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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

Cracks coalescence mechanism and cracks propagation paths in rock-like specimens containing pre-existing random cracks under compression

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Journal of Central South University 2014年第6期21卷 2404-2414页

作者： Hadi Haeri Kourosh Shahriar Mohammad Fatehi Marji parviz Moarefvand Department of Mining Engineering Science and Research BranchIslamic Azad University Department of Mining and Metallurgical Engineering Amirkabir University of Technology Mine Exploitation Engineering Department Faculty of Mining and MetallurgyInstitution of EngineeringYazd University

The mechanism of cracks propagation and cracks coalescence due to compressive loading of the brittle substances containing pre-existing cracks （flaws） was modeled experimentally using specially made rock-like specimens from Portland Pozzolana Cement （PPC）. The breakage process of the specimens was studied by inserting single and double flaws with different inclination angles at the center and applying uniaxial compressive stress at both ends of the specimen. The first crack was oriented at 50＆#176; from the horizontal direction and kept constant throughout the analysis while the orientation of the second crack was changed. It is experimentally observed that the wing cracks are produced at the first stage of loading and start their propagation toward the direction of uniaxial compressive loading. The secondary cracks may also be produced in form of quasi-coplanar and/or oblique cracks in a stable manner. The secondary cracks may eventually continue their propagation in the direction of maximum principle stress. These experimental works were also simulated numerically by a modified higher order displacement discontinuity method and the cracks propagation and cracks coalescence were studied based on Mode I and Mode II stress intensity factors （SIFs）. It is concluded that the wing cracks initiation stresses for the specimens change from 11.3 to 14.1 MPain the case of numerical simulations and from 7.3 to 13.8 MPa in the case of experimental works. It is observed that cracks coalescence stresses change from 21.8 to 25.3 MPa and from 19.5 to 21.8 MPa in the numerical and experimental analyses, respectively. Comparing some of the numerical and experimental results with those recently cited in the literature validates the results obtained by the proposed study. Finally, a numerical simulation was accomplished to study the effect of confining pressure on the crack propagation process, showing that the SIFs increase and the crack initiation angles change in this case.

关键词： crack propagation crack coalescence rock-like specimen numerical simulation experiment

Hydrodynamic Efficiency Improvement of the High Skew Propeller for the Underwater Vehicle Under Surface and Submerged Conditions

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Journal of Ocean University of China 2011年第4期10卷 314-324页

作者： Hassan Ghassemi parviz Ghadimi Department of Marine Technology Amirkabir University of Technology

An algorithm based on the Boundary Element Method(BEM)is presented for designing the High Skew Propeller(HSP)used in an Underwater Vehicle(UV).Since UVs operate under two different kinds of working conditions(*** and submerged conditions),the design of such a propeller is an unwieldy *** is mainly due to the fact that the resistance forces as well as the vessel efficiency under these conditions are significantly ***,some factors are necessary for the design of the opti-mum propeller to utilize the power under the mentioned *** design objectives of the optimum propeller are to obtain the highest possible thrust and efficiency with the minimum *** the current UV,the main dimensions of the propeller are pre-dicted based on the given required thrust and the defined operating *** dimensions(number of blades,pitch,diameter,expanded area ratio,thickness and camber)are determined through iterative *** the propeller operates at the stern of the UV where the inflow velocity to the propeller is non-uniform,a 5-blade HSP is preferred for running the ***,the propel-ler is designed based on the numerical calculations to acquire the improved hydrodynamic efficiency.

关键词： underwater vehicle propeller design factors high skew propeller surface and submerged conditions hydrodynamic propeller efficiency

Numerical Analysis of the High Skew Propeller of an Underwater Vehicle

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Journal of Marine Science and Application 2011年第3期10卷 289-299页

作者： Hassan Ghasseni parviz Ghadimi Department of Marine Technology Amirkabir University of Technology

A numerical analysis based on the boundary element method （BEM） was presented for the hydrodynamic performance of a high skew propeller （HSP） which is employed by an underwater vehicle （UV）. Since UVs operate at two different working conditions （surface and submerged conditions）, the design of such a propeller is a cumbersome task. This is primarily due to the fact that the resistance forces as well as the vessel efficiency under these conditions are significantly different. Therefbre, some factors are necessary for the design of the optimum propeller to utilize the power at the mentioned conditions. The design objectives of the optimum propeller are to obtain the highest possible thrust, minimum torque, and efficiency. In the current study, a 5-bladed HSP was chosen for running the UV. This propeller operated at the stern of the UV hull where the inflow velocity to the propeller was non-uniform. Some parameters of the propeller were predicted based on the UV geometrical hull and operating conditions. The computed results include the pressure distribution and the hydrodynamic characteristics of the HSP in open water conditions, and comparison of these results with those of the experimental data indicates good agreement. The propeller efficiency for both submerged and surface conditions was found to be 67% and 64%, respectively, which compared to conventional propellers is a significantly higher efficiency.

关键词： boundary element method (BEM) hydrodynamic analysis high skew propeller surface andsubmerged conditions

Application of graphite screen printed electrode modified with dysprosium tungstate nanoparticles in voltammetric determination of epinephrine in the presence of acetylcholine

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Journal of Rare Earths 2018年第7期36卷 750-757页

作者： Hadi Beitollahi Zahra Dourandish Somayeh Tajik Mohammad Reza Ganjali parviz Norouzi Farnoush Faridbod Environment Department Irtstitute of Science and High Technology and Environmental SciencesGraduate University of Advanced Technology Department of Chemistry Graduate University of Advanced Technology NanoBioElectrochemistry Research Center Bam University of Medical Scicnce Center of Excellence in Electrochemistry Faculty of ChemistryUniversity of Tehran Biosensor Research Center Endocrinology & Metabolism Molecular-Cellular Sciences InstituteTehran University of Medical Sciences

The current work focuses on the development of a sensitive and selective electrochemical device based on a graphite screen printed electrode modified with Dy2（WO4）3 nanoparticles（DWO/SPE） for the analysis of epinephrine in samples also containing acetylcholine. The study proves that the sensor has excellent electron-mediating behavior in the oxidation of epinephrine in a 0.1 mol/L phosphate buffer solution（PBS）（pH 7.0）. The application of the DWO/SPE in differential pulse voltammetry（DPV） is found to lead to distinct response for the oxidation of epinephrine and acetylcholine, with the potentials of the epinephrine and acetylcholine peaks（△Ep） to be 550 mV apart. The detection limits of the method for epinephrine and acetylcholine are 0.5 and 0.7 μmol/L（S/N = 3） and the responses are found to be linear in the concentration ranges of 1.0-900.0 μmol/L and 1.0-1200.0 μmol/L in a PBS buffer（pH = 7.0）respectively. The modified electrode was used for the detection of epinephrine and acetylcholine in real samples and found to produce satisfactory results. These results can be a proof that Dy2（WO4）3 nanoparticles can find promising applications in electrochemical sensors to be used for the analysis of（bio）chemical species.

关键词： Epinephrine Acetylcholine Dy2(WO4)3 nanoparticles Graphite screen printed electrode Rare earths

Synthesis, Characterization and Ion Exchange Properties of a New Composite of Inorganic Ion Exchanger： Polyacrylonitrile Cerium（IV） Molybdophosphate

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Chinese Journal of Chemistry 2012年第1期30卷 177-182页

作者： Ahmadi,Seyed Javad Yavari,Ramin Ashtari,parviz' Gholipour,Vanik Kamel,Leila Rakhshandehru,Farokh Waste Management Department Nuclear Science and Technology Research InstituteP.O.Box 11365/8486TehranIran Faculty of Chemistry Tarbiat Moallem UniversityP.C.TehranIran

In this work, the synthesis of the composite of cerium（IV） molybdophosphate （CMP） and polyacrylonitrile （PAN） was reported （CMP-PAN）. The material has been characterized by elemental and spectral （FT-IR）, X-ray and thermal （TGA） analysis. Also the size analysis of the composite was done by scanning electron microscopy （SEM）. Its chemical stability in acidic, basic and saline solutions and radiation stability up to 100 kGy total expose dose were assessed. Whereas the synthesized composite has ion exchange properties, its ion exchange capacity and behavior toward several metal ions were also investigated. Further, the distribution coefficients of the metal ions were calculated. Finally, the ability of the synthesized CMP-PAN composite for the decontamination of low level liquid waste （LLLW） was investigated.

关键词： composite ion-exchange cerium(IV) molybdophosphate

Inverse Stone-Thrower-Wales defect and transport properties of 9AGNR double-gate graphene nanoribbon FETs

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Journal of Central South University 2019年第11期26卷 2943-2952页

作者： Mohammad Bagher NASROLLAHNEJAD parviz KESHAVARZI Electrical and Computer Engineering Department Semnan University

Defect-based engineering of carbon nanostructures is becoming an important and powerful method to modify the electron transport properties in graphene nanoribbon FETs. In this paper, the impact of the position and symmetry of the ISTW defect on the performance of low dimensional 9AGNR double-gate graphene nanoribbon FET (DG-GNRFET) is investigated. Analyzing the transmission spectra, density of states and current-voltage characteristics shows that the defect effect on the electron transport is considerably varied depending on the positions and the orientations (the symmetric and asymmetric configuration) of the ISTW defect in the channel length. Based on the results, the asymmetric ISTW defect leads to a more controllability of the gate voltages over drain current, and drain current increases more than 5 times. The results have also con rmed the ISTW defect engineering potential on controlling the channel electrical current of DG-AGNR FET.

关键词： inverse Stone-Thrower-Wales defect electronic transport properties graphene nanoribbon tight binding NEGF formalism

The Relationship between Fe Mineralization and Magnetic Basement Faults using Multifractal Modeling in the Esfordi and Behabad Areas(BMD), Central Iran

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Acta Geologica Sinica(English Edition) 2022年第2期96卷 591-606页

作者： Masoumeh NABILOU Peyman AFZAL Mehran ARIAN Ahmad ADIB Hassan KHEYROLLAHI Mohammad FOUDAZI parviz ANSARIRAD Department of Earth Sciences Science and Research BranchIslamic Azad UniversityTehranIran Department of Petroleum and Mining Engineering South Tehran BranchIslamic Azad UniversityTehranIran Division of Airborne Geophysics Explorartion DepartmentGeological Survey of IranTehranIran Department of Geology Eslamshar BranchIslamic Azad UniversityTehranIran Farhangian University TehranIran

Multifractal modeling is a mathematical method for the separation of a high potential mineralized background from a non-mineralized background. The Concentration-Distance to Fault structures(C-DF) fractal model and the distribution of the known iron(Fe) deposits/mines seen in the Esfordi and Behabad 1:100,000 sheets from the Bafq region of central Iran are used to distinguish Fe mineralization based on their distance to magnetic basement structures and surface faults, separately, using airborne geophysical data and field surveys. Application of the C-DF fractal model for the classification of Fe mineralizations in the Esfordi and Behabad areas reveals that the main ones show a correlation with their distance from magnetic basement structures. Accordingly, the distances of Fe mineralizations with grades of Fe higher than 55%(43% < Fe ≤ 60%) are located at a distance of less than 1 km, whereas for surfacial faults with grades of 43% ≤ Fe ≤ 60%, the distances are 3162< DF ≤ 4365 m from the faults. Thus, there is a positive relationship between Fe mineralization and magnetic basement structures. Also, the proximity evidence of Precambrian high-grade Fe mineralization related to magnetic basement structures indicates syn-rifting tectonic events. Finally, this C-DF fractal model can be used for exploration of magmatic and hydrothermal ore deposits.

关键词： Fe mineralization prospecting Concentration-Distance to Fault model(C-DF) fractals Bafq Iran

Comparative evaluation of impacts of climate change and droughts on river flow vulnerability in Iran

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Water Science and Engineering 2020年第4期13卷 265-274页

作者： Zahra Noorisameleh Shahriar Khaledi Alireza Shakiba parviz Zeaiean Firouzabadi William AGough MMonirul Qader Mirza Faculty of Earth Sciences Shahid Beheshti UniversityTehran ***Iran Department of Physical and Environmental Sciences University of Toronto ScarboroughToronto M1C 1A4Canada Faculty of Geographical Sciences Kharazmi UniversityTehran 15719-14911Iran

Rivers in arid and semi-arid regions are threatened by droughts and climate *** study focused on a comparative evaluation of the impacts of climate change and droughts on the vulnerability of river flows in three basins with diverse climates in *** standardized precipitation-evapotranspiration index(SPEI)and precipitation effectiveness variables(PEVs)extracted from the conjunctive precipitation effectiveness index(CPEI)were used to analyze the drought *** investigate hydrological droughts in the basins,the normalized difference water index(NDWI)and the streamflow drought index(SDI)were calculated and *** effects of droughts were assessed under various representative concentration pathway(RCP)*** in the number of wet days and precipitation depth restricted hydrological droughts,whereas an increasing number of dry days amplified their *** projected increases in dry days and precipitation over short durations throughout a year under future climate scenarios would produce changes in drought and flood periods and ultimately impact the frequency and severity of hydrological *** RCP 4.5,an increase in the frequencies of moderate and severe meteorological/hydrological droughts would further affect the Central Desert *** RCPs 2.6 and 8.5,the frequencies of severe and extreme droughts would increase,but the drought area would be smaller than that under RCP 4.5,demonstrating less severe drought *** to the shallow depths of most rivers,SDI was found to be more feasible than NDWI in detecting hydrological droughts.©2020 Hohai *** and hosting by Elsevier *** is an open access article under the CC BY-NC-ND license(http://***/licenses/by-nc-nd/4.0/).

关键词： Climate change River flow Precipitation Drought index Standardized precipitation-evapotranspiration index Iran