Sharif Digital Repository

In this project, modeling and control of grasping phase of flight is investigated inspired by birds’ aerial hunting. For this purpose, grasping mechanism and its challenges in flight is studied. In the following, an explanation about gripper, its design and its performance in flight is given. Both 1-DOF and 2-DOF gripper is modeled. Then, the simulation is evaluated during different test cases. After modeling, optimum trajectory for an air-vehicle in grasping phase is studied and analyzed. When using a 2-DOF gripper instead of a 1-DOF gripper, the vehicle is capable of grasping in different positions and attitudes. Therefore, the results of trajectory generation show more chances of grasping... 

The dipole in the angular distribution of the cosmic microwave background (CMB) is typically attributed to the Doppler effect and our motion relative to the CMB rest frame. It is expected that observations of large-scale structures (LSS) would also exhibit a related kinematic dipole, helping to confirm the kinematic origin of the CMB dipole. However, numerous studies of the LSS dipole have shown significant discrepancies with predictions based on the CMB. In this study, we assume that the CMB dipole is due to our motion relative to the CMB frame, and using radio source data from NVSS, we calculate the dipole induced by local large-scale structures across different redshift ranges.... 

Hydrogen is known to be a renewable and clean source of energy, which produces water vapor and zero carbon dioxide as a result of its combustion. Photoelectrochemical water splitting (PEC) could be a promising approach in order to generate hydrogen by sunlight. Hematite (α-Fe2O3), as the most abundant naturally occurring form of iron oxide with suitable band gap, low cost, high stability and nontoxicity is considered to be an ideal photoanode. However, intrinsic drawbacks of hematite including low electrical conductivity, limited hole diffusion length, and high recombination rate of electron-hole pairs restrict its photoelectrochemical performance efficiency. In the present research,... 

In this thesis a smart anticorrosive pH-responsive coat was developed with layer by layer (LbL) technique in the assembly of SiO2/CTAB/PSS/HMTA/PSS/PEI/PSS. SiO2 nanoparticles were prepared from Matland Company (Iran) with average size of 24 nm. At first, the corrosion inhibition of HMTA for API 5L Grade B steel in 3.5 wt.% NaCl solution was investigated. Tafel polarization technique showed the optimum concentration of HMTA was 0.08 M with 92% corrosion inhibition efficiency as the morphology of coverage and adsorption on the steel surface was confirmed by SEM and EDS. AFM results showed the roughness of the surface decreased from 241 nm to 56 nm that is attributed to HMTA adsorption on the... 

One of the issues that has always been paid attention to financial markets is that the use of mathematical relations and formulas for the better estimation of the forecasts made by the process of indicators that are of great importance in financial markets. In financial markets, algorithms have been developed to help reduce the cost of executing transactions from a variety of factors, in order to impose less costs on traders. In these algorithms, a market order and a limited order are used in such a way that the cost of executing transactions can eventually be minimized. Under a limited order, traders determine how much their stake will be at what price they are willing to trade, but in the... 

Monitoring is of particular importance after impounding and during dam operation. In all large dams, by installation of the required instruments the pore pressure, soil mass pressure and displacement during construction, first impounding and operation are measured, then the performance of dam will be analyzed and evaluated. The aim of this study is to evaluate the performance of the "Gavoshan" dam, which has an important role on agriculture development and drinking water supply at west part of Country. To reach this, the values resulting from instruments have been implemented by FLAC software, using "Back Analysis" method. However, this assessment is complete when "back analysis" method is... 

Simultaneous localization and mapping (SLAM) is the action of detecting robot pose in an unknown environment and building the environment map by use of input data that captured from robot sensors. In visual SLAM, the input data for the robot, is limited to camera sensors. Nowadays, SLAM is one of the main challenges in robotic research.For autonomous action, we need robot pose in the map of the environment. The map production in the indoor environment, there is no GPS data, is one of the research issue in robotic community, in last decade. In this thesis, a new and efficient method is proposed for SLAM at the level of objects. The maps produced by state of the art methods don’t have a... 

When demand for a product is price sensitive, pricing and lot sizing decisions are interdependent. Similarly, when a product is highly perishable, the demand may need to be backlogged to avoid costs due to deterioration, i.e., perishability and backlogging are complementary conditions.In this thesis we stablish two economic production quantity models for deteriorating items under conditions of finite production, exponential decay and partial backordering and lost sale. Two joint pricing inventory control models are developed for the problem by employing different modeling approaches over an infinite planning horizon. In two models, customer is viewed to be impatient and the fraction of the... 

Oil/water separation is an important field, not only for scientific research, but also for environmental, economic, and social issues. On the one hand, oily wastewater, resulting from industries such as steel, aluminum, food, textile, leather, petrochemical and metal finishing, has become the most common pollutant all over the world. On the other hand, frequent oil spill accidents are of great concern since the discharge can lead not only to serious environmental pollution, but also a great loss of energy.
In crude oil removing water is necessary due to reducing corrosion, increasing thermal values of fuels obtained from crude oil, preventing catalists from destruction by water and... 

Breast cancer is the most common type of cancer in women and the second cause of death among them. The chance of successful treatment would be significantly increased if the disease is diagnosed at its early stages. There are numerous methods to diagnose breast cancer. One of the most important methods is positron emission mammography (PEM).The main aim of this study is to investigate the feasibility of improving PEM images by considering the time of flight corrections and the penetration depth of the rays in the crystals.In this study, a commercial PEM system, Naviscan PEM, is simulated using the GATE software. In the first phase of the study, two opposing planar detectors are used to study... 

Direct speech-to-speech translation, in which all compontents are trained jointly, is advantageous over cascaded approaches, because this method employs a simple yet effective pipeline to produce the outputs with a little inference time. Direct speech-to-speech translation models suffer from data scarcity issue, because they need parallel speech data in source and target languages. In this thesis, we present a novel direct speech-to-speech translation model to translate Persian speech to English, which is based on discrete speech units and uses a conformer-based encoder which is pretrained and a transformer-based causal decoder which uses relative position multi-head attention to do the task... 

Today, with the widespread use of decentralized systems, many people interact with each other and this interaction can endanger their safety. Therefore, the strategy should be to keep people safe. Interaction with a trusted and highly recommended people is essential and this is considered the first step toward security. Privacy preserving is critical in Successful operation of reputation system, in other words, the trust value should not be available. This method can prevent from positive and negative feedback of people because one person (may be due to personal animosity or to lack of commitment or person discomfort) can manipulate the trust value. For this reason, the trust value should be...