Sharif Digital Repository

People are increasingly using private vehicles as a result of the ever-increasing population growth worldwide and the increasing number of travel requests through the transportation network. There are many problems associated with the use of private vehicles on the transportation network, including traffic congestion and air pollution. To address the existing demand, decision-makers have always sought effective modes to respond to the existing situation. For passengers, the proposed modes of transportation should offer the same level of convenience and affordability as a private vehicle. In recent years, shared mobility has become increasingly popular. This mode of transportation has... 

In recent years, we have seen the proliferation of real-time and time-dependent systems. They have increased both in number and in complexity. Due to their increasing complexity, we need to model them and become assured of their correctness. Several formalisms have been devised for time-dependent systems. They include timed automaton and timed extensions of Petri nets. Our focus is on timed extension of activity networks and its model checking. Activity networksare powerful formalisms which allow designers to model the system in a natural, small and conceivable manner. This way, timed extension of activity networks can greatly help modelers. In this thesis, we propose a method to specify the... 

One of the open questions in particle physics and cosmology is matter-antimatter asymmetry in the Universe. Observations at different scales in the early universe indicates that the number of baryons and leptons are greater than the number of anti-baryons and anti-leptons. Various mechanisms in the last 50 years, have been proposed to generate this asymmetry from a symmetric Universe. They can be classified into two groups: models which add new particles and interactions and models which consider gravity and time dependent background fields. The basic difference is that if they respect CPT symmetry or not. In this thesis we take the second approach. We study the neutrino sector of the... 

Rhenium(I) tricarbonyl complexes with NN-donor ligands display promising properties for potential applications as molecular catalysts for the reduction of carbon dioxide and as biocompatible pro-drugs for the controlled release of carbon monoxide. In this context the diimine type ligands are one of the most widely used bidentate chelating moieties. In this work, several [Re(CO)3(DAB)X] complexes were prepared in a standard manner by replacement of two cis CO groups in the starting bromo- or chloro-pentacarbonylrhenium complexes with 1,4-diazabutadiene (DAB) ligands. Their pseudo-octahedral facial structures were established using FT-IR, 13C-NMR and 1H-NMR and confirmed by X-ray... 

Intelligent transportation systems (ITS) have been widely studied in recent years. One of the challenging problems in this field is routing on urban networks, which are largescale networks that are almost planar and sparse. In the routing problem, a person wants to journey from a known source to a known destination. He may have multiple choices as to the path to traverse, and wants to discover the best path, designated in terms of its travel time. The routing problem can itself be a subproblem of another larger problem, and so the running time of the routing algorithm is important. In addition, the existence of traffic flow on urban roads has great impact on travel times. The network is... 

The rapid growth of e-commerce and home delivery has increased the number of vehicles on the streets. As a result of that, traffic congestion and, in return, air pollution have got worse. To prevent this trend, using electric vehicles is highly suggested, and in recent years, some companies have started using autonomous delivery robots. Since these robots can travel for a limited time, it is better to use them in conjunction with other vehicles, like vans. In this research, we propose a mixed-integer programming model to formulate a two-echelon time-dependent vehicle routing problem with simultaneous pick-up and delivery. In the first echelon, vans travel from a central depot to parking and... 

Prediction of crack growth is one of the greatest achievements of continuum mechanics in 20th century. However, in spite of Griffith’s achievements, nowadays lots of subjects remain unchallenged in the field of Fracture Mechanics. Concrete and asphalt concrete are two of the most popular material in civil engineering and crack growth prediction in these materials are very important. Cohesive crack model is one of the models which is used for prediction of crack growth in quasi-brittle material such as concrete and it has been used widely in recent years because of simplicity and good agreement with experiment.The aim of this thesis is three-dimensional static and dynamic cohesive modeling of... 

Human brain is one of the most wonderful complex machine which is designed for ever. A huge complex network, composed of neurons as tiny biological and chemical processors which are distributed and work together as a super parallel system to do control and vital activities of human body. Today the main secrecies of operation mechanism in individual neurons as fundamental elements of brain are reasonably understood, but network interactions of this wonderful processors and full understanding of information coding in brain seems elusive and remains as a big challenge in many interdisciplinary fields of science, from biology to cognitive science and engineering.
Thus human brain learning... 

In this project, ionization and dissociation of nitrogen, methane and formaldehyde molecules through interaction by intense femto-second lasers have been investigated. The optimum shape of laser pulses for dissociation of methane and formaldehyde molecules for controlling the dissociation paths into desired products are obtained. Based on time dependent density functional theory and quantum optimal control theory, the calculations are carried out in intensities at the range of 1014-1016 Wcm-2 with pulse durations of 4 -20fs. Octopus package is used as a powerful computational program. By using, quantum optimal control theory, optimum laser pulses with manipulation of amplitude, phase and... 

Nowadays, the population growth and industrial development have caused pollution of air, water, and soil, which this turned into in a global challenge. Thus, replacing the running-out fossil fuels with renewable sources of energy is an important issue facing research and scientific communities. One of the methods to generate clean energy is hydrogen production through water splitting reaction inside photoelectrochemical cells using an appropriate semiconductor. Upon the light illumination, rates of charge transfer and recombination in semiconductors heterostructure (as photoanodes) are determining factors for efficiency of these cells. If electron transfer occurs faster (in a shorter time... 

The cationic cyclometalated platinum(II) complex [Pt(ⱪ2-2-ppy)(ⱪ1-N-2-ppy)2][OTF], 2, has been prepared by reaction of [PtMe3I]4, 1, with one equiv Ag(OTF) and then three equiv 2-phenylpyridine. The similar complex with formula [Pt(ⱪ2-p′py)(ⱪ1-N-p′py)2][OTF], in which p′py = 2-(3-bromophenyl)pyridine, 4, has been prepared with similar procedure, from the reaction of 1 with one equiv Ag(OTF) and then three equiv of the corresponding cyclometalating ligand. Also, the cationic cyclometalated platinum(IV) complex [Pt(2-(p-tolyl)pyridine)2(Me)(H2O)][OTF], 3, has been prepared from the reaction of 1 with one equiv Ag(OTF) and then three equiv 2-(p-tolyl)pyridine. The structure of complexes 2, 3... 

With the decline in oil discoveries during the last decades, it is believed that enhanced oil recovery (EOR) technologies will play a key role to meet the energy demand in coming years. Polymer flooding has been commonly used worldwide as one of the EOR processes. Literature reviews show that the active water-soluble polymers have a number of limitations related to their surface absorption, undesirable plugging, polymer concentration limitation,expensive, and low thermal, mechanical, bacterial, and salt tolerance. Up to now, five different polymer categories (i.e. polyacrylamide, hydrolyzed polyacrylamide, acrylamidebased resistant copolymers, associative copolymers, and thermoassociative... 

Entanglement is one of the unique phenomena in quantum systems that does not have any similar phenomena in classical systems. Entanglement has been used in many protocols of quantum information theory, and there is agreement on its key role in quantum computations and quantum communication protocols. Therefore, studying its dynamics as well as preventing its degradation is important for us. Extensive studies have been done in this field, including the study of entanglement evolution in a situation where all parts of the system are entangled with one of its sub-system has irreversible dynamics due to interaction with its environment [1], [2], [3], [4], [5], [6], [7], [8]. However, the study... 

Battery Electric vehicles (BEVs) are turning into a more well known type of transportation because of their energy effectiveness, further sustainability, and the arrangement of government support through motivation programs. However, BEVs have a constrained driving range due to their limited battery capacity. This limited battery capacity leads to a fear of exhausting energy in the middle of route which is referred to as range anxiety. The range anxiety affects BEV users’ travel choices such as route choice. Hence, BEV users should consider their vehicles’ remaining range while trying to minimize their travel times. This concern consequently changes the equilibrium flow on the transportation... 

The X-ray attosecond pulses have many useful applications for studying atomic and sub-atomic scales phenomena in attosecond scale duration. Generation and optimization of high-order harmonics is an efficient way to produce such attosecond pulses which are studied in this thesis. There are several limitations in the attosecond pulse generation such as low efficiency of high-order harmonics, long duration of output pulses and the impossibility of producing an attosecond pulse with any desired wavelength in the x-ray region. Therefore, more investigations into high harmonic generation and fully control and optimization of this process is significant. In this thesis, high harmonic generation... 

A highly reliable tool for transient simulation is vital in the safety analysis of a nuclear reactor. Despite this fact most tools still use diffusion theory and point-kinetics that involve many approximations such as discretization in space, energy, angle and time. However, Monte Carlo method inherently overcomes these restrictions and provides an appropriate foundation to accurately calculate the parameters of a reactor. For this reason, in this thesis, a dynamic Monte Carlo code named MCSP (Monte Carlo dynamic Simulation of Particles tracking) is developed for both the steady state and time-dependent simulation of particle (neutrons, photons and electrons) tracking in an arbitrary 3D... 

The focus of this research is to present a model to verify the acceptance of projects with time and cost dependency on the usage of equipments. Decision on these projects is based on a dynamic programming in which at each stage, the profit of available projects in this stage, equipment value and the best choice of future stage are decision keys. In other words, after the completion of a project, it should be decided between doing a project or selling the equipment and leaving the remaining projects. For each projects, there is a product network that includes projects jobs and operations. After accepting projects, equipments of the projects will not be renewed and the usage of the equipments... 

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... 

In this project, the ionization and dissociation of methane molecule by intense femto-second lasers has been studied. Dissociation probability is calculated for interacting CH4 molecule under Ti: Sapphire laser pulse with pulse durations of 10- 40fs in intensities at the range of 1014-1016 Wcm-2. Calculations are carried out with time-dependent density functional theory using Gaussian03 and Octopus packages as powerful computational chemical physics programs. Due to importance of the dependence of interaction dynamics to laser parameters, the effect of these parameters including different intensities, polarization, various pulse durations and pulse envelopes are investigated. The optimal... 

Droplet-based microfluidics offers a promising tool in engineering and biomedicine such as drug delivery, biochemistry, sample handling in lab-on-a-chip devices, and tissue engineering. These systems provide the droplets manipulation that can be used as reactors without any contamination for medical purposes. Utilizing magnetic force and ferrofluid droplets can help to better control over the droplet formation and manipulation. Considering the importance of this issue and its rich underlying physics, in this dissertation, ferrofluid droplets formation under a time-dependent, non-uniform magnetic field is studied. A Pulse-Width-Modulation signal (PWM) is utilized to apply the time-dependent...