Sharif Digital Repository

Approximate Agreement (AA) is one of the most important issues in distributed networks in which non-faulty processes execute a voting algorithm to reach the values that are very close to each other. AA for Partially Connected Networks (PCNs) is very limited because a node may not have a complete view of the whole network which makes it difficult to reach the convergence. This research proposes a convergent Fuzzy algorithm for synchronous distributed networks in the presence of faulty or Byzantine processes. When each node receives a new value from its neighbors,it runs the convergent Fuzzy algorithm. If the received value is not in the expected range of values, the processor can discard the... 

Business Processes are a set of activities which is designed for produce specific output for specific customer or market. Nowadays business processes have a significant role in organizations and they progress to mechanized business processes and transform them to executable workflows. Existence of complex domains with particular requirements from one hand and scale of business projects on the other hand, make existing business processes, which only consider structure and flow of work, are not enough for fulfillment of organizational requirements. By provision of semantics into business processes, which Semantic Web technologies is used in them, business processes become more flexible and... 

After passing many iterations of tests, video games still suffers from major bugs after they’ve been released. One of these problems is the incompatibility between the video game and target audience’s computers. In this thesis, we have proposed a testing strategy by utilizing Cloud Computing infrastructure for video games and Deep Convolutional Neural Networks. We used a simple algorithm to make the graphical output of a video game partially deterministic and thus it’s possible for us to compare different instances of the game in Draw Call level. We’ve used two separate Deep Convolutional Neural Networks for 1. detecting visual artifacts in frames and 2. comparing pairs of Draw Calls for... 

The main goal of petroleum reservoir simulation is finding of Pressure (P) and Saturation (S) of fluid in different places of prose media environment of the reservoir in a specific time interval. In this project we will implement a distributed reservoir simulator of a cluster. In fact parallelization of reservoir simulator is finding a method to decompose the reservoir domain into some region and assigning each region to a computer in a cluster of parallel computers in order to minimize the total amount of dependency of regions to each other and messages between nodes in the parallel network according to fluid equation in the system and finaly minimize' the duration of simulation. In this... 

Cancer is a class of diseases characterized by out-of-control cell growth. Cancer is among the leading causes of death worldwide.Cancer modeling is increasingly being recognized as a powerful tool to refine hypotheses, focus experiments, and enable predictions that are more accurate.We investigate a three-dimensional multiscale model of vascular tumour growth, which couples blood flow, angiogenesis, vascular remodelling, nutrient/growth factor transport, movement of, and interactions between, normal and tumour cells. We constructed a hybrid multi- scale agent-based model that combines continuous and discrete methods.Each cell is represented as an agent. The agents have rules that they must... 

The emerging blockchain technology has introduced a new approach in today's industry, creating new opportunities in technical, financial, and economic domains. With the emergence of blockchain-based platforms such as Ethereum and the capability of smart contracts, the possibility of creating decentralized systems has arisen. One of the most popular decentralized systems in the realm of finance is crowdfunding platforms that assist technical and academic projects in need of capital for industrialization. Startups or research-academic projects secure the necessary funding by selling initial offering tokens to both small and large-scale investors. In this research, we aim to present an... 

The MP210 superalloy belongs to the category of multi-phase superalloys, designed for specific applications at high temperatures, such as components in gas turbine engines. However, its usage is limited due to hot fracture concerns at temperatures around 800 degrees Celsius. This research delves into the mechanism of hot fracture in this alloy. To explore this, the microstructural changes in samples subjected to hot tensile testing in the temperature range of 500 to 1000 degrees Celsius were studied using microscopic and microanalytical techniques. The yield strength and ultimate tensile strength at 500 degrees Celsius were 475 and 850 megapascals, respectively, decreasing to 105 megapascals... 

In the pas few years, the use of web-based education systems have grown exponentially spurred by the fact that neither students nor teachers are bound to a specific location and that this form of computer-based education is virtually independent of any specific hardware platforms. These systems can offer a great variety of channels and workspaces to facilitate information sharing and communication between participants in a course, let educators distribute information to students, produce content material, prepare assignments and tests, engage in discussions, manage distance classes and enable collaborative learning with virtual classroom sessions, forums, chats, file storage areas, news... 

Non-Fungible Tokens (NFTs) are unique assets on the blockchain that prove ownership of various digital assets. Presently, a wide range of assets, such as digital art, music, tweets, and virtual assets in the metaverse, are being traded. Since there is no reliable standard for valuing NFTs, identifying criteria and correlations for their valuation and understanding the influence of social networks on these assets is crucial. Two key factors are identified in this process: (1) opinions, thoughts, and feedback from real individuals, and (2) the content of the token itself. Since these factors represent different types of data—textual and visual—two distinct analytical approaches are proposed.... 

In this researh, we study the problem of profit maximization using viral marketing in social networks. In our model, the individual’s ultility value consists of two parts: a private utility and a value obtained by effects of other network members. Each member selects the service that maximizes its utility and Server can exhibit services in different qualities. First we focus on the problem from the Game Theory viewpoint and discuss on the existence and optimality of equilibrium. Next, we show that finding the best equilibrium is NP-hard. For the case of two services, we show that while P ̸= NP, no approximation algorithm with factor better than 2 exists for this problem. Finally, we try to... 

In 2014, Iranian government initiated “Salamat” universal insurance program, aiming to provide free health insurance coverage for the uninsured population. Consequently, more than 10 million individuals enrolled in the program, and insurance coverage rose 15 percentage points among the urban population. The purpose of this study is to evaluate the program’s consequences on healthcare utilization and mortality of various age-groups. To this end, we have estimated data on healthcare utilization from the results of “Households Expenditures and Income Survey” for years 2011-2017, and also used the data on the frequency of mortality of each age-group taken from the National Organization for Civil... 

Online question-answering communities, as reliable sources for exchanging experts' opinions, have specific rules to maintain their content quality. Due to their large number of users and posts, manual control and approval by administrators is not plausible, and these systems require solutions that are more scalable. The current dominant solution, i.e., the use of crowdsourcing and relying on user reports, has serious problems, including the slow speed of handling violations, the waste of time of users, and the discouraging feedback from the community towards new users. Although the automation of moderation actions via artificial intelligence methods would solve the existing problems, the... 

In this thesis, we study the treewidth of social networks. The importance of studding treewidth is for two reasons. The first is that for the graph with bounded treewidth, many optimization problems that are NP-hard in general, can be solved in polynomial or even linear time. The second is that the high value of treewidth in a graph, reflects some high degree of connectivity and robustness, which is an essential factor in designing many networks. But the problem is that determining the value of treewidth in a graph is NP-complete so, computing the treewidth of real complex networks is not feasible. We first review the related works and mention the weakness of the past works, then introduce a... 

For along time, analysis of financial markets is an interesting topic for mankind. There are different statistical methods to analyze financial time series. In this manuscript, financial markets are analyzed from network view point. Inference of hidden structures between companies of a market is merit information so we introduce different methods to infer
hidden network structure of financial markets. In addition, we will show that dynamic of network structure can provide important information about external sources of influence on financial markets. Actually, we show affect of political events on financial market of Iran. At last, we generalize diffusion concept at financial networks... 

The success of matrix acid production operations and its proper efficiency is one of the main challenges for oil and gas companies. The heterogeneity of the reservoir formation (especially the permeability difference) in the area around the well due to the presence of different reservoir layers results in the non-uniform distribution of acid among them and adds acidizing challenges. In order to improve production conditions, stimulation fluid transfer to the low permeability layer, which is the main target of acidizing. In this study, a new generation of chemical diverter, called Viscoelastic Surfactant, has been used. These materials have two components of elastic and viscous behavior, and... 

Today’s biggest IoT companies are built on the extraction of insight from data of sensors, and data processing has become crucial in IoT businesses. Nevertheless, the size of data which should be processed is growing significantly fast. The pace of the data growing has changed the nature of data processing in IoT. Today, IoT industries demand highly scalable and fault tolerant data processing architectures which can handle the massive amount of data. In this research, we presented a distributed architecture for scalable and resilient data processing based on the Liquid which is a nearline and offline big data architecture. We used the Reactive Manifesto to design the architecture highly... 

The final goal of knowledge management is the creation of knowledge flows in a way that they sway the organization towards its goals. A knowledge flow model must take into account all kinds of horizontal and vertical flows at different levels, as well as providing support for organizational processes and goals. Because of lack of a framework for knowledge flow modeling, most models presented by researchers only cover part of these requirements. A framework for knowledge flow modeling facilitates the design of a complete and comprehensive model by considering all aspects and levels of knowledge flow. Hence, in this research, a framework for modeling of knowledge flow has been presented which... 

Nowadays, the world is based on the interaction between individuals, groups and different systems. The actual networks that have a complex structure and behavior are called complex networks. Complex networks are one of the new knowledge that studies the connections. The complex systems represented as graph, with non-trivial topological features—features that do not occur in simple networks.With the vast development of computer networks, complex networks appear in different categories such as social networks, citation networks, collaboration networks and communication networks. Data mining is the process of exploring hidden knowledge in data bases and it has applications in complex networks.... 

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... 

In recent years with the growth and development of emerging technologies, one of the main challenges in various organizations is the issue of Business-IT Alignment programs at different levels of strategic, tactical, and operational. Many managers and experts in the field of information technology recognize the importance of this issue because of its broad effects on the development and maturity of the organization. However, they face various difficulties in creating actionable plans to achieve high levels of alignment. The main problem is the inability to measure the alignment degree index. This index is affected by various sub-indicators in various fields of business and information...