Sharif Digital Repository

Massive-MIMO and C-RAN are the two technologies which will be among most important parts of fifth generation (5G) stsrems. They will find widespread uses in future years. However, data transfer rate between these two technologies is a challenging problem. Also channel estimation is crucial in massive-MIMO systems. In this research, the problem of estimating the channel and the problems with the data transfer rate between these two technologies are investigated. We propose using 1-bit quantizers to solve the rate problem and also an algorithm with perfect performance in aspect of error rate is proposed. The mentioned algorithm is implemented on GPUs, which are available at C-RANs and resulted... 

Given a divisible finite field extension K/F, the structure of Br(F), the Brauer group of F, is investigated. It is shown that, if F is indivisible, then Br(F) ≃ Z_2, which generalizes the Frobenius Theorem. As a consequence, when F is indivisible, the class of all finite dimensional non-commutative F-central division algebras D having radicable multiplicative groups is determined. In fact, it is proved that the following statements are equivalent: (1) D is radicable, (2) D contains a divisible subfield K/F, and (3) D is the ordinary quaternion division algebra and F(√-1) is divisible  

In the last three years, the lives of many people around the world have changed with the spread of the Corona virus. In order to better manage the consequences related to the spread of this disease, extensive research has been done on this virus, and researchers in data science and artificial intelligence have devoted a part of their research to studying the effects of this virus on the people in one or different societies.On the other hand, the study of social networks about a specific issue or trend topic, allows us to examine more closely the atmosphere that governs the society and analyze the emotions, feelings and the level of concern of the members of the society about that issue.The... 

In the extension of his former developments of the theories of philosophy of mind and language, John Searle (1932- ) proceeded into the realm of social reality by his The Construction of Social Reality and Making the Social World, written in 1995 and 2010 respectively. With his naturalistic background, he placed his new theory on top of his former theories of mind and language already naturalized and fully worked out. As we will see, social reality comes with our three marvelous capacities, not coming together, to the extent we know, in animals other than us: collective intentionality, assignment of function, and language; all of them already being treated by Searle, in a naturalized manner,... 

Detection and determination of ultra-trace electroactive materials using electrochemical methods have been widely employed by researchers since they offer a fast, easy and reliable approach. In this way, developing of new nanoelectrodes with special and unique properties plays a profound role on the achievement of better results.
Gold nanoelectrode ensembles are one of the most important nanoelectrodes which due to the high surface area, chemical, electrochemical and physical stability, and integration of a large number of individual nanoelectrodes, introduce excellent opportunities to be employed as promising nanoelectrodes in determinations applications.
In this work, preparation... 

Sohail Inayatullah is one of the most successful futurists of the last decade. His proposed method for futures studies, which is called Causal Layered Analysis (CLA), has attracted a lot of attention and has won futurists’ admiration. Although, Wendell Bell counts the study of epistemological foundations of futures studies as one of the major purposes in this field, unfortunately, no significant attempt has been made to clarify the epistemological foundation of CLA, up to this time. The primary purpose of this thesis is to relieve this weakness. Inayatullah calls his approach, in developing CLA, “critical”. On the other hand, Wendell Bell claims that Roy Bhaskar’s “critical realism” is an... 

In this work, the in-motion estimation of Euler angles of a strapdown inertial navigation system is studied using a speedometer, as an aided navigation sensor. First, the derivation of governing error equations has been done. Then, the most appropriate heuristic filters available in references have been chosen for this study. Among this filters, unscented particle filter, that has better performance and conditions for the real-time implementation, has been chosen. Then, an innovative solution for improving the performance of this filter is presented. The proposed filter uses particle swarm optimization to resample the particles. The proposed... 

In recent years, much attention has been paid to the preparation of nanoparticles as carriers for drug delivery. Nanoparticle carriers, by changing the pharmacokinetic properties of the drug, improve the function of the drug and reduce its side effects. In the manufacture of nanoparticles, various materials such as polymers, metal particles, lipids, etc. are used to transfer the drugs, which can produce a different shape and size of the particles depending on their production method. The purpose of this project is the synthesis of liposomal nanoparticles (as nano-carriers) to load an antibiotic (Eucalyptus oil) and study the release of the encapsulated drug in the simulated environment of... 

Bones adapt their form and structure to make an efficient use of their mass against the applied mechanical loads. So, it is not surprising to assume that the geometry and density distribution of a bone contains information about its loading history. The objective of this work was to develop a framework to simulate the bone remodeling procedure as a topology optimization process and then use this framework to develop a simple technique for estimating the dominant joint loads based on the bone’s density distribution.
At first, the remodeling equation was derived from the structural optimization task of minimizing the strain energy in each time step, using the level set method. Employment... 

An accurate numerical methodology for capturing the field quantities a center lamellar inhomogeneity within the interface of two different phases of a bimaterial rectangular plate subjected to non-uniform tensile stress, in the context of reproducing kernel particle method (RKPM), is of particular interest. For this purpose the innovative numerical technique, so-called extended augmented corrected collocation method is introduced; this technique is an extension of the augmented corrected collocation method used for imposing continuity condition of the displacement at the interface. The robustness of this methodology is shown by solving problems of material discontinuities, namely plates... 

Self-excitation vibration or chatter in the milling process is one of the most critical factors in reducing the tool life and surface smoothness. With the change of tool speed or depth of cut, bifurcation phenomena occur at some points (bifurcation points) such that the system behaviour becomes unstable and the chatter is observed. In this study, using nonlinear modelling for cutting forces, two main methods for active control of this process are proposed. The first is an intelligent control based on emotional learning, which is a model-free strategy. In this method, the critic generates a signal (stress signal) using error and its derivative. The purpose of this controller is to reduce the... 

Linear position sensors are widely used in linear motion-control drives. In this thesis, the design, optimization, performance analysis, and prototyping of a linear variable reluctance, variable area resolver is discussed. To test the new design approach of the studied sensor, three-dimensional time-stepping finite element analysis (3-D TSFEA) is crucial. However, the 3D TSFEA is a very time-consuming method which leads to an inappropriate choice for co-using with optimization algorithms. Hence, an accurate analytical model based on a winding function (WF) method presented in favor of calculating the inductances, air-gap flux density, induced voltages precisely and yet is a very fast method,...