Sharif Digital Repository

By scaling the technology node, leakage power and process variations emerge as the two important factors to design a chip. Static power becomes more important when the number of portable devices which spend most of the time in the idle mode is increasing.Process variations lessen performance, reliability and lead to more leakage power. To mitigate these limitations multiple devices have been proposed to displace Bulk MOSFET.Among these devices we can name FinFET and CNTFET transistors. FinFET transistors due to their superior gate control in compare to Bulk MOSFETs transistor have shown lesser short channel effects, more scalability, more I_on to I_off ratio and lesser process variations.... 

Metal sheets are widely used in different industries such as ship building and pressure vessels. One of the most important things in these industries is to create the desired sheets through line heating process. Designing the heating lines in order to get the desired shape with the sufficient accuracy has always been a concern for the engineers in this process. In this research, different methods of designing the heating lines for creating special surfaces are discussed. By integrating the two algorithms called distance based criterion method and angle based criterion method in MATLAB, the heating path and its parameters are defined. These two algorithms can be used in order to predict the... 

The purpose of this thesis is designing and implementation of a Carry Skip Adder using CMOS traditional technology and Gate Diffusion Input technique (GDI). I present a carry skip adder (CSKA) structure that has a higher speed, lower energy consumption compared with the conventional one. The Gate Diffusion Input is a novel technique for low power digital circuit design. This technique reduces the power dissipation, propagation delay, area of digital circuits and it maintains low complexity of logic design  

There is a strong drive toward handheld communication devices with building blocks that are fully integrated in standard CMOS technologies. Although there are obvious cost, size, and repeatability advantages, it is particularly challenging to implement fully integrated power amplifiers with no external matching in standard CMOS under the large supply variations and harsh load mismatches present in handheld devices. This Project deals with the front-end of an Integrated RFID Reader for the UHF band. The bottleneck of the design is the design of a fully on-chip Power Amplifier. In this thesis, a new method is introduced to increase transistors breakdown voltage in a class E power amplifier.... 

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... 

A Radio Frequency Power Amplifier was designed for IS-95 standard in 0.18μm / 1.8V CMOS technology. In order to increase output voltage swing and protect gate oxide of devices, pseudo-differential cascode topology was exploited. Bondwire inductors with exact modeling were used to tune out parasitic capacitances. A low-pass, L match impedance transformation network, realized using bondwire inductors, was used at output of power amplifier. An impedance transformation network design process was developed which considers the quality factor of inductors, from the first step. Also having examined the nonlinearity phenomena in power amplifiers, a fast simulation or measurement method was proposed... 

Preventing critical damages to structures and hence saving the lives and money is an inevitable work which a designer has to do. During the earthquake, huge amount of energy applies to the structure and finding a way to reduce transfer of this energy to main structure is crucial. For this purpose, Structural Control systems may be used. Metallic Dampers are one of those systems which absorb the earthquake input energy by having nonlinear deformations. In this Thesis, one type of this dampers which is innovated by Estekanchi, have been studied .Indeed, this damper is a connection between bracing and main frame. In this damper a U shape part acts as a sacrificing portion and absorbs energy by... 

Since that pathogenic bacteria have a predominant role in different aspects of human life such as clinical analysis and spread of contagious disease, food quality control and monitoring of environmental microbial infections, the aim of these studies is design and construction of electrochemical and electro-optical biosensors based on nanomaterials employing specific aptamer and antibody for detection of different bacteria in various real samples. An impedimetric biosensor based on nanoporous gold (NPG) was presented in the first part of the thesis for detection of Salmonella typhimurium as one of the main food- borne pathogenic bacterium. Three-dimensional structure of NPG was synthesized... 

As one of the key technologies for high performance electronic devices, composite solders have been recently developed to improve thermal and mechanical properties of solder joints. In this study, accumulative roll bonding (ARB) process was used as an effective alternative method for manufacturing high-strength, finely dispersed, void-free and highly uniform Sn-Ag-Cu/CeO2 nanocomposite solders. Microstructural investigation of nanocomposite solders revealed that homogenous distribution of CeO2 nanoparticle has been achieved and the eutectic as-cast morphology of the solder changed to recrystallized fine grained structure. As a result of severe plastic deformation during rolling, brittle and... 

Energy and the environment issues are among the most important concerns of the present age. Global demand for energy is growing rapidly and energy demand is projected to double within the next 15 years. However, today most of the energy consumption comes from fossil fuels, which have limited and unstable reserves and are among the sources of environmental pollution. Hence, the production and conversion of clean energy from renewable sources is considered as an intelligent solution to significantly reduce dependence on fossil fuels and protect the environment. Fuel cells, metal-air batteries, and water electrolysis are among the simplest, most efficient, and most reliable technologies among... 

Foil gas bearings are compliant surface, self-acting hydrodynamic bearings that use ambient gas as their working fluid. They do not require external pressurization and are typically constructed from several layers of sheet metal foils. In high-speed, high-temperature applications the GFB’s have the advantage of developing higher load capacities than with fixed geometry gas bearings. Since GFB’s have a complex structure consisting of a spring-like substructure with an overlying flexible surface, there exists a great variety of permutations on any given design. At current work presents a 1D model for GFB with couple solving Reynolds and Euler-Bernoulli beam equation. This mean top foil assume to... 

Knee arthritis is a painful disease from which millions of people around the world are suffering. One of the main causes of osteoarthritis and joint damage that starts from a young age, is that bones around the knee are not in a straight line. As a result, this situation causes additional pressure to the knee. This should be corrected with surgery. There are two procedures for this operation, a conventional method and a customized method. In conventional method, surgical planning is based on 2d X-ray images and plates are formed and fixed approximately at the desired location. This method is not precise enough and may cause problems for the patient. A new developing method, is that all the... 

In this research application of Ionic Polymer Metal Composite (IPMC) as actuator in a deformable ring capable of locomotion is studied. Such a deformable ring moves as a result of gravitational force acting on its body when its shape changes. A deformable robot made of IPMC can be used in exploration, search and rescue missions in future, where using conventional robots with rigid bodies and actuators is impossible. Large deformation induced by small stimulating voltage, low stiffness and the sensing characteristics that in future work can be used in feedback control make IPMC a good choice for such an application. In this work first a model for IPMC is introduce that can be used in... 

In this treatise, the effect of type of macrocycle ring on the final structure of the complexes which made from them was investigated. For this purpose, by changing the 15-membered benzylic macrocycle with two pyridine pendant arms (2p), which was studied in our previous experiments (the effect of the position of the nitrogen atom of the pyridine ring in the side arm and the type of metal ion in the geometry of its complexes), two new macrocycles by adding a naphthalene rings instead of benzylic ringsin in 2p and increasing the ring size from 15 to 17 members, Lpy-naph and Lpy-benz were symthesized respectively. The molecular formula and structure of Lpy-naph and Lpy-benz were confirmed by... 

DIRECT reduction is a process for reducing iron ore in the solid state. The product is in the form of sponge iron. This can be used directly as a raw material for steelmaking in an electric arc furnace. MIDREX process produces more than 60 percent of global DRI production. Because of high potential natural gas and iron ore resources in Iran and also lack of scarp, MIDREX direct reduction process is feasible. The main function of the MIDREX shaft furnace is to generate sponge iron from iron ore. The solids flow downwards by gravity and the reducing gases flow upwards in counter current, while the corresponding chemical transformations occur. Physical phenomena in the reactor could be... 

The primary purpose of this study is to perform nonlinear behavior simulations in the compaction and forming of metal powders and their alloys and investigate their behavior in the plastic state. Powder compression is one of the methods of producing metal parts with high precision and improved mechanical properties, which is why it has been considered in addition to its need in the industry.There are various methods for performing these simulations, including multi-scale methods with optimal performance. Given that only the use of high-scale methods or only low-scale methods will have problems and disadvantages in such simulations, multi-scale methods will be a good alternative in which both... 

Direct Metal Deposition is one of the methods of Additive manufacturing that has seen the most spread in recent years. In this method metal powder is directed towards the free surface of the workpiece through a nuzzle, and is simultaneously heated to become molten in a melting pool by a laser beam and begins the deposition process. One of the parts that make up a DMD system is powder feeding nuzzle. These nuzzles usually encounter a similar fundamental problem: that the effect of gravity on the stream of metal powder and the carrier fluid causes this stream to deviate from its intended position. To prevent this, nuzzles are usually designed with a fixed downward angle and the angle of the... 

In this study, a new type of metallic yielding damper called Telescopic damper is proposed and analyzed numerically. The damper comprises of three concentric steel tubes connected together by lead shear keys. The relative axial deformation of steel tubes under axial forces results in shear deformation and yielding in lead shear keys and dissipates energy. The inner steel tube has a lock which limits its movement to some certain extent and beyond this limit the outer tube activates. Therefore, a multi-linear force-deformation behavior with two different yield plateaus is expected for the introduced telescopic damper. The multi-level yield plateaus of damper makes it effective in both low and... 

Since it is important to obtain the suitable cutting conditions for machining and investigate the effect of various parameters on this process, the simulation of this process has been developed extensively by using the finite element method in recent years. Due to very large plastic deformation and also continuous chip flow, one of the most appropriate techniques in modeling chip formation is the arbitrary Lagrangian-Eulerian (ALE) finite element method which has been used in several papers using some traditional codes like ABAQUS or personal codes in recent years. However, one of the limitations in this method is the use of a continuous mesh retains with no change in connectivities which is... 

Solar cells are one of the most promising clean and readily available energy sources. Organic solar cells as a new generation of solar cells, have attracted strong attention in recent years, due to the advantages of flexibility, thinness, and simple manufacturing process. This work focuses on the electrical processes in organic solar cells and approaches for enhancing the efficiency of solar cell by employing two-dimensional drift-diffusion model. At the first step. We investigate the role of different parameters such as mobility (considering different recombination mechanisms), active layer thickness, light intensity, barrier injections and energetic disorder on the performance of single...