先进控制技术在波浪发电系统中的应用

由于波浪储量丰富,具有随机性,如何控制波能转换系统捕获最大波能和控制并网电能质量成为波浪发电的核心问题。简述了波能转换装置实现最大波能捕获的方法,综述了滑模变结构控制、自适应控制、最优控制、智能算法、模糊控制、无源控制在控制最大波能捕获以及改善电能质量方面的研究成果。并提出未来的控制算法应是多种先进控制算法相结合。     

Engineering practice and economic analysis of ozone oxidation wet denitrification technology

SO₂ and NO emitted from coal-fired power plants have caused serious air pollution in China. In this study, a test system for NO oxidation using O₃ is established. The basic characteristics of NO oxidation and products forms are studied. A separate test system for the combined removal of SO₂ and NO_x is also established, and the absorption characteristics of NO_x are studied. The characteristics of NO oxidation and NO_x absorption were verified in a 35 t·h^-1 industrial boiler wet combined desulfurization and denitrification project. The operating economy of ozone oxidation wet denitrification technology is analyzed. The results show that O₃ has a high rate and strong selectivity for NO oxidation. When O₃ is insufficient, the primary oxidation product is NO₂. When O₃ is present in excess, NO₂ continues to get oxidized to N₂O₅ or NO₃. The removal efficiency of NO₂ in alkaline absorption system is low (only about 15%). NO_x removal efficiency can be improved by oxidizing NO_x to N₂O₅ or NO₃ by increasing ozone ratio. When the molar ratio of O₃/NO is 1.77, the NO_x removal efficiency reaches 90.3%, while the operating cost of removing NO_x per kilogram is 6.06 USD (NO₂).     

Coalescence dynamics of two droplets of different viscosities in T-junction microchannel with a funnel-typed expansion chamber

The coalescence behavior of two droplets with different viscosities in the funnel-typed expansion cham-ber in T-junction microchannel was investigated experimentally and compared with droplet coalescence of the same viscosity.Four types of coalescence regimes were observed:contact non-coalescence,squeeze non-coalescence,two-droplet coalescence and pinch-off coalescence.For droplet coalescence of different viscosities,the operating range of non-coalescence becomes narrowed compared to the droplet coalescence of same viscosity,and it shrinks with increasing viscosity ratio η of two droplets,indicating that the difference in the viscosity of two droplets is conducive to coalescence,especially when 1 ＜ η＜ 6.Furthermore,the influences of viscosity ratio and droplet size on the film drainage time (Tdr) and critical capillary number (Cac) were studied systematically.It was found that the film drainage time declined with the increase of average droplet size,which abided by power-law relation with the size dif-ference and viscosity ratio of the two droplets:Tdr ～ (ld)0.25±0.04 and Tdr ～ (η)-0.1±002.For droplet coales-cence of same viscosity,the relation of critical capillary number with two-phase viscosity ratio and dimensionless droplet size is Cac =0.48λ0.26l-2.64,while for droplet coalescence of different viscosities,the scaling of critical capillary number with dimensionless average droplet size,dimensionless droplet size difference and viscosity ratio of two droplets is Cac =0.11 η-0.07ls-2.23ld0.16.     

Modified g-C3N4 derived from ionic liquid and urea for promoting visible-light photodegradation of organic pollutants

In this work, modified g-C₃N₄ was fabricated successfully by calcination of ionic liquid (IL) and urea. The addition of IL changed the polymerization mode of urea, induced the self-assembly of urea molecules, modified the morphological structure of the tightly packed g-C₃N₄, and extended the electron conjugation system. When using 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) as a modifier, the heteroatom Cl could be inserted into the g-C₃N₄ to optimize the electronic structure. The results of characterizations indicate that the unique structure of modified g-C₃N₄ has an expanded electron delocalization range, introduces an interlayer charge transmission channel, promotes the charge transmission, reduces the band gap, enhances the absorption of visible light, and inhibits electron-hole recombination. Modified g-C₃N₄ showed excellent photocatalytic performance for the degradation of rhodamine B and tetracycline. Furthermore, the effect of different anions in 1-butyl-3-methylimidazolium salts ([Bmim]Cl, [Bmim]Br, [Bmim][BF₄], and [Bmim][PF₆]) on the structure and function of g-C₃N₄ are discussed.     

基于异构物联网络的输电线路智慧巡检方法

为解决高海拔地区输电线路运行维护检修存在的传感器供电可靠性差、无移动信号区域数据传输难度大的问题,文中提出了一种基于异构物联网络的输电线路智慧巡检方法。首先,研究了风光协同的传感器供电技术,实现了高海拔地区恶劣环境下输电线路监测传感器的可靠供电;其次,建立了异构的输电线路物联网络,实现了输电线路无移动信号传感器的数据采集。在此基础上,通过深度学习对所采集数据样本进行分析,实现对输电线路的智慧巡检;最后,将所提方法在某无信号地区110 kV线路的现场运行,其结果验证了所提方法的有效性和可行性。     

CLLLC谐振式变换器的广义预测控制

针对CLLLC谐振式双向DC/DC变换器的模型复杂、环路设计困难以及动态特性慢等问题,提出了一种基于低阶等效模型的广义预测电压控制GPVC(generalized predictive voltage control)算法.首先通过扫频方法拟合得到变换器低阶等效模型;其次设计一种基于模型的GPVC策略,构建成本函数;最后,搭建实验样机实现预测电压控制算法.实验结果证明了所提控制策略的有效性,在多种工况下相比传统PI控制方法具有更优的稳态性、动态性和鲁棒性.     

夹层玻璃中间膜(离子聚合物)的表征与性能探究

离子聚合物中间膜具有较强的力学特征,在力学要求较高的结构性幕墙、栏杆、透明栈道等玻璃建筑上具有广泛的应用.通过对离子聚合物中间膜进行力学、光学等相关的物理性能测试,并与PVB中间膜的数据对比,凸显出离子聚合物的力学、光学等性能优势.利用傅立叶红外光谱(FTIR)、扫描电镜与X光谱区分析联用(SEM-EDS)确定离子聚合物中的主要成分,通过有机元素分析仪、物化分析对离子聚合物各组分基团进行定量分析.对不同厂家及实验室自制的离子聚合物中间膜性能进行比较和探究.     

Antibacterial and Antibiofilm Activities of Novel Antimicrobial Peptides against Multidrug-Resistant Enterotoxigenic Escherichia Coli

Post-weaning diarrhea due to enterotoxigenic Escherichia coli (ETEC) is a common disease of piglets and causes great economic loss for the swine industry. Over the past few decades, decreasing effectiveness of conventional antibiotics has caused serious problems because of the growing emergence of multidrug-resistant (MDR) pathogens. Various studies have indicated that antimicrobial peptides (AMPs) have potential to serve as an alternative to antibiotics owing to rapid killing action and highly selective toxicity. Our previous studies have shown that AMP GW-Q4 and its derivatives possess effective antibacterial activities against the Gram-negative bacteria. Hence, in the current study, we evaluated the antibacterial efficacy of GW-Q4 and its derivatives against MDR ETEC and their minimal inhibition concentration (MIC) values were determined to be around 2~32 μg/mL. Among them, AMP Q4-15a-1 with the second lowest MIC (4 μg/mL) and the highest minimal hemolysis concentration (MHC, 256 μg/mL), thus showing the greatest selectivity (MHC/MIC = 64) was selected for further investigations. Moreover, Q4-15a-1 showed dose-dependent bactericidal activity against MDR ETEC in time–kill curve assays. According to the cellular localization and membrane integrity analyses using confocal microscopy, Q4-15a-1 can rapidly interact with the bacterial surface, disrupt the membrane and enter cytosol in less than 30 min. Minimum biofilm eradication concentration (MBEC) of Q4-15a-1 is 4× MIC (16 μg/mL), indicating that Q4-15a-1 is effective against MDR ETEC biofilm. Besides, we established an MDR ETEC infection model with intestinal porcine epithelial cell-1 (IPEC-1). In this infection model, 32 μg/mL Q4-15a-1 can completely inhibit ETEC adhesion onto IPEC-1. Overall, these results suggested that Q4-15a-1 may be a promising antibacterial candidate for treatment of weaned piglets infected by MDR ETEC.     

IGBT串联均压方法综述

绝缘栅双极性晶体管IGBT(insulated gate bipolar transistor)在高电压场合应用时需串联使用满足电压需求。由于器件内部的性能差异和外围电路参数不一致等,引起IGBT模块之间电压不均衡问题,威胁其运行安全。综述了国内外IGBT串联均压方法的发展及其研究现状。根据均压方法机理的不同,将IGBT串联均压方法分为被动均压方法和主动均压方法两种,进一步将主动均压方法归纳为无源控制方法和有源控制方法两类。根据各类方法的基本电路拓扑分析了均压原理,梳理了不同方法在电路拓扑、参数选择和控制策略等方面的优化和最新进展。通过均压效果、附加损耗和可靠性等多方面对不同均压方法进行对比,被动均压方法拓扑简单不需外加控制电路更适合在低频应用场合,在高频应用场合中,准有源栅极控制法以单驱动与无源器件相结合的方式,具有良好的发展前景。最后对IGBT串联均压方法进行了展望。