Sharif Digital Repository

Due to the diameter and size of nanoparticles, they have been applied in various fields to make materials with better properties. In this thesis, the purpose has been to investigate the influence of nano alumina and nano alumina incorporating nano silica particles on mechanical properties of cement mortars. Different portions of nano alumina that include 1, 3, and 5% have been used. Nano silica with 1 and 2% has been used. At first, nano particles were dispersed by sonication with water, and then the cement mortars with various percent of nano additives with the same workability have been made. After different curing periods (7, 28 days), the specimens have been tested for bending and... 

A triple antibiotic mixture (ciprofloxacin, metronidazole, and minocycline) has been used for dental root canal medicaments in pulp regeneration therapy. However, tooth discolorations, cervical root fractures, and inadequate pulp-dentin formation have been reported due to the triple antibiotic regimen. Therefore, antibiotic containing scaffold has been developed to minimize the clinical limitations and maximize a natural healing process in root canal infections. The ideal controlled release drug device should have the following characteristics. It should not degrade inside the root canal and it should be easily inserted into and removed from the root canal. In addition, the drug should be... 

The problem of attitude determination (AD) has always been a challenging issue for space missions that is of importance either independently or for attitude control purposes. The problem of AD is generally focused from two aspects: measurement mechanisms (sensoring) and determination algorithms. From the former point of view, there exists a variety of measuring systems such as the Sun sensors, magnetometers, gyroscopes, star and horizon sensors that have been separately or collaboratively utilized for AD. Integrative usage of sensors not only can bring about added advantages in terms of accuracy, but also provides for estimates of attitude during special times such as the Sun eclipse. The... 

The current research is devoted to the design and optimization of a Blended Wing Body aircraft configuration in the conceptual design phase. In this respect, two objective functions with eight design variables have been considered within the optimization process in order to reach to a desired design. The key objective functions include the aerodynamic efficiency as well as the aircraft empty weight alongside the longitudinal stability requirement that are accounted for within the Genetic algorithm optimization loop. In this regard, some analytical and semi-empirical relations are utilized to determine the aerodynamic and structural characteristics of different designs alongside the numerical... 

Membership inference attacks are one of the most important privacy-violating attacks in machine learning, as well as infrastructure of more serious attacks such as data extraction attacks. Since membership inference attack is used as a measure to evaluate the level of privacy protection of machine learning models, different researches have investigated and provided new methods for this attack. However, the accuracy of these attacks has not been investigated on models trained with the latest techniques such as data augmentation and regularization techniques. In this research, we see that the Lira attack, the latest membership inference attack, which has much more power compared to previous... 

In a GAN, the generator receives random noise data and produces outputs similar to real data. The generated output data, along with the original dataset, is fed to the discriminator, which distinguishes between real and fake data. The two networks have opposing objectives, but they help each other learn in practice, continuously improving each other's performance. Each of the two networks aims to minimize its own error while maximizing the other's error. John Nash mathematically proved that the optimal solution to these problems occurs when neither agent can further increase its utility. This situation is referred to as Nash equilibrium. If the training data is limited, the GAN cannot... 

Wars are destructive and ruin lives. However, when it comes to defending one’s home country and religion, the brilliant aspects of sacrifice are highlighted. The 1980 war between Iran and Iraq, which lasted eight years and cost more than 200,000 lives, is a prime example of such sacrifices. Religions demand sacrifices and create club goods like altruism, cooperation, and effort, which are crucial on the battlefield. Religious institutions, like the Imamzadehs in Iran, strengthen people’s faith and play a significant role in these sacrifices. About eight thousand Imamzadehs in Iran are tombs of the grandchildren of Prophet Muhammad, who left the Arab land seeking a peaceful life among... 

In this thesis, a laminated composite beam with single delamination under the action of moving force/oscillatory mass has been modeled and analyzed. The beam has been divided into four sub-beams and based on Bernoulli-Euler and also shear deformation theories and by applying the Hamilton’s principle, equations of motion along with boundary conditions and continuity and compatibility conditions are obtained. Primarily, based on the constrained mode model the delaminated layers have been analyzed then by implementing the Lagrange multipliers method, the nature of dynamic contact is incorporated. In the analysis of delaminated beam based on the constrained mode, by applying the mode summation... 

In recent decades, considerable attention has been paid to application of passive energy dissipation systems in design of new buildings as well as in seismic rehabilitation of existing ones. The increased application of these devices in structures will depend on the availability of simplified methods for their analysis and design. In this study, considering high viscously damped single-degree-of-freedom systems, an equivalent linear system with new effective parameters is introduced which has capability to predict maximum displacement and maximum inertia force of the structure simultaneously. Effective mass and effective damping ratio as pair of effective parameters instead of the effective... 

Environmental problems and limitation in fossil fuels have increased the application of renewable energy sources (RES) and distributed generations (DG). Due to the DC nature of most loads and DGs, DC microgrids provide a suitable structure to integrate different kinds of DGs and loads. Undesirable voltage regulation and poor power sharing among the sources in conventional voltage-based control methods are solved by the superimposed droop frequency method. However, the superimposed droop frequency scheme suffers from three major problems which are (i) instability in terms of load variation, (ii) limitation in the system maximum loading which is due to the limitation in the transferred... 

Numerical study of the interaction mechanism of the premixed flame and the acoustic field is performed in this work. The geometry similar to those used in experiments, is a two-dimensional tube in which flame travels form open end towards the closed end. The numerical study is done using PPM method. Results show that the shape and speed of laminar flame is strongly affected by the induced acoustic field. Stronger interaction is observed in the closed-end tube with no slip boundary conditions. The effect of the Lewis number on the interaction mechanism is also investigated. Premixed flame- accelerated flame – interaction of flame and acoustic field  

Translation quality assessment (TQA) as a systematic field of inquiry has been under scholarly investigation over the past decades. In spite of the challenges appeared in the path to success, theoretical and practical developments have already been made in translation studies. One of the unsettled and challenging problems concerning translation assessment, yet, is the subjectivity that is inherent in the process of scoring test-takers’ translation performances. In the absence of any granular objective criteria which includes all the subcomponents of translation as a multi-layer rather than unitary construct, the raters inevitably bring their intuition and will to the act of measurement.... 

Knowing the location and time of oil accidents and trying to track the pollution caused by these accidents is very important for the purpose of monitoring and protecting the environment. The occurrence of large oil spills in the marine environment can have serious environmental, social and economic consequences. In this research, oil spills in the Persian Gulf were first identified using remote sensing method and Sentinel-1 satellite images. The images of this satellite were called for the processes needed to identify oil spills in Google Earth Engine space. After detecting the oil spills, it is necessary to determine the duplicate spills and remove these types of spills, as well as estimate... 

In the present study, performance of a novel fan namely bladeless fan has been evaluated. The aerodynamic and aeroacoustic performances are studied by using 3D simulation of this fan. Mass conservation equation, momentum conservation equations and noise equations of FfowcsWilliams-Hawkings numerically solved to investigate performance of this fan. Firstly, fan cross section profile was designed by Eppler airfoil 473 instead of the prior profile as a modification then effect of different geometrical parameters on the performance is examined. These parameters are height of cross section, angle of output flow with respect to fan axis, thickness of output airflow, hydraulic diameter and aspect... 

Nowadays, despite the special position of power electronic converters in the world, and the fact that they become an integral part of human life, still in the wake of a serious necessity the development process has not stopped and the increasingly fast pace, it opens up new horizons. This important necessity emerges from the environmental concerns regarding consumption of fossil fuels and their limited and imbalanced distribution which can be effectively addressed with the use renewable energy systems. By improving the quality of the semiconductor switches and offering new topologies in different functions as well as using new control methods, scholars try to develop enhanced converters in... 

In this thesis, we focus on some internal organization issues of the supply chain; in particular, we analyze some network design problems which are typical of producer companies. The aim is to optimize the flow of goods through the literature distribution network, from the plants where the goods are produced (supply points) to the demand points, which are essentially distributors such as wholesalers or retailers. The system addresses a class of distribution network design problems, which is characterized by multiple product families, a central manufacturing plant site, multiple central warehouses and distribution center, and retail outlets (customer zones) which demand multiple units of...