Sharif Digital Repository

In this thesis, the purpose of the research was to develop a four-wheeled Mobile platform (Lower body) with three degrees of freedom for a humanoid robot upper body which is called RASA. RASA robot was designed and constructed for helping kids who have speech and hearing impairments. The objective was to develop a low-cost and affordable robot as compared to its international models to be used at home or school as a teacher assistant. RASA can help kids to learn signs as fast as possible due to the game-based and entertaining education system. The wheeled base platform consists of a new mechanism with 6 bar linkage for bending robot from the hip to about 60 degrees from a vertical position... 

Recent studies show that spherical shape robots have been widely developed by many robotic researchers. A spherical shape can be also benefited in keeping mechanical components and electronic circuits inside a compact volume. The shell can also perform rolling motions for going fast and smooth on flat area. The reconfigurable spherical robot can be configured into a form of two interconnected hemispheres with three legs equipped with three Omni-directional wheels. The conceptual design of the robot will be initially packed and deployed in a spherical configuration. The spherical construction offers ease in transportation and deployment; for example, a number of these robots can be packed and... 

Knowledge of the properties of aerosols is of great importance in aerosol science. To gain a better understanding of particle properties, behaviors and dynamics, measurement capabilities are crucial and inevitable. The most critical steps in the aerosol size measurements based on electrical techniques are the processes of particle charging and neutralizing. Corona discharge is a paramount method among all aerosol charging methods because of highest concentration of produced ions, which is essential for the efficient particle charging, based on diffusion and field charging mechanisms. The only known method, which could be applied to provide required conditions for these two charging... 

Aerosol measurement is used in different fields such as nanotechnology and materials science, environmental air pollution monitoring and air quality measurements, combustion and engine exhaust, inhalation toxicology and medical studies. One of the most prevalent methods for aerosol measurement uses electrical mobility. An electrical mobility spectrometer (EMS) is used to classify particles ranging from 10 – 1000 nanometers, under the influence of an electric field. There are two electrodes in EMS between which the aerosol and sheath air flow. Charged particles in the aerosol and sheath enter the device from one end and are subjected to an electric field. Passing through the annulus,... 

In this thesis, in order to improve the performance of the mobile robot navigation, a Fuzzy approach is used for making a safe path in the cluttered environment with hurdles in the work space of the robot. To this end, based on data collected from instantaneous location of the robot and location of the robot, heuristic rules are extracted. Also, in order to obtain optimal data fusion of the sensors, Kalman filter is used to localize the robot. In this regards, by using the kinematics of the robot and supposing the white noise in the process and measurements, the position and orientation of the mobile robot are estimated in a real-time and adaptive manner  

The financial services industry, specially the retail banking sector, has experienced significant changes in which the consequences could be a competitive pressure, customer requirements, and technological innovation. One of these new service deliveries, which has been presented recently and has been developed dramatically in this industry, is mobile banking which offers a great deal of benefit for both banks and customers. As far as this new trend suggests, researchers in various fields draw their interests toward this new technology as a subject matter for their research. Although there is a great number of a researcher in this field, this still is an infancy stage of progress. No one... 

Today, almost all the Iranian mobile telecommunication companies should rely heavily on customer loyalty and customer retention as essential and vital tools to provide a competitive advantage in this competitive telecommunication world by offering value and upper hand service with respect to the existing demand in the Iranian market, hence these determinants arise the need for studying eCRM, Loyalty and Retention in order to achieve customer satisfaction in the Iranian mobile telecommunication field. 400 customers who use the Iranian mobile telecom operators’ services (Hamrah-e Avval, Irancell, and Talia) have been asked as respondents in this research. The study is based mainly on primary... 

In recent years, mobile social networks have largely been developed and gained considerable popularity. With the development of smartphones, the growth rate of users on mobile social networks has dramatically increased, with users constantly interacting and sharing their various private and public data. Such volume of information can be used for profitable purposes and may affect the users' privacy. However, due to the limitations of smartphones and the trivial and costly encryption, entrusting the encryption to the user, both for users and for the service provider will be challenging, thus, social network providers themselves take charge that can compromise the privacy. In this... 

Vehicular Ad-Hoc Network (VANET) is a special case of Mobile Ad-Hoc Network (MANET) which is rapidly emerging with some unique properties in which vehicles have the ability to communicate with each other without any preexisting centralized infrastructure and coordinator. VANETs help in improving road safety, traffic control and information as well as commercial applications. Performance of such kind of communication between vehicles depends on various routing protocols. Routing may be a great thought employed in VANET. Current routing protocols cannot perform efficient routing in both high and low density of vehicles environments. Therefore, we propose a hybrid reliable routing protocol for... 

Nowadays, use of wireless networks and devices is inevitable due to their beneficial features, such as ease of use, portability, rapid and comfortable access to information. On the other hand, the security for wireless networks is a challenging matter by overwhelming increase over the number of mobile hardware and devices. Mobile Ad-hoc network (MANET) is a class of wireless networks, which forms dynamically by joining or leaving the nodes into/from the network without any fix infrastructure. This kind of network in comparison to other types of networks, is prone to various security threats or attacks due to its unique characteristics (dynamic topology, open medium, lack of central... 

Wireless Sensor Networks (WSNs) consist of few hundred to thousand sensor nodes that are usually deployedrandomly in a sensing field. The duty of sensor nodes is to sense the environment for data collection and sending these data to a sink node for future processes. Sensor nodes are equipped with a non-rechargeable battery. Hence, network lifetime is an important issue in WSNs. When a static sink node is used in a WSN, sensor nodes that are located in the neighborhood of the sink node willdrain out of energy faster than other sensor nodes which are farther away from the sink node, because traffic load is heavier on sensor nodes which are closer to the sink node. This problem is named “the... 

In a distributed system, each solution for the problem of Byzantine Agreement requires that some of correct processes reach a common decision value from a set of proposed values while Byzantine processes may behave arbitrary. This problem is one of the most fundamental problems in the theory of distributed systems. While the problem has been widely studied in fully-connected fixed networks, few studies have been carried out in the context of self-organizing mobile networks such as Mobile Ad-Hoc Networks.
This research presents a randomized consensus protocol with three additional modules for the case of dynamic networks: Participant Detectors, Failure Detectors and Maintainer. We assume... 

Mobile Worldwide Interoperability for Microwave Access (Mobile WiMAX) is a wireless access technology based on IEEE 802.16e. Mobile WiMAX supports mobility and a wide range of Quality of Service (QoS) requirements for several applications. This wireless technology introduces handover mechanisms to avoid disruption of services running on Mobile Stations (MS) through moving. In this thesis, we have focused on balancing the load of the system, using handover mechanisms suggested by mobile WiMAX. The proposed algorithm, WQLB, concentrates on controlling the system load and keeping it in a balanced state by using a handover process. Also, the algorithm is designed to utilize resources... 

In mobile ad hoc networks, having an efficient routing protocol to deal with dynamics in network topology, based on the user behavior learning, has a significant role in generating more accurate results. It is valuable to use a realistic mobility model in such networks so that the results from the simulation will reflect the actual reaction of mobile nodes in the real world. Using a realistic mobility model helps simulation to have more accurate results in comparison with other kinds of mobility models especially in a Vehicular Ad hoc Network (VANET). Before exchanging information between moving vehicles, the destination node should be located. However, the existing location service... 

Mobile Ad-Hoc Networks (MANETs) have been studied as one of the most important technologies in the mid to late 1990s. There are several research works on types of network traffic modeling and prediction. Therefore, a very important issue is to make prediction on traffic-flows that each node handles. Because of this, prediction permits us to improve and increase the performance of the network. This project is a contributing effort to improve the traffic packets prediction by Neural Networks in MANET. The main goal of this thesis is about the recovery of data after crisis in phenomenal roads and highways. Our goal is recognizing phenomenal crisis-points in roads. In this thesis packets are... 

Vehicular ad hoc networks (VANETs) are currently attracting the attention of researchers around the world. They offer a wide range of applications improving road safety and driving comfort. Since VANET applications affect safety-of-life, data security in a vehicular system is mandatory. VANET is a special case of Mobile Ad hoc Network (MANET). Routing in VANET is a controversial issue. Furthermore, Security at routing level is so important because if the routing is compromised, other protocol layers on top of the network layer are also compromised. In this thesis, DSDV, DSR and AODV routing protocols are simulated to understand which of these protocols are suitable for VANET. Finding... 

A Mobile Ad hoc NETwork (MANET) is a set of wireless mobile nodes that form a self configured network. MANETs do not have infrastructure and are not currently deployed on large scales. So research in this area is simulation based. Mobility model in a mobile ad hoc network explains the movement pattern of mobile users and is designed to describe the change of their location, velocity and acceleration over time. One of the challenges in this field is the definition of a common mobility model that provides an accurate and realistic movement description of mobile nodes. In this thesis we want to study the mobility pattern of vehicles on Kish Island and compare it with different kinds of... 

Several applications have been envisioned for wireless sensor networks (WSNs). These range in scope from military applications to environment monitoring to biomedical applications. It is a widely accepted fact that the limited energy available at the nodes of a wireless sensor network must be used as efficiently as possible. If energy conservation techniques are used at different levels, the functional lifetime of both individual nodes and the network can be extended considerably.
Energy can be saved if the network topology itself is energy-efficient. The research in topology construction and connectivity has been approached independently along two paths. In one path, researchers aim to... 

Today, communication sciences are advancing very rapidly; one of these advances is mobile location determination, means finding position of a mobile station. there are some method to location determination; one of these methods is Signal Strength (Power of Arrivals); In this research, Mobile Location Determination using Signal strength measurements in a Location grid will be describe; In this method there is a Mobile Location Server (MLS); In MLS, there re comparable records in database which have been collected from Location grid. When a MS needs to be located, its signaling data (fingerprint) is transmitted to MLS; In MLS, the fingerprints are compared to Data which is store in signature...