The characteristics of negative corona discharge and radio interference at different altitudes based on coaxial wire-cylinder gap

The corona discharge from transmission lines in high-altitude areas is more severe than at lower altitudes. The radio interference caused thereby is a key factor to be considered when designing transmission lines. To study the influence of altitude on negative corona characteristics, an experimental platform comprising a movable small corona cage was established: experiments were conducted at four altitudes in the range of 1120-4320 m, and data on the corona current pulse and radio interference level of 0.8-mm diameter fine copper wire under different negative voltages were collected. The experimental results show that the average amplitude, repetition frequency and average current of the corona current pulse increase with increasing altitude. The dispersion of pulse amplitude increases with increase in altitude, while the randomness of the pulse interval decreases continuously. Taking the average current as an intermediate variable,the relationship between radio interference level and altitude is obtained. The result of this research has some significance for understanding the corona discharge characteristics of ultra-highvoltage lines.

Electromagnetic Ion Beam Instability in the Solar Corona

Remote-sensing measurements indicate that heavy ions in the corona undergo an anisotropic and mass-charge dependent energization.A popular explanation to this phenomenon is the damping of the Alfven/ion cyclotron waves.In this paper,we propose that the ion beam instability can be an important source of the Alfven/ion cyclotron waves,and we study the excitation of the ion beam instability in the corona at the heliocentric distance~3R_(⊙)and the corresponding energy transfer process therein ba sed on plasma kinetic theory.The results indicate that the existence of the motionless heavy ions inhibits the ion beam instability.However,the anisotropic beams of heavy ions promote the excitation of the ion beam instability.Besides,the existence ofαbeams can provide a second energy source for exciting beam instability.However,when both the proton beam and the a beam reach the instability excitation threshold,the proton beam driven instability excites preferentially.Moreover,the excitation threshold of the Alfven/ion cyclotron instability driven by ion beam is of the local Alfven speed or even less in the corona.

Observation of Standing Slow Magneto-acoustic Waves in a Flaring Active Region Corona Loop

Intensity fluctuations are frequently observed in different regions and structures of the solar corona.These fluctuations may be caused by magneto-hydrodynamic(MHD)waves in coronal plasma.MHD waves are prime candidates for the dynamics,energy transfer,and anomalous temperature of the solar corona.In this paper,analysis is conducted on intensity and temperature fluctuations along the active region coronal loop(NOAA AR 13599)near solar flares.The intensity and temperature as functions of time and distance along the loop are extracted using images captured by the Atmospheric Imaging Assembly(AIA)instrument onboard the Solar Dynamics Observatory(SDO)space telescope.To observe and comprehend the causes of intensity and temperature fluctuations,after conducting initial processing,and applying spatial and temporal frequency filters to data,enhanced distance-time maps of these variables are drawn.The space-time maps of intensities show standing oscillations at wavelengths of 171,193,and 211A with greater precision and clarity than earlier findings.The amplitude of these standing oscillations(waves)decreases and increases over time.The average values of the oscillation period,damping time,damping quality,projected wavelength,and projected phase speed of standing intensity oscillations are in the range of 15-18 minutes,24-31 minutes,1.46″-2″,132″-134″,and 81-100 km s^(-1),respectively.Also,the differential emission measure peak temperature values along the loop are found in the range of 0.51-3.98 MK,using six AIA passbands,including 94,131,171,193,211,and 335?.Based on the values of oscillation periods,phase speeds,damping time,and damping quality,it is inferred that the fluctuations in intensity are related to standing slow magneto-acoustic waves with weak damping.

Non-thermal atmospheric-pressure positive pulsating corona discharge in degradation of textile dye Reactive Blue 19 enhanced by Bi_(2)O_(3) catalyst

In this work,monoclinic Bi_(2)O_(3) was applied for the first time,to the best of our knowledge,as a catalyst in the process of dye degradation by a non-thermal atmospheric-pressure positive pulsating corona discharge.The research focused on the interaction of the plasma-generated species and the catalyst,as well as the role of the catalyst in the degradation process.Plasma decomposition of the anthraquinone reactive dye Reactive Blue 19(RB 19) was performed in a selfmade reactor system.Bi_(2)O_(3) was prepared by electrodeposition followed by thermal treatment,and characterized by x-ray diffraction,scanning electron microscopy and energy-dispersive xray techniques.It was observed that the catalyst promoted decomposition of plasma-generated H_(2)O_(2) into ·OH radicals,the principal dye-degrading reagent,which further attacked the dye molecules.The catalyst improved the decolorization rate by 2.5 times,the energy yield by 93.4%and total organic carbon removal by 7.1%.Excitation of the catalyst mostly occurred through strikes by plasma-generated reactive ions and radical species from the air,accelerated by the electric field,as well as by fast electrons with an energy of up to 15 eV generated by the streamers reaching the liquid surface.These strikes transferred the energy to the catalyst and created the electrons and holes,which further reacted with H_(2)O_(2) and water,producing ·OH radicals.This was indentified as the primary role of the catalyst in this process.Decolorization reactions followed pseudo first-order kinetics.Production of H_(2)O_(2) and the dye degradation rate increased with increase in the input voltage.The optimal catalyst dose was 500 mg·dm^(-3).The decolorization rate was a little lower in river water compared with that in deionized water due to the side reactions of ·OH radicals with organic matter and inorganic ions dissolved in the river water.

End-to-end computational design for an EUV solar corona multispectral imager with stray light suppression

An extreme ultraviolet solar corona multispectral imager can allow direct observation of high temperature coronal plasma,which is related to solar flares,coronal mass ejections and other significant coronal activities.This manuscript proposes a novel end-to-end computational design method for an extreme ultraviolet(EUV)solar corona multispectral imager operating at wavelengths near 100 nm,including a stray light suppression design and computational image recovery.To suppress the strong stray light from the solar disk,an outer opto-mechanical structure is designed to protect the imaging component of the system.Considering the low reflectivity(less than 70%)and strong-scattering(roughness)of existing extreme ultraviolet optical elements,the imaging component comprises only a primary mirror and a curved grating.A Lyot aperture is used to further suppress any residual stray light.Finally,a deep learning computational imaging method is used to correct the individual multi-wavelength images from the original recorded multi-slit data.In results and data,this can achieve a far-field angular resolution below 7",and spectral resolution below 0.05 nm.The field of view is±3 R_(☉)along the multi-slit moving direction,where R☉represents the radius of the solar disk.The ratio of the corona's stray light intensity to the solar center's irradiation intensity is less than 10-6 at the circle of 1.3 R_(☉).

Corona渲染技术在室内效果图仿真制作中的应用教学——以“教研室办公空间”效果图制作为例

Corona是一款建筑可视化渲染器,可作为插件集成在3ds Max中,它渲染设置简单,可在浮动视口开启交互式渲染并实时观察渲染结果,可以渲染出照片级写实的室内效果图。以“教研室办公空间”Corona渲染为例,基于3ds Max通过硬装材质赋予、硬装场景灯光设置、硬装场景摄影机创建及视口设置,完成软装和渲染输出,从而阐明Corona渲染器在室内设计项目、室内设计专业教学中的应用,为其他室内效果图仿真提供技术参考。

Comprehensive and deep profiling of the plasma proteome with protein corona on zeolite NaY

Proteomic characterization of plasma is critical for the development of novel pharmacodynamic biomarkers.However,the vast dynamic range renders the profiling of proteomes extremely challenging.Here,we synthesized zeolite NaY and developed a simple and rapid method to achieve comprehensive and deep profiling of the plasma proteome using the plasma protein corona formed on zeolite NaY.Specifically,zeolite NaY and plasma were co-incubated to form plasma protein corona on zeolite NaY(NaY-PPC),followed by conventional protein identification using liquid chromatography-tandem mass spectrometry.NaY was able to significantly enhance the detection of low-abundance plasma proteins,minimizing the“masking”effect caused by high-abundance proteins.The relative abundance of middleand low-abundance proteins increased substantially from 2.54%to 54.41%,and the top 20 highabundance proteins decreased from 83.63%to 25.77%.Notably,our method can quantify approximately 4000 plasma proteins with sensitivity up to pg/mL,compared to only about 600 proteins identified from untreated plasma samples.A pilot study based on plasma samples from 30 lung adenocarcinoma patients and 15 healthy subjects demonstrated that our method could successfully distinguish between healthy and disease states.In summary,this work provides an advantageous tool for the exploration of plasma proteomics and its translational applications.

Study on the interaction mechanism of double-blade corona discharge with a large discharge gap

Multi-source corona discharge is a commonly used method to generate more charged particles,but the interaction mechanism between multiple discharge sources,which largely determines the overall discharge effect,has still not been studied much.In this work,a large-space hybrid model based on a hydrodynamic model and ion-transport model is adopted to study the interaction mechanism between discharge sources.Specifically,the effects of the number of electrodes,voltage level,and electrode spacing on the discharge characteristics are studied by taking a double-blade electrode as an example.The calculation results show that,when multiple discharge electrodes operate simultaneously,the superimposed electric field includes multiple components from the electrodes,making the ion distribution and current different from that under a single-blade electrode.The larger the distance between discharge electrodes,the weaker the interaction.When the electrode spacing d is larger than 4 cm,the interaction can be ignored.The results can guide the design of large discharge gap array electrodes to achieve efficient discharge.

Traceability Technology of DC Electric Energy Metering for On-Site Inspection of Chargers

The on-site inspection of high-power DC chargers results in new DC high-current measurement and DC energy traceability system requirements.This paper studies the traceability technology of electric energy value for automotive high-power DC chargers,including:(1)the traceability method of the built-in DC energy meter and shunt of the charger;(2)precision DC high current and small precision DC voltage output and measurement technology.This paper designs a 0.1 mA∼600 A DC high current measurement system and proposes a 0.005 level DC powermeasurement traceability system.The uncertainty evaluation experiment of theDC powermeasurement calibration system and the high-power DC charger’s on-site calibration experiment results verify the method’s effectiveness and feasibility in this paper.The experimental results show that the combined standard uncertainty of the DC power metering verification system can be 0.0451%.

Improving plasma sterilization by constructing a plasma photocatalytic system with a needle array corona discharge and Au plasmonic nanocatalyst

Efficient sterilization by a plasma photocatalytic system(PPS)requires strong synergy between plasma and photocatalyst to inactivate microorganisms while suppressing the formation of secondary pollutants.Here,we report that a PPS constructed from a needle array corona discharge and Au/TiO2plasmonic nanocatalyst could remarkably improve the sterilization of Escherichia coli(E.coli)and alleviate formation of the discharge pollutant O3.At 6 kV,the combination of corona discharge and Au/TiO2achieves sterilization efficiency of 100%within an exposure time of 5 min.At 5 kV and an exposure time of 8 min,the presence of Au/TiO2improves sterilization efficiency of the corona discharge from 73%to 91%and reduces the O3concentration from 0.38 to 0.04 ppm,whereas the presence of TiO2reduces the sterilization efficiency and O3concentration to 66%and 0.17 ppm,respectively.The Au/TiO2in the PPS enables a uniform corona discharge,enhances the interaction between plasma,E.coli and nanocatalysts,and suppresses the formation of O3.Further,the Au/TiO2can be excited by ultraviolet-visible light emitted from the plasma to generate electron-hole pairs,and thus contributes to the formation of reactive radicals and the oxidative inactivation of E.coli.The PPS constructed from a needle array corona discharge and Au-based plasmonic nanocatalyst provides a promising approach for developing high-efficiency sterilization techniques.

Multi-point discharge model: study on corona discharge of double-ended needle in large space

Corona discharge, as a common means to obtain non-equilibrium plasma, can generally obtain high-concentration plasma by increasing discharge points to meet production needs. However,the existing numerical simulation models used to study multi-point corona discharge are all calculations of small-scale space models, which cannot obtain the distribution characteristics of plasma in large space. Based on our previous research, this paper proposes a hybrid model for studying the distribution of multi-point discharge plasma in large-scale spaces, which divides the computational domain and computes separately with the hydrodynamic model and the ion mobility model. The simulation results are verified by a needle–ball electrode device. Firstly, the electric field distribution and plasma distribution of the needle electrodes with single tip and double tips are compared and discussed. Secondly, the plasma distribution of the needle electrode with the double tip at different voltages is investigated. Both computational and experimental results indicate that the charged particle concentration and current of the needle electrode with double tips are both twice as high as those of the needle electrode with a single tip. This model can extend the computational area of the multi-point corona discharge finite element model to the sub-meter(25 cm) or meter level, which provides an effective means to study the plasma distribution generated by multiple discharge points in large-scale space.

Simulation analysis on microscopic discharge characteristics of the bipolar corona of a floating conductor

A floating conductor exhibits a bipolar corona phenomenon with microscopic discharge characteristics that are still unclear.In this study,a plasma simulation model of the bipolar corona with 108 chemical reaction equations is established by combining hydrodynamics and plasma chemical reactions.The evolution characteristics of electrons,positive ions,negative ions and neutral particles,as well as the distribution characteristics of space charges are analyzed,and the evolutionary flow of microscopic particles is summarized.The results indicate that the positive end of the bipolar corona initiates discharge before the negative end,but the plasma chemistry at the negative end is more vigorous.The electron generation rate can reach 1240 mol(m^(3) s)^(-1),and the dissipation rate can reach 34 mol(m^(3) s)^(-1).The positive ion swarm is dominated by O_(4)^(+),and the maximum generation rate can reach 440 mol((m^(3) s)^(-1).The negative ion swarm is mainly O_(2) and O_(4).The O_(2) content is approximately 1.5-3 times that of O_(4),and the maximum reaction rate can reach 51 mol(m^(3) s)^(-1).The final destination of neutral particles is an accumulation in the form of O_(3) and NO,and the amount of O3 produced is approximately 4-6 times that of NO.The positive end of the bipolar corona is dominated by positive space charges,which continue to develop and spread outwards in the form of a pulse wave.The negative end exhibits a space charge distribution structure of concentrated positive charges and diffused negative charges.The validity of the microscopic simulation analysis is verified by the macroscopic discharge phenomenon.

A network pharmacology approach to explore the mechanism of action of Yiqi Fumai lyophilized injection in the treatment of novel coronavirus disease

Background:Shengmai decoction,which has been included in the diagnosis and treatment of coronavirus disease 2019(COVID-19),is effective in the early treatment of patients with severe COVID-19.Yiqi Fumai lyophilized injection(YQFM)is a modern Chinese medicine preparation of the Shengmai decoction.The mechanism of its intervention at the molecular level in the severe stage of COVID-19 remains unclear.Therefore,it is necessary to investigate the mechanism of YQFM in the treatment of patients with severe COVID-19.Methods:The corresponding target genes of the main active ingredients in YQFM and COVID-19 were obtained by using multiple databases and literature retrieval.A protein-protein interaction network was constructed,and enrichment analysis of the target was performed using Cytoscape 3.8.1.Lastly,the docking of all the identified compounds with angiotensin-converting enzyme II was confirmed by applying molecular docking technology.Results:YQFM has anti-inflammatory effects on RAW267.4 macrophages.The main active compounds of YQFM are all effective anti-inflammatory agents,and these active compounds also show beneficial physiological functions,such as anti-oxidation,anti-bacterial,and anticancer activities.Gene Ontology analysis showed enrichment in the following pathways:lipopolysaccharides,interleukins,NF-kappa B,interleukin-2 and others,revealing that YQFM may play a role in the treatment of patients with severe COVID-19 through these pathways.Conclusion:YQFM has multicomponent and multitarget characteristics,and it could reduce lung injury by inhibiting inflammatory reactions,promoting antiviral activities,and regulating immunity,among other functions,to treat patients with severe COVID-19.

The current pulses characteristics of the negative corona discharge in SF_(6)/CF_(4)mixtures

This paper presents the results of numerical investigation of the current pulses characteristics in SF_(6)/CF_(4)mixtures for the negative point-plane corona discharge.The pressure and the temperature of gas mixtures are 0.4 MPa and 300 K,respectively.The CF_(4)content varies from20%to 80%.The 2D axisymmetric geometry with point-plane electrodes is investigated,and the three drift-diffusion equations are solved to predict the characteristics of the negative corona discharge.In addition,Poisson’s equation is coupled with the above three continuity equations to calculate the electric field.In order to calculate the electron impact coefficients,including the Townsend ionization and attachment coefficients,as well as the mobilities and diffusion coefficients for electrons,the two-term Boltzmann equation is solved.The characteristics of three ionic species at five stages of the first current pulse in 60%SF_(6)-40%CF_(4)and20%SF_(6)-80%CF_(4)mixtures are selected to discuss the development mechanism of current pulses.Moreover,the reduced electric field strengths at the corresponding time instants are presented to help understand the discharge process.The current waveform and the total number of three species are compared in all the cases to analyze the effects of the CF_(4)content on the discharge.The reduced electric field strength is also helpful in understanding the effects of CF_(4)content.When the CF_(4)content increases to 80%,the discharge is more intensive and the pulse frequency also increases.

Extraction and Analysis of Coronal High-temperature Components Based on Outlier Detection

The extraction of high-temperature regions in active regions(ARs)is an important means to help understand the mechanism of coronal heating.The important observational means of high-temperature radiation in ARs is the main emission line of Fe XVⅢin the 94?of the Atmospheric Imaging Assembly.However,the diagnostic algorithms for Fe XVⅢ,including the differential emission measure(DEM)and linear diagnostics proposed by Del based on the DEM,have been greatly limited for a long time,and the results obtained are different from the predictions.In this paper,we use the outlier detection method to establish the nonlinear correlation between 94?and 171,193,211?based on the former researches by others.A neural network based on 171,193,211?is constructed to replace the low-temperature emission lines in the ARs of 94?.The predicted results are regarded as the low-temperature components of 94?,and then the predicted results are subtracted from 94?to obtain the outlier component of 94?,or Fe XVⅢ.Then,the outlier components obtained by neural network are compared with the Fe XVⅢobtained by DEM and Del's method,and a high similarity is found,which proves the reliability of neural network to obtain the high-temperature components of ARs,but there are still many differences.In order to analyze the differences between the Fe XVⅢobtained by the three methods,we subtract the Fe XVⅢobtained by the DEM and Del's method from the Fe XVⅢobtained by the neural network to obtain the residual value,and compare it with the results of Fe XIV in the temperature range of 6.1-6.45 MK.It is found that there is a great similarity,which also shows that the Fe XVⅢobtained by DEM and Del's method still has a large low-temperature component dominated by Fe XIV,and the Fe XVⅢobtained by neural network is relatively pure.

Long-term corona behaviour and performance enhancing mechanism of SiC/epoxy nanocomposite in SF6 gas environment

Surface coating technology is an effective way to solve the interface insulation problem of DC GIS/GIL basin insulators, but the performance of the coating will change greatly, and the insulation strength will be completely lost, after long-term use in the extreme conditions of corona erosion. In this research, the multi-needle-plate electrode platform was constructed to explore the long-term use performance of Si C-doped nanocomposite exposed to corona discharge in SF6gas. Samples with a high Si C content have advantages in maintaining physical and chemical properties such as elemental composition, erosion depth, surface roughness and mass loss. The nanocomposite doped with 6 wt.% Si C has prominent surface insulation strength after long term exposure to corona, and the others are close to losing, or have completely lost,their insulating properties. Furthermore, the degradation mechanism of physicochemical properties of composite exposed to corona discharge was investigated with the proposed Reax FF MD model of energetic particles from SF6decomposition bombarding the epoxy surface. The reaction process of SF particles and F particles with the cross-linked epoxy resin, and the Si C nanoparticles providing shelter to the surrounding polymer and mitigating their suffering direct bombardment, have been established. The damage propagation depth, mass loss and surface roughness change of nanocomposite material bombarded by SF6decomposition products is reproduced in this simulation. Finally, the deterioration mechanism of insulation properties for the Si C-doped composite was elucidated with DFT analysis. The band gap of the molecule containing S drops directly from the initial 7.785 e V to 1.875 e V, which causes the deterioration of surface electric properties.

体质贴联合八段锦功法治疗气虚血瘀质新型冠状病毒感染恢复期患者的临床研究

[目的]观察气虚血瘀体质贴(简称体质贴)联合八段锦功法对气虚血瘀体质的新型冠状病毒感染恢复期患者的临床疗效。[方法]符合入选标准的43例新型冠状病毒感染恢复期患者分为试验组(21例)和对照组(22例)两组均在八段锦功法的基础上予体质贴辅助治疗,治疗12周后,观察两组患者治疗前后在中医症状积分量表、改良英国医学研究委员会呼吸困难量表(mMRC)、Borg自觉疲劳量表和匹兹堡睡眠问卷(PSQI)的评分改善情况。[结果]治疗12周后,与治疗前相比,试验组中医症状总积分明显降低(P<0.05);组间比较显示试验组总积分明显低于对照组(P<0.05)。在改善单项症状积分方面,两组与各自治疗前相比,试验组在改善肌肉疲劳、气短、胸闷、干咳的方面积分明显降低(P<0.05),对照组在改善肌肉疲劳、自汗盗汗方面的积分明显降低(P<0.05)。组间比较显示,试验组在改善肌肉疲劳、气短、心悸、胸闷、干咳上的积分较对照组积分明显降低(P<0.05)。mMRC量表评分结果显示,两组患者与治疗前相比,呼吸症状评分无明显变化(P>0.05)。Borg量表和PSQI量表结果显示,与治疗前相比,两组患者症状积分均明显下降(P<0.05),但组间比较差异无统计学意义(P>0.05)。[结论]体质贴联合八段锦康复治疗对气虚血瘀质新型冠状病毒感染恢复期患者的中医症状有改善作用,尤对肌肉疲劳、气短、心悸、胸闷、干咳改善明显,同时可以减轻患者疲劳,改善患者睡眠质量。

SiC改性提升聚酰亚胺薄膜直流耐电晕性能的机理

传统聚酰亚胺(PI)薄膜应用到更高电压等级设备中,易产生电晕放电甚至绝缘失效。为提升聚酰亚胺薄膜耐电晕能力,实验采取碳化硅(SiC)作为增强相对PI基体相进行改性,探究SiC改性对复合薄膜耐电晕特性的影响机理。实验结果表明,随着SiC含量增加,SiC/PI复合薄膜出现非线性电导特性并逐渐增强,其同步提升的浅深陷阱密度比与载流子迁移率促进了表面电荷消散速率的增加。同时,SiC提升了15 kV直流电压下薄膜的沿面闪络和击穿时间,其中质量分数25%SiC/PI复合薄膜较纯PI膜分别提升了416.28%和298.39%。这是因为增强的非线性电导率和表面电荷消散速率,有利于空间和表面电荷运输,减少电场畸变,从而提升复合薄膜的耐电晕能力。对电晕损伤薄膜的无损区、圆状白斑区和白色堆积区进行形貌观测,发现SiC颗粒会在等离子体碰撞下形成放电阻挡层,有效减少电晕对基体相的侵蚀,延长了复合薄膜的耐电晕时间。最后发现质量分数15%SiC/PI复合薄膜为综合耐电晕与力学特性下的最优选择。

基于GaN器件与磁集成技术的车载充电机实验平台研究

随着新能源汽车的普及,对车载充电机的要求越来越高。为了有效提升整机效率和功率密度,将GaN器件与磁集成技术应用于车载充电机,进行了实验平台研究。基于GaN器件设计了两级式车载充电机拓扑结构与外围电路,通过制作磁集成平面变压器,优化了CLLC变换器,完成了整机控制程序设计及2kW车载充电机实验样机搭建,并对样机进行了实验测试与波形分析。实验结果表明,实验样机具有良好的稳态特性与动态特性,整机功率因数在0.98以上,满载峰值效率达到95.22%。该平台能够帮助学生加深对电力电子技术的认识,掌握新型电力电子器件的特性及应用,锻炼实践操作能力,提高相关课程的教学质量。

基于电流检测电流注入的车载充电机EMI混合滤波器设计方法

针对目前车载充电机传统无源滤波器低频性能差的问题,在传统车载充电机无源滤波器的基础上加入有源反馈回路,提出了一种基于电流检测电流注入(CSCI)的车载充电机电磁干扰(EMI)混合滤波器设计方法,并给出了车载充电机混合滤波器结构及分析和反馈回路设计过程。实验结果表明,提出的新型EMI滤波器方案与已有车载充电机无源滤波器方案相比,传导测试和辐射测试结果都有大幅度的提升。