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Analytical approach for calculating the sheet output curvature in asymmetrical rolling: In the case of roll axis displacement as a new asymmetry factor
, Article International Journal of Mechanical Sciences ; Volume 105 , 2016 , Pages 11-22 ; 00207403 (ISSN) ; Assempour, A ; Afrasiab, H ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
In this paper, a less studied factor in the asymmetrical rolling process of sheets, namely the rolls horizontal displacement, is investigated using an analytical approach based on the slab method analysis. The presented method is capable of computing the force and torque of the process under different asymmetrical factors such as the rolls horizontal displacement, the interface friction inequality, and the rolls speed mismatch. A formula is presented to predict the outgoing sheet curvature induced by the rolls horizontal displacement. The results can be potentially used in producing curved sheets of various shapes by the asymmetrical rolling process. The analytical model is compared with a...
Image acquisition for trolling-mode atomic force microscopy based on dynamical equations of motion
, Article Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science ; 2020 ; Nejat Pishkenari, H ; Vossoughi, G ; Sharif University of Technology
SAGE Publications Ltd
2020
Abstract
Trolling mode atomic force microscopy (TR-AFM) can considerably reduce the liquid-resonator interaction forces, and hence, has overcome many imaging problems in liquid environments. This mode increases the quality factor (QF) significantly compared with the conventional AFM operation in liquid; therefore, the duration to reach the steady-state periodic motion of the oscillating probe is relatively high. As a result, utilizing conventional imaging techniques, which are based on measuring the amplitude and phase, are significantly slower when compared to our proposed method. This research presents a high-speed scanning technique based on an estimation law to obtain the topography of various...
Analytical Approach for Calculating the sheet Output Curvature in Asymmetrical Cold Rolling: In the Case of Roll Axis Displacement as a new Asymmetry Factor
, M.Sc. Thesis Sharif University of Technology ; Asempour, Ahmad (Supervisor)
Abstract
In the rolling process some parameters may cause the rolling process to be asymmetric, the most important of this parameters are unequal radii, friction and rotational speed of upper and lower rolls. The mentioned asymmetry factors change the symmetric rolling process to the new process called asymmetrical rolling process. Asymmerical roling process that caused from various asymmetry factor have been studeid for many years by various researchers from different directions with different methods.Among the most important of which was raised by many researchers, slab method was the most accuracy and acceptable method. Using the slab method researchers were able to calculate the force, torque and...
Designing nonlinear observer for topography estimation in trolling mode atomic force microscopy
, Article JVC/Journal of Vibration and Control ; Volume 28, Issue 23-24 , 2022 , Pages 3890-3905 ; 10775463 (ISSN) ; Chahari, M ; Pishkenari, H. N ; Vossoughi, G ; Sharif University of Technology
SAGE Publications Inc
2022
Abstract
In this study, a nonlinear observer for high-speed estimation of the sample surface topography in a small duration of the probe transient motion utilizing a 2DOF model of TR-AFM is proposed. Since the time duration to reach the steady-state periodic motion of the oscillating probe in conventional imaging methods is relatively high, the proposed nonlinear observer in this research is able to address this limitation and estimate the surface topography throughout transient oscillation of the microcantilever. With this aim, topography estimation process utilizing a Thau observer without any linearization of the system dynamics is designed and coupled with the system dynamics to achieve sample...
Imaging performance of trolling mode atomic force microscopy: investigation of effective parameters
, Article Archive of Applied Mechanics ; Volume 92, Issue 5 , 2022 , Pages 1551-1570 ; 09391533 (ISSN) ; Chahari, M ; Nejat Pishkenari, H ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2022
Abstract
In this study, we investigate the limitations and influence of various factors on the performance of trolling mode atomic force microscopy (TR-AFM). For this purpose, at first, based on the governing equations of motion and using a conventional control method, a simulation tool capable of correctly simulating the imaging procedure in TR-AFM is developed. Then based on the developed simulation tool, imaging of different surfaces is performed, and the effect of different factors on the image quality is analyzed. The flexibility of nanoneedle in TR-AFM has unpredictable effects on dynamics of system as well as imaging performance. One problem in imaging is due to coexistence of two stable...
Numerical Analysis of Dynamic Behavior of Pile Foundations in Non-homogeneous Liquefiable Soils
, M.Sc. Thesis Sharif University of Technology ; Pak, Ali (Supervisor)
Abstract
The behavior of pile foundations during earthquakes is one of the most important factors that affect the performance of structures. Therefore, a large number of studies have been performed on the behavior of pile foundations under dynamic loading. A lot of procedures for the analysis and design of piles under earthquake loading have been developed, especially after the earthquakes which took place in 1964 in Niigata and Alaska. They introduced two major mechanisms for the failure of pile foundations in liquefiable grounds: Bending mechanism and buckling mechanism.In this research the focus is the evaluation of pile failure under buckling mechanism. A fully coupled three-dimensional dynamic...
Simulating dynamic plastic continuous neural networks by finite elements
, Article IEEE Transactions on Neural Networks and Learning Systems ; Volume 25, Issue 8 , August , 2014 , Pages 1583-1587 ; ISSN: 2162237X ; Torghabehi, O. O ; Sharif University of Technology
Abstract
We introduce dynamic plastic continuous neural network (DPCNN), which is comprised of neurons distributed in a nonlinear plastic medium where wire-like connections of neural networks are replaced with the continuous medium. We use finite element method to model the dynamic phenomenon of information processing within the DPCNNs. During the training, instead of weights, the properties of the continuous material at its different locations and some properties of neurons are modified. Input and output can be vectors and/or continuous functions over lines and/or areas. Delay and feedback from neurons to themselves and from outputs occur in the DPCNNs. We model a simple form of the DPCNN where the...
Image acquisition for trolling-mode atomic force microscopy based on dynamical equations of motion
, Article Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science ; Volume 235, Issue 18 , 2021 , Pages 3654-3677 ; 09544062 (ISSN) ; Pishkenari, H. N ; Vossoughi, G ; Sharif University of Technology
SAGE Publications Ltd
2021
Abstract
Trolling mode atomic force microscopy (TR-AFM) can considerably reduce the liquid-resonator interaction forces, and hence, has overcome many imaging problems in liquid environments. This mode increases the quality factor (QF) significantly compared with the conventional AFM operation in liquid; therefore, the duration to reach the steady-state periodic motion of the oscillating probe is relatively high. As a result, utilizing conventional imaging techniques, which are based on measuring the amplitude and phase, are significantly slower when compared to our proposed method. This research presents a high-speed scanning technique based on an estimation law to obtain the topography of various...
The effect of geometry on structural behavior of buildings with steel plate shear wall system subjected to blast loading
, Article International Journal of Steel Structures ; Volume 21, Issue 2 , 2021 , Pages 650-665 ; 15982351 (ISSN) ; Moghaddam, H ; Saedi Daryan, A ; Sharif University of Technology
Korean Society of Steel Construction
2021
Abstract
Many important public buildings have suffered significant damages due to terrorist attacks in the last few decades. This paper investigates the behavior of structures with steel plate shear wall lateral load resisting system under various blast loadings. A number of twenty steel frames with different heights and widths subjected to four different blast scenarios are modeled and analyzed in opensees software. The results showed that structures with steel plate shear wall systems subjected to blast loading have better behavior in high-rise structures than in low-rise structures in terms of drift and ductility ratio. The steel plate shear wall system exhibited shear-dominated,...
Surge motion passive control of TLP with double horizontal tuned mass dampers
, Article International Journal of Acoustics and Vibrations ; Volume 26, Issue 1 , 2021 , Pages 4-8 ; 10275851 (ISSN) ; Malayjerdi, E ; Sharif University of Technology
International Institute of Acoustics and Vibrations
2021
Abstract
The tension leg platform (TLP) is comprised of a buoyant hull that holds the platform’s topside. A group of tendons under the columns connect the TLP to the foundation. The TLP is displaced in six degrees of freedom due to environmental loads. Tendons moor the TLP in vertical direction (heave and pitch). Surge amplitude (horizontal displacement) of TLP is greater than other degrees of freedom. Also heave motion is coupled with surge one. Therefore, it is important to introduce and implement a method to control and reduce displacement of the TLP in horizontal direction. In this paper, a passive control system (double horizontal tuned mass damper (TMD)) is used to mitigate the surge motion of...