WorldWideScience

Sample records for wave induced ring

  1. Imaging electron wave functions inside open quantum rings.

    Science.gov (United States)

    Martins, F; Hackens, B; Pala, M G; Ouisse, T; Sellier, H; Wallart, X; Bollaert, S; Cappy, A; Chevrier, J; Bayot, V; Huant, S

    2007-09-28

    Combining scanning gate microscopy (SGM) experiments and simulations, we demonstrate low temperature imaging of the electron probability density |Psi|(2)(x,y) in embedded mesoscopic quantum rings. The tip-induced conductance modulations share the same temperature dependence as the Aharonov-Bohm effect, indicating that they originate from electron wave function interferences. Simulations of both |Psi|(2)(x,y) and SGM conductance maps reproduce the main experimental observations and link fringes in SGM images to |Psi|(2)(x,y).

  2. Waves in Saturn's rings probed by radio occultation

    International Nuclear Information System (INIS)

    Rosen, P.A.

    1989-01-01

    Thirty wave features, observed in 3.6 and 13 cm-wavelength optical depth profiles of Saturn's rings obtained by Voyager 1 radio occultation, are analyzed individually and comparatively. Many are the signature of spiral density waves and bending waves excited by gravitational resonances with Saturn's satellites. A new technique for locating waveform extrema, which fits a sinusoid to each half cycle of wave data, quantifies the wavelength variation across a feature. Fitting dispersion models to the derived wavelengths provides new estimates of ambient surface mass density σ in each wave region. For fourteen weak density waves in Ring A, modelling of the waveform near resonance with linear density wave theory gives independent estimates of σ, as well as reliable estimates of resonance location. Measurements of wave amplitude damping give an upper bound for ring thickness 2H, where H is the ring scale height. In the wave regions studied, Rings A, B, and C have 30 approx-lt σ approx-lt 70, σ approx-gt 65, and σ ∼ 1 g/cm 2 , respectively. Mass loading estimates from waveform modelling are 20 to 40% larger than dispersion-derived values, suggesting accumulation of mass in the wave regions. The average offset of derived wave location from theoretical resonance is about 1 km. Model waveforms of overlapping waves excited by the satellites Janus and Epimethenus agree well with observed morphologies in the linear region near resonance. In Ring C, dispersion analysis indicates that the most prominent wave feature, previously unidentified, is a one-armed spiral wave

  3. Damping of Resonantly Forced Density Waves in Dense Planetary Rings

    Science.gov (United States)

    Lehmann, Marius; Schmidt, Jürgen; Salo, Heikki

    2016-10-01

    We address the stability of resonantly forced density waves in dense planetary rings.Already by Goldreich and Tremaine (1978) it has been argued that density waves might be unstable, depending on the relationship between the ring's viscosity and the surface mass density. In the recent paper (Schmidt et al. 2016) we have pointed out that when - within a fluid description of the ring dynamics - the criterion for viscous overstability is satisfied, forced spiral density waves become unstable as well. In this case, linear theory fails to describe the damping.We apply the multiple scale formalism to derive a weakly nonlinear damping relation from a hydrodynamical model.This relation describes the resonant excitation and nonlinear viscous damping of spiral density waves in a vertically integrated fluid disk with density dependent transport coefficients. The model consistently predicts linear instability of density waves in a ring region where the conditions for viscous overstability are met. In this case, sufficiently far away from the Lindblad resonance, the surface mass density perturbation is predicted to saturate to a constant value due to nonlinear viscous damping. In general the model wave damping lengths depend on a set of input parameters, such as the distance to the threshold for viscous overstability and the ground state surface mass density.Our new model compares reasonably well with the streamline model for nonlinear density waves of Borderies et al. 1986.Deviations become substantial in the highly nonlinear regime, corresponding to strong satellite forcing.Nevertheless, we generally observe good or at least qualitative agreement between the wave amplitude profiles of both models. The streamline approach is superior at matching the total wave profile of waves observed in Saturn's rings, while our new damping relation is a comparably handy tool to gain insight in the evolution of the wave amplitude with distance from resonance, and the different regimes of

  4. Wave-Kinetic Simulations of the Nonlinear Generation of Electromagnetic VLF Waves through Velocity Ring Instabilities

    Science.gov (United States)

    Ganguli, G.; Crabtree, C. E.; Rudakov, L.; Mithaiwala, M.

    2014-12-01

    Velocity ring instabilities are a common naturally occuring magnetospheric phenomenon that can also be generated by man made ionospheric experiments. These instabilities are known to generate lower-hybrid waves, which generally cannot propagte out of the source region. However, nonlinear wave physics can convert these linearly driven electrostatic lower-hybrid waves into electromagnetic waves that can escape the source region. These nonlinearly generated waves can be an important source of VLF turbulence that controls the trapped electron lifetime in the radiation belts. We develop numerical solutions to the wave-kinetic equation in a periodic box including the effects of nonlinear (NL) scattering (nonlinear Landau damping) of Lower-hybrid waves giving the evolution of the wave-spectra in wavenumber space. Simultaneously we solve the particle diffusion equation of both the background plasma particles and the ring ions, due to both linear and nonlinear Landau resonances. At initial times for cold ring ions, an electrostatic beam mode is excited, while the kinetic mode is stable. As the instability progresses the ring ions heat, the beam mode is stabilized, and the kinetic mode destabilizes. When the amplitude of the waves becomes sufficient the lower-hybrid waves are scattered (by either nearly unmagnetized ions or magnetized electrons) into electromagnetic magnetosonic waves [Ganguli et al 2010]. The effect of NL scattering is to limit the amplitude of the waves, slowing down the quasilinear relaxation time and ultimately allowing more energy from the ring to be liberated into waves [Mithaiwala et al. 2011]. The effects of convection out of the instability region are modeled, additionally limiting the amplitude of the waves, allowing further energy to be liberated from the ring [Scales et al., 2012]. Results are compared to recent 3D PIC simulations [Winske and Duaghton 2012].

  5. Modelling of Resonantly Forced Density Waves in Dense Planetary Rings

    Science.gov (United States)

    Lehmann, M.; Schmidt, J.; Salo, H.

    2014-04-01

    Density wave theory, originally proposed to explain the spiral structure of galactic disks, has been applied to explain parts of the complex sub-structure in Saturn's rings, such as the wavetrains excited at the inner Lindblad resonances (ILR) of various satellites. The linear theory for the excitation and damping of density waves in Saturn's rings is fairly well developed (e.g. Goldreich & Tremaine [1979]; Shu [1984]). However, it fails to describe certain aspects of the observed waves. The non-applicability of the linear theory is already indicated by the "cusplike" shape of many of the observed wave profiles. This is a typical nonlinear feature which is also present in overstability wavetrains (Schmidt & Salo [2003]; Latter & Ogilvie [2010]). In particular, it turns out that the detailed damping mechanism, as well as the role of different nonlinear effects on the propagation of density waves remain intransparent. First attemps are being made to investigate the excitation and propagation of nonlinear density waves within a hydrodynamical formalism, which is also the natural formalism for describing linear density waves. A simple weakly nonlinear model, derived from a multiple-scale expansion of the hydrodynamic equations, is presented. This model describes the damping of "free" spiral density waves in a vertically integrated fluid disk with density dependent transport coefficients, where the effects of the hydrodynamic nonlinearities are included. The model predicts that density waves are linearly unstable in a ring region where the conditions for viscous overstability are met, which translates to a steep dependence of the shear viscosity with respect to the disk's surface density. The possibility that this dependence could lead to a growth of density waves with increasing distance from the resonance, was already mentioned in Goldreich & Tremaine [1978]. Sufficiently far away from the ILR, the surface density perturbation caused by the wave, is predicted to

  6. Induced electric dipole in a quantum ring

    Energy Technology Data Exchange (ETDEWEB)

    Dantas, L.; Furtado, Claudio, E-mail: furtado@fisica.ufpb.br

    2013-12-02

    In this contribution, we investigate the quantum dynamics of a neutral particle confined in a quantum ring potential. We use two different field configurations for induced electric dipole in the presence of electric and magnetic fields and a general confining potential, for which we solve the Schrödinger equation and obtain the complete set of eigenfunctions and eigenvalues.

  7. The Effects of Hydrogen Band EMIC Waves on Ring Current H+ Ions

    Science.gov (United States)

    Wang, Zhiqiang; Zhai, Hao; Gao, Zhuxiu

    2017-12-01

    Hydrogen band electromagnetic ion cyclotron (EMIC) waves have received much attention recently because they are found to frequently span larger spatial areas than the other band EMIC waves. Using test particle simulations, we study the nonlinear effects of hydrogen band EMIC waves on ring current H+ ions. A dimensionless parameter R is used to characterize the competition between wave-induced and adiabatic motions. The results indicate that there are three regimes of wave-particle interactions for typical 35 keV H+ ions at L = 5: diffusive (quasi-linear) behavior when αeq ≤ 35° (R ≥ 2.45), the nonlinear phase trapping when 35° < αeq < 50° (0.75 < R < 2.45), and both the nonlinear phase bunching and phase trapping when αeq ≥ 50° (R ≤ 0.75). The phase trapping can transport H+ ions toward large pitch angle, while the phase bunching has the opposite effect. The phase-trapped H+ ions can be significantly accelerated (from 35 keV to over 500 keV) in about 4 min and thus contribute to the formation of high energy components of ring current ions. The results suggest that the effect of hydrogen band EMIC waves is not ignorable in the nonlinear acceleration and resonance scattering of ring current H+ ions.

  8. Electric currents induced by twisted light in Quantum Rings.

    Science.gov (United States)

    Quinteiro, G F; Berakdar, J

    2009-10-26

    We theoretically investigate the generation of electric currents in quantum rings resulting from the optical excitation with twisted light. Our model describes the kinetics of electrons in a two-band model of a semiconductor-based mesoscopic quantum ring coupled to light having orbital angular momentum (twisted light). We find the analytical solution, which exhibits a "circular" photon-drag effect and an induced magnetization, suggesting that this system is the circular analog of that of a bulk semiconductor excited by plane waves. For realistic values of the electric field and material parameters, the computed electric current can be as large as microA; from an applied perspective, this opens new possibilities to the optical control of the magnetization in semiconductors.

  9. Generation of stable mixed-compact-toroid rings by inducing plasma currents in strong E rings

    International Nuclear Information System (INIS)

    Jayakumar, R.; Taggart, D.P.; Parker, M.R.; Fleischmann, H.H.

    1989-01-01

    In the RECE-Christa device, hybrid-type compact toroid rings are generated by inducing large toroidal plasma currents I rho in strong electron rings using a thin induction coil positioned along the ring axis. Starting from field-reversal values δ ο = 50 - 120 percent of the original pure fast-electron ring, the induced plasma current I rho raises δ to a maximum value of up to 240 percent with I rho contributing more than 50 percent of the total ring current. Quite interestingly, the generated hybrid compact toroid configurations appear gross-stable during the full I rho pulse length (half-amplitude width about 100 μs)

  10. Bacterial population solitary waves can defeat rings of funnels

    International Nuclear Information System (INIS)

    Morris, Ryan J; Phan, Trung V; Austin, Robert H; Black, Matthew; Bos, Julia A; Lin, Ke-Chih; Kevrekidis, Ioannis G

    2017-01-01

    We have constructed a microfabricated circular corral for bacteria made of rings of concentric funnels which channel motile bacteria outwards via non-hydrodynamic interactions with the funnel walls. Initially bacteria do move rapidly outwards to the periphery of the corral. At the edge, nano-slits allow for the transport of nutrients into the device while keeping the bacteria from escaping. After a period of time in which the bacteria increase their cell density in this perimeter region, they are then able to defeat the physical constrains of the funnels by launching back-propagating collective waves. We present the basic data and some nonlinear modeling which can explain how bacterial population waves propagate through a physical funnel, and discuss possible biological implications. (paper)

  11. Continuous wave room temperature external ring cavity quantum cascade laser

    Energy Technology Data Exchange (ETDEWEB)

    Revin, D. G., E-mail: d.revin@sheffield.ac.uk; Hemingway, M.; Vaitiekus, D.; Cockburn, J. W. [Physics and Astronomy Department, The University of Sheffield, S3 7RH Sheffield (United Kingdom); Hempler, N.; Maker, G. T.; Malcolm, G. P. A. [M Squared Lasers Ltd., G20 0SP Glasgow (United Kingdom)

    2015-06-29

    An external ring cavity quantum cascade laser operating at ∼5.2 μm wavelength in a continuous-wave regime at the temperature of 15 °C is demonstrated. Out-coupled continuous-wave optical powers of up to 23 mW are observed for light of one propagation direction with an estimated total intra-cavity optical power flux in excess of 340 mW. The uni-directional regime characterized by the intensity ratio of more than 60 for the light propagating in the opposite directions was achieved. A single emission peak wavelength tuning range of 90 cm{sup −1} is realized by the incorporation of a diffraction grating into the cavity.

  12. Continuous wave room temperature external ring cavity quantum cascade laser

    International Nuclear Information System (INIS)

    Revin, D. G.; Hemingway, M.; Vaitiekus, D.; Cockburn, J. W.; Hempler, N.; Maker, G. T.; Malcolm, G. P. A.

    2015-01-01

    An external ring cavity quantum cascade laser operating at ∼5.2 μm wavelength in a continuous-wave regime at the temperature of 15 °C is demonstrated. Out-coupled continuous-wave optical powers of up to 23 mW are observed for light of one propagation direction with an estimated total intra-cavity optical power flux in excess of 340 mW. The uni-directional regime characterized by the intensity ratio of more than 60 for the light propagating in the opposite directions was achieved. A single emission peak wavelength tuning range of 90 cm −1 is realized by the incorporation of a diffraction grating into the cavity

  13. On condensation-induced waves

    NARCIS (Netherlands)

    Cheng, W.; Luo, X.; Dongen, van M.E.H.

    2010-01-01

    Complex wave patterns caused by unsteady heat release due to cloud formation in confined compressible flows are discussed. Two detailed numerical studies of condensation-induced waves are carried out. First, the response of a flow of nitrogen in a slender Laval nozzle to a sudden addition of water

  14. Ring Current He Ion Control by Bounce Resonant ULF Waves

    Science.gov (United States)

    Kim, Hyomin; Gerrard, Andrew J.; Lanzerotti, Louis J.; Soto-Chavez, Rualdo; Cohen, Ross J.; Manweiler, Jerry W.

    2017-12-01

    Ring current energy He ion (˜65 keV to ˜520 keV) differential flux data from the Radiation Belt Storm Probe Ion Composition Experiment (RBSPICE) instrument aboard the Van Allan Probes spacecraft show considerable variability during quiet solar wind and geomagnetic time periods. Such variability is apparent from orbit to orbit (˜9 h) of the spacecraft and is observed to be ˜50-100% of the nominal flux. Using data from the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) instrument, also aboard the Van Allen Probes spacecraft, we identify that a dominant source of this variability is from ULF waveforms with periods of tens of seconds. These periods correspond to the bounce resonant timescales of the ring current He ions being measured by RBSPICE. A statistical survey using the particle and field data for one full spacecraft precession period (approximately 2 years) shows that the wave and He ion flux variations are generally anticorrelated, suggesting the bounce resonant pitch angle scattering process as a major component in the scattering of He ions.

  15. On radio frequency wave induced radial transport and wave helicity

    International Nuclear Information System (INIS)

    Petrzilka, V.

    1992-09-01

    Expressions for wave induced radial transport are derived allowing simple estimates. The transport is enhanced due to the presence of poloidal magnetostatic field and in the vicinity of the ion cyclotron resonance. The direction of the wave induced transport depends also on the wave polarization. (author) 19 refs

  16. On helicon wave induced radial plasma transport

    International Nuclear Information System (INIS)

    Petrzilka, V.

    1993-04-01

    Estimates of helicon wave induced radial plasma transport are presented. The wave induced transport grows or decreases in dependence on the sign of the azimuthal wave number; these changes in transport may play an important role in helicon wave plasma sources. (author) 5 figs., 18 refs

  17. 200 MW S-band traveling wave resonant ring development at IHEP

    Science.gov (United States)

    Zhou, Zu-Sheng; Chi, Yun-Long; Git, Meng-Ping; Pei, Guo-Xi

    2010-03-01

    The resonant-ring is a traveling wave circuit, which is used to produce high peak power with comparatively smaller stored energy. The application to be considered is its use as a high power simulator mainly for testing the klystron ceramic output window, as well as for high power microwave transmission devices. This paper describes the principle of a resonant ring and introduces the structure and property of the newly constructed traveling wave resonant ring at IHEP. Our goal is to produce a 200 MW class resonant ring at 2.856 GHz with a pulse length of 2 μs and repetition rate of 25 Hz. The installation, commissioning and testing of the ring have been completed and a peak power of 200 MW at 3 μs has been achieved. The conditioning results show that all the parameters of the resonant ring reach the design goals.

  18. Gravity induced wave function collapse

    Science.gov (United States)

    Gasbarri, G.; Toroš, M.; Donadi, S.; Bassi, A.

    2017-11-01

    Starting from an idea of S. L. Adler [in Quantum Nonlocality and Reality: 50 Years of Bell's Theorem, edited by M. Bell and S. Gao (Cambridge University Press, Cambridge, England 2016)], we develop a novel model of gravity induced spontaneous wave function collapse. The collapse is driven by complex stochastic fluctuations of the spacetime metric. After deriving the fundamental equations, we prove the collapse and amplification mechanism, the two most important features of a consistent collapse model. Under reasonable simplifying assumptions, we constrain the strength ξ of the complex metric fluctuations with available experimental data. We show that ξ ≥10-26 in order for the model to guarantee classicality of macro-objects, and at the same time ξ ≤10-20 in order not to contradict experimental evidence. As a comparison, in the recent discovery of gravitational waves in the frequency range 35 to 250 Hz, the (real) metric fluctuations reach a peak of ξ ˜10-21.

  19. Exact wave functions of two-electron quantum rings.

    Science.gov (United States)

    Loos, Pierre-François; Gill, Peter M W

    2012-02-24

    We demonstrate that the Schrödinger equation for two electrons on a ring, which is the usual paradigm to model quantum rings, is solvable in closed form for particular values of the radius. We show that both polynomial and irrational solutions can be found for any value of the angular momentum and that the singlet and triplet manifolds, which are degenerate, have distinct geometric phases. We also study the nodal structure associated with these two-electron states.

  20. Femtosecond laser-induced concentric ring microstructures on Zr-based metallic glass

    International Nuclear Information System (INIS)

    Ma Fengxu; Yang Jianjun; Xiaonong Zhu; Liang Chunyong; Wang Hongshui

    2010-01-01

    Surface morphological evolution of Zr-based metallic glass ablated by femtosecond lasers is investigated in atmosphere condition. Three types of permanent ring structures with micro-level spacing are observed for different laser shots and fluences. In the case of low laser fluences, the generation of annular patterns with nonthermal features is observed on the rippled structure with the subwavelength scale, and the ring spacing shows a decrease tendency from the center to the margin. While in the case of high laser fluences, the concentric rings formation within the laser spot is found to have evident molten traces and display the increasing ring spacing along the radial direction. Moreover, when the laser shots accumulation becomes large, the above two types of ring microstructures begin to develop into the common ablation craters. Analysis and discussion suggests that the stress-induced condensation of ablation vapors and the frozen thermocapillary waves on the molten surfaces should be responsible for the formation of two different types of concentric ring structures, respectively. Eventually, a processing window for each resulting surface microstructure type is obtained experimentally and indicates the possibility to control the morphological transitions among different types.

  1. Modal Ring Method for the Scattering of Electromagnetic Waves

    Science.gov (United States)

    Baumeister, Kenneth J.; Kreider, Kevin L.

    1993-01-01

    The modal ring method for electromagnetic scattering from perfectly electric conducting (PEC) symmetrical bodies is presented. The scattering body is represented by a line of finite elements (triangular) on its outer surface. The infinite computational region surrounding the body is represented analytically by an eigenfunction expansion. The modal ring method effectively reduces the two dimensional scattering problem to a one-dimensional problem similar to the method of moments. The modal element method is capable of handling very high frequency scattering because it has a highly banded solution matrix.

  2. Wave Induced Loads on the LEANCON Wave Energy Converter

    DEFF Research Database (Denmark)

    Frigaard, Peter; Kofoed, Jens Peter; Beserra, Eliab Ricarte

    This report is a product of the co-operation agreement between Aalborg University and LEANCON (by Kurt Due Rasmussen) on the evaluation and development of the LEANCON wave energy converter (WEC). The work reported here has focused on evaluation of the wave induced loads on the device, based...... in the laboratory, all under the supervision of the personnel of the Wave Energy Research Group at Department of Civil Engineering, Aalborg University....

  3. High-energy terahertz wave parametric oscillator with a surface-emitted ring-cavity configuration.

    Science.gov (United States)

    Yang, Zhen; Wang, Yuye; Xu, Degang; Xu, Wentao; Duan, Pan; Yan, Chao; Tang, Longhuang; Yao, Jianquan

    2016-05-15

    A surface-emitted ring-cavity terahertz (THz) wave parametric oscillator has been demonstrated for high-energy THz output and fast frequency tuning in a wide frequency range. Through the special optical design with a galvano-optical scanner and four-mirror ring-cavity structure, the maximum THz wave output energy of 12.9 μJ/pulse is achieved at 1.359 THz under the pump energy of 172.8 mJ. The fast THz frequency tuning in the range of 0.7-2.8 THz can be accessed with the step response of 600 μs. Moreover, the maximum THz wave output energy from this configuration is 3.29 times as large as that obtained from the conventional surface-emitted THz wave parametric oscillator with the same experimental conditions.

  4. Magnetoelectric effect in concentric quantum rings induced by shallow donor

    Science.gov (United States)

    Escorcia, R.; García, L. F.; Mikhailov, I. D.

    2018-05-01

    We study the alteration of the magnetic and electric properties induced by the off-axis donor in a double InAs/GaAs concentric quantum ring. To this end we consider a model of an axially symmetrical ring-like nanostructure with double rim, in which the thickness of the InAs thin layer is varied smoothly in the radial direction. The energies and of contour plots of the density of charge for low-lying levels we find by using the adiabatic approximation and the double Fourier-Bessel series expansion method and the Kane model. Our results reveal a possibility of the formation of a giant dipole momentum induced by the in-plane electric field, which in addition can be altered by of the external magnetic field applied along the symmetry axis.

  5. A Weakly Nonlinear Model for the Damping of Resonantly Forced Density Waves in Dense Planetary Rings

    Science.gov (United States)

    Lehmann, Marius; Schmidt, Jürgen; Salo, Heikki

    2016-10-01

    In this paper, we address the stability of resonantly forced density waves in dense planetary rings. Goldreich & Tremaine have already argued that density waves might be unstable, depending on the relationship between the ring’s viscosity and the surface mass density. In the recent paper Schmidt et al., we have pointed out that when—within a fluid description of the ring dynamics—the criterion for viscous overstability is satisfied, forced spiral density waves become unstable as well. In this case, linear theory fails to describe the damping, but nonlinearity of the underlying equations guarantees a finite amplitude and eventually a damping of the wave. We apply the multiple scale formalism to derive a weakly nonlinear damping relation from a hydrodynamical model. This relation describes the resonant excitation and nonlinear viscous damping of spiral density waves in a vertically integrated fluid disk with density dependent transport coefficients. The model consistently predicts density waves to be (linearly) unstable in a ring region where the conditions for viscous overstability are met. Sufficiently far away from the Lindblad resonance, the surface mass density perturbation is predicted to saturate to a constant value due to nonlinear viscous damping. The wave’s damping lengths of the model depend on certain input parameters, such as the distance to the threshold for viscous overstability in parameter space and the ground state surface mass density.

  6. Love waves trains observed after the MW 8.1 Tehuantepec earthquake by an underground ring laser gyroscope

    Science.gov (United States)

    Simonelli, A.; Belfi, J.; Beverini, N.; Di Virgilio, A.; Giacomelli, U.; De Luca, G.; Igel, H.

    2017-12-01

    We report the observation and analysis of the MW 8.1 Tehuantepec earthquake-induced rotational ground motion as observed by the Gingerino ring laser gyroscope (RLG).This instrument is located inside the National laboratory of the "Istituto Nazionale di Fisica Nucleare" in Gran Sasso (Italy) in a deep underground environment.We compare the vertical rotation rate with the horizontal acceleration measured by a co-located broadband seismometer. This analysis, performed by means of a wavelet-based correlation method, permits to identify the G1,G2,G3,G4 onsets of the surface Love waves in the 120 to 280 seconds period range.

  7. Theory of magnetospheric hydromagnetic waves excited by energetic ring-current protons

    International Nuclear Information System (INIS)

    Chen, Liu; Hasegawa, Akira.

    1987-06-01

    A general theoretical formulation, allowing finite ion Larmor radii, general magnetic field geometries and plasma equilibria, has been developed to investigate excitations of magnetohydrodynamic (MHD) Alfven waves within the earth's magnetosphere by the storm-time energetic ring-current protons. In particular, it is found that for adiabatically injected protons, various predicted instability properties are consistent with satellite observations. 8 refs

  8. Current density waves in open mesoscopic rings driven by time-periodic magnetic fluxes

    International Nuclear Information System (INIS)

    Yan Conghua; Wei Lianfu

    2010-01-01

    Quantum coherent transport through open mesoscopic Aharonov-Bohm rings (driven by static fluxes) have been studied extensively. Here, by using quantum waveguide theory and the Floquet theorem we investigate the quantum transport of electrons along an open mesoscopic ring threaded by a time-periodic magnetic flux. We predicate that current density waves could be excited along such an open ring. As a consequence, a net current could be generated along the lead with only one reservoir, if the lead additionally connects to such a normal-metal loop driven by the time-dependent flux. These phenomena could be explained by photon-assisted processes, due to the interaction between the transported electrons and the applied oscillating external fields. We also discuss how the time-average currents (along the ring and the lead) depend on the amplitude and frequency of the applied oscillating fluxes.

  9. Frequency-agile terahertz-wave parametric oscillator in a ring-cavity configuration.

    Science.gov (United States)

    Minamide, Hiroaki; Ikari, Tomofumi; Ito, Hiromasa

    2009-12-01

    We demonstrate a frequency-agile terahertz wave parametric oscillator (TPO) in a ring-cavity configuration (ring-TPO). The TPO consists of three mirrors and a MgO:LiNbO(3) crystal under noncollinear phase-matching conditions. A novel, fast frequency-tuning method was realized by controlling a mirror of the three-mirror ring cavity. The wide tuning range between 0.93 and 2.7 THz was accomplished. For first demonstration using the ring-TPO, terahertz spectroscopy was performed as the verification of the frequency-agile performance, measuring the transmission spectrum of the monosaccharide glucose. The spectrum was obtained within about 8 s in good comparison to those of Fourier transform infrared spectrometer.

  10. Generation of lower hybrid and whistler waves by an ion velocity ring distribution

    International Nuclear Information System (INIS)

    Winske, D.; Daughton, W.

    2012-01-01

    Using fully kinetic simulations in two and three spatial dimensions, we consider the generation and nonlinear evolution of lower hybrid waves produced by a cold ion ring velocity distribution in a low beta plasma. We show that the initial development of the instability is very similar in two and three dimensions and not significantly modified by electromagnetic effects, consistent with linear theory. At saturation, the level of electric field fluctuations is a small fraction of the background thermal energy; the electric field and corresponding density fluctuations consist of long, field-aligned striations. Energy extracted from the ring goes primarily into heating the background ions and the electrons at comparable rates. The initial growth and saturation of the magnetic components of the lower hybrid waves are related to the electric field components, consistent with linear theory. As the growing electric field fluctuations saturate, parallel propagating whistler waves develop by the interaction of two lower hybrid waves. At later times, these whistlers are replaced by longer wavelength, parallel propagating whistlers that grow through the decay of the lower hybrid fluctuations. Wave matching conditions demonstrate these conversion processes of lower hybrid waves to whistler waves. The conversion efficiency (=ratio of the whistler wave energy to the energy in the saturated lower hybrid waves) is computed and found to be significant (∼15%) for the parameters of the three-dimensional simulation (and even larger in the two-dimensional simulation), although when normalized in terms of the initial kinetic energy in the ring ions the overall efficiency is very small ( −4 ). The results are compared with relevant linear and nonlinear theory.

  11. Single and multi-band electromagnetic induced transparency-like metamaterials with coupled split ring resonators

    Science.gov (United States)

    Bagci, Fulya; Akaoglu, Baris

    2017-08-01

    We present a metamaterial configuration exhibiting single and multi-band electromagnetic induced transparency (EIT)-like properties. The unit cell of the single band EIT-like metamaterial consists of a multi-split ring resonator surrounded by a split ring resonator. The multi-split ring resonator acts as a quasi-dark or dark resonator, depending on the polarization of the incident wave, and the split ring resonator serves as the bright resonator. Combination of these two resonators results in a single band EIT-like transmission inside the stop band. EIT-like transmission phenomenon is also clearly observed in the measured transmission spectrum at almost the same frequencies for vertical and horizontal polarized waves, and the numerical results are verified for normal incidence. Moreover, multi-band transmission windows are created within a wide band by combining the two slightly different single band EIT-like metamaterial unit cells that exhibit two different coupling strengths inside a supercell configuration. Group indices as high as 123 for single band and 488 for tri-band transmission, accompanying with high transmission rates (over 80%), are achieved, rendering the metamaterial very suitable for multi-band slow light applications. It is shown that the group delay of the propagating wave can be increased and dynamically controlled by changing the polarization angle. Multi-band EIT-like transmission is also verified experimentally, and a good agreement with simulations is obtained. The proposed novel methodology for obtaining multi-band EIT, which takes advantage of a supercell configuration by hosting slightly different configured unit cells, can be utilized for easily formation and manipulation of multi-band transmission windows inside a stop band.

  12. HYDROCARBON EMISSION RINGS IN PROTOPLANETARY DISKS INDUCED BY DUST EVOLUTION

    Energy Technology Data Exchange (ETDEWEB)

    Bergin, Edwin A.; Du, Fujun; Schwarz, K.; Zhang, K. [Department of Astronomy, University of Michigan, 311 West Hall, 1085 S. University Ave, Ann Arbor, MI 48109 (United States); Cleeves, L. Ilsedore [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Blake, G. A. [Division of Geological and Planetary Sciences, MC 150-21, California Institute of Technology, 1200 E California Blvd, Pasadena, CA 91125 (United States); Visser, R. [European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748, Garching (Germany)

    2016-11-01

    We report observations of resolved C{sub 2}H emission rings within the gas-rich protoplanetary disks of TW Hya and DM Tau using the Atacama Large Millimeter Array. In each case the emission ring is found to arise at the edge of the observable disk of millimeter-sized grains (pebbles) traced by submillimeter-wave continuum emission. In addition, we detect a C{sub 3}H{sub 2} emission ring with an identical spatial distribution to C{sub 2}H in the TW Hya disk. This suggests that these are hydrocarbon rings (i.e., not limited to C{sub 2}H). Using a detailed thermo-chemical model we show that reproducing the emission from C{sub 2}H requires a strong UV field and C/O > 1 in the upper disk atmosphere and outer disk, beyond the edge of the pebble disk. This naturally arises in a disk where the ice-coated dust mass is spatially stratified due to the combined effects of coagulation, gravitational settling and drift. This stratification causes the disk surface and outer disk to have a greater permeability to UV photons. Furthermore the concentration of ices that transport key volatile carriers of oxygen and carbon in the midplane, along with photochemical erosion of CO, leads to an elemental C/O ratio that exceeds unity in the UV-dominated disk. Thus the motions of the grains, and not the gas, lead to a rich hydrocarbon chemistry in disk surface layers and in the outer disk midplane.

  13. Effects of the Ring Current on ULF Waves in the Magnetosphere

    Directory of Open Access Journals (Sweden)

    Khan-Hyuk Kim

    1994-06-01

    Full Text Available A three-dimensional box model has been developed to study the MHD wave coupling in the magnetosphere. In this model, the effects of the ring current are included by assuming the pressure gradients in the MHD equations. It is found that the axisymmetric ring current may play an important role in producing spectral noises in compressional waves, while field line resonances have no such disturbances. These results may explain the current observational characteristics that compressional cavity modes hardly appear in the satellite experiment, while field line resonances often occur. Our numerical results also suggest that any discrete spectral peaks such as the global cavity modes can hardly occur where the pressure distribution of the ring current becomes important. The continuous band of transverse waves is found to be unperturbed until the ring current becomes significantly asymmetric with respect to the dipole axis. In addition, our results in the absence of the pressure gradient are found to be consistent with the previous results from the box-like and dipole models.

  14. Energy transfer between energetic ring current H(+) and O(+) by electromagnetic ion cyclotron waves

    Science.gov (United States)

    Thorne, Richard M.; Horne, Richard B.

    1994-01-01

    Electromagnetic ion cyclotron (EMIC) waves in the frequency range below the helium gyrofrequency can be excited in the equatorial region of the outer magnetosphere by cyclotron resonant instability with anisotropic ring current H(+) ions. As the unducted waves propagate to higher latitudes, the wave normal should become highly inclined to the ambient magnetic field. Under such conditions, wave energy can be absorbed by cyclotron resonant interactions with ambient O(+), leading to ion heating perpendicular to the ambient magnetic field. Resonant wave absorption peaks in the vicinity of the bi-ion frequency and the second harmonic of the O(+) gyrofrequrency. This absorption should mainly occur at latitudes between 10 deg and 30 deg along auroral field lines (L is greater than or equal to 7) in the postnoon sector. The concomitant ion heating perpendicular to the ambient magnetic field can contribute to the isotropization and geomagnetic trapping of collapsed O(+) ion conics (or beams) that originate from a low-altitude ionospheric source region. During geomagnetic storms when the O(+) content of the magnetosphere is significantly enhanced, the absorption of EMIC waves should become more efficient, and it may contribute to the observed acceleration of O(+) ions of ionospheric origin up to ring current energies.

  15. Tunable electromagnetically induced transparency in coupled three-dimensional split-ring-resonator metamaterials

    Science.gov (United States)

    Han, Song; Cong, Longqing; Lin, Hai; Xiao, Boxun; Yang, Helin; Singh, Ranjan

    2016-01-01

    Metamaterials have recently enabled coupling induced transparency due to interference effects in coupled subwavelength resonators. In this work, we present a three dimensional (3-D) metamaterial design with six-fold rotational symmetry that shows electromagnetically induced transparency with a strong polarization dependence to the incident electromagnetic wave due to the ultra-sharp resonance line width as a result of interaction between the constituent meta-atoms. However, when the six-fold rotationally symmetric unit cell design was re-arranged into a fourfold rotational symmetry, we observed the excitation of a polarization insensitive dual-band transparency. Thus, the 3-D split-ring resonators allow new schemes to observe single and multi-band classical analogues of electromagnetically induced transparencies that has huge potential applications in slowing down light, sensing modalities, and filtering functionalities either in the passive mode or the active mode where such effects could be tuned by integrating materials with dynamic properties. PMID:26857034

  16. Enhanced spin wave propagation in magnonic rings by bias field modulation

    Science.gov (United States)

    Venkat, G.; Venkateswarlu, D.; Joshi, R. S.; Franchin, M.; Fangohr, H.; Anil Kumar, P. S.; Prabhakar, A.

    2018-05-01

    We simulate the spin wave (SW) dynamics in ring structures and obtain the ω - k dispersion relations corresponding to the output waveguide. Different bias field configurations affect the transfer of SW power from one arm of the structure to the other arm. To this end, we show that circular or radial bias fields are more suitable for energy transfer across the ring than the conventional horizontal bias field Hx. The SW dispersion shows that modes excited, when the bias field is along the ring radius, are almost 10 dB higher in power when compared to the modal power in the case of Hx. This is also corroborated by the SW energy density in the receiving stub.

  17. Optimisation of spontaneous four-wave mixing in a ring microcavity

    Science.gov (United States)

    Chuprina, I. N.; An, P. P.; Zubkova, E. G.; Kovalyuk, V. V.; Kalachev, A. A.; Gol'tsman, G. N.

    2017-11-01

    A theory of spontaneous four-wave mixing in a ring microcavity is developed. The rate of emission of biphotons for pulsed and monochromatic pumping with allowance for the dispersion of group velocities is analytically calculated. In the first case, pulses in the form of an increasing exponential are considered, which are optimal for excitation of an individual resonator mode. The behaviour of the group velocity dispersion as a function of the width and height of the waveguide is studied for a specific case of a ring microcavity made of silicon nitride. The results of the numerical calculation are in good agreement with the experimental data. The ring microcavity is made of two types of waveguides: completely etched and half etched. It is found that the latter allow for better control over the parameters in the manufacturing process, making them more predictable. Presented at the Russian - British Symposium on Quantum Technologies (Moscow, 20 - 23 March 2017)

  18. Omnidirectional piezo-optical ring sensor for enhanced guided wave structural health monitoring

    International Nuclear Information System (INIS)

    Giurgiutiu, Victor; Roman, Catalin; Lin, Bin; Frankforter, Erik

    2015-01-01

    This paper presents a novel method for the detection of ultrasonic waves from acoustic emission events using piezoelectric wafer ac3tive sensors (PWAS) and optical fiber Bragg grating (FBG) sensing combined with mechanical resonance amplification principles. The method is best suited for detecting the out-of-plane motion of the AE wave with preference for a certain frequency that can be adjusted by design. Several issues are discussed: (a) study the mode shapes of the sensors under different resonance frequencies in order to understand the behavior of the ring in a frequency band of interest; (b) comparison of analytical results and mode shapes with FEM predictions; (c) choice of the final piezo-optical ring sensor shape; (d) testing of the piezo-optical ring sensor prototype; (e) discussion of the ring-sensor test results in comparison with conventional results from PWAS and FBG sensors mounted directly on the test structure. The paper ends with summary, conclusions, and suggestions for further work. (paper)

  19. Ring waves as a mass transport mechanism in air-driven core-annular flows.

    Science.gov (United States)

    Camassa, Roberto; Forest, M Gregory; Lee, Long; Ogrosky, H Reed; Olander, Jeffrey

    2012-12-01

    Air-driven core-annular fluid flows occur in many situations, from lung airways to engineering applications. Here we study, experimentally and theoretically, flows where a viscous liquid film lining the inside of a tube is forced upwards against gravity by turbulent airflow up the center of the tube. We present results on the thickness and mean speed of the film and properties of the interfacial waves that develop from an instability of the air-liquid interface. We derive a long-wave asymptotic model and compare properties of its solutions with those of the experiments. Traveling wave solutions of this long-wave model exhibit evidence of different mass transport regimes: Past a certain threshold, sufficiently large-amplitude waves begin to trap cores of fluid which propagate upward at wave speeds. This theoretical result is then confirmed by a second set of experiments that show evidence of ring waves of annular fluid propagating over the underlying creeping flow. By tuning the parameters of the experiments, the strength of this phenomenon can be adjusted in a way that is predicted qualitatively by the model.

  20. Characteristics and measurement of supersonic projectile shock waves by a 32-microphone ring array

    Science.gov (United States)

    Chang, Ho; Wu, Yan-Chyuan; Tsung, Tsing-Tshih

    2011-08-01

    This paper discusses about the characteristics of supersonic projectile shock wave in muzzle region during firing of high explosive anti-tank (HEAT) and high explosive (HE) projectiles. HEAT projectiles are fired horizontally at a muzzle velocity of Mach 3.5 from a medium caliber tank gun equipped with a newly designed multi-perforated muzzle brake, whereas HE projectiles are fired at elevation angles at a muzzle velocity of Mach 2 from a large caliber howitzer equipped with a newly designed double-baffle muzzle brake. In the near field, pressure signatures of the N-wave generated from projectiles are measured by 32-microphone ring array wrapped by cotton sheath. Records measured by the microphone array are used to demonstrate several key characteristics of the shock wave of supersonic projectile. All measurements made in this study can be a significant reference for developing guns, tanks, or the chassis of fighting vehicles.

  1. Melatonin attenuates thiocyanate-induced vasoconstriction in aortic rings

    Directory of Open Access Journals (Sweden)

    Alexander M. Prusa

    2017-11-01

    Full Text Available Cigarette smoking not only has a carcinogenic effect but also leads to an increase in arterial blood pressure. Besides its main components, i.e. nicotine, tar, and carbon monoxide, cigarette smoke also contains thiocyanate. Thiocyanate anions (SCN− arise from the detoxification of hydrogen cyanide and its plasma concentrations were found to correlate significantly with cigarette consumption. There is also evidence that atherosclerotic disease progression is much more rapid when serum SCN− levels are increased. Melatonin, a non-toxic indolamine with various physiologic functions, is believed to protect against inflammatory processes and oxidative stress. It has been demonstrated that melatonin serves as free radical scavenger and represents a potent antioxidant. Therefore, it is believed that melatonin with its atheroprotective effects may be useful either as a sole therapy or in conjunction with others. The aim of this study was to quantify the thiocyanate-induced vasomotor response in aortic tissue and further to examine the potential of melatonin in affecting the generated vasoreactivity. Aortic rings of adult male normotensive Wistar rats were cut into 4-mm rings. Following the administration of thiocyanate in various concentrations, vasomotor response of aortic vessel segments was measured. To assess the effect of melatonin on vasomotor activity, organ bath concentrations were modulated from 60 to 360 pM, which corresponds to physiologic plasma up to the levels of patients with regular oral intake of 3 mg of melatonin as a supplement. Thirty-six rat aortic rings were studied. When exposed to thiocyanate, vessel segments revealed vasoconstriction in a concentration-dependent manner. In rings which were preincubated with melatonin at a concentration of 360 pM, a 56.5% reduction of effect size could be achieved (4.09 ± 1.22 mN versus 9.41 ± 1.74 mN, P < 0.0001. Additionally, administration of 360 pM melatonin at a

  2. Emittance growth induced by electron cloud in proton storage rings

    CERN Document Server

    Benedetto, Elena; Coppa, G

    2006-01-01

    In proton and positron storage rings with many closely spaced bunches, a large number of electrons can accumulate in the beam pipe due to various mechanisms (photoemission, residual gas ionization, beam-induced multipacting). The so-formed electron cloud interacts with the positively charged bunches, giving rise to instabilities, emittance growth and losses. This phenomenon has been observed in several existing machines such as the CERN Super Proton Synchrotron (SPS), whose operation has been constrained by the electron-cloud problem, and it is a concern for the Large Hadron Collider (LHC), under construction at CERN. The interaction between the beam and the electron cloud has features which cannot be fully taken into account by the conventional and known theories from accelerators and plasma physics. Computer simulations are indispensable for a proper prediction and understanding of the instability dynamics. The main feature which renders the beam-cloud interactions so peculiar is that the the electron cloud...

  3. A new omnidirectional shear horizontal wave transducer using face-shear (d24) piezoelectric ring array.

    Science.gov (United States)

    Miao, Hongchen; Huan, Qiang; Wang, Qiangzhong; Li, Faxin

    2017-02-01

    The non-dispersive fundamental shear horizontal (SH 0 ) wave in plate-like structures is of practical importance in non-destructive testing (NDT) and structural health monitoring (SHM). Theoretically, an omnidirectional SH 0 transducer phased array system can be used to inspect defects in a large plate in the similar manner to the phased array transducers used in medical B-scan ultrasonics. However, very few omnidirectional SH 0 transducers have been proposed so far. In this work, an omnidirectional SH 0 wave piezoelectric transducer (OSH-PT) was proposed, which consists of a ring array of twelve face-shear (d 24 ) trapezoidal PZT elements. Each PZT element can produce face-shear deformation under applied voltage, resulting in circumferential shear deformation in the OSH-PT and omnidirectional SH 0 waves in the hosting plate. Both finite element simulations and experiments were conducted to examine the performance of the proposed OSH-PT. Experimental testing shows that the OSH-PT exhibits good omnidirectional properties, no matter it is used as a SH 0 wave transmitter or a SH 0 wave receiver. This work may greatly promote the applications of SH 0 waves in NDT and SHM. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Evanescent-wave cavity ring-down spectroscopy for enhanced detection of surface binding under flow injection analysis conditions

    NARCIS (Netherlands)

    Van Der Sneppen, L.; Ariese, F.; Gooijer, C.; Ubachs, W.

    2008-01-01

    In evanescent-wave cavity ring-down spectroscopy, one (or more) of the re°ections inside the cavity is a total internal re°ection (TIR) event. Only the evanescent wave associated with this TIR is being used for prob-ing the sample. This technique is therefore highly surface-speci-c and attractive

  5. Evaluation of radiation-induced degradation of silicon '0' ring

    International Nuclear Information System (INIS)

    Ikeshima, Yoshiaki; Shiraishi; Tadao; Sato, Ryuichi; Tanaka, Isao; Ichihashi, Yoshinori; Ito, Masayuki.

    1990-12-01

    Currently there is too few available data on mechanical properties of an 'O' ring made of organic material, which is used over an extensive period of time under actual Nuclear Reactor environmental conditions. The 'O' rings which were evaluated were made of Silicon Rubber, and are used to provide water tightness. The 'O' rings also served as a pressure boundary within the nozzle of the in-reactor tube in the Water Loop-2 (OWL-2) at the JMTR in Oarai, Ibaraki. The 'O' rings were subjected to a constant penetrating radiation (up to 3.46 kGy) over a period of thirteen (13) years. The effects on the mechanical properties of a Silicon Rubber 'O' Ring were evaluated after having been used over an extensive period of time in an actual in-reactor tube within a radiation environment; a full thirteen years in durations. In making comparison of the properties of other Silicon Rubber 'O' Rings. It was also found that these other 'O' rings were subject to Gamma Rays for a shorter period, but with the same amount of radiation as the 'O' rings in the reactor were supposedly to have received. The evaluation showed that a Silicon Rubber 'O' Ring could have been used for a period, as much as forty (40) years even with a (absorbed) dose of about 300 kGy, before the life expectancy of such an 'O' ring is fully met. It was also discovered that the mechanical properties of an Ethylene Propylene 'O' Rings (currently used in the new OWL-2 in-reactor tube) were much superior to those of the Silicon Rubber 'O' Rings. The Ethylene Propylene 'O' Rings had a live expectancy which was about three times that of a Silicon Rubber 'O' Rings. (author)

  6. Accuracy enhancement of laser induced breakdown spectra using permittivity and size optimized plasma confinement rings.

    Science.gov (United States)

    Li, An; Guo, Shuai; Wazir, Nasrullah; Chai, Ke; Liang, Liang; Zhang, Min; Hao, Yan; Nan, Pengfei; Liu, Ruibin

    2017-10-30

    The inevitable problems in laser induced breakdown spectroscopy are matrix effect and statistical fluctuation of the spectral signal, which can be partly avoided by utilizing a proper confined unit. The dependences of spectral signal enhancement on relative permittivity were studied by varying materials to confine the plasma, which include polytetrafluoroethylene(PTFE), nylon/dacron, silicagel, and nitrile-butadiene rubber (NBR) with the relative permittivity 2.2, ~3.3, 3.6, 8~13, 15~22. We found that higher relative permittivity rings induce stronger enhancement ability, which restricts the energy dissipation of plasma better and due to the reflected electromagnetic wave from the wall of different materials, the electromagnetic field of plasma can be well confined and makes the distribution of plasma more orderly. The spectral intensities of the characteristic lines Si I 243.5 nm and Si I 263.1 nm increased approximately 2 times with relative permittivity values from 2.2 to ~20. The size dependent enhancement of PTFE was further checked and the maximum gain was realized by using a confinement ring with a diameter size of 5 mm and a height of 3 mm (D5mmH3mm), and the rings with D2mmH1mm and D3mmH2mm also show higher enhancement factor. In view of peak shift, peak lost and accidental peaks in the obtained spectra were properly treated in data progressing; the spectral fluctuation decreased drastically for various materials with different relative permittivities as confined units, which means the core of plasma is stabilized, attributing to the confinement effect. Furthermore, the quantitative analysis in coal shows wonderful results-the prediction fitting coefficient R 2 reaches 0.98 for ash and 0.99 for both volatile and carbon.

  7. Miniature chemical sensor combining molecular recognition with evanescent wave cavity ring-down spectroscopy

    International Nuclear Information System (INIS)

    Pipino, Andrew C. R.

    2004-01-01

    A new chemical detection technology has been realized that addresses DOE environmental management needs. The new technology is based on a variant of the sensitive optical absorption technique, cavity ring-down spectroscopy (CRDS). Termed evanescent-wave cavity ring-down spectroscopy (EW-CRDS), the technology employs a miniature solid-state optical resonator having an extremely high Q-factor as the sensing element, where the high-Q is achieved by using ultra-low-attenuation optical materials, ultra-smooth surfaces, and ultra-high reflectivity coatings, as well as low-diffraction-loss designs. At least one total-internal reflection (TIR) mirror is integral to the resonator permitting the concomitant evanescent wave to probe the ambient environment. Several prototypes have been designed, fabricated, characterized, and applied to chemical detection. Moreover, extensions of the sensing concept have been explored to enhance selectivity, sensitivity, and range of application. Operating primarily in the visible and near IR regions, the technology inherently enables remote detection by optical fiber. Producing 11 archival publications, 5 patents, 19 invited talks, 4 conference proceedings, a CRADA, and a patent-license agreement, the project has realized a new chemical detection technology providing >100 times more sensitivity than comparable technologies, while also providing practical advantages

  8. Mathematical modeling of calcium waves induced by mechanical stimulation in keratinocytes.

    Directory of Open Access Journals (Sweden)

    Yasuaki Kobayashi

    Full Text Available Recent studies have shown that the behavior of calcium in the epidermis is closely related to the conditions of the skin, especially the differentiation of the epidermal keratinocytes and the permeability barrier function, and therefore a correct understanding of the calcium dynamics is important in explaining epidermal homeostasis. Here we report on experimental observations of in vitro calcium waves in keratinocytes induced by mechanical stimulation, and present a mathematical model that can describe the experimentally observed wave behavior that includes finite-range wave propagation and a ring-shaped pattern. A mechanism of the ring formation hypothesized by our model may be related to similar calcium propagation patterns observed during the wound healing process in the epidermis. We discuss a possible extension of our model that may serve as a tool for investigating the mechanisms of various skin diseases.

  9. Formation of moon induced gaps in dense planetary rings

    Science.gov (United States)

    Grätz, F.; Seiß, M.; Spahn, F.

    2017-09-01

    Recent works have shown that bodies embedded in planetary rings create S-shaped density modula- tions called propellers if their mass deceeds a certain threshold or cause a gap around the entire circumference of the disc if the embedded bodies mass exceeds it. Two counteracting physical processes govern the dynamics and determine what structure is created: The gravitational disturber excerts a torque on nearby disc particles, sweeping them away from itself on both sides thus depleting the discs density and forming a gap. Diffusive spreading of the disc material due to collisions counteracts the gravitational scattering and has the tendency to fill the gap. We develop a nonlinear diffusion model that accounts for those two counteracting processes and describes the azimutally averaged surface density profile an embedded moon creates in planetary rings. The gaps width depends on the moons mass, its radial position and the rings viscosity allowing us to estimate the rings viscosity in the vicinity of the Encke and Keeler gap in Saturns A-Ring and compare it to previous measurements. We show that for the Keeler gap the time derivative of the semi-major axis as derived by Goldreich and Tremaine 1980 is underestimated yielding an underestimated viscosity for the ring. We therefore derive a corrected expression for said time derivative by fitting the solutions of Hill's equations for an ensemble of test particles. Furthermore we estimate the masses for potentionally unseen moonlets in the C-Ring and Cassini division.

  10. Modeling of Mud-Wave Interaction: Mud-Induced Wave Transport & Wave-Induced Mud Transport

    National Research Council Canada - National Science Library

    Winterwerp, Johan C

    2007-01-01

    .... Also a new rheological model has been proposed to describe liquefaction of soft mud by waves, and the subsequent strength recovery after the passage of the waves. A scheme is presented on how to implement these formulations in Delft3D.

  11. Longitudinal elliptically polarized electromagnetic waves in off-diagonal magnetoelectric split-ring composites.

    Science.gov (United States)

    Chui, S T; Wang, Weihua; Zhou, L; Lin, Z F

    2009-07-22

    We study the propagation of plane electromagnetic waves through different systems consisting of arrays of split rings of different orientations. Many extraordinary EM phenomena were discovered in such systems, contributed by the off-diagonal magnetoelectric susceptibilities. We find a mode such that the electric field becomes elliptically polarized with a component in the longitudinal direction (i.e. parallel to the wavevector). Even though the group velocity [Formula: see text] and the wavevector k are parallel, in the presence of damping, the Poynting vector does not just get 'broadened', but can possess a component perpendicular to the wavevector. The speed of light can be real even when the product ϵμ is negative. Other novel properties are explored.

  12. Fractional conductance oscillations in quantum rings: wave packet picture of transport in a few-electron system

    International Nuclear Information System (INIS)

    Chwiej, T; Szafran, B

    2013-01-01

    We study electron transfer across a two-terminal quantum ring using a time-dependent description of the scattering process. For the considered scattering event the quantum ring is initially charged with one or two electrons, with another electron incident to the ring from the input channel. We study the electron transfer probability (T) as a function of the external magnetic field. We determine the periodicity of T for a varied number of electrons confined within the ring. For that purpose we develop a method to describe the wave packet dynamics for a few electrons participating in the scattering process, taking into full account the electron–electron correlations. We find that electron transfer across the quantum ring initially charged by a single electron acquires a distinct periodicity of half of the magnetic flux quantum (Φ 0 /2), corresponding to the formation of a transient two-electron state inside the ring. In the case of a three-electron scattering problem with two electrons initially occupying the ring, a period of Φ 0 /3 for T is formed in the limit of thin channels. The effect of disorder present in the confinement potential of the ring is also discussed. (paper)

  13. Fractional conductance oscillations in quantum rings: wave packet picture of transport in a few-electron system.

    Science.gov (United States)

    Chwiej, T; Szafran, B

    2013-04-17

    We study electron transfer across a two-terminal quantum ring using a time-dependent description of the scattering process. For the considered scattering event the quantum ring is initially charged with one or two electrons, with another electron incident to the ring from the input channel. We study the electron transfer probability (T) as a function of the external magnetic field. We determine the periodicity of T for a varied number of electrons confined within the ring. For that purpose we develop a method to describe the wave packet dynamics for a few electrons participating in the scattering process, taking into full account the electron-electron correlations. We find that electron transfer across the quantum ring initially charged by a single electron acquires a distinct periodicity of half of the magnetic flux quantum (Φ0/2), corresponding to the formation of a transient two-electron state inside the ring. In the case of a three-electron scattering problem with two electrons initially occupying the ring, a period of Φ0/3 for T is formed in the limit of thin channels. The effect of disorder present in the confinement potential of the ring is also discussed.

  14. Alfven wave resonances and flow induced by nonlinear Alfven waves in a stratified atmosphere

    International Nuclear Information System (INIS)

    Stark, B. A.; Musielak, Z. E.; Suess, S. T.

    1996-01-01

    A nonlinear, time-dependent, ideal MHD code has been developed and used to compute the flow induced by nonlinear Alfven waves propagating in an isothermal, stratified, plane-parallel atmosphere. The code is based on characteristic equations solved in a Lagrangian frame. Results show that resonance behavior of Alfven waves exists in the presence of a continuous density gradient and that the waves with periods corresponding to resonant peaks exert considerably more force on the medium than off-resonance periods. If only off-peak periods are considered, the relationship between the wave period and induced longitudinal velocity shows that short period WKB waves push more on the background medium than longer period, non-WKB, waves. The results also show the development of the longitudinal waves induced by finite amplitude Alfven waves. Wave energy transferred to the longitudinal mode may provide a source of localized heating

  15. Observation of electromagnetically induced transparency and absorption in Yttrium Iron Garnet loaded split ring resonator

    Science.gov (United States)

    Tay, Z. J.; Soh, W. T.; Ong, C. K.

    2018-04-01

    In this paper, we propose a new method of controlling microwave transmission from Electromagnetically Induced Absorption (EIA) to Electromagnetically Induced Transparency (EIT). EIA describes the state where the system strongly absorbs microwaves, whereas EIT describes the state in which the system is transparent to microwaves. Control is achieved via coupling of the 3 GHz photon mode of a metamaterial Split Ring Resonator (SRR) to the spin wave magnon modes of a Yttrium Iron Garnet (YIG) bulk. The system is described by a 2-body interaction matrix with an additional fitting parameter τ which takes into account the fact that the microstrip feed line could excite the SRR as well as the YIG. The parameter τ reveals the effect of geometry and shielding on the coupling behaviour and gives rise to unique physics. In low τ (τ ⩽ 2) configurations, only EIT is reported. However, in high τ (τ ≈ 10) configurations, EIA is reported. Furthermore, we report that the system can be easily changed from a low τ to high τ configuration by shielding the SRR from the microstrip with a thin metal piece. Varying the τ parameter through shielding is thus proposed as a new method of controlling the microwave transmission at the coupling region.

  16. A new traveling wave ultrasonic motor using thick ring stator with nested PZT excitation.

    Science.gov (United States)

    Chen, Weishan; Shi, Shengjun; Liu, Yingxiang; Li, Pei

    2010-05-01

    To avoid the disadvantages of conventional traveling wave ultrasonic motors--lower efficiency PZT working mode of d(31), fragility of the PZT element under strong excitation, fatigue of the adhesive layer under harsh environmental conditions, and low volume of the PZT material in the stator--a new type of traveling wave ultrasonic motor is presented in this paper. Here we implement the stator by nesting 64 PZT stacks in 64 slots specifically cut in a thick metal ring and 64 block springs nested within another 64 slots to produce preloading on the PZT stacks. In this new design, the d33 mode of the PZT is used to excite the flexural vibrations of the stator, and fragility of the PZT ceramics and fatigue of the adhesive layer are no longer an issue. The working principle, FEM simulation, fabrication, and performance measurements of a prototype motor were demonstrated to validate the proposed ideas. Typical output of the prototype motor is no-load speed of 15 rpm and maximum torque of 7.96 N x m. Further improvement will potentially enhance its features by increasing the accuracy in fabrication and adopting appropriate frictional material into the interface between the stator and the rotor.

  17. Vortex-ring-induced large bubble entrainment during drop impact

    KAUST Repository

    Thoraval, Marie-Jean; Li, Yangfan; Thoroddsen, Sigurdur T

    2016-01-01

    , produced in the neck between the drop and the pool, controls the crater deformations and pinchoff. However, it is not the strongest vortex rings that are responsible for the large bubbles, as they interact too strongly with the pool surface and self

  18. Assembly of silver nanowire ring induced by liquid droplet

    Science.gov (United States)

    Seong, Baekhoon; Park, Hyun Sung; Chae, Ilkyeong; Lee, Hyungdong; Wang, Xiaofeng; Jang, Hyung-Seok; Jung, Jaehyuck; Lee, Changgu; Lin, Liwei; Byun, Doyoung

    2017-11-01

    Several forces in the liquid droplet drive the nanomaterials to naturally form an assembled structure. During evaporation of a liquid droplet, nanomaterials can move to the rim of the droplet by convective flow and capillary flow, due to the difference in temperature between the top and contact line of the droplet. Here, we demonstrate a new, simple and scalable technology for the fabrication of ring-shaped Ag NWs by a spraying method. We experimentally identify the compressive force of the droplet driven by surface tension as the key mechanism for the self-assembly of ring structures. We investigated the progress of ring shape formation of Ag NWs according to the droplet size with theoretically calculated optimal conditions. As such, this self-assembly technique of making ring-shaped structures from Ag NWs could be applied to other nanomaterials. This work was supported by the New & Renewable Energy R&D program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) Grant funded by the Korea government Ministry of Trade, Industry and Energy. (No. 20163010071630).

  19. Vortex-ring-induced large bubble entrainment during drop impact

    KAUST Repository

    Thoraval, Marie-Jean

    2016-03-29

    For a limited set of impact conditions, a drop impacting onto a pool can entrap an air bubble as large as its own size. The subsequent rise and rupture of this large bubble plays an important role in aerosol formation and gas transport at the air-sea interface. The large bubble is formed when the impact crater closes up near the pool surface and is known to occur only for drops that are prolate at impact. Herein we use experiments and numerical simulations to show that a concentrated vortex ring, produced in the neck between the drop and the pool, controls the crater deformations and pinchoff. However, it is not the strongest vortex rings that are responsible for the large bubbles, as they interact too strongly with the pool surface and self-destruct. Rather, it is somewhat weaker vortices that can deform the deeper craters, which manage to pinch off the large bubbles. These observations also explain why the strongest and most penetrating vortex rings emerging from drop impacts are not produced by oblate drops but by more prolate drop shapes, as had been observed in previous experiments.

  20. Bingham liquid flow between two cylinders induced by inner ring rotation

    Science.gov (United States)

    Jaroslav, Štigler; Simona, Fialová

    2017-09-01

    This paper deals with the fluid flow between two cylinders induced by inner ring rotation. The gap width between the cylinders, in case that they are both concentric, is 1mm, the gap and inner ring radius ratio 0.013 and the radius ratio 0.987. Attention is focused on rotation speed and eccentricity influence on the flow. Calculations were done for both Newtonian liquid and Bingham plastic liquid with the yield stress threshold 50 Pa.

  1. Modulated spin waves and robust quasi-solitons in classical Heisenberg rings

    International Nuclear Information System (INIS)

    Schmidt, Heinz-Juergen; Schroeder, Christian; Luban, Marshall

    2011-01-01

    We investigate the dynamical behavior of finite rings of classical spin vectors interacting via nearest-neighbor isotropic exchange in an external magnetic field. Our approach is to utilize the solutions of a continuum version of the discrete spin equations of motion (EOM) which we derive by assuming continuous modulations of spin wave solutions of the EOM for discrete spins. This continuum EOM reduces to the Landau-Lifshitz equation in a particular limiting regime. The usefulness of the continuum EOM is demonstrated by the fact that the time-evolved numerical solutions of the discrete spin EOM closely track the corresponding time-evolved solutions of the continuum equation. It is of special interest that our continuum EOM possesses soliton solutions, and we find that these characteristics are also exhibited by the corresponding solutions of the discrete EOM. The robustness of solitons is demonstrated by considering cases where initial states are truncated versions of soliton states and by numerical simulations of the discrete EOM equations when the spins are coupled to a heat bath at finite temperatures. (paper)

  2. Self-Consistent Model of Magnetospheric Electric Field, Ring Current, Plasmasphere, and Electromagnetic Ion Cyclotron Waves: Initial Results

    Science.gov (United States)

    Gamayunov, K. V.; Khazanov, G. V.; Liemohn, M. W.; Fok, M.-C.; Ridley, A. J.

    2009-01-01

    Further development of our self-consistent model of interacting ring current (RC) ions and electromagnetic ion cyclotron (EMIC) waves is presented. This model incorporates large scale magnetosphere-ionosphere coupling and treats self-consistently not only EMIC waves and RC ions, but also the magnetospheric electric field, RC, and plasmasphere. Initial simulations indicate that the region beyond geostationary orbit should be included in the simulation of the magnetosphere-ionosphere coupling. Additionally, a self-consistent description, based on first principles, of the ionospheric conductance is required. These initial simulations further show that in order to model the EMIC wave distribution and wave spectral properties accurately, the plasmasphere should also be simulated self-consistently, since its fine structure requires as much care as that of the RC. Finally, an effect of the finite time needed to reestablish a new potential pattern throughout the ionosphere and to communicate between the ionosphere and the equatorial magnetosphere cannot be ignored.

  3. Chemical leucoderma induced by ear-ring stoppers made of polyvinyl chloride

    Directory of Open Access Journals (Sweden)

    Reena Sharma

    2012-01-01

    Full Text Available We report a case of chemical leucoderma (CL in a 15-year-old girl, who developed patterned depigmentation at the back of both ear lobules after contact with plastic ear-ring stoppers made of polyvinyl chloride (PVC after continuous use for 6-7 months. Patch test with Indian standard series and cosmetic series was negative after 48 h, but she refused patch testing for extended duration as the possibility of induced depigmentation at the test site was unacceptable to her. To the best of our knowledge, this is the first report of plastic ear-ring stopper induced CL.

  4. Modeling Restrained Shrinkage Induced Cracking in Concrete Rings Using the Thick Level Set Approach

    Directory of Open Access Journals (Sweden)

    Rebecca Nakhoul

    2018-03-01

    Full Text Available Modeling restrained shrinkage-induced damage and cracking in concrete is addressed herein. The novel Thick Level Set (TLS damage growth and crack propagation model is used and adapted by introducing shrinkage contribution into the formulation. The TLS capacity to predict damage evolution, crack initiation and growth triggered by restrained shrinkage in absence of external loads is evaluated. A study dealing with shrinkage-induced cracking in elliptical concrete rings is presented herein. Key results such as the effect of rings oblateness on stress distribution and critical shrinkage strain needed to initiate damage are highlighted. In addition, crack positions are compared to those observed in experiments and are found satisfactory.

  5. Compressible Vortex Ring

    Science.gov (United States)

    Elavarasan, Ramasamy; Arakeri, Jayawant; Krothapalli, Anjaneyulu

    1999-11-01

    The interaction of a high-speed vortex ring with a shock wave is one of the fundamental issues as it is a source of sound in supersonic jets. The complex flow field induced by the vortex alters the propagation of the shock wave greatly. In order to understand the process, a compressible vortex ring is studied in detail using Particle Image Velocimetry (PIV) and shadowgraphic techniques. The high-speed vortex ring is generated from a shock tube and the shock wave, which precedes the vortex, is reflected back by a plate and made to interact with the vortex. The shadowgraph images indicate that the reflected shock front is influenced by the non-uniform flow induced by the vortex and is decelerated while passing through the vortex. It appears that after the interaction the shock is "split" into two. The PIV measurements provided clear picture about the evolution of the vortex at different time interval. The centerline velocity traces show the maximum velocity to be around 350 m/s. The velocity field, unlike in incompressible rings, contains contributions from both the shock and the vortex ring. The velocity distribution across the vortex core, core diameter and circulation are also calculated from the PIV data.

  6. The Measurement of Aerosol Optical Properties Using Continuous Wave Cavity Ring-Down Techniques

    Science.gov (United States)

    Strawa, A. W.; Owano, T.; Castaneda, R.; Baer, D. S.; Paldus, B. A.; Gore, Warren J. (Technical Monitor)

    2002-01-01

    Large uncertainties in the effects that aerosols have on climate require improved in-situ measurements of extinction coefficient and single-scattering albedo. This abstract describes the use of continuous wave cavity ring-down (CW-CRD) technology to address this problem. The innovations in this instrument are the use of CW-CRD to measure aerosol extinction coefficient, the simultaneous measurement of scattering coefficient, and small size suitable for a wide range of aircraft applications. Our prototype instrument measures extinction and scattering coefficient at 690 nm and extinction coefficient at 1550 nm. The instrument itself is small (60 x 48 x 15 cm) and relatively insensitive to vibrations. The prototype instrument has been tested in our lab and used in the field. While improvements in performance are needed, the prototype has been shown to make accurate and sensitive measurements of extinction and scattering coefficients. Combining these two parameters, one can obtain the single-scattering albedo and absorption coefficient, both important aerosol properties. The use of two wavelengths also allows us to obtain a quantitative idea of the size of the aerosol through the Angstrom exponent. Minimum sensitivity of the prototype instrument is 1.5 x 10(exp -6)/m (1.5/Mm). Validation of the measurement of extinction coefficient has been accomplished by comparing the measurement of calibration spheres with Mie calculations. This instrument and its successors have potential to help reduce uncertainty currently associated with aerosol optical properties and their spatial and temporal variation. Possible applications include studies of visibility, climate forcing by aerosol, and the validation of aerosol retrieval schemes from satellite data.

  7. Noise induced chaos in optically driven colloidal rings.

    Science.gov (United States)

    Roichman, Yael; Zaslavsky, George; Grier, David G.

    2007-03-01

    Given a constant flux of energy, many driven dissipative systems rapidly organize themselves into configurations that support steady state motion. Examples include swarming of bacterial colonies, convection in shaken sandpiles, and synchronization in flowing traffic. How simple objects interacting in simple ways self-organize generally is not understood, mainly because so few of the available experimental systems afford the necessary access to their microscopic degrees of freedom. This talk introduces a new class of model driven dissipative systems typified by three colloidal spheres circulating around a ring-like optical trap known as an optical vortex. By controlling the interplay between hydrodynamic interactions and fixed disorder we are able to drive a transition from a previously predicted periodic steady state to fully developed chaos. In addition, by tracking both microscopic trajectories and macroscopic collective fluctuations the relation between the onset of microscopic weak chaos and the evolution of space-time self-similarity in macroscopic transport properties is revealed. In a broader scope, several optical vortices can be coupled to create a large dissipative system where each building block has internal degrees of freedom. In such systems the little understood dynamics of processes like frustration and jamming, fluctuation-dissipation relations and the propagation of collective motion can be tracked microscopically.

  8. Cell-autonomous correction of ring chromosomes in human induced pluripotent stem cells

    Science.gov (United States)

    Bershteyn, Marina; Hayashi, Yohei; Desachy, Guillaume; Hsiao, Edward C.; Sami, Salma; Tsang, Kathryn M.; Weiss, Lauren A.; Kriegstein, Arnold R.; Yamanaka, Shinya; Wynshaw-Boris, Anthony

    2014-03-01

    Ring chromosomes are structural aberrations commonly associated with birth defects, mental disabilities and growth retardation. Rings form after fusion of the long and short arms of a chromosome, and are sometimes associated with large terminal deletions. Owing to the severity of these large aberrations that can affect multiple contiguous genes, no possible therapeutic strategies for ring chromosome disorders have been proposed. During cell division, ring chromosomes can exhibit unstable behaviour leading to continuous production of aneuploid progeny with low viability and high cellular death rate. The overall consequences of this chromosomal instability have been largely unexplored in experimental model systems. Here we generated human induced pluripotent stem cells (iPSCs) from patient fibroblasts containing ring chromosomes with large deletions and found that reprogrammed cells lost the abnormal chromosome and duplicated the wild-type homologue through the compensatory uniparental disomy (UPD) mechanism. The karyotypically normal iPSCs with isodisomy for the corrected chromosome outgrew co-existing aneuploid populations, enabling rapid and efficient isolation of patient-derived iPSCs devoid of the original chromosomal aberration. Our results suggest a fundamentally different function for cellular reprogramming as a means of `chromosome therapy' to reverse combined loss-of-function across many genes in cells with large-scale aberrations involving ring structures. In addition, our work provides an experimentally tractable human cellular system for studying mechanisms of chromosomal number control, which is of critical relevance to human development and disease.

  9. Outer Measures on a Commutative Ring Induced by Measures on Its Spectrum

    Directory of Open Access Journals (Sweden)

    Dudzik Dariusz

    2017-09-01

    Full Text Available On a commutative ring R we study outer measures induced by measures on Spec(R. The focus is on examples of such outer measures and on subsets of R that satisfy the Carathéodory condition.

  10. Wave Induced Saline Intrusion in Sea Outfalls

    DEFF Research Database (Denmark)

    Larsen, Torben; Burrows, Richard

    1989-01-01

    Experimental and numerical studies have shown that the influence of wave increases the tendency of saline intrusion in multi-riser sea outfalls. The flow field in the diffusor under such unsteady and inhomogeneous circumstances is in general very complex, but when sufficient wave energy is dissip...

  11. Wave induced supersonic rotation in mirrors

    Science.gov (United States)

    Fetterman, Abraham

    2010-11-01

    Wave-particle interactions in ExB supersonically rotating plasmas feature an unusual effect: particles are diffused by waves in both potential energy and kinetic energy [1]. This wave-particle interaction generalizes the alpha channeling effect, in which radio frequency waves are used to remove alpha particles collisionlessly at low energy. In rotating plasmas, the alpha particles may be removed at low energy through the loss cone, and the energy lost may be transferred to the radial electric field. This eliminates the need for electrodes in the mirror throat, which have presented serious technical issues in past rotating plasma devices. A particularly simple way to achieve this effect is to use a high azimuthal mode number perturbation on the magnetic field [2]. In the rotating frame, this perturbation is seen as a wave near the alpha particle cyclotron harmonic, and can break the azimuthal symmetry and magnetic moment conservation without changing the particle's total energy. The particle may exit if it reduces its kinetic energy and becomes more trapped if it gains kinetic energy, leading to a steady state current that maintains the field. Simulations of single particles in rotating mirrors show that a stationary wave can extract enough energy from alpha particles for a reactor to be self-sustaining. Rotation can also be sustained by waves in plasmas without a kinetic energy source. This type of wave has been considered for plasma centrifuges used for isotope separation [3]. [4pt] [1] A. J. Fetterman and N. J. Fisch, Phys Rev Lett 101, 205003 (2008). [0pt] [2] A. J. Fetterman and N. J. Fisch, Phys. Plasmas 17, 042112 (2010). [0pt] [3] A. J. Fetterman and N. J. Fisch, Plasma Sources Sci. Tech. 18, 045003 (2009).

  12. Time variations of hf induced plasma waves

    International Nuclear Information System (INIS)

    Showen, R.L.

    1976-01-01

    Intense plasma waves are generated by an HF pump wave in an ionospheric heating experiment at the Arecibo Observatory. These plasma waves can be observed as enhancements to the ion and plasma lines of the incoherent backscatter echo. The enhancements can be three or four orders of magnitude more intense than the unenhanced lines, and tend to fluctuate wildly. Both the purely growing and the decay mode parametric instabilities are present. When the pump wave is turned on abruptly the enhancements develop in time in a repeatable manner. A rather remarkable feature on time scales of seconds is an overshoot in instability power. These overshoots occur frequently but not universally and last for 1 to 6 seconds. They can have a magnitude from ten to hundreds of times the average instability level. Field aligned irregularities may be the cause of the overshoots. The overshoots appear definitely related to an unusually rapid rise in measured electron temperature that cannot be understood in terms of ohmic energy deposition. On time scales of milliseconds there is a ''mini-overshoot'' before the growth of the instability to a large value. The spectral details also change in a striking manner. The instabilities can first be detected 2 to 4 msec after the pump wave turn-on. The decay mode is present as well as a broad featureless ''noise bump'', which partially sharpens into a line as time progresses. These changes of the spectra in time seem to run counter to the currently accepted theories of plasma wave saturation

  13. Tunable optical analog to electromagnetically induced transparency in graphene-ring resonators system.

    Science.gov (United States)

    Wang, Yonghua; Xue, Chenyang; Zhang, Zengxing; Zheng, Hua; Zhang, Wendong; Yan, Shubin

    2016-12-12

    The analogue of electromagnetically induced transparency in optical ways has shown great potential in optical delay and quantum-information technology due to its flexible design and easy implementation. The chief drawback for these devices is the bad tunability. Here we demonstrate a tunable optical transparency system formed by graphene-silicon microrings which could control the transparent window by electro-optical means. The device consists of cascaded coupled ring resonators and a graphene/graphene capacitor which integrated on one of the rings. By tuning the Fermi level of the graphene sheets, we can modulate the round-trip ring loss so that the transparency window can be dynamically tuned. The results provide a new method for the manipulation and transmission of light in highly integrated optical circuits and quantum information storage devices.

  14. Wave Induced Stresses Measured at the Wave Dragon Nissum Bredning Prototype

    DEFF Research Database (Denmark)

    Corona, L.; Kofoed, Jens Peter

    2006-01-01

    The paper describes the wave induced loading on the overtopping based wave energy converter Wave Dragon. Focus is put on the junction between the main body and the reflector, also called the "shoulder part", where large cross sectional forces and bending moments acts. There are two main objectives...... for this paper, first to verify the FEM results obtained by Niras, Danish society in charge of the finite element modelling and structural design, and then to make a first experimental fatigue analysis of a particular part of the Wave Dragon. This last part shall be considered as an exercise for the further work...

  15. Wave-induced Ship Hull Vibrations in Stochastic Seaways

    DEFF Research Database (Denmark)

    Jensen, Jørgen Juncher; Dogliani, M.

    1996-01-01

    A theoretical Study is undertaken on the determination of wave-induced loads in flexible ship hulls. The calculations are performed within the framework of a non-linear, quadratic strip theory formulated in the frequency domain. Included are non-linear effects due to changes in added mass......, hydrodynamic damping and water line breadth with sectional immersion in waves. The study is limited to continuous excitations from the waves and thus transient so-called whipping vibrations due to slamming loads are not considered.Because of the non-linearities the ship hull responses become non...... to the large separation between dominating wave frequencies and the lowest two-node frequency of the hull beam. Both extreme value predictions and fatigue damage are considered.For a fast container ship the rigid body and two-node (springing) vertical wave-induced bending moments amidship are calculated...

  16. Biological effects of laser-induced stress waves

    International Nuclear Information System (INIS)

    Doukas, A.; Lee, S.; McAuliffe, D.

    1995-01-01

    Laser-induced stress waves can be generated by one of the following mechanisms: Optical breakdown, ablation or rapid heating of an absorbing medium. These three modes of laser interaction with matter allow the investigation of cellular and tissue responses to stress waves with different characteristics and under different conditions. The most widely studied phenomena are those of the collateral damage seen in photodisruption in the eye and in 193 run ablation of cornea and skin. On the other hand, the therapeutic application of laser-induced stress waves has been limited to the disruption of noncellular material such as renal stones, atheromatous plaque and vitreous strands. The effects of stress waves to cells and tissues can be quite disparate. Stress waves can fracture tissue, damage cells, and increase the permeability of the plasma membrane. The viability of cell cultures exposed to stress waves increases with the peak stress and the number of pulses applied. The rise time of the stress wave also influences the degree of cell injury. In fact, cell viability, as measured by thymidine incorporation, correlates better with the stress gradient than peak stress. Recent studies have also established that stress waves induce a transient increase of the permeability of the plasma membrane in vitro. In addition, if the stress gradient is below the damage threshhold, the cells remain viable. Thus, stress waves can be useful as a means of drug delivery, increasing the intracellular drug concentration and allowing the use of drugs which are impermeable to the cell membrane. The present studies show that it is important to create controllable stress waves. The wavelength tunability and the micropulse structure of the free electron laser is ideal for generating stress waves with independently adjustable parameters, such as rise time, duration and peak stress

  17. Time-dependent wave packet simulations of transport through Aharanov-Bohm rings with an embedded quantum dot.

    Science.gov (United States)

    Kreisbeck, C; Kramer, T; Molina, R A

    2017-04-20

    We have performed time-dependent wave packet simulations of realistic Aharonov-Bohm (AB) devices with a quantum dot embedded in one of the arms of the interferometer. The AB ring can function as a measurement device for the intrinsic transmission phase through the quantum dot, however, care has to be taken in analyzing the influence of scattering processes in the junctions of the interferometer arms. We consider a harmonic quantum dot and show how the Darwin-Fock spectrum emerges as a unique pattern in the interference fringes of the AB oscillations.

  18. Impact induced solitary wave propagation through a woodpile structure

    International Nuclear Information System (INIS)

    Kore, R; Waychal, A; Yadav, P; Shelke, A; Agarwal, S; Sahoo, N; Uddin, Ahsan

    2016-01-01

    In this paper, we investigate solitary wave propagation through a one-dimensional woodpile structure excited by low and high velocity impact. Woodpile structures are a sub-class of granular metamaterial, which supports propagation of nonlinear waves. Hertz contact law governs the behavior of the solitary wave propagation through the granular media. Towards an experimental study, a woodpile structure was fabricated by orthogonally stacking cylindrical rods. A shock tube facility has been developed to launch an impactor on the woodpile structure at a velocity of 30 m s −1 . Embedded granular chain sensors were fabricated to study the behavior of the solitary wave. The impact induced stress wave is studied to investigate solitary wave parameters, i.e. contact force, contact time, and solitary wave velocity. With the aid of the experimental setup, numerical simulations, and a theoretical solution based on the long wavelength approximation, formation of the solitary wave in the woodpile structure is validated to a reasonable degree of accuracy. The nondispersive and compact supported solitary waves traveling at sonic wave velocity offer unique properties that could be leveraged for application in nondestructive testing and structural health monitoring. (paper)

  19. Continuous-wave singly resonant optical parametric oscillator placed inside a ring laser

    DEFF Research Database (Denmark)

    Abitan, Haim; Buchhave, Preben

    2003-01-01

    A cw singly resonant optical parametric oscillator (SRO) was built and placed inside the cavity of a ring laser. The system consists of a diode-end-pumped Nd:YVO4 ring laser with intracavity periodically poled lithium niobate as the nonlinear gain medium of the SRO. When the laser was operated...... in a unidirectional mode, we obtained more than 520 mW of signal power in one beam. When the laser was operated in a bidirectional mode, we obtained 600 mW of signal power (300 mW in two separate beams). The power and the spectral features of the laser in the unidirectional and bidirectional modes were measured while...... the laser was coupled with the SRO. The results show that it is preferable to couple a SRO with a unidirectional ring laser....

  20. Effects of ship-induced waves on aquatic ecosystems.

    Science.gov (United States)

    Gabel, Friederike; Lorenz, Stefan; Stoll, Stefan

    2017-12-01

    Most larger water bodies worldwide are used for navigation, and the intensity of commercial and recreational navigation is expected to further increase. Navigation profoundly affects aquatic ecosystems. To facilitate navigation, rivers are trained and developed, and the direct effects of navigation include chemical and biological impacts (e.g., inputs of toxic substances and dispersal of non-native species, respectively). Furthermore, propagating ships create hydrodynamic alterations, often simply summarized as waves. Although ship-induced waves are recognized as influential stressors, knowledge on their effects is poorly synthesized. We present here a review on the effects of ship-induced waves on the structure, function and services of aquatic ecosystems based on more than 200 peer reviewed publications and technical reports. Ship-induced waves act at multiple organizational levels and different spatial and temporal scales. All the abiotic and biotic components of aquatic ecosystems are affected, from the sediment and nutrient budget to the planktonic, benthic and fish communities. We highlight how the effects of ship-induced waves cascade through ecosystems and how different effects interact and feed back into the ecosystem finally leading to altered ecosystem services and human health effects. Based on this synthesis of wave effects, we discuss strategies for mitigation. This may help to develop scientifically based and target-oriented management plans for navigational waters that optimize abiotic and biotic integrity and their ecosystem services and uses. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Several localized waves induced by linear interference between a nonlinear plane wave and bright solitons

    Science.gov (United States)

    Qin, Yan-Hong; Zhao, Li-Chen; Yang, Zhan-Ying; Yang, Wen-Li

    2018-01-01

    We investigate linear interference effects between a nonlinear plane wave and bright solitons, which are admitted by a pair-transition coupled two-component Bose-Einstein condensate. We demonstrate that the interference effects can induce several localized waves possessing distinctive wave structures, mainly including anti-dark solitons, W-shaped solitons, multi-peak solitons, Kuznetsov-Ma like breathers, and multi-peak breathers. Specifically, the explicit conditions for them are clarified by a phase diagram based on the linear interference properties. Furthermore, the interactions between these localized waves are discussed. The detailed analysis indicates that the soliton-soliton interaction induced phase shift brings the collision between these localized waves which can be inelastic for solitons involving collision and can be elastic for breathers. These characters come from the fact that the profile of solitons depends on the relative phase between bright solitons and a plane wave, and the profile of breathers does not depend on the relative phase. These results would motivate more discussions on linear interference between other nonlinear waves. Specifically, the solitons or breathers obtained here are not related to modulational instability. The underlying reasons are discussed in detail. In addition, possibilities to observe these localized waves are discussed in a two species Bose-Einstein condensate.

  2. Wave-induced current considering wave-tide interaction in Haeundae

    Science.gov (United States)

    Lim, Hak Soo

    2017-04-01

    The Haeundae, located at the south eastern end of the Korean Peninsula, is a famous beach, which has an approximately 1.6 km long and 70 m wide coastline. The beach has been repeatedly eroded by the swell waves caused by typhoons in summer and high waves originating in the East Sea in winter. The Korean government conducted beach restoration projects including beach nourishment (620,000 m3) and construction of two submerged breakwaters near both ends of the beach. To prevent the beach erosion and to support the beach restoration project, the Korean government initiated a R&D project, the development of coastal erosion control technology since 2013. As a part of the project, we have been measuring waves and currents at a water depth of 22 m, 1.8 km away from the beach using an acoustic wave and current meter (AWAC) continuously for more than three years; we have also measured waves and currents intensively near the surf-zone in summer and winter. In this study, a numerical simulation using a wave and current coupled model (ROMS-SWAN) was conducted for determining the wave-induced current considering seasonal swell waves (Hs : 2.5 m, Tp: 12 s) and for better understanding of the coastal process near the surf-zone in Haeundae. By comparing the measured and simulated results, we found that cross-shore current during summer is mainly caused by the eddy produced by the wave-induced current near the beach, which in turn, is generated by the strong waves coming from the SSW and S directions. During other seasons, longshore wave-induced current is produced by the swell waves coming from the E and ESE directions. The longshore current heading west toward Dong-Back Island, west end of the beach, during all the seasons and eddy current toward Mipo-Port, east end of the beach, in summer which is well matched with the observed residual current. The wave-induced current with long-term measurement data is incorporated in simulation of sediment transport modeling for developing

  3. Wave Induced Loading and Stability of Rubble Mound Breakwaters

    DEFF Research Database (Denmark)

    Hald, Tue

    conducting model tests very large variability in e.g. the degree of stability is observed. This background motivated the investigations conducted in the present study. The objective was to investigate and clarify which wave parameters are important for the hydraulic stability of the armour layer on typical...... rubble mound breakwaters. Furthermore, it was intended to quantify the influence on the stability of each parameter. Focus was put on the wave induced loading on single armour stones and the relation to the stability. Based on existing literature the state of physical understanding of the processes...... and the stability were investigated. At Aalborg University model tests with an idealized model of a rubble mound breakwater were conducted and formed the basis for a detailed parametric investigation of the wave induced loading. Based on analyses of the experimental data wave-force models were derived containing...

  4. Test particle modeling of wave-induced energetic electron precipitation

    International Nuclear Information System (INIS)

    Chang, H.C.; Inan, U.S.

    1985-01-01

    A test particle computer model of the precipitation of radiation belt electrons is extended to compute the dynamic energy spectrum of transient electron fluxes induced by short-duration VLF wave packets traveling along the geomagnetic field lines. The model is adapted to estimate the count rate and associated spectrum of precipitated electrons that would be observed by satellite-based particle detectors with given geometric factor and orientation with respect to the magnetic field. A constant-frequency wave pulse and a lightning-induced whistler wave packet are used as examples of the stimulating wave signals. The effects of asymmetry of particle mirror heights in the two hemispheres and the atmospheric backscatter of loss cone particles on the computed precipitated fluxes are discussed

  5. Strategy of ring-shaped aggregates in excitation energy transfer for removing disorder-induced shielding

    International Nuclear Information System (INIS)

    Tei, Go; Nakatani, Masatoshi; Ishihara, Hajime

    2013-01-01

    Peripheral light harvesting complex (LH2), which is found in photosynthetic antenna systems of purple photosynthetic bacteria, has important functions in the photosynthetic process, such as harvesting sunlight and transferring its energy to the photosynthetic reaction center. The key component in excitation energy transfer (EET) between LH2s is B850, which is a characteristic ring-shaped aggregate of pigments usually formed by 18 or 16 bacteriochlorophylls in LH2. We theoretically study the strategy of the ring-shaped aggregate structure, which maximizes EET efficiency, by using the standard Frenkel exciton model and the self-consistent calculation method for the Markovian quantum master equation and Maxwell equation. As a result, we have revealed a simple but ingenious strategy of the ring-shaped aggregate structure. The combination of three key properties of the ring unit system maximizes the EET efficiency, namely the large dipole moment of aggregates causes the basic improvement of EET efficiency, and the isotropic nature and the large occupying area are critically effective to remove the disorder-induced shielding that inhibits EET in the presence of the randomness of orientation and alignment of carriers of excitation energy. (paper)

  6. Strategy of ring-shaped aggregates in excitation energy transfer for removing disorder-induced shielding

    Science.gov (United States)

    Tei, Go; Nakatani, Masatoshi; Ishihara, Hajime

    2013-06-01

    Peripheral light harvesting complex (LH2), which is found in photosynthetic antenna systems of purple photosynthetic bacteria, has important functions in the photosynthetic process, such as harvesting sunlight and transferring its energy to the photosynthetic reaction center. The key component in excitation energy transfer (EET) between LH2s is B850, which is a characteristic ring-shaped aggregate of pigments usually formed by 18 or 16 bacteriochlorophylls in LH2. We theoretically study the strategy of the ring-shaped aggregate structure, which maximizes EET efficiency, by using the standard Frenkel exciton model and the self-consistent calculation method for the Markovian quantum master equation and Maxwell equation. As a result, we have revealed a simple but ingenious strategy of the ring-shaped aggregate structure. The combination of three key properties of the ring unit system maximizes the EET efficiency, namely the large dipole moment of aggregates causes the basic improvement of EET efficiency, and the isotropic nature and the large occupying area are critically effective to remove the disorder-induced shielding that inhibits EET in the presence of the randomness of orientation and alignment of carriers of excitation energy.

  7. Deep-water bedforms induced by refracting Internal Solitary Waves

    Science.gov (United States)

    Falcini, Federico; Droghei, Riccardo; Casalbore, Daniele; Martorelli, Eleonora; Mosetti, Renzo; Sannino, Gianmaria; Santoleri, Rosalia; Latino Chiocci, Francesco

    2017-04-01

    Subaqueous bedforms (or sand waves) are typically observed in those environments that are exposed to strong currents, characterized by a dominant unidirectional flow. However, sand-wave fields may be also observed in marine environments where no such current exists; the physical processes driving their formation are enigmatic or not well understood. We propose that internal solitary waves (ISWs), induced by tides, can produce an effective, unidirectional boundary flow filed that forms asymmetric sand waves. We test this idea by examining a sand-wave field off the Messina Strait, where we hypothesize that ISWs formed at the interface between intermediate and surface waters are refracted by topography. Hence, we argue that the deflected pattern (i.e., the depth-dependent orientation) of the sand-wave field is due to refraction of such ISWs. Combining field observations and numerical modelling, we show that ISWs can account for three key features: ISWs produce fluid velocities capable of mobilizing bottom sediments; the predicted refraction pattern resulting from the interaction of ISWs with bottom topography matches the observed deflection of the sand waves; and predicted migration rates of sand waves match empirical estimates. This work shows how ISWs may contribute to sculpting the structure of continental margins and it represents a promising link between the geological and oceanographic communities.

  8. Tunable THz wave absorption by graphene-assisted plasmonic metasurfaces based on metallic split ring resonators

    International Nuclear Information System (INIS)

    Ahmadivand, Arash; Sinha, Raju; Karabiyik, Mustafa; Vabbina, Phani Kiran; Gerislioglu, Burak; Kaya, Serkan; Pala, Nezih

    2017-01-01

    Graphene plasmonics has been introduced as a novel platform to design various nano- and microstructures to function in a wide range of spectrum from optical to THz frequencies. Herein, we propose a tunable plasmonic metamaterial in the THz regime by using metallic (silver) concentric microscale split ring resonator arrays on a multilayer metasurface composed of silica and silicon layers. We obtained an absorption percentage of 47.9% including two strong Fano resonant dips in THz regime for the purely plasmonic metamaterial without graphene layer. Considering the data of an atomic graphene sheet (with the thickness of ~0.35 nm) in both analytical and experimental regimes obtained by prior works, we employed a graphene layer under concentric split ring resonator arrays and above the multilayer metasurface to enhance the absorption ratio in THz bandwidth. Our numerical and analytical results proved that the presence of a thin graphene layer enhances the absorption coefficient of MM to 64.35%, at the highest peak in absorption profile that corresponds to the Fano dip position. We also have shown that changing the intrinsic characteristics of graphene sheet leads to shifts in the position of Fano dips and variations in the absorption efficiency. The maximum percentage of absorption (~67%) was obtained for graphene-based MM with graphene layer with dissipative loss factor of 1477 Ω. Employing the antisymmetric feature of the split ring resonators, the proposed graphene-based metamaterial with strong polarization dependency is highly sensitive to the polarization angle of the incident THz beam.

  9. Impacts of wave-induced circulation in the surf zone on wave setup

    Science.gov (United States)

    Guérin, Thomas; Bertin, Xavier; Coulombier, Thibault; de Bakker, Anouk

    2018-03-01

    Wave setup corresponds to the increase in mean water level along the coast associated with the breaking of short-waves and is of key importance for coastal dynamics, as it contributes to storm surges and the generation of undertows. Although overall well explained by the divergence of the momentum flux associated with short waves in the surf zone, several studies reported substantial underestimations along the coastline. This paper investigates the impacts of the wave-induced circulation that takes place in the surf zone on wave setup, based on the analysis of 3D modelling results. A 3D phase-averaged modelling system using a vortex force formalism is applied to hindcast an unpublished field experiment, carried out at a dissipative beach under moderate to very energetic wave conditions (Hm 0 = 6m at breaking and Tp = 22s). When using an adaptive wave breaking parameterisation based on the beach slope, model predictions for water levels, short waves and undertows improved by about 30%, with errors reducing to 0.10 m, 0.10 m and 0.09 m/s, respectively. The analysis of model results suggests a very limited impact of the vertical circulation on wave setup at this dissipative beach. When extending this analysis to idealized simulations for different beach slopes ranging from 0.01 to 0.05, it shows that the contribution of the vertical circulation (horizontal and vertical advection and vertical viscosity terms) becomes more and more relevant as the beach slope increases. In contrast, for a given beach slope, the wave height at the breaking point has a limited impact on the relative contribution of the vertical circulation on the wave setup. For a slope of 0.05, the contribution of the terms associated with the vertical circulation accounts for up to 17% (i.e. a 20% increase) of the total setup at the shoreline, which provides a new explanation for the underestimations reported in previously published studies.

  10. Particle transport model sensitivity on wave-induced processes

    Science.gov (United States)

    Staneva, Joanna; Ricker, Marcel; Krüger, Oliver; Breivik, Oyvind; Stanev, Emil; Schrum, Corinna

    2017-04-01

    Different effects of wind waves on the hydrodynamics in the North Sea are investigated using a coupled wave (WAM) and circulation (NEMO) model system. The terms accounting for the wave-current interaction are: the Stokes-Coriolis force, the sea-state dependent momentum and energy flux. The role of the different Stokes drift parameterizations is investigated using a particle-drift model. Those particles can be considered as simple representations of either oil fractions, or fish larvae. In the ocean circulation models the momentum flux from the atmosphere, which is related to the wind speed, is passed directly to the ocean and this is controlled by the drag coefficient. However, in the real ocean, the waves play also the role of a reservoir for momentum and energy because different amounts of the momentum flux from the atmosphere is taken up by the waves. In the coupled model system the momentum transferred into the ocean model is estimated as the fraction of the total flux that goes directly to the currents plus the momentum lost from wave dissipation. Additionally, we demonstrate that the wave-induced Stokes-Coriolis force leads to a deflection of the current. During the extreme events the Stokes velocity is comparable in magnitude to the current velocity. The resulting wave-induced drift is crucial for the transport of particles in the upper ocean. The performed sensitivity analyses demonstrate that the model skill depends on the chosen processes. The results are validated using surface drifters, ADCP, HF radar data and other in-situ measurements in different regions of the North Sea with a focus on the coastal areas. The using of a coupled model system reveals that the newly introduced wave effects are important for the drift-model performance, especially during extremes. Those effects cannot be neglected by search and rescue, oil-spill, transport of biological material, or larva drift modelling.

  11. Iodine-induced stress corrosion cracking of fixed deflection stressed slotted rings of Zircaloy fuel cladding

    International Nuclear Information System (INIS)

    Sejnoha, R.; Wood, J.C.

    1978-01-01

    Stress corrosion cracking of Zircaloy fuel cladding by fission products is thought to be an important mechanism influencing power ramping defects of water-reactor fuels. We have used the fixed-deflection stressed slotted-ring technique to demonstrate cracking. The results show both the sensitivity and limitations of the stressed slotted-ring method in determining the responses of tubing to stress corrosion cracking. They are interpreted in terms of stress relaxation behavior, both on a microscopic scale for hydrogen-induced stress-relief and on a macroscopic scale for stress-time characteristics. Analysis also takes account of nonuniform plastic deformation during loading and residual stress buildup on unloading. 27 refs

  12. Plasmon-induced transparency in ring-bar meta-atom

    Directory of Open Access Journals (Sweden)

    Wan-Xia Huang

    2018-03-01

    Full Text Available We introduce an approach for constructing a scalable metamaterial structure, which is composed of a ring and a bar in a unit cell, and supports singular plasmon-induced transparency. The composite multilayered structure consists of coupled meta-atom with bright modes and dark modes interacting through the introduction of structural asymmetry, which involves the displacement of the bar from the center of the ring. The splitting and merging of the absorption peaks is observed with the change in asymmetric degree. In addition, coupled-mode theory with a two-mode and two-port model is introduced to explain the observed novel spectral feature. The results provide a reference for further application to optoelectronic devices.

  13. Plasmon-Induced Transparency Based on Triple Arc-Ring Resonators

    Directory of Open Access Journals (Sweden)

    Guang-Xi Dong

    2018-06-01

    Full Text Available This paper presents a plasmon-induced transparency (PIT using an easy-fabricating metamaterial composed of three pieces of metallic arc-rings on top of a dielectric substrate. The transmission of the transparent peak of 1.32 THz reaches approximately 93%. The utilization of the coupled Lorentzian oscillator model and the distribution of electromagnetic fields together explain the cause of the transparent peak. The simulation results further demonstrate that the bandwidth of the transmission peak can be narrowed by changing the sizes of the arc-rings. Moreover, an on/off effect based on the transparent peak is discussed by introducing photosensitive silicon into the air gaps of the suggested metamaterial structure.

  14. Nonlinear interaction of energetic ring current protons with magnetospheric hydromagnetic waves

    International Nuclear Information System (INIS)

    Chan, A.A.; Chen, L.; White, R.B.

    1989-01-01

    In order to study nonlinear wave-particle interactions in the Earth's magnetosphere we have derived Hamiltonian equations for the gyrophase-averaged nonrelativistic motion of charged particles in a perturbed dipole magnetic field. We assume low frequency (less than the proton gyrofrequency) fully electromagnetic perturbations, and we retain finite Larmor radius effects. Analytic and numerical results for the stochastic threshold of energetic protons (approx-gt 100 keV) in compressional geomagnetic pulsations in the Pc 5 range of frequencies 150--600 seconds are presented. These protons undergo a drift-bounce resonance with the Pc 5 waves which breaks the second (longitudinal) and third (flux) adiabatic invariants, while the first invariant (the magnetic moment) and the proton energy are approximately conserved. The proton motion in the observed spectrum of waves is found to be strongly diffusive, due to the overlap of neighboring primary resonances. copyright American Geophysical Union 1989

  15. Nonlinear interaction of energetic ring current protons with magnetospheric hydromagnetic waves

    International Nuclear Information System (INIS)

    Chan, A.A.; Chen, Liu; White, R.B.

    1989-09-01

    In order to study nonlinear wave-particle interactions in the earth's magnetosphere we have derived Hamiltonian equations for the gyrophase-averaged nonrealistic motion of charged particles in a perturbed dipole magnetic field. We assume low frequency (less than the proton gyrofrequency) fully electromagnetic perturbations, and we retain finite Larmor radius effects. Analytic and numerical results for the stochastic threshold of energetic protons (approx gt 100 keV) in compressional geomagnetic pulsations in the Pc 5 range of frequencies (150--600 seconds) are presented. These protons undergo a drift-bounce resonance with the Pc 5 waves which breaks the second (longitudinal) and third (flux) adiabatic invariants, while the first invariant (the magnetic moment) and the proton energy are approximately conserved. The proton motion in the observed spectrum of waves is found to be strongly diffusive, due to the overlap of neighboring primary resonances. 17 refs., 2 figs

  16. Control of quantum interference of an excitonic wave in a chlorophyll chain with a chlorophyll ring

    International Nuclear Information System (INIS)

    Hong, Suc-Kyoung; Nam, Seog-Woo; Yeon, Kyu-Hwang

    2010-01-01

    The quantum interference of an excitonic wave and its coherent control in a nanochain with a nanoring are studied. The nanochain is comprised of six chlorophylls, where four chlorophylls compose the nanoring and two chlorophylls are attached at two opposite sites on the nanoring. The exciton dynamics and the correlation of the excitation between chlorophylls are analyzed for a given configurational arrangement and dipolar orientation of the chlorophylls. The results of this study show that the excitation at specified chlorophylls is suppressed or enhanced by destructive or constructive interference of the excitonic wave in the chlorophyll nanochain.

  17. Cadmium toxicity to ringed seals (Phoca hispida): an epidemiological study of possible cadmium-induced nephropathy and osteodystrophy in ringed seals (Phoca hispida) from Qaanaaq in Northwest Greenland

    DEFF Research Database (Denmark)

    Sonne-Hansen, C; Dietz, R; Leifsson, P S

    2002-01-01

    The Greenland marine food chains contain high levels of cadmium, mercury and selenium. Concentrations of cadmium in the kidney of ringed seals (Phoca hispida) from the municipalities of Qaanaaq and Upernavik (Northwest Greenland) are among the highest recorded in the Arctic. The purpose of the st......The Greenland marine food chains contain high levels of cadmium, mercury and selenium. Concentrations of cadmium in the kidney of ringed seals (Phoca hispida) from the municipalities of Qaanaaq and Upernavik (Northwest Greenland) are among the highest recorded in the Arctic. The purpose...... of the study was to determine whether cadmium-induced damage in the kidneys and the skeletal system could be detected among 100 ringed seals from Northwest Greenland. The cadmium concentrations in the kidney cortex ranged from 0 to 248 microg/g wet weight (mean=44.5, N=100) in the 99 kidneys examined....... Experience from cadmium-poisoned humans and laboratory mammals indicates that concentrations above 50-200 microg/g wet wt. may induce histopathological changes. Overall, 31 of the ringed seals had cadmium concentrations in the kidney cortex above 50 microg/g wet wt., 11 had concentrations above 100 and one...

  18. Estimation of Impulsive Wave-induced Loads on a FPSO

    DEFF Research Database (Denmark)

    Jensen, Jørgen Juncher; Mansour, Alaa E.

    2005-01-01

    ) and for green water loads from the results of Buchner (1995) and Wang et al. (1998) are applied. The phase lag relative to the wave-induced peak and the decay rate are derived mainly from published experimental results, Sikora, (1998). The results are given in closed-form expressions and the required input...

  19. Electromagnetically induced transparency (EIT)-like transmission in side-coupled complementary split-ring resonators.

    Science.gov (United States)

    Guo, Yinghui; Yan, Lianshan; Pan, Wei; Luo, Bin; Wen, Kunhua; Guo, Zhen; Luo, Xiangang

    2012-10-22

    We investigate a plasmonic waveguide system based on side-coupled complementary split-ring resonators (CSRR), which exhibits electromagnetically induced transparency (EIT)-like transmission. LC resonance model is utilized to explain the electromagnetic responses of CSRR, which is verified by simulation results of finite difference time domain method. The electromagnetic responses of CSRR can be flexible handled by changing the asymmetry degree of the structure and the width of the metallic baffles. Cascaded CSRRs also have been studied to obtain EIT-like transmission at visible and near-infrared region, simultaneously.

  20. Development of a wave-induced forcing threshold for nearshore impact of Wave Energy Converter arrays

    Science.gov (United States)

    O'Dea, A.; Haller, M. C.; Ozkan-Haller, H. T.

    2016-02-01

    Wave-induced forcing is a function of spatial gradients in the wave radiation stresses and is the main driver of alongshore currents, rip currents, and nearshore sediment transport. The installation of nearshore Wave Energy Converter (WEC) arrays may cause significant changes in the surf zone radiation stresses and could therefore impact nearshore littoral processes. In the first part of this study, a new threshold for nearshore hydrodynamic impact due to the presence of WEC devices is established based on changes in the alongshore radiation stress gradients shoreward of WEC arrays. The threshold is defined based on the relationship between nearshore radiation stresses and alongshore currents as observed in field data. Next, we perform a parametric study of the nearshore impact of WEC arrays using the SWAN wave model. Trials are conducted on an idealized, alongshore-uniform beach with a range of WEC array configurations, locations, and incident wave conditions, and conditions that generate radiation stress gradients above the impact threshold are identified. Finally, the same methodology is applied to two wave energy test sites off the coast of Newport, OR with more complicated bathymetries. Although the trends at the field sites are similar to those seen in the parametric study, the location and extent of the changes in the alongshore radiation stress gradients appear to be heavily influenced by the local bathymetry.

  1. Shock wave induced sonoporation and gene transfer

    Science.gov (United States)

    Miller, Douglas L.

    2003-10-01

    During shockwave (SW) treatment, cavitation activity can be applied for cell killing. A bonus is that some surviving cells appear to be briefly permeabilized, or sonoporated, allowing them to take up large molecules including DNA. In vitro research has indicated that as the number of SW increased, survival declined exponentially but the number of sonoporated cells increased to better than 50% of survivors for 1000 SW. In vivo tests have demonstrated SW-induced tumor ablation could indeed be accompanied by the transfection of marker plasmids into mouse B16 melanoma tumors in vivo. With intratumor injection of plasmid DNA and air bubbles, significant results were obtained for only 400 SW. In a trial of cancer therapy, the effects of 500 SW combined with interleukin-12 immuno-gene therapy was observed on the progression of two mouse tumors, B16 melanoma and RENCA renal carcinoma. The combination of SW and IL-12 plasmid injection provided a statistically significant inhibition of tumor growth relative to SW alone for both tumor models, demonstrating feasibility for this treatment method. In the future, the development of intravenous gene delivery and improved transfection, together with image-guided ultrasound treatment, should lead to the clinical application of ultrasound enhanced gene therapy. [Work supported by NIH Grant No. EB002782.

  2. 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.

  3. Electronic confinement in graphene quantum rings due to substrate-induced mass radial kink.

    Science.gov (United States)

    Xavier, L J P; da Costa, D R; Chaves, A; Pereira, J M; Farias, G A

    2016-12-21

    We investigate localized states of a quantum ring confinement in monolayer graphene defined by a circular mass-related potential, which can be induced e.g. by interaction with a substrate that breaks the sublattice symmetry, where a circular line defect provides a change in the sign of the induced mass term along the radial direction. Electronic properties are calculated analytically within the Dirac-Weyl approximation in the presence of an external magnetic field. Analytical results are also compared with those obtained by the tight-binding approach. Regardless of its sign, a mass term [Formula: see text] is expected to open a gap for low-energy electrons in Dirac cones in graphene. Both approaches confirm the existence of confined states with energies inside the gap, even when the width of the kink modelling the mass sign transition is infinitely thin. We observe that such energy levels are inversely proportional to the defect line ring radius and independent on the mass kink height. An external magnetic field is demonstrated to lift the valley degeneracy in this system and easily tune the valley index of the ground state in this system, which can be polarized on either K or [Formula: see text] valleys of the Brillouin zone, depending on the magnetic field intensity. Geometrical changes in the defect line shape are considered by assuming an elliptic line with different eccentricities. Our results suggest that any defect line that is closed in a loop, with any geometry, would produce the same qualitative results as the circular ones, as a manifestation of the topologically protected nature of the ring-like states investigated here.

  4. Peroxynitrite-induced relaxation in isolated rat aortic rings and mechanisms of action

    International Nuclear Information System (INIS)

    Li Jianfeng; Li Wenyan; Altura, Bella T.; Altura, Burton M.

    2005-01-01

    The present study was designed to evaluate the effects of peroxynitrite (ONOO - ), the product of superoxide and nitric oxide, on isolated segments of rat aorta. In the absence of any vasoactive agent, ONOO - (from 10 -8 to 10 -4 M) failed to alter the basal tension. In phenylephrine (PE; 5 x 10 -7 M)-precontracted rat aortic rings (RAR), ONOO - elicited concentration-dependent relaxation at concentrations of from 10 -8 to 10 -4 M. The effective concentrations producing approximately 50% of maximal relaxation (ED 5 ) to ONOO - were 1.84 x 10 -5 M and 1.96 x 10 -5 M in intact and denuded RAR, respectively (P > 0.05). No significant differences in the relaxation responses were found between RAR with or without endothelium (P > 0.05). The presence of either 5 μM methylene blue (MB) or 5 μM 1H-[1,2,4]oxadiazolo-[4,3-α]quinoxalin-1-one (ODQ) significantly inhibited the relaxations induced by ONOO - . Sildenafil (10 -7 M), on the other hand, significantly potentiated the ONOO - -induced relaxations. Tetraethylammonium chloride (T-2265) significantly decreased the ONOO - -induced relaxations in a concentration-dependent manner. However, ONOO - had no effect on RAR precontracted by high KCL (40 mM, n = 6, P > 0.05). Addition of calyculin A also significantly decreased the ONOO - -induced relaxation in a dose-dependent manner. Furthermore, ONOO - significantly inhibited calcium-induced contractions of K + -depolarized aortic rings in a concentration-related manner. Lastly, a variety of other pharmacological agents and antagonists including L-NMMA, L-arginine, indomethacin, atropine, naloxone, diphenhydramine, cimetine, glibenclamide, haloperidol, superoxide dismutase (SOD), and catalase did not influence the relaxant effects of ONOO - on RAR. Our new results suggest that ONOO - -triggered relaxation on rat aortic rings is mediated by elevation of cGMP levels, membrane hyperpolarization via K + -channel activation, activation of myosin phosphatase activity, and

  5. Miniature Chemical Sensor Combining Molecular Recognition with Evanescent Wave Cavity Ring-Down Spectroscopy

    International Nuclear Information System (INIS)

    Pipino, Andrew C. R.; Meuse, Curtis W.

    2002-01-01

    To address the chemical sensing needs of DOE, a new class of chemical sensors is being developed that enables qualitative and quantitative, remote, real-time, optical diagnostics of chemical species in hazardous gas, liquid, and semi-solid phases by employing evanescent wave cavity ringdown spectroscopy (EW-CRDS). The sensitivity of EW-CRDS was demonstrated previously under Project No.60231. The objective of this project is to enhance the range of application and selectivity of the technique by combining EW-CRDS with refractive-index-sensitive nanoparticle optics, molecular recognition (MR) chemistry, and by utilizing the polarization-dependence of EW-CRDS. Research Progress and Implications

  6. On the Chemical Mixing Induced by Internal Gravity Waves

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, T. M. [School of Mathematics, Statistics and Physics, Newcastle University, Newcastle upon Tyne (United Kingdom); McElwaine, J. N. [Planetary Science Institute, Tucson, AZ 85721 (United States)

    2017-10-10

    Detailed modeling of stellar evolution requires a better understanding of the (magneto)hydrodynamic processes that mix chemical elements and transport angular momentum. Understanding these processes is crucial if we are to accurately interpret observations of chemical abundance anomalies, surface rotation measurements, and asteroseismic data. Here, we use two-dimensional hydrodynamic simulations of the generation and propagation of internal gravity waves in an intermediate-mass star to measure the chemical mixing induced by these waves. We show that such mixing can generally be treated as a diffusive process. We then show that the local diffusion coefficient does not depend on the local fluid velocity, but rather on the wave amplitude. We then use these findings to provide a simple parameterization for this diffusion, which can be incorporated into stellar evolution codes and tested against observations.

  7. A parametric investigation on the cyclotron maser instability driven by ring-beam electrons with intrinsic Alfvén waves

    Science.gov (United States)

    Tong, Zi-Jin; Wang, Chuan-Bing; Zhang, Pei-Jin; Liu, Jin

    2017-05-01

    The electron-cyclotron maser is a process that generates the intense and coherent radio emission in the plasma. In this paper, we present a comprehensive parametric investigation on the electron-cyclotron-maser instability driven by non-thermal ring-beam electrons with intrinsic Alfvén waves, which pervade the solar atmosphere and interplanetary space. It is found that both forward propagating and backward propagating waves can be excited in the fast ordinary (O) and extraordinary (X) electromagnetic modes. The growth rates of X1 mode are almost always weakened by Alfvén waves. The average pitch-angle ϕ 0 of electrons is a key parameter for the effect of Alfvén waves on the growth rate of modes O1, O2, and X2. For a beam-dominated electron distribution ( ϕ 0 ≲ 30 ° ), the growth rates of the maser instability for O1, O2, and X2 modes are enhanced with the increase of the Alfvén wave energy density. In other conditions, the growth rates of O1, O2, and X2 modes weakened with the increasing Alfvén wave intensity, except that the growth of the O1 mode may also be enhanced by Alfvén waves for a ring distribution. The results may be important for us in analyzing the mechanism of radio bursts with various fine structures observed in space and astrophysical plasmas.

  8. Photo-induced travelling waves in condensed Langmuir monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Tabe, Y [Yokoyama Nano-Structured Liquid Crystal Project, ERATO, Japan Science and Technology Corporation, 5-9-9 Tokodai, Tsukuba, Ibaraki 300-2635, Japan (Japan); Yamamoto, T [Yokoyama Nano-Structured Liquid Crystal Project, ERATO, Japan Science and Technology Corporation, 5-9-9 Tokodai, Tsukuba, Ibaraki 300-2635, Japan (Japan); Yokoyama, H [Yokoyama Nano-Structured Liquid Crystal Project, ERATO, Japan Science and Technology Corporation, 5-9-9 Tokodai, Tsukuba, Ibaraki 300-2635, Japan (Japan)

    2003-06-01

    We report the detailed properties of photo-induced travelling waves in liquid crystalline Langmuir monolayers composed of azobenzene derivatives. When the monolayer, in which the constituent rodlike molecules are coherently tilted from the layer normal, is weakly illuminated to undergo the trans-cis photo-isomerization, spatio-temporal periodic oscillations of the molecular azimuth begin over the entire excited area and propagate as a two-dimensional orientational wave. The wave formation takes place only when the film is formed at an asymmetric interface with broken up-down symmetry and when the chromophores are continuously excited near the long-wavelength edge of absorption to induce repeated photo-isomerizations between the trans and cis forms. Under proper illumination conditions, Langmuir monolayers composed of a wide variety of azobenzene derivatives have been confirmed to exhibit similar travelling waves with velocity proportional to the excitation power irrespective of the degree of amphiphilicity. The dynamics can be qualitatively explained by the modified reaction-diffusion model proposed by Reigada, Sagues and Mikhailov.

  9. Neutrino induced vorticity, Alfven waves and the normal modes

    Energy Technology Data Exchange (ETDEWEB)

    Bhatt, Jitesh R. [Theory Division, Physical Research Laboratory, Ahmedabad (India); George, Manu [Theory Division, Physical Research Laboratory, Ahmedabad (India); Indian Institute of Technology, Department of Physics, Ahmedabad (India)

    2017-08-15

    We consider a plasma consisting of electrons and ions in the presence of a background neutrino gas and develop the magnetohydrodynamic equations for the system. We show that the electron neutrino interaction can induce vorticity in the plasma even in the absence of any electromagnetic perturbations if the background neutrino density is left-right asymmetric. This induced vorticity supports a new kind of Alfven wave whose velocity depends on both the external magnetic field and on the neutrino asymmetry. The normal mode analysis show that in the presence of neutrino background the Alfven waves can have different velocities. We also discuss our results in the context of dense astrophysical plasma such as magnetars and show that the difference in the Alfven velocities can be used to explain the observed pulsar kick. We discuss also the relativistic generalisation of the electron fluid in presence of an asymmetric neutrino background. (orig.)

  10. Planetary Rings

    Science.gov (United States)

    Nicholson, P. D.

    2001-11-01

    A revolution in the studies in planetary rings studies occurred in the period 1977--1981, with the serendipitous discovery of the narrow, dark rings of Uranus, the first Voyager images of the tenuous jovian ring system, and the many spectacular images returned during the twin Voyager flybys of Saturn. In subsequent years, ground-based stellar occultations, HST observations, and the Voyager flybys of Uranus (1986) and Neptune (1989), as well as a handful of Galileo images, provided much additional information. Along with the completely unsuspected wealth of detail these observations revealed came an unwelcome problem: are the rings ancient or are we privileged to live at a special time in history? The answer to this still-vexing question may lie in the complex gravitational interactions recent studies have revealed between the rings and their retinues of attendant satellites. Among the four known ring systems, we see elegant examples of Lindblad and corotation resonances (first invoked in the context of galactic disks), electromagnetic resonances, spiral density waves and bending waves, narrow ringlets which exhibit internal modes due to collective instabilities, sharp-edged gaps maintained via tidal torques from embedded moonlets, and tenuous dust belts created by meteoroid impact onto parent bodies. Perhaps most puzzling is Saturn's multi-stranded, clumpy F ring, which continues to defy a simple explanation 20 years after it was first glimpsed in grainy images taken by Pioneer 11. Voyager and HST images reveal a complex, probably chaotic, dynamical interaction between unseen parent bodies within this ring and its two shepherd satellites, Pandora and Prometheus. The work described here reflects contributions by Joe Burns, Jeff Cuzzi, Luke Dones, Dick French, Peter Goldreich, Colleen McGhee, Carolyn Porco, Mark Showalter, and Bruno Sicardy, as well as those of the author. This research has been supported by NASA's Planetary Geology and Geophysics program and the

  11. Patterns of patterns of synchronization: Noise induced attractor switching in rings of coupled nonlinear oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Emenheiser, Jeffrey [Complexity Sciences Center, University of California, Davis, California 95616 (United States); Department of Physics, University of California, Davis, California 95616 (United States); Chapman, Airlie; Mesbahi, Mehran [William E. Boeing Department of Aeronautics and Astronautics, University of Washington, Seattle, Washington 98195 (United States); Pósfai, Márton [Complexity Sciences Center, University of California, Davis, California 95616 (United States); Department of Computer Science, University of California, Davis, California 95616 (United States); Crutchfield, James P. [Complexity Sciences Center, University of California, Davis, California 95616 (United States); Department of Physics, University of California, Davis, California 95616 (United States); Department of Computer Science, University of California, Davis, California 95616 (United States); Santa Fe Institute, Santa Fe, New Mexico 87501 (United States); D' Souza, Raissa M. [Complexity Sciences Center, University of California, Davis, California 95616 (United States); Department of Computer Science, University of California, Davis, California 95616 (United States); Santa Fe Institute, Santa Fe, New Mexico 87501 (United States); Department of Mechanical and Aerospace Engineering, University of California, Davis, California 95616 (United States)

    2016-09-15

    Following the long-lived qualitative-dynamics tradition of explaining behavior in complex systems via the architecture of their attractors and basins, we investigate the patterns of switching between distinct trajectories in a network of synchronized oscillators. Our system, consisting of nonlinear amplitude-phase oscillators arranged in a ring topology with reactive nearest-neighbor coupling, is simple and connects directly to experimental realizations. We seek to understand how the multiple stable synchronized states connect to each other in state space by applying Gaussian white noise to each of the oscillators' phases. To do this, we first analytically identify a set of locally stable limit cycles at any given coupling strength. For each of these attracting states, we analyze the effect of weak noise via the covariance matrix of deviations around those attractors. We then explore the noise-induced attractor switching behavior via numerical investigations. For a ring of three oscillators, we find that an attractor-switching event is always accompanied by the crossing of two adjacent oscillators' phases. For larger numbers of oscillators, we find that the distribution of times required to stochastically leave a given state falls off exponentially, and we build an attractor switching network out of the destination states as a coarse-grained description of the high-dimensional attractor-basin architecture.

  12. Imprint of the merger and ring-down on the gravitational wave background from black hole binaries coalescence

    Science.gov (United States)

    Marassi, S.; Schneider, R.; Corvino, G.; Ferrari, V.; Portegies Zwart, S.

    2011-12-01

    We compute the gravitational wave background (GWB) generated by a cosmological population of black hole-black hole (BH-BH) binaries using hybrid waveforms recently produced by numerical simulations of (BH-BH) coalescence, which include the inspiral, merger, and ring-down contributions. A large sample of binary systems is simulated using the population synthesis code SeBa, and we extract fundamental statistical information on (BH-BH) physical parameters (primary and secondary BH masses, orbital separations and eccentricities, formation, and merger time scales). We then derive the binary birth and merger rates using the theoretical cosmic star formation history obtained from a numerical study which reproduces the available observational data at redshifts zrate of 0.85Mpc-3Myr-1. Third generation detectors, such as the Einstein Telescope (ET), could reveal the GWB from the inspiral phase predicted by any of the considered models. In addition, ET could sample the merger phase of the evolution at least for models which predict local merger rates between [0.053-0.85]Mpc-3Myr-1, which are more than a factor 2 lower than the upper limit inferred from the analysis of the LIGO S5 run [J. Abadie , Phys. Rev. DPRVDAQ1550-7998 83, 122005 (2011)10.1103/PhysRevD.83.122005]. The frequency dependence and amplitude of the GWB generated during the coalescence is very sensitive to the adopted core mass threshold for BH formation. This opens up the possibility to better understand the final stages of the evolution of massive stellar binaries using observational constraints on the associated gravitational wave emission.

  13. Electronic transitions in quantum dots and rings induced by inhomogeneous off-centered light beams.

    Science.gov (United States)

    Quinteiro, G F; Lucero, A O; Tamborenea, P I

    2010-12-22

    We theoretically investigate the effect of inhomogeneous light beams with (twisted light) and without (plane-wave light) orbital angular momentum on semiconductor-based nanostructures, when the symmetry axes of the beam and the nanostructure are displaced parallel to each other. Exact analytical results are obtained by expanding the off-centered light field in terms of the appropriate light modes centered around the nanostructure. We demonstrate how electronic transitions involving the transfer of different amounts of orbital angular momentum are switched on and off as a function of the separation between the axes of the beam and the system. In particular, we show that even off-centered plane-wave beams induce transitions such that the angular momenta of the initial and final states are different.

  14. Analogy of electromagnetically induced transparency in plasmonic nanodisk with a square ring resonator

    International Nuclear Information System (INIS)

    Li, Xianping; Wei, Zhongchao; Liu, Yuebo; Zhong, Nianfa; Tan, Xiaopei; Shi, Songsong; Liu, Hongzhan; Liang, Ruisheng

    2016-01-01

    We have demonstrated the analogy of electromagnetically induced transparency in plasmonic nanodisk with a square ring resonator. A reasonable analysis of the transmission feature based on the temporal coupled-mode theory is given and shows good agreement with the Finit-Difference Time-Domain simulation. The transparency window can be easily tuned by changing the geometrical parameters and the insulator filled in the resonator. The transmission of the resonator system is close to 80% and the full width at half maximum is less than 46 nm. The sensitivity of the structure is about 812 nm/RIU. These characteristics make the new system with potential to apply for optical storage, ultrafast plasmonic switch and slow-light devices.

  15. Analogy of electromagnetically induced transparency in plasmonic nanodisk with a square ring resonator

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xianping; Wei, Zhongchao, E-mail: wzc@scnu.edu.cn; Liu, Yuebo; Zhong, Nianfa; Tan, Xiaopei; Shi, Songsong; Liu, Hongzhan; Liang, Ruisheng

    2016-01-08

    We have demonstrated the analogy of electromagnetically induced transparency in plasmonic nanodisk with a square ring resonator. A reasonable analysis of the transmission feature based on the temporal coupled-mode theory is given and shows good agreement with the Finit-Difference Time-Domain simulation. The transparency window can be easily tuned by changing the geometrical parameters and the insulator filled in the resonator. The transmission of the resonator system is close to 80% and the full width at half maximum is less than 46 nm. The sensitivity of the structure is about 812 nm/RIU. These characteristics make the new system with potential to apply for optical storage, ultrafast plasmonic switch and slow-light devices.

  16. Evanescent wave cavity ring-down spectroscopy (EW-CRDS) as a probe of macromolecule adsorption kinetics at functionalized interfaces.

    Science.gov (United States)

    O'Connell, Michael A; de Cuendias, Anne; Gayet, Florence; Shirley, Ian M; Mackenzie, Stuart R; Haddleton, David M; Unwin, Patrick R

    2012-05-01

    Evanescent wave cavity ring-down spectroscopy (EW-CRDS) has been employed to study the interfacial adsorption kinetics of coumarin-tagged macromolecules onto a range of functionalized planar surfaces. Such studies are valuable in designing polymers for complex systems where the degree of interaction between the polymer and surface needs to be tailored. Three tagged synthetic polymers with different functionalities are examined: poly(acrylic acid) (PAA), poly(3-sulfopropyl methacrylate, potassium salt) (PSPMA), and a mannose-modified glycopolymer. Adsorption transients at the silica/water interface are found to be characteristic for each polymer, and kinetics are deduced from the initial rates. The chemistry of the adsorption interfaces has been varied by, first, manipulation of silica surface chemistry via the bulk pH, followed by surfaces modified by poly(L-glutamic acid) (PGA) and cellulose, giving five chemically different surfaces. Complementary atomic force microscopy (AFM) imaging has been used for additional surface characterization of adsorbed layers and functionalized interfaces to allow adsorption rates to be interpreted more fully. Adsorption rates for PSPMA and the glycopolymer are seen to be highly surface sensitive, with significantly higher rates on cellulose-modified surfaces, whereas PAA shows a much smaller rate dependence on the nature of the adsorption surface.

  17. Analysis of Wave Fields induced by Offshore Pile Driving

    Science.gov (United States)

    Ruhnau, M.; Heitmann, K.; Lippert, T.; Lippert, S.; von Estorff, O.

    2015-12-01

    Impact pile driving is the common technique to install foundations for offshore wind turbines. With each hammer strike the steel pile - often exceeding 6 m in diameter and 80 m in length - radiates energy into the surrounding water and soil, until reaching its targeted penetration depth. Several European authorities introduced limitations regarding hydroacoustic emissions during the construction process to protect marine wildlife. Satisfying these regulations made the development and application of sound mitigation systems (e.g. bubble curtains or insulation screens) inevitable, which are commonly installed within the water column surrounding the pile or even the complete construction site. Last years' advances have led to a point, where the seismic energy tunneling the sound mitigation systems through the soil and radiating back towards the water column gains importance, as it confines the maximum achievable sound mitigation. From an engineering point of view, the challenge of deciding on an effective noise mitigation layout arises, which especially requires a good understanding of the soil-dependent wave field. From a geophysical point of view, the pile acts like a very unique line source, generating a characteristic wave field dominated by inclined wave fronts, diving as well as head waves. Monitoring the seismic arrivals while the pile penetration steadily increases enables to perform quasi-vertical seismic profiling. This work is based on datasets that have been collected within the frame of three comprehensive offshore measurement campaigns during pile driving and demonstrates the potential of seismic arrivals induced by pile driving for further soil characterization.

  18. Theory of ion Bernstein wave induced shear suppression of turbulence

    Science.gov (United States)

    Craddock, G. G.; Diamond, P. H.; Ono, M.; Biglari, H.

    1994-06-01

    The theory of radio frequency induced ion Bernstein wave- (IBW) driven shear flow in the edge is examined, with the goal of application of shear suppression of fluctuations. This work is motivated by the observed confinement improvement on IBW heated tokamaks [Phys. Fluids B 5, 241 (1993)], and by previous low-frequency work on RF-driven shear flows [Phys. Rev. Lett. 67, 1535 (1991)]. It is found that the poloidal shear flow is driven electrostatically by both Reynolds stress and a direct ion momentum source, analogous to the concepts of helicity injection and electron momentum input in current drive, respectively. Flow drive by the former does not necessarily require momentum input to the plasma to induce a shear flow. For IBW, the direct ion momentum can be represented by direct electron momentum input, and a charge separation induced stress that imparts little momentum to the plasma. The derived Er profile due to IBW predominantly points inward, with little possibility of direction change, unlike low-frequency Alfvénic RF drive. The profile scale is set by the edge density gradient and electron dissipation. Due to the electrostatic nature of ion Bernstein waves, the poloidal flow contribution dominates in Er. Finally, the necessary edge power absorbed for shear suppression on Princeton Beta Experiment-Modified (PBX-M) [9th Topical Conference on Radio Frequency Power in Plasmas, Charleston, SC, 1991 (American Institute of Physics, New York, 1991), p. 129] is estimated to be 100 kW distributed over 5 cm.

  19. Variations of helicon wave induced radial plasma transport in different experimental conditions

    International Nuclear Information System (INIS)

    Petrzilka, V.

    1993-08-01

    Variations of the helicon wave induced radial plasma transport are presented in dependence on values of the plasma radius, magnetostatic field, plasma density, frequency of the helicon wave and on the ion charge. 22 refs., 14 figs

  20. Patterns induced by magnetic impurities in d-wave superconductors

    International Nuclear Information System (INIS)

    Zuo Xianjun; Gong Changde; Zhou Yuan

    2010-01-01

    We investigate the modulated patterns induced by magnetic impurities in d-wave superconductors (DSCs) near optimal doping based on the t-t ' -U-V model. Modulated checkerboard patterns with periodicity of eight or four lattice constants (8a or 4a) in the spin-, charge- and DSC orders are observed. Moreover, the checkerboard modulation in the spin order appear to be robust against parameter changes, which is consistent with neutron-scattering experiments. For the two-impurity case, a modulated stripe-like spin order with periodicity 8a is induced, which coexists with the DSC order. Further experiments of magnetic impurity substitution in DSCs are expected to check these results.

  1. Patterns induced by magnetic impurities in d-wave superconductors

    Science.gov (United States)

    Zuo, Xian-Jun; Gong, Chang-De; Zhou, Yuan

    2010-07-01

    We investigate the modulated patterns induced by magnetic impurities in d-wave superconductors (DSCs) near optimal doping based on the t-t-U-V model. Modulated checkerboard patterns with periodicity of eight or four lattice constants (8 a or 4 a) in the spin-, charge- and DSC orders are observed. Moreover, the checkerboard modulation in the spin order appear to be robust against parameter changes, which is consistent with neutron-scattering experiments. For the two-impurity case, a modulated stripe-like spin order with periodicity 8 a is induced, which coexists with the DSC order. Further experiments of magnetic impurity substitution in DSCs are expected to check these results.

  2. Wave aberrations in rhesus monkeys with vision-induced ametropias

    Science.gov (United States)

    Ramamirtham, Ramkumar; Kee, Chea-su; Hung, Li-Fang; Qiao-Grider, Ying; Huang, Juan; Roorda, Austin; Smith, Earl L.

    2007-01-01

    The purpose of this study was to investigate the relationship between refractive errors and high-order aberrations in infant rhesus monkeys. Specifically, we compared the monochromatic wave aberrations measured with a Shack-Hartman wavefront sensor between normal monkeys and monkeys with vision-induced refractive errors. Shortly after birth, both normal monkeys and treated monkeys reared with optically induced defocus or form deprivation showed a decrease in the magnitude of high-order aberrations with age. However, the decrease in aberrations was typically smaller in the treated animals. Thus, at the end of the lens-rearing period, higher than normal amounts of aberrations were observed in treated eyes, both hyperopic and myopic eyes and treated eyes that developed astigmatism, but not spherical ametropias. The total RMS wavefront error increased with the degree of spherical refractive error, but was not correlated with the degree of astigmatism. Both myopic and hyperopic treated eyes showed elevated amounts of coma and trefoil and the degree of trefoil increased with the degree of spherical ametropia. Myopic eyes also exhibited a much higher prevalence of positive spherical aberration than normal or treated hyperopic eyes. Following the onset of unrestricted vision, the amount of high-order aberrations decreased in the treated monkeys that also recovered from the experimentally induced refractive errors. Our results demonstrate that high-order aberrations are influenced by visual experience in young primates and that the increase in high-order aberrations in our treated monkeys appears to be an optical byproduct of the vision-induced alterations in ocular growth that underlie changes in refractive error. The results from our study suggest that the higher amounts of wave aberrations observed in ametropic humans are likely to be a consequence, rather than a cause, of abnormal refractive development. PMID:17825347

  3. Wave-induced stress and breaking of sea ice in a coupled hydrodynamic discrete-element wave-ice model

    Science.gov (United States)

    Herman, Agnieszka

    2017-11-01

    In this paper, a coupled sea ice-wave model is developed and used to analyze wave-induced stress and breaking in sea ice for a range of wave and ice conditions. The sea ice module is a discrete-element bonded-particle model, in which ice is represented as cuboid grains floating on the water surface that can be connected to their neighbors by elastic joints. The joints may break if instantaneous stresses acting on them exceed their strength. The wave module is based on an open-source version of the Non-Hydrostatic WAVE model (NHWAVE). The two modules are coupled with proper boundary conditions for pressure and velocity, exchanged at every wave model time step. In the present version, the model operates in two dimensions (one vertical and one horizontal) and is suitable for simulating compact ice in which heave and pitch motion dominates over surge. In a series of simulations with varying sea ice properties and incoming wavelength it is shown that wave-induced stress reaches maximum values at a certain distance from the ice edge. The value of maximum stress depends on both ice properties and characteristics of incoming waves, but, crucially for ice breaking, the location at which the maximum occurs does not change with the incoming wavelength. Consequently, both regular and random (Jonswap spectrum) waves break the ice into floes with almost identical sizes. The width of the zone of broken ice depends on ice strength and wave attenuation rates in the ice.

  4. Particle dispersion and mixing induced by breaking internal gravity waves

    Science.gov (United States)

    Bouruet-Aubertot, Pascale; Koudella, C.; Staquet, C.; Winters, K. B.

    2001-01-01

    The purpose of this paper is to analyze diapycnal mixing induced by the breaking of an internal gravity wave — the primary wave — either standing or propagating. To achieve this aim we apply two different methods. The first method consists of a direct estimate of vertical eddy diffusion from particle dispersion while the second method relies upon potential energy budgets [Winters, K.B., Lombard, P.N., Riley, J.J., D'Asaro, E.A., 1995. J. Fluid Mech. 289, 115-128; Winters, K.B., D'Asaro, E.A., 1996. J. Fluid Mech. 317, 179-193]. The primary wave we consider is of small amplitude and is statically stable, a case for which the breaking process involves two-dimensional instabilities. The dynamics of the waves have been previously analyzed by means of two-dimensional direct numerical simulations [Bouruet-Aubertot, P., Sommeria, J., Staquet, C., 1995. J. Fluid Mech. 285, 265-301; Bouruet-Aubertot, P., Sommeria, J., Staquet, C., 1996. Dyn. Atmos. Oceans 29, 41-63; Koudella, C., Staquet, C., 1998. In: Davis, P. (Ed.), Proceedings of the IMA Conference on Mixing and Dispersion on Stably-stratified Flows, Dundee, September 1996. IMA Publication]. High resolution three-dimensional calculations of the same wave are also reported here [Koudella, C., 1999]. A local estimate of mixing is first inferred from the time evolution of sets of particles released in the flow during the breaking regime. We show that, after an early evolution dominated by shear effects, a diffusion law is reached and the dispersion coefficient is fairly independent of the initial seeding location of the particles in the flow. The eddy diffusion coefficient, K, is then estimated from the diapycnal diffusive flux. A good agreement with the value inferred from particle dispersion is obtained. This finding is of particular interest regarding the interpretation of in situ estimates of K inferred either from tracer dispersion or from microstructure measurements. Computation of the Cox number, equal to the

  5. Feeding cells induced by phytoparasitic nematodes require γ-tubulin ring complex for microtubule reorganization.

    Directory of Open Access Journals (Sweden)

    Mohamed Youssef Banora

    2011-12-01

    Full Text Available Reorganization of the microtubule network is important for the fast isodiametric expansion of giant-feeding cells induced by root-knot nematodes. The efficiency of microtubule reorganization depends on the nucleation of new microtubules, their elongation rate and activity of microtubule severing factors. New microtubules in plants are nucleated by cytoplasmic or microtubule-bound γ-tubulin ring complexes. Here we investigate the requirement of γ-tubulin complexes for giant feeding cells development using the interaction between Arabidopsis and Meloidogyne spp. as a model system. Immunocytochemical analyses demonstrate that γ-tubulin localizes to both cortical cytoplasm and mitotic microtubule arrays of the giant cells where it can associate with microtubules. The transcripts of two Arabidopsis γ-tubulin (TUBG1 and TUBG2 and two γ-tubulin complex proteins genes (GCP3 and GCP4 are upregulated in galls. Electron microscopy demonstrates association of GCP3 and γ-tubulin as part of a complex in the cytoplasm of giant cells. Knockout of either or both γ-tubulin genes results in the gene dose-dependent alteration of the morphology of feeding site and failure of nematode life cycle completion. We conclude that the γ-tubulin complex is essential for the control of microtubular network remodelling in the course of initiation and development of giant-feeding cells, and for the successful reproduction of nematodes in their plant hosts.

  6. Dynamic Behavior of Fault Slip Induced by Stress Waves

    Directory of Open Access Journals (Sweden)

    Guang-an Zhu

    2016-01-01

    Full Text Available Fault slip burst is a serious dynamic hazard in coal mining. A static and dynamic analysis for fault slip was performed to assess the risk of rock burst. A numerical model FLAC3D was established to understand the stress state and mechanical responses of fault rock system. The results obtained from the analysis show that the dynamic behavior of fault slip induced by stress waves is significantly affected by mining depth, as well as dynamic disturbance intensity and the distance between the stope and the fault. The isolation effect of the fault is also discussed based on the numerical results with the fault angle appearing to have the strongest influence on peak vertical stress and velocity induced by dynamic disturbance. By taking these risks into account, a stress-relief technology using break-tip blast was used for fault slip burst control. This technique is able to reduce the stress concentration and increase the attenuation of dynamic load by fracturing the structure of coal and rock. The adoption of this stress-relief method leads to an effective reduction of fault slip induced rock burst (FSIRB occurrence.

  7. Intraluminal bubble dynamics induced by lithotripsy shock wave

    Science.gov (United States)

    Song, Jie; Bai, Jiaming; Zhou, Yufeng

    2016-12-01

    Extracorporeal shock wave lithotripsy (ESWL) has been the first option in the treatment of calculi in the upper urinary tract since its introduction. ESWL-induced renal injury is also found after treatment and is assumed to associate with intraluminal bubble dynamics. To further understand the interaction of bubble expansion and collapse with the vessel wall, the finite element method (FEM) was used to simulate intraluminal bubble dynamics and calculate the distribution of stress in the vessel wall and surrounding soft tissue during cavitation. The effects of peak pressure, vessel size, and stiffness of soft tissue were investigated. Significant dilation on the vessel wall occurs after contacting with rapid and large bubble expansion, and then vessel deformation propagates in the axial direction. During bubble collapse, large shear stress is found to be applied to the vessel wall at a clinical lithotripter setting (i.e. 40 MPa peak pressure), which may be the mechanism of ESWL-induced vessel rupture. The decrease of vessel size and viscosity of soft tissue would enhance vessel deformation and, consequently, increase the generated shear stress and normal stresses. Meanwhile, a significantly asymmetric bubble boundary is also found due to faster axial bubble expansion and shrinkage than in radial direction, and deformation of the vessel wall may result in the formation of microjets in the axial direction. Therefore, this numerical work would illustrate the mechanism of ESWL-induced tissue injury in order to develop appropriate counteractive strategies for reduced adverse effects.

  8. Wave-induced stresses and pore pressures near a mudline

    Directory of Open Access Journals (Sweden)

    Andrzej Sawicki

    2008-12-01

    Full Text Available Conventional methods for the determination of water-wave induced stresses inseabeds composed of granular soils are based on Biot-type models, in which the soilskeleton is treated as an elastic medium. Such methods predict effective stressesin the soil that are unacceptable from the physical point of view, as they permittensile stresses to occur near the upper surface of the seabed. Therefore, in thispaper the granular soil is assumed to behave as an elastic-ideally plastic material,with the Coulomb-Mohr yield criterion adopted to bound admissible stress states inthe seabed. The governing equations are solved numerically by a~finite differencemethod. The results of simulations, carried out for the case of time-harmonicwater waves, illustrate the depth distributions of the excess pore pressures and theeffective stresses in the seabed, and show the shapes of zones of soil in the plastic state.~In particular, the effects on the seabed behaviour of suchparameters as the degree of pore water saturation, the soil permeability, and theearth pressure coefficient, are illustrated.

  9. Renal tissue damage induced by focused shock waves

    Science.gov (United States)

    Ioritani, N.; Kuwahara, M.; Kambe, K.; Taguchi, K.; Saitoh, T.; Shirai, S.; Orikasa, S.; Takayama, K.; Lush, P. A.

    1990-07-01

    Biological evidence of renal arterial wall damage induced by the microjet due to shock wave-cavitation bubble interaction was demonstrated in living dog kidneys. We also intended to clarify the mechanism of renal tissue damage and the effects of different conditions of shock wave exposure (peak pressure of focused area, number of shots, exposure rate) on the renal tissue damage in comparison to stone disintegration. Disruption of arterial wall was the most remarkable histological change in the focused area of the kidneys. This lesion appeared as if the wall had been punctured by a needle. Large hematoma formation in the renal parenchym, and interstitial hemorrhage seemed to be the results of the arterial lesion. This arterial disorder also led to ischemic necrosis of the tubules surrounding the hematoma. Micro-angiographic examination of extracted kidneys also proved such arterial puncture lesions and ischemic lesions. The number of shots required for model stone disintegration was not inversely proportional to peak pressure. It decreased markedly when peak pressure was above 700 bar. Similarly thenumber of shots for hematoma formation was not inversely proportional to peak pressure, however, this decreased markedly above 500 bar. These results suggested that a hematoma could be formed under a lower peak pressure than that required for stone disintegration.

  10. Wave induced extreme hull girder loads on containerships

    DEFF Research Database (Denmark)

    Jensen, Jørgen Juncher; Pedersen, Preben Terndrup; Shi, Bill

    2009-01-01

    This paper provides simple but rational procedures for prediction of extreme waveinduced sectional hull girder forces with reasonable engineering accuracy. The procedures take into account main ship hull characteristics such as: length, breadth, draught, block coefficient, bow flare coefficient......, forward speed and hull flexibility. The vertical hull girder loads are evaluated for specific operational profiles. Firstly a quadratic strip theory is presented which can give separate predictions for the hogging and sagging bending moments and shear forces and for hull girder loads. Then this procedure...... is based on rational methods it can be applied for novel single hull ship types not presently covered by the rules of the classification societies or to account for specific operational profiles....

  11. Shock-induced borehole waves and fracture effects

    NARCIS (Netherlands)

    Fan, H.; Smeulders, D.M.J.

    2012-01-01

    We perform wave experiments using a vertical shock tube setup. Shock waves are generated by the rupture of a thin membrane. In the test section the incident pressure waves generate borehole-guided waves along water-saturated samples. The tube is equipped with side wall gages and a mobile pressure

  12. Modelling and simulation of a thermally induced optical transparency in a dual micro-ring resonator.

    Science.gov (United States)

    Lydiate, Joseph

    2017-07-01

    This paper introduces the simulation and modelling of a novel dual micro-ring resonator. The geometric configuration of the resonators, and the implementation of a simulated broadband excitation source, results in the realization of optical transparencies in the combined through port output spectrum. The 130 nm silicon on insulator rib fabrication process is adopted for the simulation of the dual-ring configuration. Two titanium nitride heaters are positioned over the coupling regions of the resonators, which can be operated independently, to control the spectral position of the optical transparency. A third heater, centrally located above the dual resonator rings, can be used to red shift the entire spectrum to a required reference resonant wavelength. The free spectral range with no heater currents applied is 4.29 nm. For a simulated heater current of 7 mA (55.7 mW heater power) applied to one of the through coupling heaters, the optical transparency exhibits a red shift of 1.79 nm from the reference resonant wavelength. The ring-to-ring separation of approximately 900 nm means that it can be assumed that there is a zero ring-to-ring coupling field in this model. This novel arrangement has potential applications as a gas mass airflow sensor or a gas species identification sensor.

  13. On propagating direction of ring current proton ULF waves observed by ATS 6 at 6.6 R/sub e/

    International Nuclear Information System (INIS)

    Su, S.; Konradi, A.; Fritz, T.A.

    1977-01-01

    From June 11 to September 16, 1974, the NOAA low-energy proton detector on board the ATS 6 satellite observed 71 cases of ultralow-frequency oscillations of proton flux intensities. The oscillation periods varied from 40 s to 6 min, and the events were observed most frequently during moderate geomagnetic conditions. The flux oscillations occurred at various local times, yet almost two thirds of the events were detected in the near-dusk region of the magentosphere. For a majority of the events in this set a substantial phase shift in flux oscillation was detected between different energy channels and/or between two oppositely oriented detector telescopes. The phase shift is mainly due to the finite gyroradius effect of the protons gyrating in the geomagnetic field. By examining this finite gyroradius effect on the perturbed particle distribution function associated with the wave in a nonuniform magnetic field we are able to determine the propagation direction of the wave from particle observations made by a single spacecraft. Although the type of wave and its excitation mechanism can only be conjectured at the present time, it is concluded that the wave propagates in the westward direction with a phase velocity of about 13 km/s. Furthermore, it also has a very small phase velocity approx.0.15 km/s propagating toward the earth. If the wave had been traveling 1 hour or so before it was observed near the dusk magnetosphere, it might have originated in the dark magnetosphere in associating with some changes in geophysical conditions. The statistical correlation between the times of the observed wave events and the onsets of the auroral magnetic bays indicates that although they seldom occurred simultaneously, 80% of the waves were observed within 1 hour of the bay onset. Therefore it is concluded that the condition of the magnetosphere after a substorm is favorable for the occurrence of the ring current proton ultralow-frequency waves

  14. Experimental particle acceleration by water evaporation induced by shock waves

    Science.gov (United States)

    Scolamacchia, T.; Alatorre Ibarguengoitia, M.; Scheu, B.; Dingwell, D. B.; Cimarelli, C.

    2010-12-01

    Shock waves are commonly generated during volcanic eruptions. They induce sudden changes in pressure and temperature causing phase changes. Nevertheless, their effects on flowfield properties are not well understood. Here we investigate the role of gas expansion generated by shock wave propagation in the acceleration of ash particles. We used a shock tube facility consisting of a high-pressure (HP) steel autoclave (450 mm long, 28 mm in internal diameter), pressurized with Ar gas, and a low-pressure tank at atmospheric conditions (LP). A copper diaphragm separated the HP autoclave from a 180 mm tube (PVC or acrylic glass) at ambient P, with the same internal diameter of the HP reservoir. Around the tube, a 30 cm-high acrylic glass cylinder, with the same section of the LP tank (40 cm), allowed the observation of the processes occurring downstream from the nozzle throat, and was large enough to act as an unconfined volume in which the initial diffracting shock and gas jet expand. All experiments were performed at Pres/Pamb ratios of 150:1. Two ambient conditions were used: dry air and air saturated with steam. Carbon fibers and glass spheres in a size range between 150 and 210 μm, were placed on a metal wire at the exit of the PVC tube. The sudden decompression of the Ar gas, due to the failure of the diaphragm, generated an initial air shock wave. A high-speed camera recorded the processes between the first 100 μsec and several ms after the diaphragm failure at frame rates ranging between 30,000 and 50,000 fps. In the experiments with ambient air saturated with steam, the high-speed camera allowed to visualize the condensation front associated with the initial air shock; a maximum velocity of 788 m/s was recorded, which decreases to 524 m/s at distance of 0.5 ±0.2 cm, 1.1 ms after the diaphragm rupture. The condensation front preceded the Ar jet front exhausting from the reservoir, by 0.2-0.5 ms. In all experiments particles velocities following the initial

  15. Thon rings from amorphous ice and implications of beam-induced Brownian motion in single particle electron cryo-microscopy

    Energy Technology Data Exchange (ETDEWEB)

    McMullan, G., E-mail: gm2@mrc-lmb.cam.ac.uk; Vinothkumar, K.R.; Henderson, R.

    2015-11-15

    We have recorded dose-fractionated electron cryo-microscope images of thin films of pure flash-frozen amorphous ice and pre-irradiated amorphous carbon on a Falcon II direct electron detector using 300 keV electrons. We observe Thon rings [1] in both the power spectrum of the summed frames and the sum of power spectra from the individual frames. The Thon rings from amorphous carbon images are always more visible in the power spectrum of the summed frames whereas those of amorphous ice are more visible in the sum of power spectra from the individual frames. This difference indicates that while pre-irradiated carbon behaves like a solid during the exposure, amorphous ice behaves like a fluid with the individual water molecules undergoing beam-induced motion. Using the measured variation in the power spectra amplitude with number of electrons per image we deduce that water molecules are randomly displaced by a mean squared distance of ∼1.1 Å{sup 2} for every incident 300 keV e{sup −}/Å{sup 2}. The induced motion leads to an optimal exposure with 300 keV electrons of 4.0 e{sup −}/Å{sup 2} per image with which to observe Thon rings centred around the strong 3.7 Å scattering peak from amorphous ice. The beam-induced movement of the water molecules generates pseudo-Brownian motion of embedded macromolecules. The resulting blurring of single particle images contributes an additional term, on top of that from radiation damage, to the minimum achievable B-factor for macromolecular structure determination. - Highlights: • Thon rings can be seen from amorphous ice. • Radiation damage to amorphous ice randomly displaces water molecules. • Each incident 300 keV e{sup −}/Å{sup 2} displaces water molecules on average by ∼1 Å. • Macromolecules embedded in amorphous ice undergo beam induced Brownian motion.

  16. Vacillations induced by interference of stationary and traveling planetary waves

    Science.gov (United States)

    Salby, Murry L.; Garcia, Rolando R.

    1987-01-01

    The interference pattern produced when a traveling planetary wave propagates over a stationary forced wave is explored, examining the interference signature in a variety of diagnostics. The wave field is first restricted to a diatomic spectrum consisting of two components: a single stationary wave and a single monochromatic traveling wave. A simple barotropic normal mode propagating over a simple stationary plane wave is considered, and closed form solutions are obtained. The wave fields are then restricted spatially, providing more realistic structures without sacrificing the advantages of an analytical solution. Both stationary and traveling wave fields are calculated numerically with the linearized Primitive Equations in a realistic basic state. The mean flow reaction to the fluctuating eddy forcing which results from interference is derived. Synoptic geopotential behavior corresponding to the combined wave and mean flow fields is presented, and the synoptic signature in potential vorticity on isentropic surfaces is examined.

  17. Electromagnetically Induced Transparency in Four Wave Mixing Process

    International Nuclear Information System (INIS)

    Kucukkara, I.

    2008-01-01

    We have theoretically studied Four Wave Mixing (FWM) process in VUV (Vacuum Ultraviolet) region enhanced by Electromagnetically Induced Transparency in Krypton gas medium at room temperature. One of the mixing fields, in the ultraviolet region at 212.5 nm was in two-photon resonance with the 4p 6 1 S 0 -4p 5 5p[0,1/2] transition of Krypton and the second field (coupling field) at 759 nm was resonant with the 4p 5 5p[0,1/2]-4p 5 5s[1,1/2] transition in scheme. This coupling field produced an electromagnetically induced transparency and thus the efficiency of the generation of the field at 123.6 nm on the 4p 5 5s[1,1/2] to 4p 6 1 S 0 transition is enhanced. We modified the computer program previously written by changing some variables like pressure, interaction region length, UV energy, IR energy. As demonstrated by the intensity generated VUV light versus Krypton pressure graphic, the most efficient intensity value, which was approximately 4.2x10 1 6 arbitrary units, was obtained while IR energy was 3x10 - 4 J and the pressure was 2x10 - 3 bar

  18. Wave-induced release of methane : littoral zones as a source of methane in lakes

    OpenAIRE

    Hofmann, Hilmar; Federwisch, Luisa; Peeters, Frank

    2010-01-01

    This study investigates the role of surface waves and the associated disturbance of littoral sediments for the release and later distribution of dissolved methane in lakes. Surface wave field, wave-induced currents, acoustic backscatter strength, and the concentration and distribution of dissolved methane were measured simultaneously in Lake Constance, Germany. The data indicate that surface waves enhance the release of dissolved methane in the shallow littoral zone via burst-like releases of...

  19. Benzoylureas as removable cis amide inducers: synthesis of cyclic amides via ring closing metathesis (RCM).

    Science.gov (United States)

    Brady, Ryan M; Khakham, Yelena; Lessene, Guillaume; Baell, Jonathan B

    2011-02-07

    Rapid and high yielding synthesis of medium ring lactams was made possible through the use of a benzoylurea auxiliary that serves to stabilize a cisoid amide conformation, facilitating cyclization. The auxiliary is released after activation under the mild conditions required to deprotect a primary amine, such as acidolysis of a Boc group in the examples given here. This methodology is a promising tool for the synthesis of medium ring lactams, macrocyclic natural products and peptides.

  20. Saturation of the laser-induced narrowband coherent synchrotron radiation process: Experimental observation at a storage ring

    Science.gov (United States)

    Hosaka, M.; Yamamoto, N.; Takashima, Y.; Szwaj, C.; Le Parquier, M.; Evain, C.; Bielawski, S.; Adachi, M.; Zen, H.; Tanikawa, T.; Kimura, S.; Katoh, M.; Shimada, M.; Takahashi, T.

    2013-02-01

    We study the efficiency limitation affecting laser-induced coherent synchrotron radiation (CSR) at high laser power. Experiments are made on the UVSOR-II storage ring in conditions of narrowband terahertz CSR emission. While, at moderate power, CSR power increases quadratically with laser power, a noticeable decrease in efficiency and eventually a decrease in CSR power is observed experimentally at high power. Details of the underlying process are analyzed numerically. As the saturation effect depends almost instantaneously on the laser intensity, the saturation occurs locally in longitudinal space. This has important consequences on the modulation pattern induced on the electron bunch.

  1. Rosmarinic Acid Alleviates the Endothelial Dysfunction Induced by Hydrogen Peroxide in Rat Aortic Rings via Activation of AMPK

    Directory of Open Access Journals (Sweden)

    Hui Zhou

    2017-01-01

    Full Text Available Endothelial dysfunction is the key player in the development and progression of vascular events. Oxidative stress is involved in endothelial injury. Rosmarinic acid (RA is a natural polyphenol with antioxidative, antiapoptotic, and anti-inflammatory properties. The present study investigates the protective effect of RA on endothelial dysfunction induced by hydrogen peroxide (H2O2. Compared with endothelium-denuded aortic rings, the endothelium significantly alleviated the decrease of vasoconstrictive reactivity to PE and KCl induced by H2O2. H2O2 pretreatment significantly injured the vasodilative reactivity to ACh in endothelium-intact aortic rings in a concentration-dependent manner. RA individual pretreatment had no obvious effect on the vasoconstrictive reaction to PE and KCl, while its cotreatment obviously mitigated the endothelium-dependent relaxation impairments and the oxidative stress induced by H2O2. The RA cotreatment reversed the downregulation of AMPK and eNOS phosphorylation induced by H2O2 in HAEC cells. The pretreatment with the inhibitors of AMPK (compound C and eNOS (L-NAME wiped off RA’s beneficial effects. All these results demonstrated that RA attenuated the endothelial dysfunction induced by oxidative stress by activating the AMPK/eNOS pathway.

  2. Ring Theory

    CERN Document Server

    Jara, Pascual; Torrecillas, Blas

    1988-01-01

    The papers in this proceedings volume are selected research papers in different areas of ring theory, including graded rings, differential operator rings, K-theory of noetherian rings, torsion theory, regular rings, cohomology of algebras, local cohomology of noncommutative rings. The book will be important for mathematicians active in research in ring theory.

  3. Second-order Monte Carlo wave-function approach to the relaxation effects on ringing revivals in a molecular system interacting with a strongly squeezed coherent field

    International Nuclear Information System (INIS)

    Nakano, Masayoshi; Kishi, Ryohei; Nitta, Tomoshige; Yamaguchi, Kizashi

    2004-01-01

    We investigate the relaxation effects on the quantum dynamics in a two-state molecular system interacting with a single-mode strongly amplitude-squeezed coherent field using the second-order Monte Carlo wave-function method. The molecular population inversion (collapse-revival behavior of Rabi oscillations) is known to show the echoes after each revival, which are referred to as ringing revivals, in the case of strongly squeezed coherent fields with oscillatory photon-number distributions due to the phase-space interference effect. Two types of relaxation effects, i.e., cavity relaxation (the dissipation of an internal single mode to outer mode) and molecular coherent (phase) relaxation caused by nuclear vibrations on ringing revivals are investigated from the viewpoint of the quantum-phase dynamics using the quasiprobability (Q function) distribution of a single-mode field and the off-diagonal molecular density matrix ρ elec1,2 (t). It turns out that the molecular phase relaxation attenuates both the entire revival-collapse behavior and the increase in ρ elec1,2 (t) during the quiescent region, whereas a very slight cavity relaxation particularly suppresses the echoes in ringing revivals more significantly than the first revival but hardly changes a primary variation in envelope of ρ elec1,2 (t) in the nonrelaxation case

  4. Investigation of the radiation properties of magnetospheric ELF waves induced by modulated ionospheric heating

    Science.gov (United States)

    Wang, Feng; Ni, Binbin; Zhao, Zhengyu; Zhao, Shufan; Zhao, Guangxin; Wang, Min

    2017-05-01

    Electromagnetic extremely low frequency (ELF) waves play an important role in modulating the Earth's radiation belt electron dynamics. High-frequency (HF) modulated heating of the ionosphere acts as a viable means to generate artificial ELF waves. The artificial ELF waves can reside in two different plasma regions in geo-space by propagating in the ionosphere and penetrating into the magnetosphere. As a consequence, the entire trajectory of ELF wave propagation should be considered to carefully analyze the wave radiation properties resulting from modulated ionospheric heating. We adopt a model of full wave solution to evaluate the Poynting vector of the ELF radiation field in the ionosphere, which can reflect the propagation characteristics of the radiated ELF waves along the background magnetic field and provide the initial condition of waves for ray tracing in the magnetosphere. The results indicate that the induced ELF wave energy forms a collimated beam and the center of the ELF radiation shifts obviously with respect to the ambient magnetic field with the radiation power inversely proportional to the wave frequency. The intensity of ELF wave radiation also shows a weak correlation with the size of the radiation source or its geographical location. Furthermore, the combination of ELF propagation in the ionosphere and magnetosphere is proposed on basis of the characteristics of the ELF radiation field from the upper ionospheric boundary and ray tracing simulations are implemented to reasonably calculate magnetospheric ray paths of ELF waves induced by modulated ionospheric heating.

  5. High-Frequency Gravitational Wave Induced Nuclear Fusion

    International Nuclear Information System (INIS)

    Fontana, Giorgio; Baker, Robert M. L. Jr.

    2007-01-01

    Nuclear fusion is a process in which nuclei, having a total initial mass, combine to produce a single nucleus, having a final mass less than the total initial mass. Below a given atomic number the process is exothermic; that is, since the final mass is less than the combined initial mass and the mass deficit is converted into energy by the nuclear fusion. On Earth nuclear fusion does not happen spontaneously because electrostatic barriers prevent the phenomenon. To induce controlled, industrial scale, nuclear fusion, only a few methods have been discovered that look promising, but net positive energy production is not yet possible because of low overall efficiency of the systems. In this paper we propose that an intense burst of High Frequency Gravitational Waves (HFGWs) could be focused or beamed to a target mass composed of appropriate fuel or target material to efficiently rearrange the atomic or nuclear structure of the target material with consequent nuclear fusion. Provided that efficient generation of HFGW can be technically achieved, the proposed fusion reactor could become a viable solution for the energy needs of mankind and alternatively a process for beaming energy to produce a source of fusion energy remotely - even inside solid materials

  6. Simulation of Irregular Waves and Wave Induced Loads on Wind Power Plants in Shallow Water

    Energy Technology Data Exchange (ETDEWEB)

    Trumars, Jenny [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Water Environment Transport

    2004-05-01

    The essay gives a short introduction to waves and discusses the problem with non-linear waves in shallow water and how they effect an offshore wind energy converter. The focus is on the realisation of non-linear waves in the time domain from short-term statistics in the form of a variance density spectrum of the wave elevation. For this purpose the wave transformation from deep water to the near to shore site of a wind energy farm at Bockstigen has been calculated with the use of SWAN (Simulating Waves Near Shore). The result is a wave spectrum, which can be used as input to the realisation. The realisation of waves is done by perturbation theory to the first and second-order. The properties calculated are the wave elevation, water particle velocity and acceleration. The wave heights from the second order perturbation equations are higher than those from the first order perturbation equations. This is also the case for the water particle kinematics. The increase of variance is significant between the first order and the second order realisation. The calculated wave elevation exhibits non-linear features as the peaks become sharper and the troughs flatter. The resulting forces are calculated using Morison's equation. For second order force and base moment there is an increase in the maximum values. The force and base moment are largest approximately at the zero up and down crossing of the wave elevation. This indicates an inertia dominated wave load. So far the flexibility and the response of the structure have not been taken into account. They are, however, of vital importance. For verification of the wave model the results will later on be compared with measurements at Bockstigen off the coast of Gotland in the Baltic Sea.

  7. Characterization of electron clouds in the Cornell Electron Storage Ring Test Accelerator using TE-wave transmission

    International Nuclear Information System (INIS)

    De Santis, S.; Byrd, J.M.; Billing, M.; Palmer, M.; Sikora, J.; Carlson, B.

    2010-01-01

    A relatively new technique for measuring the electron cloud density in storage rings has been developed and successfully demonstrated (S. De Santis, J.M. Byrd, F. Caspers, A. Krasnykh, T. Kroyer, M.T.F. Pivi, and K.G. Sonnad, Phys. Rev. Lett. 100, 094801 (2008).). We present the experimental results of a systematic application of this technique at the Cornell Electron Storage Ring Test Accelerator. The technique is based on the phase modulation of the TE mode transmitted in a synchrotron beam pipe caused by the periodic variation of the density of electron plasma. Because of the relatively simple hardware requirements, this method has become increasingly popular and has been since successfully implemented in several machines. While the principles of this technique are straightforward, quantitative derivation of the electron cloud density from the measurement requires consideration of several effects, which we address in detail.

  8. High-Q contacted ring microcavities with scatterer-avoiding “wiggler” Bloch wave supermode fields

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yangyang, E-mail: yangyang.liu@colorado.edu; Popović, Miloš A., E-mail: milos.popovic@colorado.edu [Nanophotonic Systems Laboratory, Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder, Colorado 80309 (United States)

    2014-05-19

    High-Q ring resonators with contacts to the waveguide core provide a versatile platform for various applications in chip-scale optomechanics, thermo-, and electro-optics. We propose and demonstrate azimuthally periodic contacted ring resonators based on multi-mode Bloch matching that support contacts on both the inner and outer radius edges with small degradation to the optical quality factor (Q). Radiative coupling between degenerate modes of adjacent radial spatial order leads to imaginary frequency (Q) splitting and a scatterer avoiding high-Q “wiggler” supermode field. We experimentally measure Qs up to 258 000 in devices fabricated in a silicon device layer on buried oxide undercladding and up to 139 000 in devices fully suspended in air using an undercut step. Wiggler supermodes are true modes of the microphotonic system that offer additional degrees of freedom in electrical, thermal, and mechanical design.

  9. Thon rings from amorphous ice and implications of beam-induced Brownian motion in single particle electron cryo-microscopy.

    Science.gov (United States)

    McMullan, G; Vinothkumar, K R; Henderson, R

    2015-11-01

    We have recorded dose-fractionated electron cryo-microscope images of thin films of pure flash-frozen amorphous ice and pre-irradiated amorphous carbon on a Falcon II direct electron detector using 300 keV electrons. We observe Thon rings [1] in both the power spectrum of the summed frames and the sum of power spectra from the individual frames. The Thon rings from amorphous carbon images are always more visible in the power spectrum of the summed frames whereas those of amorphous ice are more visible in the sum of power spectra from the individual frames. This difference indicates that while pre-irradiated carbon behaves like a solid during the exposure, amorphous ice behaves like a fluid with the individual water molecules undergoing beam-induced motion. Using the measured variation in the power spectra amplitude with number of electrons per image we deduce that water molecules are randomly displaced by a mean squared distance of ∼1.1 Å(2) for every incident 300 keV e(-)/Å(2). The induced motion leads to an optimal exposure with 300 keV electrons of 4.0 e(-)/Å(2) per image with which to observe Thon rings centred around the strong 3.7 Å scattering peak from amorphous ice. The beam-induced movement of the water molecules generates pseudo-Brownian motion of embedded macromolecules. The resulting blurring of single particle images contributes an additional term, on top of that from radiation damage, to the minimum achievable B-factor for macromolecular structure determination. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

  10. Sensor integration of multiple tripolar concentric ring electrodes improves pentylenetetrazole-induced seizure onset detection in rats.

    Science.gov (United States)

    Makeyev, Oleksandr; Ding, Quan; Kay, Steven M; Besio, Walter G

    2012-01-01

    As epilepsy affects approximately one percent of the world population, electrical stimulation of the brain has recently shown potential for additive seizure control therapy. Previously, we applied noninvasive transcranial focal stimulation via tripolar concentric ring electrodes on the scalp of rats after inducing seizures with pentylenetetrazole. We developed a system to detect seizures and automatically trigger the stimulation and evaluated the system on the electrographic activity from rats. In this preliminary study we propose and validate a novel seizure onset detection algorithm based on exponentially embedded family. Unlike the previously proposed approach it integrates the data from multiple electrodes allowing an improvement of the detector performance.

  11. Stochastic procedures for extreme wave induced responses in flexible ships

    DEFF Research Database (Denmark)

    Jensen, Jørgen Juncher; Andersen, Ingrid Marie Vincent; Seng, Sopheak

    2014-01-01

    Different procedures for estimation of the extreme global wave hydroelastic responses in ships are discussed. Firstly, stochastic procedures for application in detailed numerical studies (CFD) are outlined. The use of the First Order Reliability Method (FORM) to generate critical wave episodes...

  12. Interfacial instability induced by a shock wave in a gas-liquid horizontal stratified system

    International Nuclear Information System (INIS)

    Sutradhar, S.C.; Chang, J.S.; Yoshida, H.

    1987-01-01

    The experiments are performed in a rectangular lucite duct equipped with the facility of generating shock waves. Piezo-type pressure transducers are used to monitor the strength and propagation velocity of the shock wave. As the liquid phase has high sound velocity, a prepulse wave system of flow amplitude travels in this phase at a speed faster than the principal shock wave. The magnitude of the transmitted wave in the liquid phase is estimated using a transmission coefficient for gas-liquid system. From the initial pressure ratio of the shock wave, the amplitude of the prepulse as well as the induced interfacial fluid velocity are calculated. The wave length and height of the ripples during the passage of the shock wave are estimated for a specific strength of shock wave moving through the phases. From the high speed photographs, the wave length of the ripples can be assessed. The interfacial friction factor is calculated using colebrook's equation for high speed flow. At least five distinct phenomena are observed to exist during the propagation of a shock wave. These are - (1) the energy carried by the pre-pulse is utilized in perturbing the interface; (2) shock wave induces a mass velocity at the interface; (3) the wavelength of the ripples at the interface is the product of induced interfacial mass velocity and the time period of the prepulse; (4) a portion of the liquid mass of the perturbed interface is entrained in the gas phase may be due to the hydrodynamic lift in that phase; and finally (5) waves with long wavelength are established at the interface

  13. Ship-induced solitary Riemann waves of depression in Venice Lagoon

    International Nuclear Information System (INIS)

    Parnell, Kevin E.; Soomere, Tarmo; Zaggia, Luca; Rodin, Artem; Lorenzetti, Giuliano; Rapaglia, John; Scarpa, Gian Marco

    2015-01-01

    We demonstrate that ships of moderate size, sailing at low depth Froude numbers (0.37–0.5) in a navigation channel surrounded by shallow banks, produce depressions with depths up to 2.5 m. These depressions (Bernoulli wakes) propagate as long-living strongly nonlinear solitary Riemann waves of depression substantial distances into Venice Lagoon. They gradually become strongly asymmetric with the rear of the depression becoming extremely steep, similar to a bore. As they are dynamically similar, air pressure fluctuations moving over variable-depth coastal areas could generate meteorological tsunamis with a leading depression wave followed by a devastating bore-like feature. - Highlights: • Unprecedently deep long-living ship-induced waves of depression detected. • Such waves are generated in channels with side banks under low Froude numbers. • The propagation of these waves is replicated using Riemann waves. • Long-living waves of depression form bore-like features at rear slope

  14. Ship-induced solitary Riemann waves of depression in Venice Lagoon

    Energy Technology Data Exchange (ETDEWEB)

    Parnell, Kevin E. [College of Marine and Environmental Sciences and Centre for Tropical Environmental and Sustainability Sciences, James Cook University, Queensland 4811 (Australia); Institute of Cybernetics at Tallinn University of Technology, Akadeemia tee 21, 12618 Tallinn (Estonia); Soomere, Tarmo, E-mail: soomere@cs.ioc.ee [Institute of Cybernetics at Tallinn University of Technology, Akadeemia tee 21, 12618 Tallinn (Estonia); Estonian Academy of Sciences, Kohtu 6, 10130 Tallinn (Estonia); Zaggia, Luca [Institute of Marine Sciences, National Research Council, Castello 2737/F, 30122 Venice (Italy); Rodin, Artem [Institute of Cybernetics at Tallinn University of Technology, Akadeemia tee 21, 12618 Tallinn (Estonia); Lorenzetti, Giuliano [Institute of Marine Sciences, National Research Council, Castello 2737/F, 30122 Venice (Italy); Rapaglia, John [Sacred Heart University Department of Biology, 5151 Park Avenue, Fairfield, CT 06825 (United States); Scarpa, Gian Marco [Università Ca' Foscari, Dorsoduro 3246, 30123 Venice (Italy)

    2015-03-06

    We demonstrate that ships of moderate size, sailing at low depth Froude numbers (0.37–0.5) in a navigation channel surrounded by shallow banks, produce depressions with depths up to 2.5 m. These depressions (Bernoulli wakes) propagate as long-living strongly nonlinear solitary Riemann waves of depression substantial distances into Venice Lagoon. They gradually become strongly asymmetric with the rear of the depression becoming extremely steep, similar to a bore. As they are dynamically similar, air pressure fluctuations moving over variable-depth coastal areas could generate meteorological tsunamis with a leading depression wave followed by a devastating bore-like feature. - Highlights: • Unprecedently deep long-living ship-induced waves of depression detected. • Such waves are generated in channels with side banks under low Froude numbers. • The propagation of these waves is replicated using Riemann waves. • Long-living waves of depression form bore-like features at rear slope.

  15. Dispersive waves induced by self-defocusing temporal solitons in a beta-barium-borate crystal

    DEFF Research Database (Denmark)

    Zhou, Binbin; Bache, Morten

    2015-01-01

    We experimentally observe dispersive waves in the anomalous dispersion regime of a beta-barium-borate (BBO) crystal, induced by a self-defocusing few-cycle temporal soliton. Together the soliton and dispersive waves form an energetic octave-spanning supercontinuum. The soliton was excited...

  16. Irradiation induced densification and its correlation with three-membered rings in vitreous silica

    Czech Academy of Sciences Publication Activity Database

    Gavenda, T.; Gedeon, O.; Jurek, Karel

    2015-01-01

    Roč. 425, Oct (2015), s. 61-66 ISSN 0022-3093 R&D Projects: GA ČR(CZ) GA15-12580S Institutional support: RVO:68378271 Keywords : silica glass * electron irradiation * densification * Raman spectroscopy * glass topology * three-membered rings Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 1.825, year: 2015

  17. Large-scale bedforms induced by supercritical flows and wave-wave interference in the intertidal zone (Cap Ferret, France)

    Science.gov (United States)

    Vaucher, Romain; Pittet, Bernard; Humbert, Thomas; Ferry, Serge

    2017-11-01

    The Cap Ferret sand spit is situated along the wave-dominated, tidally modulated Atlantic coast of western France, characterized by a semidiurnal macrotidal range. It displays peculiar dome-like bedforms that can be observed at low tide across the intertidal zone. These bedforms exhibit a wavelength of ca. 1.2 m and an elevation of ca. 30 cm. They occur only when the incident wave heights reach 1.5-2 m. The internal stratifications are characterized by swaley-like, sub-planar, oblique-tangential, oblique-tabular, as well as hummocky-like stratifications. The tabular and tangential stratifications comprise prograding oblique sets (defined as foresets and backsets) that almost always show variations in their steepness. Downcutting into the bottomsets of the oblique-tangential stratifications is common. The sets of laminae observed in the bedforms share common characteristics with those formed by supercritical flows in flume experiments of earlier studies. These peculiar bedforms are observed at the surf-swash transition zone where the backwash flow reaches supercritical conditions. This type of flow can explain their internal architecture but not their general dome-like (three-dimensional) morphology. Wave-wave interference induced by the geomorphology (i.e. tidal channel) of the coastal environment is proposed as explanation for the localized formation of such bedforms. This study highlights that the combination of supercritical flows occurring in the surf-swash transition zone and wave-wave interferences can generate dome-like bedforms in intertidal zones.

  18. Photon-induced tunability of the thermospin current in a Rashba ring

    Science.gov (United States)

    Abdullah, Nzar Rauf; Arnold, Thorsten; Tang, Chi-Shung; Manolescu, Andrei; Gudmundsson, Vidar

    2018-04-01

    The goal of this work is to show how the thermospin polarization current in a quantum ring changes in the presence of Rashba spin-orbit coupling and a quantized single photon mode of a cavity the ring is placed in. Employing the reduced density operator and a general master equation formalism, we find that both the Rashba interaction and the photon field can significantly modulate the spin polarization and the thermospin polarization current. Tuning the Rashba coupling constant, degenerate energy levels are formed corresponding to the Aharonov-Casher destructive phase interference in the quantum ring system. Our analysis indicates that the maximum spin polarization can be observed at the points of degenerate energy levels due to spin accumulation in the system without the photon field. The thermospin current is thus suppressed. In the presence of the cavity, the photon field leads to an additional kinetic momentum of the electron. As a result the spin polarization can be enhanced by the photon field.

  19. Wave-induced nearshore circulation along the Calangute-Candolim beach, Goa, West coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Krishnakumar, V.; Murty, C.S.; Heblekar, A.K.

    The wave-induced nearshore circulation model suggested by Noda has been modified and applied for three small segments along the coast of Goa. The present model incorporates the prevailing bottom topography and considers its variation along...

  20. The instability of the spiral wave induced by the deformation of elastic excitable media

    International Nuclear Information System (INIS)

    Ma Jun; Jia Ya; Wang Chunni; Li Shirong

    2008-01-01

    There are some similarities between the spiral wave in excitable media and in cardiac tissue. Much evidence shows that the appearance and instability of the spiral wave in cardiac tissue can be linked to one kind of heart disease. There are many models that can be used to investigate the formation and instability of the spiral wave. Cardiac tissue is excitable and elastic, and it is interesting to simulate the transition and instability of the spiral wave induced by media deformation. For simplicity, a class of the modified Fitzhugh-Nagumo (MFHN) model, which can generate a stable rotating spiral wave, meandering spiral wave and turbulence within appropriate parameter regions, will be used to simulate the instability of the spiral wave induced by the periodical deformation of media. In the two-dimensional case, the total acreage of elastic media is supposed to be invariable in the presence of deformation, and the problem is described with L x x L y = N x ΔxN x Δy = L' x L' y = N x Δx'N x Δy'. In our studies, elastic media are decentralized into N x N sites and the space of the adjacent sites is changed to simulate the deformation of elastic media. Based on the nonlinear dynamics theory, the deformation effect on media is simplified and simulated by perturbing the diffusion coefficients D x and D y with different periodical signals, but the perturbed diffusion coefficients are compensatory. The snapshots of our numerical results find that the spiral wave can coexist with the spiral turbulence, instability of the spiral wave and weak deformation of the spiral wave in different conditions. The ratio parameter ε and the frequency of deformation forcing play a deterministic role in inducing instability of the spiral wave. Extensive studies confirm that the instability of the spiral wave can be induced and developed only if an appropriate frequency for deformation is used. We analyze the power spectrum for the time series of the mean activator of four sampled sites

  1. The instability of the spiral wave induced by the deformation of elastic excitable media

    Science.gov (United States)

    Ma, Jun; Jia, Ya; Wang, Chun-Ni; Li, Shi-Rong

    2008-09-01

    There are some similarities between the spiral wave in excitable media and in cardiac tissue. Much evidence shows that the appearance and instability of the spiral wave in cardiac tissue can be linked to one kind of heart disease. There are many models that can be used to investigate the formation and instability of the spiral wave. Cardiac tissue is excitable and elastic, and it is interesting to simulate the transition and instability of the spiral wave induced by media deformation. For simplicity, a class of the modified Fitzhugh-Nagumo (MFHN) model, which can generate a stable rotating spiral wave, meandering spiral wave and turbulence within appropriate parameter regions, will be used to simulate the instability of the spiral wave induced by the periodical deformation of media. In the two-dimensional case, the total acreage of elastic media is supposed to be invariable in the presence of deformation, and the problem is described with Lx × Ly = N × ΔxN × Δy = L'xL'y = N × Δx'N × Δy'. In our studies, elastic media are decentralized into N × N sites and the space of the adjacent sites is changed to simulate the deformation of elastic media. Based on the nonlinear dynamics theory, the deformation effect on media is simplified and simulated by perturbing the diffusion coefficients Dx and Dy with different periodical signals, but the perturbed diffusion coefficients are compensatory. The snapshots of our numerical results find that the spiral wave can coexist with the spiral turbulence, instability of the spiral wave and weak deformation of the spiral wave in different conditions. The ratio parameter ɛ and the frequency of deformation forcing play a deterministic role in inducing instability of the spiral wave. Extensive studies confirm that the instability of the spiral wave can be induced and developed only if an appropriate frequency for deformation is used. We analyze the power spectrum for the time series of the mean activator of four sampled sites

  2. Scalar field vacuum expectation value induced by gravitational wave background

    Science.gov (United States)

    Jones, Preston; McDougall, Patrick; Ragsdale, Michael; Singleton, Douglas

    2018-06-01

    We show that a massless scalar field in a gravitational wave background can develop a non-zero vacuum expectation value. We draw comparisons to the generation of a non-zero vacuum expectation value for a scalar field in the Higgs mechanism and with the dynamical Casimir vacuum. We propose that this vacuum expectation value, generated by a gravitational wave, can be connected with particle production from gravitational waves and may have consequences for the early Universe where scalar fields are thought to play an important role.

  3. A hydrodynamic model of nearshore waves and wave-induced currents

    Directory of Open Access Journals (Sweden)

    Ahmed Khaled Seif

    2011-09-01

    Full Text Available In This study develops a quasi-three dimensional numerical model of wave driven coastal currents with accounting the effects of the wave-current interaction and the surface rollers. In the wave model, the current effects on wave breaking and energy dissipation are taken into account as well as the wave diffraction effect. The surface roller associated with wave breaking was modeled based on a modification of the equations by Dally and Brown (1995 and Larson and Kraus (2002. Furthermore, the quasi-three dimensional model, which based on Navier-Stokes equations, was modified in association with the surface roller effect, and solved using frictional step method. The model was validated by data sets obtained during experiments on the Large Scale Sediment Transport Facility (LSTF basin and the Hazaki Oceanographical Research Station (HORS. Then, a model test against detached breakwater was carried out to investigate the performance of the model around coastal structures. Finally, the model was applied to Akasaki port to verify the hydrodynamics around coastal structures. Good agreements between computations and measurements were obtained with regard to the cross-shore variation in waves and currents in nearshore and surf zone.

  4. Influence of thermal effects induced by nonlinear absorption on four-wave mixing in silicon waveguides

    DEFF Research Database (Denmark)

    Pu, Minhao; Chen, Yaohui; Yvind, Kresten

    2014-01-01

    Influence of thermal effects induced by nonlinear absorption on four-wave mixing in silicon waveguides is investigated. A conversion bandwidth reduction up to 63% is observed in simulation due to the thermal effects.......Influence of thermal effects induced by nonlinear absorption on four-wave mixing in silicon waveguides is investigated. A conversion bandwidth reduction up to 63% is observed in simulation due to the thermal effects....

  5. The sequence of sediment behaviour during wave-induced liquefaction

    DEFF Research Database (Denmark)

    Sumer, B. Mutlu; Hatipoglu, Figen; Fredsøe, Jørgen

    2006-01-01

    to be in agreement with recent centrifuge wave-tank experiments. As for the final stage of the sequence of processes (formation of ripples), the ripple steepness (normalized with the angle of repose) for sediment with liquefaction history is found to be the same as that in sediment with no liquefaction history.......This paper presents the results of an experimental investigation of the complete sequence of sediment behaviour beneath progressive waves. The sediment was silty with d(50) = 0.060 mm. Two kinds of measurements were carried out: pore-water pressure measurements (across the sediment depth...... of liquefaction and compaction fronts in the sediment and (iii) the characteristics of the orbital motion of the liquefied sediment including the motion of the interface between the water body and the sediment. The ranges of the various quantities in the tests were: wave height, H = 9-17 cm, wave period, T = 1...

  6. Characterization of electron clouds in the Cornell Electron Storage Ring Test Accelerator using TE-wave transmission

    Directory of Open Access Journals (Sweden)

    S. De Santis

    2010-07-01

    Full Text Available A relatively new technique for measuring the electron cloud density in storage rings has been developed and successfully demonstrated [S. De Santis, J. M. Byrd, F. Caspers, A. Krasnykh, T. Kroyer, M. T. F. Pivi, and K. G. Sonnad, Phys. Rev. Lett. 100, 094801 (2008.PRLTAO0031-900710.1103/PhysRevLett.100.094801]. We present the experimental results of a systematic application of this technique at the Cornell Electron Storage Ring Test Accelerator. The technique is based on the phase modulation of the TE mode transmitted in a synchrotron beam pipe caused by the periodic variation of the density of electron plasma. Because of the relatively simple hardware requirements, this method has become increasingly popular and has been since successfully implemented in several machines. While the principles of this technique are straightforward, quantitative derivation of the electron cloud density from the measurement requires consideration of several effects, which we address in detail.

  7. Excitation of plasma waves by nonlinear currents induced by a high-frequency electromagnetic pulse

    Energy Technology Data Exchange (ETDEWEB)

    Grishkov, V. E.; Uryupin, S. A., E-mail: uryupin@sci.lebedev.ru [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)

    2017-03-15

    Excitation of plasma waves by nonlinear currents induced by a high-frequency electromagnetic pulse is analyzed within the kinetic approach. It is shown that the most efficient source of plasma waves is the nonlinear current arising due to the gradient of the energy density of the high-frequency field. Generation of plasma waves by the drag current is usually less efficient but not negligibly small at relatively high frequencies of electron–ion collisions. The influence of electron collisions on the excitation of plasma waves by pulses of different duration is described quantitatively.

  8. Poloidal rotation induced by injecting lower hybrid waves in tokamak plasma edge

    International Nuclear Information System (INIS)

    Jiao Yiming; Gao Qingdi; Shi Bingren

    2001-01-01

    The poloidal rotation of the magnetized edge plasma in tokamak driven by the ponderomotive force which is generated by injecting lower hybrid wave (LHW) electric field has been studied. The LHW is launched from a waveguide in the plasma edge, and by Brambilla's grill theory, analytic expressions for the wave electric field in the slab model of an inhomogeneous cold plasma have been derived. It is shown that a strong wave electric field will be generated in the plasma edge by injecting LH wave of the power in MW magnitude, and this electric field will induce a poloidal rotation with a sheared poloidal velocity

  9. Charging-delay induced dust acoustic collisionless shock wave: Roles of negative ions

    International Nuclear Information System (INIS)

    Ghosh, Samiran; Bharuthram, R.; Khan, Manoranjan; Gupta, M. R.

    2006-01-01

    The effects of charging-delay and negative ions on nonlinear dust acoustic waves are investigated. It has been found that the charging-delay induced anomalous dissipation causes generation of dust acoustic collisionless shock waves in an electronegative dusty plasma. The small but finite amplitude wave is governed by a Korteweg-de Vries Burger equation in which the Burger term arises due to the charging-delay. Numerical investigations reveal that the charging-delay induced dissipation and shock strength decreases (increases) with the increase of negative ion concentration (temperature)

  10. Estimation of Ship Long-term Wave-induced Bending Moment using Closed-Form Expressions

    DEFF Research Database (Denmark)

    Jensen, Jørgen Juncher; Mansour, A. E.

    2002-01-01

    A semi-analytical approach is used to derive frequency response functions and standard deviations for the wave-induced bending moment amidships for mono-hull ships. The results are given as closed-form expressions and the required input information for the procedure is restricted to the main......-empirical closed-form expression for the skewness. The effect of whipping is included by assuming that whipping and wave-induced responses are conditionally independent given Hs. The procedure is simple and can be used to make quick estimates of the design wave bending moment at the conceptual design phase...

  11. Volcano-induced regime shifts in millennial tree-ring chronologies from northeastern North America.

    Science.gov (United States)

    Gennaretti, Fabio; Arseneault, Dominique; Nicault, Antoine; Perreault, Luc; Bégin, Yves

    2014-07-15

    Dated records of ice-cap growth from Arctic Canada recently suggested that a succession of strong volcanic eruptions forced an abrupt onset of the Little Ice Age between A.D. 1275 and 1300 [Miller GH, et al. (2012) Geophys Res Lett 39(2):L02708, 10.1029/2011GL050168]. Although this idea is supported by simulation experiments with general circulation models, additional support from field data are limited. In particular, the Northern Hemisphere network of temperature-sensitive millennial tree-ring chronologies, which principally comprises Eurasian sites, suggests that the strongest eruptions only caused cooling episodes lasting less than about 10 y. Here we present a new network of millennial tree-ring chronologies from the taiga of northeastern North America, which fills a wide gap in the network of the Northern Hemisphere's chronologies suitable for temperature reconstructions and supports the hypothesis that volcanoes triggered both the onset and the coldest episode of the Little Ice Age. Following the well-expressed Medieval Climate Anomaly (approximately A.D. 910-1257), which comprised the warmest decades of the last millennium, our tree-ring-based temperature reconstruction displays an abrupt regime shift toward lower average summer temperatures precisely coinciding with a series of 13th century eruptions centered around the 1257 Samalas event and closely preceding ice-cap expansion in Arctic Canada. Furthermore, the successive 1809 (unknown volcano) and 1815 (Tambora) eruptions triggered a subsequent shift to the coldest 40-y period of the last 1100 y. These results confirm that series of large eruptions may cause region-specific regime shifts in the climate system and that the climate of northeastern North America is especially sensitive to volcanic forcing.

  12. Measurement of surface-induced microplasticity in Alloy 600 C-rings

    International Nuclear Information System (INIS)

    Lo, C.F.; Kamide, H.; Mayo, W.E.; Weissmann, S.

    1990-03-01

    The level of microplasticity in Alloy 600 specimens used for accelerated SCC tests was measured with the aid of a novel x-ray rocking curve technique developed at Rutgers University. With this tool, it was possible to measure quantitatively the strain level at any point along the circumference of a C-ring. Combined with selective etching, the method was used to obtain a depth profile of the strain. A detailed study of the deformation state in C-rings was performed with a particular emphasis on how material parameters influence localization of the strain. These studies included the role of grain boundary carbides, grain size and mill anneal temperatures. The studies led to the development of a numerical model for calculation of the strain distribution along a C-ring which is superior to that currently in use. An additional result of these studies was a simple indirect method that can be used to determine the amount of grain boundary carbides present in tubes of Alloy 600. The final phase of this project was to measure the strain relaxation kinetics in this alloy. From this work, the activation energy for relaxation and the atomistic process responsible were identified. Based on this work, calculations were performed to indicate the degree of relaxation that can be expected during normal steam generator operation and accelerated SCC testing. These calculations suggest that relaxation may be significant in the temperature range of 280--360 degree C which is typical for such tests and highlights the fact that during these tests significant changes in the microstructure that can be detected by x-rays are taking place. These results will provide a more accurate basis for extrapolating tests to actual steam generator corrosion experience. 6 figs., 2 tabs

  13. Application of proving-ring technology to measure thermally induced displacements in large boreholes in rock

    International Nuclear Information System (INIS)

    Patrick, W.C.; Reactor, N.L.; Butkovich, T.R.

    1984-03-01

    A strain-gauged proving-ring transducer was designed and deployed to measure small diametral displacements in 0.61-m diameter boreholes in rock. The rock surrounding the boreholes was previously heated by storage of spent nuclear fuel assemblies and measurements during post-retrieval cooling of the rock were made. To accomplish this, a transducer was designed to measure displacements in the range of 10 to 100 μm, to function in a time-varying temperature regime of 30 0 to 60 0 C at a relative humidity of 100%, to be of low stiffness, and to be easily and quickly installed. 7 references, 6 figures, 1 table

  14. Propagation of electromagnetic waves in the plasma near electron cyclotron resonance: Undulator-induced transparency

    International Nuclear Information System (INIS)

    Shvets, G.; Tushentsov, M.; Tokman, M.D.; Kryachko, A.

    2005-01-01

    Propagation of electromagnetic waves in magnetized plasma near the electron cyclotron frequency can be strongly modified by adding a weak magnetic undulator. For example, both right- and left-hand circularly polarized waves can propagate along the magnetic field without experiencing resonant absorption. This effect of entirely eliminating electron cyclotron heating is referred to as the undulator-induced transparency (UIT) of the plasma, and is the classical equivalent of the well-known quantum mechanical effect of electromagnetically induced transparency. The basics of UIT are reviewed, and various ways in which UIT can be utilized to achieve exotic propagation properties of electromagnetic waves in plasmas are discussed. For example, UIT can dramatically slow down the waves' group velocity, resulting in the extreme compression of the wave energy in the plasma. Compressed waves are polarized along the propagation direction, and can be used for synchronous electron or ion acceleration. Strong coupling between the two wave helicities are explored to impart the waves with high group velocities ∂ω/∂k for vanishing wave numbers k. Cross-helicity coupling for realistic density and magnetic field profiles are examined using a linearized fluid code, particle-in-cell simulations, and ray-tracing WKB calculations

  15. Extreme Wave-Induced Oscillation in Paradip Port Under the Resonance Conditions

    Science.gov (United States)

    Kumar, Prashant; Gulshan

    2017-12-01

    A mathematical model is constructed to analyze the long wave-induced oscillation in Paradip Port, Odisha, India under the resonance conditions to avert any extreme wave hazards. Boundary element method (BEM) with corner contribution is utilized to solve the Helmholtz equation under the partial reflection boundary conditions. Furthermore, convergence analysis is also performed for the boundary element scheme with uniform and non-uniform discretization of the boundary. The numerical scheme is also validated with analytic approximation and existing studies based on harbor resonance. Then, the amplification factor is estimated at six key record stations in the Paradip Port with multidirectional incident waves and resonance modes are also estimated at the boundary of the port. Ocean surface wave field is predicted in the interior of Paradip Port for the different directional incident wave at various resonance modes. Moreover, the safe locations in the port have been identified for loading and unloading of moored ship with different resonance modes and directional incident waves.

  16. Induced wave propagation from a vibrating containment envelope

    International Nuclear Information System (INIS)

    Stout, R.B.; Thigpen, L.; Rambo, J.T.

    1985-09-01

    Low frequency wave forms are observed in the particle velocity measurements around the cavity and containment envelope formed by an underground nuclear test. The vibration solution for a spherical shell is used to formulate a model for the low frequency wave that propagates outward from this region. In this model the containment envelope is the zone of material that is crushed by the compressive shock wave of the nuclear explosion. The containment envelope is approximated by a spherical shell of material. The material in the spherical shell is densified and is given a relatively high kinetic energy density because of the high compressive stress and particle velocity of the shock wave. After the shock wave has propagated through the spherical shell, the spherical shell vibrates in order to dissipate the kinetic energy acquired from the shock wave. Based on the model, the frequency of vibration depends on the dimensions and material properties of the spherical shell. The model can also be applied in an inverse mode to obtain global estimates of averaged materials properties. This requires using experimental data and semi-empirical relationships involving the material properties. A particular case of estimating a value for shear strength is described. Finally, the oscillation time period of the lowest frequency from five nuclear tests is correlated with the energy of the explosion. The correlation provides another diagnostic to estimate the energy of a nuclear explosion. Also, the longest oscillation time period measurement provides additional experimental data that can be used to assess and validate various computer models. 11 refs., 2 figs

  17. Influence of clay content on wave-induced liquefaction

    DEFF Research Database (Denmark)

    Kirca, V.S. Ozgur; Sumer, B. Mutlu; Fredsøe, Jørgen

    2014-01-01

    of measurements were carried out: (1) pore-water pressure measurements across the soil depth and (2) water-surface elevation measurements. These measurements were synchronized with video recordings of the liquefaction process from the side. The ranges of the various quantities in the experiments were wave height...... of silt and clay was not liquefied. Sand may become prone to liquefaction with the introduction of clay, contrary to the general perception that this type of sediment is normally liquefaction-resistant under waves. For instance, sand with d50 50:4 mmwas liquefied with CC510:8%, whereas sand with d50 50...

  18. Gravity induced corrections to quantum mechanical wave functions

    International Nuclear Information System (INIS)

    Singh, T.P.

    1990-03-01

    We perform a semiclassical expansion in the Wheeler-DeWitt equation, in powers of the gravitational constant. We then show that quantum gravitational fluctuations can provide a correction to the wave-functions which are solutions of the Schroedinger equation for matter. This also implies a correction to the expectation values of quantum mechanical observables. (author). 6 refs

  19. Flow and sediment transport induced by a plunging solitary wave

    DEFF Research Database (Denmark)

    Sumer, B. Mutlu; Sen, M.Berke; Karagali, Ioanna

    2011-01-01

    Two parallel experiments involving the evolution and runup of plunging solitary waves on a sloping bed were conducted: (1) a rigid-bed experiment, allowing direct (hot film) measurements of bed shear stresses, and (2) a sediment-bed experiment, allowing for the measurement of pore-water pressures...

  20. Cell detachment method using shock wave induced cavitation

    NARCIS (Netherlands)

    Junge, L.; Junge, L.; Ohl, C.D.; Wolfrum, B.; Arora, M.; Ikink, R.

    2003-01-01

    The detachment of adherent HeLa cells from a substrate after the interaction with a shock wave is analyzed. Cavitation bubbles are formed in the trailing, negative pressure cycle following the shock front. We find that the regions of cell detachment are strongly correlated with spatial presence of

  1. On Current Drive and Wave Induced Bootstrap Current in Toroidal Plasmas

    International Nuclear Information System (INIS)

    Hellsten, T.; Johnson, T.

    2008-01-01

    A comprehensive treatment of wave-particle interactions in toroidal plasmas including collisional relaxation, applicable to heating or anomalous wave induced transport, has been obtained by using Monte Carlo operators satisfying quasi-neutrality. This approach enables a self-consistent treatment of wave-particle interactions applicable to the banana regime in the neoclassical theory. It allows an extension into a regime with large temperature and density gradients, losses and transport of particles by wave-particle interactions making the method applicable to transport barriers. It is found that at large gradients the relationship between radial electric field, parallel velocity, temperature and density gradient in the neoclassical theory is modified such that coefficient in front of the logarithmic ion temperature gradient, which in the standard neoclassical theory is small and counteracts the electric field caused by the density gradient, now changes sign and contributes to the built up of the radial electric field. The possibility to drive current by absorbing the waves on trapped particles has been studied and how the wave-particle interactions affect the bootstrap current. Two new current drive mechanisms are studied: current drive by wave induced bootstrap current and selective detrapping into passing orbits by directed waves.

  2. Width dependent transition of quantized spin-wave modes in Ni80Fe20 square nanorings

    Science.gov (United States)

    Banerjee, Chandrima; Saha, Susmita; Barman, Saswati; Rousseau, Olivier; Otani, YoshiChika; Barman, Anjan

    2014-10-01

    We investigated optically induced ultrafast magnetization dynamics in square shaped Ni80Fe20 nanorings with varying ring width. Rich spin-wave spectra are observed whose frequencies showed a strong dependence on the ring width. Micromagnetic simulations showed different types of spin-wave modes, which are quantized upto very high quantization number. In the case of widest ring, the spin-wave mode spectrum shows quantized modes along the applied field direction, which is similar to the mode spectrum of an antidot array. As the ring width decreases, additional quantization in the azimuthal direction appears causing mixed modes. In the narrowest ring, the spin-waves exhibit quantization solely in azimuthal direction. The different quantization is attributed to the variation in the internal field distribution for different ring width as obtained from micromagnetic analysis and supported by magnetic force microscopy.

  3. Wave-induced extreme water levels in the Puerto Morelos fringing reef lagoon

    Directory of Open Access Journals (Sweden)

    A. Torres-Freyermuth

    2012-12-01

    Full Text Available Wave-induced extreme water levels in the Puerto Morelos fringing reef lagoon are investigated by means of a phase-resolving non-hydrostatic wave model (SWASH. This model solves the nonlinear shallow water equations including non-hydrostatic pressure. The one-dimensional version of the model is implemented in order to investigate wave transformation in fringing reefs. Firstly, the numerical model is validated with (i laboratory experiments conducted on a physical model (Demirbilek et al., 2007and (ii field observations (Coronado et al., 2007. Numerical results show good agreement with both experimental and field data. The comparison against the physical model results, for energetic wave conditions, indicates that high- and low-frequency wave transformation is well reproduced. Moreover, extreme water-level conditions measured during the passage of Hurricane Ivan in Puerto Morelos are also estimated by the numerical tool. Subsequently, the model is implemented at different along-reef locations in Puerto Morelos. Extreme water levels, wave-induced setup, and infragravity wave energy are estimated inside the reef lagoon for different storm wave conditions (Hs >2 m. The numerical results revealed a strong correlation between the offshore sea-swell wave energy and the setup. In contrast, infragravity waves are shown to be the result of a more complex pattern which heavily relies on the reef geometry. Indeed, the southern end of the reef lagoon provides evidence of resonance excitation, suggesting that the reef barrier may act as either a natural flood protection morphological feature, or as an inundation hazard enhancer depending on the incident wave conditions.

  4. Periodic rotation noise induced by the crosstalk between two beat-frequency signals in multi-oscillator ring laser gyros

    International Nuclear Information System (INIS)

    Lu, Guangfeng; Wang, Zhiguo; Fan, Zhenfang; Luo, Hui

    2014-01-01

    Periodic rotation noise in the outputs of multi-oscillator ring laser gyros (MRLGs) is investigated in this paper for the first time. It is proved theoretically and experimentally that noise is induced by the crosstalk between two beat-frequency signals, which are combined from the left and right circularly polarized counter-propagating beams in MRLGs. Theoretical analysis and experimental results also indicate that the fundamental frequency of this noise is equal to the frequency difference between the two beat-frequency signals and the amplitude of the fundamental component is proportional to the crosstalk ratio between the two beat-frequency signals. Further, the amplitude of the nth-order component is proportional to the nth power of the crosstalk ratio. (paper)

  5. Slow light based on plasmon-induced transparency in dual-ring resonator-coupled MDM waveguide system

    International Nuclear Information System (INIS)

    Zhan, Shiping; Li, Hongjian; He, Zhihui; Li, Boxun; Yang, Hui; Cao, Guangtao

    2014-01-01

    We report a theoretical and numerical investigation of the plasmon-induced transparency (PIT) effect in a dual-ring resonator-coupled metal–dielectric–metal waveguide system. A transfer matrix method (TMM) is introduced to analyse the transmission and dispersion properties in the transparency window. A tunable PIT is realized in a constant separation design. The phase dispersion and slow-light effect are discussed in both the resonance and non-resonance conditions. Finally, a propagation constant based on the TMM is derived for the periodic system. It is found that the group index in the transparency window of the proposed structure can be easily tuned by the period p, which provides a new understanding, and a group index ∼51 is achieved. The quality factor of resonators can also be effective in adjusting the dispersion relation. These observations could be helpful to fundamental research and applications for integrated plasmonic devices. (paper)

  6. Mesoscale variations in acoustic signals induced by atmospheric gravity waves.

    Science.gov (United States)

    Chunchuzov, Igor; Kulichkov, Sergey; Perepelkin, Vitaly; Ziemann, Astrid; Arnold, Klaus; Kniffka, Anke

    2009-02-01

    The results of acoustic tomographic monitoring of the coherent structures in the lower atmosphere and the effects of these structures on acoustic signal parameters are analyzed in the present study. From the measurements of acoustic travel time fluctuations (periods 1 min-1 h) with distant receivers, the temporal fluctuations of the effective sound speed and wind speed are retrieved along different ray paths connecting an acoustic pulse source and several receivers. By using a coherence analysis of the fluctuations near spatially distanced ray turning points, the internal wave-associated fluctuations are filtered and their spatial characteristics (coherences, horizontal phase velocities, and spatial scales) are estimated. The capability of acoustic tomography in estimating wind shear near ground is shown. A possible mechanism describing the temporal modulation of the near-ground wind field by ducted internal waves in the troposphere is proposed.

  7. Induced photoassociation in the field of a strong electomagnetic wave

    International Nuclear Information System (INIS)

    Zaretskij, D.F.; Lomonosov, V.V.; Lyul'ka, V.A.

    1979-01-01

    The quantum-mechanical problem of the stimulated transition of a system in the field of a strong electromagnetic wave from the continuous spectrum to a bound state possessing a finite lifetime is considered. The expressions obtained are employed to calculate stimulated production of mesic atoms and mesic molecules (ddμ). It is demonstrated that in an external electromagnetic field the probability for production of this type may considerably increase

  8. Numerical simulation of wave-induced scour and backfilling processes beneath submarine pipelines

    DEFF Research Database (Denmark)

    Fuhrman, David R.; Baykal, Cüneyt; Sumer, B. Mutlu

    2014-01-01

    A fully-coupled hydrodynamic/morphodynamic numerical model is presented and utilized for the simulation of wave-induced scour and backfilling processes beneath submarine pipelines. The model is based on solutions to Reynolds-averaged Navier–Stokes equations, coupled with k−ω turbulence closure......≤30 demonstrate reasonable match with previous experiments, both in terms of the equilibrium scour depth as well as the scour time scale. Wave-induced backfilling processes are additionally studied by subjecting initial conditions taken from scour simulations with larger KC to new wave climates...... characterized by lower KC values. The simulations considered demonstrate the ability of the model to predict backfilling toward expected equilibrium scour depths based on the new wave climate, in line with experimental expectations. The simulated backfilling process is characterized by two stages: (1...

  9. Roughness-induced streaming in turbulent wave boundary layers

    DEFF Research Database (Denmark)

    Fuhrman, David R.; Sumer, B. Mutlu; Fredsøe, Jørgen

    2011-01-01

    -averaged streaming characteristics induced by bottom roughness variations are systematically assessed. The effects of variable roughness ratio, gradual roughness transitions, as well as changing flow orientation in plan are all considered. As part of the latter, roughness-induced secondary flows are predicted...

  10. Feasibility of recording high frequency oscillations with tripolar concentric ring electrodes during pentylenetetrazole-induced seizures in rats.

    Science.gov (United States)

    Makeyev, Oleksandr; Liu, Xiang; Wang, Liling; Zhu, Zhenghan; Taveras, Aristides; Troiano, Derek; Medvedev, Andrei V; Besio, Walter G

    2012-01-01

    As epilepsy remains a refractory condition in about 30% of patients with complex partial seizures, electrical stimulation of the brain has recently shown potential for additive seizure control therapy. Previously, we applied noninvasive transcranial focal stimulation via novel tripolar concentric ring electrodes (TCREs) on the scalp of rats after inducing seizures with pentylenetetrazole (PTZ). We developed a close-loop system to detect seizures and automatically trigger the stimulation and evaluated its effect on the electrographic activity recorded by TCREs in rats. In our previous work the detectors of seizure onset were based on seizure-induced changes in signal power in the frequency range up to 100 Hz, while in this preliminary study we assess the feasibility of recording high frequency oscillations (HFOs) in the range up to 300 Hz noninvasively with scalp TCREs during PTZ-induced seizures. Grand average power spectral density estimate and generalized likelihood ratio tests were used to compare power of electrographic activity at different stages of seizure development in a group of rats (n= 8). The results suggest that TCREs have the ability to record HFOs from the scalp as well as that scalp-recorded HFOs can potentially be used as features for seizure onset detection.

  11. Effects of transcranial focal electrical stimulation via tripolar concentric ring electrodes on pentylenetetrazole-induced seizures in rats.

    Science.gov (United States)

    Besio, W G; Makeyev, O; Medvedev, A; Gale, K

    2013-07-01

    To study the effects of noninvasive transcranial focal electrical stimulation (TFS) via tripolar concentric ring electrodes (TCRE) on the electrographic and behavioral activity from pentylenetetrazole (PTZ)-induced seizures in rats. The TCREs were attached to the rat scalp. PTZ was administered and, after the first myoclonic jerk was observed, TFS was applied to the TFS treated group. The electroencephalogram (EEG) and behavioral activity were recorded and studied. In the case of the TFS treated group, after TFS, there was a significant (p=0.001) decrease in power compared to the control group in delta, theta, and alpha frequency bands. The number of myoclonic jerks was significantly different (p=0.002) with median of 22 and 4.5 for the control group and the TFS treated groups, respectively. The duration of myoclonic activity was also significantly different (p=0.031) with median of 17.56 min for the control group versus 8.63 min for the TFS treated group. At the same time there was no significant difference in seizure onset latency and maximal behavioral seizure activity score between control and TFS treated groups. TFS via TCREs interrupted PTZ-induced seizures and electrographic activity was reduced toward the "baseline." The significantly reduced electrographic power, number of myoclonic jerks, and duration of myoclonic activity of PTZ-induced seizures suggests that TFS may have an anticonvulsant effect. Copyright © 2012 Elsevier B.V. All rights reserved.

  12. Energization of helium ions by proton-induced hydromagnetic waves

    International Nuclear Information System (INIS)

    Gendrin, R.; Roux, A.

    1980-01-01

    We consider the diffusion of He + ions under the influence of ion cyclotron waves generated in a plasma consisting of three different ion populations: a thermal isotropic population containing both H + and He + ions and an energetic H + population, with a positive anisotropy A=T/sub perpendicular//T/sub parallel/-1. We compute, in the velocity space upsilon/sub parallel/, upsilon/sub perpendicular/, the diffusion curves that He + ions will follow in the presence of ion cyclotron waves propagating in such a medium. We show that for small concentrations of the He + ions, of the order of 1 to approx.10%, these ions can be energized by such a process up to and above suprathermal energies (E> or approx. =20 eV). On some occasions the He + ions may even reach energies of the order of the Alfven energy of the cold plasma population: E/sub a/approx. =m/sub p/V/sub a/ 2 approx. =5 keV. Characteristic diffusion times, in pitch angle and energy, for both ion species, are evaluated. They are of the order of 2 to 20 min. These theoretical results are discussed in the frame of recent observations by Geos experimenters showing the close association that exists between the occurrence of ion cyclotron ULF waves and the presence of thermal or supra-thermal He + ions in the equatorial region of the magnetosphere

  13. Black rings

    International Nuclear Information System (INIS)

    Emparan, Roberto; Reall, Harvey S

    2006-01-01

    A black ring is a five-dimensional black hole with an event horizon of topology S 1 x S 2 . We provide an introduction to the description of black rings in general relativity and string theory. Novel aspects of the presentation include a new approach to constructing black ring coordinates and a critical review of black ring microscopics. (topical review)

  14. Ring laser frequency biasing mechanism

    International Nuclear Information System (INIS)

    McClure, R.E.

    1975-01-01

    A ring laser cavity including a magnetically saturable member for differentially phase shifting the contradirectional waves propagating in the laser cavity, the phase shift being produced by the magneto-optic interaction occurring between the light waves and the magnetization in the cavity forming component as the light waves are reflected therefrom is described

  15. Reduced Sodium Current in the Lateral Ventricular Wall Induces Inferolateral J-Waves.

    Science.gov (United States)

    Meijborg, Veronique M F; Potse, Mark; Conrath, Chantal E; Belterman, Charly N W; De Bakker, Jacques M T; Coronel, Ruben

    2016-01-01

    J-waves in inferolateral leads are associated with a higher risk for idiopathic ventricular fibrillation. We aimed to test potential mechanisms (depolarization or repolarization dependent) responsible for inferolateral J-waves. We hypothesized that inferolateral J-waves can be caused by regional delayed activation of myocardium that is activated late during normal conditions. Computer simulations were performed to evaluate how J-point elevation is influenced by reducing sodium current conductivity (GNa), increasing transient outward current conductivity (Gto), or cellular uncoupling in three predefined ventricular regions (lateral, anterior, or septal). Two pig hearts were Langendorff-perfused with selective perfusion with a sodium channel blocker of lateral or anterior/septal regions. Volume-conducted pseudo-electrocardiograms (ECG) were recorded to detect the presence of J-waves. Epicardial unipolar electrograms were simultaneously recorded to obtain activation times (AT). Simulation data showed that conduction slowing, caused by reduced sodium current, in lateral, but not in other regions induced inferolateral J-waves. An increase in transient outward potassium current or cellular uncoupling in the lateral zone elicited slight J-point elevations which did not meet J-wave criteria. Additional conduction slowing in the entire heart attenuated J-waves and J-point elevations on the ECG, because of masking by the QRS. Experimental data confirmed that conduction slowing attributed to sodium channel blockade in the left lateral but not in the anterior/septal ventricular region induced inferolateral J-waves. J-waves coincided with the delayed activation. Reduced sodium current in the left lateral ventricular myocardium can cause inferolateral J-waves on the ECG.

  16. Quantum chaos induced by nonadiabatic coupling in wave-packet dynamics

    International Nuclear Information System (INIS)

    Higuchi, Hisashi; Takatsuka, Kazuo

    2002-01-01

    The effect of nonadiabatic coupling due to breakdown of the Born-Oppenheimer approximation on chaos is investigated. A couple of measures (indicators) that detect the extent of chaos in wave-packet dynamics on coupled potential functions are devised. Using them, we show that chaos is indeed induced by a nonadiabatic coupling in individual time-dependent wave-packet dynamics. This chaos is genuinely of quantum nature, since it arises from bifurcation and merging of a wave packet at the quasicrossing region of two coupled potential functions

  17. Secondary current properties generated by wind-induced water waves in experimental conditions

    Directory of Open Access Journals (Sweden)

    Michio Sanjou

    2014-06-01

    Full Text Available Secondary currents such as the Langmuir circulation are of high interest in natural rivers and the ocean because they have striking impacts on scour, sedimentation, and mass transport. Basic characteristics have been well-studied in straight open-channel flows. However, little is known regarding secondary circulation induced by wind waves. The presented study describes the generation properties of wind waves observed in the laboratory tank. Wind-induced water waves are known to produce large scale circulations. The phenomenon is observed together with high-speed and low-speed streaks, convergence and divergence zones, respectively. Therefore, it is important to determine the hydrodynamic properties of secondary currents for wind-induced water waves within rivers and lakes. In this study, using two high-speed CMOS cameras, stereoscopic particle image velocimetry (PIV measurements were conducted in order to reveal the distribution of all three components of velocity vectors. The experiments allowed us to investigate the three-dimensional turbulent structure under water waves and the generation mechanism of large-scale circulations. Additionally, a third CMOS camera was used to measure the spanwise profile of thefree-surface elevation. The time-series of velocity components and the free-surface were obtained simultaneously. From our experiments, free-surface variations were found to influence the instantaneous velocity distributions of the cross-sectional plane. We also considered thegeneration process by the phase analysis related to gravity waves and compared the contribution of the apparent stress.

  18. Shock wave and flame front induced detonation in a rapid compression machine

    Science.gov (United States)

    Wang, Y.; Qi, Y.; Xiang, S.; Mével, R.; Wang, Z.

    2018-05-01

    The present study focuses on one mode of detonation initiation observed in a rapid compression machine (RCM). This mode is referred to as shock wave and flame front-induced detonation (SWFID). Experimental high-speed imaging and two-dimensional numerical simulations with skeletal chemistry are combined to unravel the dominant steps of detonation initiation under SWFID conditions. It is shown that the interaction between the shock wave generated by the end-gas auto-ignition and the spherical flame creates a region of high pressure and temperature which enables the acceleration of the flame front and the detonation onset. The experimental observation lacks adequate spatial and temporal resolution despite good reproducibility of the detonation onset. Based on the numerical results, phenomenological interpretation of the event within the framework of shock wave refraction indicates that the formation of a free-precursor shock wave at the transition between regular and irregular refraction may be responsible for detonation onset. The present results along with previous findings on shock wave reflection-induced detonation in the RCM indicate that super-knock occurs after the interaction of the shock wave generated by end-gas auto-ignition with the RCM walls, preignition flame, or another shock wave.

  19. White Ring; White ring

    Energy Technology Data Exchange (ETDEWEB)

    Aoki, H.; Yuzawa, H. [Nikken Sekkei Ltd., Osaka (Japan)

    1998-01-05

    White Ring is a citizen`s gymnasium used for figure skating and short track speed skating games of 18th Winter Olympic Games in 1998. White Ring is composed of a main-arena and a sub-arena. For the main-arena with an area 41mtimes66m, an ice link can be made by disengaging the potable floor and by flowing brine in the bridged polystyrene pipes embedded in the concrete floor. Due to the fortunate groundwater in this site, well water is used for the outside air treatment energy in 63% during heating and in 35% during cooling. Ammonia is used as a cooling medium for refrigerating facility. For the heating of audience area in the large space, heat load from the outside is reduced by enhancing the heat insulation performance of the roof of arena. The audience seats are locally heated using heaters. For the White Ring, high quality environment is realized for games through various functions of the large-scale roof of the large space. Success of the big event was expected. 15 figs., 4 tabs.

  20. Shock Induced Melting in Aluminum: Wave Profile Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Chhabildas, Lalit C.; Furnish, Michael D.; Reinhart, William D.

    1999-06-23

    We have developed launch capabilities that can propel macroscopic plates to hypervelocities (8 to 16 km/s). This capability has been used to determine the first time-resolved wave profile measurements using velocity interferometry techniques at impact velocities of 10 km/s. These measurements show that alu- minum continues to exhibit normal release behavior to 161 GPa with complete loss of strength in the shocked state. Results of these experiments are discussed and compared with the results of lower pressure experi- ments conducted at lower impact velocities.

  1. Measurement and modelling of bed shear induced by solitary waves

    Digital Repository Service at National Institute of Oceanography (India)

    JayaKumar, S.

    kleiner reibung. Z. Math. Phys., 56: 1- 37. Burbidge, D. and Cummins, P., 2007. Assessing the threat to western australia from tsunami generated by earthquakes along the sunda arc. Natural Hazards, 43(3): 319-331. Christian, J.T., Taylor, P.K., Yen, J....E. and Bernard, E.N., 2006. Tsunami science before and beyond boxing day 2004. Philosophical Transactions - A Math Physics Engineering Science, 364(1845): 2231-2265. Tadepalli, S. and Synolakis, C.E., 1994. The run-up of n-waves on sloping beaches...

  2. Visible light- and radiation-induced alkylation of pyridine ring with alkanoic acid

    International Nuclear Information System (INIS)

    Sugimori, Akira; Yamada, Tetsuo

    1986-01-01

    Quinoline and 4-methylquinoline are efficiently alkylated with alkanoic acid in the presence of iron(III) sulfate upon visible light-irradiation. Iron(III) sulfate not only accelerates the photoreaction but also increases the yield of alkylation. Gamma-irradiation also brings about the alkylation. In the photo- and radiation-induced alkylation with alkanoic acid, alkyl radicals play important roles. (author)

  3. Chaos induced by breakup of waves in a spatial epidemic model with nonlinear incidence rate

    International Nuclear Information System (INIS)

    Sun, Gui-Quan; Jin, Zhen; Liu, Quan-Xing; Li, Li

    2008-01-01

    Spatial epidemiology is the study of spatial variation in disease risk or incidence, including the spatial patterns of the population. The spread of diseases in human populations can exhibit large scale patterns, underlining the need for spatially explicit approaches. In this paper, the spatiotemporal complexity of a spatial epidemic model with nonlinear incidence rate, which includes the behavioral changes and crowding effect of the infective individuals, is investigated. Based on both theoretical analysis and computer simulations, we find out when, under the parameters which can guarantee a stable limit cycle in the non-spatial model, spiral and target waves can emerge. Moreover, two different kinds of breakup of waves are shown. Specifically, the breakup of spiral waves is from the core and the breakup of target waves is from the far-field, and both kinds of waves become irregular patterns at last. Our results reveal that the spatiotemporal chaos is induced by the breakup of waves. The results obtained confirm that diffusion can form spiral waves, target waves or spatial chaos of high population density, which enrich the findings of spatiotemporal dynamics in the epidemic model

  4. Effects of wave-induced forcing on a circulation model of the North Sea

    Science.gov (United States)

    Staneva, Joanna; Alari, Victor; Breivik, Øyvind; Bidlot, Jean-Raymond; Mogensen, Kristian

    2017-04-01

    The effect of wind waves on water level and currents during two storms in the North Sea is investigated using a high-resolution NEMO model forced with fluxes and fields from a high-resolution wave model. The additional terms accounting for wave-current interaction that are considered in this study are the Stokes-Coriolis force and the sea-state dependent energy and momentum fluxes. The individual and collective role of these processes is quantified and the results are compared with a control run without wave effects as well as against current and water level measurements from coastal stations. We find a better agreement with observations when the circulation model is forced by sea-state dependent fluxes, especially in extreme events. The two extreme events, the storm Christian (25-27 October 2013), and about a month later, the storm Xaver (5-7 December 2013), induce different wave and surge conditions over the North Sea. Including the wave effects in the circulation model for the storm Xaver raises the modelled surge by more than 40 cm compared with the control run in the German Bight area. For the storm Christian, a difference of 20-30 cm in the surge level between the wave-forced and the stand-alone ocean model is found over the whole southern part of the North Sea. Moreover, the modelled vertical velocity profile fits the observations very well when the wave forcing is accounted for. The contribution of wave-induced forcing has been quantified indicating that this represents an important mechanism for improving water level and current predictions.

  5. Width dependent transition of quantized spin-wave modes in Ni{sub 80}Fe{sub 20} square nanorings

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, Chandrima; Saha, Susmita; Barman, Saswati; Barman, Anjan, E-mail: abarman@bose.res.in [Thematic Unit of Excellence on Nanodevice Technology, Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700098 (India); Rousseau, Olivier [CEMS-RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Otani, YoshiChika [CEMS-RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan)

    2014-10-28

    We investigated optically induced ultrafast magnetization dynamics in square shaped Ni{sub 80}Fe{sub 20} nanorings with varying ring width. Rich spin-wave spectra are observed whose frequencies showed a strong dependence on the ring width. Micromagnetic simulations showed different types of spin-wave modes, which are quantized upto very high quantization number. In the case of widest ring, the spin-wave mode spectrum shows quantized modes along the applied field direction, which is similar to the mode spectrum of an antidot array. As the ring width decreases, additional quantization in the azimuthal direction appears causing mixed modes. In the narrowest ring, the spin-waves exhibit quantization solely in azimuthal direction. The different quantization is attributed to the variation in the internal field distribution for different ring width as obtained from micromagnetic analysis and supported by magnetic force microscopy.

  6. Storage and retrieval of electromagnetic waves with orbital angular momentum via plasmon-induced transparency.

    Science.gov (United States)

    Bai, Zhengyang; Xu, Datang; Huang, Guoxiang

    2017-01-23

    We propose a scheme to realize the storage and retrieval of high-dimensional electromagnetic waves with orbital angular momentum (OAM) via plasmon-induced transparency (PIT) in a metamaterial, which consists of an array of meta-atoms constructed by a metallic structure loaded with two varactors. We show that due to PIT effect the system allows the existence of shape-preserving dark-mode plasmonic polaritons, which are mixture of electromagnetic-wave modes and dark oscillatory modes of the meta-atoms and may carry various OAMs. We demonstrate that the slowdown, storage and retrieval of multi-mode electromagnetic waves with OAMs can be achieved through the active manipulation of a control field. Our work raises the possibility for realizing PIT-based spatial multi-mode memory of electromagnetic waves and is promising for practical application of information processing with large capacity by using room-temperature metamaterials.

  7. Vortex rings

    CERN Document Server

    Akhmetov, D G

    2009-01-01

    This text on vortex rings covers their theoretical foundation, systematic investigations, and practical applications such as the extinction of fires at gushing oil wells. It pays special attention to the formation and motion of turbulent vortex rings.

  8. Body-wave seismic interferometry applied to earthquake- and storm-induced wavefield

    NARCIS (Netherlands)

    Ruigrok, E.N.

    2012-01-01

    Seismology is the study of the vibration of the Earth. Seismologists pay much attention to the main source of Earth vibration: earthquakes. But also other seismic sources, like mining blasts, ocean storms and windmills, are studied. All these sources induce seismic waves, which can eventually be

  9. Shock wave-induced evaporation of water droplets in a gas-droplet mixture 646

    NARCIS (Netherlands)

    Goossens, H.W.J.; Cleijne, J.W.; Smolders, H.J.; Dongen, van M.E.H.

    1988-01-01

    A model is presented for the droplet evaporation process induced by a shock wave propagating in a fog. The model is based on the existence of a quasi-steady wet bulb state of the droplets during evaporation. It is shown that for moderate shock strength, Ma = <2,=" and=" droplet=" radii=" in=" the="

  10. A case study of typhoon-induced gravity waves and the orographic impacts related to Typhoon Mindulle (2004) over Taiwan

    OpenAIRE

    Wu, J. F.; Xue, X. H.; Hoffmann, L.; Dou, X. K.; Li, H. M.; Chen, T. D.

    2015-01-01

    Atmospheric gravity waves (GWs) significantly influence global circulation. Deep convection, particularly that associated with typhoons, is believed to be an important source of gravity waves. Stratospheric gravity waves induced by Typhoon Mindulle (2004) were detected by the Atmospheric Infrared Sounder (AIRS). Semicircular GWs with horizontal wavelengths of 100–400 km were found over Taiwan through an inspection of AIRS radiances at 4.3 μm. Characteristics of the stratospheric gravity waves...

  11. Nonlinear mechanisms for drift wave saturation and induced particle transport

    International Nuclear Information System (INIS)

    Dimits, A.M.; Lee, W.W.

    1989-12-01

    A detailed theoretical study of the nonlinear dynamics of gyrokinetic particle simulations of electrostatic collisionless and weakly collisional drift waves is presented. In previous studies it was shown that, in the nonlinearly saturated phase of the evolution, the saturation levels and especially the particle fluxes have an unexpected dependence on collisionality. In this paper, the explanations for these collisionality dependences are found to be as follows: The saturation level is determined by a balance between the electron and ion fluxes. The ion flux is small for levels of the potential below an E x B-trapping threshold and increases sharply once this threshold is crossed. Due to the presence of resonant electrons, the electron flux has a much smoother dependence on the potential. In the 2-1/2-dimensional (''pseudo-3D'') geometry, the electrons are accelerated away from the resonance as they diffuse spatially, resulting in an inhibition of their diffusion. Collisions and three-dimensional effects can repopulate the resonance thereby increasing the value of the particle flux. 30 refs., 32 figs., 2 tabs

  12. Solvent micro-evaporation and concentration gradient synergistically induced crystallization of poly(L-lactide) and ring banded supra-structures with radial periodic variation of thickness

    DEFF Research Database (Denmark)

    Huang, Shaoyong; Li, Hongfei; Wen, Huiying

    2014-01-01

    The crystalline morphology and structure of poly(L-lactide) (PLLA) in a PLLA film-chloroform system were investigated by means of wide angle X-ray diffraction (WAXD), polarized optical microscopy (POM) and atomic force microscopy (AFM). Birefringent and nonbirefringent ring banded supra-structure......The crystalline morphology and structure of poly(L-lactide) (PLLA) in a PLLA film-chloroform system were investigated by means of wide angle X-ray diffraction (WAXD), polarized optical microscopy (POM) and atomic force microscopy (AFM). Birefringent and nonbirefringent ring banded supra......-structures with radial periodic variation of thickness were obtained, which were induced by micro-evaporation of solvents and concentration gradient of PLLA. The ring banded morphologies consisted of multilayer lamellar crystals, which is a manifestation of alternating ridge and valley bands of periodic variation...

  13. Inducing rostrum interfacial waves by fluid-solid coupling in a Chinese river dolphin (Lipotesvexillifer).

    Science.gov (United States)

    Song, Zhongchang; Zhang, Yu; Wei, Chong; Wang, Xianyan

    2016-01-01

    Through numerically solving the appropriate wave equations, propagation of biosonar signals in a Chinese river dolphin (baiji) was studied. The interfacial waves along the rostrum-tissue interfaces, including both compressional (longitudinal) and shear (transverse) waves in the solid rostrum through fluid-solid coupling were examined. The baiji's rostrum was found to effect acoustic beam formation not only as an interfacial wave generator but also as a sound reflector. The wave propagation patterns in the solid rostrum were found to significantly change the wave movement through the bone. Vibrations in the rostrum, expressed in solid displacement, initially increased but eventually decreased from posterior to anterior sides, indicating a complex physical process. Furthermore, the comparisons among seven cases, including the combination of (1) the rostrum, melon, and air sacs; (2) rostrum-air sacs; (3) rostrum-melon; (4) only rostrum; (5) air sacs-melon; (6) only air sacs; and (7) only melon revealed that the cases including the rostrum were better able to approach the complete system by inducing rostrum-tissue interfacial waves and reducing the differences in main beam angle and -3 dB beam width. The interfacial waves in the rostrum were considered complementary with reflection to determine the obbligato role of the rostrum in the baiji's biosonar emission. The far-field beams formed from complete fluid-solid models and non-fluid-solid models were compared to reveal the effects brought by the consideration of shear waves of the solid structures of the baiji. The results may provide useful information for further understanding the role of the rostrum in this odontocete species.

  14. Enhanced Chondrocyte Proliferation in a Prototyped Culture System with Wave-Induced Agitation

    Directory of Open Access Journals (Sweden)

    Pilarek Maciej

    2017-06-01

    Full Text Available One of the actual challenges in tissue engineering applications is to efficiently produce as high of number of cells as it is only possible, in the shortest time. In static cultures, the production of animal cell biomass in integrated forms (i.e. aggregates, inoculated scaffolds is limited due to inefficient diffusion of culture medium components observed in such non-mixed culture systems, especially in the case of cell-inoculated fiber-based dense 3D scaffolds, inside which the intensification of mass transfer is particularly important. The applicability of a prototyped, small-scale, continuously wave-induced agitated system for intensification of anchorage-dependent CP5 chondrocytes proliferation outside and inside three-dimensional poly(lactic acid (PLA scaffolds has been discussed. Fibrous PLA-based constructs have been inoculated with CP5 cells and then maintained in two independent incubation systems: (i non-agitated conditions and (ii culture with wave-induced agitation. Significantly higher values of the volumetric glucose consumption rate have been noted for the system with the wave-induced agitation. The advantage of the presented wave-induced agitation culture system has been confirmed by lower activity of lactate dehydrogenase (LDH released from the cells in the samples of culture medium harvested from the agitated cultures, in contrast to rather high values of LDH activity measured for static conditions. Results of the proceeded experiments and their analysis clearly exhibited the feasibility of the culture system supported with continuously wave-induced agitation for robust proliferation of the CP5 chondrocytes on PLA-based structures. Aside from the practicability of the prototyped system, we believe that it could also be applied as a standard method offering advantages for all types of the daily routine laboratory-scale animal cell cultures utilizing various fiber-based biomaterials, with the use of only regular laboratory

  15. Numerical simulation of travelling wave induced electrothermal fluid flow

    International Nuclear Information System (INIS)

    Perch-Nielsen, Ivan R; Green, Nicolas G; Wolff, Anders

    2004-01-01

    Many microdevices for manipulating particles and cells use electric fields to produce a motive force on the particles. The movement of particles in non-uniform electric fields is called dielectrophoresis, and the usual method of applying this effect is to pass the particle suspension over a microelectrode structure. If the suspension has a noticeable conductivity, one important side effect is that the electric field drives a substantial conduction current through the fluid, causing localized Joule-heating. The resulting thermal gradient produces local conductivity and permittivity changes in the fluid. Dielectrophoretic forces acting upon these pockets of fluid will then produce motion of both the fluid and the particles. This paper presents a numerical solution of the electrical force and the resulting electrothermal driven fluid flow on a travelling wave structure. This common electrode geometry consists of interdigitated electrodes laid down in a long array, with the phase of the applied potential shifted by 90 0 on each subsequent electrode. The resulting travelling electric field was simulated and the thermal field and electrical body force on the fluid calculated, for devices constructed from two typical materials: silicon and glass. The electrothermal fluid flow in the electrolyte over the electrode array was then numerically simulated. The model predicts that the thermal field depends on the conductivity and applied voltage, but more importantly on the geometry of the system and the material used in the construction of the device. The velocity of the fluid flow depends critically on the same parameters, with slight differences in the thermal field for glass and silicon leading to diametrically opposite flow direction with respect to the travelling field for the two materials. In addition, the imposition of slight external temperature gradients is shown to have a large effect on the fluid flow in the device, under certain conditions leading to a reversal of

  16. Wave

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo

    2008-01-01

    Estimates for the amount of potential wave energy in the world range from 1-10 TW. The World Energy Council estimates that a potential 2TW of energy is available from the world’s oceans, which is the equivalent of twice the world’s electricity production. Whilst the recoverable resource is many...... times smaller it remains very high. For example, whilst there is enough potential wave power off the UK to supply the electricity demands several times over, the economically recoverable resource for the UK is estimated at 25% of current demand; a lot less, but a very substantial amount nonetheless....

  17. Tunable plasmon-induced absorption effects in a graphene-based waveguide coupled with graphene ring resonators

    Science.gov (United States)

    Huang, Pei-Nian; Xia, Sheng-Xuan; Fu, Guang-Lai; Liang, Mei-Zhen; Qin, Meng; Zhai, Xiang; Wang, Ling-Ling

    2018-03-01

    In this paper, we propose a structure composed of two graphene waveguides and dual coupled graphene ring resonators (GRRs) to achieve a plasmon-induced absorption (PIA) effect. A three-level plasmonic system and a temporal coupled mode theory (CMT) are utilized to verify the simulation results. Moreover, a double-window-PIA effect can be conveniently attained by introducing another GRR with proper parameters to meet more specific acquirement in optical modulation process. The pronounced PIA resonances can be tuned in a number of ways, such as by adjusting the coupling distance between the GRRs and the couplings between the GRR and the waveguide, and tuning the radius and the Fermi energy of the GRRs. Besides, the produced PIA effect shows a high group delay up to - 1 . 87 ps, exhibiting a particularly prominent fast-light feature. Our results have potential applications in the realization of THz-integrated spectral control and graphene plasmonic devices such as sensors, filters, ultra-fast optical switches and so on.

  18. Transport of ions in presence of induced electric field and electrostatic turbulence - Source of ions injected into ring current

    Science.gov (United States)

    Cladis, J. B.; Francis, W. E.

    1985-01-01

    The transport of ions from the polar ionosphere to the inner magnetosphere during stormtime conditions has been computed using a Monte Carlo diffusion code. The effect of the electrostatic turbulence assumed to be present during the substorm expansion phase was simulated by a process that accelerated the ions stochastically perpendicular to the magnetic field with a diffusion coefficient proportional to the energization rate of the ions by the induced electric field. This diffusion process was continued as the ions were convected from the plasma sheet boundary layer to the double-spiral injection boundary. Inward of the injection boundary, the ions were convected adiabatically. By using as input an O(+) flux of 2.8 x 10 to the 8th per sq cm per s (w greater than 10 eV) and an H(+) flux of 5.5 x 10 to the 8th per sq cm per s (w greater than 0.63 eV), the computed distribution functions of the ions in the ring current were found to be in good agreement, over a wide range in L (4 to 8), with measurements made with the ISEE-1 satellite during a storm. This O(+) flux and a large part of the H(+) flux are consistent with the DE satellite measurements of the polar ionospheric outflow during disturbed times.

  19. Spin-orbit coupling and applied magnetic field effects on electromagnetically induced transparency of a quantum ring at finite temperature

    Science.gov (United States)

    Zamani, A.; Setareh, F.; Azargoshasb, T.; Niknam, E.

    2018-03-01

    A wide variety of semiconductor nanostructures have been fabricated and studied experimentally and alongside theoretical investigations show the great role they have in new generation opto-electronic devices. However, mathematical modeling provide important information due to their definitive goal of predicting features and understanding of such structures' behavior under different circumstances. Hence, in the current work, the effects of applied magnetic field, temperature and dimensions of the structure on the electromagnetically induced transparency (EIT) of a GaAs quantum ring are studied while both Rashba and Dresselhaus spin-orbit interactions (SOI) are taken into account. The Schrödinger equation is solved in cylindrical coordinate with axial symmetry and in order to study the EIT, the imaginary (absorption) and real (refractive index) parts of susceptibility as well as the group velocity of the probe light pulse are investigated. The absorption and refractive index plots show that, for a specific frequency of probe field the absorption vanishes and refractive index becomes unity (known as EIT) while around such frequency the group index is positive (sub-luminal probe propagation) and for higher and lower frequencies it alters to negative (super-luminal probe propagation). The numerical results reveal that the EIT frequency, transparency window and sub(super)-luminal frequency intervals shift as we change applied magnetic field, temperature and also the structure dimensions.

  20. Characteristics of laser-induced shock wave injury to the inner ear of rats

    Science.gov (United States)

    Kurioka, Takaomi; Matsunobu, Takeshi; Niwa, Katsuki; Tamura, Atsushi; Kawauchi, Satoko; Satoh, Yasushi; Sato, Shunichi; Shiotani, Akihiro

    2014-12-01

    Recently, the number of blast injuries of the inner ear has increased in the general population. In blast-induced inner ear injury, a shock wave (SW) component in the blast wave is considered to play an important role in sensorineural hearing loss. However, the mechanisms by which an SW affects inner ear tissue remain largely unknown. We aimed to establish a new animal model for SW-induced inner ear injury by using laser-induced SWs (LISWs) on rats. The LISWs were generated by irradiating an elastic laser target with 694-nm nanosecond pulses of a ruby laser. After LISW application to the cochlea through bone conduction, auditory measurements revealed the presence of inner ear dysfunction, the extent of which depended on LISW overpressure. A significantly lower survival rate of hair cells and spiral ganglion neurons, as well as severe oxidative damage, were observed in the inner ear exposed to an LISW. Although considerable differences in the pressure characteristics exist between LISWs and SWs in real blast waves, the functional and morphological changes shown by the present LISW-based model were similar to those observed in real blast-induced injury. Thus, our animal model is expected to be useful for laboratory-based research of blast-induced inner ear injury.

  1. Characteristics of laser-induced shock wave injury to the inner ear of rats.

    Science.gov (United States)

    Kurioka, Takaomi; Matsunobu, Takeshi; Niwa, Katsuki; Tamura, Atsushi; Kawauchi, Satoko; Satoh, Yasushi; Sato, Shunichi; Shiotani, Akihiro

    2014-12-01

    Recently, the number of blast injuries of the inner ear has increased in the general population. In blast-induced inner ear injury, a shock wave (SW) component in the blast wave is considered to play an important role in sensorineural hearing loss. However, the mechanisms by which an SW affects inner ear tissue remain largely unknown. We aimed to establish a new animal model for SW-induced inner ear injury by using laser-induced SWs (LISWs) on rats. The LISWs were generated by irradiating an elastic laser target with 694-nm nanosecond pulses of a ruby laser. After LISW application to the cochlea through bone conduction, auditory measurements revealed the presence of inner ear dysfunction, the extent of which depended on LISW overpressure. A significantly lower survival rate of hair cells and spiral ganglion neurons, as well as severe oxidative damage, were observed in the inner ear exposed to an LISW. Although considerable differences in the pressure characteristics exist between LISWs and SWs in real blast waves, the functional and morphological changes shown by the present LISW-based model were similar to those observed in real blast-induced injury. Thus, our animal model is expected to be useful for laboratory-based research of blast-induced inner ear injury.

  2. Confinement effects of shock waves on laser-induced plasma from a graphite target

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Feiling; Liang, Peipei; Yang, Xu; Cai, Hua; Wu, Jiada; Xu, Ning; Ying, Zhifeng; Sun, Jian, E-mail: jsun@fudan.edu.cn [Shanghai Ultra-Precision Optical Manufacturing Engineering Center, Department of Optical Science and Engineering, Fudan University, Shanghai 200433 (China)

    2015-06-15

    The spatial confinement effects of shock waves on the laser-induced plasma (LIP) from a graphite target in air were studied by probe beam deflection (PBD) measurements and optical emission spectroscopy (OES). A clear relationship between the confinement of the LIP by the shock wave and the effects on the LIP emission was observed, and the underlying mechanisms are discussed. PBD monitoring revealed that the laser-ablation induced shock wave could be well analogized to the shock wave generated by a point explosion and would be reflected by a block. OES measurements indicated that the optical emission of the LIP exhibited significant variations with the block placement. A first enhancement and then a fast decay of CN molecular emission as well as a suppression of carbon atomic emission were observed in the presence of the block. The results revealed that the reflected shock wave spatially confined the expansion of the LIP and compressed the LIP after encountering it, pushing back the species of the LIP and changing the density of the LIP species including luminous carbon atoms and CN molecules. It is suggested that the change of the LIP emission is attributed to the density variation of the LIP species due to the compression of the LIP and the reactions occurring in the plasma.

  3. On the Detectability of Acoustic Waves Induced Following Irradiation by a Radiotherapy Linear Accelerator.

    Science.gov (United States)

    Hickling, Susannah; Leger, Pierre; El Naqa, Issam

    2016-02-11

    Irradiating an object with a megavoltage photon beam generated by a clinical radiotherapy linear accelerator (linac) induces acoustic waves through the photoacoustic effect. The detection and characterization of such acoustic waves has potential applications in radiation therapy dosimetry. The purpose of this work was to gain insight into the properties of such acoustic waves by simulating and experimentally detecting them in a well-defined system consisting of a metal block suspended in a water tank. A novel simulation workflow was developed by combining radiotherapy Monte Carlo and acoustic wave transport simulation techniques. Different set-up parameters such as photon beam energy, metal block depth, metal block width, and metal block material were varied, and the simulated and experimental acoustic waveforms showed the same relative amplitude trends and frequency variations for such setup changes. The simulation platform developed in this work can easily be extended to other irradiation situations, and will be an invaluable tool for developing a radiotherapy dosimetry system based on the detection of the acoustic waves induced following linear accelerator irradiation.

  4. Three-dimensional wave-induced current model equations and radiation stresses

    Science.gov (United States)

    Xia, Hua-yong

    2017-08-01

    After the approach by Mellor (2003, 2008), the present paper reports on a repeated effort to derive the equations for three-dimensional wave-induced current. Via the vertical momentum equation and a proper coordinate transformation, the phase-averaged wave dynamic pressure is well treated, and a continuous and depth-dependent radiation stress tensor, rather than the controversial delta Dirac function at the surface shown in Mellor (2008), is provided. Besides, a phase-averaged vertical momentum flux over a sloping bottom is introduced. All the inconsistencies in Mellor (2003, 2008), pointed out by Ardhuin et al. (2008) and Bennis and Ardhuin (2011), are overcome in the presently revised equations. In a test case with a sloping sea bed, as shown in Ardhuin et al. (2008), the wave-driving forces derived in the present equations are in good balance, and no spurious vertical circulation occurs outside the surf zone, indicating that Airy's wave theory and the approach of Mellor (2003, 2008) are applicable for the derivation of the wave-induced current model.

  5. Surface solitons of four-wave mixing in an electromagnetically induced lattice

    International Nuclear Information System (INIS)

    Zhang, Yanpeng; Yuan, Chenzhi; Zhang, Yiqi; Zheng, Huaibin; Chen, Haixia; Li, Changbiao; Wang, Zhiguo; Xiao, Min

    2013-01-01

    By creating lattice states with two-dimensional spatial periodic atomic coherence, we report an experimental demonstration of generating two-dimensional surface solitons of a four-wave mixing signal in an electromagnetically induced lattice composed of two electromagnetically induced gratings with different orientations in an atomic medium, each of which can support a one-dimensional surface soliton. The surface solitons can be well controlled by different experimental parameters, such as probe frequency, pump power, and beam incident angles, and can be affected by coherent induced defect states. (letter)

  6. Forced wave induced by an atmospheric pressure disturbance moving towards shore

    Science.gov (United States)

    Chen, Yixiang; Niu, Xiaojing

    2018-05-01

    Atmospheric pressure disturbances moving over a vast expanse of water can induce different wave patterns, which can be determined by the Froude number Fr. Generally, Fr = 1 is a critical value for the transformation of the wave pattern and the well-known Proudman resonance happens when Fr = 1. In this study, the forced wave induced by an atmospheric pressure disturbance moving over a constant slope from deep sea to shore is numerically investigated. The wave pattern evolves from a concentric-circle type into a triangular type with the increase of the Froude number, as the local water depth decreases, which is in accord with the analysis in the unbounded flat-bottom cases. However, a hysteresis effect has been observed, which implies the obvious amplification of the forced wave induced by a pressure disturbance can not be simply predicted by Fr = 1. The effects of the characteristic parameters of pressure disturbances and slope gradient have been discussed. The results show that it is not always possible to observe significant peak of the maximum water elevation before the landing of pressure disturbances, and a significant peak can be generated by a pressure disturbance with small spatial scale and fast moving velocity over a milder slope. Besides, an extremely high run-up occurs when the forced wave hits the shore, which is an essential threat to coastal security. The results also show that the maximum run-up is not monotonously varying with the increase of disturbance moving speed and spatial scale. There exists a most dangerous speed and scale which may cause disastrous nearshore surge.

  7. Study on THz wave generation from air plasma induced by quasi-square Airy beam

    Science.gov (United States)

    Zhang, Shijing; Zhang, Liangliang; Jiang, Guangtong; Zhang, Cunlin; Zhao, Yuejin

    2018-01-01

    Terahertz (THz) wave has attracted considerable attention in recent years because of its potential applications. The intense THz waves generated from air plasma induced by two-color femtosecond laser are widely used due to its high generation efficiency and broad frequency bandwidth. The parameters of the laser change the distribution of the air plasma, and then affect the generation of THz wave. In this research, we investigate the THz wave generation from air plasma induced by quasi-square Airy beam. Unlike the common Gauss beam, the quasi-square Airy beam has ability to autofocus and to increase the maximum intensity at the focus. By using the spatial light modulator (SLM), we can change the parameters of phase map to control the shape of the Airy beam. We obtain the two-color laser field by a 100-um-thick BBO crystal, then use a Golay detector to record THz wave energy. By comparing terahertz generation at different modulation depths, we find that terahertz energy produced by quasi-square Airy beam is up to 3.1 times stronger than that of Gauss beam with identical laser energy. In order to understand the influence of quasi-square Airy beam on the BBO crystal, we record THz wave energy by changing the azimuthal angle of BBO crystal with Gauss beam and Airy beam at different modulation depths. We find that the trend of terahertz energy with respect to the azimuthal angle of the BBO crystal keeps the same for different laser beams. We believe that the quasi-square Airy beam or other auto focusing beam can significantly improve the efficiency of terahertz wave generation and pave the way for its applications.

  8. Mechanically induced intracellular calcium waves in osteoblasts demonstrate calcium fingerprints in bone cell mechanotransduction.

    Science.gov (United States)

    Godin, Lindsay M; Suzuki, Sakiko; Jacobs, Christopher R; Donahue, Henry J; Donahue, Seth W

    2007-11-01

    An early response to mechanical stimulation of bone cells in vitro is an increase in intracellular calcium concentration ([Ca (2+)](i)). This study analyzed the [Ca (2+)](i) wave area, magnitude, duration, rise time, fall time, and time to onset in individual osteoblasts for two identical bouts of mechanical stimulation separated by a 30-min rest period. The area under the [Ca (2+)](i) wave increased in the second loading bout compared to the first. This suggests that rest periods may potentiate mechanically induced intracellular calcium signals. Furthermore, many of the [Ca (2+)](i) wave parameters were strongly, positively correlated between the two bouts of mechanical stimulation. For example, in individual primary osteoblasts, if a cell had a large [Ca (2+)](i) wave area in the first bout it was likely to have a large [Ca (2+)](i) wave area in the second bout (r (2) = 0.933). These findings support the idea that individual bone cells have "calcium fingerprints" (i.e., a unique [Ca (2+)](i) wave profile that is reproducible for repeated exposure to a given stimulus).

  9. Rogue waves and W-shaped solitons in the multiple self-induced transparency system.

    Science.gov (United States)

    Wang, Xin; Liu, Chong; Wang, Lei

    2017-09-01

    We study localized nonlinear waves on a plane wave background in the multiple self-induced transparency (SIT) system, which describes an important enhancement of the amplification and control of optical waves compared to the single SIT system. A hierarchy of exact multiparametric rational solutions in a compact determinant representation is presented. We demonstrate that this family of solutions contain known rogue wave solutions and unusual W-shaped soliton solutions. State transitions between the fundamental rogue waves and W-shaped solitons as well as higher-order nonlinear superposition modes are revealed in the zero-frequency perturbation region by the suitable choice for the background wavenumber of the electric field component. Particularly, it is found that the multiple SIT system can admit both stationary and nonstationary W-shaped solitons in contrast to the stationary results in the single SIT system. Moreover, the W-shaped soliton complex which is formed by a certain number of fundamental W-shaped solitons with zero phase parameters and its decomposition mechanism in the case of the nonzero phase parameters are shown. Meanwhile, some important characteristics of the nonlinear waves including trajectories and spectrum are discussed through the numerical and analytical methods.

  10. Shifts and widths of p-wave confinement induced resonances in atomic waveguides

    International Nuclear Information System (INIS)

    Saeidian, Shahpoor; Melezhik, Vladimir S; Schmelcher, Peter

    2015-01-01

    We develop and analyze a theoretical model to study p-wave Feshbach resonances of identical fermions in atomic waveguides by extending the two-channel model of Lange et al (2009 Phys. Rev. A 79 013622) and Saeidian et al (2012 Phys. Rev. A 86 062713). The experimentally known parameters of Feshbach resonances in free space are used as input of the model. We calculate the shifts and widths of p-wave magnetic Feshbach resonance of 40 K atoms emerging in harmonic waveguides as p-wave confinement induced resonance (CIR). Particularly, we show a possibility to control the width and shift of the p-wave CIR by the trap frequency and the applied magnetic field which could be used in corresponding experiments. Our analysis also demonstrates the importance of the inclusion of the effective range in the computational schemes for the description of the p-wave CIRs contrary to the case of s-wave CIRs where the influence of this term is negligible. (paper)

  11. Ionospheric Bow Waves and Perturbations Induced by the 21 August 2017 Solar Eclipse

    Science.gov (United States)

    Zhang, Shun-Rong; Erickson, Philip J.; Goncharenko, Larisa P.; Coster, Anthea J.; Rideout, William; Vierinen, Juha

    2017-12-01

    During solar eclipses, the Moon's shadow causes a large reduction in atmospheric energy input, including not only the stratosphere but also the thermosphere and ionosphere. The eclipse shadow has a supersonic motion which is theoretically expected to generate atmospheric bow waves, similar to a fast-moving river boat, with waves starting in the lower atmosphere and propagating into the ionosphere. However, previous geographically limited observations have had difficulty detecting these weak waves within the natural background atmospheric variability, and the existence of eclipse-induced ionospheric waves and their evolution in a complex coupling system remain controversial. During the 21 August 2017 eclipse, high fidelity and wide coverage ionospheric observations provided for the first time an oversampled set of eclipse data, using a dense network of Global Navigation Satellite System receivers at ˜2,000 sites in North America. We show the first unambiguous evidence of ionospheric bow waves as electron content disturbances over central/eastern United States, with ˜1 h duration, 300-400 km wavelength and 280 m/s phase speed emanating from and tailing the totality region. We also identify large ionospheric perturbations moving at the supersonic speed of the maximum solar obscuration which are too fast to be associated with known gravity wave or large-scale traveling ionospheric disturbance processes. This study reveals complex interconnections between the Sun, Moon, and Earth's neutral atmosphere and ionosphere and demonstrates persistent coupling processes between different components of the Earth's atmosphere, a topic of significant community interest.

  12. Birefringence induced by pp-wave modes in an electromagnetically active dynamic aether

    International Nuclear Information System (INIS)

    Alpin, Timur Yu.; Balakin, Alexander B.

    2017-01-01

    In the framework of the Einstein-Maxwell-aether theory we study the birefringence effect, which can occur in the pp-wave symmetric dynamic aether. The dynamic aether is considered to be a latently birefringent quasi-medium, which displays this hidden property if and only if the aether motion is non-uniform, i.e., when the aether flow is characterized by the non-vanishing expansion, shear, vorticity or acceleration. In accordance with the dynamo-optical scheme of description of the interaction between electromagnetic waves and the dynamic aether, we shall model the susceptibility tensors by the terms linear in the covariant derivative of the aether velocity four-vector. When the pp-wave modes appear in the dynamic aether, we deal with a gravitationally induced degeneracy removal with respect to hidden susceptibility parameters. As a consequence, the phase velocities of electromagnetic waves possessing orthogonal polarizations do not coincide, thus displaying the birefringence effect. Two electromagnetic field configurations are studied in detail: longitudinal and transversal with respect to the aether pp-wave front. For both cases the solutions are found, which reveal anomalies in the electromagnetic response on the action of the pp-wave aether mode. (orig.)

  13. Birefringence induced by pp-wave modes in an electromagnetically active dynamic aether

    Energy Technology Data Exchange (ETDEWEB)

    Alpin, Timur Yu.; Balakin, Alexander B. [Kazan Federal University, Department of General Relativity and Gravitation, Institute of Physics, Kazan (Russian Federation)

    2017-10-15

    In the framework of the Einstein-Maxwell-aether theory we study the birefringence effect, which can occur in the pp-wave symmetric dynamic aether. The dynamic aether is considered to be a latently birefringent quasi-medium, which displays this hidden property if and only if the aether motion is non-uniform, i.e., when the aether flow is characterized by the non-vanishing expansion, shear, vorticity or acceleration. In accordance with the dynamo-optical scheme of description of the interaction between electromagnetic waves and the dynamic aether, we shall model the susceptibility tensors by the terms linear in the covariant derivative of the aether velocity four-vector. When the pp-wave modes appear in the dynamic aether, we deal with a gravitationally induced degeneracy removal with respect to hidden susceptibility parameters. As a consequence, the phase velocities of electromagnetic waves possessing orthogonal polarizations do not coincide, thus displaying the birefringence effect. Two electromagnetic field configurations are studied in detail: longitudinal and transversal with respect to the aether pp-wave front. For both cases the solutions are found, which reveal anomalies in the electromagnetic response on the action of the pp-wave aether mode. (orig.)

  14. Striped morphologies induced by magnetic impurities in d-wave superconductors

    International Nuclear Information System (INIS)

    Zuo Xianjun

    2011-01-01

    Research Highlights: → We investigate striped morphologies induced by magnetic impurities in d-wave superconductors (DSCs). → For the single-impurity and two-impurity cases, modulated checkerboard pattern and stripe-like structures are induced. → When more magnetic impurities are inserted, more complex modulated structures could be induced, including rectilinear and right-angled stripes and quantum-corral-like structures. → Impurities could induce complex striped morphologies in DSCs. - Abstract: We study striped morphologies induced by magnetic impurities in d-wave superconductors (DSCs) near optimal doping by self-consistently solving the Bogoliubov-de Gennes equations based on the t - t' - U - V model. For the single-impurity case, it is found that the stable ground state is a modulated checkerboard pattern. For the two-impurity case, the stripe-like structures in order parameters are induced due to the impurity-pinning effect. The modulations of DSC and charge orders share the same period of four lattice constants (4a), which is half the period of modulations in the coexisting spin order. Interestingly, when three or more impurities are inserted, the impurities could induce more complex striped morphologies due to quantum interference. Further experiments of magnetic impurity substitution in DSCs are expected to check these results.

  15. Numerical study of laser-induced blast wave coupled with unsteady ionization processes

    International Nuclear Information System (INIS)

    Ogino, Y; Ohnishi, N; Sawada, K

    2008-01-01

    We present the results of the numerical simulation of laser-induced blast wave coupled with rate equations to clarify the unsteady property of ionization processes during pulse heating. From comparison with quasi-steady computations, the plasma region expands more widely, which is sustained by the inverse-bremsstrahlung since an ionization equilibrium does not establish at the front of the plasma region. The delayed relaxation leads to the rapid expansion of the driving plasma and enhances the energy conversion efficiency from a pulse heating laser to the blast wave

  16. Parametrically tunable soliton-induced resonant radiation by three-wave mixing

    DEFF Research Database (Denmark)

    Zhou, Binbin; Liu, Xing; Guo, Hairun

    2017-01-01

    We show that a temporal soliton can induce resonant radiation by three-wave mixing nonlinearities. This constitutes a new class of resonant radiation whose spectral positions are parametrically tunable. The experimental verification is done in a periodically poled lithium niobate crystal, where...... a femtosecond near-IR soliton is excited and resonant radiation waves are observed exactly at the calculated soliton phasematching wavelengths via the sum- and difference-frequency generation nonlinearities. This extends the supercontinuum bandwidth well into the mid IR to span 550–5000 nm, and the mid-IR edge...

  17. S-wave kaon-nucleon phase shifts with instanton induced effects

    International Nuclear Information System (INIS)

    Lemaire, S.; Labarsouque, J.; Silvestre-Brac, B.

    2003-01-01

    The kaon-nucleon S-wave phase shifts have been calculated, for both isospin channels I=0 and I=1, in the framework of a semirelativistic quark potential model which includes an instanton induced force. The agreement with experimental phase shifts is poor essentially because of a dominant attraction coming from instantons. The low-energy behaviour of S-wave phase shifts, for I=0 and I=1 channels, obtained in the kaon-nucleon system is characteristic of a potential which can produce one loosely bound state

  18. S-wave kaon-nucleon phase shifts with instanton induced effects

    Energy Technology Data Exchange (ETDEWEB)

    Lemaire, S. E-mail: lemaire@cenbg.in2p3.fr; Labarsouque, J.; Silvestre-Brac, B

    2003-09-22

    The kaon-nucleon S-wave phase shifts have been calculated, for both isospin channels I=0 and I=1, in the framework of a semirelativistic quark potential model which includes an instanton induced force. The agreement with experimental phase shifts is poor essentially because of a dominant attraction coming from instantons. The low-energy behaviour of S-wave phase shifts, for I=0 and I=1 channels, obtained in the kaon-nucleon system is characteristic of a potential which can produce one loosely bound state.

  19. Phase separation and d-wave superconductivity induced by extended electron-exciton interaction

    Energy Technology Data Exchange (ETDEWEB)

    Cheng Ming [Department of Physics and Texas Center for Superconductivity, University of Houston, 4800 Calhoun Road, Houston, Texas 77204 (United States)], E-mail: cheng896@hotmail.com; Su Wupei [Department of Physics and Texas Center for Superconductivity, University of Houston, 4800 Calhoun Road, Houston, Texas 77204 (United States)

    2008-12-15

    Using an auxiliary-field quantum Monte Carlo (AFQMC) method, we have studied a two-dimensional tight-binding model in which the conduction electrons can polarize an adjacent layer of molecules through electron-electron repulsion. Calculated average conduction electron density as a function of chemical potential exhibits a clear break characteristic of phase separation. Compared to the noninteracting system, the d-wave pair-field correlation function shows significant enhancement. The simultaneous presence of phase separation and d-wave superconductivity suggests that an effective extended pairing force is induced by the electron-exciton coupling.

  20. Phase separation and d-wave superconductivity induced by extended electron-exciton interaction

    International Nuclear Information System (INIS)

    Cheng Ming; Su Wupei

    2008-01-01

    Using an auxiliary-field quantum Monte Carlo (AFQMC) method, we have studied a two-dimensional tight-binding model in which the conduction electrons can polarize an adjacent layer of molecules through electron-electron repulsion. Calculated average conduction electron density as a function of chemical potential exhibits a clear break characteristic of phase separation. Compared to the noninteracting system, the d-wave pair-field correlation function shows significant enhancement. The simultaneous presence of phase separation and d-wave superconductivity suggests that an effective extended pairing force is induced by the electron-exciton coupling

  1. Wave-induced mass transport affects daily Escherichia coli fluctuations in nearshore water

    Science.gov (United States)

    Ge, Zhongfu; Whitman, Richard L.; Nevers, Meredith B.; Phanikumar, Mantha S.

    2012-01-01

    Characterization of diel variability of fecal indicator bacteria concentration in nearshore waters is of particular importance for development of water sampling standards and protection of public health. Significant nighttime increase in Escherichia coli (E. coli) concentration in beach water, previously observed at marine sites, has also been identified in summer 2000 from fixed locations in waist- and knee-deep waters at Chicago 63rd Street Beach, an embayed, tideless, freshwater beach with low currents at night (approximately 0.015 m s–1). A theoretical model using wave-induced mass transport velocity for advection was developed to assess the contribution of surface waves to the observed nighttime E. coli replenishment in the nearshore water. Using average wave conditions for the summer season of year 2000, the model predicted an amount of E. coli transported from water of intermediate depth, where sediment resuspension occurred intermittently, that would be sufficient to have elevated E. coli concentration in the surf and swash zones as observed. The nighttime replenishment of E. coli in the surf and swash zones revealed here is an important phase in the cycle of diel variations of E. coli concentration in nearshore water. According to previous findings in Ge et al. (Environ. Sci. Technol. 2010, 44, 6731–6737), enhanced current circulation in the embayment during the day tends to displace and deposit material offshore, which partially sets up the system by the early evening for a new period of nighttime onshore movement. This wave-induced mass transport effect, although facilitating a significant base supply of material shoreward, can be perturbed or significantly influenced by high currents (orders of magnitude larger than a typical wave-induced mass transport velocity), current-induced turbulence, and tidal forcing.

  2. Acoustic cavitation bubbles in the kidney induced by focused shock waves in extracorporeal shock wave lithotripsy (ESWL)

    Science.gov (United States)

    Kuwahara, M.; Ioritani, N.; Kambe, K.; Taguchi, K.; Saito, T.; Igarashi, M.; Shirai, S.; Orikasa, S.; Takayama, K.

    1990-07-01

    On an ultrasonic imaging system a hyperechoic region was observed in a focal area of fucused shock waves in the dog kidney. This study was performed to learn whether cavitation bubbles are responsible for this hyperechoic region. The ultrasonic images in water of varying temperatures were not markedly different. In the flowing stream of distilled water, the stream was demonstrated as a hyperechoic region only with a mixture of air bubbles. Streams of 5%-50% glucose solutions were also demonstrated as a hyperechoic region. However, such concentration changes in living tissue, as well as thermal changes, are hardly thought to be induced. The holographic interferometry showed that the cavitation bubbles remained for more than 500 msec. in the focal area in water. This finding indicate that the bubble can remain for longer period than previously supposed. These results support the contentions that cavitation bubbles are responsible for the hyperechoic region in the kidney in situ.

  3. Operational wave now- and forecast in the German Bight as a basis for the assessment of wave-induced hydrodynamic loads on coastal dikes

    Science.gov (United States)

    Dreier, Norman; Fröhle, Peter

    2017-12-01

    The knowledge of the wave-induced hydrodynamic loads on coastal dikes including their temporal and spatial resolution on the dike in combination with actual water levels is of crucial importance of any risk-based early warning system. As a basis for the assessment of the wave-induced hydrodynamic loads, an operational wave now- and forecast system is set up that consists of i) available field measurements from the federal and local authorities and ii) data from numerical simulation of waves in the German Bight using the SWAN wave model. In this study, results of the hindcast of deep water wave conditions during the winter storm on 5-6 December, 2013 (German name `Xaver') are shown and compared with available measurements. Moreover field measurements of wave run-up from the local authorities at a sea dike on the German North Sea Island of Pellworm are presented and compared against calculated wave run-up using the EurOtop (2016) approach.

  4. Nonlinear generation of the fundamental radiation in plasmas: the influence of induced ion-acoustic and Langmuir waves

    International Nuclear Information System (INIS)

    Rizzato, F.B.

    1992-01-01

    A nonlinear emission mechanism of electromagnetic waves at the fundamental plasma frequency has been examined. This mechanism is based on the electromagnetic oscillating two-stream instability driven by two oppositely propagating Langmuir waves. The excitation of the electromagnetic oscillating two-stream instability is due to nonlinear wave-wave coupling involving Langmuir waves, low-frequency density waves and electromagnetic waves. The Chian and Alves model is improved using the generalized Zakharov equations. Attention is directed toward the influence of induced low-frequency and Langmuir waves on the properties of the electromagnetic oscillating two-stream instability. Presumably, the properties derived in the present context may be relevant to both space and laboratory plasmas. (author)

  5. Observation of Atom Wave Phase Shifts Induced by Van Der Waals Atom-Surface Interactions

    International Nuclear Information System (INIS)

    Perreault, John D.; Cronin, Alexander D.

    2005-01-01

    The development of nanotechnology and atom optics relies on understanding how atoms behave and interact with their environment. Isolated atoms can exhibit wavelike (coherent) behavior with a corresponding de Broglie wavelength and phase which can be affected by nearby surfaces. Here an atom interferometer is used to measure the phase shift of Na atom waves induced by the walls of a 50 nm wide cavity. To our knowledge this is the first direct measurement of the de Broglie wave phase shift caused by atom-surface interactions. The magnitude of the phase shift is in agreement with that predicted by Lifshitz theory for a nonretarded van der Waals interaction. This experiment also demonstrates that atom waves can retain their coherence even when atom-surface distances are as small as 10 nm

  6. EEG slow-wave coherence changes in propofol-induced general anesthesia: Experiment and theory

    Directory of Open Access Journals (Sweden)

    Kaier eWang

    2014-10-01

    Full Text Available The electroencephalogram (EEG patterns recorded during general anesthetic-induced coma are closely similar to those seen during slow-wave sleep, the deepest stage of natural sleep; both states show patterns dominated by large amplitude slow waves. Slow oscillations are believed to be important for memory consolidation during natural sleep. Tracking the emergence of slow-wave oscillations during transition to unconsciousness may help us to identify drug-induced alterations of the underlying brain state, and provide insight into the mechanisms of general anesthesia. Although cellular-based mechanisms have been proposed, the origin of the slow oscillation has not yet been unambiguously established. A recent theoretical study by Steyn-Ross et al. [Physical Review X 3(2, 021005 (2013] proposes that the slow oscillation is a network, rather than cellular phenomenon. Modeling anesthesia as a moderate reduction in gap-junction interneuronal coupling, they predict an unconscious state signposted by emergent low-frequency oscillations with chaotic dynamics in space and time. They suggest that anesthetic slow-waves arise from a competitive interaction between symmetry-breaking instabilities in space (Turing and time (Hopf, modulated by gap-junction coupling strength. A significant prediction of their model is that EEG phase coherence will decrease as the cortex transits from Turing--Hopf balance (wake to Hopf-dominated chaotic slow-waves (unconsciousness. Here, we investigate changes in phase coherence during induction of general anesthesia. After examining 128-channel EEG traces recorded from five volunteers undergoing propofol anesthesia, we report a significant drop in sub-delta band (0.05--1.5 Hz slow-wave coherence between frontal, occipital, and frontal-occipital electrode pairs, with the most pronounced wake-versus-unconscious coherence changes occurring at the frontal cortex.

  7. Structural and functional alterations in the atrioventricular node and atrioventricular ring tissue in ischaemia-induced heart failure.

    Science.gov (United States)

    Yanni, Joseph; Maczewski, Michal; Mackiewicz, Urszula; Siew, Samuel; Fedorenko, Olga; Atkinson, Andrew; Price, Marcus; Beresewicz, Andrzej; Anderson, Robert H; Boyett, Mark R; Dobrzynski, Halina

    2014-07-01

    Heart failure (HF) causes dysfunction of the atrioventricular node (AVN) - first or second-degree heart block is a risk factor for sudden cardiac death in HF patients. The aim of the study was to determine if HF causes remodelling of the AVN and right atrioventricular ring (RAVR). HF was induced in rats (n=4) by ligation of the proximal left coronary artery, which resulted in a large infarct of the left ventricle. Sham-operated rats (n=4) were used as controls. Eight weeks after surgery, functional experiments were performed and the hearts were frozen. The body weight of HF rats was similar to control rats, but the mean heart weight of HF rats was significantly enlarged. In HF rats compared to controls, the left ventricle was dilated, left ventricular end-diastolic pressure elevated (21.0 ± 0.6 and 5.4 ± 0.2 mm Hg), left ventricular ejection fraction reduced (0.2 ± 0.02 and 0.5 ± 0.02) and left ventricular end-systolic pressure reduced (102 ± 4.2 and 127 ± 3.1 mm Hg). In HF rats, the in vivo and in vitro PR intervals were increased (41% and 20%), as was the Wenckebach cycle length, indicative of AVN dysfunction. The collagen content was significantly increased in the AVN and RAVR indicating fibrosis. Immunolabelling of caveolin3 (cell membrane marker) showed that there was hypertrophy in HF (cell diameter was increased by 63%, 39% in AVN, RAVR). The TUNEL assay showed that the myocytes of the AVN and RAVR in HF undergo apoptotic cell death. Immunolabelling showed that expression of HCN4 was significantly decreased in the AVN and RAVR (43% and 47%) in HF. We conclude that in HF there is remodelling of the AVN and RAVR and this remodelling may explain the AVN dysfunction.

  8. Energy-imbalance mechanism of domain wall motion induced by propagation spin waves in finite magnetic nanostripe

    International Nuclear Information System (INIS)

    Zhu, Jinrong; Han, Zhaoyan; Su, Yuanchang; Hu, Jingguo

    2014-01-01

    The mechanism of the domain wall (DW) motions induced by spin wave in finite magnetic nanostripe is studied by micromagnetic simulations. We find that the spin-wave induced DM motions are always accompanied by an energy imbalance between two sides of the DW. The DW motion can be attributed to the expansion of the low-energy-density area and the contraction of the high-energy-density area. The energy imbalance strongly depends on whether the spin wave passes through the DW or is reflected by the DW. In the area of the spin wave propagation, the energy density increases with the time. However, in the superposition area of the incident spin wave and the reflected spin wave, the energy density decreases with the increasing of the time. It shows that this energy imbalance can be controlled by tuning the frequency of the spin wave. Finally, the effect of the damping parameter value is discussed. - Highlights: • The mechanism of the spin-wave induced DW motions is studied. • The spin-wave induced DW motions and the energy imbalance mechanism are given. • The DW motion with the same direction to that of SW is explained. • The DW motion with the opposite direction to that of SW is explained

  9. Development of laser-induced grating spectroscopy for underwater temperature measurement in shock wave focusing regions

    Science.gov (United States)

    Gojani, Ardian B.; Danehy, Paul M.; Alderfer, David W.; Saito, Tsutomu; Takayama, Kazuyoshi

    2004-02-01

    In Extracorporeal Shock Wave Lithotripsy (ESWL) underwater shock wave focusing generates high pressures at very short duration of time inside human body. However, it is not yet clear how high temperatures are enhanced at the spot where a shock wave is focused. The estimation of such dynamic temperature enhancements is critical for the evaluation of tissue damages upon shock loading. For this purpose in the Interdisciplinary Shock Wave Research Center a technique is developed which employs laser induced thermal acoustics or Laser Induced Grating Spectroscopy. Unlike most of gas-dynamic methods of measuring physical quantities this provides a non-invasive one having spatial and temporal resolutions of the order of magnitude of 1.0 mm 3 and 400 ns, respectively. Preliminary experiments in still water demonstrated that this method detected sound speed and hence temperature in water ranging 283 K to 333 K with errors of 0.5%. These results are used to empirically establish the equation of states of water, gelatin or agar cell which will work as alternatives of human tissues.

  10. Vortex-Induced Waves in Two-Phase Liquid-Liquid Flows past Bluff Body

    Science.gov (United States)

    Zainal Abidin, M. I. I.; Park, Kyeong H.; Angeli, Panagiota; Xie, Zhihua; Kahouadji, Lyes; Matar, Omar K.

    2017-11-01

    Transverse cylinders of various sizes are used to generate vortex-induced interfacial waves in two-phase oil-water flows and to influence flow pattern transitions. The vortex shedding properties at different cylinder sizes and the resulting induced waves are studied experimentally with Particle Image Velocimetry (PIV) and high-speed imaging. The system consists of a 7 m long horizontal 37 mm ID acrylic pipe and different cylinders with diameters of 2, 5 and 8 mm, located in the water phase, 460 mm after the two phases come into contact. The cylinder generates waves with frequencies similar to the von Karman vortices and changes in vortex shedding properties at different cylinder size are reflected on the resulting interfacial wave characteristics. The presence of the transverse cylinder actuates the transition from stratified to dispersed flows; the boundary between the two patterns is shifted to lower mixture velocity with increasing cylinder size. Three-dimensional numerical simulation of the system is developed to assist in designing new system. Project funded by EPSRC UK and Memphis Grant.

  11. Impact induced damage assessment by means of Lamb wave image processing

    Science.gov (United States)

    Kudela, Pawel; Radzienski, Maciej; Ostachowicz, Wieslaw

    2018-03-01

    The aim of this research is an analysis of full wavefield Lamb wave interaction with impact-induced damage at various impact energies in order to find out the limitation of the wavenumber adaptive image filtering method. In other words, the relation between impact energy and damage detectability will be shown. A numerical model based on the time domain spectral element method is used for modeling of Lamb wave propagation and interaction with barely visible impact damage in a carbon-epoxy laminate. Numerical studies are followed by experimental research on the same material with an impact damage induced by various energy and also a Teflon insert simulating delamination. Wavenumber adaptive image filtering and signal processing are used for damage visualization and assessment for both numerical and experimental full wavefield data. It is shown that it is possible to visualize and assess the impact damage location, size and to some extent severity by using the proposed technique.

  12. Sheared electric field-induced suppression of edge turbulence using externally driven R.F. waves

    International Nuclear Information System (INIS)

    Craddock, G.G.; Diamond, P.H.

    1991-01-01

    Here the authors propose a novel method for active control and suppression of edge turbulence by sheared ExB flows driven by externally launched RF waves. The theory developed addresses the problem of open-quotes flow driveclose quotes, which is somewhat analogous to the problem of plasma current drive. As originally demonstrated for the case of spontaneously driven flows, a net difference in the gradient of the fluid and magnetic Reynolds' stresses produced by radially propagating waves can drive the plasma flow. For the prototypical case of the Alfven wave flow drive considered here, ρ 0 r v θ > - r B θ > is proportional to k perpendicular 2 ρ s 2 in the case of the kinetic Alfven wave, and [(ηk perpendicular 2 -vk perpendicular 2 )/ω] 2 in the case of resistive MHD. Both results reflect the dependence of flow drive on the net stress imbalance. The shear layer width is determined by the waves evanescence length (determined by dissipation) that sets the stress gradient scale length, while the direction of the flow is determined by the poloidal orientation of the launched waves. In particular, it should be noted that both positive and negative E r may be driven, so that enhanced confinement need not be accompanied by impurity accumulation, as commonly encountered in spontaneous H-modes. The efficiency is determined by the criterion that the radial electric field shear be large enough to suppress turbulence. For typical TEXT parameters, and unity efficiency, 300 kW of absorbed power is needed to suppress turbulence over 3 cm radially. For DIII-D, 300 kW over 4 cm is needed. Also, direct transport losses induced by RF have been shown to be small. Extensions of the theory to ICRF are underway and are discussed. They also discuss the analogous problem of current drive using kinetic Alfven waves. 2 refs

  13. Delay-induced wave instabilities in single-species reaction-diffusion systems

    Science.gov (United States)

    Otto, Andereas; Wang, Jian; Radons, Günter

    2017-11-01

    The Turing (wave) instability is only possible in reaction-diffusion systems with more than one (two) components. Motivated by the fact that a time delay increases the dimension of a system, we investigate the presence of diffusion-driven instabilities in single-species reaction-diffusion systems with delay. The stability of arbitrary one-component systems with a single discrete delay, with distributed delay, or with a variable delay is systematically analyzed. We show that a wave instability can appear from an equilibrium of single-species reaction-diffusion systems with fluctuating or distributed delay, which is not possible in similar systems with constant discrete delay or without delay. More precisely, we show by basic analytic arguments and by numerical simulations that fast asymmetric delay fluctuations or asymmetrically distributed delays can lead to wave instabilities in these systems. Examples, for the resulting traveling waves are shown for a Fisher-KPP equation with distributed delay in the reaction term. In addition, we have studied diffusion-induced instabilities from homogeneous periodic orbits in the same systems with variable delay, where the homogeneous periodic orbits are attracting resonant periodic solutions of the system without diffusion, i.e., periodic orbits of the Hutchinson equation with time-varying delay. If diffusion is introduced, standing waves can emerge whose temporal period is equal to the period of the variable delay.

  14. Acoustic streaming induced by two orthogonal ultrasound standing waves in a microfluidic channel.

    Science.gov (United States)

    Doinikov, Alexander A; Thibault, Pierre; Marmottant, Philippe

    2018-07-01

    A mathematical model is derived for acoustic streaming in a microfluidic channel confined between a solid wall and a rigid reflector. Acoustic streaming is produced by two orthogonal ultrasound standing waves of the same frequency that are created by two pairs of counter-propagating leaky surface waves induced in the solid wall. The magnitudes and phases of the standing waves are assumed to be different. Full analytical solutions are found for the equations of acoustic streaming. The obtained solutions are used in numerical simulations to reveal the structure of the acoustic streaming. It is shown that the interaction of two standing waves leads to the appearance of a cross term in the equations of acoustic streaming. If the phase lag between the standing waves is nonzero, the cross term brings about circular vortices with rotation axes perpendicular to the solid wall of the channel. The vortices make fluid particles rotate and move alternately up and down between the solid wall and the reflector. The obtained results are of immediate interest for acoustomicrofluidic applications such as the ultrasonic micromixing of fluids and the manipulation of microparticles. Copyright © 2018 Elsevier B.V. All rights reserved.

  15. Contribution of wave-induced liquefaction in triggering hyperpycnal flows in Yellow River Estuary

    Science.gov (United States)

    Liu, X.; Jia, Y.

    2017-12-01

    Hyperpycnal flows, driven mainly by the gravity of near-bed negatively buoyant layers, are one of the most important processes for moving marine sediment across the earth. The issue of hyperpycnal flows existing in marine environment has drawn increasing scholars' attention since that was observed in situ off the Yellow River estuary in the 1980s. Most researches maintain that hyperpycnal flows in the Yellow River estuary are caused by the high-concentration sediments discharged from the Yellow River into sea, however, other mechanisms have been discounted since the sediment input from the river has been significantly changed due to climate and anthropogenic change. Here we demonstrate that wave-seabed interactions can generate hyperpycnal flows, without river input, by sediment flux convergence above an originally consolidated seabed. Using physical model experiments and multi-sensor field measurements, we characterize the composition-dependent liquefaction properties of the sediment due to wave-induced pore water pressure accumulation. This allows quantification of attenuation of sediment threshold velocity and critical shear stress (predominant variables in transport mechanics) during the liquefaction under waves. Parameterising the wave-seabed interactions in a new concept model shows that high waves propagating over the seabed sediment can act as a scarifier plough remoulding the seabed sediment. This contributes to marine hyperpycnal flows as the sediment is quickly resuspended under accumulating attenuation in strength. Therefore, the development of more integrative numerical models could supply realistic predictions of marine record in response to rising magnitude and frequency of storms.

  16. Welding induced residual stress evaluation using laser-generated Rayleigh waves

    Science.gov (United States)

    Ye, Chong; Zhou, Yuanlai; Reddy, Vishnu V. B.; Mebane, Aaron; Ume, I. Charles

    2018-04-01

    Welding induced residual stress could affect the dimensional stability, fatigue life, and chemical resistance of the weld joints. Ultrasonic method serves as an important non-destructive tool for the residual stress evaluation due to its easy implementation, low cost and wide application to different materials. Residual stress would result in the ultrasonic wave velocity variation, which is the so called acoustoelastic effect. In this paper, Laser/EMAT ultrasonic technique was proposed to experimentally study the relative velocity variation ΔV/V of Rayleigh wave, which has the potential to evaluate surface/subsurface longitudinal residual stress developed during the Gas Metal Arc Welding process. Broad band ultrasonic waves were excited by pulsed Q-Switched Nd: YAG laser. An electromagnetic acoustic transducer (EMAT) attached to the welded plates was used to capture the Rayleigh wave signals propagating along the weld seam direction. Different time of flight measurements were conducted by varying the distance between the weld seam and Rayleigh wave propagating path in the range of 0 to 45 mm. The maximum relative velocity difference was found on the weld seam. With the increasing distance away from the weld seam, the relative velocity difference sharply decreased to negative value. With further increase in distance, the relative velocity difference slowly increased and approached zero. The distribution of relative velocity variations indicates that tensile stress appears in the melted zone as it becomes compressive near the heat-affected zone.

  17. A study on early microstructural changes in the rabbit gallbladder induced by shock waves

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Eun Oak [Hong-Sung Koryo Hospital, Hongsung (Korea, Republic of); Shim, Hyung Jin; Kim, Kun Sang; Ryo, Dae Sik; Choi, Yun Sun; Song, In Sup; Kim, Young Koo [College of Medicine, Chung Ang University, Seoul (Korea, Republic of)

    1994-05-15

    In order to evaluate microstructural changes after shock wave exposure, gross, light microscopic and transmission electron microscopic findings were analyzed with rabbit gallbladders. A preliminary study(2 rabbits) was performed to determine the dosage intensity of shock waves needed to inflict damage, using a EDAP LT 01 piezoelectric extracorporeal shock wave lothotriptor. The Gallbladders of three different groups of rabbits were given shock waves of various intensity. A storage value of 100, 50, 25 at rate of 20/sec under 80% power were given to group I (4 rabbits), group II (4 rabbits), and group III (3 rabbits), respectively. The rabbits were sacrificed 6-12 hours later. The observed pathologic changes in the transmission electron microscopy were vaculization of cytoplasm and swelling of epithelial cells with dilatation and structural alteration of intracellular organelles, especially endoplasmic reticulum. Cell membrane rupture and necrosis were observed at the markedly affected area. The structural changes of intracellular organelles were minimally found at a storage value of 25. However, above pathologic changes with dilatation and structural alterations of endoplasmic reticulums were more profound at value of 100. Early histologic changes induced by shocked waves are dose dependent and findings of cellular damage caused by ESWL might be explained as above.

  18. Photoacoustic imaging of blood vessels with a double-ring sensor featuring a narrow angular aperture

    NARCIS (Netherlands)

    Kolkman, R.G.M.; Hondebrink, Erwin; Steenbergen, Wiendelt; van Leeuwen, Ton; de Mul, F.F.M.

    2004-01-01

    A photoacoustic double-ring sensor, featuring a narrow angular aperture, is developed for laser-induced photoacoustic imaging of blood vessels. An integrated optical fiber enables reflection-mode detection of ultrasonic waves. By using the cross-correlation between the signals detected by the two

  19. Enhancement of four-wave mixing induced by interacting dark resonances

    International Nuclear Information System (INIS)

    Yang Weifeng; Gong Shangqing; Niu Yueping; Jin Shiqi; Xu Zhizhan

    2005-01-01

    We analyse a four-wave mixing (FWM) scheme in a five-level atomic system in which double-dark resonances are present. It is found that the enhancement of FWM in both electromagnetically induced transparency (EIT) windows can be obtained even without the condition of multiphoton resonance. Moreover, the conversion efficiency of FWM in one EIT window can be much larger than that in the other due to the presence of interacting dark resonances

  20. Perirenal hematomas induced by extracorporeal shock wave lithotripsy (ESWL). Therapeutic management.

    Science.gov (United States)

    Labanaris, Apostolos P; Kühn, Reinhard; Schott, Günter E; Zugor, Vahudin

    2007-09-17

    Extracorporeal shock wave lithotripsy (ESWL) is nowadays accepted as the treatment of choice for the majority of patients with renal or proximal ureteral calculi. Although, a relatively noninvasive modality with low morbidity, minor or major complications can be noted. A relative severe complication for the patient and confusing for the treating physician is the perirenal hematoma. With review the literature and an example of perirenal hematoma induced by ESWL in a patient treated in our department, we describe its therapeutic management.

  1. Bernstein instability driven by thermal ring distribution

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Peter H., E-mail: yoonp@umd.edu [Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742 (United States); School of Space Research, Kyung Hee University, Yongin-Si, Gyeonggi-Do 446-701 (Korea, Republic of); Hadi, Fazal; Qamar, Anisa [Institute of Physics and Electronics, University of Peshawar, Peshawar 25000 (Pakistan)

    2014-07-15

    The classic Bernstein waves may be intimately related to banded emissions detected in laboratory plasmas, terrestrial, and other planetary magnetospheres. However, the customary discussion of the Bernstein wave is based upon isotropic thermal velocity distribution function. In order to understand how such waves can be excited, one needs an emission mechanism, i.e., an instability. In non-relativistic collision-less plasmas, the only known Bernstein wave instability is that associated with a cold perpendicular velocity ring distribution function. However, cold ring distribution is highly idealized. The present Brief Communication generalizes the cold ring distribution model to include thermal spread, so that the Bernstein-ring instability is described by a more realistic electron distribution function, with which the stabilization by thermal spread associated with the ring distribution is demonstrated. The present findings imply that the excitation of Bernstein waves requires a sufficiently high perpendicular velocity gradient associated with the electron distribution function.

  2. Bernstein instability driven by thermal ring distribution

    International Nuclear Information System (INIS)

    Yoon, Peter H.; Hadi, Fazal; Qamar, Anisa

    2014-01-01

    The classic Bernstein waves may be intimately related to banded emissions detected in laboratory plasmas, terrestrial, and other planetary magnetospheres. However, the customary discussion of the Bernstein wave is based upon isotropic thermal velocity distribution function. In order to understand how such waves can be excited, one needs an emission mechanism, i.e., an instability. In non-relativistic collision-less plasmas, the only known Bernstein wave instability is that associated with a cold perpendicular velocity ring distribution function. However, cold ring distribution is highly idealized. The present Brief Communication generalizes the cold ring distribution model to include thermal spread, so that the Bernstein-ring instability is described by a more realistic electron distribution function, with which the stabilization by thermal spread associated with the ring distribution is demonstrated. The present findings imply that the excitation of Bernstein waves requires a sufficiently high perpendicular velocity gradient associated with the electron distribution function

  3. A miniaturized oxygen sensor integrated on fiber surface based on evanescent-wave induced fluorescence quenching

    Energy Technology Data Exchange (ETDEWEB)

    Xiong, Yan [School of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500 (China); Oil and Gas Field Applied Chemistry Key Laboratory of Sichuan Province, Southwest Petroleum University, Chengdu, 610500 (China); Tan, Jun; Wang, Chengjie; Zhu, Ying [School of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500 (China); Fang, Shenwen [School of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500 (China); Oil and Gas Field Applied Chemistry Key Laboratory of Sichuan Province, Southwest Petroleum University, Chengdu, 610500 (China); Wu, Jiayi; Wang, Qing [School of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500 (China); Duan, Ming, E-mail: swpua124@126.com [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500 (China); School of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500 (China); Oil and Gas Field Applied Chemistry Key Laboratory of Sichuan Province, Southwest Petroleum University, Chengdu, 610500 (China)

    2016-11-15

    In this work, a miniaturized sensor was integrated on fiber surface and developed for oxygen determination through evanescent-wave induced fluorescence quenching. The sensor was designed by using light emitting diode (LED) as light source and optical fiber as light transmission element. Tris(2,2′-bipyridyl) ruthenium ([Ru(bpy){sub 3}]{sup 2+}) fluorophore was immobilized in the organically modified silicates (ORMOSILs) film and coated onto the fiber surface. When light propagated by total internal reflection (TIR) in the fiber core, evanescent wave could be produced on the fiber surface and excite [Ru(bpy){sub 3}]{sup 2+} fluorophore to produce fluorescence emission. Then oxygen could be determinated by its quenching effect on the fluorescence and its concentration could be evaluated according to Stern–Volumer model. Through integrating evanescent wave excitation and fluorescence quenching on fiber surface, the sensor was successfully miniaturized and exhibit improved performances of high sensitivity (1.4), excellent repeatability (1.2%) and fast analysis (12 s) for oxygen determination. The sensor provided a newly portable method for in-situ and real-time measurement of oxygen and showed potential for practical oxygen analysis in different application fields. Furthermore, the fabrication of this sensor provides a miniaturized and portable detection platform for species monitoring by simple modular design. - Highlights: • ORMOSILs sensing film immobilized with [Ru(bpy){sub 3}]{sup 2+} fluorophore was coated on fiber surface. • Evanescent wave on the fiber surface was utilized as excitation source to produce fluorescence. • Oxygen was measured based on its quenching effect on evanescent wave-induce fluorescence. • Sensor fabrication was miniaturized by integrating detection and sensing elements on the fiber. • The modular design sensor provides a detection platform for other species monitoring.

  4. Interventricular dispersion in repolarization causes bifid T waves in dogs with dofetilide-induced long QT syndrome

    NARCIS (Netherlands)

    Meijborg, Veronique M F; Chauveau, Samuel; Janse, Michiel J; Anyukhovsky, Evgeny P; Danilo, Peter R; Rosen, Michael R; Opthof, Tobias; Coronel, Ruben

    BACKGROUND: Long QT2 (LQT2) syndrome is characterized by bifid (or notched) T waves, whose mechanism is not understood. OBJECTIVE: The purpose of this study was to test whether increased interventricular dispersion of repolarization induces bifid T waves. METHODS: We simultaneously recorded surface

  5. Interventricular dispersion in repolarization causes bifid T waves in dogs with dofetilide-induced long QT syndrome

    NARCIS (Netherlands)

    Meijborg, Veronique M. F.; Chauveau, Samuel; Janse, Michiel J.; Anyukhovsky, Evgeny P.; Danilo, Peter R.; Rosen, Michael R.; Opthof, Tobias; Coronel, Ruben

    2015-01-01

    Long QT2 (LQT2) syndrome is characterized by bifid (or notched) T waves, whose mechanism is not understood. The purpose of this study was to test whether increased interventricular dispersion of repolarization induces bifid T waves. We simultaneously recorded surface ECG and unipolar electrograms at

  6. Evaporation-induced self-assembly of quantum dots-based concentric rings on polymer-based nanocomposite films.

    Science.gov (United States)

    Zhang, Shaofu; Luan, Weiling; Zhong, Qixin; Yin, Shaofeng; Yang, Fuqian

    2016-10-12

    The "ball-on-film" template is used to construct concentric rings on the surface of PMMA-QDs (polymethyl methacrylate - quantum dots) nanocomposite films via the evaporation of pure chloroform droplets, which are confined by a steel ball. The concentric rings consist of QDs, as revealed by the fluorescence images of the concentric rings. The photoluminescence intensity of the concentric rings increases with the increase of the distance to the ball center, suggesting that the amount of QDs accumulated around the contact line at individual stick state increases with the increase of the distance to the ball center. Both the wavelength and cross-sectional area (width) of the concentric rings increase approximately linearly with increasing distance to the ball center, independent of the ball size, the film thickness and the QDs concentration. For the PMMA-QDs nanocomposite films prepared from the same QDs concentration in chloroform, the thicker the PMMA-QDs nanocomposite film, the larger the wavelength for the same distance to the ball center. The effect of confinement of two steel balls on the surface patterns over the PMMA-QDs nanocomposite films is studied via a template of "two spheres on film". Symmetric surface patterns are formed. There exist two types of featureless zone between the two balls, depending on the distance between the two balls: one is the inner featureless zone and the other is the outer featureless zone. The size of both featureless zones increases with the increase of the ball distance.

  7. Modification of the ionosphere by VLF wave-induced electron precipitation

    International Nuclear Information System (INIS)

    Doolittle, J.H.

    1982-01-01

    Very low frequency (VLF) waves propagating in the whistler mode in the magnetosphere are known to cause precipitation of energetic electrons at middle latitudes. The interactions between the waves and electrons trapped in the magnetic field are believed to occur through cyclotron resonance. As a monochromatic wave propagates along a field line, the condition for resonance can be satisfied by electrons of a minimum energy at the equator and higher energies at increasing latitudes. Resonant interactions occurring in a field aligned region extending several thousand kilometers on both sides of the equator can therefore result in a precipitation flux with a wide range of energies. Electrons which are scattered into the loss cone will collide with the constituents of the ionosphere, causing additional ionization optical emissions, x-rays and heating. A computational technique is introduced which allows the temporal shape of pulse of precipitation to be modeled. A realistic energy distribution is used to weigh the contribution to the total precipitation energy flux resulting from resonant interactions in each segment of the duct. Wave growth along the path is found to affect the shape of the pulse. In its simplest application, the model sets limits on the time window in which a precipitation event can occur. The model arrival times are shown to agree with experimental correlations of VLF waves and effects of precipitation occurring on three occasions, thus supporting the assumption, that the precipitation results from cyclotron resonant scattering. Various techniques that have been employed for detecting wave-induced precipitation are compared. A quantitative analysis of the use of an HF radar for this purpose is introduced, based on the changes in the phase and group paths of the radar signals that are reflected from the perturbed ionosphere

  8. Effect of a transverse plasma jet on a shock wave induced by a ramp

    Directory of Open Access Journals (Sweden)

    Hongyu WANG

    2017-12-01

    Full Text Available We conducted experiments in a wind tunnel with Mach number 2 to explore the evolution of a transverse plasma jet and its modification effect on a shock wave induced by a ramp with an angle of 24°. The transverse plasma jet was created by arc discharge in a small cylindrical cavity with a 2 mm diameter orifice. Three group tests with different actuator arrangements in the spanwise or streamwise direction upstream from the ramp were respectively studied to compare their disturbances to the shock wave. As shown by a time-resolved schlieren system, an unsteady motion of the shock wave by actuation was found: the shock wave was significantly modified by the plasma jet with an upstream motion and a reduced angle. Compared to spanwise actuation, a more intensive impact was obtained with two or three streamwise actuators working together. From shock wave structures, the control effect of the plasma jet on the shock motion based on a thermal effect, a potential cause of shock modification, was discussed. Furthermore, we performed a numerical simulation by using the Improved Delayed Detached Eddy Simulation (IDDES method to simulate the evolution of the transverse plasma jet plume produced by two streamwise actuators. The results show that flow structures are similar to those identified in schlieren images. Two streamwise vortices were recognized, which indicates that the higher jet plume is the result of the overlap of two streamwise jets. Keywords: Flow control, Improved delayed detached eddy simulation (IDDES method, Plasma synthetic jet, Shock wave/boundary layer interaction, Time resolved schlieren system

  9. Laser-induced pressure-wave and barocaloric effect during flash diffusivity measurements

    International Nuclear Information System (INIS)

    Wang, Hsin; Porter, Wallace D.; Dinwiddie, Ralph Barton

    2017-01-01

    We report laser-induced pressure-wave and barocaloric effect captured by an infrared detector during thermal diffusivity measurements. Very fast (< 1 ms) and negative transients during laser flash measurements were captured by the infrared detector on thin, high thermal conductivity samples. Standard thermal diffusivity analysis only focuses the longer time scale thermal transient measured from the back surface due to thermal conduction. These negative spikes are filtered out and ignored as noise or anomaly from instrument. This study confirmed that the initial negative signal was indeed a temperature drop induced by the laser pulse. The laser pulse induced instantaneous volume expansion and the associated cooling in the specimen can be explained by the barocaloric effect. The initial cooling (< 100 microsecond) is also known as thermoelastic effect in which a negative temperature change is generated when the material is elastically deformed by volume expansion. A subsequent temperature oscillation in the sample was observed and only lasted about one millisecond. The pressure-wave induced thermal signal was systematically studied and analyzed. In conclusion, the underlying physics of photon-mechanical-thermal energy conversions and the potential of using this signal to study barocaloric effects in solids are discussed.

  10. Ring cavity surface emitting semiconductor lasers

    International Nuclear Information System (INIS)

    Mujagic, E.

    2010-01-01

    m. Characterizations indicate a high temperature operation of MIR ring-CSELs along with a reduction in threshold current density of MIR devices by 35% as compared to Fabry-Perot devices. The lower operating currents in ring-CSELs became noticeable in continuous wave (CW) operation with a 50K higher maximum temperature than in FP lasers. A two-fold enhancement in radiation efficiency was obtained in MIR and THz ring-CSELs as compared to FP emitters. The DFB grating on top of the resonator gives rise to a single-mode operation of ring-CSELs for all operation currents. Linear wavelength tuning is achieved by fabricating different gratings periods as well as by a variation in temperature. The slope efficiency and the threshold current density does not seem to significantly depend on the grating period, which is attributed to the absence of mirrors. The incorporated circular waveguide geometry along with the surface emitting character gives rise to symmetric and low divergence azimuthally polarized optical beams. The recorded far-fields indicate a ring shaped interference patterns with lobe separations of 1.34 o and 14.14 o for MIR and THz ring-CSELs, respectively. Fabrication of detuned gratings led to a grating period induced as well as to a tunable wavelength induced beam shaping, with beam patterns ranging from spot to wide ring cross sections. (author) [de

  11. Multielement analysis of Picea rubens Sarg. Three-rings by proton-induced x-ray emission

    International Nuclear Information System (INIS)

    Hall, G.S.

    1984-01-01

    A 3.7 MeV external proton beam was employed to produce X-rays in Picea rubens Sarg. (red spruce). Intra-annual growth rings and several elements were quantitatively determined (P, S, Cl, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Pb, Sr). The PIXE experimental set-up, rapid sample preparation methods, and some interesting observations are discussed. In addition, statistical analysis of the tree-ring element concentrations revealed that K, Cl, and Ca were slightly translocated whereas the other elements detected were not. 15 references, 1 figure, 1 table

  12. Striped morphologies induced by magnetic impurities in d-wave superconductors

    Science.gov (United States)

    Zuo, Xian-Jun

    2011-05-01

    We study striped morphologies induced by magnetic impurities in d-wave superconductors (DSCs) near optimal doping by self-consistently solving the Bogoliubov-de Gennes equations based on the t - t‧ - U - V model. For the single-impurity case, it is found that the stable ground state is a modulated checkerboard pattern. For the two-impurity case, the stripe-like structures in order parameters are induced due to the impurity-pinning effect. The modulations of DSC and charge orders share the same period of four lattice constants (4 a), which is half the period of modulations in the coexisting spin order. Interestingly, when three or more impurities are inserted, the impurities could induce more complex striped morphologies due to quantum interference. Further experiments of magnetic impurity substitution in DSCs are expected to check these results.

  13. Spiral Waves and Multiple Spatial Coherence Resonances Induced by Colored Noise in Neuronal Network

    International Nuclear Information System (INIS)

    Tang Zhao; Li Yuye; Xi Lei; Jia Bing; Gu Huaguang

    2012-01-01

    Gaussian colored noise induced spatial patterns and spatial coherence resonances in a square lattice neuronal network composed of Morris-Lecar neurons are studied. Each neuron is at resting state near a saddle-node bifurcation on invariant circle, coupled to its nearest neighbors by electronic coupling. Spiral waves with different structures and disordered spatial structures can be alternately induced within a large range of noise intensity. By calculating spatial structure function and signal-to-noise ratio (SNR), it is found that SNR values are higher when the spiral structures are simple and are lower when the spatial patterns are complex or disordered, respectively. SNR manifest multiple local maximal peaks, indicating that the colored noise can induce multiple spatial coherence resonances. The maximal SNR values decrease as the correlation time of the noise increases. These results not only provide an example of multiple resonances, but also show that Gaussian colored noise play constructive roles in neuronal network. (general)

  14. Evaluation of a shock wave induced cavitation activity both in vitro and in vivo

    International Nuclear Information System (INIS)

    Tu Juan; Matula, Thomas J; Bailey, Michael R; Crum, Lawrence A

    2007-01-01

    This study evaluated the cavitation activity induced by shock wave (SW) pulses, both in vitro and in vivo, based on the area measurements of echogenic regions observed in B-mode ultrasound images. Residual cavitation bubble clouds induced by SW pulses were detected as echogenic regions in B-mode images. The temporal evolution of residual bubble clouds, generated by SWs with varying lithotripter charging voltage and pulse repetition frequency (PRF), was analyzed by measuring the time-varying behaviors of the echogenic region areas recorded in B-mode images. The results showed that (1) the area of SW-induced echogenic regions enlarged with increased SW pulse number; (2) echogenic regions in the B-mode images dissipated gradually after ceasing the SWs, which indicated the dissolution of the cavitation bubbles; and (3) larger echogenic regions were generated with higher charging voltage or PRF

  15. Measurements in a container ship of wave-induced hull girder stresses in excess of design values

    DEFF Research Database (Denmark)

    Andersen, Ingrid Marie Vincent; Jensen, Jørgen Juncher

    2014-01-01

    This paper describes full-scale measurements of the wave-induced vertical bending moment amidships a 9400 TEU container carrier and focuses on the effect of the hydro-elastic high-frequency vibration on the extreme hogging wave bending moment. One extreme event, where the vertical wave-induced ho...... is quite significant. Finally, the hydro-elastic behaviour of the hull girder is assessed by simple approximations using the measured statistical properties and closed-form expressions and the agreement with the actual measurements is found to be good. © 2014 Elsevier Ltd....

  16. Parameter Diversity Induced Multiple Spatial Coherence Resonances and Spiral Waves in Neuronal Network with and Without Noise

    International Nuclear Information System (INIS)

    Li Yuye; Jia Bing; Gu Huaguang; An Shucheng

    2012-01-01

    Diversity in the neurons and noise are inevitable in the real neuronal network. In this paper, parameter diversity induced spiral waves and multiple spatial coherence resonances in a two-dimensional neuronal network without or with noise are simulated. The relationship between the multiple resonances and the multiple transitions between patterns of spiral waves are identified. The coherence degrees induced by the diversity are suppressed when noise is introduced and noise density is increased. The results suggest that natural nervous system might profit from both parameter diversity and noise, provided a possible approach to control formation and transition of spiral wave by the cooperation between the diversity and noise. (general)

  17. Auroral electron fluxes induced by static magnetic field aligned electric field and plasma wave turbulence

    International Nuclear Information System (INIS)

    Assis, A.S. de; Silva, C.E. da; Dias Tavares, A. Jr.; Leubner, C.; Kuhn, S.

    2001-07-01

    We have studied the formation of auroral electron fluxes induced by a field aligned dc electric field in the presence of plasma wave turbulence. The effect of the wave spectral shape on the production rate has been considered. This acceleration scheme was modelled by the weak turbulence approach. The electron fluxes for narrow and broad band spectra, in the case of low and high phase velocities, are calculated, and it is found as a general feature, for all modes, that their enhancement is larger the weaker the background electric field, while for its absolute enhancement it is just the opposite. The electron fluxes are enhanced by many orders of magnitude over that without turbulence. It is also shown that the modes enhance the runaway production rate via their Cherenkov dissipation, and that a synergetic effect occurs in the enhancement when more than one mode turbulent is present in the acceleration region. (author)

  18. Distorted wave calculations for electron loss process induced by bare ion impact on biological targets

    International Nuclear Information System (INIS)

    Monti, J.M.; Tachino, C.A.; Hanssen, J.; Fojón, O.A.; Galassi, M.E.; Champion, C.; Rivarola, R.D.

    2014-01-01

    Distorted wave models are employed to investigate the electron loss process induced by bare ions on biological targets. The two main reactions which contribute to this process, namely, the single electron ionization as well as the single electron capture are here studied. In order to further assess the validity of the theoretical descriptions used, the influence of particular mechanisms are studied, like dynamic screening for the case of electron ionization and energy deposition on the target by the impacting projectile for the electron capture one. Results are compared with existing experimental data. - Highlights: ► Distorted wave models are used to investigate ion-molecule collisions. ► Differential and total cross-sections for capture and ionization are evaluated. ► The influence of dynamic screening is determined. ► Capture reaction dominates the mean energy deposited by the projectile on the target

  19. Parametric study of the damage ring pattern in fused silica induced by multiple longitudinal modes laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Chambonneau, M., E-mail: maxime.chambonneau@hotmail.fr; Grua, P.; Rullier, J.-L.; Lamaignère, L. [CEA CESTA, 15 Avenue des Sablières, CS 60001, 33116 Le Barp Cedex (France); Natoli, J.-Y. [Aix Marseille Université, CNRS, Centrale Marseille, Institut Fresnel, UMR 7249, 13013 Marseille (France)

    2015-03-14

    With the use of multiple longitudinal modes nanosecond laser pulses at 1064 nm, laser damage sites at the exit surface of fused silica clearly and systematically exhibit ring patterns. It has been shown in our previous works that the apparent chronology of rings was closely related to the temporal shape of the laser pulses. This particular correspondence had suggested an explanation of the ring morphology formation based on the displacement of an ionization front in the surrounding air. To provide a former basis for this hypothesis and deeper understanding of ring pattern formation, additional experiments have been performed. First, the impact of fluence has been investigated, revealing that a wide variety of damage sites are produced within a very narrow fluence range; this fact involves the chronology of appearance of a surface plasma during the laser pulse. The sizes of the damage sites are proportional to the fluence of their expansion occurring between the beginning of the plasma and the end of the laser pulse. Second, specific experiments have been carried out at different angles of incidence, resulting in egg-shaped patterns rather than circular ones. This behavior can be explained by our previous hypothesis of creation of a plasma in air, its expansion being tightly conditioned by the illumination angle. This series of experiments, in which the angle of incidence is varied up to 80°, permits us to link quantitatively the working hypothesis of ionization front propagation with theoretical hydrodynamics modeling.

  20. ring system

    African Journals Online (AJOL)

    1,3,2-DIAZABORACYCLOALKANE. RING SYSTEM. Negussie Retta" and Robert H. Neilson. 'Department of Chemistry, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia. Department of Chemistry, Texas Christian University.

  1. Laser light scattering in a laser-induced argon plasma: Investigations of the shock wave

    Energy Technology Data Exchange (ETDEWEB)

    Pokrzywka, B. [Obserwatorium Astronomiczne na Suhorze, Uniwersytet Pedagogiczny, ulica Podchorazych 2, 30-084 Krakow (Poland); Mendys, A., E-mail: agata.mendys@uj.edu.pl [Instytut Fizyki im. M. Smoluchowskiego, Uniwersytet Jagiellonski, ulica Reymonta 4, 30-059 Krakow (Poland); Dzierzega, K.; Grabiec, M. [Instytut Fizyki im. M. Smoluchowskiego, Uniwersytet Jagiellonski, ulica Reymonta 4, 30-059 Krakow (Poland); Pellerin, S. [GREMI, site de Bourges, Universite d' Orleans, CNRS, rue Gaston Berger BP 4043, 18028 Bourges (France)

    2012-08-15

    Shock wave produced by a laser induced spark in argon at atmospheric pressure was examined using Rayleigh and Thomson scattering. The spark was generated by focusing a laser pulse from the second harmonic ({lambda} = 532 nm) of a nanosecond Nd:YAG laser using an 80 mm focal length lens, with a fluence of 2 kJ{center_dot}cm{sup -2}. Images of the spark emission were recorded for times between 30 ns and 100 {mu}s after the laser pulse in order to characterize its spatial evolution. The position of the shock wave at several instants of its evolution and for several plasma regions was determined from the Rayleigh-scattered light of another nanosecond Nd:YAG laser (532 nm, 40 J{center_dot}cm{sup -2} fluence). Simultaneously, Thomson scattering technique was applied to determine the electron density and temperature in the hot plasma core. Attempts were made to describe the temporal evolution of the shock wave within a self-similar model, both by the simple Sedov-Taylor formula as well as its extension deduced by de Izarra. The temporal radial evolution of the shock position is similar to that obtained within theory taking into account the counter pressure of the ambient gas. Density profiles just behind the shock front are in qualitative agreement with those obtained by numerically solving the Euler equations for instantaneous explosion at a point with counter pressure. - Highlights: Black-Right-Pointing-Pointer We investigated shock wave evolution by Rayleigh scattering method. Black-Right-Pointing-Pointer 2D map of shockwave position for several times after plasma generation is presented. Black-Right-Pointing-Pointer Shock wave evolution is not satisfactorily described within self-similar models. Black-Right-Pointing-Pointer Evolution of shock position similar to theory taking into account counter pressure. Black-Right-Pointing-Pointer Density profile behind the shock similar to numerical solution of Euler equations.

  2. Formation and damping of a shock wave induced by laser in a metallic target

    International Nuclear Information System (INIS)

    Cottet, F.

    1981-01-01

    In the first part of this work, a numerical simulation of the formation and of the damping of the shock wave induced in a solid target by a laser impulse is developed. It allows to interpret the experimental obtained in the second part of the study. Two series of experiments have been realized. An iron target metallographic study is intended to verify if laser shocks produce effects comparable with conventional shocks, particularly a deformation by albite twinning the existence of which is related to the shock amplitude and its evolution during the propagation in the target. Macles observation become a possible mean to estimate the value of the induced pressures. Another experiment series has been realized to determine more directly the shock parameters. Piezoelectric cermets have been used to detect a shock-wave passage and to measure the time taken to go through targets of variable thickness. The numerical solution allows, afterwards, to deduce the maximum pressure of the induced shock. The most part of the tests have been done on copper targets, the behaviour of which is well known in a large pressure domain. Some tests have been realized on aluminium and iron targets [fr

  3. Modeling quiescent phase transport of air bubbles induced by breaking waves

    Science.gov (United States)

    Shi, Fengyan; Kirby, James T.; Ma, Gangfeng

    Simultaneous modeling of both the acoustic phase and quiescent phase of breaking wave-induced air bubbles involves a large range of length scales from microns to meters and time scales from milliseconds to seconds, and thus is computational unaffordable in a surfzone-scale computational domain. In this study, we use an air bubble entrainment formula in a two-fluid model to predict air bubble evolution in the quiescent phase in a breaking wave event. The breaking wave-induced air bubble entrainment is formulated by connecting the shear production at the air-water interface and the bubble number intensity with a certain bubble size spectra observed in laboratory experiments. A two-fluid model is developed based on the partial differential equations of the gas-liquid mixture phase and the continuum bubble phase, which has multiple size bubble groups representing a polydisperse bubble population. An enhanced 2-DV VOF (Volume of Fluid) model with a k - ɛ turbulence closure is used to model the mixture phase. The bubble phase is governed by the advection-diffusion equations of the gas molar concentration and bubble intensity for groups of bubbles with different sizes. The model is used to simulate air bubble plumes measured in laboratory experiments. Numerical results indicate that, with an appropriate parameter in the air entrainment formula, the model is able to predict the main features of bubbly flows as evidenced by reasonable agreement with measured void fraction. Bubbles larger than an intermediate radius of O(1 mm) make a major contribution to void fraction in the near-crest region. Smaller bubbles tend to penetrate deeper and stay longer in the water column, resulting in significant contribution to the cross-sectional area of the bubble cloud. An underprediction of void fraction is found at the beginning of wave breaking when large air pockets take place. The core region of high void fraction predicted by the model is dislocated due to use of the shear

  4. Pyrimidine-pyridine ring interconversion

    NARCIS (Netherlands)

    Plas, van der H.C.

    2003-01-01

    This chapter discusses the pyrimidine-to-pyridine ring transformation and pyridine-to-pyrimidine ring transformation. In nucleophile-induced pyrimidine-to-pyridine rearrangements, two types of reactions can be distinguished depending on the structure of the nucleophile: (1) reactions in which the

  5. How to detect the gravitationally induced phase shift of electromagnetic waves by optical-fiber interferometry

    International Nuclear Information System (INIS)

    Tanaka, K.

    1983-01-01

    Attention is called to a laboratory experiment of an optical-fiber interferometer which can show the gravitationally induced phase shift of optical waves. A phase shift of approx.10 -6 rad is anticipated for the Earth's gravitational potential difference of 1 m when a He-Ne laser and two multiple-turn optical-fiber loops of length 5 km are used. The phase shift can be varied by rotating the loops about an axis parallel to the Earth's surface. This order of phase shifts can be detected by current optical-fiber interferometric techniques

  6. Fluorescence and Four-Wave Mixing in Electromagnetically Induced Transparency Windows

    International Nuclear Information System (INIS)

    Wang Zhi-Guo; Li Cheng; Zhang Zhao-Yang; Che Jun-Ling; Qin Meng-Zhe; He Jia-Nan; Zhang Yan-Peng

    2013-01-01

    We simultaneously compare the probe transmission, Four-Wave Mixing (FWM) and fluorescence signals with dressing effects in a four-level atomic system. The variation rules of three types of signals are exhibited by changing the frequency detuning and power of incident laser beams. The interplay between two ladder subsystems is investigated in the Y-type atomic system. In particular, the fluorescence signal with ultra-narrow linewidth is obtained due to being sheared twice by the electromagnetically induced transparency window. Such fluorescence with very high coherence and monochromaticity can be used for the quantum correlation and narrow linewidth laser

  7. Chemical Sensors Based on Optical Ring Resonators

    Science.gov (United States)

    Homer, Margie; Manfreda, Allison; Mansour, Kamjou; Lin, Ying; Ksendzov, Alexander

    2005-01-01

    Chemical sensors based on optical ring resonators are undergoing development. A ring resonator according to this concept is a closed-circuit dielectric optical waveguide. The outermost layer of this waveguide, analogous to the optical cladding layer on an optical fiber, is a made of a polymer that (1) has an index of refraction lower than that of the waveguide core and (2) absorbs chemicals from the surrounding air. The index of refraction of the polymer changes with the concentration of absorbed chemical( s). The resonator is designed to operate with relatively strong evanescent-wave coupling between the outer polymer layer and the electromagnetic field propagating along the waveguide core. By virtue of this coupling, the chemically induced change in index of refraction of the polymer causes a measurable shift in the resonance peaks of the ring. In a prototype that has been used to demonstrate the feasibility of this sensor concept, the ring resonator is a dielectric optical waveguide laid out along a closed path resembling a racetrack (see Figure 1). The prototype was fabricated on a silicon substrate by use of standard techniques of thermal oxidation, chemical vapor deposition, photolithography, etching, and spin coating. The prototype resonator waveguide features an inner cladding of SiO2, a core of SixNy, and a chemical-sensing outer cladding of ethyl cellulose. In addition to the ring Chemical sensors based on optical ring resonators are undergoing development. A ring resonator according to this concept is a closed-circuit dielectric optical waveguide. The outermost layer of this waveguide, analogous to the optical cladding layer on an optical fiber, is a made of a polymer that (1) has an index of refraction lower than that of the waveguide core and (2) absorbs chemicals from the surrounding air. The index of refraction of the polymer changes with the concentration of absorbed chemical( s). The resonator is designed to operate with relatively strong

  8. Direct measurement of the plasma response to electrostatic ion waves

    International Nuclear Information System (INIS)

    Sarfaty, M.; DeSouza-Machado, S.; Skiff, F.

    1995-01-01

    Plasma wave-wave and wave-particle interactions are studied in a linear magnetized plasma. The relatively quiet plasma is produced by an argon gas-discharge. The plasma density is n e ≅ 10 9 cm -3 and the electron/ion temperatures are T e ≅ 5eV and T i = 0.05eV. A grid and a four ring antenna, both mounted on a scanning carriage, are used to launch electrostatic ion waves in the plasma. Laser Induced Fluorescence measurements of both the linear and the nonlinear plasma response to the wave fields are presented. The Vlasov-Poisson equations are used to explain the measured zero, first and second order terms of the ion distribution function in the presence of wave fields. In addition to the broadening (heating) of the ion distribution as the authors increase the wave amplitudes, induced plasma flows are observed both along and across the magnetic field

  9. Experimental Study of Shock Generated Compressible Vortex Ring

    Science.gov (United States)

    Das, Debopam; Arakeri, Jaywant H.; Krothapalli, Anjaneyulu

    2000-11-01

    Formation of a compressible vortex ring and generation of sound associated with it is studied experimentally. Impulse of a shock wave is used to generate a vortex ring from the open end of a shock-tube. Vortex ring formation process has been studied in details using particle image Velocimetry (PIV). As the shock wave exits the tube it diffracts and expands. A circular vortex sheet forms at the edge and rolls up into a vortex ring. Far field microphone measurement shows that the acoustic pressure consists of a spike due to shock wave followed by a low frequency pressure wave of decaying nature, superimposed with high frequency pressure wave. Acoustic waves consist of waves due to expansion, waves formed in the tube during diaphragm breakage and waves associated with the vortex ring and shear-layer vortices. Unsteady evolution of the vortex ring and shear-layer vortices in the jet behind the ring is studied by measuring the velocity field using PIV. Corresponding vorticity field, circulation around the vortex core and growth rate of the vortex core is calculated from the measured velocity field. The velocity field in a compressible vortex ring differs from that of an incompressible ring due to the contribution from both shock and vortex ring.

  10. Analysis of flow induced valve operation and pressure wave propagation for single and two-phase flow conditions

    International Nuclear Information System (INIS)

    Nagel, H.

    1986-01-01

    The flow induced valve operation is calculated for single and two-phase flow conditions by the fluid dynamic computer code DYVRO and results are compared to experimental data. The analysis show that the operational behaviour of the valves is not only dependent on the condition of the induced flow, but also the pipe flow can cause a feedback as a result of the induced pressure waves. For the calculation of pressure wave propagation in pipes of which the operation of flow induced valves has a considerable influence it is therefore necessary to have a coupled analysis of the pressure wave propagation and the operational behaviour of the valves. The analyses of the fast transient transfer from steam to two-phase flow show a good agreement with experimental data. Hence even these very high loads on pipes resulting from such fluid dynamic transients can be calculated realistically. (orig.)

  11. Time-synchronized continuous wave laser-induced fluorescence on an oscillatory xenon discharge.

    Science.gov (United States)

    MacDonald, N A; Cappelli, M A; Hargus, W A

    2012-11-01

    A novel approach to time-synchronizing laser-induced fluorescence measurements to an oscillating current in a 60 Hz xenon discharge lamp using a continuous wave laser is presented. A sample-hold circuit is implemented to separate out signals at different phases along a current cycle, and is followed by a lock-in amplifier to pull out the resulting time-synchronized fluorescence trace from the large background signal. The time evolution of lower state population is derived from the changes in intensity of the fluorescence excitation line shape resulting from laser-induced fluorescence measurements of the 6s(')[1/2](1)(0)-6p(')[3/2](2) xenon atomic transition at λ = 834.68 nm. Results show that the lower state population oscillates at twice the frequency of the discharge current, 120 Hz.

  12. Time-synchronized continuous wave laser-induced fluorescence on an oscillatory xenon discharge

    Energy Technology Data Exchange (ETDEWEB)

    MacDonald, N. A.; Cappelli, M. A. [Stanford Plasma Physics Laboratory, Stanford University, Stanford, California 94305 (United States); Hargus, W. A. Jr. [Air Force Research Laboratory, Edwards AFB, California 93524 (United States)

    2012-11-15

    A novel approach to time-synchronizing laser-induced fluorescence measurements to an oscillating current in a 60 Hz xenon discharge lamp using a continuous wave laser is presented. A sample-hold circuit is implemented to separate out signals at different phases along a current cycle, and is followed by a lock-in amplifier to pull out the resulting time-synchronized fluorescence trace from the large background signal. The time evolution of lower state population is derived from the changes in intensity of the fluorescence excitation line shape resulting from laser-induced fluorescence measurements of the 6s{sup Prime }[1/2]{sub 1}{sup 0}-6p{sup Prime }[3/2]{sub 2} xenon atomic transition at {lambda}= 834.68 nm. Results show that the lower state population oscillates at twice the frequency of the discharge current, 120 Hz.

  13. Wave-mixing-induced transparency with zero phase shift in atomic vapors

    Science.gov (United States)

    Zhou, F.; Zhu, C. J.; Li, Y.

    2017-12-01

    We present a wave-mixing induced transparency that can lead to a hyper-Raman gain-clamping effect. This new type of transparency is originated from a dynamic gain cancellation effect in a multiphoton process where a highly efficient light field of new frequency is generated and amplified. We further show that this novel dynamic gain cancellation effect not only makes the medium transparent to a probe light field at appropriate frequency but also eliminates the probe field propagation phase shift. This gain-cancellation-based induced transparency holds for many potential applications on optical communication and may lead to effective suppression of parasitic Raman/hyper-Raman noise field generated in high intensity optical fiber transmissions.

  14. New insights into the by-product fatigue mechanism of the photo-induced ring-opening in diarylethenes.

    Science.gov (United States)

    Mendive-Tapia, David; Perrier, Aurélie; Bearpark, Michael J; Robb, Michael A; Lasorne, Benjamin; Jacquemin, Denis

    2014-09-14

    The photochromic properties of diarylethenes, some of the most studied class of molecular switches, are known to be controlled by non-adiabatic decay at a conical intersection seam. Nevertheless, as their fatigue-reaction mechanism - leading to non-photochromic products - is yet to be understood, we investigate the photo-chemical formation of the so-called by-product isomer using three complementary computational methods (MMVB, CASSCF and CASPT2) on three model systems of increasing complexity. We show that for the ring-opening reaction a transition state on S1(2A) involving bond breaking of the penta-ring leads to a low energy S1(2A)/S0(1A) conical intersection seam, which lies above one of the transition states leading to the by-product isomer on the ground state. Therefore, radiationless decay and subsequent side-product formation can take place explaining the photo-degradation responsible for the by-product generation in diarylethene-type molecules. The effect of dynamic electron correlation and the possible role of inter-system crossing along the penta-ring opening coordinate are discussed as well.

  15. Magnetization of two coupled rings

    International Nuclear Information System (INIS)

    Avishai, Y; Luck, J M

    2009-01-01

    We investigate the persistent currents and magnetization of a mesoscopic system consisting of two clean metallic rings sharing a single contact point in a magnetic field. Many novel features with respect to the single-ring geometry are underlined, including the explicit dependence of wavefunctions on the Aharonov-Bohm fluxes, the complex pattern of two-fold and three-fold degeneracies, the key role of length and flux commensurability, and in the case of commensurate ring lengths the occurrence of idle levels which do not carry any current. Spin-orbit interactions, induced by the electric fields of charged wires threading the rings, give rise to a peculiar version of the Aharonov-Casher effect where, unlike for a single ring, spin is not conserved. Remarkably enough, this can only be realized when the Aharonov-Bohm fluxes in both rings are neither integer nor half-integer multiples of the flux quantum

  16. Planetary-scale circulations in the presence of climatological and wave-induced heating

    Science.gov (United States)

    Salby, Murry L; Garcia, Rolando R.; Hendon, Harry H.

    1994-01-01

    Interaction between the large-scale circulation and the convective pattern is investigated in a coupled system governed by the linearized primitive equations. Convection is represented in terms of two components of heating: A 'climatological component' is prescribed stochastically to represent convection that is maintained by fixed distributions of land and sea and sea surface temperature (SST). An 'induced component' is defined in terms of the column-integrated moisture flux convergence to represent convection that is produced through feedback with the circulation. Each component describes the envelope organizing mesoscale convective activity. As SST on the equator is increased, induced heating amplifies in the gravest zonal wavenumbers at eastward frequencies, where positive feedback offsets dissipation. Under barotropic stratification, a critical SST of 29.5 C results in positive feedback exactly cancelling dissipation in wavenumber 1 for an eastward phase speed of 6 m/s. Sympathetic interaction between the circulation and the induced heating is the basis for 'frictional wave-Conditional Instability of the Second Kind (CISK)', which is distinguished from classical wave-CISK by rendering the gravest zonal dimensions most unstable. Under baroclinic stratification, the coupled system exhibits similar behavior. The critical SST is only 26.5 C for conditions representative of equinox, but in excess of 30 C for conditions representative of solstice. Having the form of an unsteady Walker circulation, the disturbance produced by frictional wave-CISK compares favorably with the observed life cycle of the Madden-Julian oscillation (MJO). SST above the critical value produces an amplifying disturbance in which enhanced convection coincides with upper-tropospheric westerlies and is positively correlated with temperature and surface convergence. Conversely, SST below the critical value produces a decaying disturbance in which enhanced convection coincides with upper

  17. Storage Rings

    International Nuclear Information System (INIS)

    Fischer, W.

    2010-01-01

    Storage rings are circular machines that store particle beams at a constant energy. Beams are stored in rings without acceleration for a number of reasons (Tab. 1). Storage rings are used in high-energy, nuclear, atomic, and molecular physics, as well as for experiments in chemistry, material and life sciences. Parameters for storage rings such as particle species, energy, beam intensity, beam size, and store time vary widely depending on the application. The beam must be injected into a storage ring but may not be extracted (Fig. 1). Accelerator rings such as synchrotrons are used as storage rings before and after acceleration. Particles stored in rings include electrons and positrons; muons; protons and anti-protons; neutrons; light and heavy, positive and negative, atomic ions of various charge states; molecular and cluster ions, and neutral polar molecules. Spin polarized beams of electrons, positrons, and protons were stored. The kinetic energy of the stored particles ranges from 10 -6 eV to 3.5 x 10 12 eV (LHC, 7 x 10 12 eV planned), the number of stored particles from one (ESR) to 1015 (ISR). To store beam in rings requires bending (dipoles) and transverse focusing (quadrupoles). Higher order multipoles are used to correct chromatic aberrations, to suppress instabilities, and to compensate for nonlinear field errors of dipoles and quadrupoles. Magnetic multipole functions can be combined in magnets. Beams are stored bunched with radio frequency systems, and unbunched. The magnetic lattice and radio frequency system are designed to ensure the stability of transverse and longitudinal motion. New technologies allow for better storage rings. With strong focusing the beam pipe dimensions became much smaller than previously possible. For a given circumference superconducting magnets make higher energies possible, and superconducting radio frequency systems allow for efficient replenishment of synchrotron radiation losses of large current electron or positron beams

  18. Experimental investigation of flow induced dust acoustic shock waves in a complex plasma

    Energy Technology Data Exchange (ETDEWEB)

    Jaiswal, S., E-mail: surabhijaiswal73@gmail.com; Bandyopadhyay, P.; Sen, A. [Institute for Plasma Research, Bhat, Gandhinagar, Gujarat 382428 (India)

    2016-08-15

    We report on experimental observations of flow induced large amplitude dust-acoustic shock waves in a complex plasma. The experiments have been carried out in a Π shaped direct current glow discharge experimental device using kaolin particles as the dust component in a background of Argon plasma. A strong supersonic flow of the dust fluid is induced by adjusting the pumping speed and neutral gas flow into the device. An isolated copper wire mounted on the cathode acts as a potential barrier to the flow of dust particles. A sudden change in the gas flow rate is used to trigger the onset of high velocity dust acoustic shocks whose dynamics are captured by fast video pictures of the evolving structures. The physical characteristics of these shocks are delineated through a parametric scan of their dynamical properties over a range of flow speeds and potential hill heights. The observed evolution of the shock waves and their propagation characteristics are found to compare well with model numerical results based on a modified Korteweg-de-Vries-Burgers type equation.

  19. Furosin, an ellagitannin, suppresses RANKL-induced osteoclast differentiation and function through inhibition of MAP kinase activation and actin ring formation

    International Nuclear Information System (INIS)

    Park, Eui Kyun; Kim, Myung Sunny; Lee, Seung Ho; Kim, Kyung Hee; Park, Ju-Young; Kim, Tae-Ho; Lee, In-Seon; Woo, Je-Tae; Jung, Jae-Chang; Shin, Hong-In; Choi, Je-Yong; Kim, Shin-Yoon

    2004-01-01

    Phenolic compounds including tannins and flavonoids have been implicated in suppression of osteoclast differentiation/function and prevention of bone diseases. However, the effects of hydrolysable tannins on bone metabolism remain to be elucidated. In this study, we found that furosin, a hydrolysable tannin, markedly decreased the differentiation of both murine bone marrow mononuclear cells and Raw264.7 cells into osteoclasts, as revealed by the reduced number of tartrate resistant acid phosphatase (TRAP)-positive multinucleated cells and decreased TRAP activity. Furosin appears to target at the early stage of osteoclastic differentiation while having no cytotoxic effect on osteoclast precursors. Analysis of the inhibitory mechanisms of furosin revealed that it inhibited the receptor activator of nuclear factor-κB ligand (RANKL)-induced activation of p38 mitogen-activated protein kinase (p38MAPK) and c-Jun N-terminal kinase (JNK)/activating protein-1 (AP-1). Furthermore, furosin reduced resorption pit formation in osteoclasts, which was accompanied by disruption of the actin rings. Taken together, these results demonstrate that naturally occurring furosin has an inhibitory activity on both osteoclast differentiation and function through mechanisms involving inhibition of the RANKL-induced p38MAPK and JNK/AP-1 activation as well as actin ring formation

  20. Topological rings

    CERN Document Server

    Warner, S

    1993-01-01

    This text brings the reader to the frontiers of current research in topological rings. The exercises illustrate many results and theorems while a comprehensive bibliography is also included. The book is aimed at those readers acquainted with some very basic point-set topology and algebra, as normally presented in semester courses at the beginning graduate level or even at the advanced undergraduate level. Familiarity with Hausdorff, metric, compact and locally compact spaces and basic properties of continuous functions, also with groups, rings, fields, vector spaces and modules, and with Zorn''s Lemma, is also expected.

  1. Ring accelerators

    International Nuclear Information System (INIS)

    Gisler, G.; Faehl, R.

    1983-01-01

    We present two-dimensional simulations in (r-z) and r-theta) cylinderical geometries of imploding-liner-driven accelerators of rings of charged particles. We address issues of azimuthal and longitudinal stability of the rings. We discuss self-trapping designs in which beam injection and extraction is aided by means of external cusp fields. Our simulations are done with the 2-1/2-D particle-in-cell plasma simulation code CLINER, which combines collisionless, electromagnetic PIC capabilities with a quasi-MHD finite element package

  2. Alfvén Wave Turbulence as a Coronal Heating Mechanism: Simultaneously Predicting the Heating Rate and the Wave-induced Emission Line Broadening

    Energy Technology Data Exchange (ETDEWEB)

    Oran, R. [Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139 (United States); Landi, E.; Holst, B. van der; Sokolov, I. V.; Gombosi, T. I., E-mail: roran@mit.edu [Atmospheric, Oceanic and Atmospheric Sciences, University of Michigan, 2455 Hayward, Ann Arbor, MI, 48109 (United States)

    2017-08-20

    We test the predictions of the Alfvén Wave Solar Model (AWSoM), a global wave-driven magnetohydrodynamic (MHD) model of the solar atmosphere, against high-resolution spectra emitted by the quiescent off-disk solar corona. AWSoM incorporates Alfvén wave propagation and dissipation in both closed and open magnetic field lines; turbulent dissipation is the only heating mechanism. We examine whether this mechanism is consistent with observations of coronal EUV emission by combining model results with the CHIANTI atomic database to create synthetic line-of-sight spectra, where spectral line widths depend on thermal and wave-related ion motions. This is the first time wave-induced line broadening is calculated from a global model with a realistic magnetic field. We used high-resolution SUMER observations above the solar west limb between 1.04 and 1.34 R {sub ⊙} at the equator, taken in 1996 November. We obtained an AWSoM steady-state solution for the corresponding period using a synoptic magnetogram. The 3D solution revealed a pseudo-streamer structure transversing the SUMER line of sight, which contributes significantly to the emission; the modeled electron temperature and density in the pseudo-streamer are consistent with those observed. The synthetic line widths and the total line fluxes are consistent with the observations for five different ions. Further, line widths that include the contribution from the wave-induced ion motions improve the correspondence with observed spectra for all ions. We conclude that the turbulent dissipation assumed in the AWSoM model is a viable candidate for explaining coronal heating, as it is consistent with several independent measured quantities.

  3. Shock-wave induced mechanoluminescence: A new technique for studying effects of shock pressure on crystals

    Energy Technology Data Exchange (ETDEWEB)

    Chandra, B.P.; Parganiha, S.; Sonwane, V.D. [School of Studies in Physics and Astrophysics, Pt. Ravishankar Shukla University, Raipur 492010, Chhattisgarh (India); Chandra, V.K. [Department of Electrical and Electronics Engineering, Chhatrapati Shivaji Institute of Technology, Shivaji Nagar, Kolihapuri, Durg 491001, Chhattisgarh (India); Jha, Piyush, E-mail: piyushjha22@rediffmail.com [Department of Applied Physics, Raipur Institute of Technology, Chhatauna, Mandir Hasuad, Raipur 492101, Chhattisgarh (India); Baghel, R.N. [School of Studies in Physics and Astrophysics, Pt. Ravishankar Shukla University, Raipur 492010, Chhattisgarh (India)

    2016-10-15

    The impact of a projectile propelled to velocities in the range of 0.5–2.5 km/s on to a target (X-cut quartz crystal) produces shock waves travelling at velocity of nearly 10 km/s in target, in which intense mechanoluminescence (ML) pulses of microsecond duration are produced, both in compression and post-compression conditions. The piezoelectric field produced due to surface charges of fractured target, causes band bending and subsequently, the free charge carriers are generated in the respective bands and the emission of ML occurs. The ML appears after a delay time t{sub th} whose value decreases with increasing value of the shock pressure. Initially, the ML intensity increases with the shock pressure because of the creation of more surfaces; however, for higher values of the shock pressure, the ML intensity tends to attain a saturation value because of the hardening of the crystals due to the creation of small crystallites in which the creation of new surfaces becomes difficult. The ratio between peak ML intensity in the uncompressed region and the maximum ML intensity in the compressed region decreases with increasing shock pressure because more defects produced at high pressure generate higher barrier for the relaxation of blocked cracks under compression. The expressions derived for characteristics of shock-induced ML are able to explain satisfactorily the experimental results. Shock-wave velocity, shock pressure, transit time, lifetime of electrons in conduction band, etc. can be determined by the shock-induced ML.As such, the shock-induced ML provides a new optical technique for the studies of materials under shock pressure.

  4. Ring interferometry

    CERN Document Server

    Malykin, Grigorii B; Zhurov, Alexei

    2013-01-01

    This monograph is devoted to the creation of a comprehensive formalism for quantitative description of polarized modes' linear interaction in modern single-mode optic fibers. The theory of random connections between polarized modes, developed in the monograph, allows calculations of the zero shift deviations for a fiber ring interferometer. The monograph addresses also the

  5. Experimental and numerical investigations of shock and shear wave propagation induced by femtosecond laser irradiation in epoxy resins

    International Nuclear Information System (INIS)

    Ecault, Romain; Touchard, Fabienne; Boustie, Michel; Berthe, Laurent; Lescoute, Emilien; Sollier, Arnaud; Voillaume, Hubert

    2015-01-01

    In this work, original shock experiments are presented. Laser-induced shock and shear wave propagations have been observed in an epoxy resin, in the case of femtosecond laser irradiation. A specific time-resolved shadowgraphy setup has been developed using the photoelasticimetry principle to enhance the shear wave observation. Shear waves have been observed in epoxy resin after laser irradiation. Their propagation has been quantified in comparison with the main shock propagation. A discussion, hinging on numerical results, is finally given to improve understanding of the phenomenon. (paper)

  6. Polarization Insensitivity in Double-Split Ring and Triple-Split Ring Terahertz Resonators

    International Nuclear Information System (INIS)

    Wu Qian-Nan; Lan Feng; Tang Xiao-Pin; Yang Zi-Qiang

    2015-01-01

    A modified double-split ring resonator and a modified triple-split ring resonator, which offer polarization-insensitive performance, are investigated, designed and fabricated. By displacing the two gaps of the conventional double-split ring resonator away from the center, the second resonant frequency for the 0° polarized wave and the resonant frequency for the 90° polarized wave become increasingly close to each other until they are finally identical. Theoretical and experimental results show that the modified double-split ring resonator and the modified triple-split ring resonator are insensitive to different polarized waves and show strong resonant frequency dips near 433 and 444 GHz, respectively. The results of this work suggest new opportunities for the investigation and design of polarization-dependent terahertz devices based on split ring resonators. (paper)

  7. An improved method to experimentally determine temperature and pressure behind laser-induced shock waves at low Mach numbers

    International Nuclear Information System (INIS)

    Hendijanifard, Mohammad; Willis, David A

    2011-01-01

    Laser-matter interactions are frequently studied by measuring the propagation of shock waves caused by the rapid laser-induced material removal. An improved method for calculating the thermo-fluid parameters behind shock waves is introduced in this work. Shock waves in ambient air, induced by pulsed Nd : YAG laser ablation of aluminium films, are measured using a shadowgraph apparatus. Normal shock solutions are applied to experimental data for shock wave positions and used to calculate pressure, temperature, and velocity behind the shock wave. Non-dimensionalizing the pressure and temperature with respect to the ambient values, the dimensionless pressure and temperature are estimated to be as high as 90 and 16, respectively, at a time of 10 ns after the ablation pulse for a laser fluence of F = 14.5 J cm -2 . The results of the normal shock solution and the Taylor-Sedov similarity solution are compared to show that the Taylor-Sedov solution under-predicts pressure when the Mach number of the shock wave is small. At a fluence of 3.1 J cm -2 , the shock wave Mach number is less than 3, and the Taylor-Sedov solution under-predicts the non-dimensional pressure by as much as 45%.

  8. Wave-current induced erosion of cohesive riverbanks in northern Manitoba, Canada

    Science.gov (United States)

    Kimiaghalam, N.; Clark, S.; Ahmari, H.; Hunt, J.

    2015-03-01

    The field of cohesive soil erosion is still not fully understood, in large part due to the many soil parameters that affect cohesive soil erodibility. This study is focused on two channels, 2-Mile and 8-Mile channels in northern Manitoba, Canada, that were built to connect Lake Winnipeg with Playgreen Lake and Playgreen Lake with Kiskikittogisu Lake, respectively. The banks of the channels consist of clay rich soils and alluvial deposits of layered clay, silts and sands. The study of erosion at the sites is further complicated because the flow-induced erosion is combined with the effects of significant wave action due to the large fetch length on the adjacent lakes, particularly Lake Winnipeg that is the seventh largest lake in North America. The study included three main components: field measurements, laboratory experiments and numerical modelling. Field measurements consisted of soil sampling from the banks and bed of the channels, current measurements and water sampling. Grab soil samples were used to measure the essential physical and electrochemical properties of the riverbanks, and standard ASTM Shelby tube samples were used to estimate the critical shear stress and erodibility of the soil samples using an erosion measurement device (EMD). Water samples were taken to estimate the sediment concentration profile and also to monitor changes in sediment concentration along the channels over time. An Acoustic Doppler Current Profiler (ADCP) was used to collect bathymetry and current data, and two water level gauges have been installed to record water levels at the entrance and outlet of the channels. The MIKE 21 NSW model was used to simulate waves using historical winds and measured bathymetry of the channels and lakes. Finally, results from the wave numerical model, laboratory tests and current measurement were used to estimate the effect of each component on erodibility of the cohesive banks.

  9. Wave-current induced erosion of cohesive riverbanks in northern Manitoba, Canada

    Directory of Open Access Journals (Sweden)

    N. Kimiaghalam

    2015-03-01

    Full Text Available The field of cohesive soil erosion is still not fully understood, in large part due to the many soil parameters that affect cohesive soil erodibility. This study is focused on two channels, 2-Mile and 8-Mile channels in northern Manitoba, Canada, that were built to connect Lake Winnipeg with Playgreen Lake and Playgreen Lake with Kiskikittogisu Lake, respectively. The banks of the channels consist of clay rich soils and alluvial deposits of layered clay, silts and sands. The study of erosion at the sites is further complicated because the flow-induced erosion is combined with the effects of significant wave action due to the large fetch length on the adjacent lakes, particularly Lake Winnipeg that is the seventh largest lake in North America. The study included three main components: field measurements, laboratory experiments and numerical modelling. Field measurements consisted of soil sampling from the banks and bed of the channels, current measurements and water sampling. Grab soil samples were used to measure the essential physical and electrochemical properties of the riverbanks, and standard ASTM Shelby tube samples were used to estimate the critical shear stress and erodibility of the soil samples using an erosion measurement device (EMD. Water samples were taken to estimate the sediment concentration profile and also to monitor changes in sediment concentration along the channels over time. An Acoustic Doppler Current Profiler (ADCP was used to collect bathymetry and current data, and two water level gauges have been installed to record water levels at the entrance and outlet of the channels. The MIKE 21 NSW model was used to simulate waves using historical winds and measured bathymetry of the channels and lakes. Finally, results from the wave numerical model, laboratory tests and current measurement were used to estimate the effect of each component on erodibility of the cohesive banks.

  10. Proxy records of Holocene storm events in coastal barrier systems: Storm-wave induced markers

    Science.gov (United States)

    Goslin, Jérôme; Clemmensen, Lars B.

    2017-10-01

    Extreme storm events in the coastal zone are one of the main forcing agents of short-term coastal system behavior. As such, storms represent a major threat to human activities concentrated along the coasts worldwide. In order to better understand the frequency of extreme events like storms, climate science must rely on longer-time records than the century-scale records of instrumental weather data. Proxy records of storm-wave or storm-wind induced activity in coastal barrier systems deposits have been widely used worldwide in recent years to document past storm events during the last millennia. This review provides a detailed state-of-the-art compilation of the proxies available from coastal barrier systems to reconstruct Holocene storm chronologies (paleotempestology). The present paper aims (I) to describe the erosional and depositional processes caused by storm-wave action in barrier and back-barrier systems (i.e. beach ridges, storm scarps and washover deposits), (ii) to understand how storm records can be extracted from barrier and back-barrier sedimentary bodies using stratigraphical, sedimentological, micro-paleontological and geochemical proxies and (iii) to show how to obtain chronological control on past storm events recorded in the sedimentary successions. The challenges that paleotempestology studies still face in the reconstruction of representative and reliable storm-chronologies using these various proxies are discussed, and future research prospects are outlined.

  11. Vortex shedding induced by a solitary wave propagating over a submerged vertical plate

    International Nuclear Information System (INIS)

    Lin Chang; Ho, T.-C.; Chang, S.-C.; Hsieh, S.-C.; Chang, K.-A.

    2005-01-01

    Experimental study was conducted on the vortex shedding process induced by the interaction between a solitary wave and a submerged vertical plate. Particle image velocimetry (PIV) was used for quantitative velocity measurement while a particle tracing technique was used for qualitative flow visualization. Vortices are generated at the tip of each side of the plate. The largest vortices at each side of the plate eventually grow to the size of the water depth. Although the fluid motion under the solitary wave is only translatory, vortices are shed in both the upstream and downstream directions due to the interaction of the generated vortices as well as the vortices with the plate and the bottom. The process can be divided into four phases: the formation of a separated shear layer, the generation and shedding of vortices, the formation of a vertical jet, and the impingement of the jet onto the free surface. Similarity velocity profiles were found both in the separated shear layer and in the vertical jet

  12. Influences of Gravity Waves on Convectively Induced Turbulence (CIT): A Review

    Science.gov (United States)

    Sharman, Robert D.; Trier, S. B.

    2018-03-01

    Thunderstorms are known to produce turbulence. Such turbulence is commonly referred to as convectively induced turbulence or CIT, and can be hazardous to aviation. Although this turbulence can occur both within and outside the convection, out-of-cloud CIT is particularly hazardous, since it occurs in clear air and cannot be seen by eye or onboard radar. Furthermore, due to its small scale and its ties to the underlying convection, it is very difficult to forecast. Guidelines for out-of-cloud CIT avoidance are available, but they are oversimplified and can be misleading. In the search for more appropriate and physically based avoidance guidelines, considerable research has been conducted in recent years on the nature of the phenomenon, and in particular, its connection to gravity waves generated by the convection. This paper reviews the advances in our understanding of out-of-cloud CIT and its relation to convective gravity waves, and provides several detailed examples of observed cases to elucidate some of the underlying dynamics.

  13. Direct measurement of density oscillation induced by a radio-frequency wave

    International Nuclear Information System (INIS)

    Yamada, T.; Ejiri, A.; Shimada, Y.; Oosako, T.; Tsujimura, J.; Takase, Y.; Kasahara, H.

    2007-01-01

    An O-mode reflectometer at a frequency of 25.85 GHz was applied to plasmas heated by the high harmonic fast wave (21 MHz) in the TST-2 spherical tokamak. An oscillation in the phase of the reflected microwave in the rf range was observed directly for the first time. In TST-2, the rf (250 kW) induced density oscillation depends mainly on the poloidal rf electric field, which is estimated to be about 0.2 kV/m rms by the reflectometer measurement. Sideband peaks separated in frequency by ion cyclotron harmonics from 21 MHz, and peaks at ion cyclotron harmonics which are suggested to be quasimodes generated by parametric decay, were detected

  14. DC current in the collisionless limit induced by a travelling wave

    International Nuclear Information System (INIS)

    Midzuno, Yukio; Fukuda, Masaji.

    1977-03-01

    The DC current induced by a Travelling Wave is calculated on the basis of the assumption that the distribution function of electrons in the collisionless limit should be determined by a condition derived from the nature of the collision operator, as in the case of the calculation of the neoclassical transport in a torus. The resultant net current is found to have the same parameter dependence as the one derived in a previous analysis, in which we assumed the initial distribution of electrons to be uniform and isotropic Maxwellian. The numerical coefficient is found, however, to be a little different from the previous one. The importance of the accurate matching of the distribution function of untrapped particles to the Maxwellian one for large velocity is demonstrated. (auth.)

  15. Extreme value prediction of the wave-induced vertical bending moment in large container ships

    DEFF Research Database (Denmark)

    Andersen, Ingrid Marie Vincent; Jensen, Jørgen Juncher

    2015-01-01

    increase the extreme hull girder response significantly. Focus in the present paper is on the influence of the hull girder flexibility on the extreme response amidships, namely the wave-induced vertical bending moment (VBM) in hogging, and the prediction of the extreme value of the same. The analysis...... in the present paper is based on time series of full scale measurements from three large container ships of 8600, 9400 and 14000 TEU. When carrying out the extreme value estimation the peak-over-threshold (POT) method combined with an appropriate extreme value distribution is applied. The choice of a proper...... threshold level as well as the statistical correlation between clustered peaks influence the extreme value prediction and are taken into consideration in the present paper....

  16. Laser Structuring of Thin Layers for Flexible Electronics by a Shock Wave-induced Delamination Process

    Science.gov (United States)

    Lorenz, Pierre; Ehrhardt, Martin; Zimmer, Klaus

    The defect-free laser-assisted structuring of thin films on flexible substrates is a challenge for laser methods. However, solving this problem exhibits an outstanding potential for a pioneering development of flexible electronics. Thereby, the laser-assisted delamination method has a great application potential. At the delamination process: the localized removal of the layer is induced by a shock wave which is produced by a laser ablation process on the rear side of the substrate. In this study, the thin-film patterning process is investigated for different polymer substrates dependent on the material and laser parameters using a KrF excimer laser. The resultant structures were studied by optical microscopy and white light interferometry (WLI). The delamination process was tested at different samples (indium tin oxide (ITO) on polyethylene terephthalate (PET), epoxy-based negative photoresist (SU8) on polyimide (PI) and indium tin oxide/copper indium gallium selenide/molybdenum (ITO/CIGS/Mo) on PI.

  17. Controllable ultra-narrow fluorescence and six-wave mixing under double electromagnetically induced transparency

    International Nuclear Information System (INIS)

    Wang, Z G; Zhang, Z Y; Che, J L; Zhang, Y Z; Li, C B; Zheng, H B; Zhang, Y P

    2013-01-01

    We report the first observation of six-wave mixing (SWM) and fluorescence signals in an electromagnetically induced transparency (EIT) window. Several remarkable advantages are described. First, multiple bright and dark states are simultaneously observed due to enhancement or suppression of the SWM signal. Second, ultra-narrow fluorescence, much narrower than the EIT window, is experimentally obtained. Third, the ultra-narrow fluorescence can also generate Autler–Townes splitting on scanning the coupling beam. Fourth, a double-peak EIT window is obtained using the nest-dressing scheme. Such studies concerning SWM and fluorescence have applications in optical switching, multi-channel communication and narrowband and long-range quantum communication. (letter)

  18. Shock wave emission from laser-induced cavitation bubbles in polymer solutions.

    Science.gov (United States)

    Brujan, Emil-Alexandru

    2008-09-01

    The role of extensional viscosity on the acoustic emission from laser-induced cavitation bubbles in polymer solutions and near a rigid boundary is investigated by acoustic measurements. The polymer solutions consist of a 0.5% polyacrylamide (PAM) aqueous solution with a strong elastic component and a 0.5% carboxymethylcellulose (CMC) aqueous solution with a weak elastic component. A reduction of the maximum amplitude of the shock wave pressure and a prolongation of the oscillation period of the bubble were found in the elastic PAM solution. It might be caused by an increased resistance to extensional flow which is conferred upon the liquid by the polymer additive. In both polymer solutions, however, the shock pressure decays proportionally to r(-1) with increasing distance r from the emission centre.

  19. Double cascade turbulence and Richardson dispersion in a horizontal fluid flow induced by Faraday waves.

    Science.gov (United States)

    von Kameke, A; Huhn, F; Fernández-García, G; Muñuzuri, A P; Pérez-Muñuzuri, V

    2011-08-12

    We report the experimental observation of Richardson dispersion and a double cascade in a thin horizontal fluid flow induced by Faraday waves. The energy spectra and the mean spectral energy flux obtained from particle image velocimetry data suggest an inverse energy cascade with Kolmogorov type scaling E(k) ∝ k(γ), γ ≈ -5/3 and an E(k) ∝ k(γ), γ ≈ -3 enstrophy cascade. Particle transport is studied analyzing absolute and relative dispersion as well as the finite size Lyapunov exponent (FSLE) via the direct tracking of real particles and numerical advection of virtual particles. Richardson dispersion with ∝ t(3) is observed and is also reflected in the slopes of the FSLE (Λ ∝ ΔR(-2/3)) for virtual and real particles.

  20. A Numerical Study on the Screening of Blast-Induced Waves for Reducing Ground Vibration

    Science.gov (United States)

    Park, Dohyun; Jeon, Byungkyu; Jeon, Seokwon

    2009-06-01

    Blasting is often a necessary part of mining and construction operations, and is the most cost-effective way to break rock, but blasting generates both noise and ground vibration. In urban areas, noise and vibration have an environmental impact, and cause structural damage to nearby structures. Various wave-screening methods have been used for many years to reduce blast-induced ground vibration. However, these methods have not been quantitatively studied for their reduction effect of ground vibration. The present study focused on the quantitative assessment of the effectiveness in vibration reduction of line-drilling as a screening method using a numerical method. Two numerical methods were used to analyze the reduction effect toward ground vibration, namely, the “distinct element method” and the “non-linear hydrocode.” The distinct element method, by particle flow code in two dimensions (PFC 2D), was used for two-dimensional parametric analyses, and some cases of two-dimensional analyses were analyzed three-dimensionally using AUTODYN 3D, the program of the non-linear hydrocode. To analyze the screening effectiveness of line-drilling, parametric analyses were carried out under various conditions, with the spacing, diameter of drill holes, distance between the blasthole and line-drilling, and the number of rows of drill holes, including their arrangement, used as parameters. The screening effectiveness was assessed via a comparison of the vibration amplitude between cases both with and without screening. Also, the frequency distribution of ground motion of the two cases was investigated through fast Fourier transform (FFT), with the differences also examined. From our study, it was concluded that line-drilling as a screening method of blast-induced waves was considerably effective under certain design conditions. The design details for field application have also been proposed.

  1. Investigation of the Effects of Ship Induced Waves on the Littoral Zone with Field Measurements and CFD Modeling

    Directory of Open Access Journals (Sweden)

    Gábor Fleit

    2016-07-01

    Full Text Available Waves induced by ship movement might be harmful for the habitat in the littoral zone of rivers due to the temporally increasing bed shear stress, the high-energy breaking waves and the consequently related detachment of benthic animals. In order to understand the complex hydrodynamic phenomena resulting from littoral waves, we present the testing of a novel methodology that incorporates field observations and numerical tools. The study is performed at a section of the Danube River in Hungary and analyzes the influence of different ship types. The field methods consist of parallel acoustic measurements (using Acoustic Doppler Velocimetry (ADV conducted at the riverbed and Large Scale Particle Image Velocimetry (LSPIV of the water surface. ADV measurements provided near-bed flow velocities based on which the wave induced currents and local bed shear stress could be estimated. The LSPIV was able to quantify the dynamics of the breaking waves along the bank. Furthermore, computational fluid dynamics (CFD modeling was successfully applied to simulate the propagation and the breaking of littoral waves. The used techniques complement each other well and their joint application provides an adequate tool to support the improvement of riverine habitats.

  2. Spiral and Rotor Patterns Produced by Fairy Ring Fungi

    Science.gov (United States)

    Karst, N.; Dralle, D.; Thompson, S. E.

    2015-12-01

    Soil fungi fill many essential ecological and biogeochemical roles, e.g. decomposing litter, redistributing nutrients, and promoting biodiversity. Fairy ring fungi offer a rare glimpse into the otherwise opaque spatiotemporal dynamics of soil fungal growth, because subsurface mycelial patterns can be inferred from observations at the soil's surface. These observations can be made directly when the fungi send up fruiting bodies (e.g., mushrooms and toadstools), or indirectly via the effect the fungi have on neighboring organisms. Grasses in particular often temporarily thrive on the nutrients liberated by the fungus, creating bands of rich, dark green turf at the edge of the fungal mat. To date, only annular (the "ring" in fairy ring) and arc patterns have been described in the literature. We report observations of novel spiral and rotor pattern formation in fairy ring fungi, as seen in publically available high-resolution aerial imagery of 22 sites across the continental United States. To explain these new behaviors, we first demonstrate that a well-known model describing fairy ring formation is equivalent to the Gray-Scott reaction-diffusion model, which is known to support a wide range of dynamical behaviors, including annular traveling waves, rotors, spirals, and stable spatial patterns including spots and stripes. Bifurcation analysis and numerical simulation are then used to define the region of parameter space that supports spiral and rotor formation. We find that this region is adjacent to one within which typical fairy rings develop. Model results suggest simple experimental procedures that could potentially induce traditional ring structures to exhibit rotor or spiral dynamics. Intriguingly, the Gray-Scott model predicts that these same procedures could be used to solicit even richer patterns, including spots and stripes, which have not yet been identified in the field.

  3. 4D Density Determination of NH Radicals in an MSE Microplasma Combining Planar Laser Induced Fluorescence and Cavity Ring-Down Spectroscopy

    Science.gov (United States)

    Visser, Martin; Schenk, Andreas; Gericke, Karl-Heinz

    2010-10-01

    An application of microplasmas is surface modification under mild conditions and of small, well defined areas. For this, an understanding of the plasma composition is of importance. First results of our work on the production and detection of NH radicals in a capacitively coupled radio frequency (RF) microplasma are presented. A microstructured comb electrode was used to generate a glow discharge in a hydrogen/nitrogen gas mixture by applying 13.56 MHz RF voltage. The techniques of planar laser induced fluorescence (PLIF) and cavity ring-down spectroscopy (CRDS) are used for space and time resolved, quantitative detection of the NH radical in the plasma. The rotational temperature was determined to be 820 K and, the density 5.1×1012 cm3. Also, time dependent behaviour of the NH production was observed.

  4. 4D Density Determination of NH Radicals in an MSE Microplasma Combining Planar Laser Induced Fluorescence and Cavity Ring-Down Spectroscopy

    International Nuclear Information System (INIS)

    Visser, Martin; Schenk, Andreas; Gericke, Karl-Heinz

    2010-01-01

    An application of microplasmas is surface modification under mild conditions and of small, well defined areas. For this, an understanding of the plasma composition is of importance. First results of our work on the production and detection of NH radicals in a capacitively coupled radio frequency (RF) microplasma are presented. A microstructured comb electrode was used to generate a glow discharge in a hydrogen/nitrogen gas mixture by applying 13.56 MHz RF voltage. The techniques of planar laser induced fluorescence (PLIF) and cavity ring-down spectroscopy (CRDS) are used for space and time resolved, quantitative detection of the NH radical in the plasma. The rotational temperature was determined to be 820 K and, the density 5.1x10 12 cm 3 . Also, time dependent behaviour of the NH production was observed.

  5. Characteristics of brain injury induced by shock wave propagation in solids after underwater explosion in rats

    Directory of Open Access Journals (Sweden)

    Xin-ling LI

    2016-09-01

    Full Text Available Objective  To observe the characteristics of rat brain injury induced by shock wave propagation in solids resulting from underwater explosion and explore the related mechanism. Methods  Explosion source outside the simulated ship cabin underwater was detonated for establishing a model of brain injury in rats by shock wave propagation in solid; 72 male SD rats were randomly divided into normal control group (n=8, injury group 1 (600mg RDX paper particle explosion source, n=32, injury group 2 (800mg RDX paper particle explosion source, n=32. The each injury group was randomly divided into 4 subgroups (n=8, 3, 6, 24 and 72h groups. The division plate as a whole and the head of 8 rats in each injury group were measured for the peak value of the solid shock wave, its rising time and the duration time of shock wave propagation in solid. To observe the physiological changes of animals after injury, plasma samples were collected for determination of brain damage markers, NSE and S-100β. All the animals were sacrificed, the right hemisphere of the brain was taken in each group of animals, weighting after baking, and the brain water content was calculated. Pathological examination was performed for left cerebral hemisphere in 24-h group. The normal pyramidal cells in the hippocampal CA1 region were counted. Results  The peak value, rising time and duration time of shock wave propagation on the division plate and head were 1369.74±91.70g, 0.317±0.037ms and 24.85±2.53ms, 26.83±3.09g, 0.901±0.077ms and 104.21±6.26ms respectively in injury group 1, 1850.11±83.86g, 0.184±0.031ms and 35.61±2.66ms, 39.75±3.14g, 0.607±0.069ms and 132.44±7.17ms in injury group 2 (P<0.01. After the injury, there was no abnormality in the anatomy, and brain damage markers NSE, S-100β increased, reached the peak at 24 h, and they were highest in injury group 2 and lowest in control group with a statistically significant difference (P<0.05. The brain water content

  6. Ionospheric Bow Wave Induced by the Moon Shadow Ship Over the Continent of United States on 21 August 2017

    Science.gov (United States)

    Sun, Yang-Yi; Liu, Jann-Yenq; Lin, Charles Chien-Hung; Lin, Chi-Yen; Shen, Ming-Hsueh; Chen, Chieh-Hung; Chen, Chia-Hung; Chou, Min-Yang

    2018-01-01

    A moon shadow of the total solar eclipse swept through the continent of United States (CONUS) from west to east on 21 August 2017. Massive total electron content (integration of electron density from 0 km to 20,200 km altitude) observations from 2,255 ground-based Global Navigation Satellite System receivers show that the moon shadow ship generates a great ionospheric bow wave front which extends 1,500 km away from the totality path covering the entire CONUS. The bow wave front consists of the acoustic shock wave due to the supersonic/near-supersonic moon shadow ship and the significant plasma recombination due to the reduction in solar irradiation within the shadow area. The deep bow wave trough (-0.02 total electron content unit (1 TECU = 1016 el m-2) area) nearly coincides with the 100% obscuration moving along the totality path over the CONUS through the entire eclipse period. The supersonic moon shadow ship induces a bow wave crest in front of the ship ( 80% obscuration). It is the first time to find the acoustic shock wave-formed bow wave trough and crest near the totality.

  7. Surface Waves and Flow-Induced Oscillations along an Underground Elliptic Cylinder Filled with a Viscous Fluid

    Science.gov (United States)

    Sakuraba, A.

    2015-12-01

    I made a linear analysis of flow-induced oscillations along an underground cylindrical conduit with an elliptical cross section on the basis of the hypothesis that volcanic tremor is a result of magma movement through a conduit. As a first step to understand how the self oscillation occurs because of magma flow, I investigated surface wave propagation and attenuation along an infinitely long fluid-filled elliptic cylinder in an elastic medium. The boundary element method is used to obtain the two-dimensional wave field around the ellipse in the frequency-wavenumber domain. When the major axis is much greater than the minor axis of the ellipse, we obtain the analytic form of the dispersion relation of both the crack-wave mode (Korneev 2008, Lipovsky & Dunham 2015) and the Rayleigh-wave mode with flexural deformation. The crack-wave mode generally has a slower phase speed and a higher attenuation than the Rayleigh-wave mode. In the long-wavelength limit, the crack-wave mode disappears because of fluid viscosity, but the Rayleigh-wave mode exists with a constant Q-value that depends on viscosity. When the aspect ratio of the ellipse is finite, the surface waves can basically be understood as those propagating along a fluid pipe. The flexural mode does exist even when the wavelength is much longer than the major axis, but its phase speed coincides with that of the surrounding S-wave (Randall 1991). As its attenuation is zero in the long-wavelength limit, the flexural mode differs in nature from surface wave. I also obtain a result on linear stability of viscous flow through an elliptic cylinder. In this analysis, I made an assumption that the fluid inertia is so small that the Stokes equation can be used. As suggested by the author's previous study (Sakuraba & Yamauchi 2014), the flexural (Rayleigh-wave) mode is destabilized at a critical flow speed that decreases with the wavelength. However, when the wavelength is much greater than the major axis of the ellipse, the

  8. Continuum contribution to excitonic four-wave mixing due to interaction-induced nonlinearities: A numerical study

    DEFF Research Database (Denmark)

    Sayed, Karim El; Birkedal, Dan; Vadim, Lyssenko

    1997-01-01

    We present a theoretical investigation of ultrafast transient four-wave mixing (FWM) of GaAs quantum wells for coherent excitation of excitons and a large number of continuum states. It is shown that in this case the line shape of the FWM signal is drastically altered due to an interaction-induce...

  9. New edge magnetoplasmon for a two-dimensional electron gas in a ring geometry

    International Nuclear Information System (INIS)

    Proetto, C.R.

    1992-09-01

    The dynamical response of a classical two-dimensional electron gas confined in a ring geometry under a perpendicular magnetic field is analysed. Within the hydrodynamical approach and in the strong magnetic field limit, a new set of antidot edge magnetoplasmons is obtained, corresponding to density oscillations circulating along the inner boundary of the ring and whose frequency increases with magnetic field. The associated self-induced distribution of densities and currents are presented, together with an analysis of the size dependence of these perimeter waves. (author). 15 refs, 4 figs

  10. TMS-induced cortical potentiation during wakefulness locally increases slow wave activity during sleep.

    Directory of Open Access Journals (Sweden)

    Reto Huber

    2007-03-01

    Full Text Available Sleep slow wave activity (SWA is thought to reflect sleep need, increasing in proportion to the length of prior wakefulness and decreasing during sleep. However, the process responsible for SWA regulation is not known. We showed recently that SWA increases locally after a learning task involving a circumscribed brain region, suggesting that SWA may reflect plastic changes triggered by learning.To test this hypothesis directly, we used transcranial magnetic stimulation (TMS in conjunction with high-density EEG in humans. We show that 5-Hz TMS applied to motor cortex induces a localized potentiation of TMS-evoked cortical EEG responses. We then show that, in the sleep episode following 5-Hz TMS, SWA increases markedly (+39.1+/-17.4%, p<0.01, n = 10. Electrode coregistration with magnetic resonance images localized the increase in SWA to the same premotor site as the maximum TMS-induced potentiation during wakefulness. Moreover, the magnitude of potentiation during wakefulness predicts the local increase in SWA during sleep.These results provide direct evidence for a link between plastic changes and the local regulation of sleep need.

  11. Acoustic pressure waves induced in human heads by RF pulses from high-field MRI scanners.

    Science.gov (United States)

    Lin, James C; Wang, Zhangwei

    2010-04-01

    The current evolution toward greater image resolution from magnetic resonance image (MRI) scanners has prompted the exploration of higher strength magnetic fields and use of higher levels of radio frequencies (RFs). Auditory perception of RF pulses by humans has been reported during MRI with head coils. It has shown that the mechanism of interaction for the auditory effect is caused by an RF pulse-induced thermoelastic pressure wave inside the head. We report a computational study of the intensity and frequency of thermoelastic pressure waves generated by RF pulses in the human head inside high-field MRI and clinical scanners. The U.S. Food and Drug Administration (U.S. FDA) guides limit the local specific absorption rate (SAR) in the body-including the head-to 8 W kg(-1). We present results as functions of SAR and show that for a given SAR the peak acoustic pressures generated in the anatomic head model were essentially the same at 64, 300, and 400 MHz (1.5, 7.0, and 9.4 T). Pressures generated in the anatomic head are comparable to the threshold pressure of 20 mPa for sound perception by humans at the cochlea for 4 W kg(-1). Moreover, results indicate that the peak acoustic pressure in the brain is only 2 to 3 times the auditory threshold at the U.S. FDA guideline of 8 W kg(-1). Even at a high SAR of 20 W kg(-1), where the acoustic pressure in the brain could be more than 7 times the auditory threshold, the sound pressure levels would not be more than 17 db above threshold of perception at the cochlea.

  12. Character, distribution, and ecological significance of storm wave-induced scour in Rhode Island Sound, USA

    Science.gov (United States)

    McMullen, Katherine Y.; Poppe, Lawrence J.; Parker, Castle E.

    2015-01-01

    Multibeam bathymetry, collected during NOAA hydrographic surveys in 2008 and 2009, is coupled with USGS data from sampling and photographic stations to map the seabed morphology and composition of Rhode Island Sound along the US Atlantic coast, and to provide information on sediment transport and benthic habitats. Patchworks of scour depressions cover large areas on seaward-facing slopes and bathymetric highs in the sound. These depressions average 0.5-0.8 m deep and occur in water depths reaching as much as 42 m. They have relatively steep well-defined sides and coarser-grained floors, and vary strongly in shape, size, and configuration. Some individual scour depressions have apparently expanded to combine with adjacent depressions, forming larger eroded areas that commonly contain outliers of the original seafloor sediments. Where cobbles and scattered boulders are present on the depression floors, the muddy Holocene sands have been completely removed and the winnowed relict Pleistocene deposits exposed. Low tidal-current velocities and the lack of obstacle marks suggest that bidirectional tidal currents alone are not capable of forming these features. These depressions are formed and maintained under high-energy shelf conditions owing to repetitive cyclic loading imposed by high-amplitude, long-period, storm-driven waves that reduce the effective shear strength of the sediment, cause resuspension, and expose the suspended sediments to erosion by wind-driven and tidal currents. Because epifauna dominate on gravel floors of the depressions and infauna are prevalent in the finer-grained Holocene deposits, it is concluded that the resultant close juxtaposition of silty sand-, sand-, and gravel-dependent communities promotes regional faunal complexity. These findings expand on earlier interpretations, documenting how storm wave-induced scour produces sorted bedforms that control much of the benthic geologic and biologic diversity in Rhode Island Sound.

  13. Supersymmetric rings in field theory

    International Nuclear Information System (INIS)

    Blanco-Pillado, Jose J.; Redi, Michele

    2006-01-01

    We study the dynamics of BPS string-like objects obtained by lifting monopole and dyon solutions of N = 2 Super-Yang-Mills theory to five dimensions. We present exact traveling wave solutions which preserve half of the supersymmetries. Upon compactification this leads to macroscopic BPS rings in four dimensions in field theory. Due to the fact that the strings effectively move in six dimensions the same procedure can also be used to obtain rings in five dimensions by using the hidden dimension

  14. Modelling of Wave Attenuation Induced by Multi-Purpose Floating Structures

    DEFF Research Database (Denmark)

    Stratigaki, Vasiliki; Troch, Peter; Stallard, Tim

    2014-01-01

    , polychromatic, long- and short-crested irregular waves), WEC response and modification of the wave field have been measured to provide data for the understanding of WEC farm interactions and for the evaluation of farm interaction numerical models. A first extensive wave farm database is established...

  15. Morning sector drift-bounce resonance driven ULF waves observed in artificially-induced HF radar backscatter

    Directory of Open Access Journals (Sweden)

    L. J. Baddeley

    Full Text Available HF radar backscatter, which has been artificially-induced by a high power RF facility such as the EISCAT heater at Tromsø, has provided coherent radar ionospheric electric field data of unprecedented temporal resolution and accuracy. Here such data are used to investigate ULF wave processes observed by both the CUTLASS HF radars and the EISCAT UHF radar. Data from the SP-UK-OUCH experiment have revealed small-scale (high azimuthal wave number, m -45 waves, predominantly in the morning sector, thought to be brought about by the drift-bounce resonance processes. Conjugate observations from the Polar CAM-MICE instrument indicate the presence of a non-Maxwellian ion distribution function. Further statistical analysis has been undertaken, using the Polar TIMAS instrument, to reveal the prevalence and magnitude of the non-Maxwellian energetic particle populations thought to be responsible for generating these wave types.

    Key words. Ionosphere (active experiments; wave-particle interactions Magnetospheric physics (MHD waves and instabilities

  16. Morning sector drift-bounce resonance driven ULF waves observed in artificially-induced HF radar backscatter

    Directory of Open Access Journals (Sweden)

    L. J. Baddeley

    2002-09-01

    Full Text Available HF radar backscatter, which has been artificially-induced by a high power RF facility such as the EISCAT heater at Tromsø, has provided coherent radar ionospheric electric field data of unprecedented temporal resolution and accuracy. Here such data are used to investigate ULF wave processes observed by both the CUTLASS HF radars and the EISCAT UHF radar. Data from the SP-UK-OUCH experiment have revealed small-scale (high azimuthal wave number, m -45 waves, predominantly in the morning sector, thought to be brought about by the drift-bounce resonance processes. Conjugate observations from the Polar CAM-MICE instrument indicate the presence of a non-Maxwellian ion distribution function. Further statistical analysis has been undertaken, using the Polar TIMAS instrument, to reveal the prevalence and magnitude of the non-Maxwellian energetic particle populations thought to be responsible for generating these wave types.Key words. Ionosphere (active experiments; wave-particle interactions Magnetospheric physics (MHD waves and instabilities

  17. The Aharonov-Bohm effect in a side-gated graphene ring

    International Nuclear Information System (INIS)

    Huefner, Magdalena; Molitor, Francoise; Jacobsen, Arnhild; Pioda, Alessandro; Stampfer, Christoph; Ensslin, Klaus; Ihn, Thomas

    2010-01-01

    We investigate the magnetoresistance of a side-gated ring structure etched out of single-layer graphene. We observe Aharonov-Bohm oscillations with about 5% visibility. We are able to change the relative phases of the wave functions in the interfering paths and induce phase jumps of π in the Aharonov-Bohm oscillations by changing the voltage applied to the side gate or the back gate. The observed data can be interpreted within existing models for 'dirty metals'.

  18. Extreme Value Predictions for Wave- and Wind-induced Loads on Floating Offshore Wind Turbines using FORM

    DEFF Research Database (Denmark)

    Joensen, Sunvard; Jensen, Jørgen Juncher; Mansour, Alaa E.

    2007-01-01

    duration of the time domain simulations needed (typically 60-300s to cover the hy-drodynamic memory effects in the response) the calcu-lation of the mean out-crossing rates of a given response are very fast. Thus complicated non-linear effects can be included. The FORM analysis also identifies the most...... probable wave episodes leading to given re-sponses. As an example the motions of floating foundations for offshore wind turbines are analysed taking into consid-eration both the wave and wind induced loads and con-sidering different mooring systems. The possible large horizontal motions make it important...

  19. Predictions of Resuspension of Highway Detention Pond Deposits in Interrain Event Periods due to Wind-Induced Currents and Waves

    DEFF Research Database (Denmark)

    Bentzen, Thomas Ruby; Larsen, Torben; Rasmussen, Michael R.

    2009-01-01

    -shear stress induced by the return flow near the bed and waves both generated by the wind. Wind statistics for 30 years have been applied for prediction of the annual discharged bulk of suspended solids and associated pollutants; fluoranthene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, dibenzo......(a,h)anthracene and indeno(1,2,3-cd)pyrene (PAHs) and the heavy metals of cadmium, chromium, copper, lead, nickel, and zinc. The current and wave-generated bed-shear stresses entail a discharged bulk of pollutants corresponding to approximately 10% of the annual accumulation of pollutants in the present pond due...

  20. Noradrenaline decreases spike voltage threshold and induces electrographic sharp waves in turtle medial cortex in vitro.

    Science.gov (United States)

    Lorenzo, Daniel; Velluti, Julio C

    2004-01-01

    The noradrenergic modulation of neuronal properties has been described at different levels of the mammalian brain. Although the anatomical characteristics of the noradrenergic system are well known in reptiles, functional data are scarce. In our study the noradrenergic modulation of cortical electrogenesis in the turtle medial cortex was studied in vitro using a combination of field and intracellular recordings. Turtle EEG consists of a low voltage background interspersed by spontaneous large sharp waves (LSWs). Noradrenaline (NA, 5-40 microM) induced (or enhanced) the generation of LSWs in a dose-dependent manner. Pharmacological experiments suggest the participation of alpha and beta receptors in this effect. In medial cortex neurons NA induced a hyperpolarization of the resting potential and a decrease of input resistance. Both effects were observed also after TTX treatment. Noradrenaline increased the response of the cells to depolarizing pulses, resulting in an upward shift of the frequency/current relation. In most cells the excitability change was mediated by a decrease of the spike voltage threshold resulting in the reduction of the amount of depolarization needed to fire the cell (voltage threshold minus resting potential). As opposed to the mechanisms reported in mammalian neurons, no changes in the frequency adaptation or the post-train afterhyperpolarization were observed. The NA effects at the cellular level were not reproduced by noradrenergic agonists. Age- and species-dependent properties in the pharmacology of adrenergic receptors could be involved in this result. Cellular effects of NA in turtle cortex are similar to those described in mammals, although the increase in cellular excitability seems to be mediated by a different mechanism. Copyright 2004 S. Karger AG, Basel

  1. Long-wave, infrared laser-induced breakdown (LIBS) spectroscopy emissions from energetic materials.

    Science.gov (United States)

    Yang, Clayton S-C; Brown, Ei E; Hommerich, Uwe; Jin, Feng; Trivedi, Sudhir B; Samuels, Alan C; Snyder, A Peter

    2012-12-01

    Laser-induced breakdown spectroscopy (LIBS) has shown great promise for applications in chemical, biological, and explosives sensing and has significant potential for real-time standoff detection and analysis. In this study, LIBS emissions were obtained in the mid-infrared (MIR) and long-wave infrared (LWIR) spectral regions for potential applications in explosive material sensing. The IR spectroscopy region revealed vibrational and rotational signatures of functional groups in molecules and fragments thereof. The silicon-based detector for conventional ultraviolet-visible LIBS operations was replaced with a mercury-cadmium-telluride detector for MIR-LWIR spectral detection. The IR spectral signature region between 4 and 12 μm was mined for the appearance of MIR and LWIR-LIBS emissions directly indicative of oxygenated breakdown products as well as dissociated, and/or recombined sample molecular fragments. Distinct LWIR-LIBS emission signatures from dissociated-recombination sample molecular fragments between 4 and 12 μm are observed for the first time.

  2. Propagation characteristics of laser-induced stress wave in deep tissue for gene transfer

    International Nuclear Information System (INIS)

    Ando, Takahiro; Sato, Shunichi; Takano, Shinta; Ashida, Hiroshi; Obara, Minoru

    2009-01-01

    Propagation characteristics of laser-induced stress waves (LISWs) in tissue and their correlation with properties of gene transfection were investigated for targeted deep-tissue gene therapy. LISWs were generated by irradiating a laser-absorbing material with 532-nm Q-switched Nd:YAG laser pulses; a transparent plastic sheet was attached on the absorbing material for plasma confinement. Temporal pressure profiles of LISWs that were propagated through different thickness tissues were measured with a needle-type hydrophone and propagation of LISWs in water was visualized by shadowgraph technique. The measurements showed that at a laser fluence of 1.2 J/cm 2 with a laser spot diameter of 3 mm, flat wavefront was maintained for up to 5 mm in depth and peak pressure P decreased with increasing tissue thickness d; P was proportional to d -0.54 . Rat dorsal skin was injected with plasmid DNA coding for reporter gene, on which different numbers of excised skin(s) was/were placed, and LISWs were applied from the top of the skins. Efficient gene expression was observed in the skin under the 3 mm thick stacked skins, suggesting that deep-located tissue such as muscle can be transfected by transcutaneous application of LISWs.

  3. Finite element analysis of the shock waves induced in the liquid wall of a pellet fusion reactor

    International Nuclear Information System (INIS)

    Miya, K.; Iizuka, T.; Silverman, J.

    1985-01-01

    A shock wave induced in liquid metal is analyzed numerically by application of the finite element method. Since the governing equations of motion of the fluid are nonlinear, an incremental method is combined with the finite element method to obtain a convergent solution of the shock wave without an interaction technique. To demonstrate the validity of the method developed, shock wave problems in an inertial confinement spherical reactor with a liquid lithium ''waterfall'' are solved for two cases of surface heating due to soft x-ray absorption and bulk heating due to 14-MeV neutron absorption. The solution is based on a combination of the conservation equations for mass, energy, and momentum along with the following equation of state for liquid metals: p = P /sub b/ ((/rho///rho/ 0 ) /sup n/ - 1). Numerical results show that peak pressure induced in the liquid lithium is very high even for a comparatively small energy release E /sub TAU/ = 100 MJ/microexplosion of a pellet. Dynamic stress induced in a 5-cm-thick stainless steel pressure vessel is 1.14 x 10 3 MPa for the surface heating. The results show that the dynamic stress induced by bulk heating is superimposed on that due to surface heating within the same period. Two appropriate ways to reduce the high stress are application of two-phase flow of liquid lithium or an increase in the thickness of the pressure vessel

  4. Mitigation technologies for damage induced by pressure waves in high-power mercury spallation neutron sources (1). Material surface improvement

    International Nuclear Information System (INIS)

    Naoe, Takashi; Futakawa, Masatoshi; Wakui, Takashi; Kogawa, Hiroyuki; Shoubu, Takahisa; Takeuchi, Hirotsugu; Kawai, Masayoshi

    2008-01-01

    Liquid-mercury target systems for MW-class spallation neutron sources are being developed in the world. Proton beams will be used to induce the spallation reaction. At the moment the proton beam hits the target, pressure waves are generated in the mercury because of the abrupt heat deposition. The pressure waves interact with the target vessel leading to negative pressure that may cause cavitation along the vessel wall. Localized impacts by microjets and/or shock waves that are caused by cavitation bubble collapse impose pitting damage on the vessel wall. Bubble collapse behavior was observed by using a high-speed video camera, as well as simulated numerically. Localized impact due to cavitation bubble collapse was quantitatively estimated through comparison between numerical simulation and experiment. A novel surface treatment technique that consists of carburizing and nitriding processes was developed and the treatment condition was optimized to mitigate the pitting damage due to localized impacts. (author)

  5. Human gastric signet ring carcinoma (KATO-III) cell apoptosis induced by Vitex agnus-castus fruit extract through intracellular oxidative stress.

    Science.gov (United States)

    Ohyama, Kunio; Akaike, Takenori; Imai, Masahiko; Toyoda, Hiroo; Hirobe, Chieko; Bessho, Toshio

    2005-07-01

    We have previously reported that an ethanol extract of the dried ripe fruit of Vitex agnus-castus (Vitex) displays cytotoxic activity against certain kinds of human cancer cell line resulting in the induction of apoptosis. In this paper, we investigate the molecular mechanism of apoptosis induced by Vitex using a human gastric signet ring carcinoma cell line, KATO-III. DNA fragmentation was observed in Vitex-treated KATO-III cells in a time- and dose-dependent manner. DNA fragmentation was accompanied by the following phenomena: elevation in the level of hemeoxygenase-1 protein and thioredoxin reductase mRNA; repression of Mn-superoxide dismutase and catalase mRNAs; release of cytochrome c from mitochondria into the cytosol; activation of caspases-8, -9 and -3; decrease in the level of Bcl-2, Bcl-XL and Bid protein; increase in the level of Bad protein. The intracellular oxidized state, measured using 2',7'-dichlorofluorescin diacetate, increased after Vitex treatment. While the amount of intracellular GSH decreased significantly after treatment with Vitex, the level of GSSG was unaffected. Furthermore, no significant perturbation in the amount of proteins/mRNAs related to glutathione metabolism could be detected. These apoptotic alterations induced by exposure to Vitex were blocked by the presence of an anti-oxidative reagent, N-acetyl-l-cysteine, or the addition of exogenous GSH. Our results demonstrate that intracellular oxidative stress and mitochondrial membrane damage is responsible for Vitex-induced apoptosis, which may be mediated by a diminution of reduced type glutathione within the cell.

  6. Implementation of viscoelastic mud-induced energy attenuation in the third-generation wave model, SWAN

    Science.gov (United States)

    Beyramzade, Mostafa; Siadatmousavi, Seyed Mostafa

    2018-01-01

    The interaction of waves with fluid mud can dissipate the wave energy significantly over few wavelengths. In this study, the third-generation wave model, SWAN, was advanced to include attenuation of wave energy due to interaction with a viscoelastic fluid mud layer. The performances of implemented viscoelastic models were verified against an analytical solution and viscous formulations for simple one-dimensional propagation cases. Stationary and non-stationary test cases in the Surinam coast and the Atchafalaya Shelf showed that the inclusion of the mud-wave interaction term in the third-generation wave model enhances the model performance in real applications. A high value of mud viscosity (of the order of 0.1 m2/s) was required in both field cases to remedy model overestimation at high frequency ranges of the wave spectrum. The use of frequency-dependent mud viscosity value improved the performance of model, especially in the frequency range of 0.2-0.35 Hz in the wave spectrum. In addition, the mud-wave interaction might affect the high frequency part of the spectrum, and this part of the wave spectrum is also affected by energy transfer from wind to waves, even for the fetch lengths of the order of 10 km. It is shown that exclusion of the wind input term in such cases might result in different values for parameters of mud layer when inverse modeling procedure was employed. Unlike viscous models for wave-mud interaction, the inverse modeling results to a set of mud parameters with the same performance when the viscoelastic model is used. It provides an opportunity to select realistic mud parameters which are in more agreement with in situ measurements.

  7. Dependence of Whistler-mode Wave Induced Electron Precipitation on k-vector Direction.

    Science.gov (United States)

    Kulkarni, P.; Inan, U. S.; Bell, T. F.; Bortnik, J.

    2007-12-01

    Whistler-mode waves that are either spontaneously generated in-situ (i.e., chorus), or externally injected (lightning, VLF transmitters) are known to be responsible for the loss of radiation belt electrons. An important determinant in the quantification of this loss is the dependence of the cyclotron resonant pitch angle scattering on the initial wave normal angles of the driving waves. Inan et al. (U.S. Inan et al., Controlled precipitation of radiation belt electrons, Journal of Geophysical Research-Space Physics, 108 (A5), 1186, doi: 10.1029/2002JA009580, 2003.) suggested that the lifetime of > 1 MeV electrons in the inner radiation belts might be moderated by in situ injection of VLF whistler mode waves at frequencies of a few kHz. The formulation of Wang and Bell (T.N.C. Wang and T.F. Bell, Radiation resisitance of a short dipole immersed in a cold magnetoionic medium, Radio Science, 4(2), 167-177, February 1969) for an electric dipole antenna located in the inner magnetosphere established that most of the radiated power is concentrated in waves whose wave normal angles lie near the local resonance cone. Such waves, compared to those injected at less oblique initial wave normal angles, undergo several more magnetospheric reflections, persist in the magnetospheric cavity for longer periods of time, and resonate with electrons of higher energies. Accordingly, such waves may be highly effective in contributing to the loss of electrons from the inner belt and slot regions [Inan et al., 2006]. Nevertheless, it has been noted (Inan et al. [2006], Inan and Bell [1991] and Albert [1999]) that > 1 MeV electrons may not be effectively scattered by waves propagating with very high wave normal angles, due to the generally reduced gyroresonant diffusion coefficients for wave normals near the resonance cone. We use the Stanford 2D VLF raytracing program to determine the energetic electron pitch angle scattering and the precipitated flux signatures that would be detected for

  8. Ring magnet firing angle control

    International Nuclear Information System (INIS)

    Knott, M.J.; Lewis, L.G.; Rabe, H.H.

    1975-01-01

    A device is provided for controlling the firing angles of thyratrons (rectifiers) in a ring magnet power supply. A phase lock loop develops a smooth ac signal of frequency equal to and in phase with the frequency of the voltage wave developed by the main generator of the power supply. A counter that counts from zero to a particular number each cycle of the main generator voltage wave is synchronized with the smooth AC signal of the phase lock loop. Gates compare the number in the counter with predetermined desired firing angles for each thyratron and with coincidence the proper thyratron is fired at the predetermined firing angle

  9. Rogue wave train generation in a metamaterial induced by cubic-quintic nonlinearities and second-order dispersion

    Science.gov (United States)

    Essama, Bedel Giscard Onana; Atangana, Jacques; Frederick, Biya Motto; Mokhtari, Bouchra; Eddeqaqi, Noureddine Cherkaoui; Kofane, Timoleon Crepin

    2014-09-01

    We investigate the behavior of the electromagnetic wave that propagates in a metamaterial for negative index regime. Second-order dispersion and cubic-quintic nonlinearities are taken into account. The behavior obtained for negative index regime is compared to that observed for absorption regime. The collective coordinates technique is used to characterize the light pulse intensity profile at some frequency ranges. Five frequency ranges have been pointed out. The perfect combination of second-order dispersion and cubic nonlinearity leads to a robust soliton at each frequency range for negative index regime. The soliton peak power progressively decreases for absorption regime. Further, this peak power also decreases with frequency. We show that absorption regime can induce rogue wave trains generation at a specific frequency range. However, this rogue wave trains generation is maintained when the quintic nonlinearity comes into play for negative index regime and amplified for absorption regime at a specific frequency range. It clearly appears that rogue wave behavior strongly depends on the frequency and the regime considered. Furthermore, the stability conditions of the electromagnetic wave have also been discussed at frequency ranges considered for both negative index and absorption regimes.

  10. Observation of the shock wave propagation induced by a high-power laser irradiation into an epoxy material

    International Nuclear Information System (INIS)

    Ecault, Romain; Boustie, Michel; Touchard, Fabienne; Berthe, Laurent; Lescoute, Emilien; Sollier, Arnaud; Mercier, Patrick; Benier, Jacky

    2013-01-01

    The propagation of laser-induced shock waves in a transparent epoxy sample is investigated by optical shadowgraphy. The shock waves are generated by a focused laser (3 ns pulse duration—1.2 to 3.4 TW cm −2 ) producing pressure from 44 to 98.9 GPa. It is observed that the shock wave and the release wave created by the shock reverberation at the rear face are both followed by a dark zone in the pictures. This corresponds to the creation of a tensile zone resulting from the crossing on the loading axis of the release waves coming from the edge of the impact area (2D effects). After the laser shock experiment, the residual stresses in the targets are identified and quantified through a photoelasticimetry analysis of the recovered samples. This work results in a new set of original data which can be directly used to validate numerical models implemented to reproduce the behaviour of epoxy under extreme strain rate loading. The residual stresses observed prove that the high-pressure shocks can modify the pure epoxy properties, which could have an influence on the use made of these materials. (paper)

  11. Kayser-Fleischer Rings

    Science.gov (United States)

    ... Support Contacts Lab Tracker/Copper Calculator Stories Programs & Research ... About Everything you need to know about Wilson Disease Kayser-Fleischer Rings Definition Kayser-Fleischer Ring: Clinical sign. Brownish-yellow ring visible around the corneo- ...

  12. Femtoslicing in Storage Rings

    CERN Document Server

    Khan, Shaukat

    2005-01-01

    The generation of ultrashort synchrotron radiation pulses by laser-induced energy modulation of electrons and their subsequent transverse displacement, now dubbed "femtoslicing," was demonstrated at the Advanced Light Source in Berkeley. More recently, a femtoslicing user facility was commissioned at the BESSY storage ring in Berlin, and another project is in progress at the Swiss Light Source. The paper reviews the principle of femtoslicing, its merits and shortcomings, as well as the variations of its technical implementation. Various diagnostics techniques to detect successful laser-electron interaction are discussed and experimental results are presented.

  13. Tachycardia-Induced J-Wave Changes in Patients With and Without Idiopathic Ventricular Fibrillation.

    Science.gov (United States)

    Aizawa, Yoshiyasu; Takatsuki, Seiji; Nishiyama, Takahiko; Kimura, Takehiro; Kohsaka, Shun; Kaneko, Yoshiaki; Inden, Yasuya; Takahashi, Naohiko; Nagase, Satoshi; Aizawa, Yoshifusa; Fukuda, Keichi

    2017-07-01

    To know the underlying mechanisms of J waves, the response to atrial pacing was studied in patients with idiopathic ventricular fibrillation (IVF) and patients with non-IVF. In 8 patients with IVF, the J-wave amplitude was measured before, during, and after atrial pacing. All patients had episodes of ventricular fibrillation without structural heart disease. The responses of J waves were compared with those of the 17 non-IVF control subjects who revealed J waves but no history of cardiac arrest and underwent electrophysiological study. The IVF patients were younger than the non-IVF patients (28±10 versus 52±14 years, respectively; P =0.002) and had larger J waves with more extensive distribution. J waves decreased from 0.35±0.26 to 0.22±0.23 mV ( P =0.025) when the RR intervals were shortened from 782±88 to 573±162 ms ( P =0.001). A decrease (≥0.05 mV) in the J-wave amplitude was observed in 6 of the 8 patients. In addition, 1 patient showed a distinct reduction of J waves in the unipolar epicardial leads. In contrast, J waves were augmented in the 17 non-IVF subjects from 0.27±0.09 to 0.38±0.10 mV ( P J waves to rapid pacing suggest different mechanisms: early repolarization in IVF patients and conduction delay in non-IVF patients. The response to atrial pacing was different between the IVF and non-IVF patients, which suggests the presence of different mechanisms for the genesis of J waves. © 2017 American Heart Association, Inc.

  14. Does the sun ring

    International Nuclear Information System (INIS)

    Isaak, G.R.

    1978-01-01

    The work of various groups, which have been investigating the possibility of measuring the periodicities of solar oscillations in an attempt to test theoretical models of the sun, is reported. In particular the observation of small velocity oscillations of the surface layers of the sun that permits the measurement of the sound waves (or phonons) in the solar atmosphere, is discussed. Oscillations with periods of 2.65 h, 58 and 40 min and amplitudes of 2.7, 0.8 and 0.7 ms -1 respectively are reported. Support for a periodicity at about 2.65 h from a number of other groups using other measuring techniques are considered. It is felt that the most probable interpretation of the observed solar oscillations is that the sun is a resonator which is ringing. (UK)

  15. ASSOCIATIVE RINGS SOLVED AS LIE RINGS

    Directory of Open Access Journals (Sweden)

    M. B. Smirnov

    2011-01-01

    Full Text Available The paper has proved that an associative ring which is solvable of a n- class as a Lie ring has a nilpotent ideal of the nilpotent class not more than 3×10n–2  and a corresponding quotient ring satisfies an identity [[x1, x2, [x3, x4

  16. Differentiating chondroitin sulfate glycosaminoglycans using collision-induced dissociation; uronic acid cross-ring diagnostic fragments in a single stage of tandem mass spectrometry.

    Science.gov (United States)

    Kailemia, Muchena J; Patel, Anish B; Johnson, Dane T; Li, Lingyun; Linhardt, Robert J; Amster, I Jonathan

    2015-01-01

    The stereochemistry of the hexuronic acid residues of the structure of glycosaminoglycans (GAGs) is a key feature that affects their interactions with proteins and other biological functions. Electron based tandem mass spectrometry methods, in particular electron detachment dissociation (EDD), have been able to distinguish glucuronic acid (GlcA) from iduronic acid (IdoA) residues in some heparan sulfate tetrasaccharides by producing epimer-specific fragments. Similarly, the relative abundance of glycosidic fragment ions produced by collision-induced dissociation (CID) or EDD has been shown to correlate with the type of hexuronic acid present in chondroitin sulfate GAGs. The present work examines the effect of charge state and degree of sodium cationization on the CID fragmentation products that can be used to distinguish GlcA and IdoA containing chondroitin sulfate A and dermatan sulfate chains. The cross-ring fragments (2,4)A(n) and (0,2)X(n) formed within the hexuronic acid residues are highly preferential for chains containing GlcA, distinguishing it from IdoA. The diagnostic capability of the fragments requires the selection of a molecular ion and fragment ions with specific ionization characteristics, namely charge state and number of ionizable protons. The ions with the appropriate characteristics display diagnostic properties for all the chondroitin sulfate and dermatan sulfate chains (degree of polymerization of 4-10) studied.

  17. On the signatures of flare-induced global waves in the Sun: GOLF and VIRGO observations

    Science.gov (United States)

    Kumar, Brajesh; Mathur, Savita; García, Rafael A.; Jiménez, Antonio

    2017-11-01

    Recently, several efforts have been made to identify the seismic signatures of flares and magnetic activity in the Sun and Sun-like stars. In this work, we have analysed the disc-integrated velocity and intensity observations of the Sun obtained from the Global Oscillations at Low Frequencies (GOLF) and Variability of solar IRradiance and Gravity Oscillations/Sun photometers (VIRGO/SPM) instruments, respectively, on board the Solar and Heliospheric Observatory space mission covering several successive flare events, for the period from 2011 February 11 to 2011 February 17, of which 2011 February 11 remained a relatively quiet day and served as a `null test' for the investigation. Application of the spectral analysis to these disc-integrated Sun-as-a-star velocity and intensity signals indicates that there is enhanced power of the global modes of oscillations in the Sun during the flares, as compared to the quiet day. The GOLF instrument obtains velocity observations using the Na I D lines which are formed in the upper solar photosphere, while the intensity data used in our analysis are obtained by VIRGO/SPM instrument at 862 nm, which is formed within the solar photosphere. Despite the fact that the two instruments sample different layers of the solar atmosphere using two different parameters (velocity versus intensity), we have found that both these observations show the signatures of flare-induced global waves in the Sun. These results could suffice in identifying the asteroseismic signatures of stellar flares and magnetic activity in the Sun-like stars.

  18. Experimental study of the Richtmyer-Meshkov instability induced by a Mach 3 shock wave

    International Nuclear Information System (INIS)

    BP Puranik; JG Oakley; MH Anderson; R Bonaazza

    2003-01-01

    OAK-B135 An experimental investigation of a shock-induced interfacial instability (Richtmyer-Meshkov instability) is undertaken in an effort to study temporal evolution of interfacial perturbations in the late stages of development. The experiments are performed in a vertical shock tube with a square cross-section. A membraneless interface is prepared by retracting a sinusoidally shaped metal plate initially separating carbon dioxide from air, with both gases initially at atmospheric pressure. With carbon dioxide above the plate, the Rayleigh-Taylor instability commences as the plate is retracted and the amplitude of the initial sinusoidal perturbation imposed on the interface begins to grow. The interface is accelerated by a strong shock wave (M=3.08) while its shape is still sinusoidal and before the Kelvin-Helmhotz instability distorts it into the well known mushroom-like structures; its initial amplitude to wavelength ratio is large enough that the interface evolution enters its nonlinear stage very shortly after shock acceleration. The pre-shock evolution of the interface due to the Rayleigh-Taylor instability and the post-shock evolution of the interface due to the Richtmyer-Meshkov instability are visualized using planar Mie scattering. The pre-shock evolution of the interface is carried out in an independent set of experiments. The initial conditions for the Richtmyer-Meshkov experiment are determined from the pre-shock Rayleigh-Taylor growth. One image of the post-shock interface is obtained per experiment and image sequences, showing the post-shock evolution of the interface, are constructed from several experiments. The growth rate of the perturbation amplitude is measured and compared with two recent analytical models of the Richtmyer-Meshkov instability

  19. χ(2) Induced Non-Reciprocal Loss and/or Phase Shift for Unidirectional Operation of Ring Lasers

    DEFF Research Database (Denmark)

    Tidemand-Lichtenberg, Peter; Cheng, Haynes Pak Hay; Pedersen, Christian

    2010-01-01

    Numerical modelling and experimental validation of sum-frequency mixing enforcing stable unidirectional operation of a diode pumped solid-state 1342 nm ring laser with improved stability toward feedback.......Numerical modelling and experimental validation of sum-frequency mixing enforcing stable unidirectional operation of a diode pumped solid-state 1342 nm ring laser with improved stability toward feedback....

  20. 22 July 2009 total solar eclipse induced gravity waves in ionosphere as inferred from GPS observations over EIA

    Science.gov (United States)

    Kumar, K. Vijay; Maurya, Ajeet K.; Kumar, Sanjay; Singh, Rajesh

    2016-11-01

    In the present contribution we investigate the variation in the Global Positioning System (GPS) derived ionospheric Total Electron Content (TEC) over Equatorial Ionization Anomaly (EIA) region on the rare occasional astronomical phenomenon of total solar eclipse of 22 July 2009. The aim is to study and identify the wave like structure enumerated due to solar eclipse induced gravity waves in the F-region ionosphere altitude. The work is aimed to understand features of horizontal and vertical variation of atmospheric gravity waves (AGWs) properties over the Equatorial Ionization Anomaly (EIA) region in Indian low latitude region. The ionospheric observations is from the site of Allahabad (lat 25.4° N; lon. 81.9° E; dip 38.6° N) located at the fringe of eclipse totality path. The estimated vertical electron density profile from FORMOSAT-3/COSMIC GPS-RO satellite, considering all the satellite line of sight around the time of eclipse totality shows maximum depletion of 43%. The fast fourier transform and wavelet transform of GPS DTEC data from Allahabad station (Allahabad: lat 25.4 N; lon. 81.9 E) shows the presence of periodic waves of ∼20 to 45 min and ∼70 to 90 min period at F-region altitude. The shorter period correspond to the sunrise time morning terminator and longer period can be associated with solar eclipse generated AGWs. The most important result obtained is that our results along with previous result for wave like signatures in D-region ionosphere from Allahabad station show that AGWs generated by sunrise time terminator have similarity in the D and F region of the ionosphere but solar eclipse induced AGWs show higher period in the F-region compared to D-region ionosphere.

  1. Motions and Hull-Induced Bridging-Structure Loads for a Small Waterplane Area, Twin-Hulled, Attack Aircraft Carrier in Waves

    National Research Council Canada - National Science Library

    Jones, Harry D; Gerzina, David M

    1973-01-01

    ... small waterplane area, twin-hulled, attack aircraft carrier in waves. Motions of the model were measured, together with the forces and moments induced by the hulls on the cross structure spanning the two hulls...

  2. Detection of traveling ionospheric disturbances induced by atmospheric gravity waves using the global positioning system

    Science.gov (United States)

    Bassiri, Sassan; Hajj, George A.

    1993-01-01

    Natural and man-made events like earthquakes and nuclear explosions launch atmospheric gravity waves (AGW) into the atmosphere. Since the particle density decreases exponentially with height, the gravity waves increase exponentially in amplitude as they propagate toward the upper atmosphere and ionosphere. As atmospheric gravity waves approach the ionospheric heights, the neutral particles carried by gravity waves collide with electrons and ions, setting these particles in motion. This motion of charged particles manifests itself by wave-like fluctuations and disturbances that are known as traveling ionospheric disturbances (TID). The perturbation in the total electron content due to TID's is derived analytically from first principles. Using the tilted dipole magnetic field approximation and a Chapman layer distribution for the electron density, the variations of the total electron content versus the line-of-sight direction are numerically analyzed. The temporal variation associated with the total electron content measurements due to AGW's can be used as a means of detecting characteristics of the gravity waves. As an example, detection of tsunami generated earthquakes from their associated atmospheric gravity waves using the Global Positioning System is simulated.

  3. Scenarios for the nonlinear evolution of alpha particle induced Alfven wave instability

    International Nuclear Information System (INIS)

    Berk, H.L.; Breizman, B.N.; Ye, Huanchun.

    1992-03-01

    Various nonlinear scenarios are given for the evolution of energetic particles that are slowing down in a background plasma and simultaneously causing instability of the background plasma waves. If the background damping is sufficiently weak, a steady-state wave is established as described by Berk and Breizman. For larger background damping rate pulsations develop. Saturation occurs when the wave amplitude rises to where the wave trapping frequency equals the growth rate. The wave then damps due to the small background dissipation present and a relatively long quiet interval exists between bursts while the free energy of the distribution is refilled by classical transport. In this scenario the anomalous energy loss of energetic particles due to diffusion is small compared to the classical collisional energy exchange with the background plasma. However, if at the trapping frequency, the wave amplitude is large enough to cause orbit stochasticity, a phase space ''explosion'' occurs where the wave amplitudes rise to higher levels which leads to rapid loss of energetic particles

  4. Mechanical Characterization of Nanoporous Thin Films by Nanoindentation and Laser-induced Surface Acoustic Waves

    Science.gov (United States)

    Chow, Gabriel

    Thin films represent a critical sector of modern engineering that strives to produce functional coatings at the smallest possible length scales. They appear most commonly in semiconductors where they form the foundation of all electronic circuits, but exist in many other areas to provide mechanical, electrical, chemical, and optical properties. The mechanical characterization of thin films has been a continued challenge due foremost to the length scales involved. However, emerging thin films focusing on materials with significant porosity, complex morphologies, and nanostructured surfaces produce additional difficulties towards mechanical analysis. Nanoindentation has been the dominant thin film mechanical characterization technique for the last decade because of the quick results, wide range of sample applicability, and ease of sample preparation. However, the traditional nanoindentation technique encounters difficulties for thin porous films. For such materials, alternative means of analysis are desirable and the lesser known laser-induced surface acoustic wave technique (LiSAW) shows great potential in this area. This dissertation focuses on studying thin, porous, and nanostructured films by nanoindentation and LiSAW techniques in an effort to directly correlate the two methodologies and to test the limits and applicabilities of each technique on challenging media. The LiSAW technique is particularly useful for thin porous films because unlike indentation, the substrate is properly accounted for in the wave motion analysis and no plastic deformation is necessary. Additionally, the use of lasers for surface acoustic wave generation and detection allows the technique to be fully non-contact. This is desirable in the measurement of thin, delicate, and porous films where physical sample probing may not be feasible. The LiSAW technique is also valuable in overcoming nanoscale roughness, particularly for films that cannot be mechanically polished, since typical SAW

  5. Invasion-wave-induced first-order phase transition in systems of active particles.

    Science.gov (United States)

    Ihle, Thomas

    2013-10-01

    An instability near the transition to collective motion of self-propelled particles is studied numerically by Enskog-like kinetic theory. While hydrodynamics breaks down, the kinetic approach leads to steep solitonlike waves. These supersonic waves show hysteresis and lead to an abrupt jump of the global order parameter if the noise level is changed. Thus they provide a mean-field mechanism to change the second-order character of the phase transition to first order. The shape of the wave is shown to follow a scaling law and to quantitatively agree with agent-based simulations.

  6. Primordial gravitational waves induced by magnetic fields in an ekpyrotic scenario

    Directory of Open Access Journals (Sweden)

    Asuka Ito

    2017-08-01

    Full Text Available Both inflationary and ekpyrotic scenarios can account for the origin of the large scale structure of the universe. It is often said that detecting primordial gravitational waves is the key to distinguish both scenarios. We show that this is not true if the gauge kinetic function is present in the ekpyrotic scenario. In fact, primordial gravitational waves sourced by the gauge field can be produced in an ekpyrotic universe. We also study scalar fluctuations sourced by the gauge field and show that it is negligible compared to primordial gravitational waves. This comes from the fact that the fast roll condition holds in ekpyrotic models.

  7. Higher-order geodesic deviation for charged particles and resonance induced by gravitational waves

    Science.gov (United States)

    Heydari-Fard, M.; Hasani, S. N.

    We generalize the higher-order geodesic deviation for the structure-less test particles to the higher-order geodesic deviation equations of the charged particles [R. Kerner, J. W. van Holten and R. Colistete Jr., Class. Quantum Grav. 18 (2001) 4725]. By solving these equations for charged particles moving in a constant magnetic field in the spacetime of a gravitational wave, we show for both cases when the gravitational wave is parallel and perpendicular to the constant magnetic field, a magnetic resonance appears at wg = Ω. This feature might be useful to detect the gravitational wave with high frequencies.

  8. The use of laser-induced shock wave plasma spectroscopy (LISPS) for examining physical characteristics of pharmaceutical products

    Energy Technology Data Exchange (ETDEWEB)

    Abdulmadjid, Syahrun Nur, E-mail: syahrun-madjid@yahoo.com; Lahna, Kurnia, E-mail: kurnialahna@gmail.com [Department of Physics, Faculty of Mathematics and Natural Sciences, Syiah Kuala University, Darussalam, Banda Aceh 23111, Aceh (Indonesia); Desiyana, Lydia Septa, E-mail: lydia-septa@yahoo.com [Department of Pharmacy, Faculty of Mathematics and Natural Sciences, Syiah Kuala University, Darussalam, Banda Aceh 23111, Aceh (Indonesia)

    2016-03-11

    An experimental study has been performed to examine the physical characteristics of pharmaceutical products, such as tablet, by employing an emission plasma induced by Nd-YAG laser at a low pressure of Helium gas. The hardness of tablet is one of the parameters that examined during the production process for standard quality of pharmaceutical products. In the Laser-Induced Shock Wave Plasma Spectroscopy (LISPS), the shock wave has a significant role in inducing atomic excitation. It was known that, the speed of the shock wavefront depends on the hardness of the sample, and it correlates with the ionization rate of the ablated atoms. The hardness of the tablet is examined using the intensity ratio between the ion of Mg (II) 275.2 nm and the neutral of Mg (I) 285.2 nm emission lines detected from the laser-induced plasma. It was observed that the ratio changes with respect to the change in the tablet hardness, namely the ratio is higher for the hard tablet. Besides the ratio measurements, we also measured the depth profile of a tablet by focusing 60 shots of irradiation of laser light at a fixed position on the surface of the tablet. It was found that the depth profile varies differently with the hardness of the tablet. These experiment results show that the technique of LISPS can be applied to examine the quality of pharmaceutical products.

  9. The use of laser-induced shock wave plasma spectroscopy (LISPS) for examining physical characteristics of pharmaceutical products

    International Nuclear Information System (INIS)

    Abdulmadjid, Syahrun Nur; Lahna, Kurnia; Desiyana, Lydia Septa

    2016-01-01

    An experimental study has been performed to examine the physical characteristics of pharmaceutical products, such as tablet, by employing an emission plasma induced by Nd-YAG laser at a low pressure of Helium gas. The hardness of tablet is one of the parameters that examined during the production process for standard quality of pharmaceutical products. In the Laser-Induced Shock Wave Plasma Spectroscopy (LISPS), the shock wave has a significant role in inducing atomic excitation. It was known that, the speed of the shock wavefront depends on the hardness of the sample, and it correlates with the ionization rate of the ablated atoms. The hardness of the tablet is examined using the intensity ratio between the ion of Mg (II) 275.2 nm and the neutral of Mg (I) 285.2 nm emission lines detected from the laser-induced plasma. It was observed that the ratio changes with respect to the change in the tablet hardness, namely the ratio is higher for the hard tablet. Besides the ratio measurements, we also measured the depth profile of a tablet by focusing 60 shots of irradiation of laser light at a fixed position on the surface of the tablet. It was found that the depth profile varies differently with the hardness of the tablet. These experiment results show that the technique of LISPS can be applied to examine the quality of pharmaceutical products.

  10. Combining historical eyewitness accounts on tsunami-induced waves and numerical simulations for getting insights in uncertainty of source parameters

    Science.gov (United States)

    Rohmer, Jeremy; Rousseau, Marie; Lemoine, Anne; Pedreros, Rodrigo; Lambert, Jerome; benki, Aalae

    2017-04-01

    Recent tsunami events including the 2004 Indian Ocean tsunami and the 2011 Tohoku tsunami have caused many casualties and damages to structures. Advances in numerical simulation of tsunami-induced wave processes have tremendously improved forecast, hazard and risk assessment and design of early warning for tsunamis. Among the major challenges, several studies have underlined uncertainties in earthquake slip distributions and rupture processes as major contributor on tsunami wave height and inundation extent. Constraining these uncertainties can be performed by taking advantage of observations either on tsunami waves (using network of water level gauge) or on inundation characteristics (using field evidence and eyewitness accounts). Despite these successful applications, combining tsunami observations and simulations still faces several limitations when the problem is addressed for past tsunamis events like 1755 Lisbon. 1) While recent inversion studies can benefit from current modern networks (e.g., tide gauges, sea bottom pressure gauges, GPS-mounted buoys), the number of tide gauges can be very scarce and testimonies on tsunami observations can be limited, incomplete and imprecise for past tsunamis events. These observations often restrict to eyewitness accounts on wave heights (e.g., maximum reached wave height at the coast) instead of the full observed waveforms; 2) Tsunami phenomena involve a large span of spatial scales (from ocean basin scales to local coastal wave interactions), which can make the modelling very demanding: the computation time cost of tsunami simulation can be very prohibitive; often reaching several hours. This often limits the number of allowable long-running simulations for performing the inversion, especially when the problem is addressed from a Bayesian inference perspective. The objective of the present study is to overcome both afore-described difficulties in the view to combine historical observations on past tsunami-induced waves

  11. Ring-shaped functions and Wigner 6j-symbols

    International Nuclear Information System (INIS)

    Mardoyan, L.G.; Erevanskij Gosudarstvennyj Univ., Erevan

    2006-01-01

    The explicit expression for the ring-shaped matrix connecting the ring-shaped functions relating to different values of the axial parameter is obtained. The connection of this matrix with Wigner 6j-symbols is found out. The motion of quantum particle in the ring-shaped model with the zero priming potential is investigated. The bases of this model, which are factored in spherical cylindrical coordinates, are obtained. The formula generalizing the Rayleigh expansion of a plane wave with respect to spherical waves in the ring-shaped model is deduced [ru

  12. Laser Induced Shock Waves and Vaporization in Biological System and Material Science

    National Research Council Canada - National Science Library

    Gerstman, Bernard S

    2008-01-01

    .... We have developed a computational model that allows the calculation of damage resulting from a laser pulse of any duration or energy due to temperature rise, explosive bubble formation, and shock wave production...

  13. Stirling engine piston ring

    Science.gov (United States)

    Howarth, Roy B.

    1983-01-01

    A piston ring design for a Stirling engine wherein the contact pressure between the piston and the cylinder is maintained at a uniform level, independent of engine conditions through a balancing of the pressure exerted upon the ring's surface and thereby allowing the contact pressure on the ring to be predetermined through the use of a preloaded expander ring.

  14. 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.

  15. Wave-induced mixing and transport of buoyant particles: application to the Statfjord A oil spill

    Directory of Open Access Journals (Sweden)

    M. Drivdal

    2014-12-01

    Full Text Available This study focuses on how wave–current and wave–turbulence interactions modify the transport of buoyant particles in the ocean. Here the particles can represent oil droplets, plastic particles, or plankton such as fish eggs and larvae. Using the General Ocean Turbulence Model (GOTM, modified to take surface wave effects into account, we investigate how the increased mixing by wave breaking and Stokes shear production, as well as the stronger veering by the Coriolis–Stokes force, affects the drift of the particles. The energy and momentum fluxes, as well as the Stokes drift, depend on the directional wave spectrum obtained from a wave model. As a first test, the depth and velocity scales from the model are compared with analytical solutions based on a constant eddy viscosity (i.e., classical Ekman theory. Secondly, the model is applied to a case in which we investigate the oil drift after an oil spill off the west coast of Norway in 2007. During this accident the average net drift of oil was observed to be both slower and more deflected away from the wind direction than predicted by oil-drift models. In this case, using wind and wave forcing from the ERA Interim archive it is shown that the wave effects are important for the resultant drift and have the potential to improve drift forecasting.

  16. On the possibility of wave-induced chaos in a sheared, stably stratified fluid layer

    Directory of Open Access Journals (Sweden)

    W. B. Zimmermann

    1994-01-01

    Full Text Available Shear flow in a stable stratification provides a waveguide for internal gravity waves. In the inviscid approximation, internal gravity waves are known to be unstable below a threshold in Richardson number. However, in a viscous fluid, at low enough Reynolds number, this threshold recedes to Ri = 0. Nevertheless, even the slightest viscosity strongly damps internal gravity waves when the Richardson number is small (shear forces dominate buoyant forces. In this paper we address the dynamics that approximately govern wave propagation when the Richardson number is small and the fluid is viscous. When Ri ξ = λ1A + λ2Aξξ + λ3Aξξξ + λ4AAξ + b(ξ where ξ is the coordinate of the rest frame of the passing temperature wave whose horizontal profile is b(ξ. The parameters λi are constants that depend on the Reynolds number. The above dynamical system is know to have limit cycle and chaotic attrators when forcing is sinusoidal and wave attenuation negligible.

  17. Synthesis of Methylenebicyclo[3.2.1]octanol by a Sm(II)-Induced 1,2-Rearrangement Reaction with Ring Expansion of Methylenebicyclo[4.2.0]octanone.

    Science.gov (United States)

    Takatori, Kazuhiko; Ota, Shoya; Tendo, Kenta; Matsunaga, Kazuma; Nagasawa, Kokoro; Watanabe, Shinya; Kishida, Atsushi; Kogen, Hiroshi; Nagaoka, Hiroto

    2017-07-21

    Direct conversion of methylenebicyclo[4.2.0]octanone to methylenebicyclo[3.2.1]octanol by a Sm(II)-induced 1,2-rearrangement with ring expansion of the methylenecyclobutane is described. Three conditions were optimized to allow the adaptation of this approach to various substrates. A rearrangement mechanism is proposed involving the generation of a ketyl radical and cyclopentanation by ketyl-olefin cyclization, followed by radical fragmentation and subsequent protonation.

  18. Alternative loop rings

    CERN Document Server

    Goodaire, EG; Polcino Milies, C

    1996-01-01

    For the past ten years, alternative loop rings have intrigued mathematicians from a wide cross-section of modern algebra. As a consequence, the theory of alternative loop rings has grown tremendously. One of the main developments is the complete characterization of loops which have an alternative but not associative, loop ring. Furthermore, there is a very close relationship between the algebraic structures of loop rings and of group rings over 2-groups. Another major topic of research is the study of the unit loop of the integral loop ring. Here the interaction between loop rings and group ri

  19. Pure phase decoherence in a ring geometry

    International Nuclear Information System (INIS)

    Zhu, Z.; Aharony, A.; Entin-Wohlman, O.; Stamp, P. C. E.

    2010-01-01

    We study the dynamics of pure phase decoherence for a particle hopping around an N-site ring, coupled both to a spin bath and to an Aharonov-Bohm flux which threads the ring. Analytic results are found for the dynamics of the influence functional and of the reduced density matrix of the particle, both for initial single wave-packet states, and for states split initially into two separate wave packets moving at different velocities. We also give results for the dynamics of the current as a function of time.

  20. Shock wave induced martensitic transformations and morphology changes in Fe-Pd ferromagnetic shape memory alloy thin films

    International Nuclear Information System (INIS)

    Bischoff, A. J.; Arabi-Hashemi, A.; Ehrhardt, M.; Lorenz, P.; Zimmer, K.; Mayr, S. G.

    2016-01-01

    Combining experimental methods and classical molecular dynamics (MD) computer simulations, we explore the martensitic transformation in Fe_7_0Pd_3_0 ferromagnetic shape memory alloy thin films induced by laser shock peening. X-ray diffraction and scanning electron microscope measurements at shock wave pressures of up to 2.5 GPa reveal formation of martensitic variants with preferred orientation of the shorter c-axis of the tetragonal unit cell perpendicular to the surface plane. Moreover, consequential merging of growth islands on the film surface is observed. MD simulations unveil the underlying physics that are characterized by an austenite-martensite transformation with a preferential alignment of the c-axis along the propagation direction of the shock wave, resulting in flattening and in-plane expansion of surface features.

  1. Research on Formation Mechanism of Dynamic Response and Residual Stress of Sheet Metal Induced by Laser Shock Wave

    Science.gov (United States)

    Feng, Aixin; Cao, Yupeng; Wang, Heng; Zhang, Zhengang

    2018-01-01

    In order to reveal the quantitative control of the residual stress on the surface of metal materials, the relevant theoretical and experimental studies were carried out to investigate the dynamic response of metal thin plates and the formation mechanism of residual stress induced by laser shock wave. In this paper, the latest research trends on the surface residual stress of laser shock processing technology were elaborated. The main progress of laser shock wave propagation mechanism and dynamic response, laser shock, and surface residual stress were discussed. It is pointed out that the multi-scale characterization of laser and material, surface residual stress and microstructure change is a new hotspot in laser shock strengthening technology.

  2. Suppression of inducer stall based on inlet recirculation in a centrifugal impeller. 1st Report. Improvement in stall limit by ring groove arrangement; Enshin haneguruma iriguchi junkanryu ni yoru inducer shissoku no yokusei. 1. kanjoko ni yoru shissoku genkai no kaizen

    Energy Technology Data Exchange (ETDEWEB)

    Ueki, H.; Ishida, M.; Sakaguchi, D.; Sun, Z. [Nagasaki University, Nagasaki (Japan). Faculty of Engineering

    2000-07-25

    A ring groove arrangement is proposed to suppress unstable flow or surge in a centrifugal blower. The ring groove arrangement connects the upstream position of impeller inlet and the inducer throat tip through a bypass. The recirculation flow 'vas formed by the pressure difference between the two positions, and the recirculation flow rate was changed by increasing the ring groove widths. The inlet recirculation results in a decrease in the flow rate of unstable flow inception, and an up to 800 improvement in stall limit was obtained by the ring groove arrangement at a small expense of the delivery pressure drop. The improvement of stall limit in the present experiment seems to be mainly due to decrease in flow incidence based on the inlet recirculation flow. Tre flow incidence decreases more as the recirculation flow rate increases, thus resulting in a larger improvement in stall limit. (author)

  3. Calcium waves.

    Science.gov (United States)

    Jaffe, Lionel F

    2008-04-12

    Waves through living systems are best characterized by their speeds at 20 degrees C. These speeds vary from those of calcium action potentials to those of ultraslow ones which move at 1-10 and/or 10-20 nm s(-1). All such waves are known or inferred to be calcium waves. The two classes of calcium waves which include ones with important morphogenetic effects are slow waves that move at 0.2-2 microm s(-1) and ultraslow ones. Both may be propagated by cycles in which the entry of calcium through the plasma membrane induces subsurface contraction. This contraction opens nearby stretch-sensitive calcium channels. Calcium entry through these channels propagates the calcium wave. Many slow waves are seen as waves of indentation. Some are considered to act via cellular peristalsis; for example, those which seem to drive the germ plasm to the vegetal pole of the Xenopus egg. Other good examples of morphogenetic slow waves are ones through fertilizing maize eggs, through developing barnacle eggs and through axolotl embryos during neural induction. Good examples of ultraslow morphogenetic waves are ones during inversion in developing Volvox embryos and across developing Drosophila eye discs. Morphogenetic waves may be best pursued by imaging their calcium with aequorins.

  4. Characterizing wave- and current- induced bottom shear stress: U.S. middle Atlantic continental shelf

    Science.gov (United States)

    Dalyander, P. Soupy; Butman, Bradford; Sherwood, Christopher R.; Signell, Richard P.; Wilkin, John L.

    2013-01-01

    Waves and currents create bottom shear stress, a force at the seabed that influences sediment texture distribution, micro-topography, habitat, and anthropogenic use. This paper presents a methodology for assessing the magnitude, variability, and driving mechanisms of bottom stress and resultant sediment mobility on regional scales using numerical model output. The analysis was applied to the Middle Atlantic Bight (MAB), off the U.S. East Coast, and identified a tidally-dominated shallow region with relatively high stress southeast of Massachusetts over Nantucket Shoals, where sediment mobility thresholds are exceeded over 50% of the time; a coastal band extending offshore to about 30 m water depth dominated by waves, where mobility occurs more than 20% of the time; and a quiescent low stress region southeast of Long Island, approximately coincident with an area of fine-grained sediments called the “Mud Patch”. The regional high in stress and mobility over Nantucket Shoals supports the hypothesis that fine grain sediment winnowed away in this region maintains the Mud Patch to the southwest. The analysis identified waves as the driving mechanism for stress throughout most of the MAB, excluding Nantucket Shoals and sheltered coastal bays where tides dominate; however, the relative dominance of low-frequency events varied regionally, and increased southward toward Cape Hatteras. The correlation between wave stress and local wind stress was lowest in the central MAB, indicating a relatively high contribution of swell to bottom stress in this area, rather than locally generated waves. Accurate prediction of the wave energy spectrum was critical to produce good estimates of bottom shear stress, which was sensitive to energy in the long period waves.

  5. Wave-induced ripple development in mixed clay-sand substrates

    Science.gov (United States)

    Wu, Xuxu; Parsons, Daniel; Baas, Jaco H.; Mouazé, Dominique; McLelland, Stuart; Amoudry, Laurent; Eggenhuisen, Jorris; Cartigny, Matthieu; Ruessink, Gerben

    2016-04-01

    This paper reports on a series of experiments that aim to provide a fuller understanding of ripple development within clay-sand mixture substrates under oscillatory flow conditions. The work was conducted in the Total Environment Simulator at the University of Hull and constituted 6 separate runs, in which 5 runs were conducted under identical sets of regular waves (an additional run was conducted under irregular waves, but is not discussed in present paper). The bed content was systematically varied in its composition ranging from a pure sand bed through to a bed comprising 7.4% clay. A series of state-of-the-art measurements were employed to quantify interactions of near-bed hydrodynamics, sediment transport, and turbulence over rippled beds formed by wave action, during and after, each run. The experimental results demonstrate the significant influence of the amount of cohesive clay materials in the substrate on ripple evolution under waves. Most importantly, addition of clay in the bed dramatically slowed down the rate of ripple development and evolution. The equilibrium time of each run increased exponentially from 30 minutes under the control conditions of a pure sand bed, rising to ~350 minutes for the bed with the highest fraction of clay. The paper discusses the slower ripple growth rates with higher cohesive fractions, via an influence on critical shear, but highlights that the end equilibrium size of ripples is found to be independent of increasing substrate clay fraction. The suspended particles mass (SPM) concentration indicates that clay particles were suspended and winnowed by wave action. Additionally, laser granulometry of the final substrates verified that ripple crests were composed of pure sand layers that were absent at ripple troughs, reflecting a relatively higher winnowing efficiency at wave ripples crest. The winnowing process and its efficiency is inexorably linked to wave ripple development and evolution. The implications of the results

  6. Characterizing Hypervelocity Impact (HVI-Induced Pitting Damage Using Active Guided Ultrasonic Waves: From Linear to Nonlinear

    Directory of Open Access Journals (Sweden)

    Menglong Liu

    2017-05-01

    Full Text Available Hypervelocity impact (HVI, ubiquitous in low Earth orbit with an impacting velocity in excess of 1 km/s, poses an immense threat to the safety of orbiting spacecraft. Upon penetration of the outer shielding layer of a typical two-layer shielding system, the shattered projectile, together with the jetted materials of the outer shielding material, subsequently impinge the inner shielding layer, to which pitting damage is introduced. The pitting damage includes numerous craters and cracks disorderedly scattered over a wide region. Targeting the quantitative evaluation of this sort of damage (multitudinous damage within a singular inspection region, a characterization strategy, associating linear with nonlinear features of guided ultrasonic waves, is developed. Linear-wise, changes in the signal features in the time domain (e.g., time-of-flight and energy dissipation are extracted, for detecting gross damage whose characteristic dimensions are comparable to the wavelength of the probing wave; nonlinear-wise, changes in the signal features in the frequency domain (e.g., second harmonic generation, which are proven to be more sensitive than their linear counterparts to small-scale damage, are explored to characterize HVI-induced pitting damage scattered in the inner layer. A numerical simulation, supplemented with experimental validation, quantitatively reveals the accumulation of nonlinearity of the guided waves when the waves traverse the pitting damage, based on which linear and nonlinear damage indices are proposed. A path-based rapid imaging algorithm, in conjunction with the use of the developed linear and nonlinear indices, is developed, whereby the HVI-induced pitting damage is characterized in images in terms of the probability of occurrence.

  7. A Lagrangian model for laser-induced fluorescence and its application to measurements of plasma ion temperature and electrostatic waves

    Science.gov (United States)

    Chu, F.; Skiff, F.

    2018-01-01

    Extensive information can be obtained on wave-particle interactions and wave fields by a direct measurement of perturbed ion distribution functions using laser-induced fluorescence (LIF). For practical purposes, LIF is frequently performed on metastable states that are produced from neutral gas particles and ions in other electronic states. If the laser intensity is increased to obtain a better LIF signal, then optical pumping can produce systematic effects depending on the collision rates which control metastable population and lifetime. We numerically simulate the ion velocity distribution measurement and wave-detection process using a Lagrangian model for the LIF signal for the case where metastables are produced directly from neutrals. This case requires more strict precautions and is important for discharges with energetic primary electrons and a high density of neutrals. Some of the results also apply to metastables produced from pre-existing ions. The simulations show that optical pumping broadening affects the ion velocity distribution function f0(v) and its first-order perturbation f1(v,t) when the laser intensity is increased above a certain level. The results also suggest that ion temperature measurements are only accurate when the metastable ions can live longer than the ion-ion collision mean free time. For the purposes of wave detection, the wave period has to be significantly shorter than the lifetime of metastable ions for a direct interpretation. It is more generally true that metastable ions may be viewed as test-particles. As long as an appropriate model is available, LIF can be extended to a range of environments.

  8. Electromagnetic Ion Cyclotron Waves in the Helium Branch Induced by Multiple Electromagnetic Ion Cyclotron Triggered Emissions

    Science.gov (United States)

    Shoji, M.; Omura, Y.; Grison, B.; Pickett, J. S.; Dandouras, I. S.; Engebretson, M. J.

    2011-12-01

    Electromagnetic ion cyclotron (EMIC) triggered emissions with rising tones between the H+ and He+ cyclotron frequencies were found in the inner magnetosphere by the recent Cluster observations. Another type of EMIC wave with a constant frequency is occasionally observed below the He+ cyclotron frequency after the multiple EMIC triggered emissions. We performed a self-consistent hybrid simulation with a one-dimensional cylindrical magnetic flux model approximating the dipole magnetic field of the Earth's inner magnetosphere. In the presence of energetic protons with a sufficient density and temperature anisotropy, multiple EMIC triggered emissions are reproduced due to the nonlinear wave growth mechanism of rising-tone chorus emissions, and a constant frequency wave in the He+ EMIC branch is subsequently generated. Through interaction with the multiple EMIC rising-tone emissions, the velocity distribution function of the energetic protons is strongly modified. Because of the pitch angle scattering of the protons, the gradient of the distribution in velocity phase space is enhanced along the diffusion curve of the He+ branch wave, resulting in the linear growth of the EMIC wave in the He+ branch.

  9. Extracting gravitational waves induced by plasma turbulence in the early Universe through an averaging process

    International Nuclear Information System (INIS)

    Garrison, David; Ramirez, Christopher

    2017-01-01

    This work is a follow-up to the paper, ‘Numerical relativity as a tool for studying the early Universe’. In this article, we determine if cosmological gravitational waves can be accurately extracted from a dynamical spacetime using an averaging process as opposed to conventional methods of gravitational wave extraction using a complex Weyl scalar. We calculate the normalized energy density, strain and degree of polarization of gravitational waves produced by a simulated turbulent plasma similar to what was believed to have existed shortly after the electroweak scale. This calculation is completed using two numerical codes, one which utilizes full general relativity calculations based on modified BSSN equations while the other utilizes a linearized approximation of general relativity. Our results show that the spectrum of gravitational waves calculated from the nonlinear code using an averaging process is nearly indistinguishable from those calculated from the linear code. This result validates the use of the averaging process for gravitational wave extraction of cosmological systems. (paper)

  10. Seismic interferometry of railroad induced ground motions: body and surface wave imaging

    Science.gov (United States)

    Quiros, Diego A.; Brown, Larry D.; Kim, Doyeon

    2016-04-01

    Seismic interferometry applied to 120 hr of railroad traffic recorded by an array of vertical component seismographs along a railway within the Rio Grande rift has recovered surface and body waves characteristic of the geology beneath the railway. Linear and hyperbolic arrivals are retrieved that agree with surface (Rayleigh), direct and reflected P waves observed by nearby conventional seismic surveys. Train-generated Rayleigh waves span a range of frequencies significantly higher than those recovered from typical ambient noise interferometry studies. Direct P-wave arrivals have apparent velocities appropriate for the shallow geology of the survey area. Significant reflected P-wave energy is also present at relatively large offsets. A common midpoint stack produces a reflection image consistent with nearby conventional reflection data. We suggest that for sources at the free surface (e.g. trains) increasing the aperture of the array to record wide angle reflections, in addition to longer recording intervals, might allow the recovery of deeper geological structure from railroad traffic. Frequency-wavenumber analyses of these recordings indicate that the train source is symmetrical (i.e. approaching and receding) and that deeper refracted energy is present although not evident in the time-offset domain. These results confirm that train-generated vibrations represent a practical source of high-resolution subsurface information, with particular relevance to geotechnical and environmental applications.

  11. Nanoscale charcoal powder induced saturable absorption and mode-locking of a low-gain erbium-doped fiber-ring laser

    International Nuclear Information System (INIS)

    Lin, Yung-Hsiang; Chi, Yu-Chieh; Lin, Gong-Ru

    2013-01-01

    Triturated charcoal nano-powder directly brushed on a fiber connector end-face is used for the first time as a fast saturable absorber for a passively mode-locked erbium-doped fiber-ring laser (EDFL). These dispersant-free charcoal nano-powders with a small amount of crystalline graphene phase and highly disordered carbon structure exhibit a broadened x-ray diffraction peak and their Raman spectrum shows the existence of a carbon related D-band at 1350 cm −1 and the disappearance of the 2D-band peak at 2700 cm −1 . The charcoal nano-powder exhibits a featureless linear absorbance in the infrared region with its linear transmittance of 0.66 nonlinearly saturated at 0.73 to give a ΔT/T of 10%. Picosecond mode-locking at a transform-limited condition of a low-gain EDFL is obtained by using the charcoal nano-powder. By using a commercial EDFA with a linear gain of only 17 dB at the saturated output power of 17.5 dB m required to initiate the saturable absorption of the charcoal nano-powder, the EDFL provides a pulsewidth narrowing from 3.3 to 1.36 ps associated with its spectral linewidth broadening from 0.8 to 1.83 nm on increasing the feedback ratio from 30 to 90%. This investigation indicates that all the carbon-based materials containing a crystalline graphene phase can be employed to passively mode-lock the EDFL, however, the disordered carbon structure inevitably induces a small modulation depth and a large mode-locking threshold, thus limiting the pulsewidth shortening. Nevertheless, the nanoscale charcoal passively mode-locked EDFL still shows the potential to generate picosecond pulses under a relatively low cavity gain. An appropriate cavity design can be used to compensate this defect-induced pulsewidth limitation and obtain a short pulsewidth. (letter)

  12. SOR-ring failure

    International Nuclear Information System (INIS)

    Kitamura, Hideo

    1981-01-01

    It was in the autumn of 1976 that the SOR-ring (synchrotron radiation storage ring) has commenced the regular operation. Since then, the period when the operation was interrupted due to the failures of SOR-ring itself is in total about 8 weeks. Failures and accidents have occurred most in the vacuum system. Those failure experiences are described on the vacuum, electromagnet, radio-frequency acceleration and beam transport systems with their interrupted periods. The eleven failures in the vacuum system have been reported, such as bellows breakage in a heating-evacuating period, leakage from the bellows of straight-through valves (made in U.S.A. and Japan), and leakage from the joint flange of the vacuum system. The longest interruption was 5 weeks due to the failure of a domestically manufactured straight-through valve. The failures of the electromagnet system involve the breakage in a cooling water system, short circuit of a winding in the Q magnet power transformer, blow of a fuse protecting the deflection magnet power source by the current less than the rating, and others. The failures of the RF acceleration system include the breakage of an output electronic tube the breakage of a cavity ceramic, RF voltage fluctuation due to the contact deterioration at a cavity electrode, and the failure of grid bias power source. It is necessary to select the highly reliable components for the vacuum system because the vacuum system failures require longer time for recovery, and very likely to induce secondary and tertiary failures. (Wakatsuki, Y.)

  13. Spectral features of lightning-induced ion cyclotron waves at low latitudes: DEMETER observations and simulation

    Czech Academy of Sciences Publication Activity Database

    Shklyar, D. R.; Storey, L. R. O.; Chum, Jaroslav; Jiříček, František; Němec, F.; Parrot, M.; Santolík, Ondřej; Titova, E. E.

    2012-01-01

    Roč. 117, A12 (2012), A12206/1-A12206/16 ISSN 0148-0227 R&D Projects: GA ČR GA205/09/1253; GA ČR GAP205/10/2279; GA MŠk ME09107 Grant - others:GA ČR(CZ) GPP209/12/P658 Program:GP Institutional support: RVO:68378289 Keywords : Plasma waves analysis * ion cyclotron waves * satellite observation and numerical simulation * geometrical optics * multi-component measurements * simulation * spectrogram * wave propagation Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.174, year: 2012 http://onlinelibrary.wiley.com/doi/10.1029/2012JA018016/abstract

  14. Piezoelectricity induced defect modes for shear waves in a periodically stratified supperlattice

    Science.gov (United States)

    Piliposyan, Davit

    2018-01-01

    Properties of shear waves in a piezoelectric stratified periodic structure with a defect layer are studied for a superlattice with identical piezoelectric materials in a unit cell. Due to the electro-mechanical coupling in piezoelectric materials the structure exhibits defect modes in the superlattice with full transmission peaks both for full contact and electrically shorted interfaces. The results show an existence of one or two transmission peaks depending on the interfacial conditions. In the long wavelength region where coupling between electro-magnetic and elastic waves creates frequency band gaps the defect layer introduces one or two defect modes transmitting both electro-magnetic and elastic energies. Other parameters affecting the defect modes are the thickness of the defect layer, differences in refractive indexes and the magnitude of the angle of the incident wave. The results of the paper may be useful in the design of narrow band filters or multi-channel piezoelectric filters.

  15. Effects induced by ICRF waves on various confinement schemes in Tore Supra

    International Nuclear Information System (INIS)

    Saoutic, B.

    1995-01-01

    The 1993-94 experimental campaign has seen a significant increase of the application of waves in the ion cyclotron range of frequency on Tore Supra. Ion cyclotron resonant heating has been applied to plasmas with strongly radiating layers, pellet-enhanced performance and lower hybrid enhanced performance. Initial experiments on direct coupling of the fast magnetosonic wave to the electrons have demonstrated coupling up to 5 MW to the plasma and have demonstrated an efficient electron heating in these discharges. A significant bootstrap current fraction is observed. This heating scheme leads to a stationary improvement in energy confinement, with implications for the Rebut-Lallia-Watkins local transport model. Finally, preliminary experiments on antenna phasing have shown clear evidence of fast wave current drive. (author) 25 refs.; 9 figs

  16. Parametrically induced low-frequency waves in weakly inhomogeneous magnetized plasmas

    International Nuclear Information System (INIS)

    Pesic, S.

    1981-01-01

    The linear dispersion relation governing the parametric interaction of a lower hybrid pump wave with a weakly-inhomogeneous current carrying hot plasma confined by a helical magnetic field is derived and solved numerically. The stability boundaries are delineated over a wide range in the k-space. The frequency and growth rate of decay instabilities are calculated for plasma parameters relevant to lower hybrid plasma heating experiments. The parametric excitation of drift waves and ion cyclotron current instabilities is discussed. In the low-density plasma region low minimum thresholds and high growth rates are obtained for the pump decay into ion cyclotron and nonresonant quasimodes. The spatial amplification of hot ion Bernstein waves and nonresonant quasimodes dominate in the plasma core (ω 0 /ωsub(LH) < 2). The presented theoretical results are in qualitative agreement with current LH plasma heating experiments. (author)

  17. An N-body Integrator for Planetary Rings

    Science.gov (United States)

    Hahn, Joseph M.

    2011-04-01

    A planetary ring that is disturbed by a satellite's resonant perturbation can respond in an organized way. When the resonance lies in the ring's interior, the ring responds via an m-armed spiral wave, while a ring whose edge is confined by the resonance exhibits an m-lobed scalloping along the ring-edge. The amplitude of these disturbances are sensitive to ring surface density and viscosity, so modelling these phenomena can provide estimates of the ring's properties. However a brute force attempt to simulate a ring's full azimuthal extent with an N-body code will likely fail because of the large number of particles needed to resolve the ring's behavior. Another impediment is the gravitational stirring that occurs among the simulated particles, which can wash out the ring's organized response. However it is possible to adapt an N-body integrator so that it can simulate a ring's collective response to resonant perturbations. The code developed here uses a few thousand massless particles to trace streamlines within the ring. Particles are close in a radial sense to these streamlines, which allows streamlines to be treated as straight wires of constant linear density. Consequently, gravity due to these streamline is a simple function of the particle's radial distance to all streamlines. And because particles are responding to smooth gravitating streamlines, rather than discrete particles, this method eliminates the stirring that ordinarily occurs in brute force N-body calculations. Note also that ring surface density is now a simple function of streamline separations, so effects due to ring pressure and viscosity are easily accounted for, too. A poster will describe this N-body method in greater detail. Simulations of spiral density waves and scalloped ring-edges are executed in typically ten minutes on a desktop PC, and results for Saturn's A and B rings will be presented at conference time.

  18. Streak-photographic investigation of shock wave emission after laser-induced plasma formation in water

    Science.gov (United States)

    Noack, Joachim; Vogel, Alfred

    1995-05-01

    The shock wave emission after dielectric breakdown in water was investigated to assess potential shock wave effects in plasma mediated tissue ablation and intraocular photodisruption. Of particular interest was the dependence of shock wave pressure as a function of distance from the plasma for different laser pulse energies. We have generated plasmas in water with a Nd:YAG laser system delivering pulses of 6 ns duration. The pulses, with energies between 0.4 and 36 mJ (approximately equals 180 times threshold), were focused into a cuvette containing distilled water. The shock wave was visualized with streak photography combined with a schlieren technique. An important advantage of this technique is that the shock position as a function of time can directly be obtained from a single streak and hence a single event. Other methods (e.g. flash photography or passage time measurements between fixed locations) in contrast rely on reproducible events. Using the shock wave speed obtained from the streak images, shock wave peak pressures were calculated providing detailed information on the propagation of the shock. The shock peak pressure as a function of distance r from the optical axis was found to decrease faster than 1/r2 in regions up to distances of 100-150 micrometers . For larger distances it was found to be roughly proportional to 1/r. The scaling law for maximum shock pressure p, at a given distance was found to be proportional to the square root of the laser pulse energy E for distances of 50-200 micrometers from the optical axis.

  19. A study on early microstructural changes in the rabbit kidney induced by shock waves

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Kyung Soo [Sung Ae Hospital, Seoul (Korea, Republic of); Shim, Hyung Jin; Kim, Kun Sang; Song, In Sup; Lee, Yong Chul; Song, Kei Yong [College of Medicine, Chung Ang University, Seoul (Korea, Republic of)

    1993-07-15

    Many reports have been published on the tissue damage of a shock wave with respect to histopathological changes in light microscopy and various imaging modalities. However, the studies on the electron microscopic findings and cause of renal functional change such as parenchymal obstructive pattern following extracorporeal shock wave lithotripsy (ESWL) have not been elucidated. In order to evaluate the microstructural changes after shock wave exposure, gross, light microscopic and transmission electron microscopic findings were analyzed with rabbit kidneys. Preliminary study (n=2) was performed to determine the dosage intensity of shock waves to inflict damage, using a EDAP LT 01 piezoelectric extracorporeal shock wave lithotriptor. A shock wave of various intensities were given to the left kidneys of 3 different groups of rabbits. Storage of value of 100, 50, 25 at rate of 20/sec under 87% power were given to group I (n=4), group II (n=4), and group III (n=3) respectively. The right kidneys were preserved as the control group. The rabbits were killed 6-12 hour later. In gross, there were a few subcapsular hemorrhage foci and mild congestion of corticomedullary junction without a large hematoma formation. No significant differences were noted between each group. Light microscopic findings were mainly hydropic changes in the proximal convoluted tubules and congestion without significant necrotic changes. The observed pathologic changes in the transmission electron microscopy were vacuolization of cytoplasm with swelling of epithelial cells especially porximal convoluted tubules. There were also tubular obstruction due to swelling and desquamation of epithelial cells into tubular lumen. The structural changes of intracellular organelles were not found at storage values of 25 and 50. But dilatation and structural alterations of endoplasmic reticulums were noted at value of 100 with cell membrane rupture. The findings of this study suggest that tubular obstructions with

  20. Functionalization of embedded thiol-ene waveguides for evanescent wave induced fluorescence detection in a microfluidic device

    DEFF Research Database (Denmark)

    Feidenhans'l, Nikolaj Agentoft; Jensen, Thomas Glasdam; Lafleur, Josiane P.

    2013-01-01

    We demonstrate the use of functional surface groups inherently present on off-stoichiometric thiol−ene polymers, for site-specific immobilization of biomolecules and detection by evanescent wave-induced fluorescence. An optofluidic chip featuring an embedded thiol−ene waveguide was selectively...... functionalized with biotin using photografting. The biotin was used for immobilization of fluorescently labelled streptavidin, and experiments revealed a linear correlation between streptavidin concentration and fluorescent intensity. To further demonstrate the attractiveness of using thiol−ene for optofluidic...

  1. Interaction of the superconducting domains induced by external electric field with electromagnetic waves

    International Nuclear Information System (INIS)

    Shapiro, B.Y.

    1992-01-01

    The behavior of a superconductor in time-independent electric field perpendicular to the surface and in the external electromagnetic wave is theoretically investigated. A new type of the resonance interaction between superconducting domains localized along the magnetic field (if the superconducting phase transition takes place in the external magnetic field perpendicular to the surface) and electromagnetic waves is predicted. The surface impedance of the superconductor with domains is calculated. It is shown that the real part of the impedance has a saturation if the skin length equals the domain size. (orig.)

  2. Self-induced dipole force and filamentation instability of a matter wave

    DEFF Research Database (Denmark)

    Saffman, M.

    1998-01-01

    The interaction of copropagating electromagnetic and matter waves is described with a set of coupled higher-order nonlinear Schrodinger equations. Optical self-focusing modulates an initially planar wave leading to the generation of dipole forces on the atoms. Atomic channeling due to the dipole...... forces leads, in the nonlinear regime, to filamentation of the atomic beam. Instability growth rates are calculated for atomic beams with both low and high phase space densities. In one transverse dimension an exact solution is found that describes a coupled optical and atomic soliton....

  3. Truncation effects in connected arrays: Analytical models to describe the edge-induced wave phenomena

    NARCIS (Netherlands)

    Neto, A.; Cavallo, D.; Gerini, G.

    2011-01-01

    This paper presents a Green's function based procedure to assess edge effects in finite wideband connected arrays. Truncation effects are more severe in broadband arrays, since the inter-element mutual coupling facilitates the propagation of edge-born waves that can become dominant over large

  4. The effect of instanton-induced interaction on P-wave meson spectra ...

    Indian Academy of Sciences (India)

    possible to reproduce the observed spectra as the tensor and spin-orbit terms of. OGEP are attractive, and hence naturally triplet states masses will be lower than the corresponding singlet states. Hence, to reproduce the full P-wave spectra it is essential to include the hyperfine interaction term of III to have a consistent. 76.

  5. Observations of acoustic-wave-induced superluminescence in an argon plasma

    International Nuclear Information System (INIS)

    Aramyan, A.R.

    2003-01-01

    It is shown that in an argon discharge plasma it is possible to obtain overpopulation of certain electronic levels of atomic argon under the influence of acoustic waves. When the specified threshold is exceeded, then a superluminescence (in the form of light flashes) from the overpopulated electronic levels of atomic argon is observed

  6. Plasma waves and electric discharges induced by a beam from a high-latitude satellite

    International Nuclear Information System (INIS)

    Kuns, G.; Koen, G.

    1985-01-01

    Using P78-2 satellite measurements of characteristics of space probe charging in synchronous orbit are carried out. A particle beam generation system including electron and ion guns was part of the satellite equipment. Electric charge analyser placed aboard the satellite in course of electron and ion beam generation recorded plasma waves and electric discharges

  7. Ferroelectricity Induced by Acentric Spin-Density Waves in YMn2O5

    NARCIS (Netherlands)

    Chapon, L.C.; Radaelli, P.G.; Blake, G.R.; Park, S.; Cheong, S.-W.

    2006-01-01

    The commensurate and incommensurate magnetic structures of the magnetoelectric system YMn2O5, as determined from neutron diffraction, were found to be spin-density waves lacking a global center of symmetry. We propose a model, based on a simple magnetoelastic coupling to the lattice, which enables

  8. Continuum contribution to excitonic four-wave mixing due to interaction-induced nonlinearities

    DEFF Research Database (Denmark)

    Birkedal, Dan; Vadim, Lyssenko; Hvam, Jørn Märcher

    1996-01-01

    We present an experimental and theoretical investigation of ultrafast transient four-wave mixing of GaAs/AlxGa1-xAs quantum wells for coherent excitation of exciton and continuum states. The signal appears at the exciton resonance and is shown to consist of two contributions: an intense spectrall...

  9. Effect of molecular weight and density of ambient gas on shock wave in laser-induced surface nanostructuring

    International Nuclear Information System (INIS)

    Guo Liying; Wang Xinwei

    2009-01-01

    This paper presents the results of molecular dynamics studies about the shock wave during laser-induced surface nanostructuring. A quasi-three dimensional model is constructed to study systems consisting of over 2 million atoms. Detailed studies are carried out about the shock wave front and Mach number, evolution of plume and ambient gas interaction zone, and energy exchange between the ambient gas and plume. Under an ambience of lower pressure or lighter molecular mass, the plume affects a larger area while the strength of the shock wave front is weaker. With the same ambient pressure, the ablated material features the same kinetic energy at the late stage regardless of the molecular weight of the ambient gas. The same conclusion holds for the energy increase of the ambient gas as well. When the ambient pressure is reduced, more kinetic energy is carried out by the ablated material while less energy is transferred to the ambient gas. It is observed that heavier ambient gas could bounce back the ablated material to the target surface.

  10. Simulation study and guidelines to generate Laser-induced Surface Acoustic Waves for human skin feature detection

    Science.gov (United States)

    Li, Tingting; Fu, Xing; Chen, Kun; Dorantes-Gonzalez, Dante J.; Li, Yanning; Wu, Sen; Hu, Xiaotang

    2015-12-01

    Despite the seriously increasing number of people contracting skin cancer every year, limited attention has been given to the investigation of human skin tissues. To this regard, Laser-induced Surface Acoustic Wave (LSAW) technology, with its accurate, non-invasive and rapid testing characteristics, has recently shown promising results in biological and biomedical tissues. In order to improve the measurement accuracy and efficiency of detecting important features in highly opaque and soft surfaces such as human skin, this paper identifies the most important parameters of a pulse laser source, as well as provides practical guidelines to recommended proper ranges to generate Surface Acoustic Waves (SAWs) for characterization purposes. Considering that melanoma is a serious type of skin cancer, we conducted a finite element simulation-based research on the generation and propagation of surface waves in human skin containing a melanoma-like feature, determine best pulse laser parameter ranges of variation, simulation mesh size and time step, working bandwidth, and minimal size of detectable melanoma.

  11. Time-resolved X-ray diffraction studies of laser-induced acoustic wave propagation in bilayer metallic thin crystals

    Energy Technology Data Exchange (ETDEWEB)

    Er, Ali Oguz [Department of Physics and Astronomy, Western Kentucky University, Bowling Green, Kentucky 42101 (United States); Tang, Jau, E-mail: jautang@gate.sinica.edu.tw, E-mail: prentzepis@ece.tamu.edu [Research Center for Applied Sciences Academia Sinica, Taipei, Taiwan (China); Chen, Jie [Key Laboratory for Laser Plasmas (Ministry of Education) and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Rentzepis, Peter M., E-mail: jautang@gate.sinica.edu.tw, E-mail: prentzepis@ece.tamu.edu [Department of Electrical and Computer Engineering, Texas A and M University, College Station, Texas 77843 (United States)

    2014-09-07

    Phonon propagation across the interface of a Cu/Ag(111) bilayer and transient lattice disorder, induced by a femtosecond 267 nm pulse, in Ag(111) crystal have been measured by means of time resolved X-ray diffraction. A “blast” force due to thermal stress induced by suddenly heated electrons is formed within two picoseconds after excitation and its “blast wave” propagation through the interface and Ag (111) crystal was monitored by the shift and broadening of the rocking curve, I vs. ω, as a function of time after excitation. Lattice disorder, contraction and expansion as well as thermal strain formation and wave propagation have also been measured. The experimental data and mechanism proposed are supported by theoretical simulations.

  12. Tuning gain and bandwidth of traveling wave tubes using metamaterial beam-wave interaction structures

    International Nuclear Information System (INIS)

    Lipton, Robert; Polizzi, Anthony

    2014-01-01

    We employ metamaterial beam-wave interaction structures for tuning the gain and bandwidth of short traveling wave tubes. The interaction structures are made from metal rings of uniform cross section, which are periodically deployed along the length of the traveling wave tube. The aspect ratio of the ring cross sections is adjusted to control both gain and bandwidth. The frequency of operation is controlled by the filling fraction of the ring cross section with respect to the size of the period cell.

  13. Evaluating temperature changes of brain tissue due to induced heating of cell phone waves

    Directory of Open Access Journals (Sweden)

    Farhad Forouharmajd

    2018-01-01

    Full Text Available Background: Worries have recently been increased in the absorption of radiofrequency waves and their destructing effects on human health by increasing use of cell phones (mobile phones. This study performed to determine the thermal changes due to mobile phone radio frequency waves in gray and white brain tissue. Methods: This study is an empirical study, where the thermal changes of electromagnetic waves resulted from cell phones (900 MHZ, specific absorption rate for head 1.18 w/kg on the 15 brain tissue of a cow were analyzed in a compartment with three different thickness of 2 mm, 12 mm, and 22 mm, for 15 min. The Lutron thermometer (model: MT-917 with 0.01°C precision was used for measuring the tissue temperature. For each thickness was measured three times. Data analysis is done by Lutron and MATLAB software packages. Results: In confronting of the tissue with the cell phone, the temperature was increased by 0.53°C in the 2 mm thickness that is the gray matter of the brain, increased by 0.99°C in the 12 mm thickness, and also increased by 0.92°C in the 22 mm thickness. Brain temperature showed higher rates than the base temperature after 15 min of confrontation with cell phone waves in all the three thicknesses. Conclusions: Cell phone radiated radio frequency waves were effective on increasing brain tissue temperature, and this temperature increase has cumulative effect on the tissue, being higher, for some time after the confrontation than the time with no confrontation.

  14. Induced Electromagnetic Field by Seismic Waves in Stratified Media in Earth's Magnetic Field

    Science.gov (United States)

    Yamazaki, K.

    2017-12-01

    Seismic waves accompany electromagnetic (EM) variations because Earth's crust involves a variety of EM properties such as finite electrical conductivity and ion contents. If we can catch the EM variations just after the earthquake rupture, we will know the occurrence of earthquake before the arrival of seismic waves at observation point. However, quantitative aspects of EM variations arising from seismic waves have not sufficiently understood. Together with observational works, theoretical works have been made to simulate EM variations arising from seismic waves. The generation mechanisms of EM variations include electrokinetic effect (Pride, 1994), motional induction (Gao et al., 2014), piezo-electric effect (Ogawa and Utada, 2000), piezo-magnetic effect (Yamazaki, 2016), etc. It is widely accepted that the electrokinetic effect is the dominant mechanism. Theoretical calculation of EM variations assuming the electrokinetic effect roughly explains the observed EM variations accompanying with earthquake ground motions (e.g. Gao et al. 2016). However, there are a significant disagreement between observed and predicted EM variations. In the present study, I focus on the motional induction mechanism that possibly explain some parts of EM variations accompanying with seismic waves. A theoretical work on EM variations arising from the motional induction has been presented by Gao et al. (2014), but their work assumed uniform full-space medium. In contrast, the present work assumes stratified media which correctly incorporate the effect of the ground surface. I apply a calculating method developed in seismology (e.g. Kennett, 2013) and in EM studies (Haartsen and Pride, 1997), and derive a set of expressions describing the spatial-temporal variations of the EM field after the onset of rupture. The derived formula is used to calculate EM variations for actual earthquakes to compare the theoretical prediction to observed EM variations.

  15. Topographically induced internal solitary waves in a pycnocline: Ultrasonic probes and stereo-correlation measurements

    International Nuclear Information System (INIS)

    Dossmann, Yvan; Paci, Alexandre; Auclair, Francis; Lepilliez, Mathieu; Cid, Emmanuel

    2014-01-01

    Internal solitary waves (ISWs) are large amplitude stable waves propagating in regions of high density gradients such as the ocean pycnocline. Their dynamics has often been investigated in two-dimensional approaches, however, their three-dimensional evolution is still poorly known. Experiments have been conducted in the large stratified water tank of CNRM-GAME to study the generation of ISWs in two academic configurations inspired by oceanic regimes. First, ultrasonic probes are used to measure the interfacial displacement in the two configurations. In the primary generation case for which the two layers are of constant density, the generation of ISWs is investigated in two series of experiments with varying amplitude and forcing frequency. In the secondary generation case for which the lower layer is stratified, the generation of ISWs from the impact of an internal wave beam on the pycnocline and their subsequent dynamics is studied. The dynamics of ISWs in these two regimes accords well with analytical approaches and numerical simulations performed in analogous configurations. Then, recent developments of a stereo correlation technique are used to describe the three-dimensional structure of propagating ISWs. In the primary generation configuration, small transverse effects are observed in the course of the ISW propagation. In the secondary generation configuration, larger transverse structures are observed in the interfacial waves dynamics. The interaction between interfacial troughs and internal waves propagating in the lower stratified layer are a possible cause for the generation of these structures. The magnitude of these transverse structures is quantified with a nondimensional parameter in the two configurations. They are twice as large in the secondary generation case as in the primary generation case

  16. Wave-induced Maintenance of Suspended Sediment Concentration during Slack in a Tidal Channel on a Sheltered Macro-tidal Flat, Gangwha Island, Korea

    Science.gov (United States)

    Lee, Guan-hong; Kang, KiRyong

    2018-05-01

    A field campaign was conducted to better understand the influence of wave action, in terms of turbulence and bed shear stress, on sediment resuspension and transport processes on a protected tidal flat. An H-frame was deployed in a tidal channel south of Gangwha Island for 6 tidal cycles during November 2006 with instrumentation including an Acoustic Doppler Velocimeter, an Acoustic Backscatter System, and an Optical Backscatter Sensor. During calm conditions, the current-induced shear was dominant and responsible for suspending sediments during the accelerating phases of flood and ebb. During the high-tide slack, both bed shear stress and suspended sediment concentration were reduced. The sediment flux was directed landward due to the scour-lag effect over a tidal cycle. On the other hand, when waves were stronger, the wave-induced turbulence appeared to keep sediments in suspension even during the high-tide slack, while the current-induced shear remained dominant during the accelerating phases of flood and ebb. The sediment flux under strong waves was directed offshore due to the sustained high suspended sediment concentration during the high-tide slack. Although strong waves can induce offshore sediment flux, infrequent events with strong waves are unlikely to alter the long-term accretion of the protected southern Gangwha tidal flats.

  17. Inertial waves in a spherical shell induced by librations of the inner sphere: experimental and numerical results

    Energy Technology Data Exchange (ETDEWEB)

    Koch, S; Harlander, U; Egbers, C [Department of Aerodynamics and Fluid Mechanics, Brandenburg University of Technology Cottbus, Siemens-Halske-Ring 14, D-03046 Cottbus (Germany); Hollerbach, R, E-mail: uwe.harlander@tu-cottbus.de [Institute of Geophysics, ETH Zuerich, Sonneggstrasse 5, CH-8092 Zurich (Switzerland)

    2013-06-15

    We begin with an experimental investigation of the flow induced in a rotating spherical shell. The shell globally rotates with angular velocity {Omega}. A further periodic oscillation with angular velocity 0 Less-Than-Or-Slanted-Equal-To {omega} Less-Than-Or-Slanted-Equal-To 2{Omega}, a so-called longitudinal libration, is added on the inner sphere's rotation. The primary response is inertial waves spawned at the critical latitudes on the inner sphere, and propagating throughout the shell along inclined characteristics. For sufficiently large libration amplitudes, the higher harmonics also become important. Those harmonics whose frequencies are still less than 2{Omega} behave as inertial waves themselves, propagating along their own characteristics. The steady component of the flow consists of a prograde zonal jet on the cylinder tangent to the inner sphere and parallel to the axis of rotation, and increases with decreasing Ekman number. The jet becomes unstable for larger forcing amplitudes as can be deduced from the preliminary particle image velocimetry observations. Finally, a wave attractor is experimentally detected in the spherical shell as the pattern of largest variance. These findings are reproduced in a two-dimensional numerical investigation of the flow, and certain aspects can be studied numerically in greater detail. One aspect is the scaling of the width of the inertial shear layers and the width of the steady jet. Another is the partitioning of the kinetic energy between the forced wave, its harmonics and the mean flow. Finally, the numerical simulations allow for an investigation of instabilities, too local to be found experimentally. For strong libration amplitudes, the boundary layer on the inner sphere becomes unstable, triggering localized Goertler vortices during the prograde phase of the forcing. This instability is important for the transition to turbulence of the spherical shell flow. (paper)

  18. Electro-optically Induced and Manipulated Terahertz Waves from Fe-doped InGaAs Surfaces

    Science.gov (United States)

    Hatem, O.

    2018-03-01

    We demonstrate the presence of dual simultaneous nonlinear mechanisms: field-induced optical rectification (FIOR) and field-induced surge current (FISC) for the generation of terahertz (THz) pulses from p-type and n-type Fe:In0.53Ga0.47As surfaces upon excitation with femtosecond laser pulses centered at 800 nm wavelength. Experimental investigations of the dependence of the generated THz waves on the incident angular optical polarization, optical irradiance, and the direction and magnitude of applied electric DC fields give confirming results to the proposed THz generation mechanisms. Applying external DC electric fields in the plane of the incident optical field shows efficient capability in manipulating the direction and phase of the generated THz waves, and controlling the refractive index of Fe:In0.53Ga0.47As material in the THz range, in addition to enhancing the emitted THz power up to two orders of magnitude. The fast and reliable response of Fe:In0.53Ga0.47As to the changes in the direction and magnitude of the optical and electrical fields suggests its use in amplitude and phase modulators, and ultrafast optoelectronic systems.

  19. Sci-Thur AM: YIS – 02: Imaging dose distributions through the detection of radiation-induced acoustic waves

    Energy Technology Data Exchange (ETDEWEB)

    Hickling, Susannah; Lei, Hao; Hobson, Maritza; Leger, Pierre; Wang, Xueding; El Naqa, Issam [University of Michigan, McGill University, McGill University , University of Michigan, University of Michigan/McGill University (United States)

    2016-08-15

    Purpose: X-ray acoustic computed tomography (XACT) is an emerging technique that images the dose deposited within an object following linac irradiation by detecting acoustic waves induced via the photoacoustic effect. This work shows that XACT images can be formed in soft-tissue equivalent material and that dosimetric information can be extracted from such images. Methods: Acoustic waves induced in a water tank following irradiation by a 10 MV flattening filter free photon beam were detected with an immersion ultrasound transducer at 60 angles surrounding the radiation field. A back-projection algorithm was used to reconstruct an XACT image from the detected transducer signals. Profiles extracted from XACT images were compared to profiles measured with ion chambers as per the current clinical protocol. Results: XACT images were successfully formed of simple 4 cm × 4 cm and 6 cm × 3 cm fields, as well as of more complicated multi-leaf collimator defined fields. For the 6 cm × 3 cm field, 74% and 87% of the XACT profile points in the 6 cm and 3 cm dimensions, respectively, passed a 7% / 4 mm gamma test when compared to ion chamber measurements. In a complicated puzzle piece shaped field, 86% of the pixels in an extracted profile passed a 7% / 4 mm gamma test. Conclusions: XACT is capable of imaging the dose distribution delivered by a variety of field sizes and shapes in water, and is a viable technique for both water tank and in vivo dosimetry.

  20. Linear acoustic waves induced in a cylindrical solid target by particle beam in e--e+ colliders

    International Nuclear Information System (INIS)

    Adeyemi, Olufemi Segun

    2015-06-01

    A future high energy lepton collider will demand high luminosities to achieve its physics goals. For the electron-positron linear collider, the generation of the desired amount of positrons is a non-trivial problem: the positron production target has to survive huge amounts of energy deposited by the bombardment of intense beams of electrons or photons. This causes a rapid increase of the temperature in the target within a very short time period. The resulting deformation due to the induced pressure waves can substantially shorten the operating life-span of the target material. In this work, we study linear effects of induced stress in a solid target through pressure acoustic waves using continuum mechanics. We derived analytical solutions for different cases and imposed different boundary conditions. The application of the model to the SLC positron target gave us the results which are in agreement with the existing literature. In a similar manner, we investigated the effect of single and multiple photon bunches on the conversion target for ILC.

  1. Rings in drugs.

    Science.gov (United States)

    Taylor, Richard D; MacCoss, Malcolm; Lawson, Alastair D G

    2014-07-24

    We have analyzed the rings, ring systems, and frameworks in drugs listed in the FDA Orange Book to understand the frequency, timelines, molecular property space, and the application of these rings in different therapeutic areas and target classes. This analysis shows that there are only 351 ring systems and 1197 frameworks in drugs that came onto the market before 2013. Furthermore, on average six new ring systems enter drug space each year and approximately 28% of new drugs contain a new ring system. Moreover, it is very unusual for a drug to contain more than one new ring system and the majority of the most frequently used ring systems (83%) were first used in drugs developed prior to 1983. These observations give insight into the chemical novelty of drugs and potentially efficient ways to assess compound libraries and develop compounds from hit identification to lead optimization and beyond.

  2. Birth Control Ring

    Science.gov (United States)

    ... Health Food & Fitness Diseases & Conditions Infections Drugs & Alcohol School & Jobs Sports Expert Answers (Q&A) Staying Safe Videos for Educators Search English Español Birth Control Ring KidsHealth / For Teens / Birth Control Ring What's ...

  3. The Electromechanical Behavior of a Micro-Ring Driven by Traveling Electrostatic Force

    Science.gov (United States)

    Ye, Xiuqian; Chen, Yibao; Chen, Da-Chih; Huang, Kuo-Yi; Hu, Yuh-Chung

    2012-01-01

    There is no literature mentioning the electromechanical behavior of micro structures driven by traveling electrostatic forces. This article is thus the first to present the dynamics and stabilities of a micro-ring subjected to a traveling electrostatic force. The traveling electrostatic force may be induced by sequentially actuated electrodes which are arranged around the flexible micro-ring. The analysis is based on a linearized distributed model considering the electromechanical coupling effects between electrostatic force and structure. The micro-ring will resonate when the traveling speeds of the electrostatic force approach some critical speeds. The critical speeds are equal to the ratio of the natural frequencies to the wave number of the correlative natural mode of the ring. Apart from resonance, the ring may be unstable at some unstable traveling speeds. The unstable regions appear not only near the critical speeds, but also near some fractions of some critical speeds differences. Furthermore the unstable regions expand with increasing driving voltage. This article may lead to a new research branch on electrostatic-driven micro devices. PMID:22438705

  4. Groups, rings, modules

    CERN Document Server

    Auslander, Maurice

    2014-01-01

    This classic monograph is geared toward advanced undergraduates and graduate students. The treatment presupposes some familiarity with sets, groups, rings, and vector spaces. The four-part approach begins with examinations of sets and maps, monoids and groups, categories, and rings. The second part explores unique factorization domains, general module theory, semisimple rings and modules, and Artinian rings. Part three's topics include localization and tensor products, principal ideal domains, and applications of fundamental theorem. The fourth and final part covers algebraic field extensions

  5. Unidirectional Spin-Wave-Propagation-Induced Seebeck Voltage in a PEDOT:PSS/YIG Bilayer

    Science.gov (United States)

    Wang, P.; Zhou, L. F.; Jiang, S. W.; Luan, Z. Z.; Shu, D. J.; Ding, H. F.; Wu, D.

    2018-01-01

    We clarify the physical origin of the dc voltage generation in a bilayer of a conducting polymer film and a micrometer-thick magnetic insulator Y3Fe5O12 (YIG) film under ferromagnetic resonance and/or spin wave excitation conditions. The previous attributed mechanism, the inverse spin Hall effect in the polymer [Nat. Mater. 12, 622 (2013), 10.1038/nmat3634], is excluded by two control experiments. We find an in-plane temperature gradient in YIG which has the same angular dependence with the generated voltage. Both vanish when the YIG thickness is reduced to a few nanometers. Thus, we argue that the dc voltage is governed by the Seebeck effect in the polymer, where the temperature gradient is created by the nonreciprocal magnetostatic surface spin wave propagation in YIG.

  6. Detecting free-mass common-mode motion induced by incident gravitational waves

    Science.gov (United States)

    Tobar, Michael Edmund; Suzuki, Toshikazu; Kuroda, Kazuaki

    1999-05-01

    In this paper we show that information on both the differential and common mode free-mass response to a gravitational wave can provide important information on discriminating the direction of the gravitational wave source and between different theories of gravitation. The conventional Michelson interferometer scheme only measures the differential free-mass response. By changing the orientation of the beam splitter, it is possible to configure the detector so it is sensitive to the common-mode of the free-mass motion. The proposed interferometer is an adaptation of the Fox-Smith interferometer. A major limitation to the new scheme is its enhanced sensitivity to laser frequency fluctuations over the conventional, and we propose a method of cancelling these fluctuations. The configuration could be used in parallel to the conventional differential detection scheme with a significant sensitivity and bandwidth.

  7. Solar-flare-induced Forbush decreases - Dependence on shock wave geometry

    Science.gov (United States)

    Thomas, B. T.; Gall, R.

    1984-01-01

    It is argued that the principal mechanism for the association of Forbush decreases with the passage of a solar flare shock wave is prolonged containment of cosmic ray particles behind the flare compression region, which acts as a semipermeable obstacle to particle motion along the field lines, leading to additional adiabatic cooling of the particles. Liouville's theorem is used to calculate the instantaneous distribution function at 1 AU for each particle arriving at the earth. By averaging over a large number of individual estimates, a representative estimate of the omnidirectional phase space density and the corresponding particle intensity is obtained. The energy change of individual particles at the shocks is found to be small in comparison to the energy lost by adiabatic cooling of the cosmic rays between the shock wave and the sun. The effects of particle rigidity, diffusion coefficient, and flare longitude on the magnitude of the Forbush decrease are quantitatively investigated.

  8. Mitigation of Traffic-Induced Ground Vibration by Inclined Wave Barriers

    DEFF Research Database (Denmark)

    Andersen, Lars; Augustesen, Anders Hust

    2009-01-01

    Double sheet pile walls can be used as wave barriers in order to mitigate ground vibrations from railways. The present analysis concerns the efficiency of such barriers, especially with regard to the influence of the barrier inclination and the backfill between the walls. Thus, the screening capa...... of reference following the load. This allows a computation of the steady state response to a harmonically varying point source moving at different speeds typical for a train....

  9. Phase control of electromagnetically induced acoustic wave transparency in a diamond nanomechanical resonator

    Energy Technology Data Exchange (ETDEWEB)

    Evangelou, Sofia, E-mail: Evangelousof@gmail.com

    2017-05-10

    Highlights: • A high-Q single-crystal diamond nanomechanical resonator embedded with nitrogen-vacancy (NV) centers is studied. • A Δ-type coupling configuration is formed. • The spin states of the ground state triplet of the NV centers interact with a strain field and two microwave fields. • The absorption and dispersion properties of the acoustic wave field are controlled by the use of the relative phase of the fields. • Phase-dependent acoustic wave absorption, transparency, and gain are obtained. • “Slow sound” and negative group velocities are also possible. - Abstract: We consider a high-Q single-crystal diamond nanomechanical resonator embedded with nitrogen-vacancy (NV) centers. We study the interaction of the transitions of the spin states of the ground state triplet of the NV centers with a strain field and two microwave fields in a Δ-type coupling configuration. We use the relative phase of the fields for the control of the absorption and dispersion properties of the acoustic wave field. Specifically, we show that by changing the relative phase of the fields, the acoustic field may exhibit absorption, transparency, gain and very interesting dispersive properties.

  10. Selective enhancement of Selényi rings induced by the cross-correlation between the interfaces of a two-dimensional randomly rough dielectric film

    Science.gov (United States)

    Banon, J.-P.; Hetland, Ø. S.; Simonsen, I.

    2018-02-01

    By the use of both perturbative and non-perturbative solutions of the reduced Rayleigh equation, we present a detailed study of the scattering of light from two-dimensional weakly rough dielectric films. It is shown that for several rough film configurations, Selényi interference rings exist in the diffusely scattered light. For film systems supported by dielectric substrates where only one of the two interfaces of the film is weakly rough and the other planar, Selényi interference rings are observed at angular positions that can be determined from simple phase arguments. For such single-rough-interface films, we find and explain by a single scattering model that the contrast in the interference patterns is better when the top interface of the film (the interface facing the incident light) is rough than when the bottom interface is rough. When both film interfaces are rough, Selényi interference rings exist but a potential cross-correlation of the two rough interfaces of the film can be used to selectively enhance some of the interference rings while others are attenuated and might even disappear. This feature may in principle be used in determining the correlation properties of interfaces of films that otherwise would be difficult to access.

  11. Interferometric investigation of shock waves induced by a TEA-CO2 laser produced plasma in air in front of a solid target

    International Nuclear Information System (INIS)

    Apostol, D.; Apostol, I.; Cojocaru, E.; Draganescu, V.; Mihailescu, N.I.; Morjan, I.; Konov, I.V.

    1979-06-01

    The shock waves induced in the surrounding atmosphere by an air plasma were investigated by laser interferometry. The air breakdown plasma was produced by a TEA-CO 2 laser in front of a solid target. The results were compared to the predictions of theory of intense explosions in gases and a good agreement was inferred. It was also determined that the symmetry of the expansion of the initial shock wave is determined by the plasma source shape and, accordingly, depends on the laser power density incident on the target surface. However, for further stages all the shock waves expand spherically. (author)

  12. SU-G-201-13: Investigation of Dose Variation Induced by HDR Ir-192 Source Global Shift Within the Varian Ring Applicator Using Monte Carlo Methods

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Y; Cai, J; Meltsner, S; Chang, Z; Craciunescu, O [Duke University Medical Center, Durham, NC (United States)

    2016-06-15

    Purpose: The Varian tandem and ring applicators are used to deliver HDR Ir-192 brachytherapy for cervical cancer. The source path within the ring is hard to predict due to the larger interior ring lumen. Some studies showed the source could be several millimeters different from planned positions, while other studies demonstrated minimal dosimetric impact. A global shift can be applied to limit the effect of positioning offsets. The purpose of this study was to assess the necessities of implementing a global source shift using Monte Carlo (MC) simulations. Methods: The MCNP5 radiation transport code was used for all MC simulations. To accommodate TG-186 guidelines and eliminate inter-source attenuation, a BrachyVision plan with 10 dwell positions (0.5cm step sizes) was simulated as the summation of 10 individual sources with equal dwell times for simplification. To simplify the study, the tandem was also excluded from the MC model. Global shifts of ±0.1, ±0.3, ±0.5 cm were then simulated as distal and proximal from the reference positions. Dose was scored in water for all MC simulations and was normalized to 100% at the normalization point 0.5 cm from the cap in the ring plane. For dose comparison, Point A was 2 cm caudal from the buildup cap and 2 cm lateral on either side of the ring axis. With seventy simulations, 108 photon histories gave a statistical uncertainties (k=1) <2% for (0.1 cm)3 voxels. Results: Compared to no global shift, average Point A doses were 0.0%, 0.4%, and 2.2% higher for distal global shifts, and 0.4%, 2.8%, and 5.1% higher for proximal global shifts, respectively. The MC Point A doses differed by < 1% when compared to BrachyVision. Conclusion: Dose variations were not substantial for ±0.3 cm global shifts, which is common in clinical practice.

  13. SU-G-201-13: Investigation of Dose Variation Induced by HDR Ir-192 Source Global Shift Within the Varian Ring Applicator Using Monte Carlo Methods

    International Nuclear Information System (INIS)

    Yang, Y; Cai, J; Meltsner, S; Chang, Z; Craciunescu, O

    2016-01-01

    Purpose: The Varian tandem and ring applicators are used to deliver HDR Ir-192 brachytherapy for cervical cancer. The source path within the ring is hard to predict due to the larger interior ring lumen. Some studies showed the source could be several millimeters different from planned positions, while other studies demonstrated minimal dosimetric impact. A global shift can be applied to limit the effect of positioning offsets. The purpose of this study was to assess the necessities of implementing a global source shift using Monte Carlo (MC) simulations. Methods: The MCNP5 radiation transport code was used for all MC simulations. To accommodate TG-186 guidelines and eliminate inter-source attenuation, a BrachyVision plan with 10 dwell positions (0.5cm step sizes) was simulated as the summation of 10 individual sources with equal dwell times for simplification. To simplify the study, the tandem was also excluded from the MC model. Global shifts of ±0.1, ±0.3, ±0.5 cm were then simulated as distal and proximal from the reference positions. Dose was scored in water for all MC simulations and was normalized to 100% at the normalization point 0.5 cm from the cap in the ring plane. For dose comparison, Point A was 2 cm caudal from the buildup cap and 2 cm lateral on either side of the ring axis. With seventy simulations, 108 photon histories gave a statistical uncertainties (k=1) <2% for (0.1 cm)3 voxels. Results: Compared to no global shift, average Point A doses were 0.0%, 0.4%, and 2.2% higher for distal global shifts, and 0.4%, 2.8%, and 5.1% higher for proximal global shifts, respectively. The MC Point A doses differed by < 1% when compared to BrachyVision. Conclusion: Dose variations were not substantial for ±0.3 cm global shifts, which is common in clinical practice.

  14. From coffee ring to spherulites ring of poly(ethylene oxide) film from drying droplet

    Science.gov (United States)

    Hu, Yinchun; Zhang, Xuerong; Qiu, Maibo; Wei, Yan; Zhou, Qiong; Huang, Di

    2018-03-01

    We discuss how the "spherulites ring" morphology and "coffee ring" profile of PEO film formed by the drying droplet at glass substrate with different heating rate. Upon increasing the heating rate of substrate, it is found that deposited PEO film from drying droplet shows the unusually observed "coffee ring" profile and "spherulites ring" morphology. The main mechanism for this phenomenon is proposed to be an enhanced Marangoni convection which is induced by the increased solute concentration gradient and reduced viscous force above 70 °C. A simple formation mechanism of the unusually observed "coffee ring" profile and "spherulites ring" morphology is proposed. These findings can be exploited to trace the center of Marangoni convection, with potential applications in designing the spherulite patterns of crystalline polymer films in ink-jet printing and self-assembly fields.

  15. Laser induced purely-thermal-wave interferometry (PTWI) using a novel photopyroelectric (PPE) instrument

    Science.gov (United States)

    Wang, Chinhua

    A novel purely thermal-wave interferometric technique and its applications to non-contact and non-destructive evaluation of Ti:sapphire laser crystals, high-precision measurement of thermal diffusivity of gases, and high- sensitivity gas (hydrogen) sensors have been successfully developed both theoretically and experimentally. A comprehensive theoretical and experimental analysis of the system noise and detectivity has been conducted to consolidate the basis of the technique. Unlike the conventional single-ended photopyroelectric(PPE) technique, different thermal-wave interference patterns can be obtained by adjusting two incident beams (relative intensity and phase shift) and two thermal-wave cavities on both sides of a pyroelectric detector. It is found that the large base-line signal and large optical noise, which are encountered in the single- ended PPE scheme, can be coherently and completely suppressed in the fully destructive interferometric measurement. Differential surface absorptance, differential and absolute bulk absorption coefficient of Ti:sapphire laser crystals have been separately measured using an extended PPE-interference (PPEI) theory. Unlike the single-ended PPE method, in which thermal contributions from several optical parameters are always coupled together, the destructive interferometric: method provides a unique method for extracting precise values of one of these coupled parameters, without the need of equally precise knowledge of the values of others. The comparison measurement of thermal diffusivity of air using the single-ended PPE method and the PPEI method shows that the PPEI method enhances the measuring precision by one significant figure when compared with the single-beam method. The conventionally used concept of ``thermal-wave reflection coefficient'' has been extended to a more general case that is sample- thickness dependent. A novel hydrogen gas sensor has been initialized and developed based on the PPEI technique. It is

  16. Continuous wave ultraviolet radiation induced frustration of etching in lithium niobate single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Mailis, S.; Riziotis, C.; Smith, P.G.R.; Scott, J.G.; Eason, R.W

    2003-02-15

    Illumination of the -z face of congruent lithium niobate single crystals with continuous wave (c.w.) ultraviolet (UV) laser radiation modifies the response of the surface to subsequent acid etching. A frequency doubled Ar{sup +} laser ({lambda}=244 nm) was used to illuminate the -z crystal face making it resistive to HF etching and thus transforming the illuminated tracks into ridge structures. This process enables the fabrication of relief patterns in a photolithographic manner. Spatially resolved Raman spectroscopy indicates preservation of the good crystal quality after irradiation.

  17. Density wave oscillations of a boiling natural circulation loop induced by flashing

    Energy Technology Data Exchange (ETDEWEB)

    Furuya, Masahiro; Inada, Fumio; Yasuo, Akira [Central Research Institute of Electric Power Industry, Tokyo (Japan)

    1995-09-01

    Experiments are conducted to investigate two-phase flow instabilities in a boiling natural circulation loop with a chimney due to flashing in the chimney at lower pressure. The test facility used in this experiment is designed to have non-dimensional values which are nearly equal to those of natural circulation BWR. Stability maps in reference to the heat flux, the inlet subcooling, the system pressure are presented. This instability is suggested to be density wave oscillations due to flashing in the chimney, and the differences from other phenomena such as flow pattern oscillations and geysering phenomena are discussed by investigating the dynamic characteristics, the oscillation period, and the transient flow pattern.

  18. Imprint of accretion disk-induced migration on gravitational waves from extreme mass ratio inspirals.

    Science.gov (United States)

    Yunes, Nicolás; Kocsis, Bence; Loeb, Abraham; Haiman, Zoltán

    2011-10-21

    We study the effects of a thin gaseous accretion disk on the inspiral of a stellar-mass black hole into a supermassive black hole. We construct a phenomenological angular momentum transport equation that reproduces known disk effects. Disk torques modify the gravitational wave phase evolution to detectable levels with LISA for reasonable disk parameters. The Fourier transform of disk-modified waveforms acquires a correction with a different frequency trend than post-Newtonian vacuum terms. Such inspirals could be used to detect accretion disks with LISA and to probe their physical parameters. © 2011 American Physical Society

  19. Estimating Wind and Wave Induced Forces On a Floating Wind Turbine

    DEFF Research Database (Denmark)

    Henriksen, Lars Christian; Natarajan, Anand; Kim, Taeseong

    2013-01-01

    -principles derived state space model of the floating wind turbine. The ability to estimate aero- and hydrodynamic states could prove crucial for the performance of model-based control methods applied on floating wind turbines. Furthermore, two types of water kinematics have been compared two determine whether......In this work, the basic model for a spar buoy floating wind turbine [1], used by an extended Kalman filter, is presented and results concerning wind speed and wave force estimations are shown. The wind speed and aerodynamic forces are estimated using an extended Kalman filter based on a first...... or not linear and nonlinear water kinematics lead to significantly different loads....

  20. SUPERNOVA SHOCK-WAVE-INDUCED CO-FORMATION OF GLASSY CARBON AND NANODIAMOND

    Energy Technology Data Exchange (ETDEWEB)

    Stroud, Rhonda [Naval Research Laboratory, Washington, D.C.; Chisholm, Matthew F [ORNL; Heck, Phillipp [The Field Museum, Chicago, IL; Alexander, Conel [Carnegie Institution of Washington; Nittler, Larry [Carnegie Institution of Washington

    2011-01-01

    Nanodiamond (ND) was the first extrasolar dust phase to be identified in meteorites. However, the 2 nm average size of the NDs precludes isotopic analysis of individual particles, and thus their origin(s) remains controversial. Using electron microscopy with subnanometer resolution, we show that ND separates from the Allende and Murchison meteorites are actually a two-phase mixture of ND and glassy carbon. This phase mixture is likely the product of supernova shock-wave transformation of pre-formed organics in the interstellar medium (ISM). The glassy carbon ND mixture is also a plausible contributor to the 2175 extinction feature in the diffuse ISM.

  1. SUPERNOVA SHOCK-WAVE-INDUCED CO-FORMATION OF GLASSY CARBON AND NANODIAMOND

    International Nuclear Information System (INIS)

    Stroud, Rhonda M.; Chisholm, Matthew F.; Heck, Philipp R.; Alexander, Conel M. O'D.; Nittler, Larry R.

    2011-01-01

    Nanodiamond (ND) was the first extrasolar dust phase to be identified in meteorites. However, the 2 nm average size of the NDs precludes isotopic analysis of individual particles, and thus their origin(s) remains controversial. Using electron microscopy with subnanometer resolution, we show that ND separates from the Allende and Murchison meteorites are actually a two-phase mixture of ND and glassy carbon. This phase mixture is likely the product of supernova shock-wave transformation of pre-formed organics in the interstellar medium (ISM). The glassy carbon-ND mixture is also a plausible contributor to the 2175 A extinction feature in the diffuse ISM.

  2. Quasitravelling waves

    International Nuclear Information System (INIS)

    Beklaryan, Leva A

    2011-01-01

    A finite difference analogue of the wave equation with potential perturbation is investigated, which simulates the behaviour of an infinite rod under the action of an external longitudinal force field. For a homogeneous rod, describing solutions of travelling wave type is equivalent to describing the full space of classical solutions to an induced one-parameter family of functional differential equations of point type, with the characteristic of the travelling wave as parameter. For an inhomogeneous rod, the space of solutions of travelling wave type is trivial, and their 'proper' extension is defined as solutions of 'quasitravelling' wave type. By contrast to the case of a homogeneous rod, describing the solutions of quasitravelling wave type is equivalent to describing the quotient of the full space of impulsive solutions to an induced one-parameter family of point-type functional differential equations by an equivalence relation connected with the definition of solutions of quasitravelling wave type. Stability of stationary solutions is analyzed. Bibliography: 9 titles.

  3. Effect of heat-induced pain stimuli on pulse transit time and pulse wave amplitude in healthy volunteers.

    Science.gov (United States)

    van Velzen, Marit H N; Loeve, Arjo J; Kortekaas, Minke C; Niehof, Sjoerd P; Mik, Egbert G; Stolker, Robert J

    2016-01-01

    Pain is commonly assessed subjectively by interpretations of patient behaviour and/or reports from patients. When this is impossible the availability of a quantitative objective pain assessment tool based on objective physiological parameters would greatly benefit clinical practice and research beside the standard self-report tests. Vasoconstriction is one of the physiological responses to pain. The aim of this study was to investigate whether pulse transit time (PTT) and pulse wave amplitude (PWA) decrease in response to this vasoconstriction when caused by heat-induced pain. The PTT and PWA were measured in healthy volunteers, on both index fingers using photoplethysmography and electrocardiography. Each subject received 3 heat-induced pain stimuli using a Temperature-Sensory Analyzer thermode block to apply a controlled, increasing temperature from 32.0 °C to 50.0 °C to the skin. After reaching 50.0 °C, the thermode was immediately cooled down to 32.0 °C. The study population was divided into 2 groups with a time-interval between the stimuli 20s or 60s. The results showed a significant (p  Heat-induced pain causes a decrease of PTT and PWA. Consequently, it is expected that, in the future, PTT and PWA may be applied as objective indicators of pain, either beside the standard self-report test, or when self-report testing is impossible.

  4. Study of density jump in helicon-wave induced H2 plasma

    International Nuclear Information System (INIS)

    Jiang Fan; Cheng Xinlu; Xiong Zhenwei; Wu Weidong; Wang Yuying; Gao Yingxue; Dai Yang

    2012-01-01

    Hydrogen plasmas electron density and electron energy distribution function EEDF were studied with Langmuir probe. Two jumps were observed in the variation of the electron density with the radio frequency power. The relative intensity ratio of hydrogen plasmas spectrum line H α , H β and H γ validated this phenomenon. Two density jumps illuminated the transition of discharge mode,which labeled as capacitive, inductive and helicon-wave mode. In this work, the density jumps are explained from two sides, one is the interaction between electrons and hydrogen molecules, the other is Nagoya type III (N-type) antenna-plasma coupling. With the increase of radiofrequency power, the interaction between electron and hydrogen molecule has been enhanced which causes the electron density jumps. The antenna couples well to plasmas when transverse field E y is maximum, and the wave vector of k z locates at π/l a or 3π/l a , corresponding to the first and second density jump. (authors)

  5. Density wave induced star formation: The optical surface brightness of galaxies

    International Nuclear Information System (INIS)

    Bash, F.N.

    1979-01-01

    A model for the galactic orbits of molecular clouds has been devised. The molecular clouds are assumed to be launched from the two-armed spiral-shock wave, to orbit in the Galaxy like ballistic particles with gravitational perturbations due to the density-wave spiral-potential, and each cloud is assumed to produce a cluster of stars. Each cloud radiates detectable 12 C 16 O (J=0→1) spectral line radiation from birth for 40 million years. Stars are seen in the cloud about 25 million years after birth, and the star cluster is assumed to continue in ballistic orbit around the Galaxy.The model has been tested by comparing its predicted velocity-longitude diagram for CO against that observed for the Galaxy and by comparing the model's predicted distribution of light in the UBV photometric bands against observed surface photometry for Sb and SC galaxies. The interpolation of the initial velocities in the model was corrected, and the model was examined to see whether preshock or postshock initial velocities better fit the observations. The model gives very good general agreement and reproduces many of the features observed in the CO velocity-longitude diagram

  6. Low-temperature electron irradiation induced defects in gallium arsenide: bulk and surface acoustic wave studies

    International Nuclear Information System (INIS)

    Brophy, M.J. Jr.

    1985-01-01

    Irradiation of GaAs with 2.25 to 2.5 MeV electrons at temperatures below 190 K produces two peaks in ultrasonic attenuation versus temperature. The defects responsible for both peaks have trigonal symmetry and were observed in n-type and semi-insulating GaAs with bulk and surface acoustic waves (SAW) respectively. Bulk waves at eight frequencies between 9 and 130 MHz and SAW at 73 and 145 MHz were used. The reorientation kinetics of both peaks follow the Arrhenius law. The annealing of both peaks was studied with isochronal and isothermal anneals in the temperature range 200 to 335 K. Peak I anneals with a spectrum of activation energies in the range 0.7-1.1 eV between 220 and 335 K. Peak II anneals with a single activation energy of about 1.1 eV above 300K. The different annealing characteristics indicate that these peaks represent two distinct defects. The annealing above 300 K has not been seen in electrical resistivity measurements, but was observed in earlier length change experiments. Irradiation of GaAs:Cr produces no Cr-radiation defect complexes. The attenuation peak associated with Cr 2+ decrease with electron dose, but starts to recover at 150 K

  7. Nonlinear vibration and radiation from a panel with transition to chaos induced by acoustic waves

    Science.gov (United States)

    Maestrello, Lucio; Frendi, Abdelkader; Brown, Donald E.

    1992-01-01

    The dynamic response of an aircraft panel forced at resonance and off-resonance by plane acoustic waves at normal incidence is investigated experimentally and numerically. Linear, nonlinear (period doubling) and chaotic responses are obtained by increasing the sound pressure level of the excitation. The response time history is sensitive to the input level and to the frequency of excitation. The change in response behavior is due to a change in input conditions, triggered either naturally or by modulation of the bandwidth of the incident waves. Off-resonance, bifurcation is diffused and difficult to maintain, thus the panel response drifts into a linear behavior. The acoustic pressure emanated by the panel is either linear or nonlinear as is the vibration response. The nonlinear effects accumulate during the propagation with distance. Results are also obtained on the control of the panel response using damping tape on aluminum panel and using a graphite epoxy panel having the same size and weight. Good agreement is obtained between the experimental and numerical results.

  8. Testing model parameters for wave-induced dune erosion using observations from Hurricane Sandy

    Science.gov (United States)

    Overbeck, J. R.; Long, J. W.; Stockdon, H. F.

    2017-01-01

    Models of dune erosion depend on a set of assumptions that dictate the predicted evolution of dunes throughout the duration of a storm. Lidar observations made before and after Hurricane Sandy at over 800 profiles with diverse dune elevations, widths, and volumes are used to quantify specific dune erosion model parameters including the dune face slope, which controls dune avalanching, and the trajectory of the dune toe, which controls dune migration. Wave-impact models of dune erosion assume a vertical dune face and erosion of the dune toe along the foreshore beach slope. Observations presented here show that these assumptions are not always valid and require additional testing if these models are to be used to predict coastal vulnerability for decision-making purposes. Observed dune face slopes steepened by 43% yet did not become vertical faces, and only 50% of the dunes evolved along a trajectory similar to the foreshore beach slope. Observations also indicate that dune crests were lowered during dune erosion. Moreover, analysis showed a correspondence between dune lowering and narrower beaches, smaller dune volumes, and/or longer wave impact.

  9. Ultrasonic backscatter imaging by shear-wave-induced echo phase encoding of target locations.

    Science.gov (United States)

    McAleavey, Stephen

    2011-01-01

    We present a novel method for ultrasound backscatter image formation wherein lateral resolution of the target is obtained by using traveling shear waves to encode the lateral position of targets in the phase of the received echo. We demonstrate that the phase modulation as a function of shear wavenumber can be expressed in terms of a Fourier transform of the lateral component of the target echogenicity. The inverse transform, obtained by measurements of the phase modulation over a range of shear wave spatial frequencies, yields the lateral scatterer distribution. Range data are recovered from time of flight as in conventional ultrasound, yielding a B-mode-like image. In contrast to conventional ultrasound imaging, where mechanical or electronic focusing is used and lateral resolution is determined by aperture size and wavelength, we demonstrate that lateral resolution using the proposed method is independent of the properties of the aperture. Lateral resolution of the target is achieved using a stationary, unfocused, single-element transducer. We present simulated images of targets of uniform and non-uniform shear modulus. Compounding for speckle reduction is demonstrated. Finally, we demonstrate image formation with an unfocused transducer in gelatin phantoms of uniform shear modulus.

  10. Preparing isolated vibrational wave packets with light-induced molecular potentials by chirped laser pulses

    Science.gov (United States)

    Vatasescu, Mihaela

    2012-05-01

    We consider a specific wave packet preparation arising from the control of tunneling in the 0g-(6s,6p3/2) double well potential of a Cs2 cold molecule with chirped laser pulses. Such a possibility to manipulate the population dynamics in the 0g-(6s,6p3/2) potential appears in a pump-dump scheme designed to form cold molecules by photoassociation of two cold cesium atoms. The initial population in the 0g-(6s,6p3/2) double well is a wave packet prepared in the outer well at large interatomic distances (94 a0) by a photoassociation step with a first chirped pulse, being a superposition of several vibrational states whose energies surround the energy of a tunneling resonance. Our present work is focused on a second delayed chirped pulse, coupling the 0g-(6s,6p3/2) surface with the a3Σu+(6s,6s) one in the zone of the double well barrier (15 a0) and creating deeply bound cold molecules in the a3Σu+(6s,6s) state. We explore the parameters choice (intensity, duration, chirp rate and sign) for this second pulse, showing that picoseconds pulses with a negative chirp can lead to trapping of population in the inner well in strongly bound vibrational states, out of the resonant tunneling able to transfer it back to the outer well.

  11. ON THE FLARE INDUCED HIGH-FREQUENCY GLOBAL WAVES IN THE SUN

    International Nuclear Information System (INIS)

    Kumar, Brajesh; Venkatakrishnan, P.; Mathur, Savita; GarcIa, R. A.

    2010-01-01

    Recently, Karoff and Kjeldsen presented evidence of strong correlation between the energy in the high-frequency part (5.3 < ν < 8.3 mHz) of the acoustic spectrum of the Sun and the solar X-ray flux. They have used disk-integrated intensity observations of the Sun obtained from the Variability of solar IRradiance and Gravity Oscillations instrument on board Solar and Heliospheric Observatory (SOHO) spacecraft. Similar signature of flares in velocity observations has not been confirmed till now. The study of low-degree high-frequency waves in the Sun is important for our understanding of the dynamics of the deeper solar layers. In this Letter, we present the analysis of the velocity observations of the Sun obtained from the Michelson and Doppler Imager (MDI) and the Global Oscillations at Low Frequencies (GOLF) instruments on board SOHO for some major flare events of the solar cycle 23. Application of wavelet techniques to the time series of disk-integrated velocity signals from the solar surface using the full-disk Dopplergrams obtained from the MDI clearly indicates that there is enhancement of high-frequency global waves in the Sun during the flares. This signature of flares is also visible in the Fourier Power Spectrum of these velocity oscillations. On the other hand, the analysis of disk-integrated velocity observations obtained from the GOLF shows only marginal evidence of effects of flares on high-frequency oscillations.

  12. Reynolds Number Effect on Spatial Development of Viscous Flow Induced by Wave Propagation Over Bed Ripples

    Science.gov (United States)

    Dimas, Athanassios A.; Kolokythas, Gerasimos A.

    Numerical simulations of the free-surface flow, developing by the propagation of nonlinear water waves over a rippled bottom, are performed assuming that the corresponding flow is two-dimensional, incompressible and viscous. The simulations are based on the numerical solution of the Navier-Stokes equations subject to the fully-nonlinear free-surface boundary conditions and appropriate bottom, inflow and outflow boundary conditions. The equations are properly transformed so that the computational domain becomes time-independent. For the spatial discretization, a hybrid scheme is used where central finite-differences, in the horizontal direction, and a pseudo-spectral approximation method with Chebyshev polynomials, in the vertical direction, are applied. A fractional time-step scheme is used for the temporal discretization. Over the rippled bed, the wave boundary layer thickness increases significantly, in comparison to the one over flat bed, due to flow separation at the ripple crests, which generates alternating circulation regions. The amplitude of the wall shear stress over the ripples increases with increasing ripple height or decreasing Reynolds number, while the corresponding friction force is insensitive to the ripple height change. The amplitude of the form drag forces due to dynamic and hydrostatic pressures increase with increasing ripple height but is insensitive to the Reynolds number change, therefore, the percentage of friction in the total drag force decreases with increasing ripple height or increasing Reynolds number.

  13. Fabrication of visible-light-driven Ag/TiO{sub 2} heterojunction composites induced by shock wave

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Chunxiao [School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); Chen, Pengwan, E-mail: pwchen@bit.edu.cn [School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China); State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081 (China); Liu, Jianjun [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Yin, Hao [Institute of Systems Engineering, China Academy of Engineering Physics, Mianyang 612900, Sichuan Province (China); Gao, Xin; Mei, Xiaofeng [State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081 (China)

    2016-09-15

    Using metatitanic acid (H{sub 2}TiO{sub 3}) and silver nitrate (AgNO{sub 3}) as titanium precursor and silver source respectively, a visible-light responsible Ag/TiO{sub 2} heterojunction photocatalyst is successfully prepared by shock wave with detonation-driven flyer impact. X-ray powder diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–visible diffuse reflectance spectroscopy (UV–Vis DRS) and photoluminescence (PL) emission spectra are employed to characterize the phase structure, morphology, chemical composition and optical property of the recovered samples. The results indicate the metatitanic acid transforms to pure rutile TiO{sub 2} phase by shock wave which possess large surface area. Ag nanoparticles cover on the surface of TiO{sub 2} uniformly and a nanojunction structure is formed efficiently, which play important roles as an electron-conduction bridge and in the surface plasmon resonance effect. Ag modification feasibly improves the separation efficiency for photoinduced electron–hole pairs and enhances the visible-light response. Furthermore, due to the further enhanced separation for photogenerated charges resulting from close interfacial contact of the hetero structure, the obtained Ag/TiO{sub 2} photocatalyst exhibit remarkably improved photocatalytic activities (88% within 2 h) than that of P25 and shock induced pure TiO{sub 2} for the degradation of Rhodamine B under simulated sunlight irradiation. The experimental result shows the shock loading is an effective method to get Ag/TiO{sub 2} photocatalyst and offers new ideas to fabricate other heterojunction composite materials. - Highlights: • Shock wave was a new method of material modification. • The Ag/TiO{sub 2} hetero structure was formed efficiently by shock loading. • The visible-light responsible sample showed an enhanced photocatalytic activity. • This work gave new ideas to fabricate other heterojunction materials.

  14. Long-term evolution and gravitational wave radiation of neutron stars with differential rotation induced by r-modes

    International Nuclear Information System (INIS)

    Yu Yunwei; Cao Xiaofeng; Zheng Xiaoping

    2009-01-01

    In a second-order r-mode theory, Sa and Tome found that the r-mode oscillation in neutron stars (NSs) could induce stellar differential rotation, which naturally leads to a saturated state of the oscillation. Based on a consideration of the coupling of the r-modes and the stellar spin and thermal evolution, we carefully investigate the influences of the differential rotation on the long-term evolution of isolated NSs and NSs in low-mass X-ray binaries, where the viscous damping of the r-modes and its resultant effects are taken into account. The numerical results show that, for both kinds of NSs, the differential rotation can significantly prolong the duration of the r-modes. As a result, the stars can keep nearly a constant temperature and constant angular velocity for over a thousand years. Moreover, the persistent radiation of a quasi-monochromatic gravitational wave would also be predicted due to the long-term steady r-mode oscillation and stellar rotation. This increases the detectability of gravitational waves from both young isolated and old accreting NSs. (research papers)

  15. Calculation of laser induced impulse based on the laser supported detonation wave model with dissociation, ionization and radiation

    International Nuclear Information System (INIS)

    Gan, Li; Mousen, Cheng; Xiaokang, Li

    2014-01-01

    In the laser intensity range that the laser supported detonation (LSD) wave can be maintained, dissociation, ionization and radiation take a substantial part of the incidence laser energy. There is little treatment on the phenomenon in the existing models, which brings obvious discrepancies between their predictions and the experiment results. Taking into account the impact of dissociation, ionization and radiation in the conservations of mass, momentum and energy, a modified LSD wave model is developed which fits the experimental data more effectively rather than the existing models. Taking into consideration the pressure decay of the normal and the radial rarefaction, the laser induced impulse that is delivered to the target surface is calculated in the air; and the dependencies of impulse performance on laser intensity, pulse width, ambient pressure and spot size are indicated. The results confirm that the dissociation is the pivotal factor of the appearance of the momentum coupling coefficient extremum. This study focuses on a more thorough understanding of LSD and the interaction between laser and matter

  16. Calculation of laser induced impulse based on the laser supported detonation wave model with dissociation, ionization and radiation

    Energy Technology Data Exchange (ETDEWEB)

    Gan, Li, E-mail: ligan0001@gmail.com; Mousen, Cheng; Xiaokang, Li [College of Aerospace Science and Engineering, National University of Defense Technology, Changsha (China)

    2014-03-15

    In the laser intensity range that the laser supported detonation (LSD) wave can be maintained, dissociation, ionization and radiation take a substantial part of the incidence laser energy. There is little treatment on the phenomenon in the existing models, which brings obvious discrepancies between their predictions and the experiment results. Taking into account the impact of dissociation, ionization and radiation in the conservations of mass, momentum and energy, a modified LSD wave model is developed which fits the experimental data more effectively rather than the existing models. Taking into consideration the pressure decay of the normal and the radial rarefaction, the laser induced impulse that is delivered to the target surface is calculated in the air; and the dependencies of impulse performance on laser intensity, pulse width, ambient pressure and spot size are indicated. The results confirm that the dissociation is the pivotal factor of the appearance of the momentum coupling coefficient extremum. This study focuses on a more thorough understanding of LSD and the interaction between laser and matter.

  17. Consequences of induced transparency in a double-Λ scheme: Destructive interference in four-wave mixing

    International Nuclear Information System (INIS)

    Payne, M.G.; Deng, L.

    2002-01-01

    We investigate a four-state system interacting with long and short laser pulses in a weak probe beam approximation. We show that when all lasers are tuned to the exact unperturbed resonances, part of the four-wave mixing (FWM) field is strongly absorbed. The part that is not absorbed has the exact intensity required to destructively interfere with the excitation pathway involved in producing the FWM state. We show that with this three-photon destructive interference, the conversion efficiency can still be as high as 25%. Contrary to common belief, our calculation shows that this process, where an ideal one-photon electromagnetically induced transparency is established, is not most suitable for high-efficiency conversion. With appropriate phase matching and propagation distance, and when the three-photon destructive interference does not occur, we show that the photon flux conversion efficiency is independent of probe intensity and can be close to 100%. In addition, we show clearly that the conversion efficiency is not determined by the maximum atomic coherence between two lower excited states, as commonly believed. It is the combination of phase matching and constructive interference involving the two terms arising in producing the mixing wave that is the key element for the optimized FWM generation. Indeed, in this scheme no appreciable excited state is produced, so that the atomic coherence between states vertical bar 0> and vertical bar 2> is always very small

  18. Corneal iron ring after conductive keratoplasty.

    Science.gov (United States)

    Kymionis, George D; Naoumidi, Tatiana L; Aslanides, Ioannis M; Pallikaris, Ioannis G

    2003-08-01

    To report formation of corneal iron ring deposits after conductive keratoplasty. Observational case report. Case report. A 54-year-old woman underwent conductive keratoplasty for hyperopia. One year after conductive keratoplasty, iron ring pattern pigmentation was detected at the corneal epithelium of both eyes. This is the first report of the appearance of corneal iron ring deposits following conductive keratoplasty treatment in a patient. It is suggested that alterations in tear film stability, resulting from conductive keratoplasty-induced changes in corneal curvature, constitute the contributory factor for these deposits.

  19. Molecular detection with terahertz waves based on absorption-induced transparency metamaterials

    Science.gov (United States)

    G. Rodrigo, Sergio; Martín-Moreno, L.

    2016-10-01

    A system for the detection of spectral signatures of chemical compounds at the Terahertz regime is presented. The system consists on a holey metal film whereby the presence of a given substance provokes the appearance of spectral features in transmission and reflection induced by the molecular specimen. These induced effects can be regarded as an extraordinary optical transmission phenomenon called absorption-induced transparency (AIT). The phenomenon consist precisely in the appearance of peaks in transmission and dips in reflection after sputtering of a chemical compound onto an initially opaque holey metal film. The spectral signatures due to AIT occur unexpectedly close to the absorption energies of the molecules. The presence of a target, a chemical compound, would be thus revealed as a strong drop in reflectivity measurements. We theoretically predict the AIT based system would serve to detect amounts of hydrocyanic acid (HCN) at low rate concentrations.

  20. Influence of local hyperthermia induced by micro-waves and X-rays on the Walker carcinoma of the rat

    International Nuclear Information System (INIS)

    Brueckner, V.; Zywietz, F.; Jung, H.

    1979-01-01

    The authors studied the influence on the solid Walker carcinoma in the rat exerted by a slight hyperthermia induced by micro-waves, which was applied alone and combined with X-ray irradiations. It could be demonstrated that the tumor has the same temperature as the sub-peritoneal region. Thus the final temperature reached by the treatment with microwaves can be exactly controlled. Heating up to 41 0 C for 30 minutes produces an increase of the survival rate of animals with tumors of 2 to 6 grams from 17% to 27%, whereas the healing rate is 57% after an X-ray irradiation with 1130 rad and 75% after the combined treatment. Each of the three therapy methods produces a significant prolongation of the survival time of the dying animals. The disadvantes of an anisologic tumor-host system are discussed on the basis of the results achieved. (orig.) [de

  1. Ultrafast dynamics in CeTe{sub 3} near the pressure-induced charge-density-wave transition

    Energy Technology Data Exchange (ETDEWEB)

    Tauch, Jonas; Obergfell, Manuel [Department of Physics and Center for Applied Photonics, University of Konstanz (Germany); Schaefer, Hanjo [Department of Physics and Center for Applied Photonics, University of Konstanz (Germany); Institute of Physics, Ilmenau University of Technology (Germany); Demsar, Jure [Department of Physics and Center for Applied Photonics, University of Konstanz (Germany); Institute of Physics, Ilmenau University of Technology (Germany); Institute of Physics, Johannes Gutenberg-University Mainz (Germany); Giraldo, Paula; Fisher, Ian R. [Geballe Laboratory for Advanced Materials and Department of Applied Physics, Stanford University (United States); Pashkin, Alexej [Department of Physics and Center for Applied Photonics, University of Konstanz (Germany); Helmholtz-Zentrum Dresden-Rossendorf (Germany)

    2015-07-01

    Femtosecond pump-probe spectroscopy is an efficient tool for studying ultrafast dynamics in strongly correlated electronic systems, in particular, compounds with a charge-density-wave (CDW) order. Application of external pressure often leads to a suppression of a CDW state due to an impairment of the Fermi surface nesting. We combine time-resolved optical spectroscopy and diamond anvil cell technology to study electron and lattice dynamics in tri-telluride compound CeTe{sub 3}. Around pressures of 4 GPa we observe a gradual vanishing of the relaxation process related to the recombination of the photoexcited quasiparticles. The coherent oscillations of the phonon modes coupled to the CDW order parameter demonstrate even more dramatic suppression with increasing pressure. These observations clearly indicate a transition into the metallic state of CeTe{sub 3} induced by the external pressure.

  2. Dominant phonon wave vectors and strain-induced splitting of the 2D Raman mode of graphene

    Science.gov (United States)

    Narula, Rohit; Bonini, Nicola; Marzari, Nicola; Reich, Stephanie

    2012-03-01

    The dominant phonon wave vectors q* probed by the 2D Raman mode of pristine and uniaxially strained graphene are determined via a combination of ab initio calculations and a full two-dimensional integration of the transition matrix. We show that q* are highly anisotropic and rotate about K with the polarizer and analyzer condition relative to the lattice. The corresponding phonon-mediated electronic transitions show a finite component along K-Γ that sensitively determines q*. We invalidate the notion of “inner” and “outer” processes. The characteristic splitting of the 2D mode of graphene under uniaxial tensile strain and given polarizer and analyzer setting is correctly predicted only if the strain-induced distortion and red-shift of the in-plane transverse optical (iTO) phonon dispersion as well as the changes in the electronic band structure are taken into account.

  3. An Archetype Semi-Ring Fabry-Perot (SRFP) Resonator

    Science.gov (United States)

    Taghavi-Larigani, Shervin; VanZyl, Jakob

    2009-01-01

    We introduce and demonstrate the generation of a novel resonator, termed Semi-Ring Fabry-Perot (SRFP), that exhibits unique features, such as, its use of one plane mirror, allowing the SRFP to be easily fabricated as a symmetrical device. In addition to its unique features, it exhibits advantages of ring and Fabry-Perot resonators: 1) compared to a ring resonator that only allows a transmitted intensity, the Semi-Ring Fabry-Perot (SRFP) supports standing waves, allowing both a reflected and transmitted intensity; 2) the reflected light spectrum of the SRFP resonator is much narrower than similar Fabry-Perot, implying higher finesse.

  4. Oblique Wave-Induced Responses of A VLFS Edged with A Pair of Inclined Perforated Plates

    Science.gov (United States)

    Cheng, Yong; Ji, Chun-yan; Zhai, Gang-jun; Oleg, Gaidai

    2018-03-01

    This paper is concerned with the hydroelastic responses of a mat-like, rectangular very large floating structure (VLFS) edged with a pair of horizontal/inclined perforated anti-motion plates in the context of the direct coupling method. The updated Lagrangian formulae are applied to establish the equilibrium equations of the VLFS and the total potential formula is employed for fluids in the numerical model including the viscous effect of the perforated plates through the Darcy's law. The hybrid finite element-boundary element (FE-BE) method is implemented to determine the response reduction of VLFS with attached perforated plates under various oblique incident waves. Also, the numerical solutions are validated against a series of experimental tests. The effectiveness of the attached perforated plates in reducing the deflections of the VLFS can be significantly improved by selecting the proper design parameters such as the porous parameter, submergence depth, plate width and inclination angle for the given sea conditions.

  5. Sulfite induced autoxidation of Cu(II/tetra/ penta and hexaglycine complexes: spectrophotometric and rotating-ring-disk glassy carbon electrode studies and analytical potentialities

    Directory of Open Access Journals (Sweden)

    Alipázaga Maria V.

    2003-01-01

    Full Text Available The oxidation of Cu(II complexes with tetra, penta and hexaglycine in borate buffer aqueous solution, by dissolved oxygen is strongly accelerated by sulfite. The formation of Cu(III complexes with maximum absorbances at 250 nm (e = 9000 mol-1 L cm-1 and 365 nm (e = 7120 mol-1 L cm-1 was also characterized by using rotating ring-disk voltammetry, whose anodic and cathodic components were observed in voltammograms recorded in solutions containing Cu(II. Voltammograms, obtained at various rotation speeds, showed that the Cu(III species electrochemically generated is not stable over the entire time window of the experiment and in solutions containing tetraglycine the overall limiting current is controlled by the kinetics of an equilibrium involving Cu(II species.The calculated first order rate constant of the decomposition was 4.37x10-3 s-1. Electrochemical experiments carried out in Cu(II solutions after the addition of relatively small amounts of sulfite demonstrated that the Cu(III species formed in the chemical reaction is the same as the one collected at the ring electrode when Cu(II is oxidized at the disk electrode in ring-disk voltammetry. The concentration of Cu(III complexes is proportional to the amount of added sulfite and the results indicated that indirect analytical methods for sulfite may be developed by means of spectrophotometric or amperometric detection of the chemically generated product.

  6. Induced spin-accumulation and spin-polarization in a quantum-dot ring by using magnetic quantum dots and Rashba spin-orbit effect

    International Nuclear Information System (INIS)

    Eslami, L.; Faizabadi, E.

    2014-01-01

    The effect of magnetic contacts on spin-dependent electron transport and spin-accumulation in a quantum ring, which is threaded by a magnetic flux, is studied. The quantum ring is made up of four quantum dots, where two of them possess magnetic structure and other ones are subjected to the Rashba spin-orbit coupling. The magnetic quantum dots, referred to as magnetic quantum contacts, are connected to two external leads. Two different configurations of magnetic moments of the quantum contacts are considered; the parallel and the anti-parallel ones. When the magnetic moments are parallel, the degeneracy between the transmission coefficients of spin-up and spin-down electrons is lifted and the system can be adjusted to operate as a spin-filter. In addition, the accumulation of spin-up and spin-down electrons in non-magnetic quantum dots are different in the case of parallel magnetic moments. When the intra-dot Coulomb interaction is taken into account, we find that the electron interactions participate in separation between the accumulations of electrons with different spin directions in non-magnetic quantum dots. Furthermore, the spin-accumulation in non-magnetic quantum dots can be tuned in the both parallel and anti-parallel magnetic moments by adjusting the Rashba spin-orbit strength and the magnetic flux. Thus, the quantum ring with magnetic quantum contacts could be utilized to create tunable local magnetic moments which can be used in designing optimized nanodevices.

  7. Current induced multi-mode propagating spin waves in a spin transfer torque nano-contact with strong perpendicular magnetic anisotropy

    Science.gov (United States)

    Mohseni, S. Morteza; Yazdi, H. F.; Hamdi, M.; Brächer, T.; Mohseni, S. Majid

    2018-03-01

    Current induced spin wave excitations in spin transfer torque nano-contacts are known as a promising way to generate exchange-dominated spin waves at the nano-scale. It has been shown that when these systems are magnetized in the film plane, broken spatial symmetry of the field around the nano-contact induced by the Oersted field opens the possibility for spin wave mode co-existence including a non-linear self-localized spin-wave bullet and a propagating mode. By means of micromagnetic simulations, here we show that in systems with strong perpendicular magnetic anisotropy (PMA) in the free layer, two propagating spin wave modes with different frequency and spatial distribution can be excited simultaneously. Our results indicate that in-plane magnetized spin transfer nano-contacts in PMA materials do not host a solitonic self-localized spin-wave bullet, which is different from previous studies for systems with in plane magnetic anisotropy. This feature renders them interesting for nano-scale magnonic waveguides and crystals since magnon transport can be configured by tuning the applied current.

  8. Tidal-Induced Internal Ocean Waves as an Explanation for Enceladus' Tiger Stripe Pattern and Hotspot Activity

    Science.gov (United States)

    Vermeersen, B. L. A.; Maas, L. R.; van Oers, S.; Rabitti, A.; Jara-Orue, H.

    2014-12-01

    One of the most peculiar features on Saturn moon Enceladus is its so-called tiger stripe pattern at the geologically active South Polar Terrain (SPT), as first observed in detail by the Cassini spacecraft early 2005. It is generally assumed that the four almost parallel surface lines that constitute this pattern are faults in the icy surface overlying a confined salty water reservoir. Indeed, later Cassini observations have shown that salty water jets originate from the tiger stripes [e.g., Hansen et al., Science, 311, 1422-1425, 2006; Postberg et al., Nature, 474, 620-622, 2011]. More recently, Porco et al. [Astron. J., 148:45, Sep. 2014] and Nimmo et al. [Astron. J., 148:46, Sep. 2014] have reported strong evidence that the geysers are not caused by frictional heating at the surface, but that geysers must originate deeper in Enceladus' interior. Tidal flexing models, like those of Hurford et al., Nature, 447, 292-294, 2007, give a good match for the brightness variations Cassini observes, but they seem to fail to reproduce the exact timing of plume brightening. Although jet activity is thus strongly connected to tidal forcing, another mechanism must be involved as well. Last year, we formulated the original idea [Vermeersen et al., AGU Fall Meeting 2013, abstract #P53B-1848] that the tiger stripe pattern is formed and maintained by induced, tidally and rotationally driven, wave-attractor motions in the ocean underneath the icy surface of the tiger-stripe region. Such wave-attractor motions are observed in water tank experiments in laboratories on Earth and in numerical experiments [Maas et al., Nature, 338, 557-561, 1997; Drijfhout and Maas, J. Phys. Oceanogr., 37, 2740-2763, 2007; Hazewinkel et al., Phys. Fluids, 22, 107102, 2010]. The latest observations by Porco et al. and Nimmo et al. seem to be in agreement with this tidal-induced wave attractor phenomenon, both with respect to tiger stripe pattern and with respect to timing of hotspot activity. However, in

  9. Token Ring Project

    Directory of Open Access Journals (Sweden)

    Adela Ionescu

    2007-01-01

    Full Text Available Ring topology is a simple configuration used to connect processes that communicate among themselves. A number of network standards such as token ring, token bus, and FDDI are based on the ring connectivity. This article will develop an implementation of a ring of processes that communicate among themselves via pipe links. The processes are nodes in the ring. Each process reads from its standard input and writes in its standard output. N-1 process redirects the its standard output to a standard input of the process through a pipe. When the ring-structure is designed, the project can be extended to simulate networks or to implement algorithms for mutual exclusion

  10. Saturn's Ring: Pre-Cassini Status and Mission Goals

    Science.gov (United States)

    Cuzzi, Jeff N.; DeVincenzi, Donald L. (Technical Monitor)

    1999-01-01

    In November 1980, and again in August 1981, identical Voyager spacecraft flew through the Saturn system, changing forever the way we think about planetary rings. Although Saturn's rings had been the only known ring system for three centuries, a ring system around Uranus had been discovered by stellar occultations from Earth in 1977, and the nearly transparent ring of Jupiter was imaged by Voyager in 1979 (the presence of material there had been inferred from charged particle experiments on Pioneer 10 and 11 several years earlier). While Saturn had thus temporarily lost its uniqueness as having the only ring system, with Voyager it handily recaptured the role of having the most fascinating one. The Voyager breakthroughs included spiral density and bending waves such as cause galactic structure; ubiquitous fine-scale radial 'irregular' structure, with the appearance of record-grooves; regional and local variations in particle color; complex, azimuthally variable ring structure; empty gaps in the rings, some containing very regular, sharp-edged, elliptical rings and one containing both a small moonlet and incomplete arcs of dusty material; and shadowy 'spokes' that flicker across the main rings. One of the paradigm shifts of this period was the realization that many aspects of planetary rings, and even the ring systems themselves, could be 'recent' on geological timescales. These early results are reviewed and summarized in the Arizona Space Science series volumes 'Saturn'. (An excellent review of ring dynamics at a formative stage is by Goldreich and Tremaine.) From the mid 1980's to the time of this writing, progress has been steady, while at a less heady pace, and some of the novel ring properties revealed by Voyager 1 and 2 are beginning to be better understood. It is clearly impossible to cite, much less review, every advance over the last decade; however, below we summarize the main advances in understanding of Saturn's rings since the mid 1980's, in the context

  11. Token ring technology report

    CERN Document Server

    2013-01-01

    Please note this is a Short Discount publication. This report provides an overview of the IBM Token-Ring technology and products built by IBM and compatible vendors. It consists of two sections: 1. A summary of the design trade-offs for the IBM Token-Ring. 2. A summary of the products of the major token-ring compatible vendors broken down by adapters and components, wiring systems, testing, and new chip technology.

  12. Radioactive gold ring dermatitis

    International Nuclear Information System (INIS)

    Miller, R.A.; Aldrich, J.E.

    1990-01-01

    A superficial squamous cell carcinoma developed in a woman who wore a radioactive gold ring for more than 30 years. Only part of the ring was radioactive. Radiation dose measurements indicated that the dose to basal skin layer was 2.4 Gy (240 rad) per week. If it is assumed that the woman continually wore her wedding ring for 37 years since purchase, she would have received a maximum dose of approximately 4600 Gy

  13. Manifestation of J wave induced by acetylcholine applied for a coronary spasm provocation test in a patient with aborted sudden cardiac death.

    Science.gov (United States)

    Kodama, Hiroyuki; Fujita, Kazumasa; Moriyama, Shouhei; Irie, Kei; Noda, Hirotaka; Yokoyama, Taku; Fukata, Mitsuhiro; Arita, Takeshi; Odashiro, Keita; Maruyama, Toru; Akashi, Koichi

    2017-06-01

    A 51-year-old man with a resuscitation episode was referred to our hospital. Coronary angiography revealed a focal spasm overlapped with organic stenosis where a bare metal stent was implanted. Acetylcholine (ACh) provocation test did not induce chest pain. It revealed no discernible ST-T changes but unmasked a J wave at the end of the QRS complex, which was associated with short-coupled repetitive premature ventricular beats. A J wave reportedly appears immediately before the onset of ventricular fibrillation caused by vasospastic angina. However, a J wave observed newly after a coronary spasm provocation test using ACh without ST-T changes is informative when considering the mechanisms of the J wave.

  14. Radial diffusion of toroidally trapped particles induced by lower hybrid and fast waves

    International Nuclear Information System (INIS)

    Krlin, L.

    1992-10-01

    The interaction of RF field with toroidally trapped particles (bananas) can cause their intrinsic stochastically diffusion both in the configuration and velocity space. In RF heating and/or current drive regimes, RF field can interact with plasma particles and with thermonuclear alpha particles. The aim of this contribution is to give some analytical estimates of induced radial diffusion of alphas and of ions. (author)

  15. Physics of quantum rings

    International Nuclear Information System (INIS)

    Fomin, Vladimir M.

    2014-01-01

    Presents the new class of materials of quantum rings. Provides an elemental basis for low-cost high-performance devices promising for electronics, optoelectronics, spintronics and quantum information processing. Explains the physical properties of quantum rings to cover a gap in scientific literature. Presents the application of most advanced nanoengineering and nanocharacterization techniques. This book deals with a new class of materials, quantum rings. Innovative recent advances in experimental and theoretical physics of quantum rings are based on the most advanced state-of-the-art fabrication and characterization techniques as well as theoretical methods. The experimental efforts allow to obtain a new class of semiconductor quantum rings formed by capping self-organized quantum dots grown by molecular beam epitaxy. Novel optical and magnetic properties of quantum rings are associated with non-trivial topologies at the nanoscale. An adequate characterization of quantum rings is possible on the basis of modern characterization methods of nanostructures, such as Scanning Tunneling Microscopy. A high level of complexity is demonstrated to be needed for a dedicated theoretical model to adequately represent the specific features of quantum rings. The findings presented in this book contribute to develop low-cost high-performance electronic, spintronic, optoelectronic and information processing devices based on quantum rings.

  16. Frequency domain and wavelet analysis of the laser-induced plasma shock waves

    Energy Technology Data Exchange (ETDEWEB)

    Burger, Miloš, E-mail: milosb@ff.bg.ac.rs; Nikolić, Zoran

    2015-08-01

    In addition to optical emission, another trace of interest that laser-induced plasma provides is a form of acoustic feedback. The acoustic emission (AE) signals were obtained using both microphone and piezo transducers. This kind of optoacoustic signals have some distinct features resembling the short, burst-like sounds, that may differ significantly depending mainly on the sample exposed and irradiance applied. Experiments were performed on atmospheric pressure by irradiating various metallic samples. The recorded waveforms were examined and numerically processed. Single-shot acoustical spectra have shown significant potential of providing valuable supplementary information regarding plasma propagation dynamics. Moreover, the general approach suggests the possibility of making the whole measurement system cost-effective and portable. - Highlights: • We report acoustical waveform, and acoustical spectroscopy measurements and analysis in a laser-induced plasma of a different metals in air. • Both piezo and microphone transducer were used. • The acoustical spectra of the emission were obtained when the sample (and plasma) were enclosed in experimental chamber. • The acquired acoustical spectra are time-integrated and the frequency peaks were sharp and relatively isolated. • Finally, both time and frequency resolved wavelet spectrogram present a novel method of observing laser-induced plasma behavior.

  17. Mechanical improvement of metal reinforcement rings for a finite ring-shaped superconducting bulk

    Science.gov (United States)

    Huang, Chen-Guang; Zhou, You-He

    2018-03-01

    As a key technique, reinforcement of type-II superconducting bulks with metal rings can efficiently improve their mechanical properties to enhance the maximum trapped field. In this paper, we study the magnetostrictive and fracture behaviors of a finite superconducting ring bulk reinforced by three typical reinforcing structures composed of metal rings during the magnetizing process by means of the minimization of magnetic energy and the finite element method. After a field-dependent critical current density is adopted, the magnetostriction, pinning-induced stress, and crack tip stress intensity factor are calculated considering the demagnetization effects. The results show that the mechanical properties of the ring bulk are strongly dependent on the reinforcing structure and the material and geometrical parameters of the metal rings. Introducing the metal ring can significantly reduce the hoop stress, and the reduction effect by internal reinforcement is much improved relative to external reinforcement. By comparison, bilateral reinforcement seems to be the best candidate structure. Only when the metal rings have particular Young's modulus and radial thickness will they contribute to improve the mechanical properties the most. In addition, if an edge crack is pre-existing in the ring bulk, the presence of metal rings can effectively avoid crack propagation since it reduces the crack tip stress intensity factor by nearly one order of magnitude.

  18. Estimation of the Effect of Green Water and Bow Flare Slamming on the Wave-Induced Vertical Bending Moment Using Closed-Form Ex-pressions

    DEFF Research Database (Denmark)

    Jensen, Jørgen Juncher; Mansour, A. E.

    2003-01-01

    (1993) and for green water loads the results from Buchner (1995) and Wang et al .(1998) are applied. The phase lag relative to the wave-induced peak and the decay rate are derived mainly from published experimental results, Sikora, (1998). The results are given in closed-form expressions...

  19. Spin wave mode coexistence on the nanoscale: A consequence of the Oersted field induced asymmetric energy landscape

    Science.gov (United States)

    Dumas, Randy

    2014-03-01

    The emerging field of magnonics relies on the systematic generation, manipulation, and detection of spin waves (SWs). Nanocontact spin torque oscillators (NC-STOs) provide an ideal platform to study spin transfer torque induced SW emission. In analogy to two species competing for the same food supply it has been argued that only one SW mode can survive in the steady state. However, as evidenced in many experiments clear signatures of mode-hopping are often observed. Here, we present a third possibility, namely that under the correct experimental conditions, mode coexistencecan be realized in NC-STOs. Micromagnetic simulations reveal that the SW modes are spatially separated under the NC. Mode coexistence is facilitated by the local field asymmetries induced by the spatially inhomogeneous Oersted field in the vicinity of the NC and further promoted by SW localization. Finally, both simulation and experiment reveal a weak low frequency signal exactly at the difference of the mode frequencies, consistent with inter-modulation of two coexistent modes. The Swedish Research Council, The Swedish Foundation for Strategic Research, and the Knut and Alice Wallenberg Foundation are acknowledged. ANL is a US DOE Science Laboratory operated under contract no. DE-AC02-06CH11357 by UChicago Argonne, LLC.

  20. AN N-BODY INTEGRATOR FOR GRAVITATING PLANETARY RINGS, AND THE OUTER EDGE OF SATURN'S B RING

    International Nuclear Information System (INIS)

    Hahn, Joseph M.; Spitale, Joseph N.

    2013-01-01

    A new symplectic N-body integrator is introduced, one designed to calculate the global 360° evolution of a self-gravitating planetary ring that is in orbit about an oblate planet. This freely available code is called epi i nt, and it is distinct from other such codes in its use of streamlines to calculate the effects of ring self-gravity. The great advantage of this approach is that the perturbing forces arise from smooth wires of ring matter rather than discreet particles, so there is very little gravitational scattering and so only a modest number of particles are needed to simulate, say, the scalloped edge of a resonantly confined ring or the propagation of spiral density waves. The code is applied to the outer edge of Saturn's B ring, and a comparison of Cassini measurements of the ring's forced response to simulations of Mimas's resonant perturbations reveals that the B ring's surface density at its outer edge is σ 0 = 195 ± 60 g cm –2 , which, if the same everywhere across the ring, would mean that the B ring's mass is about 90% of Mimas's mass. Cassini observations show that the B ring-edge has several free normal modes, which are long-lived disturbances of the ring-edge that are not driven by any known satellite resonances. Although the mechanism that excites or sustains these normal modes is unknown, we can plant such a disturbance at a simulated ring's edge and find that these modes persist without any damping for more than ∼10 5 orbits or ∼100 yr despite the simulated ring's viscosity ν s = 100 cm 2 s –1 . These simulations also indicate that impulsive disturbances at a ring can excite long-lived normal modes, which suggests that an impact in the recent past by perhaps a cloud of cometary debris might have excited these disturbances, which are quite common to many of Saturn's sharp-edged rings

  1. Long-wave ultraviolet light induces phospholipase activation in cultured human epidermal keratinocytes

    International Nuclear Information System (INIS)

    Hanson, D.; DeLeo, V.

    1990-01-01

    Long wave ultraviolet radiation (UVA) has been shown to play an important role in the overall response of skin to solar radiation, including sunburn, tanning, premature aging, and non-melanoma skin cancer. UVA induction of inflammation in human skin is thought to be mediated by membrane lipid derived products. In order to investigate the mechanism of this response we examined the effect of UVA on phospholipid metabolism of human epidermal keratinocytes in culture. Keratinocytes were grown in serum free low calcium medium. The cells were prelabeled with [3H] arachidonic acid or [3H] choline and irradiated with UVA (Honle 2002-Hg vapor lamp). Identification and quantitation of specific membrane phospholipid-derived components was achieved using high-performance liquid chromatography, paper chromatography, and radioimmunoassay. UVA resulted in a linear dose dependent release of [3H] arachidonic acid into medium between 1 and 20 joule/cm2. This response was inhibited in an oxygen-reduced environment. The radiolabel released was predominantly free arachidonate and cyclooxygenase metabolites. Cyclooxygenase metabolites prostaglandin E2 and prostacyclin derivative, 6-keto-prostaglandin F1a, were stimulated following UVA irradiation, but the lipoxygenase metabolite, leukotriene B was not detected. Maximal release was measured immediately after irradiation and changed little over 24 h post-irradiation. UVA stimulated an increase of [3H] choline metabolites glycerophosphorylcholine and phosphorylcholine in media extracts suggesting UVA activation of phospholipase C and phospholipase A2 or diacylglyceride lipase

  2. Flare-induced MHD disturbances in the corona--Moreton waves and type II shocks

    International Nuclear Information System (INIS)

    Uchida, Y.

    1972-01-01

    The propagation in the corona of the magnetohydrodynamic (MHD) disturbance possibly emitted at the explosive stage in the initial phase of a flare is considered. The behavior of the MHD fast-mode wavefront, whose source is located at the flare, is calculated by using eiconal-characteristic method in the High Altitude Observatory (HAO) realistic models of coronal magnetic field and density for the days of some particular flare events. It is shown as the result that the peculiar behavior of Moreton' s surface wave and the peculiar appearance in the shape and position of the type II burst sources can be consistently understood by considering the refraction, focussing, and fermation of shocks of MHD fast-mode disturbance in the actual distribution of Alfven velocity in the corona. Based on some comparison of the positions of low-Alfven-velocity regions in the corona with observed positions of type II burst sources, it is proposed that the type II burst sources may be identified with such low-Alfven-velocity regions ''illuminated'' by thus enhanced shocks. (U.S.)

  3. Continuous-wave spatial quantum correlations of light induced by multiple scattering

    DEFF Research Database (Denmark)

    Smolka, Stephan; Ott, Johan Raunkjær; Huck, Alexander

    2012-01-01

    and reflectance. Utilizing frequency-resolved quantum noise measurements, we observe that the strength of the spatial quantum correlation function can be controlled by changing the quantum state of an incident bright squeezed-light source. Our results are found to be in excellent agreement with the developed......We present theoretical and experimental results on spatial quantum correlations induced by multiple scattering of nonclassical light. A continuous-mode quantum theory is derived that enables determining the spatial quantum correlation function from the fluctuations of the total transmittance...... theory and form a basis for future research on, e. g., quantum interference of multiple quantum states in a multiple scattering medium....

  4. Long-wave UVA offers partial protection against UVB-induced

    DEFF Research Database (Denmark)

    Skov, L.; Villadsen, L.; Ersbøll, Bjarne Kjær

    2000-01-01

    Ultraviolet-B (UVB, 280–320 nm) interferes with the generation of cell-mediated immunity to contact allergens applied epicutaneously on the irradiated site. To investigate whether pretreatment with UVA-1 (340–400 nm) protects against the UVB-induced immune suppression we sensitized human volunteers...... with diphenylcyclopropenone (DPCP) on normal buttock skin (n=12), on UVB-irradiated buttock skin (n=21), on buttock skin pretreated with UVA-1 (n=12), and on buttock skin pretreated with UVA-1 and thereafter irradiated with UVB (n=22). Sensitization on UVB-irradiated skin reduced the immunization rate to DPCP compared...

  5. Synthesis and Evaluation of Changes Induced by Solvent and Substituent in Electronic Absorption Spectra of New Azo Disperse Dyes Containig Barbiturate Ring

    Directory of Open Access Journals (Sweden)

    Hooshang Hamidian

    2013-01-01

    Full Text Available Six azo disperse dyes were prepared by diazotizing 4-amino hippuric acid and coupled with barbituric acid and 2-thiobarbituric acid. Then, the products were reacted with aromatic aldehyde, sodium acetate, and acetic anhydride, and oxazolone derivatives were formed. Characterization of the dyes was carried out by using UV-Vis, FT-IR, 1H NMR and 13C NMR, and mass spectroscopic techniques. The solvatochromic behavior of azo disperse dyes was evaluated in various solvents. The effects of substituents of aromatic aldehyde, barbiturate, and thiobarbiturate ring on the color of dyes were investigated.

  6. Long-wave-instability-induced pattern formation in an evaporating sessile or pendent liquid layer

    Science.gov (United States)

    Wei, Tao; Duan, Fei

    2018-03-01

    We investigate the nonlinear dynamics and stability of an evaporating liquid layer subject to vapor recoil, capillarity, thermocapillarity, ambient cooling, viscosity, and negative or positive gravity combined with buoyancy effects in the lubrication approximation. Using linear theory, we identify the mechanisms of finite-time rupture, independent of thermocapillarity and direction of gravity, and predict the effective growth rate of an interfacial perturbation which reveals competition among the mechanisms. A stability diagram is predicted for the onset of long-wave (LW) evaporative convection. In the two-dimensional simulation, we observe well-defined capillary ridges on both sides of the valley under positive gravity and main and secondary droplets under negative gravity, while a ridge can be trapped in a large-scale drained region in both cases. Neglecting the other non-Boussinesq effects, buoyancy does not have a significant influence on interfacial evolution and rupture time but makes contributions to the evaporation-driven convection and heat transfer. The average Nusselt number is found to increase with a stronger buoyancy effect. The flow field and interface profile jointly manifest the LW Marangoni-Rayleigh-Bénard convection under positive gravity and the LW Marangoni convection under negative gravity. In the three-dimensional simulation of moderate evaporation with a random perturbation, the rupture patterns are characterized by irregular ridge networks with distinct height scales for positive and negative gravity. A variety of interfacial and internal dynamics are displayed, depending on evaporation conditions, gravity, Marangoni effect, and ambient cooling. Reasonable agreement is found between the present results and the reported experiments and simulations. The concept of dissipative compacton also sheds light on the properties of interfacial fractalization.

  7. Infrared rotational light curves on Jupiter induced by wave activities and cloud patterns andimplications on brown dwarfs

    Science.gov (United States)

    Ge, Huazhi; Zhang, Xi; Fletcher, Leigh; Orton, Glenn S.; Sinclair, James Andrew; Fernandes,, Joshua; Momary, Thomas W.; Warren, Ari; Kasaba, Yasumasa; Sato, Takao M.; Fujiyoshi, Takuya

    2017-10-01

    Many brown dwarfs exhibit infrared rotational light curves with amplitude varying from a fewpercent to twenty percent (Artigau et al. 2009, ApJ, 701, 1534; Radigan et al. 2012, ApJ, 750,105). Recently, it was claimed that weather patterns, especially planetary-scale waves in thebelts and cloud spots, are responsible for the light curves and their evolutions on brown dwarfs(Apai et al. 2017, Science, 357, 683). Here we present a clear relationship between the direct IRemission maps and light curves of Jupiter at multiple wavelengths, which might be similar withthat on cold brown dwarfs. Based on infrared disk maps from Subaru/COMICS and VLT/VISIR,we constructed full maps of Jupiter and rotational light curves at different wavelengths in thethermal infrared. We discovered a strong relationship between the light curves and weatherpatterns on Jupiter. The light curves also exhibit strong multi-bands phase shifts and temporalvariations, similar to that detected on brown dwarfs. Together with the spectra fromTEXES/IRTF, our observations further provide detailed information of the spatial variations oftemperature, ammonia clouds and aerosols in the troposphere of Jupiter (Fletcher et al. 2016,Icarus, 2016 128) and their influences on the shapes of the light curves. We conclude that waveactivities in Jupiter’s belts (Fletcher et al. 2017, GRL, 44, 7140), cloud holes, and long-livedvortices such as the Great Red Spot and ovals control the shapes of IR light curves and multi-wavelength phase shifts on Jupiter. Our finding supports the hypothesis that observed lightcurves on brown dwarfs are induced by planetary-scale waves and cloud spots.

  8. EBT ring physics

    International Nuclear Information System (INIS)

    Uckan, N.A.

    1980-04-01

    This workshop attempted to evaluate the status of the current experimental and theoretical understanding of hot electron ring properties. The dominant physical processes that influence ring formation, scaling, and their optimal behavior are also studied. Separate abstracts were prepared for each of the 27 included papers

  9. Reconfiguration of the multiwavelength operation of optical fiber ring lasers by the modifiable intra-cavity induced losses of an in-fiber tip probe modal Michelson interferometer

    Science.gov (United States)

    Salceda-Delgado, G.; Martinez-Rios, A.; Sierra-Hernandez, J. M.; Rodríguez-Carreón, V. C.; Toral-Acosta, D.; Selvas-Aguilar, R.; Álvarez-Tamayo, R. I.; Castillo-Guzman, A. A.; Rojas-Laguna, R.

    2018-03-01

    A straightforward and versatile method for switching from single to different multiwavelength laser emission in ring cavity fiber lasers is proposed and demonstrated experimentally. The method is based on using the changeable interference pattern from an optical fiber modal Michelson interferometer as a wavelength selective filter into the ring cavity laser. The interferometer is constructed using a bi-conical tapered fiber and a single-mode fiber segment, with these being spliced together to form an optical fiber tip probe. When the length of the single-mode fiber piece is modified, the phase difference between the interfering modes of the interferometer causes a change in the interferometer free spectral range. As a consequence, the laser intra-cavity losses lead to gain competition, which allows us to adjust the number of simultaneously generated laser lines. A multiwavelength reconfiguration of the laser from one up to a maximum of eight emission lines was obtained, with a maximum SNR of around 47 dBm.

  10. Observation of laser-induced elastic waves in agar skin phantoms using a high-speed camera and a laser-beam-deflection probe.

    Science.gov (United States)

    Laloš, Jernej; Gregorčič, Peter; Jezeršek, Matija

    2018-04-01

    We present an optical study of elastic wave propagation inside skin phantoms consisting of agar gel as induced by an Er:YAG (wavelength of 2.94 μm) laser pulse. A laser-beam-deflection probe is used to measure ultrasonic propagation and a high-speed camera is used to record displacements in ablation-induced elastic transients. These measurements are further analyzed with a custom developed image recognition algorithm utilizing the methods of particle image velocimetry and spline interpolation to determine point trajectories, material displacement and strain during the passing of the transients. The results indicate that the ablation-induced elastic waves propagate with a velocity of 1 m/s and amplitudes of 0.1 mm. Compared to them, the measured velocities of ultrasonic waves are much higher, within the range of 1.42-1.51 km/s, while their amplitudes are three orders of magnitude smaller. This proves that the agar gel may be used as a rudimental skin and soft tissue substitute in biomedical research, since its polymeric structure reproduces adequate soft-solid properties and its transparency for visible light makes it convenient to study with optical instruments. The results presented provide an insight into the distribution of laser-induced elastic transients in soft tissue phantoms, while the experimental approach serves as a foundation for further research of laser-induced mechanical effects deeper in the tissue.

  11. Role of misalignment-induced angular chirp in the electro-optic detection of THz waves

    CERN Document Server

    Walsh, D A; Pan, R; Snedden, E W; Graham, D M; Gillespie, W A; Jamison, S P

    2014-01-01

    A general description of electro-optic detection including non-collinear phase matching and finite transverse beam profiles is presented. It is shown theoretically and experimentally that non-collinear phase matching in ZnTe (and similar materials) produces an angular chirp in the chi((2))-generated optical signal. Due to this, in non-collinear THz and probe arrangements such as single-shot THz measurements or through accidental misalignment, measurement of an undistorted THz signal is critically dependent on having sufficient angular acceptance in the optical probe path. The associated spatial walk-off can also preclude the phase retardation approximation used in THz-TDS. The rate of misalignment-induced chirping in commonly used ZnTe and GaP schemes is tabulated, allowing ready analysis of a detection system. (C) 2014 Optical Society of America.

  12. Pressure-induced forces and shear stresses on rubble mound breakwater armour layers in regular waves

    DEFF Research Database (Denmark)

    Jensen, Bjarne; Christensen, Erik Damgaard; Sumer, B. Mutlu

    2014-01-01

    This paper presents the results from an experimental investigation of the pressure-induced forces in the core material below the main armour layer and shear stresses on the armour layer for a porous breakwater structure. Two parallel experiments were performed which both involved pore pressure...... structure i.e. no additional filter layers were applied. For both experiments, high-speed video recordings were synchronised with the pressure measurements for a detailed investigation of the coupling between the run-up and run-down flow processes and the measured pressure variations. Outward directed...... and turbulence measurements showed that the large outward directed pressure gradients in general coincide, both in time and space, with the maximum bed-shear stresses on the armour layer based on the Reynolds-stresses. The bed-shear stresses were found to result in a Shields parameter in the same order...

  13. Polarized gas targets for storage rings

    International Nuclear Information System (INIS)

    Holt, R.J.

    1990-01-01

    It is widely recognized that polarized gas targets in electron storage rings represent a new opportunity for precision nuclear physics studies. New developments in polarized target technology specific to internal applications will be discussed. In particular, polarized gas targets have been used in the VEPP-3 electron ring in Novosibirsk. A simple storage cell was used to increase the total target thickness by a factor of 15 over the simple gas jet target from an atomic beam source. Results from the initial phase of this project will be reported. In addition, the plans for increasing the luminosity by an additional order or magnitude will be presented. The application of this work to polarized hydrogen and deuterium targets for the HERA ring will be noted. The influence of beam-induced depolarization, a phenomena encountered in short-pulse electron storage rings, will be discussed. Finally, the performance tests of laser-driven sources will be presented. 8 refs., 12 figs., 1 tab

  14. On the evolution of vortex rings with swirl

    International Nuclear Information System (INIS)

    Naitoh, Takashi; Okura, Nobuyuki; Gotoh, Toshiyuki; Kato, Yusuke

    2014-01-01

    A laminar vortex ring with swirl, which has the meridional velocity component inside the vortex core, was experimentally generated by the brief fluid ejection from a rotating outlet. The evolution of the vortex ring was investigated with flow visualizations and particle image velocimetry measurements in order to find the influence of swirling flow in particular upon the transition to turbulence. Immediately after the formation of a vortex ring with swirl, a columnar strong vortex along the symmetric axis is observed in all cases of the present experiment. Then the characteristic fluid discharging from a vortex ring with swirl referred to as “peeling off” appears. The amount of discharging fluid due to the “peeling off” increases with the angular velocity of the rotating outlet. We conjectured that the mechanism generating the “peeling off” is related to the columnar strong vortex by close observations of the spatio-temporal development of the vorticity distribution and the cutting 3D images constructed from the successive cross sections of a vortex ring. While a laminar vortex ring without swirl may develop azimuthal waves around its circumference at some later time and the ring structure subsequently breaks, the swirling flow in a vortex ring core reduces the amplification rate of the azimuthal wavy deformation and preserved its ring structure. Then the traveling distance of a vortex ring can be extended using the swirl flow under certain conditions

  15. On the evolution of vortex rings with swirl

    Energy Technology Data Exchange (ETDEWEB)

    Naitoh, Takashi, E-mail: naitoh.takashi@nitech.ac.jp [Department of Engineering Physics, Electronics and Mechanics, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Okura, Nobuyuki, E-mail: ohkura@meijo-u.ac.jp [Department of Vehicle and Mechanical Engineering, Meijo University, 1-501 Shiogamaguchi Tempaku-ku, Nagoya 468-8502 (Japan); Gotoh, Toshiyuki, E-mail: gotoh.toshiyuki@nitech.ac.jp [Department of Scientific and Engineering Simulation, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Kato, Yusuke [Controller Business Unit Engineering Division 1, Engineering Department 3, Denso Wave Incorporated, 1 Yoshiike Kusagi Agui-cho, Chita-gun Aichi 470-2297 (Japan)

    2014-06-15

    A laminar vortex ring with swirl, which has the meridional velocity component inside the vortex core, was experimentally generated by the brief fluid ejection from a rotating outlet. The evolution of the vortex ring was investigated with flow visualizations and particle image velocimetry measurements in order to find the influence of swirling flow in particular upon the transition to turbulence. Immediately after the formation of a vortex ring with swirl, a columnar strong vortex along the symmetric axis is observed in all cases of the present experiment. Then the characteristic fluid discharging from a vortex ring with swirl referred to as “peeling off” appears. The amount of discharging fluid due to the “peeling off” increases with the angular velocity of the rotating outlet. We conjectured that the mechanism generating the “peeling off” is related to the columnar strong vortex by close observations of the spatio-temporal development of the vorticity distribution and the cutting 3D images constructed from the successive cross sections of a vortex ring. While a laminar vortex ring without swirl may develop azimuthal waves around its circumference at some later time and the ring structure subsequently breaks, the swirling flow in a vortex ring core reduces the amplification rate of the azimuthal wavy deformation and preserved its ring structure. Then the traveling distance of a vortex ring can be extended using the swirl flow under certain conditions.

  16. Imidazolopiperazines (IPZ) kill both rings and dormant rings in wild type and K13 artemisinin resistant Plasmodium falciparum in vitro.

    Science.gov (United States)

    Dembele, Laurent; Gupta, Devendra Kumar; Lim, Michelle Yi-Xiu; Ang, Xiaoman; Selva, Jeremy J; Chotivanich, Kesinee; Nguon, Chea; Dondorp, Arjen M; Bonamy, Ghislain M C; Diagana, Thierry T; Bifani, Pablo

    2018-03-12

    Artemisinin (ART) resistance has spread through Southeast Asia, posing serious threat to the control and elimination of malaria. ART resistance has been associated with mutations in the Plasmodium falciparum kelch-13 ( Pfk13 ) propeller domain. Phenotypically, ART resistance is defined as delayed parasite clearance in patients' due to the reduced susceptibility of early ring-stage parasites to the active metabolite of ART dihydroartemisinin (DHA). Early rings can enter a state of quiescence upon DHA exposure and resume growth in its absence. These quiescent rings are referred to as dormant rings or DHA-pretreated rings (called here dormant rings). The imidazolopiperazine (IPZ) is a novel class of antimalarial drugs, which has demonstrated efficacy in early clinical trials. Here, we characterized the stage of action of IPZ GNF179 and evaluated its activity against rings and dormant rings in wild type and ART resistant parasites. Unlike DHA, GNF179 does not induce dormancy. We show that GNF179 is more rapidly cidal against schizonts than ring and trophozoite stages. However, with 12 hours exposure, the compound effectively kills rings and dormant rings of both susceptible and ART resistant parasites within 72 hours. We further demonstrate that in combination with ART, GNF179 effectively prevent recrudescence of dormant rings including those bearing pfk13 propeller mutations. Copyright © 2018 Dembele et al.

  17. Vortices trapped in discrete Josephson rings

    International Nuclear Information System (INIS)

    Van der Zanta, H.S.J.; Orlando, T.P.; Watanabe, Shinya; Strogatz, S.H.

    1994-01-01

    We report the first measurements of current- (I-V) characteristics of discrete rings of Josephson junctions. As I is increased, resonant steps appear in the I-V curve, due to phase-locking between a propagating, trapped vortex and the linear waves excited in its wake. Unexpectedly, the phase velocity of the linear waves, not the group velocity, is the physically important quantity and mode numbers outside the Brillouin zone are relevant. Our measurements show that away from the resonant steps, a single vortex can move in an environment with very little damping, making the discrete one-dimensional ring a well-defined model system for the study of ballistic and quantum vortex experiments. ((orig.))

  18. Vortices trapped in discrete Josephson rings

    Energy Technology Data Exchange (ETDEWEB)

    Van der Zanta, H.S.J. [Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Orlando, T.P. [Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Watanabe, Shinya [Department of Mathematics, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Strogatz, S.H. [Department of Mathematics, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

    1994-12-01

    We report the first measurements of current- (I-V) characteristics of discrete rings of Josephson junctions. As I is increased, resonant steps appear in the I-V curve, due to phase-locking between a propagating, trapped vortex and the linear waves excited in its wake. Unexpectedly, the phase velocity of the linear waves, not the group velocity, is the physically important quantity and mode numbers outside the Brillouin zone are relevant. Our measurements show that away from the resonant steps, a single vortex can move in an environment with very little damping, making the discrete one-dimensional ring a well-defined model system for the study of ballistic and quantum vortex experiments. ((orig.)).

  19. Mechanical seal having a double-tier mating ring

    Science.gov (United States)

    Khonsari, Michael M.; Somanchi, Anoop K.

    2005-09-13

    An apparatus and method to enhance the overall performance of mechanical seals in one of the following ways: by reducing seal face wear, by reducing the contact surface temperature, or by increasing the life span of mechanical seals. The apparatus is a mechanical seal (e.g., single mechanical seals, double mechanical seals, tandem mechanical seals, bellows, pusher mechanical seals, and all types of rotating and reciprocating machines) comprising a rotating ring and a double-tier mating ring. In a preferred embodiment, the double-tier mating ring comprises a first and a second stationary ring that together form an agitation-inducing, guided flow channel to allow for the removal of heat generated at the seal face of the mating ring by channeling a coolant entering the mating ring to a position adjacent to and in close proximity with the interior surface area of the seal face of the mating ring.

  20. Foam on troubled water: Capillary induced finite-time arrest of sloshing waves

    Science.gov (United States)

    Viola, Francesco; Brun, P.-T.; Dollet, Benjamin; Gallaire, François

    2016-09-01

    Interfacial forces exceed gravitational forces on a scale small relative to the capillary length—two millimeters in the case of an air-water interface—and therefore dominate the physics of sub-millimetric systems. They are of paramount importance for various biological taxa and engineering processes where the motion of a liquid meniscus induces a viscous frictional force that exhibits a sublinear dependence in the meniscus velocity, i.e., a power law with an exponent smaller than one. Interested in the fundamental implications of this dependence, we use a liquid-foam sloshing system as a prototype to exacerbate the effect of sublinear friction on the macroscopic mechanics of multi-phase flows. In contrast to classical theory, we uncover the existence of a finite-time singularity in our system yielding the arrest of the fluid's oscillations. We propose a minimal theoretical framework to capture this effect, thereby amending the paradigmatic damped harmonic oscillator model. Our results suggest that, although often not considered at the macroscale, sublinear capillary forces govern the friction at liquid-solid and liquid-liquid interfaces.