Sharif Digital Repository

We analyze the fundamental communication limits and capabilities of random wireless networks. In order to achieve this goal, we investigate and analyze efficient communication strategies in such networks. The traffic model considered is unicasting. Also, we consider two different channel models, namely, the geometric channel model and the random connections model.
In networks with random connection model, channel powers between different nodes are drawn from a common distribution in an independent manner. We assume an on-off strategy for operation of transmitters, and show that finding the optimum transmission strategy problem is an NP-hard problem. Thus, we propose a heuristic algorithm... 

Attitude estimation means calculating the state variables during the flight, especially in landing and takeoff phases. If we can extract the optical flow using the sensors mounted on the flying object, due to the fact that the optical flow is created by linear and rotational speed of the object relative to the surrounding, we are able to calculate the relative attitude by analyzing the optical flow. Indeed the purpose is developing this idea by using artificial neural networks.
First, we find the optical flow patterns for every attitude condition near the ground, using geometrical calculations. Then we produce an optimal neural network by these patterns. This network has the ability to... 

Popular usage of composite materials in aerospace, civil and defense industries in the last decades has been caused more attention to optimization of composite problems. Due to natural complexity of composite problems, i.e. discrete nature, complex dependence between design variables, existence of too much local optimum and etc., traditional methods of optimization are inefficient and it is necessary to use a powerful method to work cost effectively. Genetic algorithm as a technique through evolutionary algorithms is the most popular methods of tackling composite problems. The success of a genetic algorithm can be quantified by estimating the cost, time required and the quality of final... 

Transonic flow compressors are widely used today. In these systems, the occurrence of shock waves, interaction of the shock and the boundary layer, thickening of the boundary layer and separation are some challenges which can severely affect the aerodynamic performance. Here we use a numerical analysis and an optimization algorithm to optimize the aerodynamic shape of a transonic axial compressor blade section. The total pressure loss through a cascade of blade sections is selected as the cost function. A continuous adjoint optimization method is used along with a RANS solver to find the new blade section shape. Application of three different geometric modelling of a compressor blade section...