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Articles 1 - 15 of 15
Full-Text Articles in Engineering
Generation Of Vector Partially Coherent Optical Sources Using Phase-Only Spatial Light Modulators, Milo W. Hyde Iv, Santasri Bose-Pillai, David G. Voelz, Xifeng Xiao
Generation Of Vector Partially Coherent Optical Sources Using Phase-Only Spatial Light Modulators, Milo W. Hyde Iv, Santasri Bose-Pillai, David G. Voelz, Xifeng Xiao
Faculty Publications
A simple and flexible optical system for generating electromagnetic or vector partially coherent sources or beams is presented. The alternative design controls field amplitude (beam shape), coherence, and polarization using only spatial light modulators. This improvement makes the apparatus simpler to construct and significantly increases the flexibility of vector partially coherent source generators by allowing many different types of sources to be produced without changing the physical setup. The system’s layout and theoretical foundations are thoroughly discussed. The utility and flexibility of the proposed system are demonstrated by producing a vector Schell-model and non-Schell-model source. The experimental results are compared …
Dual Role Of Sb Ions As Electron Traps And Hole Traps In Photorefractive Sn2P2S6 Crystals, Brant E. Kananen, Eric M. Golden, Sergey A. Basun, D. R. Evans, A. A. Grabar, I. M. Stoika, John W. Mcclory, Nancy C. Giles, Larry E. Halliburton
Dual Role Of Sb Ions As Electron Traps And Hole Traps In Photorefractive Sn2P2S6 Crystals, Brant E. Kananen, Eric M. Golden, Sergey A. Basun, D. R. Evans, A. A. Grabar, I. M. Stoika, John W. Mcclory, Nancy C. Giles, Larry E. Halliburton
Faculty Publications
Doping photorefractive single crystals of Sn2P2S6 with antimony introduces both electron and hole traps. In as-grown crystals, Sb3+ (5s2) ions replace Sn2+ ions. These Sb3+ ions are either isolated (with no nearby perturbing defects) or they have a charge-compensating Sn2+ vacancy at a nearest-neighbor Sn site. When illuminated with 633 nm laser light, isolated Sb3+ ions trap electrons and become Sb2+ (5s25p1) ions. In contrast, Sb3+ ions with an adjacent Sn vacancy trap holes during illumination. The hole is primarily …
Benchmarking Approach For Empirical Comparison Of Pricing Models In Drms, Seif Azghandi, Kenneth M. Hopkinson, Kennard R. Laviers
Benchmarking Approach For Empirical Comparison Of Pricing Models In Drms, Seif Azghandi, Kenneth M. Hopkinson, Kennard R. Laviers
Faculty Publications
emand response management systems often involve the use of pricing schemes to motivate the efficient use of electrical power. Achieving this efficiency requires the detection of electrical power patterns. The detection of these patterns normally involves use of non-linear, quasi-non-linear, and at times linear data pattern detection models. The behavioural disparities of these models and specifically when used for a specific set of data make it hard to select the most efficient model. The contribution of this study is devising an empirical benchmark (reference) ( perfect ) control pricing (PCP) model through which various models are compared in order to …
Investigation Of Shadowing Effects In Typical Propagation Scenarios For High Speed Railway At 2350 Mhz, Liu Liu, Cheng Tao, David W. Matolak, Tao Zhou, Houjin Chen
Investigation Of Shadowing Effects In Typical Propagation Scenarios For High Speed Railway At 2350 Mhz, Liu Liu, Cheng Tao, David W. Matolak, Tao Zhou, Houjin Chen
Faculty Publications
Based on realistic measurements in China, shadowing characteristics at the frequency of 2350 MHz were investigated in typical High-Speed Railway environments. After confirming that the measured shadowing satisfies wide-sense stationarity (assessed via the reverse arrangement test method), we quantify the shadowing correlation. Three types of correlation models are compared for the shadowing characterization, and the Normalized Mean Square Error is used to determine the best matching model: a single decaying exponential function. Decorrelation distances were found to be 11.9 m, 17.7 m, and 8.3 m in our three HSR scenarios, respectively. The results should be useful for the evaluation and …
Thermal Management Using Mems Bimorph Cantilever Beams, Ronald A. Coutu Jr., Robert S. Lafleur, John P. Walton, Laverne A. Starman
Thermal Management Using Mems Bimorph Cantilever Beams, Ronald A. Coutu Jr., Robert S. Lafleur, John P. Walton, Laverne A. Starman
Faculty Publications
This paper examines a passive cooling technique using microelectromechanical systems (MEMS) for localized thermal management of electronic devices. The prototype was designed using analytic equations, simulated using finite element methods (FEM), and fabricated using the commercial PolyMUMPs™ process. The system consisted of an electronic device simulator (EDS) and MEMS bimorph cantilever beams (MBCB) array with beams lengths of 200, 250, and 300 μm that were tested to characterize deflection and thermal behavior. The specific beam lengths were chosen to actuate in response to heating associated with the EDS (i.e. the longest beams actuated first corresponding to the hottest portion of …
Direct Bandgap Cross-Over Point Of Ge1-YSnY Grown On Si Estimated Through Temperature-Dependent Photoluminescence Studies, Thomas R. Harris, Mee-Yi Ryu, Yung Kee Yeo, Buguo Wang, C. L. Senaratne
Direct Bandgap Cross-Over Point Of Ge1-YSnY Grown On Si Estimated Through Temperature-Dependent Photoluminescence Studies, Thomas R. Harris, Mee-Yi Ryu, Yung Kee Yeo, Buguo Wang, C. L. Senaratne
Faculty Publications
Epitaxial Ge1-ySny (y = 0%–7.5%) alloys grown on either Si or Ge-buffered Si substrates by chemical vapor deposition were studied as a function of Sn content using temperature-dependent photoluminescence (PL). PL emission peaks from both the direct bandgap (Γ-valley) and the indirect bandgap (L-valley) to the valence band (denoted by ED and EID, respectively) were clearly observed at 125 and 175 K for most Ge1-ySny samples studied. At 300 K, however, all of the samples exhibited dominant ED emission with either very weak or no measureable EID emission. At 10 K, …
Variable Response Of A Thermally Tuned Mems Pressure Sensor, Robert A. Lake, Ronald A. Coutu Jr.
Variable Response Of A Thermally Tuned Mems Pressure Sensor, Robert A. Lake, Ronald A. Coutu Jr.
Faculty Publications
A typical microelectromechanical systems (MEMS) pressure sensor consists of a thin, deformable membrane and sensing element such as a piezoresistive element which is used to measure the amount of deflection in response to an applied pressure. Previous efforts demonstrated that buckled membranes, from silicon on insulator (SOI) wafers, can be thermally tuned via joule heating. By applying heat to the membrane through a resistive heating element, compressive stress is induced in the membrane causing it to buckle further out of plane and increasing its overall stiffness response. It is demonstrated that by increasing the stiffness of the membrane, the response …
Benefits Of Considering More Than Temperature Acceleration For Gan Hemt Life Testing, Ronald A. Coutu Jr., Robert A. Lake, Bradley D. Christiansen, Eric R. Heller, Christopher A. Bozada, Brian S. Poling, Glen D. Via, James P. Theimer, Stephen E. Tetlak, Ramakrishna Vetury, Jeffrey B. Shealy
Benefits Of Considering More Than Temperature Acceleration For Gan Hemt Life Testing, Ronald A. Coutu Jr., Robert A. Lake, Bradley D. Christiansen, Eric R. Heller, Christopher A. Bozada, Brian S. Poling, Glen D. Via, James P. Theimer, Stephen E. Tetlak, Ramakrishna Vetury, Jeffrey B. Shealy
Faculty Publications
The purpose of this work was to investigate the validity of Arrhenius accelerated-life testing when applied to gallium nitride (GaN) high electron mobility transistors (HEMT) lifetime assessments, where the standard assumption is that only critical stressor is temperature, which is derived from operating power, device channel-case, thermal resistance, and baseplate temperature. We found that power or temperature alone could not explain difference in observed degradation, and that accelerated life tests employed by industry can benefit by considering the impact of accelerating factors besides temperature. Specifically, we found that the voltage used to reach a desired power dissipation is important, and …
High Density 3d Printed Microfluidic Valves, Pumps, And Multiplexers, Hua Gong, Adam T. Woolley, Gregory P. Nordin
High Density 3d Printed Microfluidic Valves, Pumps, And Multiplexers, Hua Gong, Adam T. Woolley, Gregory P. Nordin
Faculty Publications
In this paper we demonstrate that 3D printing with a Digital Light Processor stereolithographic (DLP-SLA) 3D printer can be used to create high density microfluidic devices with active components such as valves and pumps. Leveraging our previous work on optical formulation of inexpensive resins (RSC Adv. 5, 106621, 2015), we demonstrate valves with only 10% of the volume of our original 3D printed valves (Biomicrofluidics 9, 016501, 2015), which were already the smallest that have been reported. Moreover, we show that inclusion of a thermal initiator in the resin formulation along with a post-print bake can dramatically improve the durability …
Ray-Based Statistical Propagation Modeling For Indoor Corridor Scenarios At 15 Ghz, Qi Wang, Bo Ai, David W. Matolak, Ruisi He, Xin Zhou
Ray-Based Statistical Propagation Modeling For Indoor Corridor Scenarios At 15 Ghz, Qi Wang, Bo Ai, David W. Matolak, Ruisi He, Xin Zhou
Faculty Publications
According to the demands for fifth-generation (5G) communication systems, high frequency bands (above 6 GHz) need to be adopted to provide additional spectrum. This paper investigates the characteristics of indoor corridor channels at 15 GHz. Channel measurements with a vector network analyzer in two corridors were conducted. Based on a ray-optical approach, a deterministic channel model covering both antenna and propagation characteristic is presented. The channel model is evaluated by comparing simulated results of received power and root mean square delay spread with the corresponding measurements. By removing the impact of directional antennas from the transmitter and receiver, a path …
Efficacy Of Physical Layer Preamble Manipulation For Ieee 802.11a/Ac, Benjamin W. Ramsey, Jonathan D. Fuller, Christopher W. Badenhop
Efficacy Of Physical Layer Preamble Manipulation For Ieee 802.11a/Ac, Benjamin W. Ramsey, Jonathan D. Fuller, Christopher W. Badenhop
Faculty Publications
Wireless physical layer manipulation is a recently discovered technique for selective packet obfuscation. This process exploits the unique and proprietary nature of transceiver designs rather than manufacturing imperfections. To date, preamble manipulation has only successfully been demonstrated on low data rate transceivers operating in the2.4 GHz band. This Letter investigates the effectiveness of preamble manipulation on common 5 GHz IEEE 802.11a and IEEE 802.11ac wireless transceivers for the first time. Herein it is demonstrated that the preamble short training sequence length can be manipulated to discern among the six transceiver designs under test with greater than 99% accuracy using fewer …
Improved Sensitivity Mems Cantilever Sensor For Terahertz Photoacoustic Spectroscopy, Ronald A. Coutu Jr., Ivan R. Medvedev, Douglas T. Petkie
Improved Sensitivity Mems Cantilever Sensor For Terahertz Photoacoustic Spectroscopy, Ronald A. Coutu Jr., Ivan R. Medvedev, Douglas T. Petkie
Faculty Publications
In this paper, a microelectromechanical system (MEMS) cantilever sensor was designed, modeled and fabricated to measure the terahertz (THz) radiation induced photoacoustic (PA) response of gases under low vacuum conditions. This work vastly improves cantilever sensitivity over previous efforts, by reducing internal beam stresses, minimizing out of plane beam curvature and optimizing beam damping. In addition, fabrication yield was improved by approximately 50% by filleting the cantilever’s anchor and free end to help reduce high stress areas that occurred during device fabrication and processing. All of the cantilever sensors were fabricated using silicon-on-insulator (SOI) wafers and tested in a custom …
Reduced Haemodynamic Coupling And Exercise Are Associated With Vascular Stiffening In Pulmonary Arterial Hypertension, Alessandro Bellofiore, Eric Dinges, Robert Naeije, Hamorabi Mkrdichian, Lauren Beussink-Nelson, Melissa Bailey, Michael Cuttica, Ranya Sweis, James Runo, Jon Keevil, Christopher Francois, Sanjiv Shah, Naomi Chesler
Reduced Haemodynamic Coupling And Exercise Are Associated With Vascular Stiffening In Pulmonary Arterial Hypertension, Alessandro Bellofiore, Eric Dinges, Robert Naeije, Hamorabi Mkrdichian, Lauren Beussink-Nelson, Melissa Bailey, Michael Cuttica, Ranya Sweis, James Runo, Jon Keevil, Christopher Francois, Sanjiv Shah, Naomi Chesler
Faculty Publications
Inadequate right ventricular (RV) and pulmonary arterial (PA) functional responses to exercise are important yet poorly understood features of pulmonary arterial hypertension (PAH). This study combined invasive catheterisation with echocardiography to assess RV afterload, RV function and ventricular–vascular coupling in subjects with PAH.
Fusion Of Renewable Ring Resonator Lasers And Ultrafast Laser Inscribed Photonic Waveguides, Hengky Chandrahalim, Stephen C. Rand, Xudong Fan
Fusion Of Renewable Ring Resonator Lasers And Ultrafast Laser Inscribed Photonic Waveguides, Hengky Chandrahalim, Stephen C. Rand, Xudong Fan
Faculty Publications
We demonstrated the monolithic integration of reusable and wavelength reconfigurable ring resonator lasers and waveguides of arbitrary shapes to out-couple and guide laser emission on the same fused-silica chip. The ring resonator hosts were patterned by a single-mask standard lithography, whereas the waveguides were inscribed in the proximity of the ring resonator by using 3-dimensional femtosecond laser inscription technology. Reusability of the integrated ring resonator – waveguide system was examined by depositing, removing, and re-depositing dye-doped SU-8 solid polymer, SU-8 liquid polymer, and liquid solvent (toluene). The wavelength reconfigurability was validated by employing Rhodamine 6G (R6G) and 3,3′-Diethyloxacarbocyanine iodide (CY3) …
Unequal A Priori Probability Multiple Hypothesis Testing In Space Domain Awareness With The Space Surveillance Telescope, Tyler J. Hardy, Stephen C. Cain, Travis F. Blake
Unequal A Priori Probability Multiple Hypothesis Testing In Space Domain Awareness With The Space Surveillance Telescope, Tyler J. Hardy, Stephen C. Cain, Travis F. Blake
Faculty Publications
This paper investigates the ability to improve Space Domain Awareness (SDA) by increasing the number of detectable Resident Space Objects (RSOs) from space surveillance sensors. With matched filter based techniques, the expected impulse response, or Point Spread Function (PSF), is compared against the received data. In the situation where the images are spatially undersampled, the modeled PSF may not match the received data if the RSO does not fall in the center of the pixel. This aliasing can be accounted for with a Multiple Hypothesis Test (MHT). Previously, proposed MHTs have implemented a test with an equal a priori prior …