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Mohammad Abbaspour Niasani,Rahmatollah Ghajar,Hamed Saeidi Googarchin,Seyed Mohammad Hossein Sharifi 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.4
Circumferential crack growth pattern in a thin-walled cylinder is studied. Thermo-elastic stresses in a cylinder subjected to thermomechanical loads are extracted. Closed form thermo-elastic stress intensity factor for cracked cylinder are derived using weight function method. An algorithm is developed to simulate different crack growth patterns utilizing a very high efficiency weight function method. This would lessen the taken time for the analyses compared to other numerical methods such as FEM. Results show that while the load effect on cylinder subjected to thermal load lead to the crack growth in small aspect ratio, in cylinder subjected to mechanical loads, it would lead to the growth of crack in large aspect ratio. The results show that, apart from load effects, the cylinders containing initial semi-circular crack have the longest life among the cylinders containing initial semi-elliptical crack with the same initial depth.
Buckling treatment of piezoelectric functionally graded graphene platelets micro plates
Fatemeh Abbaspour,Hadi Arvin 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.38 No.3
Micro-electro-mechanical systems (MEMS) are widely employed in sensors, biomedical devices, optic sectors, and micro-accelerometers. New reinforcement materials such as carbon nanotubes as well as graphene platelets provide stiffer structures with controllable mechanical specifications by changing the graphene platelet features. This paper deals with buckling analyses of functionally graded graphene platelets micro plates with two piezoelectric layers subjected to external applied voltage. Governing equations are based on Kirchhoff plate theory assumptions beside the modified couple stress theory to incorporate the micro scale influences. A uniform temperature change and external electric field are regarded along the micro plate thickness. Moreover, an external in-plane mechanical load is uniformly distributed along the micro plate edges. The Hamilton’s principle is employed to extract the governing equations. The material properties of each composite layer reinforced with graphene platelets of the considered micro plate are evaluated by the Halpin–Tsai micromechanical model. The governing equations are solved by the Navier’s approach for the case of simply-supported boundary condition. The effects of the external applied voltage, the material length scale parameter, the thickness of the piezoelectric layers, the side, the length and the weight fraction of the graphene platelets as well as the graphene platelets distribution pattern on the critical buckling temperature change and on the critical buckling in-plane load are investigated. The outcomes illustrate the reduction of the thermal buckling strength independent of the graphene platelets distribution pattern while meanwhile the mechanical buckling strength is promoted. Furthermore, a negative voltage, -50 Volt, strengthens the micro plate stability against the thermal buckling occurrence about 9% while a positive voltage, 50 Volt, decreases the critical buckling load about 9% independent of the graphene platelet distribution pattern.
Numerical Investigation of Turbulent Open Channel Flow with Semi-cylindrical Rough Beds
Akram Abbaspour,Saeed Hashemi Kia 대한토목학회 2014 KSCE Journal of Civil Engineering Vol.18 No.7
Flow development in an open-channel with rough beds was investigated using FLUENT, a commercial Computational Fluid Dynamics (CFD) software. The Renormalization Group (RNG) k-ε turbulence model was used for subcritical flow cases. The Volume of Fluid (VOF) method was used to allow the free-surface to deform freely with the underlying turbulence. The main purpose of this study was to examine the effects of the different types of surface roughness on a turbulent boundary layer in a relatively high Reynolds flow. The determination of velocity profile in turbulent open channels with rough bed is a difficult task due to the significant effects of the roughness. The velocity distributions in the log-region for the rough wall were determined. The roughness function ∆U + , the characteristic downward shift of the logarithmic part of the mean velocity profile, was found to be more than 12 for three rough surfaces the roughness function, ∆U + scales logarithmically with normalized effective height y+.
INVERTIBILITY OF GENERALIZED BESSEL MULTIPLIERS IN HILBERT C<sup>∗</sup>-MODULES
Tabadkan, Gholamreza Abbaspour,Hosseinnezhad, Hessam Korean Mathematical Society 2021 대한수학회보 Vol.58 No.2
This paper includes a general version of Bessel multipliers in Hilbert C∗-modules. In fact, by combining analysis, an operator on the standard Hilbert C∗-module and synthesis, we reach so-called generalized Bessel multipliers. Because of their importance for applications, we are interested to determine cases when generalized multipliers are invertible. We investigate some necessary or sufficient conditions for the invertibility of such operators and also we look at which perturbation of parameters preserve the invertibility of them. Subsequently, our attention is on how to express the inverse of an invertible generalized frame multiplier as a multiplier. In fact, we show that for all frames, the inverse of any invertible frame multiplier with an invertible symbol can always be represented as a multiplier with an invertible symbol and appropriate dual frames of the given ones.
Developing an Architecture for the Intelligent Tour Planning System
Rahim. A. Abbaspour,Farhad Samadzadegan 세계문화관광학회 2008 Conference Proceedings Vol.9 No.0
Current mobile tourist guide systems provide its users with relevant information about interesting points. They also offer several functions to analyze data which are in internal geodatabase according to the context elements. Despite these facilities, they suffer from some limitations such as limitations in analysis and management of context information. In this paper, we propose an extension to the first generation of these systems to upgrade them towards the second generation.
A method for similarity measurement in spatial trajectories
Rahim Ali Abbaspour,Mohammad Shaeri,Alireza Chehreghan 대한공간정보학회 2017 Spatial Information Research Vol.25 No.3
Owing to increasing number of moving objects and positioning technologies both indoors and outdoors, spatial databases have encountered immense amount of spatio-temporal data. This causes spatial analyses of trajectories to be one of the most interesting topics in GIS research recently. Finding similar trajectories are of high importance to utilize these analyses. Distance functions play the key role in similarity measurement to find similar trajectories. Thus far, various distance functions have been proposed, but they show some drawbacks for spatial trajectories due to their nature. In this paper, a novel method is proposed considering spatio-temporal behaviors of spatial trajectories. In first step, polyline with minimum number of line segments representing trajectory in correspondent space with acceptable similarity is fitted. Then, the comparisons of trajectories are based on fitted polylines. Robustness of trajectories similarity to noise and sampling rate is proven with 96% according to evaluations.
Seyed Foad Abbaspour,Mojtaba Kanvisi 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.122 No.-
In this paper, to improve the thermal conductivity of polymer composites, the epoxy matrix has beenfilled with single graphene nanoplatelets (SGNPs) modified by Fe3O4 magnetic nanoparticles. Fe3O4modified graphene nanoplatelets were aligned by the magnetic field tunnel method in the epoxy matrix. The highest alignment and controlled orientation of the nanoplatelets were achieved in different compositesamples. FT-IR and TEM tests were used to investigate the structure and characterization ofSGNP@Fe3O4 synthesized nanoparticles. A constant intensity magnetic field at different times was usedto control the nanoplatelets’ orientation in the epoxy matrix. This controlled orientation and high alignmentof the fillers lead to an increase in the thermal conductivity of the composite. The thermal conductivityof the EP/SGNP @Fe3O4 composite showed a 309% increase in high alignment compared to the nonalignedsamples.
Mahdavia, Iraj,Abbaspour-Ghomi, Hassanjan,Sahebjamnia, Navid,Eissazadeh-Roshan, Yousof,Fazlollahtabar, Hamed,Mahdavi-Amiri, Nezam,Hamzehpour, Amin The Society of Digital Policy and Management 2009 디지털융복합연구 Vol.7 No.1
The rapid growth of information and communication technologies prompted the need for developing the strategic implementation framework of IT/ICT programs in universities. Here, we propose a strategic framework for the development of the IT/ICT programs in the universities of the province of Mazandaran in Iran. We use the SWOT analysis to assist the formulation of the strategy, where the Analytic Hierarchy Process (AHP) is applied to weigh the SWOT factors and the fuzzy TOPSIS is used to evaluate the strategic plans. Based on Iran and Mazandaran Digital Indices (DI) and considering the SWOT matrix, four strategies are identified. Finally, an analytical concept, namely the strategy shooting, is considered to show the role of SWOT factors and strategic plans on the performance of the system.
Khalil Alipour,Adel Abbaspour 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.1
Formation control is a potential advanced technology for aircrafts, spacecrafts and space robots. This paper, for the first time, studies several methods of passive and semi-active Remote Center Compliance (RCC) in order to examine their effects on formation control of a group of Wheeled Mobile Robots (WMRs) for object manipulation during space/terrestrial explorations. To this end, first, the dynamics model of the constrained nonholonomic robots, object and RCC system have been derived precisely. A leader-follower control strategy is then utilized for trajectory tracking of the desired path by the cooperative robots. Finally, the passive and semi active RCC are optimized to make the formation robust in the presence of significant disturbances. The results obtained reveal that the semi-active RCC system, combined with a PID controller, reduces the effect of the disturbances experienced as compared to the other passive RCC modules.