排序方式: 共有67条查询结果,搜索用时 0 毫秒
21.
A. Cemal Eringen 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2010,16(4):119-132
Based on the theory of micromorphic fluid dynamics (MMF), a new theory of turbulence is introduced. The law of conservation
of microinertia of MMF is replaced by a balance law of microinertia, with all other laws remaining unchanged, the theory is
called, “extended micromorphic fluid dynamics”. The present theory of turbulence is founded on the extended theory. Thus,
a new theory of turbulence, is founded on the first principles, not using any a priori closure assumptions or semi-empirical
hypothesis. Field equations are solved for the two-dimensional steady channel flow. The mean velocity turbulent shear stress
and all turbulent velocities are in remarkably good agreement with the experimentally observed turbulent velocities. 相似文献
22.
The paper presents a new method for predicting the frequency of the b1 mode, which is infrared-inactive, in complexes of the type LM(CO)5 belonging to C4V point group. The method was based on the relation λ3=λ4+[(1−δ/δ)](λ1−λ2), where δ=(λ1−λ2)/(λ1−λ2+λ3−λ4), λ1, λ2, λ3 and λ4 are the λ parameters of the , , b1 and e modes, respectively. For a large numbers of complexes of the type LM(CO)5 the average value of δ was found to be 0.80, with a standard deviation of 0.02. With the use of average value of δ, the frequencies of b1 mode were estimated. The result obtained indicated that there exists a rather good fit between observed and calculated frequencies, with a mean error of 2.7 cm−1. In addition, it was shown that the δ parameter can be used as a criterion of the correct band assignment for the complexes understudy. 相似文献
23.
Chemical polymerization of acrylamide at room temperature was examined by using thioglycolic acid-cerium (IV) sulfate and
thioglycolic acid-KMnO4 redox systems in acid aqueous medium. Water soluble polyacrylamides containing thioglycolic acid end groups were synthesized.
The effects of the molar ratio of acrylamide to Ce(IV) n
AAm
/n
Ce(IV)
, the polymerization time, the temperature, the monomer concentration, the molar ratio of cerium (IV) sulfate to thioglycolic
acid and the concentration of sulfuric acid on the yield and molecular weight of polymer were investigated. Lower molar ratios
of acrylamide/Ce(IV) at constant monomer concentration resulted in an increase in the yield but a decrease in molecular weight
of polymer. The increase of reaction temperature from 20 to 70°C resulted in a decrease in the yield but generally resulted
in a constant value for the molecular weight of polymer. With increasing polymerization time, the yield and molecular weight
of polymer did not change substantially. Ce(IV) and Mn(VII) ions are reduced to Ce(III) and Mn(II) ions respectively in the
polymerization reaction. The existence of Ce(III) ion bound to polymer was investigated by UV-visible spectrophotometry and
fluoresce measurements. The amount of Mn(II) incorporated into the polymer was determined using graphite furnace atomic absorption
spectrometry. The mechanism of this phenomenon is discussed. 相似文献
24.
Proton coupled and uncoupled 13C, 1H, DEPT, COSY and HETCOR NMR spectra of 4-Phenylpyridine (4-Phpy) have been reported for the first time except for its 1H NMR spectrum. In order to provide a precise structural elucidation for carbon atoms those have very close chemical shifts to each other, the magnitude of nJCH (n=1,2,3) coupling constants of 4-Phpy (C11H9N) have also been investigated. 13C, 1H NMR chemical shifts and 1-3JCH coupling constants of 4-Phpy have been calculated by means of B3LYP density functional method with 6-311++G(d,p) basis set. Moreover, the optimized parameters (bond lengths, bond and torsion angles) of 4-Phpy have been calculated with B3LYP at 6-31G(d) level in methanol (ε=32.63). Comparison between the experimental and the theoretical results indicates that density functional B3LYP method is able to provide satisfactory results for predicting NMR properties. 相似文献
25.
Phase equilibrium measurements of acoustically levitated squalane–CO2 mixtures by Raman spectroscopy
This work describes the phase equilibrium measurements of acoustically levitated binary mixtures with concentration measurements using Raman spectroscopy without sample extraction of the autoclave. The levitator design is implemented in a Single‐Droplet Optical Cell for levitation processes under varying atmospheres. The advantages of acoustic levitation of small droplets under increased temperatures and pressure combined with spectroscopic applications like Raman spectroscopy enable novel experiments possibly relevant to the fields of chemical engineering. To the author's knowledge, this is the first use of Raman spectroscopy for phase equilibria investigations on acoustically levitated droplets under high pressure and temperature. The results show very good agreements with literature data. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
26.
BAGLAYAN zge KESAN Gürkan PARLAK Cemal ALVER zgür SENYEL Mustafa 《中国科学:物理学 力学 天文学(英文版)》2014,57(9):1654-1661
FT-IR and Raman spectra of 1-cyclopentylpiperazine(1cppp)have been experimentally examined in the region of 4000–200cm-1.The optimized geometric parameters,conformational equilibria,normal mode frequencies and corresponding vibrational assignments of 1cppp(C9H18N2)are theoretically examined by means of B3LYP hybrid density functional theory(DFT)method together with 6-31++G(d,p)basis set.On the basis of potential energy distribution(PED)reliable vibrational assignments have been made and the thermodynamics functions,highest occupied and lowest unoccupied molecular orbitals(HOMO and LUMO)of 1cppp have been predicted.Calculations are employed for four different conformations in C1 and Cs point groups of 1cppp in gas phase.Comparison between the experimental and theoretical results indicates that B3LYP method is able to provide satisfactory results for predicting vibrational frequencies and the structural parameters,vibrational frequencies and assignments.Furthermore,C1(equatorial-axial)point group has been found as the most stable conformer of 1cppp. 相似文献
27.
Fullerenes have been of research interest and they have been particularly studied for their possible applications as drug delivery vehicles. In the present research, the optimized molecular geometries, electronic properties and the possible interaction mechanisms between C60, Si- or Al-doped C60 and 6-chloro-3-hydroxy-2-pyrazinecarboxamide were investigated using quantum mechanical calculations. The calculated binding energies to the Si- and Al-doped fullerenes suggest that doping of fullerene nanocage enhances the interaction mechanism and alters the chemical and electronic properties. The results and parameters found in this research reveal further insight into drug delivery systems. 相似文献
28.
The zinc nitrate salt acts as a solvent in the ZnX-C(12)EO(10) (ZnX is [Zn(H(2)O)(6)](NO(3))(2) and C(12)EO(10) is C(12)H(25)(OCH(2)CH(2))(10)OH) lyotropic liquid crystalline (LLC) mesophase with a drastic dropping on the melting point of ZnX. The salt-surfactant LLC mesophase is stable down to -52 °C and undergoes a phase change into a solid mesostructured salt upon cooling below -52 °C; no phase separation is observed down to -190 °C. The ZnX-C(12)EO(10) mesophase displays a usual phase behavior with an increasing concentration of the solvent (ZnX) in the media with an order of bicontinuous cubic(V(1))-2D hexagonal(H(1))--a mixture of 2D hexagonal and micelle cubic(H(1) + I)-micelle cubic(I)-micelle(L(1)) phases. The phase behaviors, specifically at low temperatures, and the first phase diagram of the ZnX-C(12)EO(10) system was investigated using polarized optical microscopy (POM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR), and Raman techniques and conductivity measurements. 相似文献
29.
30.
The decision problem considered in this paper is a hierarchical workforce scheduling problem in which a higher qualified worker can substitute for a lower qualified one, but not vice versa, labour requirements may vary, and each worker must receive n off-days a week. Within this context, five mathematical models are discussed. The first two of these five models are previously published. Both of them are for the case where the work is indivisible. The remaining three models are developed by the authors of this paper. One of these new models is for the case where the work is indivisible and the other two are for the case where the work is divisible. The three new models are proposed with the purpose of removing the shortcomings of the previously published two models. All of the five models are applied on the same illustrative example. Additionally, a total of 108 test problems are solved within the context of two computational experiments. 相似文献