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Full-Text Articles in Engineering

Expanded Mathematical Treatment For "Spectral Bias In Adaptive Beamforming With Narrowband Interference'', Brian D. Jeffs, Karl F. Warnick Jan 2008

Expanded Mathematical Treatment For "Spectral Bias In Adaptive Beamforming With Narrowband Interference'', Brian D. Jeffs, Karl F. Warnick

Faculty Publications

This technical note presents extended versions of some mathematical derivations found in the paper Spectral Bias in Adaptive Beamforming with Narrowband Interference which is under review for publication in IEEE Signal Processing Letters. Though the SP Letters paper is self contained and complete, this note provides intermediate steps for some of the equation derivations to assist the interested readers who would like to re-create the results.


Air-Trench Splitters For Ultra-Compact Ring Resonators In Low Refractive Index Contrast Waveguides, Seunghyun Kim, Gregory P. Nordin, Yongbin Lin, Nazli Rahmanian Jan 2008

Air-Trench Splitters For Ultra-Compact Ring Resonators In Low Refractive Index Contrast Waveguides, Seunghyun Kim, Gregory P. Nordin, Yongbin Lin, Nazli Rahmanian

Faculty Publications

We demonstrate air-trench splitters in low index contrast perfluorocyclobutyl (PFCB) waveguides. Splitters are fabricated by etching 800 nm wide high aspect ratio (18:1) trenches. The measured optical loss is 0.4 dB/splitter. The reflection/transmission splitting ratio is 0.859/0.141, which closely matches two-dimensional finite difference time domain (2DFDTD) simulation results. Air-trench splitters and bends are used to demonstrate an ultra-compact ring resonator (RR) with a size reduction of 1,700 compared to a RR based on traditional curved waveguides in the same material system. A comparison between the RR’s measured and analytically calculated performance shows close agreement when splitter and bend losses are …


Reduced Order Modeling Of Time-Dependent Reflectance Profiles From Purely Scattering Media, R. Scott Larson, Matthew R. Jones Jan 2008

Reduced Order Modeling Of Time-Dependent Reflectance Profiles From Purely Scattering Media, R. Scott Larson, Matthew R. Jones

Faculty Publications

Due to the widespread existence and importance of foam, inverse techniques for characterizing industrial foams are of interest. An essential element in an inverse method used to characterize a foam layer is a model of the time-dependent reflectance of a laser pulse. Monte Carlo methods may be used to accurately model reflectance, but these methods are computationally expensive. Computationally efficient methods based on the diffusion approximation have been developed, but this approach is not sufficiently accurate in many cases of interest. Therefore, a computationally efficient and robust method is desirable. This paper presents a computationally efficient method for modeling the …


Evolution Of Surface Deposits On A High-Pressure Turbine Blade—Part I: Physical Characteristics, James Edward Wammack, Jared M. Crosby, Daniel Fletcher, Jeffrey P. Bons, Thomas H. Fletcher Jan 2008

Evolution Of Surface Deposits On A High-Pressure Turbine Blade—Part I: Physical Characteristics, James Edward Wammack, Jared M. Crosby, Daniel Fletcher, Jeffrey P. Bons, Thomas H. Fletcher

Faculty Publications

Turbine blade coupons with three different surface treatments were exposed to deposition conditions in an accelerated deposition facility. The facility simulates the flow conditions at the inlet to a first stage high-pressure turbine (T=1150 C, M=0.31). The combustor exit flow is seeded with dust particulate that would typically be ingested by a large utility power plant. The three coupon surface treatments included: (1) bare polished metal; (2) polished thermal barrier coating with bondcoat; and (3) unpolished oxidation resistant bondcoat. Each coupon was subjected to four successive 2 h deposition tests. The particulate loading was scaled to simulate 0.02 parts per …


Effects Of Temperature And Particle Size On Deposition In Land Based Turbines, Jared M. Crosby, Scott Lewis, Jeffrey P. Bons, Weiguo Ai, Thomas H. Fletcher Jan 2008

Effects Of Temperature And Particle Size On Deposition In Land Based Turbines, Jared M. Crosby, Scott Lewis, Jeffrey P. Bons, Weiguo Ai, Thomas H. Fletcher

Faculty Publications

Four series of tests were performed in an accelerated deposition test facility to study the independent effects of particle size, gas temperature, and metal temperature on ash deposits from two candidate power turbine synfuels (coal and petcoke). The facility matches the gas temperature and velocity of modern first stage high pressure turbine vanes while accelerating the deposition process. Particle size was found to have a significant effect on capture efficiency with larger particles causing significant thermal barrier coating (TBC) spallation during a 4 h accelerated test. In the second series of tests, particle deposition rate was found to decrease with …


Evolution Of Surface Deposits On A High-Pressure Turbine Blade—Part Ii: Convective Heat Transfer, Jeffrey P. Bons, James Edward Wammack, Jared M. Crosby, Daniel Fletcher, Thomas H. Fletcher Jan 2008

Evolution Of Surface Deposits On A High-Pressure Turbine Blade—Part Ii: Convective Heat Transfer, Jeffrey P. Bons, James Edward Wammack, Jared M. Crosby, Daniel Fletcher, Thomas H. Fletcher

Faculty Publications

A thermal barrier coating (TBC)-coated turbine blade coupon was exposed to successive deposition in an accelerated deposition facility simulating flow conditions at the inlet to a first stage high pressure turbine (T=1150 C, M=0.31). The combustor exit flow was seeded with dust particulate that would typically be ingested by a large utility power plant. The turbine coupon was subjected to four successive 2 h deposition tests. The particulate loading was scaled to simulate 0.02 parts per million weight (ppmw) of particulate over 3 months of continuous gas turbine operation for each 2 h laboratory simulation (for a cumulative 1 year …


Socially Rational Models For Autonomous Agents, Wynn C. Stirling, James K. Archibald, Matthew S. Nokleby Jan 2008

Socially Rational Models For Autonomous Agents, Wynn C. Stirling, James K. Archibald, Matthew S. Nokleby

Faculty Publications

Autonomous multi-agent systems that are to coordinate must be designed according to models that accommodate such complex social behavior as compromise, negotiation, and altruism. In contrast to individually rational models, where each agent seeks to maximize its own welfare without regard for others, socially rational agents have interests beyond themselves. Such models require a new type of utility function a social utility to ensure three desirable properties: (a) conditional preferences agents may adjust their preferences to account for the preferences of others; (b) endogeny group preferences are determined internally by interactions between individual agents; (c) framing invariance reformulations of the …