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101.
102.
Chuong V. Nguyen Thien D. Nguyen John C. Wells Akihiko Nakayama 《Experiments in fluids》2010,48(4):577-587
PIV measurements near a wall are generally difficult due to low seeding density, low velocity, high velocity gradient, and
strong reflections. Such problems are often compounded by curved boundaries, which are commonly found in many industrial and
medical applications. To systematically solve these problems, this paper presents two novel techniques for near-wall measurement,
together named Interfacial PIV, which extracts both wall-shear gradient and near-wall tangential velocity profiles at one-pixel
resolution. To deal with curved walls, image strips at a curved wall are stretched into rectangles by means of conformal transformation.
To extract the maximal spatial information on the near-wall tangential velocity field, a novel 1D correlation function is
performed on each horizontal pixel line of the transformed image template to form a “correlation stack”. This 1D correlation
function requires that the wall-normal displacement component of the particles be smaller than the particle image diameter
in order to produce a correlation signal. Within the image regions satisfying this condition, the correlation function yields
peaks that form a tangential velocity profile. To determine this profile robustly, we propose to integrate gradients of tangential
velocity outward from the wall, wherein the gradient at each wall-normal position is measured by fitting a straight line to
the correlation peaks. The capability of Interfacial PIV was validated against Particle Image Distortion using synthetic image
pairs generated from a DNS velocity field over a sinusoidal bed. Different velocity measurement schemes performed on the same
correlation stacks were also demonstrated. The results suggest that Interfacial PIV using line fitting and gradient integration
provides the best accuracy of all cases in the measurements of velocity gradient and velocity profile near wall surfaces. 相似文献
103.
环丙沙星-铽络合物的荧光特性及其应用研究 总被引:3,自引:1,他引:2
中性条件下,铽(Ⅲ)与环丙沙星反应极易形成络合物。该络合物与小牛胸腺DNA分子作用后荧光强度显著增强,据此建立了简单、快速、灵敏的DNA测定方法,并优选出反应的最佳条件为:25 ℃,λex/λem =325/545 nm,Tb3+浓度5.0×10-5 mol·L-1,环丙沙星浓度1.0×10-6 mol·L-1,Tris-HCl缓冲溶液,pH 7.0。结果表明,在4.3×10-7~3.0×10-5 mol·L-1浓度范围内DNA与其荧光强度呈良好的线性关系,其线性方程为F1-F0=107c+48.00(r=0.998 8, n=8),检出限为2.8×10-9 mol·L-1。此法同时用于临床近20例全血DNA提取样本的检测,经t检验,两组在545 nm所得的荧光强度有差异(P<0.05)。 相似文献
104.
Howard Yi Fan Sim Jaslyn Ru Ting Chen Charlynn Sher Lin Koh Hiang Kwee Lee Xuemei Han Gia Chuong Phan‐Quang Jing Yi Pang Chee Leng Lay Srikanth Pedireddy In Yee Phang Edwin Kok Lee Yeow Xing Yi Ling 《Angewandte Chemie (International ed. in English)》2020,59(39):16997-17003
The electrochemical nitrogen reduction reaction (NRR) offers a sustainable solution towards ammonia production but suffers poor reaction performance owing to preferential catalyst–H formation and the consequential hydrogen evolution reaction (HER). Now, the Pt/Au electrocatalyst d‐band structure is electronically modified using zeolitic imidazole framework (ZIF) to achieve a Faradaic efficiency (FE) of >44 % with high ammonia yield rate of >161 μg mgcat?1 h?1 under ambient conditions. The strategy lowers electrocatalyst d‐band position to weaken H adsorption and concurrently creates electron‐deficient sites to kinetically drive NRR by promoting catalyst–N2 interaction. The ZIF coating on the electrocatalyst doubles as a hydrophobic layer to suppress HER, further improving FE by >44‐fold compared to without ZIF (ca. 1 %). The Pt/Au‐NZIF interaction is key to enable strong N2 adsorption over H atom. 相似文献
105.
Yu. V. Egorov Nguyen Minh Chuong Dang Anh Tuan 《Journal of Mathematical Sciences》2011,179(4):461-474
A quasilinear boundary-value problem is considered for a degenerate parabolic pseudodifferential equation in a Sobolev space. By the Laplace transformation, this problem is reduced to a boundary-value problem for a degenerate elliptic equation with a parameter. The latter problem is studied with the help of Vishik–Grushin methods and the Rothe theorem. The approach proposed differs from those previously used in relation to similar problems. 相似文献
106.
The paper is concerned with the stability theory of the efficient solution map of a parametric vector optimization problem.
Utilizing the advanced tools of modern variational analysis and generalized differentiation, we study the calmness of the
efficient solution map. More explicitly, new sufficient conditions in terms of the Fréchet and limiting coderivatives of parametric
multifunctions for this efficient solution map to have the calmness at a given point in its graph are established by employing
the approach of implicit multifunctions. Examples are also provided for analyzing and illustrating the results obtained. 相似文献
107.
We apply some advanced tools of variational analysis and generalized differentiation to establish necessary conditions for (weakly) efficient solutions of a nonsmooth semi-infinite multiobjective optimization problem (SIMOP for brevity). Sufficient conditions for (weakly) efficient solutions of a SIMOP are also provided by means of introducing the concepts of (strictly) generalized convex functions defined in terms of the limiting subdifferential of locally Lipschitz functions. In addition, we propose types of Wolfe and Mond–Weir dual problems for SIMOPs, and explore weak and strong duality relations under assumptions of (strictly) generalized convexity. Examples are also designed to analyze and illustrate the obtained results. 相似文献
108.
Yu. V. Egorov Nguyen Minh Chuong Dang Anh Tuan 《Russian Journal of Mathematical Physics》2008,15(2):222-237
Boundary value problems for degenerate semilinear elliptic pseudodifferential operators are considered. Using the apparatus
of the theory of pseudodifferential operators, function spaces introduced in [4–8], and the Rabinowitz construction [12] based
on the Borsuk theorem (see [11]), we prove the existence of solutions of the problem in suitable function spaces.
To the memory of Leonid Romanovich Volevich 相似文献