A Numerical Study for Turbulent Flow and Thermal Influence Over Inhomogenous Canopy of Roughness Elements

A large-eddy simulation with transitional structure function(TSF) subgrid model we previously proposed was performed to investigate the turbulent flow with thermal influence over an inhomogeneous canopy, which was represented as alternative large and small roughness elements. The aerodynamic and thermodynamic effects of the presence of a layer of large roughness elements were modelled by adding a drag term to the three-dimensional Navier-Stokes equations and a heat source/sink term to the scalar equation, respectively. The layer of small roughness elements was simply treated using the method as described in paper (Moeng 1984, J. Atmos Sci. 41, 2052-2062) for homogeneous rough surface. The horizontally averaged statistics such as mean vertical profiles of wind velocity, air temperature, et al., are in reasonable agreement with Gao et al.(1989, Boundary layer meteorol. 47, 349-377) field observation (homogeneous canopy). Not surprisingly, the calculated instantaneous velocity and temperature fields show that the roughness elements considerably changed the turbulent structure within the canopy. The adjustment of the mean vertical profiles of velocity and temperature was studied, which was found qualitatively comparable with Belcher et al. (2003, J Fluid Mech. 488, 369-398)'s theoretical results. The urban heat island(UHI) was investigated imposing heat source in the region of large roughness elements. An elevated inversion layer, a phenomenon often observed in the urban area (Sang et al., J Wind Eng. Ind. Aesodyn. 87, 243-258)'s was successfully simulated above the canopy. The cool island(CI) was also investigated imposing heat sink to simply model the evaporation of plant canopy. An inversion layer was found very stable and robust within the canopy.

Variable power singular interface elements for a crack normal to the bimaterial interface

Zero thickness crack tip interface elements for a crack normal to the interface between two materials are presented. The elements are shown to have the desired r(lambda-1) (0 < lambda < 1) singularity in the stress field at the crack tip and are compatible with other singular elements. The stiffness matrices of the quadratic and cubic interface element are derived. Numerical examples are given to demonstrate the applicability of the proposed interface elements for a crack perpendicular to the bimaterial interface.

Inhomogeneous isoparametric elements for stress analysis of composites

The concept of inhomogeneous element is proposed and the formulations of the inhomogeneous isoparametric elements for stress analysis of four kinds of problems are derived. As an example of applications of the inhomogeneous elements, the stress distribution in a cone-like composite syntheticrope termination is calculated.

Effects of sensing temperature on the NO2-sensing properties of octa-iso-pentyloxymetallonaphthalocyanine spin-coated films

A kind of 1,6,10,15,19,24,28,33-octa-iso-pentyloxy-2,3-metallonaphthalocyanines complexes MNc(iso-PeO)(8) (M = Co, Cu, Pd) are used as spincoating film-forming materials. The surface morphologies of the films prepared were studied first. These films were then used for the experiments of NO2 sensing. The effects of sensing temperature as well as the NO concentration on the sensing properties were studied. The experimental results showed that the three MNc(iso-PeO)(8) films were uniform, smooth and dense. Due to the different metal ions (M) on the center of naphthalocyanine, the CoNc(iso-PeO)(8) film had a higher film resistance and response-recovery rate in the NO2 sensing experiments. On the contrary, the response to NO2 of the PdNc(iso-PeO)(8) and CuNc(iso-PeO)(8) films were superior to that of CoNc(iso-PeO)(8). By varying the sensing temperature, it was found that the elevation of sensing temperature could improve the sensing response, recovery ratio, and sensitivity of the sensing films. At high concentrations of NO2, the response time became shorter. (c) 2007 Elsevier B.V. All rights reserved.

Preparation, characterization and gas sensing properties of nickel octa-iso-pentyloxynaphthalocyanine spin-coating films

Spin-coated films of nickel 1,6,10,15,19,24,28,33-octa-iso-pentyloxy-2,3-naphthalocyanine complex were obtained and characterized by UV-vis absorption spectroscopy. A linear relationship between the absorbance and solution concentration was observed. Low concentration solutions could afford smooth and homogeneous film surfaces as indicated by atomic force microscopy. The film structure was studied by small angle X-ray diffraction. The films were used for NO2 sensing experiments. The results indicate that the elevation of sensing temperature can shorten the response time and increase recovery ratio and response magnitude of the sensing films. High NO2 concentration can also shorten response time. (C) 2008 Elsevier B.V. All rights reserved.

Identification of the Angel-related elements in cyprinid fishes and their phylogenetic implications

Angel-related element belongs to the family of miniature inverted-repeat transposable elements (MITEs). In this paper we report the identification of an Angel-related element in the series Leuciscini of cyprinid fishes, which is located in the second intron of the growth hormone (GH) gene. We have also found that this element is absent in orthologous locus in the series Barbini of cyprinid fishes, that provides new evidence for the monophyly of the series Leuciscini. The insertion of Angel-related element into the GH gene might take place in the common ancestor of the series Leuciscini after its divergence from the series Barbini. The high sequence divergence and relatively broad species distribution of Angel-related elements implies that they might be ancient transposons which appeared about 26 million years ago.

Total and subcellular distribution of trace elements in the liver of a mother-fetus pair of Dall's porpoises (Phocoenoides dalli)

Total and subcellular hepatic Zn, Cu, Se, Mn, V, Hg, Cd, and Ag were determined in a mother-fetus pair of Dall's porpoises (Phocoenoides dalli). Except for higher fetal Cu concentration, all maternal elements were higher. Elements existed mostly in the cytosol of both animals except in the case of maternal Ag in the microsome and fetal Cu and Ag in the nuclei and mitochondria. In the maternal cytosol, Zn, Mn, Hg, and Ag were present in the high-molecular-weight substances (HMW); Se and V were present in the low-molecular-weight substances (LMW); Cu and Cd were mostly sequestered by metallothionein (MT). In the fetal cytosol, Zn, Se, Mn, Hg, Cd, and Ag were present in the HMW and V in the LMW, while Cu and Ag were mostly associated with MT. MT isoforms were characterized using the HPLC/ICP-MS. Two and four obvious peaks appeared in the maternal and fetal MT fractions, respectively. The highest elemental ion intensities were at a retention time of 7.8 min for the mother, and for the fetus the peak elemental ion intensities occurred at a retention time of 4.3 min, suggesting that different MT isoforms may be involved in elemental accumulation in maternal and fetal hepatocytosols. (C) 2003 Elsevier Ltd. All rights reserved.

Kinetic studies on the effects of rare earth elements (REES) on the growth of Microcystis and their accumulation by Microcystis

In the paper the kinetic effects of La3+ and Ce4+ on the growth of Microcystis and the accumulation kinetics of Microcystis in the single and combined systems of La3+ and Ce4+ were studied. The mechanism of the effects of La3+ and Ce4+ on the growth of Microcystis and their accumulation kinetics were also discussed. In the single system, La3+ stimulated the growth of Microcystis at initial concentrations below 2 mg / 1, but inhibited it above 2 mg / 1. Ce4+ accelerated the growth of Microcystis at initial concentrations below 0.2 mg / 1 and inhibited at above 0.2 mg /l. Furthermore, the stimulation weakened with the increase of initial concentrations of La3+ and Ce4+. In the combined system, the growth of Microcystis was accelerated in the over all cases. In the single system, the amount of La3+ and Ce4+ uptake was more at higher initial concentrations than at lower ones. At the same initial concentrations, La3+ and Ce4+ uptake in the combined system was less than that in the single system. The kinetic process of La3+ and Ce4+ adsorpted by Microcystis can be explained with the second order kinetics adsorption model.

When Does a Polynomial Over a Finite Field Permute the Elements of the Field?

We present a class of indecomposable polynomials of non prime-power degree over the finite field of two elements which are permutation polynomials on infinitely many finite extensions of the field. The associated geometric monodromy groups are the simple ...

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中国计算机学会