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Turbulent heat transfer and pressure loss in a square channel with discrete broken V-rib turbulators

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Journal of Hydrodynamics 2016年第2期28卷 275-283页

作者： Promthaisong PITAK Eiamsa-ard PETPICES Jedsadaratanachai WITHADA Eiamsa-ard SMITH faculty of Engineering Mahanakorn University of Technology faculty of Industrial Technology Phetchaburi Rajabhat University faculty of Engineering King Mongkut's Institute of Technology Ladkrabang

Turbulent periodic flow, heat transfer, friction loss and thermal enhancement characteristics in a three-dimensional horizo- ntal square channel with broken V-ribs （B-VR） are numerically investigated. The computations are based on the finite volume method, and the SIMPLE algorithm with QUICK scheme is implemented. The B-VR were installed on both sides of a plate which was diagonally placed in a square channel to produce longitudinal vortex flows through the tested section. Effects of different open comer ratios （ d/H = 0, 0.01, 0.02, 0.03, 0.04 and 0.05） on heat transfer and pressure loss in the channel and the results of the B-VR are studied. The pitch ratio （PR = p/H） and blockage ratio （BR = p/H） of B-VRs were fixed at 1.0 and 0.15, respectively. As compared with the channel without V-rib, the one with B-VRs possessed considerably higher heat transfer and friction loss. It is observed that apart from the rise of Reynolds number, the reduction of the open comer ratios leads to an increase in the Nusselt number and friction factor due to the weaker turbulence and lower resistance to the flow. According to the computational results for B-VRs, the optimum thermal enhancement is fotmd at d/H = 0.

关键词： channel periodic flow heat transfer friction loss broken V-ribs

Physical Studies of Some Hydrazinobenzoic Acid Complexes

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Journal of Materials Science & Technology 2005年第1期21卷 140-144页

作者： M.G.Abd El Wahed S.Abd El Wanees M.El Gamel S.Abd El Haleem faculty of Science Zagazig University Zagazig EgyptFaculty of Science Zagazig University Zagazig EgyptFaculty of Science Zagazig University Zagazig EgyptFaculty of Science Zagazig University Zagazig Egypt

The stability constants of complexes of 2-hydrazinobenzoic acid and 4-hydrazinobenzoic acid with Ni (Ⅱ), Cu (Ⅱ), Zn (Ⅱ), Cd (Ⅱ), and Hg (Ⅱ) were determined potentiometricaIly at different temperatures. The thermodynamic parameters, △G0, △H0, and △S0 were calculated and proved that the complexation process is spontaneous and endothermic. The thermodynamic functions were analyzed in terms of electrostatic and non-electrostatic components and the results reveal that ionic bonds are formed between the studied ligands and metal ions. Conductometric titration was shown that the stoichiometry of the formed complexes are M:L and M:2L. The structure of the prepared solid complexes was characterized using IR, 1H NMR, 13C NMR spectroscopies as well as X-ray diffraction technique. Finally electrical conductivity of the ligands and their copper complexes was measured and shown that the ligands have a semiconductor behaviour.

关键词： Potentiometric titration Stability constants Thermodynamic parameters Structure of metal complexes

Effect of substitution group on dielectric properties of 4H-pyrano [3,2-c] quinoline derivatives thin films

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Chinese Physics B 2016年第7期25卷 440-449页

作者： H M Zeyada F M El-Taweel M M El-Nahass M M El-Shabaan Department of Physics Faculty of Science Damietta University Department of Chemistry Faculty of Science Damietta University Department of Physics Faculty of Education Ain Shams University

The AC electrical conductivity and dielectrical properties of 2-amino-6-ethyl-5-oxo-4-（3-phenoxyphenyl）-5,6-dihydro-4H-pyrano[3, 2-c]quinoline-3-carbonitrile（Ph-HPQ） and 2-amino-4-（2-chlorophenyl）-6-ethyl-5-oxo-5,6-dihydro-4H-pyrano [3, 2-c] quinoline-3-carbonitrile（Ch-HPQ） thin films were determined in the frequency range of 0.5 k Hz–5 MHz and the temperature range of 290–443 K. The AC electrical conduction of both compounds in thin film form is governed by the correlated barrier hopping（CBH） mechanism. Some parameters such as the barrier height, the maximum barrier height, the density of charges, and the hopping distance were determined as functions of temperature and frequency. The phenoxyphenyl group has a greater influence on those parameters than the chlorophenyl group. The AC activation energies were determined at different frequencies and temperatures. The dielectric behaviors of Ph-HPQ and Ch-HPQ were investigated using the impedance spectroscopy technique. The impedance data are presented in Nyquist diagrams for different temperatures. The Ch-HPQ films have higher impedance than the Ph-HPQ films. The real dielectric constant and dielectric loss show a remarkable dependence on the frequency and temperature. The Ph-HPQ has higher dielectric constants than the Ch-HPQ.

关键词： thin films quinoline derivatives dielectrical properties correlated barrier hopping

Exact solutions for nonlinear partial fractional differential equations

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Chinese Physics B 2012年第11期21卷 32-38页

作者： Khaled A.Gepreel Saleh Omran Mathematics Department Faculty of ScienceZagazig University Mathematics Department Faculty of ScienceTaif University Mathematics Department Faculty of scienceSouth Valley University

′In this article, we use the fractional complex transformation to convert nonlinear partial fractional differential equations to nonlinear ordinary differential equations. We use the improved （G′/G）-expansion function method to calculate the exact solutions to the time- and space-fractional derivative foam drainage equation and the time- and space-fractional derivative nonlinear KdV equation. This method is efficient and powerful for solving wide classes of nonlinear evolution fractional order equations.

关键词： fractional calculus complex transformation modified Riemann-Liouville derivative im- proved (G′/G)-expansion function method

Spectral analysis in ultraweak emissions of chemi-and electrochemiluminescence systems

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Journal of Rare Earths 2009年第4期27卷 593-597页

作者： K.Staninski M.Kaczmarek S.Lis D.Komar A.Szyczewski faculty of Chemistry Adam Mickiewicz University faculty of Physics Adam Mickiewicz University

Investigation of ultraweak emissions in the processes of chemiluminescence, CL, and electrochemiluminesce, ECL, requires special techniques of their recording and spectral analysis. From among the hitherto proposed methods of detection of the emission spectra of these processes, that of the cut-off filter was most sensitive. The usefulness of this method in interpretation of the CL and ECL systems of the quantum yields in the range 1×10^-9-1×10^-11 containing ions and complexes of Eu（Ⅲ）, Tb（Ⅲ） and Dy0ID was shown. Exceptional character of the emission bands of lanthanide ions, being a result of the f-f electron transitions and in particular their low FWHM, permitted the appli- cation of the cut-off filter method to their analysis. The results obtained for CL and ECL on the basis of analysis of ultraweak emission proved to be successful in analytical applications. The systems containing Eu（Ⅲ） ions hydrated or complexed with organic ligands enabled inferring changes in the coordination sphere of the ions.

关键词： chemiluminescence electrochemiluminescence cut-off fdter method lanthanide rare earths

A Generalization of the Concept of q-fractional Integrals

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Acta Mathematica Sinica,English Series 2009年第10期25卷 1635-1646页

作者： Predrag M.RAJKOVIC Sladjana D.MARINKOVIC Miomir S.STANKOVIC faculty of Mechanical Engineering University of Nis faculty of Electronic Engineering University of Nis faculty of Occupational Safety University of Nis

In this paper, we consider the fractional q-integral with variable lower limit of integration. We prove the semigroup property of these integrals, and a formula of Leibniz type. Finally, we evaluate fractional q-integrals of some functions. The consideration of q-exponential function in that sense leads to q-analogs of Mittag-Leffier function.

关键词： basic hypergeometric functions q-integral q-derivative fractional integrals Mittag-Leffler function

Optical properties of cobalt xanthate films on different substrates

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International Journal of Minerals,Metallurgy and Materials 2014年第7期21卷 736-740页

作者： I.A.Kariper T.zpozan Education faculty Erciyes University Chemistry Department Science FacultyErciyes University

Cobalt isopropyl xanthate thin films （CXTFs） were deposited via chemical bath deposition onto different substrates：commercial glass （CG）, indium tin oxide （ITO）, and poly（methyl methacrylate）（PMM）. Isopropyl xanthate was synthesized according to a method described in the literature. The cobalt nitrate and isopropyl xanthate were mixed in a beaker, which allowed the thin films to be deposited via a simple ion-ion mechanism. The transmission, reflectivity, refractive index, dielectric constant, and optical conductivity were investigated for various thin films coated onto different substrates. An ultraviolet-visible spectrophotometer was used to measure the optical properties of the thin films. The lowest value of the transmission and the highest value of the refractive index were observed for the thin films deposited onto PMM. The structure of the cobalt xanthate was characterized by Fourier transform infrared （FTIR） spectroscopy, which was measured using a Perkin-Elmer Spectrum 400 spectrometer. The stretching vibration of the Co-S bonds was observed at 359 cm^-1 in the FTIR spectrum of the CXTFs.

关键词： thin films cobalt compounds xanthates chemical deposition optical properties

Evaluation of FEMA-440 for including soil-structure interaction

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Earthquake Engineering and Engineering Vibration 2010年第3期9卷 397-408页

作者： Khoshnoudian F. Behmanesh I. faculty of Civil Engineering Amirkabir University of Technology faculty of Civil and Environmental Engineering Tufts University

Replacing the entire soil-structure system with a fixed base oscillator to consider the effect of soil-structure interaction （SSI） is a common analysis method in seismic design. This technique has been included in design procedures such as NEHRP, ASCE, etc. by defining an equivalent fundamental period and damping ratio that can modify the response of the structure. However, recent studies indicate that the effects of SSI should be reconsidered when a structure undergoes a nonlinear displacement demand. In recent documents on Nonlinear Static Procedures （NSPs）, FEMA-440 （2005）, a modified damping ratio of the replacement oscillator was proposed by introducing the ductility of the soil-structure system obtained from pushover analysis. In this paper, the damping defined in FEMA-440 to include the soil-structure interaction effect is evaluated, and the accuracy of the Coefficient Method given in FEMA-440 and the Equivalent Linearization Method is studied. Although the improvements for Nonlinear Static Procedures （NSPs） in FEMA-440 are achieved for a fixed base SDOF structure, the soil effects are not perfectly obtained. Furthermore, the damping definition of a soil-structure system is extended to structures to consider bilinear behavior.

关键词： soil-structure interaction foundation damping inelastic behavior equivalent linearization

Mathematical Modelling of the Transient Response of Pipeline

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Journal of Thermal Science 2016年第6期25卷 549-557页

作者： Dawid Taler Karol Kaczmarski Cracow University of Technology Faculty of Environmental Engineering Cracow University of Technology Faculty of Mechanical Engineering

Steam pipelines applied in power units operate at high pressures and *** addition,to stress from the pipeline pressure also arise high thermal stresses in transient states such as start-up,shutdown or a load change of the power ***-varying stresses are often the cause of the occurrence of fatigue cracks since the plastic deformations appear at the stress concentration *** determine the transient temperature of the steam along the steam flow path and axisymmetric temperature distribution in the pipeline wall,a numerical model of pipeline heating was *** determine the transient temperature of the steam and pipeline wall the finite volume method(FVM) was used Writing the energy conservation equations for control areas around all the nodes gives a system of ordinary differential equations with respect to *** system of ordinary differential equations of the first order was solved by the Runge-Kutta method of the fourth order to give the time-temperature changes at the nodes lying in the area of the wall and *** steam pressure distribution along pipeline was determined from the solution of the momentum conservation *** on the calculated temperature distribution,thermal stresses were *** friction factor was calculated using the correlations of Churchill and Haaland,which were proposed for pipes with a rough inner *** assess the accuracy of the proposed model,numerical calculations were also performed for the thin-walled pipe,and the results were compared to the exact analytical *** of the results shows that the accuracy of the proposed model of pipeline heating is very *** paper presents examples of the determination of the transient temperature of the steam and the wall.

关键词： pipeline steam heating walled satisfactory Pipeline conservation lying Kutta Runge