Sharif Digital Repository

The substructuring method provides a suitable tool to conduct modal analysis of large and complicated structures. In this method the original structure is decomposed into simpler and smaller substructures, and the dynamic properties of the resulting substructures are first evaluated independently. The original structure’s dynamic properties are subsequently estimated by coupling the substructures’ dynamic results. In this procedure, the boundary conditions need to be imposed in such a way that the overall behaviour of the original structure is properly represented. Substructuring method can be used in different types of dynamic analysis. The focus of this paper is on the modal type of... 

An important issue in High-Frequency circuits is the transmission of electrical signals in Integrated Circuits and Printed Circuit Boards (PCBs). At high frequencies, however, the often used transmission lines suffer from high conductor and substrate loss as well as unwanted electromagnetic coupling to other circuit elements caused by parasitic substrate surface. One method through which both of the above problems may be solved is utilizing waveguide structures on PCBs and ICs. In this way, due to the reduction of conductor loss, a large proportion of signal passes easily. Moreover, and because of closed nature of cavity waveguides, neighboring circuits are protected against electromagnetic... 

Markov chains are memoryless stochastic processes that undergoes transitions from one state to another state on a state space having the property that, given the present,the future is conditionally independent of the past. Under general conditions, the markov chain has a stationary distribution and the probability distribution of the markov chain, independent of the staring state, converges to it’s stationary distribution.
We use this fact to construct markov chain monte carlo, which are a class of algorithms for sampling from probability distributions based on constructing a markov chain that has the desired distribution as its stationary distribution. The state of a chain after a large... 

The synchronization phenomena are abundant is science, nature, engineering, and social life. Systems as diverse as clocks, singing crickets, cardiac pacemakers, firing neurons, and applauding audiences exhibit a tendency to operate in synchrony. These phenomena are universal and can be understood within a common framework based on modern nonlinear dynamics. First chapter of this thesis describes the basic ideas of the synchronization in an intuitive way. The main physical concepts are presented with experimental examples.
One of the main effects of synchronization is the ability to infer the directionality of coupling for two time series. Uncovering the directionality of coupling is a... 

Slosh phenomenon is described as the motion of the fluid’s free surface in a tank or partially-filled container. This motion can induce undesired forces that can change the path of a vehicle. In some liquid carrying vehicles these undesired changes is sensed by the driver or control system and can lead to instability. Some examples of this phenomenon are aircrafts, rockets, ships and fuel carrier trucks.
In this project, a coupling between the dynamics of the vehicle and the contained fluid is implemented for in depth understanding of the interactions. This is done by Co-Simulation. With the help of Co-Simulation, corrective control actions can be taken and the design of more powerful... 

The fused pyrimidine rings have many biological applications such as antibacterial, antiviral, antitumor and anti-inflammation activity. Therefore, their synthesis has attracted many attentions. In this thesis, the synthesis of fused pyrazolopyrimidine rings through two component reaction catalyzed by iodine was investigated. In this reaction, iodine is used to active the imine bond. Low toxicity, availability, low cost and stability to air are some benefits of iodine as a Lewis acid leading to widespread application of I2 in many different organic transformation. Mild reaction conditions, high yields and lower reaction times are among the main advantage of these reactions.
Another part... 

Analysis of neutronic and thermal-hydraulics fluctuations has various applications in calculation or measurement of the core dynamical parameters (temperature reactivity coefficients) furthermore it is applicable in thermal-hydraulics surveillance and diagnostics. Experience of the Fukushima Dai-ichi plant and the lessons learned from the European stress tests, demonstrated that alternative and various tools and methods are needed for the reactor's condition identification. In this paper the feasibility of development of an alternative accident monitoring via eminent coupling of neutron and thermal-hydraulics noise is proposed. and it is programming a simple simulator for calculating... 

In this thesis, heterogenous catalysts based on magnetic nanoparticles coated with organosilanes and poly(ionic liquids) were synthesized. These catalysts were synthesized by hydrolysis of tetraethyl organosilanes and other organosilicons such as 3-aminopropyl triethoxy silane and polymerization of some monomers in the presence of ionic cross-link agents. The synthesized matrixes were used to stabilize precious metals such as Pd and Au. The magnetic properties of the catalysts aid to easy separation from the reaction medium by an external magnetic field. High thermal stability low toxicity and high-level loading of metals are some beneficiaries of the magnetic catalysts. At the end,... 

There are two parts in this thesis. The first one is about the synthesis of azulene based compounds, which are characterized by 13C and 1H NMR. These compounds were included in three imine ligands (1,2 and 3) and a NHC ligand (4). Azulene based materials shows a fluorescence emission. The stimuli-responsive emissive azulene derivatives are very rare. herein, we report the synthesis of stimuli responsive emissive 1- and 1,3-disubstitution azulene-based compounds that can switch on and off the emission upon protonation with trifluoroacetic acid (TFAH) and deprotonation with triethylamine respectively. The type of transitions were studied by computational calculations. The complexation of some... 

Antenna arrayss have long been utilized in many applications including communication, radar, and imaging. With the advancement of the telecommunication industry and the emergence of new requirements in the fifth generation of telecommunications, imaging and the Internet of Things, new antenna arrays are designed at higher operating frequencies and with particular specifications. One of the major challenges in using these types of antennas is unwanted mutual coupling in these systems. These couplings can occur between the antenna elements of the array itself, or between two or more arrays that are adjacent to each other. These couplings can seriously affect the performance of the system.... 

The presence of spatial partial derivatives in the equations of classical continuum mechanics has led to the fact that methods based on this theory are not valid in displacement discontinuities (such as cracks). The peridynamic theory is a nonlocal formulation of solid mechanics which is most suited to model discontinuities and dynamic fractures in continuous or discrete media. By substituting integral expressions instead of partial differentials in the equations of motion, peridynamics provides an integrated model that is valid and the same in continuous, discontinuous, and discrete media.The capability of the peridynamic theory in modeling discontinuities and cracks has been demonstrated... 

Idiopathic pulmonary fibrosis is the most common type of pulmonary fibrosis that causes ulcers inside the lungs. In addition to Nintedanib, Pirfenidone is currently the only compound approved by the US Food and Drug Administration in 2014 for the treatment of idiopathic pulmonary fibrosis. Meanwhile, in the pharmaceutical industry, drug synthesis is usually done through batch-wise processes, and pirfenidone is currently only produced through batch-wise processes. Hence, this study aims to change the synthesis method of this drug, which is traditionally performed through batch-wise processes, to a continuous flow process. Therefore, a micro-reactor technology can be adopted which offers a...