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Probabilistic stability of uncertain composite plates and stochastic irregularity in their buckling mode shapes:A semi-analytical non-intrusive approach

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Frontiers of Structural and Civil Engineering 2023年第2期17卷 179-190页

作者： Arash Tavakoli MALEKI Hadi PARVIZ akbar A.KHATIBI Mahnaz ZAKERI Advanced Structures Research Laboratory K.N.Toosi University of TechnologyTehran 16569-83911Iran Faculty of New Sciences and Technologies University of TehranTehran 16569-83911Iran School of Engineering RMIT UniversityMelbourne VIC 3001Australia

In this study,the mechanical properties of the composite plate were considered Gaussian random fields and their effects on the buckling load and corresponding mode shapes were studied by developing a semi-analytical nonintrusive *** random fields were decomposed by the Karhunen−Loève *** strains were defined based on the assumptions of the first-order and higher-order shear-deformation *** equations of motion were extracted using Euler-Lagrange *** probabilistic response space was obtained by employing the nonintrusive polynomial chaos ***,the effect of spatially varying stochastic properties on the critical load of the plate and the irregularity of buckling mode shapes and their sequences were studied for the first *** findings showed that different shear deformation plate theories could significantly influence the reliability of thicker plates under compressive *** is suggested that a linear relationship exists between the mechanical properties’variation coefficient and critical loads’variation ***,in modeling the plate properties as random fields,a significant stochastic irregularity is obtained in buckling mode shapes,which is crucial in practical applications.

关键词： uncertain composite plate stochastic assume mode method Karhunen−Loève theorem polynomial chaos approach plate buckling irregularity in buckling mode shapes

Foliations on the tangent bundle of Finsler manifolds

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Science China Mathematics 2012年第3期55卷 647-662页

作者： PEYGHAN Esmaei TAYEBI akbar ZHONG ChunPing Department of Mathematics Faculty of Science Arak University Arak *** Iran Department of Mathematics Faculty of Science Qom University Qom *** Iran School of Mathematical Sciences Xiamen University Xiamen 361005 China

Let M be a smooth manifold with Finsler metric F,and let T M be the slit tangent bundle of M with a generalized Riemannian metric G,which is induced by *** this paper,we prove that (i) (M,F) is a Landsberg manifold if and only if the vertical foliation F V is totally geodesic in (T M,G);(ii) letting a:= a(τ) be a positive function of τ=F 2 and k,c be two positive numbers such that c=2 k(1+a),then (M,F) is of constant curvature k if and only if the restriction of G on the c-indicatrix bundle IM (c) is bundle-like for the horizontal Liouville foliation on IM (c),if and only if the horizontal Liouville vector field is a Killing vector field on (IM (c),G),if and only if the curvature-angular form Λ of (M,F) satisfies Λ=1-a 2/R on IM (c).

关键词： Finsler manifold g-natural metrics Riemannian foliation

Application of artificial neural networks in optimal tuning of tuned mass dampers implemented in high-rise buildings subjected to wind load

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Earthquake Engineering and Engineering Vibration 2018年第4期17卷 903-915页

作者： Meysam Ramezani akbar Bathaei Amir K.Ghorbani-Tanha School of Civil Engineering College of Engineering University of Tehran

High-rise buildings are usually considered as flexible structures with low inherent damping. Therefore, these kinds of buildings are susceptible to wind-induced vibration. Tuned Mass Damper（TMD） can be used as an effective device to mitigate excessive vibrations. In this study, Artificial Neural Networks is used to find optimal mechanical properties of TMD for high-rise buildings subjected to wind load. The patterns obtained from structural analysis of different multi degree of freedom（MDF） systems are used for training neural networks. In order to obtain these patterns, structural models of some systems with 10 to 80 degrees-of-freedoms are built in MATLAB/SIMULINK program. Finally, the optimal properties of TMD are determined based on the objective of maximum displacement response reduction. The Auto-Regressive model is used to simulate the wind load. In this way, the uncertainties related to wind loading can be taken into account in neural network’s outputs. After training the neural network, it becomes possible to set the frequency and TMD mass ratio as inputs and get the optimal TMD frequency and damping ratio as outputs. As a case study, a benchmark 76-story office building is considered and the presented procedure is used to obtain optimal characteristics of the TMD for the building.

关键词： artificial neural networks tuned mass damper wind load auto-regressive model optimal frequency anddamping

Chip-scale gas chromatography:From injection through detection

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Microsystems & Nanoengineering 2015年第1期1卷 8-15页

作者： Muhammad akbar Michael Restaino Masoud Agah VT MEMS Laboratory Bradley Department of Electrical and Computer EngineeringVirginia TechBlacksburgVA 24061USA Department of Biomedical Engineering and Mechanics Virginia TechBlacksburgVA 24061USA

Miniaturized gas chromatography(μGC)systems hold potential for the rapid analysis of volatile organic compounds(VOCs)in an extremely compact and low-power enabled ***,we utilize microfabrication technology to demonstrate the single chip integration of the key components of aμGC system in a two-step planar fabrication *** 1.5×3 cm microfluidic platform includes a sample injection unit,a micromachined semi-packed separation column(μSC)and a micro-helium discharge photoionization detector(μDPID).The sample injection unit consists of a T-shaped channel operated with an equally simple setup involving a single three-way fluidic valve,a micropump for sample loading and a carrier gas supply for subsequent analysis of the *** innovative sample injection technique described herein requires a loading time of only a few seconds and produces sharp and repeatable sample pulses(full width at half maximum of approximately 200 ms)at a carrier gas flow rate that is compatible with efficient chromatographic ***,our comprehensive characterization of the chip reveals that a wide variety of VOCs with boiling points in the range of 110–216℃ can be analyzed in less than 1 min by optimizing the flow and temperature programming ***,the analysis of four VOCs at the concentration level of one part per million in an aqueous sample(which corresponds to a headspace concentration in the lower parts-per-billion regime)was performed with a sampling time of only 6 *** μDPID has demonstrated a linear dynamic range over three orders of *** system presented here could potentially be used to monitor hazardous VOCs in real time in industrial workplaces and residential settings.

关键词： gas chromatography lab-on-a-chip MEMS microsystem

Effect of microwave pretreatment on grinding and flotation kinetics of copper complex ore

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International Journal of Minerals,Metallurgy and Materials 2021年第12期28卷 1887-1897页

作者： Hamed Gholami Bahram Rezai Ahmad Hassanzadeh akbar Mehdilo Mohammadreza Yarahmadi Department of Mining and Metallurgical Engineering Amirkabir University of TechnologyTehran 158754413Iran Department of Geoscience and Petroleum Faculty of Engineering ScienceNorwegian University of Science and TechnologyNO-7491TrondheimNorway Faculty of Engineering University of Mohaghegh ArdabiliArdabil ***Iran Research and Development Division Sarcheshmeh Copper MineNational Iranian Copper Industries CompanyRafsanjanIran

The present study initially investigates the kinetics of microwave-assisted grinding and flotation in a porphyry copper *** tests were conducted on untreated and microwave-irradiated samples by varying the exposure time from 15 to 150 *** microscopy,energy-dispersive X-ray spectroscopy,and scanning electron microscopy were conducted to determine the mineral liberation and particle surface properties,and to perform mineralogical *** showed that the ore breakage rate constant monotonically increased by increasing the exposure time,particularly for the coarsest fraction size(400μm)due to the creation of thermal stress fractures alongside grain *** irradiation time(>60 s)led to the creation of oxidized and porous surfaces along with a dramatic change in particle morphologies that result in a substantial reduction of chalcopyrite and pyrite flotation rate constants and ultimate *** concluded that MW-pretreated copper ore was ground faster than the untreated variety,but the two types have slightly similar floatabilities.

关键词： grinding microwave copper

Blood flow analysis in tapered stenosed arteries with pseudoplastic characteristics

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International Journal of Biomathematics 2014年第6期7卷 89-106页

作者： Noreen Sher akbar S. Nadeem National University of Sciences and Technology Islamabad Pakistan Department of MathematicsQuaid-i-Azam University 45320 Islamabad 44000 Pakistan

In this paper, the blood flow through a tapered artery with a stenosis by considering axially non-symmetric but radially symmetric mild stenosis on blood flow characteristics is analyzed, assuming the flow is steady and blood is treated as Williamson fluid. Per- turbation solutions have been evaluated for velocity, resistance impedance, wall shear stress and shearing stress at the stenosis throat. The graphical results of different type of tapered arteries （i.e. converging tapering, diverging tapering, non-tapered artery） have been examined for different parameters of interest.

关键词： Williamson fluid blood flow tapered artery stenosis perturbation solution.

Emerging Trends in Damage Tolerance Assessment:A Review of Smart Materials and Self-Repairable Structures

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Structural Durability & Health Monitoring 2024年第1期18卷 1-18页

作者： Ali akbar Firoozi Ali Asghar Firoozi Department of Civil Engineering Faculty of Engineering&TechnologyUniversity of BotswanaGaboroneUB0061Botswana Department of Civil Engineering University Kebangsaan Malaysia(UKM)Bangi43600Malaysia

The discipline of damage tolerance assessment has experienced significant advancements due to the emergence of smart materials and self-repairable *** review offers a comprehensive look into both traditional and innovative methodologies employed in damage tolerance *** a detailed exploration of damage tolerance concepts and their historical progression,the review juxtaposes the proven techniques of damage assessment with the cutting-edge innovations brought about by smart materials and self-repairable *** subsequent sections delve into the synergistic integration of smart materials with self-repairable structures,marking a pivotal stride in damage tolerance by establishing an autonomous system for immediate damage identification and *** holistic approach broadens the applicability of these technologies across diverse sectors yet brings forth unique challenges demanding further innovation and ***,the review examines future prospects that combine advanced manufacturing processes with data-centric methodologies,amplifying the capabilities of these‘intelligent’*** review culminates by highlighting the transformative potential of this union between smart materials and self-repairable structures,promoting a sustainable and efficient engineering paradigm.

关键词： Damage tolerance smart materials self-repairable structures structural health monitoring synergy autonomous system advanced manufacturing data-driven methodologies

Mathematical analysis of Phan-Thien-Tanner fluid model for blood in arteries

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International Journal of Biomathematics 2015年第5期8卷 215-230页

作者： Noreen Sher akbar S. Nadeem INational University of Sciences and Technology Islamabad Pakistan Department of Mathematics Quaid-i-Azam University45320 Islamabad 44000 Pakistan

In the present paper, we have studied the blood flow through tapered artery with a stenosis. The non-Newtonian nature of blood in small arteries is analyzed mathematically by considering the blood as Phan-Thien-Tanner fluid. The representation for the blood flow is through an axially non-symmetrical but radially symmetric stenosis. Symmetry of the distribution of the wall shearing stress and resistive impedance and their growth with the developing stenosis is another important feature of our analysis. Exact solutions have been evaluated for velocity, resistance impedance, wall shear stress and shearing stress at the stenosis throat. The graphical results of different type of tapered arteries （i.e. converging tapering, diverging tapering, non-tapered artery） have been examined for different narameters of interest.

关键词： Phan-Thien-Tanner fluid blood flow tapered artery stenosis exact solu-tions.

Bright, periodic, compacton and bell-shape soliton solutions of the extended QZK and (3+1)-dimensional ZK equations

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Communications in Theoretical Physics 2021年第10期73卷 23-35页

作者： M Ali akbar Md Abdul Kayum M S Osman Department of Applied Mathematics University of RajshahiBangladesh Department of Computer Science&Engineering North Bengal International UniversityRajshahiBangladesh Department of Mathematics Faculty of ScienceCairo UniversityGiza 12613Egypt

The(3+1)-dimensional Zakharov–Kuznetsov(ZK) and the new extended quantum ZK equations are functional to decipher the dense quantum plasma, ion-acoustic waves, electron thermal energy,ion plasma, quantum acoustic waves, and quantum Langmuir waves. The enhanced modified simple equation(EMSE) method is a substantial approach to determine competent solutions and in this article, we have constructed standard, illustrative, rich structured and further comprehensive soliton solutions via this method. The solutions are ascertained as the integration of exponential, hyperbolic,trigonometric and rational functions and formulate the bright solitons, periodic, compacton, bellshape, parabolic shape, singular periodic, plane shape and some new type of solitons. It is worth noting that the wave profile varies as the physical and subsidiary parameters change. The standard and advanced soliton solutions may be useful to assist in describing the physical phenomena previously mentioned. To open out the inward structure of the tangible incidents, we have portrayed the three-dimensional, contour plot, and two-dimensional graphs for different parametric values. The attained results demonstrate the EMSE technique for extracting soliton solutions to nonlinear evolution equations is efficient, compatible and reliable in nonlinear science and engineering.

关键词： (3+1)-dimensional ZK the extended QZK equation enhanced modified simple equation method soliton solutions NLEEs