平面上具有有界Fréchet导数的调和映照单叶半径的精确估计

给定单位圆盘D={z||z|1}上调和映照f(z)=h(z)+g(z),其中h(z)和g(z)为D上的解析函数,满足f(0)=0,λf(0)=1,ΛfΛ.通过引入复参数λ,|λ|=1,本文研究调和映照Fλ(z)=h(z)+λg(z)和解析函数Gλ(z)=h(z)+λg(z)的性质,得到Fλ(z)和Gλ(z)单叶半径的精确估计.作为应用,本文得到单位圆盘D上某些K-拟正则调和映照Bloch常数的更好估计,改进和推广由Chen等人所得的相应结果.     

平面拟共形映照的偏差函数估计

研究平面拟共形映照的偏差函数μ(r),λ(K)和ηK(t).利用环形区域模函数的共形不变性,证明μ(r)满足一个新的不等式.作为应用,不必利用椭圆函数的性质,得到了估计Gr(o|¨)tzsch,Teichm(u|¨)ller和Mori这3种典型极值环形区域模函数的更精确的不等式,并得到了λ(K)和ηK(t)的更精确的上下界估计不等式.改进了由Anderson,Vamanamurthy,Qiu和Vuorinen所得的相应结果.     

Accurate measurement of wall skin friction by single-pixel ensemble correlation

The present work deals with accurately estimating wall-skin friction from near-wall mean velocity by means of PIV measurement.The estimation accuracy relies on the spatial resolution and the precision of the resolved velocity profile inside the viscous sublayer,which is a big challenge for conventional window-based correlation method(K?hler C J,et al.Exp Fluids,2012,52:1641–1656).With the help of single-pixel ensemble correlation,the ensemble-averaged velocity vector can be resolved at significant spatial resolution,thus improving the measurement accuracy.To demonstrate the feasibility of this single-pixel ensemble correlation method,we first study the velocity estimation precision in a case of steady near-wall flow.Synthetic particle images are used to investigate the effect of different image parameters.It is found that the velocity RMS-uncertainty level of the single-pixel ensemble correlation method can be equivalent to the conventional window correlation method once the effective particle number used for the ensemble correlation is large enough.Furthermore,a canonical turbulent boundary layer is synthetically simulated based on velocity statistics resolved by previous Direct Numerical Simulation(DNS)work(Schlatter P,et al.J Fluid Mech,2010,659:116–126).The relative error of wall skin friction coefficient is shown to be one-order smaller than that of the window correlation method.And the optimization strategy to further minimize the measurement uncertainty is discussed in the last part.     

单位圆到水平条形无界区域的调和拟共形映照

研究单位圆盘到水平条形无界区域在原点满足一定规范条件的单叶保向调和映照的解析特征.推导出该类单叶调和映照的解析表示法.得到单位圆盘到水平条形无界区域在原点满足一定规范条件的单叶保向调和映照f(z)成为调和拟共形映照的充分必要条件,对该类调和拟共形映照的系数作出精确估计.作为应用,证明了该类调和拟共形映照的像在欧氏度量下的长度和面积与原像在非欧度量下的偏差定理.本文的结果改进和推广了由Hengartner和Schober所得的相应结论.     

Atomic decomposition of the protein solvation free energy and its application to amyloid-beta protein in water

We report the development of an atomic decomposition method of the protein solvation free energy in water, which ascribes global change in the solvation free energy to local changes in protein conformation as well as in hydration structure. So far, empirical decomposition analyses based on simple continuum solvation models have prevailed in the study of protein-protein interactions, protein-ligand interactions, as well as in developing scoring functions for computer-aided drug design. However, the use of continuum solvation model suffers serious drawbacks since it yields the protein free energy landscape which is quite different from that of the explicit solvent model and since it does not properly account for the non-polar hydrophobic effects which play a crucial role in biological processes in water. Herein, we develop an exact and general decomposition method of the solvation free energy that overcomes these hindrances. We then apply this method to elucidate the molecular origin for the solvation free energy change upon the conformational transitions of 42-residue amyloid-beta protein (Aβ42) in water, whose aggregation has been implicated as a primary cause of Alzheimer's disease. We address why Aβ42 protein exhibits a great propensity to aggregate when transferred from organic phase to aqueous phase.     

纳米Ag,CeO2和Ag-CeO2的合成及在CO催化氧化中的应用

系统合成了不同粒径的CeO2和Ag纳米粒子及Ag-CeO2纳米复合粒子,并对其进行了结构表征和CO催化氧化性能测试.结果表明,Ag纳米粒子的催化活性较低,以其为催化剂时CO的最大催化转化率仅为40%,且粒径越小越容易失活;在CeO2纳米粒子催化下,CO的催化转化率可达到100%,但催化反应的温度较高(约350℃);与CeO2和Ag相比,Ag-CeO2的催化性能明显增强,CO在较低的温度(150℃)下可实现完全转化.程序升温还原(Temperature-programmed reduction,TPR)分析结果表明,纳米复合材料中Ag和CeO2之间的相互作用是产生优异催化性能的关键原因.     

300 MW燃煤电厂ESP和WFGD对烟气汞的脱除特性

采用燃煤电厂汞形态浓度取样测试OHM标准方法,对一座300 MW燃煤电厂静电除尘器(ESP)和湿法脱硫装置(WFGD)前后烟气进行了等速取样.使用美国Leeman Labs Hydra AA全自动汞分析仪检测烟气中的汞形态浓度.采集了固体样品,包括入炉煤、底渣、ESP电场灰、脱硫剂石灰石、脱硫产物石膏等,使用意大利Milestone公司生产的DMA80全自动汞分析仪检测固体样品中的汞浓度.计算锅炉系统的汞质量平衡,获得了ESP和WFGD前后烟气的汞形态浓度和分布规律,分析讨论了影响烟气汞形态转化的各种影响因素.结果表明,燃煤烟气中气态单质汞Hg⁰和气态氧化汞Hg²⁺占到总汞量的95%.煤渣中的汞可忽略不计;ESP对颗粒态汞Hg^p的脱除效率达到95%以上,但是对Hg⁰和Hg²⁺脱除率不高.ESP对烟气总汞Hg^T脱除效率为12.77%~17.38%;WFGD对Hg²⁺的脱除率达到79.93%~90.53%,但是对Hg⁰没有脱除效果,其含量不仅没有下降反而有少量上升,说明有部分Hg²⁺在WFGD中被还原成Hg⁰.WFGD对Hg^T脱除效率为9.68%~29.36%;该电厂现有污染控制设备ESP+WFGD可以脱除全部的Hg^p和大部分Hg²⁺,但是由于部分Hg²⁺的还原使得Hg^T的脱除效率在25.38%~38.38%.综合来看,该燃煤电厂的污染物控制设备在进行除尘和脱硫的同时,对汞的脱除率并不高,与燃煤中的氯含量较低有关.     

无烟煤流化床气化飞灰的结渣特性

通过烧结特性实验研究了无烟煤流化床气化飞灰在"近灰熔点"处的烧结特性,并利用X射线衍射分析(XRD)进行了结晶矿物质和玻璃相的定量分析以研究其烧结机制。结果表明,飞灰中矿物质间的相互转化控制着其结渣特性。由于铁、钙和镁等碱性组分的部分富集,飞灰的灰熔点与原煤相比要低;在低于灰熔点DT 100~200℃附近,由于长石类矿物质的转变熔融形成了具有黏结性的液相,灰样发生液相烧结导致收缩变形而结块;大部分的钙和铁等助熔组分赋存于玻璃相中提高了其浓度,且在热处理过程中它们并未发生析晶行为,从而促进灰样的烧结致密化过程,进一步使得飞灰的结渣倾向增强。     

CO对褐煤快速热解行为的影响

利用快速升温固定床进行了霍林河褐煤在CO气氛下快速热解反应行为的研究,考察了热解半焦的产率、性质和气体产物的分布特点。半焦的红外光谱图、元素含量和表面结构性质分析表明,CO参与并改变了褐煤的热解行为。与N₂气氛相比,热解温度低于600 ℃时,带孤对电子的极性CO容易诱发半焦结构中芳香环的开裂,侧链、醚键和脂肪链的断裂,促进小分子片段和自由基的生成,自由基稳定了煤热解生成的碎片,导致挥发分的生成和逸出量增加,H₂、CH₄、CO和CO₂的产率增大,半焦产率降低,半焦的比表面积和孔容增大。热解温度高于700 ℃时,CO的歧化反应程度增大,产生的积碳附着于半焦的表面,阻塞了孔道,导致半焦的比表面积和孔容减小,从而抑制了CO在半焦孔隙结构内部的扩散,限制了CO与煤中有机大分子结构的接触和反应,导致H₂、CH₄和CO产率减小,而CO₂产率因CO歧化反应而增大。     

金属离子导向自组装的磺酰化对氨基苯甲酸配合物的合成与表征

用普通溶液法合成了4个配合物：[Cu（Ts-p-aba）₂（phen）（H₂O）]_n（1）、[Zn（Ts-p-aba）₂（phen）（H₂O）]·H₂O（2）、[Pb（Ts-p-aba）₂（phen）]2（3）和{[Pb（Ts-p-aba）（phen）（NO₃）]（DMF）}_n（4）（Ts-p-aba=N-对甲苯磺酰对氨基苯甲酸,phen=菲咯啉,DMF=N,N-二甲基甲酰胺）。X-射线单晶衍射结果表明：配合物1和2均为三斜晶系,P1空间群。配合物1的中心铜离子处于变形的八面体配位环境,并通过配体N-对甲苯磺酰对氨基苯甲酸扩展为一维直线链结构;配合物2是个单核分子,锌离子的配位多面体为四角锥体。配合物3和4均为单斜晶系,P2₁/c空间群。配合物3由配体N-对甲苯磺酰对氨基苯甲酸桥联成二聚体,铅离子处于变形的八面体配位环境;配合物4是具有一维链状结构的配位聚合物,铅离子处于变形的一面心八面体配位环境。另外,对4个配合物的热稳定性、电化学性能和荧光性质也进行了研究。