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Articles 1 - 3 of 3
Full-Text Articles in Mechanical Engineering
The Effect Of Stirring On The Morphology Of Birnessite Nanoparticles, Marcos A. Cheney, Pradip K. Bhowmik, Shingo Moriuchi, Mario Villabos, Shizhi Qian, Sang W. Joo
The Effect Of Stirring On The Morphology Of Birnessite Nanoparticles, Marcos A. Cheney, Pradip K. Bhowmik, Shingo Moriuchi, Mario Villabos, Shizhi Qian, Sang W. Joo
Mechanical & Aerospace Engineering Faculty Publications
The effect of mechanical stirring on the morphology of hexagonal layer- structure birnessite nanoparticles produced from decomposition of KMnO4 in dilute aqueous H2SO4 is investigated, with characterization by X- ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high- resolution transmission electron microscopy (HRTEM), thermogravimetric analysis (TGA), and N2 adsorption (BET). Mechanical stirring during an initial stage of synthesis is shown to produce black birnessite containing nanofibers, whereas granular particulates of brown birnessite are produced without stirring. This is the first reduction synthesis of black birnessite nanoparticles with dendritic morphology without any use …
A New Method Of Synthesizing Black Birnessite Nanoparticles: From Brown To Black Birnessite With Nanostructures, Marcos A. Cheney, Pradip K. Bhowmik, Shizhi Qian, Sang W. Joo, Wensheng Hou, Joseph M. Okoh
A New Method Of Synthesizing Black Birnessite Nanoparticles: From Brown To Black Birnessite With Nanostructures, Marcos A. Cheney, Pradip K. Bhowmik, Shizhi Qian, Sang W. Joo, Wensheng Hou, Joseph M. Okoh
Mechanical & Aerospace Engineering Faculty Publications
A new method for preparing black birnessite nanoparticles is introduced. The initial synthesis process resembles the classical McKenzie method of preparing brown birnessite except for slower cooling and closing the system from the ambient air. Subsequent process, including wet-aging at 7° C for 48 hours, overnight freezing, and lyophilization, is shown to convert the brown birnessite into black birnessite with complex nanomorphology with folded sheets and spirals. Characterization of the product is performed by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), thermogravimetric analysis (TGA), and N(2) adsorption ( BET) techniques. Wet-aging and lyophilization times are …
Experimental Investigation Of Active Control Of Bluff Body Vortex Shedding, Ilteris Koc
Experimental Investigation Of Active Control Of Bluff Body Vortex Shedding, Ilteris Koc
Mechanical & Aerospace Engineering Theses & Dissertations
Mean and fluctuating forces acting on a body are strongly related to vortex shedding generated behind it. Therefore, it is possible to obtain substantial reductions of at least the unsteady forces if vortex shedding is controlled or its regularity is reduced. While conventional active flow control methods are mainly concerned with direct interaction with, and alteration of, the mean flow about a body, modern techniques involve altering existing flow instabilities using relatively small inputs to obtain large-scale changes of mean flows. Aerodynamic flow control may be intended to delay or suppress boundary layer separation through creation of a boundary layer …