Sharif Digital Repository

Perovskite solar cells with 25.5% efficiency and fast and cheap manufacturing process are among the most promising technologies in this field to replace silicon cells. Despite the challenges of stability and toxicity to these cells, their manufacturing technology has recently shifted to the development of large-scale manufacturing methods in module dimensions. In the present study, the fabrication of perovskite cells in large dimensions to achieve the perovskite module has been aimed and studied that to achieve this, the method of large-scale spraying and printing using the vacuum system was used to create cell-forming films and, consequently, to make the final cell and module. To... 

In this research, modal incremental dynamic analysis (MIDA) has been investigated on three-dimensional structures with irregular plans. The MIDA method is an incremental static analysis that considers higher modes of the structure. In fact, it is a combination of modal pushover (MPO) and incremental dynamic analysis (IDA) methods that incorporate the advantages of both and is much faster than the IDA method. Compared to constant analyses, incremental analysis is more extensive in terms of results and response to earthquakes. Due to the uncertainties in the nature of future earthquakes, engineers use the IDA method to achieve a broader view of the structure's response under potential... 

The dynamic nature of today’s manufacturing industry, which is caused by the intense global competition and constant technological advancements, requires systems that are easily adaptable with new functions and technologies. In fact, a highly responsive manufacturing system is needed in which, introducing new products, adjusting system capacity with demand fluctuations and integrating new technologies with the existing ones are quickly possible.Reconfigurable Manufacturing systems (RMS) are a relatively new paradigm in industry that enable rapid adjustments of production capacity to changes in product mix and volume through their main characteristics including modularity, scalability and... 

Let be a field and R= [x0, . . . , xn−1] be the polynomial ring in n variables over the field . Let G be a finite simple graph with the vertex set V(G) ={0, . . . , n − 1} and the edge set E(G). One can associate a square-free quadratic monomial ideal I(G) = (xixj | {i, j} ∈ E(G)) of R to the graph G. The ideal I(G) is called the edge ideal of G in R. The graph G is called Cohen–Macaulay (resp. Buchsbaum, Gorenstein) over if the ring R/I(G) is Cohen–Macaulay (resp. Buchsbaum, Gorenstein).Let n be a positive integer and let Sn be the set of all nonnegative integers less than n which are relatively prime to n. In this thesis, we investigate structural properties of Cayley graphs generated by... 

Let K be a field and S=K[x0,…,xn-1] be the polynomial ring in n variables over the field K. Let G be a finite undirected graph without loops or multiple edges with the vertex set V(G)={0,…,n-1} and the edge set E(G). One can associate a squarefree quadratic monomial ideal I(G)=of S to the graph G. The ideal I (G) is called the edge ideal of G in S. It is an algebraic object whose invariants can be related to the properties of G and vice versa. The graph G is called Cohen–Macaulay over K (Gorenstein over K) if the ring S/I (G) is Cohen–Macaulay (Gorenstein). Let n ≥ 2 be an integer. The Grimaldi graph represented by G(n) is obtained by letting all the elements of... 

Because of environmental problems of fossil fuel energies and the rise in petroleum products, the tendencies to the renewable sources like wind power and solar power have been increased. In some particular applications like electric vehicles, satellites power system and all stand-alone unites that are using solar and wind powers are the only solutions. On the other hand, because of intermittent behavior of renewable sources, use of back-up supplies e.g. batteries are necessary to make a balance in power consumptions and productions. To interface between different ports some independent two port converters are used in traditional techniques. Multiport converters, used in... 

Grid simulator is a system that, as a voltage source, can produce various current waveforms in power grid at its output, and also as a load, can draw different currents of different loads from the power grid. Grid simulators may be used for testing power grid connected systems, such as chargers, power supplies, etc. In this thesis the system is consisted of programmable AC current source, dual active bridge converter and back-to-back grid-tied inverter. Dual active bridge can normally operate while the current source is in different modes of function, such as constant current, constant power and constant impedance. Depending on the mode of function, the current at the DC link can behave... 

With the increase of electric energy demand, one of the human concerns is to create the infrastructure for the production and transmission of energy in order to meet this need. Since the network must have the ability to supply the load during the peak load times, practically during the non-peak load times, many production capacities remain unused and their productivity decreases. One of the ways to reduce this problem due to the increase in penetration of batteries in the network can be the participation of battery banks to inject power into the network during peak load times. The goal of this project is to develop an 8 kilowatt-hour battery bank system that can inject 2 kilowatts of power... 

Breast cancer has been one of the main causes of women's deaths in recent years. Today, various methods are used to treat this disease, among which intensity-modulated radiation therapy is one of the most common methods. The goal of radiation therapy is to destroy cancer cells while protecting the surrounding healthy tissues. In left breast cancer, due to the proximity of the heart and breast tissue, we are at risk of delivering an excessive dose to the heart and increasing cardiac complications after the treatment. In addition, due to the irregular and unpredictable breathing movements of the patient during the treatment and the resulting uncertainty, we face more challenges. In order to... 

Increasing dynamics of mobile users intensifies the Doppler effect and degrades the performance of the communication system. Considering Fourier kernel-based modulation, in this research, we focus on dealing with the Doppler effect and compensating non-ideal communication channel response suffered from the Doppler-delay spread. In the first step, we study Zak transform and present a new transform for 2-D representation of time signals. This mapping is a well-known transformation that can be considered as a generalized discrete-time Fourier transform in the field of signal processing and can be used to represent a signal in the delay-Doppler domain. After providing a new 2-D transform, we... 

Molecular communication (MC) is a relatively new branch in telecommunication science. This branch is designed to transmit information in small environments (about nanometers). Applications of molecular communication include identification of abnormalities, detection of cancers, etc. The smallness of the transmission environment has caused new challenges and areas in this field. One of the unique features of MC with no parallel in classical wireless communication is chemical reactions: different types of molecules can react with each other and form new types of molecules in the medium. This feature of MC poses a challenge in macroscale MC since equations describing chemical reaction with... 

Intensity-modulated radiation therapy is a well-known technique to treat cancer patients worldwide. A treatment plan in this technique requires decision-making for three main problems: selection of beam angles, intensity map calculation, and leaf sequencing. Previous works have investigated these problems sequentially. In this research, we present a new integrated framework for simultaneous decision-making of directions, intensities, and apertures shape, called direct angle and aperture optimization, and develop a mixed-integer nonlinear mathematical model for the problem. At first, the problem's single-objective model is established using the quadratic dose penalty function. After that,... 

Over the past decade there has been dramatic increase in fossil fuel’s usage; As a consequence, world now faces problems such as: air pollution, climate change, global warming and ozone layer depletion. In addition, depletion of the fossil energy resources is growing as a serious issue. Renewable energy(RE) sources are the most promising solution to these problems. Global investment in clean energy was increased by 16% in 2014 and solar power is anticipated to become the world’s largest source of electricity by 2050 .The German government has planned to achieve a goal of 8 percent renewables for gross power consumption by 2050 .RE is still more expensive than traditional one and faces a... 

The application of deep learning algorithms in the processing of telecommunication signals is increasing. One of the issues in this area is the automatic recognition of radio signal modulation. Recognizing the type of signal modulation as the first stage of baseband signal processing on the receiver side is a key issue in military and civilian applications. The problem with classical algorithms for solving this problem is their strong dependence on channel characteristics and factors resulting from the transmitter and receiver being non-ideal. However, modern algorithms based on deep neural networks have been able to make the model somewhat resistant to these factors. However, the detection... 

Optical impairments, as a challenging obstacle in optical communication systems, have been under deep attention of optical engineers in recent years. These impairments can be divided into two categories of linear and nonlinear impairments. Dispersion is a significant linear impairment leads to broadening of the optical signal and interference between transmitted symbols during detection. Nonlinear impairments such as cross-phase modulation (XPM) and self-phase modulation (SPM) also distort the transmitted signal through the fiber, causing interference at the receiver and degrading the system's performance. An appropriate solution for compensating optical fiber impairments is to utilize... 

The use of protons and charged particles such as carbon in the treatment of cancerous tumors is one of the new methods of external radiation therapy. Proton therapy can achieve almost the same tumor dose coverage as traditional photon therapy with a greatly reduced dose to the normal organ. The radiation deviations caused by the magnetic field are an effective factor in reducing the dose of vital organs without sacrificing the dose coverage of tumors; Therefore, a new method of proton therapy, called magnetic field-modulated proton therapy, has been proposed, in which the Bragg peak positions of proton beams can be modulated under the cover of predesigned magnetic fields inside cancer... 

Wideband mm-wave radars are gaining popularity in automotive applications due to their superiority in harsh weather conditions, high distance resolution, precise velocity measurement, and superior spatial resolution. The primary purpose of this thesis is to design and implement a voltage-controlled oscillator for 77GHz automotive radar applications.Phase noise -as one of the most crucial specifications in VCO design- Phase noise improvement techniques as well as harmonic engineering methods are delineated. Also, an Ocean-based code for ISF simulation is introduced and developed to obviate the need for additional signal processing software so that simulation speed increases... 

This project is dedicated to design and implementation of a 77 GHz Power Amplifier for FMCW automotive radar application. Design of this type of Power amplifier faces several main challenges. The first challenge is due to the limits of technology used for implementing the power amplifier design (CMOS 65nm), for example the low breakdown voltage of transistors forces us to use low supply voltage. The other challenges are high frequency effects and complexity of design in mm-wave frequency. however, there are phenomena which dont have any important effect on output results in low frequency, but we should consider those when designing Power Amplifier in mm-wave frequencies.In order to... 

With the advancement of automotive technology, the use of automotive radar for collision avoidance and pedestrian detection has been increasingly become universal. In this thesis, our goal is to design a dual-band radar antenna for obstacle detection and a 5G omnidirectional antenna for communication purposes in self-driving cars. We will first introduce the automotive radar and its operation. Next, the FMCW radar, which is simultaneously effective for speed, distance and direction estimation is introduced. Then we introduce the leaky wave antenna as the frequency scanning antenna. This is realized in an SIW waveguide technology. The main issue in this part is the achievement of high... 

Thanks to the recent advances in the semiconductor technology and transistors’ miniaturization, design and implementation of millimeter-wave circuits is no longer a dream. As instance, transistors of 65nm CMOS technology are characterized to have cut-off frequencies higher than 200 GHz. This, along with the wide band-width available in millimeter-wave, has pushed the IC design engineers to mm-wave circuit design.In this project, different types of automotive sensors will be discussed. In the following, after a brief comparison of typical radar systems, a receiver front-end based on FMCW radar system specifications will be designed. Keeping in mind the required specifications for maximum...