Two-dimensional numerical study of an atmospheric pressure helium plasma jet with dual-power electrode

In this paper, the characteristics of an atmospheric pressure helium plasma jet generated by a dual-power electrode （DPE） configuration are investigated by using a two-dimensional fluid model. The effect of a needle electrode on the discharge is studied by comparing the results of the DPE configuration with those of the single ring electrode configuration. It is found that the existence of the needle leads to the generation of a helium plasma jet with a higher propagation velocity, higher species density, and larger discharge width. Furthermore, the influences of the needle radius and needle-to-ring discharge gap on the generation of a plasma jet are also studied. The simulation results indicate that the needle electrode has an evident influence on the plasma jet characteristics.

A Computational Study on the Discharge Characteristics of Atmospheric Dielectric Barrier Discharges at a Constant Power

The study on homogeneous DBDs at atmospheric pressure has attracted much attention for their advantages in applications. Tremendous work has been conducted both experimentally and numerically at a constant applied voltage or driving frequency. However the investigation of dielectric barrier discharges is still scarce for a constant power or power density. In this work, a new computational approach for DBDs is developed to explore atmospheric DBDs at a constant power based on a one-dimensional fluid model. The frequency and gap spacing effects on the atmospheric plasmas are systematically analyzed based on computational data. The computational results show that at a constant power both the current density and the amplitude of the applied voltage decrease, whereas the current pulse width increases, with increasing frequency. The simulation also indicates that as the gap spacing is raised with a fixed power and frequency, the current density and electron density increase initially, then reach their peak values, and then decrease, which means that there are maximum values for both of them. These results are significant for many industrial applications, as they can be used to optimize plasma devices of DBDs with the consideration of power consumption.

Power and Cross-Spectra for the Turbulent Atmospheric Motion and Transports in the Domain of Wave Number Frequency Space: Theoretical Aspects

The study of large-scale atmospheric turbulence and transport processes is of vital importance in the general circulation of the atmosphere. The governing equations of the power and cross-spectra for the atmospheric motion and transports in the domain of wave number frequency space have been derived. The contributions of the nonlinear interactions of the atmospheric waves in velocity and temperature fields to the conversion of kinetic and potential energies and to the meridional transports of angular momentum and sensible heat in the atmosphere have been discussed.

Korean Atmospheric Environmental Impact Assessment for Thermal Power Plant

Korea has adopted Environmental Impact Assessment (hereafter “EIA”) system for more than 3 decades. There are 74 big projects subject to EIA according to (Environmental Impact Assessment Law (No. 10892). For thermal power plant of which output is more than 10 MW, EIA must be done by proponents. To assess impact on atmospheric environment, proponents utilize air dispersion models and to minimize the adverse impact on air quality, state-of-the-art add-on control technology is applied.

Modeling the Dispersion and Atmospheric Mitigation of Pollutants in the Dibamba-Douala Thermal Power Plant

This work simulates the dispersion and atmospheric attenuation of pollutants from the Dibamba-Douala thermal power plant. The objective of this research is to study the dispersion of air pollutants and mitigate the impact of pollutants on the populations living around the power plant. The methodology used is as follows: the Gaussian model is used for the representation of the dispersion in the form of a plume, the finite difference method for digital resolution. Finally, dispersion charts are constructed which allow the heights of the chimneys to be fixed for which the concentrations of pollutants discharged comply with ambient air quality standards. The results obtained using the simulation made in the MATLAB software version 2016 show that, for a wind regime of 1.5 m/s;we have a predicted distance of 150 m at which the concentration is canceled out. Then, for the wind speed of 2 m/s;we had a predicted distance of 125 m and finally for a wind speed of 2.5 m/s;we observed the 120 m distance at which the concentration is canceled. In addition, for the same wind regimes, the attenuation of pollutants at ground level is obtained for a height of 60 m.

Electrical Characteristics of Dielectric-Barrier Discharges in Atmospheric Pressure Air Using a Power-Frequency Voltage Source

Dielectric-barrier discharges （DBDs） in atmospheric pressure air have been studied by using a power-frequency voltage source. In this paper the electrical characteristics of DBDs us- ing glass and alumina dielectrics have been investigated experimentally. According to the Lissajous figures of voltage-charges, it is discovered that the discharge power for an alumina dielectric is much higher than that for a glass dielectric at the same applied voltage. Also~ the voltage-current curves of the glass and alumina dielectrics confirm the fact that the dielectric barriers behave like semiconducting materials at certain applied voltages.

The Effect of Discharge Power on the Atmospheric Pressure Non-equilibrium Ar/O_2/TiCl_4 Plasma Deposition of TiO_2 Film

Deposition of TiO2 film from atmospheric pressure non-equilibrium Ar/O2/TiCl4 plasma was done to study the effect of discharge power during the film deposition process in this paper. TiO2 films with kinds of morphologies and controlled crystallization were deposited from mixtures of TiCl4 and O2 on quartz substrate by one step process. Scanning electron microscope (SEM) and transmission electron microscope (TEM) were used to analyze the morphology and crystallization of the deposited TiO2 films. It was found that the discharge power played a key role in the morphology and crystallization of the deposited TiO2 film whether the flow of TiCl4 was large or small. When the flow of TiCl4 was large, the deposited TiO2 film was amorphous particles at low discharge power and was multi-crystalline at high discharge power. When the flow of TiCl4 [JP2]was small, the deposited TiO2 film became more compact and the crystallization was enhanced as the discharge power increased . The dependence of the discharge current and the applied voltage with the discharge power indicated that it was a glow discharge. The gas temperature which increases with the discharge power is one of the main causes that affect the morphology and crystallization of the deposited film.

Polyoxometalates for continuous power generation by atmospheric humidity

Atmospheric humidity is a sustainable low-value energy widely existing in natural environment,which is a promising candidate to solve the noncontinuous and low efficiency of low-value energy power generation.Here the mono-substituted Dawson-type polyoxometalates are constructed to be highly dispersed organic ammonium-polyoxoanion clusters and are assembled into thin films power generators with micropores,working in atmospheric humidity.The optimal polyoxometalates generator with the thickness of 7.2μm and the area of 0.36 cm^(2) produces a voltage of 0.68 V and a current density of 19.5μA·cm^(-2) under simulated natural environment,and works continuously and stably under almost all-natural environments(humidity 10%–90%).The highly dispersed polyoxometalate nanoclusters can form microporous in polyoxometalate films to effectively absorb atmospheric humidity and spontaneously form distribution gradient of water,which is the structural basis of power generation.The continuous power generation may be maintained by the effective adsorption and utilization of H_(2)O,the huge electrostatic field of organic ammonium-polyoxoanion clusters,and the reasonably designed polyoxometalates containing inorganic small ions with high mobility.It is the first humidity generator designed with polyoxometalates,which may provide a new research direction for polyoxometalates in sustainable utilization of low-value energy.

Surface Treatment of PET Nonwovens with Atmospheric Plasma

In this study, polyethylene-terephthalate （PET） nonwovens are treated using an atmospheric plasma and the effects of the treatment time, treatment power and discharge distance on the ability of water-penetration into the nonwovens are investigated. The result indicates that the method can improve the wettability of PET nonwovens remarkably, but the aging decay of the sample＇s wettability is found to be notable as a function of the storage time after treatment due to the internal rotation of the single bond of surface macromolecules. As shown by SEM and XPS analysis, the etching and surface reaction are significant, and water-penetration weight is found to increase remarkably with the increasing power. This variation can be attributed to momentum transfer and enhanced higher-energy particle excitation.

Kinetics Characteristics and Bremsstrahlung of Argon DC Discharge Under Atmospheric Pressure

An improved self-consistent, multi-component, and one-dimensional plasma model for simulating atmospheric pressure argon glow discharge is presented. In the model, both the plasma hydrodynamics model and chemical model are considered. The numerical simulation is carried out for parallel-plate geometry with a separation of 0.06 cm. The results show that Ar＊ plays a major role in the discharge, which is mainly produced by ground state excitation reaction. The electron temperature reaches its maximum in the cathode sheath but maintains a low value （0.23 eV） in bulk plasma. Elastic collision is the dominant volumetric electron energy loss in atmosphere argon glow discharge, which is negligible in low pressure argon glow discharge. The metastable step-wise ionization is the main mechanism for electron production to sustain the discharge. However, the highest contribution to electron production rate is ground state ionization reaction. The bremsstrahlung power density is related to electric voltage. With the increase of the electric voltage, the bremsstrahlung power density increases, namely, the strength of ultraviolet radiation spectrum enhances in the cathode sheath.

Quantitative study of atmospheric effects in spaceborne InSAR measurements

Atmospheric effects on interferometric synthetic aperture radar(InSAR) measurements are quantitatively studied based on a tandem pair of SAR data and a month-long continuous GPS tracking data obtained at six stations. Differential atmospheric signals extracted from the SAR data for two selected areas show apparent power law characteristics. The RMS values of the signals are 2.04 and 3.66 rad respectively for the two areas. These differential delays can potentially cause in the two areas peak-to-peak deformation errors of 3.64 and 6.52cm, respectively, at the 95% confidence level and Gaussian distribution. The respective potential peak-to-peak DEM errors are 123 and 221 m. The GPS tropospheric total zenith delays estimate indicates that a peak-to-peak error of about 7.8cm can potentially be caused in a SAR interferogram with only 1 d interval at the 95% confidence level. The error increases to about 9.6cm for 10 d interval. The potential peak-to-peak DEM and deformation errors estimated from GPS total zenith delay measurements are however quite similar to those estimated from InSAR data. This provides us with a useful tool to pre-estimate the potential atmospheric effects in a SAR interferogram before we order the SAR images. Nevertheless, the results reveal that even in a small area the atmospheric delays can obscure centimetre level ground displacements and introduce a few hundred meters of errors to derived DEM.

Generation of Atmospheric Pressure Plasma by Repetitive Nanosecond Pulses in Air Using Water Electrodes

Dielectric barrier discharge （DBD） excitated by pulsed power is a promising method for producing nonthermal plasma at atmospheric pressure. Discharge characteristic in a DBD with salt water as electrodes by a home-made unipolar nanosecond-pulse power source is presented in this paper. The generator is capable of providing repetitive pulses with the voltage up to 30 kV and duration of 70 ns at a 300 Ω resistive load. Applied voltage and discharge current are measured under various experimental conditions. The DBD created between two liquid electrodes shows that the discharge is homogeneous and diffuse in the whole discharge regime, Spectra diagnosis is conducted by an optical emission spectroscopy. The air plasma has strong emission from nitrogen species below 400 nm, notably the nitrogen second positive system.

Analysis of Reflection Properties of High Power Microwave Propagation in Mixture-Atmosphere

A simple theoretical modeling is made to describe the reflection features of the high power microwave (HPM) in the mixture-atmosphere. The time-space dependent mixture-atmosphere is generated by ionization of the neutral molecules in atmosphere. Reflection will occur when HPM propagates in such mixture-atmosphere. The reflection characteristic of the HPM propagation in the mixture-atmosphere is investigated by FDTD numerical experiments in inhomogeneous medium, the influence on the reflection for different HPM parameters is concluded. An additional stability conditions for the FDTD difference scheme of the HPM mixture-atmosphere propagation model are presented.

考虑大气稳定度的典型复杂地形风场CFD模式

为评估中国典型复杂山地风资源,实现风资源的高效利用,结合雷诺时均的k-ε两方程模型、大气粗糙度壁面函数和热浮力作用,提出能模拟不稳定、中性和稳定状态复杂地形风场特性的大气CFD模式,并针对湍流参数、大气粗糙度对风速廓线的影响进行参数化研究。采用两种方式驱动CFD模式:一种是通过来流上游的实测风速廓线驱动CFD模式,一种是通过WRF模式输出风速廓线和温度廓线驱动CFD模式。利用山西神池南桦山丘陵山地测风数据进行大气CFD模式验证,通过WRF-CFD耦合仿真研究山地公里级范围热浮力作用对风场的影响,详细对比不同热浮力作用下的大气CFD模式仿真精度。结果表明大气CFD模式能准确地模拟不同稳定度状态下的山区大气风环境,但对于不稳定状态下山后风场的模拟能力稍差。

不同“碳达峰”情景下火电行业环境效益预测及分析

为了研究“碳达峰”目标下我国火电的环境效益,从我国“十四五”和2035年远景目标出发,基于Verhulst灰色模型建立环境效益目标预测模型,设置6种情景,达峰时间依次为2025—2030年;计算并分析不同情景下CO_(2)、SO_(2)、NO_(x)和颗粒物(particulate matter,PM)排放量和减排量。结果表明,所有情景中,2021年至达峰年,CO_(2)、SO_(2)、NO_(x)和PM的排放量逐渐上升,达峰后直到2035年快速下降。CO_(2)的减排量在2035年前出现正值的情景是2025年达峰和2026年达峰。2025年达峰时,2032—2035年的CO_(2)减排累积量为4.31亿t;2026年达峰时,2034年和2035年的CO_(2)减排累积量为0.77亿t。SO_(2)、NO_(x)和PM的减排量在2021~2035年都为正值。2025年达峰时,2021—2035年SO_(2)、NO_(x)和PM的减排累积量分别是1276.73、933.02和268.36万t,达峰年推迟将会导致2021—2035年SO_(2)、NO_(x)和PM的减排累积量逐渐减少。最后,根据研究结果提出了火电环境效益目标实现路径。

内陆复杂风电场风速垂直外推模型研究

陆上风能资源评估中风电机组的轮毂高度大于测风塔高度,忽略大气稳定度影响与地表粗糙度变化,风切变指数受地面地形和地貌因素的影响,且在外推到轮毂高度处时,风速难以精确预测。综合考虑了Monin Obukhov相似理论与动力学粗糙度最小二乘法计算模型,建立一种基于大气热稳定性在中性条件下的拟合方法。首先,评估了风切变指数在不同地点的空间分布和与大气稳定度变化之间的相关影响;其次,以2个不同地貌下陆上风电场的实测数据为基础,与常用的综合切变外推轮毂高度风速的计算方案相比较,结果表明:风切变指数日变化与大气稳定性日变化存在一定的相关性,新型外推风速模型计算方法能更加准确地评估目标高度风速的垂直分布变化。

典型风电场地形大气稳定度对风机出力的影响

[目的]分析了大气稳定度对风机出力的影响,为提高计算流体动力学(Computational Fluid Dynamics,CFD)风能资源模拟精度提供技术参考。[方法]选取立于平坦和复杂山地两类典型地形上的两座测风塔不同高度的风速、气温、气压等观测数据,使用莫宁-奥布霍夫长度法分别计算两座测风塔所在区域的大气稳定度,参照Irwin大气稳定分类标准对稳定度计算结果分类,再根据分类结果进行两座测风塔轮毂高度处出力分析。[结果]结果表明:在近地面层,复杂山地大气热效应造成的表层垂直混合作用更为明显,造成的大气不稳定性较为强烈,但垂直混合作用不充分;复杂山地大气稳定度对风机出力的影响大于平坦地形,其不确定性更强。[结论]在进行CFD风电场流体建模时需要考虑大气稳定度的影响,特别是超低风速复杂山地场址条件下,大气稳定度的评估对风机选型及发电量仿真精度尤为重要。

安徽省电网用镀锌钢的大气腐蚀及其影响规律

为评估安徽省大气环境下电网镀锌钢构件的腐蚀状态,针对自然曝露1a、3a后的镀锌钢试样,利用SEM、EDS及XRD等表征手段开展腐蚀产物组成及其形貌测试,探讨其大气腐蚀机理;采用失重法获取镀锌钢试样的腐蚀速率,结合灰色关联分析,揭示主要环境因素对镀锌钢试样大气腐蚀速率的影响规律。结果表明,镀锌钢试样大气腐蚀产物为ZnO及少量的Zn_(5)(OH)_(6)(CO_(3))_(2)和Zn_(4)(OH)_(6)SO_(4);腐蚀层表面胞状凸起由层片状的Zn_(5)(OH)_(6)(CO_(3))_(2)、Zn_(4)(OH)_(6)SO_(4)构成,呈菊花状。腐蚀层结构致密,与镀锌层结合紧密,具有良好的保护性,镀锌钢腐蚀程度低。主要环境因素对安徽省域镀锌钢试样大气腐蚀速率影响程度排序为:温度>相对湿度>O_(3)>NO_(2)>PM_(2.5)>PM_(10)>SO_(2)。温度及大气相对湿度的影响较大,而SO_(2)的影响较小。

针对一次对流云降水反演大气垂直运动速度及雨滴谱

反演大气垂直速度和雨滴谱分布是研究云降水机制和云微物理信息的重要内容,对人工预报天气、干预天气都有重要意义。针对2021年8月29日安徽省内毫米波雷达探测到的一次对流云降水过程,处理毫米波雷达的功率谱数据并进行大气垂直速度和雨滴谱反演。在小粒子示踪法的基础上引入改进小粒子示踪法:选取有效云信号段中最小功率对应的谱点作为反演大气垂直速度的示踪物。首先,根据改进前后的小粒子示踪法分别从功率谱数据中反演大气垂直速度,并跟基数据反演大气速度的结果展开对比分析。进一步得到粒子在静止空气中的下落速度,根据现有粒子下落速度-粒子直径之间的经验公式计算反演粒子直径。研究表明:(1)采用改进后的小粒子示踪法反演大气垂直速度得到的结果比小粒子示踪法得到的结果更精确,在云层内部两者误差较大;(2)进一步得到粒子下落速度,结合探测时段的天气状况,得到的粒子速度与大气速度可很好地契合,跟对流云天气情况信息大致吻合;(3)粒子浓度是反演雨滴谱分布时需要注意的主要参数,云在快速发展过程中,内部粒子持续朝外部扩张,云内部的粒子浓度较小,云边界的粒子浓度反而较大。

数字关爱抑或媒介控制?老年人视角下智能手机使用中的数字鸿沟

文章以数字鸿沟理论的三个层次为分析框架,理解老年人对于数字设备接入、使用和效果的感知。通过家庭访谈研究发现,在智能手机接入方面,社会中弥散的边缘气氛预设了老年人对新技术较低的需求;在智能手机使用中,年轻人基于代际关系将永远在线气氛传递给老年人进而影响其媒介使用;在智能手机使用效果中,老年人的实际媒介使用效果处于流动变化中,与社会责任、性别关系等要素相关。研究认为,社会以一种看似关爱老年人的方式遮蔽了对老年人媒介使用的控制,老年人自身则受困于家庭资源和亲情需求,不断让渡自身权力。老年人需要从数字社会边缘回归社会中心,以真正弥合银色数字鸿沟。