Sharif Digital Repository

In this thesis the problem of spacecrafts formation control for halo orbit around the second libration point (L2) of the Sun-Earth Three Body (TB) system is investigated. Station keeping, reconfiguration and precision formation control of spacecrafts on halo orbits are performed via the use of the nonlinear Integral Sliding Mode (ISM) method, optimal closed loop Linear Quadratic regulator (LQR) approach as well as the Model Prodective Control (MPC). In this regard the nonlinear relative dynamics of deputy-chief spacecrafts are derived within the concept of both circular and elliptical three body problem; as well the perturbation model of the Moon and the linear model of restricted three... 

Mental disorders are very common nowadays and affect a person’s everyday life, as well as the lives of other people around him/her. According to the World Health Organization, major depressive disorder (MDD) is considered as the fourth main cause of death and premature weakness in the whole world. Information Technology (IT) could be used to diagnose the people who are affected by the mental disorders as well as reduce their effects. As clinical decision making inherently requires reasoning under uncertainty, fuzzy logic is a suitable technique for dealing with this partial evidence. The fuzzy logic is the science of reasoning; thinking and inference that recognizes and uses the real world... 

Galaxy clusters are the most massive virialized systems in the universe. Their studies provide crucial grasp on the galaxy formation and evolution, dark matter and its nature, cosmological parameters and large scale structure of the universe. Because of their significant role in cosmology, providing a catalogue of galaxy clusters in a wide range of spatial angle, mass and redshift seems vital. Galaxy cluster detection can be performed by various methods in a broad spectrum of electromagnetic radiation. Optical detection of galaxy clusters is of the most traditional and popular methods. Among optical algorithms, one of the most efficient is called Cluster Red Sequence (CRS) which applies the... 

According to different interpretations of the philosophy of science schools, scientific knowledge, is responsible for explanation, description, control and prediction of material phenomena and their relationships. But these facts, besides their real aspects, which can be observed and found by episteme, have a conventional side. The conventional aspect of science is rules and contracts which are obtained from the facts you can find by techne. Although conventionals can be traced back to the division of science into theoretical and practical by Aristotle and other Hellenistic philosophers, but in this century Islamic philosophers especially, Tatbayee paid more attention to this topic. This... 

Electrical connectors that used in high speed systems interrupt the connection at the effect of Inertia. Also connectors should be able to work in high vibration conditions without any problems. Vibration of the connector pins can reduce the contact area or even remove it at very short time intervals, which lead to increase connector resistance or disconnection of instantaneous current. These current fluctuations will result in unpredictable performance disturbanceof the electrical system in very sensitive systems and therefore it should be avoided. In this Project, impacts of shock and vibration loads on the connectors is modeled by using FEM and with consideration of this model, connection... 

Characterizing cellular states in response to various disease conditions is an important issue which is addressed by different methods such as Large-scale gene expression profiling. One of the most important challenges in front of bioinformaticians is the loss of data because expression profiling is still very expensive. It is understood that profiling a group of selected genes could be enough for understanding all of the gene expression profile.In this research, we propose a fast method for estimation of the missing values inlow-rank matrices. We consider the highly correlated expression profiles as a low-rank matrix. Then, we used this new method in a proposed algorithm which will select...