Sharif Digital Repository

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... 

In this thesis we want to discuss about a new approach about information. Using this approach, Scott Muller builds his formalism on two basic concepts: distinguishablity and symmetry. His claim is that there is an inverse relation between symmetry and information. It means that if we have a symmetric system we need less information (Than an asymmetric system) to describe it. Here, we are going to explore the role and significance of symmetry in probabilistic distributions of the double-slit experiment, and we want to show if there is a predetermined relation between symmetry and information or not.
 

This dissertation on the Schrodinger-Virasoro algebra will begin by a brief historical review on the development of the symmetry arguments and its final overwhelming success in the 20th century physics. Testifying many successes of symmetry arguments and group theoretic methods in physics such as the theory of relativity, many physicists began to ask whether covariance under a larger group of symmetry transformation would explain a broader era of physical phenomena? As will be reviewed in the beginning of the second chapter, invariance under conformal group - which includes Poincaré group as a subgroup and thus underlies Lorentzian geometry as its natural background geometry – has been... 

The phase space of the Near Horizon of Extremal Geometries has been studied in ”arXiv:1506.07181”. The phase space for the NHEGs consists of the space of all near horizon geometries with a given symmetry. Utilizing covariant phase space method we will build the symplectic two form on the phase space and will use it to define the notion of symplectic symmetry. The conserved charges corresponding to this symmetries form a symmetry algebra which is called NHEG algebra. It turns out that this algebra is a generalization of the celebrated Virasoro algebra. In this thesis we will first review necessary concepts for construction of the phase space of a Lagrangian field theory and will build the... 

In this manuscript we used the method of coset construction to describe theories of spontaneous symmetry breaking. The mathematical details are included in chapter 2. The utility of the method is that without any knowledge of the UV part of a theory we can construct IR part by just knowing the symmetry breaking pattern. We used the method for some symmetry breaking patterns to construct general relativity, massive gravity and also some symmetry breaking patterns corresponding to conformal gravity  

The importance of the issue of laws of nature is obvious so that some say the purpose of science is discovering the laws of nature. In his “laws and symmetry” (1989) van Fraassen takes an antirealistic position toward the laws. His project is to clear science from metaphysics, and since the notion of laws of nature has heavy metaphysical presuppositions it should be eliminated from the literature of science. He tries to provide three kinds of arguments against the notion of laws: first, historical arguments, second, arguing in favor of insufficiency of all presented accounts of laws, and third, rejecting the tasks that accounts of laws should do. In van Frassen’s view, studies of science... 

The concept of symmetry has long been the focus of numerous debates in different fields; some have come up with an artistic approach looking for a beautiful notion germane to the concept of symmetry. Others have examined this issue from a philosophical viewpoint and studied the ontology of symmetry and philosophers like Kant moved beyond the limits and have given their symmetry a transcendental position. On the other hand, in an anti-realist position relying on the fact that the goal of science is not truth but merely it’s an empirical adequacy, Van Fraassen argued that “science was rapidly gaining autonomy not only from theology but from all of philosophy, and was exploiting concepts and...