Loading...
Search for:
structural-optimization
0.01 seconds
Total 101 records
Application and Comparison of Modern Optimization Methods for Optimal Seismic Design of Trusses under Base Excitation
, M.Sc. Thesis Sharif University of Technology ; Joghatayi, Abdolreza (Supervisor)
Abstract
Taking into consideration of optimization methods has been increased recently. Optimization methods in engineering that consumes a lot of time and cost have been developed. Optimal design of structures is a matter that grabbed the attention of civil engineers and due to the deficiency of classical methods the modern approaches are being developed. One of the most important structures that are constructed for industrial and transportation purposes are truss structures.Structural control under support excitation is constraining the structure to some structural limitations. The final target in this paper is to apply the modern methods to get the optimal weight of structure under seismic loads....
Value-Based Seismic Design of Framed Tube System of Tall Steel Buildings
, M.Sc. Thesis Sharif University of Technology ; Esmaeil Pourestekanchi, Homayun (Supervisor)
Abstract
The objective of this research is to evaluate the concept of a new design methodology based on the total value of the structure namely Value Based Design of structures (VBD) by the use of potential benefits of the ET method. While prescriptive and also performance based approaches of seismic design commonly try to find a structure with lower initial cost satisfying a number of requirements under seismic actions, a new design approach to incorporate directly the concept of value in design procedure have been formulated here to achieve an economical design with lower total cost in its life time. In this method the design sections of structural elements are considered as optimization parameters...
Optimization of Distribution and Stiffness of Connections in Steel Frames by Value based Seismic Design
, M.Sc. Thesis Sharif University of Technology ; Esmail Pourestekanchi, Homayoon (Supervisor)
Abstract
Structural optimization has always been one of the concerns of engineers. Usually, engineers decide to optimize the structure with its weight. Nowadays we know that the best solution in weight optimization is not good for the structural damage and performance of the structure due to risk analysis.In this study, using the genetic algorithm to reduce construction cost, Loss and damaged cost and total cost of the structure by calculating structural damage based on FEMA-P58 guidelines according to two types of connections (rigid or hinge) and their elements (beams and columns) in two types of structures 4 and 8 story has been investigated.At each stage of increment in algorithms, first, the...
Optimum Seismic Design Assessment of Tall Buildings Based on Life Cycle Cost Using Endurance Time Method
, Ph.D. Dissertation Sharif University of Technology ; Esmail Pourestekanchi, Homayoon (Supervisor) ; Ghannad, Mohammad Ali (Co-Supervisor)
Abstract
The relatively large number of structural elements and the variety of design code requirements complicate the design process of tall buildings. This process is exacerbated when the target is to obtain the seismic code-compliant optimal design with the minimum weight which results in a large-scale and challenging optimization problem. On the other hand, past earthquakes and hurricanes demonstrated that while satisfying the requirements of the conventional design codes guarantees the life safety of the occupants, significant economic losses may still be incurred. This highlights the importance of considering life cycle costs in the design process of the structures. But the issue is that the...
Determination of Stable Crystal Structure of Y358 New Superconductor and its Phonon and Electronic Structure using Density Functional Theory
, M.Sc. Thesis Sharif University of Technology ; Khosroabadi, Hossein (Supervisor) ; Akhavan, Mohammad (Co-Advisor)
Abstract
Y-based Superconducting compounds (YBCO) with different stoichiometry have been considered by researchers for its transition temperature above the boiling temperature of liquid nitrogen, preparation of high quality samples, simple crystal and electronic structure and other advantages relative to the other high-Tc copper oxide superconductors. Reaching to higher transition temperature has been considered in the recent years. In 2009, new compound of this family with different stoichiometry Y3Ba5Cu8O18(Y358) and transition temperature above 100 K was synthesized which is 10 K higher than maximum transition temperature in this family. Confirming this transition temperature can be help us for...
An Investigation on the Effect of Design Parameters on Behabior of Prestressed Ring-Shaped Steel Structures
, M.Sc. Thesis Sharif University of Technology ; Esmaeil Purestekanchi, Homayoon (Supervisor)
Abstract
A tensile-compression ring is derived from the spoke wheel principle. The wheel is one of the greatest inventions in mankind. The use of the wheel has developed through time. Engineers found out that the use of the spoke wheel as a roof structure provides many benefits. With the spoke wheel principle a lightweight, cost-efficient roof structure can be made. In recent years the spoke wheel principle has also been applied for oval shaped roofs in order to increase the application of the principle. An example is the use of the roof structure for football stadia. The problem is that the spoke wheel principle will only work at full extend when its shape is completely circular. The question rises...
Inverse design of supersonic diffuser with flexible walls using a Genetic Algorithm
, Article Journal of Fluids and Structures ; Volume 22, Issue 4 , 2006 , Pages 529-540 ; 08899746 (ISSN) ; Ziaei-Rad, M ; Sharif University of Technology
2006
Abstract
An efficient algorithm for the design optimization of the compressible fluid flow problem through a flexible structure is presented. The methodology has three essential parts: first the behavior of compressible flow in a supersonic diffuser was studied numerically in quasi-one-dimensional form using a flux splitting method. Second, a fully coupled sequential iterative procedure was used to solve the steady state aeroelastic problem of a flexible wall diffuser. Finally, a robust Genetic Algorithm was implemented and used to calculate the optimum shape of the flexible wall diffuser for a prescribed pressure distribution. © 2006 Elsevier Ltd. All rights reserved
Comparative analysis of hydrate formation pressure applying cubic equations of state (eos), artificial neural network (ann) and adaptive neuro-fuzzy inference system (anfis)
, Article International Journal of Thermodynamics ; Volume 15, Issue 2 , 2012 , Pages 91-101 ; 13019724 (ISSN) ; Saber, M ; Ameri, A ; Sharif University of Technology
Abstract
The objective of this work is making comparison between thermodynamic models and data-driven techniques accuracy in prediction of hydrate formation pressure as a function of temperature and composition of gas mixtures. The Peng-Robinson (PR) and Patel-Teja (PT) equations of state are used for thermodynamic modeling and Artificial Neural Networks (ANNs) and Adaptive Neuro-Fuzzy Inference System (ANFIS) are used as data-driven models. The capability of each method is evaluated by comparison with the experimental data collected from literature. It is shown that there is a good agreement between thermodynamic modeling and the experimental data in most of the cases; however, the prediction...
Optimization of the calibration for an internal combustion engine management system using multi-objective genetic algorithms
, Article 2005 IEEE Congress on Evolutionary Computation, IEEE CEC 2005, Edinburgh, Scotland, 2 September 2005 through 5 September 2005 ; Volume 2 , 2005 , Pages 1254-1261 ; 0780393635 (ISBN) ; Rezazadeh, S ; Sharif University of Technology
2005
Abstract
This paper proposes a multi-objective structure for the optimization of an engine control unit mapping. In this way, first an integrated engine-vehicle model is developed. The objective functions for the optimization problem can be defined from this model. After describing the structure of the optimization problem, two different multi-objective genetic algorithms, namely Distance-based Pareto Genetic Algorithm and Non-Dominated Sorting Genetic Algorithm (together with Entropy-based Multi-Objective Genetic Algorithm), are proposed and implemented. The results demonstrate the superiority of this computerized structure to the manual mapping methods and also more generality of the...
An efficient approach for reflectivity and coupling computation in an abruptly ended planar layered waveguide using modified formulation of CGF-RFFM
, Article German Microwave Conference, GeMiC 2016, 14 March 2016 through 16 March 2016 ; 2016 , Pages 128-131 ; 9783981266870 (ISBN) ; Shishegar, A. A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2016
Abstract
An efficient method for computation of surface wave (SW) reflectivity and coupling in an abruptly ended planar layered waveguide is presented. Using characteristic Green's function (CGF) technique, the original structure is approximated by a separable structure. Then by applying rational function fitting method (RFFM) a uniform and closed-form expression of spatial Green's function for separable structure is derived. Having a full wave solution of the original structure, an optimization problem is defined to find the reflection coefficients of SW modes. Unlike the previous presented CGF based method called CGF-complex images (CI), CGF-RFFM leads to easy incorporation of radiation modes...
Optimal riser design in sand casting process with evolutionary topology optimization
, Article Structural and Multidisciplinary Optimization ; Volume 38, Issue 2 , 2009 , Pages 205-214 ; 1615147X (ISSN) ; Davami, P ; Sharif University of Technology
2009
Abstract
The optimal design of a casting feeding system is considered. The riser topology is systematically modified to minimize the riser volume, while simultaneously ensuring that no defect appears in the product. In this approach, we combine finite-difference analysis of the solidification process with evolutionary topology optimization to systematically improve the feeding system design. The outstanding features of the presented method are: its efficiency, ease of implementation and simplifying definition of the initial design. The efficiency and capability of the presented method are supported by illustrative examples. © 2008 Springer-Verlag
Feeder growth: a new method for automatic optimal feeder design in gravity casting processes
, Article Structural and Multidisciplinary Optimization ; Volume 39, Issue 5 , 2009 , Pages 519-530 ; 1615147X (ISSN) ; Davami, P ; Sharif University of Technology
2009
Abstract
The optimal feeder design in gravity casting processes is considered. The design problem is formulated as an additive, growth-like, evolutionary topology optimization problem. The initial design of the presented method is a casting part which is placed in a suitable environmental mould box. The method is composed of three stages: determining the feeder-neck connection point on the casting surface, constructing the feeder-neck and the feeder growth. During the growth stage, the feeder topology is changed gradually until satisfying some predefined criteria. The design of multiple feeders is also considered in this work. In the presented method, feeders are designed in a descending order of...
Optimal riser design in sand casting process by topology optimization with SIMP method I: poisson approximation of nonlinear heat transfer equation
, Article Structural and Multidisciplinary Optimization ; Volume 36, Issue 2 , 25 January , 2008 , Pages 193-202 ; 1615147X (ISSN) ; Davami, P ; Sharif University of Technology
2008
Abstract
The optimal design of a casting feeding system is considered. The problem is formulated as the volume constrained topology optimization and is solved with the finite element analysis, explicit design sensitivity, and numerical optimization. In contrast to the traditional topology optimization where the objective function is defined on the design space, in the presented method, the design space is a subset of the complement of the objective function space. To accelerate optimization procedure, the nonlinear unsteady heat transfer equation is approximated with a Poisson-like equation. The feasibility of the presented method is supported with illustrative examples. © 2007 Springer-Verlag
Optimum arrangement of braces in jacket platform based on strength and ductility
, Article Marine Structures ; Volume 71 , 2020 ; Fatemi, M ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Nonlinear behavior of jacket platforms is important in both design and rehabilitation issues that depends on the bracing arrangement. Both ductility and strength of the structures derived from pushover analysis are highly related to configuration of the braces. Considering a suitable criterion such as constant weight or constant stiffness and period of the structure in all arrangement cases, one can compare the capacity curves and find the best configuration. In this paper a simple logical method for investigating the strength and ductility of the jacket structure is presented, it is shown that global geometry and configuration of the braces are very important and effective in both strength...
Design of landmark pedestrian urban bridge with evolutionary topology optimization
, Article 7th Annual International Conference on Architecture and Civil Engineering, ACE 2019, 27 May 2019 through 28 May 2019 ; 2019 , Pages 100-120 ; 2301394X (ISSN) ; Aliakbarlou, H ; Khoraskani, R. A ; Hafezi, M ; Sharif University of Technology
Global Science and Technology Forum
2019
Abstract
one of the important issues of construction industry today, is providing a meaningful interconnectivity between Architecture and its technical and technological aspects. In construction projects aesthetic and form is habitually crucial for the architect while structural designers aim for efficiency and stability of the structure. This research is concerned with the design of an urban footbridge located in Tehran-Iran with social and cultural spaces in which the form of the bridge is obtained by the use of topology optimization process. The objective of this study is to investigate the utilization of topology optimization process in architecture in order to achieve a beneficial design...
Design of landmark pedestrian urban bridge with evolutionary topology optimization
, Article 7th Annual International Conference on Architecture and Civil Engineering, ACE 2019, 27 May 2019 through 28 May 2019 ; 2019 , Pages 100-120 ; 2301394X (ISSN) ; Aliakbarlou, H ; Afghani Khoraskani, R ; Hafezi, M ; Anderson M. S. T ; Anderson P. C. O ; Sharif University of Technology
Global Science and Technology Forum
2019
Abstract
one of the important issues of construction industry today, is providing a meaningful interconnectivity between Architecture and its technical and technological aspects. In construction projects aesthetic and form is habitually crucial for the architect while structural designers aim for efficiency and stability of the structure. This research is concerned with the design of an urban footbridge located in Tehran-Iran with social and cultural spaces in which the form of the bridge is obtained by the use of topology optimization process. The objective of this study is to investigate the utilization of topology optimization process in architecture in order to achieve a beneficial design...
Non-linear metric learning using pairwise similarity and dissimilarity constraints and the geometrical structure of data
, Article Pattern Recognition ; Volume 43, Issue 8 , August , 2010 , Pages 2982-2992 ; 00313203 (ISSN) ; Bagheri Shouraki, S ; Sharif University of Technology
2010
Abstract
The problem of clustering with side information has received much recent attention and metric learning has been considered as a powerful approach to this problem. Until now, various metric learning methods have been proposed for semi-supervised clustering. Although some of the existing methods can use both positive (must-link) and negative (cannot-link) constraints, they are usually limited to learning a linear transformation (i.e., finding a global Mahalanobis metric). In this paper, we propose a framework for learning linear and non-linear transformations efficiently. We use both positive and negative constraints and also the intrinsic topological structure of data. We formulate our metric...
Kernel-based metric learning for semi-supervised clustering
, Article Neurocomputing ; Volume 73, Issue 7-9 , 2010 , Pages 1352-1361 ; 09252312 (ISSN) ; Bagheri Shouraki, S ; Sharif University of Technology
2010
Abstract
Distance metric plays an important role in many machine learning algorithms. Recently, there has been growing interest in distance metric learning for semi-supervised setting. In the last few years, many methods have been proposed for metric learning when pairwise similarity (must-link) and/or dissimilarity (cannot-link) constraints are available along with unlabeled data. Most of these methods learn a global Mahalanobis metric (or equivalently, a linear transformation). Although some recently introduced methods have devised nonlinear extensions of linear metric learning methods, they usually allow only limited forms of distance metrics and also can use only similarity constraints. In this...
Low loaded MoS2/Carbon cloth as a highly efficient electrocatalyst for hydrogen evolution reaction
, Article International Journal of Hydrogen Energy ; 2021 ; 03603199 (ISSN) ; Mehdipour, H ; Moshfegh, A. Z ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Active edge sites of MoS2 nanosheets exhibit promising futures for hydrogen evolution reaction (HER), comparable with remarkable performances of highly cost platinum. However, 3D structures of MoS2 suffer from a lack of high mobility and unexposed active sites which lower the electrocatalytic activity. In this study, we show that there is a balance between increasing the active sites on the one hand and managing the charge transfer to facilitate the reaction on the other hand, and achieving this balance increases the efficiency of the electrocatalyst tremendously. For this purpose, we directly attached exfoliated MoS2 nanosheets onto carbon cloth (CC) substrate as a 3D network of conductive...
Low loaded MoS2/Carbon cloth as a highly efficient electrocatalyst for hydrogen evolution reaction
, Article International Journal of Hydrogen Energy ; Volume 47, Issue 3 , 2022 , Pages 1579-1588 ; 03603199 (ISSN) ; Mehdipour, H ; Moshfegh, A. Z ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Active edge sites of MoS2 nanosheets exhibit promising futures for hydrogen evolution reaction (HER), comparable with remarkable performances of highly cost platinum. However, 3D structures of MoS2 suffer from a lack of high mobility and unexposed active sites which lower the electrocatalytic activity. In this study, we show that there is a balance between increasing the active sites on the one hand and managing the charge transfer to facilitate the reaction on the other hand, and achieving this balance increases the efficiency of the electrocatalyst tremendously. For this purpose, we directly attached exfoliated MoS2 nanosheets onto carbon cloth (CC) substrate as a 3D network of conductive...