Sharif Digital Repository

The main problem of steel-reinforced concrete structures is corrosion of steel reinforcements which leads to premature failure of the concrete structures. This problem costs a lot annually to rehabilitate and repair these structures. In order to improve the longterm performance of reinforced concrete structures and for preventing this corrosion problem, Fiber Reinforced Polymer (FRP) bars can be substituted of conventional steel bars for reinforcing concrete structures. This study is a numerical study to evaluate structural behavior of the simply supported concrete beams reinforced with FRP bars in comparison with steel-reinforced concrete beams. The commercial Finite Element Modeling... 

The ground experiences various hydraulic conditions under climate and groundwater level changes, and it becomes dry or wet frequently. The states of pore-water within the geomaterial, being signified in terms of suction and saturation degree, change during these variations, and consequently affect the soil behavior. The main objective of this research is investigation the effect of anisotropic loading induced by rotation angel of principal axes parameter under unsaturated conditions . Hence, shear strength of firoozkooh silt, in terms of deviatoric stress at failure under monotonic loading under different values of rotation angel of principal stress axes parameter and confining stress have... 

Although surface water networks play a very important role in transporting runoff, they contain significant amounts of pollutants entered through the point or non-point sources which cannot be neglected. The goal of this research is quantitative modeling of Zargande reach located in Maghsoodbeyg-Sadr area using SWMM model and investigating the effect of variation of permeable surface on the volume of runoff. Analysis of a 7 hour precipitation with the total of 5 mm cumulative precipitation resulted in 1.6 mm per hour loss of watershed. We utilized a FORTRAN code which minimizes the difference between the Espey synthetic hydrograph and the observed hydrograph for the precipitation to obtain... 

Mixed-model production Lines manufacture or assemble more than one product with similar production characteristics or different models of a product on the same line. This level of flexibility in commodities is very important to face diverse customers' expectations. In this article, U-shaped, mixed-model, synchronous lines with stochastic task times are discussed in a cost-oriented perspective. In U-shaped, mixed-model, Simultaneous consideration of line balancing and model sequencing is essential because different models require different tasks with different task times and the sequence of models determine the models which is produced in each station in each cycle. This sequence affects the... 

Metallic multilayer composites provide remarkable mechanical, electrical and magnetic properties. These kinds of composites are recently processed by severe plastic deformation methods. Accumulative roll bonding (ARB) is one of the SPD processes in which accumulation of strain by repeating cycles, leads to the ultra fine grains structures. The goal of this research is manufacturing of Al/AZ31 composite and investigating the relation between the rolling process parameters and the mechanical and physical properties of the final sheet. The initial composite was carried out by cladding of 1mm thick AZ31 sheet in between two commercially pure aluminum sheets with the same thickness (57%... 

As digital content grows rapidly due to the internet, user reviews about different topics such as product quality can be used as a rich source to check and analyze product quality and performance. Automatic methods are being widely used to extract these information because of the massive amount of available resources. Sentiment analysis is one of the important fields in natural language processing, which uses a combination of learning and rule-based methods to extract subjective information out of documents. Aspect based sentiment analysis deals with sentiment analysis based on each aspect of the product. It consists of two main steps: first, aspects should be extracted from the reviews and... 

Making distribution networks smart includes all appropriate hardware and software devices for controlling and making operation of the network optimized. (SCADA system, distribution management, communication equipments, substation automation, monitoring equipments, etc). Monitoring and management of electricity distribution networks enable us to control and record events in the operation. Equipments in the distribution substations, will be under full time monitoring and hence, we would be able to protect them against over loads, over voltages, load unbalances and inefficient usage of transformers capacity and other distribution instruments. It also enables us to manage operation switchings,... 

This thesis addresses design of an adaptive tracking control of input-quantized strict-feedback fractional-order nonlinear systems with unknown control directions. The control design is achieved by using a hysteretic quantizer to avoid chattering. The main advantages of the proposed controller are: the fractional order is available for both commensurate and non-commensurate cases, the¬¬ controller design does not depend on the quantization parameters and some restrictive assumptions are relaxed. Additionally only one adaptive law has been used for the unknown control directions which leads to reduction of computational load. By utilizing the backstepping approach and based on the frequency... 

About 42 percent of annual mortality in all around the world is originated from cardiovascular arrhythmias and diseases. One of these arrhythmias is atrial fibrillation whose onset and persistence can produce clot and consequently cause stroke. The basis of our research are upon this idea that dangerous heart arrhythmias do not happen abruptly and there always are some background signs before occurrence of them. In our approach to predict the onset of atrial fibrillation, by analyzing ECG signal in order to extract distinguishing features, we want to classify signals which will terminate Paroxysmal Atrial Fibrillation (PAF) from signals which won’t end with PAF. In this thesis, we propose... 

In this thesis, I am going to review an introduction of scattering amplitude as a recently hot subject.First of all, I will introduce spinor representation and its applications to calculating scattering amplitudes. After that, I will focus on the MHV amplitudes as an Impressive part in simplifying scattering amplitudes. Then, I am going to speak about CSW and BCFW; some powerful toolkits in calculating scattering amplitudes of Yang-Mills theories, and I will show the power of these methods in simplifying the complexities in scattering amplitudes. Finally, I am going to speak about the amplitudes and super amplitudes in N=4 Super Yang-Mills theories and we will touch their amazing simplicity... 

The main goal of this work is to estimate the linear transfer function of a single-blade VTOL aerial vehicle, the so-called Monocopter.At first, a prototype of this vehicle is designed and built based on the previously gathered information. The complexity and high manufacturing cost of the first prototype has forced us to build one other simple and cost-effective vehicle. A complete electronic board for data-logging has also designed and built. Many flight test has been carried out and recorded output data are processed by CIFER and MATLAB software in order to identify the dynamic model of the vehicle. The results are presented in different forms