Sharif Digital Repository

Automatic theorem proving has been attractive in artificial intelligence (AI). The aim of the usual automatic theorem proving methods is applying of the mathematical logic rules to decide intelligently, and reasoning automatically. In contrast the aim of our research is to apply computers abilities and artificial intelligence methods to simulate human abilities to prove mathematical theorems. For this purpose, we invent a typed formal language (TFL) to describe mathematical theories. The language must be clearly computable and should cover the First Order Logic (FOL) and the usual mathematical sentences. Then some algorithms and inference rules to compare sentences conceptually are... 

Inlet flow of afterburners comes from the burnt products of the primary combustion chamber. The fuel is injected and the mixture is ignited to form a flame which is stabilized behind a flameholder in the afterburner. Flame stability stems from wake (recirculation zone) of flameholder. With the aid of high residence time of flow behind the flameholder reactants get the time to catch activation energy. Some parameters like oxygen content, mass flow rate, inlet temperature, and nozzle area ratio play an important role in afterburner combustion efficiency and flame stability. In this study we focused on afterburner combustion stability in GE J85-21 engine. This engine will be in service through... 

The Smith Predictor does not work for unstable plants; therefore a lot of modifications have been proposed in order to solve this problem. In this project, advantages and disadvantages of most of these methods are studied in a general framework and based on Diophantine equation and using pole-placement technique. a discrete control scheme for unstable processes has been proposed. This structure can be used for non-minimum phase and stochastic processes. Robust stability of the suggested control structure has been shown. Performance of the proposed method is compared with previous works through computer simulations and its superiority for robust stability, load rejection; set-point tracking... 

Petroleum contains a large variety of metal compounds with vanadium and nickel being the major metals. Some 6–34% of the total vanadium content is made up out of metallo-oxo-porphyrins, also referred to as petroporphyrins. Metalloporphyrins have long excited interest as oxidation and epoxidation catalysts. In the other hand the selective oxidation of sulfides to sulfoxides is of interest because of the importance of sulfoxides as synthetic intermediates in organic synthesis. A range of sulfides can be selectively oxidized to the corresponding sulfoxides in good yields using catalytic quantities of vanadyl complexes. Vanadium oxo tetraphenylporphyrin VO(TPP) catalyst is successfully applied... 

Miniaturized electroceuticals" (therapeutic devices capable of stimulating the nervous system to treat diseases) hold the potential to revolutionize medicine. Specifically, implantable medical devices designed for peripheral nerve stimulation have shown significant promise in treating a wide range of conditions such as chronic pain, inflammatory diseases, metabolic disorders (like diabetes), and gastrointestinal disorders. While efforts have been made over the past decades to miniaturize implantable medical devices for peripheral nerve stimulation, there remains a significant need to reduce the size of these devices to millimeter scale, while incorporating all the complex functionalities... 

In the present thesis, the issue of locating end devices in the LoRa IoT network is examined using the received signal strength (RSS) approach. Recent advancements in machine learning techniques have revolutionized the localization field, enabling researchers to achieve better performance in non-line-of-sight (NLOS) and multipath interference conditions compared to traditional methods such as RSS and time difference of arrival (TDOA). This research first aims to reduce the position estimation error by appropriately scaling the received signal strength values on the public Antwerp dataset and to obtain a trained model for real-time localization of end devices. After introducing an appropriate... 

Different parts of this research are focused on developing FO membranes and improving their performance. For this purpose, thin film composite (TFC) membranes with fixed composition of polyethersulfone/polyamide (PES/PA) have been used to investigate the effect of nanocomposites containing transition metal dichalcogenides (TMDs) on their performance. The support layer in all cases is PES, which is prepared through the phase inversion process and does not contain any nanofillers. The modification process takes place in the polyamide layer by dispersing the desired nanoparticles in the aqueous monomer solution necessary to form this active layer. Identification and characterization of... 

Multi-period Value-at-Risk (VaR) forecasting is important for risk management. Financial institutions especially commercial banks according to Basel Committee regulations for capital adequacy in “Internal Approach”, should forecast their VaR for multi-period horizons (longer than one day). The most conventional approach for forecasting multi-period VaR is scaling one-day forecasted VaR that is called “square root of time rule”; therefore most works in this area have been focused on forecasting one-day VaR. In this study, we review performance of a wide range of different methods in forecasting multi-period VaR. The results of our study show that historical simulation performs weakly in... 

Molecule of DNA is one of the most important biomolecule in cell which contains genetic information to supply the required proteins for body. Evidence shows prefered binding sequence for proteins exist to interact with proteins which this preference is determined not only by specefic chemical interactions between DNA and protein, but also specific suitable geometrical arrangements of DNA have important role to inding DNA oligomer and protein, such as winding DNA around histon to creating nucleosome is related to curvature and deformability of DNA. Thus knowing elastic behaviour and properties of DNA helps us to approach the answer of such questions. Despite the recent dvancement in labratory... 

The main effort of this thesis is to present a numerical method to simulate and implement a special type of controllers, called proportional-weighted integral (PWI) controllers. For this purpose, at first mathematical equations of the fractional order proportional-integral controllers have been investigated in the time domain, and then by generalization of these controllers, the PWI controllers are achieved. Next the discretization of these controllers are carried out and the performance of the controllers are simulated by means of this discretization and comparison between these controllers and the conventional PI controllers has been held. After that a method for estimation of these... 

Regarding recent progress in the field of decision theory and the discovery of the important factors in human decision making, it is suggested by researchers to build up models that take all of, or at least most of, those factors into account simultaneously. In this research, first, we present some important achievements in the field of decision theory then develop a model based on these factors. Therefore, we focus on influential factors in human decision making, especially recent ones in neuroeconomics and mathematical models are presented to describe their effects. Then a descriptive model is proposed and changed it to a prescriptive model by adding some assumptions and standard charts.... 

The frequency divider is one of the components of a frequency synthesizer. Regenerative frequency divider is one of the frequency division methods and is used in narrow band applications. In this thesis, the process of designing & fabricating Ka band and Ku band regenerative frequency dividers is reported. A bandwidth of 550MHz for the Ka band divider and 400MHz for the Ku band divider have been achieved. Multiple passive structures such as microstrip filters, Wilkinson power dividers and a waveguide-to-microstrip transition have been designed during the fabrication of the mentioned frequency dividers. According to the results of the simulations, the bandwidth of the waveguide-to-microstrip... 

The resistive pulse sensing (RPS) method based on the Coulter principle is a powerful method for particle counting and sizing in electrolyte solutions. This method involves measuring a current pulse that is produced as a particle transits a small channel, or pore. Throughout its development the technique has been expanded from detection of biological cells to counting nanoparticles and viruses, and even registering individual molecules, e.g., nucleotides in nucleic acids. This technique combined with microfluidic or nanofluidic systems shows great potential for various bioanalytical applications. An increasing number of production methods have been reported to make apertures, which have been... 

In recent years, significant attention has been given to methods for measuring micrometer and nanometer biological and synthetic particles using microfluidic systems. One such method is resistive pulse sensing, which is used to detect and count particles as well as determining their surface charge. This technique is based on Coulter's principle. When a micropore is placed in an electrolyte solution containing the target particles, a drop in electric current occurs as the particles pass through the pore. Electrodes on either side of the micropore allow for the analysis of the pulses generated by the particles. Tunable resistive pulse sensing enables the adjustment of the pore size, allowing... 

Delta-Sigma Analog-to-Digital converters have been positioned themselves as robust reliable converters so far. The magic Of extracting high resolutions from low bit ADC has made them popular between designers. Previously, the noise-shaping magic was used in high-resolution applications such as high-quality audio signal converters. However, as the technology scales and proceeds, these converters are approaching RF applications, too. Power and OSR trade-off limits this progress. To increase OSR in bandpass delta-sigma modulators, more power should be consumed to increase the quality factor of loop filters. In this thesis, a systematic approach has been utilized. An n-path filter is employed... 

In this thesis, we consider the problem of online conflict-free coloring for regions. First, we analyze online variant of the conflict-free coloring of intervals on the line, where each newly inserted interval must be assigned a color upon insertion such that the coloring remains conflict-free, i.e. for every point p in the union of the current intervals, there must be an interval I with a unique color among all intervals covering p. we present deterministic algorithm for achieving this goal which uses O(log^3⁡n) color. Next, we consider the online conflict-free coloring of nearly-equal axis-parallel rectangles in the plane and present a deterministic algorithms which uses O(log^12⁡n)... 

There are several methods for EEG state detection, and there are still many challenges. Switching Kalman Filter (SKF) is a suitable approach for state detection, which has been used in various applications such as QRS detection in ECG signal, apnea detection using ECG signal, and also hand path detection using EEG signal. Our goal here is to use Switching Kalman Filter (SKF) in order to detect changes in EEG signal, and in particular in sleep. In other words, we want to detect Sleep Stages. Here, detecting Sleep Stages will help doctors diagnose and treat diseases. There is a Kalman Model for each Stages of Sleep in SKF, that I model it with a AR model. In addition, SKF switch is a state... 

A grid simulator is a system for testing various types of grid-connected devices, such as inverters of renewable energy sources, chargers, power supplies, etc. In this project, the design and implementation of a 3 KVA three-phase regenerative programmable AC current source is presented. In the future, this structure can be used as a grid simulator. The topology used for the current source is a two-level three-phase AC to DC converter. The current source can operate in constant current (CC), constant power (CP), constant impedance (CI), and constant voltage (CV) modes. In the constant current operating mode, the user sets the amplitude and phase of the 1st, 5th, 7th, 11th, and 13th harmonics... 

In the first part of this thesis, the application of core-shell magnetic nanoparticles supported V(V), Mo(VI) and Mn(III) complexes in the catalytic oxidation and reduction reactions was discussed. A magnetically recyclable vanadium(V) catalyst was synthesized by covalent anchoring of VO(salen)Cl on silica coated Fe3O4 nanoparticles. These nanoparticles were efficient catalysts for selective oxidation of sulfides to corresponding sulfoxides with urea hydrogen peroxide in excellent yields. Leaching and recycling experiments revealed that the nanocatalyst can be applied for nearly complete oxidation of sulfides for at least five successive cycles. A manganese(III) complex was immobilized on... 

This research proposes a probabilistic framework for seismic risk analysis of industrial plants of oil infrastructure using reliability methods. The proposed approach integrates multiple probabilistic models and system reliability to quantify the seismic risk of the process plants. A chain of probabilistic seismic hazard and risk models is utilized for the risk analysis. The Monte Carlo sampling method is used to propagate the significant uncertainty in the hazard event, damage to components and its consequences, and the potential losses incurred by process plant. In each sample of the analysis, hazard models simulate the occurrence, magnitude, and rupture area and location of earthquake...