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Thermal instability and dynamic response analysis of a tensioned carbon nanotube under moving uniformly distributed external pressure

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Nano materials Science 2021年第1期3卷 75-88页

作者： A.A.Yinusa m.g.Sobamowo Department of mechanical Engineering University of LagosAkokaLagos StateNigeria

Single-walled carbon nanotubes(SWCNTs)are receiving immense research attention due to their tremendous thermal,electrical,structural and mechanical *** this paper,an exact solution of the dynamic response of SWCNT with a moving uniformly distributed load is *** SWCNT is modelled via the theories of Bernoulli-Euler-thermal elasticity mechanics and solved using Integral *** developed closed-form solution in the present work is compared with existing results and excellent agreements are *** parametric studies show that as the magnitude of the pressure distribution at the surface increases,the deflection associated with the single walled nanotube increases at any mode whilst a corresponding increase in temperature and foundation parameter have an attenuating effect on ***,an increase in the Winkler parameter,as well as a decrease in the SWCNT mass increases its frequency of ***,an increase in the speed of the external agent decreases the total external pressure as a result of the removal of dead *** present work is envisaged to improve the application of SWCNT as nanodevices for structural,electrical and mechanical systems.

关键词： Thermal and moving external uniform pressure Tensioned carbon nanotube Dynamic and stability analysis Integral transform

Ion acoustic shock and periodic waves through Burgers equation in weakly and highly relativistic plasmas with nonextensivity

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Plasma Science and Technology 2017年第1期19卷 7-19页

作者： m g HAFEZ N C ROY m R TALUKDER m HOSSAIN ALI Department of of Applied mathematics University of Rajshahi Rajshahi-6205 Bangladesh Department of mathematics Chittagong University of Engineering and Technology Chittagong-4349Bangladesh Plasma Science and Technology Lab Department of Applied Physics and Electronic EngineeringUniversity of Rajshahi Rajshahi-6205 Bangladesh

A comparative study is carried out for the nonlinear propagation of ion acoustic shock waves both for the weakly and highly relativistic plasmas consisting of relativistic ions and qdistributed electrons and *** Burgers equation is derived to reveal the physical phenomena using the well known reductive perturbation *** integration of the Burgers equation is performed by the（g￠/g）-expansion *** effects of positron concentration,ion–electron temperature ratio,electron–positron temperature ratio,ion viscosity coefficient,relativistic streaming factor and the strength of the electron and positron nonextensivity on the nonlinear propagation of ion acoustic shock and periodic waves are presented graphically and the relevant physical explanations are provided.

关键词： electron-positron-ion plasmas ion acoustic shock and periodic waves weakly and highly relativistic effects Burgers equation

The impact of alpha-fetoprotein(AFP),child-turcotte-pugh(CTP)score and disease staging on the survival of hepatocellular carcinoma(HCC)patients:a retrospective cohort from single oncology center

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Oncology Research 2025年第1期33卷 149-160页

作者： NASSER mULLA YOUSEF KATIB ASIm m.ALmUgHAmSI DUAA S.ALKHAYAT mOHAmED mOSAAD SAmIR T.ALFOTIH RAWAN ALAOFI Department of Internal medicine Faculty of MedicineTaibah UniversityMadinah42278Saudi Arabia Department of Radiology Faculty of MedicineTaibah UniversityMadinah42278Saudi Arabia Department of Surgery Faculty of MedicineTaibah UniversityMadinah42278Saudi Arabia Department of Endemic and Infectious Diseases Suez Canal UniversityIsmailia41522Egypt King Salman bin Abdulaziz medical City Madinah42311Saudi Arabia Prince mohammed Bin Abdulaziz Hospital Madinah41511Saudi Arabia

Background:Hepatocellular carcinoma(HCC)is the most common cause of cancer-related death in Saudi *** study aimed to investigate the patterns of HCC and the effect of TNm staging,Alfa-fetoprotein(AFP),and Child-Turcotte Pugh(CTP)on patients’overall survival(OS).methods:A retrospective analysis was conducted on 43 HCC patients at a single oncology center in Saudi Arabia from 2015 to *** patients had to fulfill one of the following criteria:(a)a liver lesion reported as definitive HCC on dynamic imaging and/or(b)a biopsy-confirmed ***:The mean patient age of all HCC cases was 66.8 with a male-to-female ratio of 3.3:*** patients were stratified into two groups:viral HCC(n=22,51%)and non-viral HCC(n=21,49%).Among viral-HCC patients,55%were due to HBV and 45%due to *** was diagnosed in 79%of *** and sex did not significantly statistically differ in OS among viral and non-viral HCC patients(p-value>0.05).About 65%of patients had tumor size>5 cm during the diagnosis,with a significant statistical difference in OS(p-value=0.027).AFP was>400 ng/ml in 45%of the *** was a statistically significant difference in the OS in terms of AFP levels(p-value=0.021).A statistically significant difference was also observed between the CTP score and OS(p-value=0.02).CTP class B had the longest *** was the most common treatment provided to HCC patients followed by sorafenib *** was a significant statistical difference in OS among viral and non-viral HCC patients(p-value=0.008).Conclusions:The most common predictors for OS were the underlying cause of HCC,AFP,and tumor *** having non-viral etiology,a tumor size>5 cm,an AFP>400 ng/mL,and a CTP score class C were all negatively associated with OS.

关键词： Hepatocellular carcinoma Pattern Alpha-fetoprotein(AFP) Child-turcotte-pugh Progression free survival

The adsorption and corrosion inhibition of 8-hydroxy-7-quinolinecarboxaldehyde derivatives on C-steel surface in hydrochloric acid

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Chinese Journal of Chemical Engineering 2017年第9期25卷 1256-1265页

作者： A.m.Eldesoky S.g.Nozha Engineering Chemistry Department High Institute of Engineering & Technology Al-Qunfudah Center for Scientific Research (QCSR) Al-Qunfudah University College Umm Al-Qura University ministry of Health Domyat Laboratory

The protection influence of 8-hydroxy-7-quinolinecarboxaldehyde derivatives against C-steel corrosion was studied in 2 mol·L^(-1)HCl solutions at 30 °C. measurements were conducted under various experimental conditions using weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy(EIS) and electrochemical frequency modulation(EFm) techniques. These studies have shown that 8-hydroxy-7-quinolinecarboxaldehyde derivatives are very good "green", mixed-type inhibitors. Corrosion rates obtained from both EFm and EIS methods are comparable with those recorded using Tafel extrapolation method, confirming validation of corrosion rates measured by the latter. The inhibitive action of these 8-hydroxy-7-quinolinecarboxaldehyde derivatives was discussed in terms of blocking the electrode surface by adsorption of the molecules through the active centers contained in their structures following Langmuir adsorption isotherm. Quantum chemical method was also employed to explore the relationship between the inhibitor molecular properties and its protection efficiency.

关键词： 8-Hydroxy-7-quinolinecarboxaldehyde derivatives C-steel HCl EFm

modeling and Simulation of microstructurally Small Crack Formation and growth in Notched Nickel-base Superalloy Component

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Journal of materials Science & Technology 2014年第3期30卷 203-212页

作者： g.m.Owolabi H.A.Whitworth Department of mechanical Engineering Howard University

Studies on microstructurally small fatigue cracks have illustrated that heterogeneous microstructural features such as inclusions, pores, grain size distribution as well as precipitate size distribution and volume fraction create stochasticity in their behavior under cyclic loads. Therefore, to enhance safe-life and damage-tolerance approaches, accurate modeling of the influence of these heterogeneous microstructural features on microstructurally small crack formation and growth from stress raisers is necessary. In this work, computational micromechanics was used to predict the high cycle fatigue of microstructurally small crack formation and growth in notched polycrystalline nickel-base superalloys and to quantify the variability in the driving force for formation and growth of microstructurally small crack from notch root in the matrix with non-metallic inclusions. The framework involves computational modeling to obtain three-dimensional perspectives of microstructural features influencing fatigue crack growth in notched nickel-base superalloys, which accounts for the effects of nonlocal notch root plasticity, loading, microstructural variability, and extrinsic defects on local cyclic plasticity at the microstructure-scale level. This approach can be used to explore sensitivity of minimum fatigue lifetime to microstructures. The simulation results obtained from this framework were calibrated to existing experimental results for polycrystalline nickel-base superalloys.

关键词： microstructuraliy small crack Crystal plasticity Nickel-base superalloy Fatigue life

SURFACE FINITE ELEmENTS FOR PARABOLIC EQUATIONS

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Journal of Computational mathematics 2007年第4期25卷 385-407页

作者： g. Dziuk C.m. Elliott Abteilung für Angewandte mathematik University of Freiburg Hermann-Herder-Straβe 10 D-79104Freiburg i. BrGermany Department of mathematics University of Sussex Falmer Brighton BN1 9RF United Kingdom

In this article we define a surface finite element method （SFEm） for the numerical solution of parabolic partial differential equations on hypersurfaces F in R^n＋1. The key idea is based on the approximation of F by a polyhedral surface Гh consisting of a union of simplices （triangles for n = 2, intervals for n = 1） with vertices on Г. A finite element space of functions is then defined by taking the continuous functions on Гh which are linear affine on each simplex of the polygonal surface. We use surface gradients to define weak forms of elliptic operators and naturally generate weak formulations of elliptic and parabolic equations on Г. Our finite element method is applied to weak forms of the equations. The computation of the mass and element stiffness matrices are simple and straightforward. We give an example of error bounds in the case of semi-discretization in space for a fourth order linear problem. Numerical experiments are described for several linear and nonlinear partial differential equations. In particular the power of the method is demorrstrated by employing it to solve highly nonlinear second and fourth order problems such as surface Allen-Cahn and Cahn-Hilliard equations and surface level set equations for geodesic mean curvature flow.

关键词： Surface partial differential equations Surface finite element method geodesic curvature Triangulated surface.

CFD Based Determination of Dynamic Stability Derivatives in Yaw for a Bird

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Journal of Bionic Engineering 2007年第4期4卷 201-208页

作者： m. A. moelyadi g. Sachs Aeronautics and Astronautics Department Bandung Institute of Technology Ganesha 10 40132 Bandung Indonesia Institute of Flight mechanics and Flight Control Technische Universitt München Boltzmannstrasse 15 85748 Garching Germany

Dynamic yaw stability derivatives of a gull bird are determined using Computational Fluid Dynamics（CFD） method. Two kinds of motions are applied for calculating the dynamic yaw stability derivatives CNr and CNβ. The first one relates to a lateral translation and, separately, to a yaw rotation. The second one consists of a combined translational and rotational motion. To determine dynamic yaw stability derivatives, the simulation of an unsteady flow with a bird model showing a harmonic motion is performed. The flow solution for each time step is obtained by solving unsteady Euler equations based on a finite volume approach for a small reduced frequency. Then, an evaluation of unsteady forces and moments for one cycle is conducted using harmonic Fourier analysis. The results of the dynamic yaw stability derivatives for both simulations of the model show a good agreement.

关键词： dynamic yaw stability CFD Fourier analysis unsteady aerodynamics reduced frequency

Scaling of residual displacements in terms of elastic and inelastic spectral displacements for existing SDOF systems

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Earthquake Engineering and Engineering Vibration 2020年第1期19卷 71-85页

作者： m.g.Harikrishnan Vinay K.gupta Department of Civil Engineering Indian Institute of Technology Kanpur

Structures undergoing inelastic displacements during earthquake ground motions are known to sustain some amount of residual displacements, which may make them unusable or unsafe. In this study an attempt is made to estimate residual displacements for elastic-perfectly-plastic single-degree-of-freedom oscillators with a given lateral strength ratio. It is observed in the case of a class of ground motions that there are no trends in the dependence of residual displacement on the temporal features of the ground motion, and thus any estimation of residual displacements should be carried out only in the statistical sense. Statistical estimation of residual displacement spectrum via normalization with respect to inelastic or elastic spectral displacements is considered, and it is found that normalization with respect to inelastic spectral displacements is preferable. Expressions for residual displacement spectra are proposed for both types of normalizations and for the givenlateral-strength-ratio type oscillators.

关键词： residual displacement spectrum lateral strength ratio elastic-perfectly-plastic oscillator inelastic displacement spectrum elastic displacement spectrum horizontal ground motions

Hartree-Fock-Roothaan Calculations for ground States of Some Atoms Using minimal Basis Sets of Integer and Noninteger n-STOs

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Chinese Journal of Chemistry 2004年第11期22卷 1262-1266页

作者： gümü■ Sedat ZSO■AN Telhat Department of Physics Amasya Education Faculty Ondokuz Mayis University 05189 Amasya TURKEYDepartment of Physics Amasya Education Faculty Ondokuz Mayis University 05189 Amasya TURKEY

Hartree-Fock-Roothaan (HFR) calculations for ground states of some atoms, i.e. He, Be, Ne, Ar, and Kr have been performed using minimal basis sets of Slater type orbitals (STOs) with integer and noninteger principal quan-tum numbers (integer n-STOs and noninteger n-STOs). The obtained total energies for these atoms using minimal basis sets of integer n-STOs are in good agreement with those in the previous literature. On the other hand, for the case of minimal basis sets of noninteger n-STOs, although the calculated total energies of these atoms agree well with the results in literature, some striking results have been obtained for atoms Ar and Kr. Our computational re-sults for the energies of atoms Ar and Kr are slightly better than those in literature, by amount of 0.00222 and 0.000054 a.u., respectively. The improvement in the energies of atoms Ar and Kr may result from the efficient cal-culations of one-center two-electron integrals over noninteger n-STOs. For some atomic ions in their ground state, HFR calculations have been carried out using minimal basis sets of noninteger n-STOs. The obtained total energies for these atomic ions are substantially lower than those available in literature.

关键词： Hartree-Fock-Roothaan Slater type orbital