Sharif Digital Repository

One of the ultimate goals in robotics is to design autonomous robots. Among other things, this means a robot has to be able to plan its own motion. To be able to plan a motion, a robot must have some knowledge about the environment in which it is moving. Some of this information can be provided by a floor plan. For other information the robot will have to rely on its sensors. In this thesis, we consider that the environment is unknown for the robot. So, the robot uses weak sensor to planning its motion. The sensor can distinguish between colors. The robot can follow the colors. Therefore, we need to specify the umber of colors in which the robot can navigate by them. We propose an efficient... 

Adobe structures are considered as masonry structures which are out of scope of 2800 Iranian code. Due to this code, since these structures are made of weak materials, they do not have a considerable resistance to earthquakes. Since these structures can be found all around Iran; therefore, seismic study of walls as an important component of these structures, is, indeed, necessary. During this study, cyclic tests on three types of adobe walls, without opening, with window-opening, and with door-and-window-opening with a scale of 2:3 were done to study their in-plane behavior and also their failure modes. Based on our observations, in these walls, because of small ratio of height to length,... 

Prediction of axial flow turbine’s performance with different operating conditions due to the high costs and lack of reliable empirical data is always under developing. In this type of turbine, fluid flow is three-dimensional, viscous and highly turbulent. Nowadays, although a relatively detailed picture of the flow field can be obtained by the computational and numerical tools, but using of appropriate loss models in one-dimensional modeling for the performance prediction as well as optimization of the turbine in initial design phases, is a common trend.
In the current study, aerodynamic losses in the axial flow turbine are investigated. Several loss models for the axial flow turbines... 

Knew is the biggest and most complicated joint in the body.Morever knew creat mobility must bear the weight of body and have a stability during static and dynamic activities.Knew is exposed different forces that force to around ligaments and soft fibers.After knew injuries, administration of aid is the important part of rehabilitation program.Rehabilitation robots with ability of accuracy and repetitive practices are good method for reducing time and energy of physiotherapist.At this thesis a 3 DOF Cartesian robot is designed and constructed for rehabilitation of knew that can do every practices for rehabilitation.Steps of designing and constructing of robot are based on movments of knew... 

Evaluation of the seismic-induced settlement of an unsaturated soil layer depends on several variables, among which the small strain shear modulus, Gmax, and soil’s state of stress have been demonstrated to be of particular significance. Recent interpretation of trends in Gmax revealed considerable effects of the degree of saturation and hydraulic hysteresis on the shear stiffness of soils in unsaturated states. Accordingly, the soil layer is expected to experience different settlement behaviors depending on the soil saturation and seasonal weathering conditions. In this study, a semi-empirical formulation was adapted to extend an existing Gmax model to infer hysteretic effects along... 

Polymer/clay nanocomposites (PCNs) are multifunctional materials that have superior mechanical and thermal properties than polymer-based materials. These materials are obtained by adding small amounts of nanoclays to a polymer matrix. In this work, a molecular dynamics simulation was carried out to investigate the thermomechanical properties of thermosetting clay nanocomposites. The polymer matrix was composed of phenolic molecules with the crosslink density of 0.74, and different structures of PCNS were considered by varying the amount of polymer molecules. Molecular dynamics simulations of different nanocomposite structures were used to provide the atomistic insights, the molecular... 

The main objective of all managers of the economic organizations, manufacturing and industrial companies and service providers is to take steps toward improvement and effective use of different resources like workforce, capital, materials, energy and information. To attain the desired productivity, managers have to observe requirements such as establishment of a working organizational structure, effective implementation methods, safe equipment and tools, balanced working atmosphere and qualified human force as the most important factor. Therefore productivity culture should be publicized throughout the organization, and human force should be considered as the main component of this process.... 

This work numerically simulates pressure drop and heat transfer for flow in a pipe with porous wall. Incompressible two dimensional, ax symmetric laminar or turbulence flow with constant mass flow rate is considered. It is assumed that there is no thermal equilibrium in the porous media region between solid and fluid phase. Effect of porous wall thickness and Darcy number on the rate of heat transfer and pressure drop were investigated. The Darcy number varies from to and porous wall thickness can fill entire pipe. the turbulent model is used to calculate the fluid flow and heat transfer characteristics in turbulent flow. Nusselt number can enhance about ... 

Briefly in this thesis, these subjects have been investigated: In recent years, water is used as a solvent instead of an organic solvents have become more and more important due to cheap and environmental consideration. In this context, preparation of quinoxaline, pyrrole, new 1,4-dihydropyridine and reduction of imine to amine with 1,4-dihydropyridine derivatives as the reducing agents with the use of one-pot multicomponent reaction have been reported. The existence of several hydrogen bonding groups (NH) in the new dihydropyridines they acts as biologically active compounds in the forthcoming years. In continuation, oxidation of thiols to disulfides in the presence of NBS and NCS and... 

This thesis contains four chapters. In first chapter the role of water in organic reactions as a ecofriendly solvent, computational chemistry and dynamic nuclear magnetic resonance were studied. In the second chapter synthesis of new 4-hydroxy pyrrole derivatives in water were reported. For the synthesis of these compounds arylglyoxal derivatives, 1,3-dicarbonyl compounds and ammonium acetate were used. The reaction conditions are very mild. The third chapter contains the synthesis of new (4 or 5)-Aryl-2-aryloeil-(1H)-imidazole compounds in aqueous media. We also investigated the tauto-isomerisation of isomeric imidazoles during this reaction using DNMR technique. In forth chapter a... 

In recent decades, nano-structured materials have been allocated specific position for wide use in various fields. The nano-diamonds has attracted the attention of many researchers. The inherent characteristics of a diamond like spherical structure of nanoparticles and carbon atoms which have used their full capacity in the chemical bonds,also the same surface as the radiography particles which have empty orbital, provides an ability to perform a variety of surface modification on the particle . This article introduces the nanocomposites based on polymer, constituents specification and discuss properties of nanocomposites after mixing components together. Lots of studies was on... 

In this thesis, heterogenous catalysts based on magnetic nanoparticles were synthesized. In these catalysts, magnetic nanoparticles were coated with defferent fuctional groups to produce a catalyst with magnetic properties which is easily separated from the reaction medium. The structure of synthesized catalyst was characterized using techniques such as transmission electron microscopy (TEM), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), and CHNS elemental analysis. Easy preparation, low cost, biodegradability and high thermal stability are advantages of these catalysts. At the end, the catalytic properties of resulted catalysts were investigated in many... 

This thesis contains two parts .In the first part a catalyst such as AlCl3/Al20 has been demonstrated to catalyze Michael addition reaction of amines to a,�- unsaturated compounds with high yields , short reaction time and under solvent-free condition.The Michael addition to a,�- unsaturated compounds produces quantitively the mono addition products.The next part is about olefins epoxidation . Alkene epoxidation is a useful reaction in organic synthesis. Epoxides play an important role in industrial intermediates for the production of fine chemicals as well as pharmaceuticals .The hydrogen peroxide has been used as an oxidant because it is considered as an economical and appropriate reagent... 

The method of nonlinear time history analysis is well known as one of the most accurate techniques in seismic analysis of structures. However, this method needs much effort in terms of required data and computational cost. Within the time constrains of design consulting firms, more simple analysis tools are also desirable. One of the simple methods which have been gaining ground, as an alternative to time history analysis, is nonlinear static pushover analysis. In this method, the capacity curve of the structure with respect to the roof displacement is established. In nonlinear static pushover analysis, disproportionate increases in the roof displacement and even outright reversals the... 

Enanthioselective synthesis of biological molecules are so important in synthetic chemistry, and because of their biological activities, β-amino carbonyl compounds have earned so much attention in this area of chemistry. Mannich reaction is a classical method for synthesis of these molecules. The Mannich reaction is a three-component reaction between an enolizable CH-acidic carbonyl compound, an amine, and an aldehyde producing β-amino carbonyl compounds. But acidic or basic difficult circumstances, long reaction time, low yield and enantioselectivity, are the drawbacks of classical methods. In this project, we used titania-based solid acid as an enantioselective catalyst to overcome these... 

Nowadays, pile usage in construction of deep foundations has increased significantly, instead of shallow foundation in areas that shallow foundations doesn’t provide enough bearing capacity and measuring the velocity and acceleration due to pile driving is very important. Because, all responses of building and individuals located near the pile driving site influenced by these three parameters: pile vertical displacement, peak particle acceleration (PPA) and peak particle velocity (PPV). One can estimates these important parameters by numerical analysis of pile driving process in different distances and depths to determining the effect of pile driving. Compared values obtained from numerical... 

Cardiovascular diseases are the leading cause of death globally so early diagnosis of them is important. Many researchers focused on this field. First signs of cardiac diseases appear in the electrocardiogram signal. This signal represents the electrical activity of the heart so it’s primarily used for the detection and classification of cardiac arrhythmias. Permanent monitoring of this signal is not possible for specialists so we should do this by means of Artificial Intelligence. In this thesis, we use recurrent neural networks to classify electrocardiogram’s arrhythmias. This deep learning method, use two sources of data to learn from. The first part of data is global for everyone and the... 

Topological defects are interesting phenomena which can be observed in ordered phases such as oriented active fluids or nematic liquid crys¬ tals. Topological defects are determined by the overall structure of the director field in an active fluid in nematic phase and by exerting force to the units of the active particles they can interact or cause motion in the environment. Studying them as particles with dynamical equations, instead of studying the director field of the nematic environment, would provide us the power to study the characteristics of their motion. The equations of motion for multi¬defect systems have been previously stud¬ ied and in this work we focus on the chaotic...