检索结果-南通市图书馆

Frequency-dependent viscoelasticity effects on the wave attenuation performance of multi-layered periodic foundations

在线全文

学校读者我要写书评

暂无评论

Applied mathematics and mechanics(English Edition) 2024年第3期45卷 407-424页

作者： m.SAFI m.VAKILIFARD m.J.mAHmOODI Faculty of Civil Water&Environmental EngineeringShahid Beheshti UniversityTehran ***Iran Faculty of mechanical and Energy Engineering Shahid Beheshti UniversityTehran ***Iran

In this paper,layered periodic foundations(LPFs)are numerically examined for their responses to longitudinal and transverse modes in the time and frequency *** different unit-cells,i.e.,2-layer,4-layer,and 6-layer unit-cells,comprising concrete/rubber,concrete/rubber/steel/rubber,and concrete/rubber/steel/rubber/lead/rubber materials,respectively,are taken into ***,the viscoelasticity behavior of the rubber is modeled with two factors,i.e.,a frequency-independent(FI)loss factor and a linear frequency-dependent(FD)loss *** the extraction of the complex dispersion curves and the identification of the band gaps(BGs),the simulations of wave transmission in the time and frequency domains are performed using the COmSOL *** parametric studies evaluate the effects of the rubber viscoelasticity models on the dispersion curves and the wave transmission for the longitudinal and transverse *** results show that considering the rubber viscoelasticity enhances the wave attenuation ***,the transverse-mode damping is more sensitive to the viscoelasticity model than its longitudinal *** 6-layer unit-cell LPF exhibits the lowest BG,ranging from 4.8 Hz to 6.5 Hz.

关键词： layered metamaterial periodic foundation complex dispersion curve wave transmission diagram

Dirac R-matrix calculations of photoionization cross sections of Ni Ⅻ and atomic structure data of Ni 

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2017年第2期26卷 127-140页

作者： R T Nazirt m A Bari m Bilal S Sardar m H Nasim m Salahuddin Department of Physics and Applied mathematics Pakistan Institute of Engineering and Applied Sciences Islamabad 45650 Pakista

We performed R-matrix calculations for photoionization cross sections of the two ground state configuration 3s^23p^5（~2P_（3/2,1/2）~o） levels and 12 excited states of Ni Ⅻ using relativistic Dirac Atomic R-matrix Codes（DARC） across the photon energy range between the ionizations thresholds of the corresponding states and well above the thresholds of the last level of the Ni XIII target ion. Generally, a good agreement is obtained between our results and the earlier theoretical photoionization cross sections. moreover, we have used two independent fully relativistic GRASP and FAC codes to calculate fine-structure energy levels, wavelengths, oscillator strengths, transitions rates among the lowest 48 levels belonging to the configuration（3s^23p^4, 3s3p^5, 3p^6, 3s^23p^33d） in Ni XIII. Additionally, radiative lifetimes of all the excited states of Ni XIII are presented. Our results of the atomic structure of Ni XIII show good agreement with other theoretical and experimental results available in the literature. A good agreement is found between our calculated lifetimes and the experimental *** present results are useful for plasma diagnostic of fusion and astrophysical plasmas.

关键词： photoionization cross sections energy levels wavelengths lifetimes

Complexity of charged anisotropic spherically symmetric fluids in f(G)gravity

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2023年第3期75卷 91-104页

作者： Z Yousaf m Z Bhatti m m m Nasir Department of mathematics University of the PunjabQuaid-i-Azam CampusLahore-54590Pakistan

The previous ideology of complexity factor for the dynamical spheres[Herrera et al 2018,***.D,98,104059]is extended for the influence of charge.A dynamical spherically symmetric non-dissipative and dissipative self-gravitating structure is examined in the presence of maxwell f(G)gravity to examine the complexity *** pattern of evolution is studied with the minimal complexity *** complexity factor remains the same for the structure of fluid distribution,while we examine homologous constraints for the most basic evolution *** calculate the structure scalars which play an important role in order to understand the fundamental properties of the *** fluid is geodesic as well as shearing for the dissipative case and there is a large number of *** the non-dissipative fluid distribution,a shear-free,homogeneous and isotropic,geodesic fluid correlates with the evolving homologous and vanishing complexity *** implication of the condition of vanishing complexity factor and stability are discussed at the end.

关键词： gravitation anisotropy complexity hydrodynamics

Non-Newtonian effect on natural convection flow over cylinder of elliptic cross section

在线全文

学校读者我要写书评

暂无评论

Applied mathematics and mechanics(English Edition) 2020年第2期41卷 361-382页

作者： P.NAG m.m.mOLLA m.A.HOSSAIN Department of mathematics and Physics North South UniversityDhaka 1229Bangladesh Center for Applied Scientific Computing(CASC) North South UniversityDhaka 1229Bangladesh Department of mathematics University of DhakaDhaka 1000Bangladesh

The non-Newtonian effect in the boundary layer flow over a horizontal elliptical cylinder is investigated numerically. A modified power-law viscosity model is used to correlate the non-Newtonian characteristics of the fluid flow. For natural convectionflows, the surface of the cylinder is maintained by the uniform surface temperature(UST)or the uniform heat flux(UHF) condition. The governing equations corresponding to theflow are first transformed into a dimensionless non-similar form using suitable transformations. The resulting equations are solved numerically by an efficient finite difference scheme. The numerical results are presented for the skin friction coefficient and the local Nusselt number with the eccentric angle for different values of the power-law index n. The local skin friction coefficient and the local Nusselt number are found to be higher and lower, respectively, for the shear thickening fluids(n > 1) than the other fluids(n≤1).The effects of different elliptical configurations on the average Nusselt number are also presented and discussed for both conditions of the surface temperature.

关键词： non-Newtonian fluid free convection boundary layer elliptical cylinder

Adsorption isotherm and inhibition effect of a synthesized di-(m-Formylphenol)-1,2-cyclohexandiimine on corrosion of steel X52 in HCl solution

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2016年第2期23卷 249-257页

作者： A.karimi I.Danaee H.Eskandari m.RashvanAvei Abadan Faculty of Petroleum Engineering Petroleum University of Technology Department of Chemistry K.N.Toosi University of Technology

The potential of di-(m-Formylphenol)-1,2-cyclohexandiimine as an environmentally friendly corrosion inhibitor for steel was investigated in 1 mol/L HCl using potentiodynamic polarization, electrochemical impedance spectroscopy and chronoamperometry measurements. All electrochemical measurements suggest that this compound is an excellent corrosion inhibitor for mild steel and the inhibition efficiency increases with the increase in inhibitor concentration. The effect of temperature on the corrosion behavior of mild steel with the addition of the Schiff base was studied in the temperature range from 25 °C to 65 °C. It is found that the adsorption of this inhibitor follows the Langmuir adsorption isotherms. The value of activation energy and the thermodynamic parameters such as ΔHads, ΔSads, Kads and ΔGads were calculated by the corrosion currents at different temperatures using the adsorption isotherm. The morphology of mild steel surface in the absence and presence of inhibitor was examined by scanning electron microscopy(SEm) images.

关键词： corrosion inhibitor Schiffbase adsorption Langmuir adsorption isotherm

Quantitative analysis of saindha salt using laser induced breakdown spectroscopy and cross-validation with ICP-mS

在线全文

学校读者我要写书评

暂无评论

Plasma Science and Technology 2020年第7期22卷 51-58页

作者： m QASIm m ANWAR-UL-HAQ m SHER AFGAN S U HAQ m A BAIG Department of Physics University of SargodhaSargodha 40100Pakistan Department of Energy&Power Engineering Tsinghua-BP Clean Energy CenterTsinghua UniversityBeijing 100084People’s Republic of China National Institute of Lasers and Optronics(NILOP) NiloreIslamabad 45650Pakistan National Center for Physics Quaid-i-Azam University CampusIslamabad 45320Pakistan

Saindha salt is considered to be more advantageous than the other edible salts for the patients suffering from diabetes,blood pressure and kidney *** explore the constituent elements of this salt,laser induced breakdown spectroscopy(LIBS) has been exploited for its qualitative and quantitative *** third harmonic(355 nm) of a Q-switched Nd:YAG laser has been used to produce the saindha salt plasma and the time integrated optical emission spectra were registered using a set of six miniature spectrometers covering the spectral range of 230-805 *** spectroscopic analysis of the emission spectra predominately revealed numerous neutral or singly ionized emission lines of Ca,mg,Na,K,Fe,Sr,Si,Li and *** laser produced plasma was characterized by calculating the electron temperature from the Boltzmann plots and the electron number density from the Stark broadened line profile as a function of laser irradiance and distance from the target *** relative concentration of the constituent elements was extracted by the integrated line intensities of the strongest spectral line of each element using the self-calibration-LIBS(SC-LIBS) and one-line calibration free-LIBS(OLCF-LIBS) *** cross-validation,the LIBS results have been compared with that obtained from the inductively coupled plasma-mass spectroscopy(ICP-mS) showing good agreement.

关键词： elemental analysis CF-LIBS plasma parameters

Use of breakthrough experiment to evaluate the performance of hydrogen isotope separation for metal-organic frameworks m-mOF-74(m=Co, Ni, mg, Zn)

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2020年第7期63卷 881-889页

作者： Yanan Si Wenjing Wang El-Sayed m.El-Sayed Daqiang Yuan State Key Laboratoty of Structural Chemistry Fujian Institute o f Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China University of the Chinese Academy of Sciences Beijing 100049China Chemical Refining Laboratory Refining DepartmentEgyptian Petroleum Research InstituteNasr CityCairoEgypt

The unique adsorption performance of metal-organic frameworks(mOFs) indicates a new direction for gas separation and purification. The low-temperature distillation, as a traditional technique for hydrogen isotope separation, is limited as it is a high energy-and cost-intensive process. Instead of utilizing such a conventional separation route, we use ordered microporous frameworks based on a physical adsorption mechanism to solve the challenge of hydrogen isotope separation. Herein we analyze m-mOF-74(m=Co, Ni, mg, Zn), featuring a hexagonal channel about 11 ? and high density of open metal sites, for their ability to separate and purify deuterium from the hydrogen isotope mixture by dynamic column breakthrough experiments. Our results show that the combination of the strength of binding sites, density of coordinatively unsaturated metal sites and hydrogen isotope adsorption capacity of materials renders Co-mOF-74 as an optimal adsorbent for the capture of deuterium from hydrogen isotope mixtures in a simulated industrial process.

关键词： hydrogen isotope separation breakthrough experiment mOF-74

Electron Density and Optical Emission measurements of SF_6/O_2 Plasmas for Silicon Etch Processes

在线全文

学校读者我要写书评

暂无评论

Plasma Science and Technology 2012年第4期14卷 316-320页

作者： m.m.mORSHED S.m.DANIELS National Centre for Plasma Science and Technology School of Electronic EngineeringDublin City UniversityGlasnevinDublin 9Ireland

This work investigates internal plasma process parameters using a hairpin resonance probe and optical emission spectroscopy. The dependence of electron density and atomic fluorine on the percentage of oxygen in an SF6/O2 discharge was measured using these methods. An RIE Oxford Instruments 80 plus chamber was used for the experiments. Two different process powers （100 W and 300 W） at a constant pressure （100 mTorr） were used, and it was found that the optical emission intensity of the 703.7 nm and 685.6 nm lines of atomic fluorine increased rapidly as oxygen was added to the SF6 discharge, reached their maximum at an O2 fraction of 20% and then decreased with further addition of oxygen. The plasma electron density was also strongly influenced by the addition of O2.

关键词： OES hairpin probe SF6 O2 electron density atomic fluorine

Relativistic symmetry of position-dependent mass particles in a Coulomb field including tensor interaction

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2013年第3期22卷 122-128页

作者： m.Eshghi m.Hamzavi S.m.Ikhdair Physics Department Imam Hossein Comprehensive UniversityTehranIran Department of Science and Engineering Abhar BranchIslamic Azad UniversityAbharIran Department of Electrical and Electronic Engineering Near East University922022NicosiaNorthern CyprusTurkey Department of Physics Faculty of ScienceAn-Najah National UniversityNablusWest BankPalestine

The spatially-dependent mass Dirac equation is solved exactly for attractive scalar and repulsive vector Coulomb potentials,including a tensor interaction under the spin and pseudospin symmetric *** forms of the energy eigenvalue equation and wave functions are obtained for arbitrary spin-orbit quantum number κ.Some numerical results are also given,and the effect of tensor interaction on the bound states is *** is shown that tensor interaction removes the degeneracy between two states in the spin *** also investigate the effects of the spatially-dependent mass on the bound states under spin symmetric limit conditions in the absence of tensor interaction.

关键词： Dirac equation spin and pseudospin symmetries spatially-dependent mass tensor interaction