垫层的E/d对水电站蜗壳结构的影响分析

利用ANSYS大型有限元软件,建立垫层蜗壳结构的三维有限元模型,研究了结构自重和内水压力作用下垫层弹性模量与厚度比值E/d对水电站蜗壳结构的影响,给出了蜗壳外围混凝土、蜗壳以及座环的特性随垫层E/d变化的规律。结果表明:在有垫层区,蜗壳外围混凝土承载比、与蜗壳接触处混凝土切向应力随垫层E/d增大而增大,蜗壳应力以及最大相对变形量随垫层E/d的增大而减小,当垫层E/d确定时蜗壳结构外围混凝土承载比、与蜗壳接触处混凝土切向应力、蜗壳和座环应力以及蜗壳变形量一定,不会随E或d的变化而变化;在无垫层区,蜗壳外围混凝土承载比、与蜗壳接触处混凝土切向应力、蜗壳应力变形与垫层E/d无关。     

SiO2-BaTiO3异质双尺寸超材料结构的制备

采用垂直沉积法自组装制备了SiO2胶体晶体模板,并结合Pechini溶胶-凝胶法实现多种SiO2-BaTiO3异质双尺寸超材料结构的制备.通过X射线衍射分析仪(XRD)和场发射扫描电子显微镜(FE-SEM)对所得粉体和光子晶体的晶型、形貌及排列方式进行测试分析.对比钛酸钡粉体,对SiO2-BaTiO3异质超材料的结构进行探讨,研究不同pH值对钛酸钡粉体的形貌和粒径的影响,进而研究不同凝胶对异质超材料结构的影响.研究结果表明异质结构中胶体晶体模板的排列更加紧密有序,缺陷减少,纳米颗粒的粒径与原钛酸钡粉体的粒径基本一致,利用不同凝胶可获得LS2、LS4、LS6型结构及层-层复合结构.     

超导约瑟夫森结在外光场下的数-相压缩效应

以约瑟夫森结为主要元件的量子计算机有广阔的应用前景.本文用纠缠态表象对超导约瑟夫森结进行研究,不但可以展现约瑟夫森结的隧穿电流,还能给出库珀对数-相的不确定关系.此基础上,探讨在外光场作用下约瑟夫森结的数-相压缩效应,即约瑟夫森结中的位相和库珀对数目的变化.同时推导出外光场作用下约瑟夫森结中的超导电流以及库珀对数-相所满足的不确定关系.     

Theoretical analysis of stack gas emission velocity measurement by optical scintillation

Theoretical analysis for an online measurement of the stack gas flow velocity based on the optical scintillation method with a structure of two parallel optical paths is performed. The causes of optical scintillation in a stack are first introduced. Then, the principle of flow velocity measurement and its mathematical expression based on cross correlation of the optical scintillation are presented. The field test results show that the flow velocity measured by the proposed technique in this article is consistent with the value tested by the Pitot tube. It verifies the effectiveness of this method. Finally, by use of the structure function of logarithmic light intensity fluctuations, the theoretical explanation of optical scintillation spec- tral characteristic in low frequency is given. The analysis of the optical scintillation spectrum provides the basis for the measurement of the stack gas flow velocity and particle concentration simultaneously.     

Near-field multiple super-resolution imaging from Mikaelian lens to generalized Maxwell's fish-eye lens

Super-resolution imaging is vital for optical applications, such as high capacity information transmission, real-time bio-molecular imaging, and nanolithography. In recent years, technologies and methods of super-resolution imaging have attracted much attention. Different kinds of novel lenses, from the superlens to the super-oscillatory lens, have been designed and fabricated to break through the diffraction limit. However, the effect of the super-resolution imaging in these lenses is not satisfactory due to intrinsic loss, aberration, large sidebands, and so on. Moreover, these lenses also cannot realize multiple super-resolution imaging. In this research, we introduce the solid immersion mechanism to Mikaelian lens (ML) for multiple super-resolution imaging. The effect is robust and valid for broadband frequencies. Based on conformal transformation optics as a bridge linking the solid immersion ML and generalized Maxwell's fish-eye lens (GMFEL), we also discovered the effect of multiple super-resolution imaging in the solid immersion GMFEL.     

高比表面积铝土矿载体的制备及在CO氧化反应中的应用

采用水热法,对天然铝土矿进行改性,获得高比表面积的铝土矿载体(Bauxite)。用等体积浸渍法制备了不同Pt含量的Pt/bauxite和1.0%Pt/Al2O3催化剂,以CO氧化为探针反应,考察了催化剂性能。采用XRF、XRD、低温N2-物理吸附、H2-TPR以及CO-TPD等对载体和催化剂样品进行表征。结果表明:Pt/bauxite催化剂具有优异的CO氧化性能,特别是当反应温度为200℃时,催化剂1.0%Pt/bauxite的CO转化率为93.4%,而1.0%Pt/Al2O3CO转化率仅为9.4%。其原因是铝土矿含有的Fe2O3是CO氧化反应的催化剂,且Fe2O3与负载的Pt之间发生了相互作用,降低了Pt和Fe2O3还原温度,提高了对CO的吸附能力且降低了CO的脱附温度,进而提高了催化剂的CO氧化反应性能。     

汽车制动噪声的研究

近年来,随着人们环保意识的增强,汽车制动产生的噪声污染备受关注.本文分析了汽车制动噪声产生的特点,并从实验和理论两方面系统回顾了制动噪声的研究工作,重点对各种制动噪声的机理进行了分析和评述.最后,指出目前制动噪声研究工作的不足,并对未来的研究工作提出了一些展望和建议.     

Existence of solutions for fourth-order boundary value problem with parameter

This paper is a sequel to a previous paper (Yang,Y.and Zhang,J.H.Existence of solutions for some fourth-order boundary value problems with parameters.Nonlinear Anal.69(2),1364–1375 (2008)) in which the nontrivial solutions to the fourthorder boundary value problems were studied.In the current work with the same conditions near infinity but different near zero,the positive,negative,and sign-changing solutions are obtained by the critical point theory,retracting property,and invariant sets.     

Correlation dynamics of a qubit–qutrit system in a spin-chain environment with Dzyaloshinsky–Moriya interaction

We study the dynamics of correlations for a hybrid qubit-qutrit system in an XY spin-chain environment with Dzyaloshinsky-Moriya interaction. Our discussion involves a comparative analysis of negativity, quantum discord, and measurement-induced disturbance. It is found that the quantum discord is optimal of the three quantum correlations to de- tect the critical point of quantum phase transition. Only when the qubit interacts with the environment, is the phenomenon of sudden transition between the classical correlation and the quantum discord observed. Moreover, the Dzyaloshinsky- Moriya interaction enhances the decay of quantum correlations.     

三元异质结构Ag-Bi2MoO6/BiPO4光催化剂高效降解苯酚红

多组分复合体系有利于电荷的有效分离,减少电子空穴对的复合几率。通过低温液相法首次合成Ag-Bi₂MoO₆/BiPO₄三元异质结构光催化剂。利用XRD、SEM、EDX及XPS等技术对样品进行了表征。结果表明,Ag纳米粒子光照积累在Bi₂MoO₆/BiPO₄的表面,通过表面等离子共振增加对可见光的吸收,同时作为电子受体促进了光生电子的转移。Ag、BiPO₄和Bi₂MoO₆形成三元异质结构有效地抑制了光生电子空穴对的复合。Ag-Bi₂MoO₆/BiPO₄表现出优异的光催化性能,其光催化活性较BiPO₄、Bi₂MoO₆和Bi₂MoO₆/BiPO₄样品有较大提高。并且对Ag-Bi₂MoO₆/BiPO₄三元异质结构的光催化机制进行了讨论。光催化过程中反应活性物种捕获实验结果表明h⁺和O₂^·-是主要的活性基团.