Sharif Digital Repository

Isogeometric Analysis method is a newly introduced method for the analysis of problems governed by partial differential equations. The method has some features in common with the finite element method and some in common with the mesh-less methods. This method uses the Non-Uniform Rational B-Splines (NURBS) functions as basis function for analysis. With this basis functions, the refinement procedure is much easier than the classical finite element method by eliminating the need to communicate with the CAD model. Modeling cracks in classical finite element method requires very fine mesh near the crack tip. One can model crack propagation by means of classical finite element, using an updating... 

In the era of the internet and with the emergence of online stores, the possibility of changing prices for these e-commerce platforms has become simple and virtually cost-free. This allows them to adjust prices optimally in response to environmental and surrounding factors, maximizing their revenue from product sales. This development has led to numerous applications of statistical learning methods, particularly online learning, in these markets. In this thesis, we explore the issue of online pricing from various perspectives. One aspect is that product pricing is based on their features, which can be numerous. This leads us to the use of online learning methods and statistical learning in... 

Wear is the most important cause of surface damage occurs by direct contact of surfaces. Increasing the quality and strength of surface against different kinds of destructive phenomena is significant in manufacturing of mechanical parts. Surface nanocrystallisation can improve the surface protection against wear and can be done by lazer beam and shot peening. In this investigation by sever shot peening process the surface of A356 Aluminium alloy transforms to nanocrystal structure. The dry sliding wear and friction behaviors of A356 Aluminum were evaluated using a pin-on-disk apparatus at ambient conditions. The stationary diameter of 5mm stainless steel pin produced a wear track (scar) on... 

Regarding the increasing trend of network costumers and services, requirement of high-speed and high quality seems to be inevitable. Therefor much effort has been put to issue the problem properly in recent years. Optical fiber networks are attending more attention and optical fiber channels are dominating the world of networking and data. Applying new methods such as CDMA and OFDM raise the issue of maximum achievable rate and quality of these systems.These include the main concentration of this project. First, optical channels are modeled.Then, applying OFDM and CDMA methods, lower and upper bound of channel capacity will be determined  

Critical sets and defining sets in combinatorics have been attended by mathematics fans. These subjects have been debated since 1997 and a lot of researches have been done about them and a lot of articles have been published. But number of unsolved questions might be more than answered questions. In these years critical sets for Latin square and defining sets for vertex coloring have been attended and also enough researches about issues related to defining sets for edge coloring and total coloring have not been done. For these reasons we focus on these issues in this thesis. Issues like defining sets for edge coloring and total coloring in complete graphs, generalized Petersen graphs and also... 

Design of superconducting material based wide band radiation detectors has recently been attractive. Interesting features of detectors, which are based on Josephson Junctions such as high sensitivity in a wide range of frequencies and low power consumption, potentially have many advantages over other semiconductor-based photo-detectors. According to variety of applications of high-Tc superconductors, particularly YBCO, and significant progress in manufacturing of thin films and Josephson junctions, this thesis mainly focuses on investigation of radiation effects on I-V characteristics of high-Tc step-edge Josephson junctions experimentally. The current-voltage characteristics of fabricated... 

In this dissertation, Data analysis and information retrieval from incomplete observations are investigated in different applications. Incomplete observations may be induced by lack of observations or part of data affected by specific noise (quantization noise). Data-driven algorithms are among important hot topics. Our goal is to process the lost information inducing certain assumption on big data structures. Then, the approach is to mathematically model the problem of interest as an optimization problem. Next, the designed algorithms for the optimization problems are proposed trying to cut down on the computational complexity of as well as enhancing recovery accuracy for big data... 

The Internet of Things (IoT) is one of the fields witnessing a significant growth in recent years and is expected to make the lives of so many people go under substantial changes. IoT will exploit large numbers of smart objects in people’s everyday life to bring smartness into reality and this necessitates correct and seamless connection and integration between smart entities. One of the key tasks of the IoT platform is providing such a connection, which is assigned to the resource discovery framework.A resource discovery framework should consider requirements and challenges present in the IoT environment. Heeding the literature, one finds deficiencies in this field. These shortcomings are... 

One of the best ways to overcome the weaknesses of technology services in different industries is right technology transfer with feasibility in the country. 3D painters have been recently widely used industrially in different countries. The 3D printer is one of the new emerging technologies, enabling the production of every 3D objects with any complexity. 3D printing has provided the possibility of producing, in fastest, more economics and regardless of those complexities. By transfer of this kind of technology and proper management, a huge transformation can created in all industries and factories. To do this, there are several technologies of 3D printing, that each of them used in various... 

The most important challenge in microgrids is the coordination of distributed energy resources (DERs), due to the existence of several DERs with fugacious characteristics. Also, energy management in the microgrid is very important because there may be conflicting needs or poor communication between different elements of the microgrid. In this work, a robust frame associated with a quantum version of the Teaching-Learning-Based Optimization (quantum TLBO) algorithm is proposed for the first time to the microgrid optimal energy management problem. Uncertainties in the load and in the output power of renewable energy sources are modeled using robust optimization (RO). The operation cost of the... 

Nowadays electricity power has a key role in developing various aspects of the world. The great importance of fossil fuel power plants come from their large contribution in electricity power generation. Among the different fossil fuel power generation technologies, supercritical power plants have great advantages. They are an advanced power generation technology with high plant efficiency, high coal utilization and low emission. Their complexity and existing many unavoidable uncertainty sources in their dynamic such as changes of ambient temperature, climate condition and wear of components make their control challenging. To overcome mentioned problems and achieving a good performance, a... 

The relationship between art and philosophy has been disputed for a long time and its history goes back to the ancient Greece. The dominant literary form at that time was poetry or tragedy, which are the first side of this relationship. On the other side was philosophical ethics. Plato and Aristotle are the main protagonists in this quarrel, which is known as the "Ancient Quarrel". I will first examine this quarrel and follow its different forms in the modern era, in which Hegel plays a prominent role by proposing the "end of art" thesis. By examining the criticisms made to this thesis, I will make clear the context in which the contemporary defenses that I explained in the following... 

Expert finding is an important task in community question answering (CQA) websites, enabling the routing of new questions towards users who have the highest level of expertise in the relevant topic. This method helps question raisers receive satisfactory responses in a shorter time and makes it easier for answerers to find questions they are interested in and have enough expertise to answer. . The primary goal in expert finding is to learn the representation of questions and expert candidates based on the history of answered questions. Many existing approaches generate a unique representation for users without considering the specific question asked. Additionally, many of these approaches... 

Hard disk drives are the main component of computers for permanent data storage. The security of the stored data is related closely to the air gap between the read-write head and the surface of disk. This gap which is created by the aerodynamic force between head and the disk is altered continually by lateral oscillations of disk. In the extreme condition of zero gap and contact between the protective coating layer and subsequently the magnetic material of the disk with the head, the disk will be scratched and damaged. Therefore, the active or passive control of these vibrations has a particular importance in the technology of manufacturing of hard disks. The first step in active control... 

Phospholipid vesicles are able to carry drugs or DNA to infected or cancerous cells. The blood flow can carry them to their target positions but their performance will be enhanced if they complete their attack by swimming in final stages of their journey. Vesicles built only by lipid molecules have rotational symmetry and undergo a random motion in their solvents without having a preferred direction. In this project, we break the symmetrical shape of phospholipid vesicles by a cluster of transmembrane proteins. We use a triangulated model of the membrane, apply the method of multi-particle collision dynamics to the motion of solvent particles, and simulate the motility of vesicles for... 

The Hubbard model is one of the simplest interacting models in theoretical physics, especially condensed matter physics which despite its simplicity, its solutions are highly nontrivial and intractable. After 5 decades since its introduction, its phase diagram is not fully understood and whether or not, it has a high-temperature superconducting phase. In this thesis, we aim to employ the recent advances in machine learning and GPU programming to accelerate the QMC method. By accelerated QMC methods, we can explore the Hubbard model's phase diagram more efficiently. Using massive parallelization of the GPUs can speed up the measuring process by several times. The self-learning quantum...