Publications

2016
R. Rojo, Tinney, C. E., and Ruf, J., “Effect of stagger on the vibroacoustic loads from clustered rockets,” AIAA Journal, vol. 54, no. 11, pp. 3588-3597, 2016.Abstract
The effect of stagger startup on the vibroacoustic loads that form during the end-effects regime of clustered rockets is studied using both full-scale (hot-gas) and laboratory-scale (cold-gas) data with vehicle geometry. Both configurations comprise three nozzles with thrust-optimized parabolic contours that undergo free-shock separated flow and restricted-shock separated flow as well as an end-effects regime before flowing full. Acoustic pressure waveforms recorded at the base of the nozzle cluster are analyzed using various statistical metrics as well as time-frequency analysis. The findings reveal a significant reduction in end-effects regime loads when engine startups are staggered. However, regardless of stagger, both the skewness and kurtosis of the acoustic pressure time derivative elevate to the same levels, thereby demonstrating the intermittence and impulsiveness of the acoustic waveforms during the end effects regime.
A. Qajar, Daigle, H., and Prodanović, M., “The effects of pore geometry on adsorption equilibrium in shale formations and coal-beds: Lattice density functional theory study,” Fuel, vol. 163, pp. 205-213, 2016.
K. Yang, Yilmaz, A., and Torres-Verdín, C., “Efficient 3D parametric inversion of hydraulic fractures with low-frequency borehole tri-axial electromagnetic measurements (Expanded Abstract).,” Society of Exploration Geophysicists (SEG) 86th Ann. Internat. Mtg. Dallas, TX, October 16-21., 2016.
K. Yang, Yilmaz, A., and Torres-Verdín, C., “Efficient 3D parametric inversion of hydraulic fractures with low-frequency borehole tri-axial electromagnetic measurements (Expanded Abstract),” Society of Exploration Geophysicists (SEG) 86th Ann. Internat. Mtg. Dallas, TX, October 16-21, 2016.
T. Cantu, Rodier, B., Iszard, Z., Kilian, A., Pattani, V., Walsh, K., Weber, K., Tunnell, J., Betancourt, T., and Irvin, J., “Electroactive Polymer Nanoparticles Exhibiting Photothermal Properties,” no. 107, pp. e53631, 2016. Publisher's VersionAbstract
A method for the synthesis of electroactive polymers is demonstrated, starting with the synthesis of extended conjugation monomers using a three-step process that finishes with Negishi coupling. Negishi coupling is a cross-coupling process in which a chemical precursor is first lithiated, followed by transmetallation with ZnCl2. The resultant organozinc compound can be coupled to a dibrominated aromatic precursor to give the conjugated monomer. Polymer films can be prepared via electropolymerization of the monomer and characterized using cyclic voltammetry and ultraviolet-visible-near infrared (UV-Vis-NIR) spectroscopy. Nanoparticles (NPs) are prepared via emulsion polymerization of the monomer using a two-surfactant system to yield an aqueous dispersion of the polymer NPs. The NPs are characterized using dynamic light scattering, electron microscopy, and UV-Vis-NIR-spectroscopy. Cytocompatibility of NPs is investigated using the cell viability assay. Finally, the NP suspensions are irradiated with a NIR laser to determine their effectiveness as potential materials for photothermal therapy (PTT).
J. D. Escobar, Torres-Verdín, C., Proett, M., and Ma, S. M., “Evaluating the impact of multiphase flow properties on formation-tester pressure transients (Expanded Abstract).,” Society of Petroleum Engineers (SPE) 2016 Annual Technical Conference and Exhibition. Dubai, UAE, September 26-28., 2016.
J. D. Escobar, Torres-Verdín, C., Proett, M., and Ma, S. M., “Evaluating the impact of multiphase flow properties on formation-tester pressure transients (Expanded Abstract),” Society of Petroleum Engineers (SPE) 2016 Annual Technical Conference and Exhibition. Dubai, UAE, September 26-28, 2016.
A. M. Bergquist, Choe, J. K., Strathmann, T. J., and Werth, C. J., “Evaluation of a hybrid ion exchange-catalyst treatment technology for nitrate removal from drinking water,” Water Research, vol. 96, pp. 177-187, 2016. Publisher's VersionAbstract
Ion exchange (IX) is the most common approach to treating nitrate-contaminated drinking water sources, but the cost of salt to make regeneration brine, as well as the cost and environmental burden of waste brine disposal, are major disadvantages. A hybrid ion exchange-catalyst treatment system, in which waste brine is catalytically treated for reuse, shows promise for reducing costs and environmental burdens of the conventional IX system. An IX model with separate treatment and regeneration cycles was developed, and ion selectivity coefficients for each cycle were separately calibrated by fitting experimental data. Of note, selectivity coefficients for the regeneration cycle required fitting the second treatment cycle after incomplete resin regeneration. The calibrated and validated model was used to simulate many cycles of treatment and regeneration using the hybrid system. Simulated waste brines and a real brine obtained from a California utility were also evaluated for catalytic nitrate treatment in a packed-bed, flow-through column with 0.5 wt%Pd–0.05 wt%In/activated carbon support (PdIn/AC). Consistent nitrate removal and no apparent catalyst deactivation were observed over 23 d (synthetic brine) and 45 d (real waste brine) of continuous-flow treatment. Ion exchange and catalyst results were used to evaluate treatment of 1 billion gallons of nitrate-contaminated source water at a 0.5 MGD water treatment plant. Switching from a conventional IX system with a two bed volume regeneration to a hybrid system with the same regeneration length and sequencing batch catalytic reactor treatment would save 76% in salt cost. The results suggest the hybrid system has the potential to address the disadvantages of a conventional IX treatment systems.
C. Soares, Daigle, H., and Gray, K., “Evaluation of PDC bit ROP models and the effect of rock strength on model coefficients,” Journal of Natural Gas Science and Engineering, vol. 34, pp. 1225-1236, 2016.
M. Lotfollahi, Kim, I., Beygi, M. R., Worthen, A. J., Huh, C., Johnston, K. P., Wheeler, M. F., and DiCarlo, D. A., “Experimental Studies and Modeling of Foam Hysteresis in Porous Media,” SPE Improved Oil Recovery Conference. Society of Petroleum Engineers, 2016. Publisher's VersionAbstract
The use of foam in gas enhanced oil recovery (EOR) processes has the potential to improve oil recovery by reducing gas mobility. Nanoparticles are a promising alternative to surfactants in creating foam in the harsh environments found in many oil fields. We conducted several CO2-in-brine foam generation experiments in Boise sandstones with surface-treated silica nanoparticle in high-salinity conditions. All the experiments were conducted at the fixed CO2 volume fraction (g = 0.75) and fixed flow rate which changed in steps. We started at low flow rates, increased to a medium flow rates followed by decreasing and then increasing into high flow rates. The steady-state foam apparent viscosity was measured as a function of injection velocity. The foam flowing through the cores showed higher foam generation and consequently higher apparent viscosity as the flow rate increased from low to medium and high velocities. At very high velocities, once foam bubbles were finely textured, the foam apparent viscosity was governed by foam shear-thinning rheology rather than foam creation. A noticeable "hysteresis" occurred when the flow velocity was initially increased and then decreased, implying multiple (coarse and strong) foam states at the same superficial velocity. A normalized generation function was combined with CMG-STARS foam model to cover the full spectrum of foam flow behavior observed during the experiments. The new foam model successfully captures foam generation and hysteresis trends observed in presented experiments in this study and other foam generation experiments at different operational conditions (e.g. fixed pressure drop at fixed foam quality, and fixed pressure drop at fixed water velocity) from the literature. The results indicate once foam is generated in porous media, it is possible to maintain strong foam at low injection rates. This makes foam more feasible in field applications where foam generation is limited by high injection rates (or high pressure gradient) that may only exist near the injection well. Therefore, understanding of foam generation, and foam hysteresis in porous media and accurate modeling of the process are necessary steps for efficient foam design in field.
A. Canchero, Tinney, C. E., Murray, N., and Ruf, J. H., “Flow and acoustics of clustered rockets during startup,” AIAA Journal, vol. 54, no. 5, pp. 1660-1669, 2016.Abstract
The plume produced by a cluster of two large area-ratio thrust-optimized paraboliccontour nozzles is visualized over a range of nozzle pressure ratios by way of retrore-flective shadowgraphy. Both nozzles exhibit free-shock separated flow, restricted-shockseparated flow and an end-effects regime prior to flowing full. Transient (startup) op-erations of the nozzles are studied with the primary focus being the pulsations thatform during the end-effects regime. This occurs at a pressure ratio of 37 for thesenozzles and is associated with elevated sound levels in the immediate vicinity of thenozzles and vehicle. The shadowgraphy images reveal the formation of turbulent largescale structures, on the order of the nozzle diameter, during the end-effects regime.These large scale structures are driven by the intermittent opening of the last trappedannular separation bubble to the ambient and grow rapidly within the first two nozzlediameters.
B. Ghanbarian, Hunt, A. G., and Daigle, H., “Fluid flow in porous media with rough pore‐solid interface,” Water Resources Research, 2016.
M. Lotfollahi, Kim, I., Beygi, M. R., Worthen, A. J., Huh, C., Johnston, K. P., Wheeler, M. F., and DiCarlo, D. A., “Foam Generation Hysteresis in Porous Media: Experiments and New Insights,” Transport in Porous Media, pp. 1-17, 2016. Publisher's VersionAbstract
Foam application in subsurface processes including environmental remediation, geological carbon-sequestration, and gas-injection enhanced oil recovery (EOR) has the potential to enhance contamination remediation, secure CO2">CO2CO2 storage, and improve oil recovery, respectively. Nanoparticles are a promising alternative to surfactants in creating foam in harsh environments. We conducted CO2">CO2CO2-in-brine foam generation experiments in Boise sandstones with surface-treated silica nanoparticle in high-salinity conditions. All the experiments were conducted at the fixed CO2">CO2CO2 volume fraction and fixed flow rate which changed in steps. The steady-state foam apparent viscosity was measured as a function of injection velocity. The foam flowing through the cores showed higher apparent viscosity as the flow rate increased from low to medium and high velocities. At very high velocities, once foam bubbles were finely textured, the foam apparent viscosity was governed by foam rheology rather than foam creation. A noticeable hysteresis occurred when the flow velocity was initially increased and then decreased, implying multiple (coarse and strong) foam states at the same superficial velocity. A normalized generation function was combined with CMG-STARS foam model to cover full spectrum of foam behavior in the experiments. The new model successfully captures foam generation and hysteresis trends in presented experiments in this study and data from the literature. The results indicate once foam is generated in porous media, it is possible to maintain strong foam at low injection rates. This makes foam more feasible in field applications where foam generation is limited by high injection rates that may only exist near the injection well.
R. J. Stover, Moaseri, E., Gourisankar, S. P., Iqbal, M., Rahbar, N. K., Changalvaie, B., Truskett, T. M., and Johnston, K. P., “Formation of Small Gold Nanoparticle Chains with High NIR Extinction through Bridging with Calcium Ions,” Langmuir, vol. 32, no. 4, pp. 1127-1138, 2016. Publisher's VersionAbstract
The self-assembly of citrate-capped Au nanoparticles (5 nm) resulted in branched nanochains by adding CaCl2 versus spherical nanoclusters for NaCl. These assemblies were formed between 1 s to 30 min by tuning the electrostatic repulsion and the interparticle bridging attraction between the cations and citrate ligands as a function of electrolyte concentration. For dilute Ca2+, strong interparticle bridging favored particle attachment at chain ends. This resulted in the formation of small, branched chains with lengths as short as 20 nm, due to the large Debye length for the diffuse counterions. Furthermore, the bridging produced very small interparticle spacings and sintering, as evident in high-resolution TEM despite the low temperature. This morphology produced a large red shift in the surface plasmon resonance, as characterized by a broad extinction peak with NIR absorption out to 1000 nm, which is unusual for such small particles. Whereas these properties were seen for primary particles with partial citrate monolayers, the degrees of sintering and NIR extinction were small in the case of citrate multilayers. The ability to design the size and shape of nanoparticle clusters as well as the interparticle spacing by tuning bridging and electrostatic interactions may be expected to be quite general and of broad applicability in materials synthesis
P. Zhang, Shiriyev, J., Torres-Verdín, C., Sharma, M. M., Brick, Y., Massey, J., and Yilmaz, A., “Fracture diagnostics using a low-frequency electromagnetic induction method (Extended Abstract).,” American Rock Mechanics Association (ARMA) 50th US Rock Mechanics/Geomechanics Symposium. Houston, Texas, June 26-29, 2016.
P. Zhang, Shiriyev, J., Torres-Verdín, C., Sharma, M. M., Brick, Y., Massey, J., and Yilmaz, A., “Fracture diagnostics using a low-frequency electromagnetic induction method (Extended Abstract),” American Rock Mechanics Association (ARMA) 50th US Rock Mechanics/Geomechanics Symposium. Houston, Texas, June 26-29, 2016.
J. K. Bean and Hildebrandt Ruiz, L., “Gas-particle partitioning and hydrolysis of organic nitrates formed from the oxidation of alpha-pinene in environmental chamber experiments,” Atmos. Chem. Phys., vol. 16, pp. 2175-2184, 2016. Publisher's Version
M. Kayyalha, Maassen, J., Lundstrom, M., Shi, L., and Chen, Y. P., “Gate-tunable and thickness-dependent electronic and thermoelectric transport in few-layer MoS2,” Journal of Applied Physics, vol. 120, pp. 134305, 2016. Publisher's Version
R. Qi, Wang, Q., and Ren, P., “General van der Waals potential for common organic molecules,” Bioorg Med ChemBioorg Med Chem, vol. 24, pp. 4911-4919, 2016.Abstract
This work presents a systematic development of a new van der Waals potential (vdW2016) for common organic molecules based on symmetry-adapted perturbation theory (SAPT) energy decomposition. The Buf-14-7 function, as well as Cubic-mean and Waldman-Hagler mixing rules were chosen given their best performance among other popular potentials. A database containing 39 organic molecules and 108 dimers was utilized to derive a general set of vdW parameters, which were further validated on nucleobase stacking systems and testing organic dimers. The vdW2016 potential is anticipated to significantly improve the accuracy and transferability of new generations of force fields for organic molecules.
Z. Wang, Xu, X., Fan, D., Wang, Y., Subbaraman, H., and Chen, R. T., “Geometrical tuning art for entirely subwavelength grating waveguide based integrated photonics circuits,” Scientific Reports, vol. 6, pp. 24106, 2016. Publisher's VersionAbstract
Subwavelength grating (SWG) waveguide is an intriguing alternative to conventional optical waveguides due to the extra degree of freedom it offers in tuning a few important waveguide properties, such as dispersion and refractive index. Devices based on SWG waveguides have demonstrated impressive performances compared to conventional waveguides. However, the high loss of SWG waveguide bends jeopardizes their applications in integrated photonic circuits. In this work, we propose a geometrical tuning art, which realizes a pre-distorted refractive index profile in SWG waveguide bends. The pre-distorted refractive index profile can effectively reduce the mode mismatch and radiation loss simultaneously, thus significantly reduce the bend loss. This geometry tuning art has been numerically optimized and experimentally demonstrated in present study. Through such tuning, the average insertion loss of a 5 μm SWG waveguide bend is reduced drastically from 5.43 dB to 1.10 dB per 90° bend for quasi-TE polarization. In the future, the proposed scheme will be utilized to enhance performance of a wide range of SWG waveguide based photonics devices.
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