method can be employed for machine initial optimization to achieve higher power density.

Fabrication of an Electrostatic Actuated Dielectric Mirror With Free-Standing Layers of Polymer

Common materials used in dielectric mirrors are inorganic and rigid such that their optical properties cannot be modified. Here, we developed a method to fabricate a dielectric mirror with free-standing flexible layers that can be actuated by applying an electrostatic force or air pressure between the top and bottom ones. The membranes are sequentially compressed by reducing the structure reflectance by eliminating the air layers, where reflectance is the total electromagnetic power reflected divided in the incident one. A potential bias is applied between the layers of up to 30 V and an actuation time is shown to be less than 4.1 ms, recorded with a camera at 240 frames/s. Mirrors with length and width of up to 230 μm each were achieved with three polymer/air layers. The polymer free-standing layers thickness ranged from 840 to 1240 nm and the air gaps from 140 to 400 nm. The small gaps and the large length of the mirrors allow fast actuation with relatively low voltages. The mirrors can be designed to reflect specific colors of the visual spectrum with potential application for color reflective displays.

Particle-in-Cell Algorithm-Based Computation of Time-Dependent-Multimode Behavior of 42-GHz Gyrotron

The analysis of the multimode behavior of the interaction cavity for 42-GHz gyrotron is presented here. The in-house developed codes single-mode cold cavity solver (SMCCS) and GYCAD and commercial particle-in-cell (PIC) simulator MAGIC are used in the design and analysis of 42-GHz gyrotron cavity. SMCCS is used for the calculation of cold cavity parameters such as <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Q$ </tex-math></inline-formula> factor, resonant frequency, and the axial electric field profile, which are further used in the beam–wave interaction computation. The PIC code is used here for the parametric optimization and time-dependent-multimode beam–wave interaction simulations of the interaction cavity. The mode purity in terms of the electromagnetic power in individual modes is also calculated using the data generated in the beam–wave interaction simulations. The single-mode analysis of the cavity is also performed using the analytical code GYCAD based on the generalized nonlinear theory. The results obtained by the PIC simulator and GYCAD are discussed and compared here. The analysis of the electron beam misalignment, which may occur due to the radial shifting or tilting of the different components during the fabrication of the device, is also performed and the effects on the efficiency, mode competition, and mode stability are discussed in detail.

Design and Analysis of a Novel Linear Oscillating Actuator with Dual Stator Rectangular Geometry

This paper proposes a new design of a linear oscillating actuator (LOA) with rectangular topology of stator and mover. The shape of a permanent magnet (PM) has a major impact on cost, mechanical strength and generation of magnetic flux density. This design uses rectangular PMs that are relatively cheaper than tubular PMs. Proposed LOA operates on single phase AC loading source. All the design parameters are optimized by using parametric sweep and the response of the LOA in terms of thrust force is compared. The Electromagnetic (EM) force received by the mover is investigated at various mover positions as well as at different values of the current. Motor constant is examined toward both directions of the force. Resonance phenomena is analyzed using input and output power of the LOA, which is the unique advantage of the LOA. Compared to the conventional LOA designs, the output parameters of the LOA, such as EM force, stroke, operating frequency and power, show great improvement with regards of volume of the proposed LOA. This topology shows significant development in terms of thrust force, motor constant, easy manufacturing and cost. Moreover, range of the stroke of proposed LOA is feasible for linear refrigeration system.

Modeling Microwave Heating and Drying of Lignocellulosic Foams through Coupled Electromagnetic and Heat Transfer Analysis

Microwave drying of suspensions of lignocellulosic fibers has the potential to produce porous foam materials that can replace materials such as expanded polystyrene, but the design and control of this drying method are not well understood. The main objective of this study was to develop a microwave drying model capable of predicting moisture loss regardless of the shape and microwave power input. A microwave heating model was developed by coupling electromagnetic and heat transfer physics using a commercial finite element code. The modeling results predicted heating time behavior consistent with experimental results as influenced by electromagnetic fields, waveguide size and microwave power absorption. The microwave heating modeling accurately predicted average temperature increase for 100 cm3 water domain at 360 and 840 W microwave power inputs. By dividing the energy absorption by the heat of vaporization, the amount of water evaporation in a specific time increment was predicted leading to a novel method to predict drying. Using this method, the best time increments, and other parameters were determined to predict drying. This novel method predicts the time to dry cellulose foams for a range of sample shapes, parameters, material parameters. The model was in agreement with the experimental results.

Investigation of the Polycrystalline Silicon PV Cell Efficiency in 3D Approximation versus Electromagnetic Field under Monochromatic Illumination

This manuscript is about the electric output of the silicon (Si) photovoltaic (PV) cell versus the electromagnetic field of a radio wave and a monochromatic illumination in three-dimensional (3D) assumptions. The polarisation direction of the electromagnetic wave and power density are fixed. The electromagnetic wave is provided by electromagnetic emission sources such as the telecommunication, radio, or TV antennas. A PV system is installed in the vicinity of an electromagnetic emission source. The current produced by the PV cell is sensitive to electromagnetic field increase more than the electric voltage. The electromagnetic field causes the decomposition of the current into two components which are a transferred current and a leakage current. The transferred component provides the transmitted current to the external load while the leakage component gives the loss of the carrier charge into the junction. Consequently, this decomposition of the current shares the electric power in transferred electric power and leakage electric power. The transferred electric power is obtained only in the intermediate circuit, and the maximum power point (MPP) shifts to the short circuit situation as the junction dynamic velocity becomes the greatest. However, the leakage electric power corresponds to a loss of the minority carrier’s charge in the junction during the crossing of the junction. This loss causes a Joule heating effect of the junction. The heating of the junction causes the quality degradation of the PV cell mainly due to the electric component. The solar illumination wavelength is presenting the inversion phenomenon with the maximum of the electrical outputs of the silicon PV cell of around 0.70 μm which provides the greatest conversion efficiency. This value has been chosen for the modelling of the radio wave influence. Hence, the conversion efficiency increases when the PV system is far away from the electromagnetic emission source. PV system installation in the vicinity of an electromagnetic emission source is not advised.

Electromagnetic radiation detection using cantilever-based photoacoustic effect: A method for realizing power detectors with broad spectral sensitivity and large dynamic range

A sensitive photoacoustic detection approach employing a silicon cantilever is investigated for power measurement of electromagnetic radiation. The technique which is actuated by pressure waves generated through radiation-induced heat depicts high sensitivity for a considerably large spectral range from 325 nm to 1523 nm. The implemented method shows linear response in the measurement of radiation power from 15 nW to 6 mW demonstrating a dynamic range of almost six orders of magnitude. A numerical model has been developed to analyze and optimize the measurement sensitivity. The model allows studying different dimensions of the cantilever which is one of the key components of the radiation detection process. The numerical results are in good agreement with experimental results. The electromagnetic power detection technique shows future potential for industrial applications and scientific studies.

Research on the High Reliable Electromagnetic Stirring Power Supply

A reconstructed topology with fault diagnosis and fault-tolerant control strategy of the two-phase quadrature power supply of an electromagnetic stirring system are proposed to improve the reliability of the system. First, if the back stage inverter is faulty, the topology will be reconstructed after the diagnosed fault. The reconstructed topology with the fault diagnosis can be applied twice. Additionally, a fault pulse reset method is proposed to form a fault-tolerant control strategy, for which the high-reliability electromagnetic stirring power supply does not need to switch the control algorithm before and after the failure. The reliability of the electromagnetic stirring power supply is improved greatly. Finally, simulations and experiments verify the correctness of the electromagnetic stirring power supply fault diagnosis algorithm, reconstruction topology, and its fault-tolerant control strategy proposed in this paper.

Method for calculating the resistance of an asynchronous squirrel cage motor according to passport data and estimation of its error

A simpler method is proposed for determining the resistances of an induction motor (total inductive resistance, active resistance of the stator and reduced active resistance of the rotor) according to reference data. Three algebraic equations are obtained from the equations of reactive power dissipation and electromagnetic power in the nominal mode and the equation of electromagnetic power in the critical mode: the first is relative to three resistances, the second is the equation of the dependence of the active resistance of the stator relative to the total inductive resistance, and the third is the active resistance of the rotor relative to the total inductive resistance. An iterative method is proposed for solving this system of equations, which gives a small error already at the second step of the calculations.&#x0D; When assessing the error of the method, the specified values ​​of the electromagnetic power and the multiplicity of the maximum torque were used, which are expressed relative to the reference resistances of the control motors. An estimate is given of the total error from the imperfection of the method and the discrepancy between the reference values ​​of the multiplicity of the maximum torque and power on the motor shaft with their refined values ​​calculated from the resistances from the reference book.&#x0D; Based on the calculated resistances in the nominal mode, the dependences of the active and inductive resistances of the motor are constructed using an accurate and approximate method.

Сравнение энергетической эффективности трехфазных линейных индукционных машин поперечного и продольного поля

The paper presents the results of energy efficiency and traction evaluation of linear induction machines for with molten aluminum recycling furnaces. Ansys Maxwell software was used for the synthesis of 3D parametric models of electromagnetic fields for a large air gap furnace. Interchangeable modules of three-phase transverse and longitudinal field inductors were used as a subsystem of a parametric model. Both inductor models include invertor low frequency power supply. Transverse and longitudinal field inductors have been designed with similarity principles. A stationary electromagnetic mode and power parameters has been modeled without taking melt hydrodynamics into account. Linear induction transverse-field machines have demonstrated higher efficiency.

A novel dynamic integral sliding mode control for power electronic converters.

The key characteristics of the sliding mode control (SMC) are the ability to manage unmodeled dynamics with rapid response and the inherent robustness of parametric differences, making it an appropriate choice for the control of power electronic converters. However, its drawback of changing switching frequency causes critical electro-magnetic compatibility and switching power loss issues. This paper addresses the problem by proposing a dynamic integral sliding mode control for power converters having fixed switching frequency. A special hardware test rig is developed and tested under unregulated 12.5-22.5 V input and 30 V output. The experimental findings indicate excellent controller efficiency under wide range of loads and uncertain input voltage conditions. In addition, the findings indicate that the closed-loop system is robust to sudden differences in load conditions. This technique provides an improvement of % in the rise time, % in the settling time and % in robustness of the controller as compared to conventional controllers. Furthermore, the comparison with the existing fixed-frequency sliding mode control techniques is presented in a tabular form.