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ghahremani--hamed
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Seismic performance and fragility analysis of power distribution concrete poles
, Article Soil Dynamics and Earthquake Engineering ; Volume 150 , 2021 ; 02677261 (ISSN) ; Mahsuli, M ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
This paper proposes probabilistic damage and collapse models for reinforced concrete poles in electric power distribution networks and investigates the damage and collapse pattern of poles under earthquake excitations. To this end, detailed finite element models of the H-type reinforced concrete poles are developed and verified using past experimental studies as well as the observed damage in previous earthquakes. The models are then subjected to nonlinear static analyses to study the effect of the loading pattern, loading direction, concrete strength, and failure criteria on the capacity and the collapse pattern of the pole. Next, incremental dynamic analysis is carried out to investigate...
An efficient tabu search algorithm for the single row facility location problem [electronic resource]
, Article European Journal Of Operational Research ; Vol. 205, No. 1, pp. 98-105 ; Eshghi, Kourosh ; Sharif University of Technology
Abstract
The general goal of the facility layout problem is to arrange a given number of facilities to minimize the total cost associated with the known or projected interactions between them. One of the special classes of the facility layout problem is the Single Row Facility Layout Problem (SRFLP), which consists of finding an optimal linear placement of rectangular facilities with varying dimensions on a straight line. This paper first presents and proves a theorem to find the optimal solution of a special case of SRFLP. The results obtained by this theorem prove to be very useful in reducing the computational efforts when a new algorithm based on tabu search for the SRFLP is proposed in this...
Sensitivity analysis of matching pennies game [electronic resource]
, Article Mathematical and Computer Modelling ; Volume 51, Issues 5–6, March 2010, Pages 722–735 ; Eshghi, Kourosh ; Sharif University of Technology
Abstract
In this paper, we have discussed the results of sensitivity analysis in a payoff matrix of the Matching Pennies game. After representing the game as a LP model, the sensitivity analysis of the elements of the payoff matrix is presented. The game value and the optimal strategies for different values of parameters are determined and compared
Quantifying seismic response uncertainty of electrical substation structures using endurance time method
, Article Structures ; Volume 30 , 2021 , Pages 838-849 ; 23520124 (ISSN) ; Estekanchi, H. E ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
A new procedure is proposed to quantify uncertainties involved in the seismic response of structures including ground motion and modeling variability. The advent of performance-based earthquake engineering (PBEE) and probabilistic seismic risk analysis necessitates consideration of uncertainties in predicting seismic responses. However, the high computational cost of conventional methods restricts their application to only simple numerical models. The present study employs the endurance time (ET) method concept to predict the response distribution which requires much less computational efforts than conventional methods. The proposed procedure for the quantification of record-to-record...
Reachability in injective piecewise affine maps
, Article Proceedings - Symposium on Logic in Computer Science ; Volume 2023-June , 2023 ; 10436871 (ISSN); 979-835033587-3 (ISBN) ; Kelmendi, E ; Ouaknine, J ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2023
Abstract
One of the most basic, longstanding open problems in the theory of dynamical systems is whether reachability is decidable for one-dimensional piecewise affine maps with two intervals. In this paper we prove that for injective maps, it is decidable.We also study various related problems, in each case either establishing decidability, or showing that they are closely connected to Diophantine properties of certain transcendental numbers, analogous to the positivity problem for linear recurrence sequences. Lastly, we consider topological properties of orbits of one-dimensional piecewise affine maps, not necessarily with two intervals, and negatively answer a question of Bournez, Kurganskyy, and...
Temperature-Dependent Hierarchical Multi-Scale Modeling of Nano-Materials Considering Surface Effect
, M.Sc. Thesis Sharif University of Technology ; Khoei, Amir Reza (Supervisor)
Abstract
In continuum mechanics, the constitutive models are usually based on the Cauchy-Born (CB) hypothesis which seeks the intrinsic characteristics of the material via the atomistic information and it is valid in small deformation. The main purpose of this thesis is to investigate the temperature effect on the stability and size dependency of Cauchy-Born hypothesis and a novel temperature-dependent multi-scale method is developed to investigate the role of temperature on surface effects in the analysis of nano-scale materials. Three-dimensional temperature-related Cauchy-Born formulation are developed for crystalline structure and the stability and size dependency of temperature-related...
A Model for Reducing the Cost of Organization with the Use of Process Attitude (Along with a Case Study)
, M.Sc. Thesis Sharif University of Technology ; Eshraghniaye Jahromi, Abdolhamid (Supervisor)
Abstract
Undoubtedly, reducing the organization's costs in today's world economy situation is a requisite for the survival of the organization. In order to continue their economic life, organizations must make their movements more effective by reducing costs and increasing agility and productivity. Various methods have been proposed to reduce costs, but before any measurements, identification of the reducible factors is very necessary.
Improving processes in an organization is considered as one of the best ways to reduce costs and increase profitability. In this research, the goal is to provide a model for reducing costs using process attitude so that the associated costs of the organization can...
Improving processes in an organization is considered as one of the best ways to reduce costs and increase profitability. In this research, the goal is to provide a model for reducing costs using process attitude so that the associated costs of the organization can...
An analytical investigation of transient imperfectly expanded turbulent jet
, Article Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering ; Volume 236, Issue 14 , 2022 , Pages 3057-3063 ; 09544100 (ISSN) ; Aramfard, M ; Saidi, M. H ; Sharif University of Technology
SAGE Publications Ltd
2022
Abstract
Supersonic turbulent high-pressure jet flows, which are discharging in low-pressure quiescent ambient, are recognized as imperfectly expanded turbulent jet. Steady-state imperfectly expanded jet flow has been already studied analytically; however, the transient flow has not been thoroughly studied. In the present study, the transient imperfectly expanded jet flow with focus on fuel spray in combustion is investigated analytically employing two-step separation of variables method and Fourier-Bessel expansion. The results are validated using available experimental data. The effects of different parameters such as eddy viscosity and pressure ratio on the behavior of the jet are studied. Results...
Temperature-dependent multi-scale modeling of surface effects on nano-materials
, Article Mechanics of Materials ; Volume 46 , March , 2012 , PP. 94–112 ; Ghahremani, P ; Sharif University of Technology
2012
Abstract
In this paper, a novel temperature-dependent multi-scale method is developed to investigate the role of temperature on surface effects in the analysis of nano-scale materials. In order to evaluate the temperature effect in the micro-scale (atomic) level, the temperature related Cauchy–Born hypothesis is implemented by employing the Helmholtz free energy, as the energy density of equivalent continua relating to the inter-atomic potential. The multi-scale technique is applied in atomistic level (nano-scale) to exhibit the temperature related characteristics. The first Piola–Kirchhoff stress and tangential stiffness tensor are computed, as the first and second derivatives of the free energy...
Dynamic responses of a rectangular plate under motion of an oscillator using a semi-analytical method
, Article JVC/Journal of Vibration and Control ; Volume 17, Issue 9 , 2011 , Pages 1310-1324 ; 10775463 (ISSN) ; Kargarnovin, M. H ; Ghahremani, A. R ; Sharif University of Technology
2011
Abstract
A semi-analytical method is presented to calculate the dynamic responses of a rectangular plate due to a moving oscillator. In previous analytical solutions of the moving oscillator problem, the elastic distributed structure has usually been modeled by an elastic beam structure. This restrictive assumption is removed in this study by assuming a general plate as two-dimensional elastic distributed structure. The method can be applied for any arbitrary path on the plate. A combination of the Fourier and Laplace transformation as well as the convolution theorem is used to solve the governing differential equations of the problem. A modified integration technique is then presented to solve the...
Simultaneous analytical solution of the complete system of double-inlet pulse tube refrigerator
, Article Journal of Thermophysics and Heat Transfer ; Volume 26, Issue 2 , 2012 , Pages 337-344 ; 08878722 (ISSN) ; Saidi, M. H ; Ebrahimian, M ; Sharif University of Technology
2012
Abstract
Double-inlet pulse tube refrigerators are one of the most common types of cryocoolers. There are several advantages of double-inlet pulse tube refrigerators, such as not having moving parts, reliability, and long life. Double-inlet pulse tube refrigerators have been used in several applications such as cooling the semiconductors, infrared sensors, and astronomical detectors. In the recent decade, several research efforts have been performed to investigate double-inlet pulse tube refrigerators. Generally, most of them are experimental or numerical, and the recent literature survey shows there is not an analytical solution for the complete system of a double-inlet pulse tube refrigerator,...
Numerical modeling of pulse tube refrigerator and sensitivity analysis of simulation
, Article HVAC and R Research ; Volume 19, Issue 3 , 2013 , Pages 242-256 ; 10789669 (ISSN) ; Saidi, M. H ; Ghahremani, A. R ; Sharif University of Technology
2013
Abstract
In this article a double-inlet pulse-tube refrigerator (DIPTR) is modeled using the nodal analysis technique. The main complexity of the problem is oscillatory and unsteady characteristics of the flow. Solving the flow field in the regenerator section of the system as a porous medium with nonlocal thermal equilibrium is challenging. Governing equations are developed applying mass, energy, and momentum equations to different finite volumes in each component of DIPTR. A numerical code (SharifPTR), with graphical user interface, has been developed to investigate the influence of geometrical and working parameters on performance. The governing equations are a system of boundary value problems....
A UHF-RFID transceiver with a blocker-canceller feedback and 30 dBm output power
, Article IEEE Transactions on Circuits and Systems I: Regular Papers ; Volume 60, Issue 11 , 2013 , Pages 3043-3054 ; 15498328 (ISSN) ; Rezaei, V. D ; Bakhtiar, M. S ; Sharif University of Technology
2013
Abstract
A single chip UHF-RFID transceiver front-end is presented. The chip was designed according to EPCglobal Class-1 Gen-2 and supports both ETSI and FCC requirements. The receiver front end is capable of rejecting self-jammers as large as 10 dBm with the aid of a feedback loop. The stability and the robustness of the loop and other system requirements are studied. A 30 dBm class-AB power amplifier (PA) with 28% PAE is also integrated on the chip. The pseudo differential architecture of the PA greatly reduces the injection of the signal into the substrate. A simple model is used to estimate the effect of the substrate noise injection by the PA on the receiving circuit modules and design guides...
Identifying Active Followership Behaviors in Interaction with Managers with Autocratic Leadership Style in an Iranian Organization
, M.Sc. Thesis Sharif University of Technology ; Alavi, Babak (Supervisor) ; Banki, Sara (Supervisor)
Abstract
Purpose: The purpose of this thesis was to identify active followership behaviors of followers in interaction with autocratic leaders. An active follower thinks critically and takes initiatives.
Design: Given that Followership literature is still in its infancy, the research questions needed a qualitative approach, in this case grounded theory. In total, 19 top- & middle-level managers were interviewed as leaders and followers, accordingly, using semi-structured interviews.
Findings: 4 categories of active followership were found, each having 3-4 specific behaviors. These categories are: precautionary behaviors, facilitating behaviors, modificating behaviors, and consolidating...
Design: Given that Followership literature is still in its infancy, the research questions needed a qualitative approach, in this case grounded theory. In total, 19 top- & middle-level managers were interviewed as leaders and followers, accordingly, using semi-structured interviews.
Findings: 4 categories of active followership were found, each having 3-4 specific behaviors. These categories are: precautionary behaviors, facilitating behaviors, modificating behaviors, and consolidating...
A Framework for Seismic Risk Assessment of Electrical Substation Equipment with Reliability and Endurance Time Methods
, M.Sc. Thesis Sharif University of Technology ; Esmaeil Purestekanchi, Homayoon (Supervisor)
Abstract
Influences of dynmic interaction between substation equipment on responses and fragility are studied. Proposing a framework for seismic risk analysis of substation equipment using reliability and endurance time methods is another aim of this project. Risk, in this contex, means the probability of exceeding monetary loss. Three dimensional models of four vulnerable types of equipment including surge arrester, current transformer, circuit breaker and disconnect switch are developed and verified. Six different systems of equipment connected through rigid bus bars comprising of two, three and four equipment are considered. Fragility curves are developed for equipment in both unconnected and...
Parametric study and computation of seismic performance factors of braced shear panels
, Article Scientia Iranica ; Volume 23, Issue 2 , 2016 , Pages 460-474 ; 10263098 (ISSN) ; Mofid, M ; Sharif University of Technology
Sharif University of Technology
2016
Abstract
By locating a steel shear panel on the intersection point of the X-braces, concentrically or eccentrically braced shear panel (CBFSP or EBFSP) is formed. In this paper, to perform parametric study, 1-story CBFSP and EBFSP models with span length greater or less than height are considered. Using linear static analyses, the effects of size and location of the shear panel on the lateral stiffness of the frame with respect to the moment resisting frame with the same member sections are investigated. Next, for 1- And 3-story models, maximum displacement, along with base shear, and the ratio between the dissipated energy and input energy are examined under 4 ground motion records. Behavior of the...
Assessment of Seismic Retrofit Policies for Buildings
, M.Sc. Thesis Sharif University of Technology ; Kashani, Hamed (Supervisor)
Abstract
Occurrence of natural disasters such as earthquake could seriously damage most buildings especially those with insufficient resistance located in urban worn-out textures. In order to reduce unpleasant consequences of an earthquake, appropriate policies need to be considered to persuade the beneficiaries to follow retrofitting standards in the process of planning, designing, and construction of buildings. These policies shall be implemented through institutions in arbitrary or obligatory forms, by encouragement or penalty mechanisms. In order to consider these policies, first of all we need to identify the beneficiaries and their particulars. By studying and considering subjects discussed in...
Optimal-Robust Control of Drug Delivery in Cancer Chemotherapy
, M.Sc. Thesis Sharif University of Technology ; Moradi, Hamed (Supervisor)
Abstract
Chemotherapy is a proven and effective systematic approach to treat various types of cancers. Despite its advantages, chemotherapy would kill healthy as well as cancer cells. To overcome this problem, different controlling strategies are implemented. This study aims to provide a medicine drug delivery schedule for chemotherapy (by designing a proper controlling system) based on the verifiable mathematical models. First, the dynamic model is analysed and stability points are reviewed. The selected model has five state variables and two inputs. In this study, the focus is on dynamic model analysis and obtaining an effective and appropriate treatment pattern by designing a proper controller. To...
Real Options Analysis Framework for the Optimal Timing of Network Infrastructure Systems Retrofits
, M.Sc. Thesis Sharif University of Technology ; Kashani, Hamed (Supervisor)
Abstract
Natural disasters can damage the infrastructure of society. Damages to the infrastructure components of society can disrupt their service delivery. Disruption in providing services to society's infrastructure can disrupt social and economic activities and impose various significant costs on society. The cost of repairing the damaged infrastructure and reducing the income of households are among the economic damages of accidents. The decline in the quality of life, as well as the death and injury of people due to the breakdown of the infrastructure or the disruption in their services, are among the social damages caused by accidents. In the same way, natural disasters are considered a...
Analysis of Seismic Vulnerability Reduction Policies of Residential Buildings Using a Multi-agent Evolutionary Game Model Based on Prospect Theory
, M.Sc. Thesis Sharif University of Technology ; Kashani, Hamed (Supervisor)
Abstract
Due to the vulnerability of urban fabric and residential buildings to earthquakes and considering its destructive social and economic effects on society, the need to adopt appropriate policies to prevent and reduce vulnerability, has been increasingly considered by policy makers. Despite the laws, regulations, incentives and penalties that policymakers have envisioned to prevent unprincipled and unsafe construction, evidence shows that a significant number of new buildings being built in the country are not earthquake resistant and there are many violations in design, implementation and supervision that is done by the stakeholders. To solve this problem, research has been done on the...