Sharif Digital Repository

The use of superhydrophobic surfaces is one the most promising methods for reducing the friction and increasing the flow rate in fluid transfer systems. Since in such systems the surface structure plays a key role, in the first part of this study, the performance of the hierarchical nanostructures is explored. These nanostructures are inspired by the superhydrophobic surface of the lotus leaf. The flow is considered between two walls with hierarchical nanostructures and simulate the system via the molecular dynamics (MD) method. The size of the nanostructures and the distance between them have been studied to find whether a design with maximum flow rate exists. The nanostructures have two... 

Sign language is the main medium of communication for mute and deaf people. Unfortunately most hearing people do not understand this language. This fact causes communication difficulties for hearing impaired people and negatively affects their social life. This problem motivates researchers to develop speaking aids and helps deaf people to communicate with hearing people. Sign language includes concurrent combination of hand shapes, orientation and movements of the hands, arms or body, and facial expressions which make the character and word recognition a challenging task. Generally there are two fields of study in sign language recognition based on measuring devices: 1- camera based 2-... 

Insulin pump treatment is considered the most physiological way to imitate the healthy body's insulin profile in patients with diabetes. They provide a precisely controlled rate of insulin delivery to diabetic patients who would normally need multiple daily injections to regulate blood glucose levels. The firmware allows numerous modifications to the bolus dose and basal rate to enable patients to manage insulin levels in response to events such as eating, sleeping, and exercise.
In this Study, we have first investigated different models of insulin pumps on the market and chose the Spring ZoneTM insulin pump model for our study due to its innovative technology. This pump employs a... 

The current study was attributed to uranium uptake by Varion-AP resin from Saghand, Iran Uranium Mine, ore leach liquor. A suitable high-efficiency system was designed for continuous ion exchange at the bench scale and the uranium uptake parameters were optimized. In this system, 1 reactors was used with a volume of 3 liters in stage with the same height difference. A leach liquor containing uranium with a concentration of between 200 and 300 mg/l was flowed from the feed storage by gravity between reactor 1 to 10 at a flow rate of 30 lit/h and Varion-AP resin was transferred in counter-current flow from stage 10 to 1 by a pneumatic pump. The output of each reactor had a screener that... 

During various stages of processing uranium in Isfahan’s UCF plant, liquid waste containing uranium compounds, is directed to evaporation lagoons. Gradually, a considerable amount of precipitation will form at the bottom of the lagoons. Since the concentration of uranium in evaporation ponds is relatively high, it seems that in addition to environmental issues, recycling uranium from existing pools is also economical. Uranium may be recovered from an aqueous solution by precipitation, solvent extraction and ion exchange. The solvent extraction is the best option for our purpose because of simple operation without increased consumption of heat or chemicals. It is also preferable when large... 

Application of composite patches in repair of damaged/aged aircraft structures is one of the most popular repairing methods in aerospace engineering and because of its advantages the use of this type of repair is increasing today. However, to use these patches in life extension of aged aircraft, the added weight to the structure should be strictly controlled. This could be best done if achieving the optimum and smart design by using optimization and structural health monitoring methods. These two concept about pre-designed of composite patch repair are investigated in this thesis. The simulation by Abaqus software and experimental results and tests will be used for this purpose. In first... 

In this work, inertial guidance and control of an axisymmetric flying vehicle with a spinning part is performed based on dynamic modeling and seven degree of freedom simulation. Flying vehicle is composed of front and aft bodies and these bodies are connected to each other via a hydrodynamic bearing. Front body is roll isolated from the aft body and includes all necessary guidance and control equipments such as sensors, canard set and so on. The control fins, located on the nose, is used to control the roll angle of the nose and to execute the lateral acceleration commands. Also, the aft body is freely rolling and includes the stabilizing fins. In this project, the translational and... 

In this thesis an algorithm has been implemented for automatic landing of a quadrotor under the ground effect. In this regard the six degrees of freedom equations of motion using the Newton-Euler method has been designed. Then, the ground effect has been modeled by inspiring from the similar available models in the literature. The proposed models and proportional-integral-derivative attitude control loops have been simulated in MATLAB/Simulink environment. Also, two control strategies, a classical proportional-integral-derivative controller and a sliding mode controller have been utilized for height control loop.Since sliding mode controller requires all state variables to generate control... 

A cooperative aerial system to defense a Ground Station (GS), against an Incoming aerial Targets (IT) is presented. GS is surrounded by given terrains and a group of homogenous Unmanned Aerial Vehicles (UAVs) are employed using a novel online guidance algorithm in a decentralized manner. The proposed algorithm includes loiter, midcourse and terminal phases. During loiter; UAVs follow an optimal circular path. IT is supposed to approach GS along an optimal low altitude trajectory with respect to the terrains. UAVs are informed the initial position and velocity of IT and they are unaware of IT trajectory. Each UAV decides on whether to engage with IT or not, and shares its decision with other... 

Airport saturation is one of the important issues which have always been of the specialists’ concern. One of the major applications of this subject is at the airport approach problems. While using current conventional approach procedures have many disadvantages regarding high fuel consumption and subsequent much environmental and noise pollution, the CDA concept which is one of the modern topics introduced in consequence of free flight theory, has less such disadvantages compared to conventional approach. Subject of this study is to investigate whether Procedural approach or CDA saturates an aiport sooner if the traffic flow increases. In this dissertation, using BADA database, CDA... 

In this thesis, possibility and advanteges of dynamic descent route assignment during busy traffics and implementing changes within navigation infrastructure is examined. Facilitating Continuous Descent Approaches (CDA) as optimum descent paths is the main goal of this research. One advantage of this project with respect to previous works in this field is dynamic CDA routing between cruise altitude and Terminal Radar Approach Control (TRACON) entry to meet the demand of traffic during peak hours.The other superiority is proposition of LASER technology as an alternative/backup NAVAID system in order to facilitate the latter.Terminal area of Hartsfield-Jackson international airport with real... 

In this thesis, optimal station keeping of spacecraft on the closed-orbits near the Earth-Moon Lagrange points has been investigated. Lagrange points L1 and L2 are unstable equilibrium points of the circular restricted three-body problem (CRTBP), and periodic orbits near them are the destination of modern missions. However, perturbations resulting from the gravitational forces of the Sun and the planets and the eccentricity of the orbit of the Moon around the Earth make the Lagrange point unstable, even L4 and L5, which are stable in CRTBP. The most suitable choice for spacecraft mission near the collinear Lagrange points is the Halo and other closed-orbits around them, which need... 

Super app is known as a software that provides the users with a variety of services in the form of a whole platform. Only a few studies have been done into the field of super apps. Although previous studies have made observations regarding the effect of motives on the customers` satisfaction, the effect of use intention on the customers` engagement has been negligibly looked into. The present research focuses on the effect of different use intentions (Hedonic, Utilitarian and social benefits) on the super app users` purpose by taking the customers` satisfaction and engagement into account. This study is different from the previous ones as the motives` effect has not been examined... 

Recent advances in deep neural networks have shown significant potential; however, they still face challenges when it comes to non-stationary environments. Continual learning is related to deep neural networks with limited capacity that should perform well on a sequence of tasks. On the other hand, studies have shown that neural networks are sensitive to covariate shifts. But in many cases, the distribution of data varies with time. Domain Adaptation tries to improve the performance of a model on an unlabeled target domain by using the knowledge of other related labeled data coming from a different distribution. Many studies on domain adaptation have optimistic assumptions that are not... 

The existing continual learning methods are mainly focused on fully-supervised scenarios and are still not able to take advantage of unlabeled data available in the environment. Some recent works tried to investigate semi-supervised continual learning (SSCL) settings in which the unlabeled data are available, but it is only from the same distribution as the labeled data. This assumption is still not general enough for real-world applications and restricts the utilization of unsupervised data. In this work, we introduce Open-Set Semi-Supervised Continual Learning (OSSCL), a more realistic semi-supervised continual learning setting in which out-of-distribution (OoD) unlabeled samples in the... 

Despite the remarkable success of deep learning algorithms in recent years, it still has a long way to reach the status of human natural intelligence and to acquire the expected self-autonomy. As a result, many researchers in this field have focused on the development of these algorithms while taking inspiration from human cognitive behaviors. One of the disadvantages of current algorithms is the lack of their ability to learn in a continual manner while deployed in the environment. More precisely, deep learning models are not able to gradually gather knowledge from the environment and if they are in a situation of limited access to data, they will suffer from catastrophic forgetting; a... 

Quality Assurance is one of the crucial steps in software production and should be repeated. These days, software companies are using continuous integration (CI) pipelines for building software and controlling software quality. Regression test, is a test which is performed after each change in software, to assess the quality of the software system and its ability to meet functional and non-functional needs. Each execution of this test, leads to infrastructure costs and a waste of time for the software development team. The reason is that the development team has to wait until the test is completed to ensure that the changes are correct. To reduce this cost, methods such as prioritizing and... 

Stock price patterns are a technical analysis approach to forecast future trends with tremendous practical benefits. However, the current algorithms solely rely on machine learning techniques and deep neural networks which could be a problem in countries where data sets such as these are not available. We propose an algorithm based on geometry and mathematics for this problem, leading to an O(n^3logn + n^2k) complexity, where k is the number of triangular patterns  

Continuous-time Stochastic Game (CTSG) can be seen as a proper model to analyze probabilistic, nondeterministic, and competitive behaviors as found in Stochastic Multi-Player Game (SMG). The difference is that in an SMG, the system under design is analyzed in the discrete-time setting. In comparison, in a CTSG, the system transitions occur in the continuous-time setting with exponentially distributed delays. This thesis focuses on the model checking of CTSGs with bounded transition rates. We present a uniformization-based algorithm to approximate the optimal time-bounded reachability probabilities with an arbitrary error bound. To illustrate the strength points of our algorithm, we compare... 

This thesis focuses on the problem of large vocabulary continuous speech recognition (LVCSR).Numerous research results in recent years proved effectiveness of deep neural networks (DNN) for LVCSR. As a result, many methods were proposed to incorporate DNNs in LVCSR. From one perspective we can look at these methods from the viewpoint of objective functions used for training DNNs. A frame-level objective function is one that is defined on frames locally, whereas a sequence-level objective function is defined on whole sequences. Since speech recognition is essentially a sequentional problem, here we focus on designing and imroving sequencelevel objective functions for DNNs. The main proposed...