Loading...
Search for:
hasan-nasab--m
0.193 seconds
Total 20512 records
Thermal stresses and kinetics of phase transformation on the run-out table after hot strip rolling of low-carbon steels
, Article International Journal of Advanced Manufacturing Technology ; Volume 83, Issue 9-12 , 2016 , Pages 1725-1736 ; 02683768 (ISSN) ; Serajzadeh, S ; Sharif University of Technology
2016
Abstract
A thermo-elastic analysis coupled with a phase change model is employed to evaluate thermal stresses as well as progress of austenite decomposition after hot strip rolling operations. The thermo-mechanical finite element analysis is utilized to assess the distributions of temperature and thermal stresses during cooling while at the same time, a model based on the additivity rule is used to determine the rate of austenite to ferrite decomposition. The proposed model is applicable to multi-pass rolling schedules while the effects of different process parameters including the rolling speed and cooling configuration of the run-out table can be taken into account. In order to verify the...
Lot sizing and job shop scheduling with compressible process times: A cut and branch approach
, Article Computers and Industrial Engineering ; Volume 85 , 2015 , Pages 196-205 ; 03608352 (ISSN) ; Modarres, M ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
This paper studies simultaneous lot sizing and scheduling problem in a job shop environment over a finite number of periods. The machines are flexible such that the production manager is able to change their working speeds. Also, the production schedule of the items over machines should be in consistence with technological precedence relationships. The problem is formulated as an integer linear program. Then, a number of valid inequalities are developed based on the problem structures. The proposed valid inequalities are added to the problem formulation in a "cut and branch" manner to accelerate the search process by common solvers. Finally, performance of the valid inequalities is...
A self-adaptive PSO for joint lot sizing and job shop scheduling with compressible process times
, Article Applied Soft Computing Journal ; Volume 27 , Sharif University of Technology , 2015 , Pages 137-147 ; 15684946 (ISSN) ; Modarres, M ; Seyedhoseini, S. M ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
This paper presents mathematical modeling of joint lot sizing and scheduling problem in a job shop environment under a set of realistic working conditions. One main realistic assumption of the current study is dealing with flexible machines able to change their working speeds, known as process compressibility. The production schedules should be subject to limited available time in every planning period. Also, the model assumes that periodical sequences should be determined in a way that they obey from a fixed global sequence. Another complicating aspect of the problem is about consideration of precedence relationships for the needed processes of an item type over the corresponding machines....
Multi-period lot sizing and job shop scheduling with compressible process times for multilevel product structures
, Article International Journal of Production Research ; Volume 51, Issue 20 , 2013 , Pages 6229-6246 ; 00207543 (ISSN) ; Seyedhoseini, S. M ; Modarres, M ; Heidari, M ; Sharif University of Technology
2013
Abstract
This paper presents mathematical modelling of joint lot sizing and scheduling problem in job shop environment under a set of working conditions. The main feature of the problem is to deal with flexible machines able to change their working speeds, known as process compressibility. Furthermore, produced items should be assembled together to make final products. In other words, the products have a multilevel structure, shown with bill of materials. As the problem is proved to be strongly NP-hard, it is solved by a memetic algorithm here. Computational experiences on the data of Mega Motor company are reported. Also, further experiences on random test data confirm the performance of the...
The impact of demand response programs on UPFC placement
, Article Turkish Journal of Electrical Engineering and Computer Sciences ; Volume 27, Issue 6 , 2019 , Pages 4624-4639 ; 13000632 (ISSN) ; Ehsan, M ; Fotuhi Firuzabad, M ; Sharif University of Technology
Turkiye Klinikleri
2019
Abstract
Demand response (DR) and flexible AC transmission system (FACTS) devices can be effectively used for congestion management in power transmission systems. However, demand response program (DRP) implementation can itself affect the optimum location of FACTS devices, which is one of the main issues in power system planning. This paper investigates the impact of DRPs on unified power flow controller (UPFC) placement. The harmony search algorithm is employed to determine the optimum locations and parameter setting of UPFC in a long-term framework. The optimization problem is solved with different objectives including generation and congestion cost reduction, as well as loss reduction. In this...
Introducing GyroSym: a single-wheel robot
, Article International Journal of Dynamics and Control ; Volume 8, Issue 2 , 2020 , Pages 404-417 ; Abedin Nasab, M. H ; Liu, G ; Sharif University of Technology
Springer
2020
Abstract
In this paper, GyroSym, a compact highly-stable single-wheel robot is introduced. Symmetrical flywheels have been used as its stabilization mechanism to keep the wheel upright. Thanks to the type of the flywheel used, the dynamic equations of the robot is simplified, the torque needed to tilt the spin axis is reduced, and the space is drastically minimized. Besides, a centrifugal clutch is used to smooth the motion of the robot in forward motion. Two controllers, fuzzy and fuzzy-Padé, were implemented based on their ability to stabilize the robot. Although both prevented the GyroSym from falling over, neither can entirely cancel out the effects of nonlinear behaviors that is present in the...
Arbitrary Lagrangian-Eulerian unstructured finite-volume lattice-Boltzmann method for computing two-dimensional compressible inviscid flows over moving bodies
, Article Physical Review E ; Volume 101, Issue 2 , 2020 ; Hashemi Nasab, H ; Azampour, M. H ; Sharif University of Technology
American Physical Society
2020
Abstract
The objective of this study is to develop and apply an arbitrary Lagrangian-Eulerian unstructured finite-volume lattice-Boltzmann method (ALE-FVLBM) for solving two-dimensional compressible inviscid flows around moving bodies. The two-dimensional compressible form of the LB equation is considered and the resulting LB equation is formulated in the ALE framework on an unstructured body-fitted mesh to correctly model the body shape and properly incorporate the mesh movement due to the body motion. The spatial discretization of the resulting system of equations is performed by a second-order cell-centered finite-volume method on arbitrary quadrilateral meshes and an implicit dual-time stepping...
Application of arbitrary Lagrangian–Eulerian unstructured finite volume lattice Boltzmann method to simulate compressible viscous flows over moving bodies
, Article Meccanica ; Volume 58, Issue 12 , 2023 , Pages 2329-2346 ; 00256455 (ISSN) ; Hejranfar, K ; Azampour, M. H ; Sharif University of Technology
Springer Science and Business Media B.V
2023
Abstract
In this work, a central difference unstructured finite volume lattice Boltzmann method (FVLBM) in an arbitrary Lagrangian–Eulerian (ALE) framework is applied to effectively simulate the compressible viscous flows over moving bodies. Here, the two-dimensional compressible LB equation based on the multispeed Watari model is formulated in the ALE framework on an unstructured body-fitted mesh and the resulting equation is discretized by using the cell-centered finite volume method in which a central averaging scheme is made to calculate the numerical fluxes. A suitable dissipation term is added to the formulation to ensure the stability of the numerical scheme applied. The time integration is...
On the performance of high voltage electrospray echnique for producing nanoparticles
, Article 26th Iranian Conference on Electrical Engineering, ICEE 2018, 8 May 2018 through 10 May 2018 ; 2018 , Pages 283-288 ; 9781538649169 (ISBN) ; Naghibi Nasab, J ; Elyasi, M ; Zarrabi, R ; Vosoghi, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
Electrospray technique is one of the commonly used methods for generating nanoparticles. In this method, the chemical solution which consists of a polymer and its solvent are injected into an electric field via a nozzle. At the end of this nozzle, due to electric forces, a certain part of this liquid is separated. Then, the separated part is divided into smaller particles and the solvent is evaporated and hence, the nanoparticles are acquired. Produced nanoparticales are collected in deionized water placed under the certain distant from nozzle. However, construction of this method is generally based on practical results. In this paper, modeling and performance evaluation of high voltage...
Investigations on equivalent circuit models of high frequency transformers
, Article Proceedings of 2018 IEEE International Conference on Power Electronics, Drives and Energy Systems, PEDES 2018 ; Volume 2018-January , April , 2018 , Pages 475-480 ; 9781538646977 (ISBN) ; Naghibi Nasab, J ; Aghaei, M ; Kaboli, S ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
High frequency transformer is an important component in lots of modern power electronic circuits. In order to analyze the behavior of these transformers, equivalent circuit models containing parasitic elements have been proposed. But most of them are complicated and not appropriate to use in processes in which high speed analysis is crucial. In this paper, a second-order simplified model for high frequency transformers is obtained. Besides, the frequency ranges in which the proposed model has enough precision, are calculated and examined. To validate the simplified circuit model, some simulations are carried out. During the simulation, the effects of transformer equivalent circuit parameters...
Synthesis and optimization of CuxNi0.6-xMn0.4Fe2O4 oxygen carrier for chemical looping steam methane reforming
, Article Energy Sources, Part A: Recovery, Utilization and Environmental Effects ; 2021 ; 15567036 (ISSN) ; Heydari Nasab, A ; Soltanieh, M ; Maddah, B ; Sharif University of Technology
Bellwether Publishing, Ltd
2021
Abstract
The self-supported CuxNi0.6-xMn0.4Fe2O4 oxygen carrier (x = 0.1–0.5) is synthesized to be applied in the chemical looping steam methane reforming (CL-SMR) process through the synthesized co-precipitation method. The response surface methodology (RSM) based on the Box–Behnken model is adopted to evaluate the effects of independent variables on the functionality of responses as well as predicting the best response volume. In this method, the variables consisting of reaction temperature (550–700°C), oxygen carrier (OC) loading percentage (0.1–0.5), steam-to-CH4 ratio (S/C), (1.5–3.5), and redox cycles’ count (10–24) and the responses consisting of hydrogen (H2) production yield, CH4 conversion...
Reliability maximization in uncertain graphs
, Article IEEE Transactions on Knowledge and Data Engineering ; Volume 34, Issue 2 , 2022 , Pages 894-913 ; 10414347 (ISSN) ; Khan, A ; Al Hasan, M ; Rezvansangsari, R ; Sharif University of Technology
IEEE Computer Society
2022
Abstract
Network reliability measures the probability that a target node is reachable from a source node in an uncertain graph, i.e., a graph where every edge is associated with a probability of existence. In this paper, we investigate the novel and fundamental problem of adding a small number of edges in the uncertain network for maximizing the reliability between a given pair of nodes. We study the mathbf {NP}NP-hardness and the approximation hardness of our problem, and design effective, scalable solutions. Furthermore, we consider extended versions of our problem (e.g., multiple source and target nodes can be provided as input) to support and demonstrate a wider family of queries and...
Investigation of counterflow microchannel heat exchanger with hybrid nanoparticles and pcm suspension as a coolant
, Article Mathematical Problems in Engineering ; Volume 2021 , 2021 ; 1024123X (ISSN) ; Khafeef, M. J ; Mohammadi, O ; Bhattacharyya, S ; Issakhov, A ; Sharif University of Technology
Hindawi Limited
2021
Abstract
The effect of the hybrid suspension on the intrinsic characteristics of microencapsulated phase change material (MEPCM) slurry used as a coolant in counterflow microchannel heat exchanger (CFMCHE) with different velocities is investigated numerically. The working fluid used in this paper is a hybrid suspension consisting of nanoparticles and MEPCM particles, in which the particles are suspended in pure water as a base fluid. Two types of hybrid suspension are used (Al2O3 +MEPCM and Cu + MEPCM), and the hydrodynamic and thermal characteristics of these suspensions flowing in a CFMCHE are numerically investigated. The results indicated that using hybrid suspension with high flow velocities...
Optimization of microbial culture for production of poly hydroxy butyrate (PHB) by azotobacter beijerinckii DSMZ-1041
, Article World Applied Sciences Journal ; Volume 14, Issue SPL ISS 3 , 2011 , Pages 72-82 ; 18184952 (ISSN) ; Ardjmand, M ; Nasab, A. H ; Kordi, A. S ; Sharif University of Technology
2011
Abstract
Azotobacter beijerinckii DSMZ 1041 strain was used for production of polyhydroxybutyrate (PHB) and the optimum glucose concentration, as the carbon source and ammonium chloride, as the nitrogen source were obtained 60gr/lit and 0.5gr/lit respectively. The resulting optimum PHB production was investigated 2.95gr/lit. The obtained yield of PHB with respect to glucose (Yp/s) and PHB productivity (Qp) were 0.202 g/g and 0.123 g/lit.hr, respectively. The response surface methodology (RSM) was used to verify the accuracy of the designed experiments. azotobacter beijerinckii microorganism from Deutsch sammlung von microorganismen und zellkulturen(DSMZ) bank is used for production of Poly Hydroxy...
Integrated Pricing and Queuing Problem
, M.Sc. Thesis Sharif University of Technology ; Shavandi, Hasan (Supervisor)
Abstract
Joint price and service capacity decisions and integrated pricing and queuing problems with finite or infinite buffers are two remarkable issues of pricing research. In this thesis we consider a joint price and service capacity determination problem in a single server, finite buffer queuing system. Customers arrival and serving occur as Poisson processes. Because of finite buffer capacity, customers finding the system full upon their arrival would be rejected. Customers differ with respect to their reservation prices and time sensitivities. This study focuses on investigating the effect of finite buffer capacity and customers reservation prices and time sensitivities on optimal policy and...
Application of Pricing in Flowshop Scheduling
, M.Sc. Thesis Sharif University of Technology ; Shavandi, Hasan (Supervisor)
Abstract
This research considers coordination of pricing and scheduling decisions in a make-to-order environment. We consider a two machine flowshop environment. The objective is to maximize the total net profit, i.e. revenue minus scheduling cost resulting from pricing and scheduling decisions. Prices of orders are set by the manufacturer and demand is a non-increasing function of price. Two mixed integer linear programming models have been developed for the research problem. As the problem is shown to be NP-Hard, a Metaheuristic algorithm is developed which is combination of two tabu search sub algorithms, one for pricing and the other for scheduling. And to evaluate performance, results from...
On The Non-Linear Behavior of Continuous Beam to Column Connection
, M.Sc. Thesis Sharif University of Technology ; Moghadam, Hasan (Supervisor)
Abstract
A special steel beam-to-column connection, named Khor-jini, is commonly used for steel framing system in Iran. In this system, two continuous beams are passed next to the columns and are connected to the column side using seated brackets.This type of connection has been common in Iran from the late past. Unfortunately, the seismic behavior of Khorjini frames had not been sufficiently studied prior to Manjil Earthquake of 1990. Due to very large damages which occurred in steel structures especially in connections during the said earthquake, the seismic behavior of this type of connection was studied and some of its weak points were recognized.In this study non-linear...
Geometrical Optimization of Traction Infinitely Variable Transmission for Minimizing of Rollers Deformation
, M.Sc. Thesis Sharif University of Technology ; Zohoor, Hasan (Supervisor)
Abstract
With intensified concerns of rising fuel vehicles that reduce fossil fuel globally and also prescript strict rules by standard institutes, vehicle manufacturers try to find a way for reducing the fuel of their products. One these methods use a continuously variable transmission (CVT) instead of manual and automatic gearboxes. Various CVT’s have been proposed in recent year.
One of the proposed systems is traction infinitely variable transmission (TIVT) that is type of traction drive continuously variable transmission and has been presented in 2007. Research on this system showed that average efficiency is about 96% that is high efficiency. Completed research in 2011 showed that despite...
One of the proposed systems is traction infinitely variable transmission (TIVT) that is type of traction drive continuously variable transmission and has been presented in 2007. Research on this system showed that average efficiency is about 96% that is high efficiency. Completed research in 2011 showed that despite...
Distribution Problem in Heterogeneous Networks with the Assumption of Flexibility in the Delivery of Goods
, M.Sc. Thesis Sharif University of Technology ; Shavandi, Hasan (Supervisor)
Abstract
In this research, we consider a network of distiribution channels and a central warehouse to deliver the products to distribution centers. We assume the price of products are fixed and the central warehouse is authorized to change the delivery amount for each DC in a reasonable interval. The main idea is authorizing the central warehouse to be flexible in delivery of ordered amounts of DCs in a reasonable interval in order to reduce the transportation cost and then maximizing the profit.
The problem is formulated as a linear integer programming model and the properties of optimal solution is analyzed. Based on the properties of the model a solution algorithm is developed to solve the...
The problem is formulated as a linear integer programming model and the properties of optimal solution is analyzed. Based on the properties of the model a solution algorithm is developed to solve the...
A Marx-based generator with adjustable FWHM using a controllable magnetic switch
, Article IEEE Transactions on Dielectrics and Electrical Insulation ; Volume 26, Issue 2 , 2019 , Pages 324-331 ; 10709878 (ISSN) ; Hadizade, A ; Mohsenzade, S ; Zarghany, M ; Kaboli, S ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
The lack of turn-off ability makes the spark gap-based Marx generator uncontrollable in terminating the output pulse. In addition, there are some limitations for rise time and voltage gain improvements in the conventional critically-damped Marx design. In this paper, an efficient over-damped design of Marx circuit is proposed, which leads to a shorter rise time as well as a larger voltage gain. A chopping magnetic switch is employed to achieve the desired values of the fall time and full width at half maximum (FWHM). Moreover, adding a DC bias circuit to the magnetic switch provides the ability to adjust the pulse FWHM parameter. Therefore, an output pulse with a shorter rise time, larger...