Investigation on the Flow Field Entropy Structure of Non-Synchronous Blade Vibration in an Axial Turbocompressor

In order to explore the inducing factors and mechanism of the non-synchronous vibration, the flow field structure and its formation mechanism in the non-synchronous vibration state of a high speed turbocompressor are discussed in this paper, based on the fluid–structure interaction method. The predicted frequencies f_BV (4.4EO), f_AR (9.6EO) in the field have a good correspondence with the experimental data, which verify the reliability and accuracy of the numerical method. The results indicate that, under a deviation in the adjustment of inlet guide vane (IGV), the disturbances of pressure in the tip diffuse upstream and downstream, and maintain the corresponding relationship with the non-synchronous vibration frequency of the blade. An instability flow that developed at the tip region of 90% span emerged due to interactions among the incoming main flow, the axial separation backflow, and the tip leakage vortices. The separation vortices in the blade passage mixed up with the tip leakage flow reverse at the trailing edge of blade tip, presenting a spiral vortex structure which flows upstream to the leading edge of the adjacent blade. The disturbances of the spiral vortexes emerge to rotate at 54.5% of the rotor speed in the same rotating direction as a modal oscillation. The blade vibration in the turbocompressor is found to be related to the unsteadiness of the tip flow. The large pressure oscillation caused by the movement of the spiral vortex is regarded as the one of the main drivers for the non-synchronous vibration for the present turbocompressor, besides the deviation in the adjustment of IGV.     

矩阵方程X+A*X-qA=Q(q≥1)的 Hermitian正定解

本文研究矩阵方程X+A*X-qA=Q(q≥1)的Hermitian正定解,给出了存在正定解的充分条件和必要条件,构造了求解的迭代方法.最后还用数值例子验证了迭代方法的可行性和有效性.     

扩展的Hellinger-Reissner原理及特殊层合杂交应力元

建立了一种非匀质材料新的、扩展的H ellinger-Reissner原理,发展了当一个单元域划分为不同材料特性子域、其元内应力场沿子域表面不连续、且位移场在子域表面也急剧变化时,一个非匀质有限元刚度列式便利方法.这种列式亦可用于对每层横向剪应变均独立处置的厚层板.基于此变分原理建立了新的具有一个无外力圆柱表面的层合杂交应力元,单元各层独立假定的应力场通过以自然坐标表示的非协调位移为权函数使齐次平衡方程变分满足的理性方法及严格满足给定圆柱面上无外力条件得到,位移场在元间及层间连续条件则分别通过Lagrange乘子进行了松弛.数值算例表明:这类新型元可有效地分析具有多类圆柱形槽孔的厚、中厚及薄层板自由孔边应力分布.     

Synthesis of TiO2/S@PPy composite for chemisorption of polysulfides in high performance Li-S batteries

Journal of Solid State Electrochemistry - The commercial application of lithium-sulfur (Li-S) battery is hampered by the insulating characteristic and dissolution problem of sulfur and lithium...     

非平衡大气辐射强度与透过率的Line-By-Line计算模式

导出了非局域热力学平衡(NLTE)大气辐射强度与透过率的基本公式,以及NLT和LTE的线强、光学厚度和透过率的关系。假设转动能级是热力学平衡(LTE)的,建立了一个精确的Line-by-LineNLTE辐射强度与透过率的有效算法来计算较高层行星大气红外活跃样品的辐射强度。计算了地球大气¹⁶O₃9.6μm带在白天、夜晚和NLTE、LTE条件下的临边光谱辐射强度、线积分辐射强度、带积分辐射强度和合成光谱辐射强度,揭示了NLTE辐射强度对LTE辐射强度有显著而重要的偏离。     

Multiple positive solutions to multipoint one-dimensional <Emphasis Type="Italic">p</Emphasis>-Laplacian boundary value problem with impulsive effects

In this paper, using a fixed point theorem on a convex cone, we consider the existence of positive solutions to the multipoint one-dimensional p-Laplacian boundary value problem with impulsive effects, and obtain multiplicity results for positive solutions.     

Ultrasensitive electrochemiluminescent brombuterol immunoassay by applying a multiple signal amplification strategy based on a PAMAM-gold nanoparticle conjugate as the bioprobe and Ag@Au core shell nanoparticles as a substrate

Microchimica Acta - A multiple amplified electrochemiluminescence immunosensor is described for the determination of the illicit β-adrenergic agonist brombuterol. Firstly, cystein-coated...     

Ultrasensitive competitive electrochemiluminescence immunoassay for the β-adrenergic agonist phenylethanolamine A using quantum dots and enzymatic amplification

Microchimica Acta - We have designed an ultrasensitive electrochemiluminescence (ECL) immunoassay for the determination of the β-adrenergic agonist phenylethanolamine A (PA). It is based on...     

Preparation of orange-red fluorescent gold nanoclusters using denatured casein as a reductant and stabilizing agent,and their application to imaging of HeLa cells and for the quantitation of mercury(II)

We describe a method for the preparation of water-soluble gold nanoclusters (Au-NCs) from chloroauric acid using denatured-casein as both a reducing and stabilizing agent. The resulting Au-NCs were characterized by photoluminescence, UV–vis absorption, and X-ray photoelectron spectroscopies, and by transmission electron microscopy. The Au-NCs have an average diameter of 1.7 ± 0.2 nm and exhibit orange-red fluorescence emission peaking at 600 nm (with a Stokes’ shift as large as 237 nm), a quantum yield of 4.3 %, and good stability over the physiologically relevant range of pH values and ionic strength. Cytotoxicity studies showed the Au-NCs to display negligible effects in terms of altering cell proliferation or triggering apoptosis. Fluorescence imaging of HeLa cancer cells was accomplished by loading such cells with the Au-NCs. The fluorescence of the Au-NCs is found to be strongly quenched by Hg(II) ions, and thus the Au-NCs can be used for detecting and, possibly, imaging of Hg(II). An assay was worked out for the determination of Hg(II), and its limit of detection is 1.83 nM, which is 5.5 times lower than the maximum allowed concentration of Hg(II) in drinking water as defined by the US EPA.

Denatured-casein was firstly used as a reductant and stabilizing agent in facile preparation of orange-red fluorescent AuNCs for imaging of HeLa cells and for the quantitation of mercury(II)

     

一类新的具有无外力圆柱表面的杂交应力元

根据Hellinger-Reissner原理,建立了进一步改进的具有一个无外力圆柱表面三维杂交应力元.元内假定应力场满足以柱坐标表示的平衡方程,及圆柱面上的无外力边界条件.当退化为二维时,也满足协调方程.数值算例表明,当分析带圆弧的槽孔板、块时,在稀疏的有限元网格下,这类单元即可提供较以前各类特殊元、一般假定位移元及一般假定应力元远为准确的三维及二维应力分布.