一种新的电容层析成像电极组合激励测量模式

电容层析成像图像重建为非线性不适定反问题,其敏感场分布不均匀,可获得的测量数据有限,中心处物体的成像效果不佳。增加电极数目,可获得更多的电容测量数据,减小其不定性,同时改善敏感场分布。但同时导致电容测量值变小,测量精度下降。在保证电容测量精度的前提下,提出了24电极组合式电容层析成像传感器结构,研究了两种激励测量方案,并与传统12电极电容层析成像传感器进行了对比分析,包括电容测量值的大小及其动态测量范围、灵敏场分布的均匀性以及不同流型下的重建图像。仿真结果表明,与12电极电容层析成像传感器相比,采用24电极组合式电容层析成像传感器,其电容测量值大,可较好地保证测量精度,其灵敏度分布更加均匀,对中心处物体的成像质量明显提高。     

基于碳纳米传感器的复合材料内部缺陷测量及误差估计

结合三维编织复合材料制造工艺,提出了利用碳纳米线传感器对三维编织复合材料试件缺陷检测的应用方法。论述了碳纳米线传感器嵌入三维编织复合材料预制件的方式,分析了碳纳米线传感器的力学特性。分析了编织角对嵌入碳纳米线传感器的影响。系统使用传统的应变放大器测量电阻变化。最后,应用响应面法对实验结果进行统计分析。实验表明,本实验的研究方法成功地实现了三维编织复合材料内部缺陷位置和大小的估计。     

基于红外热成像检测的飞机复合材料冲击试验研究

飞机复合材料的抗冲击能力是其重要的性能指标之一.本文通过对飞机复合材料结构常见冲击损伤源的研究,严格按照相关标准设计制作了冲击试件,并采用自由落体冲击试验方法和红外热成像检测技术手段,模拟分析了飞机复合材料结构的典型低能冲击损伤,研究得出了其主要损伤形式和特点.     

柔性传感多孔碳泡沫复合材料的制备及性能

为改善碳泡沫复合材料的性能，以低成本、短周期的一步碳化法制备了兼具柔性传感与超级电容器特性的三聚氰胺源多孔碳泡沫复合材料，研究了热处理温度对碳泡沫复合材料性能的影响。结果表明：碳泡沫复合材料为三维多孔网状结构，碳骨架在节点处部分呈凹形纤维状；经800℃热处理得到的碳泡沫复合材料比电容较大，为223.9 F/g，满足赝电容器电极材料的要求；经650℃以上热处理制备的碳泡沫复合材料灵敏度较好，将其作为压阻式传感器，可快速响应并精确分辨0.196～9.800kPa内的外部载荷。研究表明，制备的碳泡沫复合材料可以很好地应用于压应力传感器与超级电容器。     

高声衰减树脂基复合材料超声检测方法

根据高声衰减树脂基复合材料的特点,采用高能超声激励技术和接收端信号增强技术结合的穿透法对该种材料进行检测。分析了影响超声波幅值的激励电压、超声仪阻尼电阻、激励电信号波形等因素,提出了双极性方波脉冲串的激励方式,设计了接收端的放大电路,确定了检测参数。结果表明:在小于击穿电压的前提下,激励电压与超声波幅值成正比;其他条件不变,超声仪阻尼电阻调至最大时,可激励最大幅值的超声波信号;在同一条件下,不同激励电信号波形激励的超声波幅值大小关系为双极性方波脉冲串单方波尖脉冲;提出的方法实现了高声衰减树脂基复合材料的超声检测,且可检测不大于5mm的缺陷。     

人造板胶粘剂现场固化监测系统

介绍了人造板胶粘剂现场固化监测的系统组成,尤其对同面叉指电极电容传感器涉及的边缘电场、电极电容形态参数的计算方法以及测量终端连线方法等进行了分析.利用该介电测量方法可以准确了解人造板胶粘剂在实际热压时的固化开始温度和时间,对改进现有胶粘剂配方、优化热压工艺曲线具有明确的指导作用.     

两相流相关测速内外环电容传感器灵敏度

为了设计应用于两相流相关流速测量的内外环电容传感器,优化内外环电容传感器的结构 ,借助有限元仿真的方法对内外环电容传感器的灵敏度特性进行分析,利用正交实验设计方法来安排仿真实验。分析仿真实验结果,得到了影响传感器灵敏度特性指标（传感器相对灵敏度和检测场均匀性误差）的主要因素以及各个因素对这两个指标的影响程度和影响趋势,优选出一组传感器的结构参数,为内外环电容传感器的设计提供了理论依据。     

AC5/CP5-2交流阻抗测试系统

一、技术简介:电化学交流阻抗技术是交流信号对电化学体系进行激励观察电化学体系对激励信号的响应。响应信号中包含了电化学体系的极化电阻(Rp、Ra)、双电层电容(Cd)、溶液电阻(Rs)等电化学信息。电化学交流阻抗技术是对同一电极进行阳极和阴极交替微小极化,即使测量信号作用于电解池时间较长,对电极的影响也比较小。     

AC5／CP5—2交流阻抗测试系统

一、技术简介： 电化学交流阻抗技术是交流信号对电化学体系进行激励观察电化学体系对激励信号的响应。响应信号中包含了电化学体系的极化电阻（Rp、Ra）、双电层电容（Cd）、溶液电阻（Rs）等电化学信息。电化学交流阻抗技术是对同一电极进行阳极和阴极交替微小极化．即使测量信号作用于电解池时间较长,对电极的影响也比较小。     

有机硅酸酯薄膜SO2气体传感器

采用溶胶-凝胶法和自旋涂覆技术在二氧化硅为基材的梳状电极电容器（IDC）上形成有机硅酸酯的气敏涂层.在室温和0.1 kHz、1 kHz、10 kHz频率下测定了该电容器的电容,实验表明其电容的改变值和气氛中二氧化硫(SO₂)浓度的变化呈线性关系,亦与测量时使用的频率和气敏涂层的厚度密切相关.在本实验条件下,经有机改性的N,N-二乙基氨丙基三甲氧基硅烷比同类的硅酸酯对SO2有更高的灵敏度.     

Preparation and Characterization of hybrid graphene oxide composite and its application in paracetamol microbiosensor

Graphene oxides decorated with Sn(II) (Sn‐GO) were prepared via a redox reaction between graphene oxide (GO) and SnCl₂. GO was reacted Sn²⁺ leading to a homogeneous distribution of Sn on GO. An electrochemical sensor based on the electrocatalytic activity of functionalized graphene oxide for sensitive detection of paracetamol is presented. The electrochemical behaviors of paracetamol on grapheme modified carbon fiber electrodes were investigated by DC potential amperometry. The results showed that the Sn‐GO‐modified electrode exhibited excellent electrocatalytic activity to paracetamol. A redox process of paracetamol at the modified electrode was obtained. Such electrocatalytic behavior of graphene oxide is attributed to its unique physical and chemical properties, e.g., subtle electronic characteristics, attractive π–π interaction, and strong adsorptive capability. This electrochemical sensor shows an excellent performance for detecting paracetamol with a detection limit of 8 µM, a response time of 27 s, and a satisfied recovery. The sensor shows great promise for simple, sensitive, and quantitative detection and screening of paracetamol. We have investigated the composite properties of the self‐assembled electrodes for biological compounds analysis and showed that the Sn‐GO composite biosensor can achieve great sensitivity without significant bio material. The sensor shows great promise for simple, sensitive, and quantitative detection and screening of paracetamol. POLYM. COMPOS., 36:221–228, 2015. © 2014 Society of Plastics Engineers     

Complex capacitance analysis on rate capability of electric-double layer capacitor (EDLC) electrodes of different thickness

The complex capacitance analysis is utilized to examine the thickness-dependent rate capability of electric double-layer capacitor (EDLC) electrodes. Based on the transmission line model, the theoretical imaginary capacitance is derived for porous carbon electrodes, where the resistance relevant to ion transport in pores of carbon particles (intra-particle pores) and within electrode layer (inter-particle pores) is assumed to be the major component for equivalent series resistance (ESR). The use of hexagonal mesoporous carbon (HMC) as the EDLC electrode material, which has a well-defined pore structure, allows us to estimate the number of intra-particle pores in the composite electrodes such that the two resistance components are separately analyzed as a function of electrode thickness. As the theoretical derivation suggests, the time constant for intra-particle pores is invariant against the electrode thickness, whereas the time constant for inter-particle pores becomes larger for thicker electrodes. The poorer rate capability observed in the thicker electrodes is thus ascribed to a larger time constant for inter-particle pores.     

Recent advances and prospects of symmetrical solid oxide fuel cells

Solid oxide fuel cells (SOFCs) with symmetrical electrodes have been investigated extensively because of their potential significant advantages compared to the traditional configurations, regarding manufacturing, thermomechanical compatibility with cell components, operation stability, anting sulfur poisoning and carbon deposition. Many electrodes with novel structure and properties are currently being developed and studied in recent years. In this review, we summarized the recent advances of symmetrical SOFCs on their electrode materials, applications and prospects. The electrode materials include single phased perovskite, double perovskite, perovskite derived structures and composite electrodes. The relationships between the electrode materials and relevant properties are discussed. The applications and perspectives are highlighted, providing critical and useful directions for researchers to prepare and design electrode materials rationally.     

A strategy for selective detection based on interferent depleting and redox cycling using the plane-recessed microdisk array electrodes

The fabrication, characterization and application of the plane-recessed microdisk array electrodes for selective detection are demonstrated. The electrodes, fabricated by lithographic microfabrication technology, are composed of a planar film electrode and a 32 × 32 recessed microdisk array electrode. Different from commonly used redox cycling operating mode for array configurations such as interdigitated array electrodes, a novel strategy based on a combination of interferent depleting and redox cycling is proposed for the electrodes with an appropriate configuration. The planar film electrode (the plane electrode) is used to deplete the interferent in the diffusion layer. The recessed microdisk array electrode (the microdisk array), locating within the diffusion layer of the plane electrode, works for detecting the target analyte in the interferent-depleted diffusion layer. In addition, the microdisk array overcomes the disadvantage of low current signal for a single microelectrode. Moreover, the current signal of the target analyte that undergoes reversible electron transfer can be enhanced due to the redox cycling between the plane electrode and the microdisk array. Based on the above working principle, the plane-recessed microdisk array electrodes break up the restriction of selectively detecting a species that exhibits reversible reaction in a mixture with one that exhibits an irreversible reaction, which is a limitation of single redox cycling operating mode. The advantages of the plane-recessed microdisk array electrodes are verified by detecting dopamine in the presence of ascorbic acid and detecting pyrocatechol in the presence of hydroquinone, i.e., the electrodes can work regardless of the reversibility of interfering species.     

Electrochemical processes in the photoelectrolysis of nicotinamide adenine dinucleotide on the chlorophyll electrodes

The photoelectrolysis, in which redox compounds are electrolysed on a pair of photo-excitable electrodes by supplying photo—energy in place of electric energy, has been performed. The photo—excitable electrodes were prepared by coating a platinum plate with a thin layer of a chlorophyll—quinone composite. These electrodes were called chlorophyll electrodes. The chlorophyll electrode of chlorophyll—naphthoquinone composite worked as a cathode and that of chlorophyll—anthrahydroquinone composite as an anode when they were illuminated. The chlorophyll electrode of chlorophyll—naphthoquinone composite was characterized by an electrochemical behavior of p-type semiconductor electrode. Reduction of nicotinamide adenine dinucleotide (NAD⁺) was carried out on the chlorophyll electrode under illumination at various controlled electrode potentials. NAD was reduced at extremely noble electrode potentials are compared with the reductive potential of NAD⁺ to NADH. Electron transfer accompanied with the photoelectrochemical reactions is discussed.     

A highly selective electrochemical sensor for l‐tryptophan based on a screen‐printed carbon electrode modified with poly‐p‐phenylenediamine and CdS quantum dots

A new highly selective electrochemical sensor for the determination of l ‐tryptophan was proposed by modifying the surface of screen‐printed carbon electrodes (SPCEs). The surface of SPCE was firstly modified by electropolymerization of p‐phenylenediamine (PPD). The polymer film was then covalently linked with cysteamine capped cadmium sulfide quantum dots (Cys‐CdS QDs) by using glutaraldehyde (GA) as a cross‐linker resulted in an organic–inorganic hybrid composite film (QDs/GA/PPD/SPCE). The modified electrode was applied as a working electrode for detecting various amino acids. It was found that the modified electrode gave an electrochemical response selectively to l ‐tryptophan over other amino acids. The experimental parameters, including pH of solution, buffer types, electropolymerization cycles, scan rate, and accumulation time, were studied and optimized. The proposed sensor can be used to detect l ‐tryptophan with a low detection limit of 14.74 µmol L^?1 with good precision and the relative standard deviation less than 3.7%. The modified electrode was used to detect l ‐tryptophan in beverage samples and gave satisfactory recoveries from 91.9 to 104.9%. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40356.     

The use of microdielectrometry in monitoring the cure of resins and composites

As thermosetting resins and composites made from them begin to be used in critical applications, it becomes necessary to monitor and analyze the cure of the resin within the confines of the processing equipment. Such measurements have been carried out using a dielectric technique called dielectrometry or dielectric analysis. Conventional dielectrometry has certain limitations associated with the use of parallel plate geometry for electrodes. For in situ measurement of cure, intrusiveness of electrodes is a problem which may require placement of electrodes in non-strategic areas. Since electrode spacing changes during cure, it is difficult to deduce permittivity and loss factor from the data. At lower frequencies the capacitive currents are small and signal-to-noise ratios are small, therefore, measurement at low frequencies (>100 Hz) typically require large electrode sizes. One approach to overcome the problems described above is the development of microdielectrometry. A solid state integrated circuit chip, 2 by 4 mm in size, is used as the sensor. The miniature sensor can measure the properties of a dielectric on its surface, therefore it need not intrude into the composite part. Transistors which are built into the integrated circuit are used to amplify the signal to make low frequency (>1 Hz) measurements feasible. The electrode geometry does not change, therefore loss factor and permittivity data can be deduced in real-time. During cure of the resin or composite material, permittivity and loss factor are measured continuously at a series of preselected frequencies. Real-time-data is plotted on a strip chart and is also stored in a cassette for later analysis. Temperature of the curing material is measured either by a diode on the sensor or by externally placed thermocouples. Results on an aromatic amine cured epoxy resin and a dicyandiamide cured epoxy resin prepreg are presented in this report. The data obtained by microdielectrometry is compared and correlated to results obtained using differential scanning calorimetry, infrared analysis, and dynamic mechanical analysis. Results show that microdielectrometry can be used to follow the cure of epoxy resins and absolute measurements of permittivity and loss factor can be made to provide information on the mechanisms that produce the observed changes. Data at 1 Hz can be obtained but for certain lossy systems at typical cure temperatures, the data is often out of range of the instrument, thus restricting use to 10 Hz and higher frequencies. At very high loss factors (>100) a “blocking” phenomenon is observed due to charge pile up at electrode surfaces which results in erroneously high permittivity values.     

碱性电解水析氢电极的研究进展

电解水制氢将成为未来绿色制氢工业的核心技术。研究新型阴极材料以有效降低阴极过电位,对降低电解水能耗和设备成本、提高生产稳定性和安全性,具有十分重要的现实意义。本文主要对碱性水溶液电解制氢工业的析氢阴极材料进行综述。围绕电极结晶结构设计和尺寸结构设计两个主要的电极发展方向,重点介绍了3类基于电沉积制备技术的Ni基电极材料:合金析氢电极、复合析氢电极、多孔析氢电极。分析了当前析氢电极在实验研发与工业应用中存在的问题。指出采用电沉积法,制备催化活性更高且适用于工业电解环境的多元复合电极材料将是今后析氢电极发展的趋势。     

电化学技术制备高效析氢电极

采用电镀及复合电镀技术,制备出Ni、Ni-Mo、Ni-S、Ni-Co-Mo复合电极和Ni-S-Co-Mo纳米晶复合电极,并测试了以上各电极在1mol／L AlCl3溶液中的阴极极化曲线。结果表明,Ni-S合金电极、Ni-Co-Mo复合电极均具有较高的析氢电催化活性,而Ni-S-Co-Mo纳米晶复合电极的析氢电催化活性超过了Pt,具有很大的实用价值。     

Novel bipolar electrodes for battery applications

A novel bipolar graphite felt electrode for use in redox flow batteries and other electrochemical systems is described. The new electrode features a unique approach in the design of bipolar electrodes, employing carbon black free, nonconductive polymer materials as substrates. This innovation allows a dramatic reduction of processing time and cost compared to conventional carbon polymer composite electrodes used in bipolar battery systems. The conductivity of the new electrode assembly is similar to that of conventional bipolar electrodes, however, it shows significant improvements in mechanical properties. The functionality of these novel electrodes has been evaluated in the vanadium redox battery application and the results show comparable performance with conventional composite materials. An important operational advantage, however, is that side reactions leading to the deterioration of conductive filler in the electrode substrate material (i.e., electrode delamination due to CO₂-evolution) during cell overcharging are eliminated, making these electrodes more durable than the conventional designs. To date, these bipolar electrodes have been applied in vanadium redox cells but their design and properties promise further applications in a range of other redox flow batteries and bipolar electrochemical cell systems.