低温等离子体灭活核糖核酸酶研究

该文主要探讨了低温等离子体技术在核糖核酸酶灭活方面的应用,分析了作用气体类型和等 离子体发生器结构对酶灭活性能的影响。实验结果表明,低温等离子体能够有效地灭活核糖核酸酶, 混有氧气或水汽的作用气体能够明显提高对酶的灭活能力,且悬浮式电极介质阻挡放电装置的灭活效 果优于表面介质阻挡放电装置。     

不同接线方式下介质阻挡放电的电气特性

为了研究不同接线方式对介质阻挡放电(DBD)电气特性的影响,降低表面放电等离子体的能耗,设计了一种新型微等离子体发生器,并对其在3种不同接线方式下的放电特性(包括Lissajous图形,放电功率、放电传输电荷、气隙电压等参数)进行了测量和比较.结果表明:有一个正面电极悬浮时,放电传输电荷和功率是两极接线方式下的一半,有效减少了放电能耗,并且此方式不等同于增大电极间距;背面电极悬浮时,起始放电电压和放电气隙电压都较高,但是放电传输电荷和放电功率均较小.     

DBD电路参数的在线测量的实现和研究

准确而简单地测量DBD型负载电气参数一直以来都是研究重点,传统的测量方法是通过重构李萨茹图形读取坐标点进行人工计算,费时费力,效率低下且操作复杂。基于李萨如图形测量原理,设计了DBD型负载电气参数在线测量控制系统。该系统通过采集DBD负载上的关键点数据,重新构建李萨如图形,通过软件计算介质阻挡电容、气隙电容、放电维持电压以及放电功率。该控制系统具有操作简单、安全、效率高、误差小和实时在线测量的优点,并通过实验验证了所提出在线测量系统的正确性。     

表面介质阻挡放电致动器的配置特性研究

沿面介质阻挡放电(SDBD)等离子体发生器在等离子体的产生中起着重要的作用.通过实验和仿真计算相结合的的方法,研究了大气压环境下等离子体发生器的结构对正弦波电源作用下放电的影响.结果表明:相同条件下,对称结构发生器电场强度最大,产生的等离子体分布在正面电极的两侧,等离子体层面积大,亮度高,但消耗功率较大;不对称结构发生器电场强度最低,产生的等离子体在正负电极处对称分布,整体看上去比较均匀;不对称结构底面电极封装之后正面电极处电场强度增强,等离子体分布在正面电极的一侧,亮度居中,底面电极附近的电场降低,抑制了低电极放电消耗能量,但均匀性最差.证明了等离子体激励器的封装抑制了底面电极的放电,同时降低了功耗.     

原煤脱硫模型仿真与实验研究

搭建了介质阻挡放电脱硫模型,在此基础上,通过仿真分析了影响脱硫放电效果的介质种类、介质厚度、气隙间距、电源电压、电源频率等因素,确定了各因素的最佳配合方案。对介质阻挡放电原煤脱硫实验数据进行了处理分析,发现实验结果与仿真结果基本一致。通过对比分析放电电流频谱图和Lissajous波形,做出进一步推论:加煤能提高放电功率,介质阻挡放电对原煤的脱硫效果体现在低次谐波上。     

煤介质阻挡放电脱硫的影响因素分析

依据介质阻挡放电理论,对原煤进行煤介质阻挡放电脱硫实验。实验结果表明,煤介质阻挡放电脱硫的影响因素与电极结构、介质成分和气隙距离等因素有关,如将介质放到放电间隙中间时脱硫的效果没有将介质直接放在放电极板上的脱硫效果好,加煤的情况下微放电的强度明显大于不加煤的微放电过程强度;脱硫效果呈"U"字型变化,由此推论,在一定的外界条件下,煤介质阻挡放电除硫有一个最佳的施加电压;随着电压的增加,放电脉冲的相位范围逐渐扩展。     

气体放电等离子体(DPP)极紫外光源研究进展

极紫外光刻技术被认为是下一代最有潜力的光刻技术,对推动集成电路发展具有重要作用。极紫外光源是极紫外光刻技术的源头,其技术水平直接制约了光刻技术的发展。气体放电等离子体极紫外光源结构简单,转换效率高,适合大规模工业应用,具备良好的应用前景。现有气体放电等离子体光源包括毛细管放电等离子体极紫外光源、激光辅助等离子体极紫外光源、等离子聚焦极紫外光源和中空阴极管放电等离子体极紫外光源等。近年来,极紫外光光刻技术工业化进展较快,该文对气体放电等离子体技术做了综述,掌握最新研究进展有助于推动我国相关领域研究。     

Ar等离子体射流助燃空气/Ar介质阻挡放电光谱特性研究

本文提出了Ar等离子体射流助燃空气/Ar介质阻挡放电装置,并对其进行了电气参数和等离子体参数诊断。实验结果表明,随着峰值电压的增大放电功率、N_2转动温度和振动温度、电子激发温度几乎线性地增大,并且当峰值电压从8 kV增大到11 kV时,放电功率最大值为61.21 W,N_2转动温度和振动温度分别从335 K和2497 K增大到了393 K和2672 K,而电子激发温度从 4129 K增大到了4465 K。另外,通过光谱诊断发现,放电等离子体富含了Ar*,O*,OH*,N_2*以及N_2~+等多种活性粒子。     

同轴介质阻挡放电功率和等效电容特性研究

以同轴—针放电结构为研究基础,采用Lissajous图像法,研究了介质阻挡放电管径、载气流速变化对放电功率和介质等效电容的影响关系;设计了正交实验,进一步研究载气流速和放电管径对周期传输电荷量显著性影响的大小.研究结果表明:随着载气速度的提升,放电功率和介质等效电容都呈减小趋势;随着放电管径的增大,介质等效电容减小.正交实验中,管径的F值为22.15,相比载气流速对传输电荷量的影响更加显著.     

高频板式DBD臭氧发生器的鲁棒控制北大核心CSCD

为了增强高频臭氧发生器系统长期工作的稳定性和动态调节特性,对板式介质阻挡放电(DBD)臭氧发生器进行建模和推导,得出其数学模型,并在此模型的基础上使用鲁棒控制方法,设计了一个H∞鲁棒控制器。通过仿真验证了控制器在臭氧发生器负载参数变化和外界干扰的情况下,系统能够快速地调节以达到原先设定的电压,实现系统的稳定输出。结果表明,使用该方法设计的控制器对板式DBD臭氧发生器系统的动态特性和系统的鲁棒性具有明显的提高作用,对工业上要求臭氧发生器需长期稳定地运行具有明显的参考意义。     

碳纳米管在高电压设备在线监测领域的应用

阐述了高压电气设备绝缘故障在线检测的一些方法,介绍了碳纳米管气体传感器近期的研究动向和取得的成果。应用碳纳米管气体传感器监测电气设备绝缘故障特征气体时,重点介绍了纯SF6,SF6/N2混合气体中局部放电产生的气体分解组分在电压、气体压强、温度等因素下对气体传感器的影响。并提出了碳纳米管气体传感器在高电压设备在线检测领域研究中所存在的问题和未来的研究发展方向。     

基于随机共振的纳米碳管气体传感器的研究

基于气体电晕放电原理,利用纳米碳管独特的物理结构和尖端发射效应,提出了一种新型的纳米碳管离子型气体传感器.采用阳极氧化铝模板法生长的定向纳米碳管阵列所构成的传感器,纳米碳管和电极是一体的,简化了器件结构和工艺.在外加直流电压激励下,纳米碳管顶部形成很强的非均匀电场,在电压相对低的情况下能很容易地电离气体,根据气体的击穿电压和放电电流来实现对单一气体和确定性混合气体的检测.为了提高检测混合气体的灵敏度,创新地在检测回路中引入随机共振发生装置,有效地提高了混合气体浓度检测的范围.实验中还分析了温度、湿度对传感器的影响,对该传感器的性能也作了评价.实验结果表明该传感器具有选择性好、体积小、响应时间快、灵敏度高、稳定性好,室温操作等优点,而且实现方便,操作简单,有较大的实用价值.     

Reduction of permanent image sticking in ACPDPs using RF‐plasma pretreatment on MgO surface

Abstract— The characteristics of the MgO layer are known to be an important parameter that affects the permanent image sticking or lifetime of an ACPDP. In this paper, to reduce the permanent image sticking in ACPDPs, the effects of RF‐plasma pretreatments of the MgO layer on the permanent image sticking are investigated. The treatment was conducted by using several plasma‐forming gases, including Ar, Ar followed by O², and O² followed by Ar. Measurements of luminance, normalized luminance, V^t closed curve, haze, MgO hardness, and photoluminescence between the discharge and nondis‐charge regions under dark and bright backgrounds indicated that the plasma treatments of MgO using either Ar or Ar followed by O² gases reduce the permanent image sticking on dark and bright images in an ACPDP.     

A silicon rectangular micro-orifice for gas flow measurement at moderate Reynolds numbers: design,fabrication and flow analyses

This work describes a micro-flowmeter for moderate flow rates of gases based on a differential pressure measurement. The micro-flowmeters consist of a microfabricated silicon–glass rectangular micro-orifice plate, with external pressure measurement. We experimentally evaluate the effects of geometrics parameters, Reynolds number and compressibility on the discharge coefficient. The paper examines a series of 13 rectangular micro-orifice sizes, with orifice hydraulic diameters ranging from 115 to 362 µm. The behavior of the discharge coefficient is presented for orifice Reynolds numbers ranging from 200 to 18000. Agreement is shown between the experimental and numerical results of the discharge coefficient. The micro-flowmeters measure moderate flow of air ranging from 1 to 106 mg/s. This demonstration implements a design method of micro-flowmeters that can be used in a broad range of microfluidic applications, such as microreactors and power MEMS.     

SnO2超微粒子薄膜的气敏特性研究

作者用自行设计的直流气体放电活化反应蒸发装置制备出平均粒径约为40nm的SnO_2超微粒子薄膜.研究了不同氧分压下所得SnO_2超微粒膜的形貌、结构和组成等特性,以及不同样品对各种易燃气体的气敏特性,得出了灵敏度随氧分压及灵敏度随工作温度的变化曲线.     

Modeling and online parameter estimation of intake manifold in gasoline engines using sliding mode observer

Model based control of automotive engines for fuel economy and pollution minimization depends on accuracy of models used. A number of mathematical models of automotive engine processes are available for this purpose but critical model parameters are difficult to obtain and generalize. This paper presents a novel method of online estimation of discharge coefficient of throttle body at the intake manifold of gasoline engines. The discharge coefficient is taken to be a varying parameter. Air mass flow across the throttle body is a critical variable in maintaining a closer to stoichiometric air fuel ratio; which is necessary to minimize the pollution contents in exhaust gases. The estimation method is based on sliding mode technique. A classical first Sliding mode observer is designed to estimate intake manifold pressure and the model uncertainty arising from the uncertain and time varying discharge coefficient is compensated by the discontinuity/switching signal of sliding mode observer. This discontinuity is used to compute coefficient of discharge as a time varying signal. The discharge coefficient is used to tune/correct the intake manifold model to engine measurements. The resulting model shows a very good agreement with engine measurements in steady as well s transient state. The stability of the observer is shown by Lyapunov direct method and the validity of the online estimation is successfully demonstrated by experimental results. OBD-II (On Board Diagnostic revision II) based sensor data acquisition from the ECU (Electronic Control Unit) of a production model vehicle is used. The devised algorithm is simple enough to be designed and implemented in a production environment. The online estimation of parameter can also be used for engine fault diagnosis work.     

线性分类器与BP网络联合诊断变压器故障

油中溶解气体分析(DGA)是目前电力充油设备潜伏性故障诊断的重要手段。为了克服传统BP网络及其改进诊断算法所具有的隐层节点数多、收敛时间长的缺陷,减少算法运算量及提高变压器故障诊断的正确率,提出了一种新的诊断算法:线性分类器-BP神经网络(LC-BP)故障辨识方法。通过对变压器大量过热和放电两类典型故障数据的研究,发现其DGA故障数据的特征空间线性可分且分离度较好。基于以上特性,先用线性分类器诊断过热和放电故障,然后利用两个小型BP网络分别进行进一步诊断,得到最终诊断结果。实验结果表明,提出的LC-BP算法具有良好的分类能力,故障诊断的正确率达到94%,且网络结构简单,运算量小,从而为变压器的故障诊断提供了一条新的有效途径。     

CEST and MEST: Tools for the simulation of radio frequency electric discharges in waveguides

In this paper we present two software tools for the simulation of electron multiplication processes in radio frequency (RF) waveguides. The electric discharges are caused by the multiplication of a small initial number of electrons. These are accelerated by the RF field and produce new electrons either by collisions with the walls of the waveguide (ripping new electrons from them), or by ionization of the neutral atoms of a gas inside the device.MEST allows simulating the Multipactor effect, a discharge produced in vacuum and generated by the collision of the electrons with the walls. CEST simulates the discharge when in addition a neutral gas is present in the waveguide, at pressures lower than ground levels (often denominated Corona discharge). The main characteristic of both tools is that they implement individual-based, microscopic models, where every electron is individually represented and tracked. In the case of MEST, the simulation is discrete-event, as the trajectory of each electron can be computed analytically. In CEST we use a hybrid simulation approach. The trajectory of each electron is governed by the Langevin stochastic differential equations that take into account a deterministic RF electric force and the random interaction with the neutral atom background. In addition, wall and ionizing collisions are modelled as discrete events.The tools allow performing batches of simulations with different wall coating materials and gases, and have produced results in good agreement with experimental and theoretical data. The different output forms generated at run-time have proven to be very useful in order to analyze the different discharge processes. The tools are valuable for the selection of the most promising coating materials for the construction of the waveguide, as well as for the identification of safe operating parameters.     

信息融合技术在变压器油气识别故障诊断中的研究

变压器故障分为放电性故障和过热性故障两大类别,它们均会在变压器油中有所反映。本文通过对变压器油中主要气体的分析,判断变压器的故障类型。具体方法是:利用改进算法的BP网络和信息融合技术,以变压器油中五种主要特征气体作为神经网络的输入,以六种变压器状态作为相应的输出,通过加入动量因子,可以提高学习率系数,充分发挥改进算法的BP网络具有自适应学习能力的优势。仿真测试结果表明,本方法能够在较大范围内准确有效地进行变压器的故障诊断。     

汽车尾气用NO_x传感器

汽车尾气中的有害物主要有CO,HC,NOx,SOx以及一些微粒物质,给人类赖以生存的大气环境带来了严重的危害。汽车尾气用NOx传感器开发主要是为了解决NOx(包括NO,NO2)的排放问题,能够实现准确、快速地测定NOx含量,从而满足大气质量检测和环境保护的要求。目前,NOx气体传感器主要有半导体型、电位型和电流型。主要介绍了这3种汽车用NOx传感器的原理、结构及应用,并简要分析了其向微型化、集成化和智能化等方向发展的趋势。