Sharif Digital Repository

With the proliferation of mass media such as smartphones and the use of social networks, the exchange of video data between users has increased, and according to forecasts in the coming years we will see significant growth in the amount of this data on mobile networks. In this dissertation, we examine the effect of sending video packets via LTE and WiFi and try to calculate two parameters that affect the quality of experience, namely the probability of interruption and the amount of delay. The modeling results show that if the packets are optimally routed to these two paths, there is about a 15% improvement in the probability of interruption. Sending packets from two separate routes Although... 

Semi-structured documents are a new type of textual documents which has gained a lot of attention nowadays to itself. A specific document modeling for boosting classifiers is needed more than ever which reflects major document specifications. The main goal of this thesis is presenting new adaptive model based on semi-structured documents features. We also aim to use some problem solving approaches such as Statistical approach, Machine Learning and few Algorithmic solutions. In some cases 10% precision optimization can be seen compare to the best approaches available nowadays  

Tuned Mass Damper (TMD) is one of the most popular device implemented in structures in order to control the motion induced by wind. The performance of TMD has correlation with its design, which is depending on the Structure dynamic properties as well as the specifications of lateral loading. During the earthquake since the both of the mentioned parameters will be uncertain, hence, the reduction of TMD’s sensitivity to its design parameters is vital. In this regard, in 2012, Maurizio De Angelis et al. tested the unconventional TMD – it has a large mass ratio – and corroborated its merit. The results were limited to short structures with linear behavior. This research not only verified... 

Recently, a new generation of machine learning tasks, namely data generation, was born by emerging deep networks and modern methods for training neural networks on one hand, and the growth of available training data for training these networks on the other hand. Although distribution estimation and sampling were well-known problems in the science of statics, deep generative models can properly generate samples from real world distributions that common statistical methods fail in them e.g., image and music generation.Due to these improvements in deep generative models, researchers have recently tried to propose deep generative models for datasets with complex structures. These structured... 

The aim of this research is presentation of A framework to select the appropriate combination of retrofit and insurance in order to reduce earthquake losses. The vulnerability of buildings to earthquakes can lead to significant damage to owners and residents of these buildings. It is imperative that appropriate measures be taken to reduce these adverse effects before the risk occurs. Some of these measures, such as seismic retrofit of buildings, can reduce the vulnerability of buildings and, consequently, financial and human losses. Some other measures like insurance, in the event of an earthquake, can reduce the financial losses incurred by owners and residents of vulnerable buildings.... 

The Gaussian mixture (cardinalized) probability hypothesis density (GM-(C)PHD) filter is a closed form approximation of multi-target Bayes filter which can overcome most of multi-target tracking problems. Limited field of view, decreasing cost of cameras and its advances induce us to use large-scale camera networks. Increasing the size of camera networks make centralized networks practically inefficient. On the other hand, scalability, simplicity and low data transmission cost has made distributed networks a good replacement for centralized networks. However, data fusion in distributed network is sub-optimal due to unavailable cross-correlation.Among data fusion algorithms which deal with... 

Nowadays, researchers working on classifiers which are designed to predict minority class. In this work, we attempt to improve fraud detection performance, with minimum possible complexity. In this regard, by incrementing model sensitivity to minority class samples, we solve the problem of model ignorance to these instances. Moreover, by using clustering, we cluster similar inputs based on their features, and split each class to smaller bins. Then with considering the fact that, prediction probability threshold influences the final performance, we define statistical hypothesis testing exclusively for each cluster to evaluate predictions with expected range. In this method, model is not... 

In recent years, an increasing demand of water on one hand and over-exploitation of groundwater resources on the other hand lead to the unsustainability of these resources worldwide. Due to arid and semi-arid climate in Iran, groundwater resources play an essential role in food production, as well as domestic and industrial water supply. Increasing population, scarcity of surface water resources, and effects of worldwide and regional climate change have resulted in over-exploitation of groundwater resources in the country and threatens the water security of the nation. The present study aims to estimate groundwater sustainable yield, examine effects of spatial and temporal scale, water... 

Rotary machines including gas turbines have been widely used in many industries like gas reducing pressure stations and power plants. Blades are important components of gas turbines which are subjected to failure due to different kind of damages like crack occurrence. There are various reasons for crack occurrence and its propagation in blades. Presence of crack in the blades may lead to major failure, which in turn, result in emergency shutdown of the system. Therefore condition monitoring is employed to check the possibility of failures. In recent years, condition monitoring techniques have been developed to prevent unnecessary shutdown of the systems. The present thesis aims to... 

Toxic flow occurs when a trader with confidential information trades with a market maker without that information. The trade price is such that the market maker is obliged to provide the desired liquidity by taking the risk of loss for the order. The PIN (Probability of Informed Trading) is widely used to calculate the amount of toxic flow in a market and evaluate the market condition in terms of informed trading. However, Easley et al. (2012a) propose a new alternative method based on high-frequency data and daily orders called VPIN (Volume-Synchronized Probability of Informed Trading), and we apply it in the Iran stock market. This method can give the market makers the ability to predict... 

In this thesis, we investigate the statistical performance of the array processing algorithms. Theoretical performance analysis leads to better methods that outperform the existing algorithms. Besides, analytical performance analysis, results in a more profound understanding of the nature of the considered problem. First of all, problem of covariance matrix estimation, in the non-Gaussian signal case will be investigated. We will focus on a nonparametric estimator which relies on the sign of the data to estimate the covariance matrix on an element-by-element basis. It was known that, sign estimator may give invalid covariance estimates in higher dimensions of the data. We prove this fact in... 

In this thesis, a new passive method suitable for Geolocating LPI radars is introduced. The method uses two Electronic Support (ES) receivers placed on a fast moving platform (e.g., an airplane or a satellite). The proposed method has a high processing gain, which makes it highly suitable for very weak LPI signals. The processing gain of the method was analytically derived and illustrated with simulation to determine if the proposed method can detect LPI radars in much lower SNRs compared to regular time-frequency LPI detection methods. Also, the resolution of the proposed method in both range and cross-range direction in radar location finding was analyzed. Furthurmore, the effect of the... 

The compute-and-forward (CMF) method has shown a great promise as an innovative approach to exploit interference towards achieving higher network throughput. Here, instead of recovering single messages, the relays attempt to reliably decode (compute) and pass an integer linear combination of the transmitted messages, referred to as an equation, to the destination. By receiving sufficient equations,the destination can solve the linear equation system to recover the desired messages.Two main challenges of the CMF methods are the computational complexity and the rank failure problem at the destination. In this thesis, to decrease the implementation as well as the computational complexity of the... 

Most of the seismic regulations in the Iranian design codes are adopted from the U.S. codes, while the severe earthquake rates with regards to the gross area and total population of Iran is 8.4 and 5.5 times the rates for U.S. respectively. In fact, Iranian rates are between the ones for U.S. and Japan which have up to 200% difference in prescribed strength level in their seismic codes. Poor construction quality regarding defected control in Iran adds to the problem. Therefore, the prescribed strength level of U.S. building codes and thus their target reliability index seems insufficient for use in Iran. Also, previous research has shown that the load and resistance factors in Iranian... 

Increasing the demands for different services over the Internet, need for modern network designs and protocols to meet the required necessities is more appreciated. Therefore GMPLS protocol which can guarantee the Quality of Service has been introduced. Afterwards code-based GMPLS networks have been introduced which can provide different services with multi length variable weight codes for multimedia applications. In order to investigate network behavior, a comprehensive traffic model is required.
In this thesis an accurate and efficient model for the discussed networks using state dependent queuing network theory is introduced. By calculating the steady state probability of network, it... 

Lake Urmia in northwest Iran is an important water body at the national and international level and plays a significant role in the natural, social, and economic aspects of life in the region. Unfortunately, as a result of natural and anthropologic factors, the lake has suffered a severe water decline in recent decades and was even on the verge of complete drying. Being aware of the catastrophic consequences of lake Urmia's desiccation, a megaproject called Urmia Lake Restoration Program (ULRP) aiming to revive the lake was launched in 2013. Failure in megaprojects is common and frequent in which a high level of uncertainty is one of the main contributing factors. The purpose of this study... 

The ultimate goal of this study is to provide a general framework for assessing the reliability of different layouts of marine structures. This reliability is a yardstick for determining the safety level of marine structures at any given time. Using this criterion, it is possible to prioritize structures for maintenance operations and, by performing appropriate operations, create a uniform level of safety for all marine structures in a region, or the best type of fixed platform arrangement for structural strength He chose economics and so on. This framework is flexible and expandable, which means that its generalization to various hazards and the various effects of these hazards is possible... 

Daily price limits are boundaries that regulators impose to control daily volatility in stock market. This paper studies the impact of an imposing price limit in Tehran Stock Exchange. To this end we use all the data about companies which were accepted in stock exchange and fara-stock exchange in 1392.In this year the price limit imposed on companies in stock exchange and fara-stock exchange are 4 and 5 percent respectively. Therefore, to estimate the effect of price limit we use the propensity score matching method and inverse probability weighting.The results indicate no significant differences between returns and trade volume between 4% and 5% price limits, but a significant difference... 

Using of physical safety devices such as pressure safety valves, are the most conventional methods to protect vessels against overpressure but operation of these devices have many negative effect on environment also they waste significant amount of valuable hydrocarbon materials. Relying on conventional safety devices needs a flare net to send excess gas to torch and in many cases essential equipments for flare net is so expensive and their maintenance are difficult thus reducing the size of flare net for a chemical plant is beneficial.
Application of new alternative device (HIPPS) is very helpful to reduce flaring load and releasing pollutant materials such as SOx and NOx. The main...