Sharif Digital Repository

During this research, ceramic coatings on titanium substrate were prepared by plasma electrolytic oxidation process at a constant current density. Effect of different parameters such as frequency, current density, additives and time on the characteristics of the coated samples was studied. Composition, structure and elemental distribution of the coatings were studied by XRD, SEM and wave-length dispersive spectroscopy (WDS), respectively. Various tests were carried out to calculate the amount of coatings porosity. Pin-On-Disk method was used to evaluate erosion resistance of coatings. Corrosion and erosion-corrosion behaviors of the coatings were studied in 3.5wt% sodium chloride aqueous... 

One of the most essential part of power system are transmission lines. Transmission of power from production centers to consumption centers is duty of these lines. Any disturbance in this duty make great losses to producers and consumers. One of the most disturbance in transmission lines are short circuits that occurred because of various causes. Most faults on transmission lines occurred in stormy weather that make more troubles for fault search. So we need a tool that can find location of fault precisely and quickly. This tool named fault locator. There are many algorithms for fault location and detection on power system transmission lines. These algorithms usually are dependent on very... 

Fast and accurate fault diagnosis has a significant role in the power system operation. For a power system to come back to the normal state, the precise fault diagnosis is necessary. The current practice in power system fault diagnosis needs operators in the control center to use data of PR and CB in order to infer the faulted section based on their experiences. Expert systems and artificial intelligence have been suggested as alternatives to the human expert experience and inference. Other model- and optimization-based methods have also been reported for fault diagnosis, provided that similar data is available from the SCADA system.Nevertheless, in large disturbances resulting in partial or... 

This work attempt to analyze the impact of changes in nurse scheduling on quality of services at emergency department of Emam Khomeini Hospital Complex. In nurse scheduling some constraints such as maximum working hours per week and unacceptable working sequences must be considered. A simulation model is developed to cover the complete flow for the patient through the emergency department. Emergency department of Emam Khomeini is simulated in order to obtain the patient average waiting time for each nurse roster. Then a genetic algorithm is integrated with the simulation model. In each iteration genetic algorithm produces many nurse rosters . For each roster the patient average waiting time... 

Today, supercapacitors are an inseparable component of electronic devices such as hybrid cars, telecommunication equipment, and personal electronic devices, and this device is also used to store clean energy. In this research, polyacrylic acid hydrogel was first synthesized to be used as a supercapacitor electrode and polyaniline was used as an electrically conductive polymer in its structure to improve the electrical properties of this hydrogel. To achieve this structure, the previously synthesized polyacrylic acid hydrogel was immersed in a solution of aniline monomer and other components necessary for the aniline polymerization reaction, and after the soaking process was completed, the... 

Due to immense increase in availability of text data, interest in using machine learning models to solve problems previously impossibly costly has increased significantly. The first step is to represent natural language in a form that is easy for the machine learning algorithms to work on. Recent advances in learned representation of text data using simple neural networks(e.g. word2vec and doc2vec) helped increase performance of natural language processing on downstream tasks. Here we show that methods like doc2vec that were examined mostly in the English language can be used on Persian(Farsi) with little modification. To Demonstrate this, we use text classification tasks, and train... 

The results of a theoretical and experimental study of a resonant interaction between a surface wave and two internal waves are presented. It is shown that the motion of a surface wave in a horizontally infinite two-layer fluid can lead to generation of two oblique internal waves. The internal waves have short wave length compared to the surface wave and have nearly opposite propagation directions. The frequencies of the internal waves are approximately half of the frequency of the surface wave.
In present thesis, Higher-order effects in sub-harmonic resonant interaction of a surface wave with a pair of interfacial waves in a two-layer fluid are studied theoretically and experimentally.... 

In this thesis, we intend to propose low cost SED-tolerant techniques for different compo­ nents of embedded processors core including data path components such as register file and ALU as well as control path components such as control unit. Since the reliability es­ timation is the essential step in design of a fault-tolerant system, we propose fast and accu­ rate analytical soft error rate (SER) estimation techniques in Section 4. The proposed techniques have the ability to measure: 1) the SER of a design; 2) the SER of each indi­ vidual gate and FF, and 3) the SER of a specific path in the design. Using such infor­ mation, designers can selectively protect the vulnerable parts...