Sharif Digital Repository

Performance measurement and its information enable managers for better control and management of their processes. Since, rolling stock maintenance process is a dominant supporting process, which plays a key role in the reliability, safety and quality of service delivery in railway passenger transportation, this thesis is aimed to study the performance measurement of rolling stock maintenance process. The scope of this research work is to study the concept and state-of-the-art of measuring performance with specific reference to maintenance; to study and discuss relevant issues and challenges; to study and analyze current practices in maintenance process of Iranian passenger railway system... 

The enzyme Bruton's tyrosine kinase (BTK) is one of the essential proteins that plays a vital role in the proliferation of B lymphocyte cells. Therefore, it is considered a primary target for restricting the growth of corresponding cancer cells. The side effects of BTK inhibitors, as commonly available drugs, have always been a considerable concern, and efforts to find a more effective drug with fewer side effects have never been rare. Among them, drugs with selectively chosen structures from nature are promising to improve these side effects and achieve greater acceptance through the body's natural system. To address this, innovative drug design methods were employed using various tools,... 

Most of the existing visual SLAM methods heavily rely on a static world assumption and easily fail in dynamic environments. One solution is to eliminate the influence of dynamic objects by introducing deep learning-based semantic information to SLAM systems. In this project, we propose a real-time semantic RGB-D SLAM (built upon RTAB-Map) system for dynamic environments that is capable of detecting moving objects and maintaining a static map for robust camera tracking. Furthermore, we augment the semantic segmentation process using an Extended Kalman filter module to detect temporarily static moving objects by adding centroids to each found dynamic object and calculating their velocity. We... 

Today, many evidences, including the distribution of galactic velocities, gravitational lensing observations, and the cosmic microwave background, show that there exist dark matter (non-baryon matter) in large-scale cosmological structures that are stable, free of charge and without color, which has gravitational interaction like normal matter. The hypothesis that weakly interacting massive particles (WIMPs) as a dark matter candidate with mass range of several tens of GeV to several teV and with the typical couplings of Electroweak order of magnitude, is an attractive and desirable model, Which naturally explains the density of cosmic dark matter in agreement with observations. Alongside... 

Autism is a neurodevelopmental disorder for which there is no definitive cure and it is increasing every year for people with this disorder. In the last decade, the use of virtual environment to improve the skills of people on the autism spectrum has increased. In this research, a semi-intelligent algorithm was designed for a virtual reality game that could provide a more appropriate step to the user according to the user's responses. Our focus is on designing games to strengthen the child in terms of shared attention and eye contact. In other words, we seek to create a virtual environment with the ability to intelligently adapt to interact with our user and turn it into a suitable coaching... 

Wide utilization of nanomanipulation as a promising approach in microorganisms, nanoelectromechanical systems (NEMS) and assembly of nanostructures remarks the importance of nanostructures’ motion in electric fields. Despite of many reports on manipulation and assembly of nanowires (NWs) in non-uniform and alternating electric fields by dielectrophoresis, and also rotation of NWs in rotating electric fields, there is still a lack of knowledge on rotational and translational dynamics of metallic and dielectric NWs in uniform static electric fields. In this dissertation, we study the dynamics of silver (Ag) and titanium dioxide (TiO2) NWs, with diameters and lengths in the range of 40 to 100... 

Examining composite quantum systems through quantum thermodynamics, we face the new concept of binding energy. In this thesis, we are going to present a general definition for binding energy in quantum systems which covers any kind of interactions. First of all, we examine the possibility of energy exchange in a quantum system using quantum thermodynamics. In this theory, energy exchanges of an open quantum system may be divided in to two portions: heat and work; due to an accepted definition, heat is the portion of energy that is supposed to change entropy, while work has no influence on that. In this research, we restrict our calculations to the systems which are thermally closed and... 

Internet of Things (IoT) is one of the most emerging fields in the computer science context. It is predicted that more than 9 billion devices will be connected to IoT networks by 2025. Considering the specifications of IoT devices such as low battery capacity and small memory, these networks face major challenges in energy consumption and reliability. One of the most important elements which have an indisputable effect on network efficiency is routing protocol. In this manner, IETF presented RPL in 2012. It is designed to create a robust network among IoT devices.Although RPL performs well in static networks, it is not designed originally for mobile networks and it has serious flaws in that... 

The design and construction of humanoid robotic hands play a crucial role in advancing human-robot interaction. In this study, a new robotic hand has been designed and developed for the Rasa social robot. This robot is intended to teach Iranian sign language to deaf children, and its new hand must be capable of grasping and lifting objects. To achieve this, various robotic hand structures were examined, and an optimized power transmission mechanism for the fingers, based on both flexible and rigid links, was selected. This design enhances the precision of finger movements and enables the execution of grasping and lifting operations. Additionally, a 3D printer was used to manufacture... 

In recent years, social robots have used simple and complicated context-aware systems to provide better services for users. The navigation module is one of the most important modules in which a context-aware system can be used; Where a social robot can change the way it navigates with respect to the context that the users are experiencing in a manner that fits the cultural background of the users. This kind of navigation helps the robot to keep its users safe both psychologically and physically. In this research, we present a context-aware navigation method that changes its proxemics due to the group context the users are experiencing. This research consists of three main parts: first, a... 

Sign language is an essential means of communication for millions of people around the world and serves as their primary language. However, most communication tools and technologies are designed for spoken and written languages, which can create barriers and limitations for the deaf community. By creating a sign language recognition system, we can bridge this communication gap and enable people who use sign language as their primary mode of expression to communicate better with people and their surroundings. This sign language recognition system increases the quality of education, the quality of health services, improves public interactions and creates equal opportunities for the deaf... 

The persistent demand for advanced materials in the field of field emission has driven extensive research into semiconductor nanostructures. Among these, zinc oxide (ZnO) nanowires have emerged as promising candidates due to their high aspect ratio, favorable thermal stability, and outstanding electronic properties, including a wide energy bandgap. However, the intrinsic limitations of pure ZnO nanowires, such as low electron mobility and suboptimal work function, necessitate enhancements to meet the performance requirements of high-efficiency field emission devices. Doping the crystalline structure of ZnO with Group III elements from the periodic table transforms it into an n-type... 

The coupling of optical and mechanical degrees of feedom via radiation pressure has been a subject of early research in the context of gravitational wave detection. Recent experimental advances have allowed studying the modifications of mechanical dynamics provided by radiation pressure. First, this thesis reviews the consequences of dynamic back-action in optical microcavities with mechanical degree of feedom, and presents a unified treatment of its two manifestations: the parametric instability (mechanical amplification or oscillation) and radiation pressure back-action cooling. Then, by considering the Fabry-Perot cavity with two movable mirrors, and using Multi-Reflection Method, we... 

Video games, as a form of entertainment, have gained widespread attention and usage among all age groups, especially children and adolescents. With a wide variety of game genres and difficulty levels, they offer the opportunity to assess cognitive performance in individuals based on inter-individual differences and variable characteristics such as age, gender, and literacy level. The aim of this research is to study the brain response and gaze dynamics of individuals in a computer game (endless runner) based on electroencephalogram (EEG) signals and eye tracker data. The research process consists of two phases: "Brain Signal Processing in Motor Imagery Tasks" and "Reward and Punishment... 

Emotions are one of the most important issues which affects daily life and activities. On the other hand, robots play an increasing role in human life and play a fundamental role in meeting our needs. One of these basic roles is empathy and verbal interaction between the robot and human. In this research, participant's emotions were stimulated in two ways: by using OASIS and GAPED image data sets and by instructing the participants to remind about their good or bad memories. During emotional stimulation, EEG signals have been recorded for the training and testing process. The preprocessing of training data includes filtering, removing bad parts of data, removing bad channels and... 

In this thesis, we introduced a new augmentation method that takes into account the inherent properties of trajectory data and regenerates valid trajectories while preserving all the distinctive features of the main path. Our method uses Dynamic movement primitives (DMP) formulation, which is widely used in path generation in robotics, to manipulate the data in a kinematically accurate way. We implemented the presented method on our Iranian sign language data set by augmenting each group in our data set with a proper form of our DMP data augmentation method. After training our augmented data set with two deep classification models, We achieved 82.95 percent maximum and 77.61 percent mean... 

Using learning from demonstration approaches is one of the ways to teach a robot how to perform different skills. In classic methods of learning from demonstration, the subject should wear some sensors and devices which is and expensive way. But, with the progresses that have been made in the context of computer vision, it is possible now to achieve to the same results with less cost. Learning from observation is the approach that would be used in this project to do that. By using this method, when robot watches a video, it tries to understand the behavior of the subject and behave in the same way.The purpose of the project is that the robot learns some social (interactive) skills through... 

A social robot is an artificial intelligence-based system designed for humans and other robots. These robots can be used in various settings. The more closely a robot resembles and behaves like a human, the more attention and popularity it will gain. The aim of this research is to humanize the behavior patterns of the robot, especially its gaze in different social situations. The social situations considered in this study are common in human life. In these situations, the robot should make decisions based on the activities that humans are engaged in. The research consists of three parts that design neural networks using LSTM and Transformers architecture. The first part utilizes data...