Sharif Digital Repository

Cancer is an abnormal growth of cells which is one of the major cause of worldwide’s mortality. Circulating Tumor Cells (CTCs) are rare cancer cells released from the primary or metastatic tumors and transported though the peripheral circulatory system and spreads in body and seize healthy organs. Early detection of CTCs can help in overtaking the cancer, hence isolation of CTCs is an essential step for many therapeutics. In spite of its clinical potential, the isolation and detection of CTCs has been a challenging task due to its rare presence amongst other blood cells (as low as 1–10 CTCs per billions of blood cells), similarity to white blood cell in size and also variability in terms of... 

Solving the visual symbol grounding problem has long been a goal of modern aritificial intelligence. Due to recent breakthroughs in deep learning methods for natural language processing and visual interpretation tasks‚ the field now seems to be as near to achieving this goal as it ever was. Also recent progress in using recurrent neural netowrks (RNNs) for image description‚ has motivated the exploration of their application for video description tasks. However, while images remain static‚ interpreting videos require modeling complex dynamic temporal sturctures and then properly integrating that information into a natural language description. Recurrent neural networks can be both used to... 

In the era of the internet and with the emergence of online stores, the possibility of changing prices for these e-commerce platforms has become simple and virtually cost-free. This allows them to adjust prices optimally in response to environmental and surrounding factors, maximizing their revenue from product sales. This development has led to numerous applications of statistical learning methods, particularly online learning, in these markets. In this thesis, we explore the issue of online pricing from various perspectives. One aspect is that product pricing is based on their features, which can be numerous. This leads us to the use of online learning methods and statistical learning in... 

In this thesis, we consider the model of random interlacement on transient graghs, which was first introduced by Sznitman for the special case of Zd(d > 3) in 2010’s. in Sznitman’s case, it was shown that on Zd: for any intensity u > 0, the interlacement set is almost surely connected. The main result of this thesis says that for transient, transitive graphs, the above property holds if and only if the graph is amenable. In paticular, we show that in nonamenable transitive graphs, for small values of the intensity u the interlacement set has infinitely many infinite clusters. We also provide examples of nonamenable transitive graphs, for which the interlacement set becomes connected for... 

The increasing demand for autonomous vehicles and reliable communication protocols and hardware interfaces, such as CAN bus and USB, underscores the necessity for stable clock sources that maintain a low temperature coefficient (TC) over wide temperature ranges. This demand is particularly emphasized in applications such as wearables, network sensors, downhole devices, WSNs, and IoT, where long-lasting battery life and frequency-stable clock sources over a broad temperature range (e.g. -20 °C to 100 °C) are crucial. Traditionally, variations in frequency caused by temperature have been mitigated by employing off-chip components like crystals or ceramic based oscillators, but this approach... 

In restructured power system, the Independent System Operator (ISO) implements Security Constraint Unit Commitment (SCUC) for clearing of day-ahead market. In this project, SCUC is also uses for simultaneous clearing of energy and reserve market. Spinning reserve and of generating units and Interruptible Loads (IL) are considered as system operating reserves in the proposed model. Some of IL usage restrictions such as maximum load curtailed, maximum curtailment hour in a day, maximum length of each curtailment and etc is also considered. One of these constraints is interruption time (the time between ISO’s request and IL’s Answer) which is very difficult to formulate. Expected Energy Not... 

Turbulence can distort and corrupt the image in quite a few ways when light from a distance star or another astronomical object enters the Earth's atmosphere. It is inevitable that all images produced by any telescope on ther Earth are blurred by these distortions. Adaptive Optics is a technology used to improve the performance of optical systems by reducing the effect of wavefront distortions: it aims at correcting the deformations of an incoming wavefront by deforming a mirror in order to compensate for the distortion. The research work reported in this thesis presents a solution to the surface shape control problems in a Deformable Mirror system. Our first goal is to derive equations that... 

Analog to digital converters with different specifications are widely used in modern electronic circuits. The significant demand on pipeline converters in several low power applications is mainly due to their high speed and high resolution characteristics. Fast and simple design of analog circuits using CAD tools, is highly sought after by integrated circuit designers. In this thesis, pipeline analog to digital converters is studied and a CAD tool is proposed for transistor level design and optimizations. The main advantage of this design in comparison with the previous works is that the yield and power consumption are considered as optimization factors. The module operates in three parts:... 

This study investigates consumers’ response to changing the household electricity meter from single stroke case to three stroke case. Existence of different prices in different hours during the day is the advantage of three stroke electricity meters compared to single stroke ones. Electricity bill data of 19,742 subscribers, in Tehran Interior Region 2, during the period 1387 to 1393, has been used to evaluate this policy. Subscribers who always use only single stroke electricity meters or three stroke ones are considered as the control group; and subscribers who have experienced electricity meter change during the period are considered as the experimental group. Changing electricity meters... 

Identifying fractional systems and designing controllers for these systems is one of the leading challenges due to their limitations. Systems can have constraints on output, input, and states. These constraints make it difficult to design a controller. In this project, controller design methods for fractional-order systems with output constraints are investigated. A controller is designed for a strict feedback nonlinear system with unknown dynamics subject to asymmetric and variable output constraints, unknown direction of the controller, and unmeasurable states. To design the controller, the direct and backstepping technique is used and the Lyapunov barrier function is applied for the first... 

Considering the widespread applications of α-aminonitriles, their synthesis is of great importance. The Strecker reaction represents a direct and appealing approach for the preparation of α-aminonitriles. With the aim of developing a mild and convenient approach towards the construction of α-aminonitriles, numerous methods have been reported for this important process over the past few decades. These have been mostly related to the optimization of reaction conditions and the use of more challenging substrates including ketimines and ketiminium salts and design of novel and effective catalytic systems. Due to the various advantages of supported heterogeneous catalysts and in our aim to... 

Financial and monetary markets are appropriate areas of applying Chaos Theory. Firstly, current theories of financial and monetary economics state that economic and financial variables such as exchange rates and stock prices are stochastic, so forecasting them is almost impossible. Secondly, if we find the hidden ordered and deterministic trends, we can achieve considerable profits. In this piece of research, we evaluate different methods and tests of detecting chaos in financial time series, and choose the most applicable methods to test financial markets’ indices. The main three indices of Tehran Stock Exchange, including Price, Finance and Industry indices, are examined. A sample of the... 

In small settling tanks, the sludges can be removed using perforated pipes. In this method the pipe is placed in the depth of a fluid and the lateral inflow through perforations lead to the outlet. Since there are few researches about hydraulic characteristic of perforated pipes, this research will investigate the hyadraulic characteristic of these pipes experimentally. One of the main objectives of these pipes is to use the entire lenghte of the pipe and also provide the uniform distribution of inflow. In the past studies, it was found out that inflow mostly comes through downstream perforations. The objective of this research is to find the distribution of discharge along the perporated... 

Textile industry is one of the biggest consumers of water in the world. Effluents of textile industry ordinarily have huge rate of dye compounds which are toxic and persistent in environment. In case which they did not treat and discharged in the environment, they can create cancer, poisoning and etc. Finding efficient, economic and fast method for treating of these effluents is an important factor on the management. Combination of ultrafiltration membrane and reverse osmosis processes, has taken into consideration as an efficient and fast method of treatment of textile effluents in recent years. One of the fundamental problems of this process is the high costs of operation and chemical... 

Nowadays, air pollution has become one of the biggest problem of large cities and has numerous negative effects on the environment and people's health. The present research examines how various types of pollutants are distributed in an urban environment, depending on the type of arrangement in different places. Razaviyeh town (including nine 15-story buildings) in the 9th phase of Pardis new city in Tehran has been studied three-dimensionally here. The dimensions of each building in this complex are 12 x 13.5 meters and their height is about 45 meters. Thus, the dimensions of the computational domain used are estimated to be less than 0.02 square kilometers. In this research, computational... 

Performance of reinforced concrete frames is highly dependent on detailing of the joint connections between its members, such as beams and columns. To have a good structural behavior, joints must show ductile behavior and designed based on the philosophy of strong column-weak beam. In the case of sever lacking ductility, strength or even rigidity of the connections, or having a weak column-strong beam, in the existing structures, there is a need for seismic upgrading of the connection. There are several ways for seismic upgrading of this type of connections.In this research, using steel plates for seismic upgrading of Concrete Beam-Column connections subjected to axial and cyclic loads has...