Sharif Digital Repository

Pile foundations suffered severe damages during the past earthquakes in all around the world. These damages were more severe in laterally spreading grounds and they mostly have been observed in gently sloping grounds and coastal areas. In these cases, Pile foundations not only are subjected to structures inertial loads and kinematic loads of liquefied soil but also lateral spreading intensifies damages. Thus, in the recent decade, several researches have been conducted to investigate the behavior of pile foundations in liquefiable and laterally spreading grounds, however, some uncertainties still remain in modeling of soil-pile interaction. In this study, the effects of liquefaction- induced... 

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... 

Anti-lock brakes car as one of the most fundamental and vehicle stability control system is considered. Solenoid valves, one-way valves, Accumulator, damper orifices and other components is a crucial role in the anti-lock system performance, so that the performance of the system and thus affect the dynamic performance of the vehicle. This is the most important part of the anti-lock brake System and These components are all new brake system.In this study a complete modeling of hydraulic control unit and obtain sufficient data to model the dynamic behavior of the hydraulic control unit to be seen. operators working in higher frequencies are weak and virtually reached saturation and efficient... 

In this work we have investigated the methods of providing quality of service in cognitive radio networks. At first, we have explained the various algorithms of providing BER quality of service in wireless networks. Especially we have explained those algorithms which are known as the distributed power control algorithms. Then we have introduced methods of using adaptive modulation and we have used this kind of modulation to provide delay quality of service in cognitive radio networks. We have done this by maximizing the sum of effective capacities of secondary links under the power constraints and also the interference constraints set by the primary receivers. Finally, we have introduced... 

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... 

Analog to digital converters are one of the most important component of Bluetooth and GSM receivers. The pipeline and Successive Approximation Register (SAR) ADCs are mainly used in these receivers. However, the pipeline ADCs consume lots of power and SAR ADCs suffer the resolution in advanced technologies. On the other hand, the Delta-Sigma ADCs are capable of achieving high resolution with a low power. So in this thesis, the various kinds and different implementations of Delta-Sigma Modulators are introduced. The system level design and the conversion between Discrete-Time Modulators and Continuous-Time Modulators are explained. The non-ideality effects such as limited gain and bandwidth... 

Nowadays, in the presence of different types of computer attacks and different methods of eavesdropping on network communications, nobody can deny the importance of cryptography. Hardware Security Modules that are specifically designed for this purpose are widely used as a fast and reliable tool for encrypting data in computer networks. In this project, using the common and well-known FPGA platform and by leveraging the reconfigurability feature of this platform and also by adding a network protocol detection module to the traditional architecture of Hardware Security Modules, a novel module has been designed and implemented that can encrypt and decrypt data in a communication network, at... 

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... 

In this thesis, study the design of a compact low-cost integrated time modulated array(TMA). In TMAs, a switch is used instead of a phase shifter, which reduces the area, complexity, power consumption and the final price of the array. The TMAs uses the switch as a control element for array weighting that causes beamforming and beam steering. For the lower cost, designed IC compacted as small as possible and use inexpensive CMOS 180nm technology of TSMC fabrication. Initially, maximum layout size forced 0.7 by 1.5 mm2. The proposed switch type is SPDT that one of its output paths terminated by a matched load and another end to a pad and then by a bond wire connected to an external board that... 

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... 

The issue of automation has always been a concern for humans over the years. Replacing humans with machines or intelligent software to perform various tasks can significantly improve the accuracy and speed of those activities. One of the long-standing aspirations of humanity has been the automation of driving. In addition to freeing individuals from the time-consuming task of driving, automating vehicles can also dramatically reduce road accidents. To achieve this goal, vehicles need to be equipped with various sensors such as radar, cameras, lidar, and more. Each of these sensors has its advantages and disadvantages, and as a result, all of them must be used for safe driving. In this... 

Nowadays almost all the research laboratories use femtosecond lasers, and Ti: sapphire laser is the most popular among them. Therefore, in this thesis, a Ti: sapphire pulsed laser with z-fold cavity with output of 50 fs and repetition rate of 100MHz has designed and simulated. Therefore, in the first chapter, introduction to the theory of ultrashort pulses and situation to create these pulses are presented. In addition, as regards to produce of short pulses, it is necessary to set laser in cw mode, in the second chapter we have investigated laser in cw mode. So, in this chapter, rate equations of gain medium, the stability zone of the laser, manner of removing astigmatism in the cavity,... 

It is generally accepted that Electronic Warfare has three distinct components: (1) electronic support (ES), (2) electronic attack (EA), and (3) electronic protect (EP). ES is included those measures taken to collect information about an adversary by intercepting radiated emissions. EA refers to attempting to deny adversaries access to their information by radiating energy into their receivers. EP includes activities under taken to prevent an adversary from successfully conducting ES or EA on friendly forces.
The function of Electronic Support Measurement (ESM) System is considered as a part of the first component (i.e. ES). After receiving emitted signals from various radars by ESM... 

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... 

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... 

In this study, we simulated and analyzed a plasmonic waveguide modulator based on single layer graphene. It includes a graphene sheet, which sandwiches between two layers of silicon dioxide. Then, some gates are arranged on either side of the waveguide on a periodic structure. When an electric field is applied perpendicular to the waveguide plate, the Fermi level of graphene under the gates, changes. Detailed analysis is performed by the method of lines based on Maxwell's equations along the propagation direction of the waveguide. Computation of the multi-gate device starts by examining the effect of Fermi level. Transmission coefficient of the magnetic-field norms of the modulator is... 

iN This thesis, Design and implementation of a low voltage, low power Delta-Sigma Modulator (DSM) is presented. System level considerations have been discussed thoroughly. In addition a systematic design flow in the context of continuous time delta sigma modulators is provided. While voltage-domain signal processing becomes more difficult in deep sub-micron processes, a finer time resolution is achievable. Time-domain quantizers can ameliorate the design challenges of flash quantizers which arises from lower supply voltages and higher fraction of comparator metastable region. VCO based quantizer such as voltage to frequency and voltage to phase considered as time domain quantizers can be a... 

Sigma-delta modulators have largely been implemented as discrete-time (DT) circuits because of their low sensitivity to circuit nonidealities, and their frequency scaling specification, however a continuous-time (CT) design offers significant advantage in the design of high accuracy, high speed analog to digital converters (ADC). A CT design allows for relaxed amplifier(s) bandwidth and power requirements, which enables the realization of high accuracy modulators with bandwidths of several megahertz at low power consumption. Furthermore CT modulators provide inherent anti-aliasing filtering which becomes especially important at low oversampling ratios. This thesis reports the design of a... 

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...