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Articles 121 - 150 of 1603

Full-Text Articles in Mechanical Engineering

Comparing Mathematical And Heuristic Approaches For Scientific Data Analysis, Aparna Varde, Shuhui Ma, Mohammed Maniruzzaman, David Brown, Elke Rundensteiner, Richard Sisson Dec 2015

Comparing Mathematical And Heuristic Approaches For Scientific Data Analysis, Aparna Varde, Shuhui Ma, Mohammed Maniruzzaman, David Brown, Elke Rundensteiner, Richard Sisson

David C. Brown

Scientific data is often analyzed in the context of domain-specific problems, for example, failure diagnostics, predictive analysis, and computational estimation. These problems can be solved using approaches such as mathematical models or heuristic methods. In this paper we compare a heuristic approach based on mining stored data with a mathematical approach based on applying state-of-the-art formulae to solve an estimation problem. The goal is to estimate results of scientific experiments given their input conditions. We present a comparative study based on sample space, time complexity, and data storage with respect to a real application in materials science. Performance evaluation with …


U.S. Billion-Ton Update: Biomass Supply For A Bioenergy And Bioproducts Industry, Robert D. Perlack, Laurence M. Eaton, Anthony F. Turhollow Jr., Matt H. Langholtz, Craig C. Brandt, Mark E. Downing, Robin L. Graham, Lynn L. Wright, Jacob M. Kavkewitz, Anna M. Shamey, Richard G. Nelson, Bryce J. Stokes, William L. Rooney, David J. Muth Jr., J. Richard Hess, Jared M. Abodeely, Chad Hellwinckel, Danial De La Torre Ugarte, Daniel C. Yoder, James P. Lyon, Timothy G. Rials, Timothy A. Volk, Thomas S. Buchholz, Lawrence P. Abrahamson, Robert P. Anex, Thomas B. Voigt, William Berguson, Don E. Riemenschneider, Douglas Karlen, Jane M. F. Johnson, Robert B. Mitchell, Kenneth P. Vogel, Edward P. Richard Jr., John Tatarko, Larry E. Wagner, Kenneth E. Skog, Patricia K. Lebow, Dennis P. Dykstra, Marilyn A. Buford, Patrick D. Miles, D. Andrew Scott, James H. Perdue, Robert B. Rummer, Jamie Barbour, John A. Stanturf, David B. Mckeever, Ronald S. Zalesny Jr., Edmund A. Gee, P. Daniel Cassidy, David Lightle Dec 2015

U.S. Billion-Ton Update: Biomass Supply For A Bioenergy And Bioproducts Industry, Robert D. Perlack, Laurence M. Eaton, Anthony F. Turhollow Jr., Matt H. Langholtz, Craig C. Brandt, Mark E. Downing, Robin L. Graham, Lynn L. Wright, Jacob M. Kavkewitz, Anna M. Shamey, Richard G. Nelson, Bryce J. Stokes, William L. Rooney, David J. Muth Jr., J. Richard Hess, Jared M. Abodeely, Chad Hellwinckel, Danial De La Torre Ugarte, Daniel C. Yoder, James P. Lyon, Timothy G. Rials, Timothy A. Volk, Thomas S. Buchholz, Lawrence P. Abrahamson, Robert P. Anex, Thomas B. Voigt, William Berguson, Don E. Riemenschneider, Douglas Karlen, Jane M. F. Johnson, Robert B. Mitchell, Kenneth P. Vogel, Edward P. Richard Jr., John Tatarko, Larry E. Wagner, Kenneth E. Skog, Patricia K. Lebow, Dennis P. Dykstra, Marilyn A. Buford, Patrick D. Miles, D. Andrew Scott, James H. Perdue, Robert B. Rummer, Jamie Barbour, John A. Stanturf, David B. Mckeever, Ronald S. Zalesny Jr., Edmund A. Gee, P. Daniel Cassidy, David Lightle

Douglas L Karlen

The Report, Biomass as Feedstock for a Bioenergy and Bioproducts Industry: The Technical Feasibility of a Billion-Ton Annual Supply (generally referred to as the Billion-Ton Study or 2005 BTS), was an estimate of “potential” biomass within the contiguous United States based on numerous assumptions about current and future inventory and production capacity, availability, and technology. In the 2005 BTS, a strategic analysis was undertaken to determine if U.S. agriculture and forest resources have the capability to potentially produce at least one billion dry tons of biomass annually, in a sustainable manner—enough to displace approximately 30% of the country’s present petroleum …


Probing The Roles Of Polymeric Separators In Lithium-Ion Battery Capacity Fade At Elevated Temperatures, Jianchao Chen, Yongda Yan, Tao Sun, Yue Qi, Xiaodong Li Dec 2015

Probing The Roles Of Polymeric Separators In Lithium-Ion Battery Capacity Fade At Elevated Temperatures, Jianchao Chen, Yongda Yan, Tao Sun, Yue Qi, Xiaodong Li

Xiaodong Li

The high temperature mechanical property of separators is very important for safety of lithium-ion batteries. However, the mechanical integrity of polymeric separators in lithium-ion batteries at elevated temperatures is still not well characterized. In this paper, the temperature dependent micro-scale morphology change of PP (polypropylene)-PE (polyethylene)-PP sandwiched separators (Celgard 2325) was studied by in-situ high temperature surface imaging using an atomic force microscope (AFM) coupled with power spectral density (PSD) analysis and digital image correlation (DIC) technique. Both PSD and DIC analysis results show that the PP phase significantly closes its pores by means of dilation of the nanofibrils surrounding …


Probing The Roles Of Polymeric Separators In Lithium-Ion Battery Capacity Fade At Elevated Temperatures, Jianchao Chen, Yongda Yan, Tao Sun, Yue Qi, Xiaodong Li Dec 2015

Probing The Roles Of Polymeric Separators In Lithium-Ion Battery Capacity Fade At Elevated Temperatures, Jianchao Chen, Yongda Yan, Tao Sun, Yue Qi, Xiaodong Li

Xiaodong Li

The high temperature mechanical property of separators is very important for safety of lithium-ion batteries. However, the mechanical integrity of polymeric separators in lithium-ion batteries at elevated temperatures is still not well characterized. In this paper, the temperature dependent micro-scale morphology change of PP (polypropylene)-PE (polyethylene)-PP sandwiched separators (Celgard 2325) was studied by in-situ high temperature surface imaging using an atomic force microscope (AFM) coupled with power spectral density (PSD) analysis and digital image correlation (DIC) technique. Both PSD and DIC analysis results show that the PP phase significantly closes its pores by means of dilation of the nanofibrils surrounding …


A Platinum Nanowire Network As A Highly Effective Current Collector For Intermediate Temperature Solid Oxide Fuel Cells, Hanping Ding, Xingjian Xue Dec 2015

A Platinum Nanowire Network As A Highly Effective Current Collector For Intermediate Temperature Solid Oxide Fuel Cells, Hanping Ding, Xingjian Xue

Xingjian "Chris" Xue

We report the fabrication and evaluation of a platinum nanowire network as a highly efficient current collector for solid oxide fuel cells (SOFCs). The ink of carbon-black supported platinum nanoparticles was sprayed onto the cathode. After firing, the carbon black was oxidized and disappeared as carbon dioxide gas while the platinum nanoparticles connect with one another, forming a tree-branch-like nanowire network. The diameters of the nanowires range from 100 nm to 400 nm. Compared to a conventional platinum paste current collector, the polarization resistance of the PrBaCo2O5+δ (PBCO) cathode with a nanowire current collector was reduced …


A Platinum Nanowire Network As A Highly Effective Current Collector For Intermediate Temperature Solid Oxide Fuel Cells, Hanping Ding, Xingjian Xue Dec 2015

A Platinum Nanowire Network As A Highly Effective Current Collector For Intermediate Temperature Solid Oxide Fuel Cells, Hanping Ding, Xingjian Xue

Xingjian "Chris" Xue

We report the fabrication and evaluation of a platinum nanowire network as a highly efficient current collector for solid oxide fuel cells (SOFCs). The ink of carbon-black supported platinum nanoparticles was sprayed onto the cathode. After firing, the carbon black was oxidized and disappeared as carbon dioxide gas while the platinum nanoparticles connect with one another, forming a tree-branch-like nanowire network. The diameters of the nanowires range from 100 nm to 400 nm. Compared to a conventional platinum paste current collector, the polarization resistance of the PrBaCo2O5+δ (PBCO) cathode with a nanowire current collector was reduced by 44% at 650 …


Effectiveness Of Group Kickboxing As A Means To Improve Gait And Balance In Individuals With Ms, Kurt Jackson, Kimberly Edginton Bigelow, Christina Cooper, Harold L. Merriman Nov 2015

Effectiveness Of Group Kickboxing As A Means To Improve Gait And Balance In Individuals With Ms, Kurt Jackson, Kimberly Edginton Bigelow, Christina Cooper, Harold L. Merriman

Harold L. Merriman

In recent years, there has been a particular emphasis on identifying and delivering appropriate therapeutic interventions that address the significant balance and gait impairments that affect individuals with multiple sclerosis (MS). Group interventions implemented in community settings have been especially of interest, including tai chi classes. Recently, the authors conducted a preliminary study to examine whether group kick-boxing, which requires more vigorous movements, might be a feasible intervention. Initial findings showed promise and led the authors to pursue a more rigorous follow-up study, with the objective of determining whether a 5-week group kickboxing class improved clinical measures of balance and …


Metal Wear Detection Apparatus And Method Employing Microfluidic Electronic Device, Jiang Zhe, Li Du, Joan Carletta, Robert Veillette Nov 2015

Metal Wear Detection Apparatus And Method Employing Microfluidic Electronic Device, Jiang Zhe, Li Du, Joan Carletta, Robert Veillette

Robert Veillette

An apparatus and a method for detection of wear particles in a lubricant are disclosed. The apparatus includes a microfluidic device including a microchannel sized for a lubricant containing wear particles to pass therethrough and first and second electrodes extending into the microchannel. A detection system is coupled with the electrodes for detection of wear particles passing through the microchannel, based on a change in capacitance of the electrodes.


Inductive Coulter Counting: Detection And Differentiation Of Metal Wear Particles In Lubricant, Li Du, Jiang Zhe, Robert Veillette Nov 2015

Inductive Coulter Counting: Detection And Differentiation Of Metal Wear Particles In Lubricant, Li Du, Jiang Zhe, Robert Veillette

Robert Veillette

A device based on an inductive Coulter counting principle for detecting metal particles in lubrication oil is presented. The device detects the passage of ferrous and nonferrous particles by monitoring the inductance change in a coil. First, the sensing principle is demonstrated at the mesoscale using a solenoid. Next, a small planar coil suitable for use in a microscale device is tested. Static tests are conducted on the planar coil using iron and aluminum particles ranging from 80 to 500 µm. The testing results show that the coil can be used to detect and distinguish ferrous and nonferrous metal particles …


A Magnetic Coulter Counting Device For Wear Debris Detection In Lubrication, Li Du, Joan Carletta, Robert Veillette, Jiang Zhe Nov 2015

A Magnetic Coulter Counting Device For Wear Debris Detection In Lubrication, Li Du, Joan Carletta, Robert Veillette, Jiang Zhe

Robert Veillette

A device based on a magnetic Coulter counting principle to detect metal particles in lubrication oil is presented. The device detects the passage of ferrous and non ferrous particles by monitoring inductance change in a coil. First, the sensing principle is demonstrated at the mesoscale using a solenoid. Next, a microscale device is developed using a planar coil. The device is tested using iron and aluminum particles ranging from 100μm to 500μm. The testing results show the device is capable of detecting and distinguishing ferrous and non-ferrous metal particles in lubrication oil. The design concept demonstrated here can be extended …


Real-Time Monitoring Of Wear Debris In Lubrication Oil Using A Microfluidic Inductive Coulter Counting Device, Li Du, Jiang Zhe, Joan Carletta, Robert Veillette, Fred Choy Nov 2015

Real-Time Monitoring Of Wear Debris In Lubrication Oil Using A Microfluidic Inductive Coulter Counting Device, Li Du, Jiang Zhe, Joan Carletta, Robert Veillette, Fred Choy

Robert Veillette

A microfluidic device based on an inductive Coulter counting principle to detect metal wear particles in lubrication oil is presented. The device detects the passage of ferrous and nonferrous particles by monitoring the inductance change of an embedded coil. The device was tested using iron and copper particles ranging in size from 50 to 125 μm. The testing results have demonstrated that the device is capable of detecting and distinguishing ferrous and nonferrous metal particles in lubrication oil; such particles can be indicative of potential machine faults in rotating and reciprocating machinery.


Narrow-Linewidth Megahertz-Repetition-Rate Optical Parametric Oscillator For High-Speed Flow And Combustion Diagnostics, Naibo Jiang, Walter R. Lempert, Gary L. Switzer, Terrence R. Meyer, James R. Gord Nov 2015

Narrow-Linewidth Megahertz-Repetition-Rate Optical Parametric Oscillator For High-Speed Flow And Combustion Diagnostics, Naibo Jiang, Walter R. Lempert, Gary L. Switzer, Terrence R. Meyer, James R. Gord

Terrence R Meyer

We demonstrate the ability to generate ultra-high-frequency sequences of broadly wavelength-tunable, high-intensity laser pulses using a custom-built optical parametric oscillator pumped by the thirdharmonic output of a "burst-mode" Nd:YAG laser. Burst sequences consisting of 6-10 pulses separated in time by 6-10 Îs are obtained, with average total conversion efficiency from the 355 nm pump to the near-IR signal and idler wavelengths of 33%. Typical individual pulse output energy for the signal and idler beams is in the range of 4-6 mJ, limited by the available pump energy. Line narrowing is demonstrated by means of injection seeding the idler wave using …


Interference-Free Gas-Phase Thermometry At Elevated Pressure Using Hybrid Femtosecond/Picosecond Rotational Coherent Anti- Stokes Raman Scattering, Joseph D. Miller, Chloe Elizabeth Dedic, Sukesh Roy, James R. Gord, Terrence R. Meyer Nov 2015

Interference-Free Gas-Phase Thermometry At Elevated Pressure Using Hybrid Femtosecond/Picosecond Rotational Coherent Anti- Stokes Raman Scattering, Joseph D. Miller, Chloe Elizabeth Dedic, Sukesh Roy, James R. Gord, Terrence R. Meyer

Terrence R Meyer

Rotational-level-dependent dephasing rates and nonresonant background can lead to significant uncertainties in coherent anti-Stokes Raman scattering (CARS) thermometry under high-pressure, lowtemperature conditions if the gas composition is unknown. Hybrid femtosecond/picosecond rotational CARS is employed to minimize or eliminate the influence of collisions and nonresonant background for accurate, frequency-domain thermometry at elevated pressure. The ability to ignore these interferences and achieve thermometric errors of <5% is demonstrated for N2 and O2 at pressures up to 15 atm. Beyond 15 atm, the effects of collisions cannot be ignored but can be minimized using a short probe delay (~6.5 ps) after Raman excitation, …


Comparison Of Line-Peak And Line-Scanning Excitation In Two-Color Laser-Induced-Fluorescence Thermometry Of Oh, Stanislav Kostka, Sukesh Roy, Patrick J. Lakusta, Terrence R. Meyer, Michael W. Renfro, James R. Gord, Richard Branam Nov 2015

Comparison Of Line-Peak And Line-Scanning Excitation In Two-Color Laser-Induced-Fluorescence Thermometry Of Oh, Stanislav Kostka, Sukesh Roy, Patrick J. Lakusta, Terrence R. Meyer, Michael W. Renfro, James R. Gord, Richard Branam

Terrence R Meyer

Two-line laser-induced-fluorescence (LIF) thermometry is commonly employed to generate instantaneous planar maps of temperature in unsteady flames. The use of line scanning to extract the ratio of integrated intensities is less common because it precludes instantaneous measurements. Recent advances in the energy output of high-speed, ultraviolet, optical parameter oscillators have made possible the rapid scanning of molecular rovibrational transitions and, hence, the potential to extract information on gas-phase temperatures. In the current study, two-line OH LIF thermometry is performed in a wellcalibrated reacting flow for the purpose of comparing the relative accuracy of various line-pair selections from the literature and …


Laser Applications To Chemical, Security, And Environmental Analysis: Introduction To The Feature Issue, Terrence R. Meyer, Volker Ebert, Wolfgang Schade Nov 2015

Laser Applications To Chemical, Security, And Environmental Analysis: Introduction To The Feature Issue, Terrence R. Meyer, Volker Ebert, Wolfgang Schade

Terrence R Meyer

This Applied Optics feature issue on Laser Applications to Chemical, Security, and Environmental Analysis (LACSEA) highlights topics and papers presented at the LACSEA 2010 Twelfth Topical Meeting sponsored by the Optical Society of America.


Mhz-Rate Nitric Oxide Planar Laser-Induced Fluorescence Imaging In A Mach 10 Hypersonic Wind Tunnel, Naibo Jiang, Matthew Webster, Walter R. Lempert, Joseph D. Miller, Terrence R. Meyer, Christopher B. Ivey, Paul M. Danehy Nov 2015

Mhz-Rate Nitric Oxide Planar Laser-Induced Fluorescence Imaging In A Mach 10 Hypersonic Wind Tunnel, Naibo Jiang, Matthew Webster, Walter R. Lempert, Joseph D. Miller, Terrence R. Meyer, Christopher B. Ivey, Paul M. Danehy

Terrence R Meyer

Nitric oxide planar laser-induced fluorescence (NO PLIF) imaging at repetition rates as high as 1 MHz is demonstrated in the NASA Langley 31 in. Mach 10 hypersonic wind tunnel. Approximately 200 timecorrelated image sequences of between 10 and 20 individual frames were obtained over eight days of wind tunnel testing spanning two entries in March and September of 2009. The image sequences presented were obtained from the boundary layer of a 20° flat plate model, in which transition was induced using a variety of different shaped protuberances, including a cylinder and a triangle. The high-speed image sequences captured a variety …


Simultaneous High-Speed Measurement Of Temperature And Lifetime-Corrected Oh Laserinduced Fluorescence In Unsteady Flames, Terrence R. Meyer, Galen B. King, Matthew Glusenkamp, James R. Gord Nov 2015

Simultaneous High-Speed Measurement Of Temperature And Lifetime-Corrected Oh Laserinduced Fluorescence In Unsteady Flames, Terrence R. Meyer, Galen B. King, Matthew Glusenkamp, James R. Gord

Terrence R Meyer

A means of performing simultaneous, high-speed measurements of temperature and OH lifetime-corrected laser-induced fluorescence (LIF) for tracking unsteady flames has been developed and demonstrated. The system uses the frequency-doubled and frequency-tripled output beams of an 80 MHz mode-locked Ti:sapphire laser to achieve ultrashort laser pulses (order 2 ps) for Rayleigh-scattering thermometry at 460 nm and lifetime-corrected OH LIF at 306.5 nm, respectively. Simultaneous, high-speed measurements of temperature and OH number density enable studies of flame chemistry, heat release, and flame extinction in unsteady, strained flames where the local fluorescence-quenching environment is unknown.


Hybrid Femtosecond/Picosecond Coherent Anti-Stokes Raman Scattering For High-Speed Gas-Phase Thermometry, Joseph D. Miller, Mikhail N. Slipchenko, Terrence R. Meyer, Hans U. Stauffer, James R. Goird Nov 2015

Hybrid Femtosecond/Picosecond Coherent Anti-Stokes Raman Scattering For High-Speed Gas-Phase Thermometry, Joseph D. Miller, Mikhail N. Slipchenko, Terrence R. Meyer, Hans U. Stauffer, James R. Goird

Terrence R Meyer

We demonstrate hybrid femtosecond/picosecond (fs/ps) coherent anti-Stokes Raman scattering for high-speed thermometry in unsteady high-temperature flames, including successful comparisons with a time- and frequencyresolved theoretical model. After excitation of the N2 vibrational manifold with 100 fs broadband pump and Stokes beams, the Raman coherence is probed using a frequency-narrowed 2:5 ps probe beam that is time delayed to suppress the nonresonant background by 2 orders of magnitude. Experimental spectra were obtained at 500 Hz in steady and pulsed H2–air flames and exhibit a temperature precision of 2.2% and an accuracy of 3.3% up to 2400 K. Strategies for real-time gas-phase …


Probe-Pulse Optimization For Nonresonant Suppression In Hybrid Fs/Ps Coherent Anti-Stokes Raman Scattering At High Temperature, Joseph D. Miller, Mikhail N. Slipchenko, Terrence R. Meyer Nov 2015

Probe-Pulse Optimization For Nonresonant Suppression In Hybrid Fs/Ps Coherent Anti-Stokes Raman Scattering At High Temperature, Joseph D. Miller, Mikhail N. Slipchenko, Terrence R. Meyer

Terrence R Meyer

Hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (fs/ps CARS) offers accurate thermometry at kHz rates for combustion diagnostics. In high-temperature flames, selection of probe-pulse characteristics is key to simultaneously optimizing signal-to-nonresonant-background ratio, signal strength, and spectral resolution. We demonstrate a simple method for enhancing signal-to-nonresonant-background ratio by using a narrowband Lorentzian filter to generate a time-asymmetric probe pulse with full-width-half-maximum (FWHM) pulse width of only 240 fs. This allows detection within just 310 fs after the Raman excitation for eliminating nonresonant background while retaining 45% of the resonant signal at 2000 K. The narrow linewidth is comparable to that of a …


Single-Shot Gas-Phase Thermometry Using Purerotational Hybrid Femtosecond/Picosecond Coherent Anti-Stokes Raman Scattering, Joseph D. Miller, Sukesh Roy, Mikhail N. Slipchenko, James R. Gord, Terrence R. Meyer Nov 2015

Single-Shot Gas-Phase Thermometry Using Purerotational Hybrid Femtosecond/Picosecond Coherent Anti-Stokes Raman Scattering, Joseph D. Miller, Sukesh Roy, Mikhail N. Slipchenko, James R. Gord, Terrence R. Meyer

Terrence R Meyer

High-repetition-rate, single-laser-shot measurements are important for the investigation of unsteady flows where temperature and species concentrations can vary significantly. Here, we demonstrate singleshot, pure-rotational, hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (fs/ps RCARS) thermometry based on a kHz-rate fs laser source. Interferences that can affect nanosecond (ns) and ps CARS, such as nonresonant background and collisional dephasing, are eliminated by selecting an appropriate time delay between the 100-fs pump/Stokes pulses and the pulse-shaped 8.4-ps probe. A time- and frequency-domain theoretical model is introduced to account for rotational-level dependent collisional dephasing and indicates that the optimal probe-pulse time delay is 13.5 ps …


Fast-Framing Ballistic Imaging Of Velocity In An Aerated Spray, David Sedarsky, James Gord, Campbell Carter, Terrence R. Meyer, Mark Linne Nov 2015

Fast-Framing Ballistic Imaging Of Velocity In An Aerated Spray, David Sedarsky, James Gord, Campbell Carter, Terrence R. Meyer, Mark Linne

Terrence R Meyer

We describe further development of ballistic imaging adapted for the liquid core of an atomizing spray. To fully understand spray breakup dynamics, one must measure the velocity and acceleration vectors that describe the forces active in primary breakup. This information is inaccessible to most optical diagnostics, as the signal is occluded by strong scattering in the medium. Ballistic imaging mitigates this scattering noise, resolving clean shadowgram-type images of structures within the dense spray region. We demonstrate that velocity data can be extracted from ballistic images of a spray relevant to fuel-injection applications, by implementing a simple, targeted correlation method for …


Quantitative Time-Averaged Gas And Liquid Distributions Using X-Ray Fluorescence And Radiography In Atomizing Sprays, Christopher D. Radke, J. Patrick Mcmanamen, Alan L. Kastengren, Benjamin R. Halls, Terrence R. Meyer Nov 2015

Quantitative Time-Averaged Gas And Liquid Distributions Using X-Ray Fluorescence And Radiography In Atomizing Sprays, Christopher D. Radke, J. Patrick Mcmanamen, Alan L. Kastengren, Benjamin R. Halls, Terrence R. Meyer

Terrence R Meyer

A method for quantitative measurements of gas and liquid distributions is demonstrated using simultaneous x-ray fluorescence and radiography of both phases in an atomizing coaxial spray. Synchrotron radiation at 10.1 keV from the Advanced Photon Source at Argonne National Laboratory is used for x-ray fluorescence of argon gas and two tracer elements seeded into the liquid stream. Simultaneous time-resolved x-ray radiography combined with timeaveraged dual-tracer fluorescence measurements enabled corrections for reabsorption of x-ray fluorescence photons for accurate, line-of-sight averaged measurements of the distribution of the gas and liquid phases originating from the atomizing nozzle.


100-Ps-Pulse-Duration, 100-J Burst-Mode Laser For Khz–Mhz Flow Diagnostics, Sukesh Roy, Joseph D. Miller, Mikhail N. Slipchenko, Paul S. Hsu, Jason G. Mance, Terrence R. Meyer, James R. Gord Nov 2015

100-Ps-Pulse-Duration, 100-J Burst-Mode Laser For Khz–Mhz Flow Diagnostics, Sukesh Roy, Joseph D. Miller, Mikhail N. Slipchenko, Paul S. Hsu, Jason G. Mance, Terrence R. Meyer, James R. Gord

Terrence R Meyer

A high-speed, master-oscillator power-amplifier burst-mode laser with ∼100 ps pulse duration is demonstrated with output energy up to 110 J per burst at 1064 nm and second-harmonic conversion efficiency up to 67% in a KD*P crystal. The output energy is distributed across 100 to 10,000 sequential laser pulses, with 10 kHz to 1 MHz repetition rate, respectively, over 10 ms burst duration. The performance of the 100 ps burst-mode laser is evaluated and been found to compare favorably with that of a similar design that employs a conventional ∼8 ns pulse duration. The nearly transform-limited spectral bandwidth of 0.15 cm−1 …


Femtosecond Coherent Anti-Stokes Raman Scattering Measurement Of Gas Temperatures From Frequency-Spread Dephasing Of The Raman Coherence, Robert P. Lucht, Sukesh Roy, Terrence R. Meyer, James R. Gord Nov 2015

Femtosecond Coherent Anti-Stokes Raman Scattering Measurement Of Gas Temperatures From Frequency-Spread Dephasing Of The Raman Coherence, Robert P. Lucht, Sukesh Roy, Terrence R. Meyer, James R. Gord

Terrence R Meyer

Gas-phase temperatures and concentrations are measured from the magnitude and decay of the initial Raman coherence in femtosecond coherent anti-Stokes Raman scattering (CARS). A time-delayed probe beam is scattered from the Raman polarization induced by pump and Stokes beams to generate CARS signal; the dephasing rate of this initial coherence is determined by the temperature-sensitive frequency spread of the Raman transitions. Temperature is measured from the CARS signal decrease with increasing probe delay. Concentration is found from the ratio of the CARS and nonresonant background signals. Collision rates do not affect the determination of these quantities.


Effects Of Repetitive Pulsing On Multi-Khz Planar Laser-Induced Incandescence Imaging In Laminar And Turbulent Flames, James Bennett Michael, Prabhakar Venkateswaran, Christopher R. Shaddix, Terrence R. Meyer Nov 2015

Effects Of Repetitive Pulsing On Multi-Khz Planar Laser-Induced Incandescence Imaging In Laminar And Turbulent Flames, James Bennett Michael, Prabhakar Venkateswaran, Christopher R. Shaddix, Terrence R. Meyer

Terrence R Meyer

Planar laser-induced incandescence (LII) imaging is reported at repetition rates up to 100 kHz using a burst-mode laser system to enable studies of soot formation dynamics in highly turbulent flames. To quantify the accuracy and uncertainty of relative soot volume fraction measurements, the temporal evolution of the LII field in laminar and turbulent flames is examined at various laser operating conditions. Under high-speed repetitive probing, it is found that LII signals are sensitive to changes in soot physical characteristics when operating at high laser fluences within the soot vaporization regime. For these laser conditions, strong planar LII signals are observed …


Dual-Pump Vibrational/Rotational Femtosecond/ Picosecond Coherent Anti-Stokes Raman Scattering Temperature And Species Measurements, Chloe Elizabeth Dedic, Joseph D. Miller, Terrence R. Meyer Nov 2015

Dual-Pump Vibrational/Rotational Femtosecond/ Picosecond Coherent Anti-Stokes Raman Scattering Temperature And Species Measurements, Chloe Elizabeth Dedic, Joseph D. Miller, Terrence R. Meyer

Terrence R Meyer

A method for simultaneous ro-vibrational and pure-rotational hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (fs/ps CARS) is presented for multi-species detection and improved temperature sensitivity from room temperature to flame conditions. N2∕CH4 vibrational and N2∕O2∕H2 rotational Raman coherences are excited simultaneously using fs pump pulses at 660 and 798 nm, respectively, and a common fs Stokes pulse at 798 nm. A fourth narrowband 798 nm ps pulse probes all coherence states at a time delay that minimizes nonresonant background and the effects of collisions. The transition strength is concentration dependent, while the distribution among observed transitions is related to temperature through …


Micro-Optical Initiation Of Nanoenergetic Materials Using A Temporally Tailored Variable-Pulse-Width Laser, Mikhail N. Slipchenko, Clint E. Moody, Joseph D. Miller, Sukesh Roy, James R. Gord, Terrence R. Meyer Nov 2015

Micro-Optical Initiation Of Nanoenergetic Materials Using A Temporally Tailored Variable-Pulse-Width Laser, Mikhail N. Slipchenko, Clint E. Moody, Joseph D. Miller, Sukesh Roy, James R. Gord, Terrence R. Meyer

Terrence R Meyer

Nanoenergetic materials can provide a significant enhancement in the rate of energy release as compared with microscale materials. The energy-release rate is strongly dependent not only on the primary particle size but also on the level of agglomeration, which is of particular interest for the inclusion of nanoenergetics in practical systems where agglomeration is desired or difficult to avoid. Unlike studies of nanoparticles or nanometer-size aggregates, which can be conducted with ultrafast or nanosecond lasers assuming uniform heating, microscale aggregates of nanoparticles are more sensitive to the thermophysical time scale of the heating process. To allow control over the rate …


Quantitative Measurement Of Binary Liquid Distributions Using Multiple-Tracer X-Ray Fluorescence And Radiography, Benjamin R. Halls, Terrence R. Meyer, Alan L. Kastengren Nov 2015

Quantitative Measurement Of Binary Liquid Distributions Using Multiple-Tracer X-Ray Fluorescence And Radiography, Benjamin R. Halls, Terrence R. Meyer, Alan L. Kastengren

Terrence R Meyer

The complex geometry and large index-of-refraction gradients that occur near the point of impingement of binary liquid jets present a challenging environment for optical interrogation. A simultaneous quadruple-tracer x-ray fluorescence and line-of-sight radiography technique is proposed as a means of distinguishing and quantifying individual liquid component distributions prior to, during, and after jet impact. Two different pairs of fluorescence tracers are seeded into each liquid stream to maximize their attenuation ratio for reabsorption correction and differentiation of the two fluids during mixing. This approach for instantaneous correction of xray fluorescence reabsorption is compared with a more time-intensive approach of using …


100 Khz Thousand-Frame Burst-Mode Planar Imaging In Turbulent Flames, James B. Michael, Prabhakar Venkateswaran, Joseph D. Miller, Mikhail N. Slipchenko, James R. Gord, Sukesh Roy, Terrence R. Meyer Nov 2015

100 Khz Thousand-Frame Burst-Mode Planar Imaging In Turbulent Flames, James B. Michael, Prabhakar Venkateswaran, Joseph D. Miller, Mikhail N. Slipchenko, James R. Gord, Sukesh Roy, Terrence R. Meyer

Terrence R Meyer

High-repetition-rate, burst-mode lasers can achieve higher energies per pulse compared with continuously pulsed systems, but the relatively few number of laser pulses in each burst has limited the temporal dynamic range of measurements in unsteady flames. A fivefold increase in the range of timescales that can be resolved by burst-mode laser-based imaging systems is reported in this work by extending a hybrid diode- and flashlamp-pumped Nd:YAGbased amplifier system to nearly 1000 pulses at 100 kHz during a 10 ms burst. This enables an unprecedented burstmode temporal dynamic range to capture turbulent fluctuations from 0.1 to 50 kHz in flames of …


Spatially And Temporally Resolved Temperature And Shock-Speed Measurements Behind A Laser-Induced Blast Wave Of Energetic Nanoparticles, Sukesh Roy, Naibo Jiang, Han U. Stauffer, Jacob B. Schmidt, Waruna D. Kulatilaka, Terrence R. Meyer, Christopher E. Bunker, James R. Gord Nov 2015

Spatially And Temporally Resolved Temperature And Shock-Speed Measurements Behind A Laser-Induced Blast Wave Of Energetic Nanoparticles, Sukesh Roy, Naibo Jiang, Han U. Stauffer, Jacob B. Schmidt, Waruna D. Kulatilaka, Terrence R. Meyer, Christopher E. Bunker, James R. Gord

Terrence R Meyer

Spatially and temporally resolved temperature measurements behind an expanding blast wave are made using picosecond (ps) N2 coherent anti-Stokes Raman scattering (CARS) following laser flash heating of mixtures containing aluminum nanoparticles embedded in ammonium-nitrate oxidant. Production-front ps-CARS temperatures as high as 3600 ± 180 K-obtained for 50-nm-diameter commercially produced aluminum-nanoparticle samples-are observed. Time-resolved shadowgraph images of the evolving blast waves are also obtained to determine the shock-wave position and corresponding velocity. These results are compared with near-field blast-wave theory to extract relative rates of energy release for various particle diameters and passivating-layer compositions.