Sharif Digital Repository

In this thesis we study circuit models and their step responses of the Interconnects. First of all, we solve the Maxwell’s equations for lossless line to understand the models deeply and then generalize it for lossy lines. Only with equations that govern the model, one can realize the regions in which his model behaves correctly. After that, the transfer function of a single line with arbitrary load and source impedance is derived, based on lossy segmented model. Knowing this, we introduce different methods of getting the inverse Laplace of transfer function and their pros and cons. Finite pole approximation, Fourier series harmonics, and changing variable are various methods to simplify... 

Cogeneration or combined heat and power (CHP) which simultaneously produces electricity and heat energy from sequential use of single fuel source, has been introduced increasingly for industrial, commercial and residential applications due to its high energy efficiency. While the capital costs of CHP systems are comparatively higher than the conventional systems, their proper selection and optimal sizing and also optimal operation could result in shorter capital recovery period and lower cost of energy supply. Essentially the technical, economic and environmental performances of CHP system are closely dependent on its design and operation strategy. This project presents an optimization... 

Sampling is so deep-rooted in our habits that it usually takes place unconsciously. A large number of books and articles have been published in this field. The connection between sampling and quality control is the reason that many industries have focused their attention on sampling; however, only a few numbersare familiar with bulk material sampling related issues. Describing this theory along with its seven errors is the main object of this research. Using this theory, characteristics of the lot of interest was analyzed. Creating necessary conditions for assuring sampling correctness is very critical and if these conditions cannot be provided, implementing some part of the theory issues... 

Many studies has been focused on extracting structural and behavioral properties of complex networks in recent decade. Online Social Networks (OSNs) are one example of complex networks. Nowadays with rapid growth of OSNs such as Facebook and Twitter, the study of OSNs has become an interesting research area. Many of recent OSN studies studied friendship networks. Friendship network is a binary unweighted network, and all of its links have the same importance. But, in reality not only all friendship links are not representative of social interactions, but also the social links have a variety of intimacy, intensity, and etc. So, all links should not be considered equal. Recently researchers... 

Many real-world communication systems such as Internet, online social networks, and brain networks can be modeled as a complex network of interacting dynamical nodes. These networks have non-trivial topological features, i.e., features that do not occur in simple networks such as lattices or random networks. The tremendous growth of Internet and its applications in recent years has resulted in creation of large-scale complex networks involving tens or hundreds of millions of nodes and links. Thus, it may be impossible or costly to obtain a complete picture of these large networks, and sampling methods are essential for practical estimation of network properties. Therefore, in this thesis, we... 

Ahwaz is typical of a polluted city. It ranks in the third place after Tehran and Esfahan and with the onslaught Of the dust storms it has acquired the dubious distinction of 1st polluted city in the world. The pollution status of this city was investigated from May 2012 to May 2013. 110 air filters were collected during this period. The air filters were analysed with AAS and INAA techniques. with the use of AAS we measured the concentration of Cd, Cu, Fe, Mg, Mn, Ni and Pb elements. For the use of INAA method on the air filters we used two reactors of MNSR at Esfahan and the 5MW research reactor of Tehran. We managed to measure twenty five elements of Al , As , Br , Ca , Ce , Cl , Co , Cr ,... 

Localization of a neutron point source using a designed computer program namely “MCMC-MATURE” is performed. The computer program analyses several detector responses in some certain media by Markov Chain Monte Carlo (MCMC) method and a new iteration algorithm. Identification of the possible regions of source position would be found by analyzing the initial fluxes generated by mesh tally of MCNPX computer code. The designed computer program is capable to generate the flux between detectors. “Regular-Sequential”, “Irregular-Sequential” and “Non-Sequential” are three methods used for sampling the generated random number in two dimensions. Each sample multiplied by a sampling function and lead to... 

The running time of almost every algorithm in the graph theory depend on the number of edges. Thus, these algorithms are often too slow when the input graphs are dense. Therefore, it is useful to reduce the number of edges by sparsification. In fact, sparsification is the task of approximating a graph G = (V;E) by another graph ~G = (V; ~E) so that ~E E (j~Ej jEj) and ~G maintain a main prefixed property of G. Depending on these properties several notions of graph sparsification have been proposed. In this thesis we study a notion of sparsification that is called spectral sparsification which is based on the contributions of Daniel A. Spielman et.al..In this notion of sparsification... 

This paper presents some approaches based on data mining techniques to solve the prediction task of Computational Intelligence and Learning (CoIL) Challenge 2000. The prediction task of the contest is a direct mailing problem and the goal is to improve its response rate. The main issue in this competition is the incompatibility of the dataset in which the distribution of the classes of the target attribute is highly unbalanced. This in turn causes high error rate in identifying the minority class samples. Three different level methods including data-level, algorithm-level, and hybrid method are used to overcome this issue. The specificity and sensitivity criteria are employed to compare the... 

One of the funadmental problems in signal processing is finding the best sampling strategy of a continuous time signal, and then finding the best strategy for compressing the obtained signal samples. The sampling and compression steps are designed with the aim of minimizing the distortion of the reconstructed signal. The problem of finding the best sampling strategy has been widely studied in the signal processing literature. In particular, the Nyquist–Shannon sampling theorem gives a sufficient condition for perfect reconstruction of a continuous-time signal of finite bandwidth. Most of the signal processing literature deals with deterministic signals, with relatively less attention paid to... 

Combustion sources such as diesel vehicles are the most of the particular matter sources in ambient air. Near the tailpipe, exhaust is very hot, condense and have high velocity. This properties cause to need special methods and instrument to collect them. Numerously of combustion sources will emitted the VOCs, IVOCs, and SVOCs. This component mixed with ambient air and changing to particle phase from gas phase. Reaction between nitrogen oxides with sunlight cause to damage ozone layer and tissue in long time. Furthermore, breathe of VOCs gases cause to eye irritation, gastrointestinal effects, Damage to the nervous system, headache, dizziness, fatigue, vibration and loss of organ... 

Deep learning methods have become more popular in the past years. These methods use complex network architectures to model rich, hierarchical datasets. Although most of the research has been centered around Discriminative models, however, recently a lot of research is focused on Deep Generative Models. Two of the pioneering models in this field are Generative Adversarial Networks and Variational Auto-Encoders. In addition, knowing the structure of data helps models to search in a narrower hypothesis space. Most of the structure in datasets are models using Probabilistic Graphical Models. Using this structural information, one can achieve better parameter estimations. In the case of... 

The importance of optimizing the extraction process of available resources increases each day due to the increasing energy consumption and the lack of energy resources. Oil and gas are one of the most important sources of energy. Although existing oil and gas resources are thought to be sufficient to meet the growing energy demand for the next few decades, given the non-renewable nature of these resources and the growing demand for oil and gas, it will become much harder to meet the future energy demand. Many existing oil fields are now in the process of maturing, and the discovery of large new oil fields is rare. As a result, new technologies must be used in the future to meet this demand,... 

In examining protein-protein interaction networks, we often encounter similar and repetitive schemes. Examination of these designs, which often appear in the form of motifs and similar patterns, reveals important information such as the type of protein linkage and many of the internal similarities between these networks. The ability to recognize these similarities plays an important role in identifying the function of genes, recognizing the relationships between diseases, and making drugs. We know that exact algorithms for examining subgraph isomorphism are np-hard and time-consuming and infeasible in large networks; Therefore, in practice, approximate and heuristic algorithms are used and... 

One of the main challenges in image processing is the reconstruction of images from their samples in the discrete domain to obtain high quality images in the continuous domain. Visual signals in the continuous domain are usually represented by discrete or digital images. This reconstruction process may not be possible in general, and we need to set some specific constraints for this purpose, such as delimiting the signal bandwidth. In this dissertation, we consider the reconstruction of binary images (black and white). These images have infinite bandwidth due to the existence of edges, and thus, the conditions of the Nyquist-Shannon sampling theorem do not hold. Novel methods have been...