大型抽水蓄能机组现场启动调试技术研究及应用

随着抽水蓄能电站建设的不断增加，越来越多的抽水蓄能机组需投入电网运行，为了确保新投入机组的安全、可靠、稳定运行，新投产机组必须经过一整套严格的启动试验程序，以检验机组的安装和制造质量，同时为机组能否进入电网稳定运行作出评价。本文结合工程实际，详细叙述了抽水蓄能机组现场启动调试的步骤和顺序，并就电站首机首次启动方式进行了分析和论证。     

GB/T18482《可逆式抽水蓄能机组启动试运行规程》修订中的重大问题研究

对GB/T18482-2001《可逆式抽水蓄能机组启动试验规程》修订的主要内容和重大问题进行分析、介绍,以期在使用中更好地发挥国家标准的指导作用。     

Reversible pH-Responsive Hydrogels of Softwood Kraft Lignin and Poly[(2-dimethylamino)ethyl Methacrylate]-based Polymers

Softwood kraft lignin (SKL) pH-responsive hydrogels were prepared through controlled aggregation using poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA) and poly(2-(dimethylamino)ethyl methacrylate)-block-poly(ethylene oxide)-block-poly(2-(dimethylamino) ethyl methacrylate) triblock copolymer (PDMAEMA-co-PEO-co-PDMAEMA). At low SKL concentrations, the SKL/polymer (PDMAEMA and PDMAEMA-co-PEO-co-PDMAEMA) aqueous solutions exhibited pH-dependent aggregation arising from the formation of strong intermolecular hydrogen bonds. Decreasing the SKL/polymer weight ratio resulted in the pH-reversible soluble-insoluble (S-I) transition to become a soluble-insoluble-soluble (S-I-S) transition, which upon increasing the SKL concentration resulted in hydrogel formation. Under neutral conditions relatively strong hydrogels were formed, which upon either increasing or decreasing solution pH resulted in the hydrogels collapsing to liquid solutions, but were readily reformed upon neutralization. The effects of polymer structure, concentration, and intermolecular interactions on solution behavior and gelation are thoroughly discussed.     

大型结构件焊接变形控制浅谈

针对大型结构件焊接变形的必然性及危害,重点从设计和施工两方面介绍了其焊接变形的控制措施,通过实践应用,获得了良好的减少和控制大型结构件焊接变形的效果。     

风筒逆向隔断装置在大林煤矿的应用与改进

大林煤矿在对经过反向风门墙垛的风筒逆向隔断装置进行革新改造后,增强了逆向隔断装置的可靠性,降低了逆向隔断装置的破坏率,从而最大限度地提高了发生煤与瓦斯突出时逆向隔断风流的保险系数。     

Sensitivity and inverse analysis methods for parameter intervals

This paper proposes a sensitivity analysis method for engineering parameters using interval analyses.This method substantially extends the application of interval analysis method.In this scheme,parameter intervals and decision-making target intervals are determined using the interval analysis method.As an example,an inverse analysis method for uncertainty is presented.The intervals of unknown parameters can be obtained by sampling measured data.Even for limited measured data,robust results can also be obtained with the inverse analysis method,which can be intuitively evaluated by the uncertainty expressed in terms of an interval.For complex nonlinear problems,an iteratively optimized inverse analysis model is proposed.In a given set of loose parameter intervals,all the unknown parameter intervals that satisfy the measured information can be obtained by an iteratively optimized inverse analysis model.The influences of measured precisions and the number of parameters on the results of the inverse analysis are evaluated.Finally,the uniqueness of the interval inverse analysis method is discussed.     

基于可见水印的课件版权保护研究

互联网络的快速发展推动了网络课程和远程教育的广泛应用。课件是一种重要的网络教学资源,为保护制作者的权益,将可见水印和可逆数据隐藏技术相结合应用于课件版权保护系统中。版权通告采用了自适应图像特性的可见水印技术,为能按需还原图像采用了基于直方图的可逆数据隐藏技术。该算法使版权水印标识在不影响图像使用的基础上清晰可见,并且可去除水印,完全恢复出原始图像。实验结果验证了该算法应用于课件版权保护的有效性。     

One‐step synthesis of triarm block copolymers via simultaneous reversible‐addition fragmentation chain transfer and ring‐opening polymerization

One‐step synthesis of star copolymers by reversible addition–fragmentation chain transfer (RAFT) and ring‐opening polymerization (ROP) by using a novel dual initiator is reported. Triarm block copolymers comprising one polystyrene (or polyacrylamide) arm and two poly(β‐butyrolactone) arms were synthesized in one‐step by simultaneous RAFT polymerization of styrene (St) (or acrylamide, designated as AAm) and ROP of β‐butyrolactone (BL) in the presence of a novel trifunctional initiator, 1,2‐propanediol ethyl xanthogenate (RAFT‐ROP agent). This dual initiator was obtained through the reaction of 3‐chloro‐1,2‐propanediol with the potassium salt of ethyl xanthogenate. The principal parameters such as monomer concentration, initiator concentration, and polymerization time that affect the one‐step polymerization reaction were evaluated. The characterization of the products was achieved using Fourier‐transform infrared spectroscopy (FTIR), ¹H‐nuclear magnetic resonance (¹H‐NMR), ¹³C‐nuclear magnetic resonance (¹³C‐NMR), Gas chromatography–mass spectrometry (GC–MS), gel‐permeation chromatography (GPC), thermogravimetric analysis (TGA), and fractional precipitation (γ) techniques. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

苯乙烯可逆加成-断裂链转移聚合动力学

为了实现可逆加成-断裂链转移(RAFT)聚合过程中,苯乙烯均聚、高分子量聚苯乙烯的合成及苯乙烯与其他单体共聚时,对苯乙烯转化率、共聚时组成和分子量大小的控制,进行了二硫代苯乙酸-1-苯基乙酯(PEPDTA)调控苯乙烯本体和细乳液聚合动力学分析。在本体聚合中,反应速率慢,链增长自由基与"中间态"自由基的终止反应对聚合速率影响较小,很难合成窄分布、高转化率、高分子量的聚苯乙烯;在细乳液聚合中,反应速率快、转化率高,随着PEPDTA含量增加,乳胶粒数量减少、粒径分布变宽,诱导期和缓聚现象明显;聚合物的数均分子量随转化率线性增长,RAFT试剂浓度越高,分子量分布越窄,反应时间越长,分布越宽。以Smith-Ewart方程为基础,建立了苯乙烯RAFT细乳液聚合动力学模型,模型动力学曲线与实验数据相符合,能较好地预测实验过程。     

Microstructure optimization of fuel electrodes for high-efficiency reversible proton ceramic cells

Reversible protonic ceramic cells (R-PCCs) are efficient energy storage and conversion devices that can operate in two modes, namely, in the fuel cell mode for the conversion of fuel to electricity, and in the electrolysis (EC) mode for the EC of water into hydrogen and oxygen. Fuel electrode is a critical component of fuel-electrode-supported R-PCCs, and its pore structure directly affects the electrochemical performance of the R-PCCs, but it has not been fully studied yet. Herein, the pore structure of Ni–BaZr_0.1Ce_0.7Y_0.1Yb_0.1O_3−δ (Ni–BZCYYb) fuel electrodes was systematically modulated by varying the weight ratio (0, 5, 10, and 15 wt.%) of the pore-former added to Ni–BZCYYb, and the electrochemical performance characteristics in the fuel cell and EC modes were investigated. The cell with 10 wt.% pore-former in the Ni–BZCYYb electrode achieved a remarkable peak power density of 540.7 mW cm⁻² and a high current density of –2.28 A cm⁻² at 1.3 V at 700°C in the fuel cell and EC modes, respectively, and showing excellent durability for over 100 h. These results further highlight the critical role of the microstructure of fuel electrodes, which can be modified to achieve exceptional performance, particularly in EC operations.