Sharif Digital Repository

In many papers, GDP is used as a measure of economic growth, which is shown to possess a nonlinear structure. The study focuses on the nonlinear Granger causality between liquidity, government spending, oil revenues and economic growth by markov-switching vector autoregressive and markov- switching Granger causality approach for the period of 1369-1397 for Iran. The empirical results from MSAI(2)-VAR(4) suggest that Oil revenues and government spending have a significant impact on economic growth in both regimes. Also, markov- switching Granger causality results are quite different from the traditional Granger causality results, that suggests the nonlinear Granger causality has more... 

In this project, we investigate the influence of angular momentum of Light on the Dirac matter. We show that polarization or spin of light can change the population of [pseudo-]spins. In graphene, pseudo-spins indicate the probability of existing elec-trons in each sub-lattice. However, the two different sub-lattices are the same and the contribution from two distinct Dirac cones cancel out. Therefore, the change in the population of pseudo-spins does not happen. On the other hand, in topological insulators we have just one Dirac cone; thus, polarization of light can change the population of [pseudo-]spins  

Reducing the size of transistors has dramatically increased the impacts of NBTI, HCI, and EM phenomena in comparison with decade ago. These phenomena are able to have influence on properties of different parts of a chip to make it changed gradually; including threshold voltage of a transistor and electrical conductivity of interconnections. These changes are known as the aging of a transistors that diminish the performance and reliability of a chip. A common reason that plays a significant role in all these phenomena is temperature. The temperature becomes more important when the power density increases per unit area due to decreased size of transistors, which is a trend in multi-core... 

Deposition of solid particles present in the process air on the walls of furnaces is one of the challenges in industries. This phenomenon has various causes. For example, in a furnace, the temperature of particles increases as they pass in front of the furnace burners, and due to the softening of the particles, their chances of deposition increase when they collide with the walls. Over time, with the growth of deposited particle layers on the combustion chamber walls, the performance of the combustion system gradually becomes impaired. present research aims to design air jets intersecting with the process air path, with the purpose of reducing the temperature of particles prone to deposition... 

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... 

The use of microelectrode arrays in neural networks has offered a wonderful opportunity for evaluating numerous properties and interactions with excitable tissues such as the brain and spinal cord in the laboratory. In neural network applications, microelectrode arrays can be utilized to analyze nerve impulses or interact with neurons. They are either used to record neural data or to stimulate spinal cord nerves. Previous research has revealed that stimulating the spinal epidural region can help restore after spinal cord injuries (SCIs), which is the key to using them in the rehabilitation of living beings, including humans. According to the international campaign for the treatment of SCI... 

In this study, at first the V2O5 spent catalysts were characterized. The aim was to identifying whether these catalyst may be regenerated. Then, for feasibility study of them, three methods were applied: washing, diffusion and milling the spent catalysts for their subsequent reproduction. A variety of techniques such as XRD, XRF, AAS, TPR and TPO were applied in order to identify factors contributing in vanadium pentoxide catalysts deactivation. The results showed that approximately all of pollutants caused their performance deterioration, while they still have some active phases. Then, the polluted catalysts were washed (their yield increased from 43% to 72.2%). In the underside of the... 

Noise or noise pollution, is defined as an unwanted sound, produced mostly by motor vehicles in urban areas. If the noise exceeds its limit, adverse effects on users and citizens are expected. Thus the assessment of the noise level and its comparison with allowable values is mandatory. Traffic induced noise depends upon different factors such as traffic, weather, and, sound barriers. Noise pollution study has a long history all over the world. Many studies, mostly representing the outdoor noise pollution models, have been done in recent years. This paper presents an assessment of traffic-induced noise in a heavily traveled tunnel, locally referred to as Resalat tunnel, which is located in... 

Data collected from street networks show that travel time in urban street networks is a stochastic variable, whose range of variation increases with the congestion level. Work and school trips comprise the major part of morning peak volumes, whose common characteristic is that they need to be made on time. For this reason, these travelers are pessimistic in their route choice, and try to choose routes which are more reliable. Travel time standard deviation is one of the common measures for estimating travel time reliability that is related to properties of day-to-day travel time distribution on a particular route. Based on the empirical data collected from Tehran street network, this paper... 

With the advancement of automotive industry, the number of electronic systems that need to communicate with each other has increased. An effective strategy to meet these growing demands is using bus-based protocols, which can establish safe communication among numerous nodes with reasonable cost, weight, and space requirements. The objective of this thesis is the design and implementation of a transceiver based on the FlexRay protocol. The significance of this protocol lies in its ability to provide higher data transmission rates compared to other protocols like CAN and LIN, and its role as the foundational communication medium among various domains in modern vehicle architectures. In this... 

In this thesis, we introduce a novel Artificial Intelligence (AI) system inspired by the philosophical and psychoanalytical concept of imagination as a ``Re-construction of Experiences". Our AI system is equipped with an imagination-inspired module that bridges the gap between textual inputs and other modalities, enriching the derived information based on previously learned experiences. A unique feature of our system is its ability to formulate independent perceptions of inputs. This leads to unique interpretations of a concept that may differ from human interpretations but are equally valid, a phenomenon we term as ``Interpretable Misunderstanding". We employ large-scale models,... 

Quantum entanglement is an essential resource in quantum information processing, such as quantum communication and quantum computing. Although entanglement is critical for practical implementations in these fields, creating and transmitting entanglement without altering the states is challenging. External noise may destroy or weaken the entanglement. Consequently, there is a need for methods to improve entanglement. Entanglement distillation is an effort to address this issue. It is a process where, probabilistically, a smaller number of strongly entangled states are created from a fixed number of noisy entangled states. This process is carried out using only local operations and classical... 

Fabrication and characterization of different surface charged cellulose electrospun scaffolds including cellulose acetate, cellulose, carboxymethyl cellulose and quaternary ammonium cationic cellulose for biomedical applications have been reported in this research. We describe preparation of cellulosic nanofibers through the electrospinning following deacetylation cellulose acetate. Moreover, surface modification of electrospun cellulose nanofibers is carried out to obtain carboxymethyl cellulose and quaternized cellulose nanofibers, respectively. At last, the structural, morphological, mechanical, swelling, wettability and the cell culture properties of the scaffolds were analyzed and... 

In this research, non-isothermal annealing process at temperatures ranging between 400°C to 830 °C was investigated in warm and cold-rolled austenitic stainless steel 304L. First, the wide variety of austenitic to martensitic structure was produced by the multi-pass rolling process at room temperature -8 °C, 200 °C, and 280°C. The n exponent in Olson-Cohen equation was governed 2.83 after non-linear curve fitting to assess the fraction of deformation-induced martensite as a function of strain. Afterward, Abaqus/Explicit method was utilized to achieve the stored energy and plastic strains distribution through the thickness. Then, Cellular automata and Galerkin-finite element models were... 

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... 

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... 

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... 

As it is known, one of the dangerous consequences of the earthquake is the possibility of fire. In recent years in our country special attention have been paid to design and retrofit buildings against earthquakes, but have not done to understand the behavior and design concepts of structures against fire. One of the reasons is the lack of information and the absence of a specific standard for design of structures against fire. Since the beam-to-column connections play an important role in the performance of structures, in this study, the behavior of the moment frame with flush end plate was investigated by testing on a small scale structural model (half scale). It is observed that, the test...