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971.
In this research the fluid dynamics characteristics of a stellar turbulent jet flow is studied numerically and the results
of three dimensional jet issued from a stellar nozzle are presented. A numerical method based on control volume approach with
collocated grid arrangement is employed. The turbulent stresses are approximated using k–ε and k–ω models with four different inlet conditions. The velocity field is presented and the rate of decay at jet centerline is noted.
Special attention is drawn on the influence of corner angle and number of wings on mixing in stellar cross section jets. Stellar
jets with three; four and five wings and 15–65° corner angles are studied. Also the effect of Reynolds number (based on hydraulic
diameter) as well as the inflow conditions on the evolution of the stellar jet is studied. The Numerical results show that
the jet entrains more with corner angle 65° and five wings number. The jet is close to a converged state for high Reynolds
numbers. Also the influence of the inflow conditions on the jet characteristics is so strong. 相似文献
972.
G. Reza Bebahani David Dunnion Patrick Falvey Kenneth Hickey Mary Meade Yvonne McCarthy Martyn C. R. Symons W. Earle Waghorne 《Journal of solution chemistry》2000,29(6):521-539
We report enthalpies of solution of formamide, N,N-dimethylformamide,N,N-dimethylacetamide, acetic acid, methyl acetate, and acetonitrile in water +dimethylsulfoxide mixed solvents. These, along with literature data for additional solutes,are analyzed in terms of the extended coordination model of solvation. We alsoanalyze infrared data for several of these solutes. These analyses show thatN,N-dimethylformamide and N,N-dimethylacetamide are preferentially hydrated,while the other solutes appear to be preferentially solvated by dimethylsulfoxide.In all cases, the extent of preferential solvation is relatively small. It is also foundthat the degrees of preferential solvation recovered from analyses of the enthalpydata correspond closely to those recovered from the infrared data, although thelatter refer only to the polar chromophores on the solute molecules. It is foundthat the extent to which the solutes disrupt the solvent-solvent interactions variessystematically with the area of the nonpolar surfaces of the solute molecules. 相似文献
973.
Ali Reza Ashrafi 《Journal of Applied Mathematics and Computing》2000,7(1):115-124
For a finite groupG, #Cent(G) denotes the number of centralizers of its elements. A groupG is called n-centralizer if #Cent(G) =n, and primitiven-centralizer if # Cent(G)\text = # Cent\text(\fracGZ(G))\text = n\# Cent(G){\text{ = \# }}Cent{\text{(}}\frac{G}{{Z(G)}}){\text{ = }}n. In this paper we compute the number of distinct centralizers of some finite groups and investigate the structure of finite groups with exactly six distinct centralizers. We prove that ifG is a 6-centralizer group then % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaSaaaeaaca% WGhbaabaGaamOwaiaacIcacaWGhbGaaiykaaaacaqGGaGaeyyrIaKa% aeiiaGqaciaa-readaWgaaWcbaGaa8hoaaqabaGccaGGSaGaaeiiai% aa-feadaWgaaWcbaGaa8hnaaqabaGccaGGSaGaaeiiaiaabQfadaWg% aaWcbaGaaeOmaaqabaGccaqGGaGaey41aqRaaeiiaiaabQfadaWgaa% WcbaGaaeOmaaqabaGccaqGGaGaey41aqRaaeiiaiaabQfadaWgaaWc% baGaaeOmaaqabaGccaqGGaGaae4BaiaabkhacaqGGaGaaeOwamaaBa% aaleaacaqGYaaabeaakiaabccacqGHxdaTcaqGGaGaaeOwamaaBaaa% leaacaqGYaaabeaakiaabccacqGHxdaTcaqGGaGaaeOwamaaBaaale% aacaqGYaaabeaakiaabccacqGHxdaTcaqGGaGaaeOwamaaBaaaleaa% caqGYaaabeaaaaa!62C4!\[\frac{G}{{Z(G)}}{\text{ }} \cong {\text{ }}D_8 ,{\text{ }}A_4 ,{\text{ Z}}_{\text{2}} {\text{ }} \times {\text{ Z}}_{\text{2}} {\text{ }} \times {\text{ Z}}_{\text{2}} {\text{ or Z}}_{\text{2}} {\text{ }} \times {\text{ Z}}_{\text{2}} {\text{ }} \times {\text{ Z}}_{\text{2}} {\text{ }} \times {\text{ Z}}_{\text{2}} \] . 相似文献
974.
A second‐derivative spectrophotometric method based on zero‐crossing over technique is developed in simultaneous determination of copper(II) and nickel(II) ions. Methylthymol blue (MTB) as a chromogenic reagent and cetyltrimethylammonium bromide as a surfactant were used, and measurements were carried out in buffered solution at pH 6 and at a temperature of 25 °C. The amplitude of derivative spectra was measured at wavelengths of 631.9 and 587.7 nm for the simultaneous determination of Ni2+ and Cu2+, respectively. Linearity was obtained in the range of 0.5–5.0 μg mL?1 for both ions in the presence of 0.0–5.0 μg mL?1 of the other ion as an interfering ion. IUPAC detection limits for Cu2+ and Ni2+ ions were obtained at 0.48 and 0.43 μg mL?1, respectively. The proposed procedure has been applied successfully for the simultaneous determination of copper and nickel in synthetic binary mixtures and real samples. 相似文献
975.
Kavkhani Roya Pourzaki Mahtab Kianvash Abbas Hajalilou Abdollah Adli Reza Ghaffari 《Journal of Sol-Gel Science and Technology》2021,99(2):444-454
Journal of Sol-Gel Science and Technology - In this study, Mg–Mn–Al ferrite with a chemical composition of Mg0.8Mn0.2Al0.1Fe1.9O4 was synthesized via the sol–gel auto-combustion... 相似文献
976.
Zahra Abdi Dr. Robabeh Bagheri Dr. Mohammad Reza Mohammadi Prof. Zhenlun Song Dr. Mikaela Görlin Prof. Holger Dau Prof. Dr. Mohammad Mahdi Najafpour 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(4):1330-1336
All studies on oxygen-evolution reaction by Mn oxides in the presence of cerium(IV) ammonium nitrate (CAN) have been so far carried out by synthesizing Mn oxides in the first step. And then, followed by the investigation of the Mn oxides in the presence of oxidants for oxygen-evolution reaction (OER). This paper presents a case study of a new and promising strategy for in situ catalyst synthesis by the adding MnII to either CAN or KMnO4/CAN solution, resulting in the formation of Mn-based catalysts for OER. The catalysts were characterized by scanning electron microscopy, energy-dispersive spectroscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray absorption spectroscopy, and X-ray photoelectron spectroscopy. Both compounds contained nano-sized particles that catalyzed OER in the presence of CAN. The turnover frequencies for both catalysts were 0.02 (mmol /molMn⋅s). 相似文献
977.
Matlab Khamiyev Akbar Khanmetov Vakhshouri Amir Reza Reyhan Aliyeva Kamala Hajıyeva-Atayi Zeynab Akhundova Gunay Khamiyeva 《应用有机金属化学》2020,34(3):e5409
A review of the scientific and patent literature on oligomerization of ethylene to linear olefins in the presence of homogenous or heterogeneous zirconium complexes and various aluminum organic compounds has been fulfilled for last twenty-five years. Over these years, a wide range of studies had been conducted for selective oligomerization of ethylene into a narrow fraction of linear α-olefins such as C4-C8 and C6-C10 fractions. During the discussion of these catalytic systems, exceptional attention is also paid to feature works such as the activity of the catalysts and the acquisition of clear liquid product without any trace of polymer, all of which play important roles in the selection of the best technology. 相似文献
978.
Potassium dihydrogen phosphate (KH2PO4) with the aid of ultrasonic irradiation was found to be an efficient catalytic system for the efficient and rapid synthesis of novel 2-amino-4,5-dihydro-4-arylpyrano[3,2-b]indole-3-carbonitriles. 相似文献
979.
Ali Reza Kiasat Simin Nazari 《Journal of inclusion phenomena and macrocyclic chemistry》2013,77(1-4):429-438
In the present study, β-cyclodextrin-silica hybrid is synthesized as a novel, efficient and eco-friendly microvessel and solid–liquid phase-transfer catalyst. This molecular host system was applied for nucleophilic substitution reaction of phenacyl halides in water. No evidence was observed for the formation of by-product for example isothiocyanate or alcohol. Also the products were obtained in pure form without further purification. The structure and morphology of the obtained system were investigated by infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis and differential thermal analysis techniques. The surface porosity of the synthesized catalyst was evaluated from the nitrogen adsorption isotherm. All the results provided evidence for incorporation of β-cyclodextrin inside silica pores. 相似文献
980.