Sharif Digital Repository

Wheeled mobile robots form a subcategory of mobile robots and are usually accompanied with geometric constraints on their velocities. These constraints do not allow the robots to move in any path that only does not collide with obstacles, in order to move from one point to another. On the other hand, the nonlinear nature of these systems make their control difficult. A general approach in motion planning and control for mobile robots is using standard forms equivalent to their state equations; Usually, solving motion planning and control problems for these forms is easier than that of the original system. Also,the mentioned problems are more prospective to have a systematic solution for... 

In this thesis, we first explain how we can construct three-point amplitudes for both massive and massless particles by solely knowing the Lorentz invariance and spin or helicity of particles. Then, using BCFW recursion relation, we determine the tree-level amplitudes. To calculate the loop amplitude, we apply the unitarity of Smatrix.The unitarity relates the tree-level amplitudes to loop level. Finally, I discuss some exciting topics in this field, including color-kinematics duality, some relevant applications of contemporary S-matrix theory in effective field theories  

Due to the destructive effects of sudden and adverse changes in acceleration on the human body, drivability control has a particular importance in the automotive industry. Driveability control makes car occupants feel a smooth and comfortable driving, and it will play a vital role in the competition between companies to provide a good product with optimal driving quality.In this project, the aim is to achieve a smooth acceleration curve in a vehicle equipped with a manual transmissions. The meaning of smooth acceleration curve is to reduce jerk and shock caused by inappropriate driver behaviors and to control the car's torque and acceleration to a desirable level. In this project, first, the... 

Recent studies suggest that the selectivity filter may exhibit quantum coherence, which could play a role in explaining the processes of ion selection and conduction. As the ion channel system interacts with its environment, it undergoes a decoherence process. In this thesis, the relationship between jump rates and coherence preservation in ion channels is examined initially. To this end, using the Lindblad master equation to describe a three-level system, results are analyzed in different quantum regimes. To directly study coherence in the system, distillable coherence was used as a coherence measure, and the second-order coherence function was calculated. As expected, distillable coherence... 

Control Charts are the most popular monitoring tools for profiles. The time that a control chart gives an out-of-control signal is not the real time of change. The actual time of change is called the change point. This study suggests two new algorithms to find the change (shift) in parameters of nonlinear profiles. First, using ordinary Kriging method, new points are estimated. Then, with the help of Bernoulli hypothesis test, the probability of detecting the change for new points is tested. Nonlinear profiles in this study follow the exponential family of distributions; in particular, Exponential, Poison and Gaussian distribution structures are used as nonlinear profiles. The proposed... 

Huge availability of data in last decade has raised the opportunity to use data for decision making. The idea of using existing data to achieve more coherent reality solution has led to a branch of optimization called data-driven optimization. Presence of uncertain variables makes it crucial to design robust optimization methods for this area. On the other hand, in many real-world problems, the closed-form of the objective function is not available and a meta-model based framework is necessary. Motivated by this, we are using a Gaussian process in a Bayesian optimization framework to design a method that is consistent with the data in predefined confidence level. The goodness of the... 

Skin, as the largest organ of the body and the first protector against external injuries, plays an important role in maintaining human health. Therefore, providing a method for complete treatment of skin lesions is very important. In the last century, tissue engineering approaches, with the introduction of skin scaffolds, have been instrumental in the process of skin tissue regeneration and treatment. The aim of the present study is to construct an optimal bilayer scaffold to mimic the two outer layer of the skin (epidermis and dermis). Besides, the effects of placenta extract on acceleration of wound healing was investigated by an in-vivo test. both layer of scaffold are porous hydrogels,... 

Supported Ionic Liquid Membranes (SILMs) are fabricated by saturating the pores of a porous support with ionic liquids. To assess the performance of SILMS, it is necessary to obtain data about the properties of ionic liquids such as diffusivity, solubility, and etc. To accomplish this task, in this project the permeability and diffusivity of CO2 and CH4 through three immidazolium-based ionic liquids: [bmim][PF6], [hmim][Tf2N], and "1-methyl-3-(3- tri methoxi silil propyl) imidazolium bis (tri fluoro methyl solphonyl)" , in the temperature range between 27-45 ℃ and pressures within 10-50 kPa, are measured. It is shown in data validation section that the results of this study are in good... 

Reduction in the oil reserves level and the increasing of fossil fuel prices and GHG has led to growing value of attention to biodiesel. Reserves of fossil fuels are running out and should have proper alternative for them. Environmental benign and renewable properties of biodiesel make it consider suitable candidate to replace fossil fuels.
In this study, continuous production of biodiesel and optimization of important and influential parameters have been investigated. The method is concluded of trans esterification of soya oil with methanol as feed in presence of homogeneous catalyst of NaOH. The reactor was simple with high efficiency and low operational and investment cost. The... 

Nowadays, by distributed software development growth based on pull-requests, it is possible to review code changes before integrating into the master program by a third-party, informally and tool-based which is called Modern Code Review (MCR). Effectively performing MCR can facilitate the software evolution phase through reducing post-release defects. In MCR, after sending the pull request, the developer invites appropriate reviewers to inspect his code. Due to the high volume of requests and potential reviewers in many projects, selecting the appropriate reviewer is difficult and time consuming. Previously, a variety of recommender systems have been proposed that use methods based on...