Sharif Digital Repository

This research aims to develop an improved model for turbulent heat flux and increase the accuracy of numerical simulation of flow with heat transfer in turbine blade film cooling, especially in rotating blades. The necessity of this research stems from the high importance of blade cooling in increasing the efficiency of gas turbines and the sensitivity of blade life to temperature; such that a 30-degree Celsius error in predicting blade temperature can halve its lifespan. Turbulent heat flux, caused by velocity and temperature fluctuations, plays a key role in film cooling heat transfer. Conventional methods and commercial software often model this characteristic in a simplified manner,... 

In recent years, severe straining has attracted the attention of many researchers as a new and efficient method for improving the mechanical and microstructural properties of low-carbon steel sheets. In this study, the effect of confined groove pressing (CGP) and rolling on the mechanical properties and microstructure of low-carbon steel sheets was investigated. The samples were prepared in five conditions from 0.50 passes to 2.50 passes of CGP and then subjected to different percentages of rolling (0%, 20%, and 40%). The microstructure of the samples was analyzed by optical microscopy and changes in grain size and elongation in different areas were evaluated. The fracture surface images of... 

In the era of the internet and with the emergence of online stores, the possibility of changing prices for these e-commerce platforms has become simple and virtually cost-free. This allows them to adjust prices optimally in response to environmental and surrounding factors, maximizing their revenue from product sales. This development has led to numerous applications of statistical learning methods, particularly online learning, in these markets. In this thesis, we explore the issue of online pricing from various perspectives. One aspect is that product pricing is based on their features, which can be numerous. This leads us to the use of online learning methods and statistical learning in... 

Methodology has always one of important issues in philosophy of science; especially in social sciences lots of challenges arise from this field. Each of positivistic and relativistic different schools, on their own ontology about human and society, had suggested different methods of social studies. Roy Bhaskar, as the others, offers a model for scientific method, on the base of his own critical realistic ontological principles; and tries to secure his model from the objections on previous models of scientific method. In this model, hi suppose empirical survey as an obvious and undoubted activity in science. Then, he transcendentally derives his ontological principles from this antecedent,... 

The philosophers of social sciences, in addition to epistemological questions-the questions about our knowledge of the social world- implicitly or explicitly, consider ontological issues: the questions about the nature of social world (society, structures and relations, people and actions). In Critical Realism, ontology and epistemology are linked. It means that what it is awarded, it is crucial that knowledge can be gained from it. This school, with a critique of Positivism and Hermeneutics, tries to authenticate ontological arguments and by reconstruction of concepts like causality, necessity, structure and stratification reality, forms the realist ontology and offers a novel solution to... 

Memory and recalling process has always been a basic question. Decoding the Long-Term_Memory is one of the first steps in answering this question. Since various experiments in the field of human long-term memory, was conducted. This research is motivated by a trial that in which, the Mgntvansfalvgram (MEG) has been recorded while recalling the color and orientation of a grading which is associated with an object, after the object has been shown. High accuracy in Decoding the mentioned color and direction, will be decoding the long-term memory. In order to enhance memory decoding, the research studies different classifiers such as sparse based classifiers and other popular one. It has also... 

In recent years there has been a great effort to enhance the computer-aided diagnosis systems, Since expertise elicited from past resolved cases plays an important role in medical applications, and images acquired from various cases have a great contribution to diagnosis of the abnormalities, Content based medical image retrieval has become an active research area for many scientists. In this project we proposed a new framework to retrieve visually similar images from a large database, in which visual similarity is regarded as much as the semantic category relevance, we used optimized wavelet transform as the multi-resolution analysis of the images and extracted various statistical SGLDM... 

Breast cancer is considered as the most common type of cancer in women worldwide and mammography is currently utilized as the principal method for screening the breast cancer. Breast Magnetic resonance imaging (MRI) can be used as a complementary imaging technique besides mammography. MRI technique involves scanning a patient before and repeatedly after the injection of the contrast agent (DCE-BMRI). This examination often takes 7-10 minutes and any movement of the patient’s breasts due to breath, heartbeat or deliberate movement, made in this relatively long acquisition period, leads to a distortion in images called motion artifact. This problem makes the quantitative analysis of the images... 

Advancements in medical imaging, especially 3D imaging, leads to progressive growth of image processing for diagnosis, studying behavior of organs and development of disease. Therefore many researches have been done on segmentation, registration, modeling and 3D image refinement. In this thesis, we want to parameterize anatomic surfaces, using volume parameterization model.
Hippocampus is one of the most important components in brain that plays significant role in learning, memory, stress management and etc. There is been a theory that, shape and structure of hippocampus may change in diseases like Alzheimer, schizophrenia, chronic depression and epilepsy.
The aim of this research is... 

The definition of human action recognition is classification of input visual elements based on the action which is done by a person in the scene. One of the most important topics in the filed which has lots of applications is human action recognition in videos. Some of these applications are surveillance, video retrieval, human computer interaction and smart houses. Due to increments in number of alone elderly people, surveillance of them is one of the important applications of human action recognition. The challenges of the task are, camera movement, differences of environment and differences in acting by different actors.The goal of the project is proposing a deep convolutional neural... 

In this study pain level estimation using facial expression is investigated. To do this, there are two approaches, one approach is sequence level pain estimation and the other one is frame level pain estimation. In sequence level, after feature extraction from all frames of sequence, each sequence is represented by a fixed length feature vector, this feature vector is constructed by concatenating min, max and mean of frame features of that specific sequence, then KLPP is applied in order to reduce feature vector dimension and in the end a linear regression is implemented to predict the pain labels of the sequence. In the frame level, two approaches are introduced, the first one is based on... 

Image registration is an important preprocessing step in analysis of medical images. Detection, Treatment plan, disease grows process analysis and assistance in surgical applications are some of medical images applications. We need to be able to compare different modalities in medical images such as X-ray, PET, MRI, and CT... , or sometimes doctors need to take images of a patient in a same modality but in different times and directions. In which in order to be able to do theses comparisons we need to first align these images by using image registration methods. Image registration is an image processing method in which tries to find a geometrical transformation that would map different... 

Autism spectrum disorders (ASD) have been defined as developmental disorders characterized by abnormalities in social interaction, communication skills, and behavioral flexibility. Over the past decades, studies using various genetic, neurobiological, cognitive and behavioral approaches have sought a single explanation for the heterogeneous manifestations of ASD, but no consensus on the etiology of ASD has emerged. Further studies aim to clarify the mechanism of disease.
Functional Magnetic Resonance Imaging (fMRI) is a new way of imaging which evaluates activity of brain by measuring magnetic difference caused by oscillation in blood oxygen level. fMRI has been widely used in recent... 

Nowadays studying the brain's function in different Mental States like Resting-State or performing cognitive tasks is a very important component of research areas such as Biomedical Engineering, Neuroscience and Cognitive Sciences. The applications of studying the brain's function can be divided into two principal groups. In the first group of applications, the goal is understanding how the brain processes and response to external stimuli (like visual or audio stimuli) and internal states (like emotions). In these kinds of applications, particularly healthy subjects participate since the goal of these studies is finding healthy brain function in different states and stimuli. However, in the... 

Medical imaging is of interest because of information that will provide for doctors and registration is inevitable when we need to compare two or more images, taken from a subject at different times or with different sensors or when comparing two or more subjects together. Registration methods can be categorized in two major groups; methods based on feature and methods based on intensity. Methods in first group have three steps in common: feature extraction, finding matches and transform estimation. In second group it’s important to define a similarity measure and find the transform that minimizes this measure.
Manifold learning algorithms are mostly used as a dimensionality reduction... 

Phospholipid vesicles are able to carry drugs or DNA to infected or cancerous cells. The blood flow can carry them to their target positions but their performance will be enhanced if they complete their attack by swimming in final stages of their journey. Vesicles built only by lipid molecules have rotational symmetry and undergo a random motion in their solvents without having a preferred direction. In this project, we break the symmetrical shape of phospholipid vesicles by a cluster of transmembrane proteins. We use a triangulated model of the membrane, apply the method of multi-particle collision dynamics to the motion of solvent particles, and simulate the motility of vesicles for... 

Hard disk drives are the main component of computers for permanent data storage. The security of the stored data is related closely to the air gap between the read-write head and the surface of disk. This gap which is created by the aerodynamic force between head and the disk is altered continually by lateral oscillations of disk. In the extreme condition of zero gap and contact between the protective coating layer and subsequently the magnetic material of the disk with the head, the disk will be scratched and damaged. Therefore, the active or passive control of these vibrations has a particular importance in the technology of manufacturing of hard disks. The first step in active control... 

The Hubbard model is one of the simplest interacting models in theoretical physics, especially condensed matter physics which despite its simplicity, its solutions are highly nontrivial and intractable. After 5 decades since its introduction, its phase diagram is not fully understood and whether or not, it has a high-temperature superconducting phase. In this thesis, we aim to employ the recent advances in machine learning and GPU programming to accelerate the QMC method. By accelerated QMC methods, we can explore the Hubbard model's phase diagram more efficiently. Using massive parallelization of the GPUs can speed up the measuring process by several times. The self-learning quantum... 

As it is known, one of the dangerous consequences of the earthquake is the possibility of fire. In recent years in our country special attention have been paid to design and retrofit buildings against earthquakes, but have not done to understand the behavior and design concepts of structures against fire. One of the reasons is the lack of information and the absence of a specific standard for design of structures against fire. Since the beam-to-column connections play an important role in the performance of structures, in this study, the behavior of the moment frame with flush end plate was investigated by testing on a small scale structural model (half scale). It is observed that, the test... 

Development of DNA sequencing technologies in the recent years magnifies the need for computational tools in genomic data processing, and thus has attracted inten- sive research interest to this area. Among them, Genome-Wide Association Study (GWAS) refers to discovering of causal relationships among genetic sequences of living organisms and the macroscopic phenotypes present in their physiological structure. Chosen phenotypes for genomic association studies are mostly vulnerability or im- munity to common genetic diseases. Conventional methods in GWAS consists of statistical hypothesis testing algorithms in case/control approaches; Most of which are based upon single-locus analysis and...