Sharif Digital Repository

Artificial intelligence (AI) has become an instrumental force in reshaping various sectors, especially in mobile networks. To realize AI as a service (AIaaS) and enable prompt decision-making, edge computing has risen as an innovative response, pushing computation closer to data sources. Although this is promising to reduce the dependency on remote cloud infrastructures and save the mobile devices’ energy, current methodologies display constraints in effectively distributing deep neural network (DNN) inference tasks, leading to possible resource underutilization and performance compromises. To tackle these issues, in this thesis, we study AIaaS at the edge and focus on renowned DNN... 

In the past several decades, with the increasing evolution of electricity markets, maintenance philosophy has gradually changed, and maintenance process plays a crucial role on the profitability and effectiveness of companies. Therefore, this leads managers to use modern strategies that their performance has been proved in various industries and therefore, traditional strategies have lost their effectiveness. Reliability-Centered Maintenance (RCM) is one of the most successful strategies wherein the maintenance process of system components is linked to improvements in the system reliability and profit of companies. RCM has not been thoroughly furnished in generation system yet. This thesis... 

In previous decades, easy access to material and low cost human power allow the product process to be performed in a preferred way. The limit in amount of material, economy, and the efficiency of the model has not been influential like these days. Today, the effective use of material and consideration of an economic model have great importance. It is obvious that a process of designing implies optimizing which the range of its using is also continuing in many engineering sciences. Many optimization issues contain discrete nature. Many of searching spaces that we encounter in the real world applications are not necessarily continuous as a condition which has crucial importance for classic... 

During an earthquake, if the seat width provided at the joint is less than the relative joint opening, the bridge’s superstructure becomes unseat which leads to potential collapse due to the lack of support. Because of the catastrophic consequences of loss of support and the perception that the damage could easily be prevented at relatively low cost, some retrofitting programs focus on preventing such failures involved the addition of longitudinal restrainer cables and bars to limit the relative movements at expansion joints. Noticing the weaknesses of usual restrainers including the transmission of excessive forces to substructures, weak capability of energy dissipation during severe... 

In field management workflow, after preparation of dynamic reservoir model, next step is determining the uncertain parameters and history matching. In this step, simulation model is conditioned to available field data. In this inverse problem, different geological and petrophysical properties may provide equally good history matches. Such diverse models are likely to show different production behaviors in future. This ties the history matching with the second step, uncertainty quantification of predictions. Multiple history matched models are essential for a realistic uncertainty estimate of the future field behavior.This thesis introduces the application of two novel population-based... 

In this study, a new bioink was introduced for the production of tubular tissue structures for cardiac tissue engineering by bioprinter using the FRESH (Freeform Reversible Embedding of Suspended Hydrogels) method. The novel bioink that we used was a combination of cardiac extracellular matrix (cECM) and oxidized alginate. The cardiac extracellular matrix was used to increase the biomimetic of the printed structures to the actual tissue of the body, and also to create sites for cell adhesion, and to improve cell growth and survival. We used alginate oxide (oxidation degree: 5%) to increase the mechanical properties of the tissue. Alginate oxidation has been due to extracellular matrix (ECM)... 

Embedded real-time systems have limitations on power consumption, mainly due to battery usage and temperature constraints. In addition, a large part of these systems has timing constraints. These constraints should be considered when we use power management techniques. Nowadays, due to the use of fault-tolerance techniques, power consumption and especially peak power consumption are increased so it can miss Thermal Design Power constraint. Recently, due to the conservative design of TDP for chips, it is not considered, and hence, a new power constraint as Thermal Safe Power is defined for thermal and power characteristic of the system. The purpose of this study is to define an optimization... 

The short life of Polymer Electrolyte Membrane (PEM) fuel cells is one of the critical criteria to their commercialization. A longer operation life time should be achieved to reach high reliability, low $/kWh cost and to use fuel cells as economical alternative energy systems.Therefore,diagnosing degradation mechanisms and the causes of power loss in fuel cell life time is of great importance. Operating conditions affect output power density and performance degradation. To achieve maximum power generation through fuel cell life time, a model is needed which is able to estimate power density and performance degradation simultaneously regarding to operating conditions. In present work, a... 

Obtaining high profit is the ultimate goal of an investor in the financial market. The key to achieve high profits in stock trading is to find the right time to trade with minimum business risk. However, it is difficult, often, to make decision about the best time to buy or sell some stocks due to the extremely dynamic and volatile behavior of the stock market. In order to resolve these problems, two steps have been followed in this research:1) Create a model to predict the final price of the stock with small error rate, and 2) Suggest the best stocks for trading to the trader. In order to achieve the goals of the first step, the stock price data of Hcltech, Maruti, Axisbank is selected and... 

The energy systems efficiency is a great issue confront power plants professionals. Besides using high-tech components in power plants, plant operation optimization can significantly improve energy efficiency and economic performance, as efficiency of plant components generally depends on operating conditions. In addition, system preventive maintenance can reduce plant operation and failure costs, however it is also costly when done frequently. Therefore, optimizing operating conditions and preventive maintenance intervals can minimize the expected total cost of plant due to operation, failures and preventive maintenances. In recent years, the use of optimization models to determine plant... 

High efficiency and low-emission fuel cells have the capacity to replace fossil fuels for energy supply concerns. Solid oxide fuel cells operate in relatively high temperature and have power plant applications. Hence, they are acquainted to be coupled with cycle gas turbine to reduce the cost and increase the overall system efficiency. The control of these hybrid systems is so important. Due to the system nonlinearity and having more than one controlled variable, its control with classic methods would be difficult. The model based predictive control is used as an alternative to mitigate these difficulties. In addition to their high performance, their extension to the multivariate case would... 

Kidney transplants are vital for patients with end-stage kidney disease. Therefore, it is essential to allocate kidneys to patients efficiently. Kidney Exchange Programs allow patients with incompatible donors to exchange donors and receive a suitable kidney. In practice, these exchanges occur within cyclic or chain-like structures. Planned transplants may be canceled before the transplant takes place, for a variety of reasons. Failure of one transplant in a cycle or chain can result in the failure of all transplants in that cycle or chain, which can lead to drastic inefficiency in the exchange program.In this thesis, we study kidney exchange programs under uncertainty. We consider... 

Micro-robotics is one of the currently emerging technologies which has attracted attentions for its probable applications in different fields including biotechnology, diagnosis and treatment in medical engineering as well as general studies in micro-scale science and engineering. Magnetic micro-robotics is considered as the most promising group, primarily due to the biocompatibility of magnetic fields and advances in electronic circuits to produce and control such fields. One critical point in utilizing these robots is their high density in comparison with the working fluid and their tendency to sink. In this thesis, a method to fabricate buoyant magnetic robots has been proposed based on... 

Nowadays evolutionary algorithms help developers to solve many problems in applied science and engineering aspects. So the main goal of this thesis is to apply and verify the ability of evolutionary algorithms and artificial neural networks in optimization of Ethane recovery unit. Algorithms applied in this study are Ant Colony Algorithm, Artificial Immune Systems Algorithm, Incremental Evolutionary Algorithm, Chaotic Based Algorithm, Variable Population Size Genetic Algorithm, Frog Leaping Algorithm, Frog Leaping with Bacterial Optimization Approach and Different types of Particle Swarm Optimization Algorithm. Optimization methods based on local search are also applied in order to compare... 

In this thesis the problem of path planning for aerial robots,specifically the UAVs, is studied. Some software packs aiming to perform optimal path planning are already published worldwide. In this thesis, these software are investigated and UAV path planning is done by them. In UAV path planning using these software, due to the high number of equations, number of constraints in solution increases and even in a simple problem, the process of solving becomes difficult for software. Among introduced software packs, “GPOPS”, which uses pseudospectral methods, is chosen as the best. Avoiding obstacles in different problems is checked. Obstacle avoidance and waypoint tracking at the same time,... 

In this study, both axial dispersion and perfect mix mathematical model to simulate a three-phase slurry bubble column reactor for direct synthesis of dimethyl ether (DME) from syngas and CO2 is developed. This large-scale reactor is modeled by using mass and energy balances, catalyst sedimentation and single-bubble as well as; two-bubbles’ class flow hydrodynamics. A comparison between the two hydrodynamic models with pilot plant experimental data from the literature showed that heterogeneous two-bubbles flow model is in better agreement with the experimental data than homogeneous single-bubbles gas flow model. Also, by investigating the heterogeneous gas flow and axial dispersion model for... 

Human blood is a valuable and scarce product which is only produced by human body. There is no replaceable material for our blood and there has always been a constant need to donors and blood products in societies. Like every other product, blood has to be transfused to patients after it is donated and this process requires a complete and effective blood supply chain. Considering all properties, complexities and uncertainties of a blood supply chain, we need to develop stable methodologies in order to simplify decision making in blood supply chain. In this research, we develop a novel blood distribution system from a regional blood center (RBC) to its nearby hospitals. It helps RBCs plan the... 

Next generation wireless networks support high data rates and QoS parameters of various users. OFMDA is a popular transmission technique to support high rate transmission, however in multi-access environments, it relies on careful resource allocation to guarantee the desired QoS parameters. While resource allocation in centralized scenarios such as cellular networks is relatively straightforward, the problem becomes quite complex in distributed scheduling of multiple access environments. One key resource is power assigned to each sub-channel which determines the overall transmission capacity.In this dissertation, firstly we introduce some cross layer QoS provisioning or power efficient QoS... 

Nowadays, gas turbines are from the most widely used devices in terms of power generation. According to their vital role in suppling electrical power required for daily life and their widespread application in power plants, tremendous efforts have been made to improve the efficiency of gas turbine working cycle. One of the most applicable methods to optimize a gas turbine is to cool the compressor inlet air. Applying an absorption chiller is a wisely technique especially when it comes to hot and humid weather condition. In this thesis, effects of applying an absorption chiller with specified technical facts on the performance of gas turbines, which are now functional in Kish Island power... 

We study the optimization of the payoff of a decision-maker (a player or a team) in the presence of an adversary who wishes to minimize the payoff of the decision-maker. In this situation, the decision-maker can puzzle the adversary by playing random actions and hence, gain more payoff. We assume that the decision-maker has limited access to randomness sources and is only allowed to randomize his actions by conditioning them to the limited randomness sourse to which he has access. We consider two models: in the first model, in each stage, the decision maker observes a random source independent of past, and distributed according to a time invariant probability distribution. The adversary...