Sharif Digital Repository

Neck fracture caused by impacts on the head and neck during road accidents annually imposes a great cost to the people hospitals and the economy of country. Most of these accidents, regardless of cartilaginous injury causes sudden pressure to the spinal cord so it seems necessary to understand the biomechanical response of the neck and the mechanism of injury to reduce costs. Many computational models related to the neck injury have been developed recently. The aim of this project is to investigate the effect of frontal and rear impacts to the head and neck during road accidents. There are many researches have used elastic property for tissues but a little portion of research in this field... 

Let (P;≼) be a partially ordered set (poset, briefly) with a least element 0. In this thesis, we deal with zero-divisor graphs of posets. We show that if the chromatic number r(P) and the clique number r(P) (x(r(P)) and !(r(P)), respectively) are finite, then x(r(P)) = !(w(P)) = n in which n is the number of minimal prime ideals of P. We also prove that the diameter of such a graph is either 1, 2 or 3 while its girth is either 3, 4 or 1  

Management decisions, Enhanced Oil Recovery, and reservoir development plans in petroleum industries are based on predictions by reservoir simulation. Due to uncertainties in model parameters or engineering assumptions, the simulation results are not accurate, while they are correct. One remedy is to match simulation results with engineering measurements, typically pressure and flow rate, by adjusting model parameters. In Reservoir Engineering literature, this is called History Matching and is an optimization problem. Common methods of history matching are based on finite difference simulation, and therefore have a very low speed. In addition, these methods usually ignore Geostatistical... 

Face recognition, which is one of the most important biometrics, has always been one of the main challenges in many security issues, such as verifying the identity of customers of financial institutions and passengers at the airport, and such issues have many applications in daily life. Face recognition has always been an important issue in computer vision and pattern recognition. Currently, several methods based on deep networks have shown great results in face recognition, among which the following can be mentioned.1.The deep face was introduced by Facebook in 2014; 2.Face-net was presented by Google in 2015 ;3.VGGFace was presented by Oxford University in 2015; 4.Openface was presented by... 

The effects of biosurfactants on sandstone rocks are known in the literature. However, there are few examples of experimental works in Iranian carbonate reservoirs dealing with the effects of biosurfactants under reservoir conditions. This thesis discusses the effect of an efficient biosurfactant produced from Pseudomonas aeroginosa MRo1, a bacterial strain isolated from oil excavation areas in southern Iran, on the recovery of residual oil trapped within carbonate rocks was investigated. The MRO1 could reduce surface tension from 72 to 28 dyne/cm. It also could reduce Interfacial tension from 18.382 to 5.646 dyne/cm.
In a core holder set-up bearing four limestone- and... 

Detection text in natural images is a challenging task due to the complex backgrounds in an image. complex backgrounds, changes in ambient light, changing viewing angles, and other factors can make systems difficult to detection text. Hence text detection is always an problem. Since detection and recognizing a text in an image has many uses such as translating texts for tourists, helping the blind, etc., recognizing a text in different languages is important. In this thesis, we first examine the three methods of Reading Text in the Wild with Convolutional Neural Networks and FOTS and CRAFT. Then we prepared two Persian data sets. The first data set contains images to which Persian texts have... 

Non-overlapping Cameras in multi-camera systems have become prevalent in robotics and computer vision research; therefore, it is possible to cover the wide field of view, and researches have been done for computing extrinsic parameters of cameras. These cameras do not have any overlap in their views, so obtaining the corresponding point in their images is somehow impossible. Light and shadow geometry is analogous to Structure from Motion problem. In this thesis,we study Structure from Motion problem and have tried to propose an approach for estimating extrinsic parameters of non-overlapping cameras in Multi-camera systems. We formulate the problem by using light and shadow geometry and... 

Image retrieval refers to the task of finding images related to a query image within an image set. Due to ever-increasing volumes of data, it has become increasingly necessary to find suitable and efficient methods for searching in massive databases. In this thesis, modern image retrieval techniques developed within the last 15 years have been studied, with an aim to satisfy three primary constraints of efficiency, accuracy, and low memory usage. Our focus has been on content-based retrieval; meaning that instead of using text and other information, we directly utilize image features for analysis and processing. To achieve this, we studied two established techniques, the bag-of-words model,... 

The Vehicle Routing Problem with Simultaneous Pick-up and Delivery (VRPSPD) and maximum time for traversing of each tour is a variant of the classical vehicle routing problem (VRP) where clients require simultaneous delivery and pick-up. Deliveries are supplied from a single depot at the beginning of the vehicle’s service, while pick-up loads are taken to the same depot at the conclusion of the service. Also the required time for traversing each route should not encroach the specified limit.
In this research, the aforesaid problem was introduced and a mixed integer programming model developed for it. Because of being NP-Hard and impossibility of solving it in the large instances, two... 

Networks of neurons produce diverse patterns of oscillations, arising from the net-work’s global properties, the propensity of individual neurons to oscillate, or a mixture of the two. Here we describe noisy limit cycles and quasi-cycles, two related mech-anisms underlying emergent oscillations in neuronal networks whose individual com- ponents, stochastic spiking neurons, do not themselves oscillate. Both mechanisms are shown to produce gamma band oscillations atthepopulation level while individualneu-rons fire at a rate much lower than the population frequency. Spike trains in a network undergoing noisy limit cycles display a preferred period which is not found in the case... 

In this research, a facile, two-step synthesis was reported for 34-LCysteine- nanocomposites. The first step comprises the preparation of LCysteine functionalized magnetic nanoparticles (MNPs) core-shell structures via co-precipitation method. In the second step, graphene quantum dots (GQDs), which were synthesized by citric acid carbonization, added to the functionalized MNPs and finally refluxed at the appropriate time and temperature. LCysteine as a biocompatible, natural amino acid were used to link MNPs with GQDs. This nanocomposite was characterized by various techniques. XRD and FT-IR were used to investigate the formation of MNPs and LCysteine existence on the MNPs surface. XPS... 

Quantum mechanics is very succesful in the description and prediction of the microphysical world. So nowadays very few doubt its authenticity. Nevertheless, there are some conceptual issues that are still under debate, such as action at a distance. It took a while after the introduction of the EPR paradox in 1935 until John Stewart Bell derived an inequality, using local hidden variables. This inequality was in contrast with predictions of quantum mechanics. Experiments also contradicted this inequality. This implies that there is action at distance which, in turn suggests, the violation of the special relativity. In this thesis, we consider this issue and shall see that on the one hand we... 

Credit scoring is a mechanism used to quantify the risk factors relevant for an obligor’s ability and willingness to pay. Credit scoring has become the norm in modern banking, due to the large number of applications received on a daily basis and the increased regulatory requirements for banks. The meaning of credit scoring is to assign scores to the characteristics of debt and borrowers, historical default, and other loss experienced as an indication of the risk level of the borrower. The aim of the credit score model is to build a single aggregate risk indicator for a set of risk factors.
In this study, current method in which Maskan bank will give a loan is explained. We developed a... 

Nowadays, with the increasing size of data,it’s impossible to collect data and fast classification by human, and needs for an automated classification and data analysis, is more interested. Data classification is a process of giving the training data along with their class labels to the learning agent, which learns the relation between the instances and the labels. Then make a prediction to the label of the training data.In this thesis we will observe the classification of the multi-label data. Multi-label data have more than one label. In other words, each instance appears with a vector of labels.In this thesis, a method based on nearest neighbor is proposed to classify the multi-label... 

Recent progress in developing Artificial Neural Network (ANN) meta-models has paved the way for reliable use of these models in the prediction of air pollutant concentrations in urban atmosphere. However, improvement of prediction performance, proper selection of input parameters and model architecture remain key challenges to their practical use. This study’s main objectives are: selecting proper input parameters for ANN meta-models, optimizing the ANN models to achieve the most accurate hourly prediction for a case study (City of Tehran), coupling the ANN method with filtered input data and evaluating its privilege. In the current study the ANNs were constructed to predict criteria... 

In this thesis, static and dynamic analysis of nano beams based on second strain gradient theory is presented. Due to their small sizes, nano electro mechanical devices (NEMS) hold tremendous promise for novel, versatile and very sensitive devices for different applications ranging from actuators, transducers and also mass, force, light and frequency detectors. Therefore accurate modeling and analysis of such devices has an important role in their design and performance improvement. Neglecting the size effect, traditional theory of elasticity can not be suitable to predict mechanical behavior of these systems and so, it should be used non-classical theories which include size dependency...