Sharif Digital Repository

In this thesis, we deal with the problem of direction of arrival (DOA) using single-snapshot samples taken from multiple source signals by an array of sensors. The array we are looking for in this work is a uniform linear array. There are many ways to solve this problem, including MUSIC and Prony. But one of the few methods that are able to estimate correctly with single-snapshot samples with incomplete uniform linear arrays in compressed sensing base algorithms. In the first step, we can estimate the data of a incomplete uniform linear array by arranging them in the form of low-rank Hankel matrices and using leverage scores and minimizing the weight nuclear norm. If the weight matrices are... 

The purpose of Direction-of-arrival(DOA) estimation in MIMO communication networks is to find the direction of signals that are mixed together and mixed with noise by using an array of multiple receiving antennas. DOA estimation is an important issue in array signal processing. The traditional methods for DOA estimation try to solve this problem with mathematical algorithms. For example, some of these methods are based on parameter estimation; such as DOA estimation methods using maximum likelihood estimation methods. Some of other traditional methods are based on subspace decomposition; Like the famous MUSIC method. The traditional methods of DOA estimation usually have a drawback, and that... 

In this thesis, the impact of both time offsets (TOs) and carrier frequency offsets (CFOs) on the average output signal-to-interference-plus-noise ratio (SINR) of OFDM systems is investigated with a novel and simple approach. First, TOs are partitioned into five cases based on how they occur. Then the mathematical models for different cases are derived. Considering CFOs and benefiting from the obtained models, closed-form expression for the SINR in each case is derived. It is proved that, SINR is independent of the observed subcarrier for the given TO and CFO. Besides, it is shown that the performance of the affected system deteriorates rapidly as the number of subcarriers increases. It is... 

Nowadays increasing demands of Bandwidth, higher data rate and efficiency cause a huge and novel challenges in communicational systems. One of the recent innovative idea to satisfy these increasing demands is Heterogeneous Networks. Compressive deployment of small cell in Heterogeneous Networks can fulfill a large number of satisfactory parameters in wireless networks. After first Presentation of Heterogeneous Networks idea, loads of structure based on them was proposed.In this Research we consider two outstanding and common structure for this technology and analyze the user association and resource allocation problem at their specific structure. The first one is equipped with simple... 

Rate splitting multiple access (RSMA) is an efficient approach that divides massages in space and power domain in specific time and frequency in order to control interference. Therefore, in this approach, the goal is linear precoding and power allocation on the transmitter side and successful interference cancellation (SIC) on the receiver side. On the other hand, integrated sensing and communication (ISAC) is an emerging technology in the new generation of communications (six generation) in which the process of sensing and communication can be done by same hardware and in a same frequency band so it can be more cost-effective. we can use RSMA in ISAC system in the applications which we aim... 

In recent years, base station coordination (also known as network MIMO) has been analyzed as a means of handling inter cell interference. In principle, all base stations might share their CSI and data through backhaul links. Unfortunately, the demands on backhaul capacity and computational power scale rapidly with the number of cells, which makes this approach unsuitable for practical systems. And these problems shift the researches to find ways for turning this idea to an idea that can be used in practical systems. One of the major changes to this idea can be dealing with local CSIT that there would be no need to exchanging CSIT among BSs. The other change that can make the idea to a more... 

The purpose of ranking Persian web pages is to retrieve the highest number of relevant documents related to the search query of Persian language users, with the minimum number of documents returned from the web. Information retrieval is one of the key issues in search engines. In this study, billions of documents were collected from Persian web pages, and due to infrastructure limitations, a few hundred million documents were indexed in a database like Elastic. Now, considering the user’s actual query, relevant documents should be retrieved from the indexed documents. To achieve this goal, a large Persian language model was needed. Existing large language models for Persian were not usable... 

Ethylene process is one of the most complex systems in petrochemical industries.The first section of the ethylene plant is the cracking furnace.The radiant section of predicted olefin furnaces is symmetrical with respect to a plane through the center line of the furnace and at an angle of 90° with the side walls. There are a total of 24 vertical radiant coils located centrally in the firebox wherein, bottom andside wall burners supply the heat necessary. Each four coils known as a ZONE so, as a result there are six zones, called zone A through F. Failures(rapture, creep, material degradation) rate on the coils decreases from zone A to zone F (A, B, C, D, E and F) respectively.From... 

For a Banach space E and a compact metric space (X, d), a function F : X → E is a Lipschitz function if there exists k > 0 such that ∥F (x) − F (y)∥ ≤ kd(x, y) for all x, y ∈ X.The smallest such k is called the Lipschitz constant L(F ) for F . The space Lip(X, E) of all Lipschitz functions from X to E is a Banach space under the norm defined by ∥F ∥ = max{L(F ), ∥F ∥∞}, where ∥F ∥∞ = sup{∥F (x)∥ : x ∈ X}.Recent results characterizing isometries on these vector-valued Lipschitz spaces require the Banach space E to be strictly convex. We inves- tigate the nature of the extreme points of the dual ball for Lip(X, E) and use the information to describe the surjective isometries on Lip(X, E) under... 

The rapid development of scientific areas in this modern era makes the process of finding new field of research slow and laborious for prospective scholars. Thus, having a vision of the future could be helpful to pick a right path for doing researches and ensuring that it is worth to invest in. This thesis seeks to predict research trends by using link prediction approaches on keywords network and discusses about the performance of various algorithms in different situations. Moreover, for the last part of the experiments, novel link prediction algorithms are proposed by the author, enhances the accuracy of prediction results. The data set collected from Sciencedirect and Scopus by a strong... 

Wind power is site dependent and is by nature partially dispatchable. Furthermore, good wind sites are far from grid. Due to these problems, and along with the existing limitations in the transmission networks, a comprehensive analysis over an extended time is needed to properly explore all potential wind sites for wind capacity allocation. This problem is computationally expensive and decomposition methods are required to break down this problem. Here Benders decomposition approach is used, which is a popular technique for solving large-scale problems, to decompose the original problem into a master and a subproblem. The master problem is a linear problem, which allocates wind capacity to... 

Single nucleotide polymorphs, There are changes caused by a mutation in a nucleotide in the Dena sequence. Mononucleotide polymorphisms are the most common type of genetic variation. Some of these changes have little or no effect on cells, while others cause significant changes in the expression of cell genes that can lead to disease or resistance to certain diseases. Because of the importance of these changes and their effect on cell function, the relationships between these changes are also important. Over the past decade, thousands of single disease-related mononucleotide polymorphisms have been identified in genome-related studies. Studies in this field have shown that the expression of... 

In the past few years, many research works on the controllable integration of metal nanoparticles and metal-organic frameworks were done, since the obtained composite material shows a synergism effect in catalysis and photocatalysis, drug delivery applications, gas, and energy storage, as well as sensing. For the first time, in this study, we employed template-assisted growth to synthesize Au-HKUST-1 Nanocomposite. XRD analysis entirely confirms that employing this strategy in synthesizing Au-HKUST-1 was wholly successful, and the plasmonic properties of this nanostructure were studied via UV-visible spectroscopy. In the course of synthesis, gold nanoparticles with 70nm diameter were... 

Age-related macular degeneration (AMD) is the most common cause of vision loss in those aged over 50. There are two main types of AMD, Wet and Dry form. Wet AMD is more severe though more treatable. There are three conventional treatments for AMD including laser therapy, surgery and intravitreal injection of anti-VEGF into the eye. Delivery of drugs to the posterior segment of the eye is still challenging and several implants and devices are currently under investigation for their ability to stimulate the retina, producing visual percepts. The application of intravitreal bevacizumab (Avastin) has expanded tremendously from the time of its introduction into ophthalmic care since 3 years ago.... 

In analyzing the structural organization of many real-world networks, identifying important nodes has been a fundamental problem. The network centrality concept deals with the assessment of the relative importance of network nodes based on specific criteria. Central nodes can play significant roles on the spread of influence and idea in social networks, the user activity in mobile phone networks, the contagion process in biological networks, and the bottlenecks in communication networks. High computational cost and the requirement of full knowledge about the network topology are the most significant obstacles for applying the general concept of network centrality to large real-world social... 

Decision making often has different effects and results with unequal importance. Most of classifiers try to minimize the rate of misclassified instances. These classifiers assume equal costs for different misclassification types. However, this assumption is not true in many real world problems and different misclassification types have different costs. These differences can be applied by introducing the cost in the process of learning. In this manner, total cost of misclassification will be the evaluation metric of classification. In order to apply this metric to the problems, new learning algorithms are needed. Cost-sensitive learning is the related area of machine learning which deals with... 

Traditional classification techniques of machine learning assume that data have stationary distributions. This assumption for recent challenges where tremendous amount of data are generated at unprecedented rates with evolving patterns, is not true anymore. Classification of data streams has become an important area of machine learning, as the number of applications facing these challenges increases. Examples of such data streams applications include text streams, surveillance video streams, credit card fraud detection, market basket analysis, information filtering, computer security, etc. An appropriate method for such problems should adapt to drifting concepts by revising and refining the... 

Classification is one of the most important problems in machine learning area. Reliable and successful classification is essential for diagnosing patients for further treatment. In many applications such as bioinformatics unlabeled data is abundant and available. However labeling data is much more difficult and expensive to obtain. This dissertation presents a novel transductive approach for the development of robust microarray data classification. The transduction problem is to estimate the value of classification function at the given points in the working set. This contrasts with the standard inductive learning problem of estimating the classification method at all possible values and... 

Concept drift is a challenging problem in the context of data stream processing. As a result of increasing applications of data streams, including network intrusion detection, weather forecasting, and detection of unconventional behavior in financial transactions; numerous studies have been conducted in the field of concept drift detection. In order to solve the problem of concept drift detection, an ideal method should be able to quickly and correctly identify a variety of changes, adapt quickly to new concepts, in the presence of limitations of memory and processing power. In this thesis, a new explicit concept drift detection method based on ensemble classifiers has been proposed for data...