Sharif Digital Repository

The brain is constantly placed in stochastic environments. This leads to the brain developing a probabilistic model for the environment. However, sometimes unexpected events occur that lead to surprise and a need for updating the probabilistic model. It can be concluded from this argument that reduction in brian’s surprise is a sign of learning. On the other hand, a probability distribution obtained from a probabilistic model contains an amount of uncertainty. Reducing this uncertainty can also be considered a sign of learning. Surprise and uncertainty can be obtained from a probability distribution using information theory concepts. Another important issue in learning is habituation, which... 

Todays the use of microwave integrated circuits for military and commercial applications has gained much attention, especially riththe advent of monolithic microwave integrated circuits, which provide the possibility of fabrication of amplifiers in large number, sufficient accuracy and affordable price.GaAs pHEMT process, because of good characteristics for noise and power in high frequencies, is a good choice for microwave and millimeter wave integrated circuits. A low noise amplifier is a key block in the receiver and, its noise figure, gain and linearity directly affects the sensitivity and dynamic range of the receiver. Hence, a low noise amplifier with low NF, high gain, good return... 

Many 2D lattice models of physical phenomena are conjectured to have conformally invariant scaling limits: percolation, Ising model, self-avoiding polymers, . . .This has led to numerous exact (but non-rigorous) predictions of their scaling exponents and dimensions. We will discuss how to prove the conformal invariance conjectures, especially in relation to Schramm-Loewner Evolution  

In recent decays, multiple model controllers have been attracted much attention due to their essential ability to control of non-linear systems with wide operating ranges. Number and location of models are two important factors. In this research an algorithm for determining number of models and their locations has been proposed which can be counted as an extension to existing algorithms. Utilizing the proposed algorithm, the minimum number of models which achieve closed-loop stability can be determined. If transient response of non-linear system with these models be not satisfactory, the number of models are increased by one using Binary Search method, and consequently the location of models... 

The main purpose of this study is to develop the Hollow Cylinder Apparatus (HCA) for unsaturated testing on granular materials and to investigate the effect of stress anisotropy on dynamic parameters of soils like shear modulus and damping ratio. Direction of loading and the magnitude of intermediate principal stress have significant effect on the anisotropic response of soils. In many of in-situ loading the direction of major principal stress does not coincide with deposition direction of soil or because of the three dimensional loading condition of soil, the effect of the intermediate principal stress cannot be ignored. On the other hand, in many areas, soils are in unsaturated condition.... 

Evaluating the enviroment for achieving efcient kwnoledge in order to justifed environment recognition and making decision based on data analysis is proponed in many felds.One of these problems is Visibility Problem. The Recieved data from real world as input, for visibility problem, is uncertain such that the recieving data of two different measurments will be different with high probability. Therefore, we defne the goal of this research to solving the visibility problem conditioned to that objects or segments are uncertain.Consider ”S” as a set of ”n” uncertain segments in plane. Each uncertain segment locates in two certain places and with probability 1 2 in each place, the goal is to... 

Growing rate of eutrophication in receiving waters has made the enhancement of wastewater treatment plants to advanced methods of nutrients removal as necessary. Nitrogen and Phosphorus as the nutrients can reduce the quality of water and even make it unusable. Phosphorus is known to be one of the main reasons of eutrophication and creation of algal bloom. In this study, chemical-biological method for phosphate removal from the municipal wastewater is studied. Experiments are implemented for hydraulic retention times of 4, 8 and 16 hours, total intake concentration of phosphorus 7 ppm, COD 400 ppm and Nitrogen 25 ppm. Ferric Chloride as the precipitator chemical substance injected into the... 

In this thesis titled "Enhancing Energy Efficiency in Ideal Binary Distillation tower with a Dynamic Process Intensification," operational methods in distillation units are explored and improved. Given the high cost of energy, limited energy resources, and environmental considerations, increasing energy efficiency in process industries has become significantly important. In this context, this research attempts to enhance the performance of the distillation unit by utilizing dynamic process intensification with two operational points corresponding to the production of products with purities both higher and lower than the desired product purity, and switching between these two points. The... 

The gaps in the existing studies on L2 listening comprehension have been highlighted in the literature of second language learning. Accordingly, the necessity of the qualitative investigations in this field has been frequently addressed by the scholars (e.g., Vandergrift, 2007). The primary purpose of this study was to investigate the use of dynamic assessment (DA) in L2 listening comprehension within a group of six advanced EFL learners to extract the patterns of teacher mediation and learner reciprocity moves through a dyadic examination of their interactions. The examination of listening self-regulation was another incentive behind this study. This research also investigated learners’...