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761.
762.
Alimohammad Karami Tooraj Yousefi Saeid Ebrahimi Ehsan Rezaei Sajjad Mahmoudinezhad 《Heat and Mass Transfer》2013,49(6):789-798
This paper reports the application of the adaptive neuro-fuzzy inference system to model the forced convection heat transfer from v-shaped plate internal surfaces exposed to an air impingement slot jet. The aim of the current study is to consider the effects of the angle of the v-shaped plate $ (\Upphi ) $ , slot-to-plate spacing ratio (Z/W) and the Reynolds number (Re) variation on the average heat transfer from the v-shaped plate. 相似文献
763.
An experimental and numerical study has been carried out to investigate the heat transfer characteristics of a horizontal
circular cylinder exposed to a slot jet impingement of air. A square-edged nozzle is mounted parallel with the cylinder axis
and jet flow impinges on the bottom of the cylinder. The study is focused on low Reynolds numbers ranging from 120 to 1,210,
Grashof numbers up to Gr = 10Re
2 and slot-to-cylinder spacing from 2 to 8 of the slot width. The flow field is greatly influenced by the slot exit velocity
and the buoyancy force due to density change. A Mach–Zehnder Interferometer is used for measurement of local Nusselt number
around the cylinder at 10° interval. It is observed that the average Nusselt number decreases with increasing the jet spacing
and increases with rising the Reynolds number. A finite volume method utilizing a curvilinear coordinate transformation is
used for numerical modeling. The numerical results show good agreement with the experimental results. The flow and thermal
field are seen to be stable and symmetric around the cylinder over the range of parameters studied. 相似文献
764.
The present paper deals to the quintom model of dark energy. We introduce a first-order formalism, which shows how to relate
the potential that specifies the scalar field model to Hubble’s parameter. Reviewing briefly the quintom scenario of dark
energy, we present a general procedure to solve the equations of motion for quintom model driven by a couple scalar fields
with first-order differential equations. 相似文献
765.
Polyamide-6/poly(epichlorohydrin - co - ethylene oxide) (PA6/ECO) nanocomposites were prepared with 6 wt.% organoclay and different ECO content from 5 to 40 wt.%,
via two-step melt blending process. The effects of organoclay and rubber content on the morphological and rheological properties
of samples have been studied. Samples have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM),
and rheometry in small amplitude oscillatory shear. XRD results indicate that the nanoclay platelets are partially exfoliated
in both PA6 and ECO phases. The higher rubber content of nanocomposite samples results in higher exfoliation degree of the
nanoclay layers. SEM photomicrographs of samples show that the size of rubber droplets increases by the introducing of nanoclay.
Oscillatory shear measurements show that the storage modulus of nanocomposite samples significantly increases in comparison
with unfilled blends. The formation of physical network is the prime cause of such increase. Moreover, presence of nanoclay
dramatically increases melt yield stress of the samples. Palierne emulsion model has been applied to predict the rheological
behavior of unfilled blends. A quantitative agreement between Palierne model and those of experimental data is found for low
ECO content samples. 相似文献
766.
Xinyu Sun Xueyan Feng Xiao-Yun Yan Jiancheng Luo Ruimeng Zhang Tao Li Hui Li Jiahui Chen Fangbei Liu Ehsan Raee Stephen Z. D. Cheng Tianbo Liu 《Chemical science》2021,12(36):12130
We report herein that dendron-shaped macromolecules ABn crystallize into well-ordered pyramid-like structures from mixed solvents, instead of spherical motifs with curved structures, as found in the bulk. The design of the asymmetric molecular architecture and the choice of mixed solvents are applied as strategies to manipulate the crystallization process. In mixed solvents, the solvent selection for the Janus macromolecule and the existence of dominant crystalline clusters contribute to the formation of flat nanosheets. Whereas during solvent evaporation, the bulkiness of the asymmetric macromolecules easily creates defects within 2D nanosheets which lead to their spiral growth through screw dislocation. The size of the nanosheets and the growth into 2D nanosheets or 3D pyramidal structures can be regulated by the solvent ratio and solvent compositions. Moreover, macromolecules of higher asymmetry generate polycrystals of lower orderliness, probably due to higher localized stress.The dendron-shaped macromolecules ABn crystallize into well-ordered pyramid-like structures from mixed solvents, which is on the contrary to spherical motifs with curved structures in bulk. 相似文献
767.
In this study, an efficient hybrid continuum‐atomistic method is proposed to study electrokinetic transport of aqueous solutions in nanofluidics. The aqueous phase is considered as a continuous phase containing immersed ion particles. The behavior of the system is then simulated through utilization of an improved hybrid continuum‐atomistic four‐way coupled approach, including the MultiPhase Particle‐In‐Cell method for the short‐ranged interaction between the ion particles, the Brownian force for the collision between the aqueous phase molecules and the ion particles, and a wall force accounting for the short‐ranged interaction of ions and walls. The validation of the proposed model with the results of Molecular Dynamics simulations suggests that this model can be a promising approach for studying the electrokinetic phenomena in more complicated geometries where the Molecular Dynamics approach is computationally prohibitive. Finally, the effects of electrokinetic parameters, such as the height of the channel, the external electric field, and bulk ionic concentration, on the electroosmotic flow in a nanochannel are investigated and discussed. 相似文献
768.
Muhammad Ehsan Ashwani Kumar Jonas S. Mortensen Yang Du Parameswaran Hariharan Kaavya K. Kumar Betty Ha Bernadette Byrne Lan Guan Brian K. Kobilka Claus J. Loland Pil Seok Chae 《化学:亚洲杂志》2019,14(11):1926-1931
We prepared an amphiphile with a penta‐phenylene lipophilic group and a branched trimaltoside head group. This new agent, designated penta‐phenylene maltoside (PPM), showed a marked tendency to self‐assembly into micelles via strong aromatic–aromatic interactions in aqueous media, as evidenced by 1H NMR spectroscopy and fluorescence studies. When utilized for membrane protein studies, this new agent was superior to DDM, a gold standard conventional detergent, in stabilizing multiple proteins long term. The ability of this agent to form aromatic–aromatic interactions is likely responsible for enhanced protein stabilization when associated with a target membrane protein. 相似文献
769.
Ehsan Samei Kimberlee J. Kearfott Timothy J. Gillespie C.-K. Chris Wang 《Radiation Physics and Chemistry》1996,48(6):719-725
A method to generate depth-dose distributions due to beta radiation in LiF and soft tissue is proposed. In this method, the EGS4 Monte Carlo radiation transport code is initially used to generate a library of monoenergetic electron depth-dose distributions in the material for electron energies in the range of 10 keV to 5 MeV in 10 keV increments. A polynomial least-squares fit is applied to each distribution. In addition, a theoretical model is developed to generate beta-ray energy spectra of selected radionuclides. A standard Monte Carlo random sampling technique is then employed to sample the spectra and generate the depth-dose distributions in LiF and soft tissue. The proposed method has an advantage over more traditional methods in that the actual radiation transport in the media is performed only once for a set of monoenergetic cases and the beta depth-dose distributions are easily generated by sampling this previously-acquired database in a matter of minutes. This method therefore reduces the demand on computer resources and time. The method can be used to calculate depth-dose distribution due to any beta-emitting nuclide or combination of nuclides with up to ten beta components. 相似文献
770.
Dikshitulu K. Kalluri Monzurul M. Ehsan 《International Journal of Infrared and Millimeter Waves》2004,25(2):327-353
A frequency transformer that converts an elliptically polarized standing wave into frequency-shifted circularly polarized standing waves is considered. The transformer is a one-dimensional cavity in which a magnetoplasma, that supports longitudinal modes, is created. Theoretical derivation for the case of sudden and uniform creation of the magnetoplasma is given. Finite-Difference Time-Domain (FDTD) technique is developed to numerically simulate the problem. The simulation is used to verify the results of the theory as well as obtain results for the cases of creation of a lossy magnetoplasma with arbitrary space and time profile of the electron density. A few instructive results are presented as graphs to illustrate the effects of source parameters and system parameters. 相似文献