Simultaneous determination of lead, copper and cadmium onto mercury film supported on wax impregnated carbon paste electrode: Assessment of quantification procedures by anodic stripping voltammetry

The deposition and stripping processes of lead and copper and cadmium ions over the wide concentrations range of 1 × 10⁻⁵ to 5 × 10⁻⁹ M, have been studied at mercury film deposited on wax impregnated carbon paste electrode, using cyclic voltammetry, linear sweep anodic stripping voltammetry and differential pulse anodic stripping voltammetry. The carbon paste electrode modified with the mercury film was characterized for its physical and electrochemical properties. The parameters of deposition and stripping processes of the analytes have been investigated using standard solution of the metal ions at various concentrations and different supporting electrolytes and different pH. The linear sweep anodic stripping has been adopted for the determination of analytes at higher concentration whereas the analytes at lower concentrations were determined using DPASV. The DPASV behavior for the ions studied dependent on concentrations of the analyte as well as on the time used in the pre-concentration step. The method developed using standard solutions have been successfully applied for the determination of Cu(II), Pb(II) and Cd(II) in Fin Fish muscles and water samples.     

基于相位谱的翻录语音攻击检测算法

因与原始语音具有高度相似性,经高保真设备回放的翻录语音常被不法分子用于对说话人认证(ASV)系统进行攻击,以达到非法认证的目的.为提高系统抵抗翻录语音攻击的顽健性,通过研究原始语音与翻录语音产生的实际过程,发现两者在频率域相位上有明显差异,并在此基础上提出了一种基于相位谱的翻录语音检测方法.分析讨论了FFT和不同偷录、回放设备对翻录语音检测率的影响.实验结果表明,该方法能够准确地判断待测语音是否为翻录语音,其检测率达到了99.04％.并且,将该算法加载到说话人识别系统中,使系统的等错误概率(EER)降低了约22％,有效提高了系统抵抗翻录语音攻击的性能.     

ASV在ASP中的应用

装配次序的表述和产生是近年来的一个研究热点。对此,人们做了大量的研究工作,其中大部分工作是基于CAD几何信息模型而自动产生装配次序。本文提供的装配状态矢量法,它是结合宏观规划和微观规划的有力工具,它可以使用户易于编制和评估装配次序。     

Research and Development Techniques 1: Potentiodynamic Studies of Copper Metal Deposition

The electrochemistry of copper (II)/(I) ions in aqueous chloride solution, at pH2, is used to demonstrate the application of voltammetry techniques in characterising electrode processes. The electrolyte used is 1.5 M sodium chloride containing 20 to 50 × 10^?3 M cupric chloride at 20°C, in which both Cu(II) and Cu(I) ions are stable. A platinum rotating disc electrode (RDE, radius 0.365 cm) is used to provide controlled mass transport under laminar flow conditions. Cyclic voltammetry, at a stationary disc electrode, is used to characterise the general electrochemistry. Four current peaks due to reduction of Cu(II) ions to Cu(I) ions, deposition of Cu from Cu(I) ions, anodic stripping of Cu to form Cu(I) ions and oxidation of Cu(I) ions to Cu(II) ions are seen. Analysis of the Cu(II)/Cu(I) couple indicates a reversible process. A potential sweep rate experiment allows the diffusion coefficient of Cu(II) ions to be calculated. The anodic stripping peak in the cyclic voltammogram is used to estimate the amount of copper deposited. Reduction of Cu(II) to Cu(I) then to Cu is examined at a range of rotation speeds (150–1870 rpm) using linear sweep voltammetry at the RDE. Mass transport data are obtained in the form of limiting current density as a function of the RDE speed, allowing the diffusion coefficients of Cu(II) and Cu(I) ions to be calculated.     

Designing the NGC system of a small ASV for tracking underwater targets

The paper describes the development of the Navigation, Guidance and Control system of a small, prototypal Autonomous Surface Vehicle (ASV), which is part of an ASV/UUV (Unmanned Underwater Vehicle) robotic system. The main task of the ASV is to serve as supply vessel for the UUV it can carry, deploy and recover and to allow communication with a remote control station. The main problem the NGC system has to handle is that of making the ASV track the UUV and maintain the relative distance within a given bound, using delayed information about the UUV position provided by an acoustic tracking and positioning systems. The specific tracking problem is formulated in a suitable way and a strategy for its solution is proposed and implemented by means of an appropriate control architecture. Stability is discussed using Lyapunov techniques and performances are shown by means of simulations.     

便携式重金属分析仪同时分析水中痕量重金属的研究

评价了便携式重金属分析仪利用阳极溶出伏安法的原理分析水中的痕量重金属离子,Cu2+,Pb2+,Cd2+和Zn2+的分析指标,并对干扰Zn2+的因素及去除方法进行了研究.     

基于阳极溶出伏安法对PLS 算法的重金属离子的同时测定

重金属离子对于环境的污染和人类的危害越来越大，利用阳极溶出伏安法可以提高检测的精度和实现多种离子(Cu、Pb、Cd、Zn)的同时测定。而利用化学统计的方法可以有效的消除溶液中各种离子之间的相互干扰，我们利用偏最小二乘回归方法建立的模型对未知溶液具有很好的预测能力，预测误差不超过15％。另外我们采用超微组合圆盘铂电极，提高了检测的灵敏度，测量精度达ppb。     

导电聚合物电极同时测定痕量铜、铅、镉、锌

使用一种新型导电聚合物电极作为工作电极,采用阳极溶出伏安法通过同位镀铋对导电聚合物电极进行修饰,实现了痕量铜、铅、镉、锌的同时测定.比较了导电聚合物电极和丝网印刷碳电极的性能,研究了预富集时间和不同介质对重金属离子测定的影响规律.结果表明:铜、铅、镉、锌在铋膜修饰的导电聚合物电极上分别在0.05 V、-0.55 V、-0.80 V、-1.10 V产生灵敏的电位溶出峰,峰高与离子浓度线性相关,最低检测限分别可达到0.5 μg/L、1 μg/L、1 μg/L和0.5 μg/L.在检测重金属离子方面,导电聚合物电极比丝网印刷碳电极更加灵敏和稳定,为一次性电化学传感器的发展提供了良好的基础.     

说话人验证系统攻击方法的研究现状及展望

自动说话人验证（Automatic speaker verification,ASV）技术的发展正在深刻地影响和改变着当前的人机交互系统,ASV作为一些智能设备的语音核心功能,可以接受目标说话人的语音并准确识别出该说话人的身份。近年来,人工智能技术的快速进展推动了ASV系统实现跨越式发展。然而,随着人工神经网络和深度学习技术的发展,越来越多的研究者开始研究如何攻击ASV系统。如何通过对原始语音进行一系列处理实现对ASV系统的攻击,是近年来语音领域研究的一个热点问题。目前,对ASV系统的攻击方法大致可分为欺骗攻击（Spoofing attack）和对抗攻击（Adversarial attack）两大类。本文对两大类的典型方法和基本原理进行综述,梳理了目前一些攻击手段中存在的若干问题,揭示了ASV系统存在的安全隐患,对今后ASV系统安全性的发展做了简要的展望,并为未来进一步提高ASV系统的安全性和可靠性提供了参考。     

Adaptive predictive path following control based on least squares support vector machines for underactuated autonomous vessels

Since vessel dynamics could vary during maneuvering because of load changes, speed changing, environmental disturbances, aging of mechanism, etc., the performance of model‐based path following control may be degraded if the controller uses the same motion model all the time. This article proposes an adaptive path following control method based on least squares support vector machines (LS‐SVM) to deal with parameter changes of the motion model. The path following controller consists of two components: the online identification of varying parameters and model predictive control (MPC) using the adaptively identified models. For the online parameter identification, an improved online LS‐SVM identification method is proposed based on weighted LS‐SVM. Specifically, the objective function of LS‐SVM is modified to decrease the errors of parameter estimation, an index is proposed to detect the possible model changes, which speeds up the rate of parameter convergence, and the sliding data window strategy is used to realize the online identification. MPC is combined with the line‐of‐sight guidance to track straight line reference paths. Finally, case studies are conducted to verify the effectiveness of the proposed path following adaptive controller. Typical parameter varying scenarios, such as rudder aging, current variations and changes of the maneuverability are considered. Simulation results show that the proposed method can handle the above situations effectively.