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Experimental Investigation and CFD Simulation of the Flow Pattern of the FCC's Fluidized Bed Regenerator

, M.Sc. Thesis Sharif University of Technology Azarnivand, Abbas (Author) ; Dehkordi, Asghar Molaei (Supervisor) ; Seifkordi, Aliakbar (Supervisor) ; Behjat, Yaghoub (Supervisor)

Abstract

Hydrodynamic behavior of gas-solid fluidization in large-diameter beds like FCC regenerator exhibits complex aspects. To investigate the gas-solid flow pattern of UOP's combustor-style FCC regenerator, a lab-scale regenerator was designed by a downscale factor of 0.045. The regenerator's operation and fluidization of FCC particles through it was examined and pressure axial distributions were measured and analyzed at different superficial air velocities. 3D CFD simulation of the regenerator was performed with Eulerian-Eulerian approach to investigate the effects of operating conditions, including superficial air velocity, catalyst mass flux, presence of recirculated catalyst, and the...

Total completion time minimisation of no-wait flowshop group scheduling problem with sequence dependent setup times

, Article European Journal of Industrial Engineering ; Volume 11, Issue 1 , 2017 , Pages 22-48 ; 17515254 (ISSN) Behjat, S ; Salmasi, N ; Sharif University of Technology

Inderscience Enterprises Ltd 2017

Abstract

In this research, the no-wait flowshop sequence dependent group scheduling problem with minimisation of total completion time, noted as Fm|nwt, fmls, Splk|∑Cj is approached. A mixed integer linear mathematical model is proposed for the research problem. Due to the NP-hard nature of the proposed problem, several metaheuristic algorithms based on particle swarm optimisation and variable neighbourhood search with different neighbourhood search structures are proposed to heuristically solve the problem. Also, an efficient heuristic algorithm is proposed to generate the initial feasible solutions for the proposed algorithms. The performances of the proposed algorithms are compared with each other...

Group Scheduling on Flow Shop with Sequence Dependent Setup Times and no Wait Assumption

, M.Sc. Thesis Sharif University of Technology Behjat, Saeed (Author) ; Salmasi, Naser (Supervisor)

Abstract

The present thesis is focused upon the flow shop sequence dependent group scheduling problem (FSDGS) with no wait assumption. Generally, production sequencing and scheduling is considered as one of the most important factors in productivity and cost saving of organizations. Therefore, determining an appropriate sequencing of groups and jobs according to the logical constraints is expected to improve the performance and productivity of the production system.
In this thesis, due to the importance and multiple applications of this problem, we will consider the FSDGS problem and propose new heuristic and metaheuristic algorithms to tackle this problem. Since the good performance of...

Praparation of Nanometric Platinum Coatings on Carbon Substrate (Pt/C) for Catalytic Plates of Fuel Cells

, M.Sc. Thesis Sharif University of Technology Behjat, Saeed (Author) ; Ghorbani , Mohammad (Supervisor) ; Afshar, Abdollah (Supervisor)

Abstract

With increasing pollution and decrease in global reservoirs of fossil fuels, a lot of interest has been attracted to fuel cells as efficient and clean energy sources. Polymeric (membrane) fuel cells are special type of fuel cells, which can be built in small dimensions and power. These cells use hydrogen (and oxygen or air) and produce water. In these cells, platinum is used as electrode (and electrocatalyst) both in anode and cathode, due to its low overvoltage for both hydrogen and oxygen. To increase the efficiency of these coatings, it is best to produce platinum particles with maximum area and it automatically leads to nanometric particles. In this thesis, platinum particles are...

Design and Fabrication of a Balance Training Apparatus

, M.Sc. Thesis Sharif University of Technology Behjat, Amir (Author) ; Behzadipour, Saeed (Supervisor) ; Farahmand, Farzam (Co-Advisor)

Abstract

One of the main reasons of being unable in doing routine jobs is the disability to attain and keep balance. This ability can be restored using rehabilitation techniques. A physiotherapist can be very helpful. This approach, however, apart from being very time consuming and expensive, needs quite a few physiotherapists. The physiotherapist will be prone to physical damages as well. This leads to improving therapy methods which do not require a physiotherapist. Using the rehabilitation balance devices can help solve the problem to some extents. If good device with reliable value system be developed, this device can be used without physiotherapist.
This project has been carried out to...

Stochastic nature of series of waiting times

, Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 87, Issue 6 , 2013 ; 15393755 (ISSN) Anvari, M ; Aghamohammadi, C ; Dashti Naserabadi, H ; Salehi, E ; Behjat, E ; Qorbani, M ; Khazaei Nezhad, M ; Zirak, M ; Hadjihosseini, A ; Peinke, J ; Tabar, M. R. R ; Sharif University of Technology

2013

Abstract

Although fluctuations in the waiting time series have been studied for a long time, some important issues such as its long-range memory and its stochastic features in the presence of nonstationarity have so far remained unstudied. Here we find that the "waiting times" series for a given increment level have long-range correlations with Hurst exponents belonging to the interval 1/2