Investigation of Dropwise Condensation on Nanostructured Superhydrophobic Surfaces using Molecular Dynamics Simulation

, M.Sc. Thesis Sharif University of Technology Alborzi, Saeed (Author) ; Moosavi, Ali (Supervisor)

Abstract

Phase change processes have been used in heat transfer industries for decades. However, the heat transfer rate enhancement of the surfaces is still a challenging issue for the researchers. In this path, emerging nanostructured surfaces have shown great potentials. We demonstrate that using nanostructured surfaces in the condensation processes enhances the heat transfer behaviour of the fluid through interfacial contact area increase. In the present study molecular dynamics simulation have been employed to monitor the atomic behaviour of the system components at nanoscale. The argon liquid is considered as the working fluid and the copper surfaces as the phase change site. The effect of...

Experimental investigation of on-demand ferrofluid droplet generation in microfluidics using a Pulse-Width Modulation magnetic field with proposed correlation

, Article Sensors and Actuators, B: Chemical ; Volume 329 , 2021 ; 09254005 (ISSN) Bijarchi, M. A ; Favakeh, A ; Alborzi, S ; Shafii, M. B ; Sharif University of Technology

Elsevier B.V 2021

Abstract

Micro-magnetofluidics offers a promising tool to regulate the drop formation process with versatile applications in engineering and biomedicine. In the present study, on-demand ferrofluid drop generation at a T-junction is investigated utilizing a magnetic pulse. Also, a novel method for ferrofluid droplet formation is introduced using a non-uniform Pulse-Width Modulation (PWM) magnetic field. A novel mechanism of drop generation named “beating regime” was seen for the first time in which the ferrofluid moves back and forth before the breakup. The effect of the magnetic induction, continuous phase flow rate, duty cycle, and applied frequency on the generation frequency and drop diameter was...

P-V-L Deep: A big data analytics solution for now-casting in monetary policy

, Article Journal of Information Technology Management ; Volume 12, Issue 4 , 2021 , Pages 22-62 ; 20085893 (ISSN) Sarduie, M. H ; Kazemi, M. A ; Alborzi, M ; Azar, A ; Kermanshah, A ; Sharif University of Technology

University of Tehran 2021

Abstract

The development of new technologies has confronted the entire domain of science and industry with issues of big data's scalability as well as its integration with the purpose of forecasting analytics in its life cycle. In predictive analytics, the forecast of near-future and recent past - or in other words, the now-casting - is the continuous study of real-time events and constantly updated where it considers eventuality. So, it is necessary to consider the highly data-driven technologies and to use new methods of analysis, like machine learning and visualization tools, with the ability of interaction and connection to different data resources with varieties of data regarding the type of big...

Performance of three-level spectrally encoded spreadtime CDMA in the presence of multiple interferences [electronic resource]

, Article IET Communications ; July 2011, Volume 5, Issue 10, P. 1328-1335 Mashhadi, S. (Saeed) ; Mashhadi, Saeed ; Salehi, J. A ; Sharif University of Technology

Abstract

In this study the authors present an in-depth study, analysis and discussion on maximum likelihood (ML)-based receiver for a typical spectrally encoded spread-time CDMA in the presence of multiple narrowband interference (NBI) signals in an additive white Gaussian noise channel. Furthermore, the authors demonstrate that by combining useful properties of ML-based receiver and three-level codes, that is, codes with values of -1, 0, +1, the authors can introduce a new strategy in which superior performance with respect to previous receiver structure based on two-level codes, that is, codes with values of -1, +1, can be attained. With the help of an example, the authors drive, first, the...

Investigation of Multiphase Flow in Oil Wells (with Focus on Two Phase Flow), Flow Pattern Recognition and Modeling

, M.Sc. Thesis Sharif University of Technology Shams, Reza (Author) ; Shad, Saeed (Supervisor) ; Jamshidi, Saeed (Supervisor)

Abstract

The concurrent flow of oil and water is a common occurrence in the field of multiphase flow in different fields including petroleum industry. In oil and gas, production engineers often face a situation in which more than one phase is flowing through the producers. In such conditions an accurate assessment of pressure loss inside the well plays a vital role in efficient and effective production planning. Changes in well orientation, wellbore diameter, reservoir and fluid properties as well as fluid flow rates are among parameters in which will affect the flow patterns that can occur inside a well during its life time. These flow patterns are created as a result of a competition between...

Casing Design Optimization Considering Drilling and Production Conditions

, M.Sc. Thesis Sharif University of Technology Sadeghi, Mahdi (Author) ; Jamshidi, Saeed (Supervisor) ; Shad, Saeed (Supervisor)

Abstract

Casing design is one of the most expensive parts in the drilling of oil wells, and any cost reduction with the basic design of these casing strings will significantly reduce the total cost of the operation. In recent years, occurring scenarios-based casing design has become popular; Because in many cases, it eliminates non-occurring scenarios such as gas kick and saves on drilling costs. In this study, we have tried to investigate all scenarios that may occur during the lifetime of the well, whether drilling or production, and for each well, based on its own field information, possible scenarios for each casing part are selected separately and the applying loads are calculated. For this...

PRI (Palm Rotation Indicator): a metric for postural stability in dynamic nonprehensile manipulation [electronic resource]

, Article Journal of MECHANIKA ; 2012, Vol. 18, No. 4, pp. 461-466 Beigzadeh, B. (Borhan) ; Meghdar, Ali ; Sohrabpour, Saeed ; Sharif University of Technology

Abstract

In this study, we discuss the postural stability of a nonprehensile manipulation problem, which deals with multibody objects. As a metric for postural stability, we define PRI. Then, the system is posturally stable, if PRI is inside the convex hull of the object-manipulator contact surface. We then discuss that dynamic biped locomotion is a special case of dynamic nonprehensile manipulation in all aspects; we prove that ZMP (zero-moment point) and FRI (zoot rotation indicator) are special cases of PRI (palm rotation indicator). Simulations and experiments corresponding to simple examples support the results

On the Domination Polynomial of Graphs

, M.Sc. Thesis Sharif University of Technology Ebrahimi, Zeinab (Author) ; Akbari, Saeed (Supervisor)

Some Applications of Combinatorial Nullstellensatz in Graph Theory and Combinatorics

, M.Sc. Thesis Sharif University of Technology Fakhari, Amin (Author) ; Akbari, Saeed (Supervisor)

Electrochemical Determination of Piroxicam at thin Carbon
Nanoparticle Composite And Investigation of the Electrochemical Behavior and Synthesis of Catechols in the Presence of Mercapto Methyl Tetrazol as a Nucleophile

, M.Sc. Thesis Sharif University of Technology Jokar, Effat (Author) ; Shahrokhian, Saeed (Supervisor)

Abstract

The electrochemical oxidation behavior of the anti-inflammatory drug piroxicam was investigated. A carbon nanoparticle (CNP)-chitosan (CS) film-coated graphite electrode (PGE) was fabricated and the electrochemical behaviors of piroxicam on its surface was investigated by the means of cyclic voltammetry (CV), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). In comparison to the bare PGE, at the surface of the CNP-CS film modified electrode, the oxidation peak current of piroxicam increased significantly and the peak potential shifted negatively. Consequently, a simple and sensitive electroanalytical method was developed for the determination of piroxicam. The...

Chemically Modified Electrodes Based on Conducting Polymers and Carbon Nanotubes: Application to Voltammetric Determination of Some Biological and Pharmaceutical Compounds

, M.Sc. Thesis Sharif University of Technology Asadian, Elham (Author) ; Shahrokhian, Saeed (Supervisor)

Abstract

There are high attractions in the development of conducting polymer (CP) coatings to improve the electrochemical properties and biocompatibility of electrodes in the area of biosensors. In the first part of this thesis, a new type of modified electrodes, constructing multi-walled carbon nanotubes (MWCNTs) and polypyrrole is prepared in a layer-by-layer process. In this procedure, the glassy carbon electrode is casted first by a drop suspension of MWCNTs, leading to formation a thin film on its surface. In the second step, electrochemical polymerization of pyrrole in the presence of tiron (used as doping anion) is performed on the surface of the MWCNTs pre-coated electrode. The modification...

Probing the Electrochemical Properties of Gold Electrode Modified with Edge-Functionalized Graphene and its Application

, M.Sc. Thesis Sharif University of Technology Aghajani, Talin (Author) ; Shahrokhian, Saeed (Supervisor)

Abstract

In the present work, edge-functionalaized graphene was used as electrode material and its electrochemical properties were systematically characterized by electrochemical impedance spectroscopy and cyclic voltammetry. Two methods were applied to modify the gold electrode surface. First method was the self assembling process of graphene nanosheets on gold electrode surface. Second method was simply casting specific amounts of graphene suspension on the gold electrode surface. Nyquist plots show decrease of the charge transfer resistance on the electrode surface at both cases. In cyclic voltammetry studies, first electrode shows no significant changes while the second electrode exhibits...

Probabilistic Methods in Graph Coloring

, M.Sc. Thesis Sharif University of Technology Ahadi, Arash (Author) ; Akbari, Saeed (Supervisor)

Abstract

Graph Theory and Combinatorial Analysis like the other branches of science use the probability for solving their problems. At the first , we will introduce the most common tools from probability used in Discrete Mathematics, such as “The Lovasz Local Lemma”. Most of them are based on Linearity of Expectation, Concentration Theorems and some other innovative methods such as Deletation Method. We will present different examples for these techniques. Also we will introduce “Random Graphs” and their importance. Specially we will explain how to use “Threshold Functions” to obtain different properties about the majority of graphs. Rainbow Connection, is a natural and interesting quantifiable way...

Electrochemical Determination of Tyrosine and Tryptophan at the Surface of Pyrolytic Graphite Electrode Modified with Multi-Walled Carbon Nanotubes, New Coccine and Nitrazine

, M.Sc. Thesis Sharif University of Technology Ebrahimi, Shiva (Author) ; Shahrokhian, Saeed (Supervisor)

Abstract

At the first part of this thesis, a pyrolitic graphite electrode (PGE) modified with new coccine/multi-walled carbon nanotubes film (NC/MWCNT) was applied as a sensitive electrochemical sensor for determination and study of electrochemical behavior of tyrosine (Tyr) in aqueous solutions. The results showed that NC/MWCNT caused a remarkable increase in the peak current so the NC/MWCNT/PGE electrode surface was far more sensitive to the concentration of Tyr than the PGE surface. The determination of Tyr was investigated by linear sweep voltammetry (LSV). Experimental parameters, such as scan rate, pH and amount of the modifier used on the PGE surface were optimized by monitoring the LSV...

The Regular Graph Retated to Rings

, M.Sc. Thesis Sharif University of Technology Jamaali, Mohsen (Author) ; Akbari, Saeed (Supervisor)

Abstract

There are many papers in which some graphs are assigned to algebraic structures such as rings groupsThe concept of regular graph related to a ring was rst investigated by DF Anderson and A Badawi in Assume that R is a commutative ring and Z??R denotes the set of zerodivisors of R and Reg??R R n Z??R The regular graph of R which is denoted by Reg????R is a graph whose vertex set is Reg??R and two vertices x and y are adjacent if and only if x y ?? Z??R This can be generalized to a non commutative ring For the vertex set we consider the set of left ??right zerodivisors and join two elements if their sum is a left ??right zerodivisor Let R be the ring of n n matrices over a eld F with...

Zero-sum Flows in Graphs

, M.Sc. Thesis Sharif University of Technology Nategh, Emisa (Author) ; Akbari, Saeed (Supervisor)

Abstract

For an undirected graph G, a zero-sum flow is an assignment of non-zero real numbers on the edges of G such that the total sum of all edges incident with any vertex of G is zero. A zero-sum k-flow for a graph G is a zero-sum flow with labels from the set {±1, . . . , ±(k ? 1)}. In this thesis for a graph G, a necessary and sufficient condition forthe existence of zero-sum flow is given. It has been conjectured that if a graph G has azero-sumflow, then it has a zero-sum 6-flow. Also, it has been proved that this conjectureand Bouchet’s Conjecture for bidirected graphs are equivalent. It is shown that the con-jecture is true for 2-edge connected bipartite graphs, and every r-regular graph...

Application of Pore Network Modeling in Study of Rock Typing Algorithms

, M.Sc. Thesis Sharif University of Technology Sistan, Morteza (Author) ; Jamshidi, Saeed (Supervisor)

Abstract

One of the most important issues in modeling and simulation of reservoirs is determination of different rock types or Rock Typing. In this study, after a brief review of some conventional methods for rock typing, their capabilities have been investigated. In this way, for the first time, pore network modeling is used as a tool for validating the rock typing methods. By using flow simulation in porous medium with pore network modeling approach, similar rock types data have been generated and these artificially data have been used for validating of rock typing methods. To form more realistic pore networks, both regular and irregular pore network have been modeled and analyzed. Pore size...

On the Roman Domination Number of Graphs

, Ph.D. Dissertation Sharif University of Technology Qajar, Sahar (Author) ; Akbari, Saeed (Supervisor)

Abstract

Let G be a graph. A labeling f : V (G) ! f0; 1; 2g is called a Roman dominating function, if every vertex u with f(u) = 0 has at least a neighbor v with f(v) = 2. Define the weight of a Roman dominating function f to be w(f) =Σv2V (G) f(v). The Roman domination number of G is R(G) = minfw(f) : f is a Roman dominating functiong. Some other parameters are defined based on Roman domination number. A Roman bondage number bR(G) of G is the minimum cardinality of all sets E E(G) for which R(G E) > R(G). The edge Roman domination number of G, LR(G), is defined as R(L(G)), where L(G) is the line graph of G. In this thesis, after determining the exact value of the Roman bondage number for some...

Rationality of Scientific Knowledge From the Point of View of Feyerabend

, M.Sc. Thesis Sharif University of Technology Zali, Farshid (Author) ; ZibaKalam, Saeed (Supervisor)

Abstract

Feyerabend was a philosopher of science that became famous for his purportedly anarchistic view of science and his rejection of the existence of universal methodological rules and rationality of science. Feyerabend’s view of science can be summarize in a few points; 1. On the issue of falsifiability, Feyerabend argues that no theory is ever consistent with all the relevant facts. He sees the use of ad-hoc postulates to save the dominant paradigm as an essential to the progress of science. He claims that scientists frequently depart completely from the scientific method when they use ad-hoc ideas to explain observations that are only later justified by theory. To Feyerabend, ad-hoc...

Detection and Performance Analysis of Spread Time CDMA Systems in the Presence of Multitone Jammers

, M.Sc. Thesis Sharif University of Technology Akhoondi, Farhad (Author) ; Mashhadi, Saeed (Supervisor)

Abstract

In this thesis, we study and analyze the performance of matched and partially-matched re-ceivers for a typical Ultra Wide-band Spectrally-Encoded Spread-Time (SE/ST) CDMA in the presence of multiple tone jammers and a coexisting OFDM system. We investigate a scenario in which there is not any information about the jammer and OFDM subcarrier frequencies in the transmitter side and we try to cancel jammers and interferences at the receiver. For this case, we demonstrate that by using a partially-matched filter at the receiver in an environment with multiple tone jammers and some coexisting systems the performance of the SE/ST system can be improved. We also assume K asynchronous users and...