Publications by Type: Conference Proceedings

In Press, 2018
E. Bakolas, “Finite-Horizon Separation-Based Covariance
Control for Discrete-Time Stochastic Linear Systems
,” IEEE CDC. Miami, FL., In Press, 2018.
D. Pylorof and Bakolas, E., “Stabilization of Input Constrained Nonlinear
Systems with Imperfect State Feedback Using Sum-of-Squares
Programming
,” IEEE CDC. Miami, FL., In Press, 2018.
2017
D. Pardo and Torres-Verdín, C., “1.5D-based inversion of logging-while drilling resistivity measurements in 3D formations (Expanded Abstract),” European Association of Geoscientists and Engineers (EAGE) 79th Ann. Conference and Exhibition. Paris, France, June 12-15., 2017.
X. Xu, Pan, Z., Jia, B., Wang, Y., and Chen, R. T., “All-optical switch with 1 ps response time enabled by graphene oxide infiltrated subwavelength grating waveguide,” Silicon Photonics XII, vol. 10108. San Francisco, California, United States, pp. 1010805, 2017. Publisher's VersionAbstract
In this paper, we propose an all-optical switch using graphene oxide (GO) infiltrated subwavelength grating (SWG) waveguide. Benefiting from the extremely large Kerr coefficient of GO (four orders of magnitude larger than conventional materials) and large mode volume overlap factor of the SWG (4~10 times larger than conventional strip waveguides), the switch is capable of achieving THz speed with less than 1 fJ energy consumption per bit, which is more than three orders of magnitude smaller than THz switches reported so far.
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E. Bakolas, “Covariance Control for Discrete-Time Stochastic Linear Systems with
Incomplete State Information
,” American Control Conference. Seattle, WA, 2017.PDF icon eb_acc_2017.pdf
N. Khusnatdinov, Resnick, D. J., Singhal, S., Grigas, M. M., and Sreenivasan, S. V., “Development Of An Inkjet-enabled Adaptive Planarization Process,” SPIE Photomask Technology Conference, vol. 10451. SPIE, Monterey CA, 2017. Publisher's VersionAbstract
Nanoimprint lithography manufacturing utilizes a patterning technology that involves the field-by-field deposition and exposure of a low viscosity resist deposited by jetting technology onto the substrate. The patterned mask is lowered into the fluid which then quickly flows into the relief patterns in the mask by capillary action. Following this filling step, the resist is crosslinked under UV radiation, and then the mask is removed, leaving a patterned resist on the substrate. The technology faithfully reproduces patterns with a higher resolution and greater uniformity compared to those produced by photolithography equipment. Throughputs of 80 wph have been demonstrated, and mix and match overlay of 3.7nm 3 sigma has been achieved. The technology has already been successfully applied as a demonstration to the fabrication of advanced NAND Flash memory devices. A similar approach can also be applied however to remove topography on an existing wafer, thereby creating a planar surface on which to pattern. In this paper, a novel adaptive planarization process is presented that addresses the problems associated with planarization of varying pattern densities, even in the presence of pre-existing substrate topography. The process is called Inkjet-enabled Adaptive Planarization (IAP). The IAP process uses an inverse optimization scheme, built around a validated fluid mechanics-based forward model that takes the pre-existing substrate topography and pattern layout as inputs. It then generates an inkjet drop pattern with a material distribution that is correlated with the desired planarization film profile. This allows a contiguous film to be formed with the desired thickness variation to cater to the topography and any parasitic signatures caused by the pattern layout. In this work, it was demonstrated that planarization efficiencies of up to 99.5% could be achieved, thereby reducing an initial similar to 100nm wafer topography down to as little as 0.6nm.
C. E. Tinney, Hill, B., Valdez, J., Sirohi, J., and Cameron, C., “Drone acoustics at static thrust conditions,” American Helicopgter Society 73rd Annual Forum. Fort Worth, Texas, USA, 2017.Abstract
Multirotor drones are becoming increasingly popular in both the civilian and military sectors of our society. These compact gadgets come in a variety of sizes with the smallest ones measuring less than two inches in diameter, while larger ones can be in excess of five feet. Surprisingly, very little is known about their acoustical footprint, which is becoming a topic of broad importance given that these vehicles most often operate in populated areas. Thus, the objective of this paper is to provide a first principles understanding of the acoustical characteristics of hovering drones. To accomplish this, a new test stand was constructed at the Applied Research Laboratories at The University of Texas at Austin for studying various multirotor drone configurations. The drone test stand is capable of powering up to eight DC electric motors with adjustable arms that allow different rotor diameters to be tested. Rotor diameters ranging from 8 in to 12 in are studied and with configurations comprised of an isolated rotor, a quadcopter configuration and a hexacopter configuration. A six degree-of-freedom load cell is used to assess the aerodynamic performance of each drone configuration. Meanwhile, an azimuthal array of 1/2-inch microphones is placed between 2 and 3 hub-center diameters from the drone center thereby allowing the acoustic near-field to be quantified. The analysis is performed using standard statistical metrics such as Sound Pressure Level and Overall Sound Pressure Level and is presented to demonstrate the relationship between the number of rotors, the drone rotor size and it’s aerodynamic performance (thrust) relative to the far-field noise.
C. E. Tinney, Scott, K., Routon, M., Sirohi, J., and Ruf, J., “Effect of aeroelasticity on vibroacoustic loads during startup of large area ratio nozzles,” 23rd AIAA/CEAS Aeroacoustics Conference. Denver, Colorado, USA, 2017.Abstract
The vibroacoustic loads that form during the startup of both rigid and compliant wallhigh area ratio nozzles is investigated. The rigid wall nozzle is fabricated from 6061 aluminum while the compliant wall nozzles are formed from urethane-based elastomers in orderto invoke aeroelastic coupling between the nozzle wall and the internal flow. Single pointmeasurements of the nozzle lip displacement are synchronized with a pressure field microphone located behind the nozzle where the base of a vehicle would reside. Particularattention is drawn to the sound field during transition from free-shock separated flow torestricted shock separated flow, as well as the end-effects regime loads. The findings revealthe sensitivity of the vibroacoustic loads to the aeroelasticity of the nozzle wall duringcritical stages in the startup process.
E. D. Maalouf and Torres-Verdín, C., “Estimation of rock stiffness coefficients in VTI formations using LWD acoustic measurements (Expanded Abstract),” Society of Petrophysicists and Well Log Analysts (SPWLA) 58th Ann. Logging Symposium. Oklahoma City, OK, June 17-21, 2017.
J. Selvakumar and Bakolas, E., “Evasion with Terminal Constraints from a Group of Pursuers using a
Matrix Game Formulation
,” American Control Conference. Seattle, WA, 2017.PDF icon jseb_acc17.pdf
A. Rodríguez-Rozas, Pardo, D., and Torres-Verdín, C., “Fast 3D inversion of borehole resistivity measurements using a dimension-adaptive simulation method (Expanded Abstract),” Sixth International Symposium on Three-Dimensional Electromagnetics. Berkeley, CA, March 28-30, 2017.
A. Rodríguez-Rozas, Pardo, D., and Torres-Verdín, C., “Fast simulation of 2.5D LWD resistivity tools (Expanded Abstract),” European Association of Geoscientists and Engineers (EAGE) 79th Ann. Conference and Exhibition. Paris, France, June 12-15, 2017.
J. Joseph, Tinney, C. E., and Murray, N., “Ideal gas effects in aeroacoustics,” 55th AIAA Aerospace Sciences Meeting, AIAA Paper 2017-0688. Grapevine, Texas, USA, 2017.Abstract
The use of helium-air mixtures to simulate the effects of elevated temperatures in aeroacoustics is plagued by the inability to match exactly the density and sound speed ratios between the jet flow and the ambient field, all the while maintaining the same gas dynamic Mach number and jet exit velocity. Real heated jet flows are typically achieved using either propane combustion in air or kerosene combustion in air, which results in the formation of carbon-dioxide and water vapor byproducts. In an effort to level the playing field between the heat simulated helium-air mixture system and the air breathing combustion system, a theoretical model is developed to isolate the effect of combustion byproducts on these aeroacoustic parameters to see if similar discrepancies arise. The motivation is to narrow the gap between laboratory and full-scale jet noise testing. Gas properties from the new combustion model are validated by laboratory measurements of a real propane combustion system as well as outputs from NASA’s Chemical Equilibrium with Applications code. The findings reveal how the additional combustion byproducts from propane combustion in air and kerosene combustion in air have a negligible effect on the parameters relevant to jet noise. Closer inspection of the helium-air mixture system demonstrates how variations in the Mach wave radiation angle at moderate pressure and temperature ratios of the nozzle is accurate to within a couple of degrees, relative to a pure heated air system. Similar accuracy is reported with the far-field intensity.
PDF icon c2017aiaa-grapevinejoseph-0688.pdf
C. Schroeder, Torres-Verdín, C., and Elshahawi, H., “Influence of mud-filtrate invasion effects on pressure gradients estimated from wireline formation-tester measurements (Expanded Abstract),” Society of Petrophysicists and Well Log Analysts (SPWLA) 58th Ann. Logging Symposium. Oklahoma City, OK, June 17-21, 2017.
V. Puzyrev, Torres-Verdín, C., and Calo, V., “Interpretation of deep directional resistivity measurements in high-angle and horizontal wells (Expanded Abstract),” Sixth International Symposium on Three-Dimensional Electromagnetics. Berkeley, CA, March 28-30, 2017.
E. D. Maalouf and Torres-Verdín, C., “Interpretation of sonic measurements acquired in high-angle and horizontal wells using 3D fast forward modeling (Expanded Abstract),” Society of Petrophysicists and Well Log Analysts (SPWLA) 58th Ann. Logging Symposium. Oklahoma City, OK, June 17-21, 2017.
A. Mehmani, Kelly, S., Torres-Verdín, C., and Balhoff, M., “Quantification of fracture-matrix fluid transport in unconventional rocks using two-scale microfluidic chips (Expanded Abstract),” Unconventional Resources Technology Conference (URTeC). Austin, Texas, July 24 – 26, 2017.
A. Menshov, Brick, Y., Torres-Verdín, C., and Yilmaz, A. E., “Recent progress in rigorous algorithms for the fast solution of 3-D EM frequency-domain integral equations (Expanded Abstract),” Sixth International Symposium on Three-Dimensional Electromagnetics. Berkeley, CA, March 28-30, 2017.

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