基于流量测点的热网变动阻力系数优化辨识

随着供热计量系统的普及，系统可以根据负荷的变化进行调整，管网的阻力系数随即发生变化。对变动阻力系数进行优化辨识是了解供热管网实时运行状况的有效手段。提出一种基于流量监测数据的供热管网变动阻力系数优化辨识方法，并利用遗传算法进行求解。对洛阳市某小区供暖季管网实际运行数据进行验证，辨识结果的相对误差在5%以内。结果表明：该方法可以在只有流量观测数据时得到精度较高的供热管网变动阻力系数，为供热系统的运行调节提供指导。     

System-size effect on the friction at liquid-solid interfaces

The friction at the liquid-solid interfaces is widely involved in various phenomena ranging from nanometer to micrometer scales. By the molecular dynamic(MD)simulation, the friction properties of liquid-solid interfaces at the molecular level are calculated via the Green-Kubo relation. It is found that the system size will influence the value of the friction coefficient, especially for the solid surfaces with the larger polar charge. The value of the friction coefficient decreases with the increase in the system size and converges at large system sizes. The large polar charge will lead to a significant friction coefficient. However, the diffusion of water molecules on this surface is almost a constant, indicating that the diffusion coefficient seems to be independent of the system size and polar charge. This work provides insights for the selection of the system size in modeling the frictional properties of hydrophobic/hydrophilic surfaces.     

Identification and quantification of main flavonoids in the leaves of Bambusa multiplex cv. Fernleaf

Abstract

The chemical profile of Bambusa multiplex cv. Fernleaf (B. multiplex) leaves was analysed by UPLC-DAD-Q-TOF-MS. Twelve compounds were identified and C-glycosyl flavonoids, including vitexin, isovitexin, isoorientin and its derivatives, are the main constitutes of the plant. Besides, a HPLC method for isoorientin quantification was developed. The RSD of retention time and peak area were 0.05% and 2.04% for six times analysis of isoorientin with concentration of 20?μg/mL. The recovery of isoorientin in real sample was 99.2%. The general trend of isoorientin content in B. multiplex leaves was that it steady increased from Jan. to May, and then quickly decreased. The maximum was found on May with value of 4.7?mg/g. The lowest level of isoorientin was found during Aug. to Nov. with value of about 1.66?mg/g. In different seasons, isoorientin is always the most dominant flavonoid which was accounted for about 50% of total flavonoids in the sample.     

中空介孔SiO2纳米球的制备、改性及其对Al3+荧光识别研究

中空介孔SiO2由于中空多孔的结构而常用作功能材料的基底.将中空介孔SiO2进行官能团修饰,并应用为荧光传感材料是中空介孔SiO2一个重要的研究领域.本论文采用聚丙烯酸(PAA)为中空模板,聚醚F127为造孔剂,正硅酸乙酯(TEOS)为硅源,氨水为催化剂在乙醇体系中制备了中空介孔SiO2纳米球.系统研究了搅拌速度和聚醚F127引入量对中空介孔SiO2纳米球形貌及比表面积的影响.通过透射电镜、N2-等温吸附脱附曲线等表征说明该合成方法具有很好的普适性,通过调节F127的引入可以实现对比表面积的有效控制.通过氨基化、席夫碱反应进行荧光修饰,进一步研究表明荧光修饰后的中空介孔SiO2纳米球在水溶液中能够实现对Al3+的有效检测,检测限为1.19×10 -7M.     

衬底对单层二硫化钼光学性质的影响

为了实现二硫化钼器件化应用,通过机械剥离和PMMA纳米转移相结合的方法,研究二氧化硅、氮化硅和蓝宝石衬底对单层二硫化钼拉曼光谱以及光致发光光谱的影响.实验结果表明,单层二硫化钼在二氧化硅、氮化硅及蓝宝石衬底间转移会释放应力.氮化硅和蓝宝石衬底对单层二硫化钼引入p型掺杂,导致转移后拉曼光谱中的403 cm-1处A1g峰发生0.48 cm-1和1.20 cm-1的蓝移,光致发光光谱中的位于662 nm处的I峰有5.44 nm和12.73 nm的红移.本工作对单层二硫化钼的应用具有重要意义.     

石英相二氧化硅纳米管的制备及其对Pb2+的吸附行为研究

本文采用纯化的海泡石作为硅源,在不需要模板和煅烧工艺的条件下,制备出了石英相的硅纳米管(SNTs),并对获得样品进行了XRD、FTIR和SEM等表征.制得的SNTs具有40~50 nm外径,管腔直径为10~15 nm,长度为20~100 μm.此外,研究了SNTs对于Pb2+的吸附行为.结果表明,Pb2+吸附量随初始Pb2+浓度,吸附时间,温度和溶液pH值(<5)增加而增加.在溶液pH为5时,SNTs对于Pb2+的吸附平衡的吸附焓(ΔH)和熵变(ΔS)分别为6.28 kJ/mol和69.8 J/mol· K.     

CONTINUOUS DEPENDENCE ON DATA UNDER THE LIPSCHITZ METRIC FOR THE ROTATION-CAMASSA-HOLM EQUATION

In this article,we consider the Lipschitz metric of conservative weak solutions for the rotation-Camassa-Holm equation.Based on defining a Finsler-type norm on the tangent space for solutions,we first establish the Lipschitz metric for smooth solutions,then by proving the generic regularity result,we extend this metric to general weak solutions.     

表面增强拉曼光谱研究自组装单分子层在化学接触和纳米隔绝下的分子振动活性变化(英文)

为确定表面增强拉曼光谱中某些有争议的弱振动模式是来自高阶的影响还是分子基团对称性变化的影响,本文以1,4-苯二硫醇作为探针分子提供了一种实验验证的框架方法.光谱实验显示,观测到的有争议的弱振动模式并不是来自高阶的影响,而是分子基团对称性变化所致.我们的实验框架方法很容易拓展开来,如用于研究其它波长激光激发的类似体系或有机分子搭接的分子结.     

Dictamdiol的1H NMR 和13C NMR数据全归属

通过二维核磁技术,尤其是HMBC、HMQC和NOESY实验对一个从白鲜皮中分离得到的柠檬苦素类化合物-dictamdiol的¹H NMR 和¹³C NMR数据进行了全归属,并对文献中归属的错误进行了纠正.     

硫代硫酸钠标准溶液配制中标定基准物质的优化选择

对硫代硫酸钠标准溶液配制实验中不同基准物质的标定效果进行了对比研究,结合试剂用量、反应时间、显著性检验等分析说明不同基准物质所产生的结果:重铬酸钾、碘酸钾、溴酸钾均可实现对硫代硫酸钠溶液的标定。其中溴酸钾作为标定的基准物质时,试剂用量少,反应时间短,实验费用低且终点易于观察。双侧t检验符合统计学要求,更适用于硫代硫酸钠溶液标定,有望引入学生实验。