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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1999

Physiological response to submaximal isometric contractions of the paravertebral muscles

STUDY DESIGN: Brief (30-second) isometric trunk extensions at 5%, 20%, 40%, 60%, and 80% of maximal voluntary contraction (MVC) and 3 minutes of prolonged trunk extension (20% MVC) in erect position were studied in nine healthy male subjects. OBJECTIVES: To investigate the intercorrelation between intramuscular pressure and tissue oxygenation of the paravertebral muscles during submaximal isometric contractions and further, to evaluate paravertebral electromyogram and intramuscular pressure as indicators of force development. SUMMARY OF BACKGROUND DATA: Local physiologic responses to muscle contraction are incompletely understood. METHODS: Relative oxygenation was monitored with noninvasive near-infrared spectroscopy, intramuscular pressure was measured with a transducer-tipped catheter, and surface electromyogram was monitored at three recording sites. RESULTS: The root mean square amplitudes of the paravertebral electromyogram (L4, left and right; T12, right) and intramuscular pressure measured in the lumbar multifidus muscle at L4 increased with greater force development in a curvilinear manner. A significant decrease in the oxygenation of the lumbar paravertebral muscle in response to muscle contraction was found at an initial contraction level of 20% MVC. This corresponded to a paravertebral intramuscular pressure of 30-40 mm Hg. However, during prolonged trunk extension, no further decrease in tissue oxygenation was found compared with the tissue oxygenation level at the end of the brief contractions, indicating that homeostatic adjustments (mean blood pressure and heart rate) over time were sufficient to maintain paravertebral muscle oxygen levels. CONCLUSION: At a threshold intramuscular pressure of 30-40 mm Hg during muscle contraction, oxygenation in the paravertebral muscles is significantly reduced. The effect of further increase in intramuscular pressure on tissue oxygenation over time may be compensated for by an increase in blood pressure and heart rate. Surface electromyogram amplitudes and intramuscular pressure can be used as indicators of paravertebral muscle force.

NASA Center ARC↗
DOE OSTI2026

Skin CO 2 sniffing for wearable metabolic monitoring

CO 2 is a key physiological parameter used to assess hypoventilation and to estimate metabolic rates. However, current CO 2 monitoring relies on bulky breath-analysis systems that are impractical for continuous use in daily life. Here, we present a wearable on-skin gas-sniffing system that quantifies skin-emitted CO 2 and establishes its physiological relevance through direct correlation with exhaled CO 2 and metabolic rate. Participant studies demonstrate strong correlations between CO 2 flow rates from the skin and breath during both rest and exercise, with skin-emitted CO 2 approximately four orders of magnitude lower than exhaled CO 2 . Skin-emitted CO 2 also correlates with metabolic rate, suggesting its potential as a surrogate for breath-based indirect calorimetry. With its wearable form factor and physiological relevance, this skin gas sniffing system enables continuous, noninvasive metabolic monitoring and opens opportunities for studying skin gas exchange.

Kim, Seung-Rok [University of California, Berkeley↗
NASA NTRS2018

The Optoretinogram at 38

As early as 1980, Donald MacLeod coined the term "optoretinogram" to describe a change in the near-infrared reflectance of the retina following visual stimulation. The hope that such signals might exist was stimulated by an observation of a change in the infrared transmission of isolated toad retinae. This signal showed a time course of several seconds, much slower than the electroretinogram, and was thought to be related to some chemical step in the phototransduction cascade. During the early 1980's, we made several attempts to observe such signals in vivo in humans, without success. In the intervening decades, however, researchers have succeeded in observing what are now known as "intrinsic optical signals" or IOSs. Responses from single photoreceptors (obtained using adaptive optics) are surprisingly heterogenous, with some cells increasing their reflectance in response to visual stimulation, while others decrease. This talk will review our early work, survey recent findings, and consider various theories for the origin of the effect.

noninvasive monitoring↗
NASA NTRS2006

Measuring Vapors To Monitor the State of Cure of a Resin

A proposed noninvasive method of monitoring the cure path and the state of cure of an epoxy or other resin involves measurement of the concentration( s) of one or more compound(s) in the vaporous effluent emitted during the curing process. The method is based on the following general ideas: (1) The concentrations of the effluent compounds in the vicinity of the curing resin are approximately proportional to the instantaneous rate of curing. (2) As curing proceeds at a given temperature, subsequent decreases in the concentrations are indicative of approaching completion of cure; that is, the lower are the concentrations, the more nearly complete is the cure.

Cramer, Elliott↗
NASA NTRS2016

Fluid Shifts: Otoacoustical Emission Changes in Response to Posture and Lower Body Negative Pressure

INTRODUCTION: The purpose of the NASA Fluid Shifts Study is to characterize fluid distribution and compartmentalization associated with long-duration spaceflight and to correlate these findings with vision changes and other elements of the visual impairment and intracranial pressure (VIIP) syndrome. VIIP signs and symptoms, as well as postflight lumbar puncture data, suggest that elevated intracranial pressure (ICP) may be associated with spaceflight-induced cephalad fluid shifts, but this hypothesis has not been tested. Due to the invasive nature of direct measures of ICP, a noninvasive technique of monitoring ICP is desired for use during spaceflight. The phase angle and amplitude of otoacoustic emissions (OAEs) have been shown to be sensitive to posture change and ICP (1, 2), therefore use of OAEs is an attractive option. OAEs are low-level sounds produced by the sensory cells of the cochlea in response to auditory stimulation. These sounds travel peripherally from the cochlea, through the oval window, to the ear canal where they can be recorded. OAE transmission is sensitive to changes in the stiffness of the oval window, occurring as a result of changes in cochlear pressure. Increased stiffness of the oval window largely affects the transmission of sound from the cochlea at frequencies between 800 Hz and 1600 Hz. OAEs can be self-recorded in the laboratory or on the ISS using a handheld device. Our primary objectives regarding OAE measures in this experiment were to 1) validate this method during preflight testing of each crewmember (while sitting, supine and in head-down tilt position), and 2) determine if OAE measures (and presumably ICP) are responsive to lower body negative pressure and to spaceflight. METHODS: Distortion-product otoacoustic emissions (DPOAEs) and transient evoked otoacoustic emissions (TEOAEs) were recorded preflight using the Otoport Advance OAE system (Otodynamics Ltd., Hatfield, UK). Data were collected in four conditions (seated, supine, 15 degrees head down tilt (HDT), and 15 degrees HDT with lower body negative pressure (LBNP)) to produce a range of ICP in each subject and test the susceptibility of OAEs to LBNP. LBNP was induced using the Russian Chibis suit to produce the same fit and pressures that would be experienced inflight during Chibis LBNP trials. Similar trials have occurred inflight on the ISS. A comparative analysis of preflight and inflight phase measurements and magnitudes was completed in both broad and narrow band frequency ranges. RESULTS: TEOAE data demonstrated notable phase shifts from 859-1640 Hz when the seated baseline condition is compared to supine, HDT, and HDT plus Chibis conditions. Changes were particularly pronounced at low frequencies and were consistent with the expected ICP changes. Preflight DPOAE magnitude data revealed changes consistent with increased ICP in two conditions at 1414 Hz, where a magnitude change (relative to the seated condition) was seen in the HDT position and in HDT plus Chibis. DISCUSSION: OAEs revealed systematic changes in phase and magnitude throughout all test conditions (including use of Chibis LBNP) that were consistent with ICP changes. Results indicate that OAEs may provide a rapid noninvasive means of monitoring ICP changes. The first two subjects are projected to complete inflight testing on the ISS in early 2016, with the full complement of 10 subjects scheduled to be complete in 2018.

Melgoza, R.↗
NASA NTRS1993

Eddy-Current Monitoring Of Composite Layups

Eddy-current-probe apparatus used to determine predominant orientations of fibers in fiber/matrix composite materials. Apparatus nondestructive, noninvasive means for monitoring composite prepregs and layups during fabrication to ensure predictable and repeatable mechanical properties of finished composite panels. Consists essentially of electromagnet coil wrapped around horseshoe-shaped powdered-iron or ferrite ore. Optionally, capacitor included in series or parallel with coil to form resonant circuit. Impedance monitor excites radio-frequency current in coil and measures impedance of probe circuit. Affected by whatever material placed near ends of core, where material intercepts alternating magnetic field excited in core by current in coil.

Fox, Robert L.↗
NASA NTRS1990

Laser Schlieren System Detects Sounds Of Leaks

Hostile environments monitored safely and noninvasively. Modified laser schlieren system acts as microphone to detect sounds of leaks remotely. Sensitive to acoustical frequencies above audible range and especially suited for monitoring leaks of high-pressure steam from boilers or chemical vapors from processing equipment. Does not require placement of delicate equipment in harsh environment monitored, and no contact needed with boiler or other unit being monitored. Detects sound waves via variation of index of refraction of air at acoustical frequencies. Used to monitor sound frequencies beyond range of human hearing.

Shakkottai, Parthasarathy P.↗
NASA NTRS1985

Method for thermal monitoring subcutaneous tissue

A noninvasive accurate method for measuring the temperature of tissue beneath the surface of a living body is described. Ultrasonic signals are directed into beads of a material that are inserted into the tissue with a syringe. The reflected signals indicate the acoustic impedance or resonance frequency of the beads which in turn indicates the temperature of the tissue. A range of temperatures around the melting temperature of the material can be measured by this method.

Heyman, J. S.↗
DOE OSTI2025

Improved laser-plasma accelerator stability via high-bandwidth longitudinal focal position stabilization of a 100 TW-class laser system

Laser-plasma accelerators (LPAs) offer an attractive alternative to conventional accelerators for the development of compact electron sources and next-generation light sources. Due to orders-of-magnitude larger accelerating gradients, LPAs enable the acceleration of high-brightness electron beams to ultrarelativistic energies in millimeter- to centimeter-scale distances. However, LPA stability is limited by shot-to-shot fluctuations of the driving laser system. Specifically, fluctuations in the final-focus longitudinal position result in correlated instability in LPA electron beam qualities, including total beam charge, average beam energy, and energy spread. We demonstrate active stabilization of the longitudinal focal position for a 100 TW-class laser system. This repetition-rate scalable stabilization system leverages noninvasive wave front monitoring of a copropagating, unamplified kHz pulse train to guide corrective adjustments to the focal position of a 1 Hz amplified drive laser via an upstream telescope on millisecond timescales. In this demonstration, the approach limits standard deviation fluctuations of the amplified drive beam’s longitudinal focal position to ±0.22⁢ mm (representing at least a 53% reduction), achieved with a correction bandwidth that reaches the Nyquist frequency limit. Consequently, we observe marked improvements in both long-term and shot-to-shot LPA stability in terms of charge and spectrum.

Beam control↗
NASA NTRS1971

Future needs for biomedical transducers

In summary there are three major classes of transducer improvements required: improvements in existing transducers, needs for unexploited physical science phenomena in transducer design, and needs for unutilized physiological phenomena in transducer design. During the next decade, increasing emphasis will be placed on noninvasive measurement in all of these areas. Patient safety, patient comfort, and the need for efficient utilization of the time of both patient and physician requires that noninvasive methods of monitoring be developed.

Wooten, F. T.↗
NASA NTRS1997

Image processing for improved eye-tracking accuracy

Video cameras provide a simple, noninvasive method for monitoring a subject's eye movements. An important concept is that of the resolution of the system, which is the smallest eye movement that can be reliably detected. While hardware systems are available that estimate direction of gaze in real-time from a video image of the pupil, such systems must limit image processing to attain real-time performance and are limited to a resolution of about 10 arc minutes. Two ways to improve resolution are discussed. The first is to improve the image processing algorithms that are used to derive an estimate. Off-line analysis of the data can improve resolution by at least one order of magnitude for images of the pupil. A second avenue by which to improve resolution is to increase the optical gain of the imaging setup (i.e., the amount of image motion produced by a given eye rotation). Ophthalmoscopic imaging of retinal blood vessels provides increased optical gain and improved immunity to small head movements but requires a highly sensitive camera. The large number of images involved in a typical experiment imposes great demands on the storage, handling, and processing of data. A major bottleneck had been the real-time digitization and storage of large amounts of video imagery, but recent developments in video compression hardware have made this problem tractable at a reasonable cost. Images of both the retina and the pupil can be analyzed successfully using a basic toolbox of image-processing routines (filtering, correlation, thresholding, etc.), which are, for the most part, well suited to implementation on vectorizing supercomputers.

NASA Discipline Space Human Factors↗
NASA NTRS2012

Anomaly Detection Techniques with Real Test Data from a Spinning Turbine Engine-Like Rotor

Online detection techniques to monitor the health of rotating engine components are becoming increasingly attractive to aircraft engine manufacturers in order to increase safety of operation and lower maintenance costs. Health monitoring remains a challenge to easily implement, especially in the presence of scattered loading conditions, crack size, component geometry, and materials properties. The current trend, however, is to utilize noninvasive types of health monitoring or nondestructive techniques to detect hidden flaws and mini-cracks before any catastrophic event occurs. These techniques go further to evaluate material discontinuities and other anomalies that have grown to the level of critical defects that can lead to failure. Generally, health monitoring is highly dependent on sensor systems capable of performing in various engine environmental conditions and able to transmit a signal upon a predetermined crack length, while acting in a neutral form upon the overall performance of the engine system.

Abdul-Aziz, Ali↗
NASA NTRS2009

Health Monitoring of a Rotating Disk Using a Combined Analytical-Experimental Approach

Rotating disks undergo rigorous mechanical loading conditions that make them subject to a variety of failure mechanisms leading to structural deformities and cracking. During operation, periodic loading fluctuations and other related factors cause fractures and hidden internal cracks that can only be detected via noninvasive types of health monitoring and/or nondestructive evaluation. These evaluations go further to inspect material discontinuities and other irregularities that have grown to become critical defects that can lead to failure. Hence, the objectives of this work is to conduct a collective analytical and experimental study to present a well-rounded structural assessment of a rotating disk by means of a health monitoring approach and to appraise the capabilities of an in-house rotor spin system. The analyses utilized the finite element method to analyze the disk with and without an induced crack at different loading levels, such as rotational speeds starting at 3000 up to 10 000 rpm. A parallel experiment was conducted to spin the disk at the desired speeds in an attempt to correlate the experimental findings with the analytical results. The testing involved conducting spin experiments which, covered the rotor in both damaged and undamaged (i.e., notched and unnotched) states. Damaged disks had artificially induced through-thickness flaws represented in the web region ranging from 2.54 to 5.08 cm (1 to 2 in.) in length. This study aims to identify defects that are greater than 1.27 cm (0.5 in.), applying available means of structural health monitoring and nondestructive evaluation, and documenting failure mechanisms experienced by the rotor system under typical turbine engine operating conditions.

Abdul-Aziz, Ali↗
DOE OSTI2026

Generalizing synthetic data-trained acoustic predictive models to real-world measurements

Acoustic Resonance Spectroscopy (ARS) is highly sensitive to structural properties such as material, geometry, and environmental conditions; as a consequence, it can noninvasively measure internal properties that are unobservable by most other methods. Because of its sensing capabilities and low implementation cost and complexity, ARS has potential as a paradigm shift in noninvasive sensing, characterization, and monitoring applications. However, extracting specific properties from ARS measurements, comprising the vibration spectrum of a test object, is challenging due to the sensitivity of the spectra to other structural changes not being measured, e.g. manufacturing tolerances, component coupling, environmental variation, etc. Neural Networks are promising tools for identifying trends in ARS measurements, but their training typically requires large datasets, which are often impractical to obtain for real-world systems. Synthetic data can be simulated efficiently, but discrepancies between synthetic and real-world data frequently lead to poor generalization when testing on the real-world data. We propose a novel ARS model training framework that enables networks trained exclusively on synthetic ARS data to generalize effectively to real-world measurements. Our approach leverages the Correlation Alignment (CORAL) technique to enforce the extraction of features common to both synthetic and real-world domains. As a case study, we demonstrate noninvasive ARS-based pressure measurements in sealed systems. Finite element method (FEM) simulations were used to generate synthetic training data across diverse vessel configurations and pressure conditions, and model performance was then tested on real-world measurements. We demonstrate that robust machine learning models for ARS can be developed without large real-world datasets, significantly broadening the applicability of ARS for noninvasive sensing. Moreover, the approach is extensible to other sensing modalities where synthetic data are abundant but real-world data are limited.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Remote Americium Detection Using an Optical Sensor: A D-Optimal Strategy for Efficient PLS-Based Modeling

A fiber-optic visible–near-infrared absorption spectroscopy system in a glove box was demonstrated for remote quantification of Am(III) (0–500 µM) and HNO 3 (0.1–9 M) using partial least squares regression (PLSR) models. The sensor platform, featuring a simple plug-and-play spectrophotometer, can enable noninvasive, real-time monitoring of actinide process solutions. To establish a flexible PLSR model calibration strategy, a D-optimal design developed using Nd(III) in previous studies was successfully extended to an actinide system with Am(III) to effectively minimize sample set size while maintaining robust prediction performance. The results suggest strong spectral similarities between Nd(III) and Am(III) and validate Nd(III) as an effective optical surrogate for trivalent actinide species. This work also supports the generalizability of a D-optimal training set selection approach for two-factor systems. The PLS1 models for Am(III) and HNO 3 outperformed a PLS2 model and maintained reasonable performance in the presence of interfering U(VI). The resulting sensor system and multivariate approach provides a flexible and scalable solution for process monitoring, control, and safety in diverse nuclear applications.

actinide↗
NASA NTRS2005

Cognitive Performance in Operational Environments

Optimal cognition during complex and sustained operations is a critical component for success in current and future military operations. "Cognitive Performance, Judgment, and Decision-making" (CPJD) is a newly organized U.S. Army Medical Research and Materiel Command research program focused on sustaining operational effectiveness of Future Force Warriors by developing paradigms through which militarily-relevant, higher-order cognitive performance, judgment, and decision-making can be assessed and sustained in individuals, small teams, and leaders of network-centric fighting units. CPJD evaluates the impact of stressors intrinsic to military operational environments (e.g., sleep deprivation, workload, fatigue, temperature extremes, altitude, environmental/physiological disruption) on military performance, evaluates noninvasive automated methods for monitoring and predicting cognitive performance, and investigates pharmaceutical strategies (e.g., stimulant countermeasures, hypnotics) to mitigate performance decrements. This manuscript describes the CPJD program, discusses the metrics utilized to relate militarily applied research findings to academic research, and discusses how the simulated combat capabilities of a synthetic battle laboratory may facilitate future cognitive performance research.

Russo, Michael↗
NASA NTRS2010

Noninvasive Techniques for Intracranial Pressure Assessment: A Review from Aerospace Medicine Perspective

Microgravity-induced changes in fluid distribution and other physiological factors due to space flight have been implicated as the cause of increased intracranial pressure (ICP) in a number of space crewmembers. The modest levels of ICP elevation and absence of severe symptoms in this group do not warrant invasive diagnostic interventions. However, the long-term trends and residual or consequential changes secondary to the observed ICP elevation in this group are not yet known. Therefore, close attention is needed to evaluate the potential techniques of noninvasively assessing ICP, including those feasible for in-flight use. Of particular interest is continuity between ground and in-flight testing, whereby data from the same or different techniques allow reasonably dependable estimation of ICP trends and responses. Methods: A thorough review of current literature, analysis of NASA data, and interviews with subject matter experts were conducted to construct a presentation that reflects the state of the art for noninvasive ICP measurement and monitoring. Results: Multiple imaging and non-imaging modalities are available to assess ICP in terrestrial clinical and experimental environments. Imaging alternatives include magnetic resonance imaging (MRI) and high-resolution sonography. Non-imaging techniques include transcranial Doppler, certain audiological methods, and venous ophthalmodynamometry, among others. Special functional techniques have been proposed recently that allow the use of advanced MRI methods to calculate ICP in addition to the acquisition of high-resolution images. Our data include many of these applications, with several cases of correlation with lumbar puncture, the invasive "gold standard" measurement of ICP.

Hamilton, Douglas R.↗
NASA NTRS2015

Designing an Exploration Atmosphere Prebreathe Protocol

Extravehicular activities (EVAs) at remote locations must maximize limited resources such as oxygen (O2) and also minimize the risk of decompression sickness (DCS). A proposed remote denitrogenation (prebreathe) protocol requires astronauts to live in a mildly hypoxic atmosphere at 8.2 psia while periodically performing EVAs at 4.3 psia. Empirical data are required to confirm that the protocol meets the current accept requirements: less than or equal to 15% incidence of Type I DCS, less than or equal to 20% incidence of Grade IV venous gas emboli (VGE), both at 95% statistical confidence, with no Type II DCS symptom during the validation trial. METHODS: A repeated measures statistical design is proposed in which groups of 6 subjects with physical characteristics similar to active-duty astronauts would first become equilibrated to an 8.2 psia atmosphere in a hypobaric chamber containing 34% O2 and 66% N2, over 48 h, and then perform 4 simulated EVAs at 4.3 psia over the next 9 days. In the equilibration phase, subjects undergo a 3-h 100% O2 mask prebreathe prior to and during a 5-min ascent to 8.2 psia to prevent significant tissue N2 supersaturation on reaching 8.2 psia. Masks would be removed once 34% O2 is established at 8.2 psia, and subjects would then equilibrate to this atmosphere for 48 h. The hypoxia is equivalent to breathing air at 1,220 meters (4,000 ft) altitude, just as was experienced in the shuttle 10.2 psia - 26.5% O2 staged denitrogenation protocol and the current ISS campout denitrogenation protocol. For simulated EVAs, each subject dons a mask and breathes 85% O2 and 15% N2 during a 3-min depressurization to 6.0 psia, holds for 15 min, and then completes a 3-min depressurization to 4.3 psia. The simulated EVA period starts when 6.0 psia is reached and continues for a total of 240 min (222 min at 4.3 psia). During this time, subjects will follow a prescribed repetitive activity against loads in the upper and lower body with mean metabolic rate approaching 1500 BTU/hr [378 kcal/hr (O2 consumption about 1.3 l(sub STPD)/min)] in ambulatory subjects. Noninvasive Doppler ultrasound bubble monitoring for VGE in the pulmonary artery will be performed on subjects by 2 Doppler Technicians at about 15 min intervals while at 4.3 psia. At the end of this period, a 15-min repressurization returns all subjects back to 8.2 psia and the cycle is repeated 3 additional times with a day of rest between simulated EVAs. RESULTS: With an assumed 1.5% probability of DCS [P(DCS)] and accounting for within-subject correlation, running the proposed study with 20 subjects has a 95% probability of meeting the accept criterion for DCS. But if the true probability of DCS is 3.0%, then 30 subjects would be needed to achieve about the same probability to meet our accept criterion. These results assume a standard deviation of 1.4 for the between-subjects random component of P(DCS) on a logit scale, which was estimated from a previous study.

Conkin, Johnny↗