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991.
The main objective of this study is to compare the influence of different boundary conditions upon the incompressible Poiseuille –Bénard channel flow (PBCF) in a 2D rectangular duct heated from below. In a first technical part the algorithm used to carry out this work, based on the augmented Lagrangian method, is presented. The implementation details of the five different open boundary conditions (OBCs) and the periodic boundary conditions (PBCs) tested in the present paper are also given. The study is then carried out for 1800<Ra≤ 10,000, 0<Re≤10 and 0·67≤Pr≤6·4. The five selected OBCs, applied at the outlet of the computational domain, respectively express the following conditions: a square profile for the velocity (OBC1), mass conservation (OBC2), zero second derivative of the horizontal velocity component (OBC3), a mixed boundary condition combining Dirichlet and Neumann conditions (OBC4) and an Orlanski-type boundary condition (OBC5). A good estimation of the perturbation amplitude and of the length of the perturbed zone at the outlet boundary is proposed. It is shown that OBC5 causes very little perturbation in the recirculating flow compared with the other OBCs. © 1997 John Wiley & Sons, Ltd. 相似文献
992.
水稻第9号染色体DNA文库的构建 总被引：2，自引：0，他引：2
运用染色体显微分离技术构建了水稻第９号（Ｋ１０）染色体的ＤＮＡ文库,连接物转化大肠杆菌ＤＨ５α共获得４５０００多个重组克隆．随机选取了１００个重组克隆进行分析,插入序列的大小为８０～５００ｂｐ,平均２１０ｂｐ 相似文献
993.
994.
《Natural product research》2012,26(4):277-280
Abstract Microbial O-dealkylation of (+)-dialkyl pinoresinols by Aspergillus niger has been investigated. (+)-Diethyl pinoresinol could be transformed to (+)-monoethyl pinoresinol and then (+)-pinoresinol, while the other derivatives carrying a longer alkyl group than propyl at the p-position were not exposed to O-dealkylation. 相似文献
995.
《Natural product research》2012,26(2):99-106
Abstract The iridoid 2′-coumaroyl mussaenosidic acid, isolated from Avicennia germinans (Avicenniaceae), was analysed by NMR and molecular modeling: two isomeric forms were confirmed. In addition, the known compound 1 (6S, 9R) roseoside was isolated for the first time from this species of Avicennia. 相似文献
996.
《液相色谱法及相关技术杂志》2012,35(3):390-404
A novel fluorescent probe, 1-[1,2,5,6-dibenzocarbazol-9-yl]propan-2-yl chloroformate (DBCPC-Cl) has been designed and synthesized for amine labeling in HPLC. Using 12 aliphatic amines as the models, the derivatization conditions were optimized. In 0.2 mol/L borate buffer (pH 9.0), amines reacted with DBCPC-Cl at 30°C to form the derivatives in 3 min, and the derivatives were stable enough to be efficiently analyzed by HPLC. The separation of these amine derivatives was achieved with a C8 column and gradient elution by using 30% acetonitrile (containing 20 mmol/L formic acid) and 100% acetonitrile, and online APCI/MS identification of the derivatives was carried out in positive-ion mode. The fluorescence responses for DBCPC-derivatives were higher relative to those obtained using previously reported reagents. With fluorescence detection at an emission wavelength of 390 nm and an excitation wavelength of 300 nm, the detection limits of aliphatic amines were 0.3 – 5.1 fmol (at a signal-to-noise ratio of 3:1). The relative standard deviations for within-day determination (n = 12) were 0.051–0.079% for retention time and 0.84–1.12% for peak area for the tested aliphatic amines. The mean intra- and inter-assay precision for all amines levels were <2.52% and 3.74%, respectively. The mean recoveries ranged from 86.9 to 104.7%. Excellent linear responses were observed with coefficients >0.9991. 相似文献
997.
本文在深入学习FlexRay总线的基础之上,研究分析汽车发动机控制系统的构成,并提出一种用FlexRay总线来实现对其控制的设计。文中采用飞思卡尔高性能单片机MC9S12XF512,独立通信控制器MFR4310和FlexRay总线驱动器TJA1080,给出电路整体设计方案及软件设计流程,对汽车FlexRay总线的发动机控制系统节点开发具有一定的参考价值。 相似文献
998.
Enhancing the efficiency of charge carrier separation is crucial for improving the performance of photocatalysts, thereby offering more effective solutions to energy and environmental pollution challenges. In this study, a carbon-deficient ultra-thin porous g-C3N4 (Vc-UPCN) was synthesized and subsequently was integrated with Bi2Fe4O9 (BFO) using a sonochemical self-assembly technique, a Bi2Fe4O9/Vc-UPCN (BC) photocatalyst featuring a Z-scheme heterojunction. The BC catalyst was subjected to corona poling treatment to obtain BCp, which possesses an intrinsic electric field. Compared with pure BFO and Vc-UPCN, the BC heterojunction exhibited higher photo-generated electron–hole separation efficiency and photodegradation ability. Upon introduction of corona polarization, the photocatalytic performance of BC was further enhanced. Specifically, BCp-15 (BFO/BC mass fraction = 15) achieved complete degradation of methylene blue (MB) within 30 min. BCp-15 demonstrated that its degradation efficiency for MB was 1.28 times higher than that of BC-15, 1.85 times higher than that of Vc-UPCN, and impressive 7.69 times higher than that of pure BFO. The coupling effect of the heterojunction and ferroelectric polarization significantly improved the separation efficiency of photo-generated carriers in BCp. This study is expected to provide a reference for the synergistic application of heterojunction and ferroelectric polarization in traditional semiconductor photocatalysis. 相似文献
999.
In accelerator RF cavities, there exists not only the fundamental mode which is used to accelerate the beam, but also higher order modes(HOMs). The higher order modes excited by the beam can seriously affect beam quality, especially for the higher R/Q modes. 1.3 GHz low-loss 9-cell superconducting cavity as a candidate for ILC high gradient cavity, the properties of higher order mode has not been studied carefully. IHEP based on existing low loss cavity, designed and developed a large grain size 1.3 GHz low-loss 9-cell superconducting cavity(IHEP02cavity). The higher order mode coupler of IHEP02 used TESLA coupler's design. As a result of the limitation of the mechanical design, the distance between higher order mode coupler and end cell is larger than TESLA cavity.This paper reports on measured results of higher order modes in the IHEP02 1.3 GHz low-loss 9-cell superconducting cavity. Using different methods, Q e of the dangerous modes passbands have been obtained. The results are compared with TESLA cavity results. R/Q of the first three passbands have also been obtained by simulation and compared with the results of the TESLA cavity. 相似文献
1000.
B. Roman P. M. Reis B. Audoly S. De Villiers V. Vigui D. Vallet 《Comptes Rendus Mecanique》2003,331(12):811-816
We report a novel mode of quasi-static oscillatory crack propagation when a cutting tip of moderately large width is driven through a thin brittle polymer film. Experiments show that the amplitude and wavelength of the oscillatory crack paths scale linearly with the width of the cutting tip over a wide range of length scales but are independent of the width of the sheet and of the cutting speed. We propose a mechanism for this instability, based on the coupling between crack propagation and out-of-plane deformations of the film. To cite this article: B. Roman et al., C. R. Mecanique 331 (2003). 相似文献