A novel long short-term memory networks-based data-driven prognostic strategy for proton exchange membrane fuel cells

Proton exchange membrane fuel cell (PEMFC) long-term prognostic facilitates reducing the time/cost of the durability tests and is a critical starting point for control/maintenance suggestions. Long short-term memory (LSTM) recurrent neural networks have excellent time series processing capabilities and are proved to be useful for the short-term prognostic of PEMFC. However, LSTM prognostic models usually suffer from accumulated errors and model recognition uncertainties, which make it difficult to break the historical degradation data limitations, resulting in unsatisfactory long-term prediction performance. To tackle the problem, this paper proposes a novel model named navigation sequence driven LSTM (NSD-LSTM) for long-term prognostic. In the strategy, a navigation sequence is firstly generated by using an autoregressive integrated moving average model with exogenous variables. The sequence is then fed iteratively into LSTM in the implementation stage to achieve long-term perdition. The proposed strategy is evaluated using the aging experimental data of two types of PEMFC under different operating conditions. The long-term prognostic performance of the proposed model and other two state-of-the-art prognostic models, namely, nonlinear autoregressive exogenous and echo state network, are evaluated through comparison experiments. The simulation and experimental results show that the proposed prognostic strategy has better long-term degradation trend prediction consistency and remaining useful life estimation robustness.     

宝钢低铁损取向硅钢在变压器新能效标准下的应用

随着变压器新能效标准GB 20052-2020的正式实施，变压器各能效等级普遍提升，也推动取向硅钢产品等级的提高。本文结合新能效标准，针对宝钢低铁损取向硅钢产品应用实绩，给出选材建议，并针对产品使用过程中存在的问题进行剖析，以期对变压器制造厂家选材和使用起到参考作用。     

一种用于电气设备状态监测的新式FBG传感器北大核心CSCD

为了监测绕组变压器的静态应力场和发生短路等故障时的动态应力变化,设计了一种用于电气设备状态监测的新式FBG传感器。该传感器由聚醚醚酮材料封装的FBG构成,通过内部圆锥形空腔结构实现将轴向应力集中于FBG敏感位置。通过仿真对不同压力强度下传感器结构的应力场部分及形变趋势进行了计算与分析,论证了设计的合理性。实验分别对静态载荷和动态冲击进行测试,结果显示,在静态压载测试中,当100 N相似文献   

Cloning,sequencing and structural analysis of membrane-bound polyphenol oxidase from Granny Smith apples (Malus × domestica Borkh)

The gene sequence coding for the membrane-bound polyphenol oxidase (mPPO) with a length of 1761 bp was cloned by PCR method and shown to contain one highly conserved sequence encoding a di-copper-binding region. The predicted three-dimensional structure of mPPO indicated that the active site was located near two copper ions and composed of a typical bundle of four α-helices. Each of the two catalytic copper ions was coordinated with three histidine residues in the hydrophobic pocket, yielding His 180, His 201, His 210, His 332, His 336 and His 366. Docking studies showed that 4-methylcatechol and chlorogenic acid have different binding models due to different ligand sizes and binding sites in the active centre, and it was found that the smaller compound exhibited a higher affinity for mPPO. Molecular dynamic simulation results indicated that Phe 353 is important in controlling enzymatic activity through influencing substrate coordination in the active site.     

Electron injection barrier and energy-level alignment at the Au/PDI8-CN2 interface via current–voltage measurements and ballistic emission microscopy

We probe electron transport across the Au/organic interface based on oriented thin films of the high-performance n-type perylene diimide semiconductor PDI8-CN₂. To this purpose, we prepared organic-on-inorganic Schottky diodes, with Au directly evaporated onto PDI8-CN₂ grown on n-Si. Temperature-dependent current–voltage characteristics and complementary ballistic electron emission microscopy studies reveal that rectification at the Au/PDI8-CN₂ interface is controlled by a spatially inhomogeneous injection barrier, that varies on a length scale of tens of nanometers according to a Gaussian distribution with mean value ∼0.94 eV and standard deviation ∼100 meV. The former gradually shifts to ∼1.04 eV on increasing PDI8-CN₂ thickness from 5 nm to 50 nm. Experimental evidences and general arguments further allow to establish the energetics at the Au/PDI8-CN₂ interface. Our work indicates injection-limited current flow in PDI8-CN₂-based devices with evaporated Au electrodes. Furthermore, it suggests chemical reactivity of PDI8-CN₂ with both Au and Si, driven by the lateral isocyano groups.     

Role of activated carbon on micropollutans degradation by ionizing radiation

The objective of this study was to analyze the influence of the presence of activated carbon on the degradation of the triiodinated contrast medium diatrizoate (DTZ) by the simultaneous use of gamma radiation and activated carbon. Four commercial activated carbons (Ceca, Witco, Sorbo, and Merck) with different textural and chemical characteristics were used for this purpose. The percentage DTZ removal obtained was considerably higher with the gamma radiation/activated carbon (GM/AC) system than with radiolysis in the absence of activated carbon, and it depended on the specific activated carbon employed. First, we optimized the amount of activated carbon required to maximize the amount of DTZ removed by the GM/AC system (0.06 g). The degradation constants were higher with the GM/AC system than with radiolysis alone, evidencing a synergic effect that favors pollutant removal. This synergic effect is independent of the textural but not the chemical characteristics of the activated carbon, observing a higher synergic activity for carbons with a higher surface content of oxygen, specifically quinone groups. We also highlight that the synergic effect of the activated carbon requires adsorbent–adsorbate electrostatic interaction and is absent when this interaction is hindered.     

Carbon nanotube–polyaniline composites

The last decade has seen a growing interest in hybrid electrically conducting nanocomposites. This article aims to provide a detailed overview of the present status of research in carbon nanotube–polyaniline (CNT/PANI) composites, from processing to structural and property evaluations. CNT/PANI are synthesized by electrochemical and chemical processing. When chemical methods are used, the main challenge is to obtain processable CNT/PANI in the emeraldine salt (ES) form composites. Stable dispersions of ES–CNT in organic media are prepared using the post doping method, inverse emulsion polymerization, or ex situ polymerizations. On the contrary, stable water dispersions of CNT/ES are prepared using hydrophilization of a preformed CNT/ES composite, direct synthesis of micelle–CNT hybrid templates, interfacial polymerization, covalent functionalization of CNT with a water soluble polymer, or using electrostatic interactions between two oppositely charged ES and CNT aqueous colloids. Moreover, the strategies for the synthesis of ternary CNT/PANI composites incorporating noble metal nanoparticles, metal oxide, or graphene sheets are also presented and analyzed in depth. Finally, we give a review of potential applications, including chemical sensors, capacitors, fuel cells and electronic devices.     

双固化聚硅氧烷丙烯酸酯的性能研究

添加活性稀释剂是调节光固化体系黏度、光固化反应速率、固化产物性能的有效手段。采用丙烯酸异辛酯(2-EHA)为活性稀释剂,利用实时红外(FT-IR)研究了活性稀释剂用量对双固化聚硅氧烷丙烯酸酯树脂(PSA)光聚合的影响。结果表明,稀释剂的加入不仅能改善体系的流变性能,同时稀释剂参与光聚合过程,提高体系的固化交联程度,改变交联网络,从而影响固化物的力学性能。通过红外跟踪研究了固化顺序(先光固化后湿气固化和先湿气固化后光固化)对体系中C=C双键和Si-OCH基团转化率的影响,结果表明,先光后湿的3固化顺序更有利于使体系达到高的转化率;DSC分析发现固化顺序对固化物玻璃化转变温度有一定影响。     

变压器中绝缘纸纤维素降解化学指示剂的综述

对油浸变压器中绝缘件化学降解和热降解、故障机理、状态监测方法及寿命预测进行综述。对不同油纸环境中评估绝缘寿命的寿命预测模型进行研究。对变压器油中化学指示剂浓度的系统测试证明糠醛及其相关产物可用于检测绝缘纸裂解的程度。     

氯磺化聚乙烯的结构与性能研究进展

简述了氯磺化聚乙烯(CSM)在国内外的主要生产工艺方法,较详细地介绍了基体树脂类型、氯含量、硫含量等结构因素对CSM化学性能如热性能、力学性能以及耐燃性能的影响。同时还介绍了CSM中氯原子序列分布的3种定量分析方法,并对其相应特点进行了阐述。