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reliable underwater acoustic propagation is challenging due to complex ocean dynamics such as internal-waves and to the uncertain larger-scale ocean physics, acoustics, bathymetry, and seabed fields. for accurate acoustic propagation, capturing the important environmental uncertainties and variabilities and predicting ... | optimal stochastic modeling in random media propagation: dynamically orthogonal parabolic equations? |
the semi-analytical modeling of acoustic wave resonators is discussed in this study. a polynomial approach to wave propagation is used to predict the electromechanical behavior of piezoelectric resonators in a circular ring with hexagonal elastic symmetry. we present a legendre polynomial-based 3d semi-analytical techn... | 3-d modeling of hollow cylinder piezoelectric resonator by polynomial approach |
seismic attenuation measurements using t* have long been used to infer the anelastic (intrinsic attenuation) structure of the subsurface. an important limitation in this technique is the inability to separate intrinsic attenuation effects from those caused by focusing and defocusing of rays in the presence of seismic w... | modeling focusing and defocusing effects on teleseismic shear wave seismic attenuation measurements: case study of the isabella anomaly |
the esa-jaxa mission bepicolombo, launched on 20 october 2018 and currently in cruise, will arrive at mercury in 2025 to investigate its surface, interior structure and magnetosphere. the more radio science experiment onboard the mercury planetary orbiter (mpo) aims at determining the gravity field, rotational state an... | first results from cruise tests of the mercury orbiter radio science experiment (more) of esa's bepicolombo mission |
several methods have been developed to provide an indirect measure of soil moisture at the field scale; these methods are generally non-destructive and allow measures to be taken continuously. among indirect methods, one of the most promising is the use of wireless underground communication networks (wucns). this techn... | monitoring soil water content via wireless underground communication networks: the impact of uncertainty in soil textural parameters |
biomechanical properties of the tongue play a significant role in maintaining its normal physiological state. although some techniques have been used to evaluate the tongue's elasticity, they are limited in clinical detection because of low-resolution and invasive injuries. here, a shaker-based optical coherence elasto... | quantitative evaluation of biomechanical properties of the tongue using a shaker-based optical coherence elastography system |
symmetries are crucial to the investigation of nonlinear physical processes, particularly the evaluation of a differential problem in the real world. this study focuses on the investigation of the kadomtsev–petviashvili (kp) model within a (3+1)-dimensional domain, governing the behavior of wave propagation in a medium... | a soliton solution for the kadomtsev–petviashvili model using two novel schemes |
the idea of expanding the range of properties of natural substances with artificial matter was introduced by v. g. veselago in 1967. since then, the field of metamaterials has dramatically advanced. man-made structures can now exhibit a plethora of extraordinary electromagnetic properties, such as negative refraction, ... | optical response in planar heterostructures: from artificial magnetism to angstrom-scale metamaterials |
gpr is widely being used for clearance operations of landmines and ieds (improvised explosive devices) as these objects may contain only low amount of metal, potentially rendering metal detectors unsuitable. sensor performance strongly depends on the individual in situ condition, i.e., the target size, material and dep... | landmine and ied detection with gpr: assessing soil influence through realistic simulations |
sunspots are relatively dark regions on the solar surface where the magnetic field is strongest. this field is generated by a large-scale dynamo in the solar interior and driven upwards by plasma buoyancy until it emerges through the surface. the interaction of plasma motions and magnetic fields results in a plethora o... | discovery of long-period magnetic field oscillations and motions in isolate sunspot |
effective non-destructive methods for identifying poor quality and knotty timber in standing trees can contribute to higher quality timber reaching the appropriate processing mills and to a reduction in transport costs of harvested timber. eucalyptus nitens is a major temperate plantation hardwood species primarily use... | ultrasonic and thermal testing to non-destructively identify internal defects in plantation eucalypts |
a multi-technique high resolution 3d modelling is described here aimed at the investigation of the state of conservation of carbonate columns of the 1000 bc ancient church of buon camino located in the homonymous district of the town of cagliari (italy).the integrated application of different non-destructive testing (n... | high resolution 3d modelling of cylinder shape bodies applied to 1000 ancient bc columns |
a new satellite design permits broad science measurements from the ocean to the ionosphere by flying below the f-layer. the satellite called carina for coastal-ocean, assimilation, radio, ionosphere, neutral-drag, and atmospherics. the unique system capabilities are long duration orbits below the ionosphere and a hf re... | carina satellite mission to investigate the upper atmosphere below the f-layer ionosphere |
on-body devices are an intrinsic part of the internet-of-things (iot) vision to provide human-centric services. these on-body iot devices are largely embedded devices that lack a sophisticated user interface to facilitate traditional pre-shared key based security protocols. motivated by this real-world security vulnera... | securing on-body iot devices by exploiting creeping wave propagation |
the focus of my research interests lies in the application of microwave antenna array system and array signal processing techniques to problems in wireless power transmission and radar imaging. the two research areas share the same underlying mathematical principle of time reversality of electromagnetic wave propagatio... | applications of microwave antenna array for wireless power transmission and radar imaging in complex environment |
this thesis presents novel devices and techniques that enable new methods for enhancement, concentration, refraction, shaping, collimation, and directive beaming of electromagnetic fields. these unprecedented methods to control electromagnetic fields are achieved by exploring and harnessing the unique wave-interactions... | controlling electromagnetic fields using periodic structures: gratings, metamaterials, and photonic crystals |
this presentation outlines the basic components of an mpi-parallelized high-accuracy/resolution fully nonlinear and non-hydrostatic spectral multidomain penalty method solver designed to simulate the shoaling and potential breaking of internal solitary waves (isws) over long distances along gentle slopes. the solver em... | a spectral multidomain penalty method model for the simulation of internal solitary wave shoaling and breaking over gentle slopes |
rotor-stator interaction is the main cause of harmonic pressure pulsations and resulting dynamic stresses in pump-turbine runners in normal operation. considering the guide vane passing excitation frequency and the channel length of pump-turbine runners, it shows that compressible effects in the runner channels need to... | validation of cfd analysis of acoustic effects in pump-turbine runners |
different types of ultra low frequency (ulf) waves, such as dayside compressional pc3-pc4 waves, pc2 and pc1 waves, pc3-pc4 field line resonances, night side and day side pi2s, etc. have been successfully identified in the topside ionosphere. ulf observations in this region can help us to understand the wave structure ... | structure of compressional ulf waves in the topside ionosphere as observed by the swarm constellation |
as of july 2020, nasa's juno spacecraft has performed 28 closest approaches of jupiter, which provide opportunities to observe plasma electrons in the io plasma torus along the radio ray path. juno's x-band and ka-band radio links propagating through the io plasma torus can be used to retrieve the integrated electron c... | recent advances in the io plasma torus calibrations for galileo, juno, and europa clipper radio science measurements |
since the 19th century pioneering work of sir james hall, physical analogue modelling has been proven a valuable method for the study of geological phenomena and has significantly contributed to understanding fundamental mechanisms of crust and lithosphere deformation. traditionally, in such analogue scale models, stru... | ultrasonic imaging of analogue scale models |
similar to horizontal earthquake motions, vertical motions are amplified depedent on the local site conditions which can be critical for the safety of certain structures. production of natural gas in groningen, the netherlands, results in reservoir compaction causing low magnitude, shallow earthquakes which are recorde... | amplification behaviour of compressional waves in unconsolidated sediments |
in areas of infrequent seismicity or where geologic structures (e.g., sedimentary basins) complicate seismic wave propagation, earthquake ground-motion simulations provide one approach to improving the accuracy of ground-motion predictions for seismic hazard analyses. however, most current methods for simulating earthq... | generation of broadband ground motion from dynamic rupture simulations: a group modeling approach towards better characterizing seismic hazard for engineering applications |
sandy beaches have a paramount importance as natural barrier for coastal protection (vousdoukas et al., 2020) and a valued socioeconomical asset for touristic activities (enríquez & bujosa bestard, 2020). the unprecedented population expansion along with the sea level rise put the coastal areas under a high risk fo... | flooding of sandy beaches in a changing climate and the potential of nature based solution for impact mitigation. |
quantization error and its source of the binocular stereo vision technique are evaluated by measuring breaking wave surface in wave flume. the verification test focuses on the run-up process of a breaking solitary wave on a slope. the three-dimensional topography of the free surface is reconstructed at three representa... | error evaluation of binocular vision method for reconstructing breaking wave surface |
vlf transmitters are operated by the u.s. navy for long-distance communications. close to the transmitter, ground-wave and sky-wave propagation, both of which can be strongly dispersive, significantly affect the received signal. a newly developed time-of-arrival analysis technique, which accounts for ground-wave and sk... | advances in near-transmitter vlf remote sensing: auroral precipitation effects on the d-region ionosphere |
the theoretical foundations of recovering body wave energy via seismic interferometry are well established. however in practice, such recovery remains problematic. here, synthetic seismograms computed for subsurface sources are used to evaluate the geometrical combinations of realistic ambient source and receiver distr... | cmp reflection imaging via interferometry of distributed subsurface sources |
the cascadia subduction zone is the potential locality of devastating earthquakes that could cause severe damages to the pacific northwest coastal area. contemporary low seismicity rate along the cascadia margin precludes the use of conventional methods to study the ground motion hazard in this region. we thus use ambi... | ground motions along the cascadia margin revealed by virtual earthquakes |
the ionosphere, which extends from 50-450 kms in earth's atmosphere, is a particularly important region with regards electromagnetic wave propagation and radio communications in the l-band and lower frequencies. these ions interact with the traversing electromagnetic wave and cause rotation of polarization of the radar... | mitigation of faraday rotation in alos-2/palsar-2 full polarimetric sar imageries |
convection plays an important role in establishing the interior structure in stars and in transporting the stellar luminosity. recent helioseismic observations of solar convection have created the "solar convective conundrum" and revealed that our fundamental understanding of stellar convection is flawed. sorting out o... | numerical explorations in stellar convection |
in seismology, numerous small aftershocks can be triggered locally and at a considerable distance by a moderately-sized mainshock. aftershocks may be triggered by both the static and dynamic stress perturbation, i.e., rock deformation and transient wave motion respectively. this is true for microseismicity at the micro... | geomechanical simulation of dynamic triggering of microseismicity using a bonded particle model |
the southern annular mode (sam) is an extratropical pattern that influences the climate of all southern hemisphere. however, the variability of this mode is an active area of research. the influence of lower frequency modes on sam is a path to better knowledge about this pattern. the relationship between quasi-biennial... | statistical analysis of the relationship between quasi-biennial oscillation and southern annular mode |
non-destructive evaluation (nde) methods, like ultrasonic inspection, face numerous challenges detecting defects within thin laminates. short backwall distances paired with wave scattering and high attenuation caused by innate properties of stacked laminates result in difficulties with distinguishing sub-surface defect... | ultrasonic inspection of thin composite laminates |
performances are a key concern in aerospace vehicles, requiring safer structures with as little consumption as possible. composite materials replaced aluminum alloys even in primary structures to achieve higher performances with lighter components. however, random events such as low-velocity impacts may induce damages ... | deep learning algorithms for delaminations identification on composite panels by wave propagation signal analysis |
the multiplicative (or geometric) calculus is a non-newtonian calculus derived from an arithmetic in which the operations of addition/subtraction/multiplication are replaced by multiplication/division/exponentiation. a major difference between the multiplicative calculus and the classical additive calculus, and one tha... | modelling wave propagation without sampling restrictions using the multiplicative calculus i: theoretical considerations |
we investigate the nonlinear wave propagation through micro-cracks that are compressed by external forces by means of nonlinear ultrasonic modulation technique. the nonlinear modulated waves are generated by the truncation of the waves passing through cracks due to the opening and closing of the cracks, and the nonline... | a study on the detection of compressed micro-crack by nonlinear wave modulation technique |
cast stainless steel (css) is widely used in nuclear power plants, particularly in pwr primary coolant systems. the jsme fitness-for-service code requires periodic in-service inspection of welds in such systems by ultrasonic testing (ut), but anisotropy and heterogeneity of css make flaw detection and sizing difficult.... | observation of ultrasonic wave propagation in centrifugally cast stainless steel |
here we discuss seismic wave propagation in media that contains fine scale large contrasts in material properties. a generalization of the transmitted wave as well as the reflection coefficient is explored. multiple scattering effects can be systematically incorporated into higher order approximate solutions. examples ... | quantifying wave propagation in finely stratified elastic media |
we developed a laboratory experiment to simulate a seismic refraction survey for educational purposes. the experiment is tabletop scaled experiment using the soft hydrogel as an analogue material of a layered crust. so, we can conduct the seismic exploration experiment in a laboratory or a classroom. the softness and t... | development of laboratory seismic exploration experiment for education and demonstration |
the icdp proposal dove (drilling overdeepened alpine valleys) intends to examine the quaternary glacial cycles in the alpine region. the sediment succession of overdeepened valleys and basins will be analysed in a multidisciplinary way. other objectives are related to groundwater supply and geohazards in alpine valleys... | recent developments of seismic exploration in the tannwald basin |
the present study investigates the traversal of torsional wave at a corrugated interface between viscoelastic sandy medium and inhomogeneous half-space. in the lower half-space, the inhomogeneity has been assumed as an exponential variation in density and rigidity with respect to depth. we have taken the method of vari... | propagation of torsional wave at a corrugated interface between viscoelastic sandy medium and inhomogeneous half-space |
in accordance with the formal regulations currently in force in poland, the criteria for rockburst hazard assessment with respect to coal deposits include the records of seismic events and their impacts, de-stressing of the entire seam or its parts and expert opinions of mine operation engineers. effectiveness of the d... | rockburst hazard assessment based on seismic tomography and analytical modelling - a case study |
lung ultrasound (lus) is a widely used technique in clinical lung assessment, yet the relationship between lus images and the underlying disease remains poorly understood due in part to the complexity of the wave propagation physics in complex tissue/air structures. establishing a clear link between visual patterns in ... | ultrasound imaging of lung disease and its relationship to histopathology: an experimentally validated simulation approach |
the pipes conveying fluid are concerned as extremely significant fluid-solid coupling structures due to the extensive application in the many engineering fields, but poor operating performances induced by unexpected vibration may destroy the related devices in the piping structures. to effectively attenuate the fluid-s... | novel vibration self-suppression of periodic pipes conveying fluid based on acoustic black hole effect |
in this work, we propose a novel computational technique for forecasting solar flares based on a combination of topological data analysis (tda) and machine learning applied to sunspot magnetogram data. on a magnetogram, sunspots manifest as large-scale, high-magnitude dipolar structures, whose shapes and their evolutio... | leveraging topological data analysis and deep learning for solar flare prediction |
chopped strand mat fibre-reinforced plastics (csm-frp) are very popular composites which are widely used in many applications. csm-frp can experience degradation due to the interaction of composites with the environment and mechanical loading, resulting in the decrement of elastic modulus and finally lead to failure. c... | the measurement of elastic modulus degradation on random glass fibre-reinforced polyester composites using ultrasonic testing pulse-echo method |
the suomi100 nanosatellite was launched on dec. 3, 2018 (http://www.suomi100satelliitti.fi/eng). the 1 unit (10 cm x 10 cm x 10 cm) polar orbit cubesat will perform geospace, ionosphere and arctic region research with a white light camera and a radio wave spectrometer instrument which operates in the 1-10 mhz frequency... | ionosphere research with suomi100 cubesatellite's radio wave spectrometer |
as the high explosive pentaerythritol tetranitrate (petn) ages, its microstructure changes in the form of microcracks, grain sintering, crystal coarsening, and via other mechanisms, which affects its explosive performance. however, current methods to interrogate the microstructure can be time consuming, hard to perform... | nonlinear resonant ultrasound spectroscopy for nondestructive evaluation of thermally aged small pressed pellets |
wave propagation in rocks is typically treated as a linear elastic phenomenon; however, as strain increases, nonlinear stress-strain behavior can result. experimental evidence for nonlinear elastic behavior in geomaterials has existed for years, but the ability to use this property as a diagnostic tool has only begun d... | low-frequency nonlinear elasticity: a new tool for probing damage in rocks |
c onverging surface wave fields create a large-amplitude feature at the origin referred to as focal spot. its properties are governed by local medium properties and have long been used in medical imaging approaches such as passive elastography. modern dense seismic arrays consisting of many hundreds of sensors allow no... | refocusing surface wave fields resolve dispersion and anisotropy |
recently, induced seismicity by fluid injection (earthquakes caused by fluid injection in earth's subsurface) has been a major, new threat in the world with huge economic consequences. therefore, a computational framework is required to simulate how saturated porous media respond to fluid injection. a finite element me... | wave propagation simulation in poroelastic material with high order finite difference method (sbp) |
an arc-arc type collision between the northeastern (ne) japan arc and the kuril arc has formed hidaka collision zone (hcz) in south-central hokkaido japan. from detailed geologic information, it is known that kuril arc crust is thrusting westward on the ne japan arc along the hidaka main thrust (hmt). in order to inves... | reexamination for the subsurface structure beneath the southern part of the hidaka collision zone, hokkaido, japan by using a numerical test of wave propagation |
2d simulations of em wave-plasma interaction leading to complex scattering patterns are computationally expensive and challenging. the scattering pattern is primarily determined by the plasma density profile and the incident wave frequency. we propose a novel u-net based deep learning (dl) approach, with a series of en... | deep learning based approach for investigating electromagnetic wave propagation in plasmas |
computer generated holograms (cghs) used for ar/vr displays typically have poor image quality compared to their numerical reconstructions. the primary cause of these discrepancies can be attributed to over idealized wave propagation used for cgh generation. this problem is often exacerbated when the image is projected ... | camera feedback optimization of computer-generated holograms displayed by the texas instruments phase light modulator for ar/hud applications |
experimental and numerical studies on the soot characteristics of spray a flames were conducted with a focus on the effects of different split injection strategies in high-pressure high-temperature vessels within the engine combustion network. three high-speed imaging techniques were used to obtain the transient inform... | combined experimental and numerical studies on soot characteristics of diesel sprays with split injection strategies |
direct numerical simulation results of ionospheric plasma and mesopause airglow (oh and oi) responses to infrasonic acoustic waves (aws) generated by surface displacements during the 2016 kaikoura mw7.8 earthquake in new zealand are presented. to model realistic time-dependent surface displacement field resulting from ... | modeling of ionospheric plasma and mesopause airglow responses to infrasonic acoustic waves generated by strong inland earthquake |
we present our efforts to develop a new methodology for dense seismic arrays to extract geometrical information (size and volume) from geological targets utilizing techniques from material sciences and developing them for seismology. we provide a rapid tool to understand geology under dense seismic arrays using a synth... | a numerical experiment in small-angle scattering: from x-ray to seismology |
we report on results from the comparison of two algorithms designed to estimate the attenuation coefficient from ultrasonic b-mode scans obtained from a numerical phantom simulating an ultrasound breast scan. it is well documented that this parameter significantly diverges between normal tissue and malignant lesions. t... | estimation of tissue attenuation from ultrasonic b-mode images—spectral-log-difference and method-of-moments algorithms compared |
modern non-destructive techniques of wave analysis can be applied for the express preliminary geotechnical soil assessment. one of them is multichannel analysis of surface waves (masw) which allows obtaining velocities profile of shear waves and the initial shear modulus for the upper section promptly and at minimal la... | non-destructive method for preliminary assessment of deformation modulus of dispersive soils |
in light of recent results that have established that "steve" is the optical manifestation of a sub auroral ion drift (said), we are compelled to reassess our understanding of super dual auroral radar network (superdarn) echoes in the sub-auroral ionosphere during such events. there is a rich history of superdarn studi... | superdarn echo occurrence during "steve" events |
pipeline as one important mode of transportation, its safety is a very critical public concern. the acoustic emission (ae) played a very important role in pipeline safety inspection and monitoring due to its many advantages. moreover, ae is capable of localizing the defects in complex geometry in a real time, which is ... | the acoustic emission source localization in the pipeline network with consideration of radial position of defect |
structural health monitoring (shm) systems require integration of non-destructive technologies into structural design and operational processes. modeling and simulation of complex nde inspection processes are important aspects in the development and deployment of shm technologies. ray tracing techniques are vital simul... | modeling ultrasonic nde and guided wave based structural health monitoring |
in order to better understand the data observed by techniques in helioseismology, we implement a forward modeling approach using a newly developed 3d global numerical solver of the linearized compressible euler equations (3d glass) on a fully spherical mesh (0≤φ≤2π, 0≤θ≤π, 0≤r≤r). this algorithm simulates acoustic velo... | helioseismology techniques explored through 3d global modeling |
crack imaging is attractive in the community of nondestructive testing and structural health monitoring of plate-like structures. however, most existing research focuses on the imaging of single crack, while limited work has been reported for the imaging of multiple cracks. to this end, the application of the lamb wave... | imaging of multiple cracks in thin plates using circular sensor array based on lamb waves |
prior workers have hypothesized the various states and stability regimes of regolith-bound h2o-ice on mars based on the diffusion of atmospheric water vapor into the porous regolith of mars. such models rely upon the orbital dynamics of mars, especially obliquity variations, to determine periods of thermophysical stabi... | seismic experimentation to advance understanding of martian regolith-ice |
the graduate program in acoustics at penn state offers graduate degrees (m.eng., m.s., ph.d.) in acoustics, with courses and research opportunities in a wide variety of subfields. our 820 alumni are employed around the world in a wide variety of military and government labs, academic institutions, consulting firms, and... | the graduate program in acoustics at penn state |
thin multi-layered materials are widely used in key structures of many high technology industries. to ensure the quality and safety of structures, layer thickness measurement by non-destructive testing (ndt) techniques is essential. in this paper, a novel approach for the measurement of each layer's thickness in thin m... | simulation of layer thickness measurement in thin multi-layered material by variable-focus laser ultrasonic testing |
a multifield asymptotic homogenization technique for periodic thermo-diffusive elastic materials is provided in the present study. field equations for the first-order equivalent medium are derived and overall constitutive tensors are obtained in closed form. these lasts depend upon the micro constitutive properties of ... | wave propagation modeling in periodic elasto-thermo-diffusive materials via multifield asymptotic homogenization |
this paper reports an ultrasonic waveguide technique using u-shaped configurations to measure the fluid level. the longitudinal l(0,1) wave mode was propagated in the waveguide using through-transmission (tt) and pulse-echo (pe) techniques simultaneously using a single shear transducer. initially, we used the finite el... | enhancing the ultrasonic waveguide sensor's fluid level sensitivity using through-transmission and pulse-echo techniques simultaneously |
traditional lightning detection and location networks use the time of arrival (toa) technique to locate lightning events with a single time stamp. this contribution introduces a simulation study to lay the foundation for new lightning location concepts. here, a novel interferometric method is studied which expands the ... | long-range lightning interferometry using coherency |
the optical refractive imaging techniques quantitative schlieren and coherent gradient sensing are applied here to study shock wave propagation in optically transparent polymethyl methacrylate (pmma) samples. the approximately two-dimensional samples have holes and embedded metallic rods as inclusions with which the sh... | optical measurements of shock propagation in pmma around arrays of inclusions |
the fractional schrödinger–korteweg-de vries (s-kdv) equation is an important mathematical model that incorporates the nonlinear dynamics of the kdv equation with the quantum mechanical effects described by the schrödinger equation. motivated by the several applications of the mentioned evolution equation, in this inve... | on the solitary waves and nonlinear oscillations to the fractional schrödinger–kdv equation in the framework of the caputo operator |
the structures of short fiber reinforced composites become designable from macroscopic to microscopic due to the advancement in additive manufacturing technologies. the diffuse ultrasonic wave inspection benefits from information from multiple scattering processes, which is suitable for the quality assurance of complex... | numerical study of defect localization in additive manufactured short fiber reinforced composites with diffuse ultrasonic wave inspection |
this paper investigates the modelling of ultrasonic guided wave propagation in poly-crystalline materials (metallic, ceramic…) with the boundary element method. the dual boundary element method (dbem) formulation in elastodynamics is used. in particular, the formulation in laplace domain is implemented. the dbem is dev... | microstructural identification of poly-crystalline materials using the laplace domain dbem formulation for shm purposes |
transcranial focused ultrasound (fus) has gained significant attention as a non-invasive therapeutic technique that can reach both cortical and subcortical targets in the human brain. however, the skull barrier distorts the ultrasound beam and introduces significant losses that need to be accounted for. in this talk, i... | viscoelastic transcranial wave propagation modeling for neuronavigated focused ultrasound procedures in humans |
due to the fascinating effects of nonlinearity on the wave propagation and dynamic properties of periodic structures, nonlinear phononic crystals have been an important research topic in recent years. however, while a lot of efforts were devoted to the wave propagation analysis of nonlinear chains, 2d planar lattices w... | active control of wave propagation in nonlinear planar networks using piezoelectric actuation |
as ultrasonic testing (ut) becomes increasingly widespread, accurate numerical simulations of the complex wave propagation behavior in solids become increasingly useful. this is especially true for complex geometries and material properties created by new manufacturing processes such as those use to create additively m... | an open-source gpu-accelerated application of the elastodynamic finite integration technique (efit) to three-dimensional wave propagation and scattering in anisotropic materials of arbitrary geometries |
the d-region ionosphere (60-90 km) is critical for over-the-horizon radio wave propagation and is relied upon by many different communication and radar systems today. additionally, due to the sun's impact on the ionosphere, understanding what is going on in the ionosphere can provide insights into what is happening on ... | a look at unifying vlf transmitter and lightning-based d-region ionosphere remote sensing techniques |
a hybrid theoretical framework was developed to understand the wave propagation properties of acoustic black hole (abh) lattices, based on a combination of wkb theory and the high-frequency homogenization method. explicit approximate expressions were obtained for the associated dispersion curves. firstly, a matrix form... | high frequency homogenization for a one-dimensional acoustic black hole lattice |
salt structures play a critical role in hydrocarbon traps and underground storage. often, in seismic processing, the salt structures are considered as isotropic and homogeneous with constant velocities. however, this assumption is oversimplified because of the variabilities inside the salt body under the influence of d... | high-resolution laboratory study of the fractured salt strain field |
the surplus solar x-ray radiation during solar flares causes an enhancement of ionization in the lower ionospheric d-region and hence affects sub-ionospherically propagating very low frequency (vlf) radio wave signal amplitude and phase. vlf signal amplitude and dynamic phase perturbation (δ a) and amplitude time delay... | quantitative modeling of lower ionospheric response during solar x-ray events: a propagating radio wave simulation approach |
identification and quantification of fluid content in subduction zones remains challenging using elastic wave propagation alone. attenuation tomography is a promising tool for constraining the rock and pore fluid properties within subduction zones. however, a better understanding of seismic attenuation associated with ... | anelasticity of the orocopia schist under different effective pressures and temperatures. |
we extend the transfer matrix method to study the propagation of beams and arbitrary profiled fields through anisotropic metamaterial slabs, and to demonstrate the negative refractive index property resulting in linear self-focusing of beams in hyperbolic metamaterials. specifically, the transfer matrix method, commonl... | an anisotropic transfer matrix approach to profiled optical field propagation through hyperbolic metamaterials |
the d-region of the ionosphere is highly inaccessible; too high for continuous in-situ measurement techniques and too low for satellite measurements. very-low frequency (vlf) signals have been developed and used as a diagnostic tool for this region of the ionosphere and are favorable because of the low ionospheric atte... | characterizing d-region roughness using lf/mf signals of opportunity |
doug cato's research includes pioneering studies of the underwater acoustic environment surrounding australia and numerous contributions to our understanding of marine mammal acoustic behavior. moreover, his relaxed avuncular manner allowed him to assemble collaborations spanning disparate disciplines while mentoring t... | building bridges: doug cato's remarkable career spanning underwater acoustics and animal bioacoustics |
plasma structuring in the high-latitude ionosphere impacts over-the-horizon radio communication and global navigation systems, and are an important space weather effect. therefore, characterizing the formation and morphology of these structures is critically important. advanced modular incoherent scatter radars (isrs) ... | using novel multi-point incoherent scatter radar methods to resolve f-region high-latitude irregularity spectra |
the objects of consideration are thin linearly elastic kirchhoff-love-type circular cylindrical shells having a periodically microheterogeneous structure in circumferential and axial directions (biperiodic shells). the aim of this contribution is to study a certain long wave propagation problem related to micro-fluctua... | micro-vibrations and wave propagation in biperiodic cylindrical shells |
the radio occultation technique is one of the most useful methods to retrieve vertical temperature profiles in planetary atmospheres. ultra-stable oscillator (uso) onboard venus climate orbiter, akatsuki, enables us to investigate the thermal structure of the venus atmosphere between about 40-90 km levels. it is expect... | local time dependence of the thermal structure in the venusian equatorial region revealed by akatsuki radio occultation measurements |
helioseismic flare waves (""sunquakes"") occur due to localized force or/and momentum impacts observed during the flare impulsive phase in the lower atmosphere. such impacts may be caused by precipitation of high-energy particles, downward traveling shock wave, or by magnetic lorentz force associated with plasma erupti... | helioseismic effects of solar flares in cycle 24 |
for underwater active target detection, using conventional machine learning technique is limited and unsuitable because of small training data samples and diversity of environment. therefore, to apply conventional machine learning for underwater acoustics target detection, three methodologies can be manipulated (1) fea... | effective feature fusion via analysis of quantitative similarity matrices among various acoustic features for underwater active target detection |
this paper addresses a numerical approach for computing the solitary wave solutions of the generalized rosenau–kawahara–rlw model established by coupling the generalized rosenau–kawahara and rosenau–rlw equations. the solution of this model is accomplished by using the finite difference approach and the upwind local ra... | solitary wave propagation of the generalized rosenau–kawahara–rlw equation in shallow water theory with surface tension |
while in the classical theory of whispering gallery waves it is assumed that they propagate along a cylindrical perfectly reflecting wall, in many real situations it is important to consider similar waves propagating along penetrable interfaces or curvilinear level sets of the refractive index. an example of waves of t... | on uniform asymptotic approximations of whispering gallery modes propagating along curved penetrable interfaces |
surface plasmon polaritons (spps) play an important role in modern nanophotonics due to their vectorial characteristics, subwavelength scale and field enhancement natures. up to now, a great deal of advanced scheme has been proposed to character the intensity distributions of spps, it remains challenging to achieve the... | sorting transverse and longitudinal plasmonic fields by a structure of metal-nanoparticle-on-film |
the gas-coupled laser acoustic detection (gclad) is an optical technique for ultrasonic detection based on the deviation that a laser beam sustains when travelling in a fluid that features refractive index fluctuations. if the laser beam is perpendicular to the wave propagation direction, the technique enables simultan... | line scanning with gas-coupled laser acoustic detection |
laser damage performance is an important parameter to evaluate the quality of high power laser optical components. understanding the physical mechanism of the interaction between laser and optical material is of great significance for improving the laser damage resistance of optical elements. for nanosecond pulsed lase... | transient dynamics measurement of light-material interaction for laser optics |
among the few exactly solvable problems in theoretical physics, the 2d (two-dimensional) newtonian free fall problem in euclidean space is perhaps the least known as compared to the harmonic oscillator or the kepler–coulomb problems. the aim of this article is to revisit this problem at the classical level as well as t... | dynamical symmetries of the 2d newtonian free fall problem revisited |
in low-energy environments, the water–sediment interface often contains a dynamic fluffy transition layer (ftl) of suspended organic and inorganic matter, which is transformed by complex physical, biological, and chemical processes. the ftl mechanical properties are important for understanding carbon cycle dynamics and... | shear and scholte wave measurements on surficial intertidal mudflat sediments using medical sonoelastography techniques |
joining metallic materials with dynamic welding techniques (e.g. impact welding) provides a means to metallurgically bond material via mechanical mixing, extreme deformation rates, and local material instability. process variables of interest include the selected metals, dimension, impact velocity, and impact angle. ev... | local dynamic effects on impact welding process window variability |
laser ultrasonic line source methods have been used to study elastic anisotropy in nuclear graphites by measuring shear wave birefringence. depending on the manufacturing processes used during production, nuclear graphites can exhibit various degrees of material anisotropy related to preferred crystallite orientation a... | theory and application of laser ultrasonic shear wave birefringence measurements to the determination of microstructure orientation in transversely isotropic, polycrystalline graphite materials |
many lung diseases are associated with dramatic changes in mechanical properties of the lung. chest radiographs and computed tomography (ct) are the most common clinical methods for evaluating lung disease, but they are expensive, use radiation, and do not measure lung stiffness. shear wave elastography (swe) uses ultr... | noninvasive measurement of lung elastic properties |
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