Sharif Digital Repository

Nowadays, microgyroscopes are among the most important products of MEMS. The production of small, precise and inexpensive gyroscopes has become possible as the result of recent developments in fabrication technology. In this thesis it is intended to introduce a new method for manufacturing more precise microgyroscopes regarding manufacture facilities. Using this new method, sensitivity and resistance of microgyroscopes are increased against noises which are primarily caused by vibration and rotation about undesirable axes. The rotational movement imposed on the gyro is detected through fluid flow within its torus channel. This transformation facilitates the measurement of the initial motion.... 

In this study, a newly designed needle trap device (NTE) containing modified nanosilica as sorbent is used for sampling and preconcentration of some polycyclic aromatic hydrocarbons (PAHs) from headspace of aqueous solutions. An inexpensive modifier, cis-9-octadecenoic acid (oleic acid), which contains a long chain, was used to modify the surface of the nano-scaled silica particles. The hydrophobic interaction between oleic acid and aromatic compounds was the preliminary evidence for extraction of these compounds. After adsorption of selected compounds, thermal desorption was, subsequently, employed to transfer the extracted analytes into a GC–FID. Extraction time and temperature, flow rate... 

Superconducting SQUID sensors are one of the most sensitive magnetic sensors that have been ever produced. Due to their high sensitivity, these sensors have many applications in different fields. Magnetic Imaging and far away targets detections are of these applications. In this project, a magnetic imaging system based on Superconducting SQUID sensors have been designed and implemented. In SQUID applications one of the most important problems is the cancelation of the unwanted fields including background low frequency and high frequency fields. In residential and urban areas the interference of Electricity network is considered as one of the major noise sources. While the high frequency... 

A high percentage of patients with lower extremitiy disability consists of those suffer from paraplegy, hemiparety, spinal cord injuries and chronic stroke. Currently, a wast variety of methods are used for gait rehabilitation of these patients. Beside physiotherapy and different types of exercises, gait trainer systems have been devloped and used recently to help patients to obtain their walking abilities. The main goal of this work was to design and develope a device to lift a patient from sitting position on a chair to standing position in a safe and balanced mode besides obtaining enough space for physiotherapist that can easily help the patient in gait training on treadmill, also to... 

Superconducting Quantum Interference Devices (SQUIDs) are one of the most sensitive magnetic flux detectors. According to their high sensitivity, these sensors have many applications such as magnetic imaging, magnetocardiography and magnetoencephalography. In this project we have designed and implemented a fluxgate based active shield that would be used in magnetocardiography. One of the main concerns in RF-SQUID applications is suppression of the low and high frequency noises. These noise sources includes earth magnetic force, humming noise and RF noise caused by cell phones. These sources could unlock RF-SQUID sensors and hence needs to be shielded. Low frequency noise suppression could be... 

The aim of this project is design and implementation of the “gradiometer RF SQUID base Vibrating Sample Magnetometer (VSM)”. Different sections of the system have been designed such as pick up coils, vibration system and electronic circuits. The piezoelectric crystal has been concerned for vibration system. At the first step, we have implemented the basic VSM system. In the basic system, voltage induces in two series opposite pick up coils and its output is recognizable via electronic circuits. At the second phase of the project, the electronic circuits of basic VSM system have been replaced with the RF SQUID gradiometer and its electronic circuits. Afterwards, the sensitivity and the gain... 

The Pulse Laser Deposition (PLD), Sputtering, Evaporation and Metal-Organic Chemical Vapor Deposition are the common methods for thin film fabrication. The mentioned methods are very costly for commercials application. Due to the importance of cost in large thin film fabrication, scientist tried to find a low-cost method. The low-cost non-hazardious Metal Organic Deposition (MOD), method which is based on chemical manufacturing method was developed. The type of the solvent and removal the destructive residual materials are the main challenge in this method. In this project, by utilizing acetyl acetone method, high quality MOD YBCO superconducting thin film has been fabricated and will be... 

Analog SQUIDs have limited slew rate and dynamic range and these problems make it hard to operate SQUID systems in unshielded applications like Bio-magnetic imaging and NDE. Recently by combining analog SQUIDs and RSFQ Logic, new class of magnetic sensors are introduced. These sensors have an acceptable sensitivity and very high dynamic range. On the other hand these sensors, Which are called Digital SQUIDs, can be directly connected to digital signal processing stages. In This work, for first time, a digital SQUID completely based on i-directional RSFQ was designed and optimized. using Bi-directional RSFQ, one can significantly simplify the digital SQUID circuit design and therefore... 

In recent years, due to various reasons, such as outsourcing, hardware security and trust have become a crucial issue and confrontation with hardware Trojan has become one of the important part of it. Widespread usage of reconfiguration devices in industry, due to various reasons like low cost design and short time to market, makes these devices appealing for inserting hardware Trojan. Additionally, reconfigurable devices are susceptible to soft errors. Inserting a hardware Trojan in a system by an attacker can leak some information or even cause the system to break down. In previous works, in order to detect hardware Trojan, some methods have been proposed which impose high area and... 

Memories today expose an all-or-nothing correctness model thatincurs significant costs in performance, energy, area, and designcomplexity. But not all applications need high-precision storagefor all of their data structures all of the time. This these proposesmechan-isms that enable applications to store data approximately in a phase change memory main memoryand shows that doing so can improve the performance and reduce the power consumption by proposing two mechanisms. The First allows errors in multi-level cells by reducing the number ofprogramming pulses used to write them. The second mechanism reduces the number of error-prone patterns in the content of data block through a lightweith... 

Design, simulation, optimization and manufacturing of an enzyme-based microfluidic biosensor has been carried out during this research to measure histamine concentration in a sample. The designed biosensor is composed of a micro-bioreactor to degrade histamine and yield hydrogen peroxide, and a chemical reactor to measure the amount of hydrogen peroxide, using chemiluminescence methods. The geometry of the bioreactor and chemical reactor is developed through comparison and optimization of several different geometries. In theory, the designed sensor can determine histamine concentration in a range of 10M to 1mM under one minute, with a maximum error of 5%. Designed biosensor is built using... 

Security of cryptographic devices lies amongst the most important issues in the field of hardware security. It is frequently seen that in the process of designing cryptographic systems insufficient attention is paid to the physical implementation details. This is happening while a lot of secret information is known to be leaked through side-channels such as power consumption, electromagnetic emission and execution time. Side-channel attacks are able to reveal secret keys by using these side-channel leakages. Additionally, side-channel attacks are one of the most powerful but low-cost attacks that put the security of cryptographic systems in vain. It can be claimed that the most dangerous... 

This study is aimed at simulation of double emulsion formation in a microfluidic double flow focusing device which consists of two cross-junctions connected serially. The water in oil (w/o) emulsions are produced in the first junction. In the second junction, water in oil emulsions are encapsulated by an outer aqueous phase to generate water in oil in water (w/o/w) double emulsions. Water in oil emulsions are formed in hydrophobic channels and water in oil in water double emulsions are formed in hydrophilic channels. A three phase numerical model, based on the VOF-CSF method, is developed for simulating the process of double emulsion formation. An adaptive mesh refinement technique is... 

Hardware Trojans have emerged as a major concern for integrated circuits in recent years. As a result, detecting Trojans has become an important issue in critical applications, such as finance and health. In this work, a trusted platform for detecting Trojans in FPGA bitstreams is presented. The proposed methodology takes advantage of increased Trojan activation, caused by transition aware partitioning of the circuit, while it benefits partial reconfiguration feature of FPGAs to reduce area overhead. Simulation results, performed for the transition probability thresholds of 〖10〗^(-4) and 〖2×10〗^(-5), show that this method increases the ratio of the number of transitions in the Trojan... 

There is an increasing demand from mobile users for higher bandwidth, lower latency, longer battery life and better quality of service. It is expected that the next generation of mobile networks standards which is called 5G meets most of these demands. It is expected that the enhanced features of the mobile networks can be achieved within the limited bandwidth which is offered by the regulators and therefore, one of the key challenges in the development of these new technologies would be the issue of resource allocation. Efficient allocation of frequency, time and power to different users is an important issue and therefore, one of the important areas of development in these standards has... 

Increasing demand of bandwidth in wireless communications systems led to excessive congestion in frequency spectrum. Since radio spectrum is an expensive and rare source, its efcient use is an important challenge. These limitations as well as increasing number of communications service users,necessitate the use of newer technologies that work efciently with numerous users. Device-to-Device (D2D) communications, full-duplex capability and cognitive radio systems are introduced for this reason. In the previous technologies, due to excessive self-interference (SI), full-duplex transmission has not been implemented. However nowadays technology allows self-interference to be attenuated up to 100... 

Despite the advancement of technology in the world still some parts of the work are done by human hands. Gloves that increase fingers force can cause less fatigue, greater accuracy and efficiency in carrying out their duties in person.Also patients with muscle weakness due to M.S. or apoplexy, or elderly people are unable to do the simplest tasks. A wearable robotic glove that can restore hand function can increase the quality of life for people with mobility problems. The aim of this research is to design, build and control a conceptual prototype of a flexible wearable robot to increase fingers force by cable mechanism; and in this glove, force and position control concurrently is done by... 

Congestive heart Failure (CHF) which occurs when the heart is no longer able to pump the blood sufficiently is a worldwide growing health concern. In the U.S. alone, an estimated 8 million people will be diagnosed with heart failure by 2030.Cardiac transplantation with limitations in donor availability, cannot solely resolve this global health concern. Therefore many patients must use alternative remedies, namely Artificial Heart and Ventricle Assist Device (VAD). The Left Ventricular Assist Device (LVAD) is a mechanical pump that is implanted in patients with congestive heart failure to help the left ventricle in pumping blood to the circulatory system. They are known to... 

Ever growing users’ demand for data traffic rate in mobile networks، the strict limitations on available spectrum، reducing operators’ expenditures for higher achievable revenue and also supporting significant number of simultaneous users in the network are among the most important drivers and motivations of operators to devise new structures in their current networks. One of the proposed structures aimed at offloading the traffic from cellular networks and responding to the requirements of 5th generation of mobile networks is direct device to device communications underlaying cellular networks. Interference management and proper frequency-time resource allocation should be taken under... 

Due to the expansion of digital system threats, trusted computation with a new approach for countering such threats has emerged. This approach is based on using a hardware module for implementing a trusted platform (TPM). TPM includes a chipset and the trusted systems core. Nowadays many of mobile computers do include this technology. This hardware creates trust using a trust chain and expanding this trust to other parts of the system. The starting point in this chain is the computer BIOS. BIOS is the first code that the system usually executes. One of the most powerful recent attacks on computer systems is to infect the BIOS and other firmware. One of such complicated attacks is the rootkit...