利用小波变换检测电化学噪声信号波形

简述了应用小波变换检测点蚀电化学噪声信号的基本原理,对在3.5％ NaCl溶液中工业纯铝发生点蚀的电化学噪声信号检测分析表明：小波变换能够提取发生点蚀的电化学噪声信号和测量系统噪声在多惊讶分辨空间中的波形特征,根据表征该特征的小波系数模极大值在不同尺度下的传播特性,可实现对点蚀电化学噪声信号波形的检测。     

阳极溶解电化学振荡体系中白噪声诱导随机共振的模拟

通过对电化学阳极溶解振荡模型加白噪声后引发的随机共振现象的模拟研究发现,在该体系的周期二振荡态时呈现显性内信号随机共振现象。当白噪声加在该电化学体系的周期二振荡态时,内信号的信噪比随着噪声的增大达到了最大值。同样噪声强度情况下,强信号的信噪比增加比弱信号的增加更加迅速。如果同时改变噪声强度,体系的信号频率也维持不变。研究表明,噪声对内信号的优化具有选择性,而体系的内信号也具有抵抗噪声和维持内在机制不变的性质。     

基础电化学实验的计算机测控系统

设计了一个由样品系统、电化学测试系统及计算机组成的可用于基础电化学实验测量的计算机测控系统。两个学期的学生实验表明该系统比传统的基础电化学实验测量系统的精度大大提高 ,能提供更多的信息且缩短了实验时间。这一系统还可用于多种电化学测量 ,效果良好。     

交流电桥测量精度的提高和低频范围的扩大

交流电桥法测量电化学体系的阻抗,是交流阻抗技术中的一种经典的方法。它需要的仪器简单,测量数据准确,因此在某些需要较准确测量结果的地方有应用价值。但是,交流电桥法在应用上也有局限性,例如,由于分布电容、电感以及主要是市电噪声干扰,测量的频率范围一般在20～20K Hz。这对于许多电化学体     

信号平均技术及其在光电化学中的应用

光电化学是研究在光照影响下的各种电极过程的一门新兴学科。在大多数情况下,光电化学实验体系所产生的光电响应非常微小。假如采用常规的放大方法,其结果微弱的光电响应将和噪声一起被放大,为此必须采用微弱信号检测技术,把淹没在背景噪声中的光电信号检测出来。信号平均技术就是一种在光电化学中常用的微弱信号检测技术。     

新型耗散型电化学石英晶体微天平的研制

针对目前商品化的石英晶体微天平(Quartz crystal microbalance,QCM)仪器存在的功能单一、耗材昂贵等问题,基于正交解调法阻抗分析原理,本研究搭建了新型QCM仪器系统。在此仪器系统中,通过嵌入式软件和硬件电路的深度结合,实现了较宽的频率范围内石英晶体谐振频率自动匹配和精确测量,并引入了电容补偿电路对石英晶体谐振片的静态电容进行实时补偿,从而消除了较高弹性负载情况下谐振频率的测量误差。通过对不同粘弹性负载环境、连续小质量负载添加、电化学联用测试等多个实验对所搭建仪器的功能和性能进行了验证和测试。实验结果表明,研制的QCM仪器系统适用的石英晶体频率范围较宽,可对石英晶体谐振片的静态电容进行自动补偿,频率测量精度可达0.1 Hz,并且能够实时、连续地测量耗散因子,能与多种电化学方法联用,具有功能丰富、耗材成本低等优点。     

强噪声背景中微弱信号检测的初步研究

为了提高信噪比,以往大都设法滤除噪声。根据随机共振理论,本文对用添加噪声来提高测量信号信噪比的方法进行了初步的尝试,并将此方法应用于强噪声背景中微弱信号的检测,得出了一些有意义的初步结构。     

生物细胞电化学噪声分析仪的研制及应用

本文提出了细胞离子通道的生物电化学噪声测试方法,设计并研制了电极电位和电流噪声测试电路。普鲁士蓝修饰的玻碳电极作为钾离子传感器,以测量细胞钾离子通道的开关周期。试验结果表明,宫颈癌细胞(HeLa细胞)钾离子通道的电流噪声功率谱分别在0.04Hz和0.06Hz出现峰值,说明HeLa细胞钾离子通道的开关周期在16s至25s之间。对离子通道的开关周期11次测量结果的标准偏差(RSD)10%。     

因次分析法在电化学噪声分析中的应用

采用电化学噪声技术,研究了铝合金2024-T3在NaCl溶液中孔蚀过程的电化学噪声特 征.结果表明:电化学噪声的时域数据通过传统的FFT变换后得到的频域曲线SPD的特征参数(W 、、k和fc)均不能单独正确地刻画材料表面孔蚀的强度和趋势.基于因次分析法的基本原理 和对材料腐蚀过程影响因素的分析,从电化学噪声频域曲线SPD的特征参数出发,导出了能正 确表征材料表面孔蚀强度和趋势的两个参数SE和SG.其中,SE正比于孔蚀的强度IS,而SG的意 义仍在进一步的研究之中.     

虚拟恒电位仪的研制及其在腐蚀电化学测量中的应用

恒电位仪是腐蚀电化学测量最重要的基本设备.虚拟恒电位仪用图形程序软件取代复杂硬件来实现恒电位功能.它的结构和参数灵活,构建简单,能满足多方面腐蚀电化学测试方法的需求,虚拟恒电位仪的实现是发展虚拟腐蚀电化学仪器的重要步骤.本文采用LabVIEW 2010编程系统和比例-积分-微分(PID)控制技术,研制了虚拟恒电位仪,并组建了VEC11-A腐蚀电化学测试系统,该系统能满足不同阻抗体系的腐蚀电化学测试需求.其腐蚀电位、稳态极化曲线、线性极化曲线、循环伏安、动电位扫描、恒电位阶跃等常规腐蚀电化学测量结果与2263电化学测试系统相近,能够满足常规腐蚀电化学测试要求,具有很大的发展空间.     

Two-parameter stochastic resonance in a model of electrochemical oxidation of formic acid on Pt

Stochastic resonance (SR) is shown in a two-parameter system, a model of electrochemical oxidation of formic acid on Pt. The driving current and the saturation coverage for carbon monoxide are two control parameters in this model. Modulation of an excitable focal stable state close to a Hopf bifurcation by a weak periodic signal in one parameter and noise in the other parameter is found to give rise to SR. The results indicate that the noise can enlarge a weak periodic signal and lead the system to be ordered. The scenario and novel aspects of SR in this system are discussed.     

基于电化学噪声研究模拟海洋大气环境下304不锈钢的点蚀行为

基于电化学噪声技术建立了不锈钢海洋大气点蚀监测系统,利用该系统对处于干湿循环环境下不锈钢的点蚀行为进行监测. 使用时域谱图、时域统计、频域谱图和散粒噪声理论等分析方法对采集到的电化学噪声数据进行处理分析,并结合动电位极化法,形貌分析法共同研究不锈钢的点蚀行为. 研究结果表明,304不锈钢在模拟海洋大气环境下的点蚀行为分为钝化、亚稳态点蚀和稳态点蚀三个阶段. 在钝化阶段,电位电流噪声信号出现少量的同步异向波动,腐蚀事件发生频率高,平均电量低;在亚稳态点蚀阶段,电位电流噪声信号出现大量的同步同向波动,腐蚀事件发生频率降低,平均电量上升,通过扫描电镜观察蚀点;在稳态点蚀阶段,电位电流噪声信号不仅存在大量的同步同向波动,还出现了同步异向波动,腐蚀事件发生频率较低,平均电量大幅度上升,通过扫描电镜观察到电极表面出现小而浅的蚀点. 而动电位极化法可以证实304不锈钢点蚀的发生. 两种分析方法所得结果具有较好的一致性,证明该监测系统很好地实现了对模拟海洋大气环境下304不锈钢点蚀行为的连续监测,并能判断点蚀的发生.     

高阻抗电化学体系恒电位脉冲暂态过程研究

提出一套恒电位脉冲测量暂态电流的技术,通过累加生成处理,可大大降低曲线的噪声,再由非等间距的差分处理,可对电化学体系时间常数作出简便的判定,还分析了脉冲幅度以及溶液电阻的作用,并在Fe/H_3BO_3＋Na_2B_4O_7体系和碳钢／砂土体系中对该方法进行了验证。     

The Kramers-Moyal expansion for electrochemical stochastic diffusion

It is proved that there is a general stochastic equation, according to which any random process in the transient mode can be presented by spatially homogeneous Kramers-Moyal expansion. In the electrochemical stochastic diffusion, an integral of the fluctuation component of electrode potential over the time plays the role of spatial coordinate. Based on these two facts, we derived a spatially homogeneous Kramers-Moyal expansion for the propagator of electrochemical stochastic diffusion. By using the limiting transition to long observation times, we obtained a time and spatially homogeneous asymptotic Kramers-Moyal expansion for the propagator of asymmetric non-Gaussian electrochemical stochastic diffusion. Under the conditions of Gaussian electrochemical noise, the asymptotic Kramers-Moyal expansion turns into the Einstein stochastic diffusion equation. The method of determining time and spatially homogeneous asymptotic Kramers-Moyal expansion for the propagator of asymmetric non-Gaussian electrochemical stochastic diffusion may be useful in the stochastic theory of slow electrochemical discharge and in the electrochemical noise diagnostics.     

低频外信号选择性优化的钙信号与IP3信号

用数值模拟的方法研究了钙信号系统中钙振荡与IP3振荡共存时,噪音和低频外信号对它们的选择性优化和调控.研究结果显示,低频外信号能够协同噪音作用,在一定强度范围内优化钙信号和IP3信号,但能够协同优化钙信号的条件范围明显较宽,说明协同作用对钙信号具有优先选择性.此外,在两种化学信号均可以被优化的外信号参数作用下,信号被优化的噪音强度范围也具有选择性.     

Theory of the wavelet analysis for electrochemical noise by use of the Laguerre functions

It is shown that the wavelet transform that uses the Laguerre function as a basis function is a useful tool to analyse the stationary electrochemical noise. Knowledge of the variance of the Laguerre wavelet of noise allows the Laplace transform of the correlation function to be found. The Laplace transform of the correlation function may be referred to the spectral density in the Laplace domain as well as to the operational spectral density of noise. It is shown that the operational spectral density of noise can be found not only by averaging over the ensemble of realizations of the noise process but also by averaging over the ensemble of Laguerre wavelets. The results obtained can be useful not only for analysis of electrochemical noise but also for analysis of any stationary random process, in particular for the time series analysis in econometric research.     

Online Monitoring of the Atmospheric Corrosion of Aluminium Alloys Using Electrochemical Noise Technique

In this work, an electrochemical system based on electrochemical noise (EN) technique for online detection and monitoring of atmospheric corrosion of LY12CZ aluminium alloys has been established. A detecting probe and a monitoring instrument with a software have been developed to perform the electrochemical noise measurements with zero resistance ammeter (ZRA) mode. Experimental results show that the atmospheric corrosion behaviour of aluminium could be effectively detected and monitored by the analysis of the electrochemical potential and current noise, also by the noise resistance variation.     

Theory for a wavelet analysis of electrochemical noise in the laplace space with use of two operational frequencies

The image of a random process in the Laplace space may be viewed as resulting from use of a oneway continuous wavelet transform with an exponential as the basic function, i.e. as resulting from the application of the Laplace wavelet. If the Laplace-wavelet variance of an electrochemical noise allows one to determine the Laplace transform of a time-correlation function, i.e. a factual operational spectral density of the noise, then the covariance of two Laplace waveletes of an electrochemical noise, each of which corresponds to its own operational frequency, allows one to verify a local consistency of the initial experimental noise data. The Laplace waveletes are applied rather widely. In fact, any stationary random process and stationary random time sequence can be described with operational noise spectra. Dedicated to the ninetieth anniversary of Ya.M. Kolotyrkin’s birth.