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optimal-design
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Optimized Design of Switch Circuit and Receiver Antenna in the Field of Fifth Generation Telecommunications to Reduce the Fading Effect
, M.Sc. Thesis Sharif University of Technology ; Akbari, Mahmood (Supervisor)
Abstract
The Deep Fading Effect is a destructive factor in communication systems, one of the solutions to eliminate it is the use of Diversity, and there are two types of indicators of Diversity, Spatial Diversity and Polarization Diversity. Spatial Diversity is a common method to reduce the Fading Effect while increasing the cost and increasing the volume of the communication station, which to optimize the cost and reduce the volume of the communication station, the Polarization Diversity Structure is added to the telecommunication system. To apply Spatial Diversity, several Antennas with different Polarizations are used, which The most common method in mobile telecommunication station systems is...
Optimal topological design of power communication networks using genetic algorithm
, Article Scientia Iranica ; Volume 20, Issue 3 , 2013 , Pages 945-956 ; 10263098 (ISSN) ; Rad, Z. B ; Sharif University of Technology
2013
Abstract
An electric power supply is the backbone of development in advanced as well as in developing economies. An integral part of ensuring a secure power supply system is a power communication system. Due to the high and sustained performance requirements of power communication systems, electric companies prefer to construct their own communication networks privately rather than relying solely on a public communication system. The focus of this paper is on the optimal topological design of a power communication network. Based on advanced optimization models in public communication networks, and taking into account the specific Quality of Service, as demanded by various applications, such as...
Analysis of effective parameters on ablative PPT performance
, Article Aircraft Engineering and Aerospace Technology ; Volume 84, Issue 4 , 2012 , Pages 231-243 ; 00022667 (ISSN) ; Schönherr, T ; Sharif University of Technology
2012
Abstract
Purpose - The purpose of this paper is to comprehensively review most of the significant works ever done worldwide to study the effects of essential parameters on pulsed plasma thruster (PPT) performance and to analyze the effects of each parameter on PPT performance. Design/methodology/approach - All the important works studying PPT performance are categorized by the parameter they have studied and its effect on the thruster performance, and their works have been reviewed to analyze the influence of each parameter. Findings - The analysis leads to elucidation of the effects of different geometrical parameters including aspect ratio, electrode width, electrode spacing, electrode shape,...
An analytical approach for optimal design of rotor iron for superconducting synchronous machine
, Article IECON Proceedings (Industrial Electronics Conference), 7 November 2011 through 10 November 2011, Melbourne, VIC ; 2011 , Pages 1741-1745 ; 9781612849720 (ISBN) ; Yazdanian, M ; Zolghadri, M. R ; Fardmanesh, M ; Sharif University of Technology
2011
Abstract
Although iron-cored superconducting machine has been recently proposed in many papers for its advantages over conventional air-cored structure such as less cost and less perpendicular magnetic component on HTS tapes it has not been studied analytically yet. This paper analytically investigates a general model for iron-cored superconducting synchronous machine. In this paper, analytical equations for magnetic flux in different regions of machine have been proposed along with an algorithm to solve the equations. The analytical equations will be then used to optimize the thickness of rotor iron in order to maximize the machine power density. Analytical and finite element simulation results will...
Optimal design of powder compaction processes via genetic algorithm technique
, Article Finite Elements in Analysis and Design ; Volume 46, Issue 10 , 2010 , Pages 843-861 ; 0168874X (ISSN) ; Keshavarz, S ; Biabanaki, S. O. R ; Sharif University of Technology
Abstract
In this paper, an optimal design is performed for powder die-pressing process based on the genetic algorithm approach. It includes the shape optimization of powder component, the optimal design of punch movements, and the friction optimization of powdertool interface. The genetic algorithm is employed to perform an optimal design based on a fixed-length vector of design variables. The technique is used to obtain the desired optimal compacted component by verifying the prescribed constraints. The numerical modeling of powder compaction simulation is applied based on a large deformation formulation, powder plasticity behavior, and frictional contact algorithm. A Lagrangian finite element...
Optimization of photovoltaic electrolyzer hybrid systems; taking into account the effect of climate conditions
, Article Energy Conversion and Management ; Volume 118 , 2016 , Pages 438-449 ; 01968904 (ISSN) ; Maroufmashat, A ; Sattari, S ; Elkamel, A ; Fowler, M ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
Solar energy will make a valuable contribution for power generation in the future. However the intermittency of solar energy has become an important issue in the utilization of PV system, especially small scale distributed solar energy conversion systems. The issue can be addressed through the management of production and storage of the energy in the form of hydrogen. The hydrogen can be produced by solar photovoltaic (PV) powered electrolysis of water. The amount of transferred energy to an electrolyzer from a PV module is a function of the distance between maximum power points (MPP) of PV module and the electrolyzer operating points. The distance can be minimized by optimizing the number...
A method for optimal reduction of locating error with the minimum adjustments of locators based on the geometric capability ratio of process
, Article International Journal of Advanced Manufacturing Technology ; 2017 , Pages 1-16 ; 02683768 (ISSN) ; Sharif University of Technology
Abstract
Imprecise productions with low quality are produced by the incapable manufacturing processes. Prediction of the process capability in the design stage plays a key role to improve the product quality. In this paper, a new method is proposed to optimally reduce the locating error by allocating the minimum adjustments of locators. To quantify the precision of the manufacturing process, a proper tool that is called the geometric capability ratio (GCR) of the manufacturing process is introduced. First, based on a part fixture model, the relationship between the locating error and its sources is developed. Then, using the proposed geometric capability ratio, the manufacturing process capability is...
A method for optimal reduction of locating error with the minimum adjustments of locators based on the geometric capability ratio of process
, Article International Journal of Advanced Manufacturing Technology ; Volume 94, Issue 9-12 , February , 2018 , Pages 3963-3978 ; 02683768 (ISSN) ; Sharif University of Technology
Springer London
2018
Abstract
Imprecise productions with low quality are produced by the incapable manufacturing processes. Prediction of the process capability in the design stage plays a key role to improve the product quality. In this paper, a new method is proposed to optimally reduce the locating error by allocating the minimum adjustments of locators. To quantify the precision of the manufacturing process, a proper tool that is called the geometric capability ratio (GCR) of the manufacturing process is introduced. First, based on a part fixture model, the relationship between the locating error and its sources is developed. Then, using the proposed geometric capability ratio, the manufacturing process capability is...
Optimized design of adaptable vibrations suppressors in semi-active control of circular plate vibrations
, Article Scientia Iranica ; Volume 26, Issue 3B , 2019 , Pages 1358-1377 ; 10263098 (ISSN) ; Moradi, H ; Vossoughi, G. R ; Sharif University of Technology
Sharif University of Technology
2019
Abstract
Due to flexibility of thin plates, high-amplitude vibrations are observed when they are subjected to severe dynamic loads. Because of the extensive application of circular plates in industry, attenuating the undesired vibrations is of foremost importance. In this paper, Adaptable Vibration Suppressors (AVSs) as a semi-active control approach were utilized to suppress the vibrations in a free circular plate under the concentrative harmonic excitation. Using mode summation method, the mathematical model of the hybrid system including the plate and an arbitrary number of vibration suppressors was analyzed. By developing a complex multiple-loop algorithm, optimum values for the parameters of...
Optimized design of adaptable vibrations suppressors in semi-active control of circular plate vibrations
, Article Scientia Iranica ; Volume 26, Issue 3B , 2019 , Pages 1358-1377 ; 10263098 (ISSN) ; Moradi, H ; Vossoughi, G. R ; Sharif University of Technology
Sharif University of Technology
2019
Abstract
Due to flexibility of thin plates, high-amplitude vibrations are observed when they are subjected to severe dynamic loads. Because of the extensive application of circular plates in industry, attenuating the undesired vibrations is of foremost importance. In this paper, Adaptable Vibration Suppressors (AVSs) as a semi-active control approach were utilized to suppress the vibrations in a free circular plate under the concentrative harmonic excitation. Using mode summation method, the mathematical model of the hybrid system including the plate and an arbitrary number of vibration suppressors was analyzed. By developing a complex multiple-loop algorithm, optimum values for the parameters of...
Optimum seismic design of steel framed-tube and tube-in-tube tall buildings
, Article Structural Design of Tall and Special Buildings ; Volume 29, Issue 14 , 2020 ; Estekanchi, H. E ; Moosavian, H ; Sharif University of Technology
John Wiley and Sons Ltd
2020
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 minimum weight. The present paper aims at providing a practical methodology for the optimal design of steel tall building structures considering the constraints imposed by typical building codes. The applicability of the proposed approach is demonstrated through the determination of the optimal seismic design for 20-, 40-, and 60-story buildings with a framed tube as well as a tube-in-tube system. Such a design gives rise to a basis for the fair...
Probabilistic seismic performance assessment of optimally designed highway bridge isolated by ordinary unbonded elastomeric bearings
, Article Engineering Structures ; Volume 247 , 2021 ; 01410296 (ISSN) ; Khansefid, A ; Khaloo, A ; Ehteshami Moeini, M ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Following the idea of using unbonded isolators to eliminate the tensile stress and providing a cost-effective isolation system, recent experimental research has shown ordinary unbonded steel reinforced elastomeric bearings (SREBs) as an attractive option for seismic isolation of highway bridges. The focus of current research work is on the evaluation of the seismic vulnerability of a highway bridge isolated by unbonded SREBs through developing fragility curves of the structure. This assessment considers parameters playing a key role in the isolation system behavior, namely the friction coefficient, as well as the isolator aging effects. In this regard, a typical three-span highway bridge is...
Optimal design of truss structures with frequency constraints: a comparative study of DE, IDE, LSHADE, and CMAES algorithms
, Article Engineering with Computers ; 2021 ; 01770667 (ISSN) ; Mesbahi, P ; Moosavian, N ; Daliri, H ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2021
Abstract
The present study examines the performance of three powerful methods including the original differential evolution (DE), the improved differential evolution (IDE), and the winner of the CEC-2014 competition, LSHADE, in addition to the covariance matrix adaptation evolution strategy (CMAES) for size optimization of truss structures under natural frequency constraints. Despite the abundant researches on novel meta-heuristic algorithms in the literature, the application of CMAES, one of the most powerful and reliable optimization algorithms, on the optimal solution of the truss structures has received scant attention. For consistent comparison between these algorithms, four stopping criteria...
A new scheme for the development of IMU-based activity recognition systems for telerehabilitation
, Article Medical Engineering and Physics ; Volume 108 , 2022 ; 13504533 (ISSN) ; Eslaminia, A. R ; Bakhshayesh, P. R ; Ejtehadi, M ; Alibiglou, L ; Behzadipour, S ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Wearable human activity recognition systems (HAR) using inertial measurement units (IMU) play a key role in the development of smart rehabilitation systems. Training of a HAR system with patient data is costly, time-consuming, and difficult for the patients. This study proposes a new scheme for the optimal design of HARs with minimal involvement of the patients. It uses healthy subject data for optimal design for a set of activities used in the rehabilitation of PD1 patients. It maintains its performance for individual PD subjects using a single session data collection and an adaptation procedure. In the optimal design, several classifiers (i.e. NM, k-NN, MLP with RBF as a hidden layer, and...
Optimization of cervical cage and analysis of its base material: A finite element study
, Article Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine ; Volume 236, Issue 11 , 2022 , Pages 1613-1625 ; 09544119 (ISSN) ; Abollfathi, N ; Khajehzhadeh, M ; Hassani Gangaraj, M ; Sharif University of Technology
SAGE Publications Ltd
2022
Abstract
Nowadays, cervical disorders are common due to human lifestyles. Accordingly, the cage design should be optimized as an essential issue. For an optimal design, an objective function is utilized to calculate the proper geometrical parameters. Additionally, the base material of the cage plays a key role in its functionality and final cost. Novel materials are currently introduced with more compatibility with the bone in terms of mechanical and chemical properties. In this study, a cervical cage was modeled based on PEEK material with three types of tooth designs on its surface. The cervical cage is assumed to be implanted between C6 and C7 vertebrae. The geometric parameters of the cage were...
A discrete differential evolution with local search particle swarm optimization to direct angle and aperture optimization in IMRT treatment planning problem
, Article Applied Soft Computing ; Volume 131 , 2022 ; 15684946 (ISSN) ; Mahnam, M ; Akhavan Niaki, S. T ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Intensity-modulated radiation therapy is a well-known technique for treating cancer patients worldwide. A treatment plan in this technique requires decision-making for three main problems: selection of beam angles, intensity map calculation, and leaf sequencing. Previous works investigated these problems sequentially. We present a new integrated framework for simultaneous decision-making of directions, intensities, and aperture shape, called direct angle and aperture optimization, and develop a mixed-integer nonlinear mathematical model for the problem. Due to the nonlinearity and the dimension of the problem, three efficient metaheuristics based on differential evolution (DE) called classic...
A novel optimized design of a piezoelectric-driven 4-stage amplified compliant microgripper using a 2-step multi-objective algorithm
, Article SN Applied Sciences ; Volume 4, Issue 4 , 2022 ; 25233971 (ISSN) ; Shabani, S ; Honarmand, M ; Sharif University of Technology
Springer Nature
2022
Abstract
Abstract: Advancements in microscale technologies have prompted a demand for high precision micro-manipulation. Microgrippers are the primary means of conducting micro-scale operations, and they significantly affect the procedure's performance. This paper presents a novel optimized design for compliant microgrippers, intending to enhance functionality and durability. The mainframe of the proposed microgripper is based on a compact flexure-based compliant structure with four stages of movement amplification. Experiments were designed based on the L25 Taguchi orthogonal arrays. The experiments were conducted using the finite element method in Abaqus 6.14 workbench. Range of motion and maximum...
Optimal design of solar concentrator in multi-energy hybrid systems based on minimum exergy destruction
, Article Renewable Energy ; Volume 190 , 2022 , Pages 78-93 ; 09601481 (ISSN) ; Saboohi, Y ; Fathi, A ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
The paper presents a systematic approach to designing an imaging dish for a concentrator photovoltaic (CPV) system to minimize exergy destruction. The designed CPV system uniformly distributes light rays on the receiver (TPV/multi-junction PV) to enhance the conversion technology efficiency and lifetime. To this end, a parametric dish is designed using imaging optics and the numerical solution of a differential equation. Afterward, a Monte Carlo simulation is used to estimate the output energy and exergy of the CPV system with the parametric dish. Finally, an optimization algorithm finds the optimal design parameters to minimize the system's exergy destruction. The optimal design leads to a...
Optimal design and performance analysis of a double-sided multiturn wound-rotor resolver
, Article IEEE/ASME Transactions on Mechatronics ; Volume 27, Issue 1 , 2022 , Pages 493-500 ; 10834435 (ISSN) ; Saneie, H ; Nasiri Gheidari, Z ; Tootoonchian, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
Multispeed resolvers are used in the applications that need higher accuracy. However, they suffer from losing absolute position information. To overcome this challenge and improve the reliability of detecting position, the use of multiturn resolvers is recommended. The conventional configuration of multiturn resolver is using two individual resolvers on one shaft and into a common frame. Using such configuration needs special care on setting the distance between two resolvers. In this article, a new structure based on a dual side configuration is proposed. The performance of the double-sided resolver is analyzed and optimized using an analytical model based on a magnetic equivalent circuit....
Life Cycle Cost-Based Optimal Seismic Design of Steel Buildings with Supplemental Dampers by Utilizing Endurance Time Method
, Ph.D. Dissertation Sharif University of Technology ; Esmaeil Pourestekanchi, Homayoon (Supervisor)
Abstract
This study proposes an efficient risk-targeted framework for integrated optimal seismic design and quantifying target safety of steel Special Moment-Resisting Frames (steel SMRFs) with and without various passive damping devices such as Buckling-Restrained Braces (BRBs), Friction Dampers (FDs), and Fluid Viscous Dampers (FVDs). This framework provides an automated design procedure formulated as a constrained single-objective optimization problem to achieve the minimum Life Cycle Cost (LCC) within the Particle Swarm Optimization (PSO) algorithm and can be the basis of current seismic codes for target safety calibration. LCC includes initial construction cost and lifetime seismic losses such...