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At least 757 records · Page 42
All sourcesNASA NTRSDOE OSTI
NASA NTRS2020

A Method for Correlating Forward-Looking Remote Sensor Measurements with In-Situ Measurements on Flying Platforms

A method is described for correlating measurements from a forward looking remote sensor with measurements made by in-situ instruments installed on the same flying platform. This method assumes that remote measurements are made within a volume of space in advance of the aircraft and that in-situ measurements provide representative values for discrete segments along the flight path. This correlation method can be applied to multiple sensors and makes no assumptions about the type of remote sensor or in-situ instrument, nor what either measures. It may be applied to recorded data during post-flight analysis based on known 4-D location (geospacial position and time) measurements.

Justin K. Strickland↗
NASA NTRS2002

Development and Design of a Zero-G Liquid Quantity Gauge for a Solar Thermal Vehicle

The development and design of a cryogenic liquid quantity gauge for zero-g applications is described. The gauge, named the Compression Mass Gauge (CMG), operates on the principle of slightly changing the volume of the tank by an oscillating bellows. The resulting pressure change is measured and used to predict the volume of vapor in the tank, from which the volume of liquid is computed. For each gauging instance, pressures are measured for several different bellows frequencies to enable minor real-gas effects to be quantified and thereby to obtain a gauging accuracy of +/- 1% of tank volume. Southwest Research Institute (Tm) and NASA-GRC (Glenn Research Center) have developed several previous breadboard and engineering development gauges and tested them in cryogenic hydrogen and nitrogen to establish the gauge capabilities, to resolve several design issues, and to formulate data processing algorithms. The CMG has been selected by NASA's Future X program for a flight demonstration on the USAF (United States Air Force) / Boeing Solar Thermal Vehicle Space Experiment (SOTVSE). This paper reviews the design trade studies needed to satisfy the SOTVSE limitations on CMG power, volume, and mass, and describes the mechanical design of the CMG.

Dodge, Franklin T.↗
NASA NTRS2002

Development and Design of Zero-g Liquid Quantity Gauge for Solar Thermal Vehicle

The development and design of a cryogenic liquid quantity gauge for zero-gravity (zero-g) applications are described. The gauge, named the compression mass gauge (CMG), operates on the principle of slightly changing the volume of the tank by an oscillating bellows. The resulting pressure change is measured and used to predict the volume of vapor in the tank, from which the volume of liquid is computed. For each gauging instance, pressures are measured for several different bellows frequencies to enable minor real-gas effects to be quantified and thereby to obtain a gauging accuracy of 11 percent of tank volume. The CMG has been selected by NASA's Future-X program for a flight demonstration on the United States Air Force-Boeing Solar Orbit Transfer Vehicle Space Experiment (SOTVSE). This report reviews the design trade studies needed for the CMG to satisfy the SOTVSE limitations on its power, volume, and mass and also describes the mechanical design of the CMG.

Dodge, Franklin T.↗
DOE OSTI2024

Impact of property covariance on cluster weak lensing scaling relations

ABSTRACT We present an investigation into a hitherto unexplored systematic that affects the accuracy of galaxy cluster mass estimates with weak gravitational lensing. Specifically, we study the covariance between the weak lensing signal, ΔΣ, and the ‘true’ cluster galaxy number count, Ngal, as measured within a spherical volume that is void of projection effects. By quantifying the impact of this covariance on mass calibration, this work reveals a significant source of systematic uncertainty. Using the MDPL2 simulation with galaxies traced by the SAGE semi-analytic model, we measure the intrinsic property covariance between these observables within the three-dimensional vicinity of the cluster, spanning a range of dynamical mass and redshift values relevant for optical cluster surveys. Our results reveal a negative covariance at small radial scales (R ≲ R200c) and a null covariance at large scales (R ≳ R200c) across most mass and redshift bins. We also find that this covariance results in a $2{\!-\!}3~{{\ \rm per\ cent}}$ bias in the halo mass estimates in most bins. Furthermore, by modelling Ngal and ΔΣ as multi-(log)-linear equations of secondary halo properties, we provide a quantitative explanation for the physical origin of the negative covariance at small scales. Specifically, we demonstrate that the Ngal–ΔΣ covariance can be explained by the secondary properties of haloes that probe their formation history. We attribute the difference between our results and the positive bias seen in other works with (mock)-cluster finders to projection effects. These findings highlight the importance of accounting for the covariance between observables in cluster mass estimation, which is crucial for obtaining accurate constraints on cosmological parameters.

Astronomy & Astrophysics↗
DOE OSTI2020

National Ignition Campaign Data Analysis by an ICF Outsider

A simple DT burn model, with no alpha-particle warming feedback, using a combination of ICF inputs and the measured ion temperature, T, volume compression, C, ablator velocity, v, and burn width time, Δt, can reproduce the national-ignition campaign (NIC) fusion yields with a rms percent difference of ~40%. Analysis suggestion the fusion-yield reproducibility of NIC events with nominally identically measured T, C, v, and Δt is <30%. The highest fusion yields, at a fixed laser energy are obtained with depleted-uranium (DU) hohlraums and high-density carbon (HDC) ablators. Small diameter fit tubes (≤5 μm) enhance fusion yields by an average of 26±15% relative to 10-μm diameter fit tubes. A dependence of fusion yield on the diameter of the capsule relative to the diameter of the hohlraum is inferred for fixed T, C, v, and Δt. No evidence of conditions close to ignition, or alpha-particle warming is found in the existing NIC data with LEH< 2MJ. To obtain a predictive model for extrapolation proposes we map the T, C, and v into power laws as a function of LEH. The above mentioned extrapolatable model has a rms percent difference from the yields of the second half of the NIC of (56 ± 4)%. Higher (and significantly lower) DT temperatures are obtained with HDC ablators (and low-foot drives). The highest compressions are obtained via low-foot drives, but this does not compensate for the corresponding lower temperatures. An extrapolation of the presented model suggests significant alpha-particle heating at an LEH of ~5 MJ. It is hoped that others more familiar it the conditions needed for ignition will use to presented model to estimate the LEH required for ignition.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2022

Characterization of Infrequent Samples from the Concentration, Storage, and Transfer Facility: H-Area Diversion Box 1 (HDB-1) Sump Sample: January 25, 2022 Sample

Savannah River Remediation Engineering (SRR-E) requested that the Savannah River National Laboratory (SRNL) analyze the Concentration, Storage, and Transfer Facility (CSTF) samples from the following Tank Farm areas: the sump encasement, catch tank, drain cell, and waste tank annulus. In general, these CSTF samples will be analyzed on an infrequent basis and analyses will include detection for total beta/gamma, total alpha activities, density, free hydroxide, and pH measurements. This report presents characterization results for the H-Area diversion box 1 sump (HDB-1) January 2022 sample. The sample was slightly brown with a small amount of suspended fine particulates visually estimated to be less than 1% by volume. The results are measurements for total gamma, total alpha, total beta, density, free hydroxide, and pH.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS1990

Infrared spectroscopic detection of sulfur hexafluoride (SF6) in the lower stratosphere and upper troposphere

This paper reports the detection and identification of the unresolved SF6 nu-3 band Q branch at 947.9/cm in high-resolution solar occultation spectra of the lower stratosphere and upper troposphere, which was made from the analysis of data recorded on April 30 to May 1, 1985 by the spaceborne Atmospheric Trace Molecule Spectroscopy Fourier transform spectrometer as part of the Spacelab 3 mission. On the basis of SF6 line-by-line parameters obtained from the laboratory studies of Bobin et al. (1987) and Schatz and Hornig (1953), the measured absorption was analyzed to deduce SF6 volume mixing ratios in the altitude range 12-22 km. It was found that, in this altitude range, the SF6 volume mixing ratio is independent of altitude, with an average measured value of 1.42 parts per trillion by volume (pptv) at 31 deg N latitude.

Rinsland, C. P.↗
NASA NTRS1985

Plasma volume methodology: Evans blue, hemoglobin-hematocrit, and mass density transformations

Methods for measuring absolute levels and changes in plasma volume are presented along with derivations of pertinent equations. Reduction in variability of the Evans blue dye dilution technique using chromatographic column purification suggests that the day-to-day variability in the plasma volume in humans is less than + or - 20 m1. Mass density determination using the mechanical-oscillator technique provides a method for measuring vascular fluid shifts continuously for assessing the density of the filtrate, and for quantifying movements of protein across microvascular walls. Equations for the calculation of volume and density of shifted fluid are presented.

Greenleaf, J. E.↗
NASA NTRS1986

Laser sounding of instantaneous and mean speed of wind using correlation method

The correlation methods for laser sounding of wind speed are based on mutual processing of lidar signals scattered from several spatially separated volumes at each altitude investigated. The time of atmospheric aerosol transport between the scattering volumes estimated by the position of maximum of the mutual correlation function is the measure of corresponding wind speed. In this case the distance between the scattering volumes (the measuring base), defining the time of aerosol movement through the measuring base also determines the lidar possibilities for measuring the instantaneous (during the time interval of several seconds) or the mean wind speed (some minutes). Based on the experimental investigations performed using two lidars, these possibilites are analyzed.

Zuev, V. E.↗
DOE OSTI2020

Second ARM Aerosol Chemical Speciation Monitor Users’ Meeting Report

The aerosol chemical speciation monitor (ACSM) was developed to adapt the technology of the aerosol mass spectrometer (AMS) to routine, long-term, standalone monitoring. The calculation of particulate mass concentration from ACSM data requires the measurement of the response of the instrument to aerosol of specific size and composition as well as assumptions about the instrument response based on laboratory measurements and field experience acquired over more than two decades of operation of AMS and a decade of operation of the ACSM. Three parameters in the concentration calculations that are particularly important are the NO3 response factor (RFNO3), relative ionization efficiency (RIE), and the collection efficiency (CE). The values of RFNO3 and RIEs are determined from calibration, however the jump calibration method previously used in calibration can result in errors in the RIE for sulfate. This has been corrected by implementing a continuous calibration method. The default collection efficiency is 0.5. This has been shown to result in mass loadings that do not agree with mass determinations from other instruments because of effects of composition on the vaporization of the particles. The previous work of investigators addressing this issue is discussed. After preliminary work on ACSM and scanning mobility particle sizer (SMPS) data from the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) user facility Southern Great Plains (SGP) observatory collected in late 2016 and 2017 produced a parameterization of composition dependent collection efficiency very different from the results of previous studies, SMPS data were examined and we determined that there was significant mass that the instrument did not capture because the particles with diameters larger than 465 nm are not counted by this instrument. Data for the ultra-high-sensitivity aerosol spectrometer (UHSAS), SMPS, and ACSM are available for nearly all of 2019. The data from UHSAS and SMPS collected in 2019 were compared. We found that the UHSAS data has particle counts and total volumes significantly less than measured by the condensation particle counter (CPC) and SMPS. The SMPS data were extended by fitting the average volume distribution with a log normal curve and using this relationship to estimate a mass value for the SMPS over extended diameter range. The extended SMPS mass values result in a CDCE parameterization that is in better agreement with the results of other investigators, but is still different from other formulations. The working group recommends that the ACSM data be processed with a collective efficiency (CE)=1, that this be documented clearly in the metadata, and the use of the default CE of 0.5 or a formulation of composition-dependent collection efficiencies (CDCE) chosen by the user should be implemented based on the ammonium nitrate mass fraction. This is clearly necessary for the wintertime SGP ACSM data because of the high nitrate concentrations.

47 OTHER INSTRUMENTATION↗
DOE OSTI2026

High-throughput small-angle X-ray scattering reveals effective structure factor transitions linked to high-concentration antibody viscosity

High-concentration monoclonal antibody (mAb) formulations are often constrained by elevated viscosity, largely driven by protein–protein interactions, which complicates manufacturing and limits subcutaneous delivery. Early viscosity risk assessment is essential during discovery, yet traditional measurements require large sample volumes, and lack high-throughput capability. Here, we develop a high-throughput small-angle X-ray scattering (SAXS) protocol to detect mAb self-association at dilute concentrations, enabling early predictive insights into high-concentration viscosity. Synchrotron SAXS measurements were conducted for 21 mAbs formulated in a histidine buffer at pH 6.0. An initial subset of 10 mAbs analyzed across 1–150 mg/mL revealed that effective structure factor transitions in the low-q region, indicative of interparticle interactions, consistently emerged below 25 mg/mL. Subsequently, 11 additional mAbs were analyzed at 1–25 mg/mL using automated liquid handling and flow cells to enable high-throughput screening. High-viscosity mAbs exhibited detectable low-q upturns at concentrations ≤10 mg/mL, whereas low-viscosity mAbs showed downturns. A classification criterion based on effective structure factor transitions accurately classified all high- and low-viscosity mAbs at 150 mg/mL, offering a scalable, sample-efficient alternative to conventional methods. These results extend recent findings on the concentration-dependent sensitivity of SAXS to short-range attractions, demonstrating that they can emerge at lower concentrations than previously reported. This study presents the most comprehensive and diverse SAXS dataset for mAbs reported to date within a single formulation, providing a valuable resource for developing and validating coarse-grained models that can more accurately capture intermolecular interactions governing high-concentration solution behavior, thereby enabling rational antibody engineering and improved developability.

36 MATERIALS SCIENCE↗
NASA NTRS1999

Noninvasive assessment of left atrial maximum dP/dt by a combination of transmitral and pulmonary venous flow

OBJECTIVES: The study assessed whether hemodynamic parameters of left atrial (LA) systolic function could be estimated noninvasively using Doppler echocardiography. BACKGROUND: Left atrial systolic function is an important aspect of cardiac function. Doppler echocardiography can measure changes in LA volume, but has not been shown to relate to hemodynamic parameters such as the maximal value of the first derivative of the pressure (LA dP/dt(max)). METHODS: Eighteen patients in sinus rhythm were studied immediately before and after open heart surgery using simultaneous LA pressure measurements and intraoperative transesophageal echocardiography. Left atrial pressure was measured with a micromanometer catheter, and LA dP/dt(max) during atrial contraction was obtained. Transmitral and pulmonary venous flow were recorded by pulsed Doppler echocardiography. Peak velocity, and mean acceleration and deceleration, and the time-velocity integral of each flow during atrial contraction was measured. The initial eight patients served as the study group to derive a multilinear regression equation to estimate LA dP/dt(max) from Doppler parameters, and the latter 10 patients served as the test group to validate the equation. A previously validated numeric model was used to confirm these results. RESULTS: In the study group, LA dP/dt(max) showed a linear relation with LA pressure before atrial contraction (r = 0.80, p < 0.005), confirming the presence of the Frank-Starling mechanism in the LA. Among transmitral flow parameters, mean acceleration showed the strongest correlation with LA dP/dt(max) (r = 0.78, p < 0.001). Among pulmonary venous flow parameters, no single parameter was sufficient to estimate LA dP/dt(max) with an r2 > 0.30. By stepwise and multiple linear regression analysis, LA dP/dt(max) was best described as follows: LA dP/dt(max) = 0.1 M-AC +/- 1.8 P-V - 4.1; r = 0.88, p < 0.0001, where M-AC is the mean acceleration of transmitral flow and P-V is the peak velocity of pulmonary venous flow during atrial contraction. This equation was tested in the latter 10 patients of the test group. Predicted and measured LA dP/dt(max) correlated well (r = 0.90, p < 0.0001). Numerical simulation verified that this relationship held across a wide range of atrial elastance, ventricular relaxation and systolic function, with LA dP/dt(max) predicted by the above equation with r = 0.94. CONCLUSIONS: A combination of transmitral and pulmonary venous flow parameters can provide a hemodynamic assessment of LA systolic function.

NASA Discipline Cardiopulmonary↗
NASA NTRS2013

Miniature Sensor Probe for O2, CO2, and H2O Monitoring in Portable Life Support Systems

A miniature sensor probe, composed of four sensors which monitor the partial pressure of O2, CO2, H2O, and temperature, designed to operate in the portable life support system (PLSS), has been demonstrated. The probe provides an important advantage over existing technology in that it is able to operate reliably while wet. These luminescence-based fiber optic sensors consist of an indicator chemistry immobilized in a polymeric film, whose emission lifetime undergoes a strong change upon a reversible interaction with the target gas. Each sensor includes chemistry specifically sensitive to one target parameter. All four sensors are based on indicator chemistries that include luminescent dyes from the same chemical family, and therefore exhibit similar photochemical properties, which allow performing measurements of all the sensors by a single, compact, low-power optoelectronic unit remotely connected to the sensors by an electromagnetic interference-proof optical fiber cable. For space systems, using these miniature sensor elements with remote optoelectronics provides unmatched design flexibility for measurements in highly constrained volume systems such as the PLSS. A 10 mm diameter and 15 mm length prototype multiparameter probe was designed, fabricated, tested, and demonstrated over a wide operational range of gas concentration, humidity, and temperature relevant to operation in the PLSS. The sensors were evaluated for measurement range, precision, accuracy, and response time in temperatures ranging from 50 aF-150 aF and relative humidity from dry to 100% RH. Operation of the sensors in water condensation conditions was demonstrated wherein the sensors not only tolerated liquid water but actually operated while wet.

Delgado, Jesus↗
NASA NTRS1998

Soot Formation in Laminar Premixed Methane/Oxygen Flames at Atmospheric Pressure

Flame structure and soot formation were studied within soot-containing laminar premixed mc1hane/oxygen flames at atmospheric pressure. The following measurements were made: soot volume fractions by laser extinction, soot temperatures by multiline emission, gas temperatures (where soot was absent) by corrected fine-wire thermocouples, soot structure by thermophoretic sampling and transmission electron microscope (TEM), major gas species concentrations by sampling and gas chromatography, and gas velocities by laser velocimetry. Present measurements of gas species concentrations were in reasonably good agreement with earlier measurements due to Ramer et al. as well as predictions based on the detailed mechanisms of Frenklach and co-workers and Leung and Lindstedt: the predictions also suggest that H atom concentrations are in local thermodynamic equilibrium throughout the soot formation region. Using this information, it was found that measured soot surface growth rates could be correlated successfully by predictions based on the hydrogen-abstraction/carbon-addition (HACA) mechanisms of both Frenklach and co-workers and Colket and Hall, extending an earlier assessment of these mechanisms for premixed ethylene/air flames to conditions having larger H/C ratios and acetylene concentrations. Measured primary soot particle nucleation rates were somewhat lower than the earlier observations for laminar premixed ethylene/air flames and were significantly lower than corresponding rates in laminar diffusion flames. for reasons that still must be explained.

Xu, F.↗
NASA NTRS2001

Soot Formation in Laminar Premixed Methane/Oxygen Flames at Atmospheric Pressure

Flame structure and soot formation were studied within soot-containing laminar premixed methanefoxygen flames at atmospheric pressure. The following measurements were made: soot volume fractions by laser extinction, soot temperatures by multiline emission, gas temperatures (where soot was absent) by corrected fine-wire thermocouples, soot structure by thermophoretic sampling and transmission electron microscope (TEM), major gas species concentrations by sampling and gas chromatography, and gas velocities by laser velocimetry. Present measurements of gas species concentrations were in reasonably good agreement with earlier measurements due to Ramer et al. as well as predictions based on the detailed mechanisms of Frenklach and co-workers and Leung and Lindstedt; the predictions also suggest that H atom concentrations are in local thermodynamic equilibrium throughout the soot formation region. Using this information, it was found that measured soot surface growth rates could be correlated successfully by predictions based on the hydrogenabstraction/carbon-addition (HACA) mechanisms of both Frenklach and co-workers and Colket and Hall, extending an earlier assessment of these mechanisms for premixed ethylene/air flames to conditions having larger H/C ratios and acetylene concentrations. Measured primary soot particle nucleation rates were somewhat lower than the earlier observations for laminar premixed ethylene/air flames and were significantly lower than corresponding rates in laminar diffusion flames, for reasons that still must be explained.

Xu, F.↗
NASA NTRS1984

Acoustic measurements of a full-scale rotor with four tip shapes. Volume 2: Appendices C, D, E and F

A full scale helicopter with four different blade tip geometries is tested in a 40- by 80-foot wind tunnel. Performance, loads, and noise are measured. The four tip shapes tested were rectangular, tapered, swept, and swept/tapered. The noise data include measurements of the sound pressure levels in decibels dB, decibels adjusted dBA, and tone-corrected PNdB, for all of the conditions tested. Also included are the detailed measurements, 1/3 octave spectra and time histories for some selected data, and plots of dBA as function of test condition. Some performance measurements are included to aid interpretation of the noise data.

Mosher, M.↗
DOE OSTI2020

Electron spin resonance spectroscopy with femtoliter detection volume

We report electron spin resonance measurements of donors in silicon at millikelvin temperatures using a superconducting LC planar micro-resonator and a Josephson parametric amplifier. The resonator includes a nanowire inductor, defining a femtoliter detection volume. Due to strain in the substrate, the donor resonance lines are heavily broadened. In this work, single-spin to photon coupling strengths up to ~ 3 kHz are observed. The single shot sensitivity is 120 ± 24 spins/Hahn echo, corresponding to ≈ 12 ± 3 spins / Hz for repeated acquisition.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS1999

System identification of closed-loop cardiovascular control mechanisms: diabetic autonomic neuropathy

We applied cardiovascular system identification (CSI) to characterize closed-loop cardiovascular regulation in patients with diabetic autonomic neuropathy (DAN). The CSI method quantitatively analyzes beat-to-beat fluctuations in noninvasively measured heart rate, arterial blood pressure (ABP), and instantaneous lung volume (ILV) to characterize four physiological coupling mechanisms, two of which are autonomically mediated (the heart rate baroreflex and the coupling of respiration, measured in terms of ILV, to heart rate) and two of which are mechanically mediated (the coupling of ventricular contraction to the generation of the ABP wavelet and the coupling of respiration to ABP). We studied 37 control and 60 diabetic subjects who were classified as having minimal, moderate, or severe DAN on the basis of standard autonomic tests. The autonomically mediated couplings progressively decreased with increasing severity of DAN, whereas the mechanically mediated couplings were essentially unchanged. CSI identified differences between the minimal DAN and control groups, which were indistinguishable based on the standard autonomic tests. CSI may provide a powerful tool for assessing DAN.

Non-NASA Center↗