Sharif Digital Repository

In the last decade, Intrusion Detection Systems has attracted attention due to their importance in network security, but still they've shortcomings. Generating a lot of low level alerts is the main problem. Many of these alerts are actually false positives. One suggested solution is Alert Correlation Analysis. Because of false positives alert correlation techniques are not able to build accurate scenarios, but the accuracy of alerts can be verified with the aid of the information logged in the host systems. In this dissertation after surveying the current alert correlation techniques, a model will be introduced to effectively verify the generated alerts and to apply correlation techniques to... 

In this research, synthesis of new heterogeneous catalysts has been studied. These catalysts were prepared in three different areas of the synthesis of coordination polymers and metal-organic frameworks, supported palladium nanoparticles on these polymers, and production of metal oxide nanoparticles. At first, metal organic frameworks of cobalt and manganese transition metals were synthesized through hydrothermal method. In order to prepare these frameworks, 1,4-benzenedicarboxylic acid (terephthalic acid) and 2-amino-1,4-benzenedicarboxylic acid ligands were utilized as spacer ligands. X-ray analysis indicated that the structure of polymers is composed of secondary building units (SBUs) of... 

The properties of metamaterials can be tailored through modification of their microstructures geometry. In this regard, a vast range of metamaterials have been designed. Auxetic metamaterials are a novel class of materials exhibiting the interesting characteristic of negative Poisson’s ratio. Theoretically, auxetic metamaterials have improved mechanical properties such as shear modulus and fracture toughness. The design and modeling of auxetic metamaterials is not completed yet. In order to exploit the interesting properties of auxetic metamaterials, their potential applications have been investigated in medical, sports, automobile and defense industries, so far. In the present work, the... 

In recent years, requirement engineering and goal modeling have gained more attention among different organisations. Therefore, different methods have been designed to discover stakeholders’ requirements and translate them into process and organizational goals. Various goal models have been introduced to represent these goals and their relations towards each other. Still, these methods are manual representations of different process scenarios and do not relate to the actual behavior. In 2014, Map Miner Method (MMM) was introduced to discover intentional process models from event logs. MMM uses Hidden Markov Model (HMM) as a means to represent the process as a map model of strategies and... 

Recommending routes to city taxis in order to improve their performance in finding passengers can reduce traffic, pollution and waiting time for passengers, as well as this, increasing the efficiency of taxis can increase their income. In this study, by analyzing trajectory data obtained from 536 taxis in San Francisco over a period of one month, we generated networks of cells, each of which has time-dependent characteristics such as the probability of finding a passenger, the capacity of each cell, or the amount of demand exists is in the cell and the average speed of passing through that cell. also, the connections between these cells in order to make more use of the experiences of taxi... 

Low back pain is the most prevalence musculoskeletal pain that people experience in their life. Some cases of low back pain are called non-specific. These are cases for which the reason of pain is not well defined. The aim of this study is to propose a simple approach to diagnose and cluster low back pain patients which helps clinicians to evaluate patients by an affordable and simple tool. In this study, data are collected in two steps using Inertial Sensors. Inertial Sensors consist of a 3-axis gyroscope and a 3-axis accelerometer which represent the kinematic parameters of lumbar movement. In the first step, we examine 24 healthy and 28 patients with low back pain and in the second, 84... 

There are numerous ways available to achieve low temperatures that cryocoolers might be among the most important of them. In the meantime, the pulse tube refrigerator has a special place due to its simple geometry and not be using any moving parts. This simple property make the pulse tube refrigerator one of the most popular methods to achieve low temperatures. Nowadays, a pulse tube refrigerator is used for cooling in the range of 4 to 123 Kelvin in two form of one-stage and two-stage and up to an approximate power of 1 KW. Today, due to the temperature and the amount of power required for cooling, as well as the time it takes to reach that temperature, this chiller is used in medical,... 

The purpose of the present study is to develop neural network estimation method for hybrid or panel data which have a combination of two cross-sectional and time series structures and because of the features of both structures, their use in different sciences offers many advantages; and the analytical methods for this data structure are also different from other one-dimensional structures, so different and specific regression models are presented for this data structure. However, in the artificial neural network method, modeling the development for this data structure is neglected, so in the present study, using the concepts of panel regression methods and their application to the... 

The idea of "vacuum energy" with definition of the "Aether" has many historical backgrounds from Aristotelian philosophy to 19th century and the advent of quantum vacuum. Some assert vacuum which is defined as "pure void" and others have got contrary viewpoints. It can be said that the history of vacuum is as old as history of physics. With the advent of quantum mechanics, vacuum has taken a specific definition. Vacuum from vision of quantum mechanics describes that vacuum is the minimum possible energy state, because if the energy of "quantum vacuum state" became zero, Heisenberg uncertainty principle would be violated. The important consequence of quantum mechanics will be in apparent... 

Fusion surgery or fixation of vertebrae in the spine is used to treat scoliosis, fractures, infections, tumors, spinal cord injuries, and disc herniation. In this type of surgery, two or more vertebrae are connected by special screws called pedicle screws to eliminate movement between the vertebrae. Given the serious risks of spinal fusion surgery, if the slightest mistake is made at the entry point or angle of the screw inside the vertebrae, the risk of spinal cord injury is very high, which is one of the complications of fusion surgery. Therefore, in order to increase the accuracy of screw placement, patient-specific template guides are used as drill guides in this operation. For this... 

Over the past years, translating a grayscale image to a colorful image, due to its applications in medical imaging, and restoring and colorizing old images, has been popular. The problem we are studying here is automatic grayscale image translation to a colorized image such that the colorized image appears as real as possible. Due to the large degrees of freedom in the allocation of colors to different sections of a grayscale image, this problem is extremely ill-posed. Hence, based on previous works we attempt to utilize Generative Adversarial Networks and Convolutional Neural Networks to overcome this issue. The trained model receives a grayscale image and predicts two chromatic channels of...