Sharif Digital Repository

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 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... 

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... 

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... 

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... 

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... 

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... 

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... 

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... 

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... 

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... 

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...