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structural-modeling
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SCGG: A deep structure-conditioned graph generative model
, Article PLoS ONE ; Volume 17, Issue 11 November , 2022 ; 19326203 (ISSN) ; Hashemi Dijujin, N ; Soleymani-Baghshah, M ; Rabiee, H. R ; Sharif University of Technology
Public Library of Science
2022
Abstract
Deep learning-based graph generation approaches have remarkable capacities for graph data modeling, allowing them to solve a wide range of real-world problems. Making these methods able to consider different conditions during the generation procedure even increases their effectiveness by empowering them to generate new graph samples that meet the desired criteria. This paper presents a conditional deep graph generation method called SCGG that considers a particular type of structural conditions. Specifically, our proposed SCGG model takes an initial subgraph and autoregressively generates new nodes and their corresponding edges on top of the given conditioning substructure. The architecture...
The effect of soil-structure interaction on hysteretic energy demand of buildings
, Article Structural Engineering and Mechanics ; Volume 24, Issue 5 , 2006 , Pages 641-645 ; 12254568 (ISSN) ; Ghannad, M. A ; Sharif University of Technology
Techno-Press
2006
Abstract
The effect of soil-structure interaction (SSI) on hysteresis energy demand of buildings using an ensemble of alluvium site records was investigated. The structure and the soil were molded separately and then combined to constitute the soil-structure model using the sub-structure method. The key parameters effecting the response of the soil-structure system were found to be a non-dimensional frequency as a representative of structure to soil stiffness ratio; and aspect ratio of the building. It was found that the hysteric energy dissipated in a structure under an earthquake can be highly effected when the stiffness of the soil beneath the structure is altered
Investigation on Performance of Active Tuned Mass Dampers on Vibration Control of Three Dimentional Structures
,
M.Sc. Thesis
Sharif University of Technology
;
Rahimzadeh Rofooei, Fayyaz
(Supervisor)
Abstract
Tuned Mass Dampers(TMD) are among the most studied passive or active control devices that have been used around the world to control the lateral vibration of different building structures. On the other hand, since 2-D structural models are not appropriate for estimating the true response of the eccentric structures, application of 3-D models have been considered for determining their seismic-induced coupled lateral-torsional behavior. In this research, the performance of the Active Tuned Mass Dampers (ATMD) in controlling the seismic response of 3-D structural models was investigated. Three structural models with 4, 8 and 15 number of stories and 3 different eccentricities (0, 10% and 15%)...
Decentralized control of tall buildings
, Article Structural Design of Tall and Special Buildings ; Volume 15, Issue 2 , 2006 , Pages 153-170 ; 15417794 (ISSN) ; Monajemi Nezhad, S ; Sharif University of Technology
2006
Abstract
The response of large-scale building structures can be actively reduced using an appropriate control algorithm and a number of actuators and sensors located within the building. This paper presents a decentralized control approach for controlling the response of tall buildings. The proposed method aims to divide the structural model into several substructures, each one performing on its own controller algorithm. This approach has already been used in controlling large-scale systems such as power transmission systems and space structures. An instantaneous optimal control scheme is used as the control algorithm with different control feedbacks such as velocity feedback alone and displacement...
Simple model for exact heave motion of tension leg platform
, Article WSEAS Transactions on Mathematics ; Volume 5, Issue 5 , 2006 , Pages 500-506 ; 11092769 (ISSN) ; Golafshani, A. A ; Seif, M. S ; Sharif University of Technology
2006
Abstract
In this paper the dynamic response of the leg of a tension leg platform (tether) subjected to the load simulated as ocean wave at the top of the leg is presented. The structural model is very simple but several complicated factors such as foundation effect, buoyancy and simulated ocean wave load are considered. Two continuous models are proposed to present the structural system and the mentioned effects. The problem is solved by means of non-harmonic Fourier expansion in terms of eigenfunctions obtained from a non-regular Sturm-Liouville system
Colbert at haha 2021: parallel neural networks for rating humor in spanish tweets
, Article 2021 Iberian Languages Evaluation Forum, IberLEF 2021, 21 September 2021 ; Volume 2943 , 2021 , Pages 860-866 ; 16130073 (ISSN) ; Zoghi, G ; Sharif University of Technology
CEUR-WS
2021
Abstract
Previously, we proposed ColBERT, a humor detection model based on the general linguistic structure of humor for formal English texts. ColBERT uses BERT model to produce embeddings for the text sentences, which will be put as inputs into a parallel neural network. In this paper, we utilized the proposed model on informal Spanish texts to detect humor and rate its level. The current task has three differences compared to the original humor detection task on the ColBERT dataset: (1) rating humor is a regression task rather than binary classification, (2) texts are informal, and (3) texts are in a different language. Using our general model and without any knowledge of the Spanish language, we...
On the instability of spinning cylindrical shells partially filled with liquid
, Article International Journal of Structural Stability and Dynamics ; Volume 12, Issue 3 , 2012 ; 02194554 (ISSN) ; Permoon, M. R ; Haddadpour, H ; Sharif University of Technology
Abstract
The dynamics and stability of rotating circular cylindrical shells partially filled with ideal liquid is analyzed. The structural dynamics of the shell is modeled by using the first-order shear deformable shell theory and the flow inside the cylinder is simulated by a quasi 2D model based on the NavierStokes equations for ideal liquid. The fluid and structural models are combined using the nonpenetration condition of the flow on the wetted surface of the cylinder and the fluid pressure on the flexible shell. The obtained fluidstructure model is employed for the determination of the stable regions of the spinning frequency of the cylinder. A series of case studies are performed on the...
A reduced order model for liquid sloshing in tanks with flexible baffles using boundary element method
, Article International Journal for Numerical Methods in Engineering ; Volume 89, Issue 13 , 2012 , Pages 1652-1664 ; 00295981 (ISSN) ; Firouz Abadi, R. D ; Haddadpour, H ; Sharif University of Technology
2012
Abstract
In order to study the interaction of sloshing and structural vibrations of baffled tanks, a reduced order model based on modal analysis of structure model and boundary element method for fluids motion is developed. For this purpose, the governing equations of elastic structure and incompressible flow are used to derive simple models to simulate both fields. Using the modal analysis technique, the structural motions are applied to the fluid model and on the other hand by using boundary element method, the fluid loads are applied to the structural model. Based on this formulation, a code is developed which is applicable to an arbitrary elastic tank with arbitrary arrangement of baffles. The...
On the performance of passivr TMDs in reducing the damage in 2-D concrete structural models
, Article Procedia Engineering ; Volume 14 , 2011 , Pages 1665-1671 ; 18777058 (ISSN) ; Abtahi, P ; Sharif University of Technology
2011
Abstract
Pozzolanic materials, either naturally occurring or artificially made, have long been in practice since the early civilization. In recent years, the utilisation of pozzolanic materials in concrete construction has become increasingly widespread, and this trend is expected to continue in the years ahead because of technological, economical and ecological advantages of the materials. One of the latest additions to the ash family is palm oil fuel ash, a waste material obtained on burning of palm oil husk and palm kernel shell as fuel in palm oil mill boilers, which has been identified as a good pozzolanic material. This paper highlights test results on the performance behavior of palm oil fuel...
Semi-active vibration control of a marine structure with magnetorheological (MR) dampers utilizing LQR method
, Article Proceedings of the ASME Design Engineering Technical Conference, 15 August 2010 through 18 August 2010 ; Volume 5 , 2010 , Pages 651-659 ; 9780791844137 (ISBN) ; Zabihollah, A ; Sharif University of Technology
Abstract
The developing of technology has discovered new materials which have been applied to improve the performance of structures. The researchers have recently increased the attention in controllable fluids and its applications. Magnetorheological (MR) dampers are devices that employ rheological fluids to modify their mechanical properties. Their mechanical simplicity, high dynamic range, lower power requirements, large force capacity, robustness and safe manner operation in case of fail have made them attractive devices to passive, semi-active and active control in mechatronic, civil, aerospace and automotive applications. The characteristics of the MR damper change when the rheological fluid is...
Investigating the Performance of Tuned Mass Dampers in Controlling the Torsional Response of 3-D Steel Structural Models Under Earthquake Excitation
, M.Sc. Thesis Sharif University of Technology ; Rahimzadeh Rofouei, Fayyaz (Supervisor)
Abstract
Existing structural irregularities (in plan and elevation) has always been among the important causes of structural failures under strong earthquakes. The torsional related damages have especially been very important in multi-story buildings as the torsional behavior of structures changes their uniform translational vibration and causes concentration of demands in the elements at the perimeter of the buildings. On the other hand, the Tuned Mass Dampers (TMD) have in general been accepted as an effective passive structural control device to suppress the structural vibration. In this study, Three 3-D, irregular (in plan) steel structural models with 4, 8 and 15 number of floors are considered...
Evaluation of a Proposed Torsional TMD in Controlling the Seismic esponse of Asymmetric 3-D Steel Structural Models
, M.Sc. Thesis Sharif University of Technology ; Rahimzadeh Rofooei, Fayaz (Supervisor)
Abstract
This paper presents a new arrangement of Tuned Mass Dampers (TMDs) for response control of torsionally coupled 3-D building systems under bi-directional seismic inputs. In buildings with symmetric plan, two dampers, optimally designed, can be effectively used along each of the principal directions of the structural models to reduce their lateral displacement. The aim of this study is to explore the application of a torsional TMD to suppress the torsional response of the structures. The so-called Torsional TMD is consisted of two masses that are connected to each other by means of a rigid link. The pair of masses can rotate around the center point of the rigid link which is located on the...
Investigating the Performance of Viscoelastic Dampers in Reducing the Seismic Responses of 3D Irrigular Structural Models, Considering Soil-Structure Interaction
, M.Sc. Thesis Sharif University of Technology ; Rahimzadeh Rofooei, Fayyaz (Supervisor)
Abstract
Viscoelastic(VE) dampers are among the most practical passive control devices that are used to reduce the seismic-induced response of the structures. In this regard, extensive parametric studies have been conducted so far to investigate the performance of these dampers in reducing the seismic response of the structures under various types of ground motions and site soils. In most of these researches, the effect of soil-structure interaction (SSI) is neglected which is acceptable only for the structures located on stiff soils. In present research, the effect of the soil-structure interaction on the performance of VE dampers in reducing the seismic structural response is investigated. Also,...
Investigating the Performance of Tuned Mass Dampers in Controlling the Nonlinear Behavior of 3-D Structural Models Considering Soil-Structure Interaction By
,
M.Sc. Thesis
Sharif University of Technology
;
Rahimzadeh Rofooei, Fayyaz
(Supervisor)
Abstract
Reducing the seismic response of structures under dynamic loads has been highly considered by many researchers in the past few decades. Among them, Tuned Mass Dampers (TMD) have been studied extensively and used as a mean to control the response of structures under earthquake and wind loadings. In the majority of these studies, it is assumed that the structural models are located on rigid base and only their linear response has been considered. Soil-Structure Interaction (SSI) and nonlinear response of structures could have significant effect on the dynamic characteristics of structures that could results in detuning of TMDs. In this study, a number of 3-D nonlinear steel structural models...
Study of Physical Properties of Three Dimensional Graphene-Based Structures for Sensing Application
, Ph.D. Dissertation Sharif University of Technology ; Iraji zad, Azam (Supervisor) ; Jafari, Akbar (Co-Supervisor)
Abstract
In this thesis, physical properties and gas sensing application of three-dimensional graphene-based structures are studied. The three-dimensional structures of reduced graphene oxide and relative hybrids were synthesized through reducing graphene oxide aqueous solution. The arrangement of two-dimensional graphene layers in three-dimensional architectures has some advantages such as high surface area, hence increasing available adsorption sites. These properties result in changing electrical parameters of the structure, such as electrical impedance and phase angle in the presence of different mediums and alteration of temperature and pressure. Various characterization techniques like atomic...
Inverse vibration problem for un-damped 3-dimensional multi-story shear building models
, Article Journal of Sound and Vibration ; Volume 333, Issue 1 , 6 January , 2014 , Pages 99-113 ; ISSN: 0022460X ; Rofooei, F. R ; Sharif University of Technology
Abstract
Various researchers have contributed to the identification of the mass and stiffness matrices of two dimensional (2-D) shear building structural models for a given set of vibratory frequencies. The suggested methods are based on the specific characteristics of the Jacobi matrices, i.e., symmetric, tri-diagonal and semi-positive definite matrices. However, in case of three dimensional (3-D) structural models, those methods are no longer applicable, since their stiffness matrices are not tri-diagonal. In this paper the inverse problem for a special class of vibratory structural systems, i.e., 3-D shear building models, is investigated. A practical algorithm is proposed for solving the inverse...
Evolving a robust modeling tool for prediction of natural gas hydrate formation conditions
, Article Journal of Unconventional Oil and Gas Resources ; Volume 12 , December , 2015 , Pages 45-55 ; 22133976 (ISSN) ; Mesbah, M ; Shokrollahi, A ; Rozyn, J ; Lee, M ; Kashiwao, T ; Bahadori, A ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
Natural gas is a very important energy source. The production, processing and transportation of natural gas can be affected significantly by gas hydrates. Pipeline blockages due to hydrate formation causes operational problems and a decrease in production performance. This paper presents an improved artificial neural network (ANN) method to predict the hydrate formation temperature (HFT) for a wide range of gas mixtures. A new approach was used to define the variables for formation of a hydrate structure according to each species presented in natural gas mixtures. This approach resulted in a strong network with a precise prediction, especially in the case of sour gases. This study also...
Mathematical modelingof deflection of a beam: a finite element approach
, Article 2nd International Conference on Environmental and Computer Science, ICECS 20092009 ; Article number 5383533 , 2009 , Pages 161-164 ; 9780769539379 (ISBN) ; Durali, L ; Zareie, S ; International Association of Computer Science; and Information Technology (IACSIT) ; Parvari Rad, F ; Sharif University of Technology
Abstract
Introducing a suitable model for a structure to understand its behavior under different conditions of loading is very important. Mathematical modeling is the simulation of a physical structure or physical process by means of suitable analytical or numerical construct. One of suitable methods for finding deflection of a beam under different forms of loading is Finite Element Method (FEM). In this paper we find deflection of a beam using FEM based on Euler-Bernoulli and Timoshenko theory. © 2009 IEEE
Numerical study of propulsion performance in swimming fish using boundary element method
, Article Journal of the Brazilian Society of Mechanical Sciences and Engineering ; Volume 39, Issue 2 , 2017 , Pages 443-455 ; 16785878 (ISSN) ; Abbaspour, M ; Sharif University of Technology
Springer Verlag
2017
Abstract
In this paper, hydrodynamic simulation of fish-like swimming for two types of aquatic animals including tuna fish and giant danio is presented. We employ an unsteady three-dimensional inviscid boundary element method including time stepping algorithm to capture the wake sheet and flow features around swimming fish in a straight course. At each time step, an unsteady Bernoulli equation was used to find the pressure distribution and thrust generated by the animal. To couple fluid solver with kinematic equations of flexible body, undulating motions of backbone were defined using a prescribed continuous function. Although the flexible motion mechanism controls the fish swimming but no structural...
A structural model updating method using incomplete power spectral density function and modal data
, Article Structural Engineering and Mechanics ; Volume 68, Issue 1 , 2018 , Pages 39-51 ; 12254568 (ISSN) ; Ghareh Chaei, M ; Rofooei, F. R ; Sharif University of Technology
Techno Press
2018
Abstract
In this study, a frequency domain model updating method is presented using power spectral density (PSD) data. It uses the sensitivity of PSD function with respect to the unknown structural parameters through a decomposed form of transfer function. The stiffness parameters are captured with high accuracy through solving the sensitivity equations utilizing the least square approach. Using numerically noise polluted data, the model updating results of a truss model prove robustness of the method against measurement and mass modelling errors. Results prove the capabilities of the method for parameter estimation using highly noise polluted data of low ranges of excitation frequency. Copyright ©...