Numerical Simulation of Vortex Induced Vibration of A Flexible Cylinder

Mojtaba Hosseini,Hamid reza Ashrafi,Peyman Beiranvand,Ahmad Dehestani,Kiuomars Dehestani 한국유체기계학회 2017 International journal of fluid machinery and syste Vol.10 No.4

Numerical simulations of vortex-induced vibration of a three-dimensional flexible Cylinder under uniform turbulent flow are calculated when Reynolds number is 1.35×104. In order to achieve the vortex-induced vibration, the three-dimensional unsteady, viscous, incompressible Navier-Stokes equation and LES turbulence model are solved with the finite volume approach, the Cylinder is discretized according to the finite element theory, and its dynamic equilibrium equations are solved by the Newmark method. The fluid-Cylinder interaction is realized by utilizing the diffusion-based smooth dynamic mesh method. Considering VIV system, the variety trends of lift coefficient, drag coefficient, displacement, vertex shedding frequency, phase difference angle of Cylinder are analyzed under different frequency ratios. The nonlinear phenomena of locked-in, phase-switch are captured successfully. Meanwhile, the limit cycle and bifurcation of lift coefficient and displacement are analyzed using trajectory, phase portrait and Poincare sections. The results reveal that: when drag coefficient reaches its minimum value, the transverse amplitude reaches its maximum and the “lock-in” begins simultaneously. In the range of “lock-in”, amplitude decreases gradually with increasing of frequency ratio. When lift coefficient reaches its minimum value, the phase difference, between lift coefficient and lateral displacement, undergoes a suddenly change from the “out-of-phase” to the “in-phase” mode. There is no bifurcation of lift coefficient and lateral displacement occurred in three dimensional flexible Cylinder submitted to uniform turbulent flow.

Asymptotic Stability of Time Delay Systems With Unknown Uncertainty Bounds Using Adaptive Robust Control

Mojtaba Hosseini Toodeshki,Javad Askari,Saeed Hosseinnia 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8

The problem of adaptive robust control of un-certain linear systems with multiple time delays in the state variables is considered in this paper. The essential requirement for the parameter un-certainties is that they satisfy some matching con-ditions and are norm bounded, whose bounds are unknown. The objective is to design an adap-tive robust controller based on a new Lyapunov Krasov skii functional such that the closed loop system is a symptotically stable. The proposed de-sign condition is formulated interms of linear ma-trix in equality(LMI) which can be easily solved by LMI Tool box in Mat lab. Finally, a numerical example is included to illustrate the effectiveness of the derived controller.

Numerical Simulation of Vortex Induced Vibration of A Flexible Cylinder

Hosseini, Mojtaba,Ashrafi, Hamid reza,Beiranvand, Peyman,Dehestani, Ahmad,Dehestani, Kiuomars Korean Society for Fluid machinery 2017 International journal of fluid machinery and syste Vol.10 No.4

Numerical simulations of vortex-induced vibration of a three-dimensional flexible Cylinder under uniform turbulent flow are calculated when Reynolds number is $1.35{\times}104$. In order to achieve the vortex-induced vibration, the three-dimensional unsteady, viscous, incompressible Navier-Stokes equation and LES turbulence model are solved with the finite volume approach, the Cylinder is discretized according to the finite element theory, and its dynamic equilibrium equations are solved by the Newmark method. The fluid-Cylinder interaction is realized by utilizing the diffusion-based smooth dynamic mesh method. Considering VIV system, the variety trends of lift coefficient, drag coefficient, displacement, vertex shedding frequency, phase difference angle of Cylinder are analyzed under different frequency ratios. The nonlinear phenomena of locked-in, phase-switch are captured successfully. Meanwhile, the limit cycle and bifurcation of lift coefficient and displacement are analyzed using trajectory, phase portrait and Poincare sections. The results reveal that: when drag coefficient reaches its minimum value, the transverse amplitude reaches its maximum and the "lock-in" begins simultaneously. In the range of "lock-in", amplitude decreases gradually with increasing of frequency ratio. When lift coefficient reaches its minimum value, the phase difference, between lift coefficient and lateral displacement, undergoes a suddenly change from the "out-of-phase" to the "in-phase" mode. There is no bifurcation of lift coefficient and lateral displacement occurred in three dimensional flexible Cylinder submitted to uniform turbulent flow.

Genetic diversity of Iranian wild barley (Hordeum spontaneum Koch.) populations

Hosseini Mojtaba,Yassaie Mohsen,Rashed-Mohassel Mohammad Hassan,Ghorbani Reza,Niazi Ali 한국작물학회 2022 Journal of crop science and biotechnology Vol.25 No.3

An efective weed management program requires a comprehensive knowledge of a weed’s genetic diversity. Wild barley (Hordeum spontaneum Koch) is known as an invasive weed that is rising in commercial cereal felds of Iran. Genetic diversity of 31 populations of Iranian wild barley consisting of 27 populations from Fars province along with four collected from Alborz, Kermanshah, Khuzestan, and Lorestan provinces was investigated using 15 ISSR markers. Cluster analysis showed that populations were divided into six main groups based on 88.5% similarity level. According to PCoA results, seven groups were determined based on populations’ data. The maximum similarity is recorded between Fasa and Darab populations (95.6%) and the minimum was noted between Sepidan and Mohr (78.6%). Genetic variation within the investigated wild barley populations (53%) was higher than between populations (47%). Results of Mantel test revealed a correlation between population distance and latitude, rainfall, annual temperature, and population geographic distances. Generally, latitudes, annual mean temperature, and annual mean rainfall are infuenced by genetic diversity of wild barley in Iran.

Adaptive Robust Control of Uncertain Systems with State and Input Delay

Mojtaba Hosseini Toodeshki,Javad Askari,Saeed Hosseinnia 제어·로봇·시스템학회 2010 International Journal of Control, Automation, and Vol.8 No.6

In this paper, adaptive robust control of uncertain systems with multiple time delays in states and input is considered. It is assumed that the parameter uncertainties are time varying norm-bounded whose bounds are unknown but their functional properties are known. To overcome the effect of input delay on the closed loop system stability, new Lyapunov Krasovskii functional will be introduced. It is shown that the proposed adaptive robust controller guarantees globally uniformly exponentially convergence of all system solutions to a ball with any certain convergence rate. Moreover, if there is no disturbance in the system, asymptotic stability of the closed loop system will be established. The proposed design condition is formulated in terms of linear matrix inequality (LMI) which can be easily solved by LMI Toolbox in Matlab. Finally, an illustrative example is included to show the effec-tiveness of results developed in this paper.

Comparison of the effect of laminar and turbulent flow regimes on thermal stresses and strains in an annular fin

Mojtaba Hosseini,Ali Hatami,Samira Payan 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.1

We compared the effect of laminar and turbulent flow regimes on thermal stresses and strains in an annular fin. This comparison showed that substituting the laminar flow regime with the turbulent flow regime increases the magnitude of effective stresses and strains but does not change their position. In both regimes, tangential stress was asymmetrical and reached its highest magnitude in the flow front and in the fin base. In both regimes, the fin exhibited a two-dimensional temperature distribution, which causes asymmetric thermal strains, and hence, significant asymmetric thermal stress on the fin. An analysis of the flow surrounding the fin showed that the radial temperature variations do not provide sufficient information for identifying critical regions in terms of radial and tangential stress and thus effective stress. Overall, the results underscore the importance of the analysis of the flow around annular fins for the analysis of their thermal stresses.

Adaptive Robust H∞ Control of Time Delay Systems with Unknown Uncertainty Bounds

Mojtaba Hosseini Toodeshki,Javad Askari,Saeed Hosseinnia 제어·로봇·시스템학회 2012 International Journal of Control, Automation, and Vol.10 No.1

The problem of adaptive robust H∞ control for uncertain systems with multiple delays is considered in this paper. The essential requirement for the uncertainties is that they satisfy matching conditions and are norm-bounded, but the bounds are not necessarily known. The objective is to design adaptive robust H∞ state-feedback controller such that the resulting closed-loop system is asymptotically stable and a prescribed H∞ performance level of the closed loop system for disturbance attenuation is guaranteed. To solve this problem, a new sufficient condition is presented in terms of a linear matrix inequality (LMI). The effectiveness of proposed method is verified by its application to an unstable system.

Di-ANFIS: an integrated blockchain–IoT–big data-enabled framework for evaluating service supply chain performance

Seyed Mojtaba Hosseini Bamakan,Najmeh Faregh,Ahad ZareRavasan 한국CDE학회 2021 Journal of computational design and engineering Vol.8 No.2

Service supply chain management is a complex process because of its intangibility, high diversity of services, trustless settings, and uncertain conditions. However, the traditional evaluating models mostly consider the historical performance data and fail to predict and diagnose the problems’ root. This paper proposes a distributed, trustworthy, tamper-proof, and learning framework for evaluating service supply chain performance based on blockchain and adaptive network-based fuzzy inference systems (ANFIS) techniques, named Di-ANFIS. The main objectives of this research are as follows: (1) presenting hierarchical criteria of service supply chain performance to cope with the diagnosis of the problems’ root; (2) proposing a smart learning model to deal with the uncertainty conditions by a combination of neural network and fuzzy logic; and (3) introducing a distributed blockchain-based framework due to the dependence of ANFIS on big data and the lack of trust and security in the supply chain. Furthermore, the proposed six-layer conceptual framework consists of the data layer, connection layer, blockchain layer, smart layer, ANFIS layer, and application layer. This architecture creates a performance management system using the Internet of Things, smart contracts, and ANFIS based on the blockchain platform. The Di-ANFIS model provides a performance evaluation system without needing a third party and a reliable intermediary that provides an agile and diagnostic model in a smart and learning process. It also saves computing time and speeds up information flow.

Transplantation of Neural Stem Cells Cultured in Alginate Scaffold for Spinal Cord Injury in Rats

Seyed Mojtaba Hosseini,Ali Sharafkhah,Omid Koohi-Hosseinabadi,Maryam Semsar-Kazerooni 대한척추외과학회 2016 Asian Spine Journal Vol.10 No.4

Study Design: This study investigated the effects of transplantation of alginate encapsulated neural stem cells (NSCs) on spinal cord injury in Sprague-Dawley male rats. The neurological functions were assessed for 6 weeks after transplantation along with a histological study and measurement of caspase-3 levels. Purpose: The aim of this study was to discover whether NSCs cultured in alginate transplantation improve recovery from spinal cord injury. Overview of Literature: Spinal cord injury is one of the leading causes of disability and it has no effective treatment. Spinal cord injury can also cause sensory impairment. With an impetus on using stem cells therapy in various central nervous system settings, there is an interest in using stem cells for addressing spinal cord injury. Neural stem cell is one type of stem cells that is able to differentiate to all three neural lineages and it shows promise in spinal injury treatment. Furthermore, a number of studies have shown that culturing NSCs in three-dimensional (3D) scaffolds like alginate could enhance neural differentiation. Methods: The NSCs were isolated from 14-day-old rat embryos. The isolated NSCs were cultured in growth media containing basic fibroblast growth factor and endothelial growth factor. The cells were characterized by differentiating to three neural lineages and they were cultured in an alginate scaffold. After 7 days the cells were encapsulated and transplanted in a rat model of spinal cord injury. Results: Our data showed that culturing in an alginate 3D scaffold and transplantation of the NSCs could improve neurological outcome in a rat model of spinal cord injury. The inflammation scores and lesion sizes and also the activity of caspase-3 (for apoptosis evaluation) were less in encapsulated neural stem cell transplantation cases. Conclusions: Transplantation of NSCs that were cultured in an alginate scaffold led to a better clinical and histological outcome for recovery from spinal cord injury in a rat model.

Fabrication of novel polyethersulfone based nanofiltration membrane by embedding polyaniline-co-graphene oxide nanoplates

Mojtaba Moochani,Abdolreza Moghadassi,Sayed Mohsen Hosseini,Ehsan Bagheripour,Fahime Parvizian 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.9

Mixed matrix polyethersulfone (PES) based nanofiltration membrane was prepared through phase inversion method by using of polyvinylpyrrolidone (PVP) as pore former and N, N dimethylacetamide (DMAc) as solvent. Polyaniline-co-graphene oxide nanoplates (PANI/GO) were utilized as additive in membrane fabrication. The PANI/ GO nanoplates were prepared by polymerization of aniline in the presence of graphene oxide nanoplates. FTIR analysis, scanning electron microscopy (SEM), scanning optical microscopy (SOM), 3D images surface analysis, water contact angle, water content tests, tensile strength tests, porosity tests, salt rejection and flux tests were used in membrane characterization. FT-IR results verified formation of PANI on graphene oxide nanoplates. SOM images showed uniform particles distribution for the mixed matrix membranes. SEM images also showed formation of wide pores for the modified membranes. Water flux showed constant trend nearly by use of PANI/GO in the casting solution. Opposite trend was found for the membrane surface hydrophilicity. Salt rejection was enhanced sharply by utilizing of PANI/ GO. The membrane’s tensile strength was improved by increase of PANI/GO concentration. The water content was increased initially by use of PANI/GO nanoplates up to 0.05%wt into the casting solution and then decreased. Membrane porosity was also enhanced by using of PANI/GO nanoplates. Modified membrane containing 0.5%wt PANI/ GO nanoplates showed more appropriate antifouling characteristic compared to others.