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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 1,801 records · Page 100
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Predictions of macro-scale fracture geometries from acoustic emission point cloud data in a hydraulic fracturing experiment

Observations of laboratory fracture testing by means of acoustic emission (AE) can provide a wealth of information regarding the fracturing process and the subsequent damage of the material or structure under load. A method for determining the structure of macro-scale fractures from a point cloud of AE events was developed and tested at the laboratory scale. An unconfined hydraulic fracturing experiment was performed on granite while monitoring acoustic emissions from six piezoelectric transducers on the surfaces of the specimen. The granite specimen dimensions were 30 × 30 × 25 cm 3 . The motivation of the AE analysis was to provide location information for a secondary wellbore placement which intersects the hydraulic fracture to complete a hydraulically connected binary well-hydraulic fracture system. Information gained from the 3D event source locations was used to optimize the location and orientation of secondary production well placement to intersect the induced hydraulic fracture. A direct method was developed to predict the location, orientation and shape of the hydraulic fracture from a dense cloud of AE events. The predicted fracture plane, which was assumed to be planar, was rotated in both the pitch and roll directions, while an average error of AE event distance between the assumed plane and the individual event locations was determined for each rotation iteration, resulting with a predicted fracture plane in the minimum error orientation. Post-test fracture observations were made and digitized in 3D space from coring and slabbing the granite specimen. The actual fracture observations were compared with the predicted fracture structure from AE and showed marked correlation. In conclusion, the simple method of determining macro-scale fracture location, orientation, and extents provided a useful tool for materials that exhibit large and disperse clouds of AE activity where coalesced fracture structure is not apparent.

42 ENGINEERING↗
DOE OSTI2018

Impact of Ceramic Substrates Geometry on the Performance of Simple Thermo-Acoustic Engines

This work experimentally examines the influence of the stack geometry and position on the performance of thermo-acoustic engines (TAE). Twenty cordierite honeycomb ceramic stacks with square pores and five different lengths (7, 13, 17, 22 and 25 mm) were considered. Measurements were taken at seven different locations of the stack hot ends from the pressure antinode (closed end), namely 52, 72, 92,112, 132, 152 and 172 mm respectively. The temperature difference across the stack and radiated sound pressure level at steady state are considered indicators of the performance of the device. The results obtained with a simple standing wave thermo-acoustic engine used in this experiment reveals that the relationships between the length, the stack pores sizes and the input power are non-linear. In addition, the effect of the viscous resistance and the thermal losses were confirmed to be strong enough when the input heating power is low.

42 ENGINEERING↗
DOE OSTI2014

Dust ion-acoustic rogue waves in a three-species ultracold quantum dusty plasmas

Dust ion-acoustic (DIA) rogue waves are reported for a three-component ultracold quantum dusty plasma comprised of inertialess electrons, inertial ions, and negatively charged immobile dust particles. The nonlinear Schrödinger (NLS) equation appears for the low frequency limit. Modulation instability (MI) of the DIA waves is analyzed. Influence of the modulation wave number, ion-to-electron Fermi temperature ratio ρ and dust-to-ion background density ratio N{sub d} on the MI growth rate is discussed. The first- and second-order DIA rogue-wave solutions of the NLS equation are examined numerically. It is found that the enhancement of N{sub d} and carrier wave number can increase the envelope rogue-wave amplitudes. However, the increase of ρ reduces the envelope rogue-wave amplitudes. - Highlights: • The nonlinear Schrödinger equation is derived for the low frequency limit. • Modulational instability growth rate is discussed. • The first- and second-order dust ion-acoustic rogue waves are examined numerically.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2021

Monitoring of corrosion effects in pipes with multi-mode acoustic signals

Current commercial long-range guided wave inspection and monitoring technologies for pipes usually require establishment of certain specific acoustic modes for wave propagation and use a large number of sensors in a certain geometric arrangement (for example, uniformly-spaced arrays of sensors on a collar, placed around a pipe). This paper, in contrast, presents a long-range corrosion detection method in pipes based on multi-mode guided acoustic waves, generated and received using simple, single-element sensors. In this technique, available guided wave modes in any interrogated zone of the structure are automatically down-selected by the medium, and changes in energy distribution over the selected modes are analyzed through signal processing to monitor material loss or addition. Here, to investigate the feasibility of the proposed method, we have performed both experimental and numerical simulation studies on 50.8-mm (2-in)-diameter schedule-40 carbon steel pipes. In these studies, a linear chirp signal is injected in compression mode, perpendicular to the surface of the pipe, generating multi-mode, multi-directional guided waves that travel within the pipe wall. Corrosion effects in the pipes are simulated numerically and experimentally. To reduce errors in the measurement technique due to changes in the local or global temperature of the measured media, a universal temperature compensation algorithm is introduced. The experimental results show good agreement with simulation results, indicating that the proposed multi-mode wave generation and detection in a pipe could be used for long-range detection and monitoring of corrosion effects, such as pipe wall losses or solid material deposits.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Acoustical sensing of cardiomyocyte cluster beating

Highlights: •An example of the application of QCM-D to live cell studies. •Detection of human pluripotent stem cell-derived cardiomyocyte cluster beating. •Clusters were studied in a thin liquid film and in a large liquid volume. •The QCM-D beating profile provides an individual fingerprint of the hPS-CMCs. -- Abstract: Spontaneously beating human pluripotent stem cell-derived cardiomyocytes clusters (CMCs) represent an excellent in vitro tool for studies of human cardiomyocyte function and for pharmacological cardiac safety assessment. Such testing typically requires highly trained operators, precision plating, or large cell quantities, and there is a demand for real-time, label-free monitoring of small cell quantities, especially rare cells and tissue-like structures. Array formats based on sensing of electrical or optical properties of cells are being developed and in use by the pharmaceutical industry. A potential alternative to these techniques is represented by the quartz crystal microbalance with dissipation monitoring (QCM-D) technique, which is an acoustic surface sensitive technique that measures changes in mass and viscoelastic properties close to the sensor surface (from nm to μm). There is an increasing number of studies where QCM-D has successfully been applied to monitor properties of cells and cellular processes. In the present study, we show that spontaneous beating of CMCs on QCM-D sensors can be clearly detected, both in the frequency and the dissipation signals. Beating rates in the range of 66–168 bpm for CMCs were detected and confirmed by simultaneous light microscopy. The QCM-D beating profile was found to provide individual fingerprints of the hPS-CMCs. The presented results point towards acoustical assays for evaluation cardiotoxicity.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

Acoustic emission analysis of cyclically loaded superelastic shape memory alloy fiber reinforced mortar beams

Superelastic shape memory alloys (SMAs) are metallic alloys that can recover their nonlinear deformations upon unloading. The use of SMAs in cementitious composites as fibers can enable crack recovery and re-centering capabilities. In this study, the crack recovery characteristics of SMA fiber reinforced mortar specimens subjected to flexural cyclic loading are studied through acoustic emission analysis. SMA fiber reinforced mortar specimens with fiber volume ratios of 0.3%, 0.5% and 1.0% are tested under cyclic flexural loads. Acoustic emissions (AE) signals are captured and analyzed to characterize the crack formation and crack width development at each cycle of loading. In addition, the crack width propagation of the specimens is monitored by Digital Image Correlation measurement system and is used as a basis in AE analyses. Results show that the SMA fiber reinforced mortars exhibit considerable re-centering and crack recovery characteristics at large deformation amplitudes.

36 MATERIALS SCIENCE↗
DOE OSTI2014

A comparison of implantation methods for large PIT tags or injectable acoustic transmitters in juvenile Chinook salmon

The miniaturization of acoustic transmitters may allow greater flexibility in terms of the size and species of fish available to tag. New downsized injectable acoustic tags similar in shape to passive integrated transponder tags can be rapidly injected rather than surgically implanted through a sutured incision, as is current practice. Before wide-scale field use of these injectable transmitters, standard protocols to ensure the most effective and least damaging methods of implantation must be developed. Three implantation methods were tested in various sizes of juvenile Chinook salmon Oncorhynchus tschawytscha. Methods included a needle bevel-down injection, a needle bevel-up injection with a 90-degree rotation, and tag implantation through an unsutured incision. Tagged fish were compared to untagged control groups. Weight and wound area were measured at tagging and every week for 3 weeks; holding tanks were checked daily for mortalities and tag losses. No differences among treatments were found in growth, tag loss, or survival, but wound area was significantly reduced among incision-treated fish. The bevel-up injection had the worst results in terms of tag loss and wound area and also had high mortality. Implantation through an incision resulted in the lowest tag loss but the highest mortality. Fish from the bevel-down treatment group had the least mortality; wound areas also were smaller than the bevel-up treatment group. Cumulatively, the data suggest that the unsutured incision and bevel-down injection methods were the most effective; the drawbacks of both methods are described in detail. However, we further recommend larger and longer studies to find more robust thresholds for tagging size that include more sensitive measures.

injection↗
DOE OSTI2018

A high-order multiscale finite-element method for time-domain acoustic-wave modeling

Accurate and efficient wave equation modeling is vital for many applications in such as acoustics, electromagnetics, and seismology. However, solving the wave equation in large-scale and highly heterogeneous models is usually computationally expensive because the computational cost is directly proportional to the number of grids in the model. We develop a novel high-order multiscale finite-element method to reduce the computational cost of time-domain acoustic-wave equation numerical modeling by solving the wave equation on a coarse mesh based on the multiscale finite-element theory. In contrast to existing multiscale finite-element methods that use only first-order multiscale basis functions, our new method constructs high-order multiscale basis functions from local elliptic problems which are closely related to the Gauss–Lobatto–Legendre quadrature points in a coarse element. Essentially, these basis functions are not only determined by the order of Legendre polynomials, but also by local medium properties, and therefore can effectively convey the fine-scale information to the coarse-scale solution with high-order accuracy. Numerical tests show that our method can significantly reduce the computation time while maintain high accuracy for wave equation modeling in highly heterogeneous media by solving the corresponding discrete system only on the coarse mesh with the new high-order multiscale basis functions.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2022

Ampere field fluctuation from acoustic phonons as a possible source of spin decoherence

Here, we present a simple theory for estimating spin decoherence due to spin–phonon coupling in a lattice, and apply the theory to the Ampere field fluctuation from acoustic phonons. The Ampere field is generated by charge current loops around each lattice site due to acoustic phonon motion of the ions. The spin decoherence time due to the Ampere field fluctuation is estimated for NV centers and Mo impurities in SiC, and quantum dot qubits in Ge, GaAs, InAs, and InSb for temperature range 2 to 300 K. For most materials the estimated decoherence time is orders of magnitude longer than reported experimental values at the same temperature. The only exception is Mo impurity in SiC, for which the experimental decoherence time at 2 K is close to that due to Ampere field fluctuation.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2025

Accurate and rapid acoustic damage characterization in complex structures using sparse sensor networks and deep learning models

Damage diagnosis in critical components is essential for ensuring the safety and reliability of operations across industries, spanning manufacturing, aerospace, and energy. Traditional acoustic nondestructive testing methods primarily focus on detecting defects through the direct scattering of single-mode incident waves from the damage, which limit their applicability to simple structures and small inspection areas. Our earlier research demonstrated that machine learning algorithms combined with sparse sensor networks can identify critical defect signatures even from multiply scattered, multi-mode acoustic signals, indicating the potential for improved defect inspection in complex, real-world structures. In this work, we demonstrate the successful implementation of this approach in a fixed sensor configuration to rapidly and accurately detect simulated defects in a geometrically complex, real-world structure, a brake rotor hub. Three different types of defects were physically simulated on the surface of the hub, and the collected data were used to train an autoencoder-based deep learning model. Two models were tested, one using single measurements and the other using multiple measurements taking advantage of the spatial distribution of the sensor network. After training, the multi-measurement model achieved 100 % accuracy in identifying, classifying, and locating unseen, unique damages. This work illustrates the potential of the proposed method for a wide range of industrial applications.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Use of co-combustion bottom ash to design an acoustic absorbing material for highway noise barriers

Highlights: • The particle size of bottom ash influenced the acoustic behavior of the barrier. • The best sound absorption coefficients were measured for larger particle sizes. • The maximum noise absorption is displaced to lower frequencies for higher thickness. • A noise barrier was designed with better properties than commercial products. • Recycling products from bottom ash no present leaching and radioactivity problems. - Abstract: The present study aims to determine and evaluate the applicability of a new product consisting of coal bottom ash mixed with Portland cement in the application of highway noise barriers. In order to effectively recycle the bottom ash, the influence of the grain particle size of bottom ash, the thickness of the panel and the combination of different layers with various particle sizes have been studied, as well as some environmental properties including leachability (EN-12457-4, NEN-7345) and radioactivity tests. Based on the obtained results, the acoustic properties of the final composite material were similar or even better than those found in porous concrete used for the same application. According to this study, the material produced presented no environmental risk.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2025

Measurement of the properties of the dust acoustic wave in a magnetic field

We present the first experimental observations of the dust acoustic wave where the wave was observed to propagate in the directions of gravity and magnetic field when these directions were not aligned. The experiments were conducted in the Magnetized Dusty Plasma eXperiment facility using a novel electrode system that allows for the angle between gravity and the magnetic field to be varied in a controlled way. This letter reports on measurements in an rf glow discharge argon plasma environment where the angle between direction of gravity and the magnetic field is 45 $^{\circ }$ . When there was no applied magnetic field, the wave was observed to propagate in the direction of gravity. However, as the magnetic field increased and the ions transitioned from flowing in the direction of gravity to the direction of the magnetic field, a second wave emerged and two distinct waves were observed to simultaneously propagate, one in the direction of gravity and one in the direction of the magnetic field. As the magnetic field was further increased, the wave that propagated in the direction of gravity was suppressed and the wave was only observed to propagate in the direction of the applied magnetic field. We also observe that the speed and the kinetic temperature of the dust for the mode that propagated in the direction of gravity decreased with increasing magnetic field while the speed and the kinetic temperature of the dust for the mode that propagated in the direction of the magnetic field increased with increasing magnetic field. These measurements suggest that an ion-dust streaming instability is at least partially responsible for the high temperatures that have previously been observed in dusty plasmas when the dust acoustic wave is present.

Williams, J. D. (ORCID:000000025199707X)↗
DOE OSTI2026

Role of ion acoustic instability in magnetic reconnection

We report on a first-principles numerical study of magnetic reconnection in plasmas with different initial ion-to-electron temperature ratios. In cases where this ratio is significantly below unity, we observe intense wave activity in the diffusion region, driven by the ion-acoustic instability. Our analysis shows that the dominant macroscopic effect of this instability is to drive substantial ion heating. In contrast to earlier studies reporting significant anomalous resistivity, we find that anomalous contributions due to the ion-acoustic instability are minimal. These results shed light on the dynamical impact of this instability on reconnection processes, offering new insights into the fundamental physics governing collisionless reconnection.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2019

Exploring the Connection between Coherent Acoustic Phonons and Bright-Field Contrast in Ultrafast Electron Microscopy

Intense ultrafast photoexcitation of archetypal semiconducting materials, such as Ge and GaAs, ends in the rapid generation of large charge-carrier densities that propagate outward from the high-fluence region at initially hypersonic velocities. This produces a number of interesting effects that become interwoven with the underlying lattice; including the development of acoustic-type propagating oscillatory modes, excitation of coherent propagating strain waves, and coalescence of phase behaviors of the acoustic phonons and charge carriers via wave-particle drag. Using bright-field imaging in an ultrafast electron microscope, we directly imaged the behavior of photoexcited, nanoscale coherent strain waves in single-crystal Ge. In addition to single preferential wavevectors and initially hypersonic phase velocities (up to 35 nm/ps), we were able to directly resolve single-phonon constant velocities and an overall time-varying phase-velocity dispersion to the bulk speed of sound over approximately one nanosecond. Comparison to dispersion behaviors expected for symmetric and asymmetric Lamb-type modes showed good agreement with experiments, suggesting the preferential excitation of a single, symmetric first-order mode. Yet, quantitative comparison to the expected and measured contrast strengths associated with the coherent dynamics is needed in order to further elucidate the precise microscopic mechanisms.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

The First Detection of an Earthquake From a Balloon Using Its Acoustic Signature

Extreme temperature and pressure conditions on the surface of Venus present formidable technological challenges against performing ground-based seismology. Efficient coupling between the Venusian atmosphere and the solid planet theoretically allows the study of seismically generated acoustic waves using balloons in the upper atmosphere, where conditions are far more clement. However, earthquake detection from a balloon has never been demonstrated. We present the first detection of an earthquake from a balloon-borne microbarometer near Ridgecrest, CA in July 2019 and include a detailed analysis of the dependence of seismic infrasound, as measured from a balloon on earthquake source parameters, topography, and crustal and atmospheric structure. Our comprehensive analysis of seismo-acoustic phenomenology demonstrates that seismic activity is detectable from a high-altitude platform on Earth, and that Rayleigh wave-induced infrasound can be used to constrain subsurface velocities, paving the way for the detection and characterization of such signals on Venus.

58 GEOSCIENCES↗
DOE OSTI2023

The AtmoSOFAR Channel: First Direct Observations of an Elevated Acoustic Duct

The Sound Fixing and Ranging (SOFAR) channel in the ocean allows for low frequency sound to travel thousands of kilometers, making it particularly useful for detecting underwater nuclear explosions. Suggestions that an elevated SOFAR-like channel should exist in the stratosphere date back over half a century and imply that sources within this region can be reliably sensed at vast distances. However, this theory has not been supported with evidence of direct observations from sound within this channel. Here we show that an infrasound sensor on a solar hot air balloon recorded the first infrasound detection of a ground truth airborne source while within this acoustic channel, which we refer to as the AtmoSOFAR channel. Our results support the existence of the AtmoSOFAR channel, demonstrate that acoustic signals can be recorded within it, and provide insight into the characteristics of recorded signals. Results also show a lack of detections on ground-based stations, highlighting the advantages of using balloon-borne infrasound sensors to detect impulsive sources at altitude.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

Accessing the exceptional points of parity-time symmetric acoustics

Parity-time (PT) symmetric systems experience phase transition between PT exact and broken phases at exceptional point. These PT phase transitions contribute significantly to the design of single mode lasers, coherent perfect absorbers, isolators, and diodes. However, such exceptional points are extremely difficult to access in practice because of the dispersive behaviour of most loss and gain materials required in PT symmetric systems. Here we introduce a method to systematically tame these exceptional points and control PT phases. Our experimental demonstration hinges on an active acoustic element that realizes a complex-valued potential and simultaneously controls the multiple interference in the structure. The manipulation of exceptional points offers new routes to broaden applications for PT symmetric physics in acoustics, optics, microwaves and electronics, which are essential for sensing, communication and imaging.

42 ENGINEERING↗
DOE OSTI2020

Ultralow thermal conductivity from transverse acoustic phonon suppression in distorted crystalline α-MgAgSb

Low thermal conductivity is favorable for preserving the temperature gradient between the two ends of a thermoelectric material, in order to ensure continuous electron current generation. In high-performance thermoelectric materials, there are two main low thermal conductivity mechanisms: the phonon anharmonic in PbTe and SnSe, and phonon scattering resulting from the dynamic disorder in AgCrSe2 and CuCrSe2, which have been successfully revealed by inelastic neutron scattering. Using neutron scattering and ab initio calculations, we report here a mechanism of static local structure distortion combined with phononanharmonic-induced ultralow lattice thermal conductivity in α-MgAgSb. Since the transverse acoustic phonons are almost fully scattered by the compound’s intrinsic distorted rocksalt sublattice, the heat is mainly transported by the longitudinal acoustic phonons. The ultralow thermal conductivity in α-MgAgSb is attributed to its atomic dynamics being altered by the structure distortion, which presents a possible microscopic route to enhance the performance of similar thermoelectric materials.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

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