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Transient analysis of a three-layer microbeam subjected to electric potential

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International Journal of Smart and Nano materials 2017年第1期8卷 20-40页

作者： mohammad Arefi Ashraf m.Zenkour Department of Solid mechanics Faculty of Mechanical EngineeringUniversity of KashanKashanIran Department of mathematics Faculty of ScienceKing Abdulaziz UniversityJeddahSaudi Arabia Department of mathematics Faculty of ScienceKafrelsheikh UniversityKafrelsheikhEgypt

In this paper,free vibration,wave propagation,and bending analyses of a sandwich microbeam integrated with piezoelectric face-sheets resting on Pasternak foundation under electric potential are presented based on the strain gradient theory and Euler–Bernoulli beam *** material properties of core are assumed variable along the thickness direction and piezoelectric face-sheets are assumed homogeneous piezoelectric materials.A two-dimensional electric potential distribution along the axial and transverse direction is applied on the face-sheets of *** principal is used to derive governing differential equations of *** behaviors of sandwich microbeam including free vibration,wave propagation,and bending analyses are studied in this *** numerical results are presented to capture the effect of important parameters of the problem such as in-homogeneous index,applied voltage,parameters of foundation,and material length *** numerical results indicate that the effect of electric potential along the axial direction is very small rather than one along the transverse direction where initial voltage is applied.

关键词： Euler–Bernoulli three-layer microbeam free vibration wave propagation electric potential applied voltage

Relative accuracy of spatial predictive models for lynx Lynx canadensis derived using logistic regression-AIC,multiple criteria evaluation and Bayesian approaches

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Current Zoology 2009年第1期55卷 28-40页

作者： Hejun KANG Shelley m. ALEXANDER Center for Spatial Analysis School of Geography and Earth Sciences McMaster University Hamilton ON Canada L8S 4K1 Department of Geography University of Calgary Calgary AB Canada T2N 1N4

We compared probability surfaces derived using one set of environmental variables in three Geographic Information Systems （GIS） -based approaches： logistic regression and Akaike＇s Information Criterion （AIC）, multiple Criteria Evaluation （mCE）, and Bayesian Analysis （specifically Dempster-Shafer theory）. We used lynx Lynx canadensis as our focal species, and developed our environment relationship model using track data collected in Banff National Park, Alberta, Canada, during winters from 1997 to 2000. The accuracy of the three spatial models were compared using a contingency table method. We determined the percentage of cases in which both presence and absence points were correctly classified （overall accuracy）, the failure to predict a species where it occurred （omission error） and the prediction of presence where there was absence （commission error）. Our overall accuracy showed the logistic regression approach was the most accurate （74.51%）. The multiple criteria evaluation was intermediate （39.22%）, while the Dempster-Shafer （D-S） theory model was the poorest （29.90%）. However, omission and commission error tell us a different story： logistic regression had the lowest commission error, while D-S theory produced the lowest omission error. Our results provide evidence that habitat modellers should evaluate all three error measures when ascribing confidence in their model. We suggest that for our study area at least, the logistic regression model is optimal. However, where sample size is small or the species is very rare, it may also be useful to explore and/or use a more ecologically cautious modelling approach （e.g. Dempster-Shafer） that would over-predict, protect more sites, and thereby minimize the risk of missing critical habitat in conservation plans .

关键词： Bayesian Analysis (Dempster-Shafer) GIS Habitat Logistic regression Lynx canadensis multiple Criteria Evaluation (mCE)

The effect of severe plastic deformation on the mg properties after CEC deformation

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Journal of magnesium and Alloys 2020年第3期8卷 761-768页

作者： B.Suikowski m.Janoska G.Boczkal R.Chulist m.mroczkowski P.Paika Department of Non-Ferrous metals Engineering Faculty of Non-Ferrous MetalsAGH University of Science and Technology30 Mickiewicza Av.Krakow 30-059Poland Institute of metallurgy and materials Science Polish Academy of Sciences25 Reymonta St.Krakow 30-059Poland

In this study,the effect of severe plastic deformation on the mg grain refinement and recovery mechanism was *** pure magnesium was deformed at room temperature by cycling extrusion-compression(CEC)process up to large *** steps of deformation have been used by applying 1,2 and 4 passes of CEC giving a total effective plastic strain ofε=*** and structural properties of mg in initial state and the states after successive steps of deformation were *** mechanical properties were determined by microhardness and compression tests at room *** structural investigations involved light microscope observations,electron back scattered diffraction and texture measurements by X-ray *** was found that the CEC process refines the grain size down to 6.4μm and reduces strong rolling texture ***,only the first two passes had a strong effect on mechanical properties while a larger number of CEC cycles(above 4)led to failure of the samples with a small effect on *** observation correlates with texture evolution indicating a more random orientation distribution that slows down the typical for hep metals rapid work *** was found that the CEC process activated twin dynamic recrystallization in deformed *** process led to the formation of new randomly oriented grains inside the twinned areas and as a consequence it reduced the strong rolling texture components.

关键词： magnesium Cyclic extrusion compression Texture microhardness

Physical activity and mental well-being during COVID-19 pandemic

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World Journal of Psychiatry 2021年第12期11卷 1267-1273页

作者： Walid Kamal Abdelbasset Gopal Nambi marwa m Eid Safaa m Elkholi Department of Health and Rehabilitation Sciences College of Applied Medical SciencePrince Sattam Bin Abdulaziz UniversityAl-Kharj 11942RiyadhSaudi Arabia Department of Physical Therapy Kasr Al-Aini HospitalCairo UniversityGiza 12613Egypt Department of Physical Therapy College of Applied Medical SciencesTaif UniversityTaif 26571Saudi Arabia Department of Rehabilitation Sciences Faculty of Health and Rehabilitation SciencesPrincess Nourah bint Abdulrahman UniversityRiyadh 11564Saudi Arabia

The corona virus disease 2019(COVID-19)pandemic has resulted in most nations deciding upon self-isolation and social distancing policies for their citizens to control the pandemic and reduce hospital *** review aimed at evaluating the effect of physical activity on mental well-being during the COVID-19 *** was concluded that the COVID-19 pandemic may lead to augmented levels of angiotensin-converting enzyme(ACE)-2 that led to cardiovascular and neurological disorders associated with highly inflammatory effects of viral infection affecting the brain tissues leading to damage of the nervous system and resulting in cognition dysfunction,insulin sensitivity reduction,and behavioral *** and depression may lead to negative effects on various quality of life domains,such as being physically *** physical activities may reduce inflammatory responses,improve ACE-2 responses,and improve mental well-being during self-isolation and social distancing policies related to the COVID-19 *** studies should be conducted to assess the different intensities of physical activities on cardiovascular function,and mental well-being during the COVID-19 pandemic.

关键词： COVID-19 Physical activity mental well-being Pandemic Angiotensinconverting enzyme-2

ON SEVERAL NEW mETHODS TO POLAR DECOmPOSITION COmPUTATION

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Acta mechanica Solida Sinica 1998年第4期11卷 329-340页

作者： Huang, mJ Li, m Fu, mF Nanchang Univ Inst Engn Mech Nanchang 330029 Peoples R China

In this paper, the polar decomposition of a deformation gradient tensor is analyzed in detail. The four new methods for polar decompositioncomputation are given: (1) the iterated method, (2) the principal invariant's method, (3) the principal rotation axis' s method, (4) the coordinate transformation's method. The iterated method makes it possible to establish the nonlinear finite element method based on polar decomposition. Furthermore, the material time derivatives of the stretch tensor and the rotation tensor are obtained by explicit and simple expressions.

关键词： polar decomposition deformation gradient stretch tensor rotation tensor large deformation and large rotation

DC Programming Algorithm for Clusterwise Linear L1 Regression

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Journal of the Operations Research Society of China 2017年第2期5卷 233-256页

作者： Adil m.Bagirov Sona Taheri Faculty of Science and Technology Federation University AustraliaBallaratAustralia

The aim of this paper is to develop an algorithm for solving the clusterwise linear least absolute deviations regression *** problem is formulated as a nonsmooth nonconvex optimization problem,and the objective function is represented as a difference of convex *** conditions are derived by using this *** algorithm is designed based on the difference of convex representation and an incremental *** proposed algorithm is tested using small to large artificial and real-world data sets.

关键词： Clusterwise regression Nonsmooth optimization Smoothing Incremental algorithm

Improvements in Inversion of magnetic Resonance Exploration-Water Content, Decay Time, and Resistivity

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Journal of China University of Geosciences 2009年第3期20卷 592-605页

作者： Ugur Yaramanci mike müller-Petke Leibniz Institute of Applied Geophysics Stilleweg 2 Hannover D-30655 Germany Berlin University of Technology Ackerstrasse 71-76 Berlin D-13355 Germany

In this review article, we present recent developments and improvements in magnetic resonance sounding （mRS）, a newly established geophysical exploration method that provides unique information about hydrogeophysical properties due to its direct sensitivity to hydrogen protons and proton dynamics. Starting with the most sophisticated and complete mRS formulation, we give a detailed view on how to solve the equation, i.e., inverting exactly for all model parameters： water content, decay time, and resistivity. Giving a short review of general inversion schemes used in geophysics, the special properties of mRS inversion are evaluated and the development of mRS inversion over recent years is shown. We present the extension of mRS to magnetic resonance tomography （mRT）, i.e., the extension to two-dimensional investigations and appropriate inversions. Finally, we address restrictions, limitations, and inconsistencies as well as future developments.

关键词： magnetic resonance sounding (mRS) magnetic resonance tomography (mRT) inversion modeling water content decay time resistivity.

The threshold for a stochastic within-host CHIKV virus model with saturated incidence rate

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International Journal of Biomathematics 2021年第6期14卷 141-172页

作者： C.Gokila m.Sambath Department of mathematics Periyar University Salem 636011India

This paper deals with stochastic Chikungunya(CHIKV)virus model along with saturated incidence *** show that there exists a unique global positive solution and also we obtain the conditions for the disease to be *** also discuss about the existence of a unique ergodic stationary distribution of the model,through a suitable Lyapunov *** stationary distribution validates the occurrence of disease;through that,we find the threshold value for prevail and disappear of disease within *** the help of numerical simulations,we validate the stochastic reproduction number Rq as stated in our theoretical findings.

关键词： Chikungunya infection model extinction threshold stationary distribution

Axisymmetric Stagnation-Point Flow of Nanofluid Over a Stretching Surface

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Advances in Applied mathematics and mechanics 2014年第2期6卷 220-232页

作者： m.Nawaz T.Hayat Department of Humanities and Sciences Institute of Space Technology P.O.Box 2750Islamabad 44000Pakistan Department of mathematics Quaid-i-Azam University 45320 Islamabad 44000Pakistan Department of mathematics Faculty of SciencesKing Abdulaziz UniversityJeddah 80253Saudi Arabia

This paper investigates the laminar boundary layer flow of nanofluid induced by a radially stretching *** model exhibiting Brownian motion and thermophoresis is *** solutions for a reduced system of nonlinear ordinary differential equations are obtained by homotopy analysis method(HAm).Comparative study between the HAm solutions and previously published numerical results shows an excellent ***,temperature and mass fraction are displayed for various values of *** local skin friction coefficient,the local Nusselt number and the local Sherwood number are *** is observed that the presence of nanoparticles enhances the thermal conductivity of base *** is found that the convective heat transfer coefficient(Nusselt number)is decreased with an increase in concentration of nanoparticles whereas Sherwood number increases when concentration of nanoparticles in the base fluid is increased.

关键词： Nanofluid axisymmetric flow stagnation point Nusselt number Sherwood number