Sharif Digital Repository

Dithiocarbamate is one of the most useful components in the science of chemistry. They are used not only in agriculture as fungicides but also in photochemistry in order to determine and analyse NO in biological processes as well as in polymerization routes. Dithiocarbamates which are known as bidentate ligands with high yield are applied in many fields such as producing chemical drugs, functioning as intermediates in organic synthesis, protecting groups in peptide synthesis as well as highly chelating ligands. Regarding the high practically of dithiocarbamates and by focusing on their synthesis process, we have applied them as bidentate ligands. Cinnamaldehyde was condensed in ethanol with... 

The interest in analyzing human language with complex networks is on the rise in recent years and a considerable body of research in this area has already been accumulated.However unfortunately, the use of applications of complex networks in Persian Linguistics research is missing. With the goal of introducing complex networks and their applications in this field, two of these applications have been studied in this research. First, we tried to build an inclusive network model, considering two levels of Syntax and Word Cooccurrence, for the Persian Language and provide Linguistics interpretations for them. In addition, by comparing co-occurrence networks of different languages, garnered from... 

Nowadays financial and business jobs without new technologies and new methods to manage are not that much useful. Managers are searching for all new methods in different areas for improving their profit, quality of services or increasing number of their customers. Because of this, they would check some ways to prove their issues. But the point is that they should have a great view about their products, customers and generally their own shop. One of the perfect methods to present the form and relation between their favorite factors is complex network. With complex network they can have perfect sight about their system. Also, with some remarkable and noticeable ways they can categorize their... 

In general, Constrain Satisfaction Problems (CSP’s) are NP-complete, however, this is not the case, if we impose some restrictions on the constraints. Due to importance and applications of CSP’s in different areas of engineering and science including artificial intelligence, relational databases and logic, investigating the computational complexity of CSP’s is an important issue. Computational complexity of CSP’s has been investigated from a variety of aspects, including the Universal Algebraic approach that has given rise to a solution of dichotomy conjecture recently. In this thesis based on contributions of Bulatov, Krokhin and Jeavons, we try to explain this universal algebraic approach... 

The dynamic behavior of networks largely depends on their structural properties. The information or failures can spread through the links of complex networks constructed by people or agents, and their physical and informational contacts. In this research, the process of network diffusion was investigated in different model and real networks. In particular, we focused on ”cascaded failure” and ”viral marketing” which are among the major topics that have attracted much attention in this context. Firstly, we investigated the robustness of modular complex networks against random and systematic component failures. Many real-world networks have modular structure and they may undergo random errors... 

Vaccination is one of the ways of disease control and prevention, which not only protect individuals against the disease, but also reduce the disease spread rate. Mass vaccination of individuals is not always possible due to the high cost and limitation of immunization resources. Therefore, researchers are always seeking solutions to find the persons that their immunization may have a greater impact in reduction of disease spread rate. The advent of network epidemic models and the possibility of removal the secured nodes in those models, showed that this problem is equivalent to finding a limited set of individuals that their removal will eliminate or minimize the number of people at risk of... 

Nowadays Systems in different fields of research like computer science, biology, social networks, information networks, and economics are modeled as graphs. The graphs which model real world systems have very different topological characteristics than those of classic networks. One of the prominent characteristics of these networks, is that its not practical to describe a general model for their structure and behavior. As a consequence of this complexity in modeling and structure, these networks are called complex networks. One of the most important observations in complex networks is the presence of communities, it means that in such networks one can separate vertices in disjoint sets, such... 

A number of questions from a variety of areas of mathematics lead one to the problem of analyzing the topology of a simplicial complex. However, there are few general techniques available to aid us in this study. On the other hand, some very general theories have been developed for the study of smooth manifolds. One of the most powerful, and useful, of these theories is Morse Theory. We present a combinatorial adaptation of Morse Theory, which we call discrete Morse theory that may be applied to any simplicial complex (or more general cell complex). Our goal is to present an overview of the subject of discrete Morse Theory that is sufficient both to understand the major applications of the... 

Let (M; g) be a Riemannian manifold. Using classical Stokes’ theorem one can show that the equality (dω; η)L2 = (ω; δη)L2 holds for smooth forms ! and η with compact supports, where δ is the formal adjoint of d . There are some examples of Riemannian manifolds for which the above equality does not hold for general forms ! and η i:e: smooth square-integrable forms such taht d! and δη are also squareintegrable. In the case that the above equality holds for such general forms on a Riemannian manifold (M; g) , we say that the L2 - Stokes theorem holds for (M; g) . In 1952, Gaffney showed that the L2 - Stokes theorem holds for complete Riemannian manifolds. But at that time, there was no powerful... 

With the rapid development in information-communication technologies a huge amount of electronic documents has been produced and increase everyday in the world wide web. According to this wide information environment, summarization is critical for the users who digest this electronic big data. This research proposes two graph-based abstractive models for summarizing the Persian texts. A good summary should cover the overall context and the important subjects, and should be properly readable and coherent as well. Some permanent challenges in automatic text summarizations intended to increase the readability of output text, as well as covering all the main topics, and minimize the redundancy.... 

Magnetorheological (MR) materials show variations in their rheological properties when subjected to varying magnetic fields. They have quick time response, in the order of milliseconds, and thus are potentially applicable to structures and devices when a tunable system response is required. When integrated with a structural system, they can produce higher variations in the dynamic response of the structure. In this thesis, vibration behavior of laminated-composite beam with MR Fluid is investigated.In most studies, shear strain across the thickness of MR layer has been considered as a constant value which does not precisely describe the actual shear strain field. Shear modulus of MR layer in... 

Finding the optimal heat integrated distillation column sequence is an utmost important optimization problem in process engineering. The frequently used approach in this area is to obtain a suitable sequencing candidate and then accomplish the heat integration based on the application of Pinch technology to finalize the design. This approach reduces the problem complexity at the expense of not necessarily reaching the best possible result. This work follows a genetic super structure approach to systematic and rigorous synthesis of optimal multi-component distillation sequences (including simple and thermally coupled complex columns) and simultaneously heat exchanger networks by using a... 

Complex networks science have become the major method in the modeling of topological features of networks and graphs. Although file sharing Peer-to-Peer systems can be modeled by networks with un-weighted nodes and links, using these networks for Peer-to-Peer streaming systems have not led to a suitable model.In this research, we aim to model Peer-to-Peer streaming networks with weighted nodes and weighted links so that present the performance of nodes and the amount of streaming that is transmitted between nodes respectively. Due to lack of information about upload bandwidth distribution in networks we assume this distribution as uniform. Because of dynamics of network, this distribution... 

Single molecule magnets due to their magnetic tunneling effect and the interaction they have with an external magnetic field are used widely in quantum computing and also the storage of data with high capacities. Polyoxometalates that are used as counter ions for cationic single molecule magnets, are able to affect their spin-couple nature via a magnetic exchange and also have an influence on the crystal accumulation in order to change the magnetic property of the molecule. In this research the probability of sedimenting a cationic single molecule magnet, [Mn4O2(CH3COO)7(bipy)2]+, with the use of anionic polyoxometalates with Keggin structures has been investigated. Thus, the single... 

Over the past few years, various studies have demonstrated that the complex networks can be used to model the structure and functions of human brain. Some of these studies indi- cated that diseases such as Alzheimer, Epilepsy, and Schizophrenia can cause changes in this network. The main idea behind the methods proposed to analyze human brain’s behav- ior, is to identify regions of the brain with specific tasks. Recent studies show that multiple regions of human brain are involved in complex activities, so it’s important to detect their interactions. Using functional high resolution multichannel neurophysiological signals, like electroencephalographic (EEG) and magnetoencephalographic... 

In this thesis, the individuals’ decision process to achieve consensus in complex networks is modeled. A set of experiments with volunteered participants were run, in which the person is a node in a network with 35 other nodes who behave based on a prescribed model. Each participant is tested twice, once with and once without reward. Performance of individuals in the two experiment types and the effect of structural properties of the underlying network on the results are studied. It is observed that increase in the characteristic path length, diameter, clustering coefficient and local efficiency of the network adversely affects consensus.On the other hand, global efficiency and closeness... 

Nowadays, there exist many real networks with distinctive features in comparison with random networks. Social networks, collaboration networks, citation networks, protein networks and communication networks are some example of complex network classes. Nowadays these networks are widespread and have many applications and the study of complex networks is an important research area. In many applications, the “synthetic networks generation” is one of the first levels of complex networks analysis. This level has many applications such as simulation and extrapolation. Many generative models are proposed for complex network modeling in recent years. By the use of these models, synthetic networks... 

Mankind with it’s finite resources (Time, Energy, …) cannot make use of every accessible option in daily activities (such as buying items, listening to music and reading news), and is restricted to decide on a handful of them. Available options are increasing on a daily basis and these surplus of available options had an adverse effect; Thus, leading us to more baffling situations. As a result, need for external assistance appeared in decision situations. Considering exceptional computation power available to computers, a framework named Recommender Systems were developed. Recommender systems try to use their accessible data in order to make fitting suggestions to users. Personalization and... 

As the amount of data on the Internet grows, users face diverse options while searching for their desired information and items. Therefore, accessing what one is looking for, is usually time consuming and even impossible in some cases. In order to solve this issue, the goal of recommender systems is to offer recommendations which are compatible with users’ needs and preferences. One of the most important challenges of recommender systems is to improve the quality of recommendations. Recommender systems’ quality can be assessed using different metrics including precision, novelty and coverage. However, these metrics are inconsistent in some applications and improving one will cause a decline... 

These days, self-assembly is one of the most significant phenomena in chemistry and biology. Although There are some Experiments and Simulations which help us to understand self-assembly much more than before, their mechanism is poorly understood. As a result, Calculating Free-energy landscape could be a great development in this area.We use the Flat-histogram monte Carlo algorithm to calculate the density of states of a complex system. In this way, there is a comparison between the exact density of states of Ising Model and the same quantities that are obtained from Flat histogram Method. After that, there would be a combination of statistical thermodynamics and Graph theory toward drawing...