Sharif Digital Repository

In this study, TiO2-SiO2 nanocomposite films with different amount of SiO2 were prepared by sol-gel process and were coated onto stainless steel 316L. The effect of addition of various amounts of SiO2 in the precursor solution on the structure, morphology, photocatalysis, photo-generated hydrophilicity, self-cleaning property and mechanical properties of TiO2 thin films and corrosion behavior of AISI 316L stainless steel substrate, was investigated. For this purpose, X-ray diffraction, Fourier transform infrared spectroscopy, water contact angle measurements, UV spectroscopy, field-emission scanning electron microscopy, atomic force microscopy, depth-sensing indentation technique supporting... 

In this work, a non-isothermal model of natural gas in pipelines including mass, momentum and energy balance equations are used as model equations for modeling and state estimation in gas pipeline systems. An algorithm is proposed to handle the discontinuities that appear in the dynamic model of a GTN. The states of GTN are estimated using the continuous/discrete form of the extended Kalman filter for two benchmarks and some heuristic rules for sensor placement in a GTN are concluded. Also, a framework for distributed and decentralized state estimation in high-pressure and long-distance gas transmission networks (GTNs) is proposed. Some heuristic rules are suggested for system decomposition... 

Redundant number systems provide for carry-free arithmetic, where the result of arithmetic operations is achieved, in redundant format, without the need for latent carry propagation. However conversion of the result to a conventional nonredundant representation, always, requires carry propagation. Therefore, efficient use of redundant number systems is feasible when a series of arithmetic operations is to be performed before the need arises to obtain the result in a nonredundant representation. Redundant number systems have been used in several special purpose integrated designs (e.g., DSP applications) and also as intermediate number representation in complex arithmetic operations... 

Industrial water systems often allow efficient water uses via water reuse and/or recirculation. The design of the network layout connecting water-using processes is a complex problem which involves several criteria to optimize. The general problem can be formulated as a non-convex nonlinear program (NLP), but due to the presence of bilinear terms, it may be difficult for local optimization solvers to attain global optimal solutions. To overcome this difficulty, this paper presents a hybrid approach combining the global optimization power of evolutionary algorithms and speed and accuracy of mathematical programming technics.By this strategy, local solutions can be avoided and the... 

In this study nano zeolite was hydrothermally synthesized in order to remove ethyl and methyl mercaptans from propane and butane stream. Fifteen experimental runs were conducted using D-Optimal method experimental design to synthesize NaY, NaX and NaA zeolites. The products were characterized by measuring the morphology, particle and crystal size, surface area, adsorption isotherm, pore size, and pore volume of the products by XRD, FE-SEM, TEM and BET analyses. The pore size for NaA type zeolites is about 4 Angstrom whereas the molecular size for ethyl mercaptan and methyl mercaptan is between 4 and 5 Angtrom, Therefore, NaA zeolite is inappropriate for removing ethyl and methyl mercaptans... 

Today, environmental pollution has become a global issue, affecting both land and air, and oceans are no exception. Marine environments increasingly suffer from various forms of chemical and solid pollution, with floating solid waste among the most prevalent forms. Beaches and ports are the main sources of this waste, a significant portion of which is plastic. With the rapid growth in plastic production, concerns about floating waste have intensified globally. Consequently, numerous cultural initiatives and technological solutions have been proposed to combat this pollution. Waste collection systems are among the most effective approaches, and various types have been implemented. Since Iran... 

Because of the Complexity in Calculating the Probability of Failure of the System, This Computation is Done by the Software Have Been Developed for this Purpose. Of Course, When We Use Them, We See That Each of Them Have Their Advantages and Disadvantages. One of the disadvantages that have been tried to be resolved over time, the type of programming and algorithm for calculation of it is the fault tree Because new techniques like modularization which have been designed in recent years, a significant improvement in accuracy and speed performance computing applications that use this method have been obtained.In This Thesis Has Developed Software That is Able to Calculate the Probability of... 

Concepts and ideas of a society, formed by its discourse and ideology, are mainly manifested through language. Therefore, language has always been the subject of studies and research of many scholars such as linguists. As the languages of different countries are different, in order to transfer the thoughts of a writer, a deep examination of the source text as well as the translation of the work itself seems to be of much importance. Since translation is not an independent phenomenon and depends on the interpreter's perception, it is in relation with ideological concepts and power like the work itself. In order to be able to examine the structural effects of a work on the foundation of the... 

Synthesis gas to light olefin reactions especially propylene production is one of the important path for clean fuel production in gas conversion processes. The object of this study is to define true kinetic model of process first step (e.g. Synthesis gas to light Olefins). For that, kinetic model for Co/Mn/TiO2 catalyst, which has the best conversion and selectivity for propylene, has been developed. Kinetic reaction parameters were measured by kinetic modeling in (220-300)0C temperature , (1-5)bar pressure , H2/CO=(1:3) and (450-600)hr-1 space velocity .After studying with significant models ,the best fitting can obtained with "KPCO P 1/2H2/(1+aPco+bPH2 1/2)2"equation. Later to... 

Because of higher hydrogen demand in recent years, study of hydrogen separation from gas mixtures is highly regarded. Because of some parameters such as high surface to volume ratio and ability to withstanding high pressure, polymeric hollow fiber membranes have a good potential of hydrogen recovery. So in this study, fabrication of single-layer and dual-layer hollow fiber membranes have been investigated. Selective polymer that used in both single and dual layer membranes is polyethersulfone. Membranes were fabricated by dry-wet phase inversion method and effects of extrusion rates and their ratio, composition and temperature of polymer solution, composition of bore fluid, coating and air...