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Modeling and Analysis of Optimal Control and Condition Monitoring of Fuel Cell System Based on Performance History
, M.Sc. Thesis Sharif University of Technology ; Roshandel, Ramin (Supervisor)
Abstract
The short life of Polymer Electrolyte Membrane (PEM) fuel cells is one of the critical criteria to their commercialization. A longer operation life time should be achieved to reach high reliability, low $/kWh cost and to use fuel cells as economical alternative energy systems.Therefore,diagnosing degradation mechanisms and the causes of power loss in fuel cell life time is of great importance. Operating conditions affect output power density and performance degradation. To achieve maximum power generation through fuel cell life time, a model is needed which is able to estimate power density and performance degradation simultaneously regarding to operating conditions. In present work, a...
Water-Based Drilling Fluid Design Considering Thermal Stability by Nano Material and Evaluation Filtration Loss, and Shale Swelling Criteria for Usage in very Deep Drilling
, M.Sc. Thesis Sharif University of Technology ; Goodarznia, Iraj (Supervisor) ; Ramazani, Ahmad (Co-Advisor)
Abstract
The aim of this project is designing Suitable drilling fluid applicable in deep drilling. This aim will be reached by adding a temperature-resistant polymers or nanomaterials in water-based drilling fluid, Rheological properties of drilling fluid checked. Stability of rheological properties of drilling fluids not constant in HT state. Chain of cause and effect will happen, While the temperature increases, the viscosity and yield point of the fluids decreases. cuttings transportation and removal efficiency will be decreased due to reduction in yield point and viscosity. Evaluation of The effect of these cases conclude that these effects will also impact on filtration loss. The reason is that...
Stability investigation of colloidal FePt nanoparticle systems by spectrophotometer analysis
, Article Chinese Physics Letters ; Volume 26, Issue 2 , 2009 ; 0256307X (ISSN) ; Sebt, A ; Parhizgar, S ; Aberomand, P ; Akhavan, M ; Sharif University of Technology
2009
Abstract
FePt magnetic nanoparticle systems are an excellent candidate for ultrahigh-density magnetic recording. Monodisperse FePt nanoparticles are synthesized by superhydride reduction of FeCl24H2O and Pt(acac)2 at 263° C under N2 atmosphere. Transmission electron microscopy (TEM) images show monosize FePt nanoparticles with diameter of 4nm and a standard deviation of about 10%. The average distance between monodispesre particles is nearly 3 nm, and oleic acid and oleylamine surround the nanoparticles as surfactants. Stability investigation of nanoparticle colloidal solution is done via spectrophotometery analysis. The results for FePt nanoparticles dispersed in hexane indicate that adding...
The effect of NaCl prepared by ultra-sonic vibration on Sintering of annealed FePt nanoparticles
, Article Journal of Physics: Conference Series ; Volume 153 , 2009 ; 17426588 (ISSN) ; Sebt, S. A ; Parhizgar, S. S ; Aberomand, P ; Akhavan, M ; Sharif University of Technology
2009
Abstract
FePt nanoparticles were synthesis via high-temperature solution phase. Monodispersed 3.5 nm FePt nanoparticles were first obtained by reduction of FeCl2.4H2O and Pt(acac)2. These preformed FePt nanoparticles were then combined with NaCl to prevent from sintering after annealing. The 1 micron salt particles were fabricated by ultra-sonic vibration method and used as the separating media. Annealing studies show that these salt-matrix FePt nanoparticles are stable after annealing at 700 °C for 4 h. The annealed FePt particles diameter increases from 4 to 25 nm as observed by TEM. The magnetic properties are largely affected by annealing temperature. The role of these salt particles on sintering...