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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 685 records · Page 38
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Acoustics at the nanoscale (nanoacoustics): A comprehensive literature review. Part II: Nanoacoustics for biomedical imaging and therapy

We report in the past decade, acoustics at the nanoscale (i.e., nanoacoustics) has evolved rapidly with continuous and substantial expansion of capabilities and refinement of techniques. Motivated by research innovations in the last decade, for the first time, recent advancements of acoustics-associated nanomaterials/nanostructures and nanodevices for different applications are outlined in this comprehensive review, which is written in two parts. As part II of this two-part review, this paper concentrates on nanoacoustics in biomedical imaging and therapy applications, including molecular ultrasound imaging, photoacoustic imaging, ultrasound-mediated drug delivery and therapy, and photoacoustic drug delivery and therapy. Firstly, the recent developments of nanosized ultrasound and photoacoustic contrast agents as well as their various imaging applications are examined. Secondly, different types of nanomaterials/nanostructures as nanocarriers for ultrasound and photoacoustic therapies are discussed. Finally, a discussion of challenges and future research directions are provided for nanoacoustics in medical imaging and therapy.

47 OTHER INSTRUMENTATION↗
DOE OSTI2019

Acoustic emission Bayesian source location: Onset time challenge

Robust identification of the most accurate observed input data among a pool of observations is key in modeling and decision making. A statistically biased observed measurement deteriorates the predictive power of a model and affects decision-making ability based on the prediction of the model. When two competing methods of measurement are available, such as methods which identify arrival times in acoustic emission (AE) signals, a principal question is whether one of the two obtained datasets, or a combination of the two, should be used later on, for example, to localize an AE source. This question becomes more important when collecting not repeatable data such as AE signals created by a propagating crack. Here this paper considers an inverse source location problem in a concrete block to address the mentioned issue, a proposed methodology which also has wider application in competitive data selection. Elastic energy released by an AE event, such as a propagating crack, is recorded by acoustic emission data acquisition system. The onset time of AE signals is often used to locate the source of the event, and its accuracy directly affects the precision of source identification. This research proposes an innovative approach to select the most probable onset time obtained from two automatic picker methods. The proposed method selects the most probable onset times, which are observed by each picker for each sensor, in a probabilistic fashion. To validate the proposed method, the most accurate onset time observed by each picker is identified by visual inspection and is compared with the one is selected by the proposed method. Finally, the dataset is used for source location identification. Results show that picked onset times determined by the proposed method generate more accurate source identification when compared with coordinates obtained using each dataset individually.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2015

Coherent Acoustic Phonons in Colloidal Semiconductor Nanocrystal Superlattices

The phonon properties of films fabricated from colloidal semiconductor nanocrystals play a major role in thermal conductance and electron scattering, which govern the principles for building colloidal-based electronics and optics including thermoelectric devices with a high ZT factor. The key point in understanding the phonon properties is to obtain the strength of the elastic bonds formed by organic ligands connecting the individual nanocrystallites. In the case of very weak bonding, the ligands become the bottleneck for phonon transport between infinitively rigid nanocrystals. In the opposite case of strong bonding, the colloids cannot be considered as infinitively rigid beads and the distortion of the superlattice caused by phonons includes the distortion of the colloids themselves. We use the picosecond acoustics technique to study the acoustic coherent phonons in superlattices of nanometer crystalline CdSe colloids. We observe the quantization of phonons with frequencies up to 30 GHz. The frequencies of quantized phonons depend on the thickness of the colloidal films and possess linear phonon dispersion. Finally, the measured speed of sound and corresponding wave modulus in the colloidal films point on the strong elastic coupling provided by organic ligands between colloidal nanocrystals.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Aerosol jet printing of piezoelectric surface acoustic wave thermometer

Abstract Surface acoustic wave (SAW) devices are a subclass of micro-electromechanical systems (MEMS) that generate an acoustic emission when electrically stimulated. These transducers also work as detectors, converting surface strain into readable electrical signals. Physical properties of the generated SAW are material dependent and influenced by external factors like temperature. By monitoring temperature-dependent scattering parameters a SAW device can function as a thermometer to elucidate substrate temperature. Traditional fabrication of SAW sensors requires labor- and cost- intensive subtractive processes that produce large volumes of hazardous waste. This study utilizes an innovative aerosol jet printer to directly write consistent, high-resolution, silver comb electrodes onto a Y-cut LiNbO 3 substrate. The printed, two-port, 20 MHz SAW sensor exhibited excellent linearity and repeatability while being verified as a thermometer from 25 to 200 ∘ C. Sensitivities of the printed SAW thermometer are $$-96.9\times 1{0{}^{-6}}^{\circ }$$ − 96.9 × 1 0 − 6 ∘ C −1 and $$-92.0\times 1{0{}^{-6}}^{\circ }$$ − 92.0 × 1 0 − 6 ∘ C −1 when operating in pulse-echo mode and pulse-receiver mode, respectively. These results highlight a repeatable path to the additive fabrication of compact high-frequency SAW thermometers.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2020

Imaging grain microstructure in a model ceramic energy material with optically generated coherent acoustic phonons

Characterization of microstructure, chemistry and function of advanced energy materials remains a challenge for instrumentation science with tremendous opportunity for new discoveries. This active area of research is starting to make considerable strides with examples ranging from methodologies that employ bright X-rays, electron microscopy and optical spectroscopy. However, further development of instruments, capable of multimodal measurements, is necessary to fully reveal complex microstructure evolution in realistic environments and dynamical systems that are far from equilibrium. In this regard, laser-based instruments have a unique advantage as multiple measurement methodologies are easily combined into a single instrument using standard optics. A new pump-probe method that uses optically generated acoustic phonons is expanding standard optical characterization by providing depth resolved information. Here we report on a noteworthy extension of this pump-probe method to image grain microstructure in ceria. Rich information regarding the orientation of individual crystallites is obtained by monitoring acoustic phonon velocities and noting how the polarization of the probe beam influences the detected signal amplitude. When paired with other optical microscopies, this methodology will provide new perspectives for optical characterization of ceramic materials.

36 MATERIALS SCIENCE↗
DOE OSTI2010

Distinctive features of ion-acoustic solitons in electron-positron-ion superdense magnetoplasmas with degenerate electrons and positrons

Using the extended Poincare-Lighthill-Kuo reductive perturbation method to study the small-amplitude ion acoustic solitary wave dynamics (propagation and interaction), it is shown that in the Thomas-Fermi magnetoplasma consisting of inertial-less degenerate electrons and positrons and isothermal ions, distinctive features emerge when the ultrarelativistic degeneracy pressure applies to electrons and positrons. Calculations show that ion-acoustic solitary waves may interact differently in such plasmas under ultrarelativistic degeneracy pressure.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2010

Prufer Transformations for the Normal Modes in Ocean Acoustics

In 1926 Prufer introduced a method of transforming the second order Sturm-Liouville (SL) equation into two nonlinear first order differential equations for the phase oe and ''magnitude'', |oe{sup 2}+oe{sup 2}| for a Poincare phase space representation, (oe,oe). The useful property is the phase equation decouples from the magnitude one which leads to a nonlinear, two point boundary value problem for the eigenvalues, or SL numbers. The transformation has been used both theoretically, e.g. Atkinson, [1960] to prove certain properties of SL equations as well as numerically e.g Bailey [1978]. This paper examines the utility of the Prufer transformation in the context of numerical solutions for modes of the ocean acoustic wave equation. (Its use is certainly not well known in the ocean acoustics community.) Equations for the phase, oe, and natural logarithm of the ''magnitude'', ln(|oe{sup 2}+oe{sup 2}|) lead to same decoupling and a fast and efficient numerical solution with the SL eigenvalues mapping to the horizontal wavenubers. The Prufer transformation has stabilty problems for low order modes at high frequecies, so a numerically stable method of integrating the phase equation is derived. This seems to be the first time the these stability issues have been highlighted to provide a robust algorthim for the modes.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2010

Dust-ion-acoustic wave oscillation in metallic multiwalled carbon nanotubes

In this paper, a charged multiwalled carbon nanotube (MWCNT), which is surrounded by charged nanoparticles, is modeled as a cylindrical shell of electron-ion-dust plasma. By employing the classical electrodynamics formulations and linearized hydrodynamic model, the dispersion relation of the dust-ion-acoustic wave oscillations in the composed system is investigated. We obtain a new low-frequency electrostatic excitation in the MWCNTs, i.e., dust-ion-acoustic wave oscillations.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2010

Ion acoustic solitons in unmagnetized inhomogeneous multi-ion component plasmas with vortex distributed electrons

The ion acoustic solitons are studied in an inhomogeneous multi-ion component plasma in the presence of heavy and light adiabatic ions and two temperature electrons with vortex distribution. The modified Korteweg-de Vries equation with an additional term due to density gradients is derived by employing reductive perturbation technique. It is found that the amplitude of the soliton enhances as the concentration ratio of cold to hot electrons, density gradient parameter and ion temperature are increased in the system. The effects of mass, charge ratios of heavy to light ions and electron temperature are also investigated on the structural as well as propagation characteristics of solitary wave. The equilibrium density profile is taken to be exponential. The phase velocity of ion acoustic wave is also studied as a function of various plasma parameters. The numerical results are presented for illustration.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2010

Electron-acoustic solitary waves in a nonextensive plasma

The problem of arbitrary amplitude electron-acoustic solitary waves (EASWs) in a plasma having cold fluid electrons, hot nonextensive electrons, and stationary ions is addressed. It is found that the 'Maxwellianization' process of the hot nonextensive component does not favor the propagation of the EASWs. In contrast to superthermality, nonextensivity makes the electron-acoustic solitary structure less spiky. Our theoretical analysis brings a possibility to develop more refined theories of nonlinear solitary structures in astrophysical plasmas.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2010

Head-on collision of ion acoustic solitary waves in an electron-positron-ion plasma with superthermal electrons

The head-on collision of ion acoustic solitary waves in a three-component unmagnetized plasma with cold ions, Boltzmann distributed positrons, and superthermal electrons is investigated using the extended Poincare-Lighthill-Kuo method. The effects of the ratio of electron temperature to positron temperature, the spectral index, {kappa}, of the electron kappa distribution, and fractional concentration of positron component (p) on the phase shift are studied. It is found that the presence of superthermal electrons play a significant role on the collision of ion acoustic solitary waves.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2011

Ion-acoustic waves in a nonstationary ultra-cold neutral plasma

We consider the excitation and dispersion of electrostatic ion-acoustic (IA) waves in a nonstationary ultra-cold neutral plasma (UCNP). This can be seen as an extension of time-refraction models of photons and plasmons to the case of low-frequency IA waves in the UCNP. It is shown that temporal changes in the medium lead to a frequency-shift of the IA wave, and to the emission of the IA waves propagating in a direction opposite to each other. We consider an arbitrary temporal variation of the background plasma density, and determine the transmission and reflection coefficients. We also consider the influence of a fast ionization process, assumed inhomogeneous in volume and show that it excites a well-defined spectrum of ion-acoustic waves, which agree very well with a recent experimental observation.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2011

Stability of two-dimensional ion-acoustic wave packets in quantum plasmas

The nonlinear propagation of two-dimensional (2D) quantum ion-acoustic waves (QIAWs) is studied in a quantum electron-ion plasma. By using a 2D quantum hydrodynamic model and the method of multiple scales, a new set of coupled nonlinear partial differential equations is derived which governs the slow modulation of the 2D QIAW packets. The oblique modulational instability (MI) is then studied by means of a corresponding nonlinear Schroedinger equation derived from the coupled nonlinear partial differential equations. It is shown that the quantum parameter H (ratio of the plasmon energy density to Fermi energy) shifts the MI domains around the k{theta} -plane, where k is the carrier wave number and {theta} is the angle of modulation. In particular, the ion-acoustic wave (IAW), previously known to be stable under parallel modulation in classical plasmas, is shown to be unstable in quantum plasmas. The growth rate of the MI is found to be quenched by the obliqueness of modulation. The modulation of 2D QIAW packets along the wave vector k is shown to be described by a set of Davey-Stewartson-like equations. The latter can be studied for the 2D wave collapse in dense plasmas. The predicted results, which could be important to look for stable wave propagation in laboratory experiments as well as in dense astrophysical plasmas, thus generalize the theory of MI of IAW propagations both in classical and quantum electron-ion plasmas.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2011

Linear and nonlinear coupled drift and ion acoustic waves in collisional pair ion-electron magnetoplasma

Linear and nonlinear coupled electrostatic drift and ion acoustic waves are studied in inhomogeneous, collisional pair ion-electron plasma. The Korteweg-de Vries-Burgers (KdVB) equation for a medium where both dispersion and dissipation are present is derived. An attempt is made to obtain exact solution of KdVB equation by using modified tanh-coth method for arbitrary velocity of nonlinear drift wave. Another exact solution for KdVB is obtained, which gives a structure of shock wave. Korteweg-de Vries (KdV) and Burgers equations are derived in limiting cases with solitary and monotonic shock solutions, respectively. Effects of species density, magnetic field, obliqueness, and the acoustic to drift velocity ratio on the solitary and shock solutions are investigated. The results discussed are useful in understanding of low frequency electrostatic waves at laboratory pair ion plasmas.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2011

Quantitative enhancement of fatigue crack monitoring by imaging surface acoustic wave reflection in a space-cycle-load domain

The surface wave acoustic method is applied to the in-situ monitoring of fatigue crack initiation and evolution on tension specimens. A small low-frequency periodic loading is also applied, resulting in a nonlinear modulation of reflected pulses. The acoustic wave reflections are collected for: each experimental cycle; a range of applied tension and modulation load levels; and a range of spatial propagation positions, and are presented in image form to aid pattern identification. Salient features of the image are then extracted and processed to evaluate the initiation time of the crack and its subsequent size evolution until sample failure. Additionally, a method for enhancing signal to noise ratio in Ti-6242 alloy samples is demonstrated.

36 MATERIALS SCIENCE↗
DOE OSTI2011

Dust-acoustic filamentation of a current-driven dusty plasma

The thermal motion effect of charged particles in the filamentation of a current-driven dusty plasma in the dust-acoustic frequency region is investigated by using the Lorentz transformed conductivity of the dusty plasma components and the total dielectric permittivity tensor of the dusty plasma in the laboratory frame. Obtaining the dispersion relation for dust-acoustic waves and considering the filamentation instability, the establishment time of the filamentation structure and the instability development threshold are derived. Moreover, it is shown that the current layer divides into separate current filaments.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2011

The parametric decay of dust ion acoustic waves in non-uniform quantum dusty magnetoplasmas

The parametric decay instability of a dust ion acoustic wave into low-frequency electrostatic dust-lower-hybrid and electromagnetic shear Alfven waves has been investigated in detail in an inhomogeneous cold quantum dusty plasma in the presence of external/ambient uniform magnetic field. The quantum magnetohydrodynamic model of plasmas with quantum effect arising through the Bohm potential and Fermi degenerate pressure has been employed in order to find the linear and nonlinear responses of the plasma particles for three-wave nonlinear coupling in a dusty magnetoplasma. A relatively high frequency electrostatic dust ion acoustic wave has been taken as the pump wave. It couples with two other low-frequency internal possible modes of the dusty magnetoplasma, viz., the dust-lower-hybrid and shear Alfven waves. The nonlinear dispersion relation of the dust-lower-hybrid wave has been solved to obtain the growth rate of the parametric decay instability. The growth rate is at a maximum for a small value of the external magnetic field B{sub 0}. It is noted that the growth rate is proportional to the unperturbed electron number density n{sub oe} and is independent of inhomogeneity beyond L{sub e}=2 cm. An extraordinary growth rate is observed with the quantum effect.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2011

Ion acoustic shock waves in degenerate plasmas

Korteweg de Vries Burgers equation for negative ion degenerate dissipative plasma has been derived using reductive perturbation technique. The quantum hydrodynamic model is used to study the quantum ion acoustic shock waves. The effects of different parameters on quantum ion acoustic shock waves are studied. It is found that quantum parameter, electrons Fermi temperature, temperature of positive and negative ions, mass ratio of positive to negative ions, viscosity, and density ratio have significant impact on the shock wave structure in negative ion degenerate plasma.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗