Laminar flamelet decomposition (LFD) is a dynamic approach for modelling sub-filter scale turbulence-chemistry interactions in Large-Eddy Simulations using a stretched flamelet library. In this work, the performance of the LFD model – that was previously used only in non-premixed combustion—is investigated a priori for premixed combustion using positively-strained flamelets in the reactant-to-product configuration. For this purpose, a DNS database of methane-air premixed flames is utilized. The flames are propagating in a rectangular box under homogeneous isotropic turbulence conditions over a wide range of Karlovitz numbers. The results show that the LFD model can correctly account for the sub-filter scale turbulence-chemistry interactions to predict the filtered reaction rates and the filtered scalar field, provided that turbulent and laminar mixing are well predicted. The deviations from the DNS results are attributed to the shortcomings of the strained flamelet library and the non-flamelet effects. Finally, the LFD results are compared with a different sub-filter scale model using the same strained flamlelet library, and the relative performances of the two models are discussed.—
Journal of Applied Mechanics and Technical Physics - In the present study, entropy generation in a non-axisymmetric steady-state incompressible viscous flow over a single rotating porous disk is... 相似文献
Titanium dioxide (TiO2) nanoparticles (NPs) with different sizes and structures were probed for plausible cytotoxicity using electric cell-substrate impedance sensing (ECIS), a non-invasive and on-line procedure for continuous monitoring of cytotoxicity. For insect cells (Spodoptera frugiperda Sf9), the ECIS50 values, i.e., the concentration required to achieve 50% inhibition of the response, differed depending on the size and shape of the TiO2 nanostructure. The lowest ECIS50 value (158 ppm) was observed for the needle shaped rutile TiO2 (10 nm × 40 nm, 15.5 nm nominal particle size), followed by 211 ppm for P-25 (34.1 nm, 80% anatase and 20% rutile), 302 ppm for MTI5 (5.9 nm, 99% anatase) and 417 ppm for Hombitan LW-S bulk TiO2 (169.5 nm, 99% anatase). Exposure of TiO2 NPs to UV light at 254 nm or 365 nm exhibited no significant effect on the ECIS50 value due to the aggregation of TiO2 NPs with diminishing photocatalytic activities. Chinese hamster lung fibroblast V79 cells, exhibited no significant cytotoxicity/inhibition up to 400 ppm with P25, MTI5 and bulk TiO2. However, a noticeable inhibitory effect was observed (ECIS50 value of 251 ppm) with rutile TiO2 as cell spreading on the electrode surface was prevented 相似文献
A one-pot procedure has been developed for the synthesis of (1,2,3-triazolyl) methoxyphenyl tetrahydro-5-oxo-4H-chromene derivatives by concurrent reaction of aryloxy propargylated aldehydes, various azides, active methylene compounds, and 1,3-cyclohexanediones using catalytic amounts of Cu(OAc)2 / sodium ascorbate and diammonium hydrogen phosphate in aqueous ethanol media. Excellent conversion of starting materials was achieved to the desired (1,2,3-triazolyl) methoxyphenyl tetrahydro-5-oxo-4H-chromene products. 相似文献
We study the spontaneous symmetry breaking in a conformally invariant gravitational theory. We particularly emphasize on the
nonminimal coupling of matter fields to gravity. By the nonminimal coupling we consider a local distinction between the conformal
frames of metric of matter fieldsand the metric explicitly entering the vacuum sector. We suppose that these two frames are
conformally related by a dilaton field. We show that the imposition of a condition on the variable mass term of a scalar field
may lead to the spontaneous symmetry breaking. In this way the scalar field may imitate the Higgs field behavior. Attributing
a constant configuration to the ground state of the Higgs field, a Higgs conformal frame is specified. We define the Higgs
conformal frame as a cosmological frame which describes the large scale characteristics of the observed universe. In the cosmological
frame the gravitational coupling acquires a correct value and one no longer deals with the vacuum energy problem. We then
study a more general case by considering a variable configuration for the ground state of Higgs field. In this case we introduce
a cosmological solution of themodel. 相似文献
Summary. Crossed aldol condensations of ketones with aromatic aldehydes are carried out efficiently in the presence of magnesium hydrogensulfate
under solvent-free conditions in good to excellent yield without the occurrence of any self-condensation. Similar reactions
in solution do not proceed satisfactorily.
Corresponding authors. E-mail: p-salehi@cc.sbu.ac.ir
Received September 20, 2001. Accepted (revised) January 16, 2002 相似文献
Crossed aldol condensations of ketones with aromatic aldehydes are carried out efficiently in the presence of magnesium hydrogensulfate under solvent-free conditions in good to excellent yield without the occurrence of any self-condensation. Similar reactions in solution do not proceed satisfactorily. 相似文献
The complexation reaction between 1,13-bis(8-quinolyl)-1,4,7,10,13-pentaoxatridecane ligand (Kryptofix5) and Zn2+, Ni2+, Co2+, Pb2+ and Cu2+ ions were studied conductometrically in acetonitrile solution. The formation constants of the resulting 1:1 complexes were calculated from the computer fitting of the molar conductance and absorbance measurements in various mole ratios. The enthalpy and entropy changes of the complexation reactions were derived from titration conductometry in acetonitrile at various temperatures. At 25 °C, the stability of the resulting complexes varied in the order Pb2+ > Zn2+ > Cu2+> Co2+> Ni2+. 相似文献
We prove a sharp connectivity and degree sum condition for the existence of a subdivision of a multigraph in which some of the vertices are specified and the distance between each pair of vertices in the subdivision is prescribed (within one). Our proof makes use of the powerful Regularity Lemma in an easy way that highlights the extreme versatility of the lemma. 相似文献