Nanoscale Surface Roughness Affects Low Reynolds Number Flow: Experiments And Modeling, 2012 Iowa State University
Nanoscale Surface Roughness Affects Low Reynolds Number Flow: Experiments And Modeling, Robert Jaeger, Jing Ren, Yu Xie, Sriram Sundararajan, Michael G. Olsen, Baskar Ganapathysubramanian
Mechanical Engineering Publications
Most micro-channel fabrication strategies generate nano-to-micro-scale, stochastic surface roughness. This inherent stochasticity can potentially be harnessed to direct microfluidic operations such as self-cleaning behavior and localized mixing. This work investigates the effect of stochastic nanoscale roughness on low to moderate Reynolds number Newtonian flow using concurrent modeling and experiments. We fabricate a microscopic channel with tailored hydrofluoric-acid-etched rough surfaces. Optical profilometry and micro-particle-image-velocimetry (micro-PIV) are used to characterize the surface roughness and flow field and is integrated with direct numerical simulation that resolves effects of nanoscale roughness. Results indicate that nanoscale roughness causes flow perturbations that extend up to the ...
Investigating Polymer-Tool Steel Interfaces To Predict The Work Of Adhesion For Demoulding Force Optimisation, 2011 Technological University Dublin
Investigating Polymer-Tool Steel Interfaces To Predict The Work Of Adhesion For Demoulding Force Optimisation, Kevin Delaney, David Kennedy, Giuliano Bissacco
Demoulding parts from replication tools is a critical stage of replication processes such as injection moulding and hot embossing. This challenge increases as part size decreases since components and associated replication cores become more fragile and liable to damage. Understanding interfacial characteristics between a polymer and the tool surface is critical to optimise the demoulding of such parts from replication tools. The strength of the polymer-tool interaction is characterised by the adhesion energy and is specific for a particular polymer-tool pair. It’s magnitude depends upon the tool material, the chemical structure of the polymer, the processing conditions and the ...
Rayleigh Test Apparatus Design Report, 2011 California Polytechnic State University - San Luis Obispo
Rayleigh Test Apparatus Design Report, Josef Duller, Owen Raybould, James Nicovich
The Rayleigh Test Apparatus is a device that will be used to test the thermodynamic properties of Nitrous Oxide to assess the feasibility of using this fluid as a coolant for a hybrid rocket aero spike. The aero spike is intended to redirect the propulsion flow as it leaves the engine to create a more efficient flow pattern at low and high altitudes. However, there are issues of overheating which leads to melting of the aero spike. For this reason, the use of nitrous oxide (N2O) as a coolant is being explored. N20 is being considered because it is already ...
Manufacturing Self-Assembled Coatings Of Micro- And Nano-Particles By Controlled Evaporation Of Drops And Thin Films, Junfeng Xiao, Rajneesh Bhardwaj, Daniel Attinger
The engineered deposition of self-assembled coatings of micro- and nano-particles on solid surfaces has applications in photonic crystals, optoelectronic devices, sensors, waveguides and antireflective coatings. Besides lithographic, etching or vapor deposition methods, these coatings can be self-assembled on small (
In Situ Transmission Electron Microscopy Study On The Phase Transitionsin Lead-Free (1−X)(Bi1/2na1/2)Tio3–Xbatio3 Ceramics, C. Ma, Xiaoli Tan
Materials Science and Engineering Publications
The phase transitions in unpoled lead-free (1−x)(Bi1/2Na1/2)TiO3–xBaTiO3 (x = 0.06 and 0.11) ceramics are investigated using hot-stage transmission electron microscopy (TEM). It is found that large ferroelectric domains in both ceramics start to disappear around Td, the depolarization temperature. After the transition, both compositions exhibit the P4bm tetragonal symmetry in the form of nanodomains. The structural transition observed by the in situTEM experiments seems to be gradual and occurs within a temperature range of several tens of degrees, in contrast to the sharp ...
Patterning Of Alloy Precipitation Through External Pressure, 2010 University of Pennsylvania
Patterning Of Alloy Precipitation Through External Pressure, Jack A. Franklin
Publicly Accessible Penn Dissertations
Due to the nature of their microstructure, alloyed components have the benefit of meeting specific design goals across a wide range of electrical, thermal, and mechanical properties. In general by selecting the correct alloy system and applying a proper heat treatment it is possible to create a metallic sample whose properties achieve a unique set of design requirements. This dissertation presents an innovative processing technique intended to control both the location of formation and the growth rates of precipitates within metallic alloys in order to create multiple patterned areas of unique microstructure within a single sample. Specific experimental results for ...
Atomic Force Microscopy For Better Probing Surface Properties At Nanoscale: Calibration, Design And Application, 2010 The University of Western Ontario
Atomic Force Microscopy For Better Probing Surface Properties At Nanoscale: Calibration, Design And Application, Yu Liu
Electronic Thesis and Dissertation Repository
To measure force by AFM with high resolution requires accurate calibration of optic – lever detection sensitivity and spring constant. On biological AFM force mode, the coupling effects of the liquid environment, spot size of laser beam and laser spot location on AFM cantilever backside, must be considered to correlate the static sensitivities from force curves in air and in liquid for calibration. An effective model has been developed first and experimentally elucidated to calibrate the static sensitivity in liquid. The proposed model eliminates inconvenience of static sensitivity calibration in liquid with possible contamination sources.
The static sensitivity based on force ...
Self-Assembly Of Colloidal Particles From Evaporating Droplets: Role Of Dlvo Interactions And Proposition Of A Phase Diagram, Rajneesh Bhardwaj, Xiaohua Fang, Ponisseril Somasundaran, Daniel Attinger
The shape of deposits obtained from drying drops containing colloidal particles matters for technologies such as inkjet printing, microelectronics, and bioassay manufacturing. In this work, the formation of deposits during the drying of nanoliter drops containing colloidal particles is investigated experimentally with microscopy and profilometry, and theoretically with an in-house finite-element code. The system studied involves aqueous drops containing titania nanoparticles evaporating on a glass substrate. Deposit shapes from spotted drops at different pH values are measured using a laser profilometer. Our results show that the pH of the solution influences the dried deposit pattern, which can be ring-like or ...