Sharif Digital Repository

In this thesis, we take into account a heterogeneous network comprising of both untrusted energy harvesting receivers (UEHRs) and information receiving nodes. Our aim is to securely transmit information-bearing signals from a multi-antenna base station to multiple legitimate users, while simultaneously providing the required energy of UEHRs. In other words, the UEHRs need to receive a minimum required energy to work, however, they might be curious about the signals sent from the BS. Accordingly, we propose a secure rate-splitting multiple access (RSMA)-based technique to facilitate the procedure of serving information receiving nodes, while keeping the useful information secret from UEHRs.... 

Quality of Experience (QoE) indicates the overall quality of one service such as Voice over IP (VoIP) from users' point of view by considering several systems, human, and contextual factors. QoE measurement and prediction are more challenging than Quality of Service (QoS) which is only related to network parameters. There exist various objective and subjective methods for QoE prediction. This research investigates various features affecting QoE by proposing a comprehensive subjective evaluation by employing a large number of users. We show that many unconsidered factors including speaker specifications and signal properties, such as signal-to-noise ratio (SNR), can affect QoE so that the SNR... 

To gain commercial competitive advantage in a constantly changing business environment, demand forecasting is very crucial for an organization in order to make right decisions regarding manufacturing and inventory management. The objective of this thesis is to propose a forecasting technique which is modeled by artificial neural-fuzzy networks. The effectiveness of the proposed approach to the demand forecasting issue is demonstrated using real-word data. Then we investigate a suitability of a decision-making model for airline route planning based on the so called “Game Theory”. The model is helpful to decide whether a new route is, in fact, needed. Different case studies reveal that... 

As humans age, the intervertebral discs in the spine lose some of their water content, reducing their flexibility and making them more prone to tears in the annulus fibrosus. When the annulus fibrosus weakens, the disc's nucleus can push through and cause a herniation, which can press on surrounding nerves and lead to severe pain. Each surgical method for treating disc herniation has its own complications and challenges. The gold standard treatment is fusion surgery, which fixes two vertebrae together, preventing natural movement in that part of the spine. This altered stress distribution on adjacent vertebrae can ultimately damage adjacent healthy discs over time. This research aims to use... 

Condition monitoring of machinery is of significant economic importance to mitigate production losses resulting from downtimes. Unforeseen failure of roller element bearings is the most common issue observed in industrial units. However, detecting and tracking the progression of these failures through machine vibration monitoring and predicting the deterioration of these rotating components are viable solutions. Numerous studies have focused on using laboratory accelerated life test data for fault detection and remaining useful life prediction of these components. While online monitoring of all equipment in the industry may not be feasible, and conditions in the field differ from laboratory... 

Intelligent predictive maintenance is recognized as a cornerstone of Industry 4.0, where intelligent software is employed for the early detection of faults and the prevention of unexpected failures. Recent research indicates that the integration of multi-sensor data for fault diagnosis of gearboxes and bearings, using artificial intelligence models, has been successful. However, conventional methods face several challenges. These include an over-reliance on the signal characteristics of a single sensor and the impracticality of applying intelligent learning methods, particularly deep learning, despite their high potential, due to the unavailability of sufficiently large and diverse... 

In this thesis, combustion of liquid fuel spray under the condition of hot and diluted oxidizer, has been investigated. To this end, a novel type laboratory-scale test rig was designed to study the physics governing the MILD-Spray combustion conditions with an applied approach. The underlined test rig eliminates the operational problems of its predecessor test stands and is used for a heavier fuel with much more complex chemical composition (kerosene). The test section is axially symmetrical, in which the fuel is injected by a pressure-swirl atomizer in the direction of hot and diluted co-flowing air. With the use of the aforesaid test rig, the effect of variables such as oxygen...