Sharif Digital Repository

We study the problem of preclustering a set $B$ of imprecise points in~$\Reals^d$: we wish to cluster the regions specifying the potential locations of the points such that, no matter where the points are located within their regions, the resulting clustering approximates the optimal clustering for those locations. We consider $k$-center, $k$-median, and $k$-means clustering, and obtain the various results. Then we study the higher order Voronoi Tessellations as an important concept in clustering area. Generalizing Lee’s inductive argument for counting the cells of higher order Voronoi tessellations in $\Reals^2$ to $\Reals^3$, we get precise relations in terms of Morse theoretic quantities... 

In traditional networks, network management was performed locally at the data layer by switches and routers. This approach made it difficult to make optimal decisions with a comprehensive view of the network. Software-Defined Networks (SDNs), by separating the control layer from the data layer, introduced a centralized decision-making unit in the network. This decision-making layer, equipped with overall network information, makes decisions that enhance the overall efficiency of the network. Software-defined networks provide customizable traffic control by storing numerous rules in on-chip memories with minimal access latency. However, the current on-chip memory capacity falls short of meeting... 

Intrusion Detection System (IDS) is an equipment destined to provide computer networks security. In recent years, Machine Learning and Deep Neural Network (DNN) methods have been considered as a way to detect new network attacks. Due to the huge amounts of calculations needed for these methods, there is a need for high performance and parallel or specific processors, such as Application Specific Integrated Circuit (ASIC), Graphical Processor Unit (GPU) and Field-Programmable Gate Array (FPGA). The latter seems more suitable than others due to its higher configurability and lesser power consumption. The goal of this study is the acceleration of a DNN-based IDS on FPGA. In this study, which is... 

In many real-world problems, graphlets in graph theory and simplets in simplicial complexes (SCs) are essential building blocks for analyzing topological structures. Graphlet analysis, which involves calculating the frequency distributions of graphlets, poses significant challenges in large networks. Two crucial concepts in this context are the graphlet frequency distribution (GFD) vector for entire networks and the graphlet degree vector (GDV) for individual nodes. Although previous studies have attempted to approximate the GFD and GDV, little attention has been given to determining the required sample complexity to achieve specific error bounds and confidence levels. This article addresses... 

In local transportation service companies, there is a need for estimation of arrival times (ETA) for customers. These companies not having the sufficient number of active online users, they are not able to obtain a proper estimation for ETA from that data. However, there are some overseas companies that have the established user base, and provide access to necessary data with a service fee. It is possible to solve this problem using the data which they provide.In this thesis, the problem of learning a hidden graph for the purpose of aiding local companies is explained and different aspects of it are introduced. In order to tackle this problem, first we define the idea of vertex separators,... 

Examining composite quantum systems through quantum thermodynamics, we face the new concept of binding energy. In this thesis, we are going to present a general definition for binding energy in quantum systems which covers any kind of interactions. First of all, we examine the possibility of energy exchange in a quantum system using quantum thermodynamics. In this theory, energy exchanges of an open quantum system may be divided in to two portions: heat and work; due to an accepted definition, heat is the portion of energy that is supposed to change entropy, while work has no influence on that. In this research, we restrict our calculations to the systems which are thermally closed and... 

In recent years, deep generative models have achieved incredible successes in various fields, including graph generation. Due to the advances made in graph generation by deep generative models, these methods have shown numerous applications from drug discovery and molecular graph generation to modeling social and citation network graphs. Graph generation is an approach to discovering and exploring new graph structures and has been attracting growing attention. One of the most challenging applications of deep graph generative models is molecular graph generation since it requires not only generating chemically valid molecular structures but also optimizing their chemical properties in the... 

The realization of key goals in quantum technologies— such as the simulation of quantum processes— requires methods that control the system’s dynamics and preserve the quantum properties of the system, despite the presence of system-environment interactions. Optimal coherent control theory is a well-known technique to achieve this goal. In this method, by using an appropriate framework, the control fields are designed to steer the dynamics toward a specific process or gate, when they are applied to the system. To determine the similarity between the dynamics, fidelity or distance measures are commonly used. Optimal control is performed by optimizing a cost functional defined by these... 

With the explosion of mobile smart devices, many computation intensive applications have emerged, such as interactive gaming and augmented reality. Mobile edge computing (EC) is put forward, as an extension of cloud computing, to meet the low-latency require- ments of the applications. In mobile edge computing systems, an edge node may have a high load when a large number of mobile devices offload their tasks to it. those offloaded tasks may experience large processing delay or even be dropped when their deadlines expire. Due to the uncertain load dynamics at the edge nodes, it is challenging for each device to determine its offloading decision (i.e., whether to offload or not, and which... 

In this thesis, a real-world project scheduling problem that has been less addressed previously was examined. After a general review of the literature on the subject and a presentation of the existing classifications in the literature on the problem of project scheduling with limited resources, the problem under study was defined. In existing project scheduling models, project activities are first scheduled and then resources and equipment are allocated and leveled, while project scheduling and equipment planning are two inseparable categories, and the integration of these two can have a significant impact on project costs. After modeling the aforementioned problem, two meta-heuristic... 

Immensity and profundity of mathematical logic have provided an opportunity for its interconnection with other branches of science, one of which is computer science where theory of dependent types and lambda calculus lounges amongst the area of their overlap. The former has been engendered for the sake of deepening the connection between mathematical logic and programming. On the other side, lambda calculus which is a formal system in mathematical logic and computer science, developed as a tool for formal computations, could also be counted as a programming discipline. It is the objective of this thsis to study the two aforementioned fields with emphasis on unification of higher-order... 

In recent years, the usage of Internet bandwidth has been increased by emerging applications such as Video on Demand (VoD).As the popularity of VoD increases among the Internet users, some new problems like bandwidth limitations and congestion embark. For solving mentioned problems, Content Delivery Networks (CDN) has been introduced. Using CDN approaches either in ISP or organization is also known as Telco CDN. Generally implementing CDN approaches to process all requests either in ISP or organization can cause bottleneck. On the other hand, Software Defined Networks (SDN) could bring us new tools and opportunities which enables us to implement novel methods to confront these problems.... 

It is so essential to study a safe dynamics of agricultural mechanical equipment during duty stroke, plus getting a rich information about the nature of the soil under processing and in many cases there are associated simultaneous problems, so the main aim of this study is to create a safe working conditions for such specific equipment to extend their life time span as possible as it could. This study will predict an un-usual working circumstances for agricultural tools including plough of course depending on some automated technologies with fast response supported by smooth working conditions. Simply, the proposed Investigative system consists of a linear potentiometric element with... 

The main objective of this research is to provide a framework by which decision-makers can evaluate and compare alternatives for sustainable development planning under uncertain dynamic future considering the risk and uncertainty associated with human judgment as well as the uncertain future. This approach combines the Delphi method, fuzzy set theory, and a discrete multi-criteria method based on prospect theory (TODIM). TODIM (an acronym in Portuguese for iterative MCDM) method is a particular multi-criteria approach based on the prospect theory. A qualitative Delphi technique is used to identify a set of qualitative sustainability criteria and to rate the alternatives accordingly. The... 

Web service technology is becoming increasingly popular since it is very bene?cial in di?erent types of applications. Due to a dramatical increase in the number of developed web services, the service discovery process has become crucial for using web services e?ciently. Service is an adaptive, self-describing, modular application, which may be used in either web or an internal network. Service providers should o?er the services along with a description ?le called advertisement explaining the speci?cations and functionalities of the service. Traditional service discovery methods are based on syntax and keyword matching, which may not satisfy the requester’s desired requirements and will... 

The process of portfolio construction and optimization can be broken down into three main steps: selecting appropriate assets, allocating capital, and monitoring and adjusting the portfolio. This study focuses on evaluating the performance of the Hierarchical Risk Parity (HRP) method for capital allocation in investment portfolios, specifically in Iran’s capital market. The aim is to enhance the method's effectiveness by implementing alternative correlation calculation approaches, such as Wavelet and Chatterjee correlations. The study utilizes three different portfolios containing assets from the Tehran Stock Exchange, the US stock market, and the cryptocurrency market. The primary objective... 

Nowadays, adaptable, versatile and flexible nature of Flying ad-hoc Networks (FANETs) make them popular in many academic and practical fields such as real-time applications, civil applications, search and rescue operations, identification and logistics. FANETs are organized multi-UAV systems that can accomplish complex missions through cooperation and collaboration. The unique features of these networks, such as high mobility, low node density, high frequency of topology changes, and three-dimensional flight environment, create various challenges in communication, especially in packet routing. In this type of network, a subset of UAVs connects to the infrastructure, while the remaining UAVs... 

This thesis presents an integrated formal method for modeling and model checking of component based computing systems. Both components and coordination subsystems are modeled by a variant of standard labeled transition systems called record transition systems. A record transition system is a labeled transition system whose transition labels are records. We use records to model the concurrency of input – output operations in the ports of the system. The concurrency of the executions with respect to common transition labels are modeled by standard parallel composition operator and also a new defined operator called join which is analogous to the join operator defined to compose constraint... 

In this thesis, a new non-linear control synthsis technique (θ - D) approximation) is discussed. This approach achieves suboptimal solutions to a class of non-linear optimal control problems characterized by a quadratic cost function and a plant model that is a_ne in control. An approximate solution to the Hamilton-Jacobi-Bellman (HJB) equation is sought by adding perturbations to the cost function. By manipulating the perturbation terms both asymptotic stability and suboptimality properties are obtained. The new technique overcomes the large-control-for-large-initial-states problem that occurs in some other Taylor series expansion based methods. Also this method does not require excessive... 

Opportunistic networks are special ad-hoc networks in which nodes exploit any opportunisty of pairwise contact to forward packets, without requiring any fixed infrastructures. Routing in Opportunistic Networks due to intermittently connected, non-existence an end to end path between source and destination and with a dynamic topology is a challenging issue. There are several different routing approaches in deliver packets from source to destinations. This approaches can be divided into four categories: awareness approaches, Non-Awareness, direct Delivery and coding based. Use of awareness approaches can be more improved routing process. This category consists of two parts: Context-Aware and...