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A novel hybrid solid-like fluid-like （SLFL） method for the simulation of dry granular flows

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Particuology 2017年第2期15卷 200-219页

作者： A. Eslamian m. Khayat Department of mechanical Engineering Science and Research Branch Islamic Azad University Tehran Iran

This paper proposes a novel hybrid method to simulate the dry granular flow of materials over a wide range of inertial numbers that simultaneously covers the quasi-static and dense granular flow regimes. To overcome the lack of incremental objectivity whenever large deformations occur in solid-like regimes and to remove computational singularities in fluid-like regimes close to rest, the elastic–perfectly plastic theory based on the Drucker–Prager yield criterion is combined with the theory of dense granular flows. By implementing some new modifications at the boundaries and removing all ghost particles, smoothed particle hydrodynamics （SPH） is used as the framework for the method. A number of benchmark problems have been solved to show the capabilities of the new modified SPH method. Precise prediction of both location and pressure makes the modifications comparable with the previous works on SPH. Finally, the method is used to solve the classic 2D dry granular cliff collapse problem and to model dry granular material flow inside a rotary drum. The outcomes of the numerical simulation show good agreement with tabletop experiments and published results.

关键词： Solid-like Fluid-like Granular flow Smoothed particle hydrodynamics Inertial number Cliff collapse

Surface turbulence in a physical model of a steel thin slab continuous caster

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International Journal of minerals,metallurgy and materials 2010年第6期17卷 697-703页

作者： A. Hajari m. meratian Department of materials Engineering Isfahan University of Technology

In the thin slab continuous casting （TSCC） of steel, the issue of optimum fluid flow is very important due to higher casting speeds and has direct influence on the formation of solidified shells and the quality of final products. In the current work, a full-scale physical mod- eling of a thin slab easter on the basis of dimensionless Reynolds and Froude similarity criteria was constructed. The flow pattern in the funnel shaped mold with a new tetra-furcated submerged entry nozzle （SEN） was investigated. To determinate optimum operational parameters, some experiments were carried out under various casting conditions. The results show that the tetra-furcated design of the nozzle leads to a special flow pattern in the mold cavity with three-dimensional recirculating flow. It is also shown that the increase of casting speed and gas injection results in surface turbulence. On the other hand, using a higher depth of SEN decreases the vortex in the free surface of the caster. To avoid surface turbulent and related casting problems, it is recommended to use 30-cm and 40-cm SEN depth at the casting speeds of 3.5 and 4.5 m/min, respectively.

关键词： continuous casting slabs modelling optimization

α-FUZZY PAIRWISE RETRACT OF L-VALUED PAIRWISE STRATIFICATION SPACES

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Chinese Annals of mathematics,Series B 2004年第4期25卷 533-544页

作者： m.H.GHANIm F.S.mAHmOUD m.A.FATH ALLA m.A.HEBESHI Department of mathematics Faculty of ScienceZagazig UniversityZagazigEgypt.Department of MathematicsFaculty of ScienceSohagEgypt.Department of MathematicsFaculty of ScienceSohagEgypt.Department of MathematicsFaculty of ScienceSohagEgypt.

The notion of a fuzzy retract was introduced by Rodabaugh (1981). The notion of a fuzzy pairwise retract was introduced in 2001. some weak forms and some strong forms of α-continuous mappings were introduced in 1988 and 1997. The authors extend some of these forms to the L-fuzzy bitopological setting and construct various α-fuzzy pairwise retracts. The concept of weakly induced spaces in the case L = [0,1] was introduced by martin (1980). Liu and Luo (1987) generalized this notion to the case that L is an arbitrary F-lattice and introduced the notion of induced L-fts. Several results are obtained, especially, for L-valued pairwise stratification spaces.

关键词： L-fuzzy pairwise continuous mappings α-Pairwise continuous mappings α-Fuzzy pairwise retracts L-valued pairwise stratification spaces

Wear Behavior of PTFE–Hydroxyapatite Composite Fabricated by Hot-Press Sintering Process

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Acta metallurgica Sinica(English Letters) 2014年第2期27卷 347-351页

作者： H.R.Zafarani m.Abdi m.E.Bahrololoom Department of materials Science and Engineering School of EngineeringShiraz University

In the present work, a new biocompatible composite was fabricated by hot-press sinter-bonding of polytet- rafluoroethylene （PTFE）-hydroxyapatite composite. Furthermore, the wear properties of this composite were studied by computer-controlled pin-on-disk type tribometer in reporting volume loss per distance. The investigation was performed in three different fractions of hydroxyapatite （10, 20 and 30 wt%）. In order to improve the bonding between hydroxyapatite and PTFE, and thus to increase the wear properties of the composite, the effect of adding silane-coupling agent was investigated. Furthermore, to simulate the environment of human body, some of the wear tests were carried out in the ringer＇s solution. It was found that the wear resistance is improved at high load. moreover, an optimum fraction of hydroxyapatite （20 wt%） was found in which the best wear resistance is achieved, especially at dry sliding condition. At last, the roles of the factors such as wear load, ringer＇s solution, and silane-coupling agent are described with respect to their influences on the Lancaster wear coefficient.

关键词： Hydroxyapatite composite Polymers Silane-coupling agent Wear resistance

X-Ray Radiation Sensing Properties of ZnS Thin Film:A Study on the Effect of Annealing

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Chinese Physics Letters 2017年第7期34卷 262-265页

作者： m.P.Sarma J.m.Kalita G.Wary Department of Physics Cotton College Guwahati 781001 India Department of Physics and Electronics Rhodes University Grahamstown 6140 South Africa

Chemically synthesized ZnS thin film is found to be a good x-ray radiation sensor. We report the effect of annealing on the x-ray radiation detection sensitivity of a ZnS thin film synthesized by a chemical bath deposition technique. The chemically synthesized ZnS films are annealed at 333, 363 and 393K for 1 h. Structural analyses show that the lattice defects in the films decrease with annealing. Further, the band gap is also found to decrease from 3.38 to 3.21 eV after annealing at 393K. Current-voltage characteristics of the films are studied under dark and x-ray irradiation conditions. Due to the decrease of lattice defects and band gap, the conductivity under dark conditions is found to increase from 2.06 × 10^-6 to 1.69 × 10^-5 S/em, while that under x-ray irradiation increases from 4.13 × 10^-5 to 5.28 ×10^-5 S/cm. On the other hand, the x-ray radiation detection sensitivity of the films is found to decrease with annealing. This decrease of detection sensitivity is attributed to the decrease of the band gap as well as some structural and surface morphological changes occurring after annealing.

关键词： ZnS X-Ray Radiation Sensing Properties of ZnS Thin Film:A Study on the Effect of Annealing

Benchmarking the ARPU and Productivity of some Biggest Telecom Operators

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China Communications 2009年第1期6卷 104-108页

作者： Thorleif Herrstrm Gunnarsson & Herrstrm HB Sweden

This study is based on 15 of the biggest telecom operators globally. It focuses on two very simple measures, ARPU and Customers per Employee. The ARPU is a measure of the wealth of the specific context of the operation. While the Customers per Employee represents the productivity of the operator. Through a benchmark analysis, it shows that no one of the big operators has the ability to have both high ARPU and high productivity. The operators acting in high ARPU markets and with high ARPU market positioning seam to get "fat and lazy", while operators that have chosen markets with low GDP/capita and thus low expected ARPU are forced to be productive. The Chinese and Indian operators are characterized by "the big home market syndrome" with both low ARPU and low productivity. But the economy of scale fertilizes their profits. The African operators have very high productivities to accommodate themselves in very low-ARPU circumstances. Further, the research points out it is more possible for the operators in the "south-east" corner to enter the "north-west" corner through acquisition.

关键词： ARPU productivity benchmarking

Pressure Dependence of the Small-Signal Gain and Saturation Intensity of a Copper Bromide Laser

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Chinese Physics Letters 2017年第8期34卷 55-58页

作者： m. E. Aeinehvand S. Behrouzinia m. K. Salem m, Elahei K. Khorasani Plasma Physics Research Center Science and Research branch Islamic Azad University Tehran Iran Photonics and Quantum Technologies Research School Nuclear Science and Technology Research School Tehran Iran

A pair of copper bromide lasers in an oscillator–amplifier configuration is used to investigate the small signal gain and saturation intensity as amplifying parameters and output power of lasers, versus pressure of buffer gas. It is shown that the amplifying parameters and laser output power have a maximum value at optimum buffer gas pressure of 11？Torr. The challenge between microscopic parameters such as stimulated emission cross section, laser upper level lifetime, and population inversion, which determine the values of laser characteristics respective to the operational pressure of buffer gas, are investigated. Thus an optimum delay time of about 10？ns is determined, and a maximum output power equivalent to about 12？W is extracted. The amplifying parameters and measured output power of laser versus delay times show some local maxima and minima at the delay time interval of 6–43？ns.

关键词： In CBL Pressure Dependence of the Small-Signal Gain and Saturation Intensity of a Copper Bromide Laser

New turbulence modeling for air/water stratified flow

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Journal of Ocean Engineering and Science 2020年第1期5卷 55-67页

作者： m.Ghafari m.B.Ghofrani Department of Energy Engineering Sharif University of TechnologyAzadi Ave.TehranIran

The prediction of interfacial turbulence characteristics is one of the still challenging of two-phase stratified *** evaluation of some important parameters such as interfacial heat transfer coefficient based on turbulence kinetic energy and turbulence dissipation rate in some models,intensifies the importance of turbulence flow correct *** gradient of velocity and turbulence kinetic energy at the interface of two-phase stratified flow leads to a major overestimation or underestimation of flow characteristics without any special *** of a source function of turbulence eddy frequency at the interface is one of the common solution employed in past *** this solution remedies some shortcomings of traditional methods in smooth stratified flow,its application in wavy stratified flow needs the other *** examination of turbulence characteristics near the free surface reveals that,in addition to turbulence eddy frequency,the other source function of turbulence kinetic energy should be considered near the free ***,a new source function of turbulence kinetic energy is proposed at the interface based on flow *** new method has been employed for Fabre et al.(1987)experiment designed for air/water stratified *** results of simulation have a good agreement with experimental data and turbulence characteristic can be captured near the free surface.

关键词： Stratified flow Turbulence model Turbulence kinetic energy Source function

Activated Anilide in Heterocyclic Synthesis： Synthesis of New Dihydropyridines, Dihydropyridazines and Thiourea Derivatives

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Chinese Journal of Chemistry 2011年第6期29卷 1154-1162页

作者： Hafiz, Ibrahim S. A. Ramiz, mahmoud m. m. Sarhan, Ahmed A. m. Department of Chemistry Faculty of Education Suez Canal University Arish Egypt Faculty of Electronic Engineering Menofia University Menouf Egypt

A series of new dihydropyridines, butanamide, dihydropyridazines and thiourea derivatives have been prepared through the reactions of 3-aminopyridine （1） and N-（pyridin-3-yl）-3-（pyridin-3-ylimino）butanamide 3 with some electrophilic reagents, aryl diazonium salts and isothiocyanates. Elementary analysis, mS, IR, and 1H NmR spectra confirmed the identity of the products.

关键词： lactones oxygen heterocycles cis-Wittig olefination mono and di-O-benzyl ethers cryptofolione stereoisomers