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How particle shape affects the flow through granular materials
, Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 85, Issue 3 , 2012 ; 15393755 (ISSN) ; Ahmadi, M. M ; Mohammadi, S
2012
Abstract
Flow through the pores of granular materials has many instances in practice. Therefore, it is interesting to realize how some parameters, such as the shape of the particles affect the passing flow. Following the recent mathematical theory proposed by the authors, this paper deals with the issue of how tortuosity and permeability are influenced by the particle shape. Comparison of the results with the experimental data reveals the competency of the theory in predicting the impact of particle geometry
Some Applications of Graph Theory Inarchitectural Design
, M.Sc. Thesis Sharif University of Technology ; Mahmoodian, Ebadollah (Supervisor)
Abstract
One of the fields, in which graph theory and computer science have been appleid,is architectural design. Some of these applications are presented in this thesis. This thesis has two parts, the first part peresents a systematic pathway for design of a floor plan when given the list of cells, the required dimensions of each cell and the matrix of required adjacencies between the cells. (Based on the article by Hashimshony(1988)) The second part is about the application of Evolutionary Algorithm (EA) in ar-chitucture. The architectural layout design problems, which is concerned with the finding of the best adjacencies between functional spaces among many possible ones under given constraints,...
Tracking Consumers Throughout Their Purchase Journey: Using Deep Learning Methods
, M.Sc. Thesis Sharif University of Technology ; Aslani, Shirin (Supervisor)
Abstract
Over the past two decades, the interest in exploring consumers' behavior has risen to popularity. Nowadays, it is necessary for marketers to reach out to the right consumers at the right time and with the right message. Even though the positive impact of tracking consumers throughout their purchase journey and its managerial implications have been emphasized several times by academics, There is still a lack of practical research on how to discern the consumers' stage in the purchase journey from a holistic point of view. In this study, we develop several machine learning models, including RNNs (GRU and LSTM), Transformers, and XGBoost, by utilizing historical data of Yektanet (the leading...
The Role of Oil Price Shocks in Bussiness Cycles of an Oil-Exporting Country: Facts from Iran with a General Equillibrium Approach
, M.Sc. Thesis Sharif University of Technology ; Madanizadeh, Ali (Supervisor)
Abstract
In this research, we develop a Real Business Cycle model for Iran, as Small Open Economy. In this model, which is designed to measure the role of oil price shocks in Iran’s business cycles, the positive oil price shocks, as well as increasing the revenue of exporting oil, raises the price of oil-based tradable goods. Additionally, it causes the fiscal policy variables (taxes and government expenditures) to change. Also the productivity of this economy is fluctuated by oil price fluctuations. The model is estimated via Impulse Response Function Matching method using a SVAR model as the auxiliary model. The results from the theoretical model show that near 50 percent of non-oil GDP cycles and...
Cloning and Production of the Flavin Reductase Enzyme in Order to Perform Organic Reaction and Synthesis of Cation Exchange Column for Protein Purification
, M.Sc. Thesis Sharif University of Technology ; Kalhor, Hamid Reza (Supervisor)
Abstract
The reductase enzymes perform an important function in the cell. These enzymes are usually coupled with other enzymes and participate in reactions such as halogenation, reduction of alkene, and carboxylic acids. These reactions are carried out by reproducing cofactors such as FADH2 and NAD+; however, there is no evidence that this enzyme alone can perform an organic reaction. In this work, we aim to examine whether recombinant flavin reductase can carry out organic reactions. In order to amplify the flavin reductase enzyme gene from the E. coli genome by PCR (Polymerase Chain Reaction) method, two synthetic primers were designed; The forward primer of the gene contained a cleavage site for...
3d Design of a Microfluidic Chip for Anticancer Drugs Screening
, M.Sc. Thesis Sharif University of Technology ; Mashayekhan, Shohreh (Supervisor) ; Saadatmand, Maryam (Supervisor)
Abstract
Nowadays, advanced and inexpensive pre-clinical methods for investigating the effects of anti-cancer drugs are expanding. One of the latest three-dimensional laboratory modeling for evaluating the effects of drugs is the use of tumor-on-chip technology, which actually models the physiological system of the body through three-dimensional scaffolds, multicellular cultures, and shaped vascular systems. In this study, three-dimensional culture of cancer cells was performed in the form of spheroids. A chip of U-shaped microstructures with and without gaps was used to trap cells and form cancer spheroids. We simulated the simultaneous effect of drug and oxygen concentration distribution inside the...
Energy-efficient relay selection and power allocation for multi-source multicast network-coded D2D communications
, Article AEU - International Journal of Electronics and Communications ; Volume 128 , 2021 ; 14348411 (ISSN) ; Kalbkhani, H ; Shayesteh, M. G ; Sharif University of Technology
Elsevier GmbH
2021
Abstract
Device-to-device (D2D) communication improves spectrum efficiency (SE) and increases system capacity. Heterogeneous networks comprise macrocell and several small cells, such as picocells and femtocells, where femtocells are more efficient. In cooperative communications, one or several additional nodes help to send data from source to destination to improve the quality of service (QoS). Network coding (NC) in cooperative networks can extend data rate and coverage area of D2D communication. The purpose of this article is to minimize power consumption of transmitting nodes during network-coded cooperative D2D transmission to reduce the interference on co-channel transmissions. In this study, we...
Developing and enhancing promiscuous activity for NAD(P)H-dependent flavin reductase via elimination of cofactor
, Article Heliyon ; Volume 9, Issue 9 , 2023 ; 24058440 (ISSN) ; Kalhor, H. R ; Hayati, F ; Sharif University of Technology
Elsevier Ltd
2023
Abstract
Promiscuous enzymes have shown their synthetic abilities in generating various organic compounds with high selectively and efficiency under mild conditions. Therefore, the design and development of conditions to raise promiscuity to the enzymes have been under the spotlight in recent years. Flavin reductase, that reduces flavins by using NADH as a cofactor, has not been studied in promiscuous reactions. In the present study, it was aimed to develop a catalytic promiscuous activity in the recombinant E. coli flavin reductase by removing its cofactor. The flavin reductase demonstrated a promiscuous activity for Knoevenagel condensation and Michael addition reactions individually. The...
Optimization Models for Financial Portfolio Problem
, M.Sc. Thesis Sharif University of Technology ; Mahdavi Amiri, Nezameddin (Supervisor)
Abstract
In financial portfolio problem, optimization models with uncertainty has been considered. The multi-stage stochastic programming methodology has been used as a solution method for these problems. In this study, we use multi-stage programming with uncertainity to evaluate the asset allocation problem. Some general models have been introduced for problem solving. Non-anticipativity and parent-child models are implemented and solved by both simplex and interior-point methods and the results are compared. The results show the parent-child model to have a better performance. Also, the interior-point method appears to need less computing time than the simplex method
Analytical derivation of tortuosity and permeability of monosized spheres: A volume averaging approach
, Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 83, Issue 2 , February , 2011 ; 15393755 (ISSN) ; Mohammadi, S ; Hayati, A. N ; Sharif University of Technology
2011
Abstract
Macroscopic properties of granular materials are important in modeling a variety of flow and transport phenomena in many fields of science. Determination of these parameters has always been an issue among both researchers and engineers, mainly in view of tortuosity and permeability. This paper presents analytical functions for the tortuosity and permeability of monosized sphere arrays based on a volume averaging approach and eliminates some ambiguities by modification of the original representative elementary volume model. Veracity of the proposed formulations has been illustrated through comparisons with the latest available results on the subject. Good agreement is found
Analytical Solution for Isothermal Flow in a Shock Tube Containing Rigid Granular Material
, Article Transport in Porous Media ; Volume 93, Issue 1 , 2012 , Pages 13-27 ; 01693913 (ISSN) ; Ahmadi, M. M ; Mohammadi, S ; Sharif University of Technology
2012
Abstract
Analytical solution of shock wave propagation in pure gas in a shock tube is usually addressed in gas dynamics. However, such a solution for granular media is complex due to the inclusion of parameters relating to particles configuration within the medium, which affect the balance equations. In this article, an analytical solution for isothermal shock wave propagation in an isotropic homogenous rigid granular material is presented, and a closed-form solution is obtained for the case of weak shock waves. Fluid mass and momentum equations are first written in wave and (mathematical) non-conservation forms. Afterwards by redefining the sound speed of the gas flowing inside the pores, an...
Simulation of a 10000 bbl/day G.T.L. plant
, Article 18th International Congress of Chemical and Process Engineering, CHISA 2008, Prague, 24 August 2008 through 28 August 2008 ; 2008 ; Gholamtamimi, M ; Hayati, R ; Sobati, M. A ; Sharif University of Technology
2008
Abstract
Gas-to-Liquid (GTL) is a multi-staged process in which natural gas is converted to liquid fuels. The stages of GTL process are discussed. A GTL plant with 10,000 bpd capacity and have similar specifications with the SASOL process was simulated using the Aspen-Plus software and the simulation results were compared with the SASOL process data. This is an abstract of a paper presented at the 18th International Congress of Chemical and Process Engineering (Prague, Czech Republic 8/24-28/2008)
Model Checking of Stochastic Activity Networks
, M.Sc. Thesis Sharif University of Technology ; Movaghar, Ali (Supervisor)
Abstract
Modeling and performance evaluation of the real time distributed systems is a significant problem. Stochastic activity network is one of the high level models used for this purpose. This network is an extension of generalized stochastic Petri net which is more powerful and flexible than other Petri net extensions. Checking the satisfiability of properties such as performance, dependability and user's expected properties is considerable in these models. Thus, using the approaches and generating modeling and model checking tools with the mentioned purpose is attractive. A model checker automatically checks the correctness of the system behaviors as properties against the model by getting the...
Robust Estimation and Control of a Planet Lander
, M.Sc. Thesis Sharif University of Technology ; Kiani, Maryam (Supervisor)
Abstract
This study has focused on the important problem of landing on a planet as an important current and future space mission. In this regard, dynamics modeling and integrated state estimation and control problems have been investigated in different views. To this aim, first a novel concurrent representation for translational and rotational kinematics has been developed based on the extension of modified Rodrigues parameters to dual space. This parameter set, called dual modified Rodrigues parameters (DMRP), is then utilized to establish an integrated roto-translational dynamic. The proposed DMRP-based kinematics and dynamics have been verified via comparison to traditional methods of...
Optimal Energy Trading in a Smart Grid Based on Extremum-seeking Algorithm
, M.Sc. Thesis Sharif University of Technology ; Babazadeh, Maryam (Supervisor)
Abstract
Prevalent deployment of Distributed Energy Resources(DERs) in the demand side of electrical energy grids has several advantages such as greenhouse gases emission reduction, mitigation of power losses in the distribution grids and abatement of the dependency on the wholesale generation companies. At the same time, it paves the way for the advent of local interactive energy trading frameworks. In the following thesis, a distributed data-driven algorithm is developed for market-clearing in a community-based local energy market. The social welfare maximization is considered as the objective of the energy trading. The production and demand of electricity are the decision variables of sellers and...
Design of Microfluidic Chip for 3D Cell Culture
, M.Sc. Thesis Sharif University of Technology ; Saadatmand, Maryam (Supervisor)
Abstract
Understanding biological systems requires extensive knowledge of individual parameters, and to study the processes of cell differentiation and cell behavior, a suitable environment must be created with the physiological conditions of the human body. For this purpose, with the knowledge of microfluidics, a microenvironment can be provided to study the behavior of cells on a small scale. The use of bone tissue model microfluidic chips is an alternative and new method in which it is possible to study the behavior of cells to differentiate into bone and to examine the toxicity of drugs, which in itself can help in the effective and successful treatment of these cases show. Therefore, in this...
Navigation and Control of a Free-Flying Satellite for Cargo Transportation and Placement in Intra-Vehicular Environment
, M.Sc. Thesis Sharif University of Technology ; Kiani, Maryam (Supervisor)
Abstract
The main topic of this research is the navigation and control of a free-flying satellite with a robot manipulator while transferring and placing cargo on a space station. After connecting the cargo module, astronauts and robots need to deliver the available loads to the desired modules in a space station. Capturing an object or cargo is a critical issue studied extensively so far. However, delivery and placing of the cargo at the target point have not been investigated yet, to the best of the author’s knowledge; hence, this is a primary motivation for conducting the proposed research. After capturing the payload, the position and attitude of the manipulator with respect to the station’s...
Fabrication the Hydrogel Microfibers Using Bioprinter with Application in Cardiovascular Model
, M.Sc. Thesis Sharif University of Technology ; Saadatmand, Maryam (Supervisor)
Abstract
Cardiovascular disease (CVD) currently remains a considerable challenge for clinical treatments. CVDs account for N17.5 million deaths per year and will predictably increase to 23.6 million by 2030. The main purpose is to create human model systems to study the effect of disease mutations or drug treatment on the heart. In addition, engineered cardiac tissues are considered promising candidates to be transplanted to improve the function of diseased hearts. For engineered active tissues/organs, 3D bioprinting can fabricate complex tissue architecture with a spatiotemporal distribution of bioactive substances (cells, growth factors, and others) to better guide tissue regeneration. However,...
Utilizing Gaussian Processes to Learn Dynamics of Unknown Torques Acting on a Spacecraft
, M.Sc. Thesis Sharif University of Technology ; Kiani, Maryam (Supervisor)
Abstract
Accurate and fast attitude estimation of a rigid body plays an essential role in the performance of a vehicle’s control system, especially aerospace vehicles. Ample works have been done to increase the accuracy and speed of the attitude estimation process, but all have been developed according to a model-based approach. This approach assumes that the torques acting on the body have a known dynamical model that is used for the attitude estimation. The purpose of the present research is to estimate the attitude via a model-free approach, i. e. dynamics of the torques acting on the body are no longer assumed to be known, and its learning is the next step. Thus, the problem formulation of this...
Stabilization and Pole-Placement by Structurally-Constrained Controllers: A Graph-Theoretic Approach
, M.Sc. Thesis Sharif University of Technology ; Babazadeh, Maryam (Supervisor)
Abstract
This thesis presents a new approach to design structural output feedback controllers with stabilization and pole-placement at desired points on the S plane. It is assumed that the linear time-invariant system has no fixed mode corresponding to the specified control structure, outside the desired region of the closed-loop poles, such that the structural controller design problem is theoretically feasible. To this end, the structural output controller design problem is first transformed into a structurally equivalent problem based on the solution of a set of discrete linear programs. Then, by using the resultant structure, a new method is proposed for designing static and dynamic control loops...