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Application of Rosin-Rammler model for analysis of CSD in sugar crystallization
, Article Crystal Research and Technology ; Volume 50, Issue 11 , 2015 , Pages 873-878 ; 02321300 (ISSN) ; Alamolhoda, A. A ; Matloubi Moghaddam, F ; Nayeri, S ; Sharif University of Technology
Wiley-VCH Verlag
2015
Abstract
Crystal-size distribution (CSD) is one of the most important parameters in sugar production. The objective is to grow crystals of uniform sizes or narrow CSD. CSD appears to be determined by the growth-rate history of the crystals and the relative supersaturation (SS) of the solution from which crystals growth takes place. Three methods for preparation of nucleation seeds were described and used for industrial crystallization of raw and white sugars; these are wet milling filtered sugar (ML), agitating saturated solution (AS) and powdered sugars (PD). Rosin-Rammler (RR) and mathematical models were adopted to investigate CSD and the uniformity of the produced crystals. Higher uniformity...
Effect of current density on DC electrochemical phosphating of stainless steel 316
, Article Surface and Coatings Technology ; Volume 205, Issue 7 , December , 2010 , Pages 2302-2306 ; 02578972 (ISSN) ; Afshar, A ; Hasannejad, H ; Sharif University of Technology
2010
Abstract
In this study, tri-cation phosphate coating of zinc, calcium and iron was applied electrochemically to stainless steel 316 substrates. Cathodic current was used as an accelerator for the phosphating process. The effects of current density on the microstructures of the coatings and the time necessary for the reduction of the oxide layer have been established. For this purpose, analyses such as chronopotentiometery, SEM, EDS and linear polarization were carried out. Results indicated that higher electrophosphating current densities result in finer crystal size of the coating. This effect is detrimental to the quality of the layer. In addition, chemical analyses of the layer revealed that the...
Effect of current density on electrochemical phosphating of stainless steel 316L
, Article TMS 2009 - 138th Annual Meeting and Exhibition, San Francisco, CA, 15 February 2009 through 19 February 2009 ; Volume 3 , 2009 , Pages 613-620 ; 9780873397407 (ISBN) ; Afshar, A ; Sharif University of Technology
2009
Abstract
In this study two cation coating of calcium and zinc has been developed on stainless steel 316L by electrochemical method. Cathodic current used as an accelerator for phosphating process and the effects of current density on microstructure of the phospahted layer and the time needed for termination of the phosphating process has been evaluated by potential-time, SEM, EDS, etc. Results indicate that higher current densities in electrochemical phosphating will result in heavier phospahted layer with finer crystal size which in turn deteriorates the quality of the layer by its higher porosity. Chemical analysis of the layer reveals that using the electrochemical method for phosphating of...
Visible light photocatalytic activity of novel MWCNT-doped ZnO electrospun nanofibers
, Article Journal of Molecular Catalysis A: Chemical ; Volume 359 , 2012 , Pages 42-48 ; 13811169 (ISSN) ; Shivaee, H. A ; Zanetti, M ; Pourjavadi, A ; Moshfegh, A ; Sharif University of Technology
2012
Abstract
Multi wall carbon nanotube (MWCNT) doped ZnO nanofibers were fabricated by electrospinning for the first time. We have successfully demonstrated the photocatalytic activity of doped nanofibers under visible light. Scanning electron microscopy showed that the diameter of MWCNT-doped ZnO nanofibers varied from 120 to 300 nm without agglomeration of MWCNT. Fourier transform infrared spectroscopy and X-ray diffraction studies proved the formation of ZnO bond and wurtzite structure with smaller crystal size in doped nanofibers. Raman spectra demonstrated slight shift in bond position after nanofiber doping, indicating the chemical bond between MWCNT and ZnO. X-ray photoelectron spectroscopy...
A wet cold-flow technology for tackling offshore flow-assurance problems
, Article SPE Projects, Facilities and Construction ; Volume 5, Issue 2 , 2010 , Pages 58-64 ; 19422431 (ISSN) ; Chapoy, A ; Anderson, R ; Tohidi, B ; Sharif University of Technology
2010
Abstract
Flow assurance is a major challenge in offshore and deepwater operations. Conventional approaches for preventing gas-hydrate formation involve using thermodynamic inhibitors (e.g., methanol, glycol) or kinetic hydrate inhibitors or operating outside the hydratestability zone by insulating the pipeline and/or active heating. These techniques are not always economical and in some cases are not practical for deepwater operations, long tiebacks, or aging reservoirs with high water cuts. The industry needs new and novel flow-assurance techniques to address these challenging conditions. The approach presented in this paper is a wet cold-flow-based method in which gas-hydrate management rather than...