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The DC voltage ratio standard device is an important tool for calibrating DC voltage transformers. At the 1100 kV voltage level, an increase in electric field intensity will increase the local heat generated inside the device, affecting the accuracy of its measurement. Using a suitable grading ring can even out the electric field intensity and reduce the maximum field strength to improve its measurement accuracy. This article mainly optimizes the design of the grading-ring structure of the 1100 kV DC voltage ratio standard device. First, a finite-element model of the 1100 kV DC voltage ratio standard device was built based on ANSYS; the electric field distribution around the voltage divider was calculated and analyzed, and a data set was constructed based on the calculation results. Secondly, for the optimization of electric field strength, this article presents the design of the nation standard device neural network, which learns the relationship between the structural parameters of the toroidal core and the field strength under the PyTorch 1.8 deep learning framework. Due to the strong convergence performance, few parameters, and ease of implementation of the grey wolf optimization algorithm, this study selected this algorithm to optimize the structural parameters of the grading ring. Finally, simulation examples are established in Python for validation. The experimental results indicate that the maximum field strength of the grading ring decreased from 12,161.1348 V/cm to 10,009.2881 V/cm, a reduction of 17.69%. The optimized structural parameters of the grading ring effectively reduced the electric field intensity around the 1100 kV DC voltage proportional standard device, providing a reliable and practical design approach for the selection of the DC voltage ratio standard device. [ABSTRACT FROM AUTHOR]

In this study, the effects in terms of electric stress of composite voltages on a high-voltage disconnector were investigated. The main purpose of this study is to determine and evaluate the effects of the conditions that may occur in real working conditions but out of the type tests. As for the disconnector model, one phase of a center-break disconnector was considered. In order to examine the effects of composite voltages on high-voltage disconnectors, a model is defined in the Comsol Multiphysics program. Different types of voltages such as operating voltage, 50 Hz test voltage, lightning impulse voltage, and composite voltage, were applied to the 170 kV disconnector model separately. After applying a composite voltage consisting of power frequency voltage and lightning impulse voltage to the disconnector, electric potential and electric field distributions were obtained. It has been observed that the maximum electric potential and the maximum electric field strength values on the disconnector are higher when composite voltage is applied than when non-composite voltage is applied to the disconnector. It is observed that the intensity of the electric field lines increases near the contacts of the current-carrying arm and the main contacts of the disconnector. [ABSTRACT FROM AUTHOR]

Helical bilayer nanographenes (HBNGs) possess a unique structure and versatile properties, which are of great interest in experimental and theoretical research. This study applied an external electric field to regulate the electronic properties of the HBNG with a helicene moiety length of [9] ([9]HBNG). The direction of the external electric field (Fz) is the positive z-axis along the nanographenes. Intriguingly, the interplanar angle of [9]HBNG is regulated under the Fz. Furthermore, molecular electrostatic potential (ESP) maps demonstrate that the Fz regulates charge distribution effectively. Notably, when Fz = 100 × 10−4 a.u., the highest occupied molecular orbital (HOMO) is primarily located on the lower nanographene, while the lowest unoccupied molecular orbital (LUMO) is concentrated on the upper nanographene. Remarkably, the Fz induces a substantial increase in the βtot values, ranging from 6.53 × 102 (Fz = 0 a.u.) to 1.26 × 104 a.u. (Fz = 100 × 10−4 a.u.). This study presents an efficient approach for developing high-performance nonlinear optical (NLO) materials through the application of external electric fields, with potential applications in NLO switch devices. [ABSTRACT FROM AUTHOR]

Monitoring the electric potential (EP) response induced by coal deformation and rupture is essential to the safety of underground engineering under extreme load and stress wave disturbance conditions. In this study, the split Hopkinson pressure bar and EP acquisition systems were utilized for EP testing of coal under stress waves. The EP response under stress waves was investigated, the changes in accumulated charge caused by each stage of stress wave loading were analyzed, and the mechanism of EP signal generation is discussed. The results show that under stress waves, coal produces a significant EP signal, and the EP fluctuations correspond well to each stage of the stress wave. The EP and stress wave signals have a strong linear relationship when the stress wave is rising. During the descent of the stress wave, the EP decreases exponentially with time, showing a gradual decrease in the rate of EP decrease. The cumulative charge growth at each stage shows a "stable-surging-stable" change trend. Dislocation charged movement causes local polarization within the coal. Crack propagation leads to charge separation and free charge generation. These findings explain the mechanism of EP signal creation caused by stress waves. A mathematical model of the link between charge density and dynamic load stress is derived, indicating a strong positive correlation between the two parameters. The results of this research help to improve the reflection of coal seam stability through the EP response. [ABSTRACT FROM AUTHOR]

It is of great significance to study the optimum electric field strength of cold cathode Penning ion source (PIG), which is used on high yield neutron tube. The electric field in the ion source depends largely on the relationship between the voltage of anode and the thickness of anticathode. In the case of constant magnetic strength, the discharge modes of PIG can be distinguished by the relation between electric potential and pressure. Based on this relationship, we re-designed and optimized the PIG, and got the expected discharge mode. COMSOL was used to simulate the model, and a better extracted beam intensity (10.31 μ A) and a higher proton fraction (24 %) were obtained at an extracted voltage of −80 kV. It is estimated that the yield is higher under −80 kV than the previous design, which can reach 6 × 10 8 n / s. This study can provide reference for the development of high yield neutron tube ion sources. [ABSTRACT FROM AUTHOR]

Organic room-temperature phosphorescence materials have attracted extensive attention, but their development is limited by the stability and processibility. Herein, based on the on-line derivatization strategy, we report the urea-formaldehyde room-temperature phosphorescence materials which are constructed by polycondensation of aromatic diamines with urea and formaldehyde. Excitingly, urea-formaldehyde room-temperature phosphorescence materials achieve phosphor lifetime up to 3326 ms. There may be two ways to enhance phosphorescence performance, one is that the polycondensation of aromatic diamine with urea and formaldehyde promotes spin-orbit coupling, and another is that the imidazole derivatives derived from the condensation of aromatic o-diamine with formaldehyde maintains low levels of energy level difference and spin-orbit coupling, thus achieving ultra-long afterglow. Surprisingly, urea-formaldehyde room-temperature phosphorescence materials exhibit tunable phosphorescence emission in electrostatic field. Accordingly, 1,4-phenylenediamine, urea, and formaldehyde are copolymerized and self-assembled into phosphorescence microspheres with different electrostatic potential strengths. By mixing 1 wt% 1,4-phenylenediamine polycondensation microspheres with 1,4-phenylenediamine free microspheres, phosphor lifetime of the composite could be regulated from 27 ms to 123 ms. Moreover, vulcanization process enables precise shaping of urea-formaldehyde room-temperature phosphorescence materials. This work not only demonstrates that urea-formaldehyde room-temperature phosphorescence materials are promising candidates for organic phosphors, but also exhibits the phenomenon of electrostatically regulated phosphorescence. Organic room temperature phosphorescent materials have useful properties, but development can be limited by processing and stability challenges. Here, the authors report a derivatisation strategy for the preparation of room temperature phosphorescent materials responsive to an electrostatic field. [ABSTRACT FROM AUTHOR]

The electric potential stimulation of biological structures in aqueous environments is well-known to be a result of the gating of voltage-gated ion channels. Such voltage-gated ion channels are ubiquitous in the membranes of a wide variety of cells and they play central roles in a wide variety of sensing mechanisms and neuronal functions in biological systems. Experimental studies of ion-channel gating are frequently conducted using path-clamp techniques by placing a cumbersome external electrode in the vicinity of the extracellular side of the ion channel. Recently, it has been demonstrated that laser-induced polarization of nanoscale quantum dots can produce voltage sufficient to gate voltage-gated ion channels. This study specifically focuses on a new method of gating voltage-gated ion channels using 2D structures made of materials exhibiting large naturally occurring spontaneous polarizations, thereby eliminating the need for an external electrode or an illuminating laser. The work presents the use of self-polarizing semiconductor flakes, namely, 2H-SiC, ZnO, and GaN, to produce electric potential that is sufficient to gate voltage-gated ion channels when existing in proximity to it. [ABSTRACT FROM AUTHOR]

• The onset and termination electric potential to form the steady cone-jet electrospray increase as conductivity increasing. • The lower and upper limitation of liquid flowrate to form the steady cone-jet electrospray decrease as conductivity increases. • The varicose instability can transform into whipping instability as the electrical conductivity increasing. • The jet breakup instability transition mechanism is interpreted by theoretical analysis. • The whipping to similar micro-dripping instability can be observed for EG with higher conductivity. In present work, the effect of the electrical conductivity on the steady cone-jet electrospray are experimentally investigated, where the operating diagram and the jet breakup instability are extensively examined. A hemispherical tube is employed as spraying nozzle severed as high electric potential electrode in a needle-plated electrode configuration compared to the common and sheathed tubes. The cone-jet electrospray is visualized by a high-resolution camera and extensively analyzed offline. The aqueous solution in ethanol, Diethyleneglycol (DEG) and Ethylene glycol (EG) are atomized with varied electrical conductivity under different high electric potentials and flowrates. Experimental results indicate that the cone-jet electrospray can operate in the certain ranges of operating parameter for all types of capillaries. The operating diagram for the hemispherical tube is significantly broader than other tubes because of various electric field strength distribution. The onset electric potential to determine a steady cone-jet electrospray gradually increases and the termination value also increases as the electrical conductivity increases. The lower and upper flowrate to form a steady cone-jet electrospray also increase as the electrical conductivity increases. The jet breakup instability can transit from varicose to whipping due to low the reference flow rate as electrical conductivity increases, which is agreement with theoretical analysis. In particular, for EG, the transition from whipping to similar micro-dripping is observed as the electrical conductivity increases, while the transition also occurs as flowrate increases for EG with higher electrical conductivity. The increase in the electrical conductivity and flowrate elongates the cone due to EHD body force, which causes the electric field varying, further resulting in the difference in jet breakup instability. Moreover, the electrical conductivity also plays an important role in jet breakup length. The instability variation of jet with conductivity (DEG), q V =1000 nL/s, ϕ =8.00 kV (Hemispherical nozzle with D o =0.70mm); The variation with liquid flow rate of EG with higher conductivity (K =8.5 × 10−4 s/m, ϕ =10.20 kV, (Hemispherical nozzle with D o =0.70mm) [Display omitted] [ABSTRACT FROM AUTHOR]

Developing a fluidic platform that combines high-throughput with reconfigurability is essential for a wide range of cutting-edge applications, but achieving both capabilities simultaneously remains a significant challenge. Herein, we propose a novel and unique method for droplet manipulation via drawing surface charge graphics on electrode-free papers in a contactless way. We find that opposite charge graphics can be written and retained on the surface layer of porous insulating paper by a controlled charge depositing method. The retained charge graphics result in high-resolution patterning of electrostatic potential wells (EPWs) on the hydrophobic porous surface, allowing for digital and high-throughput droplet handling. Since the charge graphics can be written/projected dynamically and simultaneously in large areas, allowing for on-demand and real-time reconfiguration of EPWs, we are able to develop a charge-graphic fluidic platform with both high reconfigurability and high throughput. The advantages and application potential of the platform have been demonstrated in chemical detection and dynamically controllable fluidic networks. [ABSTRACT FROM AUTHOR]

This work aims to find how coupled energy per pulse influences the ability of a pulsed dielectric barrier discharge (DBD) plasma to ignite fuel-lean methane–air flow. For that, experiments are performed on a custom-built DBD flow reactor with a variable dielectric thickness and the discharge is operated by bursts of 10 ns duration pulses at 3 kHz repetition rate. With an increase in dielectric thickness, we observe that the coupled energy per pulse decreases even though applied voltage conditions are similar and so more pulses are required to ignite the lean mixture. Interestingly, we observe a significant increase in the minimum ignition energy (MIE) with an increase in the thickness beyond 3 mm. Moreover, the ignition kernel growth rate is much slower in the thicker dielectric cases even though total energy coupling per burst is similar. This phenomenon is investigated further by evaluating plasma parameters using electrical and optical diagnostics. Effective dielectric capacitance, discharge current, and voltage drop across the gas gap are derived from an equivalent circuit analysis, whereas plasma gas temperature and effective reduced electric field ( E / N) are estimated from optical emission spectroscopy. From these analyses, we conclude that a thicker dielectric limits the discharge current and so the plasma filament temperature. For more than 3 mm thick dielectric cases, the filament heating per pulse is too low to achieve strong enough plasma pulse-to-pulse coupling which eventually leads to higher MIE and slower ignition kernel growth rate or the inability to ignite at all. [ABSTRACT FROM AUTHOR]