Sharif Digital Repository

In this project, a ceramic biocompatible coating was applied on Titanium which is included Hydroxyapatite by AC Plasma Electrolyte Oxidation method. First, coating was performed in 5 different solutions and various duration in 500mA/Cm2 as a current density. Then, by microscopic and macroscopic images and size of porosity and also thickness of coat, 3 solutions were chosen for adding nanoparticles: Solution 1 which includes NaH2PO4 and Ca(CH3COO)2 , Solution 3 which includes Ca(CH3COO)2 and Na-Beta G and Solution 4 which includes Ca(H2PO4)2, HMP, NA2(EDTA) and Ca(CH3COO)2 . Also the time 10 minutes was chose as a appropriate time. The average of the porosities size in solution 1 was about... 

Reinforcement learning is a field of machine learning which is more similar to human training procedures.It uses reward signals to train an agent designed to act in that environment. Deep neural networks enhance the agent’s ability to determine and act better in its complex environment. Most previous works have addressed model-free agents, which ignore modeling details of the environment that in turn can be used to achieve better results. On the other hand, humans utilize a model-based approach in their decision-making process. They use their knowledge to predict the future and choose the action that leads them to a better state. To combine the benefits of model-based and model-free designs,... 

In this thesis, equations related to large deformation of a polymer were derived by considering viscoelastic effects. To express type of material behavior which includes elastoplastic and viscoelastic property at the same time, two-layer viscoplastic model was used. An axisymmetric model was used for modeling problem in finite element software. By derivation of parameters related to two layer model and entering them in finite element software and also entering other properties required to model the forming process, modeling was performed by special profile connecting input and output sections. Due to favorable properties of spline functions, profiles used in die geometry, were selected from... 

Stop-skipping and timetable synchronization in a transit network for subway operation are two effective strategies to reduce passengers' total travel time.Most of the current research on the topic does not consider stop-skipping strategy and timetable synchronization simultaneously. This paper proposes a mixed-integer programming model based on passenger smart-card data concerning the trains' capacity to minimize passengers' total waiting time and in-vehicle time and maximize the number of passengers who successfully reach their destination. Since increasing the number of trains, stations, or the study horizon, exponentially increase the size of the problem, seeking practical methods to... 

Land use and transportation are interrelated, and as a result in cities’ development plans, there is a need for a model that can consider both of them simultaneously. The model presented in this study is bi-level. The upper level designs the zonal population and employment, and transportation network link capacities. Its objective is to minimize the total cost of residence, receiving goods and services, and transportation. The lower level consists of two inter-related problems. One of these problems determines the allocation of population and employment and the other obtains link flows by a joint bi-modal mode choice assignment model. This study aims to develop a meta-heuristic algorithm to...