Sharif Digital Repository

Due to the interaction of high power lasers with over-dense plasma high harmonics are generated. The increase in harmonics cause an increase in frequency to the level of x-ray frequency and is thus a new method for creating x-ray lasers. In this research, we seek to understand the physics of this problem . Some theories try to explain this phenomenon based on the Doppler shift caused from the reflection of the laser beam from surface of the plasma, which oscillates with relativistic velocity.some try to explain this phenomenon based on the similarity with synchrotronic emissions. In this research, the main theories on this subject are reviewed, and a modelling of the emission caused by the... 

Structures that change color in an adjustable way have been noticed in recent years. There are structures in nature such as the skin of chameleons and octopuses and other animals that can change color. In recent years, inspired by these structures, materials based on photonic crystals or surface plasmonics have been proposed to change color. In this research, a review is made on these structures in nature as well as recent efforts to make such materials. In fact, photonic crystals create a special color due to the interference between scattered waves. For example, the change in the distance between the nanoparticles in the photonic crystals inside the chameleon skin is the cause of its color... 

Nowadays the process of making smart rehabilitations' equipment is at the centre of physicists' attention, so this affair is a matter of research in the medical engineering.Amongst of the advantages of this method there are: increasing the efficiency, recording patients' information, no need for continuous physiotherapists and therapists' presence in all the process of medical treatment, and saving time and money. In addition, due to removing traditional methods of rehabilitation, the precision and control ability of medical treatment is considerably increased, reducing the unexpected injuries during the exercise. The shoulder wheel is one of the useful devise in clinics physiotherapy... 

WSNs have been gained much attention in both industrial and educational communities, as they are expected to bring interaction between humans, environment, and machines into a new level. Due to the differences between Wireless Sensor Networks and other wireless networks, new network architectures have been developed and many new routing protocols have been proposed for these architectures. To solve routing problems in WSNs by Swarm Algorithm (SA) is an active, interesting research area and this thesis tries to bring up a new SA towards this mater. Using artificial intelligence (AI) techniques in this environment is a promising task which is challenging at the same time. In this thesis we... 

In the first stage of this research, different amounts of glycidoxypropyltrimethoxysilane (GPS) were grafted as a coupling agent on the surface of nanosilica particles (NS). Surface characterization was done by Particle Size Analyzer and Thermal Gravimetric Analyzer (TGA) and that way, samples were distinguished from each other. More comparisons were taken by Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). Then the different amounts of modified NS were added into the matrix of an epoxy resin and the physical and mechanical properties of samples were tested with Abrasion Resistance test, Tensile Strength test, Thermal Mechanical Analysis (TMA),... 

Antibacterial coatings are a branch of paints and coatings industry that has a wide application from Clothing and Textiles to Floor and Medical instrument. Different antibacterial agents such as silver, titanium dioxide, zinc oxide, gold, chitosan, Silicon dioxide, Magnesium hydroxide and carbon nanotubes have been used. UV curable coatings are economic and environmentally friendly coatings and they are one of the fastest growing segments in the paint and coatings industry. Many studies have been conducted on UV curable coatings and their properties. Among different resins, The UV curable polyurethane offer properties such as: Excellent hardness, High gloss, good chemical and weather... 

The concurrent flow of oil and water is a common occurrence in the field of multiphase flow in different fields including petroleum industry. In oil and gas, production engineers often face a situation in which more than one phase is flowing through the producers. In such conditions an accurate assessment of pressure loss inside the well plays a vital role in efficient and effective production planning. Changes in well orientation, wellbore diameter, reservoir and fluid properties as well as fluid flow rates are among parameters in which will affect the flow patterns that can occur inside a well during its life time. These flow patterns are created as a result of a competition between... 

Casing design is one of the most expensive parts in the drilling of oil wells, and any cost reduction with the basic design of these casing strings will significantly reduce the total cost of the operation. In recent years, occurring scenarios-based casing design has become popular; Because in many cases, it eliminates non-occurring scenarios such as gas kick and saves on drilling costs. In this study, we have tried to investigate all scenarios that may occur during the lifetime of the well, whether drilling or production, and for each well, based on its own field information, possible scenarios for each casing part are selected separately and the applying loads are calculated. For this... 

Fullerenes are molecular solid materials which are composed of 3D closed shell carbon-only structure. As soon as mass production of fullerenes was performed, the synthesis and characterization of endohedral fullerenes having at least one non-carbon element in the hollow fullerene cage, was started (in which about 30 atoms inserted in it so far). Furthermore, because of low efficiency and purity of these nano-particles, nowadays characterization of fullerenes is one of the most important research fields. In this project, we firstly optimized the fullerene production parameters in an arc discharge reactor to reach convenient efficiency. Then, the synthesis of endohedral fullerene by vaporizing... 

Nowadays, too much attention has been paid to Solid Oxide Fuel Cells (SOFC). One of the key components in SOFC is interconnect which plays an important role in SOFC performance. Interconnect can be either a metallic or ceramic layer that sits between each individual cell. The reduction in operating temperature of SOFC resulted in interests in using metallic interconnectors. However, the oxidation of these metallic materials is big challenge. Chromium (Cr), Nickel (Ni) and Iron (Fe) alloys have been employed to overcome this deficiency. However, these alloys bring another difficulty which is the presence of active elements such as Cr which reduces the performance of interconnects by forming... 

Many studies point to a possible new stylized fact for financial time series: the multifractality. Several authors have already detected this characteristic in multiple time series in several countries. With that in mind and based on Multifractal Detrended Fluctuation Analysis (MFDFA) method, this thesis analyzes the multifractality in the Tehran Stock Exchange. This analysis is performed with daily data from Tepix index (Tehran stock exchange's main index) and other three highly marketable stocks in the Tehran Stock Exchange (Pharma index, Oil index and Metal index), wich making up 1782 observations for each index in the period from March 21, 2011 to Aug 22, 2018. We found that the studied... 

Every year, a lot of costs are incurred to dairy production sets for new product production or product improvement.cosidering to the high amount spent on this sector so if there is not any cost management and cost planning based on life cycle of projects , costs will increase .As a result today considering of life cycle in cost management is a Essential principle . In this study we consider kalleh dairy company as a case study and resuls of this study will be a complete economic model for cost management based on the life cycle of dairy projects  

Many mobile applications running on smartphones, wearable devices, tiny autonomous robots and IoT devices would potentially benefit from the accuracy and scalability of deep CNN-based machine learning algorithms. However,performance and energy consumption limitations make the execution of such computationally intensive algorithms on embedded mobile devices prohibitive.We present a GPU-accelerated engine, dubbed mCNN, for execution of trained deep CNNs on mobile platforms. The proposed solution takes the trained model as input and automatically optimizes its parallel implementation on the target mobile platform for efficient use of hardware resources such as mobile GPU threads and SIMD units.... 

Many chip manufacturers have recently introduced high-performance deep-learning hardware accelerators. In modern GPUs, programmable tensor cores accelerate the heavy operations involved in deep neural networks. This paper presents a novel solution to re-purpose tensor cores in modern GPUs for high-throughput implementation of turbo decoders. Turbo codes closely approach Shannon’s limit on channel capacity, and are widely used in many state-of-the-art wireless systems including satellite communications and mobile communications. Experimental evaluations show that the proposed solution achieves about 1.2 Gbps throughput, which is higher compared to previous GPU-accelerated solutions  

The objective of OCR systems is to retrieve machine-encoded text from a raster image. Despite the abundance of powerful OCR algorithms for English, there are not many for Farsi. Our proposed algorithm is comprised of pre-processing, line detection, sub-word detection and segmentation, feature extraction and classification. Furthermore, hardware implementation and acceleration of this system on a GPGPU is presented. This algorithm was tested on 5 fonts including Titr, Lotus,Yekan, Koodak and Nazanin and an average accuracy above 90% was achieved