Dynamic NMR Study of Thibencarb (S-4-chlorobenzyl N,N-dimethyl Thiocarbamate)

, M.Sc. Thesis Sharif University of Technology Alinia, Zahra (Author) ; Tafazzoli, Mohsen (Supervisor)

Abstract

In this project, rotational barrier of C-N bond in thiobencarb (S-alkyl thiocarbamate) has been studied by HNMR spectroscopy. All the spectra were taken at different temperatures, and then by simulation of bandshape broadening pattern, rate constants for all temperatures were calculated. SpinWorks software was used for the simulation of line shape broadening which has two bandshape simulator programs, DNMR and MEXICO. The obtained rate constants were used to calculate the thermodynamic parameters of activation (ΔG‡, ΔH‡, ΔS‡ and Ea). Experimental ΔG‡298 value for thiobencarb was calculated 15.11kcalmol-1 and 15.86 kCalmol-1 in chloroform and acetone solvents respectively. The computational...

Measuring Multidimensional Poverty Using Structural Equation Models

, M.Sc. Thesis Sharif University of Technology Alinia, Parisa (Author) ; Souri, Davood (Supervisor)

Abstract

In order to measure poverty, researchers used to consider only the income and the financial aspect of poverty; however, further research has revealed that income in itself cannot be a proper and comprehensive index for measuring poverty, and other factors such as education, health, occupation, personal characteristics, cultural activities, political activities, etc. are also significant in determining the poverty index. Based on the information acquired from "household expenditure-income survey", this study tries to take into account all the factors affecting the poverty index, in four dimensions of economic well-being, capability, political participation and cultural participation. Poverty...

Rolling Contact Analysis of a Cylinder with a FGM Coated Half-Plane

, Ph.D. Dissertation Sharif University of Technology Alinia, Yadolah (Author) ; Adibnazari, Saeed (Supervisor)

Abstract

This study focuses on the mathematical modeling of the rolling contact problem of an FGM coating-substrate system. The first part presents the uncoupled rolling contact problem of an FGM coated half-plane under the assumption of a central stick zone with two slip zones of the same sign. Considering all possible stick/slip scenarios, the fully coupled rolling contact problem of a graded coating is given in the second part. Finally, the rolling contact problem of two elastically similar cylinders with graded coatings will be discussed. Generally, all mentioned problems can be solved in three consecutive steps. First, the governing equations of the relevant rolling contact problem are...

On the contact mechanics of a rolling cylinder on a graded coating. Part 1: Analytical formulation

, Article Mechanics of Materials ; Vol. 68, issue , 2014 , p. 207-216 Alinia, Y ; Guler, M. A ; Adibnazari, S ; Sharif University of Technology

2014

Abstract

In this paper, the fully coupled rolling contact problem of a graded coating/substrate system under the action of a rigid cylinder is investigated. Using the singular integral equation approach, the governing equations of the rolling contact problem are constructed for all possible stick/slip regimes. Applying the Gauss-Chebyshev numerical integration method, the governing equations are converted to systems of algebraic equations. A new numerical algorithm is proposed to solve these systems of equations. Both the coupled and the uncoupled solutions to the problem are found through an implemented iterative procedure. In Part I of this paper, the analytical formulation of the rolling contact...

The effect of material property grading on the rolling contact stress field

, Article Mechanics Research Communications ; Vol. 55, issue , 2014 , p. 45-52 Alinia, Y ; Guler, M. A ; Adibnazari, S ; Sharif University of Technology

2014

Abstract

This paper investigates the subsurface stress field induced by a rigid cylinder rolling over a functionally graded coating-substrate system. The Fourier transform is employed to extract the stress components within the graded coating and the homogeneous substrate. The distributions of the stresses are given through the depth and along the coating-substrate interface. The contour plots of normalized Von Mises stresses are provided as well. The results indicate that continuous variation of the shear modulus substantially reduces the difference between the in-plane stresses along the interface. Also, the softening coating leads to the minimum value of the stress concentration near the contact...

Tractive rolling contact mechanics of graded coatings

, Article International Journal of Solids and Structures ; Volume 49, Issue 6 , March , 2012 , Pages 929-945 ; 00207683 (ISSN) Guler, M. A ; Adibnazari, S ; Alinia, Y ; Sharif University of Technology

2012

Abstract

In this study, the tractive rolling contact problem between a rigid cylinder and a graded coating is investigated. The main objective of this study is to investigate the effect of the stiffness ratio, the coefficient of friction and the coating thickness on the surface contact tractions, the surface in-plane stress, the stick zone length and the creep ratio parameter that may have a bearing on the fatigue life of the component. Assuming that the shear modulus varies exponentially through the thickness of the coating, the governing integral equations associated with the rolling contact problem are constructed. Furthermore, it is supposed that the contact patch is controlled by a central stick...

Mesoporous silica nanoparticles (MCM-41) coated PEGylated chitosan as a pH-Responsive nanocarrier for triggered release of erythromycin [electronic resource]

, Article International Journal of Polymeric Materials and Polymeric Biomaterials ; 2014, Volume 63, Issue 13, Pages 692-697 Pourjavadi, A. (Ali) ; Mazaheri Tehrani, Zahra ; Sharif University of Technology

Abstract

A pH-responsive drug delivery system based on core shell structure of mesoporous silica nanoparticle (MSN) and chitosan-PEG copolymer was prepared and characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscope (SEM), and high-resolution transmission microscope (HR-TEM) techniques. In order to improve compatibility MSN and drug, mesoporous nanosilica was modified by 3-aminopropyl triethoxysilane. The release of erythromycin (a macrolide antibiotic) as a model drug was investigated in two pHs, 7.4 and 5.5

Maximizing quality of aggregation in delay-constrained wireless sensor networks

, Article IEEE Communications Letters ; Volume 17, Issue 11 , 2013 , Pages 2084-2087 ; 10897798 (ISSN) Alinia, B ; Yousefi, H ; Talebi, M. S ; Khonsari, A ; Sharif University of Technology

2013

Abstract

In this letter, both the number of participating nodes and spatial dispersion are incorporated to establish a bi-objective optimization problem for maximizing the quality of aggregation under interference and delay constraints in tree-based wireless sensor networks (WSNs). The formulated problem is proved to be NP-hard with respect to Weighted-sum scalarization and a distributed heuristic aggregation scheduling algorithm, named SDMAX, is proposed. Simulation results show that SDMAX not only gives a close approximation of the Pareto-optimal solution, but also outperforms the best, to our knowledge, existing alternative proposed so far in the literature

Rolling contact problem for an orthotropic medium

, Article Acta Mechanica ; Volume 228, Issue 2 , 2017 , Pages 447-464 ; 00015970 (ISSN) Alinia, Y ; Zakerhaghighi, H ; Adibnazari, S ; Guler, M. A ; Sharif University of Technology

Springer-Verlag Wien 2017

Abstract

In this paper, the two-dimensional tractive rolling contact problem between a rigid cylinder and an orthotropic half plane is considered. A pair of singular integral equations is derived for the contact tractions using the Fourier transform technique. The governing integral equations are decoupled using the Goodman approximation and then solved numerically. Finally, the distribution of surface tractions is achieved in the contact region. This study emphasizes the significant effect of the orthotropic material parameters and the coefficient of friction on the contact tractions as well as the rolling contact characteristics for an orthotropic medium. © 2016, Springer-Verlag Wien

Theoretical and Computational Investigation of Quantum Plasmonic Properties of Nanocluster Dimers

, M.Sc. Thesis Sharif University of Technology Mahmoudi, Erfan (Author) ; Jamshidi, Zahra (Supervisor)

Abstract

In today's era, metal nanoparticles play an important role in technologies emerging from different sciences, such as chemistry, physics, optics, material science, due to their unique characteristics. In the development of nanooptics science, it can be said that metal nanoparticles play an important role. The ability of conductive electrons collective oscillation causes surface charge density fluctuations in nanoparticles, this phenomenon is known as surface plasmons. Surface plasmons are surprisingly coupled with light and cause the significant increase in the intensity of optical fields induced in nanoparticles. Therefore, with the presence of localized surface plasmons or plasmon...

Theoretical Investigation of Ab-initio MD Approach to Increase the Efficiency and Accuracy of VCD Spectrum Calculation

, M.Sc. Thesis Sharif University of Technology Hadi, Hossein (Author) ; Jamshidi, Zahra (Supervisor)

Abstract

Understanding of the Molecules is the main purpose of the chemistry. Ab-initio molecular dynamics (AIMD) as a branch of the computational chemistry, tries to give us a deep comprehension of the molecule, and its chemical, physical and optical activities. This comprehension, relies on the accuracy of quantum mechanics, in addition to the speed of the classical mechanics. The mixing of the quantum mechanics and the classical mechanics could simulate activities of the atoms in the time-domain, provided the mixing is done with precaution. This, in turn, helps us to forecast the response of a molecule in different situations, and also translating the macroscopic phenomena in a nanoscopic...

Investigation of Plasmonic Excitation in Carbonic Nanostructures Within Near-IR

, M.Sc. Thesis Sharif University of Technology Madadi, Mahkam (Author) ; Jamshidi, Zahra (Supervisor)

Abstract

To date, the plasmonic properties of many metallic and semi-conducting materials have been investigated and used in various industries. One of the plasmonic material categories that have always been considered is polycyclic aromatic hydrocarbon or PAH, whose plasmonic resonance energy depends on the charge state of the molecule. In this regard, it is easy to change the plasmonic resonance energy via changing the induced charge, which is a unique feature of the mentioned materials. In addition, plasmonic structures with excitations in the infrared region are able to enhance the vibration intensity of absorbed molecules by increasing the electric field around themselves. Therefore, they have...

Using Nonlinear Effects of Light for Optical Signal Processing

, M.Sc. Thesis Sharif University of Technology Shatery, Farshid (Author) ; Kavehvash, Zahra (Supervisor)

Abstract

Ultrafast signal processing in time-domain with high resolution and reconfigura-bility is a challenging task. This paper, for the first time, introduces a time-varying metasurface consisting of graphene microribbon array for implementing time-lens in the terahertz domain. Given that the surface conductivity of graphene is proportional to the Fermi energy level in the THz regime, it is possible to change the phase property of the incident electromagnetic pulse by changing the Fermi level while the Fermi level itself is a function of voltage. Upon this fact, a quadratic temporal phase modulator, namely time-lens has been realized. This phase modulation is applied to the impinging signal in the...

Using Simulation-Optimization Approach for Fire Station Location and Vehicle Assignment Problem: a Case Study in Tehran, Iran

, M.Sc. Thesis Sharif University of Technology Pirmohammadi, Ali (Author) ; Amini, Zahra (Supervisor)

Abstract

In this research, the problem of locating fire stations and allocating equipment has been studied and a simulation-optimization approach has been presented to solve the problem. The mathematical models of this research were developed based on the idea of the randomness of the covered demand and the maximum expected coverage model. In these models, the issue of non-availability of equipment to cover accidents, the random nature of accidents, various fire incidents and the equipment needed to cover them are considered. Two mathematical models with deterministic and non-deterministic approach with different scenarios for demand are proposed. The non-deterministic model is developed with the aim...

Introducing An Integrated Framework For Solving The Fleet Planning Problem Using A Simulation-Optimization Approach

, M.Sc. Thesis Sharif University of Technology Sahebi, Armin (Author) ; Amini, Zahra (Supervisor)

Abstract

One of the main concerns of industrial companies’ managers is providing an efficient logistics system. To achieve an efficient logistics system, the fleet planning problem is studied by many researchers in recent years. This problem consists of multiple sub-problems at three levels: operational, tactical, and strategic. These sub-problems are closely related to each other and need to be studied and addressed in an integrated manner. In this research, an attempt is made to provide an integrated framework to solve the vehicle routing problem (operational), outsourcing problem (tactical), and fleet composition problem (strategic). These problems have various uncertainties, including customer...

Analytical Modelling and Optimization of Disk Type, Slot Less Resolver

, M.Sc. Thesis Sharif University of Technology Moheyseni, Atefeh (Author) ; Nasiri Gheidari, Zahra (Supervisor)

Abstract

Resolvers, due to their robust structure, are widely used in automation systems. Among the types of resolvers, the accuracy of the Wound Rotor (WR) resolver in the occurrence of common mechanical errors is higher than other types of resolvers. therefore, in this thesis, an AFWRR is studied to improve the performance. Increasing the number of poles in WR resolvers is a good solution for increasing the accuracy of these electromagnetic position sensors. However, high-speed WR resolvers due to employing fractional slot windings suffer from rich sub-harmonics in the induced voltages. A common solution for suppressing the undesirable sub-harmonics is using multi-layer winding with appropriate...

A Survey on Searchable Symmetric Encryption Schemes

, M.Sc. Thesis Sharif University of Technology Sajadieh, Zahra Sadat (Author) ; Khazaei, Shahram (Supervisor)

Abstract

Using “Searchable Encryption” enables us to encrypt the data, while preserving the possibility of running search queries. One of the most important applications of the mentioned is in Cloud Storage. As users do not trust the Cloud space, they are not inclined to store their data on the Could. The solution to this problem is of course, Cryptography. However, ordinary Cryptography methods, eliminate the data’s searchability. Hence, we need encryption schemes that code the data while retaining their searchability. So far, various schemes has been proposed that differ in their performance, security level, and usage. In this thesis, we aim to discuss and analyze these methods

Time Domain Optical Signal Processing Based on the Duality Between Dispersion and Diffraction

, M.Sc. Thesis Sharif University of Technology Eksiri, Fatemeh (Author) ; Kavehvash, Zahra (Supervisor)

Abstract

In the last decades, due to the growing demand of transferring information with high transmission rates, the complexity and development of telecommunication and optical systems is remarkable. Researchers around the world attempt to explore extraordinary potential of light to process information. In the mid-19th century, scientists discovered a mathematical symmetry between the spatial and temporal optics fields, which originated from the similarity of equations governing the paraxial diffraction of beams and the dispersion of narrow-band pulses known as space– time duality in scientific texts. This new approach provides more advanced and potent methods to temporal processing and...

Improving the Stability of an Urban Traffic Network with Limited Data by Using Percolation Theory and Dynamic Clustering

, M.Sc. Thesis Sharif University of Technology Hassanzadeh, Ehsan (Author) ; Amini, Zahra (Supervisor)

Abstract

One of the most vital aspects of understanding the traffic phenomenon is scrutinizing the traffic transition status, such as the transition from free flow to congestion. The Percolation Theory is a renowned theory focusing on analyzing various network types to detect the critical zones, which are the zones including links that are important to control to improve stability. By calculating the quality indices of network links, the Percolation Theory can simulate the traffic percolation propagation in the network and determine possible critical zones for further analysis. Most studies in this field assume access to data of several traffic parameters for the entire transportation network, such...

Temporal Depth Imaging Based on Dispersion

, M.Sc. Thesis Sharif University of Technology Behzadfar, Shiva (Author) ; Kavehvash, Zahra (Supervisor)

Abstract

In this thesis, the aim is designing an optical temporal imaging system. In recent years, due to many applications, including the receipt of high-rate data by slow receivers and compensation of dispersion in telecommunication systems, researchers have considered the topic of temporal imaging. This field of research is based on dispersion, electro-optical modulators or time lenses and space-time theory. By modeling dispersion properties as a depth dimension and taking ideas from three-dimensional spatial imaging systems we intended to increase the temporal resolution and depth of focus of the structure. We also present a novel technique for multiplexing and demultiplexing telecommunication...