A methodology for high performance computation of fully inhomogeneous turbulent flows

A large‐eddy simulation methodology for high performance parallel computation of statistically fully inhomogeneous turbulent flows on structured grids is presented. Strategies and algorithms to improve the memory efficiency as well as the parallel performance of the subgrid‐scale model, the factored scheme, and the Poisson solver on shared‐memory parallel platforms are proposed and evaluated. A novel combination of one‐dimensional red–black/line Gauss–Seidel and two‐dimensional red–black/line Gauss–Seidel methods is shown to provide high efficiency and performance for multigrid relaxation of the Poisson equation. Parallel speedups are measured on various shared‐distributed memory systems. Validations of the code are performed in large‐eddy simulations of turbulent flows through a straight channel and a square duct. Results obtained from the present solver employing a Lagrangian dynamic subgrid‐scale model show good agreements with other available data. The capability of the code for more complex flows is assessed by performing a large‐eddy simulation of the tip‐leakage flow in a linear cascade. Copyright © 2006 John Wiley & Sons, Ltd.     

Adsorption of L-Alanine on Cu（111） Studied by Scanning Tunnelling Microscopy

The adsorption of L-alanine on Cu（111） surface is studied by means of scanning tunnelling microscopy under ultra-high vacuum conditions. The results show that the adsorbates are chemisorbed on the surface, and can form a two-dimensional gas phase, chain phase and solid phase, depending on deposition rate and amount. The adsorbed molecules can be imaged as individual protrusions and parallel chains in gas and chain phases respectively. It is also found that alanine can form （2 × 2） superstructure on Cu（111） and copper step facet to （110） directions in solid phase. On the basis of our scanning tunnelling microscopic images, a model is proposed for the Cu（111）（2 ×2）-alanine superstructure. In the model, we point out the close link between （110）-direction hydrogen bond chains with the same direction copper step faceting.     

X-ray reflectivity study on gold films during sputter deposition

We performed in-situ X-ray reflectivity measurements of gold films during sputter deposition on polished silicon substrates. The measurements were performed at several substrate temperatures and under two argon pressures. The gold surfaces were also examined by scanning tunneling microscopy after deposition to obtain their real-space topographic images. These images were used to complement the X-ray reflectivity measurements in determining the effect of argon pressure on the gold surface and its height-height difference functions. An approximation for height-height difference functions was employed to analyze the X-ray reflectivity data. The measured interface width during growth followed a simple power law, consistent with recent theoretical results of dynamic scaling behavior. The scaling exponents, however, do not agree well with predictions based on some models in 2 + 1 dimensions.     

动态特性的参数设计在差示光度法测金中的应用

本文提出对动态特性参数设计使用相关系数与信噪比作为内表指标进行分析 ,并使用该分析方法优化了差示光度法测较高浓度金矿样的试验条件。     

Highly sensitive and interference-free determination of bismuth in environmental samples by electrothermal vaporization atomic fluorescence spectrometry after hydride trapping on iridium-coated tungsten coil

Bismuthine was on-line trapped on tungsten coil and subsequently electrothermally vaporized for the determination by atomic fluorescence spectrometry (AFS). Several noble metals, including Pd, Rh, Pt, and Ir, were explored as permanent chemical modifier for tungsten coil on-line trapping. Investigation showed that Ir gave the best performance, in which bismuthine was on-line trapped on Ir-coated tungsten coil at 560 °C, and then released at 1550 °C for subsequent transfer to AFS by a mixture of Ar and H₂. Under optimum instrumental conditions, the trapping efficiency was found to be 73 ± 3%. With 120 s (12 mL sample volume) trapping time, a limit of detection (LOD) of 4 ng L^− 1 was obtained, compared to conventional hydride generation AFS (0.09 μg L^− 1); the LOD can be lowered down to 1 ng L^− 1 by increasing the trapping time to 480 s. The LOD was found to be better or at least comparable to literature levels involving on-line trapping and some other sophisticated instrumental methods such as ICP-MS and GF-AAS. A comprehensive interference study involving conventional hydride-forming elements and some transition metals was carried out, and the result showed that the gas phase interference from other hydride-forming elements was largely reduced, thanks to the use of on-line tungsten coil trapping. Finally, the proposed method was applied to the determination of bismuth in several biological and environmental standard reference materials, and a t-test shows that the analytical results by the proposed method have no significant difference from the certified values at the confidence level of 95%.     

Electron spin resonance study on UV-irradiated single crystal of (NH3iPr)6[Mo8O28(CHO)2] · 2H2O

EPR study on UV-irradiated single crystal of (NH₃iPr)₆ [Mo₈ O₂₈(CHO)₂]·2H₂O was carried out at room temperature. Three sets of EPR lines were observed. Spectra I and II are attributed respectively to paramagnetic Mo (V) centre (A) and (B). Line III may be assigned to an unstable-paramagnetic centre. Using the least-squares-fitting method to calculate the Hamiltonian parameters, we got the accurate principal values of g, hyperfine A_MO and ligand hyperfine A_H tensors, as well as-the direction cosines of their principal axes with respect to experimental coordinate system (xyz). The electron spin density was calculated from A value. The results showed that the unpaired electron occupies 4d orbital of molybdenum which appreciably contributes to the molecular orbital and the mechanism of direct spin coupling between the unpaired spin orbital of molybdenum and hydrogen orbital.     

A Gold Electrode QCM Study on the Self-Assembling Process of Thioglycollic Acid in Aqueous Solution

Quartzcrystalmicrobalance(QCM)iswellknownasanexcellenttoolforthestudyofchemicaland/orphysicalprocessesonthesolidsurfaceaccompaniedbymasschangedowntoananogramlevell.Inaddition,itiswellestablishedthatathiol-containingcompoundisabletoadsorbonsomesubstrates(e.g.,An,Cu,andCd)toformaself-assembledmonolayerbythewell-knownchemicalreactionofthethiolgroupwiththesubstrate2.Tothebestofourknowledge,therearenoreportsontheself-assemblingprocessesofalkanethiolcompoundsinaqueoussolutionswithQCMteclmique.In…     

关于L-fuzzifying TOP范畴

In this paper,the category of L-FTOP and the relations with the categories of TOP,Lα-FTOP are discussed.