Sharif Digital Repository

As the transistors’ dimensions in integrated circuits shrink, according to Moore’s law, a number of challenges emerges that can decrease the benefits of scaling. One of the main challenges in deep submicron CMOS technologies is the delay in interconnects. In recent years, researchers have been looking into different methods to minimize the delay in interconnects. International Technology Roadmap for Semiconductors (ITRS) predicts that the input capacitance of a buffer will become in the order of 10s of aFs with technology scaling. This will give us the opportunity to transmit the data in electrical interconnects near the speed of light.In this thesis, a novel buffer is designed in which the... 

Several advantages and problems associated with technology scaling. One of the most important problems facing technology scaling is interconnects. As technology scales down wire delay becomes dominant. Optical interconnects has been subject of many researches for more than two decades to overcome this problem. The key idea behind near speed of light transmission (NSoLT) is that for buffers at the end of ITRS projections input capacitances could be as small as tens of atto Farads. Hence, voltage of the end of global wires could jump at the time of flight.
In this project, a global wire has been divided in to k segments in a way that data can be transferred with the speed close to the... 

Neutron Radiography is one of the non-destructive testing methods of materials and due to its special application compared to gamma or X-ray imaging, it is highly regarded and developed in the world. A special application of neutron imaging is the imaging of materials with a low atomic number, even when coated with a material with a high atomic number. Neutron Radiography has different methods for capturing and recording images by neutrons. Among these methods, the following 7 methods can be mentioned: Neutron radiography (film), Track Etch, Digital neutron imaging, Neutron camera (DR System), Image plates (CR System), Flat panel silicon detectors (DR system) and Micro channel plates (DR... 

Every year millions of people around the world die because of car accidents, most of which are caused by human faults. This has greatly increased the need for advanced driver-assistance systems (ADAS) and self-driving cars. Currently, driver assistance systems rely mainly on radar sensors and cameras to detect various objects and obstacles around the vehicle. Radar, due to its low lateral resolution, and Camera, due to its sensitivity to environmental conditions and lack of distance measurement, do not perform well alone. Therefore, we need light detection and ranging (LiDAR) that measures the distances from objects using laser light. Due to the micrometer wavelength of light, LiDAR can have... 

Since direct measurement of neutron energy, unlike measuring the energy of ionizing radiation, is difficult, and the use of indirect methods for detecting and measuring neutron energy with high resolution and acceptable efficiency are not possible, the neutron time of flight method is the only direct neutron energy spectroscopy method. This issue is considered and evaluated in two methods: direct and scattering neutron time of flight. For this purpose, we have considered the 241Am-9Be source. In this method, neutron velocity can be determined by measuring time. is the time for the neutron that travels at distance of . The next method is the dispersed neutron time of flight method, in... 

Most of the time there are three different materials in oil wells; Oil, water and gas. Measuring volume percentage and flow of the individual materials (phases) is an important issue, due to their critical role in extraction process control. Measuring tool should be able to measure flow and percentage of each phase in a case that they are separated (in deviated wells due to gravity). In addition, the measurement should be carried on in a high temperature and high pressure environment and in presence of corrosive substances. Most of previous researches on Multi-Phase Flow Meter (or MPFM) led to mechanical methods to measure flow and they usually use electrical impedance or permittivity for... 

In this work, the combination of a multi-scale finite volume and streamline methods is presented for subsurface flow modeling. The used multi-scale method in this work is the same with the traditional type of it in algorithm and formulation. However, because of using a new mesh structure for implementation of multi-scale finite volume method, the new method named by Staggered Mesh Multi-scale Finite Volume (SMMsFV) method. Using the staggered mesh has some advantages such as reducing the computational cost and increasing the accuracy of the multi-scale method. In the SMMsFV method, first the coarse grid and dual coarse grid are constructed on the underlying fine grid. Then, the basis and... 

Breast cancer is the most common type of cancer in women and the second cause of death among them. The chance of successful treatment would be significantly increased if the disease is diagnosed at its early stages. There are numerous methods to diagnose breast cancer. One of the most important methods is positron emission mammography (PEM).The main aim of this study is to investigate the feasibility of improving PEM images by considering the time of flight corrections and the penetration depth of the rays in the crystals.In this study, a commercial PEM system, Naviscan PEM, is simulated using the GATE software. In the first phase of the study, two opposing planar detectors are used to study... 

In this thesis a guidance algorithm is developed to control middle phase landing of a quadrotor on a moving platform. Middle phase guidance is consisted of approaching time, speed, and angle constraints. In the first step proportional guidance algorithms was studied. Then a six-freedom model of a quadrotor dynamic was developed. At the next step an appropriate guidance algorithm was developed to control a quadrotor for the mentioned constraints. Finally, the parameters of the algorithm were optimized by numerical methods. Monte-Carlo method used to validate this method. For this reason, 850 numerical simulations with random initial and final conditions were performed and the statistics...