Sharif Digital Repository

In this research with Finite Element Methods in ABAQUS, numerical modeling has done in three-dimensions, which can be used to determine the effect of different factors on the surface settlement. Also, various factors such as geotechnical conditions, tunnel diameter,tunnel depth, the impact of the thickness of the segments and the amount of eccentricity of the structure relative to the longitudinal axis of the tunnel considered in this study. Face Pressure Supports, and Grout Injection Pressures are taken into account, too.Tunnel drilling causes a change in the displacement area and creates a changing zone around the tunnel. In this regard, not only adjacent buildings will be affected by... 

Natural disasters, such as earthquakes and hurricanes, can strike without warning, resulting in a range of destruction from structural damage to loss of life. For this reason, research on structural control, which provides a new basis for design of structural systems against winds, earthquakes, waves, and traffic loadings, become of interest in civil engineering. This thesis focuses on using fluid dampers as a passive energy dissipation device. Viscous Fluid Dampers (VFD) are the most commonly used passive energy dissipation devices that are manufactured in various forms. However, the orifice type of Viscous Fluid Damper (VFD) is considered for structural applications. In this thesis, the... 

Nowadays, frequency synthesizers are widely used in many modern devices due to the ever-increasing growth of electronic circuits and their applications in various aspects of life. Imaging devices with security applications in the millimeter-wave frequency band is one of the mentioned applications. To prevent crowds at checkpoints and facilitate traffic, these devices need to monitor people's security at the highest possible speed. Furthermore, significant bandwidth is required to increase image quality. Therefore, using frequency generators with high-speed frequency sweep ability is a great advantage. In this thesis, a digital frequency generating chip with 1GHz bandwidth is designed using... 

Nowadays, micro systems are one of the most important scientific and industrial tools and become very important. Most of these systems are working based on deflection of a micro beam. As a result, studing performance of micro beams and controlling them have significant importance for science and engineering.Amoung micro beams cantilever and clamp-clamp beams, which are actuated by electrostatic or piezoelectric actuators, are very applicable. For example, micro cantilevers are used in Atomic Force Microscopy, Microswitches, acceleromiteres, and micro clamp-clamp beams are employed in micro mirrors and Grating Light Valves.In this research, a micro cantilever actuated with a piezoelectric... 

Optical Communication is a promising technology in access networks because of bandwidth hungry application like videos. So fiber Optic is an important candidate as a media in networks. There are different methods of modulation for transferring data through a channel. Among all, Orthogonal Frequency Division Multiplexing is a method which used in most wired and wireless systems. Recent researches show that OFDM is also a good approach for optical communication.
In this thesis we concentrate on hardware implementation of digital part of an Optical OFDM transceiver. In the first step we ignore the effect of optical channel and design and simulate the transmitter and receiver. After that we... 

The integration of radar and communication functionalities into a unified Joint Radar-Communication (JRC) system offers enhanced spectral efficiency and reduced hardware complexity. Recognized as a key enabler for next-generation wireless networks, JRC systems require a careful balance between radar and communication demands, where waveform design plays a pivotal role in achieving this equilibrium. Although waveform design has been extensively studied separately in radar and communication domains, the requirements of modern networks necessitate a unified approach that simultaneously addresses the needs of both systems. This thesis advances waveform design methodologies for JRC systems,... 

Morphology and alignment of endothelial cells (ECs) have great influence on plaque formation. These alignments are based on the cyclic strains and wall shear stress (WSS) on the arterial wall. In the present study, cyclic strains and WSS are investigated to predict the secondary plaque locations downstream of the primary stenosis. Therefore, left coronary artery (LCA) with its branches to left anterior descending (LAD) and left circumflex (LCX) are 3D located on a virtual sphere to consider the cardiac motion. Stenoses are placed at the beginning of the bifurcation with varying degrees from 40% to 70% based on diameter reduction. Healthy coronary is also constructed to compare with those of... 

The thesis opens with a discussion of the distinction between some of the classical and the constructive notions in mathematical analysis. There then follows a description of the three main varieties of modern constructive mathematics: Bishop’s constructive mathematics, the recursive constructive mathematics of the Russian School, and Brouwer’s intuitionistic mathematics. The main purpose of the thesis is to prove the independence, relative to Bishop’s constructive mathematics, of each of the following statements:There exists a bounded, point-wise continuous map of [0, 1] into R that is not Lebesgue measurable.If µis a positive measure on a locally compact space, then every real-valued map... 

In this study، a novel frequency multiplier chain for wideband millimeter-wave applications at 28 GHz is presented. Millimeter-wave imaging systems require high frequency and wide bandwidth to accurately detect hidden objects. Various methods have been proposed to increase the frequency of generated signals, but in the meantime، frequency multiplier structures exhibit better performance in terms of bandwidth، power consumption and, harmonic rejection. These circuits are widely used in High-frequency telecommunication systems such as 5th generation mobile services. To design a frequency quadrupler، two multiplier stages based on the improved quadrature Gilbert structure were used. Generating... 

Breast cancer is one of the most common cancer types and is the leading cause of cancerrelated death among females according to American Cancer Society statistics. Breast screening and early detection is the most effective method of management and treatment of this disease. Currently, several imaging systems for breast cancer detection are being used among which microwave imaging has caught the attention of many as a promising tool for early breast cancer detection. Microwave imaging is considered as a non-invasive, relatively low-cost, Fast, convenient, and safe method for breast cancer screening. this research aims to implement a 3D imaging system that operates based on the microwave... 

In this thesis, a low-power low-phase-noise 28 GHz voltage-controlled oscillator for 5G applications is presented. At first, to select the best structure in terms of FoM, various types of inductors and transformers have been designed and EM simulated. The class-C structure which leads to the highest FoM is chosen eventually. In order to increase oscillation amplitude and reduce phase noise while preserving FoM, a high-frequency noise filter is presented. This filter which is based on a λ/8 microstrip transmission line has solved the conventional filter problems e.g. narrow bandwidth, coupling with oscillator inductor and practical implementation issues.The oscillator is designed, EM... 

In this thesis, the design of a fully-integrated Millimeter-wave Broadband power amplifier in TSMC 0.18 µm CMOS technology is studied. The Darlington cell with cascode topology was adopted as the power cell to improve the maximum available gain of transistors in standard 0.18 µm CMOS technology to make it eligible of operating at Ka band. Furthermore, by proposing a new topology as an improved Darlington-cascode with intermediate inductor in the Darlington pair, the improvement in flat power gain at Ka band and more importantly, in available power gain of active element at high frequencies of the Ka band is achieved. The proposed power amplifier is a two stage structure with the driver stage... 

The blood pressure (BP) is one of the most vital signs to monitor human health. Hypertension is a major public health problem that is associated with morbidity and mortality. In the past decades, the number of people with hypertension disease has been increased. According to Ministry of Health, 54 percent of hypertensive patients are unaware of this health threat. Therefore, accurate and continuous measurement of BP is essential for its prevention and treatment. Traditional non-invasive methods of BP monitoring use an inflatable cuff, which causes discomfort due to occlusion of the artery and can not be used continuously. Numerous studies have attempted to present methods without using a... 

In this study, we present the front end of receiving end of an ultra-wideband imaging system designed for mobile users, operating within the 10 to 20 GHz frequency range with a 10 GHz bandwidth. The choice of this specific frequency and bandwidth aims to achieve the requisite range and lateral resolution for desired imaging outcomes. Additionally, the selection of this frequency band is motivated by its favorable performance in various weather conditions and its non-ionizing nature within the microwave spectrum, prioritizing human health in the research endeavor.Despite the advantageous characteristics associated with this frequency band, designing within such a broad bandwidth and frequency... 

Automatic classification of different sleep stages is an important and challenging research topic in the field of biomedical signal processing. The methods proposed so far for this purpose have been based on multi-channel physiological signals such as electroencephalogram , electrooculogram, and electromyogram . These signals can provide valuable information about the individual's sleep pattern and stages, but their use in a home environment is limited due to the need for complex equipment and specialized skills. Therefore, the development of a sleep stage classification method based on a single-channel signal that can achieve this goal with high accuracy without the need for complex... 

In this dissertation, the application of frequency and space diversities in radar target parameter estimation are investigated. On this basis, multi-frequency signal is used to improve the range resolution, array structure is used to increase the angle estimation accuracy and the merger of the multi-frequency signal and array structure are used to increase the maximum number of targets that can be uniquely identified.Considering the desirable properties of multi-frequency signals such as high bandwidth efficiency, high range resolution achievement without chip length decrease and …, there has been increased interest in the vast area of research on the design of such signals that has... 

Target recognition techniques based on micro Doppler phenomenon are popular because they are applicable even on low resolution radars, in contrast to other techniques such as High Resolution Range Profile (HRRP) which need high resolution in range or angle. Usually, main purpose of such techniques is generating robust features against target initial state, velocity, aspect angle, etc. rather than features which exactly identify a target. Main approaches in the literature are based on time-frequency transforms (TFT) such as spectrogram in order to generate features to classify targets, but in this thesis, we propose a totally different method using Recurrence Plot for generating features... 

Toll Pricing as a means to relieve traffic congestion has received significant attention by transportation planners recently. Inappropriate use of transportation networks is one of the major reasons that cause congestion in networks. Toll Pricing is a method of traffic management which guides the traffic flow to proper time and path in order to reduce the total delay in networks. This thesis investigates a method for solving Minimum Toll Revenue problem in real and large scale transportation networks. The objective of this problem is to find tolls that simultaneously cause users to use the transportation network effectively and minimize the total toll revenues that must be collected.... 

In this research, we have used green tea polyphenols as green reductants for reduction of graphene oxide. Furthermore, for the first time, the presence of some metals such as iron, tungsten and copper in the efficiency of reduction is investigated. XPS spectra indicate that iron can be considered as one of the best choices for helping polyphenols in the reduction process. Hence, we used AFM, XPS, Raman spectroscopy and I-V diagram to characterize graphene oxide reduced by polyphenols and iron. In recent years, hydrazine has been recognized as one of the standard reducing agents for effective reduction of graphene oxide. In our analysis, it is found that the conductivity of our reduced...