Sharif Digital Repository

Presence of emergent vegetation can change the governing forces in flow through such systems and affects the turbulence structure and scalar transport. On the other hand, vertical variation of physical characteristics of stems, which is fairly observed in reality, leads to variation in frontal area and the called vertical density difference. In this study we experimentally investigate the effect of vertical density difference on both flow and vertical transport of mass. The results will be compared with theoretical predictions.
Using rigid emergent model of cylinders as stems with step density variation in depth I simmulate field conditions considering actual variation of frontal area.... 

The main purpose of the thesis is Digital image Processing using the sparsity of image. The issue could be described in two ways. First is reconstruction of missed blocks of an image based on the sparsity of image in the transform domain and second is impulsive noise removal using the sparsity of noise in the spatial domain. In the first approach we will review Guleryuz method and simulate and analyze it. In the second approach, two new methods named RDE and Knockout will be introduced. These methods try two remove the impulsive noise of an image using its sparseness. RDE method is a development of conventional methods, but Knockout has a completely new idea. We will show that Knockout is... 

Digital image processing techniques are widely used in many areas of research and application such as astronomic monitoring, medical diagnosis, product quality control and weather forecasting. The captured film by camera, is converted into displacement data by using Matlab software and image processing methods. This study intends to provide “proof-of-concept” for the techniques, applying them to identification problems involving the simple pendulum, pendulum in-water, the car suspension system. Studies further illustrate that the digital imaging procedure and algorithms developed for the simple problems can be extended for identification of modal properties and structural characteristics.... 

Laparoscopic surgery is a branch of minimally invasive surgery that is implemented in the abdominal cavity. This kind of surgery is conducted using surgical instruments that are inserted into the abdomen through some small incisions created on its wall and the necessary vision is provided for the surgeon using a laparoscope lens that is inserted through the first created incision. In recent years, because of its advantages, controlling and manipulation of the lens is done using some robots instead of surgeon assistant. To facilitate the controlling procedure of these robots for the surgeon, several controlling modes such as keyboard, foot switch, and voice commands are presented. Robolens is... 

Detection of blood diseases is one of the hardest branches of medical science. The human circulatory system mainly consists of three main components namely white blood cells, red blood cells and platelets. Many diseases are diagnosed based on qualitative and quantitative evaluation of these cells, such as cell’s quantity, size, shape and the color of the cells. For example, AIDS and blood cancer cause major changes in components of immune system i.e. white blood cells. Also, some features of red blood cells change in various diseases such as iron deficiency, anemia, thalassemia and other diseases like malaria. Rapid diagnosis and treatment of these diseases has a considerable impact on the... 

Solar heating in aqautic systems, causes tempreture increasing.This temperature difference will promote an exchange flow between the vegetation and open water. The exchange flow generated by the differential heating and cooling associated with depth variation has also been studied through laboratory experiment and modelling. Differential solar heating can result from shading by rooted emergent aquatic plants, producing a temperature difference between vegetated and unvegetated regions of a surface water body. Horizontal density difference between shaded and open water regions drives currents that carry fluxes between biologically and chemically distinct regions of an aquatic system. Such... 

Critical Crescent Moon Detection is a new subject in astronomical image processing. In this project, crescent moon observers prepare astronomical images. Astronomers take images with valuable astronomical accounts and by CCD cameras and telescopes. Crescent moon might not be visible in obtained images, so these images must be processed. Study on different cameras can help us to find important parameters to arrive to the minimum power of the resolution in these cameras. To the best of our knowledge this project is one of the first projects about crescent moon detection. At the first, we apply common image processing methods on crescent moon images. Some of these methods are Deviation... 

Asphalt concrete is a composite mixture of three phases; aggregate, bitumen and air void. Stress and strain distributions obtained from macroscopic modeling yield different results due to distinctly different mechanical properties of the above-mentioned phases. In this study a more exact analysis of the stress and strain, were carried out by considering the mixture as a two-phase composite; aggregate and mastic phases. Asphalt concrete was considered a composite material consisted of sand mastic and aggregate. Aggregate and mastic phases were separated and response of the loaded asphalt mixture was investigated. Aggregates finer than 2.36 mm in diameter, filler and bitumen consist the... 

Ant algorithms are optimization algorithms inspired by natural behavior of real ants, which can find the shortest path between nest and food. These algorithms are used to solve numerous complex optimization and combinatorial problems. In recent years, ant algorithms have been used in image processing, specially in edge detection. Edge detection being important and having applications in image processing, several edge detection algorithms have been presented. Our goal is to study edge detection processes based on ant algorithms. Four algorithms recently proposed in the literature are implemented, and the results presented by their authors are verified. Furthermore, implemented algorithms are... 

Statistical learning plays a key role in many areas of science [38]. An example of learning problems is image matching, image matching plays an important role in many aspects of computer vision.Computers can be used in intelligent tasks, which are followed by logical inference, for example, visual scenes (images or videos) or speech (audios). For humans visual system of such task are performed hundreds of times every day so easily sometimes without any awareness. In this thesis we focus on the image matching phase which is the first phase of the classification process. One of the popular image matching methods is Scale Invariant Feature Transform (SIFT) which our proposed method is based on... 

In this thesis, we present the results of a laboratory and numerical model study of the exchange flow generated by the temperature gradient between an open water heated by sunlight and a canopy area made of floating vegetation. Particle Image Velocimetry is employed to obtain the structures of the warm flow intruding the canopy at the surface and the bottom cold return flow for different roots length and vegetation density. Following an initial, transient stage of flow build-up governed by a balance between inertia and buoyancy forces, the flow reaches a steady state in the canopy area with a force balance between buoyancy and vegetation drag dominating the flow within roots. At the steady... 

Nowadays, vegetations have an important role in protecting ecological systems. One of the impacts of vegetation in water system is pollution diffusion. The physical characteristics of plants, affect how vegetation influence the diffusion phenomenon. Plants’ flexibility may change the drag force and pollution diffusion. Also density variations of vegetation in depths have important affects on flow characteristics.
In this study we investigate experimentally the affects of flexible vegetations and their density changes in depths on vertical mass transport. Thus the current flume has modeled for crossing flow through the plants. To model the steep plants, inclined rigid cylinders have been... 

Considering the tremendous development in imaging systems’ industry, today we can afford to have imaging equipment, capable of taking multispectral images in very high resolution. One of the remarkable benefits of this technology is in the realm of arts and particularly in museums. Taking advantage of the potentials of multispectral, highquality imaging, curators will be able to probe their priceless works of art ( e.g. paintings ) without putting them in danger through invasive research. Besides, one can investigate and control the transformation of these works through time by using this new imaging method. Recently, Multispectral Imaging of paintings, in different frequency bands from... 

In the present study, synthesis, preparation, and application of bimetallic iron/nickel nano-particles were experimentally investigated with the aim of groundwater remediation. Firstly, iron/nickel nano-particles were synthesized according to chemical reduction and stabilization with starch biopolymer, and then characterized. Results confirmed the formation of bimetallic iron/nickel nano-particles with mean size of 75 nm that starch placed around of them. The more stability characteristic and also enough mobility ensure their diffusion through porous media. Secondly, reactivity of synthesized nano-particles for removal of various contaminants including nitrate, chromium, and lead were... 

Environmental flows are seldom independent of plants impact. Aquatic canopies are mostly submerged and flexible; this causes a significant impact on Hydrodynamics of flow and mixing structure. Experimental and analytical investigation of vertical mixing in vegetation canopies with flexible submerged vegetation is the aim of this study. Most of the previous studies on flexible submerged vegetation were conducted to study the transverse and longitudinal mixing. In this study, flexible submerged vegetation in the density range of 2.8% to 4.2% was used to study the vertical mixing.The concentration profiles at four separate stations were obtained by image processing. The results for the... 

In the present study, we are to investigate and calculate the drag coefficient in the secondary bag breakup regime in droplet experiment in which the liquid droplet falls into continuous air jet flow. A high speed camera is hired to record the pictures of this process. With the help of image processing techniques, parameters such as dimensionless diameter, growth of droplet, drag coefficient and etc. in secondary bag breakup regime are investigated. The liquid used in this experiments are water, gasoline and diesel fuel. Dimensionless number influencing the result of the experiment are weber and Ohnesorge numbers, with weber number ranging from 6.86 to 20.31 and Ohnesorge number ranging from... 

Image processing is very important in several applications. Here we use a rectangular grid for image processing. Other approaches exist in the literature. One new approach is to change the grid from rectangular to hexagonal, due to its various advantages over the latter. Main advantage of the hexagonal structure in image processing is its resemblance with the arrangement of photoreceptors in the human eyes. The change in arrangement amounts to requiring less pixels. There is no inconsistency in pixel connectivity and thus angular resolution is higher in this arrangement. Our goal here is to study lossless compression algorithms for images with hexagonal pixels. First, we consider the... 

This study presents an image processing technique for automatic strain and stress measurement in sheet metals. In order to measure the strain automatically, the sheet blank is electrochemically etched to create circular and rectangular grids. After press forming of the sheet, circular grids are deformed into elliptical grids and rectangular grids are deformed into quadrilateral grids. Different photos are captured for using in image processing technique. These photos are taken in different positions. Finally strain can be measured by processing these photos and the stress is obtained by using Levy-Mises flow rule. In this study, three methods of image processing technique are simultaneously... 

Pavement preventive maintenance methods such as slurry seals are cost-effective treatments that enhance pavement longevity. Incorporation of recycled materials such as reclaimed asphalt pavement (RAP) into asphalt pavements helps further reduce costs and energy consumption. Because the use of emulsions and pavement preventive methods is uncommon in Iran, there is little experience with the technology in this area. The present study designed and developed slurry seal and emulsion test devices at Sharif University lab to study the feasibility of incorporation of RAP into slurry seal mixtures while respecting the limits specified by the ISSA and ASTM. Two slurry seal mixtures in which cement... 

An autonomous method for attitude and position determination of a satellite without using data from ground stations and also without the need for human interference is proposed using the image that the satellite has taken at each moment. The proposed method is based on recognition of stable features in the image and using them in order to match the satellite image with a source image from the Earth and the latitude and longitude of the features become known.SIFT and SURF algorithms have been examined. Using the perspective equation and camera coordinate system, a model has been developed that relates the coordinates of a point in the image with its equivalent coordinates in the real world....