Sharif Digital Repository

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... 

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... 

One of issues of human in this time is questions about epistemology. Human sometimes faced with this qustion that "Is it any knowledge for human being". Sometime he or she answers this question: yes and search for any knowledge around him or her. In the context of philosophy of science these question are very imortant. In philosophy of science one of major question is how many of factors in science is subjective and how many is objective? It is obvious that one of solution to answer this question is investigation of factors that construct the knowledege. Furthermore in this thesis I try to answer that question in context of Hikmat' Motealieh. In this context all of factors that involved in... 

Many simulation optimization problems are defined in random settings and their inputs have uncertainty. Therefore, in defining an optimal solution for these problems, uncertainties should be taken into account. The primary way of dealing with this , is Robust Optimization which finds solution immune to these changing settings. Aiming at finding a new approach for simulation optimization problems, this study investigates these uncertainties and robust methods. In the optimization problem, the goal and constraints are considered with separate risk measures and a related problem is defined as follows: Minimizing the weighted sum of all risks subject to the problem constraints. To solve the... 

Phenolic compounds are hazardous pollutants that are released into environment through wastewater discharges from variety of industries. Although good biodegradability has been reported at low concentrations, but at higher concentrations phenols are known to be antibacterial. In this study the Membrane Biological Reactor (MBR) with submerged hallow fiber membrane was operated at 25±2 ºC and pH=7.5±0.5 to treat a synthetic wastewater containing high phenol concentration (up to 5.9 g/l). Removal efficiency of phenol and COD were evaluated at four various “Hydraulic Retention Times” (HRT) of 24, 12, 8 and 4 hours. To test the tolerance of the bioreactor to phenol concentration various loading... 

Wireless Sensor Networks (WSNs) consist of sensor nodes that are connected to each other and are widely used in many applications to acquire and process information. WSN nodes are battery powered, therefore energy management is a key factor for long live network. Node radio transceiver unit uses the most part of energy resource of the node and as a result limits the network lifetime. One way to prolong lifetime of network is to utilize routing protocols to manage energy consumption. To have an energy efficient protocol, we can apply cluster organization on the network, where sensor nodes are partitioned into groups called cluster. Then, the whole cluster data is sent through Cluster Head... 

During years, supersymmetry has been a candidate for resolution of Higgs mass fine-tuning problem that is quadratic dependence of scalar mass radiative correction to UV-physics. So, supersymmetry phenomenology is of great importance. As accelerators have reached energy of 13 TeV in recent years and sparticles have not yet been observed, it is important to have a theory in hand, describing SUSY breaking dynamics with scale of SUSY breaking above the energies currently accessible to accelerators. As a result of mass-sum-rule constraint which holds in theories with spontaneous SUSY breaking at tree level and leads to light sparticles and even tachyonic directions, there are currently no... 

Biomechanical models require body posture to evaluate the risk of musculoskeletal injuries during daily/occupational activities like manual material handling (MMH). The procedure to measure body posture via motion-analysis techniques is complex, time-consuming, and limited to equipped laboratories. This study aims to develop an easy-to-use yet accurate model that predict human whole-body static posture (3D body coordinates and anatomical joint angles) during different MMH activities. Twenty healthy male right-handed individuals with body mass index between 18 and 26 performed 204 symmetric and asymmetric MMH activities. Each person reached (i.e., without any load in hands) the destinations... 

In recent years, Additive Manufacturing has been extensively used by various industries. These manufacturing processes produce components in a layer-by-layer manner; therefore, they do not impose any geometric constrains to engineers and provide designers with the freedom to design components. Nowadays, one of the primary goals of all industries is to utilize as few raw materials as possible; this way they can deal with the shortage of raw materials and improve their efficiency. Consequently, they implement topology optimization algorithms to design and produce their components. However, topology optimization algorithms result in complicated geometries that can only be fabricated by AM.... 

Effective theories compatible with quantum gravity have their specific features. These features are formulated within the framework of the Swampland program, in the form of Swampland conjectures. In this dissertation, we first briefly review some of the Swampland conjectures, their motivations, and implications. We then elaborate on our research aimed at better understanding these conjectures, and using them to gain a deeper insight into the properties of the universe. We proposed a bottom-up supergravity framework with string-inspired elements where the Higgs expectation value and the cosmological constant are correlated. In this paper, we studied the Higgs dynamics in nilpotent... 

Environmental pollution caused by human activities and advanced industrialization is an important problem in the modern era due to its toxic and adverse effects on the ecosystem and human health. Municipal solid waste, including food waste, is expected to increase due to increased urbanization, economic development, and population growth, while their bioconversion into value-added products can address this problem by reducing waste as well as minimizing dependence on fossil fuels and turn it into an opportunity. In this thesis, an integrated system is designed in which the organic fraction of municipal solid waste is converted into biogas through anaerobic digestion process, and after... 

Oil sludge is the most important waste of the oil industry, which, due to its production, needs to be treated and managed properly. In this research, an integrated process of its gasification in supercritical water environment and Allam cycle is proposed. Then, the necessary investigations are done to purify the syngas to produce clean syngas with hydrogen of more than 40%. This plant is compared with an integrated gasification system and gas turbine in the second scenario. The life cycle analysis of these processes is examined from both environmental and economic aspects. The results show that by using the integrated process of synthesis gas and electricity production, from 841.875 kg/h of... 

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...