Sharif Digital Repository

Ni-P alloy coatings were electrodeposited using pulse current in a watt type bath in various conditions. The influences of different parameters were investigated and optimized for the highest amount of coating hardness using the Design Of Experiment (DOE) method. The optimized deposition parameters were current density 23.7 A/dm2, duty cycle 75%, frequency equal to 188 Hz, temperature equal to 70ºC and 17.5 gr/l of H3PO3. The DOE prediction of hardness for the optimized coatings was between 700 and 750 the achieved micro-hardness was about 725.8 HV. It was obtained that an increase of the current density will improve micro-hardness, decreases P content and increase deposition rate. Also, the... 

The gas separation properties of polycarbonate (PC) membranes were investigated in this study. These membranes were prepared via dry and dry-wet phase inversion technique. Pure O2, N2, and CO2 gases were permeated through prepared membranes. The effects of membrane preparation conditions, including solvent type, non-solvent type, non-solvent/solvent volumetric ratio, polymer weight fraction, and drying temperature on the gas separation properties of dry PC membranes were investigated using Taguchi experimental design. Taguchi analysis show that polymer weight fraction offers the most important effect on the separation characteristics of the dry PC membranes. To get the highest... 

In recent years in assembly line balancing area many researchers have focused on identifying and modeling real world situations in assembly lines in order to obtain more suitable model. As a result many generalized models have been developed in assembly line balancing area. However, designing efficient algorithms to solve these generalized problems has just begun. In this study it is aimed to design efficient algorithms to solve one of these generalized problems. Specificcally two hybrid genetic algorithms (GA) are proposed to solve assembly line balancing problem with sequence dependent setup times. Scheduling of tasks in the stations has been less considered in the literature of assembly... 

Nowadays, the attempts to reduce fuel consumption, greenhouse gas emissions and atmospheric pollutants, and economic savings, besides alignment with new rules, have been become the top priorities in the marines industry. In order to satisfy these goals, many efforts have been undertaken, including the vessel's trim and draft optimization which has done both experimentally and numerically and also thrust system simulation, to set a logical link between the effects of trim and draft of the ship and the calculated value of the required thrust from simulation to be able to optimize the fuel consumption. In this method, the ship is considered at the specific draft and the trim in bow and stern... 

Nowadays, apatite mineral is one of the most sought for the recovery of rare earth elements. This mineral is also the main source of phosphoric acid production. To achieve this end, apatite has to react with sulfuric acid to give phosphoric acid. This process is called the wet process. During the wet process, more rare elements enter the remaining solids called phosphogypsum (PG). For the dissolution of rare elements, PG, which is the same as chalk, can be leach with an acidic solution. In this project, the phosphate concentrate from Chadormalu iron ore waste after characteristics diagnosis is digested in concentrated sulfuric acid at temperatures below 100 ° C, and then hydration is... 

This study presents a novel perspective on pressure-transient analysis (PTA) of downhole-pressure and flow-rate data by use of system-identification (SI) techniques as widely used in advanced process engineering. Key features of the algorithm are that it considers the classic PTA process from a system-theoretical perspective; derives the causal structure of the flow dynamics; proposes a method to deal with continuously varying pressure and flow-rate signals contaminated with correlated noise, which estimates physical reservoir parameters through a systematic matching procedure in the frequency domain; and can cope with arbitrary (i.e., not necessarily piecewise constant) flow-rate signals.... 

This PhD dissertation presents the chemometric techniques as a tool to obtain maximum information from the chemical and biological systems. In this regards, two objectives have been followed. The first objective was to apply the design of experiment methods for approaching the most reliable data. In this section, the main concepts and applications of experimental design approaches to optimize the common analytical chemistry techniques are reviewed. The critical steps and tools for screening including Plackett-Burman, full factorial- and fractional factorial designs and response surface methodology such as central composite, Box-Behnken and Doehlert designs are discussed. Descriptions of... 

Digital computer simulation and employing the concepts of the experimental design, and other analytical tools for evaluating its output have attracted many of the scientists and researchers interests in the recent decades. The importance of this topic has been increasing and more related analytical tools have been introduced to the scientific literature. One of the powerful tools for simplifying accelerating the optimization process of simulation results, are the use of the metamodels. Use of these powerful tools becomes more eminent when the simulation runs are expensive. By the use of the metamodels the needs of conducting sampling for obtaining some more new points from direct simulating... 

In this thesis, in the first part, a promising electrochemical sensor was developed based on a layer by layer process by electropolymerization of pyrrole in the presence of new coccine (NC) as dopant anion on the surface of the CNTs pre-coated glassy carbon electrode (GCE). The modified electrode was used as a new and sensitive electrochemical sensor for voltammetric determination of sumatriptan (SUM). The results showed a remarkable increase in the anodic peak current of SUM in comparison to the bare GCE. In the second part, the electropolymerization of pyrrole was performed in the presence of Nitrazine Yellow (NY) as a dopant anion on the surface of the electrode precoated with CNTs. The...