Sharif Digital Repository

Detection and classification of arrhythmia is important especially for patients in Emergency care units. Early diagnosis of cardiac arrhythmia makes it possible to choose appropriate anti arrhythmic drugs, and is thus very important for improving arrhythmia therapy. Computer-Assisted Diagnostic (CAD) Systems are used in recent decades in which extracted features and classifiers are the most important factor. In this project, we try to focus on both of these two major factors in heart arrhythmia classification using HRV signal. Therefore, in this project, we try to classify different groups of arrhythmia using HRV signal processing especially the nonlinear processing. Our main aim is to... 

Normal aggregates are replaced by polystyrene beads (EPS) due to their low unit weight. EPS concrete is known for its low density and environmentally friendly properties apart from having various pros such as better heat and sound isolation, affordability, and ease of construction. EPS grain size can also affect the compressive strength, and the tensile strength of EPS concrete compression is also inversely related to EPS grain diameter. The EPS concrete has four different percentages of EPS; 0%, 25%, 50%, and 75%. Each EPS percentage has six different unit weights; 15,20,25,30,35 and 40 kg/m3. In the present study 19 different types of mixing designs were used, the one with no EPS beads has... 

Hyperscale cloud data center (HCDC) (a.k.a., hyperscale data center) is the backbone of a wide variety of Internet services such as web-hosting, ecommerce, social networking, software as a service (SaaS), platform as a service (PaaS), application as a service (AaaS), and cloud computing.HCDC platforms consist of massive parallel processing, high utilization rate, and high volume storage that cost hundreds of million dollars.The increased demand for various Internet services and the subsequent dramatic growth in HCDC platforms, have caused an exponential increase in utilization of energy. With energy costs on the rise and global attention focused on carbon footprints, organizations are... 

The Vehicular Ad hoc Network (VANET) have been presented to enhance the safety and comfort of driver and passengers. Thus, the functionality of VANET is related to the accuracy of disseminated messages about surrounding environment. Therefore, it is critical to detect the true reports among false reports which they have been reported by malicious nodes. However, in this research, the proposed scheme presents a centralized trust management assessment scheme named Detection of Best Report (DBR) in vehicular ad hoc environments. Each received message is evaluated individually according to its reporter interactions during event reporting. Based on this evaluation in RSU, the most reliable nodes... 

In past decades, we have seen the rise of integration density in chips making it possible to design a whole system on a single chip. The previously designed interconnection architectures for multiprocessors systems cannot directly be applied in on-chip systems (especially when the number of processor elements increases) since they require a different type of a cost-performance trade-off. This is why the interconnection networks of systems-on-chip (SoC) are such a problem. Network-on-chip (NoC) was being proposed as a scalable and reusable communication platform for SoCs, which makes use of the network model to develop efficient on-chip communication infrastructures. The NoC has a layered and... 

Greenhouses offer a controlled environment for vegetable cultivation, but their high energy demands, particularly for heating, pose significant challenges. As one of the most energy-intensive systems in agriculture, greenhouses predominantly rely on fossil fuels, leading to adverse environmental impacts. Consequently, if the energy demands of greenhouses are met using conventional methods, in line with the expansion rate of cultivated areas, it will exacerbate the strain on the national energy system. This research proposes a solution through the development of “greener” greenhouses utilizing industrial symbiosis. By using waste resources from industries, specifically waste heat and carbon... 

The objective of the present study is the development of an optimization model to identify the best configuration of renewable-based integrated energy systems. The system includes a combination of renewable energy systems such as wind, solar, hydropower and hydrogen production, storage facilities, and conventional fossil-fuel generators. The developed tool consists of various modules where water-heating assumes the utilization of waste energy as an option. Furthermore, the application, which is demonstrated for a case study in Tehran has been considered. The power exchange with the distribution network and injection of hydrogen produced from excess renewable sources into gas network are... 

In this research, a review on fluoride adsorption revealed that the modification of the adsorber surface with ions like Ca2+ results in great enhancement of the fluoride adsorption. It seems that the enhancement in fluoride adsorption by the modified adsorber, is mainly due to the selective chemical binding of the fluoride ion with the surface-bound ion (Ca2+), regardless of the base material itself. In order to confirm this hypothesis, two different adsorber materials namely, γ-alumina (a material, conventionally used for fluoride removal from water and wastewater) and Micro-silica (a mineral with small adsorption capacity for fluoride) were selected for further study. It was found that the... 

The present study was aimed at developing a model to optimize the sizing of wind turbines according to the region’s wind condition and the capital costs of each part of the turbine. The proposed model, which consists of technical aerodynamic, economic and optimization sub-models, is used to achieve maximum annual energy production by a fixed cost of a single or a number of wind turbines. A cost model has been used to determine the detailed cost of the turbine’s components. The model’s results are presented for two regions in Iran, Khaf and Ahar, and the optimized configurations for a single turbine and a wind farm have been investigated.A case study for the region- Manjil that has some... 

Study of the structural flexibility of large-scale wind turbine components on aeroelastic performance is important under the existence of critical atmospheric conditions. Prediction and control the critical deformations, identifying maximum local deformation and modeling the forces involved, are required. Aeroelasticity analysis is a suitable method for studying the coupling effects of wind turbine aerodynamics, dynamics and structures. This research has been done by modeling wind turbine components including blades, hub, nacelle and tower, taking into account aerodynamic couplings, dynamics and structures. Considering the large scale of reference wind turbine, nonlinear equations have added... 

The issue of solid and fluid interaction in horizontal axis wind turbines with diameter of more than 120 meters is one of the most important researching subjects of this type of turbines. This issues needs quick and exact solutions because of the high computational cost of fluid and structural domains.In this research a quick method with acceptable accuracy has been suggested which is based on computational fluid dynamic to examine the aeroelastic behavior of rotor and wind turbine tower. The actuator disc method in two domains of axisymmetric and three-dimensional has been used to compute aerodynamic forces. For this purpose a code has been written in C++ to set down virtual momentum on... 

Inlet flow of afterburners comes from the burnt products of the primary combustion chamber. The fuel is injected and the mixture is ignited to form a flame which is stabilized behind a flameholder in the afterburner. Flame stability stems from wake (recirculation zone) of flameholder. With the aid of high residence time of flow behind the flameholder reactants get the time to catch activation energy. Some parameters like oxygen content, mass flow rate, inlet temperature, and nozzle area ratio play an important role in afterburner combustion efficiency and flame stability. In this study we focused on afterburner combustion stability in GE J85-21 engine. This engine will be in service through... 

This thesis represents the obstacle avoidance of a fixed-wing small aircraft using optical flow information of cameras mounted on the aircraft. The thesis consists of two main sections. In section one, the ideal optical flow has been simulated based on the camera model, complete six DOF of flight equations, and the geometry of the environment. An analytical formula has been derived to relate the obstacle detection distance to the maneuverability of the aircraft. Having the obstacle detection distance, the control and navigation algorithms have been developed to achieve a collision-free flight for the aircraft in urban canyons and junctions. The effect of some parameters such as approach... 

In the field of supply chain management, understanding the impact of centralized and decentralized decision-making approaches on overall performance is highly important, especially in environments characterized by uncertainty and complexity. This study introduces an innovative approach by incorporating uncertainty into the NK model framework, a model traditionally used for analyzing interdependencies and adaptability in complex systems. Through this, the research examines the dynamic interactions within supply chains under various levels of uncertainty and complexity, offering a more realistic simulation of real-world conditions. The results show that adding uncertainty to the model... 

It has been reported that in some organizations despite delegation according to its concept, some of the organization members don’t have an internal motivation to use the autonomy that has been delegated to them. This problem might have different aspects. From the self-determination theory perspective, this might be because of unsatisfied basic needs of the person. For example, if all options the person has, are desirable or all of the options are undesirable and the person can’t choose between them. This might result in unsatisfied basic needs of the person. Due to these conditions, there is a probability that she won’t have an internal motivation to use autonomy. In some researches, it has... 

Multi-period Value-at-Risk (VaR) forecasting is important for risk management. Financial institutions especially commercial banks according to Basel Committee regulations for capital adequacy in “Internal Approach”, should forecast their VaR for multi-period horizons (longer than one day). The most conventional approach for forecasting multi-period VaR is scaling one-day forecasted VaR that is called “square root of time rule”; therefore most works in this area have been focused on forecasting one-day VaR. In this study, we review performance of a wide range of different methods in forecasting multi-period VaR. The results of our study show that historical simulation performs weakly in... 

Institutional investors are among the main players of capital market and stock market. These investor’s activities on the one hand affect directly on indices, and on the other hand on transactions of other players in the stock market. In case the transactions of stockholders are not based on sufficient information and merely based on imitation of other investors, herding behavior would be taken place within them.In this study, using two methods of Lakonishok (1992) & Sias (2004), we consider herding behavior amongst the Institutional investors of Iran stock market.In both methods, weekly and monthly data are used for testing herding behavior in the short-run and quarterly data for the... 

The debate over the nature of perceptual states has been a significant part of the literature of philosophy of the mind during the past two decades. John Campbell's philosophical works on metaphysics and epistemology of sensory perception, according to many of his followers and critics, are among the most coherent contemporary philosophical works with recent advances in cognitive science. His research on the relationship between attention, reference, knowledge and spatial representations is to a large extent supported by scientific ideas in empirical psychology, and it can be said that most of his work is devoted to analyzing and solving the theoretical complexities deriving from empirical... 

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...