WorldWideScience

Sample records for polarized surface wave

  1. Optical coating on a corrugated surface to align the polarization of an unpolarized wave without loss

    Science.gov (United States)

    Jen, Yi Jun

    2017-12-01

    A multilayer comprising birefringent thin films is devised to present to function as a polarization beam splitter and waveplate simultaneously. By arranging such a multilayer on a right triangle-shaped corrugated surface, a polarizer is realized to align the randomly oscillating electric field of an unpolarized wave into a linear polarized wave without loss.

  2. Excitation of a surface wave by an s-polarized electromagnetic wave incident upon a boundary of a dense magnetoactive plasma

    International Nuclear Information System (INIS)

    Dragila, R.; Vukovic, S.

    1988-01-01

    The properties of surfave waves that are associated with a boundary between a rare plasma and a dense magnetoactive plasma and that propagate along a dc magnetic field are investigated. It is shown that the presence of the magnetic field introduces symmetry in terms of the polarization of the incident electromagnetic wave that excites the surface waves. A surface wave excited by an incident p-polarized (s-polarized) electromagnetic wave leaks in the form of an s-polarized (p-polarized) electromagnetic wave. The rate of rotation of polarization is independent of the polarization of the incident wave. Because a surface wave can leak in the form of an s-polarized electromagnetic wave, it can also be pumped by such a wave, and conditions were found for excitation of a surface wave by an s-polarized incident electromagnetic wave

  3. Modifications of Surface Wave Discrimination Filter Based on the Polarization Properties

    International Nuclear Information System (INIS)

    Kutlu, Y. A.; Sayil, N.

    2007-01-01

    The polarization properties of Love and Rayleigh waves are utilized to design Surface Wave Discrimination Filter. Filtering process for a selected window length and moving interval is that the amplitudes at each frequency on vertical, radial and transverse components are weighted according to how closely the theoretical three-dimensional particle motion pattern. In this study, weighted functions have been modified for epicenteral distances smaller than about 2200 km to corresponding with angular distribution of polarization parameters obtained from computed synthetic seismograms. Modified Surface Wave Discrimination Filter has been tested on synthetic seismograms and digital three-components broadband records at Trabzon earthquake station

  4. Depth of anisotropy in the North American craton from surface wave polarizations

    Science.gov (United States)

    Maupin, V.; Pettersen, O.

    2009-04-01

    Analysis of P-wave traveltimes has shown the the North American craton is characterized by a coherent pattern of anisotropy with significant dip of the fast axis in some regions. The depth distribution of the anisotropy is however little constrained by P-wave analysis, limiting the geodynamical interpretation of the model. Surface wave polarizations are very sensitive to dip of anisotropy and can provide the missing depth-constraint to the model. We present an analysis of surface wave polarizations recorded at a number of stations on the North American craton. We show that the frequency range in which we do not observe polarization anomalies implies that the dipping anisotropy is not located in the upper part of the lithosphere.

  5. Dispersion and Polarization of Surface Waves Trapped in High Aspect Ratio Electrode Arrays

    DEFF Research Database (Denmark)

    Laude, Vincent; Dühring, Maria Bayard; Moubchir, Hanane

    2007-01-01

    .Phys., 90(5):2492, 2001; Appl. Phys. Lett., 89:083515, 2006.) an experimental and theoretical analysis of the transduction of SAW under a metallic array of electrodes with a large aspect ratio on a piezoelectric substrate, whereby allowing the electrode height to become larger than one wavelength...... additional results on the polarization and the dispersion of the surface waves trapped by high aspect ratio electrode arrays. A finite element model, including periodic boundary conditions along the propagation direction and a perfectly matched layer (PML) to absorb waves away from the surface...... wave vector values....

  6. Conversion of terahertz wave polarization at the boundary of a layered superconductor due to the resonance excitation of oblique surface waves.

    Science.gov (United States)

    Averkov, Yu O; Yakovenko, V M; Yampol'skii, V A; Nori, Franco

    2012-07-13

    We predict a complete TM↔TE transformation of the polarization of terahertz electromagnetic waves reflected from a strongly anisotropic boundary of a layered superconductor. We consider the case when the wave is incident on the superconductor from a dielectric prism separated from the sample by a thin vacuum gap. The physical origin of the predicted phenomenon is similar to the Wood anomalies known in optics and is related to the resonance excitation of the oblique surface waves. We also discuss the dispersion relation for these waves, propagating along the boundary of the superconductor at some angle with respect to the anisotropy axis, as well as their excitation by the attenuated-total-reflection method.

  7. Conversion from surface wave to surface wave on reflection

    DEFF Research Database (Denmark)

    Novitsky, Andrey

    2010-01-01

    can be transmitted without changing its direction (nevertheless the amplitude varies). For other media parameters, only normally incident surface waves can be converted to surface waves. We propose applications of the predicted conversion as a beam splitter and polarization filter for surface waves.......We discuss the reflection and transmission of an incident surface wave to a pure surface wave state at another interface. This is allowed only for special media parameters: at least one of the media must be magnetic. We found such material characteristics that the obliquely incident surface wave...

  8. Comment on `The azimuthal dependence of surface wave polarization in a slightly anisotropic medium' by T. Tanimoto

    Science.gov (United States)

    Maupin, Valérie

    2004-10-01

    This comment points out that the simple azimuthal dependence of the polarization anomalies derived in a recent paper by Tanimoto may not be valid for the Love wave fundamental mode in oceanic or tectonic regions as a result of strong coupling with the first Rayleigh wave overtone. More generally, I also point out the fact that polarization anomalies reflect partly the anisotropy away from the station and that this usually complicates the azimuthal pattern observed at single stations.

  9. Polarized seismic and solitary waves run-up at the sea bed

    Energy Technology Data Exchange (ETDEWEB)

    Dennis, L. C.C.; Zainal, A. A.; Faisal, S. Y. [Universiti Teknologi PETRONAS, 31750 Tronoh, Perak (Malaysia); Universiti Teknologi Malaysia, 81310 Johor Bahru (Malaysia)

    2012-09-26

    The polarization effects in hydrodynamics are studied. Hydrodynamic equation for the nonlinear wave is used along with the polarized solitary waves and seismic waves act as initial waves. The model is then solved by Fourier spectral and Runge-Kutta 4 methods, and the surface plot is drawn. The output demonstrates the inundation behaviors. Consequently, the polarized seismic waves along with the polarized solitary waves tend to generate dissimilar inundation which is more disastrous.

  10. Explaining polarization reversals in STEREO wave data

    Science.gov (United States)

    Breneman, A.; Cattell, C.; Wygant, J.; Kersten, K.; Wilson, L. B., III; Dai, L.; Colpitts, C.; Kellogg, P. J.; Goetz, K.; Paradise, A.

    2012-04-01

    Recently, Breneman et al. (2011) reported observations of large amplitude lightning and transmitter whistler mode waves from two STEREO passes through the inner radiation belt (L plane transverse to the magnetic field showed that the transmitter waves underwent periodic polarization reversals. Specifically, their polarization would cycle through a pattern of right-hand to linear to left-hand polarization at a rate of roughly 200 Hz. The lightning whistlers were observed to be left-hand polarized at frequencies greater than the lower hybrid frequency and less than the transmitter frequency (21.4 kHz) and right-hand polarized otherwise. Only right-hand polarized waves in the inner radiation belt should exist in the frequency range of the whistler mode and these reversals were not explained in the previous paper. We show, with a combination of observations and simulated wave superposition, that these polarization reversals are due to the beating of an incident electromagnetic whistler mode wave at 21.4 kHz and linearly polarized, symmetric lower hybrid sidebands Doppler-shifted from the incident wave by ±200 Hz. The existence of the lower hybrid waves is consistent with the parametric decay mechanism of Lee and Kuo (1984) whereby an incident whistler mode wave decays into symmetric, short wavelength lower hybrid waves and a purely growing (zero-frequency) mode. Like the lower hybrid waves, the purely growing mode is Doppler-shifted by ˜200 Hz as observed on STEREO. This decay mechanism in the upper ionosphere has been previously reported at equatorial latitudes and is thought to have a direct connection with explosive spread F enhancements. As such it may represent another dissipation mechanism of VLF wave energy in the ionosphere and may help to explain a deficit of observed lightning and transmitter energy in the inner radiation belts as reported by Starks et al. (2008).

  11. Surfing surface gravity waves

    Science.gov (United States)

    Pizzo, Nick

    2017-11-01

    A simple criterion for water particles to surf an underlying surface gravity wave is presented. It is found that particles travelling near the phase speed of the wave, in a geometrically confined region on the forward face of the crest, increase in speed. The criterion is derived using the equation of John (Commun. Pure Appl. Maths, vol. 6, 1953, pp. 497-503) for the motion of a zero-stress free surface under the action of gravity. As an example, a breaking water wave is theoretically and numerically examined. Implications for upper-ocean processes, for both shallow- and deep-water waves, are discussed.

  12. Viscoelastic Surface Waves

    Science.gov (United States)

    Borcherdt, R. D.

    2007-12-01

    General theoretical solutions for Rayleigh- and Love-Type surface waves in viscoelastic media describe physical characteristics of the surface waves in elastic as well as anelastic media with arbitrary amounts of intrinsic absorption. In contrast to corresponding physical characteristics for Rayleigh waves in elastic media, Rayleigh- Type surface waves in anelastic media demonstrate; 1) tilt of the particle motion orbit that varies with depth, and 2) amplitude and volumetric strain distributions with superimposed sinusoidal variations that decay exponentially with depth. Each characteristic is dependent on the amount of intrinsic absorption and the chosen model of viscoelasticity. Distinguishing characteristics of anelastic Love-Type surface waves include: 1) dependencies of the wave speed and absorption coefficient on the chosen model and amount of intrinsic absorption and frequency, and 2) superimposed sinusoidal amplitude variations with an exponential decay with depth. Numerical results valid for a variety of viscoelastic models provide quantitative estimates of the physical characteristics of both types of viscoelastic surface waves appropriate for interpretations pertinent to models of earth materials ranging from low-loss in the crust to moderate- and high-loss in water-saturated soils.

  13. Parsimonious Surface Wave Interferometry

    KAUST Repository

    Li, Jing

    2017-10-24

    To decrease the recording time of a 2D seismic survey from a few days to one hour or less, we present a parsimonious surface-wave interferometry method. Interferometry allows for the creation of a large number of virtual shot gathers from just two reciprocal shot gathers by crosscoherence of trace pairs, where the virtual surface waves can be inverted for the S-wave velocity model by wave-equation dispersion inversion (WD). Synthetic and field data tests suggest that parsimonious wave-equation dispersion inversion (PWD) gives S-velocity tomograms that are comparable to those obtained from a full survey with a shot at each receiver. The limitation of PWD is that the virtual data lose some information so that the resolution of the S-velocity tomogram can be modestly lower than that of the S-velocity tomogram inverted from a conventional survey.

  14. Dyakonov surface waves

    DEFF Research Database (Denmark)

    Takayama, Osamu; Crasovan, Lucian Cornel; Johansen, Steffen Kjær

    2008-01-01

    The interface of two semi-infinite media, where at least one of them is a birefringent crystal, supports a special type of surface wave that was predicted theoretically by D'yakonov in 1988. Since then, the properties of such waves, which exist in transparent media only under very special...... conditions, have been analyzed in different geometries and settings. Nevertheless, they are still awaiting experimental demonstration. The most important advances in this topic are briefly discussed in this review, pointing out aspects that have not been clearly covered by the literature. Finally......, the existence of these surface waves in specific material examples is analyzed, discussing the challenge posed by their experimental observation....

  15. Explaining Polarization Reversals in STEREO Wave Data

    Science.gov (United States)

    Breneman, A.; Cattell, C.; Wygant, J.; Kersten, K.; Wilson, L, B., III; Dai, L.; Colpitts, C.; Kellogg, P. J.; Goetz, K.; Paradise, A.

    2012-01-01

    Recently Breneman et al. reported observations of large amplitude lightning and transmitter whistler mode waves from two STEREO passes through the inner radiation belt (Lpaper. We show, with a combination of observations and simulated wave superposition, that these polarization reversals are due to the beating of an incident electromagnetic whistler mode wave at 21.4 kHz and linearly polarized, symmetric lower hybrid sidebands Doppler-shifted from the incident wave by +/-200 Hz. The existence of the lower hybrid waves is consistent with the parametric decay mechanism of Lee and Kuo whereby an incident whistler mode wave decays into symmetric, short wavelength lower hybrid waves and a purely growing (zero-frequency) mode. Like the lower hybrid waves, the purely growing mode is Doppler-shifted by 200 Hz as observed on STEREO. This decay mechanism in the upper ionosphere has been previously reported at equatorial latitudes and is thought to have a direct connection with explosive spread F enhancements. As such it may represent another dissipation mechanism of VLF wave energy in the ionosphere and may help to explain a deficit of observed lightning and transmitter energy in the inner radiation belts as reported by Starks et al.

  16. Anomalous Surface Wave Launching by Handedness Phase Control

    KAUST Repository

    Zhang, Xueqian

    2015-10-09

    Anomalous launch of a surface wave with different handedness phase control is achieved in a terahertz metasurface based on phase discontinuities. The polarity of the phase profile of the surface waves is found to be strongly correlated to the polarization handedness, promising polarization-controllable wavefront shaping, polarization sensing, and environmental refractive-index sensing. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Surface Acoustic Wave Devices

    DEFF Research Database (Denmark)

    Dühring, Maria Bayard

    application is modulation of optical waves in waveguides. This presentation elaborates on how a SAW is generated by interdigital transducers using a 2D model of a piezoelectric, inhomogeneous material implemented in the high-level programming language Comsol Multiphysics. The SAW is send through a model......The work of this project is concerned with the simulation of surface acoustic waves (SAW) and topology optimization of SAW devices. SAWs are elastic vibrations that propagate along a material surface and are extensively used in electromechanical filters and resonators in telecommunication. A new...

  18. Polarizer design for millimeter-wave plasma diagnostics

    DEFF Research Database (Denmark)

    Leipold, Frank; Salewski, Mirko; Jacobsen, Asger Schou

    2013-01-01

    by birefringent windows, the microwave receivers can be designed to be more compact at lower cost. Sapphire windows (a-cut) as well as grooved high density polyethylene windows can serve this purpose. The sapphire window can be designed such that the calculated transmission of the wave energy is better than 99......Radiation from magnetized plasmas is in general elliptically polarized. In order to convert the elliptical polarization to linear polarization, mirrors with grooved surfaces are currently employed in our collective Thomson scattering diagnostic at ASDEX Upgrade. If these mirrors can be substituted...

  19. the effect of surface polarity

    Indian Academy of Sciences (India)

    Abstract. An implant material when comes in contact with blood fluids (e.g., blood and lymph), adsorb proteins spontaneously on its surface. Notably, blood coagulation is influenced by many factors, including mainly chemical structure and polarity (charge) of the material. The present study describes the methodology to ...

  20. Artificial TE-mode surface waves at metal surfaces mimicking surface plasmons.

    Science.gov (United States)

    Sun, Zhijun; Zuo, Xiaoliu; Guan, Tengpeng; Chen, Wei

    2014-02-24

    Manipulation of light in subwavelength scale can be realized with metallic nanostructures for TM-polarization components due to excitation of surface plasmons. TE-polarization components of light are usually excluded in subwavelength metal structures for mesoscopic optical interactions. Here we show that, by introducing very thin high index dielectric layers on structured metal surfaces, pseudo surface polarization currents can be induced near metal surfaces, which bring to excitation of artificial TE-mode surface waves at the composite meta-surfaces. This provides us a way to manipulate TE-polarized light in subwavelength scale. Typical properties of the artificial surface waves are further demonstrate for their excitation, propagation, optical transmission, and enhancement and resonances of the localized fields, mimicking those of surface plasmon waves.

  1. Nonlinear radiation of waves at combination frequencies due to radiation-surface wave interaction in plasmas

    International Nuclear Information System (INIS)

    El Naggar, I.A.; Hussein, A.M.; Khalil, Sh.M.

    1992-09-01

    Electromagnetic waves radiated with combination frequencies from a semi-bounded plasma due to nonlinear interaction of radiation with surface wave (both of P-polarization) has been investigated. Waves are radiated both into vacuum and plasma are found to be P-polarized. We take into consideration the continuity at the plasma boundary of the tangential components of the electric field of the waves. The case of normal incidence of radiation and rarefield plasma layer is also studied. (author). 7 refs

  2. Electron Cyclotron Waves Polarization in the TJII Stellarator

    Energy Technology Data Exchange (ETDEWEB)

    Cappa, A.; Martinez-Fernandez, J.; Wagner, D.

    2013-05-01

    This report describes the theoretical calculations related with the electron cyclotron (EC) waves polarization control in the TJII stellarator. Two main aspects will be distinguished: the determination of the vacuum polarization that the wave must exhibit if a given propagation mode in a cold plasma is desired and the calculation of the behavior of the grooved polarizers and other transmission systems used to launch the vacuum wave with the required polarization. (Author) 13 refs.

  3. Surface Waves on Metamaterials Interfaces

    DEFF Research Database (Denmark)

    Takayama, Osamu; Shkondin, Evgeniy; Panah, Mohammad Esmail Aryaee

    2016-01-01

    We analyze surface electromagnetic waves supported at the interface between isotropic medium and effective anisotropic material that can be realized by alternating conductive and dielectrics layers. This configuration can host various types of surface waves and therefore can serve as a rich...... platform for applications of surface photonics. Most of these surface waves are directional and as such their propagation can be effectively controlled by changing wavelength or material parameters tuning....

  4. Light-matter interactions in a polarization standing wave

    OpenAIRE

    Fang, X.; MacDonald, K.F.; Zheludev, N.I.

    2015-01-01

    We report on the application of polarization standing waves (PSW) to the coherent control of light-matter interactions in planar photonic nanostructures. Such waves, formed by counter-propagating (linear or circular) orthogonally polarized beams can uniquely detect polarization conversion, planar chirality and related asymmetric transmission effects.

  5. Eigenwave spectrum of surface acoustic waves on a rough self-affine fractal surface

    NARCIS (Netherlands)

    Palasantzas, George

    1994-01-01

    The propagation of a sound wave along a statistically rough solid-vacuum interface is investigated for the case of self-affine fractals. The wave-number relation ω=ω(k) is examined for the transverse polarized surface wave. The range of existence of this wave is analyzed as a function of the degree

  6. Switching the response of metasurfaces in polarization standing waves

    OpenAIRE

    Fang, X.; MacDonald, K.F.; Zheludev, N.I.

    2015-01-01

    We demonstrate experimentally that standing waves of polarization, as opposed to intensity, can be engaged to coherently control light-matter interactions in planar photonic nanostructures, presenting unique opportunities for all-optical data processing and polarization-dependent molecular spectroscopy. Such waves, formed by counter-propagating (linear or circular) orthogonally polarized beams can, for example, uniquely detect polarization conversion, planar chirality and related asymmetric t...

  7. Metasurfaces for Terahertz Waves Polarization Control

    DEFF Research Database (Denmark)

    Lavrinenko, Andrei; Malureanu, Radu; Zalkovskij, Maksim

    in the visible, near infrared or microwave regimes these issues in principle have strong alternatives via a conventional optics or electromagnetic approaches, at terahertz (THz) frequencies metamaterials are often considered as being the unique solution for the encountered problems. Several approaches involving...... that the maximal conversion efficiency with a single metamaterial surface is 50 % in transmission and up to 90% in reflection. However, a double layer transmission converter and a single layer with a metallic mirror can have 100% polarization conversion efficiency. We tested our conclusions numerically reaching...

  8. Freely tunable broadband polarization rotator for terahertz waves.

    Science.gov (United States)

    Fan, Ren-Hao; Zhou, Yu; Ren, Xiao-Ping; Peng, Ru-Wen; Jiang, Shang-Chi; Xu, Di-Hu; Xiong, Xiang; Huang, Xian-Rong; Wang, Mu

    2015-02-18

    A freely tunable polarization rotator for broadband terahertz waves is demonstrated using a three-rotating-layer metallic grating structure, which can conveniently rotate the polarization of a linearly polarized terahertz wave to any desired direction with nearly perfect conversion efficiency. This low-cost, high-efficiency, and freely tunable device has potential applications as material analysis, wireless communication, and THz imaging. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Polarization-controlled asymmetric excitation of surface plasmons

    KAUST Repository

    Xu, Quan

    2017-08-28

    Free-space light can be coupled into propagating surface waves at a metal–dielectric interface, known as surface plasmons (SPs). This process has traditionally faced challenges in preserving the incident polarization information and controlling the directionality of the excited SPs. The recently reported polarization-controlled asymmetric excitation of SPs in metasurfaces has attracted much attention for its promise in developing innovative plasmonic devices. However, the unit elements in these works were purposely designed in certain orthogonal polarizations, i.e., linear or circular polarizations, resulting in limited two-level polarization controllability. Here, we introduce a coupled-mode theory to overcome this limit. We demonstrated theoretically and experimentally that, by utilizing the coupling effect between a pair of split-ring-shaped slit resonators, exotic asymmetric excitation of SPs can be obtained under the x-, y-, left-handed circular, and right-handed circular polarization incidences, while the polarization information of the incident light can be preserved in the excited SPs. The versatility of the presented design scheme would offer opportunities for polarization sensing and polarization-controlled plasmonic devices.

  10. Polarization-resolved characterization of plasmon waves supported by an anisotropic metasurface

    DEFF Research Database (Denmark)

    Samusev, Anton; Mukhin, Ivan; Malureanu, Radu

    2017-01-01

    Optical metasurfaces have great potential to form a platform for manipulation of surface waves. A plethora of advanced surface-wave phenomena such as negative refraction, self-collimation and channeling of 2D waves can be realized through on-demand engineering of dispersion properties of a periodic...... metasurface. In this letter, we report on polarization-resolved measurement of dispersion of plasmon waves supported by an anisotropic metasurface. We demonstrate that a subdiffractive array of strongly coupled resonant plasmonic nanoparticles supports both TE and TM plasmon modes at optical frequencies...... polarization degree of freedom for surface waves, our results open new routes for designing planar on-chip devices for surface photonics....

  11. Surface Acoustic Wave Devices

    DEFF Research Database (Denmark)

    Dühring, Maria Bayard

    application is modulation of optical waves in waveguides. This presentation elaborates on how a SAW is generated by interdigital transducers using a 2D model of a piezoelectric, inhomogeneous material implemented in the high-level programming language Comsol Multiphysics. The SAW is send through a model...

  12. Capillary waves with surface viscosity

    Science.gov (United States)

    Shen, Li; Denner, Fabian; Morgan, Neal; van Wachem, Berend; Dini, Daniele

    2017-11-01

    Experiments over the last 50 years have suggested a correlation between the surface (shear) viscosity and the stability of a foam or emulsion. With recent techniques allowing more accurate measurements of the elusive surface viscosity, we examine this link theoretically using small-amplitude capillary waves in the presence of the Marangoni effect and surface viscosity modelled via the Boussinesq-Scriven model. The surface viscosity effect is found to contribute a damping effect on the amplitude of the capillary wave with subtle differences to the effect of the convective-diffusive Marangoni transport. The general wave dispersion is augmented to take into account the Marangoni and surface viscosity effects, and a first-order correction to the critical damping wavelength is derived. The authors acknowledge the financial support of the Shell University Technology Centre for fuels and lubricants.

  13. Atmosphere-surface interactions over polar oceans and heterogeneous surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Vihma, T.

    1995-12-31

    Processes of interaction between the atmospheric boundary layer and the planetary surface have been studied with special emphasis on polar ocean surfaces: the open ocean, leads, polynyas and sea ice. The local exchange of momentum, heat and moisture has been studied experimentally both in the Weddell Sea and in the Greenland Sea. Exchange processes over heterogeneous surfaces are addressed by modelling studies. Over a homogeneous surface, the local turbulent fluxes can be reasonably well estimated using an iterative flux-profile scheme based on the Monin-Obukhov similarity theory. In the Greenland Sea, the near-surface air temperature and the generally small turbulent fluxes over the open ocean were affected by the sea surface temperature fronts. Over the sea ice cover in the Weddell Sea, the turbulent sensible heat flux was generally downwards, and together with an upward oceanic heat flux through the ice it compensated the heat loss from the surface via long-wave radiation. The wind dominated on time scales of days, while the current became important on longer time scales. The drift dynamics showed apparent spatial differences between the eastern and western regions, as well as between the Antarctic Circumpolar Current and the rest of the Weddell Sea. Inertial motion was present in regions of low ice concentration. The surface heterogeneity, arising e.g. from roughness or temperature distribution, poses a problem for the parameterization of surface exchange processes in large-scale models. In the case of neutral flow over a heterogeneous terrain, an effective roughness length can be used to parameterize the roughness effects

  14. Dust-acoustic waves modulational instability and rogue waves in a polarized dusty plasma

    Energy Technology Data Exchange (ETDEWEB)

    Bouzit, Omar; Tribeche, Mouloud [Faculty of Physics, Theoretical Physics Laboratory, Plasma Physics Group, University of Bab-Ezzouar, USTHB, B.P. 32, El Alia, Algiers 16111 (Algeria)

    2015-10-15

    The polarization force-induced changes in the dust-acoustic waves (DAWs) modulational instability (MI) are examined. Using the reductive perturbation method, the nonlinear Schrödinger equation that governs the MI of the DAWs is obtained. It is found that the effect of the polarization term R is to narrow the wave number domain for the onset of instability. The amplitude of the wave envelope decreases as R increases, meaning that the polarization force effects render weaker the associated DA rogue waves. The latter may therefore completely damp in the vicinity of R ∼ 1, i.e., as the polarization force becomes close to the electrostatic one (the net force acting on the dust particles becomes vanishingly small). The DA rogue wave profile is very sensitive to any change in the restoring force acting on the dust particles. It turns out that the polarization effects may completely smear out the DA rogue waves.

  15. The Probing Radio Signal Polarization Effect on Separation Efficiency of Surface Target Response

    Directory of Open Access Journals (Sweden)

    A. N. Pinchuk

    2015-01-01

    Full Text Available The aim of the study was a quantitative analysis of the level of interference with radar monitoring characteristics of surface targets, caused by the scattered electromagnetic field, arising due to the interaction between radio waves and sea surface, which is a study aspect a radiooceanography encompasses. Backscatter signal, arising from the interaction of radio waves and sea surface, extends in a direction opposite the probing radar signal of spread marine and coastal radar stations.With radar sounding of sea surface at high incidence angles of radio waves, a basic physical mechanism to form the received signal is resonant (Bragg scattering, and at small incidence angles of radio waves it is quasi-specular reflection. Consequently, the energy of electromagnetic radiation, backscattered by the sea surface, depends on the type of wave polarization: for horizontal polarization it is less than for vertical one.The paper presents a mathematical model, which describes dependence of interference level caused by interaction between radio waves and sea surface, on the radio wave polarization for the case when the same polarization is used to sent-out and receive a radio wave.To determine the noise reduction to be achievable with radar monitoring the surface targets by selecting the polarization of the probing radar signal, a signal/noise ratio is analyzed for its different polarizations.It is shown that in order to reduce the noise level caused by the interaction between radio waves and sea surface, it is possible to use the differences in the level of scattered radio signals of different polarization: with horizontally-polarized radar operation at incidence angles of 75°- 85° a signal/noise ratio is by 20-35 dB higher than that of vertically- polarized one.

  16. Polarization Statistics on 0.01 Hz Waves in the Lunar Plasma Environment

    Science.gov (United States)

    Howard, S. K.; Halekas, J. S.; Harada, Y.; Farrell, W. M.; McFadden, J. P.; Glassmeier, K. H.

    2017-12-01

    One generating mechanism for waves in the lunar plasma environment is through the process of resonant interactions with non-solar wind ions. In particular, this mechanism is believed to be a main generator of waves that lie near the ion cyclotron frequency; around 0.01 Hz. Both left-handed and right-handed polarization in the spacecraft frame has been observed for waves in this frequency range. Due to the effects of Doppler shift from the solar wind, the intrinsic polarization of the waves is not necessarily the same as their polarization in the spacecraft frame. A significant source of non-solar wind ions is incoming solar wind protons that are reflected by localized crustal magnetic fields on the lunar surface. Previous statistical studies have looked at the distribution of non-solar wind ions and 0.01 Hz waves around the Moon, and how they are influenced by the interplanetary magnetic field (IMF) direction. Here we investigate the polarization statistics of 0.01 Hz waves around the Moon using ARTEMIS data from August 2011 through December 2016. Initial statistics on observation rates and location indicate that waves that appear left-hand polarized in the spacecraft frame are more common and have a broader spatial distribution around the Moon; waves that appear right-hand polarized are less frequently observed and are more centralized to the dawn side of the Moon. We further investigate how the distributions are related to IMF direction and lunar phase, and we make comparisons between non-solar wind ion distributions and polarization distributions. Additionally, we use a combination of wave analysis and ion tracing simulations to examine the intrinsic properties of these waves.

  17. Dispersion properties of transverse waves in electrically polarized BECs

    International Nuclear Information System (INIS)

    Andreev, Pavel A; Kuz'menkov, L S

    2014-01-01

    Further development of the method of quantum hydrodynamics in applications for Bose–Einstein condensates (BECs) is presented. To consider the evolution of polarization direction along with particle movement, we have developed a corresponding set of quantum hydrodynamic equations. It includes equations of the polarization evolution and the polarization-current evolution along with the continuity equation and the Euler equation (the momentum-balance equation). Dispersion properties of the transverse waves, including the electromagnetic waves propagating through the BECs, are considered. To this end, we consider a full set of the Maxwell equations for the description of electromagnetic field dynamics. This approximation gives us the possibility of considering the electromagnetic waves along with the matter waves. We find a splitting of the electromagnetic-wave dispersion on two branches. As a result, we have four solutions, two for the electromagnetic waves and two for the matter waves; the last two are the concentration-polarization waves appearing as a generalization of the Bogoliubov mode. We also find that if the matter wave propagates perpendicular to the external electric field then the dipolar contribution does not disappear (as it follows from our generalization of the Bogoliubov spectrum). A small dipolar frequency shift exists in this case due to the transverse electric field of perturbation. (paper)

  18. Scattering of a TEM wave from a time varying surface

    Science.gov (United States)

    Elcrat, Alan R.; Harder, T. Mark; Stonebraker, John T.

    1990-03-01

    A solution is given for reflection of a plane wave with TEM polarization from a planar surface with time varying properties. These properties are given in terms of the currents on the surface. The solution is obtained by numerically solving a system of differential-delay equations in the time domain.

  19. Statistics of polarization and Stokes parameters of stochastic waves

    Science.gov (United States)

    Hole, M. J.; Robinson, P. A.; Cairns, Iver H.

    2004-09-01

    Several theories now exist to describe the probability distribution functions (PDFs) for the electric field strength, intensity, and power of signals. In this work, a model is developed for the PDFs of the polarization properties of the superposition of multiple transverse wave populations. The polarization of each transverse wave population is described by a polarization ellipse with fixed axial ratio and polarization angle, and PDFs for the field strength and phase. Wave populations are vectorially added, and expressions found for the Stokes parameters I , U , Q , and V , as well as the degrees of linear and circular polarization, and integral expressions for their statistics. In this work, lognormal distributions are chosen for the electric field, corresponding to stochastic growth, and polarization PDFs are numerically calculated for the superposition of orthonormal mode populations, which might represent the natural modes emitted by a source. Examples are provided of the superposition of linear, circular, and elliptically polarized wave populations in cases where the component field strength PDFs are the same, and where one field strength PDF is dominant.

  20. Polarization speckles and generalized Stokes vector wave: a review [invited

    DEFF Research Database (Denmark)

    Takeda, Mitsuo; Wang, Wei; Hanson, Steen Grüner

    2010-01-01

    Stokes parameters proposed by Korotkova and Wolf, and introduce its time-domain representation to describe the space-time evolution of the correlation between random electric vector fields at two different space-time points. This time-domain generalized Stokes vector, with components similar to those......We review some of the statistical properties of polarization-related speckle phenomena, with an introduction of a less known concept of polarization speckles and their spatial degree of polarization. As a useful means to characterize twopoint vector field correlations, we review the generalized...... of the beam coherence polarization matrix proposed by Gori, is shown to obey the wave equation in exact analogy to a coherence function of scalar fields. Because of this wave nature, the time-domain generalized Stokes vector is referred to as generalized Stokes vector wave in this paper....

  1. Effect of magnetic field on nonlinear interactions of electromagnetic and surface waves in a plasma layer

    International Nuclear Information System (INIS)

    Khalil, Sh.M.; El-Sherif, N.; El-Siragy, N.M.; Tanta Univ.; El-Naggar, I.A.; Alexandria Univ.

    1985-01-01

    Investigation is made for nonlinear interaction between incident radiation and a surface wave in a magnetized plasma layer. Both interacting waves are of P polarization. The generated currents and fields at combination frequencies are obtained analytically. Unlike the S-polarized interacting waves, the magnetic field affects the fundamental waves and leads to an amplification of generated waves when their frequencies approach the cyclotron frequency. (author)

  2. Multiband Circular Polarizer Based on Fission Transmission of Linearly Polarized Wave for X-Band Applications

    Directory of Open Access Journals (Sweden)

    Farman Ali Mangi

    2016-01-01

    Full Text Available A multiband circular polarizer based on fission transmission of linearly polarized wave for x-band application is proposed, which is constructed of 2 × 2 metallic strips array. The linear-to-circular polarization conversion is obtained by decomposing the linearly incident x-polarized wave into two orthogonal vector components of equal amplitude and 90° phase difference between them. The innovative approach of “fission transmission of linear-to-circular polarized wave” is firstly introduced to obtain giant circular dichroism based on decomposition of orthogonal vector components through the structure. It means that the incident linearly polarized wave is converted into two orthogonal components through lower printed metallic strips layer and two transmitted waves impinge on the upper printed strips layer to convert into four orthogonal vector components at the end of structure. This projection and transmission sequence of orthogonal components sustain the chain transmission of electromagnetic wave and can achieve giant circular dichroism. Theoretical analysis and microwave experiments are presented to validate the performance of the structure. The measured results are in good agreement with simulation results. In addition, the proposed circular polarizer exhibits the optimal performance with respect to the normal incidence. The right handed circularly polarized wave is emitted ranging from 10.08 GHz to 10.53 GHz and 10.78 GHz to 11.12 GHz, while the left handed circular polarized wave is excited at 10.54 GHz–10.70 GHz and 11.13 GHz–11.14 GHz, respectively.

  3. Spiky soliton in circular polarized Alfven wave

    International Nuclear Information System (INIS)

    Ichikawa, Y.H.; Sanuki, H.; Konno, K.; Wadati, M.

    1979-06-01

    A new type of nonlinear evolution equation for the Alfven waves, propagating parallel to the magnetic field, is now registered to the completely integrable family of nonlinear evolution equations. In spite of the extensive studies of Kaup and Newell, and of Kawata and Inoue, these analysis have been dealing with solutions for restricted boundary conditions. The present paper presents full account of stationary solitary wave solutions for the plane wave boundary condition. The obtained results exhibit peculiar structure of spiky modulation of amplitude and phase, which arises from the derivative nonlinear coupling term. A nonlinear equation for complex amplitude associated with the carrier wave is shown to be a mixed type of nonlinear Schroedinger equation, having and ordinary cubic nonlinear term and the derivative of cubic nonlinear term. (author)

  4. Circularly polarized millimeter-wave imaging for personnel screening

    Science.gov (United States)

    Sheen, David M.; McMakin, Douglas L.; Lechelt, Wayne M.; Griffin, Jeffrey W.

    2005-05-01

    A novel polarimetric millimeter-wave imaging technique has been developed at the Pacific Northwest National Laboratory (PNNL) for concealed weapon detection applications. Wideband millimeter-wave imaging systems developed at PNNL utilize low-power, coherent, millimeter-wave illumination in the 10-100 GHz range to form high-resolution images of personnel. Electromagnetic waves in these frequency ranges easily penetrate most clothing materials and are reflected from the body and any concealed items. Three-dimensional images are formed using computer image reconstruction algorithms developed to mathematically focus the received wavefronts scattered from the target. Circular polarimetric imaging can be employed to obtain additional information from the target. Circularly polarized waves incident on relatively smooth reflecting targets are typically reversed in their rotational handedness, e.g. left-hand circular polarization (LHCP) is reflected to become right-hand circular polarization (RHCP). An incident wave that is reflected twice (or any even number) of times prior to returning to the transceiver, has its handedness preserved. Sharp features such as wires and edges tend to return linear polarization, which can be considered to be a sum of both LHCP and RHCP. These characteristics can be exploited for personnel screening by allowing differentiation of smooth features, such as the body, and sharper features present in many concealed items. Additionally, imaging artifacts due to multipath can be identified and eliminated. Laboratory imaging results have been obtained in the 10-20 GHz frequency range and are presented in this paper.

  5. Wave Equation Inversion of Skeletonized SurfaceWaves

    KAUST Repository

    Zhang, Zhendong

    2015-08-19

    We present a surface-wave inversion method that inverts for the S-wave velocity from the Rayleigh dispersion curve for the fundamental-mode. We call this wave equation inversion of skeletonized surface waves because the dispersion curve for the fundamental-mode Rayleigh wave is inverted using finite-difference solutions to the wave equation. The best match between the predicted and observed dispersion curves provides the optimal S-wave velocity model. Results with synthetic and field data illustrate the benefits and limitations of this method.

  6. Databases of surface wave dispersion

    Directory of Open Access Journals (Sweden)

    L. Boschi

    2005-06-01

    Full Text Available Observations of seismic surface waves provide the most important constraint on the elastic properties of the Earth’s lithosphere and upper mantle. Two databases of fundamental mode surface wave dispersion were recently compiled and published by groups at Harvard (Ekström et al., 1997 and Utrecht/Oxford (Trampert and Woodhouse, 1995, 2001, and later employed in 3-d global tomographic studies. Although based on similar sets of seismic records, the two databases show some significant discrepancies. We derive phase velocity maps from both, and compare them to quantify the discrepancies and assess the relative quality of the data; in this endeavour, we take careful account of the effects of regularization and parametrization. At short periods, where Love waves are mostly sensitive to crustal structure and thickness, we refer our comparison to a map of the Earth’s crust derived from independent data. On the assumption that second-order effects like seismic anisotropy and scattering can be neglected, we find the measurements of Ekström et al. (1997 of better quality; those of Trampert and Woodhouse (2001 result in phase velocity maps of much higher spatial frequency and, accordingly, more difficult to explain and justify geophysically. The discrepancy is partly explained by the more conservative a priori selection of data implemented by Ekström et al. (1997. Nevertheless, it becomes more significant with decreasing period, which indicates that it could also be traced to the different measurement techniques employed by the authors.

  7. Studies of nanosecond pulse surface ionization wave discharges over solid and liquid dielectric surfaces

    International Nuclear Information System (INIS)

    Petrishchev, Vitaly; Leonov, Sergey; Adamovich, Igor V

    2014-01-01

    Surface ionization wave discharges generated by high-voltage nanosecond pulses, propagating over a planar quartz surface and over liquid surfaces (distilled water and 1-butanol) have been studied in a rectangular cross section test cell. The discharge was initiated using a custom-made, alternating polarity, high-voltage nanosecond pulse plasma generator, operated at a pulse repetition rate of 100–500 Hz, with a pulse peak voltage and current of 10–15 kV and 7–20 A, respectively, a pulse FWHM of ∼100 ns, and a coupled pulse energy of 2–9 mJ/pulse. Wave speed was measured using a capacitive probe. ICCD camera images demonstrated that the ionization wave propagated predominantly over the quartz wall or over the liquid surface adjacent to the grounded waveguide placed along the bottom wall of the test cell. Under all experimental conditions tested, the surface plasma ‘sheet’ was diffuse and fairly uniform, both for positive and negative polarities. The parameters of ionization wave discharge propagating over distilled water and 1-butanol surfaces were close to those of the discharge over a quartz wall. No perturbation of the liquid surface by the discharge was detected. In most cases, the positive polarity surface ionization wave propagated at a higher speed and over a longer distance compared to the negative polarity wave. For all three sets of experiments (surface ionization wave discharge over quartz, water and 1-butanol), wave speed and travel distance decreased with pressure. Diffuse, highly reproducible surface ionization wave discharge was also observed over the liquid butanol–saturated butanol vapor interface, as well as over the distilled water–saturated water vapor interface, without buffer gas flow. No significant difference was detected between surface ionization discharges sustained using single-polarity (positive or negative), or alternating polarity high-voltage pulses. Plasma emission images yielded preliminary evidence of charge

  8. Detectability of inflationary gravitational waves with microwave background polarization

    International Nuclear Information System (INIS)

    Kamionkowski, M.; Kosowsky, A.

    1998-01-01

    Inflation predicts specific relations between the amplitudes and spectral indices of the primordial spectrum of density (scalar metric) perturbations and gravitational waves (tensor metric perturbations). Detection of a stochastic gravitational-wave background is essential for identifying this unmistakable signature. Polarization of the cosmic microwave background can isolate these tensor modes in a model-independent way and thereby circumvent the cosmic-variance limit to detecting a small tensor signal with only a temperature map. Here we assess the detectability of a gravity-wave background with a temperature and polarization map. For detector sensitivities better than 10 endash 20μK√ (sec) , the sensitivity to a tensor signal is always dominated by the polarization map. With a detector sensitivity of order 1μK√ (sec) , polarization could improve on a temperature-map sensitivity to tensor modes by two to three orders of magnitude. Even a small amount of reionization substantially enhances tensor-mode detectability. We also argue that the sensitivity of the Planck Surveyor to tensor modes is significantly improved with polarization, even taking into account the resulting degradation of the intensity determination in the high-frequency channels. copyright 1997 The American Physical Society

  9. Estimation of the gravitational wave polarizations from a nontemplate search

    Science.gov (United States)

    Di Palma, Irene; Drago, Marco

    2018-01-01

    Gravitational wave astronomy is just beginning, after the recent success of the four direct detections of binary black hole (BBH) mergers and the first observation from a binary neutron star inspiral, with the expectation of many more events to come. Given the possibility to detect waves from not exactly modeled astrophysical processes, it is fundamental to be ready to calculate the polarization waveforms in the case of searches using nontemplate algorithms. In such a case, the waveform polarizations are the only quantities that contain direct information about the generating process. We present the performance of a new valuable tool to estimate the inverse solution of gravitational wave transient signals, starting from the analysis of the signal properties of a nontemplate algorithm that is open to a wider class of gravitational signals not covered by template algorithms. We highlight the contributions to the wave polarization associated with the detector response, the sky localization, and the polarization angle of the source. In this paper we present the performances of such a method and its implications by using two main classes of transient signals, resembling the limiting case for most simple and complicated morphologies. The performances are encouraging for the tested waveforms: the correlation between the original and the reconstructed waveforms spans from better than 80% for simple morphologies to better than 50% for complicated ones. For a nontemplate search these results can be considered satisfactory to reconstruct the astrophysical progenitor.

  10. Modeling Gravitational Waves to Test GR Dispersion and Polarization

    Science.gov (United States)

    Tso, Rhondale; Chen, Yanbei; Isi, Maximilliano

    2017-01-01

    Given continued observation runs from the Laser Interferometer Gravitational-Wave Observatory Scientific Collaboration, further gravitational wave (GW) events will provide added constraints on beyond-general relativity (b-GR) theories. One approach, independent of the GW generation mechanism at the source, is to look at modification to the GW dispersion and propagation, which can accumulate over vast distances. Generic modification of GW propagation can also, in certain b-GR theories, impact the polarization content of GWs. To this end, a comprehensive approach to testing the dispersion and polarization content is developed by modeling anisotropic deformations to the waveforms' phase, along with birefringence effects and corollary consequences for b-GR polarizations, i.e., breathing, vector, and longitudinal modes. Such an approach can be mapped to specific theories like Lorentz violation, amplitude birefringence in Chern-Simons, and provide hints at additional theories to be included. An overview of data analysis routines to be implemented will also be discussed.

  11. Stimulated polarization wave process in spin 3/2 chains

    International Nuclear Information System (INIS)

    Furman, G. B.

    2007-01-01

    Stimulated wave of polarization, triggered by a flip of a single spin, presents a simple model of quantum amplification. Recently, it has been demonstrated that, in an idealized one-dimensional Ising spin 1/2 chain with nearest-neighbor interactions and realistic spin 1/2 chain including the natural dipole-dipole interactions, irradiated by a weak resonant transverse field, a wave of flipped spins can be triggered by a single spin flip. Here we focuse on control of polarization wave in chain of spin 3/2, where the nuclear quadrupole interaction is dominant. Results of simulations for 1D spin chains and rings with up to five spins are presented.

  12. Polarization-Directed Surface Plasmon Polariton Launching

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Yu; Joly, Alan G.; El-Khoury, Patrick Z.; Hess, Wayne P.

    2017-01-05

    The relative intensities of propagating surface plasmons (PSPs) simultaneously launched from opposing edges of a symmetric trench structure etched into a silver thin film may be controllably varied by tuning the linear polarization of the driving field. This is demonstrated through transient multiphoton photoemission electron microscopy measurements performed using a pair of spatially separated phase-locked femtosecond pulses. Our measurements are rationalized using finite-difference time domain simulations, which reveal that the coupling efficiency into the PSP modes is inversely proportional to the magnitude of the localized surface plasmon fields excited at the trench edges. Additional experiments on single step edges also show asymmetric PSP launching with respect to polarization, analogous to the trench results. Our combined experimental and computational results allude to the interplay between localized and propagating surface plasmon modes in the trench; strong coupling to the localized modes at the edges correlates to weak coupling to the PSP modes. Simultaneous excitation of the electric fields localized at both edges of the trench results in complex interactions between the right- and left-side PSP modes with Fabry-Perot and cylindrical modes. This results in a trench width-dependent PSP intensity ratio using otherwise identical driving fields. A systematic exploration of polarization directed PSP launching from a series of trench structures reveals an optimal PSP contrast ratio of 4.2 using a 500 nm-wide trench.

  13. Photonics surface waves on metamaterials interfaces

    DEFF Research Database (Denmark)

    Takayama, Osamu; Bogdanov, Andrey; Lavrinenko, Andrei V

    2017-01-01

    A surface wave (SW) in optics is a light wave, which is supported at an interface of two dissimilar media and propagates along the interface with its field amplitude exponentially decaying away from the boundary. The research on surface waves has been flourishing in last few decades thanks to the...

  14. ANALYTICAL SOLUTION FOR WAVES IN PLANETS WITH ATMOSPHERIC SUPERROTATION. II. LAMB, SURFACE, AND CENTRIFUGAL WAVES

    Energy Technology Data Exchange (ETDEWEB)

    Peralta, J.; López-Valverde, M. A. [Instituto de Astrofísica de Andalucía (CSIC), Glorieta de la Astronomía, 18008 Granada (Spain); Imamura, T. [Institute of Space and Astronautical Science-Japan Aerospace Exploration Agency 3-1-1, Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Read, P. L. [Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford (United Kingdom); Luz, D. [Centro de Astronomia e Astrofísica da Universidade de Lisboa (CAAUL), Observatório Astronómico de Lisboa, Tapada da Ajuda, 1349-018 Lisboa (Portugal); Piccialli, A., E-mail: peralta@iaa.es [LATMOS, UVSQ, 11 bd dAlembert, 78280 Guyancourt (France)

    2014-07-01

    This paper is the second in a two-part study devoted to developing tools for a systematic classification of the wide variety of atmospheric waves expected on slowly rotating planets with atmospheric superrotation. Starting with the primitive equations for a cyclostrophic regime, we have deduced the analytical solution for the possible waves, simultaneously including the effect of the metric terms for the centrifugal force and the meridional shear of the background wind. In those cases where the conditions for the method of the multiple scales in height are met, these wave solutions are also valid when vertical shear of the background wind is present. A total of six types of waves have been found and their properties were characterized in terms of the corresponding dispersion relations and wave structures. In this second part, we study the waves' solutions when several atmospheric approximations are applied: Lamb, surface, and centrifugal waves. Lamb and surface waves are found to be quite similar to those in a geostrophic regime. By contrast, centrifugal waves turn out to be a special case of Rossby waves that arise in atmospheres in cyclostrophic balance. Finally, we use our results to identify the nature of the waves behind atmospheric periodicities found in polar and lower latitudes of Venus's atmosphere.

  15. Surface waves on metal-dielectric metamaterials

    DEFF Research Database (Denmark)

    Takayama, Osamu; Shkondin, Evgeniy; Panah, Mohammad Esmail Aryaee

    2016-01-01

    of surface waves and, therefore, can serve as a platform allowing many applications for surface photonics. Most of these surface waves are directional and their propagation direction is sensitive to permittivities of the media forming the interface. Hence, their propagation can be effectively controlled...... by changing a wavelength or material parameters. We discover that two new types of surface waves with complex dispersion exist for a uniaxial medium with both negative ordinary and extraordinary permittivities. Such new surface wave solutions originate from the anisotropic permittivities of the uniaxial media...

  16. SURFACE ALFVEN WAVES IN SOLAR FLUX TUBES

    Energy Technology Data Exchange (ETDEWEB)

    Goossens, M.; Andries, J.; Soler, R.; Van Doorsselaere, T. [Centre for Plasma Astrophysics, Department of Mathematics, Katholieke Universiteit Leuven, Celestijnenlaan 200B, 3001 Leuven (Belgium); Arregui, I.; Terradas, J., E-mail: marcel.goossens@wis.kuleuven.be [Solar Physics Group, Departament de Fisica, Universitat de les Illes Balears, E-07122 Palma de Mallorca (Spain)

    2012-07-10

    Magnetohydrodynamic (MHD) waves are ubiquitous in the solar atmosphere. Alfven waves and magneto-sonic waves are particular classes of MHD waves. These wave modes are clearly different and have pure properties in uniform plasmas of infinite extent only. Due to plasma non-uniformity, MHD waves have mixed properties and cannot be classified as pure Alfven or magneto-sonic waves. However, vorticity is a quantity unequivocally related to Alfven waves as compression is for magneto-sonic waves. Here, we investigate MHD waves superimposed on a one-dimensional non-uniform straight cylinder with constant magnetic field. For a piecewise constant density profile, we find that the fundamental radial modes of the non-axisymmetric waves have the same properties as surface Alfven waves at a true discontinuity in density. Contrary to the classic Alfven waves in a uniform plasma of infinite extent, vorticity is zero everywhere except at the cylinder boundary. If the discontinuity in density is replaced with a continuous variation of density, vorticity is spread out over the whole interval with non-uniform density. The fundamental radial modes of the non-axisymmetric waves do not need compression to exist unlike the radial overtones. In thin magnetic cylinders, the fundamental radial modes of the non-axisymmetric waves with phase velocities between the internal and the external Alfven velocities can be considered as surface Alfven waves. On the contrary, the radial overtones can be related to fast-like magneto-sonic modes.

  17. Swimming using surface acoustic waves.

    Directory of Open Access Journals (Sweden)

    Yannyk Bourquin

    Full Text Available Microactuation of free standing objects in fluids is currently dominated by the rotary propeller, giving rise to a range of potential applications in the military, aeronautic and biomedical fields. Previously, surface acoustic waves (SAWs have been shown to be of increasing interest in the field of microfluidics, where the refraction of a SAW into a drop of fluid creates a convective flow, a phenomenon generally known as SAW streaming. We now show how SAWs, generated at microelectronic devices, can be used as an efficient method of propulsion actuated by localised fluid streaming. The direction of the force arising from such streaming is optimal when the devices are maintained at the Rayleigh angle. The technique provides propulsion without any moving parts, and, due to the inherent design of the SAW transducer, enables simple control of the direction of travel.

  18. Electrokinetics of Polar Liquids in Contact with Non-Polar Surfaces

    OpenAIRE

    Lin, Chih-Hsiu; Ferguson, Gregory S.; Chaudhury, Manoj K.

    2014-01-01

    Zeta potentials of several polar protic (water, ethylene glycol, formamide) as well as polar aprotic (dimethyl sulfoxide) liquids were measured in contact with three non-polar surfaces using closed-cell electro-osmosis. The test surfaces were chemisorbed monolayers of alkyl siloxanes, fluoroalkyl siloxanes and polydimethylsiloxanes (PDMS) grafted on glass slides. All these liquids exhibited substantial electrokinetics in contact with the non-polar surfaces with these observations: the electro...

  19. Electric field vector measurements in a surface ionization wave discharge

    International Nuclear Information System (INIS)

    Goldberg, Benjamin M; Adamovich, Igor V; Lempert, Walter R; Böhm, Patrick S; Czarnetzki, Uwe

    2015-01-01

    This work presents the results of time-resolved electric field vector measurements in a short pulse duration (60 ns full width at half maximum), surface ionization wave discharge in hydrogen using a picosecond four-wave mixing technique. Electric field vector components are measured separately, using pump and Stokes beams linearly polarized in the horizontal and vertical planes, and a polarizer placed in front of the infrared detector. The time-resolved electric field vector is measured at three different locations across the discharge gap, and for three different heights above the alumina ceramic dielectric surface, ∼100, 600, and 1100 μm (total of nine different locations). The results show that after breakdown, the discharge develops as an ionization wave propagating along the dielectric surface at an average speed of 1 mm ns −1 . The surface ionization wave forms near the high voltage electrode, close to the dielectric surface (∼100 μm). The wave front is characterized by significant overshoot of both vertical and horizontal electric field vector components. Behind the wave front, the vertical field component is rapidly reduced. As the wave propagates along the dielectric surface, it also extends further away from the dielectric surface, up to ∼1 mm near the grounded electrode. The horizontal field component behind the wave front remains quite significant, to sustain the electron current toward the high voltage electrode. After the wave reaches the grounded electrode, the horizontal field component experiences a secondary rise in the quasi-dc discharge, where it sustains the current along the near-surface plasma sheet. The measurement results indicate presence of a cathode layer formed near the grounded electrode with significant cathode voltage fall, ≈3 kV, due to high current density in the discharge. The peak reduced electric field in the surface ionization wave is 85–95 Td, consistent with dc breakdown field estimated from the Paschen

  20. Primordial gravitational waves measurements and anisotropies of CMB polarization rotation

    Directory of Open Access Journals (Sweden)

    Si-Yu Li

    2015-12-01

    Full Text Available Searching for the signal of primordial gravitational waves in the B-modes (BB power spectrum is one of the key scientific aims of the cosmic microwave background (CMB polarization experiments. However, this could be easily contaminated by several foreground issues, such as the interstellar dust grains and the galactic cyclotron electrons. In this paper we study another mechanism, the cosmic birefringence, which can be introduced by a CPT-violating interaction between CMB photons and an external scalar field. Such kind of interaction could give rise to the rotation of the linear polarization state of CMB photons, and consequently induce the CMB BB power spectrum, which could mimic the signal of primordial gravitational waves at large scales. With the recently released polarization data of BICEP2 and the joint analysis data of BICEP2/Keck Array and Planck, we perform a global fitting analysis on constraining the tensor-to-scalar ratio r by considering the polarization rotation angle [α(nˆ] which can be separated into a background isotropic part [α¯] and a small anisotropic part [Δα(nˆ]. Since the data of BICEP2 and Keck Array experiments have already been corrected by using the “self-calibration” method, here we mainly focus on the effects from the anisotropies of CMB polarization rotation angle. We find that including Δα(nˆ in the analysis could slightly weaken the constraints on the tensor-to-scalar ratio r, when using current CMB polarization measurements. We also simulate the mock CMB data with the BICEP3-like sensitivity. Very interestingly, we find that if the effects of the anisotropic polarization rotation angle could not be taken into account properly in the analysis, the constraints on r will be dramatically biased. This implies that we need to break the degeneracy between the anisotropies of the CMB polarization rotation angle and the CMB primordial tensor perturbations, in order to measure the signal of primordial

  1. An Empirical Algorithm for Wave Retrieval from Co-Polarization X-Band SAR Imagery

    Directory of Open Access Journals (Sweden)

    Weizeng Shao

    2017-07-01

    Full Text Available In this study, we proposed an empirical algorithm for significant wave height (SWH retrieval from TerraSAR-X/TanDEM (TS-X/TD-X X-band synthetic aperture radar (SAR co-polarization (vertical-vertical (VV and horizontal-horizontal (HH images. As the existing empirical algorithm at X-band, i.e., XWAVE, is applied for wave retrieval from HH-polarization TS-X/TD-X image, polarization ratio (PR has to be used for inverting wind speed, which is treated as an input in XWAVE. Wind speed encounters saturation in tropical cyclone. In our work, wind speed is replaced by normalized radar cross section (NRCS to avoiding using SAR-derived wind speed, which does not work in high winds, and the empirical algorithm can be conveniently implemented without converting NRCS in HH-polarization to NRCS in VV-polarization by using X-band PR. A total of 120 TS-X/TD-X images, 60 in VV-polarization and 60 in HH-polarization, with homogenous wave patterns, and the coincide significant wave height data from European Centre for Medium-Range Weather Forecasts (ECMWF reanalysis field at a 0.125° grid were collected as a dataset for tuning the algorithm. The range of SWH is from 0 to 7 m. We then applied the algorithm to 24 VV and 21 HH additional SAR images to extract SWH at locations of 30 National Oceanic and Atmospheric Administration (NOAA National Data Buoy Center (NDBC buoys. It is found that the algorithm performs well with a SWH stander deviation (STD of about 0.5 m for both VV and HH polarization TS-X/TD-X images. For large wave validation (SWH 6–7 m, we applied the empirical algorithm to a tropical cyclone Sandy TD-X image acquired in 2012, and obtained good result with a SWH STD of 0.3 m. We concluded that the proposed empirical algorithm works for wave retrieval from TS-X/TD-X image in co-polarization without external sea surface wind information.

  2. Gravitational Wave Polarizations in f (R Gravity and Scalar-Tensor Theory

    Directory of Open Access Journals (Sweden)

    Gong Yungui

    2018-01-01

    Full Text Available The detection of gravitational waves by the Laser Interferometer Gravitational-Wave Observatory opens a new era to use gravitational waves to test alternative theories of gravity. We investigate the polarizations of gravitational waves in f (R gravity and Horndeski theory, both containing scalar modes. These theories predict that in addition to the familiar + and × polarizations, there are transverse breathing and longitudinal polarizations excited by the massive scalar mode and the new polarization is a single mixed state. It would be very difficult to detect the longitudinal polarization by interferometers, while pulsar timing array may be the better tool to detect the longitudinal polarization.

  3. Gravitational Wave Polarizations in f (R) Gravity and Scalar-Tensor Theory

    Science.gov (United States)

    Gong, Yungui; Hou, Shaoqi

    2018-01-01

    The detection of gravitational waves by the Laser Interferometer Gravitational-Wave Observatory opens a new era to use gravitational waves to test alternative theories of gravity. We investigate the polarizations of gravitational waves in f (R) gravity and Horndeski theory, both containing scalar modes. These theories predict that in addition to the familiar + and × polarizations, there are transverse breathing and longitudinal polarizations excited by the massive scalar mode and the new polarization is a single mixed state. It would be very difficult to detect the longitudinal polarization by interferometers, while pulsar timing array may be the better tool to detect the longitudinal polarization.

  4. Ultrafast Ultrasound Imaging With Cascaded Dual-Polarity Waves.

    Science.gov (United States)

    Zhang, Yang; Guo, Yuexin; Lee, Wei-Ning

    2018-04-01

    Ultrafast ultrasound imaging using plane or diverging waves, instead of focused beams, has advanced greatly the development of novel ultrasound imaging methods for evaluating tissue functions beyond anatomical information. However, the sonographic signal-to-noise ratio (SNR) of ultrafast imaging remains limited due to the lack of transmission focusing, and thus insufficient acoustic energy delivery. We hereby propose a new ultrafast ultrasound imaging methodology with cascaded dual-polarity waves (CDWs), which consists of a pulse train with positive and negative polarities. A new coding scheme and a corresponding linear decoding process were thereby designed to obtain the recovered signals with increased amplitude, thus increasing the SNR without sacrificing the frame rate. The newly designed CDW ultrafast ultrasound imaging technique achieved higher quality B-mode images than coherent plane-wave compounding (CPWC) and multiplane wave (MW) imaging in a calibration phantom, ex vivo pork belly, and in vivo human back muscle. CDW imaging shows a significant improvement in the SNR (10.71 dB versus CPWC and 7.62 dB versus MW), penetration depth (36.94% versus CPWC and 35.14% versus MW), and contrast ratio in deep regions (5.97 dB versus CPWC and 5.05 dB versus MW) without compromising other image quality metrics, such as spatial resolution and frame rate. The enhanced image qualities and ultrafast frame rates offered by CDW imaging beget great potential for various novel imaging applications.

  5. Wave scattering from statistically rough surfaces

    CERN Document Server

    Bass, F G; ter Haar, D

    2013-01-01

    Wave Scattering from Statistically Rough Surfaces discusses the complications in radio physics and hydro-acoustics in relation to wave transmission under settings seen in nature. Some of the topics that are covered include radar and sonar, the effect of variations in topographic relief or ocean waves on the transmission of radio and sound waves, the reproduction of radio waves from the lower layers of the ionosphere, and the oscillations of signals within the earth-ionosphere waveguide. The book begins with some fundamental idea of wave transmission theory and the theory of random processes a

  6. Excitation of surface plasma waves over corrugated slow-wave ...

    Indian Academy of Sciences (India)

    elements in metal waveguides increase the number of their natural modes and give rise to new effects accompanying wave propagation, e.g. excitation of SPW in these waveguides. Such large area surface wave plasma sources have been reported using a microwave launcher of large aperture formed on a waveguide, ...

  7. Excitation of surface plasma waves over corrugated slow-wave ...

    Indian Academy of Sciences (India)

    Abstract. A microwave propagating along vacuum–dielectric–plasma interface excites surface plasma wave (SPW). A periodic slow-wave structure placed over dielectric slows down the SPW. The phase velocity of slow SPW is sensitive to height, periodicity, number of periods, thickness and the separation between ...

  8. Polarization speed meter for gravitational-wave detection

    Science.gov (United States)

    Wade, Andrew R.; McKenzie, Kirk; Chen, Yanbei; Shaddock, Daniel A.; Chow, Jong H.; McClelland, David E.

    2012-09-01

    We propose a modified configuration of an advanced gravitational-wave detector that is a speed-meter-type interferometer with improved sensitivity with respect to quantum noise. With the addition of polarization-controlling components to the output of an arm cavity Michelson interferometer, an orthogonal polarization state of the interferometer can be used to store signal, returning it later with opposite phase to cancel position information below the storage bandwidth of the opposite mode. This modification provides an alternative to an external kilometer-scale Fabry-Pérot cavity, as presented in earlier work of Purdue and Chen [Phys. Rev. D 66, 122004 (2002)]. The new configuration requires significantly less physical infrastructure to achieve speed meter operation. The quantity of length and alignment degrees of freedom is also reduced. We present theoretical calculations to show that such a speed meter detector is capable of beating the strain sensitivity imposed by the standard quantum limit over a broad range of frequencies for Advanced Laser Interferometer Gravitational-wave Observatory-like parameters. The benefits and possible difficulties of implementing such a scheme are outlined. We also present results for tuning of the speed meter by adjusting the degree of polarization coupling, a novel possibility that does not exist in previously proposed designs, showing that there is a smooth transition from speed meter operation to that of a signal-recycling Michelson behavior.

  9. Skeletonized wave-equation Qs tomography using surface waves

    KAUST Repository

    Li, Jing

    2017-08-17

    We present a skeletonized inversion method that inverts surface-wave data for the Qs quality factor. Similar to the inversion of dispersion curves for the S-wave velocity model, the complicated surface-wave arrivals are skeletonized as simpler data, namely the amplitude spectra of the windowed Rayleigh-wave arrivals. The optimal Qs model is then found that minimizes the difference in the peak frequencies of the predicted and observed Rayleigh wave arrivals using a gradient-based wave-equation optimization method. Solutions to the viscoelastic wave-equation are used to compute the predicted Rayleigh-wave arrivals and the misfit gradient at every iteration. This procedure, denoted as wave-equation Qs tomography (WQs), does not require the assumption of a layered model and tends to have fast and robust convergence compared to Q full waveform inversion (Q-FWI). Numerical examples with synthetic and field data demonstrate that the WQs method can accurately invert for a smoothed approximation to the subsur-face Qs distribution as long as the Vs model is known with sufficient accuracy.

  10. Wave-equation Qs Inversion of Skeletonized Surface Waves

    KAUST Repository

    Li, Jing

    2017-02-08

    We present a skeletonized inversion method that inverts surface-wave data for the Qs quality factor. Similar to the inversion of dispersion curves for the S-wave velocity model, the complicated surface-wave arrivals are skeletonized as simpler data, namely the amplitude spectra of the windowed Rayleigh-wave arrivals. The optimal Qs model is the one that minimizes the difference in the peak frequencies of the predicted and observed Rayleigh wave arrivals using a gradient-based wave-equation optimization method. Solutions to the viscoelastic wave-equation are used to compute the predicted Rayleigh-wave arrivals and the misfit gradient at every iteration. This procedure, denoted as wave-equation Qs inversion (WQs), does not require the assumption of a layered model and tends to have fast and robust convergence compared to full waveform inversion (FWI). Numerical examples with synthetic and field data demonstrate that the WQs method can accurately invert for a smoothed approximation to the subsurface Qs distribution as long as the Vs model is known with sufficient accuracy.

  11. Skeletonized wave equation of surface wave dispersion inversion

    KAUST Repository

    Li, Jing

    2016-09-06

    We present the theory for wave equation inversion of dispersion curves, where the misfit function is the sum of the squared differences between the wavenumbers along the predicted and observed dispersion curves. Similar to wave-equation travel-time inversion, the complicated surface-wave arrivals in traces are skeletonized as simpler data, namely the picked dispersion curves in the (kx,ω) domain. Solutions to the elastic wave equation and an iterative optimization method are then used to invert these curves for 2D or 3D velocity models. This procedure, denoted as wave equation dispersion inversion (WD), does not require the assumption of a layered model and is less prone to the cycle skipping problems of full waveform inversion (FWI). The synthetic and field data examples demonstrate that WD can accurately reconstruct the S-wave velocity distribution in laterally heterogeneous media.

  12. Shallow water sound propagation with surface waves.

    Science.gov (United States)

    Tindle, Chris T; Deane, Grant B

    2005-05-01

    The theory of wavefront modeling in underwater acoustics is extended to allow rapid range dependence of the boundaries such as occurs in shallow water with surface waves. The theory allows for multiple reflections at surface and bottom as well as focusing and defocusing due to reflection from surface waves. The phase and amplitude of the field are calculated directly and used to model pulse propagation in the time domain. Pulse waveforms are obtained directly for all wavefront arrivals including both insonified and shadow regions near caustics. Calculated waveforms agree well with a reference solution and data obtained in a near-shore shallow water experiment with surface waves over a sloping bottom.

  13. Identification of the Rayleigh surface waves for estimation of viscoelasticity using the surface wave elastography technique.

    Science.gov (United States)

    Zhang, Xiaoming

    2016-11-01

    The purpose of this Letter to the Editor is to demonstrate an effective method for estimating viscoelasticity based on measurements of the Rayleigh surface wave speed. It is important to identify the surface wave mode for measuring surface wave speed. A concept of start frequency of surface waves is proposed. The surface wave speeds above the start frequency should be used to estimate the viscoelasticity of tissue. The motivation was to develop a noninvasive surface wave elastography (SWE) technique for assessing skin disease by measuring skin viscoelastic properties. Using an optical based SWE system, the author generated a local harmonic vibration on the surface of phantom using an electromechanical shaker and measured the resulting surface waves on the phantom using an optical vibrometer system. The surface wave speed was measured using a phase gradient method. It was shown that different standing wave modes were generated below the start frequency because of wave reflection. However, the pure symmetric surface waves were generated from the excitation above the start frequency. Using the wave speed dispersion above the start frequency, the viscoelasticity of the phantom can be correctly estimated.

  14. Mutual conversion of bulk and surface acoustic waves in gratings of finite length on half-infinite substrates. I. FE analysis of surface wave generation.

    Science.gov (United States)

    Darinskii, A N; Weihnacht, M; Schmidt, H

    2013-07-01

    A numerical study is carried out of the surface acoustic wave generation by a bulk acoustic wave in a half-infinite anisotropic half-space without piezoeffect. The efficient conversion of bulk waves into surface waves occurs due to a grating area created on the surface of the substrate. Our simulations are fully based on the finite element method. Given the incident bulk wave, we directly determine the amplitude of the surface wave and investigate its dependence on various parameters specifying the situation under consideration, such as the frequency and the polarization of the bulk wave, the length of the grating, the geometrical size of grooves or strips forming the grating. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. Tapping of Love waves in an isotropic surface waveguide by surface-to-bulk wave transduction.

    Science.gov (United States)

    Tuan, H.-S.; Chang, C.-P.

    1972-01-01

    A theoretical study of tapping a Love wave in an isotropic microacoustic surface waveguide is given. The surface Love wave is tapped by partial transduction into a bulk wave at a discontinuity. It is shown that, by careful design of the discontinuity, the converted bulk wave power and the radiation pattern may be controlled. General formulas are derived for the calculation of these important characteristics from a relatively general surface contour deformation.

  16. Broadband asymmetric transmission of linearly polarized electromagnetic waves based on chiral metamaterial

    Science.gov (United States)

    Stephen, Lincy; Yogesh, N.; Subramanian, V.

    2018-01-01

    The giant optical activity of chiral metamaterials (CMMs) holds great potential for tailoring the polarization state of an electromagnetic (EM) wave. In controlling the polarization state, the aspect of asymmetric transmission (AT), where a medium allows the EM radiation to pass through in one direction while restricting it in the opposite direction, adds additional degrees of freedom such as one-way channelling functionality. In this work, a CMM formed by a pair of mutually twisted slanted complementary metal strips is realized for broadband AT accompanied with cross-polarization (CP) conversion for linearly polarized EM waves. Numerically, the proposed ultra-thin (˜λ/42) CMM shows broadband AT from 8.58 GHz to 9.73 GHz (bandwidth of 1.15 GHz) accompanied with CP transmission magnitude greater than 0.9. The transmission and reflection spectra reveal the origin of the asymmetric transmission as the direction sensitive cross polarization conversion and anisotropic electric coupling occurring in the structure which is then elaborated with the surface current analysis and electric field distribution within the structure. An experiment is carried out to verify the broadband AT based CP conversion of the proposed CMM at microwave frequencies, and a reliable agreement between numerical and experimental results is obtained. Being ultra-thin, the reported broadband AT based CP conversion of the proposed CMM is useful for controlling radiation patterns in non-reciprocal EM devices and communication networks.

  17. Investigating Gravity Waves in Polar Mesospheric Clouds Using Tomographic Reconstructions of AIM Satellite Imagery

    Science.gov (United States)

    Hart, V. P.; Taylor, M. J.; Doyle, T. E.; Zhao, Y.; Pautet, P.-D.; Carruth, B. L.; Rusch, D. W.; Russell, J. M.

    2018-01-01

    This research presents the first application of tomographic techniques for investigating gravity wave structures in polar mesospheric clouds (PMCs) imaged by the Cloud Imaging and Particle Size instrument on the NASA AIM satellite. Albedo data comprising consecutive PMC scenes were used to tomographically reconstruct a 3-D layer using the Partially Constrained Algebraic Reconstruction Technique algorithm and a previously developed "fanning" technique. For this pilot study, a large region (760 × 148 km) of the PMC layer (altitude 83 km) was sampled with a 2 km horizontal resolution, and an intensity weighted centroid technique was developed to create novel 2-D surface maps, characterizing the individual gravity waves as well as their altitude variability. Spectral analysis of seven selected wave events observed during the Northern Hemisphere 2007 PMC season exhibited dominant horizontal wavelengths of 60-90 km, consistent with previous studies. These tomographic analyses have enabled a broad range of new investigations. For example, a clear spatial anticorrelation was observed between the PMC albedo and wave-induced altitude changes, with higher-albedo structures aligning well with wave troughs, while low-intensity regions aligned with wave crests. This result appears to be consistent with current theories of PMC development in the mesopause region. This new tomographic imaging technique also provides valuable wave amplitude information enabling further mesospheric gravity wave investigations, including quantitative analysis of their hemispheric and interannual characteristics and variations.

  18. Restoration of s-polarized evanescent waves and subwavelength imaging by a single dielectric slab

    International Nuclear Information System (INIS)

    El Gawhary, Omar; Schilder, Nick J; Costa Assafrao, Alberto da; Pereira, Silvania F; Paul Urbach, H

    2012-01-01

    It was predicted a few years ago that a medium with negative index of refraction would allow for perfect imaging. Although no material has been found so far that behaves as a perfect lens, some experiments confirmed the theoretical predictions in the near-field, or quasi-static, regime where the behaviour of a negative index medium can be mimicked by a thin layer of noble metal, such as silver. These results are normally attributed to the excitation of surface plasmons in the metal, which only leads to the restoration of p-polarized evanescent waves. In this work, we show that the restoration of s-polarized evanescent waves and, correspondingly, sub-wavelength imaging by a single dielectric slab are possible. Specifically, we show that at λ = 632 nm a thin layer of GaAs behaves as a superlens for s-polarized waves. Replacing the single-metal slab by a dielectric is not only convenient from a technical point of view, it being much easier to deposit and control the thickness and flatness of dielectric films than metal ones, but also invites us to re-think the connection between surface plasmon excitation and the theory of negative refraction. (paper)

  19. Frequency tunable surface magneto elastic waves

    NARCIS (Netherlands)

    Janusonis, J.; Chang, C. L.; van Loosdrecht, P. H. M.; Tobey, R. I.

    2015-01-01

    We use the transient grating technique to generate narrow-band, widely tunable, in-plane surface magnetoelastic waves in a nickel film. We monitor both the structural deformation of the acoustic wave and the accompanying magnetic precession and witness their intimate coupling in the time domain.

  20. The impacts of surface polarity on the solubility of nanoparticle

    International Nuclear Information System (INIS)

    Zhu, Jianzhuo; Su, Jiguo; Ou, Xinwen; Li, Jingyuan

    2016-01-01

    In order to study the dependence of water solubility and hydration behavior of nanoparticles on their surface polarity, we designed polar nanoparticles with varying surface polarity by assigning atomic partial charge to the surface of C60. The water solubility of the nanoparticle is enhanced by several orders of magnitude after the introduction of surface polarity. Nevertheless, when the atomic partial charge grows beyond a certain value (q M ), the solubility continuously decreases to the level of nonpolar nanoparticle. It should be noted that such q M is comparable with atomic partial charge of a variety of functional groups. The hydration behaviors of nanoparticles were then studied to investigate the non-monotonic dependence of solubility on the surface polarity. The interaction between the polar nanoparticle and the hydration water is stronger than the nonpolar counterpart, which should facilitate the dissolution of the nanoparticles. On the other hand, the surface polarity also reduces the interaction of hydration water with the other water molecules and enhances the interaction between the nanoparticles which may hinder their dispersion. Besides, the introduction of surface polarity disturbs and even rearranges the hydration structure of nonpolar nanoparticle. Interestingly, the polar nanoparticle with less ordered hydration structure tends to have higher water solubility.

  1. Shear wave induced resonance elastography of spherical masses with polarized torsional waves

    Science.gov (United States)

    Hadj Henni, Anis; Schmitt, Cédric; Trop, Isabelle; Cloutier, Guy

    2012-03-01

    Shear wave induced resonance (SWIR) is a technique for dynamic ultrasound elastography of confined mechanical inclusions. It was developed for breast tumor imaging and tissue characterization. This method relies on the polarization of torsional shear waves modeled with the Helmholtz equation in spherical coordinates. To validate modeling, an invitro set-up was used to measure and image the first three eigenfrequencies and eigenmodes of a soft sphere. A preliminary invivo SWIR measurement on a breast fibroadenoma is also reported. Results revealed the potential of SWIR elastography to detect and mechanically characterize breast lesions for early cancer detection.

  2. Surface wave generation due to glacier calving

    Directory of Open Access Journals (Sweden)

    Stanisław R. Massel

    2013-02-01

    Full Text Available Coastal glaciers reach the ocean in a spectacular process called "calving". Immediately after calving, the impulsive surface waves are generated, sometimes of large height. These waves are particularly dangerous for vessels sailing close to the glacier fronts. The paper presents a theoretical model of surface wave generation due to glacier calving. To explain the wave generation process, four case studies of ice blocks falling into water are discussed: a cylindrical ice block of small thickness impacting on water, an ice column sliding into water without impact, a large ice block falling on to water with a pressure impulse, and an ice column becoming detached from the glacier wall and falling on to the sea surface. These case studies encompass simplified, selected modes of the glacier calving, which can be treated in a theoretical way. Example calculations illustrate the predicted time series of surface elevations for each mode of glacier calving.

  3. Surface Acoustic Waves in ferroelectrics

    Czech Academy of Sciences Publication Activity Database

    Tarasenko A., Nataliya; Jastrabík, Lubomír; Tarasenko, Alexander

    2004-01-01

    Roč. 298, - (2004), s. 325-333 ISSN 0015-0193 R&D Projects: GA AV ČR IBS1010203 Keywords : Rayleigh waves * ferroelectric films * phase transition Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.517, year: 2004

  4. Photonics surface waves on metamaterials interfaces.

    Science.gov (United States)

    Takayama, Osamu; Bogdanov, Andrey; Lavrinenko, Andrei V

    2017-09-12

    A surface wave (SW) in optics is a light wave, which is supported at an interface of two dissimilar media and propagates along the interface with its field amplitude exponentially decaying away from the boundary. The research on surface waves has been flourishing in last few decades thanks to their unique properties of surface sensitivity and field localization. These features have resulted in applications in nano-guiding, sensing, light-trapping and imaging based on the near-field techniques, contributing to the establishment of the nanophotonics as a field of research. Up to present, a wide variety of surface waves has been investigated in numerous material and structure settings. This paper reviews the recent progress and development in the physics of SWs localized at metamaterial interfaces, as well as bulk media in order to provide broader perspectives on optical surface waves in general. For each type of the surface waves, we discuss material and structural platforms. We mainly focus on experimental realizations in the visible and near-infrared wavelength ranges. We also address existing and potential application of SWs in chemical and biological sensing, and experimental excitation and characterization methods. © 2017 IOP Publishing Ltd.

  5. Propagation of an ionizing surface electromagnetic wave

    Energy Technology Data Exchange (ETDEWEB)

    Boev, A.G.; Prokopov, A.V.

    1976-11-01

    The propagation of an rf surface wave in a plasma which is ionized by the wave itself is analyzed. The exact solution of the nonlinear Maxwell equations is discussed for the case in which the density of plasma electrons is an exponential function of the square of the electric field. The range over which the surface wave exists and the frequency dependence of the phase velocity are found. A detailed analysis is given for the case of a plasma whose initial density exceeds the critical density at the wave frequency. An increase in the wave amplitude is shown to expand the frequency range over which the plasma is transparent; The energy flux in the plasma tends toward a certain finite value which is governed by the effective ionization field.

  6. Array processing for seismic surface waves

    International Nuclear Information System (INIS)

    Marano, S.

    2013-01-01

    This dissertation submitted to the Swiss Federal Institute of Technology ETH in Zurich takes a look at the analysis of surface wave properties which allows geophysicists to gain insight into the structure of the subsoil, thus avoiding more expensive invasive techniques such as borehole drilling. This thesis aims at improving signal processing techniques for the analysis of surface waves in various directions. One main contribution of this work is the development of a method for the analysis of seismic surface waves. The method also deals with the simultaneous presence of multiple waves. Several computational approaches to minimize costs are presented and compared. Finally, numerical experiments that verify the effectiveness of the proposed cost function and resulting array geometry designs are presented. These lead to greatly improved estimation performance in comparison to arbitrary array geometries

  7. Parametric plasma surface instabilities with p-polarized radiation

    International Nuclear Information System (INIS)

    Rappaport, H.L.

    1994-01-01

    The authors argue that parametric plasma surface mode excitation is a viable broadband instability mechanism in the microwave regime since the wavelength of incident radiation can be large compared to plasma ion density gradient scale lengths. The authors restrict their attention to plasmas which are uniform in the planes perpendicular to the density gradients. The boundary region is characterized by three parameters: (1) the ion density gradient length; (2) the electron Debye length; and (3) the excursion of boundary electrons as they move in response to monochromatic p-polarized radiation. A thin vacuum plasma transition layer, in which the ion density gradient scale length is large compared with the Debye length and the electron excursion, is included in the analysis of plasma stability. The recently proposed Lagrangian Frame Two-Plasmon Decay mode (LFTPD) is investigated in the regime in which the instability is not resonantly coupled to surface waves propagating along the boundary region. In this case they have found both spatially dependent growth rate profiles and spatially dependent transit layer magnetic fields due to nonlinear surface currents. LFTPD growth rate profiles are displayed as a function of pump amplitude. The results of a time domain simulation of this mode is also shown

  8. Mie scattering in the time domain. Part 1. The role of surface waves.

    Science.gov (United States)

    Lock, James A; Laven, Philip

    2011-06-01

    We computed the Debye series p=1 and p=2 terms of the Mie scattered intensity as a function of scattering angle and delay time for a linearly polarized plane wave pulse incident on a spherical dielectric particle and physically interpreted the resulting numerical data. Radiation shed by electromagnetic surface waves plays a prominent role in the scattered intensity. We determined the surface wave phase and damping rate and studied the structure of the p=1,2 surface wave glory in the time domain.

  9. Demultiplexing Surface Waves With Silicon Nanoantennas

    DEFF Research Database (Denmark)

    Sinev, I.; Bogdanov, A.; Komissarenko, F.

    2017-01-01

    We demonstrate directional launching of surface plasmon polaritons on thin gold film with a single silicon nanosphere. The directivity pattern of the excited surface waves exhibits rapid switching from forward to backward excitation within extremely narrow spectral hand (! 50 nm), which is driven...

  10. Modelling and simulation of surface water waves

    NARCIS (Netherlands)

    van Groesen, Embrecht W.C.; Westhuis, J.H.

    2002-01-01

    The evolution of waves on the surface of a layer of fluid is governed by non-linear effects from surface deformations and dispersive effects from the interaction with the interior fluid motion. Several simulation tools are described in this paper and compared with real life experiments in large

  11. Automated detection and association of surface waves

    Directory of Open Access Journals (Sweden)

    C. R. D. Woodgold

    1994-06-01

    Full Text Available An algorithm for the automatic detection and association of surface waves has been developed and tested over an 18 month interval on broad band data from the Yellowknife array (YKA. The detection algorithm uses a conventional STA/LTA scheme on data that have been narrow band filtered at 20 s periods and a test is then applied to identify dispersion. An average of 9 surface waves are detected daily using this technique. Beamforming is applied to determine the arrival azimuth; at a nonarray station this could be provided by poIarization analysis. The detected surface waves are associated daily with the events located by the short period array at Yellowknife, and later with the events listed in the USGS NEIC Monthly Summaries. Association requires matching both arrival time and azimuth of the Rayleigh waves. Regional calibration of group velocity and azimuth is required. . Large variations in both group velocity and azimuth corrections were found, as an example, signals from events in Fiji Tonga arrive with apparent group velocities of 2.9 3.5 krn/s and azimuths from 5 to + 40 degrees clockwise from true (great circle azimuth, whereas signals from Kuriles Kamchatka have velocities of 2.4 2.9 km/s and azimuths off by 35 to 0 degrees. After applying the regional corrections, surface waves are considered associated if the arrival time matches to within 0.25 km/s in apparent group velocity and the azimuth is within 30 degrees of the median expected. Over the 18 month period studied, 32% of the automatically detected surface waves were associated with events located by the Yellowknife short period array, and 34% (1591 with NEIC events; there is about 70% overlap between the two sets of events. Had the automatic detections been reported to the USGS, YKA would have ranked second (after LZH in terms of numbers of associated surface waves for the study period of April 1991 to September 1992.

  12. Tutorial review of seismic surface waves' phenomenology

    Science.gov (United States)

    Levshin, A. L.; Barmin, M. P.; Ritzwoller, M. H.

    2018-03-01

    In recent years, surface wave seismology has become one of the leading directions in seismological investigations of the Earth's structure and seismic sources. Various applications cover a wide spectrum of goals, dealing with differences in sources of seismic excitation, penetration depths, frequency ranges, and interpretation techniques. Observed seismic data demonstrates the great variability of phenomenology which can produce difficulties in interpretation for beginners. This tutorial review is based on the many years' experience of authors in processing and interpretation of seismic surface wave observations and the lectures of one of the authors (ALL) at Workshops on Seismic Wave Excitation, Propagation and Interpretation held at the Abdus Salam International Center for Theoretical Physics (Trieste, Italy) in 1990-2012. We present some typical examples of wave patterns which could be encountered in different applications and which can serve as a guide to analysis of observed seismograms.

  13. Surface waves in fibre-reinforced anisotropic elastic media

    Indian Academy of Sciences (India)

    Springer Verlag Heidelberg #4 2048 1996 Dec 15 10:16:45

    reinforced solid elastic media. First, the theory of general surface waves has been derived and applied to study the particular cases of surface waves –. Rayleigh, Love and Stoneley types. The wave velocity equations are found to.

  14. A New Kind of Circular Polarization Leaky-Wave Antenna Based on Substrate Integrated Waveguide

    Directory of Open Access Journals (Sweden)

    Chong Zhang

    2015-01-01

    Full Text Available A new kind of circular polarization leaky-wave antenna with N-shaped slots cut in the upper side of substrate integrated waveguide (SIW is investigated and presented. The radiation pattern and polarization axial ratio of the leaky-wave antenna are studied. The results show that the width of N-shaped slots has significant effect on the circular polarization property of the antenna. By properly choosing structural parameters, the SIW based leaky-wave antenna can realize circular polarization with excellent axial ratio in 8 GHz satellite band.

  15. Dispersing surface-modified imogolite nanotubes in polar and non-polar solvents

    Science.gov (United States)

    Li, Ming; Brant, Jonathan A.

    2018-02-01

    Furthering the development of nanocomposite structures, namely membranes for water treatment applications, requires that methods be developed to ensure nanoparticle dispersion in polar and non-polar solvents, as both are widely used in associated synthesis techniques. Here, we report on a two-step method to graft polyvinylpyrrolidone (PVP), and a one-step method for octadecylphosphonic acid (OPA), onto the outer surfaces of imogolite nanotubes. The goal of these approaches was to improve and maintain nanotube dispersion in polymer compatible polar and non-polar solvents. The PVP coating modified the imogolite surface charge from positive to weakly negative at pH ≤ 9; the OPA made it weakly positive at acidic pH values to negative at pH ≥ 7. The PVP surface coating stabilized the nanotubes through steric hindrance in polar protic, dipolar aprotic, and chloroform. In difference to the PVP, the OPA surface coating allowed the nanotubes to be dispersed in n-hexane and chloroform, but not in the polar solvents. The lack of miscibility in the polar solvents, as well as the better dispersion in n-hexane, was attributed to the stronger hydrophobicity of the OPA polymer relative to the PVP. [Figure not available: see fulltext.

  16. Viscoelastic love-type surface waves

    Science.gov (United States)

    Borcherdt, Roger D.

    2008-01-01

    The general theoretical solution for Love-Type surface waves in viscoelastic media provides theoreticalexpressions for the physical characteristics of the waves in elastic as well as anelastic media with arbitraryamounts of intrinsic damping. The general solution yields dispersion and absorption-coefficient curves for the waves as a function of frequency and theamount of intrinsic damping for any chosen viscoelastic model.Numerical results valid for a variety of viscoelastic models provide quantitative estimates of the physicalcharacteristics of the waves pertinent to models of Earth materials ranging from small amounts of damping in the Earth’s crust to moderate and large amounts of damping in soft soils and water-saturated sediments. Numerical results, presented herein, are valid for a wide range of solids and applications.

  17. Polarization and Compressibility of Oblique Kinetic Alfven Waves

    Science.gov (United States)

    Hunana, Peter; Goldstein, M. L.; Passot, T.; Sulem, P. L.; Laveder, D.; Zank, G. P.

    2012-01-01

    Even though solar wind, as a collisionless plasma, is properly described by the kineticMaxwell-Vlasov description, it can be argued that much of our understanding of solar wind observational data comes from an interpretation and numerical modeling which is based on a fluid description of magnetohydrodynamics. In recent years, there has been a significant interest in better understanding the importance of kinetic effects, i.e. the differences between the kinetic and usual fluid descriptions. Here we concentrate on physical properties of oblique kinetic Alfvn waves (KAWs), which are often recognized as one of the key ingredients in the solar wind turbulence cascade. We use three different fluid models with various degrees of complexity and calculate polarization and magnetic compressibility of oblique KAWs (propagation angle q = 88), which we compare to solutions derived from linear kinetic theory. We explore a wide range of possible proton plasma b = [0.1,10.0] and a wide range of length scales krL = [0.001,10.0]. It is shown that the classical isotropic two-fluid model is very compressible in comparison with kinetic theory and that the largest discrepancy occurs at scales larger than the proton gyroscale. We also show that the two-fluid model contains a large error in the polarization of electric field, even at scales krL 1. Furthermore, to understand these discrepancies between the two-fluid model and the kinetic theory, we employ two versions of the Landau fluid model that incorporate linear low-frequency kinetic effects such as Landau damping and finite Larmor radius (FLR) corrections into the fluid description. It is shown that Landau damping significantly reduces the magnetic compressibility and that FLR corrections (i.e. nongyrotropic contributions) are required to correctly capture the polarization.We also show that, in addition to Landau damping, FLR corrections are necessary to accurately describe the damping rate of KAWs. We conclude that kinetic effects

  18. Surface Acoustic Wave Transducer Study.

    Science.gov (United States)

    1978-05-01

    ment. — ISO Lir — ~.1 L ~~~~~~~~ ~ ~~~ L~~~I&jr ~~ —- — — —--- - - - - t - s’ rlr ~~T I O , 4 ) F ~ H I ’ ~~,! ~WI.ft ?).s. ~~~~MEPORT DOCUMENTAT I...multiplying the norma l stress components thus ensuring that the normal stress is zero at x 2 = 0. For the present , an open-circuit elec trical...boundary condition is assumed so that the norma l D-uield is zero at the surface. This is taken .5 into account in a similar manner with a step-function

  19. Polarization attraction using counter-propagating waves in optical fiber at telecommunication wavelengths.

    Science.gov (United States)

    Pitois, S; Fatome, J; Millot, G

    2008-04-28

    In this work, we report the experimental observation of a polarization attraction process which can occur in optical fibers at telecommunication wavelengths. More precisely, we have numerically and experimentally shown that a polarization attractor, based on the injection of two counter-propagating waves around 1.55microm into a 2-m long high nonlinear fiber, can transform any input polarization state into a unique well-defined output polarization state.

  20. Optical Effects Induced by Bloch Surface Waves in One-Dimensional Photonic Crystals

    Directory of Open Access Journals (Sweden)

    Irina V. Soboleva

    2018-01-01

    Full Text Available The review considers the influence of Bloch surface waves on the optical and magneto-optical effects observed in photonic crystals; for example, the Goos–Hänchen effect, the Faraday effect, optical trapping and so on. Prospects for using Bloch surface waves for spatial light modulation, for controlling the polarization of light, for optical trapping and control of micro-objects are discussed.

  1. Active micromixer using surface acoustic wave streaming

    Science.gov (United States)

    Branch,; Darren W. , Meyer; Grant D. , Craighead; Harold, G [Ithaca, NY

    2011-05-17

    An active micromixer uses a surface acoustic wave, preferably a Rayleigh wave, propagating on a piezoelectric substrate to induce acoustic streaming in a fluid in a microfluidic channel. The surface acoustic wave can be generated by applying an RF excitation signal to at least one interdigital transducer on the piezoelectric substrate. The active micromixer can rapidly mix quiescent fluids or laminar streams in low Reynolds number flows. The active micromixer has no moving parts (other than the SAW transducer) and is, therefore, more reliable, less damaging to sensitive fluids, and less susceptible to fouling and channel clogging than other types of active and passive micromixers. The active micromixer is adaptable to a wide range of geometries, can be easily fabricated, and can be integrated in a microfluidic system, reducing dead volume. Finally, the active micromixer has on-demand on/off mixing capability and can be operated at low power.

  2. Modeling and Inversion of Scattered Surface waves

    NARCIS (Netherlands)

    Riyanti, C.D.

    2005-01-01

    In this thesis, we present a modeling method based on a domain-type integral representation for waves propagating along the surface of the Earth which have been scattered in the vicinity of the source or the receivers. Using this model as starting point, we formulate an inversion scheme to estimate

  3. Electrical access to critical coupling of circularly polarized waves in graphene chiral metamaterials.

    Science.gov (United States)

    Kim, Teun-Teun; Oh, Sang Soon; Kim, Hyeon-Don; Park, Hyun Sung; Hess, Ortwin; Min, Bumki; Zhang, Shuang

    2017-09-01

    Active control of polarization states of electromagnetic waves is highly desirable because of its diverse applications in information processing, telecommunications, and spectroscopy. However, despite the recent advances using artificial materials, most active polarization control schemes require optical stimuli necessitating complex optical setups. We experimentally demonstrate an alternative-direct electrical tuning of the polarization state of terahertz waves. Combining a chiral metamaterial with a gated single-layer sheet of graphene, we show that transmission of a terahertz wave with one circular polarization can be electrically controlled without affecting that of the other circular polarization, leading to large-intensity modulation depths (>99%) with a low gate voltage. This effective control of polarization is made possible by the full accessibility of three coupling regimes, that is, underdamped, critically damped, and overdamped regimes by electrical control of the graphene properties.

  4. Polarization-Based Tests of Gravity with the Stochastic Gravitational-Wave Background

    Directory of Open Access Journals (Sweden)

    Thomas Callister

    2017-12-01

    Full Text Available The direct observation of gravitational waves with Advanced LIGO and Advanced Virgo offers novel opportunities to test general relativity in strong-field, highly dynamical regimes. One such opportunity is the measurement of gravitational-wave polarizations. While general relativity predicts only two tensor gravitational-wave polarizations, general metric theories of gravity allow for up to four additional vector and scalar modes. The detection of these alternative polarizations would represent a clear violation of general relativity. The LIGO-Virgo detection of the binary black hole merger GW170814 has recently offered the first direct constraints on the polarization of gravitational waves. The current generation of ground-based detectors, however, is limited in its ability to sensitively determine the polarization content of transient gravitational-wave signals. Observation of the stochastic gravitational-wave background, in contrast, offers a means of directly measuring generic gravitational-wave polarizations. The stochastic background, arising from the superposition of many individually unresolvable gravitational-wave signals, may be detectable by Advanced LIGO at design sensitivity. In this paper, we present a Bayesian method with which to detect and characterize the polarization of the stochastic background. We explore prospects for estimating parameters of the background and quantify the limits that Advanced LIGO can place on vector and scalar polarizations in the absence of a detection. Finally, we investigate how the introduction of new terrestrial detectors like Advanced Virgo aid in our ability to detect or constrain alternative polarizations in the stochastic background. We find that, although the addition of Advanced Virgo does not notably improve detection prospects, it may dramatically improve our ability to estimate the parameters of backgrounds of mixed polarization.

  5. The polarization evolution of electromagnetic waves as a diagnostic method for a motional plasma

    Science.gov (United States)

    Shahrokhi, Alireza; Mehdian, Hassan; Hajisharifi, Kamal; Hasanbeigi, Ali

    2017-12-01

    The polarization evolution of electromagnetic (EM) radiation propagating through an electron beam-ion channel system is studied in the presence of self-magnetic field. Solving the fluid-Maxwell equations to obtain the medium dielectric tensor, the Stokes vector-Mueller matrix approach is employed to determine the polarization of the launched EM wave at any point in the propagation direction, applying the space-dependent Mueller matrix on the initial polarization vector of the wave at the plasma-vacuum interface. Results show that the polarization evolution of the wave is periodic in space along the beam axis with the specified polarization wavelength. Using the obtained results, a novel diagnostic method based on the polarization evolution of the EM waves is proposed to evaluate the electron beam density and velocity. Moreover, to use the mentioned plasma system as a polarizer, the fraction of the output radiation power transmitted through a motional plasma crossed with the input polarization is calculated. The results of the present investigation will greatly contribute to design a new EM amplifier with fixed polarization or EM polarizer, as well as a new diagnostic approach for the electron beam system where the polarimetric method is employed.

  6. The nonlinear effects on the characteristics of gravity wave packets: dispersion and polarization relations

    Directory of Open Access Journals (Sweden)

    S.-D. Zhang

    2000-10-01

    Full Text Available By analyzing the results of the numerical simulations of nonlinear propagation of three Gaussian gravity-wave packets in isothermal atmosphere individually, the nonlinear effects on the characteristics of gravity waves are studied quantitatively. The analyses show that during the nonlinear propagation of gravity wave packets the mean flows are accelerated and the vertical wavelengths show clear reduction due to nonlinearity. On the other hand, though nonlinear effects exist, the time variations of the frequencies of gravity wave packets are close to those derived from the dispersion relation and the amplitude and phase relations of wave-associated disturbance components are consistent with the predictions of the polarization relation of gravity waves. This indicates that the dispersion and polarization relations based on the linear gravity wave theory can be applied extensively in the nonlinear region.Key words: Meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides

  7. Surface and body waves from surface and underground explosions

    International Nuclear Information System (INIS)

    Kusubov, A.S.

    1976-06-01

    The characteristics of surface and ground waves were recorded for surface and underground explosions up to 100 tons and 40 kt in magnitude, respectively, and a preliminary analysis of these results is presented. The experiments were conducted at NTS in the Yucca Flats, Nevada. Ground motions were detected with triaxial geophones along seismic lines extending up to 16 miles from the point of explosions. A comparison of Rayleigh waves generated by surface and underground explosions in the same lake bed is presented indicating a very different behavior of surface and ground waves from the two types of explosions. The magnitude of the transverse wave for surface shots was smaller by a factor of two than its longitudinal counterpart. The dependence of apparent periods on the blast energy was not apparent at a fixed distance from the explosions. Changes in the apparent period with distance for both types of explosion are compared indicating a strong layering effect of the lake bed. The ground motion study was complimented by excavation of cavities generated by the explosions

  8. Analytical treatment of particle motion in circularly polarized slab-mode wave fields

    Science.gov (United States)

    Schreiner, Cedric; Vainio, Rami; Spanier, Felix

    2018-02-01

    Wave-particle interaction is a key process in particle diffusion in collisionless plasmas. We look into the interaction of single plasma waves with individual particles and discuss under which circumstances this is a chaotic process, leading to diffusion. We derive the equations of motion for a particle in the fields of a magnetostatic, circularly polarized, monochromatic wave and show that no chaotic particle motion can arise under such circumstances. A novel and exact analytic solution for the equations is presented. Additional plasma waves lead to a breakdown of the analytic solution and chaotic particle trajectories become possible. We demonstrate this effect by considering a linearly polarized, monochromatic wave, which can be seen as the superposition of two circularly polarized waves. Test particle simulations are provided to illustrate and expand our analytical considerations.

  9. A numerical assessment of rough surface scattering theories. I - Horizontal polarization. II - Vertical polarization

    Science.gov (United States)

    Rodriguez, Ernesto; Kim, Yunjin; Durden, Stephen L.

    1992-01-01

    A numerical evaluation is presented of the regime of validity for various rough surface scattering theories against numerical results obtained by employing the method of moments. The contribution of each theory is considered up to second order in the perturbation expansion for the surface current. Considering both vertical and horizontal polarizations, the unified perturbation method provides best results among all theories weighed.

  10. Induction of subterahertz surface waves on a metal wire by intense laser interaction with a foil

    Science.gov (United States)

    Teramoto, Kensuke; Inoue, Shunsuke; Tokita, Shigeki; Yasuhara, Ryo; Nakamiya, Yoshihide; Nagashima, Takeshi; Mori, Kazuaki; Hashida, Masaki; Sakabe, Shuji

    2018-02-01

    We have demonstrated that a pulsed electromagnetic wave (Sommerfeld wave) of subterahertz frequency and 11-MV/m field strength can be induced on a metal wire by the interaction of an intense femtosecond laser pule with an adjacent metal foil at a laser intensity of 8.5 × 1018W /c m2 . The polarity of the electric field of this surface wave is opposite to that obtained by the direct interaction of the laser with the wire. Numerical simulations suggest that an electromagnetic wave associated with electron emission from the foil induces the surface wave. A tungsten wire is placed normal to an aluminum foil with a gap so that the wire is not irradiated and damaged by the laser pulse, thus making it possible to generate surface waves on the wire repeatedly.

  11. Blackfolds, plane waves and minimal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Armas, Jay [Physique Théorique et Mathématique, Université Libre de Bruxelles and International Solvay Institutes, ULB-Campus Plaine CP231, B-1050 Brussels (Belgium); Albert Einstein Center for Fundamental Physics, University of Bern,Sidlerstrasse 5, 3012 Bern (Switzerland); Blau, Matthias [Albert Einstein Center for Fundamental Physics, University of Bern,Sidlerstrasse 5, 3012 Bern (Switzerland)

    2015-07-29

    Minimal surfaces in Euclidean space provide examples of possible non-compact horizon geometries and topologies in asymptotically flat space-time. On the other hand, the existence of limiting surfaces in the space-time provides a simple mechanism for making these configurations compact. Limiting surfaces appear naturally in a given space-time by making minimal surfaces rotate but they are also inherent to plane wave or de Sitter space-times in which case minimal surfaces can be static and compact. We use the blackfold approach in order to scan for possible black hole horizon geometries and topologies in asymptotically flat, plane wave and de Sitter space-times. In the process we uncover several new configurations, such as black helicoids and catenoids, some of which have an asymptotically flat counterpart. In particular, we find that the ultraspinning regime of singly-spinning Myers-Perry black holes, described in terms of the simplest minimal surface (the plane), can be obtained as a limit of a black helicoid, suggesting that these two families of black holes are connected. We also show that minimal surfaces embedded in spheres rather than Euclidean space can be used to construct static compact horizons in asymptotically de Sitter space-times.

  12. Surface Polarization Effects on Ion-Containing Emulsions

    Science.gov (United States)

    Shen, Meng; Li, Honghao; Olvera de la Cruz, Monica

    2017-09-01

    Surface polarization in ion-containing heterogeneous dielectric media such as cell media and emulsions is determined by and determines the positions of the ions. We compute the surface polarization self-consistently as the ions move and analyze their effects on the interactions between electro-neutral, ion-containing droplets using coarse-grained molecular dynamics simulations based on the true energy functional. For water droplets immersed in oil, the interdroplet interaction is attractive, and the surface polarization makes the major contribution. By contrast, for oil droplets in water, the ion-surface induced charge interaction is repulsive and counteracts the attraction between the ions, leading to a small attractive interaction between the droplets. This research improves our understanding of self-assembly in mixed phases such as metal extraction for recovering rare earth elements and nuclear waste as well as water purification.

  13. Mathematical aspects of surface water waves

    International Nuclear Information System (INIS)

    Craig, Walter; Wayne, Clarence E

    2007-01-01

    The theory of the motion of a free surface over a body of water is a fascinating subject, with a long history in both applied and pure mathematical research, and with a continuing relevance to the enterprises of mankind having to do with the sea. Despite the recent advances in the field (some of which we will hear about during this Workshop on Mathematical Hydrodynamics at the Steklov Institute), and the current focus of the mathematical community on the topic, many fundamental mathematical questions remain. These have to do with the evolution of surface water waves, their approximation by model equations and by computer simulations, the detailed dynamics of wave interactions, such as would produce rogue waves in an open ocean, and the theory (partially probabilistic) of approximating wave fields over large regions by averaged 'macroscopic' quantities which satisfy essentially kinetic equations of motion. In this note we would like to point out open problems and some of the directions of current research in the field. We believe that the introduction of new analytical techniques and novel points of view will play an important role in the future development of the area.

  14. Polarization properties of low frequency electromagnetic cyclotron waves associated with magnetic clouds

    Science.gov (United States)

    Zhao, G. Q.; Feng, H. Q.; Wu, D. J.; Huang, J.

    2018-03-01

    Recent studies have revealed that there are a large number of low frequency electromagnetic cyclotron waves (ECWs) occurring in and around magnetic clouds (MCs) that are common magnetic structures in interplanetary space. Using magnetic field data from the STEREO spacecraft, this paper investigates polarization properties of ECWs associated with 120 MCs. Results show that the ECWs are highly transverse, strongly polarized waves with large ellipticities. Specifically, almost all of the waves take place with the ratios of transverse power to total power higher than 0.94, polarization degrees greater than 0.85, and ellipticities larger than 0.5. The mean values of these quantities can be up to 0.99, 0.96, 0.85, respectively. In particular, there is a tendency of ellipticities decreasing with respect to the wave normal angles for ECWs with left handed polarization. The decreasing tendency is consistent with the recent theory and simulation results.

  15. Evolution of full stokes parameters in polarized radiative transfer of electron cyclotron waves on LHD

    Energy Technology Data Exchange (ETDEWEB)

    Idei, H.; Kubo, S.; Shimozuma, T.; Tsumori, K.; Watari, T.; Ito, S.; Kobayashi, S.; Mizuno, Y.; Takita, Y.; Yoshimura, Y.; Ohkubo, K.; Sakakibara, S.; Narihara, K.; Yamada, I.; Tanaka, K.; Morisaki, T.; Watanabe, K. Y.; Nakanishi, H.; Ohdachi, S.; Emoto, M.; Matsuoka, K.; Motojima, O.; Fujiwara, M. [LHD Experimental Group, National Institute for Fusion Science, Toki, 509-5292 (Japan); Notake, T. [Nagoya University, Faculty of Engineering, Nagoya, 464-8603 (Japan)

    2003-07-01

    To study polarized radiative transfer of electron cyclotron waves, a general equation of polarization evolution that includes the effects of both birefringence and dichroism is dealt with. Full Stokes parameters are used to describe the polarization state and the absorption rate in the equation. The evolution equation on polarization state is able to treat general cases in which two polarization states of Eigenmodes are not necessary to be orthogonal. Using this equation, a single absorption rate in second harmonic electron cyclotron heating is investigated on the Large Helical Device. (authors)

  16. Spin-wave propagation and spin-polarized electron transport in single-crystal iron films

    Science.gov (United States)

    Gladii, O.; Halley, D.; Henry, Y.; Bailleul, M.

    2017-11-01

    The techniques of propagating spin-wave spectroscopy and current-induced spin-wave Doppler shift are applied to a 20-nm-thick Fe/MgO(001) film. The magnetic parameters extracted from the position of the spin-wave resonance peaks are very close to those tabulated for bulk iron. From the zero-current propagating wave forms, a group velocity of 4 km/s and an attenuation length of about 6 μ m are extracted for 1.6-μ m -wavelength spin wave at 18 GHz. From the measured current-induced spin-wave Doppler shift, we extract a surprisingly high degree of spin polarization of the current of 83 % , which constitutes the main finding of this work. This set of results makes single-crystalline iron a promising candidate for building devices utilizing high-frequency spin waves and spin-polarized currents.

  17. Energy density and energy flow of surface waves in a strongly magnetized graphene

    Science.gov (United States)

    Moradi, Afshin

    2018-01-01

    General expressions for the energy density and energy flow of plasmonic waves in a two-dimensional massless electron gas (as a simple model of graphene) are obtained by means of the linearized magneto-hydrodynamic model and classical electromagnetic theory when a strong external magnetic field perpendicular to the system is present. Also, analytical expressions for the energy velocity, wave polarization, wave impedance, transverse and longitudinal field strength functions, and attenuation length of surface magneto-plasmon-polariton waves are derived, and numerical results are prepared.

  18. Topological events in polarization resolved angular patterns of nematic liquid crystal cells at varying ellipticity of incident wave

    OpenAIRE

    Kiselev, Alexei D.; Vovk, Roman G.

    2008-01-01

    We study the angular structure of polarization of light transmitted through a nematic liquid crystal (NLC) cell by analyzing the polarization state as a function of the incidence angles and the polarization of the incident wave. The polarization resolved angular patterns emerging after the NLC cell illuminated by the convergent light beam are described in terms of the polarization singularities such as C-points (points of circular polarization) and L-lines (lines of linear polarization). For ...

  19. Polarization Insensitive Wavelength Conversion Based on Four-Wave Mixing in a Silicon Nanowire

    DEFF Research Database (Denmark)

    Pu, Minhao; Hu, Hao; Peucheret, Christophe

    2012-01-01

    We experimentally demonstrate, for the first time, polarization-insensitive wavelength conversion of a 10 Gb/s NRZ-OOK data signal based on four-wave mixing in a silicon nanowire with bit-error rate measurements.......We experimentally demonstrate, for the first time, polarization-insensitive wavelength conversion of a 10 Gb/s NRZ-OOK data signal based on four-wave mixing in a silicon nanowire with bit-error rate measurements....

  20. Parametric analysis of change in wave number of surface waves

    Directory of Open Access Journals (Sweden)

    Tadić Ljiljana

    2015-01-01

    Full Text Available The paper analyzes the dependence of the change wave number of materials soil constants, ie the frequency of the waves. The starting point in this analysis cosists of wave equation and dynamic stiffness matrix of soil.

  1. Connections Between the Spring Breakup of the Southern Hemisphere Polar Vortex, Stationary Waves, and Air-sea Roughness

    Science.gov (United States)

    Garfinkel, Chaim I.; Oman, Luke David; Barnes, Elizabeth A.; Waugh, Darryn W.; Hurwitz, Margaret H.; Molod, Andrea M.

    2013-01-01

    A robust connection between the drag on surface-layer winds and the stratospheric circulation is demonstrated in NASA's Goddard Earth Observing System Chemistry-Climate Model (GEOSCCM). Specifically, an updated parameterization of roughness at the air-sea interface, in which surface roughness is increased for moderate wind speeds (4ms to 20ms), leads to a decrease in model biases in Southern Hemispheric ozone, polar cap temperature, stationary wave heat flux, and springtime vortex breakup. A dynamical mechanism is proposed whereby increased surface roughness leads to improved stationary waves. Increased surface roughness leads to anomalous eddy momentum flux convergence primarily in the Indian Ocean sector (where eddies are strongest climatologically) in September and October. The localization of the eddy momentum flux convergence anomaly in the Indian Ocean sector leads to a zonally asymmetric reduction in zonal wind and, by geostrophy, to a wavenumber-1 stationary wave pattern. This tropospheric stationary wave pattern leads to enhanced upwards wave activity entering the stratosphere. The net effect is an improved Southern Hemisphere vortex: the vortex breaks up earlier in spring (i.e., the spring late-breakup bias is partially ameliorated) yet is no weaker in mid-winter. More than half of the stratospheric biases appear to be related to the surface wind speed biases. As many other chemistry climate models use a similar scheme for their surface layer momentum exchange and have similar biases in the stratosphere, we expect that results from GEOSCCM may be relevant for other climate models.

  2. Meteorite Impact "Earthquake" Features (Rock Liquefaction, Surface Wave Deformations, Seismites) from Ground Penetrating Radar (GPR) and Geoelectric Complex Resistivity/Induced Polarization (IP) Measurements, Chiemgau (Alpine Foreland, Southeast Germany)

    Science.gov (United States)

    Ernstson, K.; Poßekel, J.

    2017-12-01

    Densely spaced GPR and complex resistivity measurements on a 30,000 square meters site in a region of enigmatic sinkhole occurrences in unconsolidated Quaternary sediments have featured unexpected and highlighting results from both a meteorite impact research and an engineering geology point of view. The GPR measurements and a complex resistivity/IP electrical imaging revealed extended subrosion depressions related with a uniformly but in various degrees of intensity deformed loamy and gravelly ground down to at least 10 m depth. Two principle observations could be made from both the GPR high-resolution measurements and the more integrating resistivity and IP soundings with both petrophysical evidences in good complement. Subrosion can be shown to be the result of prominent sandy-gravelly intrusions and extrusions typical of rock liquefaction processes well known to occur during strong earthquakes. Funnel-shaped structures with diameters up to 25 m near the surface and reaching down to the floating ground water level at 10 m depth were measured. GPR radargrams could trace prominent gravelly-material transport bottom-up within the funnels. Seen in both GPR tomography and resistivity/IP sections more or less the whole investigated area is overprinted by wavy deformations of the unconsolidated sediments with wavelengths of the order of 5 - 10 m and amplitudes up to half a meter, likewise down to 10 m depth. Substantial earthquakes are not known in this region. Hence, the observed heavy underground disorder is considered the result of the prominent earthquake shattering that must have occurred during the Holocene (Bronze Age/Celtic era) Chiemgau meteorite impact event that produced a 60 km x 30 km sized crater strewn field directly hosting the investigated site. Depending on depth and size of floating aquifers local concentrations of rock liquefaction and seismic surface waves (probably LOVE waves) to produce the wavy deformations could develop, when the big

  3. Nonplanar electrostatic shock waves in an opposite polarity dust ...

    Indian Academy of Sciences (India)

    M Amina

    2017-05-30

    May 30, 2017 ... The coexistence of positively and negatively charged dust grains has been observed in the Earth's mesosphere [11,12] as well as in cometary tails and comae [6]. The propagation of various types of nonlinear waves in dusty plasmas, viz., dust-acoustic (DA) waves [13], dust-ion-acoustic (DIA) waves [14,15] ...

  4. Megaquakes, prograde surface waves and urban evolution

    Science.gov (United States)

    Lomnitz, C.; Castaños, H.

    2013-05-01

    Cities grow according to evolutionary principles. They move away from soft-ground conditions and avoid vulnerable types of structures. A megaquake generates prograde surface waves that produce unexpected damage in modern buildings. The examples (Figs. 1 and 2) were taken from the 1985 Mexico City and the 2010 Concepción, Chile megaquakes. About 400 structures built under supervision according to modern building codes were destroyed in the Mexican earthquake. All were sited on soft ground. A Rayleigh wave will cause surface particles to move as ellipses in a vertical plane. Building codes assume that this motion will be retrograde as on a homogeneous elastic halfspace, but soft soils are intermediate materials between a solid and a liquid. When Poisson's ratio tends to ν→0.5 the particle motion turns prograde as it would on a homogeneous fluid halfspace. Building codes assume that the tilt of the ground is not in phase with the acceleration but we show that structures on soft ground tilt into the direction of the horizontal ground acceleration. The combined effect of gravity and acceleration may destabilize a structure when it is in resonance with its eigenfrequency. Castaños, H. and C. Lomnitz, 2013. Charles Darwin and the 1835 Chile earthquake. Seismol. Res. Lett., 84, 19-23. Lomnitz, C., 1990. Mexico 1985: the case for gravity waves. Geophys. J. Int., 102, 569-572. Malischewsky, P.G. et al., 2008. The domain of existence of prograde Rayleigh-wave particle motion. Wave Motion 45, 556-564.; Figure 1 1985 Mexico megaquake--overturned 15-story apartment building in Mexico City ; Figure 2 2010 Chile megaquake Overturned 15-story R-C apartment building in Concepción

  5. Illusions and Cloaks for Surface Waves

    Science.gov (United States)

    McManus, T. M.; Valiente-Kroon, J. A.; Horsley, S. A. R.; Hao, Y.

    2014-08-01

    Ever since the inception of Transformation Optics (TO), new and exciting ideas have been proposed in the field of electromagnetics and the theory has been modified to work in such fields as acoustics and thermodynamics. The most well-known application of this theory is to cloaking, but another equally intriguing application of TO is the idea of an illusion device. Here, we propose a general method to transform electromagnetic waves between two arbitrary surfaces. This allows a flat surface to reproduce the scattering behaviour of a curved surface and vice versa, thereby giving rise to perfect optical illusion and cloaking devices, respectively. The performance of the proposed devices is simulated using thin effective media with engineered material properties. The scattering of the curved surface is shown to be reproduced by its flat analogue (for illusions) and vice versa for cloaks.

  6. Slot-dimer babinet metamaterials as polarization shapers for terahertz waves

    DEFF Research Database (Denmark)

    Zhukovsky, Sergei; Chigrin, D. N.; Lavrinenko, Andrei

    2013-01-01

    We theoretically study optical properties of free-standing metallic membranes patterned with an array of two-slot elements (dimers) comprising two rectangular slots of different dimensions and orientation. It is shown that these structures feature extraordinary optical transmission with strong...... and spectrally selective polarization conversion capabilities. The output polarization is highly dependent on the dimer geometry, which can be used in the design of compact polarization shapers for terahertz waves....

  7. Ion sense of polarization of the electromagnetic wave field in the electron whistler frequency band

    Directory of Open Access Journals (Sweden)

    B. Lundin

    Full Text Available It is shown that the left-hand (or ion-type sense of polarization can appear in the field interference pattern of two plane electron whistler waves. Moreover, it is demonstrated that the ion-type polarized wave electric fields can be accompanied by the presence at the same observation point of electron-type polarized wave magnetic fields. The registration of ion-type polarized fields with frequencies between the highest ion gyrofrequency and the electron gyrofrequency in a cold, overdense plasma is a sufficient indication for the existence of an interference wave pattern, which can typically occur near artificial or natural reflecting magnetospheric plasma regions, inside waveguides (as in helicon discharges, for example, in fields resonantly emitted by beams of charged particles or, in principle, in some self-sustained, nonlinear wave field structures. A comparison with the conventional spectral matrix data processing approach is also presented in order to facilitate the calculations of the analyzed polarization parameters.

    Key words. Ionosphere (wave propagation Radio science (waves in plasma Space plasma physics (general or miscellaneous

  8. Ion sense of polarization of the electromagnetic wave field in the electron whistler frequency band

    Directory of Open Access Journals (Sweden)

    B. Lundin

    2002-08-01

    Full Text Available It is shown that the left-hand (or ion-type sense of polarization can appear in the field interference pattern of two plane electron whistler waves. Moreover, it is demonstrated that the ion-type polarized wave electric fields can be accompanied by the presence at the same observation point of electron-type polarized wave magnetic fields. The registration of ion-type polarized fields with frequencies between the highest ion gyrofrequency and the electron gyrofrequency in a cold, overdense plasma is a sufficient indication for the existence of an interference wave pattern, which can typically occur near artificial or natural reflecting magnetospheric plasma regions, inside waveguides (as in helicon discharges, for example, in fields resonantly emitted by beams of charged particles or, in principle, in some self-sustained, nonlinear wave field structures. A comparison with the conventional spectral matrix data processing approach is also presented in order to facilitate the calculations of the analyzed polarization parameters.Key words. Ionosphere (wave propagation Radio science (waves in plasma Space plasma physics (general or miscellaneous

  9. Vector wave diffraction pattern of slits masked by polarizing devices

    Indian Academy of Sciences (India)

    This calls for a systematic study of diffraction properties of different apertures using polarization-sensitive devices. In the present paper, we have studied the Fraunhofer diffraction pattern of slits masked by different kinds of polarizing devices which introduce a phase difference between the two orthogonal components of the ...

  10. Bistable polarization switching in a continuous wave ruby laser

    Science.gov (United States)

    Lawandy, N. M.; Afzal, R. Sohrab

    1988-01-01

    Bistability in the output power, polarization state, and mode volume of an argon-ion laser pumped single mode ruby laser at 6943 A has been observed. The laser operates in a radially confined mode which exhibits hysteresis and bistability only when the pump polarization is parallel to the c-axis.

  11. Surface wave propagation over sinusoidally varying topography: Theory and observation

    Science.gov (United States)

    Davies, A. G.; Heathershaw, A. D.

    Linear perturbation theory is used to show that the reflection coefficient of a patch of sinusoidal ripples on an otherwise flat bed is oscillatory in the quotient of the length of the patch and the surface wave length, and strongly dependent upon the quotient of the surface and bed wave numbers. Resonant interaction between the surface waves and the ripples if the surface wavenumber is half the ripple wavenumber is demonstrated. Few ripples, of relatively small steepness, are required to produce a substantial reflected wave. In resonant cases, the partially standing wave on the up-wave side of the ripple patch gives way, in an almost linear manner over the the ripple patch itself, to a progressive (transmitted) wave on the down-wave side. Wave tank data agree well with predictions, and suggest coupling between wave reflection and ripple growth on an erodible bed.

  12. Arbitrary amplitude dust kinetic Alfvén solitary waves in the presence of polarization force

    Science.gov (United States)

    Singh, Manpreet; Kaur, Nimardeep; Saini, N. S.

    2018-02-01

    In this investigation, the effect of polarization force on dust kinetic Alfvén solitary waves (DKASWs) in a magnetized dusty plasma consisting of dust fluid, electrons, and positively charged ions is studied. By incorporating density non-uniformity and polarization force in the fluid model equations, the energy balance equation is derived, and from the expression for Sagdeev pseudopotential, the existence conditions for solitary structures in terms of Mach number are determined. From the numerical analysis of Sagdeev pseudopotential, compressive and rarefactive DKASWs at sub- and super-Alfvénic speeds are observed. These waves are significantly affected by varying polarization force, angle of propagation, plasma beta, and Mach number.

  13. Surface Wave Simulation and Processing with MatSeis

    Energy Technology Data Exchange (ETDEWEB)

    THOMPSON,BEVERLY D.; CHAEL,ERIC P.; YOUNG,CHRISTOPHER J.; WALTER,WILLIAM R.; PASYANOS,MICHAEL E.

    2000-08-07

    In order to exploit the information on surface wave propagation that is stored in large seismic event datasets, Sandia and Lawrence Livermore National Laboratories have developed a MatSeis interface for performing phase-matched filtering of Rayleigh arrivals. MatSeis is a Matlab-based seismic processing toolkit which provides graphical tools for analyzing seismic data from a network of stations. Tools are available for spectral and polarization measurements, as well as beam forming and f-k analysis with array data, to name just a few. Additionally, one has full access to the Matlab environment and any functions available there. Previously the authors reported the development of new MatSeis tools for calculating regional discrimination measurements. The first of these performs Lg coda analysis as developed by Mayeda and coworkers at Lawrence Livermore National Laboratory. A second tool measures regional phase amplitude ratios for an event and compares the results to ratios from known earthquakes and explosions. Release 1.5 of MatSeis includes the new interface for the analysis of surface wave arrivals. This effort involves the use of regionalized dispersion models from a repository of surface wave data and the construction of phase-matched filters to improve surface wave identification, detection, and magnitude calculation. The tool works as follows. First, a ray is traced from source to receiver through a user-defined grid containing different group velocity versus period values to determine the composite group velocity curve for the path. This curve is shown along with the upper and lower group velocity bounds for reference. Next, the curve is used to create a phase-matched filter, apply the filter, and show the resultant waveform. The application of the filter allows obscured Rayleigh arrivals to be more easily identified. Finally, after screening information outside the range of the phase-matched filter, an inverse version of the filter is applied to obtain a

  14. Concentration polarization, surface currents, and bulk advection in a microchannel

    DEFF Research Database (Denmark)

    Nielsen, Christoffer Peder; Bruus, Henrik

    2014-01-01

    We present a comprehensive analysis of salt transport and overlimiting currents in a microchannel during concentration polarization. We have carried out full numerical simulations of the coupled Poisson-Nernst-Planck-Stokes problem governing the transport and rationalized the behavior of the syst...... as in the limit of negligible surface charge. By including the effects of diffusion and advection in the diffuse part of the electric double layers, we extend a recently published analytical model of overlimiting current due to surface conduction....

  15. Energy storage and dispersion of surface acoustic waves trapped in a periodic array of mechanical resonators

    DEFF Research Database (Denmark)

    Dühring, Maria Bayard; Laude, Vincent; Khelif, Abdelkrim

    2009-01-01

    confined to the electrode as compared to the total mechanical energy is calculated and is found to be increasing for increasing aspect ratio and to tend to a definite limit for the two families of surface waves. This observation is in support of the interpretation that high aspect ratio electrodes act......It has been shown previously that surface acoustic waves can be efficiently trapped and slowed by steep ridges on a piezoelectric substrate, giving rise to two families of shear-horizontal and vertically polarized surface waves. The mechanisms of energy storage and dispersion are explored by using...... the finite element method to model surface acoustic waves generated by high aspect ratio electrodes. A periodic model is proposed including a perfectly matched layer to simulate radiation conditions away from the sources, from which the modal distributions are found. The ratio of the mechanical energy...

  16. Wave propagation in photonic crystals and metamaterials: Surface waves, nonlinearity and chirality

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Bingnan [Iowa State Univ., Ames, IA (United States)

    2009-01-01

    Photonic crystals and metamaterials, both composed of artificial structures, are two interesting areas in electromagnetism and optics. New phenomena in photonic crystals and metamaterials are being discovered, including some not found in natural materials. This thesis presents my research work in the two areas. Photonic crystals are periodically arranged artificial structures, mostly made from dielectric materials, with period on the same order of the wavelength of the working electromagnetic wave. The wave propagation in photonic crystals is determined by the Bragg scattering of the periodic structure. Photonic band-gaps can be present for a properly designed photonic crystal. Electromagnetic waves with frequency within the range of the band-gap are suppressed from propagating in the photonic crystal. With surface defects, a photonic crystal could support surface modes that are localized on the surface of the crystal, with mode frequencies within the band-gap. With line defects, a photonic crystal could allow the propagation of electromagnetic waves along the channels. The study of surface modes and waveguiding properties of a 2D photonic crystal will be presented in Chapter 1. Metamaterials are generally composed of artificial structures with sizes one order smaller than the wavelength and can be approximated as effective media. Effective macroscopic parameters such as electric permittivity ϵ, magnetic permeability μ are used to characterize the wave propagation in metamaterials. The fundamental structures of the metamaterials affect strongly their macroscopic properties. By designing the fundamental structures of the metamaterials, the effective parameters can be tuned and different electromagnetic properties can be achieved. One important aspect of metamaterial research is to get artificial magnetism. Metallic split-ring resonators (SRRs) and variants are widely used to build magnetic metamaterials with effective μ < 1 or even μ < 0. Varactor based

  17. Rac1 regulates neuronal polarization through the WAVE complex

    DEFF Research Database (Denmark)

    Tahirovic, Sabina; Hellal, Farida; Neukirchen, Dorothee

    2010-01-01

    the physiological function of Rac1 in neuronal development, we have generated a conditional knock-out mouse, in which Rac1 is ablated in the whole brain. Rac1-deficient cerebellar granule neurons, which do not express other Rac isoforms, showed impaired neuronal migration and axon formation both in vivo...... and in vitro. In addition, Rac1 ablation disrupts lamellipodia formation in growth cones. The analysis of Rac1 effectors revealed the absence of the Wiskott-Aldrich syndrome protein (WASP) family verprolin-homologous protein (WAVE) complex from the plasma membrane of knock-out growth cones. Loss of WAVE...... function inhibited axon growth, whereas overexpression of a membrane-tethered WAVE mutant partially rescued axon growth in Rac1-knock-out neurons. In addition, pharmacological inhibition of the WAVE complex effector Arp2/3 also reduced axon growth. We propose that Rac1 recruits the WAVE complex...

  18. Electrokinetics of polar liquids in contact with nonpolar surfaces.

    Science.gov (United States)

    Lin, Chih-Hsiu; Ferguson, Gregory S; Chaudhury, Manoj K

    2013-06-25

    Zeta potentials of several polar protic (water, ethylene glycol, and formamide) as well as polar aprotic (dimethyl sulfoxide) liquids were measured in contact with three nonpolar surfaces using closed-cell electroosmosis. The test surfaces were chemisorbed monolayers of alkyl siloxanes, fluoroalkyl siloxanes, and polydimethylsiloxanes (PDMS) grafted on glass slides. All these liquids exhibited substantial electrokinetics in contact with the nonpolar surfaces with these observations: the electrokinetic effect on the fluorocarbon-coated surface is the strongest and on a PDMS grafted surface, the effect is the weakest. Even though these hygroscopic liquids contain small amounts of water, the current models of charging based on the adsorption of hydroxide ions at the interface or the dissociation of pre-existing functionalities (e.g., silanol groups) appear to be insufficient to account for the various facets of the experimental observations. The results illustrate how ubiquitous the phenomenon of electrokinetics is with polar liquids contacting such apparently passive nonpolar surfaces. We hope that these results will inspire further experimental and theoretical studies in this important area of research that has potential practical implications.

  19. Effect of cathodic polarization on coating doxycycline on titanium surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Geißler, Sebastian; Tiainen, Hanna; Haugen, Håvard J., E-mail: h.j.haugen@odont.uio.no

    2016-06-01

    Cathodic polarization has been reported to enhance the ability of titanium based implant materials to interact with biomolecules by forming titanium hydride at the outermost surface layer. Although this hydride layer has recently been suggested to allow the immobilization of the broad spectrum antibiotic doxycycline on titanium surfaces, the involvement of hydride in binding the biomolecule onto titanium remains poorly understood. To gain better understanding of the influence this immobilization process has on titanium surfaces, mirror-polished commercially pure titanium surfaces were cathodically polarized in the presence of doxycycline and the modified surfaces were thoroughly characterized using atomic force microscopy, electron microscopy, secondary ion mass spectrometry, and angle-resolved X-ray spectroscopy. We demonstrated that no hydride was created during the polarization process. Doxycycline was found to be attached to an oxide layer that was modified during the electrochemical process. A bacterial assay using bioluminescent Staphylococcus epidermidis Xen43 showed the ability of the coating to reduce bacterial colonization and planktonic bacterial growth. - Highlights: • Titanium hydride was found not to be involved in immobilization of doxycycline. • Doxycycline coating was strongly bound to a modified surface oxide layer. • Effect of coatings tested using a dynamic bacteria assay based on bioluminescence. • Topmost layer of adsorbed doxycycline was shown to have strong antibacterial effect.

  20. Planetary surface characterization from dual-polarization radar observations

    Science.gov (United States)

    Virkki, Anne; Planetary Radar Team of the Arecibo Observatory

    2017-10-01

    We present a new method to investigate the physical properties of planetary surfaces using dual-polarization radar measurements. The number of radar observations has increased radically during the last five years, allowing us to compare the radar scattering properties of different small-body populations and compositional types. There has also been progress in the laboratory studies of the materials that are relevant to asteroids and comets.In a typical planetary radar measurement a circularly polarized signal is transmitted using a frequency of 2380 MHz (wavelength of 12.6 cm) or 8560 MHz (3.5 cm). The echo is received simultaneously in the same circular (SC) and the opposite circular (OC) polarization as the transmitted signal. The delay and doppler frequency of the signal give highly accurate astrometric information, and the intensity and the polarization are suggestive of the physical properties of the target's near-surface.The radar albedo describes the radar reflectivity of the target. If the effective near-surface is smooth and homogeneous in the wavelength-scale, the echo is received fully in the OC polarization. Wavelength-scale surface roughness or boulders within the effective near-surface volume increase the received echo power in both polarizations. However, there is a lack in the literature describing exactly how the physical properties of the target affect the radar albedo in each polarization, or how they can be derived from the radar measurements.To resolve this problem, we utilize the information that the diffuse components of the OC and SC parts are correlated when the near-surface contains wavelength-scale scatterers such as boulders. A linear least-squares fit to the detected values of OC and SC radar albedos allows us to separate the diffusely scattering part from the quasi-specular part. Combined with the spectro-photometric information of the target and laboratory studies of the permittivity-density dependence, the method provides us with a

  1. Right- and left-handed rules on the transverse spin angular momentum of a surface wave of photonic crystal.

    Science.gov (United States)

    Hu, Jinbing; Xia, Tongnan; Cai, Xiaoshu; Tian, Shengnan; Guo, Hanming; Zhuang, Songlin

    2017-07-01

    By investigating the surface wave of photonic crystal, we put forward two sets of rules: the right-handed screw rule, judging the transverse spin angular momentum (SAM) directions according to the propagation direction of the surface wave; and the left-handed rule, judging the excitation direction of the surface wave in accordance to the SAM direction of incident circularly polarized light and the relative position of the dipole-like scatterer with respect to the interface where the surface wave propagates. Both right- and left-handed rules apply to the interface consisting of opposite-sign-permittivity materials. With the help of these two sets of rules, it is convenient to judge the direction of the transverse SAM and the excited surface wave, which facilitate the application involving transverse SAM of the surface wave.

  2. Resonant surface acoustic wave chemical detector

    Science.gov (United States)

    Brocato, Robert W.; Brocato, Terisse; Stotts, Larry G.

    2017-08-08

    Apparatus for chemical detection includes a pair of interdigitated transducers (IDTs) formed on a piezoelectric substrate. The apparatus includes a layer of adsorptive material deposited on a surface of the piezoelectric substrate between the IDTs, where each IDT is conformed, and is dimensioned in relation to an operating frequency and an acoustic velocity of the piezoelectric substrate, so as to function as a single-phase uni-directional transducer (SPUDT) at the operating frequency. Additionally, the apparatus includes the pair of IDTs is spaced apart along a propagation axis and mutually aligned relative to said propagation axis so as to define an acoustic cavity that is resonant to surface acoustic waves (SAWs) at the operating frequency, where a distance between each IDT of the pair of IDTs ranges from 100 wavelength of the operating frequency to 400 wavelength of the operating frequency.

  3. Surface acoustic wave actuated cell sorting (SAWACS).

    Science.gov (United States)

    Franke, T; Braunmüller, S; Schmid, L; Wixforth, A; Weitz, D A

    2010-03-21

    We describe a novel microfluidic cell sorter which operates in continuous flow at high sorting rates. The device is based on a surface acoustic wave cell-sorting scheme and combines many advantages of fluorescence activated cell sorting (FACS) and fluorescence activated droplet sorting (FADS) in microfluidic channels. It is fully integrated on a PDMS device, and allows fast electronic control of cell diversion. We direct cells by acoustic streaming excited by a surface acoustic wave which deflects the fluid independently of the contrast in material properties of deflected objects and the continuous phase; thus the device underlying principle works without additional enhancement of the sorting by prior labelling of the cells with responsive markers such as magnetic or polarizable beads. Single cells are sorted directly from bulk media at rates as fast as several kHz without prior encapsulation into liquid droplet compartments as in traditional FACS. We have successfully directed HaCaT cells (human keratinocytes), fibroblasts from mice and MV3 melanoma cells. The low shear forces of this sorting method ensure that cells survive after sorting.

  4. Study of Planar Surface Wave Excited Plasma

    Science.gov (United States)

    Tian, Caizhong

    2008-10-01

    The need for plasma processing has increased as miniaturization in semiconductor manufacturing goes ahead. In these processes, a large-diameter plasma source is required with respect to 300mm wafer size. A Radial Line Slot Antenna (RLSA) driven surface-wave-sustained plasma is a potential best candidate to various applications with respect to damage free process. Many researches focus on the control of plasma density and electron temperature in RLSA technique. However, the plasma stability and uniformity control are less implemented in the practice. In recent years, we study sheath formation and plasma behavior at the interface, where the surface wave propagate, by using electromagnetic particle-in-cell simulation techniques. The simulations include the effects of ionization, and allow us to study the buildup of plasma density associated with ionization in the presence of the large fields of the RF-enhanced sheath. Our results show both the mechanism of plasma generation and heating at the plasma dielectric interface and the strong effect on geometric design of dielectric. Various scenarios are of interest, and help us to design an optimal RLSA driven plasma source, where the plasma stability and uniformity are firmly sustained under the various process conditions. Plasma diagnosis is carried out to reveal the more essential difference in plasma behavior between our RLSA and a custom inductively coupled plasma (ICP) source.

  5. Assessing ground compaction via time lapse surface wave analysis

    Czech Academy of Sciences Publication Activity Database

    Dal Moro, Giancarlo; Al-Arifi, N.; Moustafa, S.S.R.

    2016-01-01

    Roč. 13, č. 3 (2016), s. 249-256 ISSN 1214-9705 Institutional support: RVO:67985891 Keywords : Full velocity spectrum (FVS) analysis * ground compaction * ground compaction * phase velocities * Rayleigh waves * seismic data inversion * surface wave dispersion * surface waves Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 0.699, year: 2016

  6. Surface waves in fibre-reinforced anisotropic elastic media

    Indian Academy of Sciences (India)

    reinforced solid elastic media. First, the theory of general surface waves has been derived and applied to study the particular cases of surface waves – Rayleigh, Love and Stoneley types. The wave velocity equations are found to be in agreement with ...

  7. Surface waves in a cylindrical borehole through partially-saturated ...

    Indian Academy of Sciences (India)

    M D Sharma

    published online 14 February 2018. Propagation of surface waves is discussed in a cylindrical borehole through a liquid-saturated porous solid of infinite extent. ...... 1992). In the dictionary of exploration geophysics, pseudo-Rayleigh waves are identified as the ground roll, which is a particular type of surface wave that.

  8. Tantalum surface oxidation: Bond relaxation, energy entrapment, and electron polarization

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Yongling [Key Laboratory of Low-Dimensional Materials and Application Technologies (Ministry of Education), Hunan Provincial Key Laboratory of Thin Film Materials and Devices, Faculty of Materials Science and Engineering, Xiangtan University, Hunan 411105 (China); Bo, Maolin [Yangtze Normal University, College of Mechanical and Electrical Engineering, Chongqing 408100 (China); Wang, Yan [School of Information and Electronic Engineering, Hunan University of Science and Technology, Hunan 411201 (China); Liu, Yonghui [Key Laboratory of Low-Dimensional Materials and Application Technologies (Ministry of Education), Hunan Provincial Key Laboratory of Thin Film Materials and Devices, Faculty of Materials Science and Engineering, Xiangtan University, Hunan 411105 (China); Sun, Chang Q. [NOVITAS, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Huang, Yongli, E-mail: huangyongli@xtu.edu.cn [Key Laboratory of Low-Dimensional Materials and Application Technologies (Ministry of Education), Hunan Provincial Key Laboratory of Thin Film Materials and Devices, Faculty of Materials Science and Engineering, Xiangtan University, Hunan 411105 (China)

    2017-02-28

    Graphical abstract: The bond, electron and energy relaxation result in core level energy shift, local densification, quantum entrapment and electron polarization of bonding electrons. - Highlights: • Increasing the oxygen coverage lowers the adsorption energy associated with lattice reconstruction. • Electrons transfer from Ta surface atoms to sp-hydrated oxygen, creating dipole moment that decreases the work function. • Oxygen chemisorption modified valence density-of-state (DOS) for Ta with four excessive DOS features: O−Ta bonding, O{sup 2−} lone pairs, Ta+ electron holes, and the lone-pair polarized Ta dipoles. • The bond, electron and energy relaxation between surface undercoordinated atoms are responsible for core level energy shift, local densification, quantum entrapment and electron polarization of bonding electrons. - Abstract: A combination of photoelectron spectrometric analysis and density functional theory calculations has enabled reconciliation of the bond-energy-electron relaxation for the Ta(100, 110, 111) surfaces chemisorbed with oxygen at different coverages. Results show that increasing oxygen coverage lowers the adsorption energy associated with lattice reconstruction. Valence electrons transfer from Ta surface atoms to oxygen to create four excessive DOS features in terms of O−Ta bonding, lone pairs of oxygen, Ta{sup +} electron holes, and polarized Ta dipoles. Oxidation proceeds in the following dynamics: oxygen gets electrons from two neighboring Ta atoms left behind Ta{sup +}; the sp{sup 3}-orbital hybridization takes place with additional two electron lone pairs, the lone pairs polarize the other two Ta neighbors becoming dipoles. X-ray photoelectron spectral analysis results in the 4f binding energy of an isolated Ta atom and its shift upon bond formation and oxidation. Exercises provide not only a promising numerical approach for the quantitative information about the bond and electronic behavior but also consistent

  9. Second-harmonic generation in shear wave beams with different polarizations

    Energy Technology Data Exchange (ETDEWEB)

    Spratt, Kyle S., E-mail: sprattkyle@gmail.com; Ilinskii, Yurii A.; Zabolotskaya, Evgenia A.; Hamilton, Mark F. [Applied Research Laboratories, The University of Texas at Austin, P. O. Box 8029, Austin, Texas 78713–8029, US (United States)

    2015-10-28

    A coupled pair of nonlinear parabolic equations was derived by Zabolotskaya [1] that model the transverse components of the particle motion in a collimated shear wave beam propagating in an isotropic elastic solid. Like the KZK equation, the parabolic equation for shear wave beams accounts consistently for the leading order effects of diffraction, viscosity and nonlinearity. The nonlinearity includes a cubic nonlinear term that is equivalent to that present in plane shear waves, as well as a quadratic nonlinear term that is unique to diffracting beams. The work by Wochner et al. [2] considered shear wave beams with translational polarizations (linear, circular and elliptical), wherein second-order nonlinear effects vanish and the leading order nonlinear effect is third-harmonic generation by the cubic nonlinearity. The purpose of the current work is to investigate the quadratic nonlinear term present in the parabolic equation for shear wave beams by considering second-harmonic generation in Gaussian beams as a second-order nonlinear effect using standard perturbation theory. In order for second-order nonlinear effects to be present, a broader class of source polarizations must be considered that includes not only the familiar translational polarizations, but also polarizations accounting for stretching, shearing and rotation of the source plane. It is found that the polarization of the second harmonic generated by the quadratic nonlinearity is not necessarily the same as the polarization of the source-frequency beam, and we are able to derive a general analytic solution for second-harmonic generation from a Gaussian source condition that gives explicitly the relationship between the polarization of the source-frequency beam and the polarization of the second harmonic.

  10. Polarized Microwave Background Technologies for Inflationary Gravitational Wave Detection

    Data.gov (United States)

    National Aeronautics and Space Administration — The detection of primordial gravitational waves (PGWs) from the epoch of inflation is one of the next majors goals in cosmology. These PGWs leave a signature on the...

  11. Near-perfect conversion of a propagating plane wave into a surface wave using metasurfaces

    Science.gov (United States)

    Tcvetkova, S. N.; Kwon, D.-H.; Díaz-Rubio, A.; Tretyakov, S. A.

    2018-03-01

    In this paper theoretical and numerical studies of perfect/nearly perfect conversion of a plane wave into a surface wave are presented. The problem of determining the electromagnetic properties of an inhomogeneous lossless boundary which would fully transform an incident plane wave into a surface wave propagating along the boundary is considered. An approximate field solution which produces a slowly growing surface wave and satisfies the energy conservation law is discussed and numerically demonstrated. The results of the study are of great importance for the future development of such devices as perfect leaky-wave antennas and can potentially lead to many novel applications.

  12. Raman backscattering of circularly polarized electromagnetic waves propagating along a magnetic field

    International Nuclear Information System (INIS)

    Maraghechi, B.; Willett, J.e.

    1979-01-01

    The stimulated Raman backscattering of an intense electromagnetic wave propagating in the extraordinary mode along a uniform, static magnetic field is considered. The dispersion relation for a homogeneous magnetized plasma in the presence of the circularly polarized pump waves is developed in the cold-plasma approximation with the pump frequency above the plasma frequency. Formulas are derived for the threshold νsub(OT) of the parametric instability and for the growth rate γ of the backscattered extraordinary wave and Langmuir wave. The effects of the magnetic field parallel to the direction of propagation on νsub(0T) and γ are studied numerically. (author)

  13. Circular Polarizations of Gravitational Waves from Core-Collapse Supernovae: A Clear Indication of Rapid Rotation.

    Science.gov (United States)

    Hayama, Kazuhiro; Kuroda, Takami; Nakamura, Ko; Yamada, Shoichi

    2016-04-15

    We propose to employ the circular polarization of gravitational waves emitted by core-collapse supernovae as an unequivocal indication of rapid rotation deep in their cores just prior to collapse. It has been demonstrated by three dimensional simulations that nonaxisymmetric accretion flows may develop spontaneously via hydrodynamical instabilities in the postbounce cores. It is not surprising, then, that the gravitational waves emitted by such fluid motions are circularly polarized. We show, in this Letter, that a network of the second generation detectors of gravitational waves worldwide may be able to detect such polarizations up to the opposite side of the Galaxy as long as the rotation period of the core is shorter than a few seconds prior to collapse.

  14. Polarization of concave domains by traveling wave pinning.

    Directory of Open Access Journals (Sweden)

    Slawomir Bialecki

    Full Text Available Pattern formation is one of the most fundamental yet puzzling phenomena in physics and biology. We propose that traveling front pinning into concave portions of the boundary of 3-dimensional domains can serve as a generic gradient-maintaining mechanism. Such a mechanism of domain polarization arises even for scalar bistable reaction-diffusion equations, and, depending on geometry, a number of stationary fronts may be formed leading to complex spatial patterns. The main advantage of the pinning mechanism, with respect to the Turing bifurcation, is that it allows for maintaining gradients in the specific regions of the domain. By linking the instant domain shape with the spatial pattern, the mechanism can be responsible for cellular polarization and differentiation.

  15. THz detectors using surface Josephson plasma waves in layered superconductors

    International Nuclear Information System (INIS)

    Savel'ev, Sergey; Yampol'skii, Valery; Nori, Franco

    2006-01-01

    We describe a proposal for THz detectors based on the excitation of surface waves, in layered superconductors, at frequencies lower than the Josephson plasma frequency ω J . These waves propagate along the vacuum-superconductor interface and are attenuated in both transverse directions out of the surface (i.e., towards the superconductor and towards the vacuum). The surface Josephson plasma waves are also important for the complete suppression of the specular reflection from a sample (Wood's anomalies, used for gratings) and produce a huge enhancement of the wave absorption, which can be used for the detection of THz waves

  16. Quasilinear ridge structures in water surface waves

    Science.gov (United States)

    Blümel, R.; Davidson, I. H.; Reinhardt, W. P.; Lin, H.; Sharnoff, M.

    1992-02-01

    Nodal patterns of stationary capillary waves formed on the surface of water enclosed in an agitated ripple tank with circular and stadium-shaped cylindrical walls are examined in the low-frequency (ν700 Hz) regimes. In the low-frequency regime, in agreement with predictions of quantum-chaos theory, the shape of the tank's boundaries (integrable or nonintegrable) dictates the type of nodal patterns obtained. In the high-frequency regime we obtain nodal patterns characterized by short-range order (called ``scarlets'' because they are believed to be the precursors of quantum scars), as recently predicted in the quantum-chaos context by P. O'Connor, J. Gehlen, and E. J. Heller [Phys. Rev. Lett. 58, 1296 (1987)].

  17. Nonplanar electrostatic shock waves in an opposite polarity dust ...

    Indian Academy of Sciences (India)

    A rigorous theoretical investigation has been carried out on the propagation of nonplanar (cylindrical and spherical) dust-acoustic shock waves (DASHWs) in a collisionless four-component unmagnetized dusty plasmasystem containing massive, micron-sized, positively and negatively charged inertial dust grains along with ...

  18. Surface Plasmon Wave Adapter Designed with Transformation Optics

    DEFF Research Database (Denmark)

    Zhang, Jingjing; Xiao, Sanshui; Wubs, Martijn

    2011-01-01

    On the basis of transformation optics, we propose the design of a surface plasmon wave adapter which confines surface plasmon waves on non-uniform metal surfaces and enables adiabatic mode transformation of surface plasmon polaritons with very short tapers. This adapter can be simply achieved wit...... with homogeneous anisotropic naturally occurring materials or subwavelength grating-structured dielectric materials. Full wave simulations based on a finite-element method have been performed to validate our proposal.......On the basis of transformation optics, we propose the design of a surface plasmon wave adapter which confines surface plasmon waves on non-uniform metal surfaces and enables adiabatic mode transformation of surface plasmon polaritons with very short tapers. This adapter can be simply achieved...

  19. Frequency and wavelength prediction of ultrasonic induced liquid surface waves.

    Science.gov (United States)

    Mahravan, Ehsan; Naderan, Hamid; Damangir, Ebrahim

    2016-12-01

    A theoretical investigation of parametric excitation of liquid free surface by a high frequency sound wave is preformed, using potential flow theory. Pressure and velocity distributions, resembling the sound wave, are applied to the free surface of the liquid. It is found that for impinging wave two distinct capillary frequencies will be excited: One of them is the same as the frequency of the sound wave, and the other is equal to the natural frequency corresponding to a wavenumber equal to the horizontal wavenumber of the sound wave. When the wave propagates in vertical direction, mathematical formulation leads to an equation, which has resonance frequency equal to half of the excitation frequency. This can explain an important contradiction between the frequency and the wavelength of capillary waves in the two cases of normal and inclined interaction of the sound wave and the free surface of the liquid. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Effect of polarization force on large amplitude dust kinetic Alfvén waves

    Science.gov (United States)

    Singh, M.; Kohli, R.; Kaur, N.; Saini, N. S.

    2018-01-01

    Effect of polarization force on dust kinetic Alfvén waves (DKAWs) has been studied in this paper. We incorporated the effect of polarization in fluid model equations and derived the expression for Sagdeev pseudopotential. From the numerical analysis, it is seen that DKAWs are significantly affected by the variation of polarization force, plasma beta and Mach number. This study may be useful in understanding the formation of coherent nonlinear structures and diagnostics of dusts in laboratory as well as in space/astrophysical plasma environments.

  1. Experimental study of dual polarized radar return from the sea surface

    Science.gov (United States)

    Ermakov, S. A.; Kapustin, I. A.; Lavrova, O. Yu.; Molkov, A. A.; Sergievskaya, I. A.; Shomina, O. V.

    2017-10-01

    Dual-polarized microwave radars are of particular interest nowadays as perspective tool of ocean remote sensing. Microwave radar backscattering at moderate and large incidence angles according to conventional models is determined by resonance (Bragg) surface waves typically of cm-scale wavelength range. Some recent experiments have indicated, however, that an additional, non Bragg component (NBC) contributes to the radar return. The latter is considered to occur due to wave breaking. At present our understanding of the nature of different components of radar return is still poor. This paper presents results of field experiment using an X-/C-/S-band Doppler radar operating at HH- and VVpolarizations. The intensity and radar Doppler shifts for Bragg and non Bragg components are retrieved from measurements of VV and HH radar returns. Analysis of a ratio of VV and HH radar backscatter - polarization ratio (PR) has demonstrated a significant role of a non Bragg component. NBC contributes significantly to the total radar backscatter, in particular, at moderate incidence angles (about 50-70 deg.) it is 2-3 times smaller than VV Bragg component and several times larger that HH Bragg component. Both NBC and BC depend on azimuth angle, being minimal for cross wind direction, but NBC is more isotropic than BC. It is obtained that velocities of scatterers retrieved from radar Doppler shifts are different for Bragg waves and for non Bragg component; NBC structures are "faster" than Bragg waves particularly for upwind radar observations. Bragg components propagate approximately with phase velocities of linear gravity-capillary waves (when accounting for wind drift). Velocities of NBC scatterers depend on radar band, being the largest for S-band and the smallest at X-band, this means that different structures on the water surface are responsible for non Bragg scattering in a given radar band.

  2. Polarization state of an inhomogenously refracted compressional-wave induced at interface between two anisotropic rocks.

    Science.gov (United States)

    Fa, Lin; Li, Wenya; Zhao, Jie; Han, Yonglan; Liang, Meng; Ding, Pengfei; Zhao, Meishan

    2017-01-01

    This paper is concerned with the polarization states of an inhomogenously refracted P-wave induced from the interface of two anisotropic rocks. Two realistic physical models have been studied: Model-1 is an interface between anisotropic shale and Taylor sandstone; Model-2 is an interface between anisotropic shale and oil shale. For each model, an analytical expression of the polarization states was derived and its elliptical-polarization trajectory was examined. It is shown that an anomalous incident-angle leads not only to a sudden elliptical-polarization directional variation but also to an abrupt change in size and shape of its elliptical-polarization trajectory. The calculated results and analyses provide a theoretical base for the understandings of an anomalous incident-angle recently reported in the literature [e.g., Fa, Fa, Zhang, Ding, Gong, Li, Li, Tang, and Zhao (2015). Sci. Rep. 5, 12700].

  3. Shock wave polarizations and optical metrics in the Born and the Born–Infeld electrodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Minz, Christoph, E-mail: christoph.minz@alumni.tu-berlin.de [Institute of Theoretical Physics, Technische Universität Berlin, Hardenbergstr. 36, D-10623 Berlin (Germany); Borzeszkowski, Horst-Heino von, E-mail: borzeszk@mailbox.tu-berlin.de [Institute of Theoretical Physics, Technische Universität Berlin, Hardenbergstr. 36, D-10623 Berlin (Germany); Chrobok, Thoralf, E-mail: tchrobok@mailbox.tu-berlin.de [Institute of Theoretical Physics, Technische Universität Berlin, Hardenbergstr. 36, D-10623 Berlin (Germany); Schellstede, Gerold, E-mail: schellst@physik.fu-berlin.de [ZARM (Center of Applied Space Technology and Microgravity), Universität Bremen, Am Fallturm, D-28359 Bremen (Germany)

    2016-01-15

    We analyze the behavior of shock waves in nonlinear theories of electrodynamics. For this, by use of generalized Hadamard step functions of increasing order, the electromagnetic potential is developed in a series expansion near the shock wave front. This brings about a corresponding expansion of the respective electromagnetic field equations which allows for deriving relations that determine the jump coefficients in the expansion series of the potential. We compute the components of a suitable gauge-normalized version of the jump coefficients given for a prescribed tetrad compatible with the shock front foliation. The solution of the first-order jump relations shows that, in contrast to linear Maxwell’s electrodynamics, in general the propagation of shock waves in nonlinear theories is governed by optical metrics and polarization conditions describing the propagation of two differently polarized waves (leading to a possible appearance of birefringence). In detail, shock waves are analyzed in the Born and Born–Infeld theories verifying that the Born–Infeld model exhibits no birefringence and the Born model does. The obtained results are compared to those ones found in literature. New results for the polarization of the two different waves are derived for Born-type electrodynamics.

  4. Vector wave diffraction pattern of slits masked by polarizing devices

    Indian Academy of Sciences (India)

    (7) where X = πud is the observation plane coordinate. If an analyser P(θ) is placed at the output side whose transmission axis makes an angle θ with the chosen x-axis, the vector wave amplitude obtained at the observation plane is then given by. F(u)WA = P(θ)F(u), where. P(θ) = ∣. ∣. ∣. ∣ cos2 θ sin θ cos θ sin θ cos θ.

  5. Surface Acoustic Wave (SAW Vibration Sensors

    Directory of Open Access Journals (Sweden)

    Jerzy Filipiak

    2011-12-01

    Full Text Available In the paper a feasibility study on the use of surface acoustic wave (SAW vibration sensors for electronic warning systems is presented. The system is assembled from concatenated SAW vibration sensors based on a SAW delay line manufactured on a surface of a piezoelectric plate. Vibrations of the plate are transformed into electric signals that allow identification of the sensor and localization of a threat. The theoretical study of sensor vibrations leads us to the simple isotropic model with one degree of freedom. This model allowed an explicit description of the sensor plate movement and identification of the vibrating sensor. Analysis of frequency response of the ST-cut quartz sensor plate and a damping speed of its impulse response has been conducted. The analysis above was the basis to determine the ranges of parameters for vibrating plates to be useful in electronic warning systems. Generally, operation of electronic warning systems with SAW vibration sensors is based on the analysis of signal phase changes at the working frequency of delay line after being transmitted via two circuits of concatenated four-terminal networks. Frequencies of phase changes are equal to resonance frequencies of vibrating plates of sensors. The amplitude of these phase changes is proportional to the amplitude of vibrations of a sensor plate. Both pieces of information may be sent and recorded jointly by a simple electrical unit.

  6. Surface-polarization electrooptic effect in a nematic liquid crystal

    International Nuclear Information System (INIS)

    Lavrentovich, O.D.; Nazarenko, V.G.; Pergamenshchik, V.M.; Sergan, V.V.; Sorokin, V.M.

    1991-01-01

    A new electrooptic effect was observed experimentally in a homeotropic layer of a nematic with a positive anisotropy of the permittivity and of the electrical conductivity. This effect appeared in an external vertical static electric field and was manifested by the appearance of circular or elongated domain structures due to static distortions of the director near the anode or cathode of a cell. The polarity of the effect depended on the nature of an orienting coating. The origin of the effect was the nematic surface polarization which was sufficiently strong (∼10 -2 dyn 1/2 ) to induce an instability even under the conditions where other mechanisms (dielectric, flexoelectric, anisotropic electrohydrodynamic) impeded stability. Special attention was given to the separation of the surface polarization mechanism of the investigated effect from the flexoelectric and isotropic electrodynamic mechanisms. A hierarchy of static structures observed experimentally was clearly accounted for by a theory based on an equilibrium thermodynamic approach allowing for the anisotropic properties and for the real geometry of the system

  7. Transformation of second sound into surface waves in superfluid helium

    International Nuclear Information System (INIS)

    Khalatnikov, I.M.; Kolmakov, G.V.; Pokrovsky, V.L.

    1995-01-01

    The Hamiltonian theory of superfluid liquid with a free boundary is developed. Nonlinear amplitudes of parametric Cherenkov radiation of a surface wave by second sound and the inner decay of second sound waves are found. Threshold amplitudes of second sound waves for these two processes are determined. 4 refs

  8. Phase spectral composition of wind generated ocean surface waves

    Digital Repository Service at National Institute of Oceanography (India)

    Varkey, M.J.

    A study of the composition of the phase spectra of wind generated ocean surface waves is carried out using wave records collected employing a ship borne wave recorder. It is found that the raw phase spectral estimates could be fitted by the Uniform...

  9. Nonlinear interaction of the surface waves at a plasma boundary

    International Nuclear Information System (INIS)

    Dolgopolov, V.V.; El-Naggar, I.A.; Hussein, A.M.; Khalil, Sh.M.

    1976-01-01

    Amplitudes of electromagnetic waves with combination frequencies, radiating from the plasma boundary due to nonlinear interaction of the surface waves, have been found. Previous papers on this subject did not take into account that the tangential components of the electric field of waves with combination frequencies were discontinuous at the plasma boundary. (Auth.)

  10. Temperature-mediated transition from Dyakonov-Tamm surface waves to surface-plasmon-polariton waves

    Science.gov (United States)

    Chiadini, Francesco; Fiumara, Vincenzo; Mackay, Tom G.; Scaglione, Antonio; Lakhtakia, Akhlesh

    2017-08-01

    The effect of changing the temperature on the propagation of electromagnetic surface waves (ESWs), guided by the planar interface of a homogeneous isotropic temperature-sensitive material (namely, InSb) and a temperature-insensitive structurally chiral material (SCM) was numerically investigated in the terahertz frequency regime. As the temperature rises, InSb transforms from a dissipative dielectric material to a dissipative plasmonic material. Correspondingly, the ESWs transmute from Dyakonov-Tamm surface waves into surface-plasmon-polariton waves. The effects of the temperature change are clearly observed in the phase speeds, propagation distances, angular existence domains, multiplicity, and spatial profiles of energy flow of the ESWs. Remarkably large propagation distances can be achieved; in such instances the energy of an ESW is confined almost entirely within the SCM. For certain propagation directions, simultaneous excitation of two ESWs with (i) the same phase speeds but different propagation distances or (ii) the same propagation distances but different phase speeds are also indicated by our results.

  11. Polarization properties of Gendrin mode waves observed in the Earth's magnetosphere: observations and theory

    Directory of Open Access Journals (Sweden)

    O. P. Verkhoglyadova

    2009-12-01

    Full Text Available We show a case of an outer zone magnetospheric electromagnetic wave propagating at the Gendrin angle, within uncertainty of the measurements. The chorus event occurred in a "minimum B pocket". For the illustrated example, the measured angle of wave propagation relative to the ambient magnetic field θkB was 58°±4°. For this event the theoretical Gendrin angle was 62°. Cold plasma model is used to demonstrate that Gendrin mode waves are right-hand circularly polarized, in excellent agreement with the observations.

  12. Circularly polarized few-optical-cycle solitons in the short-wave-approximation regime

    Energy Technology Data Exchange (ETDEWEB)

    Leblond, Herve [Laboratoire de Photonique d' Angers, EA 4464, Universite d' Angers, 2 Boulevard Lavoisier, F-49045 Angers Cedex 01 (France); Triki, Houria [Radiation Physics Laboratory, Department of Physics, Faculty of Sciences, Badji Mokhtar University, Post Office Box 12, 23000 Annaba (Algeria); Mihalache, Dumitru [Laboratoire de Photonique d' Angers, EA 4464, Universite d' Angers, 2 Boulevard Lavoisier, F-49045 Angers Cedex 01 (France); Horia Hulubei National Institute for Physics and Nuclear Engineering (IFIN-HH), 407 Atomistilor, RO-077125 Magurele-Bucharest (Romania); Academy of Romanian Scientists, 54 Splaiul Independentei, RO-050094 Bucharest (Romania)

    2011-08-15

    We consider the propagation of few-cycle pulses (FCPs) beyond the slowly varying envelope approximation in media in which the dynamics of constituent atoms is described by a two-level Hamiltonian by taking into account the wave polarization. We consider the short-wave approximation, assuming that the resonance frequency of the two-level atoms is well below the inverse of the characteristic duration of the optical pulse. By using the reductive perturbation method (multiscale analysis), we derive from the Maxwell-Bloch-Heisenberg equations the governing evolution equations for the two polarization components of the electric field in the first order of the perturbation approach. We show that propagation of circularly polarized (CP) few-optical-cycle solitons is described by a system of coupled nonlinear equations, which reduces in the scalar case to the standard sine Gordon equation describing the dynamics of linearly polarized FCPs in the short-wave-approximation regime. By direct numerical simulations, we calculate the lifetime of CP FCPs, and we study the transition to two orthogonally polarized single-humped pulses as a generic route of their instability.

  13. Reactive surface organometallic complexes observed using dynamic nuclear polarization surface enhanced NMR spectroscopy

    KAUST Repository

    Pump, Eva

    2016-08-15

    Dynamic Nuclear Polarization Surface Enhanced NMR Spectroscopy (DNP SENS) is an emerging technique that allows access to high-sensitivity NMR spectra from surfaces. However, DNP SENS usually requires the use of radicals as an exogenous source of polarization, which has so far limited applications for organometallic surface species to those that do not react with the radicals. Here we show that reactive surface species can be studied if they are immobilized inside porous materials with suitably small windows, and if bulky nitroxide bi-radicals (here TEKPol) are used as the polarization source and which cannot enter the pores. The method is demonstrated by obtaining significant DNP enhancements from highly reactive complelxes [(equivalent to Si-O-)W(Me)(5)] supported on MCM-41, and effects of pore size (6.0, 3.0 and 2.5 nm) on the performance are discussed.

  14. Opportunities and pitfalls in surface-wave interpretation

    KAUST Repository

    Schuster, Gerard T.

    2017-01-21

    Many explorationists think of surface waves as the most damaging noise in land seismic data. Thus, much effort is spent in designing geophone arrays and filtering methods that attenuate these noisy events. It is now becoming apparent that surface waves can be a valuable ally in characterizing the near-surface geology. This review aims to find out how the interpreter can exploit some of the many opportunities available in surface waves recorded in land seismic data. For example, the dispersion curves associated with surface waves can be inverted to give the S-wave velocity tomogram, the common-offset gathers can reveal the presence of near-surface faults or velocity anomalies, and back-scattered surface waves can be migrated to detect the location of near-surface faults. However, the main limitation of surface waves is that they are typically sensitive to S-wave velocity variations no deeper than approximately half to one-third the dominant wavelength. For many exploration surveys, this limits the depth of investigation to be no deeper than approximately 0.5-1.0 km.

  15. Polarization properties of optical phase conjugation by two-photon resonant degenerate four-wave mixing

    Science.gov (United States)

    Kauranen, Martti; Gauthier, Daniel J.; Malcuit, Michelle S.; Boyd, Robert W.

    1989-08-01

    We develop a semiclassical theory of the polarization properties of phase conjugation by two-photon resonant degenerate four-wave mixing. The theory includes the effects of saturation by the pump waves. We solve the density-matrix equations of motion in steady state for a nonlinear medium consisting of stationary atoms with a ground and excited state connected by two-photon transitions. As an illustration of the general results, we consider an S0-->S0 two-photon transition, which is known to lead to perfect polarization conjugation in the limit of third-order theory. We show that the fidelity of the polarization-conjugation process is degraded for excessively large pump intensities. The degradation can occur both due to transfer of population to the excited state and due to nonresonant Stark shifts. Theoretical results are compared to those of a recent experiment [Malcuit, Gauthier, and Boyd, Opt. Lett. 13, 663 (1988)].

  16. Unidirectional evanescent-wave coupling from circularly polarized electric and magnetic dipoles: An angular spectrum approach

    Science.gov (United States)

    Picardi, Michela F.; Manjavacas, Alejandro; Zayats, Anatoly V.; Rodríguez-Fortuño, Francisco J.

    2017-06-01

    Unidirectional evanescent-wave coupling from circularly polarized dipole sources is one of the most striking types of evidence of spin-orbit interactions of light and an inherent property of circularly polarized dipoles. Polarization handedness self-determines propagation direction of guided modes. In this paper, we compare two different approaches currently used to describe this phenomenon: the first requires the evaluation of the coupling amplitude between dipole and waveguide modes, while the second is based on the calculation of the angular spectrum of the dipole. We present an analytical expression of the angular spectrum of dipole radiation, unifying the description for both electric and magnetic dipoles. The symmetries unraveled by the implemented formalism show the existence of specific terms in the dipole spectrum which can be recognized as being directly responsible for directional evanescent-wave coupling. This provides a versatile tool for both a comprehensive understanding of the phenomenon and a fully controllable engineering of directionality of guided modes.

  17. Universal power law of the gravity wave manifestation in the AIM CIPS polar mesospheric cloud images

    Directory of Open Access Journals (Sweden)

    P. Rong

    2018-01-01

    Full Text Available We aim to extract a universal law that governs the gravity wave manifestation in polar mesospheric clouds (PMCs. Gravity wave morphology and the clarity level of display vary throughout the wave population manifested by the PMC albedo data. Higher clarity refers to more distinct exhibition of the features, which often correspond to larger variances and a better-organized nature. A gravity wave tracking algorithm based on the continuous Morlet wavelet transform is applied to the PMC albedo data at 83 km altitude taken by the Aeronomy of Ice in the Mesosphere (AIM Cloud Imaging and Particle Size (CIPS instrument to obtain a large ensemble of the gravity wave detections. The horizontal wavelengths in the range of  ∼ 20–60 km are the focus of the study. It shows that the albedo (wave power statistically increases as the background gets brighter. We resample the wave detections to conform to a normal distribution to examine the wave morphology and display clarity beyond the cloud brightness impact. Sample cases are selected at the two tails and the peak of the normal distribution to represent the full set of wave detections. For these cases the albedo power spectra follow exponential decay toward smaller scales. The high-albedo-power category has the most rapid decay (i.e., exponent  =  −3.2 and corresponds to the most distinct wave display. The wave display becomes increasingly blurrier for the medium- and low-power categories, which hold the monotonically decreasing spectral exponents of −2.9 and −2.5, respectively. The majority of waves are straight waves whose clarity levels can collapse between the different brightness levels, but in the brighter background the wave signatures seem to exhibit mildly turbulent-like behavior.

  18. Universal power law of the gravity wave manifestation in the AIM CIPS polar mesospheric cloud images

    Science.gov (United States)

    Rong, Pingping; Yue, Jia; Russell, James M., III; Siskind, David E.; Randall, Cora E.

    2018-01-01

    We aim to extract a universal law that governs the gravity wave manifestation in polar mesospheric clouds (PMCs). Gravity wave morphology and the clarity level of display vary throughout the wave population manifested by the PMC albedo data. Higher clarity refers to more distinct exhibition of the features, which often correspond to larger variances and a better-organized nature. A gravity wave tracking algorithm based on the continuous Morlet wavelet transform is applied to the PMC albedo data at 83 km altitude taken by the Aeronomy of Ice in the Mesosphere (AIM) Cloud Imaging and Particle Size (CIPS) instrument to obtain a large ensemble of the gravity wave detections. The horizontal wavelengths in the range of ˜ 20-60 km are the focus of the study. It shows that the albedo (wave) power statistically increases as the background gets brighter. We resample the wave detections to conform to a normal distribution to examine the wave morphology and display clarity beyond the cloud brightness impact. Sample cases are selected at the two tails and the peak of the normal distribution to represent the full set of wave detections. For these cases the albedo power spectra follow exponential decay toward smaller scales. The high-albedo-power category has the most rapid decay (i.e., exponent = -3.2) and corresponds to the most distinct wave display. The wave display becomes increasingly blurrier for the medium- and low-power categories, which hold the monotonically decreasing spectral exponents of -2.9 and -2.5, respectively. The majority of waves are straight waves whose clarity levels can collapse between the different brightness levels, but in the brighter background the wave signatures seem to exhibit mildly turbulent-like behavior.

  19. HF Surface Wave Radar Operation in Adverse Conditions

    National Research Council Canada - National Science Library

    Ponsford, Anthony M; Dizaji, Reza M; McKerracher, Richard

    2005-01-01

    ...) system based on HF Surface Wave Radar (HFSWR). the primary objective behind the programme was to demonstrate the capability of HFSWR to continuously detect and track surface targets (ships and icebergs...

  20. Surface wave propagation in a fluid-saturated incompressible ...

    Indian Academy of Sciences (India)

    saturated incompressible porous media. Many studies have discussed the surface wave propagation in elastic media and a com- prehensive review is available in the standard texts, e.g., Ewing et al (1957) and Achenbach. (1976). The surface ...

  1. Radio wave propagation in the Martian polar deposits: models and implications for radar sounding.

    Science.gov (United States)

    Ilyushin, Ya. A.

    In the present study the propagation of electromagnetic waves in the northern polar ice sheet of Mars is considered Several different scenarios of the structure of the polar deposits and composition of the ice compatible with previously published observational data are proposed Both analytical and numerical simulations of ultra wide band chirp radar pulse propagating through the cap are performed Approximate approach based on the non-coherent theory of the radiative transfer in layered media has been applied to the problem of the propagation of radar pulses in the polar caps Both 1D and 2D and 3D geometry applicable to the orbital and landed radar instruments are studied The side clutter and phase distortions of the signal are also addressed analyzed The possibilities of retrieval of the geological information depending on transparency of the polar cap for radio waves are discussed If the polar cap is relatively transparent the echo from the base of the sheet should be clearly distinctive and interpretable in terms of basal topography of the cap In the case of moderate optical thickness coherent basal echo is corrupted by strong multiple scattering in the layered structure However some conclusions about basal conditions could be made from the signals for example the subglacial lakes may be detected Finally optically thick polar caps prevent any sounding of the base so only the medium itself can be characterized by GPR measurements e g the impurity content in the ice can be found Ilyushin Y A R Seu

  2. Surface wave propagation characteristics in atmospheric pressure plasma column

    International Nuclear Information System (INIS)

    Pencheva, M; Benova, E; Zhelyazkov, I

    2007-01-01

    In the typical experiments of surface wave sustained plasma columns at atmospheric pressure the ratio of collision to wave frequency (ν/ω) is much greater than unity. Therefore, one might expect that the usual analysis of the wave dispersion relation, performed under the assumption ν/ω = 0, cannot give adequate description of the wave propagation characteristics. In order to study these characteristics we have analyzed the wave dispersion relationship for arbitrary ν/ω. Our analysis includes phase and wave dispersion curves, attenuation coefficient, and wave phase and group velocities. The numerical results show that a turning back point appears in the phase diagram, after which a region of backward wave propagation exists. The experimentally observed plasma column is only in a region where wave propagation coefficient is higher than the attenuation coefficient. At the plasma column end the electron density is much higher than that corresponding to the turning back point and the resonance

  3. Effects of Medium Characteristics on Laser RCS of Airplane with E-Wave Polarization

    Directory of Open Access Journals (Sweden)

    Hosam El-Ocla

    2015-01-01

    Full Text Available Plane wave incidence should be postulated to have an authentic target detection. Practically, the plane wave is incapable usually of keeping its power in the far field especially when propagating through an inhomogeneous medium. Consequently, we assume an incident beam wave with a finite width around the target. In this work, we calculate numerically a laser radar cross section (LRCS of conducting targets having smooth cross sections with inflection points such as airplane in random media. Effects of fluctuations intensity of random media on the LRCS performance are studied in this paper. E-wave polarization (E-wave incidence is considered while the mean target size is approximately twice the wavelength.

  4. Visualizing the phenomena of wave interference, phase-shifting and polarization by interactive computer simulations

    Science.gov (United States)

    Rivera-Ortega, Uriel; Dirckx, Joris

    2015-09-01

    In this manuscript a computer based simulation is proposed for teaching concepts of interference of light (under the scheme of a Michelson interferometer), phase-shifting and polarization states. The user can change some parameters of the interfering waves, such as their amplitude and phase difference in order to graphically represent the polarization state of a simulated travelling wave. Regarding to the interference simulation, the user is able to change the wavelength and type of the interfering waves by selecting combinations between planar and Gaussian profiles, as well as the optical path difference by translating or tilting one of the two mirrors in the interferometer setup, all of this via a graphical user interface (GUI) designed in MATLAB. A theoretical introduction and simulation results for each phenomenon will be shown. Due to the simulation characteristics, this GUI can be a very good non-formal learning resource.

  5. Multi-component joint analysis of surface waves

    Czech Academy of Sciences Publication Activity Database

    Dal Moro, Giancarlo; Moura, R.M.M.; Moustafa, S.S.R.

    2015-01-01

    Roč. 119, AUG (2015), s. 128-138 ISSN 0926-9851 Institutional support: RVO:67985891 Keywords : surface waves * surface wave dispersion * seismic data acquisition * seismic data inversion * velocity spectrum Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.355, year: 2015

  6. Surface acoustic wave devices for sensor applications

    Science.gov (United States)

    Bo, Liu; Xiao, Chen; Hualin, Cai; Mohammad, Mohammad Ali; Xiangguang, Tian; Luqi, Tao; Yi, Yang; Tianling, Ren

    2016-02-01

    Surface acoustic wave (SAW) devices have been widely used in different fields and will continue to be of great importance in the foreseeable future. These devices are compact, cost efficient, easy to fabricate, and have a high performance, among other advantages. SAW devices can work as filters, signal processing units, sensors and actuators. They can even work without batteries and operate under harsh environments. In this review, the operating principles of SAW sensors, including temperature sensors, pressure sensors, humidity sensors and biosensors, will be discussed. Several examples and related issues will be presented. Technological trends and future developments will also be discussed. Project supported by the National Natural Science Foundation of China (Nos. 60936002, 61025021, 61434001, 61574083), the State Key Development Program for Basic Research of China (No. 2015CB352100), the National Key Project of Science and Technology (No. 2011ZX02403-002) and the Special Fund for Agroscientific Research in the Public Interest of China (No. 201303107). M.A.M is additionally supported by the Postdoctoral Fellowship (PDF) program of the Natural Sciences and Engineering Research Council (NSERC) of Canada and the China Postdoctoral Science Foundation (CPSF).

  7. Upper mantle anisotropy beneath Australia and Tahiti from P wave polarization: Implications for real-time earthquake location

    OpenAIRE

    Fontaine, Fabrice R.,; Barruol, Guilhem; Kennett, Brian L. N.; Bokelmann, Goetz; Reymond, Dominique

    2009-01-01

    International audience; We report measurements of long-period P wave polarization (P pol) in Australia and Tahiti made by combining modeling of the polarization deviation and harmonic analysis. The analysis of the deviation of the horizontal polarization of the P wave as a function of event back azimuth may be used to obtain information about (1) sensor misorientation, (2) dipping discontinuities, (3) seismic anisotropy, and (4) velocity heterogeneities beneath a seismic station. The results ...

  8. Effect of polar and non-polar surfaces of ZnO nanostructures on photocatalytic properties

    International Nuclear Information System (INIS)

    Yang Jinghai; Wang Jian; Li Xiuyan; Lang Jihui; Liu Fuzhu; Yang Lili; Zhai Hongju; Gao Ming; Zhao Xiaoting

    2012-01-01

    Highlights: ► Large-scale arrayed ZnO nanocrystals including ZnO hexagonal platforms and hamburger-like samples have been successfully fabricated by a simple hydrothermal method. ► ZnO with hexagonal platform-like morphology exhibited higher photocatalytic activity compared with that of the hamburger-like ZnO nanostructures. ► The theories of expose surfaces and oxygen vacancies were utilized to explain the photocatalytic mechanism. - Abstract: Large-scale arrayed ZnO nanocrystals with two different expose surfaces, including ZnO hexagonal nanoplatforms with the major expose plane of (0 0 0 1) and hamburger-like samples with the nonpolar planes of {101 ¯ 0} mainly exposed, were successfully fabricated by a simple hydrothermal method. Mechanisms for compare the photocatalytic activity of two typical ZnO nanostructures were systematic explained as the key point in the paper. Compared with the hamburger-like ZnO nanostructures, the ZnO with hexagonal platform-like morphology exhibited improved ability on the photocatalytic degradation of Rhodamine B (RhB) in aqueous solution under UV radiation. The relative higher photocatalytic activity of the ZnO hexagonal nanoplatforms was attributed to the exposed polar surfaces and the content of oxygen vacancy on the nanostructures surface. The Zn-terminated (0 0 0 1) polar face and the surface defects are facile to adsorb O 2− and OH − ions, resulting in a greater production rate of O 2 · − and OH· − , hence promoting the photocatalysis reaction.

  9. Effect of polar and non-polar surfaces of ZnO nanostructures on photocatalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Yang Jinghai, E-mail: jhyang1@jlnu.edu.cn [Institute of Condensed State Physics, Jilin Normal University, Siping 136000 (China); Key Laboratory of Functional Materials Physics and Chemistry (Jilin Normal University), Ministry of Education, Siping 136000 (China); Wang Jian; Li Xiuyan; Lang Jihui; Liu Fuzhu; Yang Lili; Zhai Hongju; Gao Ming; Zhao Xiaoting [Institute of Condensed State Physics, Jilin Normal University, Siping 136000 (China); Key Laboratory of Functional Materials Physics and Chemistry (Jilin Normal University), Ministry of Education, Siping 136000 (China)

    2012-07-05

    Highlights: Black-Right-Pointing-Pointer Large-scale arrayed ZnO nanocrystals including ZnO hexagonal platforms and hamburger-like samples have been successfully fabricated by a simple hydrothermal method. Black-Right-Pointing-Pointer ZnO with hexagonal platform-like morphology exhibited higher photocatalytic activity compared with that of the hamburger-like ZnO nanostructures. Black-Right-Pointing-Pointer The theories of expose surfaces and oxygen vacancies were utilized to explain the photocatalytic mechanism. - Abstract: Large-scale arrayed ZnO nanocrystals with two different expose surfaces, including ZnO hexagonal nanoplatforms with the major expose plane of (0 0 0 1) and hamburger-like samples with the nonpolar planes of {l_brace}101{sup Macron }0{r_brace} mainly exposed, were successfully fabricated by a simple hydrothermal method. Mechanisms for compare the photocatalytic activity of two typical ZnO nanostructures were systematic explained as the key point in the paper. Compared with the hamburger-like ZnO nanostructures, the ZnO with hexagonal platform-like morphology exhibited improved ability on the photocatalytic degradation of Rhodamine B (RhB) in aqueous solution under UV radiation. The relative higher photocatalytic activity of the ZnO hexagonal nanoplatforms was attributed to the exposed polar surfaces and the content of oxygen vacancy on the nanostructures surface. The Zn-terminated (0 0 0 1) polar face and the surface defects are facile to adsorb O{sup 2-} and OH{sup -} ions, resulting in a greater production rate of O{sup 2}{center_dot}{sup -} and OH{center_dot}{sup -}, hence promoting the photocatalysis reaction.

  10. Parametric Excitation of Magnetopause Surface Waves: Global Magnetospheric Modeling in SWMF

    Science.gov (United States)

    Ellington, S.

    2017-12-01

    Magnetopause surface waves are an efficient energy transport modality in the coupling of the solar wind with the magnetosphere. The magnetopause supports several known waves such as the Kelvin-Helmholtz and Kruskal-Schwartzchild modes, which are excited by velocity shear and impulsive solarwind pressure pulses, respectively. Here we have discovered via simulations in SWMF a parametrically excited surface wave in which a slow magnetosonic wave excited by broadband, low amplitude fluctuations in the upstream solarwind number density couples to a circularly polarized shear Alfven wave at half the frequency. By varying the amplitude of the fluctuations and using various constitutive MHD equation sets-ideal, resistive, and anisotropic ion pressure with electron pressure, we verify that the theoretical model of parametric excitation accurately predicts the observed growth rates in each case. We briefly discuss the saturation mechanism of the shear modes as a nonlocal phenomenon mediated by ionospheric conductivity and describe several observations made downstream involving their decay, a process which subsequently couples the surface waves to kink mode waves that then propagate across the entire magnetotail. Lastly, we discuss the implications of these results in the context of observed magnetosphere phenomena and the impact of the numerical design of these simulations therein.

  11. Nonplanar electrostatic shock waves in an opposite polarity dust ...

    Indian Academy of Sciences (India)

    M Amina

    2017-05-30

    May 30, 2017 ... clouds, interstellar media, and nebula [1–3], dusty plasma has become a very interesting field of study. Sev- eral processes are responsible for charging of dust grains. [4,5]. The charge of the dust grains highly depends on the size of the dust surface; larger dust grains are found to be negatively charged ...

  12. A Multiscale Nested Modeling Framework to Simulate the Interaction of Surface Gravity Waves with Nonlinear Internal Gravity Waves

    Science.gov (United States)

    2015-09-30

    Interaction of Surface Gravity Waves with Nonlinear Internal Gravity Waves Lian Shen St. Anthony Falls Laboratory and Department of Mechanical...on studying surface gravity wave evolution and spectrum in the presence of surface currents caused by strongly nonlinear internal solitary waves...interaction of surface and internal gravity waves in the South China Sea. We will seek answers to the following questions: 1) How does the wind-wave

  13. Wave-current interaction near the Gulf Stream during the surface wave dynamics experiment

    Science.gov (United States)

    Wang, David W.; Liu, Antony K.; Peng, Chih Y.; Meindl, Eric A.

    1994-01-01

    This paper presents a case study on the wave-current interaction near the local curvature of a Gulf Stream meander. The wave data were obtained from in situ measurements by a pitch-roll discus buoy during the Surface Wave Dynamics Experiment (SWADE) conducted off Wallops Island, Virginia, from October 1990 to March 1991. Owing to the advection of the Gulf Stream by the semidiurnal tide, the discus buoy was alternately located outside and inside the Gulf Stream. The directional wave measurements from the buoy show the changes in wave direction, wave energy, and directional spreading when waves encountered the current in the Gulf Stream meanders. A wave refraction model, using the ray-tracing method with an estimated Gulf Stream velocity field and meandering condition, was used to simulate wave refraction patterns and to estimate wave parameters at relative locations corresponding to buoy measurements. The numerical simulation shows that a focusing zone of wave rays was formed near the boundary and behind the crest of a simulated Gulf Stream meander. The focusing of wave rays causes changes in wave direction, increases in wave energy, and decreases in wave directional spreading, which are in good agreement with the results from the buoy measurements.

  14. Direct detection of near-surface faults by migration of back-scattered surface waves

    KAUST Repository

    Yu, Han

    2014-08-05

    We show that diffraction stack migration can be used to estimate the distribution of near-surface faults. The assumption is that near-surface faults generate detectable back-scattered surface waves from impinging surface waves. The processing steps are to isolate the back-scattered surface waves, and then migrate them by diffraction migration using the surface wave velocity as the migration velocity. Instead of summing events along trial quasi-hyperbolas, surface wave migration sums events along trial quasi-linear trajectories that correspond to the moveout of back-scattered surface waves. A deconvolution filter derived from the data can be used to collapse a dispersive arrival into a non-dispersive event. Results with synthetic data and field records validate the feasibility of this method. Applying this method to USArray data or passively recorded exploration data might open new opportunities in mapping tectonic features over the extent of the array.

  15. Observation of nuclear spin waves in spin-polarized atomic hydrogen gas

    Energy Technology Data Exchange (ETDEWEB)

    Johson, B.R.; Denker, J.S.; Bigelow, N.; Levy, L.P.; Freed, J.H.; Lee, D.M.

    1984-04-23

    We have observed narrow, distinct resonances in the NMR spectrum of dilute spin-polarized atomic hydrogen gas (nroughly-equal10/sup 16/ atoms/cm/sup 3/). The dependence of the observed spectra on temperature, density, polarization, and magnetic field gradient is consistent with theoretical predictions for spin-wave excitations damped by diffusion. We have measured the parameter ..mu.., which is a measure of the importance of exchange effects in spin transport processes, and the diffusion coefficient D/sub 0/, both of which are in reasonable agreement with theory.

  16. Study of Magnetohydrodynamic Surface Waves on Liquid Gallium

    International Nuclear Information System (INIS)

    Hantao Ji; William Fox; David Pace; Rappaport, H.L.

    2004-01-01

    Magnetohydrodynamic (MHD) surface waves on liquid gallium are studied theoretically and experimentally in the small magnetic Reynolds number limit. A linear dispersion relation is derived when a horizontal magnetic field and a horizontal electric current is imposed. No wave damping is found in the shallow liquid limit while waves always damp in the deep liquid limit with a magnetic field parallel to the propagation direction. When the magnetic field is weak, waves are weakly damped and the real part of the dispersion is unaffected, while in the opposite limit waves are strongly damped with shortened wavelengths. In a table-top experiment, planar MHD surface waves on liquid gallium are studied in detail in the regime of weak magnetic field and deep liquid. A non-invasive diagnostic accurately measures surface waves at multiple locations by reflecting an array of lasers off the surface onto a screen, which is recorded by an Intensified-CCD camera. The measured dispersion relation is consistent with the linear theory with a reduced surface tension likely due to surface oxidation. In excellent agreement with linear theory, it is observed that surface waves are damped only when a horizontal magnetic field is imposed parallel to the propagation direction. No damping is observed under a perpendicular magnetic field. The existence of strong wave damping even without magnetic field suggests the importance of the surface oxide layer. Implications to the liquid metal wall concept in fusion reactors, especially on the wave damping and a Rayleigh-Taylor instability when the Lorentz force is used to support liquid metal layer against gravity, are discussed

  17. Pitch Angle Scattering of Upgoing Electron Beams in Jupiter's Polar Regions by Whistler Mode Waves

    Science.gov (United States)

    Elliott, S. S.; Gurnett, D. A.; Kurth, W. S.; Clark, G.; Mauk, B. H.; Bolton, S. J.; Connerney, J. E. P.; Levin, S. M.

    2018-02-01

    The Juno spacecraft's Jupiter Energetic-particle Detector Instrument has observed field-aligned, unidirectional (upgoing) electron beams throughout most of Jupiter's entire polar cap region. The Waves instrument detected intense broadband whistler mode emissions occurring in the same region. In this paper, we investigate the pitch angle scattering of the upgoing electron beams due to interactions with the whistler mode waves. Profiles of intensity versus pitch angle for electron beams ranging from 2.53 to 7.22 Jovian radii show inconsistencies with the expected adiabatic invariant motion of the electrons. It is believed that the observed whistler mode waves perturb the electron motion and scatter them away from the magnetic field line. The diffusion equation has been solved by using diffusion coefficients which depend on the magnetic intensity of the whistler mode waves.

  18. Observation of Zenneck-Like Waves over a Metasurface Designed for Launching HF Radar Surface Wave

    Directory of Open Access Journals (Sweden)

    Florent Jangal

    2016-01-01

    Full Text Available Since the beginning of the 20th century a controversy has been continuously revived about the existence of the Zenneck Wave. This wave is a theoretical solution of Maxwell’s equations and might be propagated along the interface between the air and a dielectric medium. The expected weak attenuation at large distance explains the constant interest for this wave. Notably in the High Frequency band such a wave had been thought as a key point to reduce the high attenuation observed in High Frequency Surface Wave Radar. Despite many works on that topic and various experiments attempted during one century, there is still an alternation of statements between its existence and its nonexistence. We report here an experiment done during the optimisation of the transmitting antennas for Surface Wave Radars. Using an infrared method, we visualize a wave having the structure described by Zenneck above a metasurface located on a dielectric slab.

  19. Highly Efficient Wave-Front Reshaping of Surface Waves with Dielectric Metawalls

    Science.gov (United States)

    Dong, Shaohua; Zhang, Yu; Guo, Huijie; Duan, Jingwen; Guan, Fuxin; He, Qiong; Zhao, Haibin; Zhou, Lei; Sun, Shulin

    2018-01-01

    Controlling the wave fronts of surface waves (including surface-plamon polaritons and their equivalent counterparts) at will is highly important in photonics research, but the available mechanisms suffer from the issues of low efficiency, bulky size, and/or limited functionalities. Inspired by recent studies of metasurfaces that can freely control the wave fronts of propagating waves, we propose to use metawalls placed on a plasmonic surface to efficiently reshape the wave fronts of incident surface waves (SWs). Here, the metawall is constructed by specifically designed meta-atoms that can reflect SWs with desired phases and nearly unit amplitudes. As a proof of concept, we design and fabricate a metawall in the microwave regime (around 12 GHz) that can anomalously reflect the SWs following the generalized Snell's law with high efficiency (approximately 70%). Our results, in excellent agreement with full-wave simulations, provide an alternative yet efficient way to control the wave fronts of SWs in different frequency domains. We finally employ full-wave simulations to demonstrate a surface-plasmon-polariton focusing effect at telecom wavelength based on our scheme.

  20. Inversion of Surface Wave Phase Velocities for Radial Anisotropy to an Depth of 1200 km

    Science.gov (United States)

    Xing, Z.; Beghein, C.; Yuan, K.

    2012-12-01

    This study aims to evaluate three dimensional radial anisotropy to an depth of 1200 km. Radial anisotropy describes the difference in velocity between horizontally polarized Rayleigh waves and vertically polarized Love waves. Its presence in the uppermost 200 km mantle has well been documented by different groups, and has been regarded as an indicator of mantle convection which aligns the intrinsically anisotropic minerals, largely olivine, to form large scale anisotropy. However, there is no global agreement on whether anisotropy exists in the region below 200 km. Recent models also associate a fast vertically polarized shear wave with vertical upwelling mantle flow. The data used in this study is the globally isotropic phase velocity models of fundamental and higher mode Love and Rayleigh waves (Visser, 2008). The inclusion of higher mode surface wave phase velocity provides sensitivities to structure at depth that extends to below the transition zone. While the data is the same as used by Visser (2008), a quite different parameterization is applied. All the six parameters - five elastic parameters A, C, F, L, N and density - are now regarded as independent, which rules out possible biased conclusions induced by scaling relation method used in several previous studies to reduce the number of parameters partly due to limited computing resources. The data need to be modified by crustal corrections (Crust2.0) as we want to look at the mantle structure only. We do this by eliminating the perturbation in surface wave phase velocity caused by the difference in crustal structure with respect to the referent model PREM. Sambridge's Neighborhood Algorithm is used to search the parameter space. The introduction of such a direct search technique pales the traditional inversion method, which requires regularization or some unnecessary priori restriction on the model space. On the contrary, the new method will search the full model space, providing probability density

  1. Unpinning of rotating spiral waves in cardiac tissues by circularly polarized electric fields

    Science.gov (United States)

    Feng, Xia; Gao, Xiang; Pan, De-Bei; Li, Bing-Wei; Zhang, Hong

    2014-04-01

    Spiral waves anchored to obstacles in cardiac tissues may cause lethal arrhythmia. To unpin these anchored spirals, comparing to high-voltage side-effect traditional therapies, wave emission from heterogeneities (WEH) induced by the uniform electric field (UEF) has provided a low-voltage alternative. Here we provide a new approach using WEH induced by the circularly polarized electric field (CPEF), which has higher success rate and larger application scope than UEF, even with a lower voltage. And we also study the distribution of the membrane potential near an obstacle induced by CPEF to analyze its mechanism of unpinning. We hope this promising approach may provide a better alternative to terminate arrhythmia.

  2. Anomalous Tunneling of Spin Wave in Polar State of Spin-1 BEC

    International Nuclear Information System (INIS)

    Watabe, Shohei; Ohashi, Yoji; Kato, Yusuke

    2012-01-01

    We investigate tunneling properties of collective spin-wave excitations in the polar state of a spin-1 spinor Bose-Einstein condensate. Within the mean-field theory at T = 0, we show that when the condensate is in the critical supercurrent state, the spin wave mode exhibits perfect transmission through a nonmagnetic potential barrier in the low energy limit, unless the strength of a spin-independent interaction c o equals that of a spin-dependent interaction c o Such an anomalous tunneling behavior is absent in the case of a magnetic barrier. We also clarify a scaling law of the transmission probability as a function of the mode energy.

  3. Anomalous Tunneling of Spin Wave in Polar State of Spin-1 BEC

    Science.gov (United States)

    Watabe, Shohei; Kato, Yusuke; Ohashi, Yoji

    2012-12-01

    We investigate tunneling properties of collective spin-wave excitations in the polar state of a spin-1 spinor Bose-Einstein condensate. Within the mean-field theory at T = 0, we show that when the condensate is in the critical supercurrent state, the spin wave mode exhibits perfect transmission through a nonmagnetic potential barrier in the low energy limit, unless the strength of a spin-independent interaction co equals that of a spin-dependent interaction co Such an anomalous tunneling behavior is absent in the case of a magnetic barrier. We also clarify a scaling law of the transmission probability as a function of the mode energy.

  4. All-dielectric metasurface realizing giant asymmetric transmission for linearly polarized wave

    Science.gov (United States)

    Pan, Weikang; Kang, Yuanyuan; Wang, Chuan; Tang, Dengfei; Dong, Jianfeng

    2018-01-01

    In this paper, a kind of chiral all-dielectric metasurface is demonstrated numerically to achieve giant asymmetric transmission (AT) in fiber communication region. The incoming polarized electromagnetic wave excites magnetic and electric resonances and the resonances in AT spectrum coincide with eigen frequencies of this structure. The all dielectric metasurface shows more excellent properties compared with its metal counterpart. AT is influenced significantly by material permittivity as well as unit cell period. The concept of all-dielectric metasurface offers a new way to manipulate electromagnetic waves and the phenomenon remains effective in other frequencies.

  5. Generation of neutron standing waves at total reflection of polarized neutrons

    International Nuclear Information System (INIS)

    Aksenov, V.L.; Nikitenko, Yu.V.; Kozhevnikov, S.V.; Radu, F.; Kruijs, R.; Rekveldt, M.Th.

    1999-01-01

    The regime of neutron standing waves at reflection of polarized thermal neutrons from the structure glass/Cu (1000 A Angstrom)/Ti (2000 A Angstrom)/Co (60 A Angstrom)/Ti (300 A Angstrom) in a magnetic field directed at an angle to the sample plane is realized. The intensity of neutrons with a particular spin projection on the external magnetic field direction appears to be a periodic function of the neutron wavelength and the glancing angle of the reflected beam. It is shown that the neutron standing wave regime can be a very sensitive method for the determination of changes in the spatial position of magnetic noncollinear layers. (author)

  6. Enhanced Sensitive Love Wave Surface Acoustic Wave Sensor Designed for Immunoassay Formats

    OpenAIRE

    Puiu, Mihaela; Gurban, Ana-Maria; Rotariu, Lucian; Brajnicov, Simona; Viespe, Cristian; Bala, Camelia

    2015-01-01

    We report a Love wave surface acoustic wave (LW-SAW) immunosensor designed for the detection of high molecular weight targets in liquid samples, amenable also for low molecular targets in surface competition assays. We implemented a label-free interaction protocol similar to other surface plasmon resonance bioassays having the advantage of requiring reduced time analysis. The fabricated LW-SAW sensor supports the detection of the target in the nanomolar range, and can be ultimately incorporat...

  7. Ultra-High-Speed Travelling Wave Protection of Transmission Line Using Polarity Comparison Principle Based on Empirical Mode Decomposition

    Directory of Open Access Journals (Sweden)

    Dong Wang

    2015-01-01

    Full Text Available The traditional polarity comparison based travelling wave protection, using the initial wave information, is affected by initial fault angle, bus structure, and external fault. And the relationship between the magnitude and polarity of travelling wave is ignored. Because of the protection tripping and malfunction, the further application of this protection principle is affected. Therefore, this paper presents an ultra-high-speed travelling wave protection using integral based polarity comparison principle. After empirical mode decomposition of the original travelling wave, the first-order intrinsic mode function is used as protection object. Based on the relationship between the magnitude and polarity of travelling wave, this paper demonstrates the feasibility of using travelling wave magnitude which contains polar information as direction criterion. And the paper integrates the direction criterion in a period after fault to avoid wave head detection failure. Through PSCAD simulation with the typical 500 kV transmission system, the reliability and sensitivity of travelling wave protection were verified under different factors’ affection.

  8. Ray-map migration of transmitted surface waves

    KAUST Repository

    Li, Jing

    2016-08-25

    Near-surface normal faults can sometimes separate two distinct zones of velocity heterogeneity, where the medium on one side of the fault has a faster velocity than on the other side. Therefore, the slope of surface-wave arrivals in a common-shot gather should abruptly change near the surface projection of the fault. We present ray-map imaging method that migrates transmitted surface waves to the fault plane, and therefore it roughly estimates the orientation, depth, and location of the near-surface fault. The main benefits of this method are that it is computationally inexpensive and robust in the presence of noise.

  9. Organic polar pollutants in surface waters of inland seas.

    Science.gov (United States)

    Orlikowska, Anna; Fisch, Kathrin; Schulz-Bull, Detlef E

    2015-12-30

    Available data about contamination by polar substances are mostly reported for rivers and near-shore waters and only limited studies exists about their occurrence in marine waters. We present concentrations and distribution of several polar pesticides and UV-filters in surface waters of three inland seas, the Baltic, Black and Mediterranean Sea. Many of the investigated compounds were below detection limits, however, those found in off-shore waters raise a concern about their persistence and possible adverse effect on the ecosystem. Despite a longstanding EU-wide ban we were able to detect atrazine in the Mediterranean and the Baltic Sea. Concentrations in the Black Sea were substantially higher. Runoff from agricultural and urban areas was the main transport route to marine ecosystems for investigated compounds, though irgarol in Mediterranean waters was attributed to intense maritime traffic. 2-Phenylbenzimidazole-5-sulfonic acid was the only UV-filter detected in marine waters, while benzophenone-4 was observed in the estuaries. Occurrence of UV-filters was seasonal. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Polarization dependence of the spin-density-wave excitations in single-domain chromium

    Energy Technology Data Exchange (ETDEWEB)

    Boeni, P. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Roessli, B. [Institut Max von Laue - Paul Langevin, 75 - Paris (France); Sternlieb, B.J. [Brookhaven (United States); Lorenzo, E. [Centre National de la Recherche Scientifique (CNRS), 38 - Grenoble (France); Werner, S.A. [Missouri (United States)

    1997-09-01

    A polarized neutron scattering experiment has been performed with a single-Q, single domain sample of chromium in a magnetic field of 4 T. It is confirmed that the longitudinal fluctuations are enhanced for small energy transfers and that the spin wave modes with {delta}S parallel to Q and {delta}S perpendicular to Q are similar. (author) 2 figs., 1 tab., 2 refs.

  11. Wave normal angles of magnetospheric chorus emissions observed on the Polar spacecraft

    Czech Academy of Sciences Publication Activity Database

    Haque, N.; Spasojevic, M.; Santolík, Ondřej; Inan, U. S.

    2010-01-01

    Roč. 115, - (2010), A00F07/1-A00F07/12 ISSN 0148-0227 R&D Projects: GA AV ČR IAA301120601 Grant - others:GA MŠk(CZ) ME 842 Institutional research plan: CEZ:AV0Z30420517 Keywords : chorus * wave normal * Polar spacecraft Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 3.303, year: 2010

  12. Numerical simulation of floating bodies in extreme free surface waves

    Directory of Open Access Journals (Sweden)

    Z. Z. Hu

    2011-02-01

    Full Text Available In this paper, we use the in-house Computational Fluid Dynamics (CFD flow code AMAZON-SC as a numerical wave tank (NWT to study wave loading on a wave energy converter (WEC device in heave motion. This is a surface-capturing method for two fluid flows that treats the free surface as contact surface in the density field that is captured automatically without special provision. A time-accurate artificial compressibility method and high resolution Godunov-type scheme are employed in both fluid regions (air/water. The Cartesian cut cell method can provide a boundary-fitted mesh for a complex geometry with no requirement to re-mesh globally or even locally for moving geometry, requiring only changes to cut cell data at the body contour. Extreme wave boundary conditions are prescribed in an empty NWT and compared with physical experiments prior to calculations of extreme waves acting on a floating Bobber-type device. The validation work also includes the wave force on a fixed cylinder compared with theoretical and experimental data under regular waves. Results include free surface elevations, vertical displacement of the float, induced vertical velocity and heave force for a typical Bobber geometry with a hemispherical base under extreme wave conditions.

  13. Effect of irregularity on torsional surface waves in an initially ...

    Indian Academy of Sciences (India)

    Effect of irregularity on torsional surface waves in an initially stressed anisotropic porous layer sandwiched between homogeneous and non-homogeneous half- ... Torsional wave; anisotropy; initial stress; irregularity; non-homogeneity ... Department of Applied Mathematics, Indian School of Mines, Dhanbad 826 004, India.

  14. Interpretation of nonlinearity in wind generated ocean surface waves

    Digital Repository Service at National Institute of Oceanography (India)

    Varkey, M.J.

    This study attempts to resolve a mix-up between a physical process and its mathematical interpretation in the context of wind waves on ocean surface. Wind generated wave systems, are conventionally interpreted as a result of interaction of a number...

  15. Surface waves in fibre-reinforced anisotropic elastic media

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    MS received 1 March 2002. Abstract. In the paper under discussion, the problem of surface waves in fibre- reinforced anisotropic elastic media has been studied. The authors express the plane strain displacement components in terms of two scalar potentials to decouple the plane motion into P and SV waves. In the present ...

  16. Discrete extrinsic curvatures and approximation of surfaces by polar polyhedra

    Science.gov (United States)

    Garanzha, V. A.

    2010-01-01

    Duality principle for approximation of geometrical objects (also known as Eu-doxus exhaustion method) was extended and perfected by Archimedes in his famous tractate “Measurement of circle”. The main idea of the approximation method by Archimedes is to construct a sequence of pairs of inscribed and circumscribed polygons (polyhedra) which approximate curvilinear convex body. This sequence allows to approximate length of curve, as well as area and volume of the bodies and to obtain error estimates for approximation. In this work it is shown that a sequence of pairs of locally polar polyhedra allows to construct piecewise-affine approximation to spherical Gauss map, to construct convergent point-wise approximations to mean and Gauss curvature, as well as to obtain natural discretizations of bending energies. The Suggested approach can be applied to nonconvex surfaces and in the case of multiple dimensions.

  17. Finite element simulations of surface effect on Rayleigh waves

    Science.gov (United States)

    He, Jin; Zhao, Jinling

    2018-03-01

    Rayleigh waves influenced by surface effect are investigated by using finite element methods, in which eigenfrequency analysis are performed on a model composed of a half-space covered by the surface effect dominated domain. For a given wavelength, the frequency of the Rayleigh wave is obtained as the eigenfrequency of the model satisfying Floquet periodic boundary conditions. The thickness of the surface effect can be set to be infinitely small or a finite value in the finite element methods. The curvature-dependent out-of-plane force induced by surface tension as described by the generalized Young-Laplace equation is realized through geometric nonlinear analysis. The finite element simulations show that the assumptions of small curvature and infinitely small thickness of the surface effect widely used in theoretical approaches become invalid when Rayleigh waves are highly influenced by the surface effect. This work gives a more accurate insight into the surface effect on Rayleigh waves and provides a potential method for measuring the thickness of the surface effect from the dispersion curves of surface effect influenced Rayleigh wave velocities.

  18. Surface Wave Focusing and Acoustic Communications in the Surf Zone

    National Research Council Canada - National Science Library

    Preisig, James

    2004-01-01

    The forward scattering of acoustic signals off of shoaling surface gravity waves in the surf zone results in a time-varying channel impulse response that is characterized by intense, rapidly fluctuating arrivals...

  19. Response of surface buoy moorings in steady and wave flows

    Digital Repository Service at National Institute of Oceanography (India)

    Anand, N.M.; Nayak, B.U.; SanilKumar, V.

    A numerical model has been developed to evaluate the dynamics of surface buoy mooring systems under wave and current loading. System tension response and variation of tension in the mooring line at various depths have been evaluated for deep water...

  20. CAMEX-3 JPL SURFACE ACOUSTIC WAVE (SAW) HYGROMETER V1

    Data.gov (United States)

    National Aeronautics and Space Administration — This CAMEX-3 Jet Propulsion Laboratory (JPL) Surface Acoustic Wave (SAW) Hygrometer dataset consists of dewpoint timeline measurements acquired during each DC-8...

  1. Estimating propagation velocity through a surface acoustic wave sensor

    Science.gov (United States)

    Xu, Wenyuan; Huizinga, John S.

    2010-03-16

    Techniques are described for estimating the propagation velocity through a surface acoustic wave sensor. In particular, techniques which measure and exploit a proper segment of phase frequency response of the surface acoustic wave sensor are described for use as a basis of bacterial detection by the sensor. As described, use of velocity estimation based on a proper segment of phase frequency response has advantages over conventional techniques that use phase shift as the basis for detection.

  2. Lage-area planar RF plasma productions by surface waves

    International Nuclear Information System (INIS)

    Nonaka, S.

    1994-01-01

    Large-area rf plasmas are confirmed to be produced by means of RF discharges inside a large-area dielectric tube. The plasma space is 73 cm x 176 cm and 2.5 cm. The plasma is thought to be produced by an odd plasma-surface wave (PSW ο ) in case of using large-area electrodes and by an even plasma-surface wave (PSW ο ) in case of without the electrodes. (author). 7 refs, 4 figs

  3. Modulation of cavity-polaritons by surface acoustic waves

    DEFF Research Database (Denmark)

    de Lima, M. M.; Poel, Mike van der; Hey, R.

    2006-01-01

    We modulate cavity-polaritons using surface acoustic waves. The corresponding formation of a mini-Brillouin zone and band folding of the polariton dispersion is demonstrated for the first time. Results are in good agreement with model calculations.......We modulate cavity-polaritons using surface acoustic waves. The corresponding formation of a mini-Brillouin zone and band folding of the polariton dispersion is demonstrated for the first time. Results are in good agreement with model calculations....

  4. Oscillon dynamics and rogue wave generation in Faraday surface ripples.

    Science.gov (United States)

    Xia, H; Maimbourg, T; Punzmann, H; Shats, M

    2012-09-14

    We report new experimental results which suggest that the generation of extreme wave events in the Faraday surface ripples is related to the increase in the horizontal mobility of oscillating solitons (oscillons). The analysis of the oscillon trajectories in a horizontal plane shows that at higher vertical acceleration, oscillons move chaotically, merge and form enclosed areas on the water surface. The probability of the formation of such craters, which precede large wave events, increases with the increase in horizontal mobility.

  5. The Surface Wave Scattering-Microwave Scanner (SWS-MS)

    Science.gov (United States)

    Geffrin, Jean-Michel; Chamtouri, Maha; Merchiers, Olivier; Tortel, Hervé; Litman, Amélie; Bailly, Jean-Sébastien; Lacroix, Bernard; Francoeur, Mathieu; Vaillon, Rodolphe

    2016-01-01

    The Surface Wave Scattering-Microwave Scanner (SWS-MS) is a device that allows the measurement of the electromagnetic fields scattered by objects totally or partially submerged in surface waves. No probe is used to illuminate the sample, nor to guide or scatter the local evanescent waves. Surface waves are generated by total internal reflection and the amplitude and phase of the fields scattered by the samples are measured directly, both in the far-field and the near-field regions. The device's principles and their practical implementation are described in details. The surface wave generator is assessed by measuring the spatial distribution of the electric field above the surface. Drift correction and the calibration method for far-field measurements are explained. Comparison of both far-field and near-field measurements against simulation data shows that the device provides accurate results. This work suggests that the SWS-MS can be used for producing experimental reference data, for supporting a better understanding of surface wave scattering, for assisting in the design of near-field optical or infrared systems thanks to the scale invariance rule in electrodynamics, and for performing nondestructive control of defects in materials.

  6. Rayleigh waves, surface disorder, and phonon localization in nanostructures

    Science.gov (United States)

    Maurer, L. N.; Mei, S.; Knezevic, I.

    2016-07-01

    We introduce a technique to calculate thermal conductivity in disordered nanostructures: a finite-difference time-domain solution of the elastic-wave equation combined with the Green-Kubo formula. The technique captures phonon wave behavior and scales well to nanostructures that are too large or too surface disordered to simulate with many other techniques. We investigate the role of Rayleigh waves and surface disorder on thermal transport by studying graphenelike nanoribbons with free edges (allowing Rayleigh waves) and fixed edges (prohibiting Rayleigh waves). We find that free edges result in a significantly lower thermal conductivity than fixed ones. Free edges both introduce Rayleigh waves and cause all low-frequency modes (bulk and surface) to become more localized. Increasing surface disorder on free edges draws energy away from the center of the ribbon and toward the disordered edges, where it gets trapped in localized surface modes. These effects are not seen in ribbons with fixed boundary conditions and illustrate the importance of phonon-surface modes in nanostructures.

  7. Chirality Driven by Magnetic Dipole Response for Demultiplexing of Surface Waves

    DEFF Research Database (Denmark)

    Sinev, Ivan S.; Bogdanov, Andrey A.; Komissarenko, Filipp E.

    2017-01-01

    Surface electromagnetic waves are characterized by the intrinsic spin-orbit interaction which results in the fascinating spin-momentum locking. Therefore, directional coupling of light to surface waves can be achieved through chiral nanoantennas. Here, we show that dielectric nanoantenna provides...... chiral response with strong spectral dependence due to the interference of electric and magnetic dipole momenta when placed in the vicinity of the metal-air interface. Remarkably, chiral behaviour in the proposed scheme does not require elliptical polarization of the pump beam or the geometric chirality...... of the nanoantenna. We show that the proposed ultracompact and simple dielectric nanoantenna allows for both directional launching of surface plasmon polaritons on a thin gold film and their demultiplexing with a high spectral resolution....

  8. Wave influence on polar mesosphere summer echoes above Wasa: experimental and model studies

    Directory of Open Access Journals (Sweden)

    P. Dalin

    2012-08-01

    Full Text Available Comprehensive analysis of the wave activity in the Antarctic summer mesopause is performed using polar mesospheric summer echoes (PMSE measurements for December 2010–January 2011. The 2-day planetary wave is a statistically significant periodic oscillation in the power spectrum density of PMSE power. The strongest periodic oscillation in the power spectrum belongs to the diurnal solar tide; the semi-diurnal solar tide is found to be a highly significant harmonic oscillation as well. The inertial-gravity waves are extensively studied by means of PMSE power and wind components. The strongest gravity waves are observed at periods of about 1, 1.4, 2.5 and 4 h, with characteristic horizontal wavelengths of 28, 36, 157 and 252 km, respectively. The gravity waves propagate approximately in the west-east direction over Wasa (Antarctica. A detailed comparison between theoretical and experimental volume reflectivity of PMSE, measured at Wasa, is made. It is demonstrated that a new expression for PMSE reflectivity derived by Varney et al. (2011 is able to adequately describe PMSE profiles both in the magnitude and in height variations. The best agreement, within 30%, is achieved when mean values of neutral atmospheric parameters are utilized. The largest contribution to the formation and variability of the PMSE layer is explained by the ice number density and its height gradient, followed by wave-induced perturbations in buoyancy period and the turbulent energy dissipation rate.

  9. Wave influence on polar mesosphere summer echoes above Wasa: experimental and model studies

    Science.gov (United States)

    Dalin, P.; Kirkwood, S.; Hervig, M.; Mihalikova, M.; Mikhaylova, D.; Wolf, I.; Osepian, A.

    2012-08-01

    Comprehensive analysis of the wave activity in the Antarctic summer mesopause is performed using polar mesospheric summer echoes (PMSE) measurements for December 2010-January 2011. The 2-day planetary wave is a statistically significant periodic oscillation in the power spectrum density of PMSE power. The strongest periodic oscillation in the power spectrum belongs to the diurnal solar tide; the semi-diurnal solar tide is found to be a highly significant harmonic oscillation as well. The inertial-gravity waves are extensively studied by means of PMSE power and wind components. The strongest gravity waves are observed at periods of about 1, 1.4, 2.5 and 4 h, with characteristic horizontal wavelengths of 28, 36, 157 and 252 km, respectively. The gravity waves propagate approximately in the west-east direction over Wasa (Antarctica). A detailed comparison between theoretical and experimental volume reflectivity of PMSE, measured at Wasa, is made. It is demonstrated that a new expression for PMSE reflectivity derived by Varney et al. (2011) is able to adequately describe PMSE profiles both in the magnitude and in height variations. The best agreement, within 30%, is achieved when mean values of neutral atmospheric parameters are utilized. The largest contribution to the formation and variability of the PMSE layer is explained by the ice number density and its height gradient, followed by wave-induced perturbations in buoyancy period and the turbulent energy dissipation rate.

  10. Nucleation of reaction-diffusion waves on curved surfaces

    International Nuclear Information System (INIS)

    Kneer, Frederike; Schöll, Eckehard; Dahlem, Markus A

    2014-01-01

    We study reaction-diffusion waves on curved two-dimensional surfaces, and determine the influence of curvature upon the nucleation and propagation of spatially localized waves in an excitable medium modelled by the generic FitzHugh–Nagumo model. We show that the stability of propagating wave segments depends crucially on the curvature of the surface. As they propagate, they may shrink to the uniform steady state, or expand, depending on whether they are smaller or larger, respectively, than a critical nucleus. This critical nucleus for wave propagation is modified by the curvature acting like an effective space-dependent local spatial coupling, similar to diffuson, thus extending the regime of propagating excitation waves beyond the excitation threshold of flat surfaces. In particular, a negative gradient of Gaussian curvature Γ, as on the outside of a torus surface (positive Γ), when the wave segment symmetrically extends into the inside (negative Γ), allows for stable propagation of localized wave segments remaining unchanged in size and shape, or oscillating periodically in size. (paper)

  11. Spin-polarized quasi-one-dimensional state with finite band gap on the Bi/InSb(001) surface

    Science.gov (United States)

    Kishi, J.; Ohtsubo, Y.; Nakamura, T.; Yaji, K.; Harasawa, A.; Komori, F.; Shin, S.; Rault, J. E.; Le Fèvre, P.; Bertran, F.; Taleb-Ibrahimi, A.; Nurmamat, M.; Yamane, H.; Ideta, S.; Tanaka, K.; Kimura, S.

    2017-11-01

    One-dimensional (1D) electronic states were discovered on the 1D surface atomic structure of Bi fabricated on semiconductor InSb(001) substrates by angle-resolved photoelectron spectroscopy (ARPES). The 1D state showed steep, Dirac-cone-like dispersion along the 1D atomic structure with a finite direct band gap opening as large as 150 meV. Moreover, spin-resolved ARPES revealed the spin polarization of the 1D unoccupied states as well as that of the occupied states, the orientation of which inverted depending on the wave-vector direction parallel to the 1D array on the surface. These results reveal that a spin-polarized quasi-1D carrier was realized on the surface of 1D Bi with highly efficient backscattering suppression, showing promise for use in future spintronics and energy-saving devices.

  12. Body surface mapping during pacing at multiple sites in the human atrium: P-wave morphology of ectopic right atrial activation

    NARCIS (Netherlands)

    SippensGroenewegen, A.; Peeters, H. A.; Jessurun, E. R.; Linnenbank, A. C.; Robles de Medina, E. O.; Lesh, M. D.; van Hemel, N. M.

    1998-01-01

    The morphology and polarity of the P wave on 12-lead ECG are of limited clinical value in localizing ectopic atrial rhythms. It was the aim of this study to assess the spatial resolution of body surface P-wave integral mapping in identifying the site of origin of ectopic right atrial (RA) impulse

  13. Surface-wave potential for triggering tectonic (nonvolcanic) tremor

    Science.gov (United States)

    Hill, D.P.

    2010-01-01

    Source processes commonly posed to explain instances of remote dynamic triggering of tectonic (nonvolcanic) tremor by surface waves include frictional failure and various modes of fluid activation. The relative potential for Love- and Rayleigh-wave dynamic stresses to trigger tectonic tremor through failure on critically stressed thrust and vertical strike-slip faults under the Coulomb-Griffith failure criteria as a function of incidence angle is anticorrelated over the 15- to 30-km-depth range that hosts tectonic tremor. Love-wave potential is high for strike-parallel incidence on low-angle reverse faults and null for strike-normal incidence; the opposite holds for Rayleigh waves. Love-wave potential is high for both strike-parallel and strike-normal incidence on vertical, strike-slip faults and minimal for ~45?? incidence angles. The opposite holds for Rayleigh waves. This pattern is consistent with documented instances of tremor triggered by Love waves incident on the Cascadia mega-thrust and the San Andreas fault (SAF) in central California resulting from shear failure on weak faults (apparent friction, ????? 0.2). However, documented instances of tremor triggered by surface waves with strike-parallel incidence along the Nankai megathrust beneath Shikoku, Japan, is associated primarily with Rayleigh waves. This is consistent with the tremor bursts resulting from mixed-mode failure (crack opening and shear failure) facilitated by near-lithostatic ambient pore pressure, low differential stress, with a moderate friction coefficient (?? ~ 0.6) on the Nankai subduction interface. Rayleigh-wave dilatational stress is relatively weak at tectonic tremor source depths and seems unlikely to contribute significantly to the triggering process, except perhaps for an indirect role on the SAF in sustaining tremor into the Rayleigh-wave coda that was initially triggered by Love waves.

  14. Improved ion acceleration via laser surface plasma waves excitation

    Energy Technology Data Exchange (ETDEWEB)

    Bigongiari, A. [CEA/DSM/LSI, CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex (France); TIPS/LULI, Université Paris 6, CNRS, CEA, Ecole Polytechnique, 3, rue Galilée, 94200 Ivry-sur-Seine (France); Raynaud, M. [CEA/DSM/LSI, CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex (France); Riconda, C. [TIPS/LULI, Université Paris 6, CNRS, CEA, Ecole Polytechnique, 3, rue Galilée, 94200 Ivry-sur-Seine (France); Héron, A. [CPHT, CNRS, Ecole Polytechnique, 91128 Palaiseau Cedex (France)

    2013-05-15

    The possibility of enhancing the emission of the ions accelerated in the interaction of a high intensity ultra-short (<100 fs) laser pulse with a thin target (<10λ{sub 0}), via surface plasma wave excitation is investigated. Two-dimensional particle-in-cell simulations are performed for laser intensities ranging from 10{sup 19} to 10{sup 20} Wcm{sup −2}μm{sup 2}. The surface wave is resonantly excited by the laser via the coupling with a modulation at the target surface. In the cases where the surface wave is excited, we find an enhancement of the maximum ion energy of a factor ∼2 compared to the cases where the target surface is flat.

  15. Scattering of surface waves modelled by the integral equation method

    Science.gov (United States)

    Lu, Laiyu; Maupin, Valerie; Zeng, Rongsheng; Ding, Zhifeng

    2008-09-01

    The integral equation method is used to model the propagation of surface waves in 3-D structures. The wavefield is represented by the Fredholm integral equation, and the scattered surface waves are calculated by solving the integral equation numerically. The integration of the Green's function elements is given analytically by treating the singularity of the Hankel function at R = 0, based on the proper expression of the Green's function and the addition theorem of the Hankel function. No far-field and Born approximation is made. We investigate the scattering of surface waves propagating in layered reference models imbedding a heterogeneity with different density, as well as Lamé constant contrasts, both in frequency and time domains, for incident plane waves and point sources.

  16. Unidirectional transmission based on polarization conversion and excitation of magnetic or surface polaritons

    Directory of Open Access Journals (Sweden)

    Xiaohu Wu

    2017-07-01

    Full Text Available We propose in this work combing a uniaxial crystal slab with a one-dimensional grating to realize unidirectional transmission (UDT. The physical mechanism for the UDT is attributed to polarization conversion with uniaxial crystal slab and excitation of magnetic polaritons (MPs or surface plasmon polaritons (SPPs in the grating region. Numerical simulations were performed by taking hexagonal boron nitride as the uniaxial crystal. The results reveal that UDT can be achieved for both TE and TM waves in the mid-infrared and the optical regions if the grating material is respectively selected as silicon carbide (SiC and silver (Ag with properly chosen values of the structure’s geometric parameters. This work may provide important guidelines for design of novel unidirectional transmission devices.

  17. Barotropic and baroclinic energy conversions associated with planetary wave forcing of the northern stratospheric polar vortex

    Science.gov (United States)

    Liberato, M. L. R.; Castanheira, J. M.; Dacamara, C. C.

    2009-04-01

    An analysis of the energy conversion of barotropic and baroclinic planetary waves for extended winter in the extratropical Northern Hemisphere is presented. The analysis is based on a three-dimensional normal mode expansion of the global circulation of the atmosphere (Castanheira et al. 2002; Liberato et al. 2007). This method allows separating the atmospheric circulation into planetary (Rossby) and inertio-gravity waves as well as characterising each type of wave by the respective zonal, meridional and vertical structures. The 3-D normal mode scheme further allows evaluating the contribution of each type of wave for the global total (i.e., kinetic + available potential) atmospheric energy. A brief overview of the normal mode energetics of the global atmospheric circulation is given, focusing on the energy conversions between barotropic and baroclinic components of different vertical and horizontal scales. The methodology is applied to the global NCEP/NCAR (National Centers for Environmental Prediction / National Center for Atmospheric Research) reanalysis data set, using extended winter (November to March) daily means of the horizontal wind components (u, v) and of the geopotential height, at the 17 standard pressure levels, with the spatial horizontal resolution available (2.5° regular grid) and spanning the period 1957-2008. Obtained results are then used to relate the variability of the stratospheric polar vortex to the variability of the energy of the forcing planetary waves. Barotropic and baroclinic energy conversions associated with planetary wave forcing of the northern winter polar vortex are finally analysed, during rapid stratospheric vortex decelerations and accelerations. Castanheira, J. M., H.-F. Graf, C. DaCamara, and A. Rocha, 2002: Using a physical reference frame to study global circulation variability. J. Atmos. Sci., 59, 1490-1501. Liberato, M. L. R., J. M. Castanheira, L. da la Torre, C. C. DaCamara and L. Gimeno, 2007: Wave Energy Associated

  18. Experimental Investigations on Microshock Waves and Contact Surfaces

    Science.gov (United States)

    Kai, Yun; Garen, Walter; Teubner, Ulrich

    2018-02-01

    The present work reports on progress in the research of a microshock wave. Because of the lack of a good understanding of the propagation mechanism of the microshock flow system (shock wave, contact surface, and boundary layer), the current work concentrates on measuring microshock flows with special attention paid to the contact surface. A novel setup involving a glass capillary (with a 200 or 300 μ m hydraulic diameter D ) and a high-speed magnetic valve is applied to generate a shock wave with a maximum initial Mach number of 1.3. The current work applies a laser differential interferometer to perform noncontact measurements of the microshock flow's trajectory, velocity, and density. The current work presents microscale measurements of the shock-contact distance L that solves the problem of calculating the scaling factor Sc =Re ×D /(4 L ) (introduced by Brouillette), which is a parameter characterizing the scaling effects of shock waves. The results show that in contrast to macroscopic shock waves, shock waves at the microscale have a different propagation or attenuation mechanism (key issue of this Letter) which cannot be described by the conventional "leaky piston" model. The main attenuation mechanism of microshock flow may be the ever slower moving contact surface, which drives the shock wave. Different from other measurements using pressure transducers, the current setup for density measurements resolves the whole microshock flow system.

  19. Temperature Compensation of Surface Acoustic Waves on Berlinite

    Science.gov (United States)

    Searle, David Michael Marshall

    The surface acoustic wave properties of Berlinite (a-AlPO4) have been investigated theoretically and experimentally, for a variety of crystallographic orientations, to evaluate its possible use as a substrate material for temperature compensated surface acoustic wave devices. A computer program has been developed to calculate the surface wave properties of a material from its elastic, piezoelectric, dielectric and lattice constants and their temperature derivatives. The program calculates the temperature coefficient of delay, the velocity of the surface wave, the direction of power flow and a measure of the electro-mechanical coupling. These calculations have been performed for a large number of orientations using a modified form of the data given by Chang and Barsch for Berlinite and predict several new temperature compensated directions. Experimental measurements have been made of the frequency-temperature response of a surface acoustic wave oscillator on an 80° X axis boule cut which show it to be temperature compensated in qualitative agreement with the theoretical predictions. This orientation shows a cubic frequency-temperature dependence instead of the expected parabolic response. Measurements of the electro-mechanical coupling coefficient k gave a value lower than predicted. Similar measurements on a Y cut plate gave a value which is approximately twice that of ST cut quartz, but again lower than predicted. The surface wave velocity on both these cuts was measured to be slightly higher than predicted by the computer program. Experimental measurements of the lattice parameters a and c are also presented for a range of temperatures from 25°C to just above the alpha-beta transition at 584°C. These results are compared with the values obtained by Chang and Barsch. The results of this work indicate that Berlinite should become a useful substrate material for the construction of temperature compensated surface acoustic wave devices.

  20. Wave influence on polar mesosphere summer echoes above Wasa. Experimental and model studies

    Energy Technology Data Exchange (ETDEWEB)

    Dalin, P.; Kirkwood, S.; Mihalikova, M.; Mikhaylova, D.; Wolf, I. [Swedish Institute of Space Physics, Kiruna (Sweden); Hervig, M. [GATS Inc., Driggs, ID (United States); Osepian, A. [Polar Geophysical Institute, Murmansk (Russian Federation)

    2012-11-01

    Comprehensive analysis of the wave activity in the Antarctic summer mesopause is performed using polar mesospheric summer echoes (PMSE) measurements for December 2010-January 2011. The 2-day planetary wave is a statistically significant periodic oscillation in the power spectrum density of PMSE power. The strongest periodic oscillation in the power spectrum belongs to the diurnal solar tide; the semi-diurnal solar tide is found to be a highly significant harmonic oscillation as well. The inertial-gravity waves are extensively studied by means of PMSE power and wind components. The strongest gravity waves are observed at periods of about 1, 1.4, 2.5 and 4 h, with characteristic horizontal wavelengths of 28, 36, 157 and 252 km, respectively. The gravity waves propagate approximately in the west-east direction over Wasa (Antarctica). A detailed comparison between theoretical and experimental volume reflectivity of PMSE, measured at Wasa, is made. It is demonstrated that a new expression for PMSE reflectivity derived by Varney et al. (2011) is able to adequately describe PMSE profiles both in the magnitude and in height variations. The best agreement, within 30 %, is achieved when mean values of neutral atmospheric parameters are utilized. The largest contribution to the formation and variability of the PMSE layer is explained by the ice number density and its height gradient, followed by waveinduced perturbations in buoyancy period and the turbulent energy dissipation rate. (orig.)

  1. Computational Modeling of Bloch Surface Waves in One-Dimensional Periodic and Aperiodic Multilayer Structures

    Science.gov (United States)

    Koju, Vijay

    -numerical approach, we show that a 1D photonic crystal, a multilayer structure composed of alternating layers of TiO2 and SiO2 , can be used to slow down light by a factor of up to 400. The results also show that better control of the speed of light can be achieved by changing the number of bilayers and the air-gap thickness appropriately. The existence of Bloch surface waves in periodic dielectric multilayer structures with a surface defect is well-known. Not yet recognized is that quasi-crystals and aperiodic dielectric multilayers can also support Bloch-like surface waves. We numerically show the excitation of Bloch-like surface waves in Fibonacci quasi-crystals, Thue-Morse aperiodic dielectric multilayers using the prism coupling method. We report improved surface electric field intensity and penetration depth of Bloch-like surface waves in the air side in such structures compared to their periodic counterparts. Bloch surface waves have also demonstrated significant potential in the field of bios-ensing technology. We further extend our study into a new type of multilayer structure based on Maximal-length sequence, which is a pseudo random sequence. We study the characteristics of Bloch surface waves in a 32 layered Maximal-length sequence multilayer and perform angular, as well as spectral sensitivity analysis for refractive index change detection. We demonstrate numerically that Maximal-length sequence multilayers significantly enhance the sensitivity of Bloch surface waves. Another type of structure that support Bloch surface waves are dielectric multilayer structures with a grating profile on the top-most layer. The grating profile adds an additional degree of freedom to the phase matching conditions for Bloch surface wave excitation. In such structures, the conditions for Bloch surface wave coupling can also be achieved by rotating both polar and azimuthal angles. The generation of Bloch surface waves as a function of azimuthal angle have similar characteristics to

  2. Wave disturbances in the polar ionosphere after a Vitim meteorite burst

    Science.gov (United States)

    Tereshchenko, V. D.; Ogloblina, O. F.; Tereshchenko, V. A.; Chernyakov, S. M.

    On September 24th, 2002, at 16:49 UT in the Mamsko-Chuisk region of the Irkutsk oblast of Russia it was a fall of a big meteorite. The fall was accompanied with light, acoustic, geomagnetic, seismic and mechanical phenomena which were recorded by ground and space means of observations. The meteorite has burst in the air at the altitude of 30 km with coordinates of the burst: 58.23 N, 113.46 E. After 17:00 UT there was recorded a sequence of small disturbances of the geomagnetic field and wavelike changes of amplitude of medium wave radioreflections at heights from 47 till 129 km in Tumanny (Murmansk oblast, Russia; 69.0 N, 35.7 E) which was situated at a distance of 4000 km from a place of the burst. It was gotten that after the burst three types of waves (magnetoacoustic, acoustic-gravitational and infraacoustic) spread in the polar mesosphere and lower ionosphere. Observable disturbances had periods of oscillations about 3-4, 5-6 and more than 9-10 minutes. A similarity characteristics of the wave indignations with analogous ones which were gotten earlier during investigations of effects of the Tungusk meteorite and the American space station "Skylab" falls and also a fact of a registration of a pressure wave on a net of microbarographs of PGI in Apatity permit to maintain that the source of the indignations in the polar ionosphere is the meteorite explosion. The hypothesis about wavequide spreading of atmospheric waves to large distance was confirmed.

  3. Coupling of surface relaxation and polarization in PbTiO{sub 3} from atomistic simulation

    Energy Technology Data Exchange (ETDEWEB)

    Behera, R K; Sinnott, S B; Phillpot, S R [Department of Materials Science and Engineering, University of Florida, Gainesville, FL 32611 (United States); Hinojosa, B B; Asthagiri, A [Department of Chemical Engineering, University of Florida, Gainesville, FL 32611 (United States)], E-mail: sphil@mse.ufl.edu

    2008-10-01

    Molecular dynamics simulations are used to characterize ferroelectricity on the (001) surfaces of PbTiO{sub 3} (PT), one of the most widely studied ferroelectric materials. Two different empirical interatomic shell model potentials are used. Both PbO and TiO{sub 2} surface terminations in PT under open circuit electrical boundary conditions are characterized. The results are found to be in good agreement with the results of density functional theory calculations. The atomic relaxations, interlayer spacings and surface rumplings of each of the four possible surface terminations are analyzed. The deviation of the polarization from the bulk value is observed to be larger when the polarization points out of the surface than when it points into the surface. Analysis of the surface energies for free-standing films shows that polarization parallel to the surface is energetically more favorable than the polarization normal to the surfaces.

  4. Solar energy converter using surface plasma waves

    Science.gov (United States)

    Anderson, L. M. (Inventor)

    1984-01-01

    Sunlight is dispersed over a diffraction grating formed on the surface of a conducting film on a substrate. The angular dispersion controls the effective grating period so that a matching spectrum of surface plasmons is excited for parallel processing on the conducting film. The resulting surface plasmons carry energy to an array of inelastic tunnel diodes. This solar energy converter does not require different materials for each frequency band, and sunlight is directly converted to electricity in an efficient manner by extracting more energy from the more energetic photons.

  5. Surface waves in the partially ionized solar plasma slab

    Science.gov (United States)

    Pandey, B. P.

    2013-12-01

    The properties of surface waves in the partially ionized, incompressible magnetized plasma slab are investigated in the present work. The waves are affected by the non-ideal magnetohydrodynamic (MHD) effects which cause the finite drift of the magnetic field in the medium. When the finite drift of the magnetic field is ignored, the characteristics of the wave propagation in the partially ionized plasma fluid are similar to the ideal MHD, except now the propagation properties depend on the fractional ionization of the medium. In the presence of the Hall diffusion, the propagation of the sausage and kink surface waves depends on the level of fractional ionization of the medium. For example, short wavelength surface modes cannot propagate in the medium if the scale over which Hall operates is comparable to the size of the plasma slab. With the increasing ionization, the surface modes of shorter wavelength are permitted in the system. When both the Hall and Pedersen diffusion are present in the medium, the waves undergo damping. In the case of Pedersen dominating Hall, the damping of the long wavelength fluctuations is dependent on the ratio of the plasma densities inside and outside the slab and on the square of the Pedersen diffusivity. For typical solar parameters, waves may damp over few minutes.

  6. Near Surface Characterization Of Concrete Structures Using Rayleigh Waves

    Science.gov (United States)

    Al Wardany, R.; Ballivy, G.; Saleh, K.; Rhazi, J.; Gallias, J.

    2004-05-01

    The deterioration of the near surface concrete minimises the structural behaviour, capacity, and working lifespan for civil engineering structures and dams. Repair strategy and maintenance require careful examination and determination of the degraded depth. In this aim, dispersive properties of Rayleigh waves are used to detect concrete stratification and cracks. Current work focuses on an experimental study and application of multichannel Rayleigh wave methods on high concrete volumes. The method considers a wavefield in the frequency-wavenumber domain to separate existing Rayleigh modes and determine the appropriate shear wave velocity profile. The classical phase unwrapping analysis technique is also used to localise near surface cracks and defects. This new way in concrete nondestructive testing lead to a best evaluation of near surface stiffness and properties from the surface of concrete structures.

  7. Experiments on seismic metamaterials: molding surface waves.

    Science.gov (United States)

    Brûlé, S; Javelaud, E H; Enoch, S; Guenneau, S

    2014-04-04

    Materials engineered at the micro- and nanometer scales have had a tremendous and lasting impact in photonics and phononics. At much larger scales, natural soils civil engineered at decimeter to meter scales may interact with seismic waves when the global properties of the medium are modified, or alternatively thanks to a seismic metamaterial constituted of a mesh of vertical empty inclusions bored in the initial soil. Here, we show the experimental results of a seismic test carried out using seismic waves generated by a monochromatic vibrocompaction probe. Measurements of the particles' velocities show a modification of the seismic energy distribution in the presence of the metamaterial in agreement with numerical simulations using an approximate plate model. For complex natural materials such as soils, this large-scale experiment was needed to show the practical feasibility of seismic metamaterials and to stress their importance for applications in civil engineering. We anticipate this experiment to be a starting point for smart devices for anthropic and natural vibrations.

  8. Experiments on Seismic Metamaterials: Molding Surface Waves

    Science.gov (United States)

    Brûlé, S.; Javelaud, E. H.; Enoch, S.; Guenneau, S.

    2014-04-01

    Materials engineered at the micro- and nanometer scales have had a tremendous and lasting impact in photonics and phononics. At much larger scales, natural soils civil engineered at decimeter to meter scales may interact with seismic waves when the global properties of the medium are modified, or alternatively thanks to a seismic metamaterial constituted of a mesh of vertical empty inclusions bored in the initial soil. Here, we show the experimental results of a seismic test carried out using seismic waves generated by a monochromatic vibrocompaction probe. Measurements of the particles' velocities show a modification of the seismic energy distribution in the presence of the metamaterial in agreement with numerical simulations using an approximate plate model. For complex natural materials such as soils, this large-scale experiment was needed to show the practical feasibility of seismic metamaterials and to stress their importance for applications in civil engineering. We anticipate this experiment to be a starting point for smart devices for anthropic and natural vibrations.

  9. A transportable hybrid antenna-transmitter system for the generation of elliptically polarized waves for NVIS propagation research

    NARCIS (Netherlands)

    Witvliet, Ben A.; Laanstra, Geert J.; van Maanen, Erik; Alsina-Pagès, Rosa M.; Bentum, Marinus Jan; Slump, Cornelis H.; Schiphorst, Roelof

    2016-01-01

    For empirical research on Near Vertical Incidence Skywave (NVIS) characteristic wave propagation, a beacon transmitter system is needed that can be programmed to emit precisely defined elliptically and circularly polarized waves at high elevation angles. This paper proposes a novel hybrid

  10. Rogue waves driven by polarization instabilities in a long ring fiber oscillator

    Science.gov (United States)

    Kolpakov, S. A.; Kbashi, Hani; Sergeyev, Sergey

    2017-05-01

    We present an experimental and theoretical results of a study of a complex nonlinear polarization dynamics in a passively self-mode-locked erbium-doped fiber oscillator implemented in a ring configuration and operating near lasing threshold. The theoretical model consists of seven coupled non-linear equations and takes into account both orthogonal states of polarizations in the fiber. The experiment confirmed the existence of seven eigenfrequencies, predicted by the model due to polarization instability near lasing threshold. By adjusting the state of polarization of the pump and in-cavity birefringence we changed some eigenfrequencies from being different (non-degenerate state) to matching (degenerate state). The non-degenerate states of oscillator lead to the L-shaped probability distribution function and true rogue wave regime with a positive dominant Lyapunov exponent value between 1.4 and 2.6. Small detuning from partially degenerate case also leads to L-shaped probability distribution function with the tail trespassing eight standard deviations threshold, giving periodic patterns of pulses along with positive dominant Lyapunov exponent of a filtered signal between 0.6 and 3.2. The partial degeneration, in turn, guides to quasi-symmetric distribution and the value of dominant Lyapunov exponent of 42 which is a typical value for systems with a source of the strongly nonhomogeneous external noise.

  11. The MaCWAVE program to study gravity wave influences on the polar mesosphere

    Directory of Open Access Journals (Sweden)

    R. A. Goldberg

    2006-07-01

    Full Text Available MaCWAVE (Mountain and Convective Waves Ascending VErtically was a highly coordinated rocket, ground-based, and satellite program designed to address gravity wave forcing of the mesosphere and lower thermosphere (MLT. The MaCWAVE program was conducted at the Norwegian Andøya Rocket Range (ARR, 69.3° N in July 2002, and continued at the Swedish Rocket Range (Esrange, 67.9° N during January 2003. Correlative instrumentation included the ALOMAR MF and MST radars and RMR and Na lidars, Esrange MST and meteor radars and RMR lidar, radiosondes, and TIMED (Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite measurements of thermal structures. The data have been used to define both the mean fields and the wave field structures and turbulence generation leading to forcing of the large-scale flow. In summer, launch sequences coupled with ground-based measurements at ARR addressed the forcing of the summer mesopause environment by anticipated convective and shear generated gravity waves. These motions were measured with two 12-h rocket sequences, each involving one Terrier-Orion payload accompanied by a mix of MET rockets, all at ARR in Norway. The MET rockets were used to define the temperature and wind structure of the stratosphere and mesosphere. The Terrier-Orions were designed to measure small-scale plasma fluctuations and turbulence that might be induced by wave breaking in the mesosphere. For the summer series, three European MIDAS (Middle Atmosphere Dynamics and Structure rockets were also launched from ARR in coordination with the MaCWAVE payloads. These were designed to measure plasma and neutral turbulence within the MLT. The summer program exhibited a number of indications of significant departures of the mean wind and temperature structures from ``normal" polar summer conditions, including an unusually warm mesopause and a slowing of the formation of polar mesospheric summer echoes (PMSE and noctilucent clouds (NLC. This

  12. NMR investigations of surfaces and interfaces using spin-polarized xenon

    Energy Technology Data Exchange (ETDEWEB)

    Gaede, Holly Caroline [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry

    1995-07-01

    129Xe NMR is potentially useful for the investigation of material surfaces, but has been limited to high surface area samples in which sufficient xenon can be loaded to achieve acceptable signal to noise ratios. In Chapter 2 conventional 129Xe NMR is used to study a high surface area polymer, a catalyst, and a confined liquid crystal to determine the topology of these systems. Further information about the spatial proximity of different sites of the catalyst and liquid crystal systems is determined through two dimensional exchange NMR in Chapter 3. Lower surface area systems may be investigated with spin-polarized xenon, which may be achieved through optical pumping and spin exchange. Optically polarized xenon can be up to 105times more sensitive than thermally polarized xenon. In Chapter 4 highly polarized xenon is used to examine the surface of poly(acrylonitrile) and the formation of xenon clathrate hydrates. An attractive use of polarized xenon is as a magnetization source in cross polarization experiments. Cross polarization from adsorbed polarized xenon may allow detection of surface nuclei with drastic enhancements. A non-selective low field thermal mixing technique is used to enhance the 13C signal of CO2 of xenon occluded in solid CO2 by a factor of 200. High-field cross polarization from xenon to proton on the surface of high surface area polymers has enabled signal enhancements of ~1,000. These studies, together with investigations of the efficiency of the cross polarization process from polarized xenon, are discussed in Chapter 5. Another use of polarized xenon is as an imaging contrast agent in systems that are not compatible with traditional contrast agents. The resolution attainable with this method is determined through images of structured phantoms in Chapter 6.

  13. Continuous wave protocol for simultaneous polarization and optical detection of P1-center electron spin resonance

    Science.gov (United States)

    Kamp, E. J.; Carvajal, B.; Samarth, N.

    2018-01-01

    The ready optical detection and manipulation of bright nitrogen vacancy center spins in diamond plays a key role in contemporary quantum information science and quantum metrology. Other optically dark defects such as substitutional nitrogen atoms (`P1 centers') could also become potentially useful in this context if they could be as easily optically detected and manipulated. We develop a relatively straightforward continuous wave protocol that takes advantage of the dipolar coupling between nitrogen vacancy and P1 centers in type 1b diamond to detect and polarize the dark P1 spins. By combining mutual spin flip transitions with radio frequency driving, we demonstrate the simultaneous optical polarization and detection of the electron spin resonance of the P1 center. This technique should be applicable to detecting and manipulating a broad range of dark spin populations that couple to the nitrogen vacancy center via dipolar fields, allowing for quantum metrology using these spin populations.

  14. Four-wave mixing using polarization grating induced thermal grating in liquids exhibiting circular dichroism

    Energy Technology Data Exchange (ETDEWEB)

    Nunes, J.A.; Tong, W.G. [San Diego State Univ., CA (United States). Dept. of Chemistry; Chandler, D.W.; Rahn, L.A. [Sandia National Lab., Livermore, CA (United States). Combustion Research Facility

    1995-04-01

    A novel four-wave mixing technique for the detection of circular dichroism in optically active liquid samples is demonstrated. When two cross-polarized laser beams are crossed at a small angle in a circular dichroic liquid a weak thermal grating is produced with a phase depending on the sign of the circular dichroism. The authors show that the polarization of one of the beams can be modified to allow coherent interference with an intensity-grating induced thermal grating. A probe beam scattering from the composite grating results in a signal that reveals the sign and magnitude of the circular dichroism. The use of this technique to optimize the signal-to-noise ratio in the presence of scattered light and laser intensity noise is discussed.

  15. Scalable Background-Limited Polarization-Sensitive Detectors for mm-wave Applications

    Science.gov (United States)

    Rostem, Karwan; Ali, Aamir; Appel, John W.; Bennett, Charles L.; Chuss, David T.; Colazo, Felipe A.; Crowe, Erik; Denis, Kevin L.; Essinger-Hileman, Tom; Marriage, Tobias A.; hide

    2014-01-01

    We report on the status and development of polarization-sensitive detectors for millimeter-wave applications. The detectors are fabricated on single-crystal silicon, which functions as a low-loss dielectric substrate for the microwave circuitry as well as the supporting membrane for the Transition-Edge Sensor (TES) bolometers. The orthomode transducer (OMT) is realized as a symmetric structure and on-chip filters are employed to define the detection bandwidth. A hybridized integrated enclosure reduces the high-frequency THz mode set that can couple to the TES bolometers. An implementation of the detector architecture at Q-band achieves 90% efficiency in each polarization. The design is scalable in both frequency coverage, 30-300 GHz, and in number of detectors with uniform characteristics. Hence, the detectors are desirable for ground-based or space-borne instruments that require large arrays of efficient background-limited cryogenic detectors.

  16. Polarized Kink Waves in Magnetic Elements: Evidence for Chromospheric Helical Waves

    Energy Technology Data Exchange (ETDEWEB)

    Stangalini, M.; Giannattasio, F. [INAF-OAR National Institute for Astrophysics, Via Frascati 33, I-00078 Monte Porzio Catone (RM) (Italy); Erdélyi, R. [Solar Physics and Space Plasma Research Centre (SP2RC), School of Mathematics and Statistics, University of Sheffield, Sheffield S3 7RH (United Kingdom); Jafarzadeh, S. [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, NO-0315 Oslo (Norway); Consolini, G.; Ermolli, I. [INAF-IAPS National Institute for Astrophysics, Via del Fosso del Cavaliere, 100, I-00133 Rome (Italy); Criscuoli, S. [NSO, National Solar Observatory, Boulder, CO 80303 (United States); Guglielmino, S. L.; Zuccarello, F., E-mail: marco.stangalini@inaf.it [Department of Physics and Astronomy, University of Catania, Via S. Sofia 78, I-95125 Catania (Italy)

    2017-05-01

    In recent years, new high spatial resolution observations of the Sun's atmosphere have revealed the presence of a plethora of small-scale magnetic elements down to the resolution limit of the current cohort of solar telescopes (∼100–120 km on the solar photosphere). These small magnetic field concentrations, due to the granular buffeting, can support and guide several magnetohydrodynamic wave modes that would eventually contribute to the energy budget of the upper layers of the atmosphere. In this work, exploiting the high spatial and temporal resolution chromospheric data acquired with the Swedish 1 m Solar Telescope, and applying the empirical mode decomposition technique to the tracking of the solar magnetic features, we analyze the perturbations of the horizontal velocity vector of a set of chromospheric magnetic elements. We find observational evidence that suggests a phase relation between the two components of the velocity vector itself, resulting in its helical motion.

  17. Artificial ocean upwelling utilizing the energy of surface waves

    Science.gov (United States)

    Soloviev, Alexander

    2016-04-01

    Artificial upwelling can bring cold water from below the thermocline to the sea surface. Vershinsky, Pshenichnyy, and Soloviev (1987) developed a prototype device, utilizing the energy of surface waves to create an upward flow of water in the tube. This is a wave-inertia pump consisting of a vertical tube, a valve, and a buoy to keep the device afloat. An outlet valve at the top of the unit synchronizes the operation of the device with surface waves and prevents back-splashing. A single device with a 100 m long and 1.2 m diameter tube is able to produce up to 1 m3s-1 flow of deep water to the surface. With a 10 oC temperature difference over 100 m depth, the negative heat supply rate to the sea surface is 42 MW, which is equivalent to a 42 Wm-2 heat flux, if distributed over 1 km2 area. Such flux is comparable to the average net air-sea flux. A system of artificial upwelling devices can cool down the sea surface, modify climate on a regional scale and possibly help mitigate hurricanes. The cold water brought from a deeper layer, however, has a larger density than the surface water and therefore has a tendency to sink back down. In this work, the efficiency of wave-inertia pumps and climatic consequences are estimated for different environmental conditions using a computational fluid dynamics model.

  18. LATERAL FLOODING ASSOCIATED TO WAVE FLOOD GENERATION ON RIVER SURFACE

    Directory of Open Access Journals (Sweden)

    C. Ramírez-Núñez

    2016-06-01

    Full Text Available This research provides a wave flood simulation using a high resolution LiDAR Digital Terrain Model. The simulation is based on the generation of waves of different amplitudes that modify the river level in such a way that water invades the adjacent areas. The proposed algorithm firstly reconstitutes the original river surface of the studied river section and then defines the percentage of water loss when the wave floods move downstream. This procedure was applied to a gently slope area in the lower basin of Coatzacoalcos river, Veracruz (Mexico defining the successive areas where lateral flooding occurs on its downstream movement.

  19. Lateral Flooding Associated to Wave Flood Generation on River Surface

    Science.gov (United States)

    Ramírez-Núñez, C.; Parrot, J.-F.

    2016-06-01

    This research provides a wave flood simulation using a high resolution LiDAR Digital Terrain Model. The simulation is based on the generation of waves of different amplitudes that modify the river level in such a way that water invades the adjacent areas. The proposed algorithm firstly reconstitutes the original river surface of the studied river section and then defines the percentage of water loss when the wave floods move downstream. This procedure was applied to a gently slope area in the lower basin of Coatzacoalcos river, Veracruz (Mexico) defining the successive areas where lateral flooding occurs on its downstream movement.

  20. Evaluation of polarization of embedded piezoelectrics by the thermal wave method.

    Science.gov (United States)

    Suchaneck, Gunnar; Eydam, Agnes; Hu, Wenguo; Kranz, Burkhart; Drossel, Welf-Guntram; Gerlach, Gerald

    2012-09-01

    This work demonstrates the benefit of the thermal wave method for the evaluation of the polarization state of embedded piezoelectrics. Two types of samples were investigated: A low-temperature co-fired ceramics (LTCC)/lead zirconate titanate (PZT) sensor-actuator and a macro-fiber composite (MFC) actuator. At modulation frequencies below 10 Hz, the pyroelectric response was governed by thermal losses to the embedding layers. Here, the sample behavior was described by a harmonically heated piezoelectric plate exhibiting heat losses to the environment characterized by a single thermal relaxation time.

  1. Bistable states of TM polarized non-linear waves guided by symmetric layered structures

    International Nuclear Information System (INIS)

    Mihalache, D.

    1985-04-01

    Dispersion relations for TM polarized non-linear waves propagating in a symmetric single film optical waveguide are derived. The system consists of a layer of thickness d with dielectric constant epsilon 1 bounded at two sides by a non-linear medium characterized by the diagonal dielectric tensor epsilon 11 =epsilon 22 =epsilon 0 , epsilon 33 =epsilon 0 +α|E 3 | 2 , where E 3 is the normal electric field component. For sufficiently large d/lambda (lambda is the wavelength) we predict bistable states of both symmetric and antisymmetric modes provided that the power flow is the control parameter. (author)

  2. Degenerate four-wave mixing and polarization spectroscopy in NO2

    Science.gov (United States)

    De Dominicis, Luigi; Fantoni, Roberta; Giorgi, Mariano

    2002-05-01

    Degenerate Four Wave Mixing (DFWM) and polarization spectroscopy (PS) have been used to detect traces of nitric dioxide in a static cell at room temperature and in a small flame from a laboratory Bunsen burner. The high resolution spectrum of the Douglas-Huber band has been recorded with both techniques. The role played by population and thermal gratings in the DFWM case has been investigated under various experimental conditions. PS measurements performed with 'orientation' and 'alignment' configurations allowed to resolve NO2 composite spectral features.

  3. Numerical Simulation of Floating Bodies in Extreme Free Surface Waves

    Science.gov (United States)

    Hu, Zheng Zheng; Causon, Derek; Mingham, Clive; Qiang, Ling

    2010-05-01

    A task of the EPSRC funded research project 'Extreme Wave loading on Offshore Wave Energy Devices: a Hierarchical Team Approach' is to investigate the survivability of two wave energy converter (WEC) devices Pelamis and the Manchester Bobber using different CFD approaches. Both devices float on the water surface, generating the electricity from the motion of the waves. In this paper, we describe developments of the AMAZON-SC 3D numerical wave tank (NWT) to study extreme wave loading of a fixed or floating (in Heave motion) structure. The extreme wave formulation as an inlet condition is due to Dalzell (1999) and Ning et. al. (2009) in which a first or second-order Stokes focused wave can be prescribed. The AMAZON-SC 3D code (see e.g. Hu et al. (2009)) uses a cell centred finite volume method of the Godunov-type for the space discretization of the Euler and Navier Stokes equations. The computational domain includes both air and water regions with the air/water boundary captured as a discontinuity in the density field thereby admitting the break up and recombination of the free surface. Temporal discretisation uses the artificial compressibility method and a dual time stepping strategy to maintain a divergence free velocity field. Cartesian cut cells are used to provide a fully boundary-fitted gridding capability on an regular background Cartesian grid. Solid objects are cut out of the background mesh leaving a set of irregularly shaped cells fitted to the boundary. The advantages of the cut cell approach have been outlined previously by Causon et al. (2000, 2001) including its flexibility for dealing with complex geometries whether stationary or in relative motion. The field grid does not need to be recomputed globally or even locally for moving body cases; all that is necessary is to update the local cut cell data at the body contour for as long as the motion continues. The handing of numerical wave paddles and device motion in a NWT is therefore straightforward

  4. The MaCWAVE program to study gravity wave influences on the polar mesosphere

    Directory of Open Access Journals (Sweden)

    R. A. Goldberg

    2006-07-01

    Full Text Available MaCWAVE (Mountain and Convective Waves Ascending VErtically was a highly coordinated rocket, ground-based, and satellite program designed to address gravity wave forcing of the mesosphere and lower thermosphere (MLT. The MaCWAVE program was conducted at the Norwegian Andøya Rocket Range (ARR, 69.3° N in July 2002, and continued at the Swedish Rocket Range (Esrange, 67.9° N during January 2003. Correlative instrumentation included the ALOMAR MF and MST radars and RMR and Na lidars, Esrange MST and meteor radars and RMR lidar, radiosondes, and TIMED (Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite measurements of thermal structures. The data have been used to define both the mean fields and the wave field structures and turbulence generation leading to forcing of the large-scale flow. In summer, launch sequences coupled with ground-based measurements at ARR addressed the forcing of the summer mesopause environment by anticipated convective and shear generated gravity waves. These motions were measured with two 12-h rocket sequences, each involving one Terrier-Orion payload accompanied by a mix of MET rockets, all at ARR in Norway. The MET rockets were used to define the temperature and wind structure of the stratosphere and mesosphere. The Terrier-Orions were designed to measure small-scale plasma fluctuations and turbulence that might be induced by wave breaking in the mesosphere. For the summer series, three European MIDAS (Middle Atmosphere Dynamics and Structure rockets were also launched from ARR in coordination with the MaCWAVE payloads. These were designed to measure plasma and neutral turbulence within the MLT. The summer program exhibited a number of indications of significant departures of the mean wind and temperature structures from ``normal" polar summer conditions, including an unusually warm mesopause and

  5. Surface waves in an heterogeneous anisotropic continental lithosphere

    Science.gov (United States)

    Maupin, V.

    2003-04-01

    At global as well as at regional scale, the lithosphere appears usually faster to Love waves than to Rayleigh waves. This Love-Rayleigh discrepancy can be modelled by introducing transverse isotropy in the mantle. In continental structures, the amount of transverse isotropy necessary to explain the discrepancy is however often quite large and not compatible with results of SKS-splitting analysis and azimuthal variation of surface wave velocities, at least in the simple framework of large scale uniform olivine orientation in the continental lithosphere. Models where the orientation of the olivine is incoherent at the scale of a few hundred km have been proposed to reconcile the different datasets, but the surface wave characteristics in such anisotropic heterogeneous models have not yet been analysed in detail. Using a mode-coupling scheme for calculating surface wave propagation in heterogeneous anisotropic structures, we analyse the characteristics of Rayleigh and Love waves in such laterally varying anisotropic models. We generate 3-D stochastic models of olivine orientation with different characteristics: preferred orientation dominantly horizontal, vertical or equally distributed in all directions, and use different correlation lengths in the horizontal and vertical directions to constrain the scale at which the anisotropy is coherent. We analyse the apparent Love-Rayleigh discrepancy and the phase velocity azimuthal variation these models generate and the mode-coupling and polarisation anomalies they produce.

  6. Enhanced sensitive love wave surface acoustic wave sensor designed for immunoassay formats.

    Science.gov (United States)

    Puiu, Mihaela; Gurban, Ana-Maria; Rotariu, Lucian; Brajnicov, Simona; Viespe, Cristian; Bala, Camelia

    2015-05-05

    We report a Love wave surface acoustic wave (LW-SAW) immunosensor designed for the detection of high molecular weight targets in liquid samples, amenable also for low molecular targets in surface competition assays. We implemented a label-free interaction protocol similar to other surface plasmon resonance bioassays having the advantage of requiring reduced time analysis. The fabricated LW-SAW sensor supports the detection of the target in the nanomolar range, and can be ultimately incorporated in portable devices, suitable for point-of-care testing (POCT) applications.

  7. Enhanced Sensitive Love Wave Surface Acoustic Wave Sensor Designed for Immunoassay Formats

    Directory of Open Access Journals (Sweden)

    Mihaela Puiu

    2015-05-01

    Full Text Available We report a Love wave surface acoustic wave (LW-SAW immunosensor designed for the detection of high molecular weight targets in liquid samples, amenable also for low molecular targets in surface competition assays. We implemented a label-free interaction protocol similar to other surface plasmon resonance bioassays having the advantage of requiring reduced time analysis. The fabricated LW-SAW sensor supports the detection of the target in the nanomolar range, and can be ultimately incorporated in portable devices, suitable for point-of-care testing (POCT applications.

  8. Surface-Wave Relocation of Remote Continental Earthquakes

    Science.gov (United States)

    Kintner, J. A.; Ammon, C. J.; Cleveland, M.

    2017-12-01

    Accurate hypocenter locations are essential for seismic event analysis. Single-event location estimation methods provide relatively imprecise results in remote regions with few nearby seismic stations. Previous work has demonstrated that improved relative epicentroid precision in oceanic environments is obtainable using surface-wave cross correlation measurements. We use intermediate-period regional and teleseismic Rayleigh and Love waves to estimate relative epicentroid locations of moderately-sized seismic events in regions around Iran. Variations in faulting geometry, depth, and intermediate-period dispersion make surface-wave based event relocation challenging across this broad continental region. We compare and integrate surface-wave based relative locations with InSAR centroid location estimates. However, mapping an earthquake sequence mainshock to an InSAR fault deformation model centroid is not always a simple process, since the InSAR observations are sensitive to post-seismic deformation. We explore these ideas using earthquake sequences in western Iran. We also apply surface-wave relocation to smaller magnitude earthquakes (3.5 wave dispersion. Frequency-domain inter-event phase observations are used to understand the time-domain cross-correlation information, and to choose the appropriate band for applications using shorter periods. Over short inter-event distances, the changing group velocity does not strongly degrade the relative locations. For small-magnitude seismic events in continental regions, surface-wave relocation does not appear simple enough to allow broad routine application, but using this method to analyze individual earthquake sequences can provide valuable insight into earthquake and faulting processes.

  9. Fermi wave vector for the partially spin-polarized composite-fermion Fermi sea

    Science.gov (United States)

    Balram, Ajit C.; Jain, J. K.

    2017-12-01

    The fully spin-polarized composite-fermion (CF) Fermi sea at the half-filled lowest Landau level has a Fermi wave vector kF*=√{4 π ρe } , where ρe is the density of electrons or composite fermions, supporting the notion that the interaction between composite fermions can be treated perturbatively. Away from ν =1 /2 , the area is seen to be consistent with kF*=√{4 π ρe } for ν 1 /2 , where ρh is the density of holes in the lowest Landau level. This result is consistent with particle-hole symmetry in the lowest Landau level. We investigate in this article the Fermi wave vector of the spin-singlet CF Fermi sea (CFFS) at ν =1 /2 , for which particle-hole symmetry is not a consideration. Using the microscopic CF theory, we find that for the spin-singlet CFFS the Fermi wave vectors for up- and down-spin CFFSs at ν =1 /2 are consistent with kF*↑,↓=√{4 π ρe↑,↓ } , where ρe↑=ρe↓=ρe/2 , which implies that the residual interactions between composite fermions do not cause a nonperturbative correction for spin-singlet CFFS either. Our results suggest the natural conjecture that for arbitrary spin polarization the CF Fermi wave vectors are given by kF*↑=√{4 π ρe↑ } and kF*↓=√{4 π ρe↓ } .

  10. ACCELERATING WAVES IN POLAR CORONAL HOLES AS SEEN BY EIS AND SUMER

    International Nuclear Information System (INIS)

    Gupta, G. R.; Banerjee, D.; Teriaca, L.; Solanki, S.; Imada, S.

    2010-01-01

    We present EIS/Hinode and SUMER/SOHO observations of propagating disturbances detected in coronal lines in inter-plume and plume regions of a polar coronal hole. The observation was carried out on 2007 November 13 as part of the JOP196/HOP045 program. The SUMER spectroscopic observation gives information about fluctuations in radiance and on both resolved (Doppler shift) and unresolved (Doppler width) line-of-sight velocities, whereas EIS 40'' wide slot images detect fluctuations only in radiance but maximize the probability of overlapping field of view between the two instruments. From distance-time radiance maps, we detect the presence of propagating waves in a polar inter-plume region with a period of 15-20 minutes and a propagation speed increasing from 130 ± 14 km s -1 just above the limb to 330 ± 140 km s -1 around 160'' above the limb. These waves can be traced to originate from a bright region of the on-disk part of the coronal hole where the propagation speed is in the range of 25 ± 1.3 to 38 ± 4.5 km s -1 , with the same periodicity. These on-disk bright regions can be visualized as the base of the coronal funnels. The adjacent plume region also shows the presence of propagating disturbances with the same range of periodicity but with propagation speeds in the range of 135 ± 18 to 165 ± 43 km s -1 only. A comparison between the distance-time radiance map of the two regions indicates that the waves within the plumes are not observable (may be getting dissipated) far off-limb, whereas this is not the case in the inter-plume region. A correlation analysis was also performed to find out the time delay between the oscillations at several heights in the off-limb region, finding results consistent with those from the analysis of the distance-time maps. To our knowledge, this result provides first spectroscopic evidence of the acceleration of propagating disturbances in the polar region close to the Sun (within 1.2 R/R sun ), which provides clues to the

  11. Relationship between ultrasonic Rayleigh waves and surface residual stress

    International Nuclear Information System (INIS)

    Adler, L.; Cook, K.V.; Dewey, B.R.; King, R.T.

    1977-01-01

    Local variations of Rayleigh (surface) circumferential ultrasonic wave velocity near a pipe-girth weld in large-diameter thin-wall type 316H stainless steel pipe were measured. The weldment was similar to those anticipated for the Liquid Metal Fast Breeder Reactor (LMFBR) piping systems. The residual stress distribution was estimated independently from shell theory for an elastic, infinite, thin shell with circumferential line loading. An upper bound on the magnitude of the residual stresses was estimated assuming the deformation of the shell was entirely elastic. The pattern of surface wave velocity variations matches the theoretical residual stress pattern closely. It is suggested that the monitoring of surface wave velocity variations might be used for characterizing residual stress patterns near critical welds in piping, aiding in design calculations, and for in-service monitoring of the state of stress of weldments

  12. Surface Acoustic Wave Devices for Harsh Environment Wireless Sensing

    Directory of Open Access Journals (Sweden)

    David W. Greve

    2013-05-01

    Full Text Available Langasite surface acoustic wave devices can be used to implement harsh-environment wireless sensing of gas concentration and temperature. This paper reviews prior work on the development of langasite surface acoustic wave devices, followed by a report of recent progress toward the implementation of oxygen gas sensors. Resistive metal oxide films can be used as the oxygen sensing film, although development of an adherent barrier layer will be necessary with the sensing layers studied here to prevent interaction with the langasite substrate. Experimental results are presented for the performance of a langasite surface acoustic wave oxygen sensor with tin oxide sensing layer, and these experimental results are correlated with direct measurements of the sensing layer resistivity.

  13. Langasite Surface Acoustic Wave Sensors: Fabrication and Testing

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Peng; Greve, David W.; Oppenheim, Irving J.; Chin, Tao-Lun; Malone, Vanessa

    2012-02-01

    We report on the development of harsh-environment surface acoustic wave sensors for wired and wireless operation. Surface acoustic wave devices with an interdigitated transducer emitter and multiple reflectors were fabricated on langasite substrates. Both wired and wireless temperature sensing was demonstrated using radar-mode (pulse) detection. Temperature resolution of better than ±0.5°C was achieved between 200°C and 600°C. Oxygen sensing was achieved by depositing a layer of ZnO on the propagation path. Although the ZnO layer caused additional attenuation of the surface wave, oxygen sensing was accomplished at temperatures up to 700°C. The results indicate that langasite SAW devices are a potential solution for harsh-environment gas and temperature sensing.

  14. Surface Wave Velocity-Stress Relationship in Uniaxially Loaded Concrete

    DEFF Research Database (Denmark)

    Shokouhi, Parisa; Zoëga, Andreas; Wiggenhauser, Herbert

    2012-01-01

    loading cycles revealed that the velocities show a stress-memory effect in good agreement with the Kaiser effect. Comparing the velocities measured during loading and unloading, the effects of stress and damage on the measured velocities could be differentiated. Moreover, the stress dependency of surface......The sonic surface wave (or Rayleigh wave) velocity measured on prismatic concrete specimens under uniaxial compression was found to be highly stress-dependent. At low stress levels, the acoustoelastic effect and the closure of existing microcracks results in a gradual increase in surface wave...... velocities. At higher stress levels, concrete suffers irrecoverable damage: the existing microcracks widen and coalesce and new microcracks form. This progressive damage process leads first to the flattening and eventually the drop in the velocity-stress curves. Measurements on specimens undergoing several...

  15. Ultrasonic attenuation of surface acoustic waves in superconducting zinc

    International Nuclear Information System (INIS)

    Bailey, W.E.; Marshall, B.J.

    1979-01-01

    The attenuation of 90-MHz elastic surface waves propagating in both 3,000 and 10,000 A films of zinc has been measured as a function of temperature from 3 to 0.38 K. The surface acoustic waves were generated and detected by using a surface-acoustic-wave device interdigital transducers plated onto a Y-Z cut lithium-niobate substrate. Utilizing the experimental results, in the BCS theory, energy gaps of 2Δ (0) equal to 4.17 +- 0.20 and 3.81 +- 0.20 in units of k/sub B/T/sub c/ were calculated for the 3,000 and 10,000 A films, respectively. The transition temperatures for the 3,000 and 10,000 A films were 1.5 +- 0.01 and 1.31 +- 0.01 K, respectively

  16. Engineered metabarrier as shield from seismic surface waves.

    Science.gov (United States)

    Palermo, Antonio; Krödel, Sebastian; Marzani, Alessandro; Daraio, Chiara

    2016-12-20

    Resonant metamaterials have been proposed to reflect or redirect elastic waves at different length scales, ranging from thermal vibrations to seismic excitation. However, for seismic excitation, where energy is mostly carried by surface waves, energy reflection and redirection might lead to harming surrounding regions. Here, we propose a seismic metabarrier able to convert seismic Rayleigh waves into shear bulk waves that propagate away from the soil surface. The metabarrier is realized by burying sub-wavelength resonant structures under the soil surface. Each resonant structure consists of a cylindrical mass suspended by elastomeric springs within a concrete case and can be tuned to the resonance frequency of interest. The design allows controlling seismic waves with wavelengths from 10-to-100 m with meter-sized resonant structures. We develop an analytical model based on effective medium theory able to capture the mode conversion mechanism. The model is used to guide the design of metabarriers for varying soil conditions and validated using finite-element simulations. We investigate the shielding performance of a metabarrier in a scaled experimental model and demonstrate that surface ground motion can be reduced up to 50% in frequency regions below 10 Hz, relevant for the protection of buildings and civil infrastructures.

  17. Measuring sea surface height with a GNSS-Wave Glider

    Science.gov (United States)

    Morales Maqueda, Miguel Angel; Penna, Nigel T.; Foden, Peter R.; Martin, Ian; Cipollini, Paolo; Williams, Simon D.; Pugh, Jeff P.

    2017-04-01

    A GNSS-Wave Glider is a novel technique to measure sea surface height autonomously using the Global Navigation Satellite System (GNSS). It consists of an unmanned surface vehicle manufactured by Liquid Robotics, a Wave Glider, and a geodetic-grade GNSS antenna-receiver system, with the antenna installed on a mast on the vehicle's deck. The Wave Glider uses the differential wave motion through the water column for propulsion, thus guaranteeing an, in principle, indefinite autonomy. Solar energy is collected to power all on-board instrumentation, including the GNSS system. The GNSS-Wave Glider was first tested in Loch Ness in 2013, demonstrating that the technology is capable of mapping geoid heights within the loch with an accuracy of a few centimetres. The trial in Loch Ness did not conclusively confirm the reliability of the technique because, during the tests, the state of the water surface was much more benign than would normally be expect in the open ocean. We now report on a first deployment of a GNSS-Wave Glider in the North Sea. The deployment took place in August 2016 and lasted thirteen days, during which the vehicle covered a distance of about 350 nautical miles in the north western North Sea off Great Britain. During the experiment, the GNSS-Wave Glider experienced sea states between 1 (0-0.1 m wave heights) and 5 (2.5-4 m wave heights). The GNSS-Wave Glider data, recorded at 5 Hz frequency, were analysed using a post-processed kinematic GPS-GLONASS precise point positioning (PPP) approach, which were quality controlled using double difference GPS kinematic processing with respect to onshore reference stations. Filtered with a 900 s moving-average window, the PPP heights reveal geoid patterns in the survey area that are very similar to the EGM2008 geoid model, thus demonstrating the potential use of a GNSS-Wave Glider for marine geoid determination. The residual of subtracting the modelled or measured marine geoid from the PPP signal combines information

  18. Super-virtual Interferometric Separation and Enhancement of Back-scattered Surface Waves

    KAUST Repository

    Guo, Bowen

    2015-08-19

    Back-scattered surface waves can be migrated to detect near-surface reflectors with steep dips. A robust surface-wave migration requires the prior separation of the back-scattered surface-wave events from the data. This separation is often difficult to implement because the back-scattered surface waves are masked by the incident surface waves. We mitigate this problem by using a super-virtual interferometric method to enhance and separate the back-scattered surface waves. The key idea is to calculate the virtual back-scattered surface waves by stacking the resulting virtual correlated and convolved traces associated with the incident and back-scattered waves. Stacking the virtual back-scattered surface waves improves their signal-to-noise ratio and separates the back-scattered surface-waves from the incident field. Both synthetic and field data results validate the robustness of this method.

  19. Photonic Crystal Biosensor Based on Optical Surface Waves

    Directory of Open Access Journals (Sweden)

    Giovanni Dietler

    2013-02-01

    Full Text Available A label-free biosensor device based on registration of photonic crystal surface waves is described. Angular interrogation of the optical surface wave resonance is used to detect changes in the thickness of an adsorbed layer, while an additional simultaneous detection of the critical angle of total internal reflection provides independent data of the liquid refractive index. The abilities of the device are demonstrated by measuring of biotin molecule binding to a streptavidin monolayer, and by measuring association and dissociation kinetics of immunoglobulin G proteins. Additionally, deposition of PSS / PAH polyelectrolytes is recorded in situ resulting calculation of PSS and PAH monolayer thicknesses separately.

  20. Velocity profiles and surface roughness under breaking waves

    Science.gov (United States)

    Craig, Peter D.

    1996-01-01

    Recent measurements under wave-breaking conditions in the ocean, lakes, and tanks reveal a layer immediately below the surface in which dissipation decays as depth to the power -2 to -4 and downwind velocities are approximately linear with depth. This behavior is consistent with predictions of a conventional, one-dimensional, level 2.5 turbulence closure model, in which the influence of breaking waves is parameterized as a surface source of turbulent kinetic energy. The model provides an analytic solution which describes the near-surface power law behavior and the deeper transition to the "law of the wall." The mixing length imposed in the model increases linearly away from a minimum value, the roughness length, at the surface. The surface roughness emerges as an important scaling factor in the wave-enhanced layer but is the major unknown in the formulation. Measurements in the wave-affected layer are still rare, but one exceptional set, both in terms of its accuracy and proximity to the surface, is that collected by Cheung and Street [1988] in the Stanford wind tunnel. Their velocity profiles first confirm the accuracy of the model, and, second, allow estimation, via a best fit procedure, of roughness lengths at five different wind speeds. Conclusions are tentative but indicate that the roughness length increases with wind speed and appears to take a value of approximately one sixth the dominant surface wavelength. A more traditional wall-layer model, which ignores the flux of turbulent kinetic energy, will also accurately reproduce the measured velocity profiles. In this case, enhanced surface turbulence is forced on the model by the assumption of a large surface roughness, three times that required by the full model. However, the wall-layer model cannot predict the enhanced dissipation near the surface.

  1. Quantum mechanical systems interacting with different polarizations of gravitational waves in noncommutative phase space

    Science.gov (United States)

    Saha, Anirban; Gangopadhyay, Sunandan; Saha, Swarup

    2018-02-01

    Owing to the extreme smallness of any noncommutative scale that may exist in nature, both in the spatial and momentum sector of the quantum phase space, a credible possibility of their detection lies in the gravitational wave (GW) detection scenario, where one effectively probes the relative length-scale variations ˜O [10-20-10-23] . With this motivation, we have theoretically constructed how a free particle and a harmonic oscillator will respond to linearly and circularly polarized gravitational waves if their quantum mechanical phase space has a noncommutative structure. We critically analyze the formal solutions which show resonance behavior in the responses of both free particle and HO systems to GW with both kind of polarizations. We discuss the possible implications of these solutions in detecting noncommutativity in a GW detection experiment. We use the currently available upper-bound estimates on various noncommutative parameters to anticipate the relative importance of various terms in the solutions. We also argue how the quantum harmonic oscillator system we considered here can be very relevant in the context of the resonant bar detectors of GW which are already operational.

  2. Illuminating "spin-polarized" Bloch wave-function projection from degenerate bands in decomposable centrosymmetric lattices

    Science.gov (United States)

    Li, Pengke; Appelbaum, Ian

    2018-03-01

    The combination of space inversion and time-reversal symmetries results in doubly degenerate Bloch states with opposite spin. Many lattices with these symmetries can be constructed by combining a noncentrosymmetric potential (lacking this degeneracy) with its inverted copy. Using simple models, we unravel the evolution of local spin splitting during this process of inversion symmetry restoration, in the presence of spin-orbit interaction and sublattice coupling. Importantly, through an analysis of quantum mechanical commutativity, we examine the difficulty of identifying states that are simultaneously spatially segregated and spin polarized. We also explain how surface-sensitive experimental probes (such as angle-resolved photoemission spectroscopy, or ARPES) of "hidden spin polarization" in layered materials are susceptible to unrelated spin splitting intrinsically induced by broken inversion symmetry at the surface.

  3. Atmospheric Polarization Imaging with Variable Aerosols, Clouds, and Surface Albedo

    Science.gov (United States)

    2013-07-01

    Continuous outdoor operation of an all-sky polarization imager,” Proc. SPIE 7672 (Polarization: Measurement, Analysis , and Remote Sensing IX), 76720A-1-7, 7...condensation nuclei activity and hygroscopicity of in-situ biomass burning aerosol,” American Assoc. Aerosol Research 31 st Annual Conference...tunable liquid crystal variable retarders (LCVRs) allows the API to achieve much faster Stokes-image acquisition than instruments that rely on

  4. Surface waves on currents with arbitrary vertical shear

    Science.gov (United States)

    Smeltzer, Benjamin K.; Ellingsen, Simen Å.

    2017-04-01

    We study dispersion properties of linear surface gravity waves propagating in an arbitrary direction atop a current profile of depth-varying magnitude using a piecewise linear approximation and develop a robust numerical framework for practical calculation. The method has been much used in the past for the case of waves propagating along the same axis as the background current, and we herein extend and apply it to problems with an arbitrary angle between the wave propagation and current directions. Being valid for all wavelengths without loss of accuracy, the scheme is particularly well suited to solve problems involving a broad range of wave vectors, such as ship waves and Cauchy-Poisson initial value problems. We examine the group and phase velocities over different wavelength regimes and current profiles, highlighting characteristics due to the depth-variable vorticity. We show an example application to ship waves on an arbitrary current profile and demonstrate qualitative differences in the wake patterns between concave down and concave up profiles when compared to a constant shear profile with equal depth-averaged vorticity. We also discuss the nature of additional solutions to the dispersion relation when using the piecewise-linear model. These are vorticity waves, drifting vortical structures which are artifacts of the piecewise model. They are absent for a smooth profile and are spurious in the present context.

  5. Boussinesq modeling of surface waves due to underwater landslides

    Directory of Open Access Journals (Sweden)

    D. Dutykh

    2013-05-01

    Full Text Available Consideration is given to the influence of an underwater landslide on waves at the surface of a shallow body of fluid. The equations of motion that govern the evolution of the barycenter of the landslide mass include various dissipative effects due to bottom friction, internal energy dissipation, and viscous drag. The surface waves are studied in the Boussinesq scaling, with time-dependent bathymetry. A numerical model for the Boussinesq equations is introduced that is able to handle time-dependent bottom topography, and the equations of motion for the landslide and surface waves are solved simultaneously. The numerical solver for the Boussinesq equations can also be restricted to implement a shallow-water solver, and the shallow-water and Boussinesq configurations are compared. A particular bathymetry is chosen to illustrate the general method, and it is found that the Boussinesq system predicts larger wave run-up than the shallow-water theory in the example treated in this paper. It is also found that the finite fluid domain has a significant impact on the behavior of the wave run-up.

  6. Polarization and Compressibility of Oblique Kinetic Alfvén Waves

    Science.gov (United States)

    Hunana, P.; Goldstein, M. L.; Passot, T.; Sulem, P. L.; Laveder, D.; Zank, G. P.

    2013-04-01

    It is well known that a complete description of the solar wind requires a kinetic description and that, particularly at sub-proton scales, kinetic effects cannot be ignored. It is nevertheless usually assumed that at scales significantly larger than the proton gyroscale rL , magnetohydrodynamics or its extensions, such as Hall-MHD and two-fluid models with isotropic pressures, provide a satisfactory description of the solar wind. Here we calculate the polarization and magnetic compressibility of oblique kinetic Alfvén waves and show that, compared with linear kinetic theory, the isotropic two-fluid description is very compressible, with the largest discrepancy occurring at scales larger than the proton gyroscale. In contrast, introducing anisotropic pressure fluctuations with the usual double-adiabatic (or CGL) equations of state yields compressibility values which are unrealistically low. We also show that both of these classes of fluid models incorrectly describe the electric field polarization. To incorporate linear kinetic effects, we use two versions of the Landau fluid model that include linear Landau damping and finite Larmor radius (FLR) corrections. We show that Landau damping is crucial for correct modeling of magnetic compressibility, and that the anisotropy of pressure fluctuations should not be introduced without taking into account the Landau damping through appropriate heat flux equations. We also show that FLR corrections to all the retained fluid moments appear to be necessary to yield the correct polarization. We conclude that kinetic effects cannot be ignored even for krL Lt 1.

  7. Nonlinear waves in viscoelastic magnetized complex astroplasmas with polarized dust-charge variations

    Directory of Open Access Journals (Sweden)

    Papari Das

    2018-01-01

    Full Text Available A nonextensive nonthermal magnetized viscoelastic astrofluid, compositionally containing nonthermal electrons and ions together with massive polarized dust micro-spherical grains of variable electric charge, is allowed to endure weakly nonlinear perturbation around its equilibrium. The nonextensivity originating from the large-scale non-local effects is included via the Tsallis thermo-statistical distribution laws describing the lighter species. Assuming the equilibrium as a homogeneous hydrostatic one, the dust polarization effects are incorporated via the conventional homogeneous polarization force law. The perturbed fluid model evolves as a unique conjugate pair of coupled extended Korteweg-de Vries (e-KdV equations. A constructed numerical tapestry shows the collective excitations of a new pair of distinct classes of nonlinear mode structures in new parametric space. The first family indicates periodic electrostatic compressive eigenmodes in the form of soliton-chains. Likewise, the second one reveals gravitational rarefactive solitary patterns. Their microphysical multi-parametric dependencies of the eigen-patterns are illustratively analyzed and bolstered. The paper ends up with some promising implications and applications in the astro-cosmo-plasmic context of wave-induced accretive triggering processes responsible for gravitationally bounded (gravito-condensed astro-structure formation, such as stellesimals, planetsimals, etc.

  8. Nonlinear waves in viscoelastic magnetized complex astroplasmas with polarized dust-charge variations

    Science.gov (United States)

    Das, Papari; Karmakar, Pralay Kumar

    2018-01-01

    A nonextensive nonthermal magnetized viscoelastic astrofluid, compositionally containing nonthermal electrons and ions together with massive polarized dust micro-spherical grains of variable electric charge, is allowed to endure weakly nonlinear perturbation around its equilibrium. The nonextensivity originating from the large-scale non-local effects is included via the Tsallis thermo-statistical distribution laws describing the lighter species. Assuming the equilibrium as a homogeneous hydrostatic one, the dust polarization effects are incorporated via the conventional homogeneous polarization force law. The perturbed fluid model evolves as a unique conjugate pair of coupled extended Korteweg-de Vries (e-KdV) equations. A constructed numerical tapestry shows the collective excitations of a new pair of distinct classes of nonlinear mode structures in new parametric space. The first family indicates periodic electrostatic compressive eigenmodes in the form of soliton-chains. Likewise, the second one reveals gravitational rarefactive solitary patterns. Their microphysical multi-parametric dependencies of the eigen-patterns are illustratively analyzed and bolstered. The paper ends up with some promising implications and applications in the astro-cosmo-plasmic context of wave-induced accretive triggering processes responsible for gravitationally bounded (gravito-condensed) astro-structure formation, such as stellesimals, planetsimals, etc.

  9. Analysis of Surface Wave Attenuation in Mangrove Forests

    Directory of Open Access Journals (Sweden)

    Safwan Hadi

    2003-11-01

    Full Text Available This paper presents an analytical study on surface wave attenuation in mangrove forest using analytical model developed by Massel et.al. (1999. The energy dissipation in the frequency domain is determined by treating the mangrove forest as a random media with certain characteristics using the geometry of mangrove trunks and their locations. Initial nonlinear governing equations are linearized using the concept of minimalization in the stochastic sense and interactions between mangrove trunks and roots have been introduced through the modification of the drag coefficients. To see the effectiveness of the mangrove forest in attenuating wave energy the analytical model was applied to two types of mangrove forest i.e. Rhizophora and Ceriops forests. The resulting rate of wave energy attenuation depends strongly on the density of the mangrove forest, and on diameter of mangrove roots and trunks. More effective wave energy attenuation is shown by Rhizophora.

  10. Optimized nonlinear inversion of surface-wave dispersion data

    International Nuclear Information System (INIS)

    Raykova, Reneta B.

    2014-01-01

    A new code for inversion of surface wave dispersion data is developed to obtain Earth’s crustal and upper mantle velocity structure. The author developed Optimized Non–Linear Inversion ( ONLI ) software, based on Monte-Carlo search. The values of S–wave velocity VS and thickness h for a number of horizontal homogeneous layers are parameterized. Velocity of P–wave VP and density ρ of relevant layers are calculated by empirical or theoretical relations. ONLI explores parameters space in two modes, selective and full search, and the main innovation of software is evaluation of tested models. Theoretical dispersion curves are calculated if tested model satisfied specific conditions only, reducing considerably the computation time. A number of tests explored impact of parameterization and proved the ability of ONLI approach to deal successfully with non–uniqueness of inversion problem. Key words: Earth’s structure, surface–wave dispersion, non–linear inversion, software

  11. Imaging near-surface heterogeneities by natural migration of backscattered surface waves

    KAUST Repository

    AlTheyab, Abdullah

    2016-02-01

    We present a migration method that does not require a velocity model to migrate backscattered surface waves to their projected locations on the surface. This migration method, denoted as natural migration, uses recorded Green\\'s functions along the surface instead of simulated Green\\'s functions. The key assumptions are that the scattering bodies are within the depth interrogated by the surface waves, and the Green\\'s functions are recorded with dense receiver sampling along the free surface. This natural migration takes into account all orders of multiples, mode conversions and non-linear effects of surface waves in the data. The natural imaging formulae are derived for both active source and ambient-noise data, and computer simulations show that natural migration can effectively image near-surface heterogeneities with typical ambient-noise sources and geophone distributions.

  12. Visualization of surface plasmon polariton waves in two-dimensional plasmonic crystal by cathodoluminescence.

    Science.gov (United States)

    Takeuchi, K; Yamamoto, N

    2011-06-20

    A cathodoluminescence technique using a 200-keV transmission electron microscope revealed the dispersion patterns of surface plasmon polaritons (SPPs) in a two-dimensional plasmonic crystal with cylindrical hole arrays. The dispersion curves of the SPP modes involving the Γ point were derived from the angle-resolved spectrum patterns. The contrast along the dispersion curves changed with the polarization direction of the emitted light due to the property of the SPP modes. The SPP modes at the Γ point were identified from the photon maps, which mimicked standing SPP waves in a real space. The beam-scan spectral images across the plasmonic crystal edge clearly demonstrated the dependence of the SPP to light conversion efficiency on the emission angle and polarization of light.

  13. A Study of the use of a Crystal as a `Quarter-Wave Plate' to Produce High Energy Circularly Polarized Photons

    CERN Multimedia

    Kononets, I

    2002-01-01

    %NA59 %title\\\\ \\\\We present a proposal to study the use of a crystal as a `quarter-wave plate' to produce high energy circularly polarized photons, starting from unpolarized electrons. The intention is to generate linearly polarized photons by letting electrons pass a crystalline target, where they interact coherently with the lattice nuclei. The photon polarization is subsequently turned into circular polarization after passing another crystal, which acts as a `quarter-wave plate'.

  14. Optimizing surface acoustic wave sensors for trace chemical detection

    Energy Technology Data Exchange (ETDEWEB)

    Frye, G.C.; Kottenstette, R.J.; Heller, E.J. [and others

    1997-06-01

    This paper describes several recent advances for fabricating coated surface acoustic wave (SAW) sensors for applications requiring trace chemical detection. Specifically, we have demonstrated that high surface area microporous oxides can provide 100-fold improvements in SAW sensor responses compared with more typical polymeric coatings. In addition, we fabricated GaAs SAW devices with frequencies up to 500 MHz to provide greater sensitivity and an ideal substrate for integration with high-frequency electronics.

  15. Surface plasma waves over bismuth–vacuum interface

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 61; Issue 3. Surface plasma waves over bismuth–vacuum interface. Ashim P Jain J Parashar. Brief Report Volume 61 Issue ... Author Affiliations. Ashim P Jain1 J Parashar1. Department of Applied Physics, Samrat Ashok Technological Institute, Vidisha 464 001, India ...

  16. Quantitative photography of intermittency in surface wave turbulence

    International Nuclear Information System (INIS)

    Wright, W.; Budakian, R.; Putterman, S.J.

    1997-01-01

    At high amplitudes of excitation surface waves on water distribute their energy according to a Kolmogorov type of turbulent power spectrum. We have used diffusing light photography to measure the power spectrum and to quantify the presence of large structures in the turbulent state

  17. Standing surface acoustic wave (SSAW) based multichannel cell sorting.

    Science.gov (United States)

    Ding, Xiaoyun; Lin, Sz-Chin Steven; Lapsley, Michael Ian; Li, Sixing; Guo, Xiang; Chan, Chung Yu; Chiang, I-Kao; Wang, Lin; McCoy, J Philip; Huang, Tony Jun

    2012-11-07

    We introduce a novel microfluidic device for cell sorting in continuous flow using tunable standing surface acoustic waves. This method allows individual cells to be precisely directed into five different outlet channels in a single step. It is versatile, simple, label-free, non-invasive, and highly controllable.

  18. Surface wave multipath signals in near-field microwave imaging.

    Science.gov (United States)

    Meaney, Paul M; Shubitidze, Fridon; Fanning, Margaret W; Kmiec, Maciej; Epstein, Neil R; Paulsen, Keith D

    2012-01-01

    Microwave imaging techniques are prone to signal corruption from unwanted multipath signals. Near-field systems are especially vulnerable because signals can scatter and reflect from structural objects within or on the boundary of the imaging zone. These issues are further exacerbated when surface waves are generated with the potential of propagating along the transmitting and receiving antenna feed lines and other low-loss paths. In this paper, we analyze the contributions of multi-path signals arising from surface wave effects. Specifically, experiments were conducted with a near-field microwave imaging array positioned at variable heights from the floor of a coupling fluid tank. Antenna arrays with different feed line lengths in the fluid were also evaluated. The results show that surface waves corrupt the received signals over the longest transmission distances across the measurement array. However, the surface wave effects can be eliminated provided the feed line lengths are sufficiently long independently of the distance of the transmitting/receiving antenna tips from the imaging tank floor. Theoretical predictions confirm the experimental observations.

  19. Surface Wave Multipath Signals in Near-Field Microwave Imaging

    Directory of Open Access Journals (Sweden)

    Paul M. Meaney

    2012-01-01

    Full Text Available Microwave imaging techniques are prone to signal corruption from unwanted multipath signals. Near-field systems are especially vulnerable because signals can scatter and reflect from structural objects within or on the boundary of the imaging zone. These issues are further exacerbated when surface waves are generated with the potential of propagating along the transmitting and receiving antenna feed lines and other low-loss paths. In this paper, we analyze the contributions of multi-path signals arising from surface wave effects. Specifically, experiments were conducted with a near-field microwave imaging array positioned at variable heights from the floor of a coupling fluid tank. Antenna arrays with different feed line lengths in the fluid were also evaluated. The results show that surface waves corrupt the received signals over the longest transmission distances across the measurement array. However, the surface wave effects can be eliminated provided the feed line lengths are sufficiently long independently of the distance of the transmitting/receiving antenna tips from the imaging tank floor. Theoretical predictions confirm the experimental observations.

  20. Note on the surface wave due to the prescribed elevation

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 62; Issue 1. Note on the surface wave due to the prescribed elevation. Niranjan Das. Brief Reports Volume 62 Issue 1 January 2004 pp 135-142. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/pram/062/01/0135-0142 ...

  1. Surface plasma waves over bismuth–vacuum interface

    Indian Academy of Sciences (India)

    electron laser, a fast emerging device of high power coherent radiation. In §2 we derive the dispersion relation for surface plasma waves using a fluid theory. In §3 we study the SPW excitation by an electron beam. A discussion of results is given in §4. 2. SPW propagation. Consider a bismuth (Bi)–free space interface (x = 0) ...

  2. Dispersive surface waves along partially saturated porous media

    NARCIS (Netherlands)

    Chao, G.; Smeulders, D.M.J.; Van Dongen, M.E.H.

    2006-01-01

    Numerical results for the velocity and attenuation of surface wave modes in fully permeable liquid/partially saturated porous solid plane interfaces are reported in a broadband of frequencies (100?Hz–1?MHz). A modified Biot theory of poromechanics is implemented which takes into account the

  3. Field verification of ADCP surface gravity wave elevation spectra

    NARCIS (Netherlands)

    Hoitink, A.J.F.; Peters, H.C.; Schroevers, M.

    2007-01-01

    Acoustic Doppler current profilers (ADCPs) can measure orbital velocities induced by surface gravity waves, yet the ADCP estimates of these velocities are subject to a relatively high noise level. The present paper introduces a linear filtration technique to significantly reduce the influence of

  4. Tuning Acoustic Wave Properties by Mechanical Resonators on a Surface

    DEFF Research Database (Denmark)

    Dühring, Maria Bayard; Laude, Vincent; Khelif, Abdelkrim

    Vibrations generated by high aspects ratio electrodes are studied by the finite element method. It is found that the modes are combined of a surface wave and vibration in the electrodes. For increasing aspect ratio most of the mechanical energy is confined to the electrodes which act as mechanical...

  5. Surface plasma waves over bismuth–vacuum interface

    Indian Academy of Sciences (India)

    A surface plasma wave (SPW) over bismuth–vacuum interface has a signature of mass anisotropy of free electrons. For SPW propagation along the trigonal axis there is no birefringence. The frequency cutoff of SPW cutoff= p / 2 ( L + ) lies in the far infrared region and can be accessed using free electron laser.

  6. Surface plasma waves over bismuth–vacuum interface

    Indian Academy of Sciences (India)

    A surface plasma wave (SPW) over bismuth–vacuum interface has a signature of mass anisotropy of free electrons. For SPW propagation along the trigonal axis there is no birefringence. The frequency cutoff of SPW ωcutoff = ωp/. Ô. 2(εL +ε) lies in the far infrared region and can be accessed using free electron laser.

  7. Surface-wave generation by underground nuclear explosions releasing tectonic strain

    International Nuclear Information System (INIS)

    Patton, H.J.

    1980-01-01

    Seismic surface-wave generation by underground nuclear explosions releasing tectonic strain is studied through a series of synthetic radiation-pattern calculations based on the earthquake-trigger model. From amplitude and phase radiation patterns for 20-s Rayleigh waves, inferences are made about effects on surface-wave magnitude, M/sub s/, and waveform character. The focus of this study is a comparison between two mechanisms of tectonic strain release: strike-slip motion on vertical faults and thrust motion on 45 0 dipping faults. The results of our calculations show that Rayleigh-wave amplitudes of the dip-slip model at F values between 0.75 and 1.5 are significantly lower than amplitudes of the strike-slip model or of the explosion source alone. This effect translates into M/sub s/ values about 0.5 units lower than M/sub s/ of the explosion alone. Waveform polarity reversals occur in two of four azimuthal quadrants for the strike-slip model and in all azimuths of the dip-slip-thrust model for F values above about 3. A cursory examination of waveforms from presumed explosions in eastern Kazakhstan suggests that releases of tectonic strain are accompanying the detonation of many of these explosions. Qualitatively, the observations seem to favor the dip-slip-thrust model, which, in the case of a few explosions, must have F values above 3

  8. Polarity compensation mechanisms on the perovskite surface KTaO3(001)

    Science.gov (United States)

    Setvin, Martin; Reticcioli, Michele; Poelzleitner, Flora; Hulva, Jan; Schmid, Michael; Boatner, Lynn A.; Franchini, Cesare; Diebold, Ulrike

    2018-02-01

    An ionic crystal surface can be electrostatically unstable, and the surface must reconstruct in some way to avoid this “polar catastrophe.” Setvin et al. used scanning probe microscopies and density functional theory to study the changes in the polar surface of the perovskite KTaO3. They observed several structural reconstructions as the surface cleaved in vacuum was heated to higher temperatures. These ranged from surface distortions to the formation of oxygen vacancies to the development of KO and TaO2 stripes. Hydroxylation after exposure to water vapor also stabilized the surface.

  9. Investigation into Mass Loading Sensitivity of Sezawa Wave Mode-Based Surface Acoustic Wave Sensors

    Directory of Open Access Journals (Sweden)

    N. Ramakrishnan

    2013-02-01

    Full Text Available In this work mass loading sensitivity of a Sezawa wave mode based surface acoustic wave (SAW device is investigated through finite element method (FEM simulation and the prospects of these devices to function as highly sensitive SAW sensors is reported. A ZnO/Si layered SAW resonator is considered for the simulation study. Initially the occurrence of Sezawa wave mode and displacement amplitude of the Rayleigh and Sezawa wave mode is studied for lower ZnO film thickness. Further, a thin film made of an arbitrary material is coated over the ZnO surface and the resonance frequency shift caused by mass loading of the film is estimated. It was observed that Sezawa wave mode shows significant sensitivity to change in mass loading and has higher sensitivity (eight times higher than Rayleigh wave mode for the same device configuration. Further, the mass loading sensitivity was observed to be greater for a low ZnO film thickness to wavelength ratio. Accordingly, highly sensitive SAW sensors can be developed by coating a sensing medium over a layered SAW device and operating at Sezawa mode resonance frequency. The sensitivity can be increased by tuning the ZnO film thickness to wavelength ratio.

  10. Influence of tides and gravity waves on layering processes in the polar summer mesopause region

    Directory of Open Access Journals (Sweden)

    P. Hoffmann

    2008-12-01

    Full Text Available Polar Mesosphere Summer Echoes (PMSE have been studied at Andenes (69° N, 16° E, Norway, using VHF radar observations since 1994. One remarkable feature of these observations is the fact that {during 50% of the time,} the radar echoes occur in the form of two or more distinct layers. In the case of multiple PMSE layers, statistical analysis shows that the lower layer occurs at a mean height of ~83.4 km, which is almost identical to the mean height of noctilucent clouds (NLC derived from observation with the ALOMAR Rayleigh/Mie/Raman lidar at the same site. To investigate the layering processes microphysical model simulations under the influence of tidal and gravity waves were performed. In the presence of long period gravity waves, these model investigations predict an enhanced formation of multiple PMSE layer structures, where the lower layer is a consequence of the occurrence of the largest particles at the bottom of the ice cloud. This explains the coincidence of the lowermost PMSE layers and NLC. During periods with enhanced amplitudes of the semidiurnal tide, the observed NLC and PMSE show pronounced tidal structures comparable to the results of corresponding microphysical simulations. At periods with short period gravity waves there is a tendency for a decreasing occurrence of NLC and for variable weak PMSE structures.

  11. Surface polarity of beta-HMX crystal and the related adhesive forces with Estane binder.

    Science.gov (United States)

    Yang, Lu

    2008-12-02

    Here I present the results on the study of surface properties of beta-HMX crystal utilizing molecular dynamics simulations. The surface polarity of three principal crystal surfaces, (011), (010), and (110), is investigated by measuring the water contact angles. The calculated contact angles are in excellent agreement with the values measured by experiment and show that the surface polarity of three crystal surfaces are different. The free energies and forces of detaching an Estane chain (with and without surrounding nitroplasticizer molecules) from the three principal crystal surfaces are also calculated using the umbrella sampling method. I find that the force for Estane detachment increases with the increasing HMX surface polarity. In addition, my results show that the nitroplasticizer also plays an important role in the adhesion between Estane and HMX surfaces.

  12. Influences of surface and flexoelectric polarization on the effective anchoring energy in nematic liquid crystal

    International Nuclear Information System (INIS)

    Guan Rong-Hua; Ye Wen-Jiang; Xing Hong-Yu

    2015-01-01

    The physical effects on surface and flexoelectric polarization in a weak anchoring nematic liquid crystal cell are investigated systematically. We derive the analytic expressions of two effective anchoring energies for lower and upper substrates respectively as well as their effective anchoring strengths and corresponding tilt angles of effective easy direction. All of these quantities are relevant to the magnitudes of both two polarizations and the applied voltage U. Based on these expressions, the variations of effective anchoring strength and the tilt angle with the applied voltage are calculated for the fixed values of two polarizations. For an original weak anchoring hybrid aligned nematic cell, it may be equivalent to a planar cell for a small value of U and has a threshold voltage. The variation of reduced threshold voltage with reduced surface polarization strength is also calculated. The role of surface polarization is important without the adsorptive ions considered. (paper)

  13. Source effects on surface waves from Nevada Test Site explosions

    International Nuclear Information System (INIS)

    Patton, H.J.; Vergino, E.S.

    1981-11-01

    Surface waves recorded on the Lawrence Livermore National Laboratory (LLNL) digital network have been used to study five underground nuclear explosions detonated in Yucca Valley at the Nevada Test Site. The purpose of this study is to characterize the reduced displacement potential (RDP) at low frequencies and to test secondary source models of underground explosions. The observations consist of Rayleigh- and Love-wave amplitude and phase spectra in the frequency range 0.03 to 0.16 Hz. We have found that Rayleigh-wave spectral amplitudes are modeled well by a RDP with little or no overshoot for explosions detonated in alluvium and tuff. On the basis of comparisons between observed and predicted source phase, the spall closure source proposed by Viecelli does not appear to be a significant source of Rayleigh waves that reach the far field. We tested two other secondary source models, the strike-slip, tectonic strain release model proposed by Toksoez and Kehrer and the dip-slip thrust model of Masse. The surface-wave observations do not provide sufficient information to discriminate between these models at the low F-values (0.2 to 0.8) obtained for these explosions. In the case of the strike-slip model, the principal stress axes inferred from the fault slip angle and strike angle are in good agreement with the regional tectonic stress field for all but one explosion, Nessel. The results of the Nessel explosion suggest a mechanism other than tectonic strain release

  14. Calibration of the Chemcatcher passive sampler for monitoring selected polar and semi-polar pesticides in surface water

    International Nuclear Information System (INIS)

    Gunold, Roman; Schaefer, Ralf Bernhard; Paschke, Albrecht; Schueuermann, Gerrit; Liess, Matthias

    2008-01-01

    Passive sampling is a powerful method for continuous pollution monitoring, but calibration experiments are still needed to generate sampling rates in order to estimate water concentrations for polar compounds. We calibrated the Chemcatcher device with an uncovered SDB-XC Empore disk as receiving phase for 12 polar and semi-polar pesticides in aquatic environments in flow-through tank experiments at two water flow velocities (0.135 m/s and 0.4 m/s). In the 14-day period of exposure the uptake of test substances in the sampler remained linear, and all derived sampling rates R s were in the range of 0.1 to 0.5 L/day. By additionally monitoring the release of two preloaded polar pesticides from the SDB-XC disks over time, very high variation in release kinetics was found, which calls into question the applicability of performance reference compounds. Our study expands the applicability of the Chemcatcher for monitoring trace concentrations of pesticides with frequent occurrence in water. - We calibrated the Chemcatcher passive sampler for current-use polar pesticides in surface waters, allowing its application in future monitoring studies

  15. On the interaction between ocean surface waves and seamounts

    Science.gov (United States)

    Sosa, Jeison; Cavaleri, Luigi; Portilla-Yandún, Jesús

    2017-12-01

    Of the many topographic features, more specifically seamounts, that are ubiquitous in the ocean floor, we focus our attention on those with relatively shallow summits that can interact with wind-generated surface waves. Among these, especially relatively long waves crossing the oceans (swells) and stormy seas are able to affect the water column up to a considerable depth and therefore interact with these deep-sea features. We quantify this interaction through numerical experiments using a numerical wave model (SWAN), in which a simply shaped seamount is exposed to waves of different length. The results show a strong interaction that leads to significant changes in the wave field, creating wake zones and regions of large wave amplification. This is then exemplified in a practical case where we analyze the interaction of more realistic sea conditions with a very shallow rock in the Yellow Sea. Potentially important for navigation and erosion processes, mutatis mutandis, these results are also indicative of possible interactions with emerged islands and sand banks in shelf seas.

  16. The Measurement and Interpretation of Surface Wave Group Arrival Times

    Science.gov (United States)

    Masters, G.; Kane, D.; Morrow, J.; Zhou, Y.; Tromp, J.

    2005-12-01

    We have recently developed an efficient technique for measuring the relative group arrival times of surface waves by using cross-correlation and cluster analysis of waveform envelope functions. Applying the analysis to minor arc Love and Rayleigh waves in the frequency band 7 to 35 mHz for all events over magnitude 5.5 results in a dataset of over 200,000 measurements at each frequency for long period Rayleigh waves (frequency less than 25 mHz) and about 100,000 measurements at the shorter periods. Analysis of transverse components results in about half as many Love wave measurements. Simple ray theory inversions of the relative arrival times for apparent group velocity produce maps which are accurate representations of the data (often over 90% variance reduction of the relative arrival times) and which show features strongly correlated with tectonics and crustal thickness. The apparent group velocity variations can be extremely large: 30% velocity variations for 20 mHz Rayleigh waves and 40% variations for 30 mHz Rayleigh waves and can have abrupt lateral changes. This raises the concern that non-ray theory effects could be important. Indeed, a recent analysis by Dahlen and Zhou (personal communication) suggests that the group arrival times should be a functions of both the group velocity AND the phase velocity. The simplest way to test the interpretation of the measurements is to perform the analysis on synthetic seismograms computed for a realistic model of the Earth. Here, we use the SEM with a model which incorporates realistic crust and mantle structure. We are currently computing synthetics for a suite of roughly 1000 events recorded globally that extend to a period of 18 seconds. We shall present the results of applying both ray-based and finite frequency inversions to the synthetic data as well as evaluating the effects of off path propagation at short periods using surface wave ray tracing.

  17. Development of a surface isolation estimation technique suitable for application of polar orbiting satellite data

    Science.gov (United States)

    Davis, P. A.; Penn, L. M. (Principal Investigator)

    1981-01-01

    A technique is developed for the estimation of total daily insolation on the basis of data derivable from operational polar-orbiting satellites. Although surface insolation and meteorological observations are used in the development, the algorithm is constrained in application by the infrequent daytime polar-orbiter coverage.

  18. Lagrangian modelling of ocean surface waves and synthetic aperture radar wave measurements

    Energy Technology Data Exchange (ETDEWEB)

    Fouques, Sebastien

    2005-07-01

    The present thesis is concerned with the estimation of the ocean wave spectrum from synthetic aperture radar imaging and the modelling of ocean surface waves using the Lagrangian formalism. The first part gives a short overview of the theories of ocean surface waves and synthetic aperture radar (SAR) whereas the second part consists of five independent publications. The first two articles investigate the influence of the radar backscatter model on the SAR imaging of ocean waves. In Article I, Monte Carlo simulations of SAR images of the ocean surface are carried out using a nonlinear backscatter model that include both specular reflection and Bragg scattering and the results are compared to simulations from the classical Hasselmann integral transform (Hasselmann and Hasselmann, 1991). It is shown that nonlinearities in the backscatter model strongly influence the imaging of range-travelling waves and that the former can suppress the range-splitting effect (Bruning et al., 1988). Furthermore, in Article II a database of Envisat-ASAR Wave Mode products co-located with directional wave spectra from the numerical model WAM and which contains range-travelling wave cases only, is set up. The WAM spectra are used as input to several ocean-to-SAR integral transforms, with various real aperture radar (RAR) models and the obtained SAR image cross-spectra are compared to the Envisat-ASAR observations. A first result is that the use of a linear backscatter model leads to a high proportion of non-physical negative backscatter values in the RAR image, as suggested by Schulz-Stellenfleth (2001). Then, a comparison between the observed SAR cross-spectra and the ones simulated through Hasselmann's integral transform reveals that only twenty percents of the observations show a range-splitting effect as strong as in the simulations. A much better agreement is obtained when using the integral transform by Schulz-Stellenfleth (2003), which is based on a nonlinear hackscatter model

  19. Superresolution near-field imaging with surface waves

    Science.gov (United States)

    Fu, Lei; Liu, Zhaolun; Schuster, Gerard

    2018-02-01

    We present the theory for near-field superresolution imaging with surface waves and time reverse mirrors (TRMs). Theoretical formulae and numerical results show that applying the TRM operation to surface waves in an elastic half-space can achieve superresolution imaging of subwavelength scatterers if they are located less than about 1/2 of the shear wavelength from the source line. We also show that the TRM operation for a single frequency is equivalent to natural migration, which uses the recorded data to approximate the Green's functions for migration, and only costs O(N4) algebraic operations for post-stack migration compared to O(N6) operations for natural pre-stack migration. Here, we assume the sources and receivers are on an N × N grid and there are N2 trial image points on the free surface. Our theoretical predictions of superresolution are validated with tests on synthetic data. The field-data tests suggest that hidden faults at the near surface can be detected with subwavelength imaging of surface waves by using the TRM operation if they are no deeper than about 1/2 the dominant shear wavelength.

  20. Superresolution Near-field Imaging with Surface Waves

    KAUST Repository

    Fu, Lei

    2017-10-21

    We present the theory for near-field superresolution imaging with surface waves and time reverse mirrors (TRMs). Theoretical formulas and numerical results show that applying the TRM operation to surface waves in an elastic half-space can achieve superresolution imaging of subwavelength scatterers if they are located less than about 1/2 of the shear wavelength from the source line. We also show that the TRM operation for a single frequency is equivalent to natural migration, which uses the recorded data to approximate the Green’s functions for migration, and only costs O(N4) algebraic operations for poststack migration compared to O(N6) operations for natural prestack migration. Here, we assume the sources and receivers are on an N × N grid and there are N2 trial image points on the free surface. Our theoretical predictions of superresolution are validated with tests on synthetic data. The field-data tests suggest that hidden faults at the near surface can be detected with subwavelength imaging of surface waves by using the TRM operation if they are no deeper than about 1/2 the dominant shear wavelength.

  1. Photon management assisted by surface waves on photonic crystals

    CERN Document Server

    Angelini, Angelo

    2017-01-01

    This book illustrates original pathways to manipulate light at the nanoscale by means of surface electromagnetic waves (here, Bloch surface waves, BSWs) on planar dielectric multilayers, also known as one-dimensional photonic crystals. This approach is particularly valuable as it represents an effective alternative to the widely exploited surface plasmon paradigm. After a brief overview on the fundamentals of BSWs, several significant applications of BSW-sustaining structures are described. Particular consideration is given to the propagation, guiding, and diffraction of BSW-coupled radiation. Further, the interaction of organic emitters with BSWs on planar and corrugated multilayers is investigated, including fluorescence beaming in free space. To provide greater insight into sensing applications, an illustrative example of fluorescent microarray-based detection is presented. The book is intended for scientists and researchers working on photon management opportunities in fields such as biosensing, optical c...

  2. Nonlinear Waves and Solitons on Contours and Closed Surfaces

    CERN Document Server

    Ludu, Andrei

    2007-01-01

    The present volume is an introduction to nonlinear waves and soliton theory in the special environment of compact spaces such a closed curves and surfaces and other domain contours. It assumes familiarity with basic soliton theory and nonlinear dynamical systems. The first part of the book introduces the mathematical concept required for treating the manifolds considered. Emphasis on the relevant notions from topology and differential geometry. An introduction to the theory of motion of curves and surfaces - as part of the emerging field of contour dynamics - is given. The second and third parts discuss the modeling of various physical solitons on compact systems, such as filaments, loops and drops made of almost incompressible materials thereby intersecting with a large number of physical disciplines from hydrodynamics to compact object astrophysics. Nonlinear Waves and Solitons on Contours and Closed Surfaces provides graduate students and researchers in mathematics, physics and engineering with a ready tut...

  3. Imaging near-surface heterogeneities by natural migration of surface waves

    KAUST Repository

    Liu, Zhaolun

    2016-09-06

    We demonstrate that near-surface heterogeneities can be imaged by natural migration of backscattered surface waves in common shot gathers. No velocity model is required because the data are migrated onto surface points with the virtual Green\\'s functions computed from the shot gathers. Migrating shot gathers recorded by 2D and 3D land surveys validates the effectiveness of detecting nearsurface heterogeneities by natural migration. The implication is that more accurate hazard maps can be created by migrating surface waves in land surveys.

  4. Phase mixing and surface wave decay in an inhomogeneous plasma

    International Nuclear Information System (INIS)

    Cally, P.S.; Sedlacek, Z.

    1992-02-01

    The decay rate is calculated of an Alfven or plasma surface wave propagating along an inhomogeneous layer of plasma. The inhomogeneous profile is thin and odd, but otherwise arbitrary. The wave's decay rate is determined using two fundamentally different methods, the integral-differential equation approach of Sedlacek and the Fourier expansion technique of Cally, and found by both to depend only on the slope of the Alfven or plasma frequency profile at the r esonant point , and not on other details of its shape. The result is verified numerically. This problem represents a good example with which to compare and contrast the two methods. (author) 3 figs., 7 refs

  5. Surface wave phase velocities between Bulgaria and the Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Gaždová, Renata; Kolínský, Petr; Popova, I.; Dimitrova, L.

    2011-01-01

    Roč. 18, č. 2 (2011), s. 16-23 ISSN 1803-1447. [OVA´11 – New Knowledge and Measurements in Seismology, Engineering Geophysics and Geotechnics. Ostrava, 12.04.2011-14.04.2011] R&D Projects: GA ČR GA205/09/1244 Institutional research plan: CEZ:AV0Z30460519 Keywords : surface waves * phase velocity * shear wave velocity Subject RIV: DC - Siesmology, Volcanology, Earth Structure http://www.caag.cz/egrse/2011-2/03%20gazdova_ova.pdf

  6. Sensitivity of Rayleigh wave ellipticity and implications for surface wave inversion

    Science.gov (United States)

    Cercato, Michele

    2018-04-01

    The use of Rayleigh wave ellipticity has gained increasing popularity in recent years for investigating earth structures, especially for near-surface soil characterization. In spite of its widespread application, the sensitivity of the ellipticity function to the soil structure has been rarely explored in a comprehensive and systematic manner. To this end, a new analytical method is presented for computing the sensitivity of Rayleigh wave ellipticity with respect to the structural parameters of a layered elastic half-space. This method takes advantage of the minor decomposition of the surface wave eigenproblem and is numerically stable at high frequency. This numerical procedure allowed to retrieve the sensitivity for typical near surface and crustal geological scenarios, pointing out the key parameters for ellipticity interpretation under different circumstances. On this basis, a thorough analysis is performed to assess how ellipticity data can efficiently complement surface wave dispersion information in a joint inversion algorithm. The results of synthetic and real-world examples are illustrated to analyse quantitatively the diagnostic potential of the ellipticity data with respect to the soil structure, focusing on the possible sources of misinterpretation in data inversion.

  7. A New Method for Simulating Power Flow Density Focused by a Silicon Lens Antenna Irradiated with Linearly Polarized THz Wave

    Directory of Open Access Journals (Sweden)

    Catur Apriono

    2015-08-01

    Full Text Available A terahertz system uses dielectric lens antennas for focusing and collimating beams of terahertz wave radiation. Linearly polarized terahertz wave radiation has been widely applied in the terahertz system. Therefore, an accurate method for analyzing the power flow density in the dielectric lens antenna irradiated with the linearly polarized terahertz wave radiation is important to design the terahertz systems. In optics, ray-tracing method has been used to calculate the power flow density by a number density of rays. In this study, we propose a method of ray-tracing combined with Fresnel’s transmission, including transmittance and polarization of the terahertz wave radiation to calculate power flow density in a Silicon lens antenna. We compare power flow density calculated by the proposed method with the regular ray-tracing method. When the Silicon lens antenna is irradiated with linearly polarized terahertz wave radiation, the proposed method calculates the power flow density more accurately than the regular ray-tracing.

  8. Human responses to wave slamming vibration on a polar supply and research vessel.

    Science.gov (United States)

    Omer, H; Bekker, A

    2018-02-01

    A polar supply and research vessel is pre-disposed to wave slamming which has caused complaints among crew and researchers regarding interference with sleep, equipment use and research activities. The present work undertook to survey passenger claims of sleep interference, disturbed motor tasks and equipment damage as a result of wave slamming during normal operations of this vessel. The hypothesis was investigated that whole-body vibration metrics from ISO 2631-1 are potentially suitable for the prediction of human slamming complaints. Full-scale acceleration measurements were performed and wave slamming events were subsequently identified from the human weighted acceleration time histories. A daily diary survey was also conducted to gather the human response. The vibration caused by wave slamming was found to be strongly correlated with sleep disturbances and activity interference. Sleep and equipment use were found to be the most affected parameters by slamming. Daily vibration dose values were determined by accumulating the vibration as a result of slamming over 24 h periods. This metric accounted for increased magnitudes and frequency of slamming incidents and proved to be the best metric to represent human responses to slamming vibration. The greatest percentage of activities affected by slamming related to sleep regardless of daily cumulative VDV magnitude. More than 50% of the recorded responses related to sleep when the daily cumulative VDV ranged between 8.0 m/s 1.75 -10.0 m/s 1.75 . The peak vertical vibration levels recorded on the vessel reach magnitudes which are associated with sleep disturbance in environments where acoustic noise is present. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Surface waves guided by metamaterials with rotational disorder

    Science.gov (United States)

    Gric, T.; Hess, O.

    2018-02-01

    The analytical analysis of the metamaterial boundary with the rotational disorder reveals both bound and leaky surface plasmon (SP) modes. The dispersion relations of SPs propagating on a surface of these metamaterials are presented along with the propagation lengths. The rigorous modeling and analysis of surface waves at the boundary of two metamaterials possessing rotational disorder are presented. Dispersion properties of two different metamaterial boundaries have been investigated. The results show that the boundary of the metamaterials having different dielectrics employed allows for the presence of the particular modes crossing the light line with the significant portion at lower frequencies lying above the free space light line.

  10. Surface impedance of travelling--Wave antenna in magnetized plasma

    International Nuclear Information System (INIS)

    Denisenko, I.B.; Ostrikov, K.N.

    1993-01-01

    Wave properties of metal antennas immersed in a magnetoactive plasma are intensively studied nowadays with the objects of radio communications in ionosphere, plasma heating, gas discharge technique. Many papers are devoted to studies of sheath waves (SW) in magnetoplasma, which are surface by nature and propagate along the metal-low-density sheath-plasma waveguide structure. The results of these papers suggest that the existence of these waves makes significant contribution in antenna impedance. Note that the impedance measurement is one of possible ways of experimental surface waves characterization. In the present report the surface impedance of travelling SW antenna immersed in magnetoactive plasma is calculated and its dependence on the waveguide structure parameters such as plasma density, external magnetic field H 0 and electrons collisional frequency values, sheath region width, conductivity of metal surface is studied. The calculations have been carried out in a quasiplane approximation, when antenna radius greatly exceeds the SW skin depth. Note that the finite conductivity of metal is necessary to be taken into account to provide a finite surface impedance value. The surface impedance is calculated in two cases, namely when SW propagate along (Ζ parallel ) and across (Ζ perpendicular ) the external magnetic field. The relation between the values Ζ parallel and Ζ perpendicular is obtained. This relation shows that the values Ζ parallel and Ζ parallel may satisfy both inequalities Ζ parallel much-gt Ζ perpendicular and Ζ perpendicular approx-gt Ζ perpendicular dependent on the parameters of the structure. The comparison of dispersion properties of the SW propagating along Η 0 with the experimental results is carried out. The results are shown to satisfactorily correspond to the experimental results

  11. Artificial upwelling using the energy of surface waves

    Science.gov (United States)

    Soloviev, A.

    2016-02-01

    The ocean is an important component of climate and climate change, since the heat capacity of a few meters of the upper ocean is equivalent to the heat capacity of the entire atmosphere. (Solar radiation and IR balance in the atmosphere are of course major factors as well.) Artificial upwelling devices using the energy of surface waves, similar to those developed by Vershinskiy, Pshenichnyy, and Soloviev (1987), can bring cold water from below the thermocline to the sea surface. Their wave-inertia pump consisted of a vertical tube, a valve, and a buoy to keep the device afloat. The device operated by using energy of surface waves to create an upward flow of water in the tube. An outlet valve at the top of the unit synchronized the operation of the device with surface waves and prevented back-splashing. A single device with a 100 m long and 1.2 m diameter tube is able to produce up to 1 m3s-1 flow of deep water to the surface. With a 10oC temperature difference over 100 m depth, the negative heat supply rate to the sea surface is 42 MW, which is equivalent to a 42 Wm-2 heat flux, if distributed over 1 km2 area. Such flux is comparable to the average net air-sea flux. This type of artificial upwelling can cool down the sea surface, modify climate on a regional scale and possibly help mitigate hurricanes. The cold water brought from the deep layer, however, has a larger density than the surface water and therefore has a tendency to sink back down. In this work, the efficiency of wave-inertia pumps has been estimated for different environmental conditions using a computational fluid dynamics model. The cooled near-surface layer of the ocean will be getting more heat from the sun, which is a detrimental consequence. Cloud seeding can help to mitigate this extra warming. A synergistic approach to climate engineering can thus reduce detriments and increase potential benefits of this system to society.

  12. Spin Polarization Inversion at Benzene-Absorbed Fe4N Surface

    KAUST Repository

    Zhang, Qian

    2015-05-27

    We report a first-principle study on electronic structure and simulation of the spin-polarized scanning tunneling microscopy graphic of a benzene/Fe4N interface. Fe4N is a compound ferromagnet suitable for many spintronic applications. We found that, depending on the particular termination schemes and interface configurations, the spin polarization on the benzene surface shows a rich variety of properties ranging from cosine-type oscillation to polarization inversion. Spin-polarization inversion above benzene is resulting from the hybridizations between C pz and the out-of-plane d orbitals of Fe atom.

  13. Polarization study of non-resonant X-ray magnetic scattering from spin-density-wave modulation in chromium

    International Nuclear Information System (INIS)

    Ohsumi, Hiroyuki; Takata, Masaki

    2007-01-01

    We present a polarization study of non-resonant X-ray magnetic scattering in pure chromium. Satellite reflections are observed at +/-Q and +/-2Q, where Q is the modulation wave vector of an itinerant spin-density-wave. The first and second harmonics are confirmed to have magnetic and charge origin, respectively, by means of polarimetry without using an analyzer crystal. This alternative technique eliminates intolerable intensity loss at an analyzer by utilizing the sample crystal also as an analyzer crystal

  14. Analysis of the Influence of a Uniform Hydrometeorological Formation on the Polarization Characteristics of an Electromagnetic Wave

    Science.gov (United States)

    Masalov, E. V.; Krivin, N. N.; Eshchenko, S. Yu.

    2018-01-01

    The influence of a homogeneous medium filled with water droplets on the polarization structure of electromagnetic waves propagating in it, emitted in series with horizontal and circular (e.g., right-handed) polarization, is considered. An approach is proposed for estimating the influence of the resulting transformation of the polarization structure on the magnitude of the modified radar reflectivity, based on the use of the functional dependence of the components of the Jones vector on the angle of ellipticity and the tilt angle of the polarization ellipse. A distinguishing feature of the proposed approach consists in the relationships calculated using it for determining the modified radar reflectivity, obtained for the case of backscattering by the medium, where the orientation of the polarization basis of the medium is different from that of the measurement basis. Estimates of the modified radar reflectivity have been obtained, allowing one to determine regions with elevated values of this parameter.

  15. Linearly Polarized Dual-Wavelength Vertical-External-Cavity Surface-Emitting Laser (Postprint)

    National Research Council Canada - National Science Library

    Fan, Li; Fallahi, Mahmoud; Hader, Joerg; Zakharian, Aramais R; Moloney, Jerome V; Stolz, Wolfgang; Koch, Stephan W; Bedford, Robert; Murray, James T

    2007-01-01

    The authors demonstrate the multiwatt linearly polarized dual-wavelength operation in an optically pumped vertical-external-cavity surface-emitting laser by means of an intracavity tilted Fabry-Perot...

  16. Comparative study of binding constants from Love wave surface acoustic wave and surface plasmon resonance biosensors using kinetic analysis.

    Science.gov (United States)

    Lee, Sangdae; Kim, Yong-Il; Kim, Ki-Bok

    2013-11-01

    Biosensors are used in a variety of fields for early diagnosis of diseases, measurement of toxic contaminants, quick detection of pathogens, and separation of specific proteins or DNA. In this study, we fabricated and evaluated the capability of a high sensitivity Love wave surface acoustic wave (SAW) biosensor. The experimental setup was composed of the fabricated 155-MHz Love wave SAW biosensor, a signal measurement system, a liquid flow system, and a temperature-control system. Subsequently, we measured the lower limit of detection (LOD) of the 155-MHz Love wave SAW biosensor, and calculated the association and dissociation constants between protein G and anti-mouse IgG using kinetic analysis. We compared these results with those obtained using a commercial surface plasmon resonance (SPR) biosensor. We found that the LOD of the SAW biosensor for anti-mouse IgG and mouse IgG was 0.5 and 1 microg/ml, respectively, and the resultant equilibrium association and dissociation constants were similar to the corresponding values obtaining using the commercial SPR biosensor. Thus, we conclude that the fabricated 155-MHz Love wave SAW biosensor exhibited the high sensitivity of the commercial SPR biosensor and was able to analyze the binding properties of the ligand and receptor by kinetic analysis similarly to the commercial SPR biosensor.

  17. Waves on the surface of the Orion molecular cloud.

    Science.gov (United States)

    Berné, Olivier; Marcelino, Núria; Cernicharo, José

    2010-08-19

    Massive stars influence their parental molecular cloud, and it has long been suspected that the development of hydrodynamical instabilities can compress or fragment the cloud. Identifying such instabilities has proved difficult. It has been suggested that elongated structures (such as the 'pillars of creation') and other shapes arise because of instabilities, but alternative explanations are available. One key signature of an instability is a wave-like structure in the gas, which has hitherto not been seen. Here we report the presence of 'waves' at the surface of the Orion molecular cloud near where massive stars are forming. The waves seem to be a Kelvin-Helmholtz instability that arises during the expansion of the nebula as gas heated and ionized by massive stars is blown over pre-existing molecular gas.

  18. New pure shear elastic surface waves in magneto-electro-elastic half-space

    OpenAIRE

    Melkumyan, Arman

    2006-01-01

    Pure shear surface waves guided by the free surface of a magneto-electro-elastic material are investigated. Three surface waves are obtained for various magneto-electrical conditions on the free surface of the magneto-electro-elastic half-space. The velocities of propagation and the existence conditions for each of these waves are obtained in explicit exact form.

  19. Stabilization mechanism for the polar ZnO(0001̅)-O surface

    DEFF Research Database (Denmark)

    Wahl, Roman; Lauritsen, Jeppe Vang; Besenbacher, Flemming

    2013-01-01

    When wurtzite ZnO is sliced perpendicular to the (0001) axis, two different polar surfaces, the (0001)-Zn and (0001̅ )-O terminated surfaces, are formed. In a simple ionic picture, both surfaces are electrostatically unstable due to a diverging electrostatic energy. Although the ionic picture...

  20. Cluster observations of surface waves on the dawn flank magnetopause

    Directory of Open Access Journals (Sweden)

    C. J. Owen

    2004-03-01

    Full Text Available On 14 June 2001 the four Cluster spacecraft recorded multiple encounters of the dawn-side flank magnetopause. The characteristics of the observed electron populations varied between a cold, dense magnetosheath population and warmer, more rarified boundary layer population on a quasi-periodic basis. The demarcation between these two populations can be readily identified by gradients in the scalar temperature of the electrons. An analysis of the differences in the observed timings of the boundary at each spacecraft indicates that these magnetopause crossings are consistent with a surface wave moving across the flank magnetopause. When compared to the orientation of the magnetopause expected from models, we find that the leading edges of these waves are approximately 45° steeper than the trailing edges, consistent with the Kelvin-Helmholtz (KH driving mechanism. A stability analysis of this interval suggests that the magnetopause is marginally stable to this mechanism during this event. Periods in which the analysis predicts that the magnetopause is unstable correspond to observations of greater wave steepening. Analysis of the pulses suggests that the waves have an average wavelength of approximately 3.4 RE and move at an average speed of ~65km s-1 in an anti-sunward and northward direction, despite the spacecraft location somewhat south of the GSE Z=0 plane. This wave propagation direction lies close to perpendicular to the average magnetic field direction in the external magnetosheath, suggesting that these waves may preferentially propagate in the direction that requires no bending of these external field lines

    Key words. Magnetospheric physics (magnetospheric configuration and dynamics; MHD waves and unstabilities; solar wind-magnetosphere interactions

  1. Wave-equation dispersion inversion of surface waves recorded on irregular topography

    KAUST Repository

    Li, Jing

    2017-08-17

    Significant topographic variations will strongly influence the amplitudes and phases of propagating surface waves. Such effects should be taken into account, otherwise the S-velocity model inverted from the Rayleigh dispersion curves will contain significant inaccuracies. We now show that the recently developed wave-equation dispersion inversion (WD) method naturally takes into account the effects of topography to give accurate S-velocity tomograms. Application of topographic WD to demonstrates that WD can accurately invert dispersion curves from seismic data recorded over variable topography. We also apply this method to field data recorded on the crest of mountainous terrain and find with higher resolution than the standard WD tomogram.

  2. Characterization of microchannel anechoic corners formed by surface acoustic waves

    Science.gov (United States)

    Destgeer, Ghulam; Alam, Ashar; Ahmed, Husnain; Park, Jinsoo; Jung, Jin Ho; Park, Kwangseok; Sung, Hyung Jin

    2018-02-01

    Surface acoustic waves (SAWs) generated in a piezoelectric substrate couple with a liquid according to Snell's law such that a compressional acoustic wave propagates obliquely at a Rayleigh angle ( θ t) inside the microchannel to form a region devoid of a direct acoustic field, which is termed a microchannel anechoic corner (MAC). In the present study, we used microchannels with various heights and widths to characterize the width of the MAC region formed by a single travelling SAW. The attenuation of high-frequency SAWs produced a strong acoustic streaming flow that moved the particles in and out of the MAC region, whereas reflections of the acoustic waves within the microchannel resulted in standing acoustic waves that trapped particles at acoustic pressure nodes located within or outside of the MAC region. A range of actuation frequencies and particle diameters were used to investigate the effects of the acoustic streaming flow and the direct acoustic radiation forces by the travelling as well as standing waves on the particle motion with respect to the MAC region. The width of the MAC ( w c), measured experimentally by tracing the particles, increased with the height of the microchannel ( h m) according to a simple trigonometric equation w c = h m × tan ( θ t ).

  3. Assessment of soil compaction properties based on surface wave techniques

    Science.gov (United States)

    Jihan Syamimi Jafri, Nur; Rahim, Mohd Asri Ab; Zahid, Mohd Zulham Affandi Mohd; Faizah Bawadi, Nor; Munsif Ahmad, Muhammad; Faizal Mansor, Ahmad; Omar, Wan Mohd Sabki Wan

    2018-03-01

    Soil compaction plays an important role in every construction activities to reduce risks of any damage. Traditionally, methods of assessing compaction include field tests and invasive penetration tests for compacted areas have great limitations, which caused time-consuming in evaluating large areas. Thus, this study proposed the possibility of using non-invasive surface wave method like Multi-channel Analysis of Surface Wave (MASW) as a useful tool for assessing soil compaction. The aim of this study was to determine the shear wave velocity profiles and field density of compacted soils under varying compaction efforts by using MASW method. Pre and post compaction of MASW survey were conducted at Pauh Campus, UniMAP after applying rolling compaction with variation of passes (2, 6 and 10). Each seismic data was recorded by GEODE seismograph. Sand replacement test was conducted for each survey line to obtain the field density data. All seismic data were processed using SeisImager/SW software. The results show the shear wave velocity profiles increase with the number of passes from 0 to 6 passes, but decrease after 10 passes. This method could attract the interest of geotechnical community, as it can be an alternative tool to the standard test for assessing of soil compaction in the field operation.

  4. Bending and splitting of spoof surface acoustic waves through structured rigid surface

    Science.gov (United States)

    Xie, Sujun; Ouyang, Shiliang; He, Zhaojian; Wang, Xiaoyun; Deng, Ke; Zhao, Heping

    2018-03-01

    In this paper, we demonstrated that a 90°-bended imaging of spoof surface acoustic waves with subwavelength resolution of 0.316λ can be realized by a 45° prism-shaped surface phononic crystal (SPC), which is composed of borehole arrays with square lattice in a rigid plate. Furthermore, by combining two identical prism-shaped phononic crystal to form an interface (to form a line-defect), the excited spoof surface acoustic waves can be split into bended and transmitted parts. The power ratio between the bended and transmitted surface waves can be tuned arbitrarily by adjusting the defect size. This acoustic system is believed to have potential applications in various multifunctional acoustic solutions integrated by different acoustical devices.

  5. Circuit Design of Surface Acoustic Wave Based Micro Force Sensor

    OpenAIRE

    Yuanyuan Li; Wenke Lu; Changchun Zhu; Qinghong Liu; Haoxin Zhang; Chenchao Tang

    2014-01-01

    Pressure sensors are commonly used in industrial production and mechanical system. However, resistance strain, piezoresistive sensor, and ceramic capacitive pressure sensors possess limitations, especially in micro force measurement. A surface acoustic wave (SAW) based micro force sensor is designed in this paper, which is based on the theories of wavelet transform, SAW detection, and pierce oscillator circuits. Using lithium niobate as the basal material, a mathematical model is established ...

  6. Improved Modeling and Prediction of Surface Wave Amplitudes

    Science.gov (United States)

    2017-05-31

    data does not license the holder or any other person or corporation; or convey any rights or permission to manufacture, use, or sell any patented... advantages of the membrane surface wave technique are that 1) it is orders of magnitude faster than 3-dimensional finite-difference; and 2) it...0.5 km depth. Although the CMT sources should more accurately reproduce the observed signals from each event, they have two disadvantages : 1) in the

  7. Conoscopic interferometry of surface-acoustic-wave substrate crystals.

    Science.gov (United States)

    Ayräs, P H; Friberg, A T; Kaivola, M A; Salomaa, M M

    1999-09-01

    Conoscopic interferometry is applied for determining the crystal orientation of lithium niobate and other commonly employed substrate wafers for integrated-optic and surface-acoustic-wave devices. The method is particularly applicable for detecting the orientation of the optic axes of the strongly birefringent niobate but is less sensitive for lithium tantalate or quartz. Conoscopic interference is a low-cost and easy-to-use method that is especially suitable for laboratory usage.

  8. Surface wave propagation in a fluid-saturated incompressible ...

    Indian Academy of Sciences (India)

    Surface wave propagation in a fluid-saturated incompressible porous medium157 where ˙xi˙xi˙xi and ¨xi¨xi¨xi(i = F,S) denote the velocities and accelerations of solid and fluid phases respectively and p is the effective pore pressure of the incompressible pore fluid. ρS and ρF are the densities of the solid and fluid phases ...

  9. Monolithic GaAs surface acoustic wave chemical microsensor array

    Energy Technology Data Exchange (ETDEWEB)

    HIETALA,VINCENT M.; CASALNUOVO,STEPHEN A.; HELLER,EDWIN J.; WENDT,JOEL R.; FRYE-MASON,GREGORY CHARLES; BACA,ALBERT G.

    2000-03-09

    A four-channel surface acoustic wave (SAW) chemical sensor array with associated RF electronics is monolithically integrated onto one GaAs IC. The sensor operates at 690 MHz from an on-chip SAW based oscillator and provides simple DC voltage outputs by using integrated phase detectors. This sensor array represents a significant advance in microsensor technology offering miniaturization, increased chemical selectivity, simplified system assembly, improved sensitivity, and inherent temperature compensation.

  10. Surface acoustic wave probe implant for predicting epileptic seizures

    Science.gov (United States)

    Gopalsami, Nachappa [Naperville, IL; Kulikov, Stanislav [Sarov, RU; Osorio, Ivan [Leawood, KS; Raptis, Apostolos C [Downers Grove, IL

    2012-04-24

    A system and method for predicting and avoiding a seizure in a patient. The system and method includes use of an implanted surface acoustic wave probe and coupled RF antenna to monitor temperature of the patient's brain, critical changes in the temperature characteristic of a precursor to the seizure. The system can activate an implanted cooling unit which can avoid or minimize a seizure in the patient.

  11. Spin-wave dynamics in Invar Fe65Ni35 studied by small-angle polarized neutron scattering

    NARCIS (Netherlands)

    Brück, E.H.; Grigoriev, S.V.; Deriglazov, V.V.; Okorokov, A.I.; Dijk van, N.H.; Klaasse, J.C.P.

    2002-01-01

    Abstract. Spin dynamics in Fe65Ni35 Invar alloy has been studied by left-right asymmetry of small-angle polarized neutron scattering below TC=485 K in external magnetic fields of H=0.05-0.25 T inclined relative to the incident beam. The spin-wave stiffness D and the damping & were obtained by

  12. Fabrication of Proton-Exchange Waveguide Using Stoichiometric LiTaO3 for Guided Wave Electrooptic Modulators with Polarization-Reversed Structure

    Directory of Open Access Journals (Sweden)

    Hiroshi Murata

    2008-01-01

    Full Text Available Optical waveguides were fabricated on z-cut stoichiometric LiTaO3 (SLT by using the proton-exchange method. The surface index change for the extraordinary ray on the SLT substrate resulting from the proton exchange was 0.017, which coincided well with congruent LiTaO3 substrates. The proton exchange coefficient in the SLT was 0.25×10−12 cm2/s. The application of the SLT waveguide to a quasi-velocity-matched travelling-wave electrooptic modulator with periodically polarization-reversed structure is also reported.

  13. Multi-channel Analysis of Passive Surface Waves (MAPS)

    Science.gov (United States)

    Xia, J.; Cheng, F. Mr; Xu, Z.; Wang, L.; Shen, C.; Liu, R.; Pan, Y.; Mi, B.; Hu, Y.

    2017-12-01

    Urbanization is an inevitable trend in modernization of human society. In the end of 2013 the Chinese Central Government launched a national urbanization plan—"Three 100 Million People", which aggressively and steadily pushes forward urbanization. Based on the plan, by 2020, approximately 100 million people from rural areas will permanently settle in towns, dwelling conditions of about 100 million people in towns and villages will be improved, and about 100 million people in the central and western China will permanently settle in towns. China's urbanization process will run at the highest speed in the urbanization history of China. Environmentally friendly, non-destructive and non-invasive geophysical assessment method has played an important role in the urbanization process in China. Because human noise and electromagnetic field due to industrial life, geophysical methods already used in urban environments (gravity, magnetics, electricity, seismic) face great challenges. But humanity activity provides an effective source of passive seismic methods. Claerbout pointed out that wavefileds that are received at one point with excitation at the other point can be reconstructed by calculating the cross-correlation of noise records at two surface points. Based on this idea (cross-correlation of two noise records) and the virtual source method, we proposed Multi-channel Analysis of Passive Surface Waves (MAPS). MAPS mainly uses traffic noise recorded with a linear receiver array. Because Multi-channel Analysis of Surface Waves can produces a shear (S) wave velocity model with high resolution in shallow part of the model, MPAS combines acquisition and processing of active source and passive source data in a same flow, which does not require to distinguish them. MAPS is also of ability of real-time quality control of noise recording that is important for near-surface applications in urban environment. The numerical and real-world examples demonstrated that MAPS can be

  14. Ultrasonic phased array with surface acoustic wave for imaging cracks

    Directory of Open Access Journals (Sweden)

    Yoshikazu Ohara

    2017-06-01

    Full Text Available To accurately measure crack lengths, we developed a real-time surface imaging method (SAW PA combining an ultrasonic phased array (PA with a surface acoustic wave (SAW. SAW PA using a Rayleigh wave with a high sensitivity to surface defects was implemented for contact testing using a wedge with the third critical angle that allows the Rayleigh wave to be generated. Here, to realize high sensitivity imaging, SAW PA was optimized in terms of the wedge and the imaging area. The improved SAW PA was experimentally demonstrated using a fatigue crack specimen made of an aluminum alloy. For further verification in more realistic specimens, SAW PA was applied to stainless-steel specimens with a fatigue crack and stress corrosion cracks (SCCs. The fatigue crack was visualized with a high signal-to-noise ratio (SNR and its length was measured with a high accuracy of better than 1 mm. The SCCs generated in the heat-affected zones (HAZs of a weld were successfully visualized with a satisfactory SNR, although responses at coarse grains appeared throughout the imaging area. The SCC lengths were accurately measured. The imaging results also precisely showed complicated distributions of SCCs, which were in excellent agreement with the optically observed distributions.

  15. Numerical study of surface water waves generated by mass movement

    Energy Technology Data Exchange (ETDEWEB)

    Ghozlani, Belgacem; Hafsia, Zouhaier; Maalel, Khlifa, E-mail: ghozlanib@yahoo.fr [Ecole Nationale d' Ingenieurs de Tunis, Laboratoire de Modelisation en ' Hydraulique et Environnement, BP 37, Le Belvedere, 1002 Tunis (Tunisia)

    2013-10-01

    In this paper waves generated by two-dimensional mass movement are simulated using a numerical model based on the full hydrodynamic coupling between rigid-body motion and ambient fluid flow. This approach has the capability to represent the dynamics of the moving rigid body, which avoids the need to prescribe the body velocity based on the data measurements. This model is implemented in the CFX code and uses the Reynolds average Navier-Stokes equations solver coupled to the recently developed immersed solid technique. The latter technique allows us to follow implicitly the motion of the solid block based on the rigid body solver. The volume-of-fluid method is used to track the free surface locations. The accuracy of the present model is firstly examined against the simple physical case of a freely falling rigid body into water reproducing Scott Russell's solitary waves. More complex and realistic simulations of aerial and submarine mass-movement, simulated by a rigid wedge sliding into water along a 45 Degree-Sign slope, are then performed. Simulated results of the aerial mass movement show the complex flow patterns in terms of the velocity fields and free surface profiles. Results are in good agreement with the available experimental data. In addition, the physical processes associated with the generation of water wave by two-dimensional submarine mass-movement are explored. The effects of the initial submergence and specific gravity on the slide mass kinematics and maximum wave amplitude are investigated. The terminal velocity and initial acceleration of the slide mass are well predicted when compared to experimental results. It is found that the initial submergence did not have a significant effect on the initial acceleration of the slide block centre of mass. However, it depends nonlinearly on the specific gravity. The maximum wave amplitude and the time at which it occurred are also presented as a function of the initial submergence and specific gravity

  16. Surface acoustic wave micromotor with arbitrary axis rotational capability

    Science.gov (United States)

    Tjeung, Ricky T.; Hughes, Mark S.; Yeo, Leslie Y.; Friend, James R.

    2011-11-01

    A surface acoustic wave (SAW) actuated rotary motor is reported here, consisting of a millimeter-sized spherical metal rotor placed on the surface of a lead zirconate titanate piezoelectric substrate upon which the SAW is made to propagate. At the design frequency of 3.2 MHz and with a fixed preload of 41.1 μN, the maximum rotational speed and torque achieved were approximately 1900 rpm and 5.37 μN-mm, respectively, producing a maximum output power of 1.19 μW. The surface vibrations were visualized using laser Doppler vibrometry and indicate that the rotational motion arises due to retrograde elliptical motions of the piezoelectric surface elements. Rotation about orthogonal axes in the plane of the substrate has been obtained by using orthogonally placed interdigital electrodes on the substrate to generate SAW impinging on the rotor, offering a means to generate rotation about an arbitrary axis in the plane of the substrate.

  17. Design and performance of dual-polarization lumped-element kinetic inductance detectors for millimeter-wave polarimetry

    Science.gov (United States)

    McCarrick, H.; Jones, G.; Johnson, B. R.; Abitbol, M. H.; Ade, P. A. R.; Bryan, S.; Day, P.; Essinger-Hileman, T.; Flanigan, D.; Leduc, H. G.; Limon, M.; Mauskopf, P.; Miller, A.; Tucker, C.

    2018-02-01

    Aims: Lumped-element kinetic inductance detectors (LEKIDs) are an attractive technology for millimeter-wave observations that require large arrays of extremely low-noise detectors. We designed, fabricated and characterized 64-element (128 LEKID) arrays of horn-coupled, dual-polarization LEKIDs optimized for ground-based CMB polarimetry. Our devices are sensitive to two orthogonal polarizations in a single spectral band centered on 150 GHz with Δν/ν = 0.2. The 65 × 65 mm square arrays are designed to be tiled into the focal plane of an optical system. We demonstrate the viability of these dual-polarization LEKIDs with laboratory measurements. Methods: The LEKID modules are tested with an FPGA-based readout system in a sub-kelvin cryostat that uses a two-stage adiabatic demagnetization refrigerator. The devices are characterized using a blackbody and a millimeter-wave source. The polarization properties are measured with a cryogenic stepped half-wave plate. We measure the resonator parameters and the detector sensitivity, noise spectrum, dynamic range, and polarization response. Results: The resonators have internal quality factors approaching 1 × 106. The detectors have uniform response between orthogonal polarizations and a large dynamic range. The detectors are photon-noise limited above 1 pW of absorbed power. The noise-equivalent temperatures under a 3.4 K blackbody load are 80%. The entire array is multiplexed on a single readout line, demonstrating a multiplexing factor of 128. The array and readout meet the requirements for 4 arrays to be read out simultaneously for a multiplexing factor of 512. Conclusions: This laboratory study demonstrates the first dual-polarization LEKID array optimized specifically for CMB polarimetry and shows the readiness of the detectors for on-sky observations.

  18. Long wave dispersion relations for surface waves in a magnetically structured atmosphere

    International Nuclear Information System (INIS)

    Rae, I.C.; Roberts, B.

    1983-01-01

    A means of obtaining approximate dispersion relations for long wavelength magnetoacoustic surface waves propagating in a magnetically structured atmosphere is presented. A general dispersion relation applying to a wide range of magnetic profiles is obtained, and illustrated for the special cases of a single interface and a magnetic slab. In the slab geometry, for example, the dispersion relation contains both the even (sausage) and odd (kink) modes in one formalism

  19. Calculation of surface acoustic waves in a multilayered piezoelectric structure

    International Nuclear Information System (INIS)

    Zhang Zuwei; Wen Zhiyu; Hu Jing

    2013-01-01

    The propagation properties of the surface acoustic waves (SAWs) in a ZnO—SiO 2 —Si multilayered piezoelectric structure are calculated by using the recursive asymptotic method. The phase velocities and the electromechanical coupling coefficients for the Rayleigh wave and the Love wave in the different ZnO—SiO 2 —Si structures are calculated and analyzed. The Love mode wave is found to be predominantly generated since the c-axis of the ZnO film is generally perpendicular to the substrate. In order to prove the calculated results, a Love mode SAW device based on the ZnO—SiO 2 —Si multilayered structure is fabricated by micromachining, and its frequency responses are detected. The experimental results are found to be mainly consistent with the calculated ones, except for the slightly larger velocities induced by the residual stresses produced in the fabrication process of the films. The deviation of the experimental results from the calculated ones is reduced by thermal annealing. (semiconductor physics)

  20. Multi-directional plasmonic surface-wave splitters with full bandwidth isolation

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Zhen; Gao, Fei [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore); Zhang, Baile, E-mail: blzhang@ntu.edu.sg [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore); Centre for Disruptive Photonic Technologies, Nanyang Technological University, Singapore 637371 (Singapore)

    2016-03-14

    We present a multidirectional plasmonic surface-wave splitter with full bandwidth isolation experimentally based on coupled defect surface modes in a surface-wave photonic crystal. In contrast to conventional plasmonic surface-wave frequency splitters with polaritonic dispersion relations that overlap at low frequencies, this multidirectional plasmonic surface-wave splitter based on coupled defect surface modes can split different frequency bands into different waveguide branches without bandwidth overlap. Transmission spectra and near-field imaging measurements have been implemented in the microwave frequencies to verify the performance of the multidirectional plasmonic surface-wave splitter. This surface wave structure can be used as a plasmonic wavelength-division multiplexer that may find potential applications in the surface-wave integrated circuits from microwave to terahertz frequencies.

  1. Ferroelectric polarization effect on surface chemistry and photo-catalytic activity: A review

    Science.gov (United States)

    Khan, M. A.; Nadeem, M. A.; Idriss, H.

    2016-03-01

    The current efficiency of various photocatalytic processes is limited by the recombination of photogenerated electron-hole pairs in the photocatalyst as well as the back-reaction of intermediate species. This review concentrates on the use of ferroelectric polarization to mitigate electron-hole recombination and back-reactions and therefore improve photochemical reactivity. Ferroelectric materials are considered as wide band gap polarizable semiconductors. Depending on the surface polarization, different regions of the surface experience different extents of band bending and promote different carriers to move to spatially different locations. This can lead to some interesting interactions at the surface such as spatially selective adsorption and surface redox reactions. This introductory review covers the fundamental properties of ferroelectric materials, effect of an internal electric field/polarization on charge carrier separation, effect of the polarization on the surface photochemistry and reviews the work done on the use of these ferroelectric materials for photocatalytic applications such as dye degradation and water splitting. The manipulation of photogenerated charge carriers through an internal electric field/surface polarization is a promising strategy for the design of improved photocatalysts.

  2. Self-focusing of electromagnetic surface waves on a nonlinear impedance surface

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Zhangjie, E-mail: zhangjie-luo-cn@126.com [College of Electronics and Information Engineering, Sichuan University, Chengdu 610064 (China); Applied Electromagnetics Group, Electrical and Computer Engineering Department, University of California, San Diego, California 92093 (United States); Chen, Xing [College of Electronics and Information Engineering, Sichuan University, Chengdu 610064 (China); Long, Jiang; Quarfoth, Ryan; Sievenpiper, Daniel, E-mail: dsievenpiper@eng.ucsd.edu [Applied Electromagnetics Group, Electrical and Computer Engineering Department, University of California, San Diego, California 92093 (United States)

    2015-05-25

    The self-focusing effect of optical beams has been a popular topic of study for quite a while, but such a nonlinear phenomenon at microwave frequencies has never been realized, partially due to the underdevelopment of nonlinear material. In this research, self-focused electromagnetic (EM) surface waves are demonstrated on a circuit-based, power-dependent impedance surface. The formation of a self-focused beam is investigated using a series of discrete-time simulations, and the result is further validated in measurement. It is experimentally observed that, in contrast to the normal scattering of low-power surface waves, high-power waves propagate through the surface while maintaining narrow beam width, and even converge extremely tightly to create a hot spot with higher power. The result is essentially a nonlinear effect of the surface that compensates for the natural tendency of surface waves to diffract. This intriguing experiment can be extended to various potential EM applications such as power-dependent beam steering antennas and nonlinear microwave propagation or dissipation.

  3. Polarization-Dependent Multi-Functional Metamaterial as Polarization Filter, Transparent Wall and Circular Polarizer using Ring-Cross Resonator

    Directory of Open Access Journals (Sweden)

    Z. Zhang

    2017-09-01

    Full Text Available We propose a polarization-dependent multi-functional metamaterial using ring-cross resonator. Based on the analysis of surface current distributions induced by different polarized incidence, we demonstrate that the proposed metamaterial serves as a polarization filter, a transparent wall and a circular polarizer under different polarization normal incidence. Additionally, parameter analyses on the control of resonance are discussed to complementally explain the physical origin. Simulated results show that the proposed metamaterial functions as a polarization filter eliminating the x-polarization wave at 10.1 GHz and y-polarization wave at 14.3 GHz, a transparent wall transmitting both x-polarized and y-polarized incident waves at 12.6 GHz, and a broadband circular polarizer converting the +45° polarized (-45° polarized incident wave to the left (right handed circularly polarized wave from 10.8 to 12.8 GHz, respectively. Measured results agree well with the simulation and validate the performance of the proposed multifunctional metamaterial.

  4. Particle separation by phase modulated surface acoustic waves.

    Science.gov (United States)

    Simon, Gergely; Andrade, Marco A B; Reboud, Julien; Marques-Hueso, Jose; Desmulliez, Marc P Y; Cooper, Jonathan M; Riehle, Mathis O; Bernassau, Anne L

    2017-09-01

    High efficiency isolation of cells or particles from a heterogeneous mixture is a critical processing step in lab-on-a-chip devices. Acoustic techniques offer contactless and label-free manipulation, preserve viability of biological cells, and provide versatility as the applied electrical signal can be adapted to various scenarios. Conventional acoustic separation methods use time-of-flight and achieve separation up to distances of quarter wavelength with limited separation power due to slow gradients in the force. The method proposed here allows separation by half of the wavelength and can be extended by repeating the modulation pattern and can ensure maximum force acting on the particles. In this work, we propose an optimised phase modulation scheme for particle separation in a surface acoustic wave microfluidic device. An expression for the acoustic radiation force arising from the interaction between acoustic waves in the fluid was derived. We demonstrated, for the first time, that the expression of the acoustic radiation force differs in surface acoustic wave and bulk devices, due to the presence of a geometric scaling factor. Two phase modulation schemes are investigated theoretically and experimentally. Theoretical findings were experimentally validated for different mixtures of polystyrene particles confirming that the method offers high selectivity. A Monte-Carlo simulation enabled us to assess performance in real situations, including the effects of particle size variation and non-uniform acoustic field on sorting efficiency and purity, validating the ability to separate particles with high purity and high resolution.

  5. The Mean Curvature of the Influence Surface of Wave Equation With Sources on a Moving Surface

    Science.gov (United States)

    Farassat, F.; Farris, Mark

    1999-01-01

    The mean curvature of the influence surface of the space-time point (x, t) appears in linear supersonic propeller noise theory and in the Kirchhoff formula for a supersonic surface. Both these problems are governed by the linear wave equation with sources on a moving surface. The influence surface is also called the Sigma - surface in the aeroacoustic literature. This surface is the locus, in a frame fixed to the quiescent medium, of all the points of a radiating surface f(x, t) = 0 whose acoustic signals arrive simultaneously to an observer at position x and at the time t. Mathematically, the Sigma- surface is produced by the intersection of the characteristic conoid of the space-time point (x, t) and the moving surface. In this paper, we derive the expression for the local mean curvature of the Sigma - space of the space-time point for a moving rigid or deformable surface f(x, t) = 0. This expression is a complicated function of the geometric and kinematic parameters of the surface f(x, t) = 0. Using the results of this paper, the solution of the governing wave equation of high speed propeller noise radiation as well as the Kirchhoff formula for a supersonic surface can be written as very compact analytic expression.

  6. Diffraction from polarization holographic gratings with surface relief in side-chain azobenzene polyesters

    DEFF Research Database (Denmark)

    Naydenova, I; Nikolova, L; Todorov, T

    1998-01-01

    We investigate the polarization properties of holographic gratings in side-chain azobenzene polyesters in which an anisotropic grating that is due to photoinduced linear and circular birefringence is recorded in the volume of the material and a relief grating appears on the surface. A theoretical...... in the appearance of a surface relief with doubled frequency....

  7. Subsurface hydrogen bonds at the polar Zn-terminated ZnO(0001) surface

    DEFF Research Database (Denmark)

    Hellström, Matti; Beinik, Igor; Broqvist, Peter

    2016-01-01

    techniques, we find that the polar Zn-terminated ZnO(0001) surface becomes excessively Zn deficient during high-temperature annealing (780 K) in ultrahigh vacuum (UHV). The Zn vacancies align themselves into rows parallel to the [10-10] direction, and the remaining surface Zn ions alternately occupy wurtzite...

  8. Circular polarization of gravitational waves from non-rotating supernova cores: a new probe into the pre-explosion hydrodynamics

    Science.gov (United States)

    Hayama, Kazuhiro; Kuroda, Takami; Kotake, Kei; Takiwaki, Tomoya

    2018-04-01

    We present an analysis of the circular polarization of gravitational-waves (GWs) using results from three-dimensional (3D), general relativistic (GR) core-collapse simulations of a non-rotating 15M⊙ star. For the signal detection, we perform a coherent network analysis taking into account the four interferometers of LIGO Hanford, LIGO Livingston, VIRGO, and KAGRA. We focus on the Stokes V parameter, which directly characterizes the asymmetry of the GW circular polarization. We find that the amplitude of the GW polarization becomes bigger for our 3D-GR model that exhibits strong activity of the standing accretion shock instability (SASI). Our results suggest that the SASI-induced accretion flows to the proto-neutron star (PNS) lead to a characteristic, low-frequency modulation (100 ˜ 200 Hz) in both the waveform and the GW circular polarization. By estimating the signal-to-noise ratio of the GW polarization, we demonstrate that the detection horizon of the circular polarization extends by more than a factor of several times farther comparing to that of the GW amplitude. Our results suggest that the GW circular polarization, if detected, could provide a new probe into the pre-explosion hydrodynamics such as the SASI activity and the g-mode oscillation of the PNS.

  9. On the dependence of sea surface roughness on wind waves

    DEFF Research Database (Denmark)

    Johnson, H.K.; Højstrup, J.; Vested, H.J.

    1998-01-01

    The influence of wind waves on the momentum transfer (wind stress) between the atmosphere and sea surface was studied using new measured data from the RASEX experiment and other datasets compiled by Donelan et al. Results of the data analysis indicate that errors in wind friction velocity u...... that calculations of the wind friction velocities using the wave-spectra-dependent expression of Hansen and Larsen agrees quite well with measured values during RASEX. It also gives a trend in Charnock parameter consistent with that found by combining the field data. Last, calculations using a constant Charnock...... parameter (0.018) also give very good results for the wind friction velocities at the RASEX site....

  10. Surface Acoustic Wave Vibration Sensors for Measuring Aircraft Flutter

    Science.gov (United States)

    Wilson, William C.; Moore, Jason P.; Juarez, Peter D.

    2016-01-01

    Under NASA's Advanced Air Vehicles Program the Advanced Air Transport Technology (AATT) Project is investigating flutter effects on aeroelastic wings. To support that work a new method for measuring vibrations due to flutter has been developed. The method employs low power Surface Acoustic Wave (SAW) sensors. To demonstrate the ability of the SAW sensor to detect flutter vibrations the sensors were attached to a Carbon fiber-reinforced polymer (CFRP) composite panel which was vibrated at six frequencies from 1Hz to 50Hz. The SAW data was compared to accelerometer data and was found to resemble sine waves and match each other closely. The SAW module design and results from the tests are presented here.

  11. High intensity surface plasma waves, theory and PIC simulations

    Science.gov (United States)

    Raynaud, M.; Héron, A.; Adam, J.-C.

    2018-01-01

    With the development of intense (>1019 W cm‑2) short pulses (≤25 fs) laser with very high contrast, surface plasma wave (SPW) can be explored in the relativistic regime. As the SPW propagates with a phase velocity close to the speed of light it may results in a strong acceleration of electron bunches along the surface permitting them to reach relativistic energies. This may be important e.g. for applications in the field of plasma-based accelerators. We investigate in this work the excitation of SPWs on grating preformed over-dense plasmas for laser intensities ranging from 1019 up to 1021 W cm‑2. We discuss the nature of the interaction with respect to the solid case in which surface plasmon can be resonantly excited with weak laser intensity. In particular, we show the importance of the pulse duration and focalization of the laser beam on the amplitude of the SPW.

  12. Biphotonic holographic gratings in azobenzene polyesters: Surface relief phenomena and polarization effects

    DEFF Research Database (Denmark)

    Sánchez, C.; Alcalá, R.; Hvilsted, Søren

    2000-01-01

    Biphotonic holographic gratings have been recorded in a side-chain azobenzene liquid crystalline polyester using a blue incoherent source and a He-Ne laser. Intensity gratings and the appearance of surface relief have been observed when two linearly polarized beams from a He-Ne laser are made...... to interfere on a film illuminated with blue light. Polarized holographic gratings are also created with two orthogonally circularly polarized He-Ne beams. All these gratings are stable in darkness but can be erased with blue light. (C) 2000 American Institute of Physics....

  13. Surface-wave-sustained plasma torch for water treatment

    Science.gov (United States)

    Marinova, P.; Benova, E.; Todorova, Y.; Topalova, Y.; Yotinov, I.; Atanasova, M.; Krcma, F.

    2018-02-01

    In this study the effects of water treatment by surface-wave-sustained plasma torch at 2.45 GHz are studied. Changes in two directions are obtained: (i) changes of the plasma characteristics during the interaction with the water; (ii) water physical and chemical characteristics modification as a result of the plasma treatment. In addition, deactivation of Gram positive and Gram negative bacteria in suspension are registered. A number of charged and excited particles from the plasma interact with the water. As a result the water chemical and physical characteristics such as the water conductivity, pH, H2O2 concentration are modified. It is observed that the effect depends on the treatment time, wave power, and volume of the treated liquid. At specific discharge conditions determined by the wave power, gas flow, discharge tube radius, thickness and permittivity, the surface-wave-sustained discharge (SWD) operating at atmospheric pressure in argon is strongly non-equilibrium with electron temperature T e much higher than the temperature of the heavy particles (gas temperature T g). It has been observed that SWD argon plasma with T g close to the room temperature is able to produce H2O2 in the water with high efficiency at short exposure times (less than 60 sec). The H2O2 decomposition is strongly dependant on the temperature thus the low operating gas temperature is crucial for the H2O2 production efficiency. After scaling up the device, the observed effects can be applied for the waste water treatment in different facilities. The innovation will be useful especially for the treatment of waters and materials for medical application.

  14. Slow upper mantle beneath Southern Norway from surface waves

    Science.gov (United States)

    Weidle, C.; Maupin, V.

    2009-04-01

    A recent regional surface wave tomography for Northern Europe revealed unprecedented images of the upper mantle beneath the (Tertiary) North Atlantic and the bordering Fennoscandian craton of Archean-Proterozoic age. With respect to the circum-Atlantic regions of uplift, no common mantle pattern supporting the uplift of these regions is observed. The western boundary of the thick cratonic lithosphere follows the trend of the continental margin offshore northern Norway (i.e. the northern Scandes are underlain by thick lithosphere) whereas further south the boundary of the craton is located further east beneath southwestern Sweden. SV shear wave velocities beneath southern Norway are 10% slower than ak135 (at 70-115 km depth) and these low-velocities are clearly connected to the North Atlantic low-velocity regime through a ~ 400 km wide "channel". The low-velocity anomaly beneath Southern Norway coincides in geometry roughly with the dome-like high topography of the southern Scandes and may thus have a non-negligible contribution to the isostatic balance of the region. The amplitude and depth-distribution of this anomaly are due to be further constrained by new data that were acquired during the MAGNUS experiment in 2006-2008. The temporary seismic network, consisting of 40 broadband seismometers covers to a large extent the location of the anomaly as imaged by the regional tomography. This enables us to get unique control on the tomographic model at improved lateral and vertical resolution. Preliminary analysis of surface wave phase velocities yields an average 1-D shear wave velocity profile for southern Norway as a first step to constrain the presence and depth extent of this low-velocity anomaly.

  15. Standing surface waves in dusty microwave slot-excited plasma

    International Nuclear Information System (INIS)

    Ostrikov, K.N.; Yu, M.Y.; Sugai, H.

    2000-01-01

    Full text: The effect of charged dust particles on microwave slot-excited plasma has been studied. The dusts absorb significant proportion of the plasma electrons, which leads to a substantial modification of the electromagnetic field structure. The overall charge balance and the eigenfrequencies of the standing TM electromagnetic surface modes are modified by the presence of dust. It has been found that the originally excited surface waves can be shifted out of resonance. For certain proportions of dusts, mode conversion appears to be possible. Microwave gas discharges sustained by surface waves (SW) are promising for many industrial applications as sources of large-volume and large-area low-temperature plasmas. Here, we study the surface-wave sustained microwave plasma reactor contaminated by fine dust particles that usually appear as a substrate-etching product or as a result of polymerization in the gaseous phase. The structure that models the slot-excited planar plasma source is considered. A vertical circular cylinder is short-circuited at its top by a metal plate. A dielectric layer isolates the cylinder top from the plasma, and the chamber bottom is open. We have shown that uncontrolled release of the dusts in the discharge chamber can adversely affect the discharge performance and under certain conditions cause a discharge disruption. This can best be understood by noting that macroparticles absorb a significant proportion of plasma electrons and hence modify the ionization-recombination balance. Moreover, stable operation of the microwave surface-wave sustained discharge depends on the resonant conditions for the operating mode, and it is thus crucial to understand how dusts affect the eigenfrequencies of the SWs. We have demonstrated that introduction of additional amounts of contaminant results in a significant shift of the electron plasma density from its resonant value for the initially excited resonant mode. The system can thus be moved out of

  16. The EUMETSAT Polar System - Second Generation (EPS-SG) micro-wave imaging (MWI) mission

    Science.gov (United States)

    Bojkov, B. R.; Accadia, C.; Klaes, D.; Canestri, A.; Cohen, M.

    2017-12-01

    The EUMETSAT Polar System (EPS) will be followed by a second generation system called EPS-SG. This new family of missions will contribute to the Joint Polar System being jointly set up with NOAA in the timeframe 2020-2040. These satellites will fly, like Metop (EPS), in a sun synchronous, low earth orbit at 830 km altitude and 09:30 local time descending node, providing observations over the full globe with revisit times of 12 hours. EPS-SG consists of two different satellites configurations, the EPS-SGa series dedicated to IR and MW sounding, and the EPS-SGb series dedicated to microwave imaging and scatterometry. The EPS-SG family will consist of three successive launches of each satellite-type. The Microwave Imager (MWI) will be hosted on Metop-SGb series of satellites, with the primary objective of supporting Numerical Weather Prediction (NWP) at regional and global scales. Other applications will be observation of surface parameters such as sea ice concentration and hydrology applications. The 18 MWI instrument frequencies range from 18.7 GHz to 183 GHz. All MWI channels up to 89 GHz will measure V- and H polarizations. The MWI was also designed to provide continuity of measurements for select heritage microwave imager channels (e.g. SSM/I, AMSR-E). The additional sounding channels such as the 50-55 and 118 GHz bands will provide additional cloud and precipitation information over sea and land. This combination of channels was successfully tested on the NPOESS Aircraft Sounder Testbed - Microwave Sounder (NAST-M) airborne radiometer, and it is the first time that will be implemented in a conical scanning configuration in a single instrument. An overview of the EPS-SG programme and the MWI instrument will be presented.

  17. Surface-Wave Tomography of Yucca Flat, Nevada

    Science.gov (United States)

    Toney, L. D.; Abbott, R. E.; Knox, H. A.; Preston, L. A.; Hoots, C. R.

    2016-12-01

    In 2015, Sandia National Laboratories conducted an active-source seismic survey of Yucca Flat, Nevada, on the Nevada National Security Site. The Yucca Flat basin hosted over 900 nuclear tests between 1951 and 1992. Data from this survey will help characterize seismic propagation effects of the area, informing models for the next phase of the Source Physics Experiments. The survey source was a 13,000-kg weight-drop at 91 locations along a 19-km N-S transect and 56 locations along an 11-km E-W transect. Over 350 three-component 2-Hz geophones were variably spaced at 10, 20, and 100 m along each line. We employed roll-along survey geometry to ensure 10-m receiver spacing within 2 km of the source. Phase velocity surface-wave analysis via the refraction-microtremor (ReMi) method was previously performed on this data in order to obtain an S-wave velocity model of the subsurface. However, the results of this approach were significantly impacted in areas where ray paths were proximate to underground nuclear tests, resulting in a spatially incomplete model. We have processed the same data utilizing group velocities and the multiple filter technique (MFT), with the hope that the propagation of wave groups is less impacted by the disrupted media surrounding former tests. We created a set of 30 Gaussian band-pass filters with scaled relative passbands and central frequencies ranging from 1 to 50 Hz. We picked fundamental Rayleigh wave arrivals from the filtered data; these picks were then inverted for 2D S-wave velocity along the transects. The new S-wave velocity model will be integrated with previous P-wave tomographic results to yield a more complete model of the subsurface structure of Yucca Flat. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  18. Robust Imaging Methodology for Challenging Environments: Wave Equation Dispersion Inversion of Surface Waves

    KAUST Repository

    Li, Jing

    2017-12-22

    A robust imaging technology is reviewed that provide subsurface information in challenging environments: wave-equation dispersion inversion (WD) of surface waves for the shear velocity model. We demonstrate the benefits and liabilities of the method with synthetic seismograms and field data. The benefits of WD are that 1) there is no layered medium assumption, as there is in conventional inversion of dispersion curves, so that the 2D or 3D S-velocity model can be reliably obtained with seismic surveys over rugged topography, and 2) WD mostly avoids getting stuck in local minima. The synthetic and field data examples demonstrate that WD can accurately reconstruct the S-wave velocity distributions in laterally heterogeneous media if the dispersion curves can be identified and picked. The WD method is easily extended to anisotropic media and the inversion of dispersion curves associated with Love wave. The liability is that is almost as expensive as FWI and only recovers the Vs distribution to a depth no deeper than about 1/2~1/3 wavelength.

  19. Polarized Human Retinal Pigment Epithelium Exhibits Distinct Surface Proteome on Apical and Basal Plasma Membranes.

    Science.gov (United States)

    Khristov, Vladimir; Wan, Qin; Sharma, Ruchi; Lotfi, Mostafa; Maminishkis, Arvydas; Bharti, Kapil

    2018-01-01

    Surface proteins localized on the apical and basal plasma membranes are required for a cell to sense its environment and relay changes in ionic, cytokine, chemokine, and hormone levels to the inside of the cell. In a polarized cell, surface proteins are differentially localized on the apical or the basolateral sides of the cell. The retinal pigment epithelium (RPE) is an example of a polarized cell that performs a variety of functions that are dependent on its polarized state including trafficking of ions, fluid, and metabolites across the RPE monolayer. These functions are absolutely crucial for maintaining the health and integrity of adjacent photoreceptors, the photosensitive cells of the retina. Here we present a series of approaches to identify and validate the polarization state of cultured primary human RPE cells using immunostaining for RPE apical/basolateral markers, polarized cytokine secretion, electrophysiology, fluid transport, phagocytosis, and identification of plasma membrane proteins through cell surface capturing technology. These approaches are currently being used to validate the polarized state and the epithelial phenotype of human induced pluripotent stem (iPS) cell derived RPE cells. This work provides the basis for developing an autologous cell therapy for age-related macular degeneration using patient specific iPS cell derived RPE.

  20. Construction and characterization of a spin polarized helium ion beam for surface electronic structure studies

    International Nuclear Information System (INIS)

    Harrison, A.R.

    1982-01-01

    Ion neutralization and metastable de-excitation spectroscopy, INS and MDS, allow detailed analysis of the surface electronic configuration of metals. The orthodox application of these spectroscopies may be enhanced by electronic spin polarization of the probe beams. For this reason, a spin polarized helium ion beam has been constructed. The electronic spin of helium metastables created within an rf discharge may be spacially aligned by optically pumping the atoms. Subsequent collisions between metastables produce helium ions which retain the orientation of the electronic spin. Extracted ion polarization, although not directly measurable, may be estimated from extracted electron polarization, metastable polarization, pumping radiation absorption and current modulation measurements. Ions extracted from the optically pumped discharge exhibit an estimated polarization of about ten per cent at a beam current of a few tenths of a microampere. Extraction of helium ions from the discharge requires that the ions have a high kinetic energy. However, to avoid undesirable kinetic electron ejection from the target surface, the ions must be decelerated. Examination of various deceleration configurations, in paticular exponential and linear deceleration fields, and experimental observation indicate that a linear decelerating field produces the best low energy beam to the target surface

  1. Bohm potential effect on the propagation of electrostatic surface wave in semi-bounded quantum plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Myoung-Jae [Department of Physics, Hanyang University, Seoul 04763 (Korea, Republic of); Research Institute for Natural Sciences, Hanyang University, Seoul 04763 (Korea, Republic of); Jung, Young-Dae, E-mail: ydjung@hanyang.ac.kr [Department of Applied Physics and Department of Bionanotechnology, Hanyang University, Ansan, Kyunggi-Do 15588 (Korea, Republic of); Department of Electrical and Computer Engineering, MC 0407, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0407 (United States)

    2017-02-12

    High frequency electrostatic wave propagation in a dense and semi-bounded electron quantum plasma is investigated with consideration of the Bohm potential. The dispersion relation for the surface mode of quantum plasma is derived and numerically analyzed. We found that the quantum effect enhances the frequency of the wave especially in the high wave number regime. However, the frequency of surface wave is found to be always lower than that of the bulk wave for the same quantum wave number. The group velocity of the surface wave for various quantum wave number is also obtained. - Highlights: • High frequency electrostatic wave propagation is investigated in a dense semi-bounded quantum plasma. • The dispersion relation for the surface mode of quantum plasma is derived and numerically analyzed. • The quantum effect enhances the frequency of the wave especially in the high wave number regime. • The frequency of surface wave is found to be always lower than that of the bulk wave. • The group velocity of the surface wave for various quantum wave number is also obtained.

  2. Combined surface acoustic wave and surface plasmon resonance measurement of collagen and fibrinogen layer physical properties

    Directory of Open Access Journals (Sweden)

    J.-M. Friedt

    2016-12-01

    Full Text Available We use an instrument combining optical (surface plasmon resonance and acoustic (Love mode surface acoustic wave device real-time measurements on a same surface for the identification of water content in collagen and fibrinogen protein layers. After calibration of the surface acoustic wave device sensitivity by copper electrodeposition and surfactant adsorption, the bound mass and its physical properties – density and optical index – are extracted from the complementary measurement techniques and lead to thickness and water ratio values compatible with the observed signal shifts. Such results are especially usefully for protein layers with a high water content as shown here for collagen on an hydrophobic surface. We obtain the following results: collagen layers include 70±20% water and are 16±3 to 19±3 nm thick for bulk concentrations ranging from 30 to 300 μg/ml. Fibrinogen layers include 50±10% water for layer thicknesses in the 6±1.5 to 13±2 nm range when the bulk concentration is in the 46 to 460 μg/ml range. Keywords: surface acoustic wave, surface plasmon resonance, collagen, fibrinogen, density, thickness

  3. Internal gravity wave contributions to global sea surface variability

    Science.gov (United States)

    Savage, A.; Arbic, B. K.; Richman, J. G.; Shriver, J. F.; Buijsman, M. C.; Zamudio, L.; Wallcraft, A. J.; Sharma, H.

    2016-02-01

    High-resolution (1/12th and 1/25th degree) 41-layer simulations of the HYbrid Coordinate Ocean Model (HYCOM), forced by both atmospheric fields and the astronomical tidal potential, are used to construct global maps of sea-surface height (SSH). The HYCOM output has been separated into steric, non-steric, and total sea-surface height and the maps display variance in subtidal, tidal, and supertidal bands. Two of the global maps are of particular interest in planning for the upcoming Surface Water and Ocean Topography (SWOT) wide-swath satellite altimeter mission; (1) a map of the nonstationary tidal signal (estimated after removing the stationary tidal signal via harmonic analysis), and (2) a map of the steric supertidal contributions, which are dominated by the internal gravity wave continuum. Both of these maps display signals of order 1 cm2, the target accuracy for the SWOT mission. Therefore, both non-stationary internal tides and non-tidal internal gravity waves are likely to be important sources of "noise" that must be accurately removed before examination of lower-frequency phenomena can take place.

  4. Surface wave propagation effects on buried segmented pipelines

    Directory of Open Access Journals (Sweden)

    Peixin Shi

    2015-08-01

    Full Text Available This paper deals with surface wave propagation (WP effects on buried segmented pipelines. Both simplified analytical model and finite element (FE model are developed for estimating the axial joint pullout movement of jointed concrete cylinder pipelines (JCCPs of which the joints have a brittle tensile failure mode under the surface WP effects. The models account for the effects of peak ground velocity (PGV, WP velocity, predominant period of seismic excitation, shear transfer between soil and pipelines, axial stiffness of pipelines, joint characteristics, and cracking strain of concrete mortar. FE simulation of the JCCP interaction with surface waves recorded during the 1985 Michoacan earthquake results in joint pullout movement, which is consistent with the field observations. The models are expanded to estimate the joint axial pullout movement of cast iron (CI pipelines of which the joints have a ductile tensile failure mode. Simplified analytical equation and FE model are developed for estimating the joint pullout movement of CI pipelines. The joint pullout movement of the CI pipelines is mainly affected by the variability of the joint tensile capacity and accumulates at local weak joints in the pipeline.

  5. Two-dimensional s-polarized solitary waves in plasmas. II. Stability, collisions, electromagnetic bursts, and post-soliton evolution

    International Nuclear Information System (INIS)

    Sanchez-Arriaga, G.; Lefebvre, E.

    2011-01-01

    The dynamics of two-dimensional s-polarized solitary waves is investigated with the aid of particle-in-cell (PIC) simulations. Instead of the usual excitation of the waves with a laser pulse, the PIC code was directly initialized with the numerical solutions from the fluid plasma model. This technique allows the analysis of different scenarios including the theoretical problems of the solitary wave stability and their collision as well as features already measured during laser-plasma experiments such as the emission of electromagnetic bursts when the waves reach the plasma-vacuum interface, or their expansion on the ion time scale, usually named post-soliton evolution. Waves with a single density depression are stable whereas multihump solutions decay to several waves. Contrary to solitons, two waves always interact through a force that depends on their relative phases, their amplitudes, and the distance between them. On the other hand, the radiation pattern at the plasma-vacuum interface was characterized, and the evolution of the diameter of different waves was computed and compared with the ''snow plow'' model.

  6. Surface Modification on Acoustic Wave Biosensors for Enhanced Specificity

    Directory of Open Access Journals (Sweden)

    Nathan D. Gallant

    2012-09-01

    Full Text Available Changes in mass loading on the surface of acoustic biosensors result in output frequency shifts which provide precise measurements of analytes. Therefore, to detect a particular biomarker, the sensor delay path must be judiciously designed to maximize sensitivity and specificity. B-cell lymphoma 2 protein (Bcl-2 found in urine is under investigation as a biomarker for non-invasive early detection of ovarian cancer. In this study, surface chemistry and biofunctionalization approaches were evaluated for their effectiveness in presenting antibodies for Bcl-2 capture while minimizing non-specific protein adsorption. The optimal combination of sequentially adsorbing protein A/G, anti-Bcl-2 IgG and Pluronic F127 onto a hydrophobic surface provided the greatest signal-to-noise ratio and enabled the reliable detection of Bcl-2 concentrations below that previously identified for early stage ovarian cancer as characterized by a modified ELISA method. Finally, the optimal surface modification was applied to a prototype acoustic device and the frequency shift for a range of Bcl-2 concentration was quantified to demonstrate the effectiveness in surface acoustic wave (SAW-based detection applications. The surface functionalization approaches demonstrated here to specifically and sensitively detect Bcl-2 in a working ultrasonic MEMS biosensor prototype can easily be modified to detect additional biomarkers and enhance other acoustic biosensors.

  7. Polarized-neutron-scattering study of the spin-wave excitations in the 3-k ordered phase of uranium antimonide.

    Science.gov (United States)

    Magnani, N; Caciuffo, R; Lander, G H; Hiess, A; Regnault, L-P

    2010-03-24

    The anisotropy of magnetic fluctuations propagating along the [1 1 0] direction in the ordered phase of uranium antimonide has been studied using polarized inelastic neutron scattering. The observed polarization behavior of the spin waves is a natural consequence of the longitudinal 3-k magnetic structure; together with recent results on the 3-k-transverse uranium dioxide, these findings establish this technique as an important tool to study complex magnetic arrangements. Selected details of the magnon excitation spectra of USb have also been reinvestigated, indicating the need to revise the currently accepted theoretical picture for this material.

  8. Robust Likelihoods for Inflationary Gravitational Waves from Maps of Cosmic Microwave Background Polarization

    Science.gov (United States)

    Switzer, Eric Ryan; Watts, Duncan J.

    2016-01-01

    The B-mode polarization of the cosmic microwave background provides a unique window into tensor perturbations from inflationary gravitational waves. Survey effects complicate the estimation and description of the power spectrum on the largest angular scales. The pixel-space likelihood yields parameter distributions without the power spectrum as an intermediate step, but it does not have the large suite of tests available to power spectral methods. Searches for primordial B-modes must rigorously reject and rule out contamination. Many forms of contamination vary or are uncorrelated across epochs, frequencies, surveys, or other data treatment subsets. The cross power and the power spectrum of the difference of subset maps provide approaches to reject and isolate excess variance. We develop an analogous joint pixel-space likelihood. Contamination not modeled in the likelihood produces parameter-dependent bias and complicates the interpretation of the difference map. We describe a null test that consistently weights the difference map. Excess variance should either be explicitly modeled in the covariance or be removed through reprocessing the data.

  9. Polarization-independent terahertz wave modulator based on graphene-silicon hybrid structure

    Science.gov (United States)

    Liang-Liang, Du; Quan, Li; Shao-Xian, Li; Fang-Rong, Hu; Xian-Ming, Xiong; Yan-Feng, Li; Wen-Tao, Zhang; Jia-Guang, Han

    2016-02-01

    In this study, we propose and demonstrate a broadband polarization-independent terahertz modulator based on graphene/silicon hybrid structure through a combination of continuous wave optical illumination and electrical gating. Under a pump power of 400 mW and the voltages ranging from -1.8 V to 1.4 V, modulation depths in a range of -23%-62% are achieved in a frequency range from 0.25 THz to 0.65 THz. The modulator is also found to have a transition from unidirectional modulation to bidirectional modulation with the increase of pump power. Combining the Raman spectra and Schottky current-voltage characteristics of the device, it is found that the large amplitude modulation is ascribed to the electric-field controlled carrier concentration in silicon with assistance of the graphene electrode and Schottky junction. Project supported by the National Natural Science Foundation of China (Grant No. 61565004), the Natural Science Foundation of Guangxi Zhuang Autonomous Region, China (Grant Nos. 2013GXNSFDA019002 and 2014GXNSFGA118003), the Guangxi Scientific Research and Technology Development Program, China (Grant No. 1598017-1), the Guilin Scientific Research and Technology Development Program, China (Grant Nos. 20140127-1 and 20150133-3), and the Special Funds for Distinguished Experts of Guangxi Zhuang Autonomous Region, China.

  10. Investigating of short period gravity waves using multi-beam experiments above Andenes in the polar summer mesopause

    Science.gov (United States)

    Stober, Gunter; Sommer, Svenja; Chau, Jorge L.; Latteck, Ralph

    2014-05-01

    In summer 2013 the Middle Atmosphere Alomar Radar System (MAARSY) conducted a multi-beam scanning experiment using 65 different beam directions. These systematic scanning experiments are analysed with respect to gravity waves with periods from 4 minutes up to 8 hours using polar mesospheric summer echoes (PMSE) as tracer. The gravity waves are investigated by decomposing the wind field into a mean wind and superimposed tidal components (diurnal, semidiurnal and terdiurnal). After subtracting these mean winds and tides we get a residuum wind dominated by the gravity waves with periods shorter than 8 hours. Using this approach we have been able to identified significant wave burst, with amplitudes as high as 50 m/s and 10-20 m/s for the horizontal and vertical wind components, respectively. In addition, we have identified events that indicate the development of KH-instabilities.

  11. Circuit Design of Surface Acoustic Wave Based Micro Force Sensor

    Directory of Open Access Journals (Sweden)

    Yuanyuan Li

    2014-01-01

    Full Text Available Pressure sensors are commonly used in industrial production and mechanical system. However, resistance strain, piezoresistive sensor, and ceramic capacitive pressure sensors possess limitations, especially in micro force measurement. A surface acoustic wave (SAW based micro force sensor is designed in this paper, which is based on the theories of wavelet transform, SAW detection, and pierce oscillator circuits. Using lithium niobate as the basal material, a mathematical model is established to analyze the frequency, and a peripheral circuit is designed to measure the micro force. The SAW based micro force sensor is tested to show the reasonable design of detection circuit and the stability of frequency and amplitude.

  12. Surface waves in fibre-reinforced anisotropic elastic media

    Indian Academy of Sciences (India)

    Springer Verlag Heidelberg #4 2048 1996 Dec 15 10:16:45

    The absence of stress over the free surface enables us to replace the right-hand side of (20) and (21) by zero, giving. 2rA + (s2 − 1)B = 0,. (24). [(λ + α) + r2(λ + 2µT )A − (2µT − α)s = 0. (25). Eliminating A and B from (24) and (25) we obtain the Rayleigh type of waves in the fibre-reinforced elastic medium as. (1 − s2)[(λ + α) + ...

  13. Strong Linear Dichroism in Spin-Polarized Photoemission from Spin-Orbit-Coupled Surface States.

    Science.gov (United States)

    Bentmann, H; Maaß, H; Krasovskii, E E; Peixoto, T R F; Seibel, C; Leandersson, M; Balasubramanian, T; Reinert, F

    2017-09-08

    A comprehensive understanding of spin-polarized photoemission is crucial for accessing the electronic structure of spin-orbit coupled materials. Yet, the impact of the final state in the photoemission process on the photoelectron spin has been difficult to assess in these systems. We present experiments for the spin-orbit split states in a Bi-Ag surface alloy showing that the alteration of the final state with energy may cause a complete reversal of the photoelectron spin polarization. We explain the effect on the basis of ab initio one-step photoemission theory and describe how it originates from linear dichroism in the angular distribution of photoelectrons. Our analysis shows that the modulated photoelectron spin polarization reflects the intrinsic spin density of the surface state being sampled differently depending on the final state, and it indicates linear dichroism as a natural probe of spin-orbit coupling at surfaces.

  14. Surface polar states and pyroelectricity in ferroelastics induced by flexo-roto field

    Science.gov (United States)

    Morozovska, A. N.; Eliseev, E. A.; Kalinin, S. V.; Qing Chen, Long; Gopalan, Venkatraman

    2012-04-01

    Theoretical analysis based on the Landau-Ginzburg-Devonshire theory is used to show that the joint action of flexoelectric effect and rotostriction leads to a large spontaneous in-plane polarization (˜1-5 μC/cm2) and pyroelectric coefficient (˜10-3 C/m2K) in the vicinity of surfaces of otherwise non-ferroelectric ferroelastics, such as SrTiO3, with static octahedral rotations. The origin of the improper polarization and pyroelectricity is an electric field we name flexo-roto field whose strength is proportional to the convolution of the flexoelectric and rotostriction tensors with octahedral tilts and their gradients. Flexo-roto field should exist at surfaces and interfaces in all structures with static octahedral rotations, and thus, it can induce surface polar states and pyroelectricity in a large class of otherwise nonpolar materials.

  15. Circular polarization of light by planet Mercury and enantiomorphism of its surface minerals.

    Science.gov (United States)

    Meierhenrich, Uwe J; Thiemann, Wolfram H P; Barbier, Bernard; Brack, André; Alcaraz, Christian; Nahon, Laurent; Wolstencroft, Ray

    2002-04-01

    Different mechanisms for the generation of circular polarization by the surface of planets and satellites are described. The observed values for Venus, the Moon, Mars, and Jupiter obtained by photo-polarimetric measurements with Earth based telescopes, showed accordance with theory. However, for planet Mercury asymmetric parameters in the circular polarization were measured that do not fit with calculations. For BepiColombo, the ESA cornerstone mission 5 to Mercury, we propose to investigate this phenomenon using a concept which includes two instruments. The first instrument is a high-resolution optical polarimeter, capable to determine and map the circular polarization by remote scanning of Mercury's surface from the Mercury Planetary Orbiter MPO. The second instrument is an in situ sensor for the detection of the enantiomorphism of surface crystals and minerals, proposed to be included in the Mercury Lander MSE.

  16. A proper methodology aimed at surface wave tomography

    Directory of Open Access Journals (Sweden)

    J. Badal

    1997-06-01

    Full Text Available When applying a methodology for obtaining the 3D shear-wave velocity structure of a medium from surface wave dispersion data, the problem must be considered with caution since one inverts path-averaged velocities and the use of any inversion method entails some drawbacks such as lack of uniqueness, unwarranted stability and constraints affecting the data. In order to avoid the application of consecutive inversions and to overcome these drawbacks, we propose alternative mapping methods, for example spatial prediction methods, or else the use of an algorithm that, from a mathematical viewpoint, can be understood through the application of the orthogonal projection theorem onto convex sets (POCS. Among the first ones, we try inverse weighted distance interpolation. The POCS algorithm we have used discretises a second order differential equation for the velocity field with boundary conditions. All these imaging techniques aimed at volumetric modelling and the visualisation of data are discussed, and finally we show some results based on ray path velocities obtained previously by inversion of phase and group velocities of Rayleigh waves propagating across the Iberian peninsula.

  17. Imaging near-surface heterogeneities by natural migration of backscattered surface waves: Field data test

    KAUST Repository

    Liu, Zhaolun

    2017-03-06

    We have developed a methodology for detecting the presence of near-surface heterogeneities by naturally migrating backscattered surface waves in controlled-source data. The near-surface heterogeneities must be located within a depth of approximately one-third the dominant wavelength λ of the strong surface-wave arrivals. This natural migration method does not require knowledge of the near-surface phase-velocity distribution because it uses the recorded data to approximate the Green’s functions for migration. Prior to migration, the backscattered data are separated from the original records, and the band-passed filtered data are migrated to give an estimate of the migration image at a depth of approximately one-third λ. Each band-passed data set gives a migration image at a different depth. Results with synthetic data and field data recorded over known faults validate the effectiveness of this method. Migrating the surface waves in recorded 2D and 3D data sets accurately reveals the locations of known faults. The limitation of this method is that it requires a dense array of receivers with a geophone interval less than approximately one-half λ.

  18. Variational space–time (dis)continuous Galerkin method for nonlinear free surface water waves

    NARCIS (Netherlands)

    Gagarina, Elena; Ambati, V.R.; van der Vegt, Jacobus J.W.; Bokhove, Onno

    2014-01-01

    A new variational finite element method is developed for nonlinear free surface gravity water waves using the potential flow approximation. This method also handles waves generated by a wave maker. Its formulation stems from Miles’ variational principle for water waves together with a finite element

  19. Variational space-time (dis)continuous Galerkin method for nonlinear free surface waves

    NARCIS (Netherlands)

    Gagarina, Elena; van der Vegt, Jacobus J.W.; Ambati, V.R.; Bokhove, Onno

    A new variational finite element method is developed for nonlinear free surface gravity water waves. This method also handles waves generated by a wave maker. Its formulation stems from Miles' variational principle for water waves together with a space-time finite element discretization that is

  20. Bloch surface waves confined in one dimension with a single polymeric nanofibre

    Science.gov (United States)

    Wang, Ruxue; Xia, Hongyan; Zhang, Douguo; Chen, Junxue; Zhu, Liangfu; Wang, Yong; Yang, Erchan; Zang, Tianyang; Wen, Xiaolei; Zou, Gang; Wang, Pei; Ming, Hai; Badugu, Ramachandram; Lakowicz, Joseph R.

    2017-02-01

    Polymeric fibres with small radii (such as ≤125 nm) are delicate to handle and should be laid down on a solid substrate to obtain practical devices. However, placing these nanofibres on commonly used glass substrates prevents them from guiding light. In this study, we numerically and experimentally demonstrate that when the nanofibre is placed on a suitable dielectric multilayer, it supports a guided mode, a Bloch surface wave (BSW) confined in one dimension. The physical origin of this new mode is discussed in comparison with the typical two-dimensional BSW mode. Polymeric nanofibres are easily fabricated to contain fluorophores, which make the dielectric nanofibre and multilayer configuration suitable for developing a large range of new nanometric scale devices, such as processor-memory interconnections, devices with sensitivity to target analytes, incident polarization and multi-colour BSW modes.

  1. Near-surface fault detection by migrating back-scattered surface waves with and without velocity profiles

    KAUST Repository

    Yu, Han

    2016-04-26

    We demonstrate that diffraction stack migration can be used to discover the distribution of near-surface faults. The methodology is based on the assumption that near-surface faults generate detectable back-scattered surface waves from impinging surface waves. We first isolate the back-scattered surface waves by muting or FK filtering, and then migrate them by diffraction migration using the surface wave velocity as the migration velocity. Instead of summing events along trial quasi-hyperbolas, surface wave migration sums events along trial quasi-linear trajectories that correspond to the moveout of back-scattered surface waves. We have also proposed a natural migration method that utilizes the intrinsic traveltime property of the direct and the back-scattered waves at faults. For the synthetic data sets and the land data collected in Aqaba, where surface wave velocity has unexpected perturbations, we migrate the back-scattered surface waves with both predicted velocity profiles and natural Green\\'s function without velocity information. Because the latter approach avoids the need for an accurate velocity model in event summation, both the prestack and stacked migration images show competitive quality. Results with both synthetic data and field records validate the feasibility of this method. We believe applying this method to global or passive seismic data can open new opportunities in unveiling tectonic features.

  2. Resent developments in high-frequency surface-wave techniques

    Science.gov (United States)

    Xia, J.; Pan, Y.; Zeng, C.

    2012-12-01

    High-frequency Rayleigh-wave methods, such as Multi-channel Analysis of Surface Waves (MASW), are getting increasingly attention in the near-surface geophysics and geotechnique community in the last 20 years because of their non-invasive, non-destructive, efficient, and low-cost advantages and their success in environmental and engineering applications. They are viewed by near-surface geophysics community as the one of most promise techniques in the future. However, they face unique problems related to extremely irregular velocity variations in near-surface geology or man-made constructions, for example, highway, foundation, dam, levee, jetty, etc., which are not solvable by techniques or algorithms widely used in earthquake seismology or oil/gas seismic exploration. We present solutions to the problems associated with near-surface materials that possess velocity inverse and high Poisson's ratio. Calculation of dispersion curves by existing algorithms may fail for some special velocity models due to velocity inverse (a high-velocity layer on the top of a low-velocity layer). Two velocity models are most common in near-surface applications. One is a low-velocity half space model and the other a high-velocity topmost layer. The former model results in a complex matrix that no roots can be found in the real number domain, which implies that no phase velocities can be calculated in certain frequency ranges based on current exist algorithms. A solution is to use the real part of the root of the complex number. It is well-known that phase velocities approach about 91% of the shear (S)-wave velocity of the topmost layer when wavelengths are much shorter than the thickness of the topmost layer. The later model, however, results in that phase velocities in a high-frequency range calculated using the current algorithms approach a velocity associated with the S-wave velocity of the second layer NOT the topmost layer. A solution to this problem is to use a two-layer model to

  3. Nonlinear waves and solitons on contours and closed surfaces

    CERN Document Server

    Ludu, Andrei

    2012-01-01

    This volume is an introduction to nonlinear waves and soliton theory in the special environment of compact spaces such a closed curves and surfaces and other domain contours. It assumes familiarity with basic soliton theory and nonlinear dynamical systems. The first part of the book introduces the mathematical concept required for treating the manifolds considered, providing relevant notions from topology and differential geometry. An introduction to the theory of motion of curves and surfaces - as part of the emerging field of contour dynamics - is given. The second and third parts discuss the modeling of various physical solitons on compact systems, such as filaments, loops and drops made of almost incompressible materials thereby intersecting with a large number of physical disciplines from hydrodynamics to compact object astrophysics. This book is intended for graduate students and researchers in mathematics, physics and engineering. This new edition has been thoroughly revised, expanded and updated.

  4. Visualization of terahertz surface waves propagation on metal foils

    Science.gov (United States)

    Wang, Xinke; Wang, Sen; Sun, Wenfeng; Feng, Shengfei; Han, Peng; Yan, Haitao; Ye, Jiasheng; Zhang, Yan

    2016-01-01

    Exploitation of surface plasmonic devices (SPDs) in the terahertz (THz) band is always beneficial for broadening the application potential of THz technologies. To clarify features of SPDs, a practical characterization means is essential for accurately observing the complex field distribution of a THz surface wave (TSW). Here, a THz digital holographic imaging system is employed to coherently exhibit temporal variations and spectral properties of TSWs activated by a rectangular or semicircular slit structure on metal foils. Advantages of the imaging system are comprehensively elucidated, including the exclusive measurement of TSWs and fall-off of the time consumption. Numerical simulations of experimental procedures further verify the imaging measurement accuracy. It can be anticipated that this imaging system will provide a versatile tool for analyzing the performance and principle of SPDs. PMID:26729652

  5. Nonlinear optical responses to circularly polarized lights of the surface state of a topological insulator

    Science.gov (United States)

    Misawa, Tetsuro; Yokoyama, Takehito; Murakami, Shuichi

    2012-02-01

    Recent photoelectron spectroscopy experiments have revealed the presence of the Dirac cone on the surface of the topological insulator and its spin-splitting due to the spin-orbit interaction. In general, on spin-orbit coupled systems, electric fields induce spin polarizations as linear and nonlinear responses. Here we investigate the inverse Faraday effect on the surface of the topological insulator. The inverse Faraday effect is a non-linear optical effect where a circularly polarized light induces a dc spin polarization. We employ the Keldysh Green's function method to calculate the induced spin polarization and discuss its frequency dependence. In particular, in the low frequency limit, our analytical result gives the spin polarization proportional to the frequency and the square of the lifetime. As for the finite frequency regime, we employ numerical methods to discuss the resonance due to interband transitions. We also discuss the photogalvanic effect, where an illumination of a circular polarized light generates the dc charge current. Lastly, we evaluate those quantities with realistic parameters.[4pt] [1] T. Misawa, T. Yokoyama, S. Murakami, Phys. Rev. B84, 165407 (2011).

  6. Spin polarization driven by a charge-density wave in monolayer 1T−TaS2

    KAUST Repository

    Zhang, Qingyun

    2014-08-06

    Using first-principles calculations, we investigate the electronic and vibrational properties of monolayer T-phase TaS2. We demonstrate that a charge-density wave is energetically favorable at low temperature, similar to bulk 1T-TaS2. Electron-phonon coupling is found to be essential for the lattice reconstruction. The charge-density wave results in a strong localization of the electronic states near the Fermi level and consequently in spin polarization, transforming the material into a magnetic semiconductor with enhanced electronic correlations. The combination of inherent spin polarization with a semiconducting nature distinguishes the monolayer fundamentally from the bulk compound as well as from other two-dimensional transition metal dichalcogenides. Monolayer T-phase TaS2 therefore has the potential to enable two-dimensional spintronics. © 2014 American Physical Society.

  7. Surface Waves Propagating on Grounded Anisotropic Dielectric Slab

    Directory of Open Access Journals (Sweden)

    Zhuozhu Chen

    2018-01-01

    Full Text Available This paper investigates the characteristics of surface waves propagating on a grounded anisotropic dielectric slab. Distinct from the existing analyses that generally assume that the fields of surface wave uniformly distribute along the transverse direction of the infinitely large grounded slab, our method takes into account the field variations along the transverse direction of a finite-width slab. By solving Maxwell’s equations in closed-form, it is revealed that no pure transverse magnetic (TM or transverse electric (TE mode exists if the fields are non-uniformly distributed along the transverse direction of the grounded slab. Instead, two hybrid modes, namely quasi-TM and quasi-TE modes, are supported. In addition, the propagation characteristics of two hybrid modes supported by the grounded anisotropic slab are analyzed in terms of the slab thickness, slab width, as well as the relative permittivity tensor of the anisotropic slab. Furthermore, different methods are employed to compare the analyses, as well as to validate our derivations. The proposed method is very suitable for practical engineering applications.

  8. Optical tracking of local surface wave for skin viscoelasticity.

    Science.gov (United States)

    Guan, Yubo; Lu, Mingzhu; Shen, Zhilong; Wan, Mingxi

    2014-06-01

    Rapid and effective determination of biomechanical properties is important in examining and diagnosing skin thermal injury. Among the methods used, viscoelasticity quantification is one of the most effective methods in determining such properties. This study aims to rapidly determine skin viscoelasticity by optically tracking the local surface wave. New elastic and viscous coefficients were proposed to indicate skin viscoelasticity based on a single impulse response of the skin. Experiments were performed using fresh porcine skin samples. Surface wave was generated in a single impulse using a vibrator with a ball-tipped device and was detected using a laser Doppler vibrometer. The motions along the depth direction were monitored using an ultrasound system. The ultrasound monitoring results indicated the multi-layered viscoelasticity of the epidermis and dermis. The viscoelastic coefficients from four healthy samples show a potential viscoelasticity variation of porcine skin. In one sample, the two coefficients were evidently higher than those in a healthy area if the skin was slightly burned. These results indicate that the proposed method is sensitive, effective, and quick in determining skin viscoelasticity. Copyright © 2014 IPEM. Published by Elsevier Ltd. All rights reserved.

  9. Determination of optimum "multi-channel surface wave method" field parameters.

    Science.gov (United States)

    2012-12-01

    Multi-channel surface wave methods (especially the multi-channel analyses of surface wave method; MASW) are routinely used to : determine the shear-wave velocity of the subsurface to depths of 100 feet for site classification purposes. Users are awar...

  10. Polarization Dependence of Surface Enhanced Raman Scattering on a Single Dielectric Nanowire

    Directory of Open Access Journals (Sweden)

    Hua Qi

    2012-01-01

    Full Text Available Our measurements of surface enhanced Raman scattering (SERS on Ga2O3 dielectric nanowires (NWs core/silver composites indicate that the SERS enhancement is highly dependent on the polarization direction of the incident laser light. The polarization dependence of the SERS signal with respect to the direction of a single NW was studied by changing the incident light angle. Further investigations demonstrate that the SERS intensity is not only dependent on the direction and wavelength of the incident light, but also on the species of the SERS active molecule. The largest signals were observed on an NW when the incident 514.5 nm light was polarized perpendicular to the length of the NW, while the opposite phenomenon was observed at the wavelength of 785 nm. Our theoretical simulations of the polarization dependence at 514.5 nm and 785 nm are in good agreement with the experimental results.

  11. Influence of refraction of p-polarized light on photoemission from metallic surface states

    International Nuclear Information System (INIS)

    Bagchi, A.; Barrera, R.G.

    1979-01-01

    The refraction of p-polarized light at a metal surface leads, under certain circumstances, to a large peak in the spatial distribution of the normal component of the electric field near the surface. The origin of this peak is explained both in terms of a classical correspondence and in terms of a theory based on the non-local dielectric response of the metal surface. The significance of the large magnitude and rapid variation of the surface electric field in exciting photoelectrons from surface states is discussed [pt

  12. Selective Solvent-Induced Stabilization of Polar Oxide Surfaces in an Electrochemical Environment

    Science.gov (United States)

    Yoo, Su-Hyun; Todorova, Mira; Neugebauer, Jörg

    2018-02-01

    The impact of an electrochemical environment on the thermodynamic stability of polar oxide surfaces is investigated for the example of ZnO(0001) surfaces immersed in water using density functional theory calculations. We show that solvation effects are highly selective: They have little effect on surfaces showing a metallic character, but largely stabilize semiconducting structures, particularly those that have a high electrostatic penalty in vacuum. The high selectivity is shown to have direct consequences for the surface phase diagram and explains, e.g., why certain surface structures could be observed only in an electrochemical environment.

  13. Wind fields of storms from surface isobars for wave hindcasting

    Digital Repository Service at National Institute of Oceanography (India)

    Varkey, M.J.; Vaithiyanathan, R.; Santanam, K.

    Marine operations of various types are critically linked to mean and extreme wave statistics. In the Indian seas extreme wave conditions are caused by cyclones and steady strong monsoon winds. Wave data from cyclone areas are not directly available...

  14. Polarity-induced persistent surface reconstruction in SrRuO3(111) thin films.

    Science.gov (United States)

    Xie, Weimei; Saghayezhian, Mohammad; Gu, M. Q.; Guo, Hangwen; Wu, X. S.; Plummer, E. W.; Zhang, Jiandi

    The surface structural and electronic properties of SrRuO3/SrTiO3\\ (111) as function of the film thickness are investigated. It is found that, though the interface of SRO/STO (111) has no polar mismatch and negligible lattice mismatch, the polar surface of SrRuO3 (111) thin films results in a persistent surface reconstruction. Above 2 unit cells, a (√{ 3} ×√{ 3}) R30° surface reconstruction is observed with both Low energy and reflection high energy electron diffraction. X-ray photoemission spectroscopy shows that the reconstruction is associated with the ordered oxygen vacancies on SrO3-δ terminated surface to compensate the surface polarity. Post annealing in oxygen/ozone mixture restores the p(1 × 1) surface structure, but results in different surface relaxation and enhances the metallicity thus reducing the thickness of dead layer in this material. Supported by U.S. DOE under Grant No. DOE DE-SC0002136.

  15. Vector Sky Glint Corrections for Above Surface Retrieval of the Subsurface Polarized Light Field

    Science.gov (United States)

    Gilerson, A.; Foster, R.; McGilloway, A.; Ibrahim, A.; El-habashi, A.; Carrizo, C.; Ahmed, S.

    2016-02-01

    Knowledge of the underwater light field is fundamental to determining the health of the world's oceans and coastal regions. For decades, traditional remote sensing retrieval methods that rely solely on the spectral intensity of the water-leaving light have provided indicators of marine ecosystem health. As the demand for retrieval accuracy rises, use of the polarized nature of light as an additional remote sensing tool is becoming necessary. In order to observe the underwater polarized light field from above the surface (for ship, shore, or satellite applications), a method of correcting the above water signal for the effects of polarized surface-reflected skylight is needed. For three weeks in July-August 2014, the NASA Ship Aircraft Bio-Optical Research (SABOR) cruise continuously observed the polarized radiance of the ocean and the sky using a HyperSAS-POL system. The system autonomously tracks the Sun position and the heading of the research vessel in order to maintain a fixed relative solar azimuth angle (i.e. ±90°) and therefore avoid the specular reflection of the sunlight. Additionally, in-situ inherent optical properties (IOPs) were continuously acquired using a set of instrument packages modified for underway measurement, hyperspectral radiometric measurements were taken manually at all stations, and an underwater polarimeter was deployed when conditions permitted. All measurements, above and below the sea surface, were combined and compared in an effort to first develop a glint (sky + Sun) correction scheme for the upwelling polarized signal from a wind-driven ocean surface and compare with one assuming that the ocean surface is flat. Accurate retrieval of the subsurface vector light field is demonstrated through comparisons with polarized radiative transfer codes and direct measurements made by the underwater polarimeter.

  16. Circular Polarization of Light By Planet Mercury and Enantiomorphism of Its Surface Minerals

    Science.gov (United States)

    Meierhenrich, U. J.; Thiemann, W. H.-P.; Barbier, B.; Brack, A.; Nahon, L.; Alcaraz, C.; Wolstencroft, R.

    Different mechanisms for the generation of circular polarization on the surface of planets and satellites are described. The observed values for Venus, the Moon, Mars, and Jupiter obtained by photo-polarimetric measurements with Earth based telescopes, showed accordance with theory. However, for planet Mercury asymmetric parameters in the circular polarization were measured that do not fit with calculations. For Bepi- Colombo, we propose to investigate this phenomenon using a concept which includes two instruments. The first instrument is a high-resolution optical polarimeter,[1,2] ca- pable to determine and map the circular polarization by remote scanning of Mercury's surface from the Mercury Planetary Orbiter MPO. The second instrument is an in situ sensor for the detection of the enantiomorphism of surface crystals and minerals, proposed to be included in the Mercury Lander MSE. [1] C. Alcaraz, R. Thissen, M. Compin, A. Jolly, M. Drescher, L. Nahon: First po- larization measurements of Ophelie: a versatile polarization VUV undulator at Super- Aco. SPIE 3773 (1999), 250-261. [2] C. Alcaraz, J.L. Marlats, D. Nether, B. Pilette, L. Nahon: A dedicated precise polarimeter for measurement of VUV versatile photon polarizations, Applied Optics, manuscript under preparation.

  17. Electrostatic Self-Assembly of Diamond Nanoparticles onto Al- and N-Polar Sputtered Aluminum Nitride Surfaces.

    Science.gov (United States)

    Yoshikawa, Taro; Reusch, Markus; Zuerbig, Verena; Cimalla, Volker; Lee, Kee-Han; Kurzyp, Magdalena; Arnault, Jean-Charles; Nebel, Christoph E; Ambacher, Oliver; Lebedev, Vadim

    2016-11-17

    Electrostatic self-assembly of diamond nanoparticles (DNPs) onto substrate surfaces (so-called nanodiamond seeding) is a notable technique, enabling chemical vapor deposition (CVD) of nanocrystalline diamond thin films on non-diamond substrates. In this study, we examine this technique onto differently polarized (either Al- or N-polar) c -axis oriented sputtered aluminum nitride (AlN) film surfaces. This investigation shows that Al-polar films, as compared to N-polar ones, obtain DNPs with higher density and more homogeneously on their surfaces. The origin of these differences in density and homogeneity is discussed based on the hydrolysis behavior of AlN surfaces in aqueous suspensions.

  18. An adaptive Bayesian inversion for upper mantle structure using surface waves and scattered body waves

    Science.gov (United States)

    Eilon, Zachary; Fischer, Karen M.; Dalton, Colleen A.

    2018-04-01

    We present a methodology for 1-D imaging of upper mantle structure using a Bayesian approach that incorporates a novel combination of seismic data types and an adaptive parameterisation based on piecewise discontinuous splines. Our inversion algorithm lays the groundwork for improved seismic velocity models of the lithosphere and asthenosphere by harnessing the recent expansion of large seismic arrays and computational power alongside sophisticated data analysis. Careful processing of P- and S-wave arrivals isolates converted phases generated at velocity gradients between the mid-crust and 300 km depth. This data is allied with ambient noise and earthquake Rayleigh wave phase velocities to obtain detailed VS and VP velocity models. Synthetic tests demonstrate that converted phases are necessary to accurately constrain velocity gradients, and S-p phases are particularly important for resolving mantle structure, while surface waves are necessary for capturing absolute velocities. We apply the method to several stations in the northwest and north-central United States, finding that the imaged structure improves upon existing models by sharpening the vertical resolution of absolute velocity profiles, offering robust uncertainty estimates, and revealing mid-lithospheric velocity gradients indicative of thermochemical cratonic layering. This flexible method holds promise for increasingly detailed understanding of the upper mantle.

  19. S-wave velocity measurements along levees in New Orleans using passive surface wave methods

    Science.gov (United States)

    Hayashi, K.; Lorenzo, J. M.; Craig, M. S.; Gostic, A.

    2017-12-01

    In order to develop non-invasive methods for levee inspection, geophysical investigations were carried out at four sites along levees in the New Orleans area: 17th Street Canal, London Avenue Canal, Marrero Levee, and Industrial Canal. Three of the four sites sustained damage from Hurricane Katrina in 2005 and have since been rebuilt. The geophysical methods used include active and passive surface wave methods, and capacitively coupled resistivity. This paper summarizes the acquisition and analysis of the 1D and 2D passive surface wave data. Twelve wireless seismic data acquisition units with 2 Hz vertical component geophones were used to record data. Each unit includes a GPS receiver so that all units can be synchronized over any distance without cables. The 1D passive method used L shaped arrays of three different sizes with geophone spacing ranging from 5 to 340 m. Ten minutes to one hour of ambient noise was recorded with each array, and total data acquisition took approximately two hours at each site. The 2D method used a linear array with a geophone spacing of 5m. Four geophones were moved forward every 10 minutes along 400 1000 m length lines. Data acquisition took several hours for each line. Recorded ambient noise was processed using the spatial autocorrelation method and clear dispersion curves were obtained at all sites (Figure 1a). Minimum frequencies ranged from 0.4 to 0.7 Hz and maximum frequencies ranged from 10 to 30 Hz depending on the site. Non-linear inversion was performed and 1D and 2D S-wave velocity models were obtained. The 1D method penetrated to depths ranging from 200 to 500 m depending on the site (Figure 1b). The 2D method penetrated to a depth of 40 60 m and provided 400 1000 m cross sections along the levees (Figure 2). The interpretation focused on identifying zones beneath the levees or canal walls having low S-wave velocities corresponding to saturated, unconsolidated sands, or low-rigidity clays. Resultant S-wave velocity profiles

  20. Risk analysis of breakwater caisson under wave attack using load surface approximation

    Science.gov (United States)

    Kim, Dong Hyawn

    2014-12-01

    A new load surface based approach to the reliability analysis of caisson-type breakwater is proposed. Uncertainties of the horizontal and vertical wave loads acting on breakwater are considered by using the so-called load surfaces, which can be estimated as functions of wave height, water level, and so on. Then, the first-order reliability method (FORM) can be applied to determine the probability of failure under the wave action. In this way, the reliability analysis of breakwaters with uncertainties both in wave height and in water level is possible. Moreover, the uncertainty in wave breaking can be taken into account by considering a random variable for wave height ratio which relates the significant wave height to the maximum wave height. The proposed approach is applied numerically to the reliability analysis of caisson breakwater under wave attack that may undergo partial or full wave breaking.

  1. Effect of attenuation correction on surface amplitude distribution of wind waves

    Digital Repository Service at National Institute of Oceanography (India)

    Varkey, M.J.

    Some selected wave profiles recorded using a ship borne wave recorder are analysed to study the effect of attenuation correction on the distribution of the surface amplitudes. A new spectral width parameter is defined to account for wide band...

  2. Effect of phase coupling on surface amplitude distribution of wind waves

    Digital Repository Service at National Institute of Oceanography (India)

    Varkey, M.J.

    Nonlinear features of wind generated surface waves are considered here to be caused by nonrandomness (non-Uniform) in the phase spectrum. Nonrandomness in recorded waves, if present, would be generally obscured within the error level of observations...

  3. Waveform inversion of surface waves at geotechnical scale

    Science.gov (United States)

    Billien, M.; Maupin, V.

    2003-04-01

    The depth profile of the shear modulus in the Earth is commonly measured by analysing the dispersion of surface waves, and this at very different scales, from a few meters in geotechnique, to a few hundred km in seismology. In geotechnique, inverting seismograms for the shear modulus of the structure is a challenging problem due to the very large span of possible model parameters and to the highly non-linear relation between model and wavefield. We present here an analysis of how a global search algorithm can be used to solve this problem. The technique is based on comparing the data with complete synthetic seismograms and using a so-called neighbourhood algorithm to search in an efficient way for models which best fit the data. The synthetic seismograms are made in plane layered structures with the discrete wavenumber integration method. Multimode surface waves can be treated without extracting the modal dispersion curves, and models with decreasing velocity with depth can be analysed. The performance of the method is of course strongly dependent on the misfit function which is used to compare data and synthetics. In most cases, misfits calculated in the frequency domain lead to better results than misfits calculated in the time domain. Since the surface layers have a much larger influence on the waveforms than the parameters of the deeper layers, we found necessary to use the search algorithm in an iterative way, searching first for the velocity in the first layer, and then refining iteratively the profile with depth. Although global search methods with computation of full synthetic seismograms can of course not compete with linearised inversions of dispersion curves in terms of computation time, we show that they are feasible on an ordinary workstation in a reasonable amount of time, and can therefore be an alternative inversion method for complex datasets.

  4. The Effect of the Leeuwin Current on Offshore Surface Gravity Waves in Southwest Western Australia

    Science.gov (United States)

    Wandres, Moritz; Wijeratne, E. M. S.; Cosoli, Simone; Pattiaratchi, Charitha

    2017-11-01

    The knowledge of regional wave regimes is critical for coastal zone planning, protection, and management. In this study, the influence of the offshore current regime on surface gravity waves on the southwest Western Australian (SWWA) continental shelf was examined. This was achieved by coupling the three dimensional, free surface, terrain-following hydrodynamic Regional Ocean Modelling System (ROMS) and the third generation wave model Simulating WAves Nearshore (SWAN) using the Coupled Ocean-Atmosphere-WaveSediment Transport (COAWST) model. Different representative states of the Leeuwin Current (LC), a strong pole-ward flowing boundary current with a persistent eddy field along the SWWA shelf edge were simulated and used to investigate their influence on different large wave events. The coupled wave-current simulations were compared to wave only simulations, which represented scenarios in the absence of a background current field. Results showed that the LC and the eddy field significantly impact SWWA waves. Significant wave heights increased (decreased) when currents were opposing (aligning with) the incoming wave directions. During a fully developed LC system significant wave heights were altered by up to ±25% and wave directions by up to ±20°. The change in wave direction indicates that the LC may modify nearshore wave dynamics and consequently alter sediment patterns. Operational regional wave forecasts and hindcasts may give flawed predictions if wave-current interaction is not properly accounted for.

  5. Impacts of Ocean Waves on the Atmospheric Surface Layer: Simulations and Observations

    National Research Council Canada - National Science Library

    Sullivan, Peter P; McWilliams, James C; Melville, W. K

    2008-01-01

    ... planetary boundary layers (PBL). Efforts were focused on the effects of surface gravity waves on the near-surface dynamics, surface fluxes, and coupling between the atmospheric and oceanic PBLs...

  6. Enhanced Transmission of Light and Matter through Nanoapertures without Assistance of Surface Waves

    OpenAIRE

    Kukhlevsky, S. V.

    2006-01-01

    Subwavelength aperture arrays in thin metal films enable enhanced transmission of light and matter waves [for example, see T.W. Ebbesen et al., Nature (London) 391, 667 (1998) and E. Moreno et al., Phys. Rev. Lett. 95, 170406 (2005)]. The phenomenon relies on resonant excitation of the surface electron or matter waves. We show another mechanism that provides a great transmission enhancement not by coupling to the surface waves but by the interference of diffracted evanescent waves in the far-...

  7. XPS study of PBO fiber surface modified by incorporation of hydroxyl polar groups in main chains

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Tao; Hu Dayong; Jin Junhong; Yang Shenglin [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Material Science and Engineering, Donghua University, Shanghai 201620 (China); Li Guang, E-mail: lig@dhu.edu.cn [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Material Science and Engineering, Donghua University, Shanghai 201620 (China); Jiang Jianming [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Material Science and Engineering, Donghua University, Shanghai 201620 (China)

    2010-01-15

    Dihydroxy poly(p-phenylene benzobisoxazole) (DHPBO), a modified poly(p-phenylene benzoxazole) (PBO) polymer containing double hydroxyl groups in polymer chains, was synthesized by copolymerization of 4,6-diamino resorcinol dihydrochloride (DAR), purified terephthalic acid (TA) and 2,5-dihydroxyterephthalic acid (DHTA). DHPBO fibers were prepared by dry-jet wet-spinning method. The effects of hydroxyl polar groups on the surface elemental compositions of PBO fiber were investigated by X-ray photoelectron spectroscopy (XPS). The results show that the ratio of oxygen/carbon on the surface of DHPBO fibers is higher than that on the surface of PBO fibers, which indicates the content of polar groups on the surface of DHPBO fiber increase compared with PBO fiber.

  8. Electron paramagnetic resonance and dynamic nuclear polarization of char suspensions: surface science and oximetry

    DEFF Research Database (Denmark)

    Clarkson, R B; Odintsov, B M; Ceroke, P J

    1998-01-01

    ; they can be calibrated and used for oximetry. Biological stability and low toxicity make chars good sensors for in vivo measurements. Scalar and dipolar interactions of water protons at the surfaces of chars may be utilized to produce dynamic nuclear polarization (DNP) of the nuclear spin population...

  9. Analysis of method of polarization surveying of water surface oil pollution

    Science.gov (United States)

    Zhukov, B. S.

    1979-01-01

    A method of polarization surveying of oil films on the water surface is analyzed. Model calculations of contrasted oil and water obtained with different orientations of the analyzer are discussed. The model depends on the spectral range, water transparency and oil film, and the selection of observational direction.

  10. Impact of trophic state on the distribution of intact polar lipids in surface waters of lakes

    NARCIS (Netherlands)

    Bale, N.J.; Hopmans, E.C.; Schoon, P.; de Kluijver, A.; Downing, J.A.; Middelburg, J.J.; Sinninghe Damsté, J.S.; Schouten, S.

    2016-01-01

    We characterized the intact polar lipid (IPL) composition in the surface waters of 22 lakes from Minnesota and Iowa, ranging in trophic state between eutrophic and oligo-mesotrophic, to investigate the impact of trophic state on IPL composition. A high diversity of IPL classes was detected. Most IPL

  11. Upper-Mantle Shear Velocities beneath Southern California Determined from Long-Period Surface Waves

    OpenAIRE

    Polet, J.; Kanamori, H.

    1997-01-01

    We used long-period surface waves from teleseismic earthquakes recorded by the TERRAscope network to determine phase velocity dispersion of Rayleigh waves up to periods of about 170 sec and of Love waves up to about 150 sec. This enabled us to investigate the upper-mantle velocity structure beneath southern California to a depth of about 250 km. Ten and five earthquakes were used for Rayleigh and Love waves, respectively. The observed surface-wave dispersion shows a clear Love/Rayleigh-wave d...

  12. Mechanically Reconfigurable Single-Arm Spiral Antenna Array for Generation of Broadband Circularly Polarized Orbital Angular Momentum Vortex Waves.

    Science.gov (United States)

    Li, Long; Zhou, Xiaoxiao

    2018-03-23

    In this paper, a mechanically reconfigurable circular array with single-arm spiral antennas (SASAs) is designed, fabricated, and experimentally demonstrated to generate broadband circularly polarized orbital angular momentum (OAM) vortex waves in radio frequency domain. With the symmetrical and broadband properties of single-arm spiral antennas, the vortex waves with different OAM modes can be mechanically reconfigurable generated in a wide band from 3.4 GHz to 4.7 GHz. The prototype of the circular array is proposed, conducted, and fabricated to validate the theoretical analysis. The simulated and experimental results verify that different OAM modes can be effectively generated by rotating the spiral arms of single-arm spiral antennas with corresponding degrees, which greatly simplify the feeding network. The proposed method paves a reconfigurable way to generate multiple OAM vortex waves with spin angular momentum (SAM) in radio and microwave satellite communication applications.

  13. Coherence and polarization speckle generated by a rough-surfaced retardation plate depolarizer

    DEFF Research Database (Denmark)

    Ma, Ning; Hanson, Steen Grüner; Takeda, Mitsuo

    2015-01-01

    of position introducing random phase differences between the two orthogonal components of the electric vector. Under the assumption of Gaussian statistics with zero mean, the surface model for the depolarizer of the rough-surfaced retardation plate is obtained. The propagation of the modulated fields through...... any quadratic optical system is examined within the framework of the complex ABCD matrix theory to show how the degree of coherence and polarization of the beam changes on propagation, including propagation in free space...

  14. Correlation of Effective Dispersive and Polar Surface Energies in Heterogeneous Self-Assembled Monolayer Coatings

    DEFF Research Database (Denmark)

    Zhuang, Yanxin; Hansen, Ole

    2009-01-01

    grown oil oxidized (100) silicon Surfaces in a vapor phase process using five different precursors. Experimentally, effective surface energy components of the fluorocarbon self-assembled monolayers were determined from measured contact angles using the Owens-Wendt-Rabel-Kaelble method. We show......We show, theoretically, that the measured effective dispersive and polar surface energies of a heterogeneous Surface are correlated; the correlation, however, differs whether a Cassic or an Israelachvili and Gee model is assumed. Fluorocarbon self-assembled monolayers with varying coverage were...

  15. Effect of near-surface topography on high-frequency Rayleigh-wave propagation

    Science.gov (United States)

    Wang, Limin; Xu, Yixian; Xia, Jianghai; Luo, Yinhe

    2015-05-01

    Rayleigh waves, which are formed due to interference of P- and Sv-waves near the free surface, propagate along the free surface and vanish exponentially in the vertical direction. Their propagation is strongly influenced by surface topography. Due to the high resolution and precision requirements of near-surface investigations, the high-frequency Rayleigh waves are usually used for near-surface structural detecting. Although there are some numerical studies on high-frequency Rayleigh-wave propagation on topographic free surface, detailed analysis of characters of high-frequency Rayleigh-wave propagation on topographic free surface remains untouched. Hence, research of propagation of Rayleigh waves on complex topographic surface becomes critical for Rayleigh-wave methods in near-surface applications. To study the propagation of high-frequency Rayleigh waves on topographic free surface, two main topographic models are designed in this study. One of the models contains a depressed topographic surface, and another contains an uplifted topographic surface. We numerically simulate the propagation of high-frequency Rayleigh waves on these two topographic surfaces by finite-difference method. Soon afterwards, we analyze the propagation character of high-frequency Rayleigh waves on such topographic models, and compare the variations on its energy and frequency before and after passing the topographic region. At last, we discuss the relationship between the variations and topographical steepness of each model. Our numerical results indicate that influence of depressed topography for high-frequency Rayleigh waves is more distinct than influence of uplifted topography. Rayleigh waves produce new scattering body waves during passing the depressed topography with reduction of amplitude and loss of high-frequency components. Moreover, the steeper the depressed topography is, the more energy of Rayleigh waves is lost. The uplifted topography with gentle slope produces similar

  16. Viscoelasticity evaluation of rubber by surface reflection of supersonic wave.

    Science.gov (United States)

    Omata, Nobuaki; Suga, Takahiro; Furusawa, Hirokazu; Urabe, Shinichi; Kondo, Takeru; Ni, Qing-Qing

    2006-12-22

    The main characteristic of rubber is a viscoelasticity. So it is important to research the characteristic of the viscoelasticity of the high frequency band for the friction between a rubber material and the hard one with roughness, for instance, the tire and the road. As for the measurement of the viscoelasticity of rubber, DMA (dynamic mechanical analysis) is general. However, some problems are pointed out to the measurement of the high frequency band by DMA. Then, we evaluated the viscoelasticity characteristic by the supersonic wave measurement. However, attenuation of rubber is large, and when the viscoelasticity is measured by the supersonic wave therefore, it is inconvenient and limited in a past method by means of bottom reflection. In this report, we tried the viscoelasticity evaluation by the method of using complex surface reflection coefficient and we compared with the friction coefficient under wide-range friction velocity. As a result, some relationships had been found for two properties. We report the result that character of viscoelasticity of rubber was comparable to friction coefficient.

  17. Multimode Surface Wave Tomography Of Asia And Surroundings

    Science.gov (United States)

    Lebedev, S.; van der Hilst, R. D.

    We construct a large-scale, high-resolution, 3-D model of the upper mantle beneath Asia, Australia, and surrounding oceans. Automated Multimode Inversion of surface waves (Lebedev and Nolet, 2000) is used to extract the waveform phase information from the regional S and fundamental-mode wavetrains and relate it to structural per- turbations in the Earth. Efficient selection of the wavetrains uncontaminated by scat- tered waves ensures high accuracy of the measurements. Full automation allows us to constrain the tomographic model using a large waveform data set of about twenty thousand vertical-component seismograms and to achieve lateral resolution of 400- 700 km, varying with the local ray-path coverage. The tectonically diverse region of study encompasses units ranging from stable Archean cratons and the oldest ocean floor on Earth to currently opening backarc basins. The western half of the Pacific ``Ring of Fire" dominates the cross-sections down to 150 km depth. At greater depths, a pattern of prominent high-velocity anoma- lies is created by the deep roots of Precambrian continental units (Yangtze, India, Siberia, and Kazakhstan), oceanic lithosphere subducted in the Western Pacific, and the Indian lithosphere descending beneath Tibet. High-velocity continental roots are present beneath some Precambrian units but absent beneath others, depending on their tectonic history. Laterally, the roots can reach beyond the present extent of the overly- ing Archean-Proterozoic crust by as much as a few hundred kilometers.

  18. Multimode Surface Wave Tomography of Asia and Western Pacific.

    Science.gov (United States)

    Lebedev, S.; van der Hilst, R. D.

    2001-12-01

    We invert a few tens of thousand long-period seismograms and select about twenty thousand to constrain a large-scale, high-resolution, 3-D model of the upper mantle beneath Asia, Australia, and Western Pacific. Automated Multimode Inversion of surface waves (Lebedev and Nolet, 2000) is used to extract the waveform phase information from the regional S and fundamental mode wavetrains and relate it to structural perturbations in the Earth. Efficient selection of the wavetrains uncontaminated by scattered waves ensures high accuracy of our measurements. Full automation allows us to constrain the tomographic model using a very large waveform data set and to achieve lateral resolution of 300-700 km, varying with the local ray-path coverage. The tectonically diverse region of study encompasses units ranging from stable Archean cratons and the oldest ocean floor on Earth to currently opening backarc basins. The western half of the Pacific ``Ring of Fire'' dominates the cross-sections down to 150 km depth. At greater depths, a pattern of prominent high-velocity anomalies is created by the deep roots of Precambrian continental units, oceanic lithosphere subducted in the Western Pacific, and the Indian lithosphere descending beneath Tibet.

  19. Surface Acoustic Wave (SAW Resonators for Monitoring Conditioning Film Formation

    Directory of Open Access Journals (Sweden)

    Siegfried Hohmann

    2015-05-01

    Full Text Available We propose surface acoustic wave (SAW resonators as a complementary tool for conditioning film monitoring. Conditioning films are formed by adsorption of inorganic and organic substances on a substrate the moment this substrate comes into contact with a liquid phase. In the case of implant insertion, for instance, initial protein adsorption is required to start wound healing, but it will also trigger immune reactions leading to inflammatory responses. The control of the initial protein adsorption would allow to promote the healing process and to suppress adverse immune reactions. Methods to investigate these adsorption processes are available, but it remains difficult to translate measurement results into actual protein binding events. Biosensor transducers allow user-friendly investigation of protein adsorption on different surfaces. The combination of several transduction principles leads to complementary results, allowing a more comprehensive characterization of the adsorbing layer. We introduce SAW resonators as a novel complementary tool for time-resolved conditioning film monitoring. SAW resonators were coated with polymers. The adsorption of the plasma proteins human serum albumin (HSA and fibrinogen onto the polymer-coated surfaces were monitored. Frequency results were compared with quartz crystal microbalance (QCM sensor measurements, which confirmed the suitability of the SAW resonators for this application.

  20. A Microring Temperature Sensor Based on the Surface Plasmon Wave

    Directory of Open Access Journals (Sweden)

    Wenchao Li

    2015-01-01

    Full Text Available A structure of microring sensor suitable for temperature measurement based on the surface plasmon wave is put forward in this paper. The sensor uses surface plasmon multilayer waveguiding structure in the vertical direction and U-shaped microring structure in the horizontal direction and utilizes SOI as the thermal material. The transfer function derivation of the structure of surface plasmon microring sensor is according to the transfer matrix method. While the change of refractive index of Si is caused by the change of ambient temperature, the effective refractive index of the multilayer waveguiding structure is changed, resulting in the drifting of the sensor output spectrum. This paper focuses on the transmission characteristics of multilayer waveguide structure and the impact on the output spectrum caused by refractive index changes in temperature parts. According to the calculation and simulation, the transmission performance of the structure is stable and the sensitivity is good. The resonance wavelength shift can reach 0.007 μm when the temperature is increased by 100 k and FSR can reach about 60 nm. This structure achieves a high sensitivity in the temperature sense taking into account a wide range of filter frequency selections, providing a theoretical basis for the preparation of microoptics.

  1. Reconfigurable micromachined antenna with polarization diversity for mm-wave applications

    KAUST Repository

    Sallam, Mai O.

    2012-03-01

    In this paper a novel MEMS antenna with reconfigurable polarization operating at 60 GHz is presented. This antenna can provide vertical linear polarization, horizontal linear polarization, left hand circular polarization (LHCP), or right hand circular polarization (RHCP) based on the states of the switches present in the feeding network. The proposed antenna is characterized by having its radiating elements isolated from the feeding circuitry via a ground plane without the need for wafer bonding or hybrid integration. Such advantage results in good electric performance while maintains low fabrication cost. The antenna parameters are optimized using HFSS and the results are cross-validated using CST. The good agreement between the two simulators, confirms that the proposed antenna enjoys attractive radiation characteristics for all polarization senses. © 2012 IEEE.

  2. The energy and temporal characteristics of orthogonal polarized waves generated by a transversely-excited pulsed CO/sub 2/ laser

    Energy Technology Data Exchange (ETDEWEB)

    Bertel, I.M.; Churakov, V.V.; Petukhov, V.O.; Prokopov, A.P.; Trushin, S.A.; Voitovich, A.P.

    1980-01-01

    The competition of orthogonally-polarized waves with various differences in the wave Q-factors and active medium pressures is studied. The possibility of controlling the parameters of a pulsed CO/sub 2/ laser by changing the value of the amplitude anisotropy of the cavity is demonstrated. The duration of the emission pulse for one of two orthogonal polarizations was reduced by virtually 50%.

  3. Kinetic computer modeling of microwave surface-wave plasma production

    International Nuclear Information System (INIS)

    Ganachev, Ivan P.

    2004-01-01

    Kinetic computer plasma modeling occupies an intermediate position between the time consuming rigorous particle dynamic simulation and the fast but rather rough cold- or warm-plasma fluid models. The present paper reviews the kinetic modeling of microwave surface-wave discharges with accent on recent kinetic self-consistent models, where the external input parameters are reduced to the necessary minimum (frequency and intensity of the applied microwave field and pressure and geometry of the discharge vessel). The presentation is limited to low pressures, so that Boltzmann equation is solved in non-local approximation and collisional electron heating is neglected. The numerical results reproduce correctly the bi-Maxwellian electron energy distribution functions observed experimentally. (author)

  4. Development of Multi-chroic Millimeter-wave Polarization Sensitive Detector Arrays

    Data.gov (United States)

    National Aeronautics and Space Administration — Improved measurements of the polarization of the Cosmic Microwave Background (CMB) will improve our understanding of both cosmology and fundamental physics....

  5. A Surface Wave's View of the Mid-Continent Rift

    Science.gov (United States)

    Foster, A. E.; Darbyshire, F. A.; Schaeffer, A. J.

    2017-12-01

    The presence of the Mid-Continent Rift (MCR), a 1.1Ga failed rift in central North America, raises many questions. We address the following: what lasting effects has it had on the continental lithosphere? Though many studies have looked at the area with a variety of data types, the combination of USArray Transportable Array stations to the south, permanent and temporary Canadian stations to the north, and SPREE stations in strategic locations crossing the rift provide a new opportunity for a regional surface-wave study. We select 80 stations with roughly 200 km spacing, resulting in dense path coverage of a broad area centered on the MCR. We use teleseismic data for all earthquakes from January 2005-August 2016 with a magnitude greater than 6.0, amounting to over 1200 events, and we make Rayleigh wave two-station dispersion measurements for all station pairs with suitable event-station geometry. We invert these measurements for anisotropic phase-velocity maps at periods of 20-200 s, yielding information not only on the wave speed but also the current fabric of the lithosphere, a complicated record of strain from formation, through modification from orogeny, attempted rifting, and hotspot interaction, to present day plate motion. We observe a clear signature of the MCR at short (20-25 s) periods, with the slowest phase-velocity anomaly in the region aligning with the strongest gravity anomaly. At increasing periods, and thus greater depths, this slowest anomaly shifts to beneath the center of Lake Superior (30-40 s). Eventually, it appears to merge with a slow anomaly to the north associated with the Nipigon Embayment, and contrasts sharply with an adjacent fast anomaly in the western Superior Province. In our preliminary anisotropy results, we observe weak anisotropy at the latitude of the MCR and to the south, whereas to the north of the MCR we find strong anisotropy. This is similar to the spatial variations in magnitude of delay times from shear-wave splitting

  6. Fluorine-Terminated Diamond Surfaces as Dense Dipole Lattices: The Electrostatic Origin of Polar Hydrophobicity.

    Science.gov (United States)

    Mayrhofer, Leonhard; Moras, Gianpietro; Mulakaluri, Narasimham; Rajagopalan, Srinivasan; Stevens, Paul A; Moseler, Michael

    2016-03-30

    Despite the pronounced polarity of C-F bonds, many fluorinated carbon compounds are hydrophobic: a controversial phenomenon known as "polar hydrophobicity". Here, its underlying microscopic mechanisms are explored by ab initio calculations of fluorinated and hydrogenated diamond (111) surfaces interacting with single water molecules. Gradient- and van der Waals-corrected density functional theory simulations reveal that "polar hydrophobicity" of the fully fluorinated surfaces is caused by a negligible surface/water electrostatic interaction. The densely packed C-F surface dipoles generate a short-range electric field that decays within the core repulsion zone of the surface and hence vanishes in regions accessible by adsorbates. As a result, water physisorption on fully F-terminated surfaces is weak (adsorption energies Ead 0.2 eV) that is dominated by electrostatic interactions. The suppression of electrostatic interactions also holds for perfluorinated molecular carbon compounds, thus explaining the prevalent hydrophobicity of fluorocarbons. In general, densely packed polar terminations do not always lead to short-range electric fields. For example, surfaces with substantial electron density spill-out give rise to electric fields with a much slower decay. However, electronic spill-out is limited in F/H-terminated carbon materials. Therefore, our ab initio results can be reproduced and rationalized by a simple classical point-charge model. Consequently, classical force fields can be used to study the wetting of F/H-terminated diamond, revealing a pronounced correlation between adsorption energies of single H2O molecules and water contact angles.

  7. IDENTIFYING SURFACE CHANGES ON HRSC IMAGES OF THE MARS SOUTH POLAR RESIDUAL CAP (SPRC

    Directory of Open Access Journals (Sweden)

    A. R. D. Putri

    2016-06-01

    Full Text Available The surface of Mars has been an object of interest for planetary research since the launch of Mariner 4 in 1964. Since then different cameras such as the Viking Visual Imaging Subsystem (VIS, Mars Global Surveyor (MGS Mars Orbiter Camera (MOC, and Mars Reconnaissance Orbiter (MRO Context Camera (CTX and High Resolution Imaging Science Experiment (HiRISE have been imaging its surface at ever higher resolution. The High Resolution Stereo Camera (HRSC on board of the European Space Agency (ESA Mars Express, has been imaging the Martian surface, since 25th December 2003 until the present-day. HRSC has covered 100 % of the surface of Mars, about 70 % of the surface with panchromatic images at 10-20 m/pixel, and about 98 % at better than 100 m/pixel (Neukum et. al., 2004, including the polar regions of Mars. The Mars polar regions have been studied intensively recently by analysing images taken by the Mars Express and MRO missions (Plaut et al., 2007. The South Polar Residual Cap (SPRC does not change very much in volume overall but there are numerous examples of dynamic phenomena associated with seasonal changes in the atmosphere. In particular, we can examine the time variation of layers of solid carbon dioxide and water ice with dust deposition (Bibring, 2004, spider-like channels (Piqueux et al., 2003 and so-called Swiss Cheese Terrain (Titus et al., 2004. Because of seasonal changes each Martian year, due to the sublimation and deposition of water and CO2 ice on the Martian south polar region, clearly identifiable surface changes occur in otherwise permanently icy region. In this research, good quality HRSC images of the Mars South Polar region are processed based on previous identification as the optimal coverage of clear surfaces (Campbell et al., 2015. HRSC images of the Martian South Pole are categorized in terms of quality, time, and location to find overlapping areas, processed into high quality Digital Terrain Models (DTMs and

  8. A novel ultrasonic surface machining tool utilizing elastic traveling waves.

    Science.gov (United States)

    Ji, Ruinan; Jin, Jiamei; Wang, Liang; Zhang, Jianhui

    2017-09-01

    With the rapid development of modern industrial technology and high performance technology products, ultra-precision machining technology becomes increasingly important. However, joint clearance of kinematic pairs, lack of feeding accuracy and overlarge contact stress still limit the further improvement of ultra-precision machining technology. In this study, a novel surface machining method utilizing structural elastic waves was proposed, and a machining tool using the piezoelectric actuating principle was presented for verifying the proposed method. Two vibration modes with a phase shift of π/2 in both space and time domains are exited simultaneously in the elliptical motion of points on the structural surface. By means of adjusting driving signal parameters, such as frequency, voltage amplitude and phase shift, different machining performances could be achieved. The configuration and working vibration modes of the proposed machining tool were firstly calculated by the finite element method, and then the optimal working frequency of the machining tool prototype was determined by vibration characteristic experiments. At last, machining characteristic experiments were conducted to validate the proposed machining method. Experimental results showed that the minimum working contact force between the machining tool and workpiece was 1N, and the chipped depth of 1.93μm was achieved at the same contact force after machining for 5min. And at the conditions of the contact force of 6N, two driving voltages of 400V pp with a phase shift of π/2, and machining time of 5min, the prototype could achieve to machine the workpiece most efficiently and the roughness of the machined workpiece surface could be reached approximating 0.20μm. In conclusion, this proposed machining method could achieve a good quality machined surface with low residual stress and little damage by applying low contact force. Furthermore, it also had the advantage of no joint clearance error due to no

  9. Covalent Surface Modification of Silicon Oxides with Alcohols in Polar Aprotic Solvents.

    Science.gov (United States)

    Lee, Austin W H; Gates, Byron D

    2017-09-05

    Alcohol-based monolayers were successfully formed on the surfaces of silicon oxides through reactions performed in polar aprotic solvents. Monolayers prepared from alcohol-based reagents have been previously introduced as an alternative approach to covalently modify the surfaces of silicon oxides. These reagents are readily available, widely distributed, and are minimally susceptible to side reactions with ambient moisture. A limitation of using alcohol-based compounds is that previous reactions required relatively high temperatures in neat solutions, which can degrade some alcohol compounds or could lead to other unwanted side reactions during the formation of the monolayers. To overcome these challenges, we investigate the condensation reaction of alcohols on silicon oxides carried out in polar aprotic solvents. In particular, propylene carbonate has been identified as a polar aprotic solvent that is relatively nontoxic, readily accessible, and can facilitate the formation of alcohol-based monolayers. We have successfully demonstrated this approach for tuning the surface chemistry of silicon oxide surfaces with a variety of alcohol containing compounds. The strategy introduced in this research can be utilized to create silicon oxide surfaces with hydrophobic, oleophobic, or charged functionalities.

  10. Effect of magnetic polarity on surface roughness during magnetic field assisted EDM of tool steel

    Science.gov (United States)

    Efendee, A. M.; Saifuldin, M.; Gebremariam, MA; Azhari, A.

    2018-04-01

    Electrical discharge machining (EDM) is one of the non-traditional machining techniques where the process offers wide range of parameters manipulation and machining applications. However, surface roughness, material removal rate, electrode wear and operation costs were among the topmost issue within this technique. Alteration of magnetic device around machining area offers exciting output to be investigated and the effects of magnetic polarity on EDM remain unacquainted. The aim of this research is to investigate the effect of magnetic polarity on surface roughness during magnetic field assisted electrical discharge machining (MFAEDM) on tool steel material (AISI 420 mod.) using graphite electrode. A Magnet with a force of 18 Tesla was applied to the EDM process at selected parameters. The sparks under magnetic field assisted EDM produced better surface finish than the normal conventional EDM process. At the presence of high magnetic field, the spark produced was squeezed and discharge craters generated on the machined surface was tiny and shallow. Correct magnetic polarity combination of MFAEDM process is highly useful to attain a high efficiency machining and improved quality of surface finish to meet the demand of modern industrial applications.

  11. Observation of the spin-polarized surface state in a noncentrosymmetric superconductor BiPd.

    Science.gov (United States)

    Neupane, Madhab; Alidoust, Nasser; Hosen, M Mofazzel; Zhu, Jian-Xin; Dimitri, Klauss; Xu, Su-Yang; Dhakal, Nagendra; Sankar, Raman; Belopolski, Ilya; Sanchez, Daniel S; Chang, Tay-Rong; Jeng, Horng-Tay; Miyamoto, Koji; Okuda, Taichi; Lin, Hsin; Bansil, Arun; Kaczorowski, Dariusz; Chou, Fangcheng; Hasan, M Zahid; Durakiewicz, Tomasz

    2016-11-07

    Recently, noncentrosymmetric superconductor BiPd has attracted considerable research interest due to the possibility of hosting topological superconductivity. Here we report a systematic high-resolution angle-resolved photoemission spectroscopy (ARPES) and spin-resolved ARPES study of the normal state electronic and spin properties of BiPd. Our experimental results show the presence of a surface state at higher-binding energy with the location of Dirac point at around 700 meV below the Fermi level. The detailed photon energy, temperature-dependent and spin-resolved ARPES measurements complemented by our first-principles calculations demonstrate the existence of the spin-polarized surface states at high-binding energy. The absence of such spin-polarized surface states near the Fermi level negates the possibility of a topological superconducting behaviour on the surface. Our direct experimental observation of spin-polarized surface states in BiPd provides critical information that will guide the future search for topological superconductivity in noncentrosymmetric materials.

  12. Wave particle interactions in the high-altitude polar cusp: a Cluster case study

    Directory of Open Access Journals (Sweden)

    B. Grison

    2005-12-01

    Full Text Available On 23 March 2002, the four Cluster spacecraft crossed in close configuration (~100 km separation the high-altitude (10 RE cusp region. During a large part of the crossing, the STAFF and EFW instruments have detected strong electromagnetic wave activity at low frequencies, especially when intense field-aligned proton fluxes were detected by the CIS/HIA instrument. In all likelihood, such fluxes correspond to newly-reconnected field lines. A focus on one of these ion injection periods highlights the interaction between waves and protons. The wave activity has been investigated using the k-filtering technique. Experimental dispersion relations have been built in the plasma frame for the two most energetic wave modes. Results show that kinetic Alfvén waves dominate the electromagnetic wave spectrum up to 1 Hz (in the spacecraft frame. Above 0.8 Hz, intense Bernstein waves are also observed. The close simultaneity observed between the wave and particle events is discussed as an evidence for local wave generation. A mechanism based on current instabilities is consistent with the observations of the kinetic Alfvén waves. A weak ion heating along the recently-opened field lines is also suggested from the examination of the ion distribution functions. During an injection event, a large plasma convection motion, indicative of a reconnection site location, is shown to be consistent with the velocity perturbation induced by the large-scale Alfvén wave simultaneously detected.

  13. Dispersion analysis of passive surface-wave noise generated during hydraulic-fracturing operations

    Science.gov (United States)

    Forghani-Arani, Farnoush; Willis, Mark; Snieder, Roel; Haines, Seth S.; Behura, Jyoti; Batzle, Mike; Davidson, Michael

    2014-01-01

    Surface-wave dispersion analysis is useful for estimating near-surface shear-wave velocity models, designing receiver arrays, and suppressing surface waves. Here, we analyze whether passive seismic noise generated during hydraulic-fracturing operations can be used to extract surface-wave dispersion characteristics. Applying seismic interferometry to noise measurements, we extract surface waves by cross-correlating several minutes of passive records; this approach is distinct from previous studies that used hours or days of passive records for cross-correlation. For comparison, we also perform dispersion analysis for an active-source array that has some receivers in common with the passive array. The active and passive data show good agreement in the dispersive character of the fundamental-mode surface-waves. For the higher mode surface waves, however, active and passive data resolve the dispersive properties at different frequency ranges. To demonstrate an application of dispersion analysis, we invert the observed surface-wave dispersion characteristics to determine the near-surface, one-dimensional shear-wave velocity.

  14. Detection of defects and evaluation of material deterioration using surface wave technique

    International Nuclear Information System (INIS)

    Yokono, Yoshikazu; Yoshiara, Toshikatsu; Suetsugu, Jun; Imanaka, Takuichi

    1996-01-01

    It is very important to detect surface damage and evaluate deterioration of material surface because of their influences on mechanical properties of materials. In general, magnetic particle testing, liquid penetrant testing and eddy current testing are commonly used for detecting surface flaws. These methods, however, are neither effective for estimating flaw height nor for evaluating material deterioration. In this paper the authors apply surface wave propagating along the test surface for these purposes. The surface wave (Rayleigh wave) propagates only near the surface layer in the order of one wave length. In other words, the lower the frequency, the deeper the penetration depth of the surface wave. Accordingly, they can select the frequency considering the inspection purpose. On the other hand, when surface wave having broad-band frequency propagates along the surface of a specimen, higher frequency ultrasound propagates very close to the surface and lower frequency ultrasound propagates deeper in the specimen. Hence, frequency analysis is expected to be effective for estimating upper edge of flaw. Surface wave is also very sensitive to material surface properties such as existence of voids or micro cracks. Acoustic characteristics such as sound velocity, attenuation and other feature parameters are influenced by the variation of the material properties. Hence, material deterioration can be evaluated by the acoustic features

  15. Enabling surface nuclear magnetic resonance at high-noise environments using a pre-polarization pulse

    Science.gov (United States)

    Lin, Tingting; Yang, Yujing; Teng, Fei; Müller-Petke, Mike

    2018-02-01

    The technique of surface nuclear magnetic resonance (SNMR) has been widely used for hydrological investigations in recent years. Unfortunately, the detected SNMR signals are limited to tens of nanovolts and are thus susceptible to environmental noise. While pre-polarization pulses to enhance the detected signal amplitudes are common in laboratory applications, SNMR field testing has only utilized excitation pulses until now. In conducting measurements in China, we demonstrate that adding a pre-polarization field to the SNMR pulse sequence is feasible and allows for the reliable detection of SNMR signals in noisy scenarios that otherwise prohibit signal detection. We introduce a forward modelling for pre-polarization using SNMR and present a three-layer model obtained from inverse modelling that satisfies the observed data from the field experiment. We expect this development to open up new applications for SNMR technology, especially in high-noise level places, such as active mines.

  16. The effects of two counterpropagating surface acoustic wave beams on single electron acoustic charge transport

    International Nuclear Information System (INIS)

    He Jianhong; Guo Huazhong; Song Li; Zhang Wei; Gao Jie; Lu Chuan

    2010-01-01

    We present a comprehensive study of the effects of two counterpropagating surface acoustic waves on the acoustoelectric current of single electron transport devices. A significant improvement in the accuracy of current quantization is achieved as a result of an additional surface acoustic wave beam. The experiments reveal the sinusoidally periodical modulation in the acoustoelectric current characteristic as a function of the relative phase of the two surface acoustic wave beams. Besides, by using standing surface acoustic waves, the acoustoelectric current is detected which we consider as the so-called anomalous acoustoelectric current produced by acoustic wave mechanical deformations. This kind current is contributed to one component of the acoustoelectric current in surface acoustic wave device, which could enable us to establish a more adequate description of acoustoelectric effects on single-electron acoustic charge transport.

  17. [The research of the relationship between snow properties and the bidirectional polarized reflectance from snow surface].

    Science.gov (United States)

    Sun, Zhong-Qiu; Wu, Zheng-Fang; Zhao, Yun-Sheng

    2014-10-01

    In the context of remote sensing, the reflectance of snow is a key factor for accurate inversion for snow properties, such as snow grain size, albedo, because of it is influenced by the change of snow properties. The polarized reflectance is a general phenomenon during the reflected progress in natural incident light In this paper, based on the correct measurements for the multiple-angle reflected property of snow field in visible and near infrared wavelength (from 350 to 2,500 nm), the influence of snow grain size and wet snow on the bidirectional polarized property of snow was measured and analyzed. Combining the results measured in the field and previous conclusions confirms that the relation between polarization and snow grain size is obvious in infrared wavelength (at about 1,500 nm), which means the degree of polarization increasing with an increase of snow grain size in the forward scattering direction, it is because the strong absorption of ice near 1,500 nm leads to the single scattering light contributes to the reflection information obtained by the sensor; in other word, the larger grain size, the more absorption accompanying the larger polarization in forward scattering direction; we can illustrate that the change from dry snow to wet snow also influences the polarization property of snow, because of the water on the surface of snow particle adheres the adjacent particles, that means the wet snow grain size is larger than the dry snow grain size. Therefore, combining the multiple-angle polarization with reflectance will provide solid method and theoretical basis for inversion of snow properties.

  18. Influence of High Speed Repetition of Pulsed Streamer Discharge Produced by Polarity-Reversed Traveling Wave on NO Oxidation

    Science.gov (United States)

    Matsuda, Eiji; Kadowaki, Kazunori; Nishimoto, Sakae; Kitani, Isamu

    This paper describes experimental results of NO removal from a simulated exhausted gas using a barrier-type plasma reactor subjected to reciprocal traveling wave voltage pulses. A pulse-forming cable was charged and then grounded at one end without any resistance, so that a traveling wave reciprocated along the cable with a change in its polarity because the traveling wave was negatively reflected at the grounded-end. Transient discharge light between point-plane electrodes with a glass barrier was observed using a gated image-intensifier. Photographs of the transient discharge light indicated that many streamer channels extended widely in the gap at the initial stage in the voltage oscillation, while only an intense discharge channel was observed at the latter stage. NO removal tests were carried out using the reciprocal pulse generator and a coaxial plasma reactor with a cylindrical glass-barrier. Results indicated that the discharges at the first and the second polarity reversals contributed largely to the oxidation reaction from NO into NO2, whereas the contribution of the subsequent discharges in the latter stage to NO removal was small.

  19. Hydrogenated amorphous silicon nitride photonic crystals for improved-performance surface electromagnetic wave biosensors.

    Science.gov (United States)

    Sinibaldi, Alberto; Descrovi, Emiliano; Giorgis, Fabrizio; Dominici, Lorenzo; Ballarini, Mirko; Mandracci, Pietro; Danz, Norbert; Michelotti, Francesco

    2012-10-01

    We exploit the properties of surface electromagnetic waves propagating at the surface of finite one dimensional photonic crystals to improve the performance of optical biosensors with respect to the standard surface plasmon resonance approach. We demonstrate that the hydrogenated amorphous silicon nitride technology is a versatile platform for fabricating one dimensional photonic crystals with any desirable design and operating in a wide wavelength range, from the visible to the near infrared. We prepared sensors based on photonic crystals sustaining either guided modes or surface electromagnetic waves, also known as Bloch surface waves. We carried out for the first time a direct experimental comparison of their sensitivity and figure of merit with surface plasmon polaritons on metal layers, by making use of a commercial surface plasmon resonance instrument that was slightly adapted for the experiments. Our measurements demonstrate that the Bloch surface waves on silicon nitride photonic crystals outperform surface plasmon polaritons by a factor 1.3 in terms of figure of merit.

  20. Effect of irregularity on torsional surface waves in an initially ...

    Indian Academy of Sciences (India)

    propagation of seismic waves is available in Ewing et al. (1957). The propagation of Love waves in water-saturated soil underlain by a heterogeneous elastic medium has been discussed by Chakraborty and Dey (1982). Dey et al. (1996) studied propa- gation of Love waves in heterogeneous crust over a heterogeneous ...

  1. Variational derivation of KdV-type of models for surface water waves

    NARCIS (Netherlands)

    van Groesen, Embrecht W.C.; Andonowati, A.

    2007-01-01

    Using the Hamiltonian formulation of surface waves, we approximate the kinetic energy and restrict the governing generalized action principle to a submanifold of uni-directional waves. Different from the usual method of using a series expansion in parameters related to wave height and wavelength,

  2. Shear wave velocity structure in North America from large-scale waveform inversions of surface waves

    Science.gov (United States)

    Alsina, D.; Woodward, R.L.; Snieder, R.K.

    1996-01-01

    A two-step nonlinear and linear inversion is carried out to map the lateral heterogeneity beneath North America using surface wave data. The lateral resolution for most areas of the model is of the order of several hundred kilometers. The most obvious feature in the tomographic images is the rapid transition between low velocities in the technically active region west of the Rocky Mountains and high velocities in the stable central and eastern shield of North America. The model also reveals smaller-scale heterogeneous velocity structures. A high-velocity anomaly is imaged beneath the state of Washington that could be explained as the subducting Juan de Fuca plate beneath the Cascades. A large low-velocity structure extends along the coast from the Mendocino to the Rivera triple junction and to the continental interior across the southwestern United States and northwestern Mexico. Its shape changes notably with depth. This anomaly largely coincides with the part of the margin where no lithosphere is consumed since the subduction has been replaced by a transform fault. Evidence for a discontinuous subduction of the Cocos plate along the Middle American Trench is found. In central Mexico a transition is visible from low velocities across the Trans-Mexican Volcanic Belt (TMVB) to high velocities beneath the Yucatan Peninsula. Two elongated low-velocity anomalies beneath the Yellowstone Plateau and the eastern Snake River Plain volcanic system and beneath central Mexico and the TMVB seem to be associated with magmatism and partial melting. Another low-velocity feature is seen at depths of approximately 200 km beneath Florida and the Atlantic Coastal Plain. The inversion technique used is based on a linear surface wave scattering theory, which gives tomographic images of the relative phase velocity perturbations in four period bands ranging from 40 to 150 s. In order to find a smooth reference model a nonlinear inversion based on ray theory is first performed. After

  3. Reconstruction of surface waves using super virtual interferometry: an example from the Forsmark site, Sweden

    Science.gov (United States)

    Xu, Zhuo; Juhlin, Christopher; Han, Liguo; Zhang, Fengjiao

    2017-10-01

    Seismic interferometry is a technique that enables the extraction of the seismic impulse response (Green's function) between two receivers. The retrieved response is generally dominated by surface waves when sources are located at or near the surface of the Earth. In onshore seismic exploration, dealing with complex near-surface conditions is one of the main challenges for seismic data processing. In some cases, seismic interferometry can be used for suppressing surface waves without the use of a priori near-surface velocity model. Aside from being an effective tool for surface wave attenuation, the reconstructed surface waves generated by seismic interferometry contain useful information about near-surface heterogeneities and can be used to characterize the near-surface velocity field. In this study, we apply super virtual interferometry (SVI) to a real onshore data set from the Forsmark site, central Sweden, with the primary aim of characterizing shallow-subsurface structure. This is accomplished by improving the dispersion characteristics of the surface waves. We also show that SVI performs better than conventional correlation-type and convolution-type interferometry when reconstructing surface waves, both in synthetic and real data. We use the dispersive behaviour of the reconstructed surface waves to infer the geological structure of the shallow subsurface.

  4. Dark Material at the Surface of Polar Crater Deposits on Mercury

    Science.gov (United States)

    Neumann, Gregory A.; Cavanaugh, John F.; Sun, Xiaoli; Mazarico, Erwan; Smith, David E.; Zuber, Maria T.; Solomon, Sean C.; Paige, Daid A.

    2012-01-01

    Earth-based radar measurements [1-3] have yielded images of radar-bright material at the poles of Mercury postulated to be near-surface water ice residing in cold traps on the permanently shadowed floors of polar impact craters. The Mercury Laser Altimeter (MLA) on board the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft has now mapped much of the north polar region of Mercury [4] (Fig. 1). Radar-bright zones lie within polar craters or along poleward-facing scarps lying mainly in shadow. Calculations of illumination with respect to solid-body motion [5] show that at least 0.5% of the surface area north of 75deg N lies in permanent shadow, and that most such permanently shadowed regions (PSRs) coincide with radar-bright regions. MLA transmits a 1064-nm-wavelength laser pulse at 8 Hz, timing the leading and trailing edges of the return pulse. MLA can in some cases infer energy and thereby surface reflectance at the laser wavelength from the returned pulses. Surficial exposures of water ice would be optically brighter than the surroundings, but persistent surface water ice would require temperatures over all seasons to remain extremely low (Mercury s eccentric orbit, 3:2 spin-orbit resonance, and near-zero obliquity generally do not support such conditions in all permanently shadowed craters but suggest that water ice buried near the surface ( 1 Gy. We describe measurements of reflectivity derived from MLA pulse returns. These reflectivity data show that surface materials in the shadowed regions are darker than their surroundings, enough to strongly attenuate or extinguish laser returns. Such measurements appear to rule out widespread surface exposures of water ice. We consider explanations for the apparent low reflectivity of these regions involving other types of volatile deposit.

  5. Cloud Masking and Surface Temperature Distribution in the Polar Regions Using AVHRR and other Satellite Data

    Science.gov (United States)

    Comiso, Joey C.

    1995-01-01

    Surface temperature is one of the key variables associated with weather and climate. Accurate measurements of surface air temperatures are routinely made in meteorological stations around the world. Also, satellite data have been used to produce synoptic global temperature distributions. However, not much attention has been paid on temperature distributions in the polar regions. In the polar regions, the number of stations is very sparse. Because of adverse weather conditions and general inaccessibility, surface field measurements are also limited. Furthermore, accurate retrievals from satellite data in the region have been difficult to make because of persistent cloudiness and ambiguities in the discrimination of clouds from snow or ice. Surface temperature observations are required in the polar regions for air-sea-ice interaction studies, especially in the calculation of heat, salinity, and humidity fluxes. They are also useful in identifying areas of melt or meltponding within the sea ice pack and the ice sheets and in the calculation of emissivities of these surfaces. Moreover, the polar regions are unique in that they are the sites of temperature extremes, the location of which is difficult to identify without a global monitoring system. Furthermore, the regions may provide an early signal to a potential climate change because such signal is expected to be amplified in the region due to feedback effects. In cloud free areas, the thermal channels from infrared systems provide surface temperatures at relatively good accuracies. Previous capabilities include the use of the Temperature Humidity Infrared Radiometer (THIR) onboard the Nimbus-7 satellite which was launched in 1978. Current capabilities include the use of the Advance Very High Resolution Radiometer (AVHRR) aboard NOAA satellites. Together, these two systems cover a span of 16 years of thermal infrared data. Techniques for retrieving surface temperatures with these sensors in the polar regions have

  6. Diversiform hybrid-polarization surface plasmon polaritons in a dielectric–metal metamaterial

    Directory of Open Access Journals (Sweden)

    Q. Zhang

    2017-04-01

    Full Text Available Hybrid-polarization surface plasmon polaritons (HSPPs at the interface between an isotropic medium and a one-dimensional metal–dielectric metamaterial (MM were discussed, where the metal-layer permittivity was described with the improved Drude model. From the obtained dispersion equations, we predicated five types of HSPPs. One type is the Dyakonov-like surface polariton and another type is the tradition-like surface polarton. The others are new types of HSPPs. We establish a numerical simulation method of the attenuated total reflection (ATR measurement to examine these HSPPs. The results from the ATR spectra are consistent with those from the dispersion equations and indicate the different polarization features of these HSPPs. The numerical results also demonstrate that the observation of each type of HSPPs requires different conditions dictated by the material parameters and the polarization direction of incident light used in the ATR spectra. These results may further widen the space of potential applications of surface plasmon polaritons.

  7. High quality broadband spatial reflections of slow Rayleigh surface acoustic waves modulated by a graded grooved surface

    KAUST Repository

    Xu, Yanlong

    2015-01-21

    We report high quality broadband spatial reflections of Rayleigh surface acoustic waves (SAWs) through a graded grooved surface. High quality means that no wave is allowed to transmit and the incident wave is nearly all reflected to the input side. The graded grooved surface is structured by drilling one dimensional array of graded grooves with increased depths on a flat surface. We investigate SAW dispersion relations, wave field distribution at several typical SAW wavelengths, and time evolution of a Gaussian pulse through the graded grooved surface. Results show that the input broadband Rayleigh SAWs can be slowed, spatially enhanced and stopped, and finally reflected to the input side. The study suggests that engraving the flat surface can be used as an efficient and economical way to manipulate Rayleigh SAWs, which has potential application in novel SAW devices such as filters, reflectors, sensors, energy harvesters, and diodes.

  8. Scattering of X-rays on the surface acoustic wave in the case of grazing geometry

    CERN Document Server

    Mkrtchyan, A R; Petrosian, A

    2000-01-01

    The scattering of X-rays on a crystal is considered in grazing geometry when a surface acoustic wave is excited normal to the diffraction vector. The intensity of wave field at finite distance from crystal to detector is obtained. It is shown that in the presence of surface acoustic wave the magnitude of the main peak of specular reflected diffracted wave intensity decreases and intensity of satellites increases. The main peak of specular reflected diffracted wave intensity is split up as the grazing observation angle increases.

  9. Analysis of the multipactor effect in circular waveguides excited by two orthogonal polarization waves

    International Nuclear Information System (INIS)

    Pérez, A. M.; Boria, V. E.; Gimeno, B.; Anza, S.; Vicente, C.; Gil, J.

    2014-01-01

    Circular waveguides, either employed as resonant cavities or as irises connecting adjacent guides, are widely present in many passive components used in different applications (i.e., particle accelerators and satellite subsystems). In this paper, we present the study of the multipactor effect in circular waveguides considering the coexistence of the two polarizations of the fundamental TE 11 circular waveguide mode. For a better understanding of the problem, only low multipactor orders have been explored as a function of the polarization ellipse eccentricity. Special attention has been paid to the linear and circular polarizations, but other more general configurations have also been explored

  10. Analysis of the multipactor effect in circular waveguides excited by two orthogonal polarization waves

    Energy Technology Data Exchange (ETDEWEB)

    Pérez, A. M.; Boria, V. E. [Departamento de Comunicaciones-iTEAM, Universidad Politécnica de Valencia Camino de Vera s/n, 46022 Valencia (Spain); Gimeno, B. [Departamento de Física Aplicada y Electromagnetismo-ICMUV, Universitat de València c/Dr. Moliner, 50, 46100 Valencia (Spain); Anza, S.; Vicente, C.; Gil, J. [Aurora Software and Testing S.L., Edificio de Desarrollo Empresarial 9B, Universidad Politécnica de Valencia, Camino de Vera s/n, 46022 Valencia (Spain)

    2014-08-15

    Circular waveguides, either employed as resonant cavities or as irises connecting adjacent guides, are widely present in many passive components used in different applications (i.e., particle accelerators and satellite subsystems). In this paper, we present the study of the multipactor effect in circular waveguides considering the coexistence of the two polarizations of the fundamental TE{sub 11} circular waveguide mode. For a better understanding of the problem, only low multipactor orders have been explored as a function of the polarization ellipse eccentricity. Special attention has been paid to the linear and circular polarizations, but other more general configurations have also been explored.

  11. Excitation of Self-Localized Spin-Wave Bullets by Spin-Polarized Current in In-Plane Magnetized Magnetic Nano-Contacts: A Micromagnetic Study

    Science.gov (United States)

    2007-10-08

    excitation of microwave spin waves.3,10,11 The analytical theory of spin-wave excitation in magnetic nanocontacts by spin-polarized current performed...linear theory ,3 the propagating spin- wave mode excited at the threshold is a cylindrical spin- wave with the wave vector kL=1.2/Rc and frequency L... Oersted magnetic field, and/or by any other small interaction, neglected in the micromagnetic model. To make the excitation of subcritical modes12,15

  12. Propagation of high frequency electrostatic surface waves along the planar interface between plasma and dusty plasma

    Science.gov (United States)

    Mishra, Rinku; Dey, M.

    2018-04-01

    An analytical model is developed that explains the propagation of a high frequency electrostatic surface wave along the interface of a plasma system where semi-infinite electron-ion plasma is interfaced with semi-infinite dusty plasma. The model emphasizes that the source of such high frequency waves is inherent in the presence of ion acoustic and dust ion acoustic/dust acoustic volume waves in electron-ion plasma and dusty plasma region. Wave dispersion relation is obtained for two distinct cases and the role of plasma parameters on wave dispersion is analyzed in short and long wavelength limits. The normalized surface wave frequency is seen to grow linearly for lower wave number but becomes constant for higher wave numbers in both the cases. It is observed that the normalized frequency depends on ion plasma frequencies when dust oscillation frequency is neglected.

  13. Ion-driven instabilities of surface dust ion-acoustic waves in bounded plasma devices

    Science.gov (United States)

    Lee, Myoung-Jae; Jung, Young-Dae

    2018-02-01

    The growth rates of the dust ion-acoustic surface wave in the plasma slab device containing ion streaming passing through the stationary electrons and dusty grains at the speed of wave phase velocity are derived and numerically analyzed. We have found that the growth rates for the resonant symmetric and antisymmetric waves are similar to the case of semi-bounded plasma when we have a thick slab. However, in the case of the symmetric wave, the growth rate moves towards the bulk wave as the slab thickness reduces. In the case of the antisymmetric wave, the growth rate increases fast as the slab thickness decreases. The growth rates of surface waves in a plasma slab are compared with those of semi-bounded and bulk waves.

  14. Impact of surface waves in a Regional Climate Model

    DEFF Research Database (Denmark)

    Rutgersson, Anna; Sætra, Oyvind; Semedo, Alvaro

    2010-01-01

    A coupled regional atmosphere-wave model system is developed with the purpose of investigating the impact of climate changes on the wave field, as well as feed-back effects of the wave field on the atmospheric parameters. This study focuses on the effects of introducing a two-way atmosphere......-wave coupling on the atmosphere as well as on wave parameters. The model components are the regional climate model RCA, and the third generation wave model WAM. Two different methods are used for the coupling, using the roughness length and only including the effect of growing sea, and using the wave age...... in climate models for a realistic description of processes over sea....

  15. Analysis of passive surface-wave noise in surface microseismic data and its implications

    Science.gov (United States)

    Forghani-Arani, F.; Willis, M.; Haines, S.; Batzle, M.; Davidson, M.

    2011-01-01

    Tight gas reservoirs are projected to be a major portion of future energy resources. Because of their low permeability, hydraulic fracturing of these reservoirs is required to improve the permeability and reservoir productivity. Passive seismic monitoring is one of the few tools that can be used to characterize the changes in the reservoir due to hydraulic fracturing. Although the majority of the studies monitoring hydraulic fracturing exploit down hole microseismic data, surface microseismic monitoring is receiving increased attention because it is potentially much less expensive to acquire. Due to a broader receiver aperture and spatial coverage, surface microseismic data may be more advantageous than down hole microseismic data. The effectiveness of this monitoring technique, however, is strongly dependent on the signal-to-noise ratio of the data. Cultural and ambient noise can mask parts of the waveform that carry information about the subsurface, thereby decreasing the effectiveness of surface microseismic analysis in identifying and locating the microseismic events. Hence, time and spatially varying suppression of the surface-wave noise ground roll is a critical step in surface microseismic monitoring. Here, we study a surface passive dataset that was acquired over a Barnett Shale Formation reservoir during two weeks of hydraulic fracturing, in order to characterize and suppress the surface noise in this data. We apply techniques to identify the characteristics of the passive ground roll. Exploiting those characteristics, we can apply effective noise suppression techniques to the passive data. ?? 2011 Society of Exploration Geophysicists.

  16. Ocean surface waves in Hurricane Ike (2008) and Superstorm Sandy (2012): Coupled model predictions and observations

    Science.gov (United States)

    Chen, Shuyi S.; Curcic, Milan

    2016-07-01

    Forecasting hurricane impacts of extreme winds and flooding requires accurate prediction of hurricane structure and storm-induced ocean surface waves days in advance. The waves are complex, especially near landfall when the hurricane winds and water depth varies significantly and the surface waves refract, shoal and dissipate. In this study, we examine the spatial structure, magnitude, and directional spectrum of hurricane-induced ocean waves using a high resolution, fully coupled atmosphere-wave-ocean model and observations. The coupled model predictions of ocean surface waves in Hurricane Ike (2008) over the Gulf of Mexico and Superstorm Sandy (2012) in the northeastern Atlantic and coastal region are evaluated with the NDBC buoy and satellite altimeter observations. Although there are characteristics that are general to ocean waves in both hurricanes as documented in previous studies, wave fields in Ike and Sandy possess unique properties due mostly to the distinct wind fields and coastal bathymetry in the two storms. Several processes are found to significantly modulate hurricane surface waves near landfall. First, the phase speed and group velocities decrease as the waves become shorter and steeper in shallow water, effectively increasing surface roughness and wind stress. Second, the bottom-induced refraction acts to turn the waves toward the coast, increasing the misalignment between the wind and waves. Third, as the hurricane translates over land, the left side of the storm center is characterized by offshore winds over very short fetch, which opposes incoming swell. Landfalling hurricanes produce broader wave spectra overall than that of the open ocean. The front-left quadrant is most complex, where the combination of windsea, swell propagating against the wind, increasing wind-wave stress, and interaction with the coastal topography requires a fully coupled model to meet these challenges in hurricane wave and surge prediction.

  17. Novel porous fiber based on dual-asymmetry for low-loss polarization maintaining THz wave guidance

    DEFF Research Database (Denmark)

    Islam, Raonaqul; Habib, Selim; Hasanuzzaman, G.K.M.

    2016-01-01

    to achieve an ultra-high birefringence. Besides, only circular air holes have been used to represent the structure, which makes the fiber remarkably simple. The transmission characteristics have been numerically examined based on an efficient finite element method (FEM). The numerical results confirm a high......In this Letter, we suggest a novel kind of porous-core photonic crystal fiber (PCF) (to the best of our knowledge) for efficient transportation of polarization maintaining (PM) terahertz (THz) waves. We introduce an asymmetry in both the porous-core and the porous-cladding of the structure...

  18. Control of Electronic Conduction at an Oxide Heterointerface using Surface Polar Adsorbates

    Energy Technology Data Exchange (ETDEWEB)

    Bell, Christopher

    2011-08-19

    We study the effect of the surface adsorption of a variety of common laboratory solvents on the conductivity at the interface between LaAlO{sub 3} and SrTiO{sub 3}. This interface possesses a range of intriguing physics, notably a proposed connection between the surface state of the LaAlO{sub 3} and the conductivity buried in the SrTiO{sub 3}. We show that the application of chemicals such as acetone, ethanol, and water can induce a large change (factor of three) in the conductivity. This phenomenon is observed only for polar solvents. These data provide experimental evidence for a general polarization-facilitated electronic transfer mechanism.

  19. Electromagnetic surface waves at the interface of a relativistic electron beam with vacuum

    International Nuclear Information System (INIS)

    Shoucri, M.M.; Gagne, R.R.J.

    1977-01-01

    The dispersion relation for electromagnetic surface waves propagating at the interface between a relativistic electron beam and vacuum is derived. The excitation of surface modes in a plasma at rest by a relativistic electron beam is discussed

  20. Polarization-Insensitive Surface Plasmon Polarization Electro-Absorption Modulator Based on Epsilon-Near-Zero Indium Tin Oxide.

    Science.gov (United States)

    Jin, Lin; Wen, Long; Liang, Li; Chen, Qin; Sun, Yunfei

    2018-02-03

    CMOS-compatible plasmonic modulators operating at the telecom wavelength are significant for a variety of on-chip applications. Relying on the manipulation of the transverse magnetic (TM) mode excited on the metal-dielectric interface, most of the previous demonstrations are designed to response only for specific polarization state. In this case, it will lead to a high polarization dependent loss, when the polarization-sensitive modulator integrates to a fiber with random polarization state. Herein, we propose a plasmonic modulator utilizing a metal-oxide indium tin oxide (ITO) wrapped around the silicon waveguide and investigate its optical modulation ability for both the vertical and horizontal polarized guiding light by tuning electro-absorption of ITO with the field-induced carrier injection. The electrically biased modulator with electron accumulated at the ITO/oxide interface allows for epsilon-near-zero (ENZ) mode to be excited at the top or lateral portion of the interface depending on the polarization state of the guiding light. Because of the high localized feature of ENZ mode, efficient electro-absorption can be achieved under the "OFF" state of the device, thus leading to large extinction ratio (ER) for both polarizations in our proposed modulator. Further, the polarization-insensitive modulation is realized by properly tailoring the thickness of oxide in two different stacking directions and therefore matching the ER values for device operating at vertical and horizontal polarized modes. For the optimized geometry configuration, the difference between the ER values of two polarization modes, i.e., the ΔER, as small as 0.01 dB/μm is demonstrated and, simultaneously with coupling efficiency above 74%, is obtained for both polarizations at a wavelength of 1.55 μm. The proposed plasmonic-combined modulator has a potential application in guiding and processing of light from a fiber with a random polarization state.

  1. Polarization-Insensitive Surface Plasmon Polarization Electro-Absorption Modulator Based on Epsilon-Near-Zero Indium Tin Oxide

    Science.gov (United States)

    Jin, Lin; Wen, Long; Liang, Li; Chen, Qin; Sun, Yunfei

    2018-02-01

    CMOS-compatible plasmonic modulators operating at the telecom wavelength are significant for a variety of on-chip applications. Relying on the manipulation of the transverse magnetic (TM) mode excited on the metal-dielectric interface, most of the previous demonstrations are designed to response only for specific polarization state. In this case, it will lead to a high polarization dependent loss, when the polarization-sensitive modulator integrates to a fiber with random polarization state. Herein, we propose a plasmonic modulator utilizing a metal-oxide indium tin oxide (ITO) wrapped around the silicon waveguide and investigate its optical modulation ability for both the vertical and horizontal polarized guiding light by tuning electro-absorption of ITO with the field-induced carrier injection. The electrically biased modulator with electron accumulated at the ITO/oxide interface allows for epsilon-near-zero (ENZ) mode to be excited at the top or lateral portion of the interface depending on the polarization state of the guiding light. Because of the high localized feature of ENZ mode, efficient electro-absorption can be achieved under the "OFF" state of the device, thus leading to large extinction ratio (ER) for both polarizations in our proposed modulator. Further, the polarization-insensitive modulation is realized by properly tailoring the thickness of oxide in two different stacking directions and therefore matching the ER values for device operating at vertical and horizontal polarized modes. For the optimized geometry configuration, the difference between the ER values of two polarization modes, i.e., the ΔER, as small as 0.01 dB/μm is demonstrated and, simultaneously with coupling efficiency above 74%, is obtained for both polarizations at a wavelength of 1.55 μm. The proposed plasmonic-combined modulator has a potential application in guiding and processing of light from a fiber with a random polarization state.

  2. Surface Polar Lipids Differ in Male and Female Phlebotomus papatasi (Diptera: Psychodidae)

    Science.gov (United States)

    2014-11-01

    sandßyLutzomyia longipalpis ( Diptera : Psychodidae) in- duces neurophysiological responses and attracts both males and females. J. Insect Physiol. 51...VECTOR CONTROL, PEST MANAGEMENT, RESISTANCE, REPELLENTS Surface Polar Lipids Differ in Male and Female Phlebotomus papatasi ( Diptera : Psychodidae...Differ in Male and Female Phlebotomus papatasi ( Diptera : Psychodidae) 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d

  3. Characterization of the Deep Water Surface Wave Variability in the California Current Region

    Science.gov (United States)

    Villas Bôas, Ana B.; Gille, Sarah T.; Mazloff, Matthew R.; Cornuelle, Bruce D.

    2017-11-01

    Surface waves are crucial for the dynamics of the upper ocean not only because they mediate exchanges of momentum, heat, energy, and gases between the ocean and the atmosphere, but also because they determine the sea state. The surface wave field in a given region is set by the combination of local and remote forcing. The present work characterizes the seasonal variability of the deep water surface wave field in the California Current region, as retrieved from over two decades of satellite altimetry data combined with wave buoys and wave model hindcast (WaveWatch III). In particular, the extent to which the local wind modulates the variability of the significant wave height, peak period, and peak direction is assessed. During spring/summer, regional-scale wind events of up to 10 m/s are the dominant forcing for waves off the California coast, leading to relatively short-period waves (8-10 s) that come predominantly from the north-northwest. The wave climatology throughout the California Current region shows average significant wave heights exceeding 2 m during most of the year, which may have implications for the planning and retrieval methods of the Surface Water and Ocean Topography (SWOT) satellite mission.

  4. Oblique propagation of surface waves in an ideal Hall-magnetohydrodynamic finite β plasma slab

    International Nuclear Information System (INIS)

    Zhelyazkov, Ivan; Mann, Gottfried

    2003-01-01

    The paper considers the most general case of oblique propagation of sausage and kink magnetohydrodynamic (MHD) surface waves in an ideal finite β magnetized plasma slab by taking into account the Hall term in the generalized Ohm's law. It is found that, like the cases of incompressible (β→∞) and cold (β→0) plasmas, the combining action of the Hall effect and the oblique wave propagation makes possible, for a given wave vector k making an angle θ with respect to the ambient magnetic field B 0 , the existence of multivalued solutions to the dispersion relations of both kinds of MHD surface waves. Like in unbounded Hall-MHD plasmas, in the low-frequency limit (the wave frequency ω smaller than the ion-cyclotron frequency ω ci ), there is generally observed three type of waves, notably fast, intermediate (or Alfven) and slow modes. In view of possible solar-wind applications, here, is considered only Alfven and slow surface waves. A peculiarity of sausage and kink surface waves is that their structure (in the direction perpendicular to the ambient magnetic field B 0 ) is determined by four attenuation coefficients (two pairs inside and outside the layer, respectively) being real or imaginary quantities. This complex structure of Hall-MHD surface waves make them akin (however, not equivalent) to the Rayleigh-type waves in solids and geophysics

  5. Oblique propagation of surface waves in an ideal Hall-magnetohydrodynamic finite β plasma slab

    Science.gov (United States)

    Zhelyazkov, Ivan; Mann, Gottfried

    2003-02-01

    The paper considers the most general case of oblique propagation of sausage and kink magnetohydrodynamic (MHD) surface waves in an ideal finite β magnetized plasma slab by taking into account the Hall term in the generalized Ohm's law. It is found that, like the cases of incompressible (β→∞) and cold (β→0) plasmas, the combining action of the Hall effect and the oblique wave propagation makes possible, for a given wave vector k making an angle θ with respect to the ambient magnetic field B0, the existence of multivalued solutions to the dispersion relations of both kinds of MHD surface waves. Like in unbounded Hall-MHD plasmas, in the low-frequency limit (the wave frequency ω smaller than the ion-cyclotron frequency ωci), there is generally observed three type of waves, notably fast, intermediate (or Alfvén) and slow modes. In view of possible solar-wind applications, here, is considered only Alfvén and slow surface waves. A peculiarity of sausage and kink surface waves is that their structure (in the direction perpendicular to the ambient magnetic field B0) is determined by four attenuation coefficients (two pairs inside and outside the layer, respectively) being real or imaginary quantities. This complex structure of Hall-MHD surface waves make them akin (however, not equivalent) to the Rayleigh-type waves in solids and geophysics.

  6. Thermodynamic stability of the UO2 surfaces: Interplay between over-stoichiometry and polarity compensation

    Science.gov (United States)

    Bottin, François; Geneste, Grégory; Jomard, Gérald

    2016-03-01

    The thermodynamic stability of UO2 surfaces is investigated using ab initio calculations. We employ the GGA+U framework to properly model the strong electronic correlations of the uranium 5 f electrons. Among the seven terminations of the (100), (110), and (111) orientations studied in this paper, we predict that the stoichiometric O-(111) is the most stable one under oxygen-poor or -intermediary environments. At odds with other fluorite surfaces, the overstoichiometric and polar O2-(100) and O2-(111) terminations become the most stable in oxygen-rich environments. For the latter, strong modifications of the electronic structure appear within the upper layers, in order to fulfill the polarity compensation criterion. Some U-5 f states are emptied, leading to higher oxidation 5 + and 6 + states for uranium in the outermost layers, but leaving the surface insulating. This unexpected polarity compensation mechanism is not observed for other charge transfer compounds (such as PuO2) and can be related to the f -f Mott-Hubbard band gap of the UO2 material. By considering the most stable stoichiometric and overstoichiometric terminations, the Castell's ratio can be fulfilled, explaining the Wulff shape of nanovoids in UO2 crystals.

  7. Surface wave scattering theory : with applications to forward and inverse problems in seismology

    NARCIS (Netherlands)

    Snieder, R.K.

    1987-01-01

    Scattering of surface waves in a three dimensional layered elastic medium with embedded heterogeneities is described in this thesis with the Born approximation. The dyadic decomposition of the surface wave Green's function provides the crucial element for an efficient application of Born theory to

  8. Surface wave scattering theory : with applications to forward and inverse problems in seismology

    NARCIS (Netherlands)

    Snieder, R.K.

    1987-01-01

    Scattering of surface waves in a three dimensional layered elastic medium with embedded heterogeneities is described in this thesis with the Born approximation. The dyadic decomposition of the surface wave Green's function provides the crucial element for an efficient application of Born theory

  9. A surface acoustic wave ICP sensor with good temperature stability.

    Science.gov (United States)

    Zhang, Bing; Hu, Hong; Ye, Aipeng; Zhang, Peng

    2017-07-20

    Intracranial pressure (ICP) monitoring is very important for assessing and monitoring hydrocephalus, head trauma and hypertension patients, which could lead to elevated ICP or even devastating neurological damage. The mortality rate due to these diseases could be reduced through ICP monitoring, because precautions can be taken against the brain damage. This paper presents a surface acoustic wave (SAW) pressure sensor to realize ICP monitoring, which is capable of wireless and passive transmission with antenna attached. In order to improve the temperature stability of the sensor, two methods were adopted. First, the ST cut quartz was chosen as the sensor substrate due to its good temperature stability. Then, a differential temperature compensation method was proposed to reduce the effects of temperature. Two resonators were designed based on coupling of mode (COM) theory and the prototype was fabricated and verified using a system established for testing pressure and temperature. The experiment result shows that the sensor has a linearity of 2.63% and hysteresis of 1.77%. The temperature stability of the sensor has been greatly improved by using the differential compensation method, which validates the effectiveness of the proposed method.

  10. Circular polarization switching and bistability in an optically injected 1300 nm spin-vertical cavity surface emitting laser

    Energy Technology Data Exchange (ETDEWEB)

    Alharthi, S. S., E-mail: ssmalh@essex.ac.uk; Henning, I. D.; Adams, M. J. [School of Computer Science and Electronic Engineering, University of Essex, Wivenhoe Park, Colchester CO4 3SQ (United Kingdom); Hurtado, A. [School of Computer Science and Electronic Engineering, University of Essex, Wivenhoe Park, Colchester CO4 3SQ (United Kingdom); Institute of Photonics, Physics Department, University of Strathclyde, Wolfson Centre, 106 Rottenrow East, Glasgow G4 0NW, Scotland (United Kingdom); Korpijarvi, V.-M.; Guina, M. [Optoelectronics Research Centre (ORC), Tampere University of Technology, P.O. Box 692, FIN-33101 Tampere (Finland)

    2015-01-12

    We report the experimental observation of circular polarization switching (PS) and polarization bistability (PB) in a 1300 nm dilute nitride spin-vertical cavity surface emitting laser (VCSEL). We demonstrate that the circularly polarized optical signal at 1300 nm can gradually or abruptly switch the polarization ellipticity of the spin-VCSEL from right-to-left circular polarization and vice versa. Moreover, different forms of PS and PB between right- and left-circular polarizations are observed by controlling the injection strength and the initial wavelength detuning. These results obtained at the telecom wavelength of 1300 nm open the door for novel uses of spin-VCSELs in polarization sensitive applications in future optical systems.

  11. Wave-Breaking Turbulence in the Ocean Surface Layer

    Science.gov (United States)

    2016-06-01

    under moderate wind speeds (Thomson et al. 2013). Assuming equilib- rium, and using a wind input formulation from Plant (1982), the TKE input is 1858...and wave direction at every frequency f of the wave energy spectrum E, and the factor of 0.04 in Plant (1982) is omitted because the adjustment of (ra...increasingly energetic wave breaking simply creates larger bubble clouds that achieve this limit. The highest dissipation rates calcu- lated here do

  12. Brillouin light scattering from surface acoustic waves in a subwavelength-diameter optical fibre.

    Science.gov (United States)

    Beugnot, Jean-Charles; Lebrun, Sylvie; Pauliat, Gilles; Maillotte, Hervé; Laude, Vincent; Sylvestre, Thibaut

    2014-10-24

    Brillouin scattering in optical fibres is a fundamental interaction between light and sound with important implications ranging from optical sensors to slow and fast light. In usual optical fibres, light both excites and feels shear and longitudinal bulk elastic waves, giving rise to forward-guided acoustic wave Brillouin scattering and backward-stimulated Brillouin scattering. In a subwavelength-diameter optical fibre, the situation changes dramatically, as we here report with the first experimental observation of Brillouin light scattering from surface acoustic waves. These Rayleigh-type surface waves travel the wire surface at a specific velocity of 3,400 m s(-1) and backscatter the light with a Doppler shift of about 6 GHz. As these acoustic resonances are sensitive to surface defects or features, surface acoustic wave Brillouin scattering opens new opportunities for various sensing applications, but also in other domains such as microwave photonics and nonlinear plasmonics.

  13. Lithospheric Structure of the Arabian Shield from the Joint Inversion of Receiver Function and Surface-Wave Dispersion Observations

    National Research Council Canada - National Science Library

    Julia, Jordi; Ammon, Charles J; Herrimann, Robert B

    2006-01-01

    .... Receiver functions are primarily sensitive to shear-wave velocity contrasts and vertical travel times and surface-wave dispersion measurements are sensitive to vertical shear-wave velocity averages...

  14. Lithospheric Structure of the Arabian Shield From the Joint Inversion of Receiver Function and Surface-Wave Dispersion Observations

    National Research Council Canada - National Science Library

    Herrmann, Robert B; Julia, Jordi; Ammon, Charles J

    2007-01-01

    .... Receiver functions are primarily sensitive to shear-wave velocity contrast and vertical travel times and surface-wave dispersion measurements are sensitive to vertical shear-wave velocity averages...

  15. Numerical study of three-dimensional sound reflection from corrugated surface waves.

    Science.gov (United States)

    Choo, Youngmin; Song, H C; Seong, Woojae

    2016-10-01

    When a sound wave propagates in a water medium bounded by a smooth surface wave, reflection from a wave crest can lead to focusing and result in rapid variation of the received waveform as the surface wave moves [Tindle, Deane, and Preisig, J. Acoust. Soc. Am. 125, 66-72 (2009)]. In prior work, propagation paths have been constrained to be in a plane parallel to the direction of corrugated surface waves, i.e., a two-dimensional (2-D) propagation problem. In this paper, the azimuthal dependence of sound propagation as a three-dimensional (3-D) problem is investigated using an efficient, time-domain Helmholtz-Kirchhoff integral formulation. When the source and receiver are in the plane orthogonal to the surface wave direction, the surface wave curvature vanishes in conventional 2-D treatments and the flat surface simply moves up and down, resulting in minimal temporal variation of the reflected signal intensity. On the other hand, the 3-D propagation analysis reveals that a focusing phenomenon occurs in the reflected signal due to the surface wave curvature formed along the orthogonal plane, i.e., out-of-plane scattering.

  16. Retrieving mesospheric winds and gravity waves using high resolution radar measurements of polar mesospheric summer echoes with MAARSY

    Science.gov (United States)

    Stober, G.; Sommer, S.; Schult, C.; Chau, J. L.; Latteck, R.

    2013-12-01

    The Middle Atmosphere Alomar Radar System (MAARSY) located at the northern Norwegian island of Andøya (69.3 ° N, 16° E) observes polar mesosphere summer echoes (PMSE) on a regular basis. This backscatter turned out to be an ideal tracer of atmospheric dynamics and to investigate the wind field at the mesosphere/lower thermosphere (MLT) at high spatial and temporal scales. MAARSY is dedicated to explore the polar mesosphere at such high resolution and employs an active phased array antenna with the capability to steer the beam on a pulse-to-pulse basis, which permits to perform systematic scanning of PMSE and to investigate the horizontal structure of the backscatter. The radar also uses a 16 channel receiver system for interferometric applications e.g. mean angle of arrival analysis or coherent radar imaging. Here we present measurements using these features of MAARSY to study the wind field at the MLT applying sophisticated wind analysis algorithms such as velocity azimuth display or volume velocity processing to derive gravity wave parameters such as horizontal wave length, phase speed and propagation direction. Further, we compare the interferometrically corrected and uncorrected wind measurements to emphasize the importance to account for likely edge effects using PMSE as tracer of the dynamics. The observations indicate huge deviations from the nominal beam pointing direction at the upper and lower edges of the PMSE altering the wind analysis.

  17. A noninvasive ultrasound elastography technique for measuring surface waves on the lung.

    Science.gov (United States)

    Zhang, Xiaoming; Osborn, Thomas; Kalra, Sanjay

    2016-09-01

    The purpose of this work was to demonstrate an ultrasound based surface wave elastography (SWE) technique for generating and detecting surface waves on the lung. The motivation was to develop a noninvasive technique for assessing superficial lung tissue disease including interstitial lung disease (ILD). ILD comprises a number of lung disorders in which the lung tissue is stiffened and damaged due to fibrosis of the lung tissue. Currently, chest radiographs and computed tomography (CT) are the most common clinical methods for evaluating lung disease, but they are associated with radiation and cannot measure lung mechanical properties. The novelty of SWE is to develop a noninvasive and nonionizing technique to measure the elastic properties of superficial lung tissue. We propose to generate waves on the lung surface through wave propagation from a local harmonic vibration excitation on the chest through an intercostal space. The resulting surface wave propagation on the lung is detected using an ultrasound probe through the intercostal space. To demonstrate that surface waves can be generated on the lung, an ex vivo muscle-lung model was developed to evaluate lung surface wave generation and detection. In this model, swine muscle was laid atop a swine lung. A vibration excitation of 0.1s 100Hz wave was generated on the muscle surface and the surface waves on the lung were detected using a linear array ultrasound probe at 5MHz. To test its feasibility for patient use, SWE was used to measure both lungs of an ILD patient through eight intercostal spaces. The mean wave speed was 1.71±0.20m/s (±SD) at the functional residual capacity, while the mean wave speed was 2.36±0.33m/s at the total lung capacity. These studies support the feasibility of SWE for noninvasive measurement of elastic properties of lung and demonstrate potential for assessment of ILD. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Amplification of surface acoustic waves by transverse electric current in piezoelectric semiconductors

    DEFF Research Database (Denmark)

    Gulyaev, Yuri V.

    1974-01-01

    It is shown that the principal characteristic feature of the surface acoustic waves in piezoelectrics—the presence of an alternating electric field transverse to the surface, which can be of the same order of magnitude as the longitudinal field—may not only give rise to the known transverse...... acoustoelectric effect but also lead to amplification of surface acoustic waves by electron drift perpendicular to the surface. For Love waves in a piezoelectric semiconductor film on a highly conducting substrate, the amplification coefficient is found and the conditions necessary for amplification...

  19. The Development of Nonlinear Surface and Internal Wave Groups.

    Science.gov (United States)

    1982-11-01

    porn (1971a3 observed groups of large amplitude waves propagating in Massachusetts Bay that seemed to rom tidal interaction with a submarine sill...provides a plan view of the tank and a platform for pictures or movies (Fig. 2.2). For these experiments the measurements from 18 wave height sensors

  20. Effect of irregularity on torsional surface waves in an initially ...

    Indian Academy of Sciences (India)

    The Earth is considered as an initially stressed body with a layered ... Keywords. Torsional wave; anisotropy; initial stress; irregularity; non-homogeneity. J. Earth Syst. Sci., DOI 10.1007/s12040-016-0689-7, 125, No. 4, June 2016, pp. 885–895 ...... wave dispersion in a finitely prestrained hollow sandwich circular cylinder; J.