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61.
Developing Couette–Poiseuille flows at Re=5000 are studied using a low Reynolds number k–ϵ two‐equation model and a finite element formulation. Mesh‐independent solutions are obtained using a standard Galerkin formulation and a Galerkin/least‐squares stabilized method. The predictions for the velocity and turbulent kinetic energy are compared with available experimental results and to the DNS data. Second moment closure's solutions are also compared with those of the k–ϵ model. The deficiency of eddy viscosity models to predict dissymmetric low Reynolds number channel flows has been demonstrated. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
62.
Stanislas Vertu Jean-Jacques Delaunay Ichiro Yamada Olivier Haeberlé 《Central European Journal of Physics》2009,7(1):22-31
Diffraction microtomography in coherent light is foreseen as a promising technique to image transparent living samples in
three dimensions without staining. Contrary to conventional microscopy with incoherent light, which gives morphological information
only, diffraction microtomography makes it possible to obtain the complex optical refractive index of the observed sample
by mapping a three-dimensional support in the spatial frequency domain. The technique can be implemented in two configurations,
namely, by varying the sample illumination with a fixed sample or by rotating the sample using a fixed illumination. In the
literature, only the former method was described in detail. In this report, we precisely derive the three-dimensional frequency
support that can be mapped by the sample rotation configuration. We found that, within the first-order Born approximation,
the volume of the frequency domain that can be mapped exhibits a missing part, the shape of which resembles that of an apple
core. The projection of the diffracted waves in the frequency space onto the set of sphere caps covered by the sample rotation
does not allow for a complete mapping of the frequency along the axis of rotation due to the finite radius of the sphere caps.
We present simulations of the effects of this missing information on the reconstruction of ideal objects.
相似文献
63.
64.
Sur un problème de type elliptique parabolique non linéaireOn a nonlinear elliptic-parabolic problem
We study the general equation b(u)t=a(u,?(u)x)x+f of elliptic-parabolic type. Using the theory of evolution equation governed by accretive operator, we establish existence and uniqueness of mild solutions to the associate Cauchy problem, under general assumptions on the data. With additional structural condition of Alt–Luckhauss type, we show that the mild solutions are weak solutions. To cite this article: S. Ouaro, H. Touré, C. R. Acad. Sci. Paris, Ser. I 334 (2002) 27–30 相似文献
65.
The effect of pulsed jet vortex generators on the structure of an adverse pressure gradient turbulent boundary layer flow was investigated. Two geometrically optimised vortex generator configurations were used, co-rotating and counter-rotating. The duty cycle and pulse frequency were both varied and measurements of the skin friction (using hot films) and flow structure (using stereo PIV) were performed downstream of the actuators. The augmentation of the mean wall shear stress was found to be dependent on the net mass flow injected by the actuators. A quasi steady flow structure was found to develop far downstream of the injection location for the highest pulse frequency tested. The actuator near field flow structure was observed to respond very quickly to variations in the jet exit velocity. 相似文献
66.
Ying Zhang Ming Zhao Cheng-Bo Wang Yu Wang Stanislas Nsanzamahoro Ling-Ling Zhu Wei-Feng Wang Jun-Li Yang 《Electrophoresis》2022,43(15):1601-1610
Prolyl hydroxylase domain 2 (PHD2) is a key enzyme regulating the expression of hypoxia inducible factor (HIF). Its inhibitors can improve the expression of HIF and downstream genes, which can treat hypoxia-related diseases. Therefore, the establishment of a reliable PHD2 inhibitors screening method is of great significance for the drug development of hypoxia-related diseases. In this work, an accurate, rapid, and simple screening method for PHD2 inhibitors was introduced by capillary zone electrophoresis (CZE). In order to improve the detection sensitivity, the derivative reaction of α-ketoglutaric acid (α-OG) and 1,2-diaminobenzene (OPD) was used to enhance the UV absorption of α-OG (the substrate in the enzymatic reaction). The CZE method selected 20 mM Na2B4O7 buffer (pH 9.0) as the separation buffer, +25 kV as the separation voltage, 25°C as the cartridge temperature, and 210 nm as the detection wavelength. Under this condition, the analysis of a single sample can be realized within 9 min. Compared with the existing reported methods, the present work can directly screen the PHD2 inhibitory activity of traditional Chinese medicine (TCM) extracts, which is of significance for the target-purification of bioactive individual compounds from TCMs. Under the optimal conditions, the PHD2 inhibitor screening platform was successfully established, and it was found that 70% methanol/water extracts of Astragali Radix and Codonopsis pilosula had good PHD2 inhibitory activity. Furthermore, the present work provides a novel approach for screening the PHD2 inhibitory activity of TCM extracts and the discovery of anti-hypoxia bioactive compounds. 相似文献
67.
Asymptotical properties of orthogonal polynomials from the so-called Szeg? class are very well-studied. We obtain asymptotics of orthogonal polynomials from a considerably larger class and we apply this information to the study of their spectral behavior. To cite this article: S. Denisov, S. Kupin, C. R. Acad. Sci. Paris, Ser. I 339 (2004). 相似文献
68.
We have recently described a new synthetic route which has been used in our laboratory for the preparation of several novel heterocyclic systems comprising, the I,l-dimethylthiazolidino[3,4-o)piperazine-5,8- dione-3-carboxylic acid and the 2,2-dimethylthiazolidino[3,2-a]piper- azine-5,8-dione-3-carboxylic acid (8). The former was obtained with quan- titative yield and the latter with 71% yield. As a development of our studies on novel 2,5-piperazinedione systems, we describe in this report, the synthesis of the (2,5-dioxopiperazinyl)2-isobutyric acid (9), then-butyl(2-isopropyl)3,6-dioxopiperazinyl-l) acetate (1 l), and another synthetic route, illustrated in Scheme I, by which the compound 8 was obtained with quantitative yield. Spectrometric data were obtained and their interpretation confirms the proposed structure of the new compounds. 相似文献
69.
An effective synthesis of 4-(5-iodo-3-methylpyrazolyl) phenylsulfonamide has been developed. This aromatic iodide template served as an efficient oxidative addition partner for the preparation of a solution-phase library of Celecoxib analogues via Suzuki coupling using Pd/C, a readily filterable catalyst. 相似文献
70.
Main results of the third international PIV Challenge 总被引:5,自引:4,他引:1
M. Stanislas K. Okamoto C. J. Kähler J. Westerweel F. Scarano 《Experiments in fluids》2008,45(1):27-71
This paper presents the main results of the third international PIV Challenge which took place in Pasadena (USA) on the 19th
and 20th of September 2005. This workshop was linked to the PIV05 International Symposium held at the same place the same
week. The present contribution states the objectives of the challenge, describes the test cases and the algorithms used by
the participants, and presents the main results together with some discussion and conclusions on the accuracy and robustness
of various PIV and PTV algorithms. As the entire amount of results obtained cannot be detailed, this contribution is written
as a guide for the use of the full database of images and results which is available at . 相似文献