Analysis of circular shape distributed piezoelectric actuators

The over 9 million deaths in 2018, and 10 million in 2020, worldwide, due to cancer, indicates that the current standard of treatments is inadequate; there is an urgent and critical need for additional/alternate physical therapies. Towards this, electroporation-based chemotherapy, known as Electrochemotherapy is emerging. This involves application of high intensity, short duration pulses at the tumor site, which enhances the biopotential across the phospholipid bilayers of the cell plasma membrane and hence opens up pores for enhanced uptake. The electric field intensity and distribution is shaped by the electrode geometry, size, material and the tissue treated. In this research, we investigated the influence of different electrodes on the electric field intensity and distribution. For this purpose, platinum and surgical steel needle array hexagonal and pentagonal electrodes were used. ANSYS, the industry standard software that uses finite element method was used to study the electric field distribution, intensity and contour. Both, healthy tissue and tumor tissue were used to identify the electric field intensity and distribution using these various electrode configurations and materials, for unipolar and bipolar voltages were studied. The results indicate that the electric field distribution, both in magnitude and pattern is similar for both electrodes, for both configurations and materials, which is desired from the clinical aspect. The electric field intensities for the hexagonal and pentagonal needle electrodes were 1280V/cm and 1180V/cm respectively in the case of tumor tissue (correlating well with the desired level of 1200V/cm). They were 835V/cm and 843V/cm for these electrodes in the case of healthy tissues. The values were same in the case of bipotential and negative voltages too.

XLPE is widely used as an insulating material in electrical systems due to its excellent dielectric properties. However, the effectiveness and dependability of the insulation might be severely impacted by the existence of voids inside it. The objective of this research is to simulate the electric field intensity in an XLPE matrix under varying voltages (15 kV, 20 kV, and 25 kV), with a focus on assessing cable aging. The study aims to examine how void size and void location influence the electric field distribution within the XLPE material. Additionally, the research seeks to explore the impact of void presence on stress concentrations and the electric potential drop within the defect area. To achieve these objectives, the study utilizes COMSOL Multiphysics software and the Finite Element Method (FEM) for the simulations. The simulation process considers different void sizes and varying distances between voids and electrodes. The electric field distribution is analyzed under the different voltage conditions to observe the effects of voids on the electric field and potential drop. The study highlighted that void location significantly impacts electric field distribution, with voids positioned closer to high-voltage electrodes resulting in higher electric field intensities, while voids located farther away exhibit lower field intensities. Additionally, the comparison between the absence and presence of voids showed that voids create stress concentrations, resulting in a more drastic drop in electric potential within the void-defect area. The examination of void location on electric field intensity has revealed the significant impact of void positioning on the distribution of electric fields, emphasizing the importance of precise insulation design and void detection strategies.

Transcranial Magnetic Stimulation (TMS) treatments have been employed in hospitals. Conventional figure-8 coils can only stimulate a highly localized area, and it is difficult to stimulate specific points accurately without an infrared camera system that is large and expensive. To ease patients' burden, we suggest home treatment with a smaller driving circuit and a smaller positioning system that has an accuracy of approximately 5 mm; this is critical for figure-8 coils. Thus, a wide focus coil is required. In the present study, we propose a new coil named the double-D coil. The radius of side elements and the number of coil turns were defined based on scalar potential finite difference method simulations. The distribution and intensity of electric field were simulated based on finite element method. We also conducted the simulations using brain models constructed from MR images to evaluate its robustness against the coil positioning error. Finally, we developed the double-D coil by using a 3D printer and measured the magnetic flux density. The results show that the double-D coil induced an electric field in an expanded area. This was enough to be applied to a smaller positioning system and the intensity of the electric field was improved at more than 16 mm from the coil surface in the simulation. In the brain model from the MR image, the mean value of the electric field by the double-D coil was 1.2 times stronger than that of the figure-8 coil. The double-D coil created by a 3D printer induced a similar magnetic field to the simulation. That indicates the efficiency of the double-D coil at more than 20 mm from the coil surface.

Pulsed power equipment is often characterized by high energy density and field intensity. In the presence of strong electric field intensity, charge accumulation within insulators exacerbates electric field non-uniformity, leading to potential insulation breakdown, thereby posing a significant threat to the safe operation of pulsed power equipment. In this manuscript, we introduce nonlinear composite materials with field-dependent conductivity and permittivity to adaptively regulate the distribution of the pulsed electric field in insulation equipment. Finite-element modeling and analysis of the needle-plate electrodes and high-voltage bushing are carried out to comprehensively investigate the non-uniformity of the distribution of the electric field and the homogenization effect of various nonlinear materials in the presence of pulsed excitations of different timescales. Numerical results indicate that the involvement of nonlinear composite materials significantly improves the electric field distribution under pulse excitations. In addition, variations in the rising time of the pulses affect the maximum electric field intensity within the insulators considerably, but for pulses of nanosecond and microsecond scales, the tendencies are the opposite. Finally, via the simulations of the bushing, we illustrate that some measures proposed for improving the uniformity of the electric field under low frequencies, e.g., increasing the length of the electric field equalization layer and the distance of the underside of the electric field equalization layer from the grounding screen, are still effective for the homogenization of pulsed electric field.

Atmospheric electric field is closely related to the thunderstorm, climate change, air pollution and solar activity. The detection of atmospheric electric field altitude distribution on special terrain is of great significance for the research of atmospheric electricity. On 12 September 2020, the Honghu special team of Chinese Academy of Sciences mounted the atmospheric electric field instrument on the air sounding balloon, and carried out the detection experiment of the high distribution of atmospheric electric field in the Dachaidan area of Haixi Mongolian-Tibetan Autonomous Prefecture in Qinghai Province. This paper has introduced the electric field instrument, experimental process, experimental results and discussion. The convex part in the middle of the atmospheric electric field curve corresponds to the electric field instrument passing through the clouds. The curve was devided into three sections. These three sections were fitted respectifly. The results show that the main influencing factors of the atmospheric electric field at different altitudes are different, and their distribution laws are also different. In addition, charged clouds can make the overall intensity of the atmospheric electric field increased, while the altitude distribution of the atmospheric electric field in the charged cloud layer is still in accordance with the exponential law.

Based on electro-magneto-rheological (EMR) effect, this paper presents a novel micro machining method to form an instantaneous tiny-grinding wheel to polish the surface of optical glass, ceramic and other rigid-fragile materials under both electric and magnetic field. Experiments were conducted to reveal the synergistic effect of electrorheological and magnethorheological effect, and the effects of process parameters, such as intensity of electric field, intensity of magnetic field, working time, machining gap between the workpiece and the needle-like tool, on material removal rate of glass surface. Experimental results confirm the effectiveness of the micro machining technique with EMR effect-based tiny-grinding wheel and the machining efficiency under the combination of electric and magnetic field is much greater than the one under applied external electric or magnetic field. The material removal rate of workpiece is directly proportional to the intensity of external electric field and will maintain stable when the voltage of external electric field reaches 2000v, while the material removal rate is directly proportional to the intensity of external magnetic field. The material removal rate markedly descends with the increase of the machining gap. In addition, the working time is directly proportional to the amount of material removal of workpiece, but inversely proportional to material removal rate.

The atmospheric pressure plasma jets have been widely used in material modification and biomedicine. In this study, the electric field distribution and influencing factors of penetrating materials under atmospheric pressure plasma jet (APPJ) acting on different materials were systematically studied by electro-optical effect measurement technique. In the experiment, alumina ceramic, quartz glass, polystyrene plastic and pig ear back skin were used as media, and the effects of the medium equivalent capacitance, applied voltage parameters (amplitude, frequency, pulse width), gas environment and secondary discharge on the electric field intensity were investigated. The results show that the dielectric equivalent capacitance is positively correlated with the electric field strength, and the peak electric field increases significantly with the increase of dielectric constant. The increase of applied voltage amplitude significantly enhances the electric field intensity, and as the frequency increases, the peak electric field intensity first increases and then decreases. Pulse width modulates electric field persistence that shorter pulses accelerate field decay, whereas longer pulses maintain field intensity throughout their duration. In addition, the existence of secondary discharge significantly changes the time evolution characteristics of the electric field, and the intensity of the reverse electric field is closely related to the equivalent capacitance of the medium.

This research is conducted to analyze the efficiency of dielectric heating by increasing the input ports which are to be symmetrically model on the electrode plate. This analysis is considering of the electric field distribution and intensity in dielectric loads. The electric fields are caused by the electric power on electrode plates of the input ports to improve the thermals temperatures and electric field distribution of dielectric loads. The dielectric loads are the grains and pests, the rice and rice weevils are the target dielectric materials. To investigate the heating predicted by the theoretical model, the electric field distribution and intensity are analyzed by using the finite difference time domain method. The results demonstrate that the efficiency of the dielectric heating exterminated pests and temperature of grains without losing the quality. The advantage of the method is being able to be utilized for the dielectric heating applications to pest control and control the appropriate temperature of the grains in the future.

The electric field distribution within a microwave plasma chemical vapor deposition (MPCVD) reactor determines the quality of synthetic diamonds. In this study, we aimed to facilitate diamond deposition for various demands by designing a rectangular MPCVD reactor that can balance and regulate the electric field intensity and uniformity in the deposition region. Establishing and utilizing a 3D numerical model, we analyzed the electromagnetic field and plasma distributions of three reactor candidates. One promising candidate was optimized and compared with two cylindrical cavities, each having a diameter equal to the width and diagonal length of the rectangular cavity, respectively. The optimized rectangular reactor combined the TM011, TM021, and TM031 modes, exhibited a high-intensity and uniform electric field in the deposition region without other hot-spot regions, and demonstrated high-density plasma and uniform gas distribution. Operating at 2.45 GHz, the reactor generated a maximum electric field intensity of 2 × 105 V/m, and the hydrogen plasma reached a maximum electron density of 5.9 × 1017 m−3 over an effective area of 4.0 × 103 mm2 at 5 kW power and 20 kPa pressure. These findings highlight the potential of the rectangular reactor design, which exhibits a novel microwave modes coupling mechanism, enabling redistribution of microwave energy, and achieves higher electric field intensity in the deposition region compared with traditional cylindrical reactors. The study emphasizes the significance of the rectangular reactor for the growth of demand-specific diamonds.

In this work, the conditional entropy (CE) and the method of surrogate data are applied on time series of electric field (EF) intensity to explore their degree of complexity and the possible presence of nonlinear dynamics. The time series were obtained during the wide-band cumulative EF intensity monitoring, performed by one sensor of the Serbian EMF RATEL monitoring system installed in the campus area of the University of Novi Sad, and are re-sampled at one sample per two hours over consecutive time epochs of one month duration. The field intensity measurements during the years 2019 and 2020 allowed us to explore the effects of mobility restrictions related to the COVID-19 pandemic on the patterns of complexity and nonlinearity underlying the EF dynamics. Using the kernel-based estimator of CE, which realizes the well-known Sample Entropy measure, and generating phase-randomized Fourier transform surrogate series, we highlight the presence of predictable but nonlinear EF dynamics associated to months of regular population mobility, while months with reduced human mobility result in more complex but linear EF patterns. In perspective, this analysis may serve to complement standard evaluation of EF intensity and variability, with implications ranging from safety assessment to optimization of sensor placement and social mobility analysis.

Electric field distribution and performance optimization of high-speed train cable terminal with internal defects

Epoxy resin insulators are widely used on the roof of high-speed trains. However, epoxy resin materials will produce air gaps during design, pouring and other operations. Air gaps are prone to partial discharge under high pressure, which threatens the safe operation of train-set. In this paper, the epoxy resin insulator on the roof of the train-set is taken as the research object, and the three-dimensional model of the epoxy resin insulator with air gap is made to simulate the electric field environment of 27.5kV on the roof epoxy resin insulator. The change of the maximum electric field intensity on the air gap surface when the air gap span, length and width change, and the influence of the change of air gap parameters on the electric field distribution near it are analyzed. The simulation results show that the change of air gap span, length and width seriously affects the surrounding electric field intensity. During the change of the air gap span, the electric field intensity on the air gap surface gradually increases with the increase of the span. When the air gap size changes, the maximum electric field intensity on the surface is 3.41 times that without defects.

Introduction: Tumor Treating Fields (TTFields) are electric fields that disrupt processes critical for cancer cell viability and tumor progression. They are generated by a portable medical device and delivered noninvasively to the tumor site via skin-placed arrays. TTFields therapy is approved for the treatment of recurrent and newly diagnosed glioblastoma as well as pleural mesothelioma. Recently, the randomized, pivotal (phase 3) LUNAR study (NCT02973789) demonstrated improved overall survival for TTFields therapy (150 kHz) delivered continuously until progression or intolerable toxicity together with an immune checkpoint inhibitor (ICI) or docetaxel (DTX) vs ICI/DTX alone in patients with metastatic non-small cell lung cancer following progression on or after platinum-based therapy. PANOVA-3 (NCT03377491) is an ongoing pivotal (phase 3), randomized, open-label study evaluating the safety and efficacy of TTFields therapy (150 kHz) together with nab-paclitaxel and gemcitabine for the treatment of patients with unresectable, locally advanced pancreatic adenocarcinoma. The effects of TTFields are dependent on several factors (i.e., intensity, frequency, and distribution) which may be affected by tissue composition/conductivity and array layout. Here, we evaluate guideline TTFields array layouts for TTFields delivery to the abdominal region at therapeutic intensities (∼1 V/cm [amplitude]) using simulation models with varying body mass index (BMI). Methods: Computerized phantom models (Ella, females with BMIs of 22, 26 and 30 kg/m2) were used to simulate the distribution of TTFields. Two different arrays sizes (small [13 disks] and large [20 disks]) were applied to the abdominal region of the models based on abdominal TTFields array layout guidelines. Region of interest (ROIs) included the left and right hypochondriac, left and right lumbar, epigastric, and umbilical regions. Simulations were performed using the Sim4Life platform v6.2.1.4910 (Zurich MedTech, Zurich, Switzerland). Electric field intensity distribution maps were generated for each model, and electric field intensity values across all ROIs in the abdomen were analyzed. Results: Electric field intensities were generally lower in the higher BMI model compared with the lower BMI models (field intensities across all ROIs were 1.60–2.57 V/cm for the 22 kg/m2 BMI model, 1.36–2.13 V/cm in the 26 kg/m2 BMI model and 1.35–1.97 V/cm in the 30 kg/m2 BMI model). However, all BMI models achieved TTFields intensities at therapeutic levels (∼1 V/cm) in all ROIs. Conclusions: Results from this simulation-based study demonstrate the feasibility of delivering TTFields at therapeutic intensities to patients with abdominal tumors regardless of their BMI when using abdominal guideline layouts. Citation Format: Ariel Naveh, Nadav Shapira. The effect of body mass index on Tumor Treating Fields (TTFields) intensity distribution in the abdomen: results of a simulation model study [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr A008.

The energized icing of composite insulators has been studied by the researchers around the world, but not much about the effects of electric field distribution on their icing and flashover performance. For this purpose, the ice accretion and flashover performance of 220 kV composite insulators with two shed configurations on occasions of different electric field distributions considering the effect of grading rings are analyzed in this paper. The test results indicate that the intensity and homogeneous distribution of electric field have positive effects on the appearance, density and weight of ice; the improvement of electric field distribution after installing grading ring has more effects than the icing characteristics, such as quality, density as well as appearance of ice, on flashover voltages of ice-covered composite insulators; the icing flashover voltages are increased by the improvement of electric field distribution and the increasing ranges of icing flashover voltage were relied on shed configuration. Icing accumulation patterns have less effect on flashover performance of composite insulators with alternatediameter or widely spaced shed configurations.

Uniform TNT growth on complex geometries, such as screw-threaded surfaces, is challenging due to non-uniform electric fields in anodization. This study examines TNT growth on screw threads and dental implants, intending to determine the impact of geometry on the electric field distribution using Finite Element Analysis (FEA). Simulation results showed that the electric field intensity was highly variable, with increased values on teeth and decreased values on the root and flank, causing nonuniform growth of TNTs. Experimental anodization coupled with Field-Emission Scanning Electron Microscopy (FESEM) affirmed the findings with shorter TNTs on the root and more stable growth on the teeth and flanks. TNT diameter correlated with applied DC voltage, while TNT length, with variations of 6 μm, was highly sensitive to the cathode design. To solve the problem, a new multicathode anodization cell was developed to produce a uniform field distribution. By adjustment of the cathode-to-anode (CA) area ratio, it was discovered that a CA of 1 yielded the optimal results, and this resulted in uniform TNT growth in all regions. Lower CAs (e.g., 0.5:1) resulted in low field strength and incomplete TNT growth, and high CAs (2:1) led to over-dissolution and structural damage. Optimization on actual dental implants using the CA 1 setup and two-stage anodization process yielded a more controlled TNT length and diameter. The final TNT morphology on the dental implant had TNT length variations of 0.4 μm with a 100 nm diameter. These results reveal the importance of the electric field uniformity in anodizing implants with complex geometries. The proposed multicathode design presents an efficient and scalable solution for uniform TNT layer deposition on dental implants and similar freeform curved surfaces.