Sharif Digital Repository

In the problem of Distributed Multi¬User Secret Sharing (DMUSS), in which K users are connected through some error¬free links to N distinct storage nodes with the same size M information unit, the users desire to retrieve their corresponding secret message through an arbitrary set of accessible storage nodes. A trusted master node, which knows all of the secret messages transmits correctly and privately, the messages with a means of coding. The capacity of Distributed Multi¬User Secret Sharing is the supremum of all achievable schemes satisfying privacy and correctness conditions. In this thesis we have investigated two notions of privacy namely, individual and joint privacy. Individual... 

Reviewing trends of energy consumption in the world reveals that sooner or later energy resources will be depleted. This concerning rate of consumption has brought about more greenhouse gases (GHG) emission influencing deleteriously on environment and climate. Human has continued energy consumption to maintain and improve the quality of his life through industrial production. Industry as a significant energy user owns considerable contribution to this consumption. Several attempts have been carried out to develop energy management systems in order to improve the energy efficiency of industrial sectors. Whilst they are comprehensive and could be applied to any sector, there is lack of... 

Control and guidance of a vehicle is vital for it to do its mission correctly. Guidance system and decisional algorithms used in it need exact information of instantaneous position, velocity, and attitude of the guided vehicle to determine and issue proper guiding commands.
Estimation algorithms and navigation sensors are two necessary tools for navigation. In the first section of present study, the satellite equations of motion are derived and a 6-DOF simulation is done for it. In the second section, measurements of star tracker will be simulated using results of the first section. The third section appertains to development of navigation equations, attitude determination using UKF... 

Unmanned Aerial Vehicles have been used for different applications despite their short life. In last recent years, the developements in technology which leads to producing smaller electronical and electromechanical deveices, attract more attention to the researches in these fields. Among these vehicles, unmanned helicopters are more important because of their special abilities and capabilities. However there are some drawbacks which makes using them more difficult.
In this project, the first principle modeling of a RC helicopter has been accomplished and a parametric model including different sections effects has been created. This model has been implemented for a Trex600 CF helicopter.... 

Microrobots (MRs) have attracted a lot of attention during recent years due to their promising biomedical applications. Due to their small size, these robots have limited capability to carry energy sources, sensors, or actuators, so researchers try to transfer energy from outside as much as possible. For this purpose, various actuation methods such as optical, acoustic, electric, and magnetic have been proposed. Magnetic field is the most used energy source. The current study deals with the design and implementation of a system for simultaneous independent control of multiple swimming magnetic MRs. The ability to control multiple MRs simultaneously and independently could lead to higher... 

Unmanned Aerial Vehicles (UAVs) have attracted huge attention in recent years due to the technology improvements. Among them, Unmanned Helicopters (UHs) have great importance because of their special abilities. In this research, the problem of design and implementation of an actual flight control system for an unmanned helicopter is investigated. For this purpose, first a multi-level flight simulation environment is developed in Simulink software environment to model the helicopter flight dynamics. The system identification, control system design and implementation are successfully performed in this flight simulator. Next, the actual helicopter flight control system is designed and produced... 

The main goal of this thesis is the design and development of a rehabilitation device for helping patients “to improve blood circulation” & retain and recover their abilities if possible that were lost during the stroke or a accident like that (my research in karaj/iran shows that it is possible by just movement of the specific body part). The focus is on hand in this thesis because Injuries to the hand are common and can be very debilitating since our hands are our primary means for interacting with our world. For rehabilitation in case of human hand there are several practices that should be done for patients either in home or in a rehabilitation center, time and money that is supposed to... 

In the past few decades, shaking tables are widely used to evaluate system response of structures under seismic excitations. These devices are used without any fundamental research performed on a shaking table system as an entity model. In most of these studies for simplicity, it is assumed that there exist no considerable vibration and displacement around the shaking tables, and no attention is paid to the peripheral substances such as soil settled under the foundation.
In this thesis, result of ambient vibration test on shaking table system (solid deck, concrete foundation and soil layer) has been presented. Precise sensors known as low frequency and high accuracy accelerometers have...