配电系统高压熔断器熔断的原因及应对措施

配电系统发生单相接地故障,引发高压熔断器熔断,从铁磁谐振产生过电压和电容在接地过程中充放电产生低频饱和电流两方面分析得出,导致配电系统高压熔断器熔断的主要原因有二:一是由于系统发生单相接地故障时,引发铁磁谐振产生过电压,最终导致高压熔断器熔断;二是当配电线路长度较长时,单相接地故障恢复后的电容放电,其产生的低频饱和电流过大造成高压熔断器熔断。     

Analysis of quinolones by voltage-assisted liquid-phase microextraction combined with LC-MS

The method of liquid-phase microextraction assisted with voltage was developed and applied on determination of quinolones in water sample in this study. Both of the reproducibility and extraction time were improved with the aid of applying voltage. Four analytes in neutral state such as cinoxacin, oxolinic acid, nalidixic acid, and flumequine were extracted from a sample solution at pH 2.0, through a polypropylene hollow fiber which was immobilized with 2-octanone, and then into a 25 μL of the acceptor phase of 40 mM borate buffer at pH 10.0 by applying voltage of 100 V. Subsequently, the acceptor solution was directly subjected to analysis by LC-MS. The performance of the method for four quinolones was also evaluated. Linearity was obtained in the range of 1.0-25.0 ng/mL with R(2) > 0.996. Limits of detection were below 0.6 ng/mL, and recoveries of water sample were ranged from 90.8 to 109.6%.     

Graphs of given degree and diameter obtained as abelian lifts of dipoles

We derive an upper bound on the number of vertices in regular graphs of given degree and diameter arising as regular coverings of dipoles over abelian groups.     

Vortex dynamics in two-dimensional Josephson junction arrays with asymmetrically bimodulated potential

On the basis of resistively-shunted junction dynamics, we study vortex dynamics in two-dimensional Josephson junction arrays with asymmetrically single and bimodulated periodic pinning potential for the full range of vortex density f. The ratchet effect occurring at a certain range of temperature, current, and f, is observed in our simulation. We explain the microscopic behavior behind this effect by analyzing the vortex distribution and interaction. The reversal of the ratchet effect can be observed at several f values for a small driven current. This effect is stronger when the asymmetric potential is simultaneously introduced in two directions.     

脉冲变压器锥形高压绕组电压分布实验研究

 对脉冲变压器锥形高压绕组进行了脉宽为1 μs,500 ns及100 ns三种不同脉宽的单脉冲实验,研究了不同输入条件下绕组中的电压分布特性,比较了空心、加内铁芯和加内外铁芯三种不同结构绕组中的对地电压及匝间电压的分布曲线。实验结果表明：在高频冲击电压条件下,脉冲变压器锥形高压绕组中的电压呈现非线性分布且存在明显的振荡过程,导致绕组首端的电压梯度增大,伴随脉宽减小电压波形发生明显畸变,冲击电压以波的形式在绕组中传播,从而引起匝间电压按照正弦规律起伏变化,匝间电压的极值通常出现在绕组首末端,加入铁芯有助于抑制电压谐振但同时增大了匝间电压。     

基于ANEP染料荧光光谱迁移的单波长心脏光学标测系统

近几年来,光学标测技术已经成为心脏电生理研究中一种非常重要的手段。它利用对嵌在细胞膜上的电压敏感染料随着膜电位变化而产生的荧光光谱迁移进行成像,来进行心律失常与电击除颤等电生理研究。文章测量了常用的电压敏感染料di-4-ANEPPS的荧光光谱,并根据该染料的光谱迁移,设计了一套包括一个通用CCD相机的单波长光学标测系统,可以达到较高的时空分辨率。记录心肌细胞中的电兴奋传导过程,从而可以为今后国内心律失常作用机制的研究工作提供一个有力的工具。     

555定时器构成的单稳态触发器的一种实用电路

以555定时器构成的单稳态触发器这一典型电路为基础自制一种实用测试器，较详细的分析了该器件的工作原理、耦合方式、使用方法。     

Semi-Metallic Superionic Layers Suppressing Voltage Fading of Li-Rich Layered Oxide Towards Superior-Stable Li-Ion Batteries

Li-rich layered oxides (LRLOs) with greater specific capacity density are constrained by voltage attenuation and inferior rate performance because of irreversible oxygen release, metal dissolving and poor lithium-ion transport capacity. Herein, a simple surface modification is designed to solve the performance degradation and structural collapse of LRLOs. Combining experiments with density functional theory (DFT) calculations, a semi-metallic LiMn₂O₄-like structure (LMO) with spin-polarized conducting electrons, is introduced to the surface of the cathode restrains the activated surficial lattice oxygen ions by its stable oxygen vacancies. Additionally, Ni doping results in a fast-ion conductor Li_0.8Nb_0.96Ni_0.2O₃ structure (LNO) with lowered lithium ions diffusion barrier, which is tightly conjugating to substrate and synergistically reinforces the Li diffusion path through the cathode-electrolyte interphase. Moreover, Mn dissolution is successfully relieved due to the decrease in Mn concentration in the coating layers. As a result, the modified material (LRLO@LMO@LNO) exhibits an ultra-high discharge capacity of 120.4 mAh g⁻¹ even at 10 C with a very small discharge voltage attenuation of 313 mV after 600 cycles (0.52 mV per cycle) at 1 C. Undoubtedly, this method discloses a simple and effective approach to promote the practical utilization of high-energy-density.     

聚3-己基噻吩：非富勒烯太阳能电池中的量子效率损失和电压损失

From the industrial perspective, poly(3-hexylthiophene) (P3HT) is one of the most attractive donor materials in organic photovoltaics. The large bandgap in P3HT makes it particularly promising for efficient indoor light harvesting, a unique advantage of organic photovoltaic (PV) devices, and this has started to gain considerable attention in the field of PV technology. In addition, the up-scalability and long material stability associated with the simple chemical structure make P3HT one of the most promising materials for the mass production of organic solar cells. However, the solar cells based on P3HT has a low power conversion efficiency (PCE), which is less than 11%, mainly due to significant voltage losses. In this study, we identified the origin of the high quantum efficiency and voltage losses in the P3HT: non-fullerene based solar cells, and we proposed a strategy to reduce the losses. More specifically, we observed that: 1) the non-radiative decay rate of the charge transfer (CT) states formed at the donor–acceptor interfaces was much higher for the P3HT: non-fullerene solar cells than that for the P3HT: fullerene solar cells, which was the main reason for the more severely limited photovoltage; 2) the origin of the high non-radiative decay rate in the P3HT: non-fullerene solar cell could be ascribed to the short packing distance between the P3HT and non-fullerene acceptor molecules at the donor–acceptor interfaces (DA distance), which is a rarely studied interfacial structural property, highly important in determining the decay rate of CT states; 3) the lower voltage loss in the state-of-the-art P3HT solar cell based on the 2, 2'-((12, 13-bis(2-butyldecyl)-3, 9-diundecyl-12, 13-dihydro-[1, 2, 5]-thiadiazolo[3, 4-e]thieno[2', 3': 4', 5']thieno[2', 3': 4, 5]p-yrolo[3, 2-g]thieno[2', 3': 4, 5]thieno[3, 2-b]indole-2, 10-diyl)bis(methanelylidene))bis(5, 6-dichloro-1H-indene-1, 3(2H)-dion-e) (ZY-4Cl) acceptor could be associated with the better alignment of the energy levels of the active materials and the longer DA distance, compared to those based on the commonly used acceptors. However, the DA distance was still very short, limiting the device voltage. Thus, improving the performance of the P3HT based solar cells requires a further increase in the DA distance. Our findings are expected to pave the way for breaking the performance bottleneck of the P3HT based solar cells.     

不对称故障下考虑故障时间的储能变流器动态电压支撑策略研究

电网发生不对称故障会造成公共连接电压（Point of Common Coupling，PCC）跌落、储能变流器（Power Conversion System，PCS）输出电流幅值增大等不利影响，严重时可能引起PCS切机.针对上述问题，提出了一种不对称故障下的PCC电压动态支撑策略.首先，分析了不对称故障下PCS的运行特性，得到了电压支撑方程；然后，根据并网标准划分了故障穿越运行区域，基于电压支撑方程和故障穿越运行区域设计了PCC电压动态支撑方案；同时对PCS输出电流幅值进行限制，在保证电压支撑效果和容量充足的情况下，进一步对负序电压进行抑制；最后，在Matlab/Simulink中验证了所提策略的有效性.