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181.
The present paper focuses on the analysis of unsteady flow and heat transfer regarding an axisymmetric impinging synthetic
jet on a constant heat flux disc. Synthetic jet is a zero net mass flux jet that provides an unsteady flow without any external
source of fluid. Present results are validated against the available experimental data showing that the SST/k − ω turbulence model is more accurate and reliable than the standard and low-Re k − ε models for predicting heat transfer from an impinging synthetic jet. It is found that the time-averaged Nusselt number
enhances as the nozzle-to-plate distance is increased. As the oscillation frequency in the range of 16–400 Hz is increased,
the heat transfer is enhanced. It is shown that the instantaneous Nu distribution along the wall is influenced mainly by the interaction of produced vortex ring and wall boundary layer. Also,
the fluctuation level of Nu decreases as the frequency is raised. 相似文献
182.
Farzad Deyhimi Rahman Salamat-Ahangari Massood Arabieh Lida Parvin 《International journal of environmental analytical chemistry》2013,93(15):1151-1163
In this work, an initial-rate spectrophotometric method and response surface methodology (RSM) were combined for modelling and optimizing the experimental parameters of the enzymatic Emerson–Trinder reaction, for the determination of hydrogen peroxide. This spectrophotometric indicator reaction is currently used in biotechnology for the determination of phenolic compounds (e.g. in industrial samples) and also for determination of various substrates (e.g. in clinical chemistry). Using 4-iodophenol as a hydrogen donor in this reaction, the quality of the generated second-order polynomial response model equation was checked by the kinetic assay of H2O2 in real samples (e.g. cosmetic and human pooled serum samples), where their resulting satisfactory analytical characteristics were reported. 相似文献
183.
Petersson P Forssen P Edström L Samie F Tatterton S Clarke A Fornstedt T 《Journal of chromatography. A》2011,1218(39):6914-6921
The purpose of this study is to demonstrate, with experiments and with computer simulations based on a firm chromatographic theory, that the wide spread perception of that the United States Pharmacopeia tailing factor must be lower than 2 (T(f)<2) is questionable when using the latest generation of LC equipment. It is shown that highly efficient LC separations like those obtained with sub-2 μm porous and 2.7 μm superficially porous particles (UHPLC) produce significantly higher T(f)-values than the corresponding separation based on 3 μm porous particles (HPLC) when the same amount of sample is injected. Still UHPLC separations provide a better resolution to adjacent peaks. Expressions have been derived that describe how the T(f)-value changes with particle size or number of theoretical plates. Expressions have also been derived that can be used to scale the injection volume based on particle size or number of theoretical plates to maintain the T(f)-value when translating a HPLC separation to the corresponding UHPLC separation. An aspect that has been ignored in previous publications. Finally, data obtained from columns with different age/condition indicate that T(f)-values should be complemented by a peak width measure to provide a more objective quality measure. 相似文献
184.
Farhad Khoeini A. A. Shokri Farzad Khoeini 《The European Physical Journal B - Condensed Matter and Complex Systems》2010,75(4):505-509
In this work, we study quantum transport properties of
superlattice-graphene nanoribbons (SGNRs) attached to two
semi-infinite metallic armchair graphene nanoribbon (AGNR) leads.
The calculations are based on the tight-binding model and Green’s
function method, in which localization length, density of states
(DOS) and conductance of the system are calculated, numerically.
By controlling the layered boron concentration, this kind of
system can separate the extended states from the localized states.
Our results may have important applications for building blocks in
the nano-electronic devices based on GNRs. 相似文献
185.
Farzad Ebrahimi Mohammad Reza Barati Ali Dabbagh 《Waves in Random and Complex Media》2018,28(2):215-235
In this article, an analytical approach is developed to study the effects of thermal loading on the wave propagation characteristics of an embedded functionally graded (FG) nanoplate based on refined four-variable plate theory. The heat conduction equation is solved to derive the nonlinear temperature distribution across the thickness. Temperature-dependent material properties of nanoplate are graded using Mori–Tanaka model. The nonlocal elasticity theory of Eringen is introduced to consider small-scale effects. The governing equations are derived by the means of Hamilton’s principle. Obtained frequencies are validated with those of previously published works. Effects of different parameters such as temperature distribution, foundation parameters, nonlocal parameter, and gradient index on the wave propagation response of size-dependent FG nanoplates have been investigated. 相似文献