聚氨酯硬段堆叠结构的再发现：类结晶行为

利用傅里叶变换红外技术（FT-IR）首先阐明了本文工作中的聚氨酯氢键缔合程度或微相分离程度与热历史无关,只与样品所处温度有关。其次,利用差示扫描量热法（DSC）探究了升降温过程中出现的热效应,发现热效应所对应的硬段缔合结构与聚合物结晶行为非常相似,例如有缔合核存在下的快速生长、硬段较多时的快速生长、等温退火后生成特定的缔合结构等。综合以上实验结果可以发现,这些缔合结构的行为非常类似于高分子晶体。但与传统观点不同的是,微相分离与这些潜在的类结晶行为是两个独立的过程。     

高效分选废旧光伏电池板中铜与硅

为了提高废旧光伏电池板中铜(Cu)与硅(Si)的分选效率,寻求高压静电分选的最佳效率因素.通过单因素影响实验,探究了电压(U)、转辊转速(n)、电晕电极间距(S)和电晕电极角度(θ)对Cu与Si分选效率的影响;利用Minitab软件进行全因子实验设计,筛选并确定了影响因素中对Cu和Si的分选效率有显著影响的主效应和交互作用,并通过响应优化对Cu的分选效率进行了优化,得到Cu的最佳参数为U=20 kV、n=65 r/min、S=90 mm、θ=-10°.在最佳参数条件下,进行了验证实验,Cu分选效率达到了97.91%,得到了良好的优化效果.     

Experimental measurement of proton conductivity and electronic conductivity of membrane electrode assembly for proton exchange membrane fuel cells

Charge transport processes involving the proton migration and electron transfer for different parts of membrane electrode assemble (MEA) play an essential role for developing the novel electrode and enhancing the electrochemical performance towards proton exchange membrane fuel cells (PEMFCs). However, the coupled charge transport processes make it difficult for evaluating proton conductivity and electronic conductivity of different parts in MEAs under operation conditions of fuel cells. Here in this work, we propose an experiment approach for separating the electronic conductivity and proton conductivity of different components of MEA at the operating conditions of PEMFCs. This approach involves two different measuring devices, which both consist of electron or proton conducting layers, sealing layers and sample layer, followed by tailoring the thickness of sample layers and via electrochemical impedance spectroscopy (EIS) to quantity the electronic conductivity and proton conductivity of different layers. These experiment results show the great potential in the development of different components of MEA.     

基于神经网络的切换非线性系统辨识

提出了一种基于神经网络的多个Hammerstein-Wiener模型构成切换非线性系统的在线辨识方法.首先,通过误差逆传播(back propagation,BP)神经网络建立切换非线性系统的切换规律预测模型;其次,提出折息递推辨识算法对各个非线性子系统的参数进行辨识.利用关键项分离法对乘积项进行分离,得到各个子系统的参数估计值.最后通过切换非线性系统辨识实例,并与其他方法进行比较,验证了所提方法的有效性.结果 表明:提出的方法在辨识切换非线性系统方面具有更高的准确率和可靠性.     

基于时频分布的跳频信号盲分离方法

根据跳频信号的非平稳特性,提出一种基于时频分布的跳频信号盲分离方法。该方法利用不同源信号时频特征的差异,通过对混合信号的一组时频分布矩阵联合近似对角化来实现信号的盲分离。理论分析和仿真结果表明,这种方法在未知任何先验参数的情况下,能够有效分离多个跳频网台,而且具有较强的噪声抑制能力。     

一种基于组合核函数的非线性盲源分离方法研究

核函数方法由于其有效性和简洁性在非线性盲源分离问题的探索中得到了应用,但其单一核的映射不能很好解决完全非线性问题。针对这一不足,提出了一种采用组合核函数分离非线性混合信号的方法。通过引入变化尺度因子将不同核函数纳入一个整体成为组合核函数,利用分离信号的互信息作为目标函数来反馈调节该组合核函数的尺度因子,以此寻找到对不同非线性的最佳映射。仿真结果证实了该算法的有效性,且在解决完全非线性问题时,组合核函数比单一核函数具有更好的性能。     

Effect of Mg content on the structural and optical properties of Mg<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Zn<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>O alloys

Mgx Zn1–x O thin films with x = 0, 0.11, 0.28, 0.44, 0.51, and 0.65 were grown by plasma-assisted molecular beam epitaxy on (0001) sapphire substrates. X-ray diffraction measurement reveals that phase separation of the Mgx Zn1–x O films occurred at x =0.44 and 0.51. Optical absorption spectra show that the absorption edges of the films shift to high-energy side with increasing Mg contents. In resonant Raman spectra, multiple-order Raman peaks originating from ZnO-like longitudinal optical phonons were obser...     

Progress of applied research on TiO<Subscript>2</Subscript> photocatalysis-membrane separation coupling technology in water and wastewater treatments

Photocatalysis-membrane separation coupling technology has been a heavily researched area in water and wastewater treatment during recent years. The membrane separation process allows the photocatalyst to be easily separated, recovered and reused. More significantly, the membrane is efficient to maintain high flux of membranes as the photocatalyst can reduce the membrane fouling problem which is a hindrance in the development of membrane process. Moreover, some synergistic effects can also be produced, and ...     

单扫描极谱法测定土壤中游离铅

提出硝酸-超声波提取,在3.36 mol/L溴化钾、0.43 mol/L盐酸羟胺、7.32 mol/L磷酸、0.34 mol/L柠檬酸钠、0.5%动物胶体系中以单扫描极谱法测定土壤中游离铅的新方法。实验发现,在选定的实验条件下,铅在-470 mV的峰电流与铅浓度在2～4 000 ng/mL的范围内有良好的线性关系。考察了超声时间对游离铅提取情况的影响。结果表明,在超声时间为50 min以内时,土壤中溶出铅离子浓度随超声时间的增加而上升,超过50 min后,溶出的铅离子浓度趋于恒定。试样在4 mol/L硝酸溶液中超声10 min,溶出的铅离子浓度与在相同试剂中浸泡12 h相当,说明超声提取效果显著。     

TBS干扰床分选机在选煤厂的应用评价

阐述了TBS分选的基本原理及分选过程,评价了TBS干扰床分选机在选煤厂工艺改造后粗煤泥分选环节的分选效果。