Sharif Digital Repository

Performance of reinforced concrete frames is highly dependent on detailing of the joint connections between its members, such as beams and columns. To have a good structural behavior, joints must show ductile behavior and designed based on the philosophy of strong column-weak beam. In the case of sever lacking ductility, strength or even rigidity of the connections, or having a weak column-strong beam, in the existing structures, there is a need for seismic upgrading of the connection. There are several ways for seismic upgrading of this type of connections.In this research, using steel plates for seismic upgrading of Concrete Beam-Column connections subjected to axial and cyclic loads has... 

Due to recent advances in laser technology and instruments, laser assisted machining processes has gained extra attention by scientists and industries. Naturally, effective modeling of the process is of great interest for researchers. Machining processes are generally modeled via FE tools and based on the requirements of model, it can be performed either mechanically or thermos-mechanically. About the LAM problems, it is basically meaningless to have a model without considering thermal effects. Hence, modeling is performed in two steps where through the first one, a thermal problem is solved to bring the temperature distribution of the work piece as the initial conditions of the next step.... 

This reaserch is study on the performance of evaporation tubes used in mini jet engines which has been done experimentally using laboratory equipment. In this study, researchers have tried to simulate the laboratory conditions as much as possible to the real conditions inside the mini-jet engine, increase the accuracy of the results and increase the results and bring them closer to the results inside the mini-jet engine. The experiments are divided into two categories, cold and hot In cold tests, an attempt is made to study and investigate the types of two-phase flow regimes created by applying different fluid and air flow rates, and to select annular flow regimes from among them.... 

Over the past five decades, the proliferation of electronic devices and the advent of Internet of Things (IoT) technology have ushered in a profound revolution in integrated circuit technology. In contemporary electronics, digital integrated circuits rely predominantly on CMOS transistors. Among the notable limitations associated with CMOS transistors are their non-zero off-state current and limited sub-threshold slope. In response to these limitations, researchers have ventured into a burgeoning field known as "Beyond CMOS," exploring technologies like Tunnel Junctions, Carbon Nanotube FETs, and more. Additionally, alternative approaches that blend electronic and mechanical principles in... 

As humans age, the intervertebral discs in the spine lose some of their water content, reducing their flexibility and making them more prone to tears in the annulus fibrosus. When the annulus fibrosus weakens, the disc's nucleus can push through and cause a herniation, which can press on surrounding nerves and lead to severe pain. Each surgical method for treating disc herniation has its own complications and challenges. The gold standard treatment is fusion surgery, which fixes two vertebrae together, preventing natural movement in that part of the spine. This altered stress distribution on adjacent vertebrae can ultimately damage adjacent healthy discs over time. This research aims to use... 

Solving Nematodynamic equations with Lattice Boltzmann method is presented.We have studid the effect of shear flow on the direction of Director in different boundary conditions and different geometries.we simulated the 2D Nematic Fluid in simple shear with tangential and perpendicular anchoring and We saw nonliner effects on velocity profile when the anchoring of Nematic and boundary was perpendicular to the boundary.also we have investigated and presented the effect of shear velocity magnitude on the overall direction of Director.Also the effect of shear flow have studid for the Nematic between two hegzagons  

In this thesis we study an unexpected reverse spiral turn in the final stage of the motion of rolling rings. Equations of motion for rolling rings have been derived in the framework of Newtonian and Lagrangian mechanics, and solved in the presence of air drag forces and torques. The rolling motions of ellipsoids and disks have been used to validate the governing equations of motion. Based on experimental tests, we have found that the center of mass of rings moves in an S-shape trajectory. This is in contrast to spinning disks and coins that follow a spiral path before they stop. To explain this behavior, we included the effect of air drag in the equations of motions and found that the escape... 

Laser cladding is a processing technique of layer-by-layer material deposition which is widely used to repair important components. However, tensile residual stresses generated in this process may result in detrimental effects such as crack, undesirable deformation and reduced fatigue life. A thermo-mechanical finite element model is developed to accurately predict residual stresses of the multiple beads laser cladding process with incorporating the cyclic plasticity into the analysis by utilizing the nonlinear kinematic hardening behavior. FE results are presented for Inconel 718, a material for which the laser cladding process is widely used. The FE results are compared with those of... 

Isogeometric Analysis method is a newly introduced method for the analysis of problems governed by partial differential equations. The method has some features in common with the finite element method and some in common with the mesh-less methods. This method uses the Non-Uniform Rational B-Splines (NURBS) functions as basis function for analysis. With this basis functions, the refinement procedure is much easier than the classical finite element method by eliminating the need to communicate with the CAD model. Modeling cracks in classical finite element method requires very fine mesh near the crack tip. One can model crack propagation by means of classical finite element, using an updating... 

Aggregation of membrane proteins plays a determinative role in many biological processes، such as signal transduction, cell division and endocytosis. In the present study, we have investigated the interaction between proteins in vesicles by means of coarse-grained molecular dynamics simulations. In the first step, a number of periodic lipid bilayers were simulated and their physical properties were calculated. Then, bilayers were immersed in water and converted into spherical vesicles via a selforganizing process . Finally two proteins were embedded into the vesicle and the potential of mean force (PMF) respect to the angle between them was obtained using umbrella sampling. This process was... 

In this thesis, we study security features of the networks which use linear network coding to multicast information to some nodes of the network in presence of a wiretapper and also an active intruder. We consider information theoretic security in which we assume no computation limits for enemy. Thus, we take advantage of the essence of network coding instead of cryptographic tools to improve security features of the network. First, we show how providing shannon security for such networks in presence of wiretapper, leads to different cost in multicast rate, depending on initial network code designed. Based on this, we present a modified secure network code design which can provide perfect... 

After the discovery of integer and fractional quantum Hall effects, a comprehensive effort started to understand the physics behind these findings thoroughly. At the end, these efforts resulted in the introduction of topological phases of matter and the notion of topological phase transition. With the recent developments in this field, as the introduction and synthesis of 3D topological insulators, many researchers began inspecting the effects of disorders and impurities in the lattice structure on the topological phases, As these imperfections are inevitable in the lab-created instances. Since, in the previous works only on-site disorders was studied, the concentration of this thesis is on... 

Two-phase fluid flow physics in porous media is applied in various fields. Studies have shown that wettability and surface tension, which represent fluid-rock and fluid-fluid interactions, have a significant effect on the dynamics of the immiscible displacement. Although the effects of wettability and surface tension on the macroscopic behavior of fluid flow are known, there is less understanding of it at the micro scale. Considering the essential role of wettability and surface tension in various fields, this project seeks to investigate the effects of wettability and surface tension on the movement and distribution of fluids and the dominant displacement mechanisms within the porous media... 

In this project identification of heavy metals has been studied by using glucose oxidase enzyme. Measurement of heavy metals such as mercury (II) nitrate, lead (II) nitrate and cadmium nitrate are based on inhibitory of glucose oxidase enzyme. To do this, two modified electrodes has stabilized on a graphite electrode. Nanocomposite of single wall carbon nanotube with Nile Blue is foundation of the first working electrode. Biological component of the electrode is glucose oxidase enzyme that bovine serum albumin and glutaraldehyde are helping enzyme in immobilization and these materials cause enzyme to cross link with the foundation. This biosensor has great stability and suitable linear... 

Optical tweezers consist of a tightly focused laser beam. A particle with refractive index greater than that of the surrounding medium can be trapped at the focus of the laser. The trapped object experiences a three-dimensional Hookean restoring force towards the focus. Nano (micron)-sized spheres can produce forces in the range of few pico-newton to few nano-newton. This range covers a large number of the forces, which contribute in biological processes; therefore, optical tweezers are very often used for micromanipulation of biological tissues. In a typical micromanipulation experiment it is crucial to perform proper positional calibration prior to use. There are several calibrate methods... 

In restructured power system, the Independent System Operator (ISO) implements Security Constraint Unit Commitment (SCUC) for clearing of day-ahead market. In this project, SCUC is also uses for simultaneous clearing of energy and reserve market. Spinning reserve and of generating units and Interruptible Loads (IL) are considered as system operating reserves in the proposed model. Some of IL usage restrictions such as maximum load curtailed, maximum curtailment hour in a day, maximum length of each curtailment and etc is also considered. One of these constraints is interruption time (the time between ISO’s request and IL’s Answer) which is very difficult to formulate. Expected Energy Not... 

Turbulence can distort and corrupt the image in quite a few ways when light from a distance star or another astronomical object enters the Earth's atmosphere. It is inevitable that all images produced by any telescope on ther Earth are blurred by these distortions. Adaptive Optics is a technology used to improve the performance of optical systems by reducing the effect of wavefront distortions: it aims at correcting the deformations of an incoming wavefront by deforming a mirror in order to compensate for the distortion. The research work reported in this thesis presents a solution to the surface shape control problems in a Deformable Mirror system. Our first goal is to derive equations that... 

Analog to digital converters with different specifications are widely used in modern electronic circuits. The significant demand on pipeline converters in several low power applications is mainly due to their high speed and high resolution characteristics. Fast and simple design of analog circuits using CAD tools, is highly sought after by integrated circuit designers. In this thesis, pipeline analog to digital converters is studied and a CAD tool is proposed for transistor level design and optimizations. The main advantage of this design in comparison with the previous works is that the yield and power consumption are considered as optimization factors. The module operates in three parts:... 

The main goal of this research is to investigate the effects of different types of heterogeneities on fluid flow and solute transport in saturated porous media. These heterogeneities are micro- and macro-fractures and cavities. For modeling micro- and macro-fractures we used an equivalent continuum model and extended finite element, respectively. Also, we modeled the problem by using mass conservation law for both components of the problem – fluid flow and the solute – and Darcy’s law. In modeling vuggy porous media, due to the high velocity of the fluid inside the free flow areas i.e. channels and cavities, we could not model the medium properly using Darcy’s law. Therefore, we had to use a...