Sharif Digital Repository

Cancer treatment is one of the most challenging issues of recent years. Extensive researches have been conducted in various fields of medicine, pharmacy, and medical physics in this regard. Today, considering nanotechnology developments, researchers believe that full cancer treatment is possible through the use of nano-systems designed with scientific background to overcome the defects of previous methods. In this research, the main purpose is to design and synthesize multifunctional hybrid nanostructures with favorable optical and magnetic properties providing a way to combine chemotherapy and thermal treatment. Accordingly, two different structures were designed and experimentally... 

Providing anonymity in communications is one of the major requirements for the preserving the privacy of users using communication networks. There are several protocols for transmitting anonymous message in public communication networks. DC-Nets can be considered as an important solution to anonymous communications because they provide perfect anonymity; however, their high message and bit complexity is a major obstacle in their practical usage. All DC-Net based protocols provide anonymity of sender and receiver by establishing some anonymous channels for transmission of messages. Each execution of the DC-Net protocol acts as an anonymous channel, which only one participant can send his... 

Conversion of Methane molecule to valuable heavier hydrocarbon and hydrogen by using of short pulse lasers is investigated. The dynamical information of molecule such as orientation, dipole moment variations with binding length, and potential energy levels are initially produced by using Gaussian software. Based on this information the Schrödinger wave equation for this polyatomic molecule is numerically solved. Then by selecting the various laser parameters and installing of them in the Hamiltonian of the mentioned system, the dependence of hydrogen transition and separation probability on these parameters are investigated. In this work by radiating of the laser beam along the C2 symmetry... 

Secret sharing is a method for sharing a secret among a number of participants in a manner that an authorized subset of participants can recover the secret using some information, called share, and some public values. One type of secret sharing schemes is Multi-stage Multisecret sharing scheme (MSSS). In such schemes, assigning one share to each participant, an authorized subset of participants is able to recover the secrets in different stages without any information leakage from the recovered secret(s) to the other one(s), using some public information.The number of public values is one of the most important parameters in secret sharing schemes. In this thesis we show that the number of... 

Artemia (brine shrimp) is a genus of crustaceans that lives in saltwater and due to having unique features, in producing the food and nutrients needed for larvae and other types of farmed sea creatures, is of great importance. In its natural environment under certain conditions, Artemia produces cysts that float at the water surface and are driven ashore by wind and waves. These cysts are inactive and do not develop further as long as they are kept dry. Upon immersion in seawater, the biconcave cysts hydrate and become spherical and, within the shell, the embryo resumes its interrupted metabolism. After about 20 h the outer membrane of the cyst breaking and the embryo appears, surrounded by... 

Nd:YAG laser is one of the most applicable lasers on laser researches where it’s basic wavelength and higher harmonics are used on different laser projects. It should be realized that it’s basic output has a wide pulse duration and lower peak power. Therefore, in order to increase the peak power the pulse duration is reduced by Q-switching.
In this project, in the first step, based on flash-lamp pump Nd:YAG laser a 600 mj energy per 60 µs pulse is constructed. Then a pulse duration is shorten by order of more than 3000 via electro-optics Q-switching system where we could reach up to 19 ns pulses and laser peak power is increased up to several megawatts  

Resent advances in ultra-intense short-pulse lasers and their numerous applications stimulated the research activities in important fields such as generation of high-energy electron and ion beams, monoenergetic electron beam, monoenergetic ion beam, X-ray emission, terahertz radiation, high harmonic and attosecond pulses generation. In all above mentioned applications the relativistic electrons behavior especially the electron density distribution and the velocity of electrons play an important role.
Investigating the behavior of relativistic electrons which are generated in the interaction of high power femtosecond lasers with plasma and their related applications is the main purpose... 

The assumption of infinite lifetime is common in most of the inventory models. However, the perishability of products is a major problem of some industry sectors in which by disregarding the finite lifetime of their products the resulting model may give inaccurate results. Although, significant studies have been carried out for inventory control of perishable products, yet the literature needs more studies to develop or optimize the inventory policies. In this thesis, the inventory control of perishable products is considered. For the case of stochastic demand, it was well known that there is no inventory control policy in which both the order size and the order interval are constant with an... 

The purpose of this project is to investigate the production of nano-micro metallic particles—of different elements—with different characteristics in size and optical property by employing a pulsed laser ablation processes in liquid medium. In this study, the means by which we build the laser, the experimental arrangement of the pulsed laser ablation process, the measurement of the absorption spectrum of generated nano-micro particles as well as the size of the particles are discussed.
To satiate this aim, we have expressed the manner of constructing the Nd:YAG laser, the power supply circuits, along with its optics. This laser has some advantages such as high energy ~700mj, good... 

Nowadays almost all the research laboratories use femtosecond lasers, and Ti: sapphire laser is the most popular among them. Therefore, in this thesis, a Ti: sapphire pulsed laser with z-fold cavity with output of 50 fs and repetition rate of 100MHz has designed and simulated. Therefore, in the first chapter, introduction to the theory of ultrashort pulses and situation to create these pulses are presented. In addition, as regards to produce of short pulses, it is necessary to set laser in cw mode, in the second chapter we have investigated laser in cw mode. So, in this chapter, rate equations of gain medium, the stability zone of the laser, manner of removing astigmatism in the cavity,... 

In this work a theoretical overview of Parity-Time symmetry and its application in multilevel atomic systems are presented. Because of equivalence between the Schrodinger equation and the paraxial propagation equation, complex index of refraction plays the role of complex potential. On the other side, the possibility to manipulate loss, gain and the index of refraction simultaneously, Optics is a fertile ground to investigate Parity-Time symmetry and one of this symmetry’s applications is reduction of loss in optical systems. Furthermore, In order to realize Parity time symmetry a four level atomic system under electromagnetically induced transparency condition is proposed. Optical gain... 

Fulfilling the demands of customers, used to be the main purpose of Supply Chain Network Designers. Soon after that, the environmental concerns created the concept of Reverse Logistic in order to prevent goods from being scattered in the environment after their disposal. Governmental regulations and people's concerns, forced the factories to gather the created pollutions of the environment. They gradualy confessed the positive impacts of these ruturns on their financials. The flow of forward and reverse logistics establishes a Closed-Loop in which the returning economical circumstances were transferd into original factories. Later, Open-Loops were created. In open-loops the returns have to... 

In this thesis, conversion of methane into heavier hydrocarbons was performed by nanoparticles-assisted nanosecond laser induced plasma. Nickel oxide nanoparticles was synthesized by sol-gel procedure and packed into a compact tablet after drying and used as a target in a two BK7 windows-camber with pressure of 1500 mbar. Methane was introduced to the chamber and two different nanosecond lasers namely, Nd:YAG (λ=1064 and 532 nm) and KrF (λ=248 nm) were radiated. Interaction of the gas with the plasma produced by metal nanoparticles and the thermionic emissions due to the inverse bremsstrahlung caused conversion of methane to the heavier hydrocarbons. These conversions can also promote by... 

The aim of this thesis is calculating soliton pulse propagation in fiber optic and its interaction with plasma to generating high accelerated electrons for radiotherapy. By chirped pulse amplification technique in the new generation of table-top lasers, the intensity of laser beam could be increased up to . A high gradient electric field more than is generated by the interaction of this high intense laser beam with plasma gas. In these high gradient fields electrons can be accelerated. These accelerated electron beam can be played an important role in radiotherapy. In this project by using general pulse propagation equation in linear and non-linear medium and solving non-linear... 

In this research, using a hydrochemical model alongside three dominant instabilities of shape, Bjerknes and diffusion, the effect of ambient parameters on the single bubble sonoluminescence (SBSL) in Sulfuric Acid (SA) is studied. The phase diagrams of the bubble in the (R0 − Pa) space are presented, and the parametric dependence of the light intensity is discussed. In a part of this research a hot plasma core is considered at the center of the bubble. The study of ambient temperature shows that in contrast to water, the calculated thermalbremsstrahlung mechanism of light emission at the fixed degassing condition of high SA concentrations shows that with increasing the temperature of aqueous... 

In this thesis the conversion of methane into higher hydrocarbures using pulsed nanosecond lasers has been studied. The lasers of 532 nm of second harmonic of Nd: YAG, 355 nm of 3rd harmonic of Nd: YAG and 248 nm of KrF have been used in this project. Acetylene, ethylen and ethane have been detected using gas chromatography detection system, which showed acetylene as a dominant product. For each wavelength the amount of the laser energy and the fraction of secondary products have been measured. Also the dependence of amount of produced components on chamber pressure has been studied for 355 nm laser. During the irradiation time of methane no considerable changes in temperature and pressure... 

Although inventory control under discrete demand in dynamic quantities and time intervals are very common in reality, existing literature has largely ignored them. In this thesis, we investigate the inventory control decisions in a two echelon supply chain. The vendor supplies a product to several retailers, buying discrete quantities in pre-determined time intervals. The order quantity and order cycles for each retailer can be different from others. We have developed a new efficient algorithm to find the optimal ordering policy involves the scheduling and the order quantity of vendor to his supplier to minimize his cost function in infinite time horizon. Moreover, we have designed a revenue... 

The abstract is the most important section of the thesis because many readers limit most of their reading to abstracts, saving in-depth reading for specific theses. It should give the reader a "preview" of what's to come. The abstract should emphasize new and important aspects of the study or observations. The purpose of the abstract is to allow researchers to decide whether or not to read the whole thesis. The abstract is what researchers read first to decide if the thesis is important, interesting, and it allows them to assess the relevance of a thesis to their own research, without having to read the entire thesis. Thus, it is crucial that the abstract both summarize succinctly the key... 

Recently, The interest of using the coherent and incoherent photons in chemical synthesis have been raised considerably. In this project, theoretical calculations due to investigation of irradiation’s effects on Fischer- Tropsch synthesis have done. Fischer – Tropsch synthesis is the process that converts synthesis gas, i.e. a mixture of carbon monoxide and hydrogen, in to a wide range of long chain hydrocarbons and oxygenates. We invest the first chapter of this project to introduce of Fischer- Tropsch synthesis and its importance. Following in the next chapter we have analyzed the photocatalyst in microscopic scale. In third chapter, we have claimed the necessary theories which are useful... 

Artemia is a small crustacean which has adapted to live in high salty water.The name of Artemia has been chosen according to its appearance. The adult Artemia is viviparous in the proper conditions whereas in tough conditions it reproduces the cysts. About 20 hours after the floating of cysts in water, its crust splits and after a while nauplii is produced by the free swimming. The changes of the hatching percentage of cysts Artemia and also the changes of Artemia Urmiana's size have been evaluated in this report.
The hatching percentage of cysts have been studied under LED radiation of red, orange, green and blue wavelengths, under red diode laser radiation and also under the...